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Sample records for optic thermal health

  1. Fiber Optic Thermal Health Monitoring of Composites

    NASA Technical Reports Server (NTRS)

    Wu, Meng-Chou; Winfree, William P.; Moore, Jason P.

    2010-01-01

    A recently developed technique is presented for thermographic detection of flaws in composite materials by performing temperature measurements with fiber optic Bragg gratings. Individual optical fibers with multiple Bragg gratings employed as surface temperature sensors were bonded to the surfaces of composites with subsurface defects. The investigated structures included a 10-ply composite specimen with subsurface delaminations of various sizes and depths. 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 data obtained from grating sensors were analyzed with thermal modeling techniques of conventional thermography to reveal particular characteristics of the interested areas. Results were compared with the calculations using numerical simulation techniques. Methods and limitations for performing in-situ structural health monitoring are discussed.

  2. 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.

  3. Thermal lensing in optical fibers.

    PubMed

    Dong, Liang

    2016-08-22

    Average powers from fiber lasers have reached the point that a quantitative understanding of thermal lensing and its impact on transverse mode instability is becoming critical. Although thermal lensing is well known qualitatively, there is a general lack of a simple method for quantitative analysis. In this work, we first conduct a study of thermal lensing in optical fibers based on a perturbation technique. The perturbation technique becomes increasingly inaccurate as thermal lensing gets stronger. It, however, provides a basis for determining a normalization factor to use in a more accurate numerical study. A simple thermal lensing threshold condition is developed. The impact of thermal lensing on transverse mode instability is also studied.

  4. Fiber Optic Thermal Detection of Composite Delaminations

    NASA Technical Reports Server (NTRS)

    Wu, Meng-Chou; Winfree, William P.

    2011-01-01

    A recently developed technique is presented for thermographic detection of delaminations in composites by performing temperature measurements with fiber optic Bragg gratings. A single optical fiber with multiple Bragg gratings employed as surface temperature sensors was bonded to the surface of a composite with subsurface defects. The investigated structure was a 10-ply composite specimen with prefabricated delaminations of various sizes and depths. 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 data obtained from grating sensors were analyzed with thermal modeling techniques of conventional thermography to reveal particular characteristics of the interested areas. Results were compared and found to be consistent with the calculations using numerical simulation techniques. Also discussed are methods including various heating sources and patterns, and their limitations for performing in-situ structural health monitoring.

  5. Optical Diagnostics for Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Eldridge, J. I.; Spuckler, C. M.; Bencic, T. J.; Martin, R. E.

    2004-01-01

    The translucent nature of ceramic oxide thermal barrier coatings (TBCs) provides an opportunity to employ optical probes to monitor temperature gradients and buried damage propagation within the coating. An important advantage of noncontact optical diagnostics is that they are amendable to health monitoring of TBCs in service. In this paper, two optical diagnostic approaches, operating in different wavelength regimes, are discussed. The first approach is the use of mid-infrared reflectance (MIR) to monitor the progression of TBC delamination produced by thermal cycling. This approach takes advantage of the maximum transparency of the TBCs at mid-infrared wavelengths, in particular, between 3 and 5 microns. Recent progress in extending the MIR method to a more practical visual inspection tool will be presented. A second approach, using visible wavelengths, is the embedding of thermographic phosphors within the TBC to add sensing functions to the coating that can provide depth-selective information about temperature gradients and TBC integrity. Emphasis will be given to the use of fluorescence decay time measurements to provide temperature readings from a thermographic phosphor layer residing beneath the TBC.

  6. Thermal strain analysis of optic fiber sensors.

    PubMed

    Her, Shiuh-Chuan; Huang, Chih-Ying

    2013-01-31

    An optical fiber sensor surface bonded onto a host structure and subjected to a temperature change is analytically studied in this work. The analysis is developed in order to assess the thermal behavior of an optical fiber sensor designed for measuring the strain in the host structure. For a surface bonded optical fiber sensor, the measuring sensitivity is strongly dependent on the bonding characteristics which include the protective coating, adhesive layer and the bonding length. Thermal stresses can be generated due to a mismatch of thermal expansion coefficients between the optical fiber and host structure. The optical fiber thermal strain induced by the host structure is transferred via the adhesive layer and protective coating. In this investigation, an analytical expression of the thermal strain and stress in the optical fiber is presented. The theoretical predictions are validated using the finite element method. Numerical results show that the thermal strain and stress are linearly dependent on the difference in thermal expansion coefficients between the optical fiber and host structure and independent of the thermal expansion coefficients of the adhesive and coating.

  7. Analysis of thermally loaded transmissive optical elements

    NASA Astrophysics Data System (ADS)

    Michels, Gregory J.; Genberg, Victor L.

    2013-09-01

    The performance metrics of many optical systems are affected by temperature changes in the system through different physical phenomena. Temperature changes cause materials to expand and contract causing deformations of optical components. The resulting stress states in transmissive optics can cause refractive changes that can affect optical performance. In addition, the temperature changes themselves can cause changes in the refractive properties of transmissive optics. Complex distributions of refractive indices that relate to the thermal profile, the thermo-optic refractive index profile, within the optical media can be predicted by the finite element method. One current technique for representing such refractive index profiles is through the generation of optical path difference (OPD) maps by integration along integration paths. While computationally efficient, this method has limitations in its ability to represent the effect of the index changes for rays associated with multiple field points and multiple wavelengths. A more complete representation of the thermo-optic refractive index profile may be passed to the optical analysis software through the use of a user defined gradient index material. The interface consists of a dynamic link library (DLL) which supplies indices of refraction to a user defined gradient index lens as ray tracing calculations are being performed. The DLL obtains its refractive index description from a database derived from the thermal analysis of the optics. This process allows optical analysis software to perform accurate ray tracing for an arbitrary refractive index profile induced by changes in temperature.

  8. Stimulated thermal Rayleigh scattering in optical fibers.

    PubMed

    Dong, Liang

    2013-02-11

    Recently, mode instability was observed in optical fiber lasers at high powers, severely limiting power scaling for single-mode outputs. Some progress has been made towards understanding the underlying physics. A thorough understanding of the effect is critical for continued progress of this very important technology area. Mode instability in optical fibers is, in fact, a manifestation of stimulated thermal Rayleigh scattering. In this work, a quasi-closed-form solution for the nonlinear coupling coefficient is found for stimulated thermal Rayleigh scattering in optical fibers. The results help to significantly improve understanding of mode instability.

  9. Thermal/Optical analysis of optical system of star tracker

    NASA Astrophysics Data System (ADS)

    Lu, Si-yu; Huang, Yi-fan

    2011-08-01

    Spacecraft would be expected to encounter diverse extreme environmental (EE) conditions throughout their mission phases. These EE conditions are often coupled. Star tracker is a high accurate 3-axis attitude measuring instrument used in various spacecrafts. In this paper, an effective scheme to the thermal/optical analysis in optical system of star sensor was described and the concept of thermal optical analysis of star tracker optical system was introduced in detail. Using finite element analysis (FEA) and ray tracing, we can study the relationship of optical properties of optical systems and optical system's temperature distribution . A lens system configuration having six uncemented elements was discussed. The lens system was a 56mm EFL, which was different from common lens used in imaging system that this lens system was required to have a high resolving power in design thoughts. It was designed to determine the attitude of space platform by detecting and mapping the geometric pattern of stars. Based on this system, the FEA models of the optical system were established for temperature distribution calculation and for thermal-elastic structural deformation analysis respectively. Using the models, the steady-state temperature distributions of the tracker were simulated. The rigid body displacements of the optical components under homogeneous temperature changes and certain temperature distributions were derived out. It is convenient to use Zernike polynomials as the data transmission between optical and structural analysis programs. Here, Zernike polynomials and their fitting method are used as an example to determine the thermal induced optical degradations of the optical system.

  10. ANALYSIS OF CARBONACEOUS AEROSOLS USING THE THERMAL OPTICAL TRANSMITTANCE AND THERMAL OPTICAL REFLECTANCE METHODS

    EPA Science Inventory

    Carbonaceous particulate typically represents a large fraction of PM2.5 (20 - 40%). Two primary techniques presently used for the analysis of particulate carbon are Thermal Optical Transmission (TOT - NIOSH Method 5040) and Thermal Optical Reflectance (TOR). These two methods b...

  11. Structural-Thermal-Optical-Performance (STOP) Analysis

    NASA Technical Reports Server (NTRS)

    Bolognese, Jeffrey; Irish, Sandra

    2015-01-01

    The presentation will be given at the 26th Annual Thermal Fluids Analysis Workshop (TFAWS 2015) hosted by the Goddard Spaceflight Center (GSFC) Thermal Engineering Branch (Code 545). A STOP analysis is a multidiscipline analysis, consisting of Structural, Thermal and Optical Performance Analyses, that is performed for all space flight instruments and satellites. This course will explain the different parts of performing this analysis. The student will learn how to effectively interact with each discipline in order to accurately obtain the system analysis results.

  12. Thermal neutron dosimetry by optical rotation

    NASA Astrophysics Data System (ADS)

    Venkataramani, R.

    Arabinose and sucrose solutions containing boric acid were irradiated in reactor-pile and the enhanced decrease in optical rotation in the presence of boric acid over that in its absence was correlated to integral thermal neutron flux. The induced activity in the sample and the level of dose on sample containers were evaluated. Post-irradiation effect on optical activity was followed and the equation connecting optical activity and dose was found to be linear in the range of 9×10 14-216× 10 14 neutrons in the case of arabinose system.

  13. Optical testing cryogenic thermal vacuum facility

    NASA Technical Reports Server (NTRS)

    Dohogne, Patrick W.; Carpenter, Warren A.

    1990-01-01

    The construction of a turnkey cryogenic vacuum test facility was recently completed. The facility will be used to measure and record the surface profile of large diameter and 540 kg optics under simulated space conditions. The vacuum test chamber is a vertical stainless steel cylinder with a 3.5 diameter and a 7 m tangent length. The chamber was designed to maximize optical testing quality by minimizing the vibrations between the laser interferometer and the test specimen. This was accomplished by designing the chamber for a high natural frequency and vibration isolating the chamber. An optical test specimen is mounted on a movable presentation stage. During thermal vacuum testing, the specimen may be positioned to + or - 0.00025 cm accuracy with a fine adjustment mechanism. The chamber is evacuated by a close coupled Roots-type blower and rotary vane pump package and two cryopumps. The chamber is equipped with an optically dense gaseous nitrogen cooled thermal shroud. The thermal shroud is used to cool or warm the optical test specimen at a controlled rate. A control system is provided to automatically evacuate the chamber and cooldown the test specimen to the selected control temperature.

  14. Thermal and optical characterization for POLARBEAR-2 optical system

    NASA Astrophysics Data System (ADS)

    Inoue, Y.; Stebor, N.; Ade, P. A. R.; Akiba, Y.; Arnold, K.; Anthony, A. E.; Atlas, M.; Barron, D.; Bender, A.; Boettger, D.; Borrilll, J.; Chapman, S.; Chinone, Y.; Cukierman, A.; Dobbs, M.; Elleflot, T.; Errard, J.; Fabbian, G.; Feng, C.; Gilbert, A.; Halverson, N. W.; Hasegawa, M.; Hattori, K.; Hazumi, M.; Holzapfel, W. L.; Hori, Y.; Jaehnig, G. C.; Jaffe, A. H.; Katayama, N.; Keating, B.; Kermish, Z.; Keskitalo, Reijo; Kisner, T.; Le Jeune, M.; Lee, A. T.; Leitch, E. M.; Linder, E.; Matsuda, F.; Matsumura, T.; Meng, X.; Morii, H.; Myers, M. J.; Navaroli, M.; Nishino, H.; Okamura, T.; Paar, H.; Peloton, J.; Poletti, D.; Rebeiz, G.; Reichardt, C. L.; Richards, P. L.; Ross, C.; Schenck, D. E.; Sherwin, B. D.; Siritanasak, P.; Smecher, G.; Sholl, M.; Steinbach, B.; Stompor, R.; Suzuki, A.; Suzuki, J.; Takada, S.; Takakura, S.; Tomaru, T.; Wilson, B.; Yadav, A.; Yamaguchi, H.; Zahn, O.

    2014-08-01

    POLARBEAR-2 (PB-2) is a cosmic microwave background (CMB) polarization experiment for B-mode detection. The PB-2 receiver has a large focal plane and aperture that consists of 7588 transition edge sensor (TES) bolometers at 250 mK. The receiver consists of the optical cryostat housing reimaging lenses and infrared filters, and the detector cryostat housing TES bolometers. The large focal plane places substantial requirements on the thermal design of the optical elements at the 4K, 50K, and 300K stages. Infrared filters and lenses inside the optical cryostat are made of alumina for this purpose. We measure basic properties of alumina, such as the index of refraction, loss tangent and thermal conductivity. All results meet our requirements. We also optically characterize filters and lenses made of alumina. Finally, we perform a cooling test of the entire optical cryostat. All measured temperature values satisfy our requirements. In particular, the temperature rise between the center and edge of the alumina infrared filter at 50 K is only 2:0 ± 1:4 K. Based on the measurements, we estimate the incident power to each thermal stage.

  15. Thermal motion of the STIS optical bench

    NASA Technical Reports Server (NTRS)

    Gull, Theodore R.; Taylor, Mary Jane; Shaw, Richard; Robinson, Richard; Hill, Robert S.

    1997-01-01

    Various tests have been done of the Space Telescope Imaging Spectrograph (STIS) using internal wavecals to measure thermal motion of the spectral format on the detectors. In most cases, the spectral format moves less than the specification not to exceed 0.2 pixels per hour. Primary causes of the motion are (1) changes to the thermal design dictated by the warmer Aft Shroud environment and (2) on-orbit power cycling of Multi-Anode Microchannel Arrays (MAMA) electronics to minimize the effects of radiation hits on the MAMA detectors. The rear portion of the STIS optical bench is too warm to be held at a constant temperature by internal heaters. Electronics swing in temperature with an orbital and daily frequency. The thermal drift of the optical formats is not negligible, but is well behaved in most circumstances. The observer is advised to examine the trade-off between the most accurate wavelengths with best spectral/spatial resolutions versus increased overheads that directly affect the observing times. A long term concern is that the Aft Shroud thermal environment is predicted to heat up as much as one Centigrade degree per year. Progressively more of the bench would move out of thermal control. Thus the external cooler for STIS, being considered for the Third Servicing Mission is of major importance to the long term operation of STIS.

  16. Thermal limiting effects in optical plasmonic waveguides

    NASA Astrophysics Data System (ADS)

    Ershov, A. E.; Gerasimov, V. S.; Gavrilyuk, A. P.; Karpov, S. V.; Zakomirnyi, V. I.; Rasskazov, I. L.; Polyutov, S. P.

    2017-04-01

    We have studied thermal effects occurring during excitation of optical plasmonic waveguide (OPW) in the form of linear chain of spherical Ag nanoparticles by pulsed laser radiation. It was shown that heating and subsequent melting of the first irradiated particle in a chain can significantly deteriorate the transmission efficiency of OPW that is the crucial and limiting factor and continuous operation of OPW requires cooling devices. This effect is caused by suppression of particle's surface plasmon resonance due to reaching the melting point temperature. We have determined optimal excitation parameters which do not significantly affect the transmission efficiency of OPW.

  17. Athermalization and thermal characteristics of multilayer diffractive optical elements.

    PubMed

    Wang, Ju; Xue, Changxi

    2015-11-20

    A mathematical model to analyze the thermal characteristics of the multilayer diffractive optical elements (MLDOEs) is presented with consideration of the thermal characteristics for the refractive optical elements and single-layer diffractive optical elements. The analysis process of athermalization for MLDOEs by using the opto-thermal expansion coefficient of optical materials is given. Meanwhile, the microstructure heights of surface relief MLDOEs, the optical path difference, and the polychromatic integral diffraction efficiency with the ambient temperature changed are analyzed. The analysis results can be used to guide an athermalization design for the hybrid refractive-diffractive optical systems with MLDOEs.

  18. Thermal conductivities of thin, sputtered optical films

    SciTech Connect

    Henager, C.H. Jr.; Pawlewicz, W.T.

    1991-05-01

    The normal component of the thin film thermal conductivity has been measured for the first time for several advanced sputtered optical materials. Included are data for single layers of boron nitride (BN), aluminum nitride (AIN), silicon aluminum nitride (Si-Al-N), silicon aluminum oxynitride (Si-Al-O-N), silicon carbide (SiC), and for dielectric-enhanced metal reflectors of the form Al(SiO{sub 2}/Si{sub 3}N{sub 4}){sup n} and Al(Al{sub 2}O{sub 3}/AIN){sup n}. Sputtered films of more conventional materials like SiO{sub 2}, Al{sub 2}O{sub 3}, Ta{sub 2}O{sub 5}, Ti, and Si have also been measured. The data show that thin film thermal conductivities are typically 10 to 100 times lower than conductivities for the same materials in bulk form. Structural disorder in the amorphous or very fine-grained films appears to account for most of the conductivity difference. Conclusive evidence for a film/substrate interface contribution is presented.

  19. 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.

  20. Optical Diagnostics of Thermal Barrier Coatings

    NASA Astrophysics Data System (ADS)

    Majewski, Mark Steven

    The high temperature properties of ceramic materials make them suitable for the extreme environments of gas combustion powered turbines. They are instrumental in providing thermal insulation for the metallic turbine components from the combustion products. Also, the addition of specific rare earth elements to ceramics creates materials with temperature diagnostic applications. Laser based methods have been applied to these ceramic coatings to predict their remaining thermal insulation service life and to explore their high temperature diagnostic capabilities. A method for cleaning thermal barrier coatings (TBCs) contaminated during engine operation has been developed using laser ablation. Surface contamination on the turbine blades hinders nondestructive remaining life prediction using photo luminescence piezospectroscopy (PLPS). Real time monitoring of the removed material is employed to prevent damage to the underlying coating. This method relies on laser induced breakdown spectroscopy (LIBS) to compute the cross correlation coefficient between the spectral emissions of a sample TBC that is contaminated and a reference clean TBC. It is possible to remove targeted contaminants and cease ablation when the top surface of the TBC has been reached. In collaboration with this work, Kelley's thesis [1] presents microscopy images and PLPS measurements indicating the integrity of the TBC has been maintained during the removal of surface contaminants. Thermographic phosphors (TGP) have optical emission properties when excited by a laser that are temperature dependent. These spectral and temporal properties have been investigated and utilized for temperature measurement schemes by many previous researchers. The compounds presented in this dissertation consist of various rare earth (Lanthanide) elements doped into a host crystal lattice. As the temperature of the lattice changes, both the time scale for vibrational quenching and the distribution of energy among atomic energy

  1. Thermal and optical characterization of the calcium phosphate biomaterial hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Bento, A. C.; Almond, D. P.; Brown, S. R.; Turner, I. G.

    1996-05-01

    Thermal wave interferometry (TWI) has been used to measure the thermophysical properties of hydroxyapatite (HA) coatings, prepared by the plasma-spraying process on titanium alloy substrates. The properties measured were thermal diffusivity, thermal conductivity, thermal effusivity, and volumetric heat capacity and the optical absorption coefficient. The thermal conductivity obtained was found to be of similar magnitude to that of human tooth enamel. The results presented confirm the usefulness of TWI as a nondestructive technique for the characterization of plasma-sprayed HA coatings.

  2. Fiber Optic Sensors for Health Monitoring of Morphing Aircraft

    NASA Technical Reports Server (NTRS)

    Brown, Timothy; Wood, Karen; Childers, Brooks; Cano, Roberto; Jensen, Brian; Rogowski, Robert

    2001-01-01

    Fiber optic sensors are being developed for health monitoring of future aircraft. Aircraft health monitoring involves the use of strain, temperature, vibration and chemical sensors. These sensors will measure load and vibration signatures that will be used to infer structural integrity. Sine the aircraft morphing program assumes that future aircraft will be aerodynamically reconfigurable there is also a requirement for pressure, flow and shape sensors. In some cases a single fiber may be used for measuring several different parameters. The objective of the current program is to develop techniques for using optical fibers to monitor composite cure in real time during manufacture and to monitor in-service structural integrity of the composite structure. Graphite-epoxy panels were fabricated with integrated optical fibers of various types. The panels were mechanically and thermally tested to evaluate composite strength and sensor durability. Finally the performance of the fiber optic sensors was determined. Experimental results are presented evaluating the performance of embedded and surface mounted optical fibers for measuring strain, temperature and chemical composition. The performance of the fiber optic sensors was determined by direct comparison with results from more conventional instrumentation. The facilities for fabricating optical fiber and associated sensors and methods of demodulating Bragg gratings for strain measurement will be described.

  3. Thermal indicating paints for ammunition health monitoring

    NASA Astrophysics Data System (ADS)

    Zunino, James L., III; Iqbal, Zafar

    2010-04-01

    Thermochromic semiconductive polymers that change color in response to external stimuli, such as heat and radiation, can be utilized to monitor the temperature range and elapsed time profiles of stored and prepositioned munitions. These polymers are being tailored to create paints and coatings that will alert Army logistic staff of dangerous temperature exposures. Irreversible indication via color change in multiple thermal bands, 145 F - 164 F (63o-73°C), 165 F - 184 F (74° - 84° C) and over 185 F (>85°C) are possible with these thermochromic polymers. The resulting active coating can be visually inspected to determine if safe temperatures were exceeded. More detailed information, including cumulative time of exposure in certain temperature bands through changes in optical chromaticity describing the vividness or dullness of a color, can be assessed using a hand-held optical densitometer.

  4. Thermal sensitivity of tellurite and germanate optical fibers.

    PubMed

    Li, Hongxia; Lousteau, Joris; Macpherson, William N; Jiang, Xin; Bookey, Henry T; Barton, James S; Jha, Animesh; Kar, Ajoy K

    2007-07-09

    The temperature coefficients of optical phase have been measured at 1536 nm wavelength for short fiber Fabry-Perot cavities of tellurite and germanate glass fibers spliced to silica fiber. The results are consistent with the thermal expansion and thermo-optic coefficients of the bulk glasses.

  5. Feedback control of optical beam spatial profiles using thermal lensing.

    PubMed

    Liu, Zhanwei; Fulda, Paul; Arain, Muzammil A; Williams, Luke; Mueller, Guido; Tanner, D B; Reitze, D H

    2013-09-10

    A method for active control of the spatial profile of a laser beam using adaptive thermal lensing is described. A segmented electrical heater was used to generate thermal gradients across a transmissive optical element, resulting in a controllable thermal lens. The segmented heater also allows the generation of cylindrical lenses, and provides the capability to steer the beam in both horizontal and vertical planes. Using this device as an actuator, a feedback control loop was developed to stabilize the beam size and position.

  6. Thermal Infrared Imaging Spectrometer - An advanced optics technology instrument

    NASA Technical Reports Server (NTRS)

    Mahoney, Colin; Labaw, Clayton; Sobel, Harold; Kahle, Anne

    1990-01-01

    Through the use of a special optical filter, the Thermal Infrared Imaging Spectrometer, an airborne multispectral IR imaging instrument operating in the thermal emission region (7.5-14 microns), will achieve signal-to-noise ratios greater than 600 with ambient temperature optics. This instrument will be used to do compositional surface mapping of the terrain, and will refine the ability to categorize rock families and types by providing much higher spectral resolution in the emission region than was previously available. Details of the optical system, the detector, the cooler system, and the support electronics are described.

  7. Optical Diagnostics for High-Temperature Thermal Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Eldridge, Jeffrey I.

    2009-01-01

    Thermal barrier coatings (TBCs) are typically composed of translucent ceramic oxides that provide thermal protection for metallic components exposed to high-temperature environments, such as in jet turbine engines. Taking advantage of the translucent nature of TBCs, optical diagnostics have been developed that can provide an informed assessment of TBC health that will allow mitigating action to be taken before TBC degradation threatens performance or safety. In particular, rare-earth-doped luminescent sublayers have been integrated into the TBC structure to produce luminescence that monitors TBC erosion, delamination, and temperature gradients. Erosion monitoring of TBC-coated specimens is demonstrated by utilizing visible luminescence that is excited from a sublayer that is exposed by erosion. TBC delamination monitoring is achieved in TBCs with a base rare-earth-doped luminescent sublayer by the reflectance-enhanced increase in luminescence produced in regions containing buried delamination cracks. TBC temperature monitoring is demonstrated using the temperature-dependent decay time for luminescence originating from the specific coating depth associated with a rare-earth-doped luminescent sublayer. The design and implementation of these TBCs with integrated luminescent sublayers is discussed, including co-doping strategies to produce more penetrating near-infrared luminescence. It is demonstrated that integration of the rare-earth-doped sublayers is achieved with no reduction in TBC life. In addition, results for multilayer TBCs designed to also perform as radiation barriers are also presented.

  8. Thermal links for the implementation of an optical refrigerator

    SciTech Connect

    Epsteiin, Richard I; Greenfield, Scott R; Parker, John; Mar, David; Von Der Porten, Steven; Hankinson, John; Byram, Kevin; Lee, Chris; Mayeda, Kai; Haskell, Richard; Yang, Qimin

    2008-01-01

    Optical refrigeration has been demonstrated by several groups of researchers, but the cooling elements have not been thermally linked to realistic heat loads in ways that achieve the desired temperatures. The ideal thermal link will have minimal surface area, provide complete optical isolation for the load, and possess high thermal conductivity. We have designed thermal links that minimize the absorption of fluoresced photons by the heat load using multiple mirrors and geometric shapes including a hemisphere, a kinked waveguide, and a tapered waveguide. While total link performance is dependent on additional factors, we have observed net transmission of photons with the tapered link as low as 0.04%. Our optical tests have been performed with a surrogate source that operates at 625 nm and mimics the angular distribution of light emitted from the cooling element of the Los Alamos solid state optical refrigerator. We have confirmed the optical performance of our various link geometries with computer simulations using CODE V optical modeling software. In addition we have used the thermal modeling tool in COMSOL MULTIPHYSICS to investigate other heating factors that affect the thermal performance of the optical refrigerator. Assuming an ideal cooling element and a nonabsorptive dielectric trapping mirror, the three dominant heating factors are (1) absorption of fluoresced photons transmitted through the thermal link, (2) blackbody radiation from the surrounding environment, and (3) conductive heat transfer through mechanical supports. Modeling results show that a 1 cm{sup 3} load can be chilled to 107 K with a 100 W pump laser. We have used the simulated steady-state cooling temperatures of the heat load to compare link designs and system configurations.

  9. Thermal links for the implementation of an optical refrigerator

    NASA Astrophysics Data System (ADS)

    Parker, John; Mar, David; Von der Porten, Steven; Hankinson, John; Byram, Kevin; Lee, Chris; Mayeda, Michael K.; Haskell, Richard; Yang, Qimin; Greenfield, Scott; Epstein, Richard

    2009-01-01

    Optical refrigeration has been demonstrated by several groups of researchers, but the cooling elements have not been thermally linked to realistic heat loads in ways that achieve the desired temperatures. The ideal thermal link will have minimal surface area, provide complete optical isolation for the load, and possess high thermal conductivity. We have designed thermal links that minimize the absorption of fluoresced photons by the heat load using multiple mirrors and geometric shapes including a hemisphere, a kinked waveguide, and a tapered waveguide. While total link performance is dependent on additional factors, we have observed net transmission of photons with the tapered link as low as 0.04%. Our optical tests have been performed with a surrogate source that operates at 625 nm and mimics the angular distribution of light emitted from the cooling element of the Los Alamos solid state optical refrigerator. We have confirmed the optical performance of our various link geometries with computer simulations using CODE V optical modeling software. In addition we have used the thermal modeling tool in COMSOL MULTIPHYSICS to investigate other heating factors that affect the thermal performance of the optical refrigerator. Assuming an ideal cooling element and a nonabsorptive dielectric trapping mirror, the three dominant heating factors are (1) absorption of fluoresced photons transmitted through the thermal link, (2) blackbody radiation from the surrounding environment, and (3) conductive heat transfer through mechanical supports. Modeling results show that a 1 cm3 load can be chilled to 107 K with a 100 W pump laser. We have used the simulated steady-state cooling temperatures of the heat load to compare link designs and system configurations.

  10. Advanced NDE research in electromagnetic, thermal, and coherent optics

    NASA Astrophysics Data System (ADS)

    Skinner, S. Ballou

    1992-09-01

    A new inspection technology called magneto-optic/eddy current imaging was investigated. The magneto-optic imager makes readily visible irregularities and inconsistencies in airframe components. Other research observed in electromagnetics included (1) disbond detection via resonant modal analysis; (2) AC magnetic field frequency dependence of magnetoacoustic emission; and (3) multi-view magneto-optic imaging. Research observed in the thermal group included (1) thermographic detection and characterization of corrosion in aircraft aluminum; (2) a multipurpose infrared imaging system for thermoelastic stress detection; (3) thermal diffusivity imaging of stress induced damage in composites; and (4) detection and measurement of ice formation on the space shuttle main fuel tank. Research observed in the optics group included advancements in optical nondestructive evaluation (NDE).

  11. Thermal/structural/optical integrated design for optical sensor mounted on unmanned aerial vehicle

    NASA Astrophysics Data System (ADS)

    Zhang, Gaopeng; Yang, Hongtao; Mei, Chao; Wu, Dengshan; Shi, Kui

    2016-01-01

    With the rapid development of science and technology and the promotion of many local wars in the world, altitude optical sensor mounted on unmanned aerial vehicle is more widely applied in the airborne remote sensing, measurement and detection. In order to obtain high quality image of the aero optical remote sensor, it is important to analysis its thermal-optical performance on the condition of high speed and high altitude. Especially for the key imaging assembly, such as optical window, the temperature variation and temperature gradient can result in defocus and aberrations in optical system, which will lead to the poor quality image. In order to improve the optical performance of a high speed aerial camera optical window, the thermal/structural/optical integrated design method is developed. Firstly, the flight environment of optical window is analyzed. Based on the theory of aerodynamics and heat transfer, the convection heat transfer coefficient is calculated. The temperature distributing of optical window is simulated by the finite element analysis software. The maximum difference in temperature of the inside and outside of optical window is obtained. Then the deformation of optical window under the boundary condition of the maximum difference in temperature is calculated. The optical window surface deformation is fitted in Zernike polynomial as the interface, the calculated Zernike fitting coefficients is brought in and analyzed by CodeV Optical Software. At last, the transfer function diagrams of the optical system on temperature field are comparatively analyzed. By comparing and analyzing the result, it can be obtained that the optical path difference caused by thermal deformation of the optical window is 138.2 nm, which is under PV ≤1 4λ . The above study can be used as an important reference for other optical window designs.

  12. Use of thermal sieve to allow optical testing of cryogenic optical systems.

    PubMed

    Kim, Dae Wook; Cai, Wenrui; Burge, James H

    2012-05-21

    Full aperture testing of large cryogenic optical systems has been impractical due to the difficulty of operating a large collimator at cryogenic temperatures. The Thermal Sieve solves this problem by acting as a thermal barrier between an ambient temperature collimator and the cryogenic system under test. The Thermal Sieve uses a set of thermally controlled baffles with array of holes that are lined up to pass the light from the collimator without degrading the wavefront, while attenuating the thermal background by nearly 4 orders of magnitude. This paper provides the theory behind the Thermal Sieve system, evaluates the optimization for its optical and thermal performance, and presents the design and analysis for a specific system.

  13. Thermal stability of intralipid optical phantoms.

    PubMed

    Rowe, Philip I; Künnemeyer, Rainer; McGlone, Andrew; Talele, Sadhana; Martinsen, Paul; Oliver, Richard

    2013-08-01

    We investigated the stability of light transmission through Intralipid-based optical phantoms in the wavelength range of 400-950 nm at temperatures between 35 and 70 °C. Optical phantoms are materials commonly used to simulate the light scattering and absorption properties of biological materials. These simulations require the phantom to be optically stable. We demonstrate that the scattering properties of Intralipid remain stable at higher temperatures, varying less than 0.5%. We also present results that show this is not the case for absorption below 700 nm at 35 and 70 °C, with greater instability at 70 °C. For example, at 500 nm, the light intensity transmitted through 15 mm of Intralipid dropped 39% over 12 h. We demonstrate that oxidation of fatty acids in Intralipid could account for this effect and show, by flushing the system continuously with nitrogen gas, the instability is reduced.

  14. Optimal design of a thermally stable composite optical bench

    NASA Technical Reports Server (NTRS)

    Gray, C. E., Jr.

    1985-01-01

    The Lidar Atmospheric Sensing Experiment will be performed aboard an ER-2 aircraft; the lidar system used will be mounted on a lightweight, thermally stable graphite/epoxy optical bench whose design is presently subjected to analytical study and experimental validation. Attention is given to analytical methods for the selection of such expected laminate properties as the thermal expansion coefficient, the apparent in-plane moduli, and ultimate strength. For a symmetric laminate in which one of the lamina angles remains variable, an optimal lamina angle is selected to produce a design laminate with a near-zero coefficient of thermal expansion. Finite elements are used to model the structural concept of the design, with a view to the optical bench's thermal structural response as well as the determination of the degree of success in meeting the experiment's alignment tolerances.

  15. Dynamic nonlinear thermal optical effects in coupled ring resonators

    NASA Astrophysics Data System (ADS)

    Huang, Chenguang; Fan, Jiahua; Zhu, Lin

    2012-09-01

    We investigate the dynamic nonlinear thermal optical effects in a photonic system of two coupled ring resonators. A bus waveguide is used to couple light in and out of one of the coupled resonators. Based on the coupling from the bus to the resonator, the coupling between the resonators and the intrinsic loss of each individual resonator, the system transmission spectrum can be classified by three different categories: coupled-resonator-induced absorption, coupled-resonator-induced transparency and over coupled resonance splitting. Dynamic thermal optical effects due to linear absorption have been analyzed for each category as a function of the input power. The heat power in each resonator determines the thermal dynamics in this coupled resonator system. Multiple "shark fins" and power competition between resonators can be foreseen. Also, the nonlinear absorption induced thermal effects have been discussed.

  16. Optical characterization of thermal properties of biological tissue

    NASA Astrophysics Data System (ADS)

    Gutierrez-Arroyo, A.; Sánchez Pérez, C.; Alemán-García, N.; Piña-Barba, C.

    2013-11-01

    In this work we utilize heat conduction measurements trough the photothermal beam deflection technique to characterize thermal properties of biological tissue. We design a heat flux sensor based on the phenomenon of photothermal laser beam deflection within a thermo-optic slab (acrylic), where the deflection is quantified by an optical fiber angle sensor. We analytically model the heat flux sensor response based on heat wave propagation theory that well agree with experimental data. We present heat conduction measurements on different tissues applying a heat pulse. Hence we obtain the thermal effusivity coefficient of bovine tendon and chicken liver and heart. It has been shown that thermal conduction depends on the tissués chemical composition as well on their structural arrangements, so any modification in tissue will affect on heat conduction rendering this method potentially useful as an auxiliary in biomedical studies. Nowadays there are several thermal effusivity and diffusivity measurement techniques with classic calorimetry (using thermistors) for research and industrial applications. However there are only few integrated optical devices already proposed, turning this optical technique in an innovative and alternative sensing system for thermal properties characterization.

  17. The influence of thermal aging on the optical coupler

    NASA Astrophysics Data System (ADS)

    Bednarek, Lukas; Hajek, Lukas; Vanderka, Ales; Nedoma, Jan; Fajkus, Marcel; Zboril, Ondrej; Vasinek, Vladimir

    2016-09-01

    Nowadays, it appears that the optical components aging faster. Therefore, it is accelerate of the research of the aging of the optical coupler by thermal stress necessary. This paper discusses finding of the influence of the thermal aging on the basic parameters of the optical coupler. The examined coupler has one input and eight outputs (1:8). The process of heat stress is carried out at 95°C in the electric drying oven where the coupler is loaded during the period of 120 hours. The optical power at the input of the coupler and the output optical powers of the individual branches of the coupler are measured after cooling to room temperature (approximately 25°C). The insertion losses of the individual branches, split ratio, total losses, homogeneity of the losses and cross-talk between individual branches are calculated using formulas. Measurements are made at wavelengths 1310 nm and 1550 nm. All optical powers are measured 20 times due to the statistical exclusion of error of measurements. The coupler is loaded during the period of 120 hours again immediately after measuring. Storing of the optical coupler in the drying oven is carried out so that is completely uniform heating of all the parts. The coupler is turn around every 30 hours. The paper contains the exact procedure of measurement of optical powers, which is followed by an evaluation of results. The results are shown for measurements before and after 5 cycles of heating.

  18. Process of making cryogenically cooled high thermal performance crystal optics

    DOEpatents

    Kuzay, Tuncer M.

    1992-01-01

    A method for constructing a cooled optic wherein one or more cavities are milled, drilled or formed using casting or ultrasound laser machining techniques in a single crystal base and filled with porous material having high thermal conductivity at cryogenic temperatures. A non-machined strain-free single crystal can be bonded to the base to produce superior optics. During operation of the cooled optic, N.sub.2 is pumped through the porous material at a sub-cooled cryogenic inlet temperature and with sufficient system pressure to prevent the fluid bulk temperature from reaching saturation.

  19. Process of making cryogenically cooled high thermal performance crystal optics

    DOEpatents

    Kuzay, T.M.

    1992-06-23

    A method is disclosed for constructing a cooled optic wherein one or more cavities are milled, drilled or formed using casting or ultrasound laser machining techniques in a single crystal base and filled with porous material having high thermal conductivity at cryogenic temperatures. A non-machined strain-free single crystal can be bonded to the base to produce superior optics. During operation of the cooled optic, N[sub 2] is pumped through the porous material at a sub-cooled cryogenic inlet temperature and with sufficient system pressure to prevent the fluid bulk temperature from reaching saturation. 7 figs.

  20. Quantitative Topographical Characterization of Thermally Sprayed Coatings by Optical Microscopy

    NASA Astrophysics Data System (ADS)

    Schwaller, P.; Züst, R.; Michler, J.

    2009-03-01

    Topography measurements and roughness calculations for different rough surfaces (Rugotest surface comparator and thermally sprayed coatings) are presented. The surfaces are measured with a novel quantitative topography measurement technique based on optical stereomicroscopy and a comparison is made with established scanning stylus and optical profilometers. The results show that for most cases the different methods yield similar results. Stereomicroscopy is therefore a valuable method for topographical investigations in both quality control and research. On the other hand, the method based on optical microscopy demands a careful optimization of the experimental settings like the magnification and the illumination to achieve satisfactory results.

  1. Solar Thermal Propulsion Optical Figure Measuring and Rocket Engine Testing

    NASA Technical Reports Server (NTRS)

    Bonometti, Joseph

    1997-01-01

    Solar thermal propulsion has been an important area of study for four years at the Propulsion Research Center. Significant resources have been devoted to the development of the UAH Solar Thermal Laboratory that provides unique, high temperature, test capabilities. The facility is fully operational and has successfully conducted a series of solar thruster shell experiments. Although presently dedicated to solar thermal propulsion, the facility has application to a variety of material processing, power generation, environmental clean-up, and other fundamental research studies. Additionally, the UAH Physics Department has joined the Center in support of an in-depth experimental investigation on Solar Thermal Upper Stage (STUS) concentrators. Laboratory space has been dedicated to the concentrator evaluation in the UAH Optics Building which includes a vertical light tunnel. Two, on-going, research efforts are being sponsored through NASA MSFC (Shooting Star Flight Experiment) and the McDonnell Douglas Corporation (Solar Thermal Upper Stage Technology Ground Demonstrator).

  2. Optical Structural Health Monitoring Device

    NASA Technical Reports Server (NTRS)

    Buckner, Benjamin D.; Markov, Vladimir; Earthman, James C.

    2010-01-01

    This non-destructive, optical fatigue detection and monitoring system relies on a small and unobtrusive light-scattering sensor that is installed on a component at the beginning of its life in order to periodically scan the component in situ. The method involves using a laser beam to scan the surface of the monitored component. The device scans a laser spot over a metal surface to which it is attached. As the laser beam scans the surface, disruptions in the surface cause increases in scattered light intensity. As the disruptions in the surface grow, they will cause the light to scatter more. Over time, the scattering intensities over the scanned line can be compared to detect changes in the metal surface to find cracks, crack precursors, or corrosion. This periodic monitoring of the surface can be used to indicate the degree of fatigue damage on a component and allow one to predict the remaining life and/or incipient mechanical failure of the monitored component. This wireless, compact device can operate for long periods under its own battery power and could one day use harvested power. The prototype device uses the popular open-source TinyOS operating system on an off-the-shelf Mica2 sensor mote, which allows wireless command and control through dynamically reconfigurable multi-node sensor networks. The small size and long life of this device could make it possible for the nodes to be installed and left in place over the course of years, and with wireless communication, data can be extracted from the nodes by operators without physical access to the devices. While a prototype has been demonstrated at the time of this reporting, further work is required in the system s development to take this technology into the field, especially to improve its power management and ruggedness. It should be possible to reduce the size and sensitivity as well. Establishment of better prognostic methods based on these data is also needed. The increase of surface roughness with

  3. Thermally robust semiconductor optical amplifiers and laser diodes

    DOEpatents

    Dijaili, Sol P.; Patterson, Frank G.; Walker, Jeffrey D.; Deri, Robert J.; Petersen, Holly; Goward, William

    2002-01-01

    A highly heat conductive layer is combined with or placed in the vicinity of the optical waveguide region of active semiconductor components. The thermally conductive layer enhances the conduction of heat away from the active region, which is where the heat is generated in active semiconductor components. This layer is placed so close to the optical region that it must also function as a waveguide and causes the active region to be nearly the same temperature as the ambient or heat sink. However, the semiconductor material itself should be as temperature insensitive as possible and therefore the invention combines a highly thermally conductive dielectric layer with improved semiconductor materials to achieve an overall package that offers improved thermal performance. The highly thermally conductive layer serves two basic functions. First, it provides a lower index material than the semiconductor device so that certain kinds of optical waveguides may be formed, e.g., a ridge waveguide. The second and most important function, as it relates to this invention, is that it provides a significantly higher thermal conductivity than the semiconductor material, which is the principal material in the fabrication of various optoelectronic devices.

  4. Adaptive beam shaping by controlled thermal lensing in optical elements.

    PubMed

    Arain, Muzammil A; Quetschke, Volker; Gleason, Joseph; Williams, Luke F; Rakhmanov, Malik; Lee, Jinho; Cruz, Rachel J; Mueller, Guido; Tanner, D B; Reitze, David H

    2007-04-20

    We describe an adaptive optical system for use as a tunable focusing element. The system provides adaptive beam shaping via controlled thermal lensing in the optical elements. The system is agile, remotely controllable, touch free, and vacuum compatible; it offers a wide dynamic range, aberration-free focal length tuning, and can provide both positive and negative lensing effects. Focusing is obtained through dynamic heating of an optical element by an external pump beam. The system is especially suitable for use in interferometric gravitational wave interferometers employing high laser power, allowing for in situ control of the laser modal properties and compensation for thermal lensing of the primary laser. Using CO(2) laser heating of fused-silica substrates, we demonstrate a focal length variable from infinity to 4.0 m, with a slope of 0.082 diopter/W of absorbed heat. For on-axis operation, no higher-order modes are introduced by the adaptive optical element. Theoretical modeling of the induced optical path change and predicted thermal lens agrees well with measurement.

  5. Optically active surfaces formed by ion implantation and thermal treatment

    SciTech Connect

    Gea, L.A.; Boatner, L.A.; Evans, H.M.; Zuhr, R.

    1996-08-01

    Embedded VO{sub 2} precipitates have been formed in single-crystal sapphire by the ion co-implantation of vanadium and oxygen and subsequent thermal annealing. The embedded VO{sub 2} particles have been shown to exhibit an optical switching behavior that is comparable to that of continuous thin films. In this work, the mechanisms of formation of these optically active particles are investigated. It is shown that precipitation of the vanadium dioxide phase is favored when the thermal treatment is performed on an ion-damaged but still crystalline (rather than amorphized) Al{sub 2}O{sub 3} substrate. The best optical switching behavior is observed in this case, and this behavior is apparently correlated with a more-favorable dispersion of VO{sub 2} small particles inside the matrix.

  6. Integration of Design, Thermal, Structural, and Optical Analysis, Including Thermal Animation

    NASA Technical Reports Server (NTRS)

    Amundsen, Ruth M.

    1993-01-01

    In many industries there has recently been a concerted movement toward 'quality management' and the issue of how to accomplish work more efficiently. Part of this effort is focused on concurrent engineering; the idea of integrating the design and analysis processes so that they are not separate, sequential processes (often involving design rework due to analytical findings) but instead form an integrated system with smooth transfers of information. Presented herein are several specific examples of concurrent engineering methods being carried out at Langley Research Center (LaRC): integration of thermal, structural and optical analyses to predict changes in optical performance based on thermal and structural effects; integration of the CAD design process with thermal and structural analyses; and integration of analysis and presentation by animating the thermal response of a system as an active color map -- a highly effective visual indication of heat flow.

  7. Design and analysis of the NFIRAOS thermal optics enclosure

    NASA Astrophysics Data System (ADS)

    Fitzsimmons, Joeleff; Andersen, David; Atwood, Jenny; Byrnes, Peter; Herriot, Glen; Hill, Alexis; Szeto, Kei

    2016-08-01

    The Narrow Field InfraRed Adaptive Optics System (NFIRAOS) will be the first-light facility adaptive optics system for the Thirty Meter Telescope (TMT). In order to meet the optical performance and stability specifications essential to leveraging the extraordinary capabilities of the TMT, all of the optical components within NFIRAOS will be protected within a large thermally-controlled optics enclosure (ENCL). Among the many functions performed by the ENCL, the most critical functions include providing a highly stable, light-tight, cold, dry environment maintained at 243±0.5 K for the NFIRAOS opto-mechanical sub-systems and supporting TABL structure. Although the performance of the ENCL during the science operation of NFIRAOS is critical, the maximum thermal loading will be defined by the cooldown/ warm-up cycle which must be accomplished within a time-frame that will minimize the on-sky operational impact due to daytime maintenance work. This study describes the thermal/mechanical design development and supporting analyses (analytical and finite element analyses (FEA)) completed during the preliminary design phase and through the current progression of the ENCL final design phase. The walls of the ENCL consist of interlocking, multilayered, thermally insulated panels, which are supported by an externally located structural framework which attaches to the NFIRAOS Instrument Support Structure. The regulation of the interior ENCL wall surface temperature to within ±0.5 K requires that the heat flux into the interior of NFIRAOS be eliminated by cooling a thermal conduction plate embedded between multiple layers of insulation. The thermal design of the enclosure was evaluated for both steady-state (SS) performance and transient performance (cool-down and warm-up cycles). The transient analysis utilizes a hybrid of a one-dimensional thermal network approach combined with three-dimensional conjugate heat transfer analyses of explicit opto-mechanical components within

  8. Method for quick thermal tolerancing of optical systems

    NASA Astrophysics Data System (ADS)

    Werschnik, J.; Uhlendorf, K.

    2016-09-01

    Optical systems for lithography (projection lens), inspection (micro-objectives) or laser material processing usually have tight specifications regarding focus and wave-front stability. The same is true regarding the field dependent properties. Especially projection lenses have tight specifications on field curvature, magnification and distortion. Unwanted heating either from internal or external sources lead to undesired changes of the above properties. In this work we show an elegant and fast method to analyze the thermal sensitivity using ZEMAX. The key point of this method is using the thermal changes of the lens data from the multi-configuration editor as starting point for a (standard) tolerance analysis. Knowing the sensitivity we can either define requirements on the environment or use it to systematically improve the thermal behavior of the lens. We demonstrate this method for a typical projection lens for which we optimized the thermal field curvature to a minimum.

  9. Optical metabolic imaging for monitoring tracheal health

    NASA Astrophysics Data System (ADS)

    Sharick, Joe T.; Gil, Daniel A.; Choma, Michael A.; Skala, Melissa C.

    2016-04-01

    The health of the tracheal mucosa and submucosa is a vital yet poorly understood component of critical care medicine, and a minimally-invasive method is needed to monitor tracheal health in patients. Of particular interest are the ciliated cells of the tracheal epithelium that move mucus away from the lungs and prevent respiratory infection. Optical metabolic imaging (OMI) allows cellular-level measurement of metabolism, and is a compelling method for assessing tracheal health because ciliary motor proteins require ATP to function. In this pilot study, we apply multiphoton imaging of the fluorescence intensities and lifetimes of metabolic co-enzymes NAD(P)H and FAD to the mucosa and submucosa of ex vivo mouse trachea. We demonstrate the feasibility and potential diagnostic utility of these measurements for assessing tracheal health and pathophysiology at the single-cell level.

  10. Fiber Optic Cable Thermal Preparation to Ensure Stable Operation

    NASA Technical Reports Server (NTRS)

    Thoames Jr, William J.; Chuska, Rick F.; LaRocca, Frank V.; Switzer, Robert C.; Macmurphy, Shawn L.; Ott, Melanie N.

    2008-01-01

    Fiber optic cables are widely used in modern systems that must provide stable operation during exposure to changing environmental conditions. For example, a fiber optic cable on a satellite may have to reliably function over a temperature range of -50 C up to 125 C. While the system requirements for a particular application will dictate the exact method by which the fibers should be prepared, this work will examine multiple ruggedized fibers prepared in different fashions and subjected to thermal qualification testing. The data show that if properly conditioned the fiber cables can provide stable operation, but if done incorrectly, they will have large fluctuations in transmission.

  11. Optical device with low electrical and thermal resistance bragg reflectors

    DOEpatents

    Lear, Kevin L.

    1996-01-01

    A compound-semiconductor optical device and method. The optical device is provided with one or more asymmetrically-graded heterojunctions between compound semiconductor layers for forming a distributed Bragg reflector mirror having an improved electrical and thermal resistance. Efficient light-emitting devices such as light-emitting diodes, resonant-cavity light-emitting diodes, and vertical-cavity surface-emitting lasers may be formed according to the present invention, which may be applied to the formation of resonant-cavity photodetectors.

  12. Optical device with low electrical and thermal resistance Bragg reflectors

    DOEpatents

    Lear, K.L.

    1996-10-22

    A compound-semiconductor optical device and method are disclosed. The optical device is provided with one or more asymmetrically-graded heterojunctions between compound semiconductor layers for forming a distributed Bragg reflector mirror having an improved electrical and thermal resistance. Efficient light-emitting devices such as light-emitting diodes, resonant-cavity light-emitting diodes, and vertical-cavity surface-emitting lasers may be formed according to the present invention, which may be applied to the formation of resonant-cavity photodetectors. 16 figs.

  13. 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.

  14. Use of Optical and Thermal Sights in Daylight Target Detection

    DTIC Science & Technology

    1983-02-01

    demonstrated in this research (see Table 1), it is clear that this variable had an effect on performance. Second , the proportion of t arge t perimeter... Research Report 1358 0- Use of Optical and Thermal Sights in Daylight Target Detection,, Brian L. Kottas and David W. Bessemer ARI Field Unit at Fort...Knox, Kentucky Training Research Laboratory DTIC ":1 Al ELECTE APR20 984 O3 U. S. Army Research Institute for the Behavioral and Social Sciences

  15. Aircraft fiber optic structural health monitoring

    NASA Astrophysics Data System (ADS)

    Mrad, Nezih

    2012-06-01

    Structural Health Monitoring (SHM) is a sought after concept that is expected to advance military maintenance programs, increase platform operational safety and reduce its life cycle cost. Such concept is further considered to constitute a major building block of any Integrated Health Management (IHM) capability. Since 65% to 80% of military assets' Life Cycle Cost (LCC) is devoted to operations and support (O&S), the aerospace industry and military sectors continue to look for opportunities to exploit SHM systems, capability and tools. Over the past several years, countless SHM concepts and technologies have emerged. Among those, fiber optic based systems were identified of significant potential. This paper introduces the elements of an SHM system and investigates key issues impeding the commercial implementation of fiber optic based SHM capability. In particular, this paper presents an experimental study of short gauge, intrinsic, spectrometric-based in-fiber Bragg grating sensors, for potential use as a component of an SHM system. Fiber optic Bragg grating sensors are evaluated against resistance strain gauges for strain monitoring, sensitivity, accuracy, reliability, and fatigue durability. Strain field disturbance is also investigated by "embedding" the sensors under a photoelastic coating in order to illustrate sensor intrusiveness in an embedded configuration.

  16. Thermal sensitivity of Lamb waves for structural health monitoring applications.

    PubMed

    Dodson, J C; Inman, D J

    2013-03-01

    One of the drawbacks of the current Lamb wave structural health monitoring methods are the false positives due to changing environmental conditions such as temperature. To create an environmental insensitive damage detection scheme, the physics of thermal effects on Lamb waves must be understood. Dispersion and thermal sensitivity curves for an isotropic plate with thermal stress and thermally varying elastic modulus are presented. The thermal sensitivity of dispersion curves is analytically developed and validated by experimental measurements. The group velocity thermal sensitivity highlights temperature insensitive features at two critical frequencies. The thermal sensitivity gives us insight to how temperature affects Lamb wave speeds in different frequency ranges and will help those developing structural health monitoring algorithms.

  17. Passive Thermal Compensation of the Optical Bench of the Galaxy Evolution Explorer

    NASA Technical Reports Server (NTRS)

    Ford, Virginia; Parks, Rick; Coleman, Michelle

    2004-01-01

    The Galaxy Evolution Explorer is an orbiting space telescope that will collect information on star formation by observing galaxies and stars in ultraviolet wavelengths. The optical bench supporting detectors and related optical components used an interesting and unusual passive thermal compensation technique to accommodate thermally-induced focal length changes in the optical system. The proposed paper will describe the optical bench thermal compensation design including concept, analysis, assembly and testing results.

  18. Monitoring of Thermal Protection Systems Using Robust Self-Organizing Optical Fiber Sensing Networks

    NASA Technical Reports Server (NTRS)

    Richards, Lance

    2013-01-01

    The general aim of this work is to develop and demonstrate a prototype structural health monitoring system for thermal protection systems that incorporates piezoelectric acoustic emission (AE) sensors to detect the occurrence and location of damaging impacts, and an optical fiber Bragg grating (FBG) sensor network to evaluate the effect of detected damage on the thermal conductivity of the TPS material. Following detection of an impact, the TPS would be exposed to a heat source, possibly the sun, and the temperature distribution on the inner surface in the vicinity of the impact measured by the FBG network. A similar procedure could also be carried out as a screening test immediately prior to re-entry. The implications of any detected anomalies in the measured temperature distribution will be evaluated for their significance in relation to the performance of the TPS during re-entry. Such a robust TPS health monitoring system would ensure overall crew safety throughout the mission, especially during reentry

  19. Optical Property Evaluation of Next Generation Thermal Control Coatings

    NASA Technical Reports Server (NTRS)

    Jaworske, Donald A.; Deshpande, Mukund S.; Pierson, Edward A.

    2010-01-01

    Next generation white thermal control coatings were developed via the Small Business Innovative Research program utilizing lithium silicate chemistry as a binder. Doping of the binder with additives yielded a powder that was plasma spray capable and that could be applied to light weight polymers and carbon-carbon composite surfaces. The plasma sprayed coating had acceptable beginning-of-life and end-of-live optical properties, as indicated by a successful 1.5 year exposure to the space environment in low Earth orbit. Recent studies also showed the coating to be durable to simulated space environments consisting of 1 keV and 10 keV electrons, 4.5 MeV electrons, and thermal cycling. Large scale deposition was demonstrated on a polymer matrix composite radiator panel, leading to the selection of the coating for use on the Gravity Recovery And Interior Laboratory (GRAIL) mission.

  20. Thermal effects in high average power optical parametric amplifiers.

    PubMed

    Rothhardt, Jan; Demmler, Stefan; Hädrich, Steffen; Peschel, Thomas; Limpert, Jens; Tünnermann, Andreas

    2013-03-01

    Optical parametric amplifiers (OPAs) have the reputation of being average power scalable due to the instantaneous nature of the parametric process (zero quantum defect). This Letter reveals serious challenges originating from thermal load in the nonlinear crystal caused by absorption. We investigate these thermal effects in high average power OPAs based on beta barium borate. Absorption of both pump and idler waves is identified to contribute significantly to heating of the nonlinear crystal. A temperature increase of up to 148 K with respect to the environment is observed and mechanical tensile stress up to 40 MPa is found, indicating a high risk of crystal fracture under such conditions. By restricting the idler to a wavelength range far from absorption bands and removing the crystal coating we reduce the peak temperature and the resulting temperature gradient significantly. Guidelines for further power scaling of OPAs and other nonlinear devices are given.

  1. Medical catheters thermally manipulated by fiber optic bundles

    DOEpatents

    Chastagner, Philippe

    1992-01-01

    A maneuverable medical catheter comprising a flexible tube having a functional tip. The catheter is connected to a control source. The functional tip of the catheter carries a plurality of temperature activated elements arranged in parallel and disposed about the functional tip and held in spaced relation at each end. These elements expand when they are heated. A plurality of fiber optic bundles, each bundle having a proximal end attached to the control source and a distal end attached to one of the elements carry light into the elements where the light is absorbed as heat. By varying the optic fiber that is carrying the light and the intensity of the light, the bending of the elements can be controlled and thus the catheter steered. In an alternate embodiment, the catheter carries a medical instrument for gathering a sample of tissue. The instrument may also be deployed and operated by thermal expansion and contraction of its moving parts.

  2. Medical catheters thermally manipulated by fiber optic bundles

    DOEpatents

    Chastagner, P.

    1992-10-06

    A maneuverable medical catheter comprising a flexible tube having a functional tip is described. The catheter is connected to a control source. The functional tip of the catheter carries a plurality of temperature activated elements arranged in parallel and disposed about the functional tip and held in spaced relation at each end. These elements expand when they are heated. A plurality of fiber optic bundles, each bundle having a proximal end attached to the control source and a distal end attached to one of the elements carry light into the elements where the light is absorbed as heat. By varying the optic fiber that is carrying the light and the intensity of the light, the bending of the elements can be controlled and thus the catheter steered. In an alternate embodiment, the catheter carries a medical instrument for gathering a sample of tissue. The instrument may also be deployed and operated by thermal expansion and contraction of its moving parts. 10 figs.

  3. Signature Optical Cues: Emerging Technologies for Monitoring Plant Health

    PubMed Central

    Liew, Oi Wah; Chong, Pek Ching Jenny; Li, Bingqing; Asundi, Anand K.

    2008-01-01

    Optical technologies can be developed as practical tools for monitoring plant health by providing unique spectral signatures that can be related to specific plant stresses. Signatures from thermal and fluorescence imaging have been used successfully to track pathogen invasion before visual symptoms are observed. Another approach for non-invasive plant health monitoring involves elucidating the manner with which light interacts with the plant leaf and being able to identify changes in spectral characteristics in response to specific stresses. To achieve this, an important step is to understand the biochemical and anatomical features governing leaf reflectance, transmission and absorption. Many studies have opened up possibilities that subtle changes in leaf reflectance spectra can be analyzed in a plethora of ways for discriminating nutrient and water stress, but with limited success. There has also been interest in developing transgenic phytosensors to elucidate plant status in relation to environmental conditions. This approach involves unambiguous signal creation whereby genetic modification to generate reporter plants has resulted in distinct optical signals emitted in response to specific stressors. Most of these studies are limited to laboratory or controlled greenhouse environments at leaf level. The practical translation of spectral cues for application under field conditions at canopy and regional levels by remote aerial sensing remains a challenge. The movement towards technology development is well exemplified by the Controlled Ecological Life Support System under development by NASA which brings together technologies for monitoring plant status concomitantly with instrumentation for environmental monitoring and feedback control. PMID:27879874

  4. Emergent Cometlike Swarming of Optically Driven Thermally Active Colloids

    NASA Astrophysics Data System (ADS)

    Cohen, Jack A.; Golestanian, Ramin

    2014-02-01

    We propose a simple system of optically driven colloids that convert light into heat and move in response to self-generated and collectively generated thermal gradients. We show that the system exhibits self-organization into a moving cometlike swarm and characterize the structure and response of the swarm to a light-intensity-dependent external tuning parameter. We observe many interesting features in this nonequilibrium system including circulation and evaporation, intensity-dependent shape, density and temperature fluctuations, and ejection of hot colloids from the swarm tip.

  5. A possible connection between thermal comfort and health

    SciTech Connect

    Stoops, John L.

    2004-05-20

    It is a well-established fact that cardiovascular health requires periodic exercise during which the human body often experiences significant physical discomfort. It is not obvious to the exerciser that the short-term pain and discomfort has a long-term positive health impact. Many cultures have well-established practices that involve exposing the body to periodic thermal discomfort. Scandinavian saunas and American Indian sweat lodges are two examples. Both are believed to promote health and well-being. Vacations often intentionally include significant thermal discomfort as part of the experience (e.g., sunbathing, and downhill skiing). So people often intentionally make themselves thermally uncomfortable yet the entire foundation of providing the thermal environment in our buildings is done to minimize the percentage of people thermally dissatisfied. We must provide an environment that does not negatively impact short-term health and we need to consider productivity but are our current thermal comfort standards too narrowly defined and do these standards actually contribute to longer-term negative health impacts? This paper examines the possibility that the human body thermoregulatory system has a corollary relationship to the cardiovascular system. It explores the possibility that we have an inherent need to exercise our thermoregulatory system. Potential, physiological, sociological and energy ramifications of these possibilities are discussed.

  6. Integrated optics for nulling interferometry in the thermal infrared

    NASA Astrophysics Data System (ADS)

    Barillot, Marc; Barthelemy, Eleonore; Broquin, Jean-Emmanuel; Frayret, Jérôme; Grelin, Jérôme; Hawkins, Gary; Kirschner, Volker; Parent, Gilles; Pradel, Annie; Rossi, Emmanuel; Vigreux, Caroline; Zhang, Shaoqian; Zhang, Xianghua

    2008-07-01

    Modal filtering is based on the capability of single-mode waveguides to transmit only one complex amplitude function to eliminate virtually any perturbation of the interfering wavefronts, thus making very high rejection ratios possible in a nulling interferometer. In the present paper we focus on the progress of Integrated Optics in the thermal infrared [6-20μm] range, one of the two candidate technologies for the fabrication of Modal Filters, together with fiber optics. In conclusion of the European Space Agency's (ESA) "Integrated Optics for Darwin" activity, etched layers of chalcogenide material deposited on chalcogenide glass substrates was selected among four candidates as the technology with the best potential to simultaneously meet the filtering efficiency, absolute and spectral transmission, and beam coupling requirements. ESA's new "Integrated Optics" activity started at mid-2007 with the purpose of improving the technology until compliant prototypes can be manufactured and validated, expectedly by the end of 2009. The present paper aims at introducing the project and the components requirements and functions. The selected materials and preliminary designs, as well as the experimental validation logic and test benches are presented. More details are provided on the progress of the main technology: vacuum deposition in the co-evaporation mode and subsequent etching of chalcogenide layers. In addition, preliminary investigations of an alternative technology based on burying a chalcogenide optical fiber core into a chalcogenide substrate are presented. Specific developments of anti-reflective solutions designed for the mitigation of Fresnel losses at the input and output surface of the components are also introduced.

  7. Thermal packaging of piggyback VCSELs for GBd optical communications modules

    NASA Astrophysics Data System (ADS)

    Simon, Jonathan; Giboney, Kirk S.; Buckman, Lisa A.

    2001-05-01

    Agilent Laboratories, in a DARPA supported effort, has been developing a series of low-cost VCSEL based, high- performance, surface mount, parallel channel optical communications modules. Separate transmit and receive modules with 12 channels operating at 1.25 and 2.5 GBd per channel have been demonstrated with a datacom application target. Current designs have Vertical Cavity Surface Emitting Lasers (VCSELs) located in tandem with a driver IC on a copper base, which performs both a mechanical and thermal function. A flex circuit substrate laminated on the base provides signal interconnects. As channel speeds increase, the need for co-locating the VCSEL array and its associated output drivers to minimize inductance becomes more important. One solution is to piggyback the VCSELs on the transmitter IC. However, the design is constrained by the need to maintain the VCSEL junction temperature at an acceptable level. Finite element thermal modeling of the tandem mounted and piggybacked VCSELs are discussed, with a focus on comparison of the two schemes at current and projected future power levels, the effect of wirebonds on IC to VCSEL heat transfer, and performance issues related to temperature. Thermal imaging data are used to validate models. The overall module packaging scheme is also discussed.

  8. Optical properties of mineral dust aerosol in the thermal infrared

    NASA Astrophysics Data System (ADS)

    Köhler, Claas H.

    2017-02-01

    The optical properties of mineral dust and biomass burning aerosol in the thermal infrared (TIR) are examined by means of Fourier Transform Infrared Spectrometer (FTIR) measurements and radiative transfer (RT) simulations. The measurements were conducted within the scope of the Saharan Mineral Dust Experiment 2 (SAMUM-2) at Praia (Cape Verde) in January and February 2008. The aerosol radiative effect in the TIR atmospheric window region 800-1200 cm-1 (8-12 µm) is discussed in two case studies. The first case study employs a combination of IASI measurements and RT simulations to investigate a lofted optically thin biomass burning layer with emphasis on its potential influence on sea surface temperature (SST) retrieval. The second case study uses ground based measurements to establish the importance of particle shape and refractive index for benchmark RT simulations of dust optical properties in the TIR domain. Our research confirms earlier studies suggesting that spheroidal model particles lead to a significantly improved agreement between RT simulations and measurements compared to spheres. However, room for improvement remains, as the uncertainty originating from the refractive index data for many aerosol constituents prohibits more conclusive results.

  9. Thermal-field-emission electron optics for nanolithography

    NASA Astrophysics Data System (ADS)

    Gesley, Mark

    1989-02-01

    A new column design for the 25-kV vector-scan Gaussian beam lithography system is described. A field-emission gun, consisting of a three-element electrostatic lens and Zr/O/W<100> cathode operated in a thermal-field mode for current stability, is combined in a demagnifying optics with a magnetic objective lens to focus a high-current-density (1000-3000 A/cm2) electron beam at high resolution (100-300 Å) at the wafer plane without a severe reduction in field size. Optimum beam semiangle, focus mode, and column magnification are determined. The modified system retains the original deflection coils and pattern-generation system which allows immediate implementation of existing subfield stitching, chip registration, and proximity correction software.

  10. Charge-induced optical bistability in thermal Rydberg vapor

    NASA Astrophysics Data System (ADS)

    Weller, Daniel; Urvoy, Alban; Rico, Andy; Löw, Robert; Kübler, Harald

    2016-12-01

    We investigate the phenomenon of optical bistability in a driven ensemble of Rydberg atoms. By performing two experiments with thermal vapors of rubidium and cesium, we are able to shed light on the underlying interaction mechanisms causing such a nonlinear behavior. Due to the different properties of these two atomic species, we conclude that the large polarizability of Rydberg states in combination with electric fields of spontaneously ionized Rydberg atoms is the relevant interaction mechanism. In the case of rubidium, we directly measure the electric field in a bistable situation via two-species spectroscopy. In cesium, we make use of the different sign of the polarizability for different l states and the possibility of applying electric fields. Both these experiments allow us to rule out dipole-dipole interactions and support our hypothesis of a charge-induced bistability.

  11. Laser induced optically and thermally reversible birefringence in azopolymers

    NASA Astrophysics Data System (ADS)

    Nazarova, D.; Nedelchev, L.; Ivanov, D.; Blagoeva, B.; Berberova, N.; Stoykova, E.; Mateev, G.; Kostadinova, D.

    2016-01-01

    Azopolymers are well known organic materials for polarization holographic recording due to the induced anisotropy under illumination with polarized light. They possess all the desirable characteristics of the known polarization-sensitive materials, as high sensitivity and reversibility, but excel them substantially in the magnitude of the photoinduced birefringence. This makes possible to record reversible polarization gratings with high diffraction efficiency. In this paper results of experimental investigations on the reversibility properties of birefringence photoinduced in azopolymers are reported, depending on the conditions of subsequent optical and thermal treatment. Thin films of different polymers were prepared in order to examine the kinetics of multiple recording and erasure of birefringence in different types of azopolymers. The reversibility of the polarization recording has been studied using two different method of erasure - by increased temperature and on illumination with circularly polarized light.

  12. Integrated Modeling Activities for the James Webb Space Telescope: Structural-Thermal-Optical Analysis

    NASA Technical Reports Server (NTRS)

    Johnston, John D.; Howard, Joseph M.; Mosier, Gary E.; Parrish, Keith A.; McGinnis, Mark A.; Bluth, Marcel; Kim, Kevin; Ha, Kong Q.

    2004-01-01

    The James Web Space Telescope (JWST) is a large, infrared-optimized space telescope scheduled for launch in 2011. This is a continuation of a series of papers on modeling activities for JWST. The structural-thermal-optical, often referred to as STOP, analysis process is used to predict the effect of thermal distortion on optical performance. The benchmark STOP analysis for JWST assesses the effect of an observatory slew on wavefront error. Temperatures predicted using geometric and thermal math models are mapped to a structural finite element model in order to predict thermally induced deformations. Motions and deformations at optical surfaces are then input to optical models, and optical performance is predicted using either an optical ray trace or a linear optical analysis tool. In addition to baseline performance predictions, a process for performing sensitivity studies to assess modeling uncertainties is described.

  13. Analysis on the effect of hypersonic vehicle's optical window on infrared thermal imaging system

    NASA Astrophysics Data System (ADS)

    Dong, Liquan; Han, Ying; Kong, Lingqin; Liu, Ming; Zhao, Yuejin; Zhang, Li; Li, Yanhong; Tian, Yi; Sa, Renna

    2015-08-01

    According to the aero-thermal effects and aero-thermal radiation effects of the optical window, the thermo-optic effect, the elasto-optical effect and the thermal deformation of the optical window are analyzed using finite element analysis method. Also, the peak value and its location of the point spread function, which is caused by the thermo-optic effect and the dome thermal deformation, are calculated with the variance of time. Furthermore, the temperature gradient influence to the transmission of optical window, the variation trend of transmission as well as optical window radiation with time are studied based on temperature distribution analysis. The simulations results show that: When the incident light is perpendicular to the optical window, image shift is mainly caused by its thermal deformation, and the value of image shift is very small. Image shift is determined only by the angle of the incident light. With a certain incident angle, image shift is not affected by the gradient refractive index change. The optical window transmission is mainly affected by temperature gradient and thus not neglectable to image quality. Therefore, the selection of window cooling methods, needs not only consider the window temperature but try to eliminate the temperature gradient. When calculating the thermal radiation, the optical window should be regarded as volume radiation source instead of surface radiator. The results provide the basis for the optical window design, material selection and the later image processing.

  14. Mechanical and thermal properties variant of polymer optical fibers

    NASA Astrophysics Data System (ADS)

    Waalib-Singh, Nirmal K.; Sceats, Mark

    2004-09-01

    Building on recent work, this paper describes the viscoelastic behavior of microstructured polymer optical fiber (MPOF). Previously published fixed frequency dynamic mechanical and thermal properties of the two types of POFs; a commercial, C-type and MPOF fiber prototype B are compared here with multi-frequency data. As expected of viscoelastic materials, results reveal a rate dependent behavior of the fibers where storage modulus (E') increases with frequency at each temperature and the glass transition (Tg) shifts to higher temperatures. A lack of a clear (Tg) and least amount of separation between low- and high-temperature transitions at different frequencies in the C fiber clearly indicate the speciality of the fiber; it exhibits extensive elongation or rather strain-softening beyond the draw-temperature-under-load (DrTUL), which is a highly desired property for optimized hot-drawing. Strain-hardening as exhibited by the MPOF B is a brought-forward effect of the mechanical and thermal histories from its macroscopic deformation during preform structuring and fiber-forming. Polymer entanglements that cause an increase in storage modulus and 'resistive' contraction from 60 to 105°C are most likely to be networked in an orderly manner. Demonstrated again in both types of fiber, DrTUL is critical for load bearing drawing.

  15. Thermal effects on the photoelastic coefficient of polymer optical fibers.

    PubMed

    Sophie, Acheroy; Patrick, Merken; Heidi, Ottevaere; Thomas, Geernaert; Hugo, Thienpont; Marques, Carlos A F; Webb, David J; Peng, Gang-Ding; Mergo, Pawel; Francis, Berghmans

    2016-06-01

    We measure the radial profile of the photoelastic coefficient C(r) in single-mode polymer optical fibers (POFs), and we determine the evolution of C(r) after annealing the fibers at temperatures from 40°C to 80°C. We demonstrate that C(r) in the fibers drawn from a preform without specific thermal pre-treatment changes and converges to values between 1.2 and 1.6×10-12  Pa-1 following annealing at 80°C. The annealed fibers display a smoothened radial profile of C(r) and a lowered residual birefringence. In contrast, the mean value of C(r) of the fiber drawn from a preform that has been pre-annealed remains constant after our annealing process and is significantly higher, i.e., 4×10-12  Pa-1. The annealing process decreases the residual birefringence to a lower extent as well. These measurements indicate the impact of annealing on the thermal stability of the photoelastic coefficient of POFs, which is an essential characteristic in view of developing POF-based thermo-mechanical sensors.

  16. Geometric optics of thermal blooming in gases. Part 1.

    PubMed

    Avizonis, P V; Hogge, C B; Butts, R R; Kenemuth, J R

    1972-03-01

    Thermal blooming is considered for the cases of with and without wind transverse to the beam propagation from the point of view of fluid dynamics of a compressible gaseous system and the coupling of this with geometric optics using eikonal formalism. Full compressible fluid dynamic relationships are developed (first-order perturbation approximation) with kinetics of energy relaxation from vibrational levels into heat and with thermal conductivity of a compressible gas as a heat loss mechanism. Eikonal theory is examined from the point of view of paraxial treatmen t in rigorous form, and some analytical beam intensity relationships are derived. In the process, several questions on the formation of caustics and thick lens effects are resolved. As a consequence of the above, a general time dependent model for the interaction of a laser beam with a compressible absorbing medium in the presence of wind is developed, and certain time dependent analytical solutions are obtained. These solutions reduce to the plain hermal blooming case with no wind and for long times to steady state wind case that has been previously reported by others to various degrees of correctness [F. G. Gebhardt and D. C. Smith, Appl. Phys. Lett. 14, 52 (1969); D. C. Smith, IEEE J. Quantum Electron. QE-5, 600 (1969)].

  17. Magnetic colloid by PLA: Optical, magnetic and thermal transport properties

    NASA Astrophysics Data System (ADS)

    Pandey, B. K.; Shahi, A. K.; Gopal, Ram

    2015-08-01

    Ferrofluids of cobalt and cobalt oxide nanoparticles (NPs) have been successfully synthesized using liquid phase-pulse laser ablation (LP-PLA) in ethanol and double distilled water, respectively. The mechanism of laser ablation in liquid media and formation process for Co target in double distilled water (DDW) and ethanol are speculated based on the reactions between laser generated highly nascent cobalt species and vaporized solvent media in a confined high temperature and pressure at the plume-surrounding liquid interface region. Optical absorption, emission, vibrational and rotational properties have been investigated using UV-vis absorption, photoluminescence (PL) and Fourier transform-infra red (FT-IR) spectroscopy, respectively. In this study optical band gap of cobalt oxide ferrofluids has been engineered using different pulse energy of Nd:YAG laser in the range of (2.80-3.60 eV). Vibrating sample magnetometer (VSM) is employed to determine the magnetic properties of ferrofluids of cobalt and cobalt oxide NPs while their thermal conductivities are examined using rotating disc method. Ferrofluids have gained enormous curiosity due to many technological applications, i.e. drug delivery, coolant and heating purposes.

  18. Optical-Fiber Thermal-Wave-Cavity Technique to Study Thermal Properties of Silver/Clay Nanofliuds

    NASA Astrophysics Data System (ADS)

    Noroozi, M.; Radiman, S.; Zakaria, A.; Shameli, K.; Deraman, M.; Soltaninejad, S.; Abedini, A.

    2014-10-01

    Thermal properties enhancement of nanofluids have varied strongly with synthesis technique, particle size and type, concentration and agglomeration with time. This study explores the possibility of changing the thermal wave signal of Ag/clay nanofluids into a thermal diffusivity measurement at well dispersion or aggregation of nanoparticles in the base fluid. Optical-Fiber Thermal-Wave-Cavity (OF-TWC) technique was achieved by using a small amount of nanofluid (only 0.2 mL) between fiber optic tip and the Pyroelectric detector and the cavity-length scan was performed. We established the accuracy and precision of this technique by comparing the thermal diffusivity of distilled water to values reported in the literature. Assuming a linear Pyroelectric signal response, the results show that adding clay reduced the thermal diffusivity of water, while increasing the Ag concentration from 1 to 5 wt.% increased the thermal diffusivity of the Ag nanofluid from 1.524×10-3 to 1.789×10-3 cm2/s. However, in particular, nanoparticles show the tendency to form aggregates over time that correlated with the performance change of thermal properties of nanofluid. Our results confirm the high sensitivity of OF-TWC technique raises the potential to be applied to measuring the optical and thermal properties of nanofluids. Furthermore, this technique allows the extraction of information not obtained using other traditional techniques.

  19. Effect of thermally induced strain on optical fiber sensors embedded in cement-based composites

    NASA Astrophysics Data System (ADS)

    Yuan, Li-bo; Zhou, Li-min; Jin, Wei; Lau, K. T.; Poon, Chi-kin

    2003-04-01

    A critical issue in developing a fiber-optic strain gauge is its codependency on temperature and strain. Any changes in the output of the optical fiber sensor due to its own thermal sensitivity and the thermal expansion of the most material will be misinterpreted as a change in shape-induced strain in the structure. This codependence is often referred to as thermally induced apparent strain or simply apparent strain. In this paper, an analytical model was developed to evaluate the thermally induced strain in fiber optic sensors embedded in cement-based composites. The effects of thermal induced strain on embedded optical fiber were measured with a white-light fiber-optic Michelson sensing interferometer for a number of cement-based host materials.

  20. Non-thermal optical excitation of terahertz-spin precession in a magneto-optical insulator

    SciTech Connect

    Parchenko, Sergii; Maziewski, Andrzej; Stupakiewicz, Andrzej; Satoh, Takuya; Yoshimine, Isao; Stobiecki, Feliks

    2016-01-18

    We demonstrate non-thermal ultrafast laser excitation of spin precession with THz frequency in Gd-Bi-substituted iron garnet via the inverse Faraday effect. The modulation of THz precession by about 60 GHz below the compensation temperature of magnetic moment was observed. The THz frequency precession was caused by the exchange resonance between the Gd and Fe sublattices; we attributed the low-frequency modulation to dielectric resonance mode with a magnetic contribution. We demonstrate the possibility of polarization-sensitive control of spin precession under THz generation by laser pulses, helping to develop high-speed magneto-optical devices.

  1. Feasibility of fiber-optic radiation sensor using Cerenkov effect for detecting thermal neutrons.

    PubMed

    Jang, Kyoung Won; Yagi, Takahiro; Pyeon, Cheol Ho; Yoo, Wook Jae; Shin, Sang Hun; Misawa, Tsuyoshi; Lee, Bongsoo

    2013-06-17

    In this research, we propose a novel method for detecting thermal neutrons with a fiber-optic radiation sensor using the Cerenkov effect. We fabricate a fiber-optic radiation sensor that detects thermal neutrons with a Gd-foil, a rutile crystal, and a plastic optical fiber. The relationship between the fluxes of electrons inducing Cerenkov radiation in the sensor probe of the fiber-optic radiation sensor and thermal neutron fluxes is determined using the Monte Carlo N-particle transport code simulations. To evaluate the fiber-optic radiation sensor, the Cerenkov radiation generated in the fiber-optic radiation sensor by irradiation of pure thermal neutron beams is measured according to the depths of polyethylene.

  2. Spatial and temporal thermal analysis of acousto-optic deflectors using finite element analysis model.

    PubMed

    Jiang, Runhua; Zhou, Zhenqiao; Lv, Xiaohua; Zeng, Shaoqun; Huang, Zhifeng; Zhou, Huaichun

    2012-07-01

    Thermal effects greatly influence the optical properties of the acousto-optic deflectors (AODs). Thermal analysis plays an important role in modern AOD design. However, the lack of an effective method of analysis limits the prediction in the thermal performance. In this paper, we propose a finite element analysis model to analyze the thermal effects of a TeO(2)-based AOD. Both transducer heating and acoustic absorption are considered as thermal sources. The anisotropy of sound propagation is taken into account for determining the acoustic absorption. Based on this model, a transient thermal analysis is employed using ANSYS software. The spatial temperature distributions in the crystal and the temperature changes over time are acquired. The simulation results are validated by experimental results. The effect of heat source and heat convection on temperature distribution is discussed. This numerical model and analytical method of thermal analysis would be helpful in the thermal design and practical applications of AODs.

  3. Optical and Thermal Stability of Oligofluorene/Rubber Luminescent Blend.

    PubMed

    Barbosa, Camila G; Faez, Roselena; Péres, Laura O

    2016-09-01

    This paper proposes to obtain homogeneous and stable blends of oligo(9,9-dioctylfluorene)-co-phenylene (OF), a conjugated oligomer with strong tendency of formation of excimers in the solid state, and nitrile rubber (NBR). This rubber protection reduces the formation of polymer excimers in the films. The fluorene oligomer was synthesized via Suzuki reaction and incorporated in the nitrile rubber. The films were formed by spin coating and casting techniques on the proportions of 1, 5, 10, 20 and 50 % (w/w) of OF in the nitrile rubber (NBR). The structural, optical and thermal properties of the films were evaluated with infrared, UV-Vis, fluorescence and thermogravimetry, respectively. The nitrile rubber proved to be essential for the preparation of homogeneous and stable films, since it was not possible to obtain films with only fluorene using the above-mentioned techniques. Furthermore, luminescent properties of OF are unchanged and the excimers formation in the solid state decrease suggesting the efficiency of nitrile rubber as the matrix for making films.

  4. Cryogenic Optical Performance of a Lightweighted Mirror Assembly for Future Space Astronomical Telescopes: Correlating Optical Test Results and Thermal Optical Model

    NASA Technical Reports Server (NTRS)

    Eng, Ron; Arnold, William R.; Baker, Marcus A.; Bevan, Ryan M.; Burdick, Gregory; Effinger, Michael R.; Gaddy, Darrell E.; Goode, Brian K.; Hanson, Craig; Hogue, William D.; Kegley, Jeffrey R.; Kirk, Charlie; Maffett, Steven P.; Matthews, Gary W.; Siler, Richard D.; Smith, W. Scott; Stahl, H. Philip; Tucker, John M.; Wright, Ernest R.

    2013-01-01

    A 43cm diameter stacked core mirror demonstrator was interferometrically tested at room temperature down to 250 degrees Kelvin for thermal deformation. The 2.5m radius of curvature spherical mirror assembly was constructed by low temperature fusing three abrasive waterjet core sections between two CNC pocket milled face sheets. The 93% lightweighted Corning ULE® mirror assembly represents the current state of the art for future UV, optical, near IR space telescopes. During the multiple thermal test cycles, test results of interferometric test, thermal IR images of the front face were recorded in order to validate thermal optical model.

  5. Cryogenic Optical Performance of a Light-weight Mirror Assembly for Future Space Astronomical Telescopes: Optical Test Results and Thermal Optical Model

    NASA Technical Reports Server (NTRS)

    Eng, Ron; Arnold, William; Baker, Markus A.; Bevan, Ryan M.; Carpenter, James R.; Effinger, Michael R.; Gaddy, Darrell E.; Goode, Brian K.; Kegley, Jeffrey R.; Hogue, William D.; Siler, Richard D.; Smith, W. Scott; Stahl. H. Philip; Tucker, John M.; Wright, Ernest R.; Kirk, Charles S.; Hanson, Craig; Burdick, Gregory; Maffett, Steven

    2013-01-01

    A 40 cm diameter mirror assembly was interferometrically tested at room temperature down to 250 degrees Kelvin for thermal deformation. The 2.5 m radius of curvature spherical mirror assembly was constructed by low temperature fusing three abrasive waterjet core sections between two face sheets. The 93% lightweighted Corning ULE mirror assembly represents the current state of the art for future UV, optical, near IR space telescopes. During the multiple thermal test cycles, test results of interferometric test, thermal IR images of the front face were recorded in order to validate thermal optical model.

  6. Fibre-optic sensors in health care

    NASA Astrophysics Data System (ADS)

    Grazia Mignani, Anna; Baldini, Francesco

    1997-05-01

    Biomedical fibre-optic sensors are attractive for the measurement of physical, chemical and biochemical parameters and for spectral measurements directly performed on the patient. An overview of fibre-optic sensors for in vivo monitoring is given, with particular attention paid to the advantages that these sensors are able to offer in different application fields such as cardiovascular and intensive care, angiology, gastroenterology, ophthalmology, oncology, neurology, dermatology and dentistry.

  7. Correlation of Predicted and Observed Optical Properties of Multilayer Thermal Control Coatings

    NASA Technical Reports Server (NTRS)

    Jaworske, Donald A.

    1998-01-01

    Thermal control coatings on spacecraft will be increasingly important, as spacecraft grow smaller and more compact. New thermal control coatings will be needed to meet the demanding requirements of next generation spacecraft. Computer programs are now available to design optical coatings and one such program was used to design several thermal control coatings consisting of alternating layers of WO3 and SiO2. The coatings were subsequently manufactured with electron beam evaporation and characterized with both optical and thermal techniques. Optical data were collected in both the visible region of the spectrum and the infrared. Predictions of solar absorptance and infrared emittance were successfully correlated to the observed thermal control properties. Functional performance of the coatings was verified in a bench top thermal vacuum chamber.

  8. Fiber-optic Bragg grating sensors for structural health monitoring at cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Ecke, Wolfgang; Latka, Ines; Habisreuther, Tobias; Lingertat, Johann

    2007-04-01

    While conventional resistance strain gages show increasing cross-sensitivities to temperature and magnetic field with decreasing temperature down to liquid helium, it has been found that fiber optic Bragg grating strain sensors show negligible thermo-optic and magneto-optic effects in cryogenic environment and allow, therefore, reliable strain measurements. These specific application advantages of optical fiber Bragg grating sensors at low temperatures, together with the electrical isolation and low electro-magnetic interference, low thermal conductivity to a large number of multiplexed sensors, make them attractive for structural health monitoring of super-conductive magnets, e.g., for super-conductive motors, magnetic levitation transport, nuclear fusion reactors, or for measurement of material parameters at low temperature, and, if using special sensor substrates, also for temperature measurements and hot spot detection on superconductors.

  9. Integrated Modeling Activities for the James Webb Space Telescope (JWST): Structural-Thermal-Optical Analysis

    NASA Technical Reports Server (NTRS)

    Johnston, John D.; Parrish, Keith; Howard, Joseph M.; Mosier, Gary E.; McGinnis, Mark; Bluth, Marcel; Kim, Kevin; Ha, Hong Q.

    2004-01-01

    This is a continuation of a series of papers on modeling activities for JWST. The structural-thermal- optical, often referred to as "STOP", analysis process is used to predict the effect of thermal distortion on optical performance. The benchmark STOP analysis for JWST assesses the effect of an observatory slew on wavefront error. The paper begins an overview of multi-disciplinary engineering analysis, or integrated modeling, which is a critical element of the JWST mission. The STOP analysis process is then described. This process consists of the following steps: thermal analysis, structural analysis, and optical analysis. Temperatures predicted using geometric and thermal math models are mapped to the structural finite element model in order to predict thermally-induced deformations. Motions and deformations at optical surfaces are input to optical models and optical performance is predicted using either an optical ray trace or WFE estimation techniques based on prior ray traces or first order optics. Following the discussion of the analysis process, results based on models representing the design at the time of the System Requirements Review. In addition to baseline performance predictions, sensitivity studies are performed to assess modeling uncertainties. Of particular interest is the sensitivity of optical performance to uncertainties in temperature predictions and variations in metal properties. The paper concludes with a discussion of modeling uncertainty as it pertains to STOP analysis.

  10. The thermal near-field: Coherence, spectroscopy, heat-transfer, and optical forces

    NASA Astrophysics Data System (ADS)

    Jones, Andrew C.; O'Callahan, Brian T.; Yang, Honghua U.; Raschke, Markus B.

    2013-12-01

    One of the most universal physical processes shared by all matter at finite temperature is the emission of thermal radiation. The experimental characterization and theoretical description of far-field black-body radiation was a cornerstone in the development of modern physics with the groundbreaking contributions from Gustav Kirchhoff and Max Planck. With its origin in thermally driven fluctuations of the charge carriers, thermal radiation reflects the resonant and non-resonant dielectric properties of media, which is the basis for far-field thermal emission spectroscopy. However, associated with the underlying fluctuating optical source polarization are fundamentally distinct spectral, spatial, resonant, and coherence properties of the evanescent thermal near-field. These properties have been recently predicted theoretically and characterized experimentally for systems with thermally excited molecular, surface plasmon polariton (SPP), and surface phonon polariton (SPhP) resonances. We review, starting with the early historical developments, the emergence of theoretical models, and the description of the thermal near-field based on the fluctuation-dissipation theory and in terms of the electromagnetic local density of states (EM-LDOS). We discuss the optical and spectroscopic characterization of distance dependence, magnitude, spectral distribution, and coherence of evanescent thermal fields. Scattering scanning near-field microscopy proved instrumental as an enabling technique for the investigations of several of these fundamental thermal near-field properties. We then discuss the role of thermal fields in nano-scale heat transfer and optical forces, and the correlation to the van der Waals, Casimir, and Casimir-Polder forces. We conclude with an outlook on the possibility of intrinsic and extrinsic resonant manipulation of optical forces, control of nano-scale radiative heat transfer with optical antennas and metamaterials, and the use of thermal infrared near

  11. Monitoring of Thermal Protection Systems and MMOD using Robust Self-Organizing Optical Fiber Sensing Networks

    NASA Technical Reports Server (NTRS)

    Richards, Lance

    2014-01-01

    The general aim of this work is to develop and demonstrate a prototype structural health monitoring system for thermal protection systems that incorporates piezoelectric acoustic emission (AE) sensors to detect the occurrence and location of damaging impacts, such as those from Micrometeoroid Orbital Debris (MMOD). The approach uses an optical fiber Bragg grating (FBG) sensor network to evaluate the effect of detected damage on the thermal conductivity of the TPS material. Following detection of an impact, the TPS would be exposed to a heat source, possibly the sun, and the temperature distribution on the inner surface in the vicinity of the impact measured by the FBG network. A similar procedure could also be carried out as a screening test immediately prior to re-entry. The implications of any detected anomalies in the measured temperature distribution will be evaluated for their significance in relation to the performance of the TPS during reentry. Such a robust TPS health monitoring system would ensure overall crew safety throughout the mission, especially during reentry.

  12. Theoretical analysis for scaling law of thermal blooming based on optical phase deference

    NASA Astrophysics Data System (ADS)

    Sun, Yunqiang; Huang, Zhilong; Ren, Zebin; Chen, Zhiqiang; Guo, Longde; Xi, Fengjie

    2016-10-01

    In order to explore the laser propagation influence of thermal blooming effect of pipe flow and to analysis the influencing factors, scaling law theoretical analysis of the thermal blooming effects in pipe flow are carry out in detail based on the optical path difference caused by thermal blooming effects in pipe flow. Firstly, by solving the energy coupling equation of laser beam propagation, the temperature of the flow is obtained, and then the optical path difference caused by the thermal blooming is deduced. Through the analysis of the influence of pipe size, flow field and laser parameters on the optical path difference, energy scaling parameters Ne=nTαLPR2/(ρɛCpπR02) and geometric scaling parameters Nc=νR2/(ɛL) of thermal blooming for the pipe flow are derived. Secondly, for the direct solution method, the energy coupled equations have analytic solutions only for the straight tube with Gauss beam. Considering the limitation of directly solving the coupled equations, the dimensionless analysis method is adopted, the analysis is also based on the change of optical path difference, same scaling parameters for the pipe flow thermal blooming are derived, which makes energy scaling parameters Ne and geometric scaling parameters Nc have good universality. The research results indicate that when the laser power and the laser beam diameter are changed, thermal blooming effects of the pipeline axial flow caused by optical path difference will not change, as long as you keep energy scaling parameters constant. When diameter or length of the pipe changes, just keep the geometric scaling parameters constant, the pipeline axial flow gas thermal blooming effects caused by optical path difference distribution will not change. That is to say, when the pipe size and laser parameters change, if keeping two scaling parameters with constant, the pipeline axial flow thermal blooming effects caused by the optical path difference will not change. Therefore, the energy scaling

  13. Optical Thermal Characterization Enables High-Performance Electronics Applications

    SciTech Connect

    2016-02-01

    NREL developed a modeling and experimental strategy to characterize thermal performance of materials. The technique provides critical data on thermal properties with relevance for electronics packaging applications. Thermal contact resistance and bulk thermal conductivity were characterized for new high-performance materials such as thermoplastics, boron-nitride nanosheets, copper nanowires, and atomically bonded layers. The technique is an important tool for developing designs and materials that enable power electronics packaging with small footprint, high power density, and low cost for numerous applications.

  14. OPTICAL FIBRES: Photoinduced and thermal reactions involving hydrogen in high-germania-core optical fibres

    NASA Astrophysics Data System (ADS)

    Rybaltovskii, A. O.; Koltashev, V. V.; Medvedkov, O. I.; Rybaltovsky, A. A.; Sokolov, V. O.; Klyamkin, Semen N.; Plotnichenko, V. G.; Dianov, Evgenii M.

    2008-12-01

    We report a Raman scattering study of photoinduced and thermal reactions between H2 and germanosilicate optical fibres with 22 mol % and 97 mol % GeO2 in the core (F1 and F2, respectively) after H2 loading at 150 MPa (1500 atm). The mechanisms of photoreactions are investigated in a wide range of incident laser wavelengths (244, 333, 354, 361 and 514 nm). Thermal reactions are studied at 500 °C. The results indicate that the main mechanism behind the formation of hydrogen-containing defects with Raman bands at 700, 750, 2190, 3600 and 3680 cm-1 involves ≡Ge—O—Ge≡ or ≡Ge—O—Si≡ bond breaking and formation of hydride and hydroxyl species: =GeH2 (700, 750 cm-1), ≡Ge—H (2190 cm-1), ≡GeO—H (3600 cm-1) and ≡SiO—H (3680 cm-1). The key features of the reactions in the F1 and F2 fibres are analysed. In particular, photoinduced reactions give ≡Si—OH groups only in the F1 fibres, whereas the formation of germanium nanoclusters at a relatively low temperature (~500 °C) or ≡GeO—H and ≡Ge—H defects under 514-nm irradiation has only been observed in the F2 fibres.

  15. Measuring the thermal expansion coefficient of the carbon fiber optical tube by heterodyne laser interferometry

    NASA Astrophysics Data System (ADS)

    Zhang, Kai; He, Wenjun; Zhang, Lei; Zhao, Xuan; Tian, Yuqi

    2016-11-01

    In This paper, we present an experimental design of measuring thermal expansion coefficient of the carbon fiber optical tube based on the heterodyne laser interferometry. In the course of the experiment, the error caused by the temperature changes of the external environment was considered, and the compensation is carried out. The data of the experiment was recorded and analyzed. The curve of the thermal expansion coefficient of the carbon fiber optical tube was close. The measurement of the thermal expansion coefficient was finished within a small range of temperature changes. The thermal expansion coefficient of the carbon fiber optical tube was 6 0.78 x 10-5m/ ° C - × , which was consistent with the experience value. Athermalization for the supporting structure of the Cassette optical system was designed according to the results of the experiment.

  16. Thermal-optical properties of Fluorel L-3203-6 and 1059

    NASA Technical Reports Server (NTRS)

    French, B.

    1972-01-01

    Fluorel L-3203-6 and 1059 and four Fluorel derivatives were irradiated monochromatically and hemispherically with electromagnetic energy in the solar- and infrared-wavelength range to determine the thermal-optical properties that are required for engineering analysis. The thermal-optical properties were measured and analyzed, and the resulting data were tabulated for convenient engineering use. The results prove that the electromagnetic-energy distribution and the measured reflectance and transmittance of materials can be used to calculate several mean values, which are the total and hemispherical thermal-optical properties. The test results also illustrate that Fluorel effectively absorbs energy in the solar- and infrared-wavelength range. In addition, the results demonstrate that fabrication alters the thermal-optical properties of Fluorel.

  17. An algorithm for retrieving black carbon optical parameters from thermal-optical (OC/EC) instruments

    NASA Astrophysics Data System (ADS)

    Andersson, A.; Sheesley, R. J.; Kirillova, E. N.; Gustafsson, Ö.

    2011-02-01

    Through absorption of sun light atmospheric black carbon (BC) is expected to influence regional/global climate by warming the atmosphere and dimming the surface. To evaluate the impact of these effects it is of interest to examine both the radiative properties of BC and the concentrations in air. Building on recent developments we present a novel application for combining these two aspects using the common thermal-optical (OC/EC) instrument. By correlating the OC/EC laser transmission with the FID-carbon detection non-carbon contributions to the light attenuation are detected. Such analysis allows the calculation of mass absorption cross-sections (MACs) for BC, corrected for certain in-organic components. This approach has been applied to data from two SS Asian and two SNS European sites, including a time series analysis for one of the SNS European sites. Taken together this study demonstrates broad applicability for this method while providing new insights into the optical properties of BC.

  18. Optical Gaussian beam interaction with one-dimensional thermal wave in the Raman-Nath configuration.

    PubMed

    Bukowski, Roman J

    2009-03-01

    Optical Gaussian beam interaction with a one-dimensional temperature field in the form of a thermal wave in the Raman-Nath configuration is analyzed. For the description of the Gaussian beam propagation through the nonstationary temperature field the complex geometric optics method was used. The influence of the refractive coefficient modulation by thermal wave on the complex ray phase, path, and amplitude was taken into account. It was assumed that for detection of the modulated Gaussian beam parameters two types of detector can be used: quadrant photodiodes or centroidal photodiodes. The influence of such parameters as the size and position of the Gaussian beam waist, the laser-screen (detector) distance, the thermal wave beam position and width, as well as thermal wave frequency and the distance between the probing optical beam axis and source of thermal waves on the so-called normal signal was taken into account.

  19. The effect of Brown Carbon on thermal-optical analysis: a correction based on optical multi-wavelength analysis

    NASA Astrophysics Data System (ADS)

    Dario, Massabò; Lorenzo, Caponi; Chiara, Bove Maria; Paolo, Prati

    2016-04-01

    Carbonaceous aerosol (CA) has an important impact on air quality, human health and climate change. Total Carbon (TC) is generally divided in organic carbon (OC) and elemental carbon (EC) (although a minor fraction of carbonate carbon (CC) may be present). This classification is based on their thermo-optical properties: while EC is strongly light absorbing, OC is generally transparent in the visible range except for some particular compounds. In fact, another fraction of light-absorbing organic carbon exists which is not black and is generally called brown carbon (BrC) (Andreae and Gelencsér, 2006). We recently introduced a new method to apportion the absorption coefficient (babs) of carbonaceous atmospheric aerosols starting from multi-wavelength optical analysis (Massabò et al., 2015). This analysis is performed by the MWAA, an instrument developed at the Physics Department of University of Genoa (Massabò et al., 2013) able to measure the aerosol absorption coefficient at 5 different wavelengths ranging from UV to IR. The method is based on the information gathered at these five different wavelengths, in a renewed and upgraded version of the approach usually referred to as Aethalometer model (Sandradewi et al., 2008). The resulting optical apportionment provides the quantification of EC and, with some assumptions, also of OC coming from fossil fuels and wood burning. Thermal-optical methods are presently the most widespread approach to OC/EC speciation. Despite their popularity, there is still a disagreement among the results, especially for what concerns EC as different thermal protocols can be used. In fact, the pyrolysis occurring during the analysis can heavily affect OC/EC separation, depending on PM composition in addition to the used protocol. Furthermore, the presence in the sample of BrC can shift the split point since it is light absorbing also @ 635nm, the typical laser wavelength used in this technique (Chen et al., 2015). We present here the

  20. Feedback control of thermal lensing in a high optical power cavity.

    PubMed

    Fan, Y; Zhao, C; Degallaix, J; Ju, L; Blair, D G; Slagmolen, B J J; Hosken, D J; Brooks, A F; Veitch, P J; Munch, J

    2008-10-01

    This paper reports automatic compensation of strong thermal lensing in a suspended 80 m optical cavity with sapphire test mass mirrors. Variation of the transmitted beam spot size is used to obtain an error signal to control the heating power applied to the cylindrical surface of an intracavity compensation plate. The negative thermal lens created in the compensation plate compensates the positive thermal lens in the sapphire test mass, which was caused by the absorption of the high intracavity optical power. The results show that feedback control is feasible to compensate the strong thermal lensing expected to occur in advanced laser interferometric gravitational wave detectors. Compensation allows the cavity resonance to be maintained at the fundamental mode, but the long thermal time constant for thermal lensing control in fused silica could cause difficulties with the control of parametric instabilities.

  1. Optimization of thermal systems with sensitive optics, electronics, and structures

    NASA Technical Reports Server (NTRS)

    Bettini, R. G.; Costello, F. A.

    1984-01-01

    A strategy was investigated by which thermal designers for spacecraft could devise an optimal thermal control system to maintain the required temperatures, temperature differences, changes in temperature, and changes in temperature differences for specified equipment and elements of the spacecraft's structure. Thermal control is to be maintained by the coating pattern chosen for the external surfaces and heaters chosen to supplement the coatings. The approach is to minimize the thermal control power, thereby minimizing the weight of the thermal control system. Because there are so many complex computations involved in determining the optimal coating design a computerized approach was contemplated. An optimization strategy including all the elements considered by the thermal designer for use in the early stages of design, where impact on the mission is greatest, and a plan for implementing the strategy were successfully developed. How the optimization process may be used to optimize the design of the Space Telescope as a test case is demonstrated.

  2. Ion beam figuring approach for thermally sensitive space optics.

    PubMed

    Yin, Xiaolin; Deng, Weijie; Tang, Wa; Zhang, Binzhi; Xue, Donglin; Zhang, Feng; Zhang, Xuejun

    2016-10-01

    During the ion beam figuring (IBF) of a space mirror, thermal radiation of the neutral filament and particle collisions will heat the mirror. The adhesive layer used to bond the metal parts and the mirror is very sensitive to temperature rise. When the temperature exceeds the designed value, the mirror surface shape will change markedly because of the thermal deformation and stress release of the adhesive layer, thereby reducing the IBF accuracy. To suppress the thermal effect, we analyzed the heat generation mechanism. By using thermal radiation theory, we established a thermal radiation model of the neutral filament. Additionally, we acquired a surface-type Gaussian heat source model of the ion beam sputtering based on the removal function and Faraday scan result. Using the finite-element-method software ABAQUS, we developed a method that can simulate the thermal effect of the IBF for the full path and all dwell times. Based on the thermal model, which was experimentally confirmed, we simulated the thermal effects for a 675  mm×374  mm rectangular SiC space mirror. By optimizing the dwell time distribution, the peak temperature value of the adhesive layer during the figuring process was reduced under the designed value. After one round of figuring, the RMS value of the surface error changed from 0.094 to 0.015λ (λ=632.8  nm), which proved the effectiveness of the thermal analysis and suppression method.

  3. Thermal Weapon Sight (TWS) AN/PAS-13 diffractive optics designed for producibility

    NASA Technical Reports Server (NTRS)

    Anderson, J. Steven; Chen, Chungte W.; Spande, Robert A.

    1993-01-01

    The Thermal Weapon Sight (TWS) program is a manportable 3-5 micrometer forward-looking-infrared (FLIR) rifle sight. The manportable nature requires that the optics modules be lightweight, low cost and compact while maximizing performance. These objectives were met with diffractive optics. TWS promises to be the first FLIR sensor to incorporate kinoform surfaces in full scale production.

  4. An Algebraic Model of Adaptive Optics for Continuous-Wave Thermal Blooming.

    DTIC Science & Technology

    1979-01-01

    blooming. The aberrations modeled generally include those applied by an adaptive optics system to compensate the naturally occurring ones. For the...results when applied to thermal blooming. However, the analysis suggests novel remedies that will tend to optimize the corrections made, thus better realizing the full potential of adaptive optics . (Author)

  5. Management of thermal effects in high-repetition-rate pulsed optical parametric oscillators.

    PubMed

    Godard, Antoine; Raybaut, Myriam; Schmid, Thomas; Lefebvre, Michel; Michel, Anne-Marie; Péalat, Michel

    2010-11-01

    We report on the investigation of thermal effects in high-repetition-rate pulsed optical parametric oscillators emitting in the mid-IR. We find that the thermal load induced by the nonresonant idler absorption plays a critical role in the emergence of thermally induced bistability. We then demonstrate a significant improvement of the conversion efficiency (more than 30%) when a proper axial temperature gradient is applied to the nonlinear crystal by use of a two-zone temperature-controlled oven.

  6. Study of spectroscopic and thermal characteristics of nonlinear optical molecular crystals based on 4-nitrophenol

    NASA Astrophysics Data System (ADS)

    Pavlovetc, I. M.; Fokina, M. I.

    2016-08-01

    The paper presents the results of study of spectroscopic and thermal characteristics of molecular co-crystals: 2-aminopyridine-4-nitrophenol-4-mtrophenolate (2AP4N) and 2,6- diaminopyridine-4-nitrophenol-4nitrophenolate (26DAP4N). Crystals were successfully grown by slow evaporation technique. Optical transparency in the region of 190-1100 was found to be suitable for applications with cut off wavelengths 420 and 430 nm respectively. Thermogravimetric and differential thermal analysis show good quality and thermal stability for studied crystals. Kurtz and Perry powder technique proves that the crystals are acentric and have significant nonlinear optical response.

  7. A wide-band fiber optic frequency distribution system employing thermally controlled phase compensation

    NASA Technical Reports Server (NTRS)

    Johnson, Dean; Calhoun, Malcolm; Sydnor, Richard; Lutes, George

    1993-01-01

    An active wide-band fiber optic frequency distribution system employing a thermally controlled phase compensator to stabilize phase variations induced by environmental temperature changes is described. The distribution system utilizes bidirectional dual wavelength transmission to provide optical feedback of induced phase variations of 100 MHz signals propagating along the distribution cable. The phase compensation considered differs from earlier narrow-band phase compensation designs in that it uses a thermally controlled fiber delay coil rather than a VCO or phase modulation to compensate for induced phase variations. Two advantages of the wide-band system over earlier designs are (1) that it provides phase compensation for all transmitted frequencies, and (2) the compensation is applied after the optical interface rather than electronically ahead of it as in earlier schemes. Experimental results on the first prototype shows that the thermal stabilizer reduces phase variations and Allan deviation by a factor of forty over an equivalent uncompensated fiber optic distribution system.

  8. Investigation of thermal and optical properties of thin WO3 films by the photothermal Deflection Technique

    NASA Astrophysics Data System (ADS)

    Gaied, I.; Dabbous, S.; Ben Nasrallah, T.; Yacoubi, N.

    2010-03-01

    Owing to its novel physical properties, as well as its technological implication in many fields, the thermal and optical properties of WO3 thin films are studied here. These thin films are prepared from Ammonium Tungstate and deposited on a glass substrate at 400°C by the Spray Pyrolysis Technique. The thermal properties (Thermal conductivity and thermal diffusivity) were studied by the Photothermal Deflection method in its uniform heating case instead of traditionally a non uniform heating one by comparing the experimental amplitude and phase variations versus square root modulation frequency to the corresponding theoretical ones. The best coincidence between theory and experience is obtained for well-defined values of thermal conductivity and thermal diffusivity. The optical properties (optical absorption spectrum and gap energy) were measured using the Photothermal Deflection Spectroscopy (PDS) by drawing the amplitude and phase variation versus wavelength in experimental way and versus absorption coefficient in theoretical one at a fixed modulation frequency. By comparing point by point the normalised experimental and corresponding theoretical amplitude variation, one can deduce the optical absorption spectrum. Using the Tauc law for energies above the gap we can deduce the gap energy. We notice that these films show low thermal conductivity and high transparency in the visible range.

  9. Crystal growth, thermal and optical studies on a semiorganic nonlinear optical material for blue-green laser generation.

    PubMed

    Ramajothi, J; Dhanuskodi, S

    2007-12-31

    The semiorganic nonlinear optical material l-histidine bromide (l-HB) has been synthesized in aqueous solution and characterized by FT-IR, FT-Raman and FT-NMR spectroscopic techniques. The single crystals with dimensions 9mm x 4mm x 3mm were grown by slow evaporation techniques. The grown crystals were subjected to single crystal X-ray diffraction to determine the unit cell dimensions. The thermal stability of the grown crystal was analyzed by thermogravimetric (TG), differential thermal (DT) and differential scanning calorimetric (DSC) analyses. The UV-vis transmittance spectrum shows that it has a good optical transmittance in the entire visible region with the lower cutoff wavelength at 220 nm. The SHG conversion efficiency and laser damage threshold were measured using a Nd:YAG laser (1064 nm). The optical birefringence was measured in the visible region as a function of temperature in the range 30-150 degrees C by interference technique.

  10. Thermally tuneable optical modulator adapted for differential signaling

    DOEpatents

    Zortman, William A.

    2016-01-12

    An apparatus for optical modulation is provided. The apparatus includes a modulator structure and a heater structure. The modulator structure comprises a ring or disk optical resonator having a closed curvilinear periphery and a pair of oppositely doped semiconductor regions within and/or adjacent to the optical resonator and conformed to modify the optical length of the optical resonator upon application of a bias voltage. The heater structure comprises a relatively resistive annulus of semiconductor material enclosed between an inner disk and an outer annulus of relatively conductive semiconductor material. The inner disk and the outer annulus are adapted as contact regions for a heater activation current. The heater structure is situated within the periphery of the optical resonator such that in operation, at least a portion of the resonator is heated by radial conductive heat flow from the heater structure. The apparatus further includes a substantially annular isolation region of dielectric or relatively resistive semiconductor material interposed between the heater structure and the modulator structure. The isolation region is effective to electrically isolate the bias voltage from the heater activation current.

  11. Computer modeling and analysis of thermal link performance for an optical refrigerator

    NASA Astrophysics Data System (ADS)

    Byram, Kevin; Mar, David; Parker, John; Von der Porten, Steven; Hankinson, John; Lee, Chris; Mayeda, Kai; Haskell, Richard C.; Yang, Qimin; Greenfield, Scott R.; Epstein, Richard I.

    2008-02-01

    We have used the thermal modeling tool in COMSOL Multiphysics to investigate factors that affect the thermal performance of the optical refrigerator. Assuming an ideal cooling element and a non-absorptive dielectric trapping mirror, the three dominant heating factors are blackbody radiation from the surrounding environment, conductive heat transfer through mechanical supports, and the absorption of fluoresced photons transmitted through the thermal link. Laboratory experimentation coupled with computer modeling using Code V optical software have resulted in link designs capable of reducing the transmission to 0.04% of the fluoresced photons emitted toward the thermal link. The ideal thermal link will have minimal surface area, provide complete optical isolation for the load, and possess high thermal conductivity. Modeling results imply that a 1cm 3 load can be chilled to 102 K with currently available cooling efficiencies using a 100 W pump laser on a YB:ZBLANP system, and using an ideal link that has minimal surface area and no optical transmission. We review the simulated steady-state cooling temperatures reached by the heat load for several link designs and system configurations as a comparative measure of how well particular configurations perform.

  12. Interfacial reflection enhanced optical extinction and thermal dynamics in polymer nanocomposite films

    NASA Astrophysics Data System (ADS)

    Dunklin, Jeremy R.; Forcherio, Gregory T.; Berry, Keith R.; Roper, D. Keith

    2016-09-01

    Polymer films containing plasmonic nanostructures are of increasing interest for development of responsive energy, sensing, and therapeutic systems. A series of novel gold nanoparticle (AuNP)-polydimethylsiloxane (PDMS) films were fabricated to elucidate enhanced optical extinction from diffractive and scattering induced internal reflection. AuNPs with dramatically different scattering-to-absorption ratios were compared at variable interparticle separations to differentiate light trapping from optical diffraction and Mie scattering. Description of interfacial optical and thermal effects due to these interrelated contributions has progressed beyond Mie theory, Beer's law, effective media, and conventional heat transfer descriptions. Thermal dissipation rates in AuNP-PDMS with this interfacial optical reflection was enhanced relative to films containing heterogeneous AuNPs and a developed thermal dissipation description. This heuristic, which accounts for contributions of both internal and external thermal dissipations, has been shown to accurately predict thermal dissipation rates from AuNP-containing insulating and conductive substrates in both two and three-dimensional systems. Enhanced thermal response rates could enable design and adaptive control of thermoplasmonic materials for a variety of implementations.

  13. Observation of fundamental thermal noise in optical fibers down to infrasonic frequencies

    NASA Astrophysics Data System (ADS)

    Dong, Jing; Huang, Junchao; Li, Tang; Liu, Liang

    2016-01-01

    The intrinsic thermal noise in optical fibers represents the ultimate limit for fiber-based systems. However, at infrasonic frequencies, the spectral behavior of the intrinsic thermal noise is still unclear. In this letter, we present measurements of the fundamental thermal noise in optical fibers that are obtained using a balanced fiber Michelson interferometer. When an ultra-stable laser is used as the laser source and other noise sources are carefully controlled, the 1/f spectral density of the thermal noise is observed down to infrasonic frequencies, and the measured magnitude is consistent with the results of theoretical predictions at frequencies over the range from 0.2 Hz to 20 kHz. Moreover, as observed experimentally, the level of the 1/f thermal noise can be reduced by changing the coatings of the optical fibers. This therefore indicates one possible way to reduce thermal noise in optical fibers at low Fourier frequencies. Finally, the inconsistency between the experimental data and the existing theory for thermomechanical noise is discussed.

  14. Application of optical character recognition in thermal image processing

    NASA Astrophysics Data System (ADS)

    Chan, W. T.; Sim, K. S.; Tso, C. P.

    2011-07-01

    This paper presents the results of a study on the reliability of the thermal imager compared to other devices that are used in preventive maintenance. Several case studies are used to facilitate the comparisons. When any device is found to perform unsatisfactorily where there is a suspected fault, its short-fall is determined so that the other devices may compensate, if possible. This study discovered that the thermal imager is not suitable or efficient enough for systems that happen to have little contrast in temperature between its parts or small but important parts that have their heat signatures obscured by those from other parts. The thermal imager is also found to be useful for preliminary examinations of certain systems, after which other more economical devices are suitable substitutes for further examinations. The findings of this research will be useful to the design and planning of preventive maintenance routines for industrial benefits.

  15. Integrated fiber optical and thermal sensor for noninvasive monitoring of blood and human tissue

    NASA Astrophysics Data System (ADS)

    Saetchnikov, Vladimir A.; Tcherniavskaia, Elina A.; Schiffner, Gerhard

    2007-05-01

    A novel concept of noninvasive monitoring of human tissue and blood based on optical diffuse reflective spectroscopy combined with metabolic heat measurements has been under development. A compact integrated fiber optical and thermal sensor has been developed. The idea of the method was to evaluate by optical spectroscopy haemoglobin and derivative concentrations and supplement with data associated with the oxidative metabolism of glucose. Body heat generated by glucose oxidation is based on the balance of capillary glucose and oxygen supply to the cells. The variation in glucose concentration is followed also by a difference from a distance (or depth) of scattered through the body radiation. So, blood glucose can be estimated by measuring the body heat and the oxygen supply. The sensor pickup contains of halogen lamp and LEDs combined with fiber optical bundle to deliver optical radiation inside and through the patient body, optical and thermal detectors. Fiber optical probe allows diffuse scattering measurement down to a depth of 2.5 mm in the skin including vascular system, which contributes to the control of the body temperature. The sensor pickup measures thermal generation, heat balance, blood flow rate, haemoglobin and derivative concentrations, environmental conditions. Multivariate statistical analysis was applied to convert various signals from the sensor pickup into physicochemical variables. By comparing the values from the noninvasive measurement with the venous plasma result, analytical functions for patient were obtained. Cluster analysis of patient groups was used to simplify a calibration procedure. Clinical testing of developed sensor is being performed.

  16. Thermal analysis of optical reference cavities for low sensitivity to environmental temperature fluctuations.

    PubMed

    Dai, Xiaojiao; Jiang, Yanyi; Hang, Chao; Bi, Zhiyi; Ma, Longsheng

    2015-02-23

    The temperature stability of optical reference cavities is significant in state-of-the-art ultra-stable narrow-linewidth laser systems. In this paper, the thermal time constant and thermal sensitivity of reference cavities are analyzed when reference cavities respond to environmental perturbations via heat transfer of thermal conduction and thermal radiation separately. The analysis as well as simulation results indicate that a reference cavity enclosed in multiple layers of thermal shields with larger mass, higher thermal capacity and lower emissivity is found to have a larger thermal time constant and thus a smaller sensitivity to environmental temperature perturbations. The design of thermal shields for reference cavities may vary according to experimentally achievable temperature stability and the coefficient of thermal expansion of reference cavities. A temperature fluctuation-induced length instability of reference cavities as low as 6 × 10(-16) on a day timescale can be achieved if a two-layer thermal shield is inserted between a cavity with the coefficient of thermal expansion of 1 × 10(-10) /K and an outer vacuum chamber with temperature fluctuation amplitude of 1 mK and period of 24 hours.

  17. Integration of design, structural, thermal and optical analysis: And user's guide for structural-to-optical translator (PATCOD)

    NASA Technical Reports Server (NTRS)

    Amundsen, R. M.; Feldhaus, W. S.; Little, A. D.; Mitchum, M. V.

    1995-01-01

    Electronic integration of design and analysis processes was achieved and refined at Langley Research Center (LaRC) during the development of an optical bench for a laser-based aerospace experiment. Mechanical design has been integrated with thermal, structural and optical analyses. Electronic import of the model geometry eliminates the repetitive steps of geometry input to develop each analysis model, leading to faster and more accurate analyses. Guidelines for integrated model development are given. This integrated analysis process has been built around software that was already in use by designers and analysis at LaRC. The process as currently implemented used Pro/Engineer for design, Pro/Manufacturing for fabrication, PATRAN for solid modeling, NASTRAN for structural analysis, SINDA-85 and P/Thermal for thermal analysis, and Code V for optical analysis. Currently, the only analysis model to be built manually is the Code V model; all others can be imported for the Pro/E geometry. The translator from PATRAN results to Code V optical analysis (PATCOD) was developed and tested at LaRC. Directions for use of the translator or other models are given.

  18. Industrial applications of fiber optics in infrared thermal monitoring

    NASA Astrophysics Data System (ADS)

    Bedrossian, John, Jr.

    1987-01-01

    The fundamental principles and practical implementation of IR temperature sensors employing fiber-optic indirect viewing are reviewed. The IR absorption and emission characteristics of different materials are discussed; the transmission of IR radiation through typical optical fibers is examined; and specific applications to turbine-blade monitoring in jet engines, injection molding and extrusion, and printed-circuit-board drilling are described in detail and illustrated with drawings. Also considered are the advantages offered by state-of-the-art two-color IR thermometry systems with bifurcated fiber links. Such devices provide accurate measurements independent of target emissivity changes, contaminants in the field of view, and target size.

  19. Optical properties of bismuth sulfide thin film prepared by thermal evaporation method

    NASA Astrophysics Data System (ADS)

    Kachari, T.; Rahman, A.

    2015-04-01

    Two types of thin films of Bi2S3 have been prepared on chemically cleaned glass substrate by thermal evaporation technique. Either by thermal evaporation of Bi2S3 powder or by thermal evaporation of bismuth and sulfur from two separate source. (Both annealed for 3 h in air inside an oven). Optical properties of these annealed films have been studied by measuring transmittance, absorbance and reflectance of the films. Optical constants such as absorption coefficient, extinction constants, refractive index, dielectric constants etc. of both types of Bi2S3 films have been calculated. Optical band gap of type (I) and (II) films have been found to be 1.647 and 1.668 eV respectively. The crystalline structure and purity of these Bi2S3 films have been studied by taking X-ray diffraction and X-ray fluorescence spectra. Surface morphology of the films has been studied by scanning electron microscopy.

  20. An optical technique to measure ion engine grid distortion due to differential thermal expansion

    NASA Technical Reports Server (NTRS)

    Trava-Airoldi, V. J.; Garner, C. E.; Pivirotto, T. J.; Brophy, J. R.

    1990-01-01

    This paper describes an optical technique developed for measuring small differential grid displacements due to thermal expansion of an ion thruster accelerator system. The technique is based on confocal scanning optical microscope type II. For the measurements of small displacements where there are distances on the order of a meter or more between the lens plane and the sample, some of the optical components are moved while the sample is kept fixed. The feasibility of applying this technique to measure the thermally induced ion thruster grid displacements was demonstrated in a bench-top simulation. It is noted that this technique can also provide information on grid movement resulting from thermal transients such as the start-up.

  1. Optical/thermal analysis methodology for a space-qualifiable RTP furnace

    NASA Technical Reports Server (NTRS)

    Bugby, D.; Dardarian, S.; Cole, E.

    1993-01-01

    A methodology to predict the coupled optical/thermal performance of a reflective cavity heating system was developed and a laboratory test to verify the method was carried out. The procedure was utilized to design a rapid thermal processing (RTP) furnace for the Robot-Operated Material Processing in Space (ROMPS) Program which is a planned STS HH-G canister experiment involving robotics and material processing in microgravity. The laboratory test employed a tungsten-halogen reflector/lamp to heat thin, p-type silicon wafers. Measurements instrumentation consisted of 5-mil Pt/Pt-Rh thermocouples and an optical pyrometer. The predicted results, utilizing an optical ray-tracing program and a lumped-capacitance thermal analyzer, showed good agreement with the measured data for temperatures exceeding 1300 C.

  2. Studies on thermal analysis and optical parameters of Cu doped poly(vinyl acetate)/polyindole composites

    NASA Astrophysics Data System (ADS)

    Bhagat, D. J.; Dhokane, G. R.

    2015-05-01

    This article reports investigation on optical parameters and thermal analysis of Cu doped poly(vinyl acetate)/polyindole composites using cupric chloride as an oxidant. The study's complex optical parameters were determined through ultraviolet-visible (UV-vis) spectroscopy. Thermal analysis was done through thermo gravimetric analysis (TGA) and differential thermal analysis (DTA). The optical band gap values were found in the range 3.4381-4.8646 eV that reflects that synthesized composites have the potential to have application in optical devices and solar cells. The optical conductivity of composites is calculated to be 1.608 × 107 S-1.

  3. Optical and thermal characterization of membrane reflector materials for solar orbit transfer vehicles

    NASA Astrophysics Data System (ADS)

    Farmer, Gregory D.; McGee, Jennie K.; Partch, Russell; Lester, Dean M.

    2002-01-01

    The Air Force Research Laboratory (AFRL), is advancing technologies to enable greater mobility for future AF spacecraft. The Solar Orbit Transfer Vehicle (SOTV) program is developing components for a concept based on a solar thermal rocket and solar thermal power generation. The program is performing ground testing of a thin film membrane concentrator concept. To better understand system performance, a series of optical characterization tests of the membrane material were performed. The objective was to quantify the relationship between membrane optical properties and the concentrator on-orbit transmission performance and thermal profile. During testing we collected reflectivity, absorptivity, transmissivity, and emissivity data for un-coated and coated membrane material. The membrane material tested was fabricated using a flight-qualified polyimide material and proven manufacturing processes. The test results, and system thermal analysis are presented in this paper. The results of this research will be used to refine hardware performance predictions and improve sizing for flight demonstration. .

  4. Optical-thermal light-tissue interactions during photoacoustic breast imaging

    PubMed Central

    Gould, Taylor; Wang, Quanzeng; Pfefer, T. Joshua

    2014-01-01

    Light-tissue interactions during photoacoustic imaging, including dynamic heat transfer processes in and around vascular structures, are not well established. A three-dimensional, transient, optical-thermal computational model was used to simulate energy deposition, temperature distributions and thermal damage in breast tissue during exposure to pulsed laser trains at 800 and 1064 nm. Rapid and repetitive temperature increases and thermal relaxation led to superpositioning effects that were highly dependent on vessel diameter and depth. For a ten second exposure at established safety limits, the maximum single-pulse and total temperature rise levels were 0.2°C and 5.8°C, respectively. No significant thermal damage was predicted. The impact of tissue optical properties, surface boundary condition and irradiation wavelength on peak temperature location and temperature evolution with time are discussed. PMID:24688817

  5. Simulation and experimental results of optical and thermal modeling of gold nanoshells.

    PubMed

    Ghazanfari, Lida; Khosroshahi, Mohammad E

    2014-09-01

    This paper proposes a generalized method for optical and thermal modeling of synthesized magneto-optical nanoshells (MNSs) for biomedical applications. Superparamagnetic magnetite nanoparticles with diameter of 9.5 ± 1.4 nm are fabricated using co-precipitation method and subsequently covered by a thin layer of gold to obtain 15.8 ± 3.5 nm MNSs. In this paper, simulations and detailed analysis are carried out for different nanoshell geometry to achieve a maximum heat power. Structural, magnetic and optical properties of MNSs are assessed using vibrating sample magnetometer (VSM), X-ray diffraction (XRD), UV-VIS spectrophotometer, dynamic light scattering (DLS), and transmission electron microscope (TEM). Magnetic saturation of synthesized magnetite nanoparticles are reduced from 46.94 to 11.98 emu/g after coating with gold. The performance of the proposed optical-thermal modeling technique is verified by simulation and experimental results.

  6. Truncated thermalization of incoherent optical waves through supercontinuum generation in photonic crystal fibers

    NASA Astrophysics Data System (ADS)

    Barviau, Benoit; Garnier, Josselin; Xu, Gang; Kibler, Bertrand; Millot, Guy; Picozzi, Antonio

    2013-03-01

    We revisit the process of optical wave thermalization through supercontinuum generation in photonic crystal fibers. We report theoretically and numerically a phenomenon of `truncated thermalization': The incoherent optical wave exhibits an irreversible evolution toward a Rayleigh-Jeans thermodynamic equilibrium state characterized by a compactly supported spectral shape. The theory then reveals the existence of a frequency cut-off which regularizes the ultraviolet catastrophe inherent to ensembles of classical nonlinear waves. This phenomenon sheds new light on the mechanisms underlying the formation of bounded supercontinuum spectra in photonic crystal fibers.

  7. Thermal and optical performance of encapsulation systems for flat-plate photovoltaic modules

    NASA Technical Reports Server (NTRS)

    Minning, C. P.; Coakley, J. F.; Perrygo, C. M.; Garcia, A., III; Cuddihy, E. F.

    1981-01-01

    The electrical power output from a photovoltaic module is strongly influenced by the thermal and optical characteristics of the module encapsulation system. Described are the methodology and computer model for performing fast and accurate thermal and optical evaluations of different encapsulation systems. The computer model is used to evaluate cell temperature, solar energy transmittance through the encapsulation system, and electric power output for operation in a terrestrial environment. Extensive results are presented for both superstrate-module and substrate-module design schemes which include different types of silicon cell materials, pottants, and antireflection coatings.

  8. The investigation of transient thermal effects in optical elements under high laser intensities

    NASA Astrophysics Data System (ADS)

    Kaskow, Mateusz; Tarka, Jan; Kwiatkowski, Jacek; Zendzian, Waldemar; Gorajek, Lukasz; Jabczynski, Jan K.

    2012-06-01

    The most important limitations in development of high energy and high power lasers based on solid state technology are thermal effects occurring under high intensity and high heat loads. The thermo-optical effects occurring inside output couplers, folding mirrors, output windows can significantly diminish the beam quality of high power lasers and therefore have to be investigated. The knowledge on transient thermal effects occurring inside bulk laser elements exposed on laser intensities of several dozens of kW/cm2 is of special interest for some specific applications (e.g. heat capacity lasers). The aims of work were theoretical analysis of those effects occurring inside the laser mirrors and its experimental verification. The hints for choice of the best materials (from the point of view of thermal limitations) for laser windows and output couplers were pointed out. The special laboratory setup enabling simultaneous registration of thermo-optical effects applying shearing interferometry and wavefront sensing by means of Shack-Hartmann test was worked out. The transient as well as averaged in time thermal-optical effects occurring inside the volume of examined element as a result of surface absorption in the coatings and bulk absorption in the material can be resolved and measured. The resolution of measurements: less than 0.1 K temperature difference and thermally induced optical power of about 0.1 D were demonstrated.

  9. Thermal optical path difference analysis of the telescope correct lens assembly

    NASA Astrophysics Data System (ADS)

    Hsu, Ming-Ying; Chang, Shenq-Tsong; Huang, Ting-Ming

    2012-12-01

    The effect of correct lens thermal optical path difference (OPD) on the optical performance of the Cassegrain telescope system is presented. The correct lens assembly includes several components such as a set of correct lenses, lens mount, spacer, mount barrel, and retainer. The heat transfer from the surrounding environment to the correct lens barrel will cause optical system aberration. The temperature distribution of the baffle is from 20.546°C to 21.485°C. Meanwhile, the off-axis ray's path of the OPD has taken the lens incidence point and emergence point into consideration. The correct lens temperature distribution is calculated by the lens barrel heat transfer analysis; the thermal distortion and stress are solved by the Finite Element Method (FEM) software. The temperature distribution is weighted to each incidence ray path, and the thermal OPD is calculated. The thermal OPD on the Z direction is transferred to optical aberration by fitting OPD into a rigid body motion and the Zernike polynomial. The aberration results can be used to evaluate the thermal effect on the correct lens assembly in the telescope system.

  10. Vibrational, electronic absorption, thermal and mechanical analyses of organic nonlinear optical material guanidinium phthalate

    NASA Astrophysics Data System (ADS)

    Devi, T. Uma; Prabha, A. Josephine; Meenakshi, R.; Kalpana, G.; Dilip, C. Surendra

    2017-02-01

    The FTIR and UV spectroscopic analysis have been carried out on guanidinium phthalate (GUP) crystal, an organic nonlinear optical material. The spectra are interpreted with the aid of normal coordinate analysis following structure optimizations and force field calculations based on density functional theory (DFT). The thermogravimetric (TG) and differential thermal analysis (DTA) ensures the thermal stability of the compound. Vickers microhardness values reveals the mechanical strength of the crystal.

  11. Thermal-stress modeling of an optical microphone at high temperature.

    SciTech Connect

    Barnard, Casey Anderson

    2010-08-01

    To help determine the capability range of a MEMS optical microphone design in harsh conditions computer simulations were carried out. Thermal stress modeling was performed up to temperatures of 1000 C. Particular concern was over stress and strain profiles due to the coefficient of thermal expansion mismatch between the polysilicon device and alumina packaging. Preliminary results with simplified models indicate acceptable levels of deformation within the device.

  12. Hybrid optical-thermal devices and materials for light manipulation and radiative cooling

    NASA Astrophysics Data System (ADS)

    Boriskina, Svetlana V.; Tong, Jonathan K.; Hsu, Wei-Chun; Weinstein, Lee; Huang, Xiaopeng; Loomis, James; Xu, Yanfei; Chen, Gang

    2015-09-01

    We report on optical design and applications of hybrid meso-scale devices and materials that combine optical and thermal management functionalities owing to their tailored resonant interaction with light in visible and infrared frequency bands. We outline a general approach to designing such materials, and discuss two specific applications in detail. One example is a hybrid optical-thermal antenna with sub-wavelength light focusing, which simultaneously enables intensity enhancement at the operating wavelength in the visible and reduction of the operating temperature. The enhancement is achieved via light recycling in the form of whispering-gallery modes trapped in an optical microcavity, while cooling functionality is realized via a combination of reduced optical absorption and radiative cooling. The other example is a fabric that is opaque in the visible range yet highly transparent in the infrared, which allows the human body to efficiently shed energy in the form of thermal emission. Such fabrics can find numerous applications for personal thermal management and for buildings energy efficiency improvement.

  13. Photopyroelectric technique for the measurement of thermal and optical properties of pigments in liquid solution.

    PubMed

    Balderas-López, J A

    2011-07-01

    The analytical solution for the one-dimensional heat diffusion problem for a two-layer system, in the Beer-Lambert model for light absorption, is shown to be useful for the implementation of a novel photopyroelectric (PPE) methodology, for the measurement of thermal and optical properties for pigments in liquid solution. The PPE signal, as a function of the sample's thickness, is used for this goal. Exponential decay for the PPE amplitude, followed by a constant PPE phase, for solutions at low dye concentration and an exponential decay for the PPE amplitude but a linear PPE phase behavior for the higher concentrated ones are shown and are, respectively, used for the measurement of the optical absorption coefficient and thermal diffusivity for liquid samples. These PPE phase behaviors also provide a criterion to decide on the corresponding limit for optical and thermal properties measurement. This PPE methodology was tested by measuring the optical absorption coefficient (at 658 nm) and thermal diffusivity for solution of methylene blue and copper sulfate in distilled water at various concentrations. Independent measurements of optical properties, using a commercial spectrometer, were done to compare with the corresponding ones obtained with this PPE methodology, finding very good agreement to each other.

  14. Health physics support for thermal shield repair at Connecticut Yankee

    SciTech Connect

    Nevelos, W.F.; Gates, W.J. )

    1988-10-01

    This article describes the radiation and safety controls used by Connecticut Yankee Atomic Power Company to support underwater repair work on the Haddam Neck Plant's core barrel thermal shield. The work was conducted by divers in the reactor cavity using remote tools and protected by a specially-constructed physical barrier that restricted their movements to a carefully defined and thoroughly surveyed area. A unique dosimetry test rig was used to determine the dose rate profiles within the work areas, and all underwater survey equipment was qualified against personnel dosimetric devices. Underwater operations were monitored and controlled by remote means (video surveillance and dosimetry telemetry), and health physics technicians were rotated through job coverage to avoid complacency and maximize training opportunities. A single, hot particle event occurred during one dive, but this was identified almost immediately and controlled to prevent excessive exposure to the diver.

  15. Thermally induced optical bistability in a new polymeric blend at room temperature

    NASA Astrophysics Data System (ADS)

    Bernini, U.; de Stefano, L.; Mormile, P.; Pierattini, G.; Russo, P.

    1993-09-01

    The transition from the transmission to the reflection regime for an Ar+-laser beam propagating in the new polymeric blend PMMA-EVA at a nonlinear interface has been observed. A comparison between the experimental data and a calculation of the input optical intensity at which this transition should occur (1.45×107 W m-2) is presented using Kaplan's theory. The results suggest the presence of thermally induced optical bistability in PMMA-EVA.

  16. Thermal Optical Properties of Lunar Dust Simulants and Their Constituents

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Ellis, Shaneise; Hanks, Nichole

    2011-01-01

    The total reflectance spectra of lunar simulant dusts (less than 20 micrometer particles) were measured in order to determine their integrated solar absorptance (alpha) and their thermal emittance (e) for the purpose of analyzing the effect of dust on the performance of thermal control surfaces. All of the simulants except one had a wavelength-dependant reflectivity (p(lambda)) near 0.10 over the wavelength range of 8 to 25 micrometers, and so are highly emitting at room temperature and lower. The 300 K emittance (epsilon) of all the lunar simulants except one ranged from 0.78 to 0.92. The exception was Minnesota Lunar Simulant 1 (MLS-1), which has little or no glassy component. In all cases the epsilon was lower for the less 20 micrometer particles than for larger particles reported earlier. There was considerably more variation in the lunar simulant reflectance in the solar spectral range (250 to 2500 nanometers) than in the thermal infrared. As expected, the lunar highlands simulants were more reflective in this wavelength range than the lunar mare simulants. The integrated solar absorptance (alpha) of the simulants ranged from 0.39 to 0.75. This is lower than values reported earlier for larger particles of the same simulants (0.41 to 0.82), and for representative mare and highlands lunar soils (0.74 to 0.91). Since the alpha of some mare simulants more closely matched that of highlands lunar soils, it is recommended that and values be the criteria for choosing a simulant for assessing the effects of dust on thermal control surfaces, rather than whether a simulant has been formulated as a highlands or a mare simulant.

  17. Thermal Optical Properties of Lunar Dust Simulants and Their Constituents

    NASA Technical Reports Server (NTRS)

    Gaier, James R.; Ellis, Shaneise; Hanks, Nichole

    2011-01-01

    The total reflectance spectra of lunar simulant dusts (< 20 mm particles) were measured in order to determine their integrated solar absorptance (alpha) and their thermal emittance (epsilon) for the purpose of analyzing the effect of dust on the performance of thermal control surfaces. All of the simulants except one had a wavelength-dependent reflectivity (p (lambda)) near 0.10 over the wavelength range of 8 to 25 microns and so are highly emitting at room temperature and lower. The 300 K emittance (epsilon) of all the lunar simulants except one ranged from 0.78 to 0.92. The exception was Minnesota Lunar Simulant 1 (MLS-1), which has little or no glassy component. In all cases the epsilon was lower for the < 20 micron particles than for larger particles reported earlier. There was considerably more variation in the lunar simulant reflectance in the solar spectral range (250 to 2500 nm) than in the thermal infrared. As expected, the lunar highlands simulants were more reflective in this wavelength range than the lunar mare simulants. The integrated solar absorptance (alpha) of the simulants ranged from 0.39 to 0.75. This is lower than values reported earlier for larger particles of the same simulants (0.41 to 0.82), and for representative mare and highlands lunar soils (0.74 to 0.91). Since the of some mare simulants more closely matched that of highlands lunar soils, it is recommended that and values be the criteria for choosing a simulant for assessing the effects of dust on thermal control surfaces, rather than whether a simulant has been formulated as a highlands or a mare simulant.

  18. Characterization of rock thermal conductivity by high-resolution optical scanning

    USGS Publications Warehouse

    Popov, Y.A.; Pribnow, D.F.C.; Sass, J.H.; Williams, C.F.; Burkhardt, H.

    1999-01-01

    We compared thress laboratory methods for thermal conductivity measurements: divided-bar, line-source and optical scanning. These methods are widely used in geothermal and petrophysical studies, particularly as applied to research on cores from deep scientific boreholes. The relatively new optical scanning method has recently been perfected and applied to geophysical problems. A comparison among these methods for determining the thermal conductivity tensor for anisotropic rocks is based on a representative collection of 80 crystalline rock samples from the KTB continental deep borehole (Germany). Despite substantial thermal inhomogeneity of rock thermal conductivity (up to 40-50% variation) and high anisotropy (with ratios of principal values attaining 2 and more), the results of measurements agree very well among the different methods. The discrepancy for measurements along the foliation is negligible (<1%). The component of thermal conductivity normal to the foliation reveals somewhat larger differences (3-4%). Optical scanning allowed us to characterize the thermal inhomogeneity of rocks and to identify a three-dimensional anisotropy in thermal conductivity of some gneiss samples. The merits of optical scanning include minor random errors (1.6%), the ability to record the variation of thermal conductivity along the sample, the ability to sample deeply using a slow scanning rate, freedom from constraints for sample size and shape, and quality of mechanical treatment of the sample surface, a contactless mode of measurement, high speed of operation, and the ability to measure on a cylindrical sample surface. More traditional methods remain superior for characterizing bulk conductivity at elevated temperature.Three laboratory methods including divided-bar, line-source and optical scanning are widely applied in geothermal and petrophysical studies. In this study, these three methods were compared for determining the thermal conductivity tensor for anisotropic rocks

  19. Structural, optical, electron paramagnetic, thermal and dielectric characterization of chalcopyrite.

    PubMed

    Prameena, B; Anbalagan, G; Gunasekaran, S; Ramkumaar, G R; Gowtham, B

    2014-03-25

    Chalcopyrite (CuFeS2) a variety of pyrite minerals was investigated through spectroscopic techniques and thermal analysis. The morphology and elemental analysis of the chalcopyrite have been done by high resolution SEM with EDAX. The lattice parameters were from the powder diffraction data (a=5.3003±0.0089 Å, c=10.3679±0.0289 Å; the volume of the unit cell=291.266 Å(3) with space group I42d (122)). The thermal decomposition behavior of chalcopyrite was studied by means of thermogravimetric analysis at three different heating rates 10, 15 and 20 °C/min. The values of effective activation energy (Ea), pre-exponential factor (ln A) for thermal decomposition have been measured at three different heating rates by employing Kissinger, Kim-Park and Flynn-Wall methods. Dielectric studies at different temperatures have also been carried out and it was found that both dielectric constant and dielectric loss decreases with the increase of frequency.

  20. Highly-efficient thermally-tuned resonant optical filters.

    PubMed

    Cunningham, John E; Shubin, Ivan; Zheng, Xuezhe; Pinguet, Thierry; Mekis, Attila; Luo, Ying; Thacker, Hiren; Li, Guoliang; Yao, Jin; Raj, Kannan; Krishnamoorthy, Ashok V

    2010-08-30

    We demonstrate spectral tunability for microphotonic add-drop filters manufactured as ring resonators in a commercial 130 nm SOI CMOS technology. The filters are provisioned with integrated heaters built in CMOS for thermal tuning. Their thermal impedance has been dramatically increased by the selective removal of the SOI handler substrate under the device footprint using a bulk silicon micromachining process. An overall ~20x increase in the tuning efficiency has been demonstrated with a 100 µm radius ring as compared to a pre-micromachined device. A total of 3.9 mW of applied tuning power shifts the filter resonant peak across one free spectral node of the device. The Q-factor of the resonator remains unchanged after the co-integration process and hence this device geometry proves to be fully CMOS compatible. Additionally, after the cointegration process our result of 2π shift with 3.9 mW power is among the best tuning performances for this class of devices. Finally, we examine scaling the tuning efficiency versus device footprint to develop a different performance criterion for an easier comparison to evaluate thermal tuning. Our criterion is defined as the unit of power to shift the device resonance by a full 2π phase shift.

  1. Optical, spectral and thermal properties of natural pumice glass

    NASA Astrophysics Data System (ADS)

    Correcher, V.; Gomez-Ros, J. M.; Dogan, T.; Garcia-Guinea, J.; Topaksu, M.

    2017-01-01

    Pumice is a natural Si-rich material displaying a complex cathodo- (CL) and thermoluminescence (TL) glow curves. The UV-IR CL emission consists of (i) a UV waveband in the range of 340-420 nm,(ii) blue band at 450-480 nm and (iii) a broad emission in the green-red region (at 550-650 nm) that could be respectively linked to Non Bridging Oxygen Hole Centers (tbnd Si-O•), self-trapped excitons and point defects (Mn2+ -0.03%- and Fe -1.15%-). Thermal treatments performed on the TL glow curves allowed us to determine that the trap system could be associated with a continuum in the trap distribution, since successive thermal pretreatments in the range of 200-310 °C induce an emission that shifts linearly to higher temperatures when the thermal pretreatment (Tstop) is increased, while the intensity of the maxima decreases similarly to the peak area. The evaluation of the Ea values, s value and the trap system calculated by VHR, IR and Glow curve fitting methods considering three possible distribution function for n(E): gaussian, exponential and uniform, has given matching values for the 280 °C TL peak.

  2. Dynamic Structural Health Monitoring of Slender Structures Using Optical Sensors

    PubMed Central

    Antunes, Paulo; Travanca, Rui; Rodrigues, Hugo; Melo, José; Jara, José; Varum, Humberto; André, Paulo

    2012-01-01

    In this paper we summarize the research activities at the Instituto de Telecomunicações—Pólo de Aveiro and University of Aveiro, in the field of fiber Bragg grating based sensors and their applications in dynamic measurements for Structural Health Monitoring of slender structures such as towers. In this work we describe the implementation of an optical biaxial accelerometer based on fiber Bragg gratings inscribed on optical fibers. The proof-of-concept was done with the dynamic monitoring of a reinforced concrete structure and a slender metallic telecommunication tower. Those structures were found to be suitable to demonstrate the feasibility of FBG accelerometers to obtain the structures' natural frequencies, which are the key parameters in Structural Health Monitoring and in the calibration of numerical models used to simulate the structure behavior. PMID:22778661

  3. Dynamic Structural Health Monitoring of slender structures using optical sensors.

    PubMed

    Antunes, Paulo; Travanca, Rui; Rodrigues, Hugo; Melo, José; Jara, José; Varum, Humberto; André, Paulo

    2012-01-01

    In this paper we summarize the research activities at the Instituto de Telecomunicações--Pólo de Aveiro and University of Aveiro, in the field of fiber Bragg grating based sensors and their applications in dynamic measurements for Structural Health Monitoring of slender structures such as towers. In this work we describe the implementation of an optical biaxial accelerometer based on fiber Bragg gratings inscribed on optical fibers. The proof-of-concept was done with the dynamic monitoring of a reinforced concrete structure and a slender metallic telecommunication tower. Those structures were found to be suitable to demonstrate the feasibility of FBG accelerometers to obtain the structures' natural frequencies, which are the key parameters in Structural Health Monitoring and in the calibration of numerical models used to simulate the structure behavior.

  4. Thermal analysis of optical polymers; DMA, MDSC and DEA

    SciTech Connect

    Harmon, J.P.; Bertolucci, P.; Gao, Hang

    1995-12-01

    A series of high refractive index, alkylated styrene polymers used in optical fibers cores is characterized along with a transparent, fluorinated alkyl methacrylate cladding polymer. The polymers were characterized by dynamic mechanical analysis (DMA), dielectric analysis (DEA) and modulated differential scanning calorimetry(MDSC). Poly(2,2,2-trifluoroethyl methacrylate) exhibited alpha, beta, and gamma transitions in the DMA and DEA spectra. These were shifted to higher temperatures than those observed in poly(ethyl methacrylate) over most of the frequencies. MDSC was used to generate reversible and irreversible heat flow versus temperature curves. These curves were used to separate the enthalpic relaxation from the glass transition for a series of these optical polymers aged at different times and temperatures.

  5. Using Thermal-Optical Analysis to Examine the OC-EC Split that Characterizes Ambient and Source Emissions Aerosols

    NASA Astrophysics Data System (ADS)

    Khan, B.; Hays, M. D.; Geron, C.; Jetter, J.

    2010-12-01

    Thermal-optical analysis (TOA) is typically used to measure OC-EC (organic carbon-elemental carbon) ratio in atmospheric aerosols. The present study utilizes a single dual-optics carbon aerosol analyzer to examine the effects of temperature-programming and optics on the OC-EC ratios. The OC-EC ratios for a variety of atmospheric and source emissions aerosols were measured using a National Institute of Occupational Safety and Health method (NIOSH 5040), the Interagency Monitoring of Protected Visual Environments method (IMPROVE), and a modified NIOSH 5040 method (referred in this paper as NIST-EPA). Use of the dual-optics instrument allowed simultaneous monitoring of the reflectance (TOR) and transmission (TOT) during each thermal protocol. Results showed no statistical difference between NIST-EPA and NIOSH OC-EC ratios for residential cookstove emissions and for an urban aerosol collected in Nairobi, Kenya. However, the OC-EC ratios for diesel exhaust (NIST [TOT and TOR]) and for a denuded rural North Carolina forest aerosol (NIST [TOT]) were significantly greater than the corresponding NIOSH values. Significantly lower IMPROVE (TOT and TOR) OC-EC ratios, compared to NIST-EPA and NIOSH, may be ascribed to the lower temperature protocol of this method. The ratio of TOT-to-TOR for the OC-EC ratio ranged between 1.37 - 1.71 (residential cookstoves), 1.05 - 1.24 (diesel exhaust), 1.63 - 2.23 (rural), and 0.80 - 1.12 (urban) for the three methods. Aerosols containing components susceptible to charring (such as water soluble organic compounds typical of rural and cookstove aerosols) tend to show the higher OC-EC variability among the methods when compared to diesel-impacted aerosols, which showed little to no detectable pyrolyzed carbon (PyC). Different sample types, due to their various chemical compositions, behave differently under dissimilar thermal and optical conditions, such that the search for a “universal” thermal-optical method for all sample types remain

  6. Carbonaceous aerosols in megacity Xi'an, China: Implications of thermal/optical protocols comparison

    NASA Astrophysics Data System (ADS)

    Han, Y. M.; Chen, L.-W. A.; Huang, R.-J.; Chow, J. C.; Watson, J. G.; Ni, H. Y.; Liu, S. X.; Fung, K. K.; Shen, Z. X.; Wei, C.; Wang, Q. Y.; Tian, J.; Zhao, Z. Z.; Prévôt, André S. H.; Cao, J. J.

    2016-05-01

    Carbonaceous aerosol is an important component that influences the environment, climate, and human health. Organic and elemental carbon (OC and EC) are the two main constituents of carbonaceous aerosols that have opposite, i.e., cooling versus warming, effects on the Earth's radiation balance. Knowledge on the variability of OC/EC splits measured by different thermal/optical protocols is useful for understanding the uncertainty in the climate models. This study shows good correlations within OC or EC (r2 > 0.83, P < 0.001) across the IMPROVE, IMPROVE_A, and EUSAAR_2 protocols for both ambient aerosol samples and biomass burning samples. However, EC concentrations differ by more than two folds, and OC/EC ratios differ up to a factor of 2.7. The discrepancies were attributed to the selection between the reflectance and transmittance corrections and the different peak inert-atmosphere temperature. The IMPROVE and IMPROVE_A protocols also quantified different char and soot concentrations, two subtypes of EC with distinct chemical and optical properties. Char, but not soot, was found to correlate with the humic-like substances (HULIS) content in the samples, suggesting that both char and HULIS originate mainly from biomass burning. A one-year (2012-2013) ambient aerosol monitoring in Xi'an, China, shows that OC, EC, and char displayed winter highs and summer lows, while soot had no seasonal trend. The char/soot ratios showed a "single peak" in winter, while OC/EC ratios exhibited "dual peak" feature due to the influence of secondary organic aerosol formation. In addition to commonly measured OC and EC, we recommend both char and soot from a common reference method to be considered in the chemical transport and climate models.

  7. Thermal characterization of micro/nanoscale conductive and non-conductive wires based on optical heating and electrical thermal sensing

    NASA Astrophysics Data System (ADS)

    Hou, Jinbo; Wang, Xinwei; Guo, Jiaqi

    2006-08-01

    In this work, a technique based on optical heating and electrical thermal sensing (OHETS) is developed to characterize the thermophysical properties of one-dimensional micro/nanoscale conductive and non-conductive wires. In this method, the to-be-measured thin wire is suspended over two electrodes and is irradiated with a periodically modulated laser beam. The laser beam induces a periodical temperature variation in the wire/tube, which will lead to a periodical change in its electrical resistance. A dc current is applied to the sample, and the resulting periodical voltage variation over the wire is measured and used to extract the thermophysical properties of the wire/tube. A 25.4 µm thick platinum wire is used as the reference sample to verify this technique. Sound agreement is obtained between the measured thermal conductivity and the reference value. Applying the OHETS technique, the thermal diffusivity of conductive single-wall carbon nanotube (SWCNT) bundles and non-conductive human hair and cloth fibres are measured. For non-conductive wires, a thin (~nm) metallic film is coated at the outside of the wire for electrical thermal sensing. The measured thermal diffusivities for three different SWCNT bundles are 2.98 × 10-5 m2 s-1, 4.41 × 10-5 m2 s-1 and 6.64 × 10-5 m2 s-1. These values are much less than the thermal diffusivity of graphite in the layer direction. For human hair and microscale cloth fibres, our experiments show that their thermal diffusivities are at the level of 10-6 m2 s-1.

  8. Chemical and optical properties of thermally evaporated manganese oxide thin films

    SciTech Connect

    Al-Kuhaili, M. F.

    2006-09-15

    Manganese oxide thin films were deposited using thermal evaporation from a tungsten boat. Films were deposited under an oxygen atmosphere, and the effects of thickness, substrate temperature, and deposition rate on their properties were investigated. The chemical properties of the films were studied using x-ray photoelectron spectroscopy and x-ray fluorescence. The optical properties were determined from normal-incidence transmittance and reflectance. Based on the chemical and optical characterizations, the optimum conditions for the deposition of the films were investigated. Subsequently, the optical properties (refractive index, extinction coefficient, and band gap) of these films were determined.

  9. All-optical beam deflection method for simultaneous thermal conductivity and thermo-optic coefficient ( d n / d T ) measurements

    NASA Astrophysics Data System (ADS)

    Putnam, Shawn A.; Fairchild, Steven B.; Arends, Armando A.; Urbas, Augustine M.

    2016-05-01

    This work describes an all-optical beam deflection method to simultaneously measure the thermal conductivity ( Λ) and thermo-optic coefficient ( d n / d T ) of materials that are absorbing at λ = 10.6 μm and are transparent to semi-transparent at λ = 632.8 nm. The technique is based on the principle of measuring the beam deflection of a probe beam (632.8 nm) in the frequency-domain due to a spatially and temporally varying index gradient that is thermally induced by 50:50 split pump beam from a CO2 laser (10.6 μm). The technique and analysis methods are validated with measurements of 10 different optical materials having Λ and d n / d T properties ranging between 0.7 W/m K ≲ Λ ≲ 33.5 W/m K and -12 × 10-6 K-1 ≲ d n / d T ≲ 14 × 10-6 K-1, respectively. The described beam deflection technique is highly related to other well-established, all-optical materials characterization methods, namely, thermal lensing and photothermal deflection spectroscopy. Likewise, due to its all-optical, pump-probe nature, it is applicable to materials characterization in extreme environments with minimal errors due to black-body radiation. In addition, the measurement principle can be extended over a broad range of electromagnetic wavelengths (e.g., ultraviolet to THz) provided the required sources, detectors, and focusing elements are available.

  10. Audio-band coating thermal noise measurement for Advanced LIGO with a multimode optical resonator

    NASA Astrophysics Data System (ADS)

    Gras, S.; Yu, H.; Yam, W.; Martynov, D.; Evans, M.

    2017-01-01

    In modern high precision optical instruments, such as in gravitational wave detectors or frequency references, thermally induced fluctuations in the reflective coatings can be a limiting noise source. This noise, known as coating thermal noise, can be reduced by choosing materials with low mechanical loss. Examination of new materials becomes a necessity in order to further minimize the coating thermal noise and thus improve sensitivity of next generation instruments. We present a novel approach to directly measure coating thermal noise using a high finesse folded cavity in which multiple Hermite-Gaussian modes coresonate. This method is used to probe surface fluctuations on the order 10-17 m /√{Hz } in the frequency range 30-400 Hz. We applied this technique to measure thermal noise and loss angle of the coating used in Advanced LIGO.

  11. Fiber-reinforced composite analysis using optical coherence tomography after mechanical and thermal cycling

    NASA Astrophysics Data System (ADS)

    Kyotoku, B. B. C.; Braz, A. K. S.; Braz, R.; Gomes, A. S. L.

    2007-02-01

    Fiber-reinforced composites are new materials which have been used for a variety of dental applications, including tooth splinting, replacement of missing teeth, treatment of dental emergencies, reinforcement of resin provisional fixed prosthodontic restorations, orthodontic retention, and other clinical applications. Different fiber types are available, but little clinical information has been disseminated. The traditional microscopy investigation, most commonly used to study this material, is a destructive technique, which requires specimen sectioning and are essentially surface measurements. On the basis of these considerations, the aim of this research is to analyze the interior of a dental sample reinforced with fiber after a mechanical and thermal cycling to emulate oral conditions using optical coherence tomography (OCT). The device we are using is a home built Fourier domain OCT working at 800 nm with 6 μm resolution. The results are compared with microscopy images to validate OCT as a working method. In long term, fractures allow bacterial invasion provoking plaque and calculus formation that can cause caries and periodontal disease. Therefore, non invasive imaging of the bridge fiber enables the possibility of periodic clinical evaluation to ensure the patient health. Furthermore, OCT images can provide a powerful method for quantitative analysis of crack propagation, and can potentially be used for in vivo assessment.

  12. Thermal Stabilization in a High Vacuum Cryogenic Optical System

    NASA Astrophysics Data System (ADS)

    Wallace, Rosa; Cripe, Jonathan; Corbitt, Thomas

    2016-03-01

    The existing technology for gravitational wave detection is limited in part by quantum noise. In our tabletop experiments, we are attempting to lower the noise floor to the quantum limit through the use of a seismically isolated cryogenic high vacuum environment, with the intention of exploring different methods to reduce quantum noise. In the development phase of this environment, we have implemented a customized strategy of ultraviolet irradiation combined with cryogenically cooled radiation shielding to reduce the impact of water vapor and blackbody radiation on the thermal stability of the cryogenic micro-components. Supported by National Science Foundation REU Site #1262890 and CAREER Award #1150531.

  13. Optical and thermal design of light emitting diodes omnidirectional bulb.

    PubMed

    Ye, Zhi Ting; Kuo, Hao-Chung; Chen, Cheng-Huan

    2015-10-01

    The penetration of LED light bulbs into the lighting market is growing quickly in recent years due to significant increase of LED efficiency and reduction of cost. One major issue to be improved is the overall light bulb efficiency, which can fulfill "Energy Star for Lamps" while keeping sufficiently high efficiency. The efficiency issue results mainly from the high directionality of the LED sources and the corresponding solutions to make the emission more diverse. In this paper, a diffusion white reflection sheet (DWRS) with an array of holes is proposed as a high efficiency solution for modulating a light emission profile with SMD type LED source. The hole size is adjusted with fixed hole pitch to both maximize the efficiency and meet the omnidirectional specification. In addition, the concept of thermal plastic insertion molding metal is proposed for thermal management without fins for cooling. The prototype demonstrates the efficiency (Ef.) of 87.6% and LED pad temperature of 85°C, which shows the feasibility as a total solution for high efficiency LED omnidirectional bulbs.

  14. Thermal, mechanical, electrical, linear and nonlinear optical properties of a nonlinear optical L-ornithine monohydrochloride single crystal

    NASA Astrophysics Data System (ADS)

    Senthil, S.; Pari, S.; Joseph, Ginson P.; Sagayaraj, P.; Madhavan, J.

    2009-08-01

    Optically transparent semiorganic nonlinear optical bulk single crystal of L-ornithine monohydrochloride (LOMHCL) of dimension 11×3×2 mm 3 has been grown from its aqueous solution by slow solvent evaporation technique. The grown crystal was characterized by powder X-ray diffraction to confirm the crystal structure. Investigation has been carried out to assign the vibrational frequencies of the grown crystals by Fourier transform infrared spectroscopy technique. Thermal behavior of the grown crystals was studied by thermogravimetric analysis. The second harmonic generation (SHG) efficiency of LOMHCL was determined by Kurtz and Perry powder technique. The optical absorption study confirms the suitability of the crystal for device applications. The mechanical properties of the grown crystals have been studied using Vickers microhardness tester. Dielectric and photoconductivity studies are also carried out for the grown samples.

  15. Thermal lens elimination by gradient-reduced zone coupling of optical beams

    DOEpatents

    Page, Ralph H.; Beach, Raymond J.

    2000-01-01

    A thermal gradient-reduced-zone laser includes a laser medium and an optically transparent plate with an index of refraction that is less than the index of refraction of the laser medium. The pump face of the laser medium is bonded to a surface of the optically transparent member. Pump light is directed through the transparent plate to optically pump the solid state laser medium. Heat conduction is mainly through the surface of the laser medium where the heat is introduced by the pump light. Heat flows in a direction opposite to that of the pump light because the side of the laser medium that is opposite to that of the pump face is not in thermal contact with a conductor and thus there is no heat flux (and hence, no temperature gradient), thus producing a thermal gradient-reduced zone. A laser cavity is formed around the laser medium such that laser light oscillating within the laser cavity reflects by total-internal-reflection from the interface between the pump face and the optically transparent plate and enters and exits through a thermal gradient-reduced zone.

  16. Optic phonons and anisotropic thermal conductivity in hexagonal Ge2Sb2Te5

    DOE PAGES

    Mukhopadhyay, Saikat; Lindsay, Lucas R.; Singh, David

    2016-11-16

    The lattice thermal conductivity ($κ$) of hexagonal Ge2Sb2Tesub>5 (h-GST) is studied via direct first-principles calculations. We find significant intrinsic anisotropy of ( $κ$a/$κ$c~2) of $κ$ in bulk h-GST along different transport directions. The dominant contribution to$κ$ is from optic phonons, ~75%. This is extremely unusual as the acoustic phonon modes carry most of the heat in typical semiconductors and insulators with small unit cells. Very recently, Lee et. al. observed anisotropic in GST thin films and attributed this to thermal resistance of amorphous regions near grain boundaries. However, our results suggest an additional strong intrinsic anisotropy for the pure hexagonalmore » phase. This derives from bonding anisotropy along different crystal directions, specifically from weak interlayer coupling, which gives anisotropic phonon dispersions. The phonon spectrum of h-GST has very dispersive optic branches with higher group velocities along the a-axis as compared to flat optic bands along the c-axis. The importance of optic mode contributions for the thermal conductivity in low-$κ$ h-GST is unusual, and development of fundamental physical understanding of these contributions may be critical to better understanding of thermal conduction in other complex layered materials.« less

  17. Optically induced thermal response of Chlorophyll for biomedical applications

    NASA Astrophysics Data System (ADS)

    Tu, Chiawei; Md Ehsan, Sadat; Zhao, Yuan; Shi, Donglu; Mast, David

    The heating behavior of Chlorophyll was investigated for possible use in hyperthermia cancer treatments. One measure of hyperthermia effectiveness is the Specific Absorption Rate (SAR) defined as the initial slope of the sample heating behavior, however, for nanoparticle (NP) loaded samples, this initial heating rate is often limited by heat transfer mechanisms from the NPs to the surrounding material and not the initial NP heating. This is especially true for water-based, NP loaded tissue surrogates. Organic solvent dispersed NP loaded samples face the additional problem of heating rate variations due to solvent evaporation effects. We report on measurements of the initial optical heating rates of Chlorophyll and deposited directly on small, Pt thin film resistance temperature detectors (RTDs). Solid state lasers (638 nm and 655 nm) were used to illuminate these samples at different intensities and at specific wavelengths associated with peaks (662 nm) in Chlorophyll's UV-VIS optical absorption spectra while recording the RTD resistance at 0.1 second intervals. This technique significantly reduce evaporation errors we had experienced and has the potential to directly measure the heating behavior of Chlorophyll based NP materials.

  18. Aerosol absorption measurement with a sinusoidal phase modulating fiber optic photo thermal interferometer

    NASA Astrophysics Data System (ADS)

    Li, Shuwang; Shao, Shiyong; Mei, Haiping; Rao, Ruizhong

    2016-10-01

    Aerosol light absorption plays an important role in the earth's atmosphere direct and semi-direct radiate forcing, simultaneously, it also has a huge influence on the visibility impairment and laser engineering application. Although various methods have been developed for measuring aerosol light absorption, huge challenge still remains in precision, accuracy and temporal resolution. The main reason is that, as a part of aerosol light extinction, aerosol light absorption always generates synchronously with aerosol light scattering, and unfortunately aerosol light scattering is much stronger in most cases. Here, a novel photo-thermal interferometry is proposed only for aerosol absorption measurement without disturbance from aerosol scattering. The photo-thermal interferometry consists of a sinusoidal phase-modulating single mode fiber-optic interferometer. The thermal dissipation, caused by aerosol energy from photo-thermal conversion when irritated by pump laser through interferometer, is detected. This approach is completely insensitive to aerosol scattering, and the single mode fiber-optic interferometer is compact, low-cost and insensitive to the polarization shading. The theory of this technique is illustrated, followed by the basic structure of the sinusoidal phase-modulating fiber-optic interferometer and demodulation algorithms. Qualitative and quantitative analysis results show that the new photo-thermal interference is a potential approach for aerosol absorption detection and environmental pollution detection.

  19. Towards Estimating Water Stress through Leaf and Canopy Water Content Derived from Optical and Thermal Hyperspectral Data

    NASA Astrophysics Data System (ADS)

    Corbin, Amie; Timmermans, Joris; van der Tol, Christiaan; Verhoef, Wout

    2015-04-01

    , PROSPECT-VISIR, an extended version of the PROSPECT model has been developed, extending the range to 5.7µm. However, this model is yet to be validated other than in the original publication. The goal of this research is to examine the biophysical property of leaf and canopy water content as an indicator of plant health through analysis of leaf spectra in the optical and thermal range. The MIDAC FTIR (3 - 20µm) and ASD spectrometer (0.35 - 2.5µm) were used to measure the thermal and optical ranges, respectively, of individual leaf spectra. A relationship between the measured spectra and leaf water content is to be analyzed. In addition, the PROPSECT-VISIR model is to be utilized along with SAIL to analyze the applications of the spectra in radiation transfer models, and to validate the recent PROSPECT-VISIR model.

  20. Optical testing of the Kepler Photometer in a thermal vacuum environment at Ball Aerospace

    NASA Astrophysics Data System (ADS)

    Martella, Mark A.; Byrd, Don A.; Willis, Stew; Spuhler, Peter; Siegel, Noah; Stewart, Chris

    2009-08-01

    The Kepler spacecraft and telescope were designed, built and tested at Ball Aerospace & Technologies Corporation in Boulder, Colorado. The Kepler spacecraft was successfully launched from NASA's Kennedy Space Center on March 6, 2009. In order to adequately support the Kepler mission, Ball Aerospace upgraded its optical testing capabilities. This upgrade facilitated the development of a meter-class optical testing capability in a thermal vacuum (TVAC) environment. This testing facility, known as the Vertical Collimator Assembly (VCA), was used to test the Kepler telescope in 2008. Ball Aerospace designed and built the VCA as a 1.5m, f/4.5 collimator that is an un-obscured system, incorporating an off-axis parabola (OAP) and test flat coated for operations in the VIS-IR wavelength region. The VCA is operated in a large thermal vacuum chamber and has an operational testing range of 80 to 300K (-315 to 80°F). For Kepler testing, the VCA produced a 112nm rms wavefront at cryogenic temperatures. Its integral autocollimation and alignment capabilities allowed knowledge of the collimated wavefront characteristics to <5nm rms during final thermal vacuum testing. Upcoming modifications to the VCA optics will bring the VCA wavefront to <20nm rms. The VCA optics are designed and mounted to allow for use in either a vertical or horizontal orientation without degradation of the collimated optical wavefront.

  1. Thermal, Structural, and Optical Analysis of a Balloon-Based Imaging System

    NASA Astrophysics Data System (ADS)

    Borden, Michael; Lewis, Derek; Ochoa, Hared; Jones-Wilson, Laura; Susca, Sara; Porter, Michael; Massey, Richard; Clark, Paul; Netterfield, Barth

    2017-03-01

    The Subarcsecond Telescope And BaLloon Experiment, STABLE, is the fine stage of a guidance system for a high-altitude ballooning platform designed to demonstrate subarcsecond pointing stability over one minute using relatively dim guide stars in the visible spectrum. The STABLE system uses an attitude rate sensor and the motion of the guide star on a detector to control a Fast Steering Mirror to stabilize the image. The characteristics of the thermal-optical-mechanical elements in the system directly affect the quality of the point-spread function of the guide star on the detector, so a series of thermal, structural, and optical models were built to simulate system performance and ultimately inform the final pointing stability predictions. This paper describes the modeling techniques employed in each of these subsystems. The results from those models are discussed in detail, highlighting the development of the worst-case cold and hot cases, the optical metrics generated from the finite element model, and the expected STABLE residual wavefront error and decenter. Finally, the paper concludes with the predicted sensitivities in the STABLE system, which show that thermal deadbanding, structural pre-loading, and self-deflection under different loading conditions, and the speed of individual optical elements were particularly important to the resulting STABLE optical performance.

  2. Electronic, Optical, and Thermal Properties of Reduced-Dimensional Semiconductors

    NASA Astrophysics Data System (ADS)

    Huang, Shouting

    Reduced-dimensional materials have attracted tremendous attention because of their new physics and exotic properties, which are of great interests for fundamental science. More importantly, the manipulation and engineering of matter on an atomic scale yield promising applications for many fields including nanoelectronics, nanobiotechnology, environments, and renewable energy. Because of the unusual quantum confinement and enhanced surface effect of reduced-dimensional materials, traditional empirical models suffer from necessary but unreliable parameters extracted from previously-studied bulk materials. In this sense, quantitative, parameter-free approaches are highly useful for understanding properties of reduced-dimensional materials and, furthermore, predicting their novel applications. The first-principles density functional theory (DFT) is proven to be a reliable and convenient tool. In particular, recent progress in many-body perturbation theory (MBPT) makes it possible to calculate excited-state properties, e.g., quasiparticle (QP) band gap and optical excitations, by the first-principles approach based on DFT. Therefore, during my PhD study, I employed first-principles calculations based on DFT and MBPT to systematically study fundamental properties of typical reduced-dimensional semiconductors, i.e., the electronic structure, phonons, and optical excitations of core-shell nanowires (NWs) and graphene-like two-dimensional (2D) structures of current interests. First, I present first-principles studies on how to engineer band alignments of nano-sized radial heterojunctions, Si/Ge core-shell NWs. Our calculation reveals that band offsets in these one-dimensional (1D) nanostructures can be tailored by applying axial strain or varying core-shell sizes. In particular, the valence band offset can be efficiently tuned across a wide range and even be diminished via applied strain. Two mechanisms contribute to this tuning of band offsets. Furthermore, varying the

  3. Optical and thermal response of single-walled carbon nanotube-copper sulfide nanoparticle hybrid nanomaterials.

    PubMed

    Tseng, Yi-Hsuan; He, Yuan; Lakshmanan, Santana; Yang, Chang; Chen, Wei; Que, Long

    2012-11-16

    This paper reports the optical and thermal response of a single-walled carbon nanotube-copper sulfide nanoparticle (SWNT-CuS NP) hybrid nanomaterial and its application as a thermoelectric generator. The hybrid nanomaterial was synthesized using oleylamine molecules as the linker molecules between SWNTs and CuS NPs. Measurements found that the hybrid nanomaterial has significantly increased light absorption (up to 80%) compared to the pure SWNT. Measurements also found that the hybrid nanomaterial thin-film devices exhibit a clear optical and thermal switching effect, which can be further enhanced up to 10 ×  by asymmetric illumination of light and thermal radiation on the thin-film devices instead of symmetric illumination. A simple prototype thermoelectric generator enabled by the hybrid nanomaterials is demonstrated, indicating a new route for achieving thermoelectricity.

  4. Thermal stability of the solid DNA as a novel optical material

    NASA Astrophysics Data System (ADS)

    Nizioł, Jacek; Makyła-Juzak, Katarzyna; Marzec, Mateusz M.; Ekiert, Robert; Marzec, Monika; Gondek, Ewa

    2017-04-01

    Deoxyribonucleic acid (DNA) has been extensively exploited for the past decade as the matrix material in organic electronics and nonlinear optics. In this work thermal stability of DNA in solid form was thoroughly studied, mainly by optical methods. Solid samples of low molecular mass DNA were subjected to heating according to different protocols and dissolved. The temperature effect was observed in the evolution of UV absorption and circular dichroism spectra. Thin films of DNA were deposited on polished silicon wafers. They were conditioned at consecutively raised temperature and simultaneously measured by spectroscopic ellipsometry. Changes in chemical composition of thermally treated films were studied by XPS. Below 100 °C all thermal effects were reversible. Melting occurred at c.a.140 °C. Irreversible chemical changes probably occurred at 170-180 °C.

  5. Tunable organization of cellulose nanocrystals for controlled thermal and optical response

    NASA Astrophysics Data System (ADS)

    Diaz A., Jairo A.

    The biorenewable nature of cellulose nanocrystals (CNCs) has opened up new opportunities for cost-effective, sustainable materials design. By taking advantage of their distinctive structural properties and self-assembly, promising applications have started to nurture the fields of flexible electronics, biomaterials, and nanocomposites. CNCs exhibit two fundamental characteristics: rod-like morphology (5-20 nm wide, 50-500 nm long), and lyotropic behavior (i.e., liquid crystalline mesophases formed in solvents), which offer unique opportunities for structural control and fine tuning of thermal and optical properties based on a proper understanding of their individual behavior and interactions at different length scales. In the present work, we attempt to provide an integral description of the influence of single crystals in the thermal and optical response exhibited by nanostructured films. Our approach involved the connection of experimental evidence with predictions of molecular dynamics (MD) simulations. In order to assess the effect of CNC orientation in the bulk response, we produced cellulose nanostructured films under two different mechanisms, namely, self-organization and shear orientation. Self-organized nanostructured films exhibited the typical iridescent optical reflection generated by chiral nematic organization. Shear oriented films disrupted the cholesteric organization, generating highly aligned structures with high optical transparency. The resultant CNC organization present in all nanostructured films was estimated by a second order statistical orientational distribution based on two- dimensional XRD signals. A new method to determine the coefficient of thermal expansion (CTE) in a contact-free fashion was developed to properly characterize the thermal expansion of thin soft films by excluding other thermally activated phenomena. The method can be readily extended to other soft materials to accurately measure thermal strains in a non

  6. 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}.

  7. 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.

  8. Two-dimensional optical thermal ratchets based on Fibonacci spirals.

    PubMed

    Xiao, Ke; Roichman, Yael; Grier, David G

    2011-07-01

    An ensemble of symmetric potential energy wells arranged at the vertices of a Fibonacci spiral can serve as the basis for an irreducibly two-dimensional thermal ratchet. Periodic rotation of the potential energy landscape through a three-step cycle drives trapped Brownian particles along spiral trajectories through the pattern. Which spiral is selected depends on the angular displacement at each step, with transitions between selected spirals arising at rational proportions of the golden angle. Fibonacci spiral ratchets therefore display an exceptionally rich range of transport properties, including inhomogeneous states in which different parts of the pattern induce motion in different directions. Both the radial and angular components of these trajectories can undergo flux reversal as a function of the scale of the pattern or the rate of rotation.

  9. Health information management using optical storage technology: case studies.

    PubMed

    Kohn, D

    1992-05-01

    All the health care facilities examined in the case studies addressed several important organizational issues before and during the installation of their systems. All the facilities examined employee commitment. The prudent managers considered how easily their employees adapt to changes in their jobs and work environment. They considered how enthusiastic cooperation can be fostered in the creation of a liberated and reengineered office. This was determined not only by each individual's reaction to change, but also by the health care facility's track record with other system installations. For example, document image, diagnostic image, and coded data processing systems allow the integration of divergent health care information systems within complex institutions. Unfortunately, many institutions are currently struggling with how to create an information management architecture that will integrate their mature systems, such as their patient care and financial systems. Information managers must realize that if optical storage technology-based systems are used in a strategic and planned fashion, these systems can act as focal points for systems integration, not as promises to further confuse the issue. Another issue that needed attention in all the examples was the work environment. The managers considered how the work environment was going to affect the ability to integrate optical image and data systems into the institution. For example, many of these medical centers have created alliances with clinics, HMOs, and large corporate users of medical services. This created a demand for all or part of the health information outside the confines of the original institution. Since the work environment is composed of a handful of factors such as merged medical services, as many work environment factors as possible were addressed before application of the optical storage technology solution in the institutions. And finally, the third critical issue was the organization of work

  10. Development of surface thermal lensing technique in absorption and defect analyses of optical coatings

    NASA Astrophysics Data System (ADS)

    He, Hongbo; Li, Xia; Fan, Shuhai; Shao, Jianda; Zhao, Yuanan; Fan, Zhengxiu

    2005-12-01

    Absorption is one of the main factors which cause damage to optical coatings, under the radiation of high power lasers. Surface thermal lensing (STL) technique was developed into a practical high-sensitivity apparatus for the weak absorption analysis of optical coatings. A 20 W continuous-wave 1064 nm Nd:YAG laser and a 30 mW He-Ne laser were employed as pump source and probe source, respectively. Low noise photoelectrical components and an SR830 DSP lock-in amplifier were used for photo-thermal deformation signal detection. In order to improve sensitivity, the configuration of the apparatus was optimized through choosing appropriate parameters, that including pump beam spot size, chopper frequency, detection distance, waist radius and position of probe beam. Coating samples were mounted on an x-y stage which was driven by high precision stepper motors. Different processes of absorption measurements, including single spot, linear scan and 2-dimension area scan, could be performed manually or automatically under the control of PC program. Various optical coatings were prepared by both electron beam evaporation and ion beam sputtering deposition. High sensitivity was obtained and low to 10 ppb absorption could be measured by surface thermal lensing technique. And a spatial resolution of 25 micron was proved according to the area scanning which traced out the profile of photo-thermal defects inside optical coatings. The system was employed in the analyses of optical absorption, absorption uniformity and defect distribution, and revealed the relationship between laser-induced damage and absorption of optical coatings.

  11. Thermal strain along optical fiber in lightweight composite FOG : Brillouin-based distributed measurement and finite element analysis

    NASA Astrophysics Data System (ADS)

    Minakuchi, Shu; Sanada, Teruhisa; Takeda, Nobuo; Mitani, Shinji; Mizutani, Tadahito; Sasaki, Yoshinobu; Shinozaki, Keisuke

    2014-05-01

    Thermal strain significantly affects stability of fiber optic gyroscope (FOG) performance. This study investigates thermal strain development in a lightweight carbon fiber reinforced plastic (CFRP) FOG under thermal vacuum condition simulating space environment. First, we measure thermal strain distribution along an optical fiber in a CFRP FOG using a Brillouin-based high-spatial resolution system. The key strain profile is clarified and the strain development is simulated using finite element analysis. Finally, several constituent materials for FOG are quantitatively compared from the aspect of the maximum thermal strain and the density, confirming the clear advantage of CFRP.

  12. A method for studying the effects of thermal deformations on optical systems for space application

    NASA Astrophysics Data System (ADS)

    Segato, Elisa; Da Deppo, Vania; Debei, Stefano; Cremonese, Gabriele

    2010-04-01

    Optical instruments for space missions work in hostile environment, it's thus necessary to accurately study the effects of ambient parameters variations on the equipment performance. In particular, optical instruments are very sensitive to ambient conditions, especially temperature. This variable can cause dilatation and misalignment of the optical elements, and can also lead to rise of dangerous stresses in the optics. Optical elements displacements and surface deformations degrade the quality of the sampled images. In this work a method for simulating and studying the effects of the thermal deformations, particularly the impact on the expected optical performance, is presented. Optical elements and their mountings are modelled and processed by a thermo-mechanical Finite Element Model (FEM) analysis, reproducing expected operative conditions. The FEM output is elaborated into a MATLAB optimisation code; a non-linear least square algorithm is used to determine the equation of the best fitting nth degree polynomial, or the spherical surface of the deformed lenses and mirrors; model accuracy is 10-8 m. The obtained mathematical surface representations are then directly imported into ZEMAX raytracing software for sequential raytrace analysis. The results are spot diagrams, chief ray coordinates on the detector, MTF curves and Diffraction Encircled Energy variations due to simulated thermal loads. This analysis helps to design and compare different optical housing systems for finding a feasible mounting solution. The described method has been applied successfully to the optics and mountings of a stereo-camera for the BepiColombo mission. Different types of lenses and prisms constraints have been designed and analysed. The results show the preferable use of kinematic constraints, instead of using glue, to correctly maintain the instrument focus in orbit around Mercury considering an operative temperature range between -20°C and +30°C.

  13. Thermal, chemical, and optical properties of Crater Lake, Oregon

    USGS Publications Warehouse

    Larson, G.L.; Hoffman, R.L.; McIntire, D.C.; Buktenica, M.W.; Girdner, S.F.

    2007-01-01

    Crater Lake covers the floor of the Mount Mazama caldera that formed 7700 years ago. The lake has a surface area of 53 km2 and a maximum depth of 594 m. There is no outlet stream and surface inflow is limited to small streams and springs. Owing to its great volume and heat, the lake is not covered by snow and ice in winter unlike other lakes in the Cascade Range. The lake is isothermal in winter except for a slight increase in temperature in the deep lake from hyperadiabatic processes and inflow of hydrothermal fluids. During winter and spring the water column mixes to a depth of about 200-250 m from wind energy and convection. Circulation of the deep lake occurs periodically in winter and spring when cold, near-surface waters sink to the lake bottom; a process that results in the upwelling of nutrients, especially nitrate-N, into the upper strata of the lake. Thermal stratification occurs in late summer and fall. The maximum thickness of the epilimnion is about 20 m and the metalimnion extends to a depth of about 100 m. Thus, most of the lake volume is a cold hypolimnion. The year-round near-bottom temperature is about 3.5??C. Overall, hydrothermal fluids define and temporally maintain the basic water quality characteristics of the lake (e.g., pH, alkalinity and conductivity). Total phosphorus and orthophosphate-P concentrations are fairly uniform throughout the water column, where as total Kjeldahl-N and ammonia-N are highest in concentration in the upper lake. Concentrations of nitrate-N increase with depth below 200 m. No long-term changes in water quality have been detected. Secchi disk (20-cm) clarity varied seasonally and annually, but was typically highest in June and lowest in August. During the current study, August Secchi disk clarity readings averaged about 30 m. The maximum individual clarity reading was 41.5 m in June 1997. The lowest reading was 18.1 m in July 1995. From 1896 (white-dinner plate) to 2003, the average August Secchi disk reading was

  14. Optical Fiber Sensors for Aircraft Structural Health Monitoring

    PubMed Central

    García, Iker; Zubia, Joseba; Durana, Gaizka; Aldabaldetreku, Gotzon; Illarramendi, María Asunción; Villatoro, Joel

    2015-01-01

    Aircraft structures require periodic and scheduled inspection and maintenance operations due to their special operating conditions and the principles of design employed to develop them. Therefore, structural health monitoring has a great potential to reduce the costs related to these operations. Optical fiber sensors applied to the monitoring of aircraft structures provide some advantages over traditional sensors. Several practical applications for structures and engines we have been working on are reported in this article. Fiber Bragg gratings have been analyzed in detail, because they have proved to constitute the most promising technology in this field, and two different alternatives for strain measurements are also described. With regard to engine condition evaluation, we present some results obtained with a reflected intensity-modulated optical fiber sensor for tip clearance and tip timing measurements in a turbine assembled in a wind tunnel. PMID:26134107

  15. Optical Fiber Sensors for Aircraft Structural Health Monitoring.

    PubMed

    García, Iker; Zubia, Joseba; Durana, Gaizka; Aldabaldetreku, Gotzon; Illarramendi, María Asunción; Villatoro, Joel

    2015-06-30

    Aircraft structures require periodic and scheduled inspection and maintenance operations due to their special operating conditions and the principles of design employed to develop them. Therefore, structural health monitoring has a great potential to reduce the costs related to these operations. Optical fiber sensors applied to the monitoring of aircraft structures provide some advantages over traditional sensors. Several practical applications for structures and engines we have been working on are reported in this article. Fiber Bragg gratings have been analyzed in detail, because they have proved to constitute the most promising technology in this field, and two different alternatives for strain measurements are also described. With regard to engine condition evaluation, we present some results obtained with a reflected intensity-modulated optical fiber sensor for tip clearance and tip timing measurements in a turbine assembled in a wind tunnel.

  16. Fiber optic sensors for structural health monitoring of air platforms.

    PubMed

    Guo, Honglei; Xiao, Gaozhi; Mrad, Nezih; Yao, Jianping

    2011-01-01

    Aircraft operators are faced with increasing requirements to extend the service life of air platforms beyond their designed life cycles, resulting in heavy maintenance and inspection burdens as well as economic pressure. Structural health monitoring (SHM) based on advanced sensor technology is potentially a cost-effective approach to meet operational requirements, and to reduce maintenance costs. Fiber optic sensor technology is being developed to provide existing and future aircrafts with SHM capability due to its unique superior characteristics. This review paper covers the aerospace SHM requirements and an overview of the fiber optic sensor technologies. In particular, fiber Bragg grating (FBG) sensor technology is evaluated as the most promising tool for load monitoring and damage detection, the two critical SHM aspects of air platforms. At last, recommendations on the implementation and integration of FBG sensors into an SHM system are provided.

  17. Fiber Optic Sensors for Structural Health Monitoring of Air Platforms

    PubMed Central

    Guo, Honglei; Xiao, Gaozhi; Mrad, Nezih; Yao, Jianping

    2011-01-01

    Aircraft operators are faced with increasing requirements to extend the service life of air platforms beyond their designed life cycles, resulting in heavy maintenance and inspection burdens as well as economic pressure. Structural health monitoring (SHM) based on advanced sensor technology is potentially a cost-effective approach to meet operational requirements, and to reduce maintenance costs. Fiber optic sensor technology is being developed to provide existing and future aircrafts with SHM capability due to its unique superior characteristics. This review paper covers the aerospace SHM requirements and an overview of the fiber optic sensor technologies. In particular, fiber Bragg grating (FBG) sensor technology is evaluated as the most promising tool for load monitoring and damage detection, the two critical SHM aspects of air platforms. At last, recommendations on the implementation and integration of FBG sensors into an SHM system are provided. PMID:22163816

  18. 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

  19. Thermally Stable Heterocyclic Imines as New Potential Nonlinear Optical Materials

    NASA Technical Reports Server (NTRS)

    Nesterov, Volodymyr V.; Antipin, Mikhail Y.; Nesterov, Vladimir N.; Moore, Craig E.; Cardelino, Beatriz H.; Timofeeva, Tatiana V.

    2004-01-01

    In the course of a search for new thermostable acentric nonlinear optical crystalline materials, several heterocyclic imine derivatives were designed, with the general structure D-pi-A(D'). Introduction of a donor amino group (D') into the acceptor moiety was expected to bring H-bonds into their crystal structures, and so to elevate their melting points and assist in an acentric molecular packing. Six heterocycle-containing compounds of this type were prepared, single crystals were grown for five of them, and these crystals were characterized by X-ray analysis. A significant melting temperature elevation was found for all of the synthesized compounds. Three of the compounds were also found to crystallize in acentric space groups. One of the acentric compounds is built as a three-dimensional H-bonded molecular network. In the other two compounds, with very similar molecular structure, the molecules form one-dimensional H-bonded head-to-head associates (chains). These chains are parallel in two different crystallographic directions and form very unusual interpenetrating chain patterns in an acentric crystal. Two of the compounds crystallized with centrosymmetric molecular packing.

  20. 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.

  1. Measurement of depth-resolved thermal deformation distribution using phase-contrast spectral optical coherence tomography.

    PubMed

    Zhang, Yun; Dong, Bo; Bai, Yulei; Ye, Shuangli; Lei, Zhenkun; Zhou, Yanzhou

    2015-10-19

    An updated B-scan method is proposed for measuring the evolution of thermal deformation fields in polymers. In order to measure the distributions of out-of-plane deformation and normal strain field, phase-contrast spectral optical coherence tomography (PC-SOCT) was performed with the depth range and resolution of 4.3 mm and 10.7 μm, respectively, as thermal loads were applied to three different multilayer samples. The relation between temperature and material refractive index was predetermined before the measurement. After accounting for the refractive index, the thermal deformation fields in the polymer were obtained. The measured thermal expansion coefficient of silicone sealant was approximately equal to its reference value. This method allows correctly assessing the mechanical properties in semitransparent polymers.

  2. Collagen remodeling in photo-thermal damaged skin with optical coherence tomography and multiphoton microscopy

    NASA Astrophysics Data System (ADS)

    Wu, Shu-lian; Li, Hui; Zhang, Xiao-man; Yu, Lili

    2009-08-01

    Cutaneous photo-thermal damage is the common damages in clinical medicine; it is a complex and dynamic process that follows an orderly sequence of events. The sequence can be roughly divided into three distinct, yet sequentially overlapping phases-inflammation, granulation tissue formation, and tissue remodeling. Characteristic structural changes associated with each phase could provide a basis for photo-thermal damage assessment with imaging technologies. Monitoring the skin tissue response during the skin after irradiated by laser and tracing the process of skin remodeling would help to understand the mechanism of photo-thermal. Optical coherence tomography (OCT) and multiphoton microscopy (MPM) imaging were used to observe the process of the collagen remodeling in mouse dermis photo-thermal injured which after irradiated by intense pulsed light source (IPLs) in this paper. Our finding showed that the OCT and MPM techniques can image the process of collagen remodeling in mouse dermis.

  3. Experimental Investigation of the Thermal Upset and Recovery of the National Ignition Facility's Optics Module

    SciTech Connect

    J. D. Bernardin

    1999-05-01

    The National Ignition Facility (NIF) at Lawrence Livermore National Laboratory is being constructed as the latest in a series of high-power laser facilities to study inertial confinement fusion. In particular, the NIF will generate and amplify 192 laser beams and focus them onto a fusion fuel capsule the size of a BB. The energy deposited by the laser beams will raise the core temperature of the target to 100,OOO,OOO C, which will ignite the fusion fuel and produce a fusion energy output that is several times greater than the energy input. The ability to generate, condition, and focus 192 laser beams onto a target the size of a BB, requires precision optical hardware and instrumentation. One of the most critical pieces of optical hardware within the NIF is the Optics Module (OM), a mechanical apparatus which is responsible for optical focusing and frequency conversion of the laser beam to optimize the energy deposition at the fusion target. The OM contains two potassium dihydrogen phosphate (KDP), frequency conversion crystals and a focusing lens. The functionality of the KDP crystals is extremely temperature sensitive. Small temperature changes on the order of 0.1 C can significantly alter the performance of these components. Consequently, to maximize NIF system availability and minimize beam conditioning problems, accurate temperature control of the OM optical components was deemed a necessity. In this study, an experimental OM prototype, containing mock frequency conversion crystals and a focusing lens, was used determine the thermal stability provided by a prototype water temperature control system. More importantly, the OM prototype was used to identify and characterize potential thermal upsets and corresponding recovery times of the KDP crystals. The results of this study indicate that the water temperature control system is adequate in maintaining uniform steady-state temperatures within the OM. Vacuum pump-down and venting of the OM generated significant

  4. Optic phonons and anisotropic thermal conductivity in hexagonal Ge2Sb2Te5

    PubMed Central

    Mukhopadhyay, Saikat; Lindsay, Lucas; Singh, David J.

    2016-01-01

    The lattice thermal conductivity (κ) of hexagonal Ge2Sb2Te5 (h-GST) is studied via direct first-principles calculations. We find significant intrinsic anisotropy (κa/κc~2) of κ in bulk h-GST, with the dominant contribution to κ from optic phonons, ~75%. This is extremely unusual as the acoustic phonon modes are the majority heat carriers in typical semiconductors and insulators. The anisotropy derives from varying bonding along different crystal directions, specifically from weak interlayer bonding along the c-axis, which gives anisotropic phonon dispersions. The phonon spectrum of h-GST has very dispersive optic branches with higher group velocities along the a-axis as compared to flat optic bands along the c-axis. The large optic mode contributions to the thermal conductivity in low-κ h-GST is unusual, and development of fundamental physical understanding of these contributions may be critical to better understanding of thermal conduction in other complex layered materials. PMID:27848985

  5. Optic phonons and anisotropic thermal conductivity in hexagonal Ge2Sb2Te5

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Saikat; Lindsay, Lucas; Singh, David J.

    2016-11-01

    The lattice thermal conductivity (κ) of hexagonal Ge2Sb2Te5 (h-GST) is studied via direct first-principles calculations. We find significant intrinsic anisotropy (κa/κc~2) of κ in bulk h-GST, with the dominant contribution to κ from optic phonons, ~75%. This is extremely unusual as the acoustic phonon modes are the majority heat carriers in typical semiconductors and insulators. The anisotropy derives from varying bonding along different crystal directions, specifically from weak interlayer bonding along the c-axis, which gives anisotropic phonon dispersions. The phonon spectrum of h-GST has very dispersive optic branches with higher group velocities along the a-axis as compared to flat optic bands along the c-axis. The large optic mode contributions to the thermal conductivity in low-κ h-GST is unusual, and development of fundamental physical understanding of these contributions may be critical to better understanding of thermal conduction in other complex layered materials.

  6. Surface Response of Brominated Carbon Media on Laser and Thermal Excitation: Optical and Thermal Analysis Study

    NASA Astrophysics Data System (ADS)

    Multian, Volodymyr V.; Kinzerskyi, Fillip E.; Vakaliuk, Anna V.; Grishchenko, Liudmyla M.; Diyuk, Vitaliy E.; Boldyrieva, Olga Yu.; Kozhanov, Vadim O.; Mischanchuk, Oleksandr V.; Lisnyak, Vladyslav V.; Gayvoronsky, Volodymyr Ya.

    2017-02-01

    The present study is objected to develop an analytical remote optical diagnostics of the functionalized carbons surface. Carbon composites with up to 1 mmol g-1 of irreversibly adsorbed bromine were produced by the room temperature plasma treatment of an activated carbon fabric (ACF) derived from polyacrylonitrile textile. The brominated ACF (BrACF) was studied by elastic optical scattering indicatrix analysis at wavelength 532 nm. The obtained data were interpreted within results of the thermogravimetric analysis, X-ray photoelectron spectroscopy and temperature programmed desorption mass spectrometry. The bromination dramatically reduces the microporosity producing practically non-porous material, while the incorporated into the micropores bromine induces the dielectric and structural impact on surface polarizability and conductivity due to the charging effect. We have found that the elastic optical scattering in proper solid angles in the forward and the backward hemispheres is sensitive to the kind of the bromine bonding, e.g., physical adsorption or chemisorption, and the bromination level, respectively, that can be utilized for the express remote fabrication control of the nanoscale carbons with given interfaces.

  7. Estimation of Soil Moisture from Optical and Thermal Remote Sensing: A Review

    PubMed Central

    Zhang, Dianjun; Zhou, Guoqing

    2016-01-01

    As an important parameter in recent and numerous environmental studies, soil moisture (SM) influences the exchange of water and energy at the interface between the land surface and atmosphere. Accurate estimate of the spatio-temporal variations of SM is critical for numerous large-scale terrestrial studies. Although microwave remote sensing provides many algorithms to obtain SM at large scale, such as SMOS and SMAP etc., resulting in many data products, they are almost low resolution and not applicable in small catchment or field scale. Estimations of SM from optical and thermal remote sensing have been studied for many years and significant progress has been made. In contrast to previous reviews, this paper presents a new, comprehensive and systematic review of using optical and thermal remote sensing for estimating SM. The physical basis and status of the estimation methods are analyzed and summarized in detail. The most important and latest advances in soil moisture estimation using temporal information have been shown in this paper. SM estimation from optical and thermal remote sensing mainly depends on the relationship between SM and the surface reflectance or vegetation index. The thermal infrared remote sensing methods uses the relationship between SM and the surface temperature or variations of surface temperature/vegetation index. These approaches often have complex derivation processes and many approximations. Therefore, combinations of optical and thermal infrared remotely sensed data can provide more valuable information for SM estimation. Moreover, the advantages and weaknesses of different approaches are compared and applicable conditions as well as key issues in current soil moisture estimation algorithms are discussed. Finally, key problems and suggested solutions are proposed for future research. PMID:27548168

  8. Estimation of Soil Moisture from Optical and Thermal Remote Sensing: A Review.

    PubMed

    Zhang, Dianjun; Zhou, Guoqing

    2016-08-17

    As an important parameter in recent and numerous environmental studies, soil moisture (SM) influences the exchange of water and energy at the interface between the land surface and atmosphere. Accurate estimate of the spatio-temporal variations of SM is critical for numerous large-scale terrestrial studies. Although microwave remote sensing provides many algorithms to obtain SM at large scale, such as SMOS and SMAP etc., resulting in many data products, they are almost low resolution and not applicable in small catchment or field scale. Estimations of SM from optical and thermal remote sensing have been studied for many years and significant progress has been made. In contrast to previous reviews, this paper presents a new, comprehensive and systematic review of using optical and thermal remote sensing for estimating SM. The physical basis and status of the estimation methods are analyzed and summarized in detail. The most important and latest advances in soil moisture estimation using temporal information have been shown in this paper. SM estimation from optical and thermal remote sensing mainly depends on the relationship between SM and the surface reflectance or vegetation index. The thermal infrared remote sensing methods uses the relationship between SM and the surface temperature or variations of surface temperature/vegetation index. These approaches often have complex derivation processes and many approximations. Therefore, combinations of optical and thermal infrared remotely sensed data can provide more valuable information for SM estimation. Moreover, the advantages and weaknesses of different approaches are compared and applicable conditions as well as key issues in current soil moisture estimation algorithms are discussed. Finally, key problems and suggested solutions are proposed for future research.

  9. Laser thermal therapy monitoring using complex differential variance in optical coherence tomography

    PubMed Central

    Lo, William C. Y.; Uribe-Patarroyo, Néstor; Nam, Ahhyun S.; Villiger, Martin; Vakoc, Benjamin J.; Bouma, Brett E.

    2016-01-01

    Conventional thermal therapy monitoring techniques based on temperature are often invasive, limited by point sampling, and are indirect measures of tissue injury, while techniques such as magnetic resonance and ultrasound thermometry are limited by their spatial resolution. The visualization of the thermal coagulation zone at high spatial resolution is particularly critical to the precise delivery of thermal energy to epithelial lesions. In this work, an integrated thulium laser thermal therapy monitoring system was developed based on complex differential variance (CDV), which enables the 2D visualization of the dynamics of the thermal coagulation process at high spatial and temporal resolution with an optical frequency domain imaging system. With proper calibration to correct for noise, the CDV-based technique was shown to accurately delineate the thermal coagulation zone, which is marked by the transition from high CDV upon heating to a significantly reduced CDV once the tissue is coagulated, in 3 different tissue types ex vivo: skin, retina, and esophagus. The ability to delineate thermal lesions in multiple tissue types at high resolution opens up the possibility of performing microscopic image-guided procedures in a vast array of epithelial applications ranging from dermatology, ophthalmology, to gastroenterology and beyond. PMID:27623742

  10. Design verification of large time constant thermal shields for optical reference cavities

    NASA Astrophysics Data System (ADS)

    Zhang, J.; Wu, W.; Shi, X. H.; Zeng, X. Y.; Deng, K.; Lu, Z. H.

    2016-02-01

    In order to achieve high frequency stability in ultra-stable lasers, the Fabry-Pérot reference cavities shall be put inside vacuum chambers with large thermal time constants to reduce the sensitivity to external temperature fluctuations. Currently, the determination of thermal time constants of vacuum chambers is based either on theoretical calculation or time-consuming experiments. The first method can only apply to simple system, while the second method will take a lot of time to try out different designs. To overcome these limitations, we present thermal time constant simulation using finite element analysis (FEA) based on complete vacuum chamber models and verify the results with measured time constants. We measure the thermal time constants using ultrastable laser systems and a frequency comb. The thermal expansion coefficients of optical reference cavities are precisely measured to reduce the measurement error of time constants. The simulation results and the experimental results agree very well. With this knowledge, we simulate several simplified design models using FEA to obtain larger vacuum thermal time constants at room temperature, taking into account vacuum pressure, shielding layers, and support structure. We adopt the Taguchi method for shielding layer optimization and demonstrate that layer material and layer number dominate the contributions to the thermal time constant, compared with layer thickness and layer spacing.

  11. Design verification of large time constant thermal shields for optical reference cavities.

    PubMed

    Zhang, J; Wu, W; Shi, X H; Zeng, X Y; Deng, K; Lu, Z H

    2016-02-01

    In order to achieve high frequency stability in ultra-stable lasers, the Fabry-Pérot reference cavities shall be put inside vacuum chambers with large thermal time constants to reduce the sensitivity to external temperature fluctuations. Currently, the determination of thermal time constants of vacuum chambers is based either on theoretical calculation or time-consuming experiments. The first method can only apply to simple system, while the second method will take a lot of time to try out different designs. To overcome these limitations, we present thermal time constant simulation using finite element analysis (FEA) based on complete vacuum chamber models and verify the results with measured time constants. We measure the thermal time constants using ultrastable laser systems and a frequency comb. The thermal expansion coefficients of optical reference cavities are precisely measured to reduce the measurement error of time constants. The simulation results and the experimental results agree very well. With this knowledge, we simulate several simplified design models using FEA to obtain larger vacuum thermal time constants at room temperature, taking into account vacuum pressure, shielding layers, and support structure. We adopt the Taguchi method for shielding layer optimization and demonstrate that layer material and layer number dominate the contributions to the thermal time constant, compared with layer thickness and layer spacing.

  12. Optical analysis and thermal management of 2-cell strings linear concentrating photovoltaic system

    NASA Astrophysics Data System (ADS)

    Reddy, K. S.; Kamnapure, Nikhilesh R.

    2015-09-01

    This paper presents the optical and thermal analyses for a linear concentrating photovoltaic/thermal collector under different operating conditions. Linear concentrating photovoltaic system (CPV) consists of a highly reflective mirror, a receiver and semi-dual axis tracking mechanism. The CPV receiver embodies two strings of triple-junction cells (100 cells in each string) adhered to a mild steel circular tube mounted at the focal length of trough. This system provides 560 W of electricity and 1580 W of heat which needs to be dissipated by active cooling. The Al2O3/Water nanofluid is used as heat transfer fluid (HTF) flowing through circular receiver for CPV cells cooling. Optical analysis of linear CPV system with 3.35 m2 aperture and geometric concentration ratio (CR) of 35 is carried out using Advanced System Analysis Program (ASAP) an optical simulation tool. Non-uniform intensity distribution model of solar disk is used to model the sun in ASAP. The impact of random errors including slope error (σslope), tracking error (σtrack) and apparent change in sun's width (σsun) on optical performance of collector is shown. The result from the optical simulations shows the optical efficiency (ηo) of 88.32% for 2-cell string CPV concentrator. Thermal analysis of CPV receiver is carried out with conjugate heat transfer modeling in ANSYS FLUENT-14. Numerical simulations of Al2O3/Water nanofluid turbulent forced convection are performed for various parameters such as nanoparticle volume fraction (φ), Reynolds number (Re). The addition of the nanoparticle in water enhances the heat transfer in the ranges of 3.28% - 35.6% for φ = 1% - 6%. Numerical results are compared with literature data which shows the reasonable agreement.

  13. Effect of thermal annealing on structural and optical properties of In2S3 thin films

    NASA Astrophysics Data System (ADS)

    Choudhary, Sonu

    2015-08-01

    There is a highly need of an alternate of toxic materials CdS for solar cell applications and indium sulfide is found the most suitable candidate to replace CdS due to its non-toxic and environmental friendly nature. In this paper, the effect of thermal annealing on the structural and optical properties of indium sulfide (In2S3) thin films is undertaken. The indium sulfide thin films of 121 nm were deposited on glass substrates employing thermal evaporation method. The films were subjected to the X-ray diffractometer and UV-Vis spectrophotometer respectively for structural and optical analysis. The XRD pattern show that the as-deposited thin film was amorphous in nature and crystallinity is found to be varied with annealing temperature. The optical analysis reveals that the optical band gap is varied with annealing. The optical parameters like absorption coefficient, extinction coefficient and refractive index were calculated. The results are in good agreement with available literature.

  14. Structural, Optical, and Dielectric Properties of Azure B Thin Films and Impact of Thermal Annealing

    NASA Astrophysics Data System (ADS)

    Zeyada, H. M.; Zidan, H. M.; Abdelghany, A. M.; Abbas, I.

    2017-03-01

    Thin films of azure B (AB) have been prepared by thermal evaporation. Structural, optical, and dielectric characteristics of as-prepared and annealed samples were studied. AB is polycrystalline in as-synthesized powder form. Detailed x-ray diffraction studies showed amorphous structure for pristine and annealed films. Fourier-transform infrared vibrational spectroscopy indicated minor changes in molecular bonds of AB thin films either after deposition or after thermal annealing. Optical transmittance and reflection spectra of prepared thin films were studied at nearly normal light incidence in the spectral range from 200 nm to 2500 nm, showing marked changes without new peaks. Annealing increased the absorption coefficient and decreased the optical bandgap. Onset and optical energy gaps of pristine films were found to obey indirect allowed transition with values of 1.10 eV and 2.64 eV, respectively. Annealing decreased the onset and optical energy gaps to 1.0 eV and 2.57 eV, respectively. The dispersion parameters before and after annealing are discussed in terms of a single-oscillator model. The spectra of the dielectric constants (ɛ 1, ɛ 2) were found to depend on the annealing temperature in addition to the incident photon energy.

  15. 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.

  16. Thermal coefficient of delay for various coaxial and fiber-optic cables

    NASA Technical Reports Server (NTRS)

    Lutes, G. F.; Diener, W.

    1989-01-01

    Data are presented on the thermal coefficient of delay for various coaxial and fiber optic cables, as measured by the Frequency and Timing Systems Engineering Group and the Time and Frequency Systems Research Group. The measured pressure coefficient of delay is also given for the air-dielectric coaxial cables. A description of the measurement method and a description of each of the cables and its use at JPL and in the DSN are included. An improvement in frequency and phase stability by a factor of ten is possible with the use of fiber optics.

  17. A review of recent measurements of optical and thermal properties of. alpha. -mercuric iodide

    SciTech Connect

    Burger, A.; Morgan, S.H.; Silberman, E. . Dept. of Physics); Nason, D.; Cheng, A.Y. . Santa Barbara Operations)

    1991-01-01

    The knowledge of the physical properties of a crystal and their relation to the nature and content of defects are essential for both applications and fundamental reasons. Alpha-mercuric iodide ({alpha}-HgI{sub 2}) is a material which was found important applications as room temperature X-ray and gamma ray detectors. Some recent thermal and optical measurements of this material, using the samples of improved crystallinity which are now available, are reviewed below. Heretofore, these properties have received less attention than the mechanical and electrical properties, particularly at elevated temperatures. In the technology of {alpha}-HgI{sub 2} where there is a continuing motivation to obtain larger single crystals without compromising the material quality, a better knowledge of the thermal and optical properties may lead to improvements in the processes of material purification, crystal growth and device fabrication.

  18. Mechanical, thermal, linear and nonlinear optical properties of barium L-tartrate single crystal

    NASA Astrophysics Data System (ADS)

    Rajesh, K.; Praveen Kumar, P.

    2017-01-01

    A potential semiorganic nonlinear optical (NLO) single crystal of barium L-tartrate (BaTr) was grown by slow evaporation technique. Single and powder x-ray diffraction study was carried out for the grown crystal. The hardness of the material was carried out by a Vickers micro hardness tester. Thermal behavior of the crystal was studied by TG-DTA thermal analyzer. Optical and electrical conductivity of the crystal was measured by photo conductivity and dielectric studies. NLO property of the crystal is confirmed by Kurt–Perry powder technique. Laser damage threshold (LDT) value of the grown crystal has been carried out using a Q-switched Nd:YAG laser beam.

  19. Optically- and Thermally-Responsive Programmable Materials Based on Carbon Nanotube-Hydrogel Polymer Composites

    DTIC Science & Technology

    2011-07-07

    hydrogels19,20 with promise to yield significant im- provements and new functionalities . In this study, we demon- strate single-walled carbon nanotube (SWNT...Reprint Optically- and Thermally-Responsive Programmable Materials Based on Carbon Nanotube -Hydrogel Polymer Composites W911NF-11-1-0089 0620BK Arash...actuators utilizing composites of poly(N-isopropylacrylamide) (pNIPAM) loaded with single-walled carbon nanotubes . With nanotube loading at concentrations

  20. Optical steering of thermally generated microbubbles in a liquid for targeted metallic nanoparticle delivery

    NASA Astrophysics Data System (ADS)

    Krishnappa, Arjun; Abeywickrema, Ujitha; Banerjee, Partha

    2016-09-01

    A novel mathematical model is developed to investigate the behavior of thermally generated microbubbles in the presence of optical radiation to understand the mechanism of their steering. Forces acting on a bubble are studied in detail using a general force model. It has been proposed that these microbubbles with agglomerated metallic nanoparticles can be used for targeted drug delivery. The model can be extended to include the steering of bubbles with agglomerated silver or gold nanoparticles on their surface.

  1. A study of the thermal diffusivities of carbons using optical beam deflection

    NASA Astrophysics Data System (ADS)

    Monzyk, John W.

    The thermal diffusivity is a property which completely characterizes the thermal wave in a material. The thermal diffusivity determines the speed, the wavelength, and the rate of extinction of the thermal wave. Optical beam deflection (OBD) is an experimental method of directly measuring the thermal diffusivity of a material parallel to the sample surface. Chopped light impingent upon the surface of a sample generates thermal waves in the material. The thermal waves propagate outward in all directions from the illuminated region. The temperature of the layer of gas immediately above the sample is driven by the temperature of the surface of the material. The time-dependent gradient of the index of refraction of the gas corresponds to the gradient of the time-dependent temperature field. Therefore, a probe laser beam propagating in this layer of gas is deflected by each passing heat pulse. The time required for the heat pulse to reach the probe laser beam causes a phase shift in the deflection of the probe beam measured relative to the phase of the illumination. This phase shift increases with probe-beam distance from the region of illumination. The thermal diffusivity is determined from the change of the phase with respect to the displacement of the probe beam. At sufficient probe-beam distances from the illuminated region, OBD theory predicts a linear dependence of the phase on the probe-beam displacement. The thermal diffusivities of five carbon materials were determined by OBD at room temperature after each was heat treated at six temperatures ranging from 1000oC to 2600oC. Two materials, an isotropic carbon and an anisotropic carbon, were made by chemical vapor deposition (CVD). After the anisotropic carbon was heat- treated beyond 2400oC, an increase in the carbon network was evidenced by a significant rise in the thermal diffusivity. The thermal diffusivity of the isotropic CVD carbon remained unchanged with heat treatment. Like the anisotropic CVD carbon, the

  2. Platinum as a release layer for thermally formed optics for IXO

    NASA Astrophysics Data System (ADS)

    Romaine, S.; Bruni, R.; Gorenstein, P.; Park, S.; Reid, P.; Ramsey, B.; Kester, T.

    2010-07-01

    Platinum is being explored as an alternative to the sprayed boron nitride mandrel release coating under study at GSFC for the International X-ray Observatory (IXO). Two and three inch diameter, polished (PFS) and superpolished (SPFS) fused silica flat mandrels, were used for these tests. Pt was applied to the mandrels by DC magnetron sputtering. The substrate material was 400 micron thick D263 glass, the material which has been proposed for the IXO segmented optics. These substrates were placed on the mandrels and thermally cycled with the same thermal profile being used at GSFC in the development of the BN slumping for IXO. After the thermal cycle was complete, the D263 substrates were removed; new D263 substrates were placed on the mandrels and the process was repeated. Four thermal cycles have been completed to date. After initially coating the mandrels with Pt, no further conditioning was applied to the mandrels before or during the thermal cycles. The microroughness of the mandrels and of the D263 substrates was measured before and after thermal cycling. Atomic force microscopy (AFM) and 8 keV X-ray reflectivity data are presented.

  3. Thermal Influence on Long-Distance Optical Measurement of Suspension Bridge Displacement

    NASA Astrophysics Data System (ADS)

    Lages Martins, Luís; Nunes Vicente Rebordão, José Manuel; Silva Ribeiro, Álvaro

    2014-04-01

    This paper discusses the thermal influence on long-distance and noncontact measurement of suspension bridge three-dimensional displacement by the use of an optical system composed of a digital camera, infrared active targets, and computational support. In this type of measurement method, the optical propagation path of light through the air can range from 250 m up to 750 m, making its measurement accuracy strongly dependent on atmospheric refraction and turbulence, phenomena that are linked to the vertical temperature gradient between the camera and targets. In addition, the adopted measurement geometrical configuration can lead to a height difference between these two elements (camera and targets) above 50 m. The paper describes the experimental setup and procedure followed for the determination of local temperature vertical gradients in the 25th of April Bridge in Lisbon (Portugal), where an optical measurement system was applied. The obtained thermal measurements are presented and applied in the evaluation of the systematic refraction vertical deviation, based on appropriate mathematical models mentioned in the paper, and for the identification of stable or unstable observation thermal conditions related to turbulence.

  4. Thermal properties of the optically transparent pore-free nanostructured yttria-stabilized zirconia

    SciTech Connect

    Ghosh, S.; Teweldebrhan, D.; Morales, J. R.; Garay, J. E.; Balandin, A. A.

    2009-12-01

    The authors report results of investigation of thermal conductivity of nanocrystalline yttria-stabilized zirconia. The optically transparent pore-free bulk samples were prepared via the spark plasma sintering process to ensure homogeneity. Thermal conductivity K was measured by two different techniques. It was found that the pore-free nanostructured bulk zirconia is an excellent thermal insulator with the room-temperature Kapprox1.7-2.0 W/m K. It was also shown that the 'phonon-hopping' model can accurately describe specifics of K dependence on temperature and the grain size. The obtained results are important for optimization of zirconia properties for specific applications in advanced electronics and coatings.

  5. Optically Detected Magnetic Resonance and Thermal Activation Spectroscopy Study of Organic Semiconductors

    SciTech Connect

    Kim, Chang-Hwan

    2003-01-01

    Organic electronic materials are a new class of emerging materials. Organic light emitting devices (OLEDs) are the most promising candidates for future flat panel display technologies. The photophysical characterization is the basic research step one must follow to understand this new class of materials and devices. The light emission properties are closely related to the transport properties of these materials. The objective of this dissertation is to probe the relation between transport and photophysical properties of organic semiconductors. The transport characteristics were evaluated by using thermally stimulated current and thermally stimulated luminescence techniques. The photoluminescence detected magnetic resonance and photoluminescence quantum yield studies provide valuable photophysical information on this class of materials. OLEDs are already in the market. However, detailed studies on the degradation mechanisms are still lacking. Since both optically detected magnetic resonance and thermal activation spectroscopy probe long-lived defect-related states in organic semiconductors, the combined study generates new insight on the OLED operation and degradation mechanisms.

  6. Evaluation of optical and chromatic properties under electrical and thermal coupling in solid state lighting systems

    NASA Astrophysics Data System (ADS)

    Fu, Han-Kuei; Peng, Yi-Ping; Wang, Chien-Ping; Chiang, Hsin-Chien; Chen, Tzung-Te; Chen, Chiu-Ling; Chou, Pei-Ting

    2013-09-01

    For energy-saving, high efficiency and low pollution, the lighting of LED systems is important for the future of green energy technology industry. The solid state lighting becomes the replacement of traditional lighting, such as, light bulbs and compact fluorescent lamps. Because of the semiconductor characteristics, the luminous efficiency of LEDs is sensitive to the operating temperature. Besides increasing the luminous efficiency, effective controlling electricity and thermal characteristics in the design of LED lighting products is the key point to achieve the best results. LED modules can be combined with multi-grain process or through a combination of multiple LED chips. Accurate analysis of this LED module for the electrical, thermal characteristics and high reliability is the critical knowledge of modular design. In this report, we studied the electrical and thermal coupling phenomenon in solid state lighting systems to analyze their reliability. By experiments and simulations, we obtained the apparent variation of temperature distribution of LED system due to differences of their forward voltages and thermal resistances. These events may reduce their reliability. Besides, the evaluation of optical and chromatic properties was based on the variation of temperature distribution and current of LED system. This is the key technology to predict the optical and chromatic properties of LED system in use.

  7. The influence of temperature calibration on the OC-EC results from a dual-optics thermal carbon analyzer

    NASA Astrophysics Data System (ADS)

    Pavlovic, J.; Kinsey, J. S.; Hays, M. D.

    2014-09-01

    Thermal-optical analysis (TOA) is a widely used technique that fractionates carbonaceous aerosol particles into organic and elemental carbon (OC and EC), or carbonate. Thermal sub-fractions of evolved OC and EC are also used for source identification and apportionment; thus, oven temperature accuracy during TOA analysis is essential. Evidence now indicates that the "actual" sample (filter) temperature and the temperature measured by the built-in oven thermocouple (or set-point temperature) can differ by as much as 50 °C. This difference can affect the OC-EC split point selection and consequently the OC and EC fraction and sub-fraction concentrations being reported, depending on the sample composition and in-use TOA method and instrument. The present study systematically investigates the influence of an oven temperature calibration procedure for TOA. A dual-optical carbon analyzer that simultaneously measures transmission and reflectance (TOT and TOR) is used, functioning under the conditions of both the National Institute of Occupational Safety and Health Method 5040 (NIOSH) and Interagency Monitoring of Protected Visual Environment (IMPROVE) protocols. The application of the oven calibration procedure to our dual-optics instrument significantly changed NIOSH 5040 carbon fractions (OC and EC) and the IMPROVE OC fraction. In addition, the well-known OC-EC split difference between NIOSH and IMPROVE methods is even further perturbed following the instrument calibration. Further study is needed to determine if the widespread application of this oven temperature calibration procedure will indeed improve accuracy and our ability to compare among carbonaceous aerosol studies that use TOA.

  8. Development and implementation of a generic analysis template for structural-thermal-optical-performance modeling

    NASA Astrophysics Data System (ADS)

    Scola, Salvatore; Stavely, Rebecca; Jackson, Trevor; Boyer, Charlie; Osmundsen, Jim; Turczynski, Craig; Stimson, Chad

    2016-09-01

    Performance-related effects of system level temperature changes can be a key consideration in the design of many types of optical instruments. This is especially true for space-based imagers, which may require complex thermal control systems to maintain alignment of the optical components. Structural-Thermal-Optical-Performance (STOP) analysis is a multi-disciplinary process that can be used to assess the performance of these optical systems when subjected to the expected design environment. This type of analysis can be very time consuming, which makes it difficult to use as a trade study tool early in the project life cycle. In many cases, only one or two iterations can be performed over the course of a project. This limits the design space to best practices since it may be too difficult, or take too long, to test new concepts analytically. In order to overcome this challenge, automation, and a standard procedure for performing these studies is essential. A methodology was developed within the framework of the Comet software tool that captures the basic inputs, outputs, and processes used in most STOP analyses. This resulted in a generic, reusable analysis template that can be used for design trades for a variety of optical systems. The template captures much of the upfront setup such as meshing, boundary conditions, data transfer, naming conventions, and post-processing, and therefore saves time for each subsequent project. A description of the methodology and the analysis template is presented, and results are described for a simple telescope optical system.

  9. Development and Implementation of a Generic Analysis Template for Structural-Thermal-Optical-Performance Modeling

    NASA Technical Reports Server (NTRS)

    Scola, Salvatore; Stavely, Rebecca; Jackson, Trevor; Boyer, Charlie; Osmundsen, Jim; Turczynski, Craig; Stimson, Chad

    2016-01-01

    Performance-related effects of system level temperature changes can be a key consideration in the design of many types of optical instruments. This is especially true for space-based imagers, which may require complex thermal control systems to maintain alignment of the optical components. Structural-Thermal-Optical-Performance (STOP) analysis is a multi-disciplinary process that can be used to assess the performance of these optical systems when subjected to the expected design environment. This type of analysis can be very time consuming, which makes it difficult to use as a trade study tool early in the project life cycle. In many cases, only one or two iterations can be performed over the course of a project. This limits the design space to best practices since it may be too difficult, or take too long, to test new concepts analytically. In order to overcome this challenge, automation, and a standard procedure for performing these studies is essential. A methodology was developed within the framework of the Comet software tool that captures the basic inputs, outputs, and processes used in most STOP analyses. This resulted in a generic, reusable analysis template that can be used for design trades for a variety of optical systems. The template captures much of the upfront setup such as meshing, boundary conditions, data transfer, naming conventions, and post-processing, and therefore saves time for each subsequent project. A description of the methodology and the analysis template is presented, and results are described for a simple telescope optical system.

  10. Optical and thermal simulations of noninvasive laser coagulation of the human vas deferens

    NASA Astrophysics Data System (ADS)

    Schweinsberger, Gino R.; Cilip, Christopher M.; Trammell, Susan R.; Cherukuri, Harish; Fried, Nathaniel M.

    2011-03-01

    Successful noninvasive laser coagulation of the canine vas deferens, in vivo, has been previously reported. However, there is a significant difference between the optical properties of canine and human skin. In this study, Monte Carlo simulations of light transport through tissue and heat transfer simulations are performed to determine the feasibility of noninvasive laser vasectomy in humans. A laser wavelength of 1064 nm was chosen for deep optical penetration in tissue. Monte Carlo simulations determined the spatial distribution of absorbed photons inside the tissue layers (epidermis, dermis, and vas). The results were convolved with a 3-mm-diameter laser beam, and then used as the spatial heat source for the heat transfer model. A laser pulse duration of 500 ms and pulse rate of 1 Hz, and cryogen spray cooling were incident on the tissue for 60 s. Average laser power (5-9 W), cryogen pulse duration (60-100 ms), cryogen cooling rate (0.5-1.0 Hz), and increase in optical transmission due to optical clearing (0-50 %), were studied. After application of an optical clearing agent to increase skin transmission by 50%, an average laser power of 6 W, cryogen pulse duration of 60 ms, and cryogen cooling rate of 1 Hz resulted in vas temperatures of ~ 60°C, sufficient for thermal coagulation, while 1 mm of the skin surface (epidermis and dermis) remained at a safe temperature of ~ 45 °C. Monte Carlo and heat transfer simulations indicate that it is possible to noninvasively thermally coagulate the human vas without adverse effects (e.g. scrotal skin burns), if an optical clearing agent is applied to the skin prior to the procedure.

  11. Factorial Based Response Surface Modeling with Confidence Intervals for Optimizing Thermal Optical Transmission Analysis of Atmospheric Black Carbon

    EPA Science Inventory

    We demonstrate how thermal-optical transmission analysis (TOT) for refractory light-absorbing carbon in atmospheric particulate matter was optimized with empirical response surface modeling. TOT employs pyrolysis to distinguish the mass of black carbon (BC) from organic carbon (...

  12. Water-soluble Au25(Capt)18 nanoclusters: synthesis, thermal stability, and optical properties

    NASA Astrophysics Data System (ADS)

    Kumar, Santosh; Jin, Rongchao

    2012-06-01

    This work was motivated by the unsatisfactory stability of Au25(SG)18 in solution under thermal conditions (e.g. 70-90 °C for DNA melting). Thus, we searched for a better, water-soluble thiol ligand. Herein, we report a one-pot synthesis and investigation of the stability and optical properties of captopril (abbreviated Capt)-protected Au25(Capt)18 nanoclusters. The Au25(Capt)18 (anionic, counterion: Na+) nanoclusters were formed via size focusing under ambient conditions. Significantly, Au25(Capt)18 nanoclusters exhibit largely improved thermal stability compared to the glutathione (HSG) capped Au25(SG)18. Both Au25(Capt)18 and Au25(SG)18 nanoclusters show fluorescence centered at ~700 nm. The chiral ligands (Capt, SG, as well as chirally modified phenylethanethiol (PET*)) give rise to distinct chiroptical features. The high thermal stability and distinct optical properties of Au25(Capt)18 nanoclusters render this material quite promising for biological applications.This work was motivated by the unsatisfactory stability of Au25(SG)18 in solution under thermal conditions (e.g. 70-90 °C for DNA melting). Thus, we searched for a better, water-soluble thiol ligand. Herein, we report a one-pot synthesis and investigation of the stability and optical properties of captopril (abbreviated Capt)-protected Au25(Capt)18 nanoclusters. The Au25(Capt)18 (anionic, counterion: Na+) nanoclusters were formed via size focusing under ambient conditions. Significantly, Au25(Capt)18 nanoclusters exhibit largely improved thermal stability compared to the glutathione (HSG) capped Au25(SG)18. Both Au25(Capt)18 and Au25(SG)18 nanoclusters show fluorescence centered at ~700 nm. The chiral ligands (Capt, SG, as well as chirally modified phenylethanethiol (PET*)) give rise to distinct chiroptical features. The high thermal stability and distinct optical properties of Au25(Capt)18 nanoclusters render this material quite promising for biological applications. Electronic supplementary

  13. Evaluating the thermal stability of multi-pass cells' effective optical path length using optical frequency domain reflectometer

    NASA Astrophysics Data System (ADS)

    Gao, Hong; Cao, Xiuhan; Li, Jinyi; Du, Zhenhui

    2016-10-01

    Multi-pass cells (MPCs) are commonly used to improve the sensitivity for trace gas detection using spectroscopy technologies. The determination of Effective Optical Path Length (EOPL) of a MPC is very important and challenging in applications which aim at absolute measurements. It is well-known that the temperature changing will exercise some influence on the MPCs' spatial structure, however, measurements of the influence haven't been reported which might due to the limitation of measuring method. In this paper, we used a direct high-precision measuring method with Optical Frequency Domain Reflectometer (OFDR) to evaluate the thermal stability of a multi-pass cell. To simulate the environment with a large range of temperature changing, this paper gave a series of experiments by setting the temperature control unit in system from 25 to 175 degree Celsius, and the MPC's EOPL was measured simultaneously for the investigation of temperature response. The results showed that the effective optical path length increase monotonically along with the variation of the temperature, and the rising rate is 0.5 mm/ºC with the total length of about 3 meters which should be pay attention to when the ultra-high accuracy results are demanded. To stabilize the EOPL of the system, if it is possible, the environment temperature of gas cell can be controlled with a constant temperature. In practical applications, the real-time monitoring of EOPL with a direct measuring method may be necessary.

  14. Synthesis, linear optical, non-linear optical, thermal and mechanical characterizations of dye-doped semi-organic NLO crystals

    NASA Astrophysics Data System (ADS)

    Sesha Bamini, N.; Vidyalakshmy, Y.; Choedak, Tenzin; Kejalakshmy, N.; Muthukrishnan, P.; Ancy, C. J.

    2015-06-01

    Organic laser dyes Coumarin 485, Coumarin 540 and Rhodamine 590 Chloride were used to dope potassium acid phthalate crystals (KAP). Dye-doped KAP crystals with different dye concentrations such as 0.01 mM, 0.03 mM, 0.05 mM, 0.07 mM and 0.09 mM (in the KAP growth solution) were grown. The linear optical, non-linear optical, mechanical and thermal characterizations of dye-doped KAP crystals were studied and compared to understand the effect of dye and dye concentration on the KAP crystal. Absorption and emission studies of KAP and dye-doped KAP single crystals indicated the inclusion of the dye into the KAP crystal lattice. The effect of dye and its concentration on the SHG efficiency of the KAP crystal was studied using the Kurtz and Perry powder technique. It was observed that the absorption maximum wavelength and concentration of the dye used for doping the KAP single crystal decided the SHG efficiency of the dye-doped KAP single crystals. The mechanical hardness of the dye-doped and undoped (pure) KAP single crystals were studied using the Vickner’s microhardness test. It was observed that doping the KAP crystals with the laser dyes changed them from softer material to harder material. Etching studies showed an improvement in the optical quality of the KAP crystal after doping with laser dyes.

  15. Optical method for measuring thermal accommodation coefficients using a whispering-gallery microresonator

    NASA Astrophysics Data System (ADS)

    Ganta, D.; Dale, E. B.; Rezac, J. P.; Rosenberger, A. T.

    2011-08-01

    A novel optical method has been developed for the measurement of thermal accommodation coefficients in the temperature-jump regime. The temperature dependence of the resonant frequency of a fused-silica microresonator's whispering-gallery mode is used to measure the rate at which the microresonator comes into thermal equilibrium with the ambient gas. The thermal relaxation time is related to the thermal conductivity of the gas under some simplifying assumptions and measuring this time as a function of gas pressure determines the thermal accommodation coefficient. Using a low-power tunable diode laser of wavelength around 1570 nm to probe a microsphere's whispering-gallery mode through tapered-fiber coupling, we have measured the accommodation coefficients of air, helium, and nitrogen on fused silica at room temperature. In addition, by applying thin-film coatings to the microsphere's surface, we have demonstrated that accommodation coefficients can be measured for various gases on a wide range of modified surfaces using this method.

  16. In vivo assessment of thermal damage in the liver using optical spectroscopy.

    PubMed

    Buttemere, Clay R; Chari, Ravi S; Anderson, Christopher D; Washington, M Kay; Mahadevan-Jansen, Anita; Lin, Wei-Chiang

    2004-01-01

    Resection is not a viable treatment option for the majority of liver cancer patients. Alternatives to resection include thermotherapies such as radio-frequency ablation; however, these therapies lack adequate intraoperative feedback regarding the degree and margins of tissue thermal damage. In this proof of principle study, we test the ability of fluorescence and diffuse reflectance spectroscopy to assess local thermal damage in vivo. Spectra were acquired in vivo from healthy canine liver tissue undergoing radio-frequency ablation using a portable fiber-optic-based spectroscopic system. The major observed spectral alterations on thermal coagulation were a red shift in the fluorescence emission peak at 480 nm, a decrease in the overall fluorescence intensity, and an increase in the diffuse reflectance from 450 to 750 nm. Spectral changes were quantified and correlated to tissue histology. We found a good correlation between the proposed spectral correlates of thermal damage and histology. The results of this study suggest that fluorescence and diffuse reflectance spectroscopy show strong potential as tools to monitor liver tissue thermal damage intraoperatively.

  17. An optically and thermally switchable electronic structure based on an anthracene-BODIPY conjugate.

    PubMed

    Aotake, Tatsuya; Suzuki, Mitsuharu; Tahara, Kazuaki; Kuzuhara, Daiki; Aratani, Naoki; Tamai, Naoto; Yamada, Hiroko

    2015-03-23

    An optically and thermally responsive boron dipyrromethene (BODIPY) dye, namely, meso-2-(9,10-dihydro-9,10-ethanoanthracene-11,12-dione) (DK)-linked, bicyclo[2.2.2]octadiene (BCOD)-fused BODIPY (BCOD-DK), was synthesized. The weakly luminous structure of BCOD-DK can be changed quantitatively to that of the strongly fluorescent BODIPY BCOD-Ant by optical excitation at the DK unit, which induces double decarbonylation of the DK unit to give an anthracene unit. The solvent effect on the fluorescence properties of BCOD-DK suggests that the dramatic change in fluorescence intensity is controlled by intramolecular electron transfer from the BODIPY moiety to the meso-DK substituent. BCOD-DK is converted to meso-DK benzene-fused BODIPY (Benzo-DK) by heating at 220 °C with 64-70 nm redshift of absorption and fluorescence peaks without changing the fluorescence quantum yield of ΦF =0.08 in dichloromethane. Benzo-DK can be converted to strongly fluorescent meso-anthracene benzene-fused BODIPY Benzo-Ant by optical excitation. Thus, BCOD-DK can show four different optical performances simply by irradiation and heating, and hence may be applicable for optical data storage and security data encryption.

  18. Thermally induced distortion of high average power laser system by an optical transport system

    SciTech Connect

    Ault, L; Chow, R; Taylor, Jedlovec, D

    1999-03-31

    The atomic vapor laser isotope separation process uses high-average power lasers that have the commercial potential to enrich uranium for the electric power utilities. The transport of the laser beam through the laser system to the separation chambers requires high performance optical components, most of which have either fused silica or Zerodur as the substrate material. One of the requirements of the optical components is to preserve the wavefront quality of the laser beam that propagate over long distances. Full aperture tests with the high power process lasers and finite element analysis (FEA) have been performed on the transport optics. The wavefront distortions of the various sections of the transport path were measured with diagnostic Hartmann sensor packages. The FEA results were derived from an in-house thermal-structural-optical code which is linked to the commercially available CodeV program. In comparing the measured and predicted results, the bulk absorptance of fused silica was estimated to about 50 ppm/cm in the visible wavelength regime. Wavefront distortions are reported on optics made from fused silica and Zerodur substrate materials.

  19. Differences in the OC/EC Ratios that Characterize Ambient and Source Aerosols due to Thermal-Optical Analysis

    EPA Science Inventory

    Thermal-optical analysis (TOA) is typically used to measure the OC/EC (organic carbon/elemental carbon) and EC/TC (elemental carbon/total carbon) ratios in source and atmospheric aerosols. The present study utilizes a dual-optical carbon aerosol analyzer to examine the effects of...

  20. The influence of temperature calibration on the OC–EC results from a dual-optics thermal carbon analyzer

    EPA Science Inventory

    The Sunset Laboratory Dual-Optical Carbonaceous Analyzer that simultaneously measures transmission and reflectance signals is widely used in thermal-optical analysis of particulate matter samples. Most often this instrument is used to measure total carbon (TC), organic carbon (O...

  1. Measurement of Black (BC) and Elemental (EC) Carbon by an Optical and a Thermal- optical Method: An Intercomparison

    NASA Astrophysics Data System (ADS)

    Ahmed, T.; Dutkiewicz, V. A.; Khan, A. R.; Husain, L.

    2009-05-01

    Elemental or Black carbon (EC or BC) aerosol emitted into the atmosphere from incomplete combustion of fossil fuel, biomass and forest fires absorbs solar radiations and contributes to global warming. EC or BC is defined based on different analytical methods used for measuring the same fraction of carbonaceous aerosol. The different methods give different results which can vary widely. There is no accepted standard available to accurately quantify EC and therefore measurements between different methods need to be compared to reduce the bias. In this study intercomparison of data between two widely used techniques, BC obtained using optical method (non-destructive technique) and EC obtained using thermal-optical methods (destructive technique) are performed on aerosol samples collected on Whatman 41 filter paper from two rural sites, Whiteface Mountain (WFM) and Mayville, NY. Daily aerosol samples from six months at Mayville collected during 1998 and 2002 and fourteen months from WFM collected during 1996 and 2002 were analyzed using Sunset thermal-optical transmittance (TOT) elemental/organic carbon (EC/OC) analyzer and Magee Scientific Transmissiometer (Model OT-21). Total numbers of samples analyzed from the two sites were around 400. Transmissiometer used for BC measurement is based on optical attenuation of light and its working principle is similar to that of widely used Aethalometer. Whatman 41 filters are not suitable for direct EC measurement using EC/OC analyzer, so a pretreatment technique was developed and EC was subsequently transferred on 47 mm quartz filter paper. The total analysis time for individual sample using Transmissiometer is short (˜ 3-5 min) compared with ˜ 20-25 minutes for EC/OC analyzer excluding the time required for chemical pre-treatment (which can be up to 60 min). Reasonably good correlation, r2>0.8 and BC/EC slope close to 1 was obtained for concentrations up to 600 ngm- 3. For concentration >600 ngm-3 the relationship tends to

  2. Laser geodynamic satellite thermal/optical/ vibrational analyses and testing. Volume 2: Technical report, book 1. [retroreflector design

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The results of the LAGEOS thermal/optical/vibrational analysis and test program are reported. Through analyses and tests it is verified that the MSFC LAGEOS design provides a retroreflector thermal environment which maintains acceptable retroflector internal thermal gradients. The technical results of the study, organized by the major task areas are presented. The interrelationships of the major tasks are described and the major decisions are identified.

  3. Differences in thermal optical response between intact diabetic and nondiabetic human skin

    NASA Astrophysics Data System (ADS)

    Yeh, Shu-Jen; Hanna, Charles F.; Kantor, Stan; Hohs, Ronald; Khalil, Omar S.

    2003-07-01

    We observed a difference in the thermal response of localized reflectance signal of human skin between type-2 diabetic and non-diabetic volunteers. We investigated the use of this thermo-optical behavior as a basis for a non-invasive method for the determination of the diabetic status of a subject. We used a two-site temperature differential method, which is predicated upon the measurement of localized reflectance from two areas on the surface of the skin, each of these areas is subjected to a different thermal perturbation. The response of skin localized reflectance to temperature was measured and used in a classification algorithm. We used a discriminant function to classify subjects as diabetics or non-diabetics. In a prediction set of 24 non-invasive tests collected from 6 diabetics and 6 non-diabetics, the sensitivity ranged between 73% and 100%, and the specificity ranged between 75% and 100%, depending on the thermal conditions and probe-skin contact time. The difference in thermo-optical response of the skin of the two groups may be explained in terms of difference in response of cutaneous microcirculation to temperature, which is manifested as a difference in the near infrared light absorption and scattering. Another factor is the difference in the temperature response of the scattering coefficient between the two groups, which may be caused by cutaneous structural differences induced by non-enzymatic glycation of skin protein fibers, and/or by the difference in blood cell aggregation.

  4. Tunable Laser Development for In-flight Fiber Optic Based Structural Health Monitoring Systems

    NASA Technical Reports Server (NTRS)

    Richards, Lance; Parker, Allen; Chan, Patrick

    2014-01-01

    The objective of this task is to investigate, develop, and demonstrate a low-cost swept lasing light source for NASA DFRC's fiber optics sensing system (FOSS) to perform structural health monitoring on current and future aerospace vehicles. This is the regular update of the Tunable Laser Development for In-flight Fiber Optic Based Structural Health Monitoring Systems website.

  5. Structural and optical behavior due to thermal effects in end-pumped Yb:YAG disk lasers.

    PubMed

    Sazegari, Vahid; Milani, Mohammad Reza Jafari; Jafari, Ahmad Khayat

    2010-12-20

    We employ a Monte Carlo ray-tracing code along with the ANSYS package to predict the optical and structural behavior in end-pumped CW Yb:YAG disk lasers. The presence of inhomogeneous temperature, stress, and strain distributions is responsible for many deleterious effects for laser action through disk fracture, strain-induced birefringence, and thermal lensing. The thermal lensing, in turn, results in the optical phase distortion in solid-state lasers. Furthermore, the dependence of optical phase distortion on variables such as the heat transfer coefficient, the cooling fluid temperature, and crystal thickness is discussed.

  6. Thermal properties of borate crystals for high power optical parametric chirped-pulse amplification.

    PubMed

    Riedel, R; Rothhardt, J; Beil, K; Gronloh, B; Klenke, A; Höppner, H; Schulz, M; Teubner, U; Kränkel, C; Limpert, J; Tünnermann, A; Prandolini, M J; Tavella, F

    2014-07-28

    The potential of borate crystals, BBO, LBO and BiBO, for high average power scaling of optical parametric chirped-pulse amplifiers is investigated. Up-to-date measurements of the absorption coefficients at 515 nm and the thermal conductivities are presented. The measured absorption coefficients are a factor of 10-100 lower than reported by the literature for BBO and LBO. For BBO, a large variation of the absorption coefficients was found between crystals from different manufacturers. The linear and nonlinear absorption coefficients at 515 nm as well as thermal conductivities were determined for the first time for BiBO. Further, different crystal cooling methods are presented. In addition, the limits to power scaling of OPCPAs are discussed.

  7. A novel interferometric technique to estimate thermal diffusivity of optically transparent solid using isothermal surface velocimetry

    NASA Astrophysics Data System (ADS)

    Settu, Balachandar; Shivaprakash, N. C.; Kameswara Rao, L.

    2015-07-01

    One-dimensional transient heat flow is interpreted as a procession of `macro-scale translatory motion of indexed isothermal surfaces'. A new analytical model is proposed by introducing velocity of isothermal surface in Fourier heat diffusion equation. The velocity dependent function is extracted by revisiting `the concept of thermal layer of heat conduction in solid' and `exact solution' to estimate thermal diffusivity. The experimental approach involves establishment of 1 D unsteady heat flow inside the sample through Step-temperature excitation. A novel self-reference interferometer is utilized to separate a `unique isothermal surface' in time- varying temperature field. The translatory motion of the said isothermal surface is recorded using digital camera to estimate its velocity. From the knowledge of thermo-optic coefficient, temperature of the said isothermal surface is predicted. The performance of proposed method is evaluated for Quartz sample and compared with literature.

  8. Structural, optical, electrical and thermal properties of zinc oxide thin films by chemical spray pyrolysis

    NASA Astrophysics Data System (ADS)

    Shinde, S. S.; Bhosale, C. H.; Rajpure, K. Y.

    2012-08-01

    Thin films of highly textured ZnO are synthesized by simple chemical spray pyrolysis onto corning glass substrates in aqueous medium. The influence of solution concentration onto photoelectrochemical, structural, morphological, compositional, optical, electrical and thermal properties have been investigated. Structural analysis shows the hexagonal (wurtzite) crystal structure. Electron-phonon-coupling in ZnO films has analyzed using Raman spectroscopy. The chemical composition and valence states of constituent elements in ZnO are analyzed by X-ray photoelectron spectroscopy. The SEM and AFM micrographs depict the films are compact and homogeneous (hexagonal platelets nanostructures) with varying grain sizes (average grain size ˜50-150 nm). The specific heat and thermal conductivity study shows the phonon conduction behavior is dominant in these polycrystalline films.

  9. Growth aspects, structural, optical, thermal and mechanical properties of benzotriazole pyridine-2-carboxylic acid single crystal

    NASA Astrophysics Data System (ADS)

    Thirunavukkarsu, A.; Sujatha, T.; Umarani, P. R.; Nizam Mohideen, M.; Silambarasan, A.; Kumar, R. Mohan

    2017-02-01

    Benzotriazole pyridine-2-carboxylic acid single crystal (BTPCA) was grown by slow evaporation solution growth technique. The cell parameters and crystallinity of BTPCA crystal were found by single crystal and powder X-ray diffraction studies. The presence of functional groups was studied by FT-IR analysis. UV-vis-NIR transmission studies reveal that the BTPCA crystal is transparent in the entire visible region with lower optical cut-off wavelength of 306 nm. The thermal stability, melting point and decomposition stages of BTPCA were analysed from the thermogravimetric and differential thermal analyses. The second harmonic output power of BTPCA was measured to be 2.5 times that of KDP reference crystal. Hardness studies reveal that grown crystal shows the reverse indentation size effect and breakeven point due to release of internal fatigue generated during indentation.

  10. Impact of thermal annealing on optical properties of vacuum evaporated CdTe thin films for solar cells

    NASA Astrophysics Data System (ADS)

    Chander, Subhash; Purohit, A.; Lal, C.; Nehra, S. P.; Dhaka, M. S.

    2016-05-01

    In this paper, the impact of thermal annealing on optical properties of cadmium telluride (CdTe) thin films is investigated. The films of thickness 650 nm were deposited on thoroughly cleaned glass substrate employing vacuum evaporation followed by thermal annealing in the temperature range 250-450 °C. The as-deposited and annealed films were characterized using UV-Vis spectrophotometer. The optical band gap is found to be decreased from 1.88 eV to 1.48 eV with thermal annealing. The refractive index is found to be in the range 2.73-2.92 and observed to increase with annealing treatment. The experimental results reveal that the thermal annealing plays an important role to enhance the optical properties of CdTe thin films and annealed films may be used as absorber layer in CdTe/CdS solar cells.

  11. Crystal growth, vibrational, optical, thermal and theoretical studies of a nonlinear optical material: 2-Methyl 3,5-dinitrobenzoic acid

    NASA Astrophysics Data System (ADS)

    Sangeetha, K.; Guru Prasad, L.; Mathammal, R.

    2016-11-01

    Single crystals of 2-methyl 3,5-dinitro benzoic acid with reasonable size have been grown by slow evaporation solution growth method using ethanol as solvent. Quantum chemical calculation of 2-methyl 3,5-Dinitro benzoic acid was carried out by using DFT/B3LYP/6-31+G(d,p) method. The powder X-ray diffraction pattern was recorded and indexed. Both the experimental and theoretical vibrational spectrum validates the presence of functional groups. Polarizability, first order hyperpolarizability and the electric dipole moment values have been computed theoretically. The 1H and 13C NMR chemical shift of the molecule was calculated and compared with experimental results. TG/DSC analysis has been employed to understand the thermal and physio-chemical stability of the title compound. Frequency conversion property of the crystal was tested by Kurtz and Perry method. Optical absorption behavior of the grown crystal was examined by recording the optical spectrum and band gap energy was also estimated. The calculated HOMO and LUMO energy shows the charge transfer nature of the molecule.

  12. Thermal radiation from optically driven Kerr (χ{sup (3)}) photonic cavities

    SciTech Connect

    Khandekar, Chinmay; Rodriguez, Alejandro W.; Lin, Zin

    2015-04-13

    We describe thermal radiation from nonlinear (χ{sup (3)}) photonic cavities coupled to external channels and subject to incident monochromatic light. Our work extends related work on nonlinear mechanical oscillators to the problem of thermal radiation, demonstrating that bistability can enhance thermal radiation by orders of magnitude and result in strong lineshape alternations, including “super-narrow spectral peaks” occurring at the onset of kinetic phase transitions. We show that when the cavities are designed to exhibit perfect linear emissivity (rate matching), such thermally activated transitions can be exploited to dramatically tune the output power and radiative properties of the cavity, leading to a kind of Kerr-mediated thermo-optic effect. Finally, we demonstrate that in certain parameter regimes, the output radiation exhibits Stokes and anti-Stokes side peaks whose relative magnitudes can be altered by tuning the internal temperature of the cavity relative to its surroundings, a consequence of strong correlations and interference between the emitted and reflected radiation.

  13. Measurement of thermal expansion coefficient of graphene diaphragm using optical fiber Fabry-Perot interference

    NASA Astrophysics Data System (ADS)

    Li, Cheng; Liu, Qianwen; Peng, Xiaobin; Fan, Shangchun

    2016-07-01

    Application of the Fabry-Perot (FP) interference method for determining the coefficient of thermal expansion (CTE) of a graphene diaphragm is investigated in this paper. A miniature extrinsic FP interferometric (EFPI) sensor was fabricated by using an approximate 8-layer graphene diaphragm. The extremely thin diaphragm was transferred onto the endface of a ferrule with an inner diameter of 125 μm, and van der Waals interactions between the graphene diaphragm and its substrate created a low finesse FP interferometer with a cavity length of 36.13 μm. Double reference FP cavities using two cleaved optical fibers as reflectors were also constructed to differentially cancel the thermal expansion effects of the trapped gas and adhesive material. A temperature test demonstrated an approximate cavity length change of 166.1 nm °C-1 caused by film thermal expansion in the range of 20-60 °C. Then along with the established thermal deformation model of the suspended circular diaphragm, the calculated CTE ranging from  -9.98  ×  10-6 K-1 to  -2.09  ×  10-6 K-1 conformed well to the previously measured results. The proposed method would be applicable in other types of elastic materials as the sensitive diaphragm of an EFPI sensor over a wide temperature range.

  14. Validation of a Hybrid Microwave-Optical Monitor to Investigate Thermal Provocation in the Microvasculature.

    PubMed

    Al-Armaghany, Allann; Tong, Kenneth; Highton, David; Leung, Terence S

    2016-01-01

    We have previously developed a hybrid microwave-optical system to monitor microvascular changes in response to thermal provocation in muscle. The hybrid probe is capable of inducing deep heat from the skin surface using mild microwaves (1-3 W) and raises the tissue temperature by a few degrees Celsius. This causes vasodilation and the subsequent increase in blood volume is detected by the hybrid probe using near infrared spectroscopy. The hybrid probe is also equipped with a skin cooling system which lowers the skin temperature while allowing microwaves to warm up deeper tissues. The hybrid system can be used to assess the condition of the vasculature in response to thermal stimulation. In this validation study, thermal imaging has been used to assess the temperature distribution on the surface of phantoms and human calf, following microwave warming. The results show that the hybrid system is capable of changing the skin temperature with a combination of microwave warming and skin cooling. It can also detect thermal responses in terms of changes of oxy/deoxy-hemoglobin concentrations.

  15. Fiber-optic temperature profiling for thermal protection system heat shields

    NASA Astrophysics Data System (ADS)

    Black, Richard J.; Costa, Joannes M.; Zarnescu, Livia; Hackney, Drew A.; Moslehi, Behzad; Peters, Kara J.

    2016-11-01

    To achieve better designs for spacecraft heat shields for missions requiring atmospheric aero-capture or entry/reentry, reliable thermal protection system (TPS) sensors are needed. Such sensors will provide both risk reduction and heat-shield mass minimization, which will facilitate more missions and enable increased payloads and returns. This paper discusses TPS thermal measurements provided by a temperature monitoring system involving lightweight, electromagnetic interference-immune, high-temperature resistant fiber Bragg grating (FBG) sensors with a thermal mass near that of TPS materials together with fast FBG sensor interrogation. Such fiber-optic sensing technology is highly sensitive and accurate, as well as suitable for high-volume production. Multiple sensing FBGs can be fabricated as arrays on a single fiber for simplified design and reduced cost. Experimental results are provided to demonstrate the temperature monitoring system using multisensor FBG arrays embedded in a small-size super-light ablator (SLA) coupon which was thermally loaded to temperatures in the vicinity of the SLA charring temperature. In addition, a high-temperature FBG array was fabricated and tested for 1000°C operation, and the temperature dependence considered over the full range (cryogenic to high temperature) for which silica fiber FBGs have been subjected.

  16. Non-thermal hot electrons ultrafastly generating hot optical phonons in graphite

    NASA Astrophysics Data System (ADS)

    Ishida, Y.; Togashi, T.; Yamamoto, K.; Tanaka, M.; Taniuchi, T.; Kiss, T.; Nakajima, M.; Suemoto, T.; Shin, S.

    2011-08-01

    Investigation of the non-equilibrium dynamics after an impulsive impact provides insights into couplings among various excitations. A two-temperature model (TTM) is often a starting point to understand the coupled dynamics of electrons and lattice vibrations: the optical pulse primarily raises the electronic temperature Tel while leaving the lattice temperature Tl low; subsequently the hot electrons heat up the lattice until Tel = Tl is reached. This temporal hierarchy owes to the assumption that the electron-electron scattering rate is much larger than the electron-phonon scattering rate. We report herein that the TTM scheme is seriously invalidated in semimetal graphite. Time-resolved photoemission spectroscopy (TrPES) of graphite reveals that fingerprints of coupled optical phonons (COPs) occur from the initial moments where Tel is still not definable. Our study shows that ultrafast-and-efficient phonon generations occur beyond the TTM scheme, presumably associated to the long duration of the non-thermal electrons in graphite.

  17. Diagnosis of Thermal Efficiency of Combined Cycle Power Plants Using Optical Torque Sensors

    NASA Astrophysics Data System (ADS)

    Umezawa, Shuichi

    A new optical torque measurement method is proposed for diagnosis of thermal efficiency of combined cycle power plants. In the case that the plant comprises a steam turbine and a gas turbine, both of which are connected to the same generator, it is difficult to identify which turbine causes deterioration of performance when the plant efficiency is reduced. Therefore, an optical torque sensor has been developed to measure the output of each turbine, which are important data to analyze performance of each machineries in a plant. The sensor measures axial distortion caused by power transmission by use of He-Ne laser beams, small stainless steel reflectors having bar-code patterns, and a technique of signal processing featuring high frequency. It was applied to TOKYO ELECTRIC POWER COMPANY (TEPCO) commercial plants. Following system improvements, it is concluded that error factors can be eliminated and sensor performance can reach a practical use level.

  18. Tunable optical transition in polymeric carbon nitrides synthesized via bulk thermal condensation

    NASA Astrophysics Data System (ADS)

    Tyborski, T.; Merschjann, C.; Orthmann, S.; Yang, F.; Lux-Steiner, M.-Ch; Schedel-Niedrig, Th

    2012-04-01

    Polymeric derivatives of dicyandiamide were synthesized via a bulk thermal condensation method, using a range of process temperatures between 400 and 610 °C. The obtained carbon nitride powders exhibit an optical transition in the UV-green range that has been assigned to the direct bandgap of a semiconductor-like material. Within this context, the apparent bandgap is linearly tunable with increasing process temperatures, showing a temperature coefficient of - 1.7(1) meV K-1 between 2.5 and 3.0 eV. The obtained results show a predominant optical transition within the tri-s-triazine unit of the polymer, with a bathochromic shift originating from a gradually increasing degree of polymerization.

  19. Incorporation of oxygen into thermally evaporated germanium and optical characterization of the resulting films

    SciTech Connect

    Al-Kuhaili, M. F.; Durrani, S. M. A.

    2007-09-01

    Germanium powder was thermally evaporated under a vacuum onto unheated substrates as well as substrates heated to 200 deg. C. The striking feature was that the resulting films were transparent. Chemical analysis using x-ray photoelectron spectroscopy depth profiling indicated that oxygen was present throughout the thickness of the films, and therefore the films were composed of substoichiometric germanium oxide. The source of oxygen was investigated, and traced to the source material. Subsequently, the optical constants and the band gaps of the films were determined from spectrophotometric measurements. These properties were found to be intermediate between those of pure germanium and germanium dioxide, with values appropriate for optical applications in the visible range.

  20. Acquisition, Tracking, and Pointing Using Earth Thermal Images for Deep Space Optical Communications

    NASA Technical Reports Server (NTRS)

    Ortiz, Gerry G.; Lee, Shinhak

    2003-01-01

    The feasibility of using long wavelength Earth thermal (infrared) images for telescope tracking/pointing application. for both Deep Space Free- pace Optical Communications has been investigated and is reported her. The advantage of this technology rests on using full Earth images in this band, which yield more accurate estimates of geometric centroids than that of Earth images in the visible band. Another major advantage is that these images are nearly independent of Earth phase angle. The results of the study show that at a Mars range, with currently available sensors, a noise equivalent angle of 10 to 150 nanoradians and a bias error of better than 80 nanoradians can be obtained. This enables precise pointing of the optical communications beam for high data rate links.

  1. Structural and optical characterization of thermally evaporated bismuth and antimony films for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Srimathy, N.; Ruban Kumar, A.

    2016-05-01

    In this present study, the thin film of bismuth and antimony is coated by thermal evaporation system equipped with the inbuilt ultra high vacuum system. XRD analysis confirmed the rhombohedral structure of Bismuth and Antimony on the prepared film. The surface roughness and physical appearance is analyzed by Atomic force microscopy. The results of Raman Spectroscopy show the wave functions and the spectrum of electrons. The preparation technique and conditions strongly influence the crystalline structure and the phase composition of bismuth and antimony thin films. The electrical and optical properties for the prepared film are analyzed. The results show a great interest and promising applications in Photovoltaic devices.

  2. Apparatus and method for measurement of weak optical absorptions by thermally induced laser pulsing

    DOEpatents

    Cremers, D.A.; Keller, R.A.

    1982-06-08

    The thermal lensing phenomenon is used as the basis for measurement of weak optical absorptions when a cell containing the sample to be investigated is inserted into a normally continuous-wave operation laser-pumped dye laser cavity for which the output coupler is deliberately tilted relative to intracavity circulating laser light, and pulsed laser output ensues, the pulsewidth of which can be rlated to the sample absorptivity by a simple algorithm or calibration curve. A minimum detection limit of less than 10/sup -5/ cm/sup -1/ has been demonstrated using this technique.

  3. Apparatus and method for measurement of weak optical absorptions by thermally induced laser pulsing

    DOEpatents

    Cremers, David A.; Keller, Richard A.

    1985-01-01

    The thermal lensing phenomenon is used as the basis for measurement of weak optical absorptions when a cell containing the sample to be investigated is inserted into a normally continuous-wave operation laser-pumped dye laser cavity for which the output coupler is deliberately tilted relative to intracavity circulating laser light, and pulsed laser output ensues, the pulsewidth of which can be related to the sample absorptivity by a simple algorithm or calibration curve. A minimum detection limit of less than 10.sup.-5 cm.sup.-1 has been demonstrated using this technique.

  4. Optical, elastic and thermal properties of ZB-AlN semiconductor from first-principle calculations

    NASA Astrophysics Data System (ADS)

    Kumar, V.; Singh, Bhanu P.; Chandra, Satish

    2017-04-01

    The optical, elastic and thermal properties of zincblende aluminium nitride have been studied. The refractive index, absorption coefficient, reflectivity, dielectric constant, extinction coefficient, and energy-loss spectrum have been calculated using the pseudo-potential method under density functional theory at different pressures. The heat capacity, Debye temperature and phonon frequencies have been calculated using CASTEP code at 0 GPa. The elastic stiffness constants, bulk modulus, Young's modulus, shear modulus and pressure derivatives of elastic constants have also been calculated. The calculated results are compared with the available experimental and theoretical data. Reasonably good agreement has been found between them.

  5. The dependence of optical turbulence on thermal and mechanical forces over the sea

    NASA Astrophysics Data System (ADS)

    van Eijk, Alexander M. J.; Sprung, Detlev; Sucher, Erik; Eisele, Christian; Seiffer, Dirk; Stein, Karin

    2016-09-01

    Optical turbulence for over-water conditions was investigated in a long-term experiment over False Bay near Cape Town, South Africa. A sonic anemometer and two boundary-layer scintillometers were deployed to access in-situ turbulence as well as the integrated turbulence over two 1.8 and 8.7 km paths. Statistical analysis reveals spatial temporal variations of the turbulence conditions over False Bay, which might be related to differences in the atmospheric conditions and/or the surface (water) temperatures. An analysis in terms of mechanical and thermal forcing reveals that the latter factor is more dominant in determining the turbulence strength.

  6. Synthesis, growth, structural, thermal and optical studies of pyrrolidinium-2-carboxylate-4-nitrophenol single crystals

    NASA Astrophysics Data System (ADS)

    Swarna Sowmya, N.; Sampathkrishnan, S.; Vidyalakshmi, Y.; Sudhahar, S.; Mohan Kumar, R.

    2015-06-01

    Organic nonlinear optical material, pyrrolidinium-2-carboxylate-4-nitrophenol (PCN) was synthesized and single crystals were grown by slow evaporation solution growth method. Single crystal X-ray diffraction analysis confirmed the structure and lattice parameters of PCN crystals. Infrared, Raman and NMR spectral analyses were used to elucidate the functional groups present in the compound. The thermal behavior of synthesized compound was studied by thermogravimetric and differential scanning calorimetry (TG-DSC) analyses. The photoluminescence property was studied by exciting the crystal at 360 nm. The relative second harmonic generation (SHG) efficiency of grown crystal was estimated by using Nd:YAG laser with fundamental wavelength of 1064 nm.

  7. Thermal, optical, and electrical engineering of an innovative tunable white LED light engine

    NASA Astrophysics Data System (ADS)

    Trivellin, Nicola; Meneghini, Matteo; Ferretti, Marco; Barbisan, Diego; Dal Lago, Matteo; Meneghesso, Gaudenzio; Zanoni, Enrico

    2014-02-01

    Color temperature, intensity and blue spectrum of the light affects the ganglion receptors in human brain stimulating the human nervous system. With this work we review different methods for obtaining tunable light emission spectra and propose an innovative white LED lighting system. By an in depth study of the thermal, electrical and optical characteristics of GaN and GaP based compound semiconductors for optoelectronics a specific tunable spectra has been designed. The proposed tunable white LED system is able to achieve high CRI (above 95) in a large CCT range (3000 - 5000K).

  8. Apparatus and method for measurement of weak optical absorptions by thermally induced laser pulsing

    DOEpatents

    Cremers, D.A.; Keller, R.A.

    1985-10-01

    The thermal lensing phenomenon is used as the basis for measurement of weak optical absorptions when a cell containing the sample to be investigated is inserted into a normally continuous-wave operation laser-pumped dye laser cavity for which the output coupler is deliberately tilted relative to intracavity circulating laser light, and pulsed laser output ensues, the pulsewidth of which can be related to the sample absorptivity by a simple algorithm or calibration curve. A minimum detection limit of less than 10[sup [minus]5] cm[sup [minus]1] has been demonstrated using this technique. 6 figs.

  9. Optical, elastic and thermal properties of ZB-AlN semiconductor from first-principle calculations

    NASA Astrophysics Data System (ADS)

    Kumar, V.; Singh, Bhanu P.; Chandra, Satish

    2016-12-01

    The optical, elastic and thermal properties of zincblende aluminium nitride have been studied. The refractive index, absorption coefficient, reflectivity, dielectric constant, extinction coefficient, and energy-loss spectrum have been calculated using the pseudo-potential method under density functional theory at different pressures. The heat capacity, Debye temperature and phonon frequencies have been calculated using CASTEP code at 0 GPa. The elastic stiffness constants, bulk modulus, Young's modulus, shear modulus and pressure derivatives of elastic constants have also been calculated. The calculated results are compared with the available experimental and theoretical data. Reasonably good agreement has been found between them.

  10. Theoretical and experimental optical studies of cholesteric liquid crystal films with thermally induced pitch gradients.

    PubMed

    Zografopoulos, Dimitrios C; Kriezis, Emmanouil E; Mitov, Michel; Binet, Corinne

    2006-06-01

    The reflection properties of cholesteric films with thermally induced pitch gradients are theoretically and experimentally studied. It is shown that the optical behavior of such films corresponds to the averaged contribution of a number of stochastic pitch variation profiles, due to the transversal and longitudinal nonuniformities that develop in the helical structure of such samples. Depending on the annealing time, both narrow-band and broadband behavior can be selectively achieved. The influence of the pitch profile gradient on the broadband reflection performance of cholesteric samples is theoretically analyzed, and a multi-slab structure for achieving optimum efficiency is proposed.

  11. Measurement of the optical fiber numeric aperture exposed to thermal and radiation aging

    NASA Astrophysics Data System (ADS)

    Vanderka, Ales; Bednarek, Lukas; Hajek, Lukas; Latal, Jan; Poboril, Radek; Zavodny, Petr; Vasinek, Vladimir

    2016-12-01

    This paper deals with the aging of optical fibers influenced by temperature and radiation. There are analyzed changes in the structure of the optical fiber, related to the propagation of light in the fiber structure. In this case for numerical aperture. For experimental measurement was used MM fiber OM1 with core diameter 62.5 μm, cladding diameter 125 μm in 2.8 mm secondary coating. Aging of the optical fiber was achieved with dry heat and radiation. For this purpose, we were using a temperature chamber with a stable temperature of 105 °C where the cables after two months. Cables were then irradiated with gamma radiation 60Co in doses of 1.5 kGy and then 60 kGy. These conditions simulated 50 years aging process of optical cables. According to European Standard EN 60793-1-43:2015 was created the automatic device for angular scan working with LabVIEW software interface. Numerical aperture was tested at a wavelength of 850 nm, with an output power 1 mW. Scanning angle was set to 50° with step 0.25°. Numerical aperture was calculated from the position where power has fallen from maximal power at e2 power. The measurement of each sample was performed 10 hours after thermal and radiation aging. The samples were subsequently tested after six months from the last irradiation. In conclusion, the results of the experiment were analyzed and compared.

  12. Thermal and optical modeling of "blackened" tips for diode laser surgery

    NASA Astrophysics Data System (ADS)

    Belikov, Andrey V.; Skrypnik, Alexei V.; Kurnyshev, Vadim Y.

    2016-04-01

    This paper presents the results of thermal and optical modeling of "blackened" tips (fiber-optic thermal converter) with different structures: film and volumetric. Film converter is created by laser radiation action on a cork or paper and it is a one-step process. As a result, a carbonized cork or paper adhered to the distal end of the optical fiber absorbs light that leads to heating of the distal end of the optical fiber. We considered the peculiarities of volumetric converters formed by sintering (second step) of the target material transferred to the tip, at irradiating the target with laser radiation (first step). We investigated the interaction between 980 nm laser radiation and converters in the air and water. As a result of experiments and modeling, it was obtain, that converter temperature and power of converter destruction depend on the environment in which it is placed. We found that film converter in the air at average power of laser radiation of 0.30+/-0.05 W is heated to 900+/-50°C and destructed, and volumetric converter in the air at average power of laser radiation of 1.0+/-0.1 W is heated to 1000+/-50°C and destructed at reaching of 4.0+/-0.1 W only. We found that film converter in the water at average power of laser radiation of 1.0+/-0.1 W is heated to 550+/-50°C and destructed at reaching of 4.0+/-0.1 W only. Volumetric converter at average power of laser radiation of4.0+/-0.1 W is heated to 450+/-50°C and is not destructed up to 7.5+/-0.1 W, it is heated to 500+/-50°C in this case. Thus, volumetric converter is more resistant to action of laser heating.

  13. Development, characterization, and application of the DRI model 2015 multiwavelength thermal-optical carbon analyzer

    NASA Astrophysics Data System (ADS)

    Sumlin, Benjamin J.

    A multiwavelength thermal/optical carbon analyzer (DRI Model 2015) equipped with a novel seven-wavelength light source (405, 445, 532, 635, 780, 808, and 980 nm) was developed to analyze chemical and optical properties of carbonaceous particles collected on quartz-fiber filters. Built upon on the DRI Model 2001 carbon analyzer at 633 nm, major modifications were made to mechanical and electrical components, flow control, and the carbon detector to adopt modern technologies, increase instrument reliability, and reduce costs and maintenance. This instrument quantifies organic and elemental carbon (OC and EC, respectively) and their thermal fractions. It also allows estimation of the amount of brown and black carbon (BrC and BC, respectively) on filters. Continuous monitoring of the light reflected from and transmitted through the filter along with carbon evolved from the filter when heated to different temperatures under either inert or oxidizing gas environments provides insights into the optical properties of the carbon released from the filter; it also allows examination of the charring process as pyrolyzed char has been one of the major uncertainties in quantifying OC and EC. The objectives of this study are: 1) characterize the Model 2015's performance parameters including detection limits, and optical behavior; 2) establish performance equivalence between the Model 2015 and Model 2001 DRI carbon analyzers when comparing similar laser wavelength to maintain consistency for long-term network sample analysis; and 3) conduct a preliminary analysis of the multiwavelength signal to estimate BrC and BC, and to optimize char correction. A selection of samples, including standard chemicals, as well as rural and urban ambient filter samples were measured by both the Model 2015 and Model 2001 analyzers. The design and construction experience will be discussed, as well as recommended future scientific research and engineering development.

  14. Predicting ambient aerosol Thermal Optical Reflectance (TOR) measurements from infrared spectra: elemental carbon

    NASA Astrophysics Data System (ADS)

    Dillner, A. M.; Takahama, S.

    2015-06-01

    Elemental carbon (EC) is an important constituent of atmospheric particulate matter because it absorbs solar radiation influencing climate and visibility and it adversely affects human health. The EC measured by thermal methods such as Thermal-Optical Reflectance (TOR) is operationally defined as the carbon that volatilizes from quartz filter samples at elevated temperatures in the presence of oxygen. Here, methods are presented to accurately predict TOR EC using Fourier Transform Infrared (FT-IR) absorbance spectra from atmospheric particulate matter collected on polytetrafluoroethylene (PTFE or Teflon) filters. This method is similar to the procedure tested and developed for OC in prior work (Dillner and Takahama, 2015). Transmittance FT-IR analysis is rapid, inexpensive, and non-destructive to the PTFE filter samples which are routinely collected for mass and elemental analysis in monitoring networks. FT-IR absorbance spectra are obtained from 794 filter samples from seven Interagency Monitoring of PROtected Visual Environment (IMPROVE) sites collected during 2011. Partial least squares regression is used to calibrate sample FT-IR absorbance spectra to collocated TOR EC measurements. The FTIR spectra are divided into calibration and test sets. Two calibrations are developed, one which is developed from uniform distribution of samples across the EC mass range (Uniform EC) and one developed from a~uniform distribution of low EC mass samples (EC < 2.4 μg, Low Uniform EC). A hybrid approach which applies the low EC calibration to low EC samples and the Uniform EC calibration to all other samples is used to produces predictions for low EC samples that have mean error on par with parallel TOR EC samples in the same mass range and an estimate of the minimum detection limit (MDL) that is on par with TOR EC MDL. For all samples, this hybrid approach leads to precise and accurate TOR EC predictions by FT-IR as indicated by high coefficient of variation (R2; 0.96), no

  15. Predicting ambient aerosol thermal-optical reflectance measurements from infrared spectra: elemental carbon

    NASA Astrophysics Data System (ADS)

    Dillner, A. M.; Takahama, S.

    2015-10-01

    Elemental carbon (EC) is an important constituent of atmospheric particulate matter because it absorbs solar radiation influencing climate and visibility and it adversely affects human health. The EC measured by thermal methods such as thermal-optical reflectance (TOR) is operationally defined as the carbon that volatilizes from quartz filter samples at elevated temperatures in the presence of oxygen. Here, methods are presented to accurately predict TOR EC using Fourier transform infrared (FT-IR) absorbance spectra from atmospheric particulate matter collected on polytetrafluoroethylene (PTFE or Teflon) filters. This method is similar to the procedure developed for OC in prior work (Dillner and Takahama, 2015). Transmittance FT-IR analysis is rapid, inexpensive and nondestructive to the PTFE filter samples which are routinely collected for mass and elemental analysis in monitoring networks. FT-IR absorbance spectra are obtained from 794 filter samples from seven Interagency Monitoring of PROtected Visual Environment (IMPROVE) sites collected during 2011. Partial least squares regression is used to calibrate sample FT-IR absorbance spectra to collocated TOR EC measurements. The FT-IR spectra are divided into calibration and test sets. Two calibrations are developed: one developed from uniform distribution of samples across the EC mass range (Uniform EC) and one developed from a uniform distribution of Low EC mass samples (EC < 2.4 μg, Low Uniform EC). A hybrid approach which applies the Low EC calibration to Low EC samples and the Uniform EC calibration to all other samples is used to produce predictions for Low EC samples that have mean error on par with parallel TOR EC samples in the same mass range and an estimate of the minimum detection limit (MDL) that is on par with TOR EC MDL. For all samples, this hybrid approach leads to precise and accurate TOR EC predictions by FT-IR as indicated by high coefficient of determination (R2; 0.96), no bias (0.00 μg m-3, a

  16. Measurements of the thermal coefficient of optical attenuation at different depth regions of in vivo human skins using optical coherence tomography: a pilot study.

    PubMed

    Su, Ya; Yao, X Steve; Li, Zhihong; Meng, Zhuo; Liu, Tiegen; Wang, Longzhi

    2015-02-01

    We present detailed measurement results of optical attenuation's thermal coefficients (referenced to the temperature of the skin surface) in different depth regions of in vivo human forearm skins using optical coherence tomography (OCT). We first design a temperature control module with an integrated optical probe to precisely control the surface temperature of a section of human skin. We propose a method of using the correlation map to identify regions in the skin having strong correlations with the surface temperature of the skin and find that the attenuation coefficient in these regions closely follows the variation of the surface temperature without any hysteresis. We observe a negative thermal coefficient of attenuation in the epidermis. While in dermis, the slope signs of the thermal coefficient of attenuation are different at different depth regions for a particular subject, however, the depth regions with a positive (or negative) slope are different in different subjects. We further find that the magnitude of the thermal coefficient of attenuation coefficient is greater in epidermis than in dermis. We believe the knowledge of such thermal properties of skins is important for several noninvasive diagnostic applications, such as OCT glucose monitoring, and the method demonstrated in this paper is effective in studying the optical and biological properties in different regions of skin.

  17. Retrieval of volcanic ash particle size, mass and optical depth from a ground-based thermal infrared camera

    NASA Astrophysics Data System (ADS)

    Prata, A. J.; Bernardo, C.

    2009-09-01

    Volcanoes can emit fine-sized ash particles (1-10 μm radii) into the atmosphere and if they reach the upper troposphere or lower stratosphere, these particles can have deleterious effects on the atmosphere and climate. If they remain within the lowest few kilometers of the atmosphere, the particles can lead to health effects in humans and animals and also affect vegetation. It is therefore of some interest to be able to measure the particle size distribution, mass and other optical properties of fine ash once suspended in the atmosphere. A new imaging camera working in the infrared region between 7-14 μm has been developed to detect and quantify volcanic ash. The camera uses passive infrared radiation measured in up to five spectral channels to discriminate ash from other atmospheric absorbers (e.g. water molecules) and a microphysical ash model is used to invert the measurements into three retrievable quantities: the particle size distribution, the infrared optical depth and the total mass of fine particles. In this study we describe the salient characteristics of the thermal infrared imaging camera and present the first retrievals from field studies at an erupting volcano. An automated ash alarm algorithm has been devised and tested and a quantitative ash retrieval scheme developed to infer particle sizes, infrared optical depths and mass in a developing ash column. The results suggest that the camera is a useful quantitative tool for monitoring volcanic particulates in the size range 1-10 μm and because it can operate during the night, it may be a very useful complement to other instruments (e.g. ultra-violet spectrometers) that only operate during daylight.

  18. Investigation on Thermal and Optical Properties of Hydrogen-Bonded Binary Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Ranjeeth kumar, T.; Sundaram, S.; Vasanthi, T.; Subhasri, P.; Chitravel, T.; Senthil, T. S.; Jayaprakasam, R.; Vijayakumar, V. N.

    2016-12-01

    A homologous series of hydrogen-bonded liquid crystals (HBLCs) are synthesized and characterized. Intermolecular hydrogen bonding occurs between 4-methoxycinnamic acid (4MCA) and p-n-alkyloxy benzoic acids (nOBA, where n = 3, 7 to 12). These binary complexes have been obtained by following well-designed synthesis route. The subsequent binary complexes have been characterized by polarizing optical thermal microscopy (POM), differential scanning calorimetry (DSC), and Fourier transform infrared spectroscopy (FTIR). The present work explains the details of the association between the mesogenic phase behavior and H-bonding in the homologous series of 4MCA + nOBA. Nematic phase is interrelated with the closed dimers between acid molecules through the formation of strong hydrogen bonds. But, high concentrations are linked to the manifestation of smectic phases that disturb the local order of the nematic phase. As a result, the higher-order mesophases are observed in the present binary complex series. The inclusion of nematic LC (4MCA) in the nOBA alters the melting temperature and the clearing temperature as lower than those of the individual. Also, the wide mesophase regions of the present series are identified compared to those of the constituent mesogens. The optical tilt angle of binary mixtures for smectic C phase and thermal stability factors of the mesogenic phases have been discussed.

  19. Analysis of thermal radiation in ion traps for optical frequency standards

    NASA Astrophysics Data System (ADS)

    Doležal, M.; Balling, P.; Nisbet-Jones, P. B. R.; King, S. A.; Jones, J. M.; Klein, H. A.; Gill, P.; Lindvall, T.; Wallin, A. E.; Merimaa, M.; Tamm, C.; Sanner, C.; Huntemann, N.; Scharnhorst, N.; Leroux, I. D.; Schmidt, P. O.; Burgermeister, T.; Mehlstäubler, T. E.; Peik, E.

    2015-12-01

    In many of the high-precision optical frequency standards with trapped atoms or ions that are under development to date, the ac Stark shift induced by thermal radiation leads to a major contribution to the systematic uncertainty. We present an analysis of the inhomogeneous thermal environment experienced by ions in various types of ion traps. Finite element models which allow the determination of the temperature of the trap structure and the temperature of the radiation were developed for five ion trap designs, including operational traps at PTB and NPL and further optimized designs. Models were refined based on comparison with infrared camera measurement until an agreement of better than 10% of the measured temperature rise at critical test points was reached. The effective temperature rises of the radiation seen by the ion range from 0.8 K to 2.1 K at standard working conditions. The corresponding fractional frequency shift uncertainties resulting from the uncertainty in temperature are in the 10-18 range for optical clocks based on the Sr+ and Yb+ E2 transitions, and even lower for Yb+ E3, In+ and Al+. Issues critical for heating of the trap structure and its predictability were identified and design recommendations developed.

  20. Light weight optics made by glass thermal forming for future x-ray telescopes

    NASA Astrophysics Data System (ADS)

    Winter, Anita; Vongehr, Monika; Friedrich, Peter

    2010-07-01

    Future X-ray observatory missions, such as IXO or Gen-X, require grazing incidence optics of large collecting area in combination with a very good angular resolution. Wolter type I X-ray telescopes made of slumped glass segments could be a possible alternative to silicon pore optics. To achieve these requirements we develop slumping methods for high accuracy segments by experimental means. In particular, we follow the approach of indirect slumping and aim to produce parabola and hyperbola in one piece. In order to avoid internal stress in the glass segments the thermal expansion coefficient of the glass should closely match the thermal expansion of the mould material. Currently we focus on a combination of the alloy KOVAR for the mould and D263 for the glass; additionally a platinum-coated silica as mould material is studied. We investigate the behaviour of both materials during slumping in order to obtain the ideal environment for the slumping process. Additionally we report on the design of different metrology methods to measure the figure and thickness variations of the glass segments in visual light, e.g. interference, and on bearings used for shape measurements and integration.

  1. Automatic Mapping of Glacier Based on SAR Imagery by Benefits of Freely Optical and Thermal Data

    NASA Astrophysics Data System (ADS)

    Fang, L.; Hoegner, L.; Stilla, U.

    2015-03-01

    For many research applications like water resources evaluation, determination of glacier specific changes, and for calculation of the past and future contribution of glaciers to sea-level change, parameters about the size and spatial distribution of glaciers is crucial. In this paper, an automatic method for determination of glacier surface area using single track high resolution TerraSAR-X imagery by benefits of low resolution optical and thermal data is presented. Based on the normalized difference snow index (NDSI) and land surface temperature (LST) map generated from optical and thermal data combined with a surface slope data, a low resolution binary mask was derived used for the supervised classification of glacier using SAR imagery. Then, a set of suitable features is derived from the SAR intensity image, such as the texture information generated based on the gray level co-occurrence matrix (GLCM), and the intensity values. With these features, the glacier surface is discriminated from the background by Random Forests (RF) method.

  2. Fiber optic sensor reliability issues in structural health monitoring

    NASA Astrophysics Data System (ADS)

    Xu, Zhihong; Bassam, Asadollah; Jia, Hongqiang; Tennant, Adam; Ansari, Farhad

    2005-05-01

    Reliability is an important aspect of any sensor, and especially in terms of long term monitoring of structures. Some issues pertaining to the reliability of optical fiber sensors in civil structures are discussed in this article. The strength and fatigue properties of optical fibers influence their performance, and life span. Lessons learnt from the reliability of optical fibers in the telecommunication industry are useful for assessment of reliability in optical fiber sensors. However, optical fiber sensors go through additional manufacturing steps, handling processes, and in general operate under environmental conditions and stress levels different from the telecommunication lines. In general, optical fiber sensors in structures are subjected to fatigue loading under high stresses. Other reliability concerns pertain to the effects of the packaging, installation issues at the construction site. These issues along with some of the results acquired from fatigue tests on fiber optic Bragg gratings and long gauge interferometric sensors are discussed in this article.

  3. Optical and thermal properties of nickel(II) hydrazone complex for recordable blu-ray storage

    NASA Astrophysics Data System (ADS)

    Chen, Zhimin; Wu, Yiqun; Gu, Donghong; Gan, Fuxi

    2009-08-01

    A nickel(II) hydrazone complex was synthesized in order to obtain a suitable optical recording medium for the new generation recordable blu-ray disk. Smooth thin films of the nickel(II) hydrazone complex were prepared by using the spin-coating method. Absorption and reflectance spectra of the thin films were evaluated in the wavelength 300-700 nm. Thermal properties of the nickel(II) complex were investigated by thermogravimetry (TG) and differential scanning calorimetry (DSC). Optical constants (complex refractive indices N=n+ik) and thickness of the thin film, prepared on single-crystal silicon substrate, were investigated on a rotating analyzer-polarizer scanning ellipsometer in the wavelength 285-705 nm. In addition, in order to examine its possible use as a blu-ray recording medium, the spin-coated film of the nickel(II) complex was prepared on K9 glass substrate with a silver reflective layer, and was studied by static optical recording testing system with a 406.7 nm laser. It is found that the absorption spectra of the thin film has an strong absorption band in the wavelength region 360-420 nm and a moderate absorbance at the 405 nm side, which indicates that the absorption of the film is well matched with the laser wavelength of the 405 nm. The reflectance spectra show that a high reflectivity of the thin film at 405 nm wavelength can be obtained by an optimum film thickness and an appropriate metal reflective layer. The thin film of the nickel(II) complex gives a high n value of 1.62 and a low k value of 0.33, corresponding to the wavelength of the blue laser of 405 nm. Measurements of the thermal properties show that the nickel(II) complex holds a high thermal stability (~ 300 °C) and a sharp weight loss which are helpful to fabricate a small and sharp recording mark edge. The results of the static optical recording test, using the nickel(II) complex thin film as the recording layer, demonstrate that high reflectivity contrast (>50 %) can be obtained at

  4. Comparison of MESSENGER Optical Images with Thermal and Radar Data for the Surface of MERCURY

    NASA Astrophysics Data System (ADS)

    Blewett, D. T.; Coman, E. I.; Chabot, N. L.; Izenberg, N. R.; Harmon, J. K.; Neish, C.

    2010-12-01

    Images collected by the MESSENGER spacecraft during its three Mercury flybys cover nearly the entire surface of the planet that was not imaged by Mariner 10. The MESSENGER data now allow us to observe features at optical wavelengths that were previously known only through remote sensing in other portions of the electromagnetic spectrum. For example, the Mariner 10 infrared (IR) radiometer made measurements along a track on the night side of Mercury during the spacecraft's first encounter in 1974. Analysis of the IR radiometer data identified several thermal anomalies that we have correlated to craters with extensive rays or ejecta deposits, including Xiao Zhao and Eminescu. The thermal properties are consistent with a greater exposure of bare rock (exposed in steep walls or as boulders and cobbles) in and around these craters compared with the lower-thermal-inertia, finer-grained regolith of the surrounding older surface. The portion of Mercury not viewed by Mariner 10 has also been imaged by Earth-based radar. The radar backscatter gives information on the wavelength-scale surface roughness. Arecibo S-band (12.6-cm wavelength) radar observations have produced images of Eminescu and also revealed two spectacular rayed craters (Debussy and Hokusai) that have since been imaged by MESSENGER. We are examining radial profiles for these craters, extracted from both the radar images and MESSENGER narrow-angle camera mosaics, that extend from the crater center outwards to a distance of several crater diameters. Comparison of optical and radar profiles for the craters, as well as similar profiles for lunar craters, can provide insight into ejecta deposition, the effect of surface gravity on the cratering process, and space weathering.

  5. Optical detection of nanometric thermal fluctuations to measure the stiffness of rigid superparamagnetic microrods.

    PubMed

    Gerbal, Fabien; Wang, Yuan

    2017-03-07

    The rigidity of numerous biological filaments and crafted microrods has been conveniently deduced from the analysis of their thermal fluctuations. However, the difficulty of measuring nanometric displacements with an optical microscope has so far limited such studies to sufficiently flexible rods, of which the persistence length ([Formula: see text]) rarely exceeds 1 m at room temperature. Here, we demonstrate the possibility to probe 10-fold stiffer rods by a combination of superresolutive optical methods and a statistical analysis of the data based on a recent theoretical model that predicts the amplitude of the fluctuations at any location of the rod [Benetatos P, Frey E (2003) Phys Rev E Stat Nonlin Soft Matter Phys 67(5):051108]. Using this approach, we report measures of [Formula: see text] up to 0.5 km. We obtained these measurements on recently designed superparamagnetic [Formula: see text]40-[Formula: see text]m-long microrods containing iron-oxide nanoparticles connected by a polymer mesh. Using their magnetic properties, we provide an alternative proof of validity of these thermal measurements: For each individual studied rod, we performed a second measure of its rigidity by deflecting it with a uniform magnetic field. The agreement between the thermal and the magnetoelastic measures was realized with more than a decade of values of [Formula: see text] from 5.1 m to 129 m, corresponding to a bending modulus ranging from 2.2 to 54 (×[Formula: see text] Jm). Despite the apparent homogeneity of the analyzed microrods, their Young modulus follows a broad distribution from 1.9 MPa to 59 MPa and up to 200 MPa, depending on the size of the nanoparticles.

  6. Optical-thermal mathematical model for endovenous laser ablation of varicose veins.

    PubMed

    van Ruijven, Peter W M; Poluektova, Anna A; van Gemert, Martin J C; Neumann, H A Martino; Nijsten, Tamar; van der Geld, Cees W M

    2014-03-01

    Endovenous laser ablation (EVLA) is successfully used to treat varicose veins. However, the exact working mechanism is still not fully identified and the clinical procedure is not yet standardized. Mathematical modeling of EVLA could strongly improve our understanding of the influence of the various EVLA processes. The aim of this study is to combine Mordon's optical-thermal model with the presence of a strongly absorbing carbonized blood layer on the fiber tip. The model anatomy includes a cylindrically symmetric blood vessel surrounded by an infinite homogenous perivenous tissue. The optical fiber is located in the center of the vessel and is withdrawn with a pullback velocity. The fiber tip includes a small layer of strongly absorbing material, representing the layer of carbonized blood, which absorbs 45% of the emitted laser power. Heat transfer due to boiling bubbles is taken into account by increasing the heat conduction coefficient by a factor of 200 for temperatures above 95 °C. The temperature distribution in the blood, vessel wall, and surrounding medium is calculated from a numerical solution of the bioheat equation. The simulations were performed in MATLAB™ and validated with the aid of an analytical solution. The simulations showed, first, that laser wavelength did virtually not influence the simulated temperature profiles in blood and vessel wall, and, second, that temperatures of the carbonized blood layer varied slightly, from 952 to 1,104 °C. Our improved mathematical optical-thermal EVLA model confirmed previous predictions and experimental outcomes that laser wavelength is not an important EVLA parameter and that the fiber tip reaches exceedingly high temperatures.

  7. Structural, thermal and optical absorption features of heavy metal oxides doped tellurite rich glasses

    NASA Astrophysics Data System (ADS)

    Kaky, Kawa M.; Lakshminarayana, G.; Baki, S. O.; Kityk, I. V.; Taufiq-Yap, Y. H.; Mahdi, M. A.

    In order to improve tellurite glass stability to be applicable for optical fiber amplifier applications, glasses with the composition of (70 - x)TeO2. (10)ZnO. (10)WO3. (5)Na2O. (5)TiO2. (x)Bi2O3 (x = 1, 2, 3, 4, and 5 mol%) have been produced and characterized using the related methods. Structural properties were investigated using X-ray diffraction (XRD) which confirms the non-crystalline structure and scanning electron microscopy (SEM) micrographs also confirm the XRD results. The energy dispersive X-ray (EDX) analysis profiles show that all the mentioned elements are present in the prepared glasses. Following the IR spectra, all the tellurium bonds such as stretching vibrations of TeO4 tbp and TeO3/TeO3+1 unit are revealed. Raman spectra confirm the presence of different functional groups, actually, it shows bands mainly in four spectral regions: R1 (65-150) cm-1, R2 (280-550) cm-1, R3 (880-950) cm-1 and R4 (916-926) cm-1 and the identified bands are assigned to respective molecular groups. The thermal study was carried out using Differential scanning calorimetry (DSC) which indicates good thermal stability of the synthesized glasses with increasing Bi concentration. From the optical absorption spectra, we evaluated cut-off edge wavelengths and found increasing cutoff wavelength with an increase in Bi2O3 concentration. In the UV-Visible region, optical band gap energy and allowed transitions were investigated using three methods; direct, indirect, and absorption spectrum fitting (ASF), and band gaps from indirect and ASF were matched.

  8. Typicality approach to the optical conductivity in thermal and many-body localized phases

    NASA Astrophysics Data System (ADS)

    Steinigeweg, Robin; Herbrych, Jacek; Pollmann, Frank; Brenig, Wolfram

    2016-11-01

    We study the frequency dependence of the optical conductivity Reσ (ω ) of the Heisenberg spin-1/2 chain in the thermal and near the transition to the many-body localized phase induced by the strength of a random z -directed magnetic field. Using the method of dynamical quantum typicality, we calculate the real-time dynamics of the spin-current autocorrelation function and obtain the Fourier transform Reσ (ω ) for system sizes much larger than accessible to standard exact-diagonalization approaches. We find that the low-frequency behavior of Reσ (ω ) is well described by Reσ (ω ) ≈σdc+a |ω| α , with α ≈1 in a wide range within the thermal phase and close to the transition. We particularly detail the decrease of σdc in the thermal phase as a function of increasing disorder for strong exchange anisotropies. We further find that the temperature dependence of σdc is consistent with the existence of a mobility edge.

  9. Fiber Optic Sensors for Temperature Monitoring during Thermal Treatments: An Overview.

    PubMed

    Schena, Emiliano; Tosi, Daniele; Saccomandi, Paola; Lewis, Elfed; Kim, Taesung

    2016-07-22

    During recent decades, minimally invasive thermal treatments (i.e., Radiofrequency ablation, Laser ablation, Microwave ablation, High Intensity Focused Ultrasound ablation, and Cryo-ablation) have gained widespread recognition in the field of tumor removal. These techniques induce a localized temperature increase or decrease to remove the tumor while the surrounding healthy tissue remains intact. An accurate measurement of tissue temperature may be particularly beneficial to improve treatment outcomes, because it can be used as a clear end-point to achieve complete tumor ablation and minimize recurrence. Among the several thermometric techniques used in this field, fiber optic sensors (FOSs) have several attractive features: high flexibility and small size of both sensor and cabling, allowing insertion of FOSs within deep-seated tissue; metrological characteristics, such as accuracy (better than 1 °C), sensitivity (e.g., 10 pm·°C(-1) for Fiber Bragg Gratings), and frequency response (hundreds of kHz), are adequate for this application; immunity to electromagnetic interference allows the use of FOSs during Magnetic Resonance- or Computed Tomography-guided thermal procedures. In this review the current status of the most used FOSs for temperature monitoring during thermal procedure (e.g., fiber Bragg Grating sensors; fluoroptic sensors) is presented, with emphasis placed on their working principles and metrological characteristics. The essential physics of the common ablation techniques are included to explain the advantages of using FOSs during these procedures.

  10. Modifying Mechanical, Optical Properties and Thermal Processability of Iridescent Cellulose Nanocrystal Films Using Ionic Liquid.

    PubMed

    Liu, Ping; Guo, Xin; Nan, Fuchun; Duan, Yongxin; Zhang, Jianming

    2017-01-25

    Iridescent films formed from the self-assembly of cellulose nanocrystals (CNCs) are brittle and difficult to handle or integrate within an industrial process. Here we present a simple approach to prepare iridescent CNC films with tunable pliability and coloration through the addition of ionic liquids (ILs) of 1-allyl-3-methylimidazolium chloride (AmimCl) as plasticizers. By using the undried CNC film as a filter membrane and ILs solution as a leaching liquid, it was found that the filtration process made ILs uniformly interpenetrate into CNC film due to the strong ionic interaction between CNC and AmimCl. Unexpectedly, the filtration process also gave rise to partial desulfurization of CNC film, which is conducive to the improvement of thermal stability. Benefiting from the improved thermal stability and the dissolving capacity of AmimCl for cellulose at high temperature, the incorporated ILs enable the cholesteric CNC film to be further toughened via a hot-pressing treatment. This study demonstrates that ionic liquids have great potential to modify the mechanical, optical properties as well as the thermal stability of iridescent CNC films.

  11. Fiber Optic Sensors for Temperature Monitoring during Thermal Treatments: An Overview

    PubMed Central

    Schena, Emiliano; Tosi, Daniele; Saccomandi, Paola; Lewis, Elfed; Kim, Taesung

    2016-01-01

    During recent decades, minimally invasive thermal treatments (i.e., Radiofrequency ablation, Laser ablation, Microwave ablation, High Intensity Focused Ultrasound ablation, and Cryo-ablation) have gained widespread recognition in the field of tumor removal. These techniques induce a localized temperature increase or decrease to remove the tumor while the surrounding healthy tissue remains intact. An accurate measurement of tissue temperature may be particularly beneficial to improve treatment outcomes, because it can be used as a clear end-point to achieve complete tumor ablation and minimize recurrence. Among the several thermometric techniques used in this field, fiber optic sensors (FOSs) have several attractive features: high flexibility and small size of both sensor and cabling, allowing insertion of FOSs within deep-seated tissue; metrological characteristics, such as accuracy (better than 1 °C), sensitivity (e.g., 10 pm·°C−1 for Fiber Bragg Gratings), and frequency response (hundreds of kHz), are adequate for this application; immunity to electromagnetic interference allows the use of FOSs during Magnetic Resonance- or Computed Tomography-guided thermal procedures. In this review the current status of the most used FOSs for temperature monitoring during thermal procedure (e.g., fiber Bragg Grating sensors; fluoroptic sensors) is presented, with emphasis placed on their working principles and metrological characteristics. The essential physics of the common ablation techniques are included to explain the advantages of using FOSs during these procedures. PMID:27455273

  12. National Ignition Facility final optics assembly thermal effects of maintenance operations

    SciTech Connect

    Parietti, L.; Martin, R.A.

    1998-04-01

    The National Ignition Facility (NIF), the world`s most powerful laser system, is being built at Lawrence Livermore National Laboratory (LLNL) to study inertial fusion and high-energy-density science. This billion-dollar facility consists of 192 beams focusing 1.8 MJ on a fusion target. The Final Optics Assembly (FOA), the last mechanical apparatus before the target chamber, converts the light from an incoming frequency of 1 {omega} to ia target-ready 3 {omega}, and focuses the laser beam. The performance of the frequency conversion crystals is very sensitive to temperature changes; crystal temperature must be maintained within a 0.1 C of a nominal temperature prior to a laser shot. Maximizing system availability requires minimizing thermal recovery times after thermal disturbances occurring in both normal and maintenance operations. To guide the design, it is important to have estimates of those recovery times. This report presents Computational Fluid Dynamics (CFD) design calculations to evaluate thermal effects of maintenance operations.

  13. Optical Coating Performance and Thermal Structure Design for Heat Reflectors of JWST Electronic Control Unit

    NASA Technical Reports Server (NTRS)

    Quijada, Manuel A.; Threat, Felix; Garrison, Matt; Perrygo, Chuck; Bousquet, Robert; Rashford, Robert

    2008-01-01

    The James Webb Space Telescope (JWST) consists of an infrared-optimized Optical Telescope Element (OTE) that is cooled down to 40 degrees Kelvin. A second adjacent component to the OTE is the Integrated Science Instrument Module, or ISIM. This module includes the electronic compartment, which provides the mounting surfaces and ambient thermally controlled environment for the instrument control electronics. Dissipating the 200 watts generated from the ISIM structure away from the OTE is of paramount importance so that the spacecraft's own heat does not interfere with the infrared light detected from distant cosmic sources. This technical challenge is overcome by a thermal subsystem unit that provides passive cooling to the ISIM control electronics. The proposed design of this thermal radiator consists of a lightweight structure made out of composite materials and low-emittance metal coatings. In this paper, we will present characterizations of the coating emittance, bidirectional reflectance, and mechanical structure design that will affect the performance of this passive cooling system.

  14. SU-E-J-161: Inverse Problems for Optical Parameters in Laser Induced Thermal Therapy

    SciTech Connect

    Fahrenholtz, SJ; Stafford, RJ; Fuentes, DT

    2014-06-01

    Purpose: Magnetic resonance-guided laser-induced thermal therapy (MRgLITT) is investigated as a neurosurgical intervention for oncological applications throughout the body by active post market studies. Real-time MR temperature imaging is used to monitor ablative thermal delivery in the clinic. Additionally, brain MRgLITT could improve through effective planning for laser fiber's placement. Mathematical bioheat models have been extensively investigated but require reliable patient specific physical parameter data, e.g. optical parameters. This abstract applies an inverse problem algorithm to characterize optical parameter data obtained from previous MRgLITT interventions. Methods: The implemented inverse problem has three primary components: a parameter-space search algorithm, a physics model, and training data. First, the parameter-space search algorithm uses a gradient-based quasi-Newton method to optimize the effective optical attenuation coefficient, μ-eff. A parameter reduction reduces the amount of optical parameter-space the algorithm must search. Second, the physics model is a simplified bioheat model for homogeneous tissue where closed-form Green's functions represent the exact solution. Third, the training data was temperature imaging data from 23 MRgLITT oncological brain ablations (980 nm wavelength) from seven different patients. Results: To three significant figures, the descriptive statistics for μ-eff were 1470 m{sup −1} mean, 1360 m{sup −1} median, 369 m{sup −1} standard deviation, 933 m{sup −1} minimum and 2260 m{sup −1} maximum. The standard deviation normalized by the mean was 25.0%. The inverse problem took <30 minutes to optimize all 23 datasets. Conclusion: As expected, the inferred average is biased by underlying physics model. However, the standard deviation normalized by the mean is smaller than literature values and indicates an increased precision in the characterization of the optical parameters needed to plan MRg

  15. Thermally insensitive determination of the linewidth broadening factor in nanostructured semiconductor lasers using optical injection locking

    PubMed Central

    Wang, Cheng; Schires, Kevin; Osiński, Marek; Poole, Philip J.; Grillot, Frédéric

    2016-01-01

    In semiconductor lasers, current injection not only provides the optical gain, but also induces variation of the refractive index, as governed by the Kramers-Krönig relation. The linear coupling between the changes of the effective refractive index and the modal gain is described by the linewidth broadening factor, which is responsible for many static and dynamic features of semiconductor lasers. Intensive efforts have been made to characterize this factor in the past three decades. In this paper, we propose a simple, flexible technique for measuring the linewidth broadening factor of semiconductor lasers. It relies on the stable optical injection locking of semiconductor lasers, and the linewidth broadening factor is extracted from the residual side-modes, which are supported by the amplified spontaneous emission. This new technique has great advantages of insensitivity to thermal effects, the bias current, and the choice of injection-locked mode. In addition, it does not require the explicit knowledge of optical injection conditions, including the injection strength and the frequency detuning. The standard deviation of the measurements is less than 15%. PMID:27302301

  16. Thermally insensitive determination of the linewidth broadening factor in nanostructured semiconductor lasers using optical injection locking.

    PubMed

    Wang, Cheng; Schires, Kevin; Osiński, Marek; Poole, Philip J; Grillot, Frédéric

    2016-06-15

    In semiconductor lasers, current injection not only provides the optical gain, but also induces variation of the refractive index, as governed by the Kramers-Krönig relation. The linear coupling between the changes of the effective refractive index and the modal gain is described by the linewidth broadening factor, which is responsible for many static and dynamic features of semiconductor lasers. Intensive efforts have been made to characterize this factor in the past three decades. In this paper, we propose a simple, flexible technique for measuring the linewidth broadening factor of semiconductor lasers. It relies on the stable optical injection locking of semiconductor lasers, and the linewidth broadening factor is extracted from the residual side-modes, which are supported by the amplified spontaneous emission. This new technique has great advantages of insensitivity to thermal effects, the bias current, and the choice of injection-locked mode. In addition, it does not require the explicit knowledge of optical injection conditions, including the injection strength and the frequency detuning. The standard deviation of the measurements is less than 15%.

  17. Structural, optical, thermal and mechanical properties of Urea tartaric acid single crystals

    NASA Astrophysics Data System (ADS)

    Vinothkumar, P.; Rajeswari, K.; Kumar, R. Mohan; Bhaskaran, A.

    2015-06-01

    Urea tartaric acid (UT) an organic nonlinear optical (NLO) material was synthesized from aqueous solution and the crystals were grown by the slow evaporation technique. The single crystal X-ray diffraction (XRD) analysis revealed that the UT crystal belongs to the orthorhombic system. The functional groups of UT have been identified by the Fourier transform infrared spectral studies. The optical transparent window in the visible and near the IR regions was investigated. The transmittance of UT has been used to calculate the refractive index (n) as a function of the wavelength. The nonlinear optical property of the grown crystal has been confirmed by the Kurtz powder second harmonic generation test. The birefringence of the crystal was determined using a tungsten halogen lamp source. The laser induced surface damage threshold for the grown crystal was measured using the Nd:YAG laser. The anisotropic in mechanical property of the grown crystals was studied using Vicker's microhardness tester at different planes. The etch pit density of UT crystals was investigated. The thermal behavior of UT was investigated using the TG-DTA and DSC studies.

  18. Optical and thermal properties of azo derivatives of salicylic acid thin films

    NASA Astrophysics Data System (ADS)

    Ghoneim, M. M.; El-Ghamaz, N. A.; El-Sonbati, A. Z.; Diab, M. A.; El-Bindary, A. A.; Serag, L. S.

    2015-02-01

    N-acryloyl-4-aminosalicylic acid (4-AMSA), monomer (HL) and 5-(4‧-alkyl phenylazo)-N-acryloyl-4-aminosalicylic acid (HLn) are synthesized and characterized with various physico-chemical techniques. Thin films of 5-(4‧-alkyl phenylazo)-N-acryloyl-4-aminosalicylic acid (HLn) are prepared by spin coating technique. The X-ray diffraction (XRD) patterns of 4-aminosalicylic acid (4-ASA) and its derivatives are investigated in powder and thin film forms. Thermal properties of the compounds are investigated by thermogravemetric analysis (TGA). The optical energy gap and the type of optical transition are investigated in the wavelength range (200-2500 nm) for 4-ASA, HL and HLn. The values of fundamental energy gap (Eg) are in the range 3.60-3.69 eV for all compounds and the type of optical transition is found to be indirect allowed. The onset energy gap Eg∗ appeared only for azodye compounds is found to be in the range 0.95-1.55 eV depending on the substituent function groups. The refractive index, n, shows a normal dispersion in the wavelength range 650-2500 nm, while shows anomalous dispersion in the wavelength rang 200-650 nm. The dispersion parameters ε∞, εL, Ed, Eo and N /m∗ are calculated. The photoluminescence phenomena (PL) appear for thin films of 4-ASA and its derivatives show three main emission transitions.

  19. Thermally Engineered Blue Photoluminescence of Porous Anodic Alumina Membranes for Promising Optical Biosensors

    NASA Astrophysics Data System (ADS)

    Bu, Sang Don; Cho, Sam Yeon; Choi, Yong Chan; Kim, Jin Woo; Han, Jin Kyu; Kwak, Jin Ho; Yang, Sun A.

    Optical biosensors based on porous anodic alumina membranes (PAAMs) have shown to be an effective device because of their unique optical properties and biocompatibility. Among various optical properties, photoluminescence (PL) emission derived from PAAMs is one of the most suitable characteristics. However, the origin of PL from PAA is unclear and still in doubt. Therefore, it is essential for further potential practical applications to understand the origin of PL and PL variations. Here, we investigate the effects of post-annealing temperatures on the blue PL of amorphous PAAMs fabricated in oxalic acid. We find that the blue PL emission is strongly dependent on the thermal properties. A strong blue PL at a peak of ~460 nm is observed from the initial PAAM (not annealed PAAM) and this PL band can be divided into two Gaussian components at 458 ~ +/- ~ 4 nm (P1 band) and 517 ~ +/- 7nm (P2 band). As the temperature increases to 600 ° C , the intensities of two PL bands gradually increase. During temperature increases from 600 to 700 ° C , the P2 band increases but the P1 band decreases. The analyses of electron paramagnetic resonance, Fourier transform infrared spectroscopy, and ultraviolet-visible absorption spectroscopy show that the P1 and P2 bands originate from the unstable carboxylates and the stable carboxylates, respectively.

  20. Optical and thermal properties of azo derivatives of salicylic acid thin films.

    PubMed

    Ghoneim, M M; El-Ghamaz, N A; El-Sonbati, A Z; Diab, M A; El-Bindary, A A; Serag, L S

    2015-02-25

    N-acryloyl-4-aminosalicylic acid (4-AMSA), monomer (HL) and 5-(4'-alkyl phenylazo)-N-acryloyl-4-aminosalicylic acid (HLn) are synthesized and characterized with various physico-chemical techniques. Thin films of 5-(4'-alkyl phenylazo)-N-acryloyl-4-aminosalicylic acid (HLn) are prepared by spin coating technique. The X-ray diffraction (XRD) patterns of 4-aminosalicylic acid (4-ASA) and its derivatives are investigated in powder and thin film forms. Thermal properties of the compounds are investigated by thermogravemetric analysis (TGA). The optical energy gap and the type of optical transition are investigated in the wavelength range (200-2500 nm) for 4-ASA, HL and HLn. The values of fundamental energy gap (Eg) are in the range 3.60-3.69 eV for all compounds and the type of optical transition is found to be indirect allowed. The onset energy gap Eg(∗) appeared only for azodye compounds is found to be in the range 0.95-1.55 eV depending on the substituent function groups. The refractive index, n, shows a normal dispersion in the wavelength range 650-2500 nm, while shows anomalous dispersion in the wavelength rang 200-650 nm. The dispersion parameters ε∞, εL, Ed, Eo and N/m(∗) are calculated. The photoluminescence phenomena (PL) appear for thin films of 4-ASA and its derivatives show three main emission transitions.

  1. Measurement of the anisotropic thermal conductivity of molybdenum disulfide by the time-resolved magneto-optic Kerr effect

    SciTech Connect

    Liu, Jun Choi, Gyung-Min; Cahill, David G.

    2014-12-21

    We use pump-probe metrology based on the magneto-optic Kerr effect to measure the anisotropic thermal conductivity of (001)-oriented MoS{sub 2} crystals. A ≈20 nm thick CoPt multilayer with perpendicular magnetization serves as the heater and thermometer in the experiment. The low thermal conductivity and small thickness of the CoPt transducer improve the sensitivity of the measurement to lateral heat flow in the MoS{sub 2} crystal. The thermal conductivity of MoS{sub 2} is highly anisotropic with basal-plane thermal conductivity varying between 85–110 W m{sup -1} K{sup -1} as a function of laser spot size. The basal-plane thermal conductivity is a factor of ≈50 larger than the c-axis thermal conductivity, 2.0±0.3 W m{sup -1} K{sup -1}.

  2. Optical sensor for precision in-situ spindle health monitoring

    NASA Astrophysics Data System (ADS)

    Zhao, Rui

    An optical sensor which can record in-situ measurements of the dynamic runout of a precision miniature spindle system in a simple and low-cost manner is proposed in this dissertation. Spindle error measurement technology utilizes a cylindrical or spherical target artifact attached to the miniature spindle with non-contact sensors, typically capacitive sensors which are calibrated with a flat target surface not a curved target surface. Due to the different behavior of an electric field between a flat plate and a curved surface and an electric field between two flat plates, capacitive sensors is not suitable for measuring target surfaces smaller than its effective sensing area. The proposed sensor utilizes curved-edge diffraction (CED), which uses the effect of cylindrical surface curvature on the diffraction phenomenon in the transition regions adjacent to shadow, transmission, and reflection boundaries. The laser diodes light incident on the cylindrical surface of precision spindle and photodetectors collect the total field produced by the diffraction around the target surface. Laser diode in the different two direction are incident to the spindle shaft edges along the X and Y axes, four photodetectors collect the total fields produced by interference of multiple waves due to CED around the spindle shaft edges. The X and Y displacement can be obtained from the total fields using two differential amplifier configurations, respectively. Precision miniature spindle (shaft φ5.0mm) runout was measured, and the proposed sensor can perform curve at the different speed of rotation from 1500rpm to 8000rpm in the X and Y axes, respectively. On the other hand, CED also show changes for different running time and temperature of spindle. These results indicate that the proposed sensor promises to be effective for in-situ monitoring of the miniature spindle's health with high resolution, wide bandwidth, and low-cost.

  3. Laser treatment of female stress urinary incontinence: optical, thermal, and tissue damage simulations

    NASA Astrophysics Data System (ADS)

    Hardy, Luke A.; Chang, Chun-Hung; Myers, Erinn M.; Kennelly, Michael J.; Fried, Nathaniel M.

    2016-02-01

    Treatment of female stress urinary incontinence (SUI) by laser thermal remodeling of subsurface tissues is studied. Light transport, heat transfer, and thermal damage simulations were performed for transvaginal and transurethral methods. Monte Carlo (MC) provided absorbed photon distributions in tissue layers (vaginal wall, endopelvic fascia, urethral wall). Optical properties (n,μa,μs,g) were assigned to each tissue at λ=1064 nm. A 5-mm-diameter laser beam and power of 5 W for 15 s was used, based on previous experiments. MC output was converted into absorbed energy, serving as input for ANSYS finite element heat transfer simulations of tissue temperatures over time. Convective heat transfer was simulated with contact cooling probe set at 0 °C. Thermal properties (κ,c,ρ) were assigned to each tissue layer. MATLAB code was used for Arrhenius integral thermal damage calculations. A temperature matrix was constructed from ANSYS output, and finite sum was incorporated to approximate Arrhenius integral calculations. Tissue damage properties (Ea,A) were used to compute Arrhenius sums. For the transvaginal approach, 37% of energy was absorbed in endopelvic fascia layer with 0.8% deposited beyond it. Peak temperature was 71°C, treatment zone was 0.8-mm-diameter, and almost all of 2.7-mm-thick vaginal wall was preserved. For transurethral approach, 18% energy was absorbed in endopelvic fascia with 0.3% deposited beyond it. Peak temperature was 80°C, treatment zone was 2.0-mm-diameter, and only 0.6 mm of 2.4-mm-thick urethral wall was preserved. A transvaginal approach is more feasible than transurethral approach for laser treatment of SUI.

  4. Estimation of the end-of-life optical properties of Z-93 thermal control coating for the Space Station Freedom

    NASA Technical Reports Server (NTRS)

    Hasegawa, Mark M.; Babel, Hank W.

    1992-01-01

    This paper describes an approach to estimating the 30-year end-of-life optical properties of Z-93 white, thermal control coating on the Space Station Freedom. Estimations of the 30-year end-of-life properties of thermal control coatings are necessary for sizing the thermal radiators. The available flight and ground data and computer generated contamination models are used to predict the effects of ground handling, exposure to UV radiation, and on-orbit contamination on the optical properties of Z-93. The solar absorptance for portions of the thermal control system radiator surfaces is predicted to change from 0.15 to 0.36 after 30 years of low earth orbit environmental exposure. The infrared emittance is predicted to change from 0.92 to 0.90.

  5. Thermal and optical properties of rare earth metal β-Diketone Bipy complexes as optical recording materials

    NASA Astrophysics Data System (ADS)

    Ma, Dongzhe; Wu, Yiqun; Jiang, Xin; Chen, Zhimin; Zuo, Xia

    2005-09-01

    Three kinds of novel rare earth metal β-diketone bipy complexes have been synthesized. Smooth films of the complexes on K9 glass substrates and single-crystal silicon substrates were prepared by spin-coating method. The absorption spectra of these new materials were measured in solution and in film. The optical constants (complex refractive index N=n+ik ) of the films on single-crystal silicon substrates at 405nm were determined with scanning ellipsometer. The thermo-gravimetric analysis (TGA) of the materials was also carried out. It is found that the absorption spectra of these films have comparatively broad band in the wavelength region 300-400nm, the peek is at ~345nm and the absorption edge is steep in the wavelength region 350-400nm, which indicates that the absorption of the films is well matched with the wavelength of GaN semiconductor laser diode (405nm). The refractive index (n) of the films is above 1.9 and the extinction coefficient (k) of is 0.1-0.3 at 405nm. The reflection peeks are located near 405nm. And also the new materials possess excellent thermal stability (their decomposition temperatures are higher than 300°C). The results imply that these novel materials are promising candidates for the recording media of blue discs.

  6. Synthesis, growth, structural, optical, thermal and mechanical properties of an organic Urea maleic acid single crystals for nonlinear optical applications

    NASA Astrophysics Data System (ADS)

    Vinothkumar, P.; Kumar, R. Mohan; Jayavel, R.; Bhaskaran, A.

    2016-07-01

    A potential organic urea maleic acid (UMA) was synthesized and single crystals were grown at room temperature by slow evaporation and seed rotation methods. The grown crystal has been subjected to single crystal XRD analysis and found to have been crystallized in a noncentrosymmetric monoclinic crystal system with Cc as space group. The High resolution X-ray diffraction analysis revealed that the specimen is free from structural grain boundaries. The transparency of the grown crystal was confirmed by optical absorption and transmittance spectra with lower cut-off wavelength of 285 nm. The microhardness test was carried out on different planes to study the load dependent hardness values. The dislocation density of the UMA crystal was estimated from the etching studies. The dielectric permittivity and dielectric loss of the grown crystal was carried out as a function of frequency for different temperatures along three crystallographic axes. Thermal properties of UMA crystals were studied by TG-DTA analysis and it is stable upto 112 °C. The laser induced surface damage threshold of the grown crystal was measured using Nd: YAG laser. The birefringence of the crystal measured in the visible region was found to vary with the wavelength. The particle size dependent SHG of the sample was measured with different input energies by Kurtz's powder method using Nd:YAG laser.

  7. Structural, thermal, linear and nonlinear optical studies of an organic optical limiter based on reverse saturable absorption

    NASA Astrophysics Data System (ADS)

    Menezes, Anthoni Praveen; Raghavendra, S.; Jayarama, A.; Sarveshwara, H. P.; Dharmaprakash, S. M.

    2016-09-01

    A new derivative of chalcone, 3-(4-bromophenyl)-1-(pyridin-4-yl) prop-2-en-1-one (4BP4AP), crystallizing in centrosymmetric structure has been synthesized using the Claisen-Schmidt condensation reaction method. The FTIR and FT-Raman spectral studies were carried out on 4BP4AP for structural conformation. The single crystals were grown using slow evaporation solution growth technique. The single crystal XRD of the crystal shows that the crystal system of 4BP4AP is triclinic with space group P-1. Scanning electron microscope images enunciate the surface smoothness and the two dimensional growth mechanisms in the crystal. The crystal is transparent in the entire visible region as indicated by the UV-VIS-NIR spectrum. The thermal stability and phase transition of the compound was studied by thermogravimetric and differential scanning calorimetric analysis and found to be stable up to 200 °C. By performing the open aperture z-scan experiment, nonlinear absorption and optical limiting behavior of the crystal were studied. The crystal can be used for optoelectronic application due to its excellent photo-physical properties.

  8. Multilayer cloud detection and retrieval of cloud physical and optical properties from thermal infrared measurements

    NASA Astrophysics Data System (ADS)

    Iwabuchi, H.; Tokoro, Y.; Saito, M.; Putri, N. S.; Katagiri, S.; Sekiguchi, M.

    2015-12-01

    Recent studies using active remote sensing have revealed significant occurrence of multi-layer cloud. Detection of multi-layer cloud is important in passive remote sensing for quality assessment of cloud property retrieval and identification of uncertain retrievals. An algorithm using several thermal infrared (TIR) bands at 6-13.5 micron wavelengths to detect multilayer cloud and retrieve cloud physical and optical properties including cloud thermodynamic phase is developed. This significantly extends applicability of passive remote sensing and improves accuracy of cloud property retrieval. The method uses the split window bands as well as the carbon dioxide and water vapor absorption bands. The forward model uses the two-stream approximation to solve radiative transfer with gaseous absorption treated by the correlated-k distribution method. Brightness temperature errors are evaluated by model-to-model and model-to-measurement comparisons. Top pressure of lower cloud in multi-layer cloud column can be retrieved if the upper cloud optical thickness is less than 6. The optimal estimation method is used to simultaneously infer several cloud properties including water path, effective particle radius and cloud-top pressure. The method is applied to the Moderate Resolution Imaging Spectroradiometer (MODIS) using 10 TIR bands and compared to MODIS operational product and active remote sensing measurements, showing promising results. The TIR method well detects optically thin clouds and retrieve their properties with relatively high accuracy. Particularly, cloud-top of optically thin cloud is estimated well. Multi-layer cloud detection works usually, while the TIR measurements miss very thin cloud that appears near the tropopause. The algorithm will be applied to frequent observation data from a new Japanese geostationary satellite, Himawari-8.

  9. Mechanism to synthesize a `moving optical mark' at solid-ambient interface for the estimation of thermal diffusivity of solid

    NASA Astrophysics Data System (ADS)

    Balachandar, Settu; Shivaprakash, N. C.; Kameswara Rao, L.

    2016-01-01

    A novel mechanism is proposed, involving a novel interaction between solid-sample supporting unsteady heat flow with its ambient-humidity; invokes phase transformation of water-vapour molecule and synthesize a `moving optical-mark' at sample-ambient-interface. Under tailored condition, optical-mark exhibits a characteristic macro-scale translatory motion governed by thermal diffusivity of solid. For various step-temperature inputs via cooling, position-dependent velocities of moving optical-mark are measured at a fixed distance. A new approach is proposed. `Product of velocity of optical-mark and distance' versus `non-dimensional velocity' is plotted. The slope reveals thermal diffusivity of solid at ambient-temperature; preliminary results obtained for Quartz-glass is closely matching with literature.

  10. Experimental and numerical analysis of thermal forming processes for precision optics

    NASA Astrophysics Data System (ADS)

    Su, Lijuan

    Glass has been fabricated into different optical elements including aspherical lenses and freeform mirrors. However, aspherical lenses are very difficult to manufacture using traditional methods since they were specially developed for spherical lenses. On the other hand, large size mirrors are also difficult to make especially for high precision applications or if designed with complicated shapes. Recently developed two closely related thermal forming processes, i.e. compression molding and thermal slumping, have emerged as two promising methods for manufacturing aspherical lenses and freeform mirrors efficiently. Compression molding has already been used in industry to fabricate consumer products such as the lenses for digital cameras, while thermal slumping has been aggressively tested to create x-ray mirrors for space-based telescopes as well as solar panels. Although both process showed great potentials, there are a quite few technical challenges that prevent them from being readily implemented in industry for high volume production. This dissertation research seeks a fundamental understanding of the thermal forming processes for both precision glass lenses and freeform mirrors by using a combined experimental, analytical and numerical modeling approach. First, a finite element method (FEM) based methodology was presented to predict the refractive index change of glass material occurred during cooling. The FEM prediction was then validated using experimental results. Second, experiments were also conducted on glass samples with different cooling rates to study the refractive index variation caused by non-uniform cooling. A Shack-Hartmann Sensor (SHS) test setup was built to measure the index variations of thermally treated glass samples. Again, an FEM simulation model was developed to predict the refractive index variation. The prediction was compared with the experimental result, and the effects of different parameters were evaluated. In the last phase of this

  11. Effects of rapid thermal annealing on the optical properties of strain-free quantum ring solar cells.

    PubMed

    Wu, Jiang; Wang, Zhiming M; Dorogan, Vitaliy G; Li, Shibin; Lee, Jihoon; Mazur, Yuriy I; Kim, Eun Soo; Salamo, Gregory J

    2013-01-02

    Strain-free GaAs/Al0.33Ga0.67As quantum rings are fabricated by droplet epitaxy. Both photoresponse and photoluminescence spectra confirm optical transitions in quantum rings, suggesting that droplet epitaxial nanomaterials are applicable to intermediate band solar cells. The effects of post-growth annealing on the quantum ring solar cells are investigated, and the optical properties of the solar cells with and without thermal treatment are characterized by photoluminescence technique. Rapid thermal annealing treatment has resulted in the significant improvement of material quality, which can be served as a standard process for quantum structure solar cells grown by droplet epitaxy.

  12. Next generation optical instruments and space experiment based on the LDEF thermal control surfaces experiment (S0069)

    NASA Technical Reports Server (NTRS)

    Wilkes, Donald R.

    1993-01-01

    The Thermal Control Surfaces Experiment (TCSE) was a successful experiment to study the effects of the space environment on thermal control surfaces using in-space optical properties measurements combined with post-flight analyses. The TCSE reflectometer performed well on the LDEF mission demonstrating that a portable compact integrating sphere spectroreflectometer can be built that is rugged and space rated. Since the retrieval of the TCSE package from space, several other instruments have evolved from its pioneering technologies. These are the Optical Properties Monitor (OPM), the Laboratory Portable SpectroReflectometer (LPSR), and the Space Portable SpectroReflectometer (SPSR). These instruments and experiment packages are described.

  13. Magneto-optical properties of cerium substituted yttrium iron garnet films with reduced thermal budget for monolithic photonic integrated circuits.

    PubMed

    Goto, Taichi; Onbaşlı, Mehmet C; Ross, C A

    2012-12-17

    Thin films of polycrystalline cerium substituted yttrium iron garnet (CeYIG) were grown on an yttrium iron garnet (YIG) seed layer on Si and Si-on-insulator substrates by pulsed laser deposition, and their optical and magneto-optical properties in the near-IR region were measured. A YIG seed layer of ~30 nm thick processed by rapid thermal anneal at 800°C provided a virtual substrate to promote crystallization of the CeYIG. The effect of the thermal budget of the YIG/CeYIG growth process on the film structure, magnetic and magnetooptical properties was determined.

  14. Characterization of nodular and thermal defects in hafnia/silica multilayer coatings using optical, photothermal, and atomic force microscopy

    SciTech Connect

    Stolz, C.J.; Yoshiyama, J.M.; Salleo, A.; Wu, Z.L.; Green, J.; Krupka, R.

    1997-12-24

    Multilayer coatings manufactured from metallic hafnium and silica sources by reactive electron beam deposition, are being developed for high fluence optics in a fusion laser with a wavelength of 1053 nm and a 3 ns pulse length. Damage threshold studies have revealed a correlation between laser damage and nodular defects, but interestingly laser damage is also present in nodule-free regions. Photothermal studies of optical coatings reveal the existence of defects with strong optical absorption in nodule-free regions of the coating. A variety of microscopic techniques were employed to characterize the effects for a better understanding of the thermal properties of nodular defects and role of thermal defects in laser damage. Photothermal microscopy, utilizing the surface thermal lensing technique, was used to map the thermal characteristics of 3 mm x 3 mm areas of the coatings. High resolution subaperture scans, with a 1 pm step size and a 3 um pump beam diameter, W= conducted on the defects to characterize their photothermal properties. Optical and atomic force microscopy was used to visually identify defects and characterize their topography. The defects were then irradiated to determine the role of nodular and thermal defects in limiting the damage threshold of the multilayer.

  15. Combined fiber optical thermal sensor for noninvasive monitoring of blood and human tissue through diffuse scattering and metabolic parameters

    NASA Astrophysics Data System (ADS)

    Saetchnikov, Vladimir A.; Tcherniavskaia, Elina A.; Schweiger, Gustav

    2007-07-01

    A method of noninvasive monitoring of human tissue and blood components based on optical diffuse scattering spectroscopy combined with metabolic heat measurements has been developed. Developed compact fiber optical and thermal sensor measures thermal generation, heat balance, blood flow rate, hemoglobin and it's derivative concentrations and environment conditions. It contains thermal and optical detectors, halogen lamp and LEDs, multi-leg fiber optical bundle to measure diffuse light scattering inside and through the patient body including vascular system, which contributes to the control of the body temperature. Measurements of surface cutaneous tissue thermal radiation, ambient room temperature and background radiation temperature are used to measure conduction, convection, and radiation of heat from the human body. Blood flow rate in the body is estimated from the change in temperature for the contact and adjacent thermal detectors. Multi wavelength spectroscopy provides a reflectance spectra which are converted to absorbance values. The calibration and measurement processes are performed independently. Methods of multivariate statistical analysis involving the variables from sensor signals, polynomials from various variables, regression analysis of individual patients, and cluster analysis of patients group were applied to convert various signals from the sensor pickup into physicochemical variables. Obtained data show that the method provides a foundation for noninvasive measuring several biochemical parameters of blood. Further developments of the technology which is under progress now are the following: clinical studies to further characterize the performance of this technology and development of compact and low cost sensor device for home diagnostics.

  16. Effect of thermally induced birefringence on performance of KD*P electro-optics crystal with rectangular shape.

    PubMed

    Yin, Xingliang; Jiang, Menghua; Sun, Zhe; Hui, Yongling; Lei, Hong; Li, Qiang

    2017-04-01

    In this paper, we present what we believe is the first demonstration of a new rectangular KD*P crystal as an electro-optic switch and calculations of the stress-induced birefringence and depolarization loss in the crystal. We simulated and experimentally demonstrate the thermal depolarization loss of crystal in both cylindrical and rectangular shape. The results show that by using a rectangular KD*P crystal, the effects of the thermally induced birefringence and depolarization can be lessened.

  17. Method And Apparatus For Determining Health Of Thermal Barrier Coatings

    DOEpatents

    Srivastava, Alok Mani; Setlur, Anant Achyut; Comanzo, Holly Ann; Devitt, John William; Ruud, James Anthony; Brewer, Luke Nathaniel

    2005-09-13

    A method for determining past-service conditions and/or remaining useful life of a component of a combustion engine and/or a thermal barrier coating ("TBC") of the component comprises providing a photoluminescent ("PL") material in the TBC, directing an exciting radiation at the TBC, measuring the intensity of a characteristic peak in the emission spectrum of the PL material, and correlating the intensity of the characteristic peak or another quantity derived therefrom to an amount of a new phase that has been formed as a result of the exposure of the component to extreme temperatures. An apparatus for carrying out the method comprises a radiation source that provides the exciting radiation to the TBC, a radiation detector for detecting radiation emitted by the PL material, and means for relating a characteristic of the emission spectrum of the PL material to the amount of the new phase in the TBC, thereby inferring the past-service conditions or the remaining useful life of the component.

  18. Ground surface temperature reconstructions: Using in situ estimates for thermal conductivity acquired with a fiber-optic distributed thermal perturbation sensor

    SciTech Connect

    Freifeld, B.M.; Finsterle, S.; Onstott, T.C.; Toole, P.; Pratt, L.M.

    2008-10-10

    We have developed a borehole methodology to estimate formation thermal conductivity in situ with a spatial resolution of one meter. In parallel with a fiber-optic distributed temperature sensor (DTS), a resistance heater is deployed to create a controlled thermal perturbation. The transient thermal data is inverted to estimate the formation's thermal conductivity. We refer to this instrumentation as a Distributed Thermal Perturbation Sensor (DTPS), given the distributed nature of the DTS measurement technology. The DTPS was deployed in permafrost at the High Lake Project Site (67 degrees 22 minutes N, 110 degrees 50 minutes W), Nunavut, Canada. Based on DTPS data, a thermal conductivity profile was estimated along the length of a wellbore. Using the thermal conductivity profile, the baseline geothermal profile was then inverted to estimate a ground surface temperature history (GSTH) for the High Lake region. The GSTH exhibits a 100-year long warming trend, with a present-day ground surface temperature increase of 3.0 {+-} 0.8 C over the long-term average.

  19. Crystal structure, thermal and optical properties of Benzimidazole benzimidazolium picrate crystal

    NASA Astrophysics Data System (ADS)

    Jagadesan, A.; Peramaiyan, G.; Srinivasan, T.; Kumar, R. Mohan; Arjunan, S.

    2016-02-01

    A new organic framework of benzimidazole with picric acid has been synthesized. A single crystal with a size of 38×10×4 mm3 was grown by a slow evaporation solution growth technique. X-ray diffraction study revealed that the BZP crystal belongs to triclinic system with space group P-1. High resolution X-ray diffraction study shows the absence of grain boundaries without any defects. The thermal stability and specific heat capacity of BZP were investigated by TG/DT and TG/DSC analyses. From the UV-vis-NIR spectral study, optical transmission window and band gap of BZP were found out. The nonlinear refractive index (n2) and third order susceptibility Re(χ(3)) values of BZP crystal are estimated to be 1.73×10-7 cm2/W and 1.26×10-5 esu, respectively using a Z-scan technique.

  20. Laser geodynamic satellite/thermal/optical vibrational analyses and testing. Volume 2: Technical report, book 3

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The overall plan for accomplishing the various tests required to achieve the program objectives and tasks of the LAGEOS thermal/optical/vibration analysis and test program is described. The requirements for each test are identified for the purpose of program review for the design and fabrication of the required test article and test fixtures, for the allocation of test facilities, equipment and expendables, and for the generation of the detail test procedures by which the specified data will be obtained at specified test conditions. The current internal test program schedules, by which the various individual preparatory subtasks are to be accomplished to ensure that the individual test will be conducted within the time period required to meet program objectives are included.

  1. Synthesis, growth, spectral, optical and thermal studies of thiourea family crystal: TTPB

    NASA Astrophysics Data System (ADS)

    Subashini, A.; Rajarajan, K.; Sagadevan, Suresh

    2017-02-01

    In the present work, bulk size single crystal of tetrakis thiourea potassium bromide [K(N2H4CS)4Br]; (TTPB) has been grown from an aqueous solution using slow evaporation solution growth method. The XRD result proved that the compound crystallize in tetragonal crystal system with space group P41. The FT-IR spectrum of TTPB has clearly identified the functional groups of thiourea in the resulting compound. The TG-DTA and DSC studies have been carried out on the grown sample of TTPB and the results are reported. The etching and scanning electron microscope studies were also carried out to understand the growth pattern and surface morphology of TTPB. The spectral, optical and thermal studies of TTPB are compared with the similar thiourea complex crystal [K(N2H4CS)4I]; (TTPI) and reported.

  2. Diagnosis of Thermal Efficiency of Advanced Combined Cycle Power Plants Using Optical Torque Sensors

    NASA Astrophysics Data System (ADS)

    Umezawa, Shuichi

    A new optical torque measurement method was applied to diagnosis of thermal efficiency of advanced combined cycle, i.e. ACC, plants. Since the ACC power plant comprises a steam turbine and a gas turbine and both of them are connected to the same generator, it is difficult to identify which turbine in the plant deteriorates the performance when the plant efficiency is reduced. The sensor measures axial distortion caused by power transmission by use of He-Ne laser beams, small stainless steel reflectors having bar-code patterns, and a technique of signal processing featuring high frequency. The sensor was applied to the ACC plants of TOKYO ELECTRIC POWER COMPANY, TEPCO, following the success in the application to the early combined cycle plants of TEPCO. The sensor performance was inspected over a year. After an improvement related to the signal process, it is considered that the sensor performance has reached a practical use level.

  3. Stimulated orientational and thermal scatterings and self-starting optical phase conjugation with nematic liquid crystals

    PubMed

    Khoo; Liang

    2000-11-01

    A quantitative theory and experimental results on self-starting optical phase conjugation, using stimulated orientational and thermal scattering in nematic liquid crystal films, are presented. The coupled wave-material equations for the laser-induced refractive index changes, grating formation, and coherent wave mixing effects are developed. Analytical solutions are obtained for the case of negligible pump depletion, and numerical solutions for various input and generated signals, taking losses into account, are obtained. Experimentally, we demonstrate the feasibility of realizing these stimulated scattering and phase conjugation processes in thin (200 &mgr;m) nematic liquid crystal with a milliwatt-power cw laser. Theoretical estimates for various gain constants and threshold intensities, and their dependence on various physical parameters, are found to be in good agreement with experimental observations.

  4. Energy losses in thermally cycled optical fibers constrained in small bend radii

    SciTech Connect

    Guild, Eric; Morelli, Gregg

    2012-09-23

    High energy laser pulses were fired into a 365μm diameter fiber optic cable constrained in small radii of curvature bends, resulting in a catastrophic failure. Q-switched laser pulses from a flashlamp pumped, Nd:YAG laser were injected into the cables, and the spatial intensity profile at the exit face of the fiber was observed using an infrared camera. The transmission of the radiation through the tight radii resulted in an asymmetric intensity profile with one half of the fiber core having a higher peak-to-average energy distribution. Prior to testing, the cables were thermally conditioned while constrained in the small radii of curvature bends. Single-bend, double-bend, and U-shaped eometries were tested to characterize various cable routing scenarios.

  5. Squeezing a thermal mechanical oscillator by stabilized parametric effect on the optical spring.

    PubMed

    Pontin, A; Bonaldi, M; Borrielli, A; Cataliotti, F S; Marino, F; Prodi, G A; Serra, E; Marin, F

    2014-01-17

    We report the confinement of an optomechanical micro-oscillator in a squeezed thermal state, obtained by parametric modulation of the optical spring. We propose and implement an experimental scheme based on parametric feedback control of the oscillator, which stabilizes the amplified quadrature while leaving the orthogonal one unaffected. This technique allows us to surpass the -3  dB limit in the noise reduction, associated with parametric resonance, with a best experimental result of -7.4  dB. While the present experiment is in the classical regime, in a moderately cooled system our technique may allow squeezing of a macroscopic mechanical oscillator below the zero-point motion.

  6. The first result of an optical monitoring system for optimization of thermal spray droplets

    NASA Astrophysics Data System (ADS)

    Kawaguchi, Y.; Miyazaki, F.; Yamasaki, M.; Yamagata, Y.; Muraoka, K.

    2015-12-01

    This article describes the first experimental result of a simple but reliable optical monitoring system for optimization of thermal spray droplets. The system, which was used in the present experiment and the authors call as ``a pre-proto instrument'', consisted of a light collecting lens followed by a part for separating the light into two wavelengths, with the light of each wavelength guided into an avalanche photo-diode (APD) to be electronically detected. First, it was calibrated using a special purpose-built calibration system. Then, it was taken to a plasma spray gun for a field test, yielding a satisfactory first result. Based on this positive result, future plans of the project are discussed.

  7. Optical Sensor of Thermal Gas Flow Based on Fiber Bragg Grating

    PubMed Central

    Jiang, Xu; Wang, Keda; Li, Junqing; Zhan, Hui; Song, Zhenan; Che, Guohang; Lyu, Guohui

    2017-01-01

    This paper aims at solving the problem of explosion proof in measurement of thermal gas flow using electronic sensor by presenting a new type of flow sensor by optical fiber heating. A measuring unit based on fiber Bragg grating (FBG) for fluid temperature and a unit for heat dissipation are designed to replace the traditional electronic sensors. The light in C band from the amplified spontaneous emission (ASE) light source is split, with one part used to heat the absorbing coating and the other part used in the signal processing unit. In the heating unit, an absorbing coating is introduced to replace the traditional resistance heating module to minimize the risk of explosion. The measurement results demonstrate a fine consistency between the flow and temperature difference in simulation. The method to enhance the measurement resolution of flow is also discussed. PMID:28212268

  8. A thermal study of cellular motility by optical time-resolved correlation

    NASA Astrophysics Data System (ADS)

    Sierra-Valdez, F. J.; Cisneros-Mejorado, A. J.; Sánchez Herrera, D. P.; Ruiz-Suárez, J. C.

    2012-04-01

    The study of motor properties of cells under appropriate physical-chemical conditions is a significant problem nowadays. The standard techniques presently used do not allow to evaluate neither large samples nor to control their thermodynamic conditions. In this work, we report a cell motility sensor based on an optical technique with a time-resolved correlation, adapted in a system able to study several samples simultaneously. Image correlation analysis is used to follow their temporal behavior. A wide variety of motile cells, such as archaea, bacteria, spermatozoa, and even contractile cells, can be studied using this technique. Here, we tested our technique with the study of sperm motility. In particular, both the sperm motility and its prevalence are studied under a temperature range from 0 to 37 °C. We found that incubation at 10 °C presents the lengthiest prevalence in motility and observed, for the first time, an interesting thermal reversibility behavior.

  9. Thermal tuning the reversible optical band gap of self-assembled polystyrene photonic crystals

    NASA Astrophysics Data System (ADS)

    Vakili Tahami, S. H.; Pourmahdian, S.; Shirkavand Hadavand, B.; Azizi, Z. S.; Tehranchi, M. M.

    2016-11-01

    Nano-sized polymeric colloidal particles could undergo self-organization into three-dimensional structures to produce desired optical properties. In this research, a facile emulsifier-free emulsion polymerization method was employed to synthesize highly mono-disperse sub-micron polystyrene colloids. A high quality photonic crystal (PhC) structure was prepared by colloidal polystyrene. The reversible thermal tuning effect on photonic band gap position as well as the attenuation of the band gap was investigated in detail. The position of PBG can be tuned from 420 nm to 400 nm by varying the temperature of the PhC structure, reversibly. This reversible effect provides a reconfigurable PhC structure which could be used as thermo-responsive shape memory polymers.

  10. Novel multijunction thermal converter in planar technique for AC current, voltage, power and optical radiation measurement

    NASA Astrophysics Data System (ADS)

    Klonz, M.; Weimann, T.

    1990-05-01

    A new planar thin film design of multijunction thermocouples on a silicon chip containing a window with a SiO2-membrane for low heat conductance underneath of the thermocouples is described. It is used as the sensor for the temperature difference in a multijunction thermal converter for ac-dc transfer of electrical quantities like voltage, current and power via Joule heat in a thin film resistor. By coating the heater with an optically absorbing layer it is used as a highly sensitive radiometer transferring absorbed energy to Joule heat in the resistor. The design can easily be optimized for all different frequency applications. It offers the possibility of the mass production of transfer standards at highest level of accuracy.

  11. Wireless Subsurface Microsensors for Health Monitoring of Thermal Protection Systems on Hypersonic Vehicles

    NASA Technical Reports Server (NTRS)

    Milos, Frank S.; Watters, David G.; Pallix, Joan B.; Bahr, Alfred J.; Huestis, David L.; Arnold, Jim (Technical Monitor)

    2001-01-01

    Health diagnostics is an area where major improvements have been identified for potential implementation into the design of new reusable launch vehicles in order to reduce life cycle costs, to increase safety margins, and to improve mission reliability. NASA Ames is leading the effort to develop inspection and health management technologies for thermal protection systems. This paper summarizes a joint project between NASA Ames and SRI International to develop 'SensorTags,' radio frequency identification devices coupled with event-recording sensors, that can be embedded in the thermal protection system to monitor temperature or other quantities of interest. Two prototype SensorTag designs containing thermal fuses to indicate a temperature overlimit are presented and discussed.

  12. Extended two-temperature model for ultrafast thermal response of band gap materials upon impulsive optical excitation

    SciTech Connect

    Shin, Taeho; Teitelbaum, Samuel W.; Wolfson, Johanna; Nelson, Keith A.; Kandyla, Maria

    2015-11-21

    Thermal modeling and numerical simulations have been performed to describe the ultrafast thermal response of band gap materials upon optical excitation. A model was established by extending the conventional two-temperature model that is adequate for metals, but not for semiconductors. It considers the time- and space-dependent density of electrons photoexcited to the conduction band and accordingly allows a more accurate description of the transient thermal equilibration between the hot electrons and lattice. Ultrafast thermal behaviors of bismuth, as a model system, were demonstrated using the extended two-temperature model with a view to elucidating the thermal effects of excitation laser pulse fluence, electron diffusivity, electron-hole recombination kinetics, and electron-phonon interactions, focusing on high-density excitation.

  13. Optical and Thermal Analyses of High-Power Laser Diode Arrays

    NASA Technical Reports Server (NTRS)

    Vasilyev, Aleksey; Allan, Graham R.; Schafer, John; Stephen, Mark A.; Young, Stefano

    2004-01-01

    An important need, especially for space-borne applications, is the early identification and rejection of laser diode arrays which may fail prematurely. The search for reliable failure predictors is ongoing and has led to the development of two techniques, infrared imagery and monitoring the Temporally-resolved and Spectrally-Resolved (TSR) optical output from which temperature of the device can be measured. This is in addition to power monitoring on long term burn stations. A direct measurement of the temperature of the active region is an important parameter as the lifetime of Laser Diode Arrays (LDA) decreases exponentially with increasing temperature. We measure the temperature from time-resolving the spectral emission in an analogous method to Voss et al. In this paper we briefly discuss the measurement setup and present temperature data derived from thermal images and TSR data for two differently designed high-power 808 nanometer LDA packages of similar specification operated in an electrical and thermal environment that mimic the expected operational conditions.

  14. Ultrafast Optical Measurements of Thermal Conductivity and Sound Velocity of Amorphous SiC

    NASA Astrophysics Data System (ADS)

    Hondongwa, Donald; Olasov, Lauren; Daly, Brian; King, Sean; Bielefeld, Jeff

    2011-03-01

    We present ultrafast optical measurements of longitudinal sound velocity and thermal transport in hydrogenated amorphous carbon (a-SiC:H) films. The films were grown on Si wafers by PECVD using combinations of methylsilanes and H2 and He diluent gases. The films were well characterized and found to have densities (1.0 -- 2.5 g cm-3) and dielectric constants (2.8 -- 7.2) that spanned a wide range of values. Prior to their measurement, the a-SiC:H films were coated with 40-70 nm of polycrystalline Al. The pump-probe measurements were performed at room temperature using a modelocked Ti:sapphire laser. Transient reflectivity changes that are associated with very high frequency sound waves (picosecond ultrasonics) and the cooling rate of the SiC sample (Time Domain Thermorerflectance (TDTR)) were measured. We extract values for the thermal conductivity and sound velocity of the SiC films, and analyze the results in terms of rigidity percolation effects within the SiC layers. This work was supported by NSF award DMR-0906753.

  15. Optical, thermal, and electrical monitoring of radio-frequency tissue modification

    NASA Astrophysics Data System (ADS)

    Floume, Timmy; Syms, Richard R. A.; Darzi, Ara W.; Hanna, George B.

    2010-01-01

    Radio-frequency (rf) tissue fusion involves the sealing of tissue between two electrodes delivering rf currents. Applications include small bowel fusion following anastomosis. The mechanism of adhesion is poorly understood, but one hypothesis is that rf modification is correlated to thermal damage and dehydration. A multimodal monitoring system capable of acquiring tissue temperature, electrical impedance, and optical transmittance at 1325-nm wavelength during rf delivery by a modified Ligasure™ fusion tool is presented. Measurements carried out on single layers of ex vivo porcine small bowel tissue heated at ~500-kHz frequency are correlated with observation of water evaporation and histological studies on full seals. It is shown that the induced current generates a rapid quasilinear rise of temperature until the boiling point of water, that changes in tissue transmittance occur before impedance control is possible, and that a decrease in transmission occurs at typical denaturation temperatures. Experimental results are compared with a biophysical model for tissue temperature and a rate equation model for thermal damage.

  16. Effect of Zn doping on structural, optical and thermal properties of CeO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Ramasamy, V.; Vijayalakshmi, G.

    2015-09-01

    The undoped and Zn doped CeO2 nanoparticles were synthesized by chemical precipitation method at room temperature. The undoped and Zn doped CeO2 nanoparticles have been characterized by X-ray powder diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), ultraviolet visible and photoluminescence (PL) spectroscopy, Fourier transform infrared spectroscopy (FTIR) and thermogravimetry and differential thermal analysis (TG-DTA). The cubic fluorite structures of the CeO2 nanoparticles were determined by XRD. The influence of particle size on structural parameters such as lattice parameter (a), inter planar distance (d), dislocation density (δ), microstrain (ε), lattice strain (η) and texture co-efficient (TC) were also determined. The lattice strains were determined by Williamson-Hall plot method. The effect of Zn doping with shifting of the bands were observed by UV-Vis spectroscopy and also their optical band gap were determined. The emission spectra and energy band diagram of the undoped and Zn doped samples were derived from PL spectroscopy. The structural bond vibrations of undoped and Zn doped CeO2 nanoparticles were analyzed by FTIR spectroscopy. The thermal property (weight loss and decomposition) of the sample is observed by TG-DTA curve.

  17. Optical, mechanical and thermal characterization of l-threonine single crystals grown in dimethyl urea solution

    NASA Astrophysics Data System (ADS)

    Shanthi, A.; Krishnan, C.; Selvarajan, P.

    2013-09-01

    An organic material of a noncentrosymmetric l-threonine single crystal was grown in a dimethyl urea solution using the slow evaporation method. The grown crystal was transparent and colorless, with a size of about 20 × 7 × 4 mm3, obtained within a period of 10 days. The grown crystal was subjected to various studies, such as x-ray diffraction (XRD), Fourier transform infrared (FTIR), microhardness, ultraviolet-visible (UV-Vis) transmittance, thermogravimetric analysis and differential thermal analysis (TGA/DTA) and second harmonic generation (SHG). l-threonine crystals grown in a dimethyl urea solution show relative SHG efficiency of 0.92 times that of potassium dihydrogen phosphate. The functional groups of the crystals have been confirmed by FTIR analysis. The mechanical strength of the crystal was estimated by the Vickers hardness test. The lattice parameters of the grown crystal were determined by single crystal XRD and powder XRD studies, and the diffraction peaks were indexed. A UV-Vis spectrum was recorded in the wavelength range of 200-1100 nm to find the suitability of the crystal for nonlinear optical applications. The thermal stability of l-threonine crystal grown in dimethyl urea was checked using the TGA/DTA analysis.

  18. Thermal characterization of Bragg gratings in polarization-maintaining optical fibres: analysis of birefringence and regeneration

    NASA Astrophysics Data System (ADS)

    Abe, I.; de Oliveira, V.; Fiorin, R.; Kalinowski, H. J.

    2017-04-01

    This paper presents an analysis of birefringence and regeneration of fibre Bragg gratings (FBGs) in two types of polarization-maintaining (PM) optical fibres, bow tie and internal elliptical cladding (IEC), with different diameters. The thermal regeneration of FBGs in PM fibres with different degrees of saturation (weakly, slightly, and strongly saturated) is presented and the influence of the gratings’ saturation degree on the birefringence of PM fibres is shown. The birefringence values obtained for IEC fibres with 80 µm of diameter were for a strongly saturated seed grating of 5.3  ×  10‑4 and 6.2  ×  10‑4 refractive index units after the regeneration. The evolution of the fibre birefringence as a function of the temperature is presented and the results show hysteresis and nonlinear dependence of the birefringence on temperature. The thermal stability of regenerated gratings in PM fibres is demonstrated, and a sensitivity coefficient value of 0.0035 dBm min‑1 at 900 °C was obtained. The results obtained show the feasibility of optimization of fibre birefringence; this could allow such fibers to be used as temperature sensors and even improve the birefringence after the grating regeneration.

  19. Growth, optical, thermal and laser damage threshold studies of 4-aminopyridinium 4-nitrophenolate 4-nitrophenol crystal

    NASA Astrophysics Data System (ADS)

    Jagadesan, A.; Peramaiyan, G.; Mohan Kumar, R.; Arjunan, S.

    2015-05-01

    Organic nonlinear optical (NLO) single crystals of 4-aminopyridinium 4-nitrophenolate 4-nitrophenol (4AP4NP) were grown by the slow evaporation solution growth technique. The unit cell parameters and space group of 4AP4NP crystal were found out by single crystal X-ray diffraction analysis. From the UV-vis-NIR spectral studies, the lower cut-off wavelength of the grown crystal was found to be 474 nm. The laser damage threshold study shows that 4AP4NP crystal withstands the laser radiation up to 3.67 GW cm-2. Thermogravimetric and differential thermal analyses revealed that 4AP4ANP is thermally stable up to 175 °C. The specific heat capacity of 4AP4NP was measured to be 3.9135 J g-1 K-1 at 33 °C. Kurtz and Perry powder study reveals that 4AP4NP is a phase-matchable NLO material. The four independent tensor coefficients of dielectric permittivity were found to be ε11=25.09, ε22=25.84, ε33=26.69 and ε13=0.8 from the dielectric measurement.

  20. M1A2 tank commander's independent thermal viewer optics: system engineering perspective

    NASA Astrophysics Data System (ADS)

    Ratcliff, David D.

    1993-08-01

    As successful as the M1A1 Abrams tank was in the Gulf War, a program has been under way for several years to improve and modernize the M1A1 to keep pace with new threats and to take advantage of new technology. This program has resulted in the M1A2 upgrade program which significantly improves the survivability and lethality of the tank. First, the point-to-point wiring and analog signal processing was replaced with digital processing and control with a modern, aircraft-style digital data bus. Additional command and control aspects of the upgrade greatly improved the situational awareness of the M1A2 commander. Finally, an additional thermal imaging system was added for the commander. This system, the M1A2 Commander's Independent Thermal Viewer (CITV) is the topic of the following paper, which details the design from a system engineering perspective, and a companion paper that presents the optical design perspective.

  1. Thermal and optical aspects of glob-top design for phosphor converted white LED light sources

    NASA Astrophysics Data System (ADS)

    Sommer, Christian; Fulmek, Paul; Nicolics, Johann; Schweitzer, Susanne; Nemitz, Wolfgang; Hartmann, Paul; Pachler, Peter; Hoschopf, Hans; Schrank, Franz; Langer, Gregor; Wenzl, Franz P.

    2013-09-01

    For a systematic approach to improve the white light quality of phosphor converted light-emitting diodes (LEDs) for general lighting applications it is imperative to get the individual sources of error for correlated color temperature (CCT) reproducibility and maintenance under control. In this regard, it is of essential importance to understand how geometrical, optical and thermal properties of the color conversion elements (CCE), which typically consist of phosphor particles embedded in a transparent matrix material, affect the constancy of a desired CCT value. In this contribution we use an LED assembly consisting of an LED die mounted on a printed circuit board by chip-on-board technology and a CCE with a glob-top configuration on the top of it as a model system and discuss the impact of the CCE shape and size on CCT constancy with respect to substrate reflectivity and thermal load of the CCEs. From these studies, some general conclusions for improved glob-top design can be drawn.

  2. Optical, thermal and magnetic studies of pure and cobalt chloride doped L-alanine cadmium chloride

    NASA Astrophysics Data System (ADS)

    Benila, B. S.; Bright, K. C.; Delphine, S. Mary; Shabu, R.

    2017-03-01

    Single crystals of L-alanine cadmium chloride (LACC) and cobalt chloride (Co2+) doped LACC have been grown by the slow evaporation solution growth technique. The grown crystals were subjected to various characterizations such as powder XRD, SXRD, FTIR, UV-vis, EDAX, TG/DTA, VSM, Dielectric and Second Harmonic Generation (SHG) measurements. The lattice parameters of the grown crystals were determined by single crystal X-ray analysis. EDAX analysis confirms the presence of Co2+ ion in the host material. The functional group and optical behavior of the crystals were identified from FTIR and UV-vis spectrum analysis. Electrical parameters such as dielectric constant, dielectric loss have been studied. The thermal stability of the compound was found out using TGA/DTA analysis. Second Harmonic Generation of the samples was confirmed by Kurtz-Perry powder technique. Magnetic properties of the crystals studied by VSM were also reported. The encouraging results show that the cobalt chloride doped LACC crystals have greater potential applications in optical devices.

  3. Thermal, optical and structural properties of Dy3+ doped sodium aluminophosphate glasses

    NASA Astrophysics Data System (ADS)

    Kaur, Manpreet; Singh, Anupinder; Thakur, Vanita; Singh, Lakhwant

    2016-03-01

    Trivalent Dysprosium doped sodium aluminophosphate glasses with composition 50P2O5-10Al2O3-(20-x)Na2O-20CaO-xDy2O3 (x varying from 0 to 5 mol%) were prepared by melt quench technique. The density of the prepared samples was measured using Archimedes principle and various physical properties like molar volume, rare earth ion concentration, polaron radius, inter nuclear distance and field strength were calculated using different formulae. The differential scanning calorimetry (DSC) was carried out to study the thermal stability of prepared glasses. The UV Visible absorption spectra of the dysprosium doped glasses were found to be comprised of ten absorption bands which correspond to transitions from ground state 6H15/2 to various excited states. The indirect optical band gap energy of the samples was calculated by Tauc's plot and the optical energy was found to be attenuated with Dy3+ ions. The photoluminescence spectrum revealed that Dy3+ doped aluminophosphate glasses have strong emission bands in the visible region. A blue emission band centred at 486 nm, a bright yellow band centred at 575 nm and a weak red band centred at 668 nm were observed in the emission spectrum due to excitation at 352 nm wavelength. Both FTIR and Raman spectra assert slight structural changes induced in the host glass network with Dy3+ ions.

  4. Comparison of thermal and optical techniques for describing light interaction with vascular grafts, sutures, and thrombus

    NASA Astrophysics Data System (ADS)

    Obremski, Susan M.; LaMuraglia, Glenn M.; Bruggemann, Ulrich H.; Anderson, R. Rox

    1991-06-01

    Pulsed photothermal radiometry (PPTR) and integrating sphere spectrophotometry analyzed by the theory of Kubelka and Munk (KM) were used to determine optical absorption coefficients of prosthetic grafts and sutures and arterial thrombus. The KM method, a purely optical theory and technique, resulted in higher absorption coefficients than those found using PPTR, a primarily thermal technique. This difference was statistically significant (t.025) for the prosthetic materials. With the KM method, other properties such as scattering can also be quantified and the experiment can be performed over a range of wavelengths at one time. The PPTR technique is limited to a single wavelength but it has the advantage that most materials can be tested without any special preparation. In addition, with PPTR the measured quantity is the temporal temperature response of an object to a laser pulse, which is itself of interest. Clinically, the high absorption coefficient of thrombus as compared to that of the graft and sutures (t.025 for the PPTR measurements) suggests that laser thrombectomy may be safe in polyethylene terephthalate (Dacron) grafts.

  5. Structural, optical and magnetic properties of gadolinium sesquioxide nanobars synthesized via thermal decomposition of gadolinium oxalate

    SciTech Connect

    Manigandan, R.; Giribabu, K.; Suresh, R.; Vijayalakshmi, L.; Stephen, A.; Narayanan, V.

    2013-10-15

    Graphical abstract: - Highlights: • The cubic Gd{sub 2}O{sub 3} nanobars are synthesized by decomposition of C{sub 6}H{sub 20}Gd{sub 2}O{sub 22}. • The nanoparticles are rectangular bar shape with high porous surface. • The combination of magnetic and optical properties within a single particle. • The Gd{sub 2}O{sub 3} nanobars have tailorable nanostructure, wide bandgap and are paramagnetic. - Abstract: Gadolinium oxide nanobars were obtained by thermal decomposition of gadolinium oxalate, which was synthesized by the chemical precipitation method along with glycerol. The functional group analysis and formation of gadolinium oxide from gadolinium oxalate were characterized by the Fourier transform infrared spectroscopy and thermo gravimetric analyzer. The crystal structure, average crystallite size, and lattice parameter were analyzed by X-ray diffraction technique. Moreover, Raman shifts, elemental composition and morphology of the gadolinium oxide was widely investigated by the laser Raman microscope, X-ray photoelectron spectroscopy, FE-SEM-EDAX and HR-TEM, respectively. Furthermore, the optical properties like band gap, absorbance measurement of the gadolinium oxide were extensively examined. In addition, the paramagnetic property of gadolinium oxide nanobars was explored by the vibrating sample magnetometer.

  6. Optical, Thermal Studies on Binary and Ternary Hydrogen-Bonded Liquid Crystal Complexes

    NASA Astrophysics Data System (ADS)

    Mahalingam, T.; Venkatachalam, T.; Jayaprakasam, R.; Vijayakumar, V. N.

    2016-06-01

    Hydrogen-bonded ferroelectric liquid crystalline (HBFLC) complexes are synthesized from binary mixtures of l-(+)-tartaric acid with 4-dodecyloxybenzoic acid and cholesteryl acetate. A ternary complex has been obtained from l-(+)-tartaric acid, 4-dodecyloxybenzoic acid, and cholesteryl acetate. Fourier transform infrared spectroscopy (FTIR) studies confirm the formation of an intermolecular hydrogen bond in the binary as well as the ternary complex. The l-(+)-tartaric acid does not show any mesomorphic behavior, but the hydrogen-bonded binary and ternary complexes are exhibiting the nematic phase along with tilted smectic phases. Phase transition properties of HBFLC mixtures have been investigated by means of differential scanning calorimetry (DSC) and polarizing optical microscope (POM). The DSC and POM clearly reveal the existence of nematic and smectic phases in the HBFLC mixtures. The optical tilt angle of binary and ternary mixtures for smectic C* phase and thermal stability factors of the mesogenic phases have been discussed. The noteworthy observation is that there is a significant reduction of phase transition temperatures with enhanced phase width, lowering melting temperature, and clearing point in the HBFLC ternary complex.

  7. Optical characteristics of wet-thermally oxidized bulk and nanoporous GaN

    NASA Astrophysics Data System (ADS)

    Kim, Sinjae; Kadam, Mahadev; Kang, Jin-Ho; Ryu, Sang-Wan

    2016-09-01

    Gallium nitride (GaN) films deposited on sapphire substrates by metal organic chemical vapor deposition were successfully transformed into bulk and nanoporous gallium oxide (Ga2O3) using a wet thermal oxidation technique. Oxidation depth measurements confirmed that the oxide growth appeared to be faster in the case of nanoporous GaN than that of bulk GaN. Spectroscopic ellipsometry was used to evaluate and compare the optical properties of nanoporous and bulk Ga2O3 films, such as refractive index and extinction coefficient, which revealed improved optical properties for nanoporous Ga2O3 compared to the bulk. The simulations conducted on the ellipsometric spectra for bulk and nanoporous Ga2O3 using the Forouhi-Bloomer model and the Bruggeman effective medium approximation revealed the best fit with a low mean square error value. In the case of nanoporous Ga2O3, zero absorption was observed in the wavelength range of 300 nm to 840 nm, supporting the use of this material as a transparent coating in optoelectronic devices.

  8. A novel single fiber optical tweezers based on light-induced thermal effect

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Liu, Zhihai; Liang, Peibo; Zhang, Yaxun; Zhao, Enming; Yang, Jun; Yuan, Libo

    2015-07-01

    We present and demonstrate a novel single fiber optical tweezers which can trap and launch (clean) a target polystyrene (PS) microsphere (diameter~10μm) with independent control by using two wavelengths beams: 980nm and 1480nm. We employ 980nm laser beam to trap the target PS microsphere by molding the fiber tip into a special tapered-shape; and we employ 1480nm laser beam to launch the trapped PS microsphere with a certain velocity by using the thermophoresis force generated from the thermal effect due to the high absorption of the 1480nm laser beams in water. When the launching force is smaller than the trapping force, the PS microsphere will be trapped near the fiber tip, and the launching force will blow away other PS microspheres in the workspace realizing the cleaning function; When the launching force is larger than the trapping force, the trapped PS microsphere will be launched away from the fiber tip with a certain velocity and towards a certain direction, realizing the launching function. This PS microsphere launching and cleaning functions expanded new features of single fiber optical tweezers, providing for the possibility of more practical applications in the micro manipulation research fields.

  9. Determination of thermal equilibrium in a sealed cell based on optical depth

    NASA Astrophysics Data System (ADS)

    Zou, Sheng; Zhang, Hong; Chen, Xi-yuan; Shan, Guang-cun; Quan, Wei

    2017-01-01

    An effective method based on optical depth (OD) is presented to measure thermal equilibrium in a cell. First, the principle of determining the temperature distribution in the cell by using the OD is demonstrated. Subsequently, relevant experiments are carried out. Original experimental results showed that some gradients of OD distributions in the cell at different wavelengths and variations of the OD increased slowly along the direction of motion of the beam at a fixed wavelength. At a wavelength of 766.6839 nm, which is about 7 GHz blue shifted with respect to the potassium resonance, the average value of the OD was about 0.764 and the maximal and the minimum inhomogeneity biases among all location points were about 6.07% and 0.56%, respectively. As for the corresponding wavelengths of 766.67785 nm and 766.73004 nm, some deviations from previous results, which were caused by different absorptions of the alkali-metal atoms at different frequencies of the laser beam, were observed. The nonuniform OD values along the direction of motion of the beam reflected an inhomogeneous distribution of the temperature in the cell, which may have been caused by layout of the oven. When the layout of the oven was modified, comparative experiments comparable to these with the previous layout of the oven demonstrated that the uniformity of the temperature distribution in the cell was improved and that thermal equilibrium time was shorter by about 10 minutes. This method played an important role in determining the thermal equilibrium time in the cell.

  10. Tracking the Plasmapause by Its Optical and Thermal Signatures in the Ionosphere

    NASA Astrophysics Data System (ADS)

    Mendillo, M.; Wroten, J.; Baumgardner, J. L.; Martinis, C. R.; Smith, S. M.; Merenda, K.; Fritz, T. A.; Hairston, M. R.; Heelis, R. A.; Barbieri, C.

    2013-12-01

    Ionospheric optical emissions and in-situ plasma temperatures can be used to identify energy sources and structures in the magnetosphere via geomagnetic field-line mapping between the two regions. At mid-latitudes, stable auroral red (SAR) arcs appear in all-sky imagers (ASIs) with fields of view that map to the L ~ 2-4 domain of the inner magnetosphere. The emission at 6300 Å is excited at ~400 km by ambient ionospheric electrons heated by conduction from the plasmapause-ring current interaction region. The plasma instruments onboard the Defense Meteorological Satellite Program (DMSP) vehicles detect electron temperature (Te) enhancements and ionospheric plasma depletions along the same SAR arc field line at ~840 km. In this study, we present the first case of a SAR arc observed from three widely-spaced ASI systems (Europe, North American, New Zealand) during the geomagnetic storm of 26-27 September 2011. Mapping the SAR arcs' latitude centers-of-emission to the geomagnetic equatorial plane provided the continuous location of the plasmapause (to × 0.1 L-value) from 18:00 UT on the 26th to 18:00 UT on the 27th. Using the lowest latitude where Te = 5000 K as the thermal marker of a SAR arc at ~840 km, DMSP satellites F15-16-17 encountered this signature 60 times within the L < 4 Re domain during the same 24-hour UT period. The average location at dusk was Ldusk = 3.1 × 0.3 Re, while at dawn Ldawn = 2.7 × 0.1 Re, in excellent agreement with the SAR arc optical locations. We thus demonstrate than plasmapause locations can be determined under cloudy sky conditions using DMSP data (but only along satellite longitudes near dawn and dusk local times), while optical imaging can give locations of the plasmpause throughout the local time night (but only regionally, and only if skies are clear).

  11. Alkaline aluminum phosphate glasses for thermal ion-exchanged optical waveguide

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Chen, Baojie; Pun, Edwin Yue Bun; Lin, Hai

    2015-04-01

    Alkaline aluminum phosphate glasses (NMAP) with excellent chemical durability for thermal ion-exchanged optical waveguide have been designed and investigated. The transition temperature Tg (470 °C) is higher than the ion-exchange temperature (390 °C), which is favorable to sustain the stability of the glass structure for planar waveguide fabrication. The effective diffusion coefficient De of K+-Na+ ion exchange in NMAP glasses is 0.110 μm2/min, indicating that ion exchange can be achieved efficiently in the optical glasses. Single-mode channel waveguide has been fabricated on Er3+/Yb3+ doped NMAP glass substrate by standard micro-fabrication and K+-Na+ ion exchange. The mode field diameter is 9.6 μm in the horizontal direction and 6.0 μm in the vertical direction, respectively, indicating an excellent overlap with a standard single-mode fiber. Judd-Ofelt intensity parameter Ω2 is 5.47 × 10-20 cm2, implying a strong asymmetrical and covalent environment around Er3+ in the optical glasses. The full width at half maximum and maximum stimulated emission cross section of the 4I13/2 → 4I15/2 are 30 nm and 6.80 × 10-21 cm2, respectively, demonstrating that the phosphate glasses are potential glass candidates in developing compact optoelectronic devices. Pr3+, Tm3+ and Ho3+ doped NMAP glasses are promising candidates to fabricate waveguide amplifiers and lasers operating at special telecommunication windows.

  12. Fiber optic acoustic emission sensors for harsh environment health monitoring

    NASA Astrophysics Data System (ADS)

    Borinski, Jason W.; Duke, John C., Jr.; Horne, Michael R.

    2001-07-01

    Optical fiber sensors are rapidly emerging as viable alternatives to piezoelectric devices as effective means of detecting and quantifying acoustic emission (AE). Compared to traditional piezoelectric-based sensors, optical fiber sensors offer much smaller size, reduced weight, ability to operate at temperatures up to 2000 degree(s)C, immunity to electromagnetic interference, resistance to corrosive environments, inherent safety within flammable environments, and the ability to multiplex multiple sensors on a single fiber. The authors have investigated low-profile fiber optic-based AE sensors for non-destructive evaluation (NDE) systems. In particular, broadband and resonant type optical fiber sensors were developed for monitoring acoustic emission for NDE of pressurized composite vessels and commercial airframe structures. The authors developed an in-plane, broadband sensor design based on optical strain gage technology. In addition, an out-of-plane, resonant sensor was developed using micromachining techniques. The sensors have been evaluated for performance using swept frequency and impulse excitation techniques and compared to conventional piezoelectric transducers. Further, application experiments were conducted using these sensors on both aluminum lap-joints and composite fracture coupons, with collocated piezoelectric transducers. The results indicate that optical fiber AE sensors can be used as transducers sensitive to acoustic events and the indication of imminent failure of a structure, making these sensors useful in many applications where conventional piezoelectric transducers are not well suited.

  13. Advanced linear Fresnel optics for solar thermal energy (STE) production (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Collares-Pereira, Manuel

    2016-09-01

    One path towards low electricity cost is the use of ever higher concentration values, since that, in turn, will provide less thermal losses at higher temperatures and high temperature operation means higher thermodynamic efficiency in the conversion of heat into electricity. However concentration has an added value, since it is associated with larger primaries (see below) and thus with a reduction of collector rows in any given collector field. That, in turn, will reduce receiver length, connecting pipe lengths, number of components, thermal losses in pipes, heat transfer fluid mass, pumping power required (thus less parasitics), OM necessary, and all of that will contribute towards a lower electricity production cost. Conventional PT and LFR concentrators are, essentially, focusing optics solutions and thus very far from the concentration limits set by Non Imaging Optics. However if a conventional PT optics is designed to accommodate a second stage concentrator (or, even better, if a parabolic like primary is designed in an optimal way with a secondary concentrator for a given receiver) the result will have a much higher concentration, but also, as a consequence, a much larger size, since available evacuated tubular receivers come in basically one (standard) size : 70mm diameter. Thus from a typical aperture size of 6m and a concentration value of 26, to double the concentration value with n.i.o., would bring the aperture close to 12m, a value which is not practical for manufacture, transportation, field installation and operation (think about wind loads, for instance) . But with LFR technology this size limitation is not there at all, and low concentration values can now be substituted by much higher ones, and primaries between 20 and 30 m can be produced for the same tube. Some LFRs on the market do have second stage concentration and offer primaries of about 12m total mirror width when designed for those evacuated tubes. These correspond to a CPC type second

  14. Integrating SAR with Optical and Thermal Remote Sensing for Operational Near Real-Time Volcano Monitoring

    NASA Astrophysics Data System (ADS)

    Meyer, F. J.; Webley, P.; Dehn, J.; Arko, S. A.; McAlpin, D. B.

    2013-12-01

    Volcanic eruptions are among the most significant hazards to human society, capable of triggering natural disasters on regional to global scales. In the last decade, remote sensing techniques have become established in operational forecasting, monitoring, and managing of volcanic hazards. Monitoring organizations, like the Alaska Volcano Observatory (AVO), are nowadays heavily relying on remote sensing data from a variety of optical and thermal sensors to provide time-critical hazard information. Despite the high utilization of these remote sensing data to detect and monitor volcanic eruptions, the presence of clouds and a dependence on solar illumination often limit their impact on decision making processes. Synthetic Aperture Radar (SAR) systems are widely believed to be superior to optical sensors in operational monitoring situations, due to the weather and illumination independence of their observations and the sensitivity of SAR to surface changes and deformation. Despite these benefits, the contributions of SAR to operational volcano monitoring have been limited in the past due to (1) high SAR data costs, (2) traditionally long data processing times, and (3) the low temporal sampling frequencies inherent to most SAR systems. In this study, we present improved data access, data processing, and data integration techniques that mitigate some of the above mentioned limitations and allow, for the first time, a meaningful integration of SAR into operational volcano monitoring systems. We will introduce a new database interface that was developed in cooperation with the Alaska Satellite Facility (ASF) and allows for rapid and seamless data access to all of ASF's SAR data holdings. We will also present processing techniques that improve the temporal frequency with which hazard-related products can be produced. These techniques take advantage of modern signal processing technology as well as new radiometric normalization schemes, both enabling the combination of

  15. VERIFICATION OF PORTABLE OPTICAL AND THERMAL IMAGING DEVICES FOR LEAK DETECTION AT PETROLEUM REFINERIES AND CHEMICAL PLANTS

    EPA Science Inventory

    Optical and thermal imaging devices are remote sensing systems that can be used to detect leaking gas compounds such as methane and benzene. Use of these systems can reduce fugitive emission losses through early detection and repair at industrial facilities by providing an effici...

  16. UNDERSTANDING SYSTEMATIC MEASUREMENT ERROR IN THERMAL-OPTICAL ANALYSIS FOR PM BLACK CARBON USING RESPONSE SURFACES AND SURFACE CONFIDENCE INTERVALS

    EPA Science Inventory

    Results from a NIST-EPA Interagency Agreement on Understanding Systematic Measurement Error in Thermal-Optical Analysis for PM Black Carbon Using Response Surfaces and Surface Confidence Intervals will be presented at the American Association for Aerosol Research (AAAR) 24th Annu...

  17. Fiber optic DTS system application in the research of accumulation possibilities of thermal energy in the rock mass

    NASA Astrophysics Data System (ADS)

    Látal, Jan; Koudelka, Petr; Šiška, Petr; Skapa, Jan; Hanáečk, František; Vašinek, Vladimír; Vitásek, Jan; Hejduk, Stanislav; Bocheza, Jiří

    2011-05-01

    The team of authors tries to provide information on the results of the fiber-optic DTS system application under long-term research of accumulation possibilities of thermal energy in the rock mass in this article. In 2006, was in Ostrava implemented the largest object in the Czech Republic, which is heated by heat pump system. It is a multi-purpose aula at VŠB-TU + CIT (Center for Information Technology). The installed heat pump system consists of ten heat pumps with a total output of 700kW and 110 wells about 140m deep. The applied research is conducted in two measuring polygons ("Big" and "Little" polygon). Simultaneously with fiber-optic DTS system is applied group of PT1000 temperature sensors and Geothermal Response Test (GERT). Fiber-optic DTS system is deployed inside polyethylene PE collector via a special sensory fiber optic cable. The ecological antifreeze mixture, based on the technical spirit, used for the collection and delivery of energy to the rock mass circulates inside of PE collector. PT1000 temperature sensors are placed at certain intervals on the outer side of the PE U-tube within the heat well. The result of application of the fiberoptic DTS system is information about the heat profile of wells, thermal conductivity of the geological environment and the impact of external changes in the thermal wells, along with the accumulation possibilities of thermal energy in the rock mass (over-summer period).

  18. OPTIMIZATION OF THERMAL OPTICAL ANALYSIS FOR THE MEASUREMENT OF BLACK CARBON IN REGIONAL PM2.5: A CHEMOMETRIC APPROACH

    EPA Science Inventory

    Thermal-optical analysis (TOA) is the principal method of the U.S. EPA's National Air Monitoring System for determining refractory carbon from combustion, or elemental carbon (EC), in particulate matter <2.5 µm (PM2.5). To isolate and quantify EC from organic carbon (...

  19. Distributed fiber optic sensors embedded in technical textiles for structural health monitoring

    NASA Astrophysics Data System (ADS)

    Krebber, Katerina; Lenke, Philipp; Liehr, Sascha; Noether, Nils; Wendt, Mario; Wosniok, Aleksander

    2010-09-01

    Technical textiles with embedded distributed fiber optic sensors have been developed for the purposes of structural health monitoring in geotechnical and civil engineering. The distributed fiber optic sensors are based on Brillouin scattering in silica optical fibers and OTDR in polymer optical fibers. Such "smart" technical textiles can be used for reinforcement of geotechnical and masonry structures and the embedded fiber optic sensors can provide information about the condition of the structures and detect the presence of any damages and destructions in real time. Thus, structural health monitoring of critical geotechnical and civil infrastructures can be realized. The paper highlights the results achieved in this innovative field in the framework of several German and European projects.

  20. Improved Thermal-Vacuum Compatible Flat Plate Radiometric Source For System-Level Testing Of Optical Sensors

    NASA Technical Reports Server (NTRS)

    Schwarz, Mark A.; Kent, Craig J.; Bousquet, Robert; Brown, Steven W.

    2016-01-01

    In this work, we describe an improved thermal-vacuum compatible flat plate radiometric source which has been developed and utilized for the characterization and calibration of remote optical sensors. This source is unique in that it can be used in situ, in both ambient and thermal-vacuum environments, allowing it to follow the sensor throughout its testing cycle. The performance of the original flat plate radiometric source was presented at the 2009 SPIE1. Following the original efforts, design upgrades were incorporated into the source to improve both radiometric throughput and uniformity. The pre-thermal-vacuum (pre-TVAC) testing results of a spacecraft-level optical sensor with the improved flat plate illumination source, both in ambient and vacuum environments, are presented. We also briefly discuss potential FPI configuration changes in order to improve its radiometric performance.

  1. Improved thermal-vacuum compatible flat plate radiometric source for system-level testing of remote optical sensors

    NASA Astrophysics Data System (ADS)

    Schwarz, Mark A.; Kent, Craig J.; Bousquet, Robert; Brown, Steven W.

    2016-09-01

    In this work, we describe an improved thermal-vacuum compatible flat plate radiometric source which has been developed and utilized for the characterization and calibration of remote optical sensors. This source is unique in that it can be used in situ, in both ambient and thermal-vacuum environments, allowing it to follow the sensor throughout its testing cycle. The performance of the original flat plate radiometric source was presented at the 2009 SPIE1. Following the original efforts, design upgrades were incorporated into the source to improve both radiometric throughput and uniformity. The pre-thermal-vacuum (pre-TVAC) testing results of a spacecraft-level optical sensor with the improved flat plate illumination source, both in ambient and vacuum environments, are presented. We also briefly discuss potential FPI configuration changes in order to improve its radiometric performance. Keywords: Calibration, radiometry, remote sensing, source.

  2. Optical characterization of thermally evaporated thin films of As40S40Se20 chalcogenide glass by reflectance measurements

    NASA Astrophysics Data System (ADS)

    Márquez, E.; González-Leal, J. M.; Prieto-Alcón, R.; Vlcek, M.; Stronski, A.; Wagner, T.; Minkov, D.

    Optical reflection spectra, at normal incidence, of ternary chalcogenide thin films of chemical composition As40S40Se20, deposited by thermal evaporation, were obtained in the 400 nm to 2200 nm spectral region. The optical constants of this amorphous material were computed using an optical characterization method based mainly on the ideas of Minkov and Swanepoel of utilising the upper and lower envelopes of the spectrum, which allows us to obtain both the real and imaginary parts of the complex refractive index, and the film thickness. Thickness measurements made by a surface-profiling stylus have been carried out to cross-check the results obtained by the optical method. The dispersion of the refractive index is discussed in terms of the single-oscillator Wemple-DiDomenico model. The optical band gap has been determined from absorption coefficient data by Tauc's procedure. Finally, the photo-induced and thermally induced changes in the optical properties of a-As40S40Se20 thin films were also studied, using both transmission and reflection spectra.

  3. Multispectral Thermal Imager Optical Assembly Performance and Intergration of the Flight Focal Plane Assembly

    SciTech Connect

    Blake, Dick; Byrd, Don; Christensen, Wynn; Henson, Tammy; Krumel, Les; Rappoport, William; Shen, Gon-Yen

    1999-06-08

    The Multispectral Thermal Imager Optical Assembly (OA) has been fabricated, assembled, successfully performance tested, and integrated into the flight payload structure with the flight Focal Plane Assembly (FPA) integrated and aligned to it. This represents a major milestone achieved towards completion of this earth observing E-O imaging sensor that is to be operated in low earth orbit. The OA consists of an off-axis three mirror anastigmatic (TMA) telescope with a 36 cm unobscured clear aperture, a wide-field-of-view (WFOV) of 1.82° along the direction of spacecraft motion and 1.38° across the direction of spacecraft motion. It also contains a comprehensive on-board radiometric calibration system. The OA is part of a multispectral pushbroom imaging sensor which employs a single mechanically cooled focal plane with 15 spectral bands covering a wavelength range from 0.45 to 10.7 µm. The OA achieves near diffraction-limited performance from visible to the long-wave infrared (LWIR) wavelengths. The two major design drivers for the OA are 80% enpixeled energy in the visible bands and radiometric stability. Enpixeled energy in the visible bands also drove the alignment of the FPA detectors to the OA image plane to a requirement of less than ± 20 µm over the entire visible detector field of view (FOV). Radiometric stability requirements mandated a cold Lyot stop for stray light rejection and thermal background reduction. The Lyot stop is part of the FPA assembly and acts as the aperture stop for the imaging system. The alignment of the Lyot stop to the OA drove the centering and to some extent the tilt alignment requirements of the FPA to the OA.

  4. Magnetomotive optical coherence elastography (MM-OCE) for thermal therapy dosimetry (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Huang, Pin-Chieh; Marjanovic, Marina; Spillman, Darold R.; Odintsov, Boris M.; Boppart, Stephen A.

    2016-03-01

    Biomechanical properties of tissues have been utilized for disease detection, diagnosis, and progression, however they have not been extensively utilized for therapy dosimetry. Magnetic hyperthermia aims to kill cells and ablate tumors using magnetic nanoparticles (MNPs) either injected in or targeted to tumors. Upon application of an appropriate AC magnetic field, MNPs can heat target tissue while sparing non-targeted healthy tissue. However, a sensitive monitoring technique for the dose of magnetic hyperthermia is needed to prevent over-treatment and collateral injury. During hyperthermia treatments, the viscoelastic properties of tissues are altered due to protein denaturation, coagulation, and tissue dehydration, making these properties candidates for dosimetry. Magnetomotive optical coherence elastography (MM-OCE) utilizes MNPs as internal force transducers to probe the biomechanical properties of tissues. Therefore, we aim to evaluate the hyperthermia dose based on the elastic changes revealed by MM-OCE. In this study, MNPs embedded in tissues were utilized for both hyperthermia and MM-OCE measurements. Tissue temperature and elastic modulus were obtained, where the elastic modulus was extracted from the resonance frequency detected by MM-OCE. Results showed a correlation between stiffness and temperature change following treatment. To investigate the thermal-dose-dependent changes, intervals of hyperthermia treatment were repeatedly performed on the same tissue sequentially, interspersed with MM-OCE. With increasing times of treatment, tissue stiffness increased, while temperature rise remained relatively constant. These results suggest that MM-OCE may potentially identify reversible and irreversible tissue changes during thermal therapy, supporting the use of MM-OCE for dosimetric control of hyperthermia in future applications.

  5. Thermal impact of near-infrared laser in advanced noninvasive optical brain imaging

    PubMed Central

    Nourhashemi, Mina; Mahmoudzadeh, Mahdi; Wallois, Fabrice

    2016-01-01

    Abstract. The propagation of laser light in human tissues is an important issue in functional optical imaging. We modeled the thermal effect of different laser powers with various spot sizes and different head tissue characteristics on neonatal and adult quasirealistic head models. The photothermal effect of near-infrared laser (800 nm) was investigated by numerical simulation using finite-element analysis. Our results demonstrate that the maximum temperature increase on the brain for laser irradiance between 0.127 (1 mW) and 12.73  W/cm2 (100 mW) at a 1 mm spot size, ranged from 0.0025°C to 0.26°C and from 0.03°C to 2.85°C at depths of 15.9 and 4.9 mm in the adult and neonatal brain, respectively. Due to the shorter distance of the head layers from the neonatal head surface, the maximum temperature increase was higher in the neonatal brain than in the adult brain. Our results also show that, at constant power, spot size changes had a lesser heating effect on deeper tissues. While the constraints for safe laser irradiation to the brain are dictated by skin safety, these results can be useful to optimize laser parameters for a variety of laser applications in the brain. Moreover, combining simulation and adequate in vitro experiments could help to develop more effective optical imaging to avoid possible tissue damage. PMID:27115020

  6. Investigations on optical, structural and thermal properties of phosphate glasses containing terbium ions

    NASA Astrophysics Data System (ADS)

    Elisa, M.; Sava, B. A.; Vasiliu, I. C.; Monteiro, R. C. C.; Iordanescu, C. R.; Feraru, I. D.; Ghervase, L.; Tanaselia, C.; Senila, M.; Abraham, B.

    2013-12-01

    Aluminophosphate glasses belonging to the Li2O-BaO-Al2O3- La2O3-P2O5 system doped with Tb3+ were prepared and investigated. Methods as Induced Coupled Plasma-Mass Spectrometry (ICP-MS), Induced Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) and X-ray diffraction (XRD) have been used to establish the elemental composition of these vitreous materials. The influence of the Tb3+ ions on the optical properties of the phosphate glasses has been investigated in relation with the structural characteristics of the vitreous matrix. The optical behavior has been studied by ultra-violet-visible (UV-Vis) spectroscopy, revealing electronic transitions specific for terbium ions. Fluorescence spectroscopy measurements have been performed by excitation in the UV and visible domains (377 nm and 488 nm) which resulted in the most significant fluorescence peaks in the Vis domain (540 and 547 nm). Structural information via vibration modes were provided by Fourier Transform Infrared (FTIR) absorption spectra in the 400-4000 cm-1 range. Absorption peaks specific for the vitreous phosphate matrix were put in evidence as P-O-P symmetrical and asymmetrical stretching vibration modes, P-O-P bend, PO2- symmetrical and asymmetrical stretching vibration modes, P=O stretching vibration mode as well as P-O-H water absorbance. Raman spectra acquired in the 100-4000 cm-1 range by 488, 514 and 633 nm laser excitation sources disclosed peaks also specific for the phosphate matrix, proving the role of phosphorous oxide as a vitreous network former. Differential Scanning Calorimetry and Thermogravimetric Analysis (DSC-TGA) provided information regarding the phase transformations that took place during the heating process and the associated thermal effects.

  7. Evaluation of thermal expansion coefficient of Fabry-Perot cavity using an optical frequency comb

    NASA Astrophysics Data System (ADS)

    Oulehla, Jindřich; Šmíd, Radek; Buchta, Zdeněk; Čížek, Martin; Mikel, Břetislav; Jedlička, Petr; Lazar, Josef; Číp, Ondřej

    2011-05-01

    In construction of highly mechanically stable measuring devices like AFM microscopes or nano-comparators the use of low expansion materials is very necessary. We can find Zerodur ceramics or ULE glasses used as a frame or basement of these devices. The expansion coefficient of such low-expansion materials is lower than 0.01 x 10-6 m•K-1. For example in case of a frame or basement 20 cm long it leads to a dilatation approximately 4 nm per 1 K. For calculation of the total uncertainty of the mentioned measuring devices the knowledge of the thermal expansion coefficient of the frame or basement is necessary. In this work we present a method, where small distance changes are transformed into rf-frequency signal. The frequency of this signal is detected by a counter which measures the value of the frequency with respect to an ultra-stable time-base. This method uses a Fabry-Perot cavity as a distance measuring tool. The spacer of the optical resonator is made from the investigated low-expansion material. It is placed into a vacuum chamber where the inside temperature is controlled. A selected mode of the femtosecond frequency of the femtosecond comb which represent the distance changes of the optical resonator. The frequency is measured by the rf-counter which is synchronized by a time-base signal from an atomic clock. The first results show the resolution of the method in the 0.1 nm order. Therefore the method has a potential in characterisation of materials in the nanoworld.

  8. Thermal casting of polymers in centrifuge for producing X-ray optics

    DOEpatents

    Hill, Randy M [Livermore, CA; Decker, Todd A [Livermore, CA

    2012-03-27

    An optic is produced by the steps of placing a polymer inside a rotateable cylindrical chamber, the rotateable cylindrical chamber having an outside wall, rotating the cylindrical chamber, heating the rotating chamber forcing the polymer to the outside wall of the cylindrical chamber, allowing the rotateable cylindrical chamber to cool while rotating producing an optic substrate with a substrate surface, sizing the optic substrate, and coating the substrate surface of the optic substrate to produce the optic with an optic surface.

  9. Comparison of cooperative and non-cooperative adaptive optics reference performance for propagation with thermal blooming effects

    NASA Astrophysics Data System (ADS)

    Edwards, Brian E.; Nitkowski, Arthur; Lawrence, Ryan; Horton, Kasey; Higgs, Charles

    2004-10-01

    Atmospheric turbulence and laser-induced thermal blooming effects can degrade the beam quality of a high-energy laser (HEL) weapon, and ultimately limit the amount of energy deliverable to a target. Lincoln Laboratory has built a thermal blooming laboratory capable of emulating atmospheric thermal blooming and turbulence effects for tactical HEL systems. The HEL weapon emulation hardware includes an adaptive optics beam delivery system, which utilizes a Shack-Hartman wavefront sensor and a 349 actuator deformable mirror. For this experiment, the laboratory was configured to emulate an engagement scenario consisting of sea skimming target approaching directly toward the HEL weapon at a range of 10km. The weapon utilizes a 1.5m aperture and radiates at a 1.62 micron wavelength. An adaptive optics reference beam was provided as either a point source located at the target (cooperative) or a projected point source reflected from the target (uncooperative). Performance of the adaptive optics system was then compared between reference sources. Results show that, for operating conditions with a thermal blooming distortion number of 75 and weak turbulence (Rytov of 0.02 and D/ro of 3), cooperative beacon AO correction experiences Phase Compensation Instability, resulting in lower performance than a simple, open-loop condition. The uncooperative beacon resulted in slightly better performance than the open-loop condition.

  10. Thermal, spectroscopic and laser properties of Nd3+ in gadolinium scandium gallium garnet crystal produced by optical floating zone method

    NASA Astrophysics Data System (ADS)

    Tian, Li; Wang, Shuxian; Wu, Kui; Wang, Baolin; Yu, Haohai; Zhang, Huaijin; Cai, Huaqiang; Huang, Hui

    2013-12-01

    A neodymium-doped gadolinium scandium gallium garnet (Nd:GSGG) single crystal with dimensions of Φ 5 × 20 mm2 has been grown by means of optical floating zone (OFZ). X-ray powder diffraction (XRPD) result shows that the as-grown Nd:GSGG crystal possesses a cubic structure with space group Ia3d and a cell parameter of a = 1.2561 nm. Effective elemental segregation coefficients of the Nd:GSGG as-grown crystal were calculated by using X-ray fluorescence (XRF). The thermal properties of the Nd:GSGG crystal were systematically studied by measuring the specific heat, thermal expansion and thermal diffusion coefficient, and the thermal conductivity of this crystal was calculated. The absorption and luminescence spectra of Nd:GSGG were measured at room temperature (RT). By using the Judd-Ofelt (J-O) theory, the theoretical radiative lifetime was calculated and compared with the experimental result. Continuous wave (CW) laser performance was achieved with the Nd:GSGG at the wavelength of 1062 nm when it was pumped by a laser diode (LD). A maximum output power of 0.792 W at 1062 nm was obtained with a slope efficiency of 11.89% under a pump power of 7.36 W, and an optical-optical conversion efficiency of 11.72%.

  11. Thermal decomposition of nano-enabled thermoplastics: Possible environmental health and safety implications

    PubMed Central

    Sotiriou, Georgios A.; Singh, Dilpreet; Zhang, Fang; Chalbot, Marie-Cecile G.; Spielman-Sun, Eleanor; Hoering, Lutz; Kavouras, Ilias G.; Lowry, Gregory V.; Wohlleben, Wendel; Demokritou, Philip

    2015-01-01

    Nano-enabled products (NEPs) are currently part of our life prompting for detailed investigation of potential nano-release across their life-cycle. Particularly interesting is their end-of-life thermal decomposition scenario. Here, we examine the thermal decomposition of a widely used NEP, namely thermoplastic nanocomposites, and assess the properties of the byproducts (released aerosol and residual ash) and possible environmental health and safety implications. We focus on establishing a fundamental understanding on the effect of thermal decomposition parameters, such as polymer matrix, nanofiller properties, decomposition temperature, on the properties of byproducts using a recently-developed lab-based experimental integrated platform. Our results indicate that thermoplastic polymer matrix strongly influences size and morphology of released aerosol, while there was minimal but detectable nano-release, especially when inorganic nanofillers were used. The chemical composition of the released aerosol was found not to be strongly influenced by the presence of nanofiller at least for the low, industry-relevant loadings assessed here. Furthermore, the morphology and composition of residual ash was found to be strongly influenced by the presence of nanofiller. The findings presented here on thermal decomposition/incineration of NEPs raise important questions and concerns regarding the potential fate and transport of released engineered nanomaterials in environmental media and potential environmental health and safety implications. PMID:26642449

  12. Thermal decomposition of nano-enabled thermoplastics: Possible environmental health and safety implications.

    PubMed

    Sotiriou, Georgios A; Singh, Dilpreet; Zhang, Fang; Chalbot, Marie-Cecile G; Spielman-Sun, Eleanor; Hoering, Lutz; Kavouras, Ilias G; Lowry, Gregory V; Wohlleben, Wendel; Demokritou, Philip

    2016-03-15

    Nano-enabled products (NEPs) are currently part of our life prompting for detailed investigation of potential nano-release across their life-cycle. Particularly interesting is their end-of-life thermal decomposition scenario. Here, we examine the thermal decomposition of widely used NEPs, namely thermoplastic nanocomposites, and assess the properties of the byproducts (released aerosol and residual ash) and possible environmental health and safety implications. We focus on establishing a fundamental understanding on the effect of thermal decomposition parameters, such as polymer matrix, nanofiller properties, decomposition temperature, on the properties of byproducts using a recently-developed lab-based experimental integrated platform. Our results indicate that thermoplastic polymer matrix strongly influences size and morphology of released aerosol, while there was minimal but detectable nano-release, especially when inorganic nanofillers were used. The chemical composition of the released aerosol was found not to be strongly influenced by the presence of nanofiller at least for the low, industry-relevant loadings assessed here. Furthermore, the morphology and composition of residual ash was found to be strongly influenced by the presence of nanofiller. The findings presented here on thermal decomposition/incineration of NEPs raise important questions and concerns regarding the potential fate and transport of released engineered nanomaterials in environmental media and potential environmental health and safety implications.

  13. Thermal and health outcomes of energy efficiency retrofits of homes of older adults.

    PubMed

    Ahrentzen, S; Erickson, J; Fonseca, E

    2016-08-01

    Mitigation of thermal stress and adverse indoor climatic conditions is important to older low-income populations whose age, health, and economic circumstances make them vulnerable to indoor environmental conditions. This research examines whether energy retrofits in affordable housing for older adults can also improve indoor climatic (i.e., temperature, humidity, air infiltration) conditions and whether such improvements correspond with improved health and comfort of residents. An apartment complex for low-income older adults in Phoenix was the study site. In 2010, renovations were undertaken to make it more energy efficient and to replace interior cabinetry, flooring, and paint with materials that had low or no volatile organic compounds (VOCs). Fifty-seven residents from 53 apartment units participated in both baseline (pre-renovation) and 1 year post-renovation data collection trials. Environmental measures included temperature, relative humidity, and air infiltration. Health measures included general health, emotional distress, and sleep. Four questions addressed residents' perceptions of temperature quality. Results demonstrated a 19% reduction in energy consumption following the retrofit. In addition, fixed effects statistical models of the panel data showed significant stabilization of unit temperature from pre-retrofit to 1 year post-retrofit. Reductions in an apartment's temperature extremes of 27.2°C (81°F) and above also corresponded with improvement in occupant's reported health over the same time period, although not with occupant's perceptions of thermal comfort.

  14. Optical assembly of a visible-through-thermal infrared multispectral imaging system

    NASA Astrophysics Data System (ADS)

    Henson, Tammy D.; Bender, Steven C.; Byrd, Donald A.; Rappoport, William M.; Shen, Gon-Yen

    1998-10-01

    The Optical Assembly (OA) for the Multispectral Thermal Imger (MTI) program has been fabricated, assembled, and successfully tested for its performance. It represents a major milestone achieved towards completion of this earth observing EO imaging sensor that is to be operated in low earth orbit. Along with its wide field of view, 1.82 degrees along-track and 1.38 degrees cross-track, and comprehensive on-board calibration system, the pushbroom imaging sensor employs a single mechanically cooled focal plane with 15 spectral bands covering a wavelength range from 0.45 to 10.7 micrometers . The OA has an off-axis three-mirror anastigmatic telescope with a 36-cm unobscured clear aperture. The two key performance criteria, 80 percent enpixeled energy in the visible and radiometric stability of 1 percent 1 (sigma) in the visible/near-IR and short wavelength IR, of 1.45 percent 1 (sigma) in the medium wavelength IR, and of 0.53 percent 1 (sigma) long wavelength IR, as well as its low weight and volume constraint drive the overall design configuration of the OA and fabrication requirements.

  15. Thermal nonlinear optical properties of TiO2 nanocrystals prepared through pulsed laser ablation

    NASA Astrophysics Data System (ADS)

    Moslehirad, F.; Majles Ara, M. H.; Torkamany, M. J.; Afsary, M.; Ghorannevis, M.; Sabbaghzadeh, J.

    2013-05-01

    Titanium dioxide (TiO2) nanoparticles (NPs) were synthesized using the pulsed laser ablation method by irradiating a titanium target immersed in distilled water with 1064 nm, Nd:YAG (yttrium aluminum garnet) laser pulses. The indirect band gap of the NPs was estimated with the aid of ultraviolet/visible spectroscopy. Transmission electron microscopy showed the NPs to be spherical in shape and to vary from 5 to 50 nm. The average size of the NPs and their crystalline phases were determined by means of x-ray diffraction analysis. The thermal conductivity of the nano-TiO2 colloids was measured at a temperature of 25 °C. The single-beam z-scan technique was employed to obtain the nonlinear index of refraction (n2) and the nonlinear absorption coefficient (β) under continuous wave He-Ne laser excitation at different input powers. Thermo-optical coefficients of the NPs were calculated using the z-scan results.

  16. A study of the thermal and optical characteristics of radiometric channels for Earth radiation budget applications

    NASA Technical Reports Server (NTRS)

    Mahan, J. R.; Tira, Nour E.

    1991-01-01

    An improved dynamic electrothermal model for the Earth Radiation Budget Experiment (ERBE) total, nonscanning channels is formulated. This model is then used to accurately simulate two types of dynamic solar observation: the solar calibration and the so-called pitchover maneuver. Using a second model, the nonscanner active cavity radiometer (ACR) thermal noise is studied. This study reveals that radiative emission and scattering by the surrounding parts of the nonscanner cavity are acceptably small. The dynamic electrothermal model is also used to compute ACR instrument transfer function. Accurate in-flight measurement of this transfer function is shown to depend on the energy distribution over the frequency spectrum of the radiation input function. A new array-type field of view limiter, whose geometry controls the input function, is proposed for in-flight calibration of an ACR and other types of radiometers. The point spread function (PSF) of the ERBE and the Clouds and Earth's Radiant Energy System (CERES) scanning radiometers is computed. The PSF is useful in characterizing the channel optics. It also has potential for recovering the distribution of the radiative flux from Earth by deconvolution.

  17. Thermally and optically stimulated luminescence of new ZnO nanophosphors exposed to beta particle irradiation

    NASA Astrophysics Data System (ADS)

    Cruz-v&Ázquez, C.; Burruel-Ibarra, S. E.; Grijalva-Monteverde, H.; Chernov, V.; Bernal, R.

    In this work, we report on the thermoluminescence (TL) and the optically stimulated luminescence (OSL) of ZnO nanophosphors obtained by thermal annealing of ZnS powders synthesized by precipitation in a chemical bath deposition reaction. To obtain nanocrystalline ZnO, ZnS pellet-shaped samples were subjected to a sintering process at 700 °C during 24 h exposed to air at atmospheric pressure. Some samples were exposed to beta particles in the 0.15-10.15 kGy dose range and the integrated TL as a function of dose increased with dose level, with no saturation indication for the tested dose levels. Computerized glow-curve deconvolution of the experimental glow curves in individual peaks revealed a second-order kinetics. In order to test the OSL response, samples were irradiated with beta particles with doses up to 600 Gy, and an increasing intensity as dose increased was observed. We conclude that the new ZnO phosphors under investigation are good candidates to be used as dosimetric materials.

  18. 3β-Acetoxy-6-nitrocholest-5-ene: Crystal structure, thermal, optical and dielectrical behavior

    NASA Astrophysics Data System (ADS)

    Shamsuzzaman; Mashrai, Ashraf; Khanam, Hena; Mabkhot, Yahia Nasser; Frey, Wolfgang

    2014-04-01

    3β-Acetoxy-6-nitrocholest-5-ene (2) has been synthesized from 3β-acetoxycholest-5-ene (1). We provided an analysis of the compound by means of FT-IR, FT-Raman, NMR and X-ray crystallography. In addition microstructural, thermal, optical and dielectrical properties were also investigated. The compound 2 crystallizes in the monoclinic space group P21 with cell dimensions, a = 15.7729 (13) Å, b = 9.8933 (8) Å, c = 17.8070(14) Å, α = 90.00, β = 96.176(4), γ = 90.00. The powder X-ray diffraction (PXRD) of the compound was recorded to ascertain phase homogeneity. The SEM micrograph showed the presence of brick shaped, elongated nitrocholestane particles with 177.12 × 25.53 × 5.69 μm dimensions. Thermogravimetric analysis showed stability of the compound up to 200 °C. The dielectrical studies showed that with increase in frequency, the dielectric constant decreases and becomes almost constant at high frequencies.

  19. Band gap energy and optical transitions in polyenes formed by thermal decomposition of polyvinyl alcohol

    NASA Astrophysics Data System (ADS)

    Kulak, A. I.; Bondarava, G. V.; Shchurevich, O. A.

    2013-07-01

    The band gap of the ensemble of oligoene clusters formed by thermocatalytic decomposition of polyvinyl alcohol is parametrized using optical absorption spectra. A band gap energy of E gm =1.53 ± 0.02 eV at the end of an infinite polyene chain is found by extrapolating the energies of π → π* transitions in clusters with a number of double bonds varying from 4 to 12. This value is close to the band gap of trans-polyacetylene and the lower bound for the Tauc energy E gT =1.50 eV, which characterizes the minimum interband transition energy. E gT is essentially independent of the concentration of oligoene clusters, which is determined by the concentration of the AlCl3 thermal decomposition catalyst. The Urbach energy determined from the long wavelength edge of the spectrum falls from 2.21 to 0.66 eV as the AlCl3 concentration is raised from 11.1 to 41.7 mmol per mol of polyvinyl alcohol structural units.

  20. Optical assembly of a visible through thermal infrared multispectral imaging system

    SciTech Connect

    Henson, T.; Bender, S.; Byrd, D.; Rappoport, W.; Shen, G.Y.

    1998-06-01

    The Optical Assembly (OA) for the Multispectral Thermal Imager (MTI) program has been fabricated, assembled, and successfully tested for its performance. It represents a major milestone achieved towards completion of this earth observing E-O imaging sensor that is to be operated in low earth orbit. Along with its wide-field-of-view (WFOV), 1.82{degree} along-track and 1.38{degree} cross-track, and comprehensive on-board calibration system, the pushbroom imaging sensor employs a single mechanically cooled focal plane with 15 spectral bands covering a wavelength range from 0.45 to 10.7 {micro}m. The OA has an off-axis three-mirror anastigmatic (TMA) telescope with a 36-cm unobscured clear aperture. The two key performance criteria, 80% enpixeled energy in the visible and radiometric stability of 1% 1{sigma} in the visible/near-infrared (VNIR) and short wavelength infrared (SWIR), of 1.45% 1{sigma} in the medium wavelength infrared (MWIR), and of 0.53% 1{sigma} long wavelength infrared (LWIR), as well as its low weight (less than 49 kg) and volume constraint (89 cm x 44 cm x 127 cm) drive the overall design configuration of the OA and fabrication requirements.

  1. Optical Absorption and Photo-Thermal Conversion Properties of CuO/H2O Nanofluids.

    PubMed

    Wang, Liangang; Wu, Mingyan; Wu, Daxiong; Zhang, Canying; Zhu, Qunzhi; Zhu, Haitao

    2015-04-01

    Stable CuO/H2O nanofluids were synthesized in a wet chemical method. Optical absorption property of CuO/H2O nanofluids was investigated with hemispheric transmission spectrum in the wavelength range from 200 nm to 2500 nm. Photo-thermal conversion property of the CuO/H2O nanofluids was studied with an evaluation system equipped with an AUT-FSL semiconductor/solid state laser. The results indicate that CuO/H2O nanofluids have strong absorption in visible light region where water has little absorption. Under the irradiation of laser beam with a wavelength of 635 nm and a power of 0.015 W, the temperature of CuO/H2O nanofluids with 1.0% mass fraction increased by 5.6 °C within 40 seconds. Furthermore, the temperature elevation of CuO/H2O nanofluids was proved to increase with increasing mass fractions. On the contrast, water showed little temperature elevation under the identical conditions. The present work shows that the CuO/H2O nanofluids have high potential in the application as working fluids for solar utilization purpose.

  2. Harmonizing aerosol carbon measurements between two conventional thermal/optical analysis methods.

    PubMed

    Zhi, Guorui; Chen, Yingjun; Sun, Junying; Chen, Laiguo; Tian, Wenjuan; Duan, Jingchun; Zhang, Gan; Chai, Fahe; Sheng, Guoying; Fu, Jiamo

    2011-04-01

    Although total carbon (TC) can be consistently quantified by various aerosol carbon measurement methods, the demarcation of TC into organic carbon (OC) and elemental carbon (EC) has long been inconsistent. The NIOSH and IMPROVE protocols are most widely used for thermal/optical analysis (TOA), but current knowledge rests in the description that the NIOSH protocol usually gives lower EC values than does the IMPROVE protocol. This study seeks to explore the possibility of quantitatively linking the difference between the two TOA protocols. Residential coal-burning samples that had been collected and analyzed following the NIOSH protocol in previous studies were directly reanalyzed following the IMPROVE protocol for this study. A comparison of each pair of NIOSH and IMPROVE EC values reveals the dynamic relation between the two protocols, which can be expressed as a regression equation, y=(1-x)/(1+4.86x2) (R2=0.96), where the independent x is the EC/TC ratio R(EC/TC) for the IMPROVE protocol, and the dependent y is the difference between IMPROVE and NIOSH REC/TC relative to IMPROVE REC/TC. This regression equation may be the first effort in formulating the relationship between the two TOA protocols, and it is very helpful in harmonizing inconsistent TOA measurements, for example, source characterization, ambient monitoring, and atmospheric modeling.

  3. Effect of thermal annealing on structural and optical properties of In{sub 2}S{sub 3} thin films

    SciTech Connect

    Choudhary, Sonu

    2015-08-28

    There is a highly need of an alternate of toxic materials CdS for solar cell applications and indium sulfide is found the most suitable candidate to replace CdS due to its non-toxic and environmental friendly nature. In this paper, the effect of thermal annealing on the structural and optical properties of indium sulfide (In{sub 2}S{sub 3}) thin films is undertaken. The indium sulfide thin films of 121 nm were deposited on glass substrates employing thermal evaporation method. The films were subjected to the X-ray diffractometer and UV-Vis spectrophotometer respectively for structural and optical analysis. The XRD pattern show that the as-deposited thin film was amorphous in nature and crystallinity is found to be varied with annealing temperature. The optical analysis reveals that the optical band gap is varied with annealing. The optical parameters like absorption coefficient, extinction coefficient and refractive index were calculated. The results are in good agreement with available literature.

  4. Influence of Annealing on the Optical Parameters of In2S3 Thin Films Produced by Thermal Evaporation

    NASA Astrophysics Data System (ADS)

    Izadneshan, H.; Gremenok, V. F.

    2014-05-01

    In2S3 thin fi lms are grown on glass substrates by vacuum thermal evaporation followed by annealing in vacuum between 330 and 400 °C for different time durations. We have investigated the infl uence of the annealing parameters on the characteristics of thin fi lms. It is shown that thermal treatment changed the crystal structure and optical energy band gap of In2S3 thin fi lms. Two energy band gaps were determined for all the fi lms, one indirect and the other direct.

  5. Structural, thermal, and optical performance (STOP) modeling and results for the James Webb Space Telescope integrated science instrument module

    NASA Astrophysics Data System (ADS)

    Gracey, Renee; Bartoszyk, Andrew; Cofie, Emmanuel; Comber, Brian; Hartig, George; Howard, Joseph; Sabatke, Derek; Wenzel, Greg; Ohl, Raymond

    2016-08-01

    The James Webb Space Telescope includes the Integrated Science Instrument Module (ISIM) element that contains four science instruments (SI) including a Guider. We performed extensive structural, thermal, and optical performance (STOP) modeling in support of all phases of ISIM development. In this paper, we focus on modeling and results associated with test and verification. ISIM's test program is bound by ground environments, mostly notably the 1g and test chamber thermal environments. This paper describes STOP modeling used to predict ISIM system performance in 0g and at various on-orbit temperature environments. The predictions are used to project results obtained during testing to on-orbit performance.

  6. Structural health monitoring system of soccer arena based on optical sensors

    NASA Astrophysics Data System (ADS)

    Shishkin, Victor V.; Churin, Alexey E.; Kharenko, Denis S.; Zheleznova, Maria A.; Shelemba, Ivan S.

    2014-05-01

    A structural health monitoring system based on optical sensors has been developed and installed on the indoor soccer arena "Zarya" in Novosibirsk. The system integrates 119 fiber optic sensors: 85 strain, 32 temperature and 2 displacement sensors. In addition, total station is used for measuring displacement in 45 control points. All of the constituents of the supporting structure are subjects for monitoring: long-span frames with under floor ties, connections, purlins and foundation.

  7. Some controversies in endovenous laser ablation of varicose veins addressed by optical-thermal mathematical modeling.

    PubMed

    Poluektova, Anna A; Malskat, Wendy S J; van Gemert, Martin J C; Vuylsteke, Marc E; Bruijninckx, Cornelis M A; Neumann, H A Martino; van der Geld, Cees W M

    2014-03-01

    Minimally invasive treatment of varicose veins by endovenous laser ablation (EVLA) becomes more and more popular. However, despite significant research efforts performed during the last years, there is still a lack of agreement regarding EVLA mechanisms and therapeutic strategies. The aim of this article is to address some of these controversies by utilizing optical-thermal mathematical modeling. Our model combines Mordon's light absorption-based optical-thermal model with the thermal consequences of the thin carbonized blood layer on the laser fiber tip that is heated up to temperatures of around 1,000 °C due to the absorption of about 45% of the laser light. Computations were made in MATLAB. Laser wavelengths included were 810, 840, 940, 980, 1,064, 1,320, 1,470, and 1,950 nm. We addressed (a) the effect of direct light absorption by the vein wall on temperature behavior, comparing computations by using normal and zero wall absorption; (b) the prediction of the influence of wavelength on the temperature behavior; (c) the effect of the hot carbonized blood layer surrounding the fiber tip on temperature behavior, comparing wall temperatures from using a hot fiber tip and one kept at room temperature; (d) the effect of blood emptying the vein, simulated by reducing the inside vein diameter from 3 down to 0.8 mm; (e) the contribution of absorbed light energy to the increase in total energy at the inner vein wall in the time period where the highest inner wall temperature was reached; (f) the effect of laser power and pullback velocity on wall temperature of a 2-mm inner diameter vein, at a power/velocity ratio of 30 J/cm at 1,470 nm; (g) a comparison of model outcomes and clinical findings of EVLA procedures at 810 nm, 11 W, and 1.25 mm/s, and 1,470 nm, 6 W, and 1 mm/s, respectively. Interestingly, our model predicts that the dominating mechanism for heating up the vein wall is not direct absorption of the laser light by the vein wall but, rather, heat flow to the

  8. Structural health monitoring of civil infrastructure using optical fiber sensing technology: a comprehensive review.

    PubMed

    Ye, X W; Su, Y H; Han, J P

    2014-01-01

    In the last two decades, a significant number of innovative sensing systems based on optical fiber sensors have been exploited in the engineering community due to their inherent distinctive advantages such as small size, light weight, immunity to electromagnetic interference (EMI) and corrosion, and embedding capability. A lot of optical fiber sensor-based monitoring systems have been developed for continuous measurement and real-time assessment of diversified engineering structures such as bridges, buildings, tunnels, pipelines, wind turbines, railway infrastructure, and geotechnical structures. The purpose of this review article is devoted to presenting a summary of the basic principles of various optical fiber sensors, innovation in sensing and computational methodologies, development of novel optical fiber sensors, and the practical application status of the optical fiber sensing technology in structural health monitoring (SHM) of civil infrastructure.

  9. Structural Health Monitoring of Civil Infrastructure Using Optical Fiber Sensing Technology: A Comprehensive Review

    PubMed Central

    Ye, X. W.; Su, Y. H.; Han, J. P.

    2014-01-01

    In the last two decades, a significant number of innovative sensing systems based on optical fiber sensors have been exploited in the engineering community due to their inherent distinctive advantages such as small size, light weight, immunity to electromagnetic interference (EMI) and corrosion, and embedding capability. A lot of optical fiber sensor-based monitoring systems have been developed for continuous measurement and real-time assessment of diversified engineering structures such as bridges, buildings, tunnels, pipelines, wind turbines, railway infrastructure, and geotechnical structures. The purpose of this review article is devoted to presenting a summary of the basic principles of various optical fiber sensors, innovation in sensing and computational methodologies, development of novel optical fiber sensors, and the practical application status of the optical fiber sensing technology in structural health monitoring (SHM) of civil infrastructure. PMID:25133250

  10. Pulsed laser manipulation of an optically trapped bead: averaging thermal noise and measuring the pulsed force amplitude.

    PubMed

    Lindballe, Thue B; Kristensen, Martin V G; Berg-Sørensen, Kirstine; Keiding, Søren R; Stapelfeldt, Henrik

    2013-01-28

    An experimental strategy for post-eliminating thermal noise on position measurements of optically trapped particles is presented. Using a nanosecond pulsed laser, synchronized to the detection system, to exert a periodic driving force on an optically trapped 10 μm polystyrene bead, the laser pulse-bead interaction is repeated hundreds of times. Traces with the bead position following the prompt displacement from equilibrium, induced by each laser pulse, are averaged and reveal the underlying deterministic motion of the bead, which is not visible in a single trace due to thermal noise. The motion of the bead is analyzed from the direct time-dependent position measurements and from the power spectrum. The results show that the bead is on average displaced 208 nm from the trap center and exposed to a force amplitude of 71 nanoNewton, more than five orders of magnitude larger than the trapping forces. Our experimental method may have implications for microrheology.

  11. Morphological, thermal and optical studies of jute-reinforced PbSrCaCuO-polypropylene composite

    NASA Astrophysics Data System (ADS)

    Jacob, Reenu; Isac, Jayakumari

    2016-11-01

    New research with modern technologies has always grabbed substantial attention. Conservation of raw materials like natural fibers has helped composite world to explore eco-friendly components. The aim of this paper is to study the potential of jute fiber-reinforced ceramic polymers. Alkali-treated jute fiber has been incorporated in a polypropylene ceramic matrix at different volume fractions. The morphological, thermal and optical studies of jute-reinforced ceramic Pb2Sr2CaCu2O9 (PbSrCaCuO) are studied. Morphological results evidently demonstrate that when the polypropylene ceramic matrix is reinforced with jute fiber, interfacial interaction between the varying proportions of the jute fiber and ceramic composite takes place. TGA and DSC results confirm the enhancement in the thermal stability of ceramic composites reinforced with jute fiber. The UV analysis of the composite gives a good quality measure on the optical properties of the new composite prepared.

  12. Next generation optical instruments and space experiments based on the LDEF thermal control surfaces experiment (S0069)

    NASA Technical Reports Server (NTRS)

    Wilkes, Donald R.

    1992-01-01

    The Thermal Control Surfaces Experiment (TCSE) on the Long Duration Exposure Facility (LDEF) was a very effective experiment to study the effects of the space environment on thermal control surfaces. Three current programs have benefitted from the TCSE experiment and are the: Optical Properties Monitor (OPM); Laboratory Portable Spectroreflectometer (LPSR); and Space Portable Spectroreflectometer. The OPM expands the TCSE optical measurement and environmental monitoring capability. The LPSR is a hand held instrument developed to measure the spectral total hemispherical reflectance of small and larger surfaces in the field. The SPSR is a space application of the LPSR and TCSE technologies with the same measurement capabilities. The SPSR will be able to characterize the external surfaces of operational spacecraft such as Space Station Freedom.

  13. On the Relationship Between Satellite-Estimated Bio-Optical and Thermal Properties in the Gulf of Mexico

    DTIC Science & Technology

    2008-03-15

    photosynthetic pigments in microalgac and cyanobacteria, J. Phycol., Nitrogen input to the Gulf of Mexico, J Environ. Qual., 30, 329- 336. 38, 17-38...and surface pigment concentration, was followed by a thermally stratified period characterized by net surface ocean heating, reduced isothermal layer...to significantly modulate the seasonal bio-optical cycle of CDM absorption and surface pigment concentration. An empirical model was developed to

  14. Using Paraffin PCM to Make Optical Communication Type of Payloads Thermally Self-Sufficient for Operation in Orion Crew Module

    NASA Technical Reports Server (NTRS)

    Choi, Michael K.

    2016-01-01

    An innovative concept of using paraffin phase change material with a melting point of 28 C to make Optical Communication type of payload thermally self-sufficient for operation in the Orion Crew Module is presented. It stores the waste heat of the payload and permits it to operate for about one hour by maintaining its temperature within the maximum operating limit. It overcomes the problem of relying on the availability of cold plate heat sink in the Orion Crew Module.

  15. Variance in radiance recorded from heterogeneous targets in the optical-reflective, middle-infrared, and thermal-infrared regions

    NASA Astrophysics Data System (ADS)

    Duggin, Michael J.

    1986-12-01

    In this paper, the variance in radiance recorded from heterogeneous scenes in the optical-reflective, middle-IR, and thermal-IR regions is considered. The impact of this variance on feature discrimination is considered. Equations are presented, by which the efficacy of standard analytical techniques for given feature mapping tasks may be evaluated using available data. It is also suggested that these equations may be helpful in development of mission-oriented sensors.

  16. Predicting ambient aerosol Thermal Optical Reflectance (TOR) measurements from infrared spectra: organic carbon

    NASA Astrophysics Data System (ADS)

    Dillner, A. M.; Takahama, S.

    2014-11-01

    Organic carbon (OC) can constitute 50% or more of the mass of atmospheric particulate matter. Typically, the organic carbon concentration is measured using thermal methods such as Thermal-Optical Reflectance (TOR) from quartz fiber filters. Here, methods are presented whereby Fourier Transform Infrared (FT-IR) absorbance spectra from polytetrafluoroethylene (PTFE or Teflon) filters are used to accurately predict TOR OC. Transmittance FT-IR analysis is rapid, inexpensive, and non-destructive to the PTFE filters. To develop and test the method, FT-IR absorbance spectra are obtained from 794 samples from seven Interagency Monitoring of PROtected Visual Environment (IMPROVE) sites sampled during 2011. Partial least squares regression is used to calibrate sample FT-IR absorbance spectra to artifact-corrected TOR OC. The FTIR spectra are divided into calibration and test sets by sampling site and date which leads to precise and accurate OC predictions by FT-IR as indicated by high coefficient of determination (R2; 0.96), low bias (0.02 μg m-3, all μg m-3 values based on the nominal IMPROVE sample volume of 32.8 m-3), low error (0.08 μg m-3) and low normalized error (11%). These performance metrics can be achieved with various degrees of spectral pretreatment (e.g., including or excluding substrate contributions to the absorbances) and are comparable in precision and accuracy to collocated TOR measurements. FT-IR spectra are also divided into calibration and test sets by OC mass and by OM / OC which reflects the organic composition of the particulate matter and is obtained from organic functional group composition; this division also leads to precise and accurate OC predictions. Low OC concentrations have higher bias and normalized error due to TOR analytical errors and artifact correction errors, not due to the range of OC mass of the samples in the calibration set. However, samples with low OC mass can be used to predict samples with high OC mass indicating that the

  17. Analytical model of thermal effect and optical path difference in end-pumped Yb:YAG thin disk laser.

    PubMed

    Zhu, Guangzhi; Zhu, Xiao; Wang, Mu; Feng, Yufan; Zhu, Changhong

    2014-10-10

    An analytical model of the thermal effect and optical path difference (OPD) of a thin disk laser is developed with the combination of the analytical method and commercial finite element analysis software. The distributions of temperature, stress, strain, and OPD caused by temperature gradient, axial thermal strain (bulging), thermal strain-induced birefringence, and deformation are obtained. Based on the analytical model, the production mechanisms, features, and influence of OPD in an end-pumped thin disk laser are discussed, which make the causes of spherical and aspherical parts of the OPD more obvious. Furthermore, the OPD including the spherical and aspherical parts of the thin disk crystal is discussed for various pumping intensities.

  18. Wireless Subsurface Sensors for Health Monitoring of Thermal Protection Systems on Hypersonic Vehicles

    NASA Technical Reports Server (NTRS)

    Milos, Frank S.; Arnold, Jim (Technical Monitor)

    2001-01-01

    Health diagnostics is an area where major improvements have been identified for potential implementation into the design of new reusable launch vehicles (RLVs) in order to reduce life cycle costs, to increase safety margins, and to improve mission reliability. NASA Ames is leading the effort to develop inspection and health management technologies for thermal protection systems. This paper summarizes a joint project between NASA Ames and industry partners to develop "wireless" devices that can be embedded in the thermal protection system to monitor temperature or other quantities of interest. These devices are sensors integrated with radio-frequency identification (RFID) microchips to enable non-contact communication of sensor data to an external reader that may be a hand-held scanner or a large portal. Both passive and active prototype devices have been developed. The passive device uses a thermal fuse to indicate the occurrence of excessive temperature. This device has a diameter under 0.13 cm. (suitable for placement in gaps between ceramic TPS tiles on an RLV) and can withstand 370 C for 15 minutes. The active device contains a small battery to provide power to a thermocouple for recording a temperature history during flight. The bulk of the device must be placed beneath the TPS for protection from high temperature, but the thermocouple can be placed in a hot location such as near the external surface.

  19. Structural, optical, and transport properties of nanocrystalline bismuth telluride thin films treated with homogeneous electron beam irradiation and thermal annealing.

    PubMed

    Takashiri, Masayuki; Asai, Yuki; Yamauchi, Kazuki

    2016-08-19

    We investigated the effects of homogeneous electron beam (EB) irradiation and thermal annealing treatments on the structural, optical, and transport properties of bismuth telluride thin films. Bismuth telluride thin films were prepared by an RF magnetron sputtering method at room temperature. After deposition, the films were treated with homogeneous EB irradiation, thermal annealing, or a combination of both the treatments (two-step treatment). We employed Williamson-Hall analysis for separating the strain contribution from the crystallite domain contribution in the x-ray diffraction data of the films. We found that strain was induced in the thin films by EB irradiation and was relieved by thermal annealing. The crystal orientation along c-axis was significantly enhanced by the two-step treatment. Scanning electron microscopy indicated the melting and aggregation of nano-sized grains on the film surface by the two-step treatment. Optical analysis indicated that the interband transition of all the thin films was possibly of the indirect type, and that thermal annealing and two-step treatment methods increased the band gap of the films due to relaxation of the strain. Thermoelectric performance was significantly improved by the two-step treatment. The power factor reached a value of 17.2 μW (cm(-1) K(-2)), approximately 10 times higher than that of the as-deposited thin films. We conclude that improving the crystal orientation and relaxing the strain resulted in enhanced thermoelectric performance.

  20. Effect of position of nitrogen in pyridine ring on structural, optical and thermal properties of chalcone single crystals

    NASA Astrophysics Data System (ADS)

    Menezes, Anthoni Praveen; Jayarama, A.

    2015-06-01

    Crystals are unacknowledged pillars of the world of contemporary technology. Single crystals of a set of three chalcone derivatives, 1-(pyridin-2-yl)-3-(2,4,6-trimethoxyphenyl) prop-2-en-1-one (C1), 1-(pyridin-3-yl)-3-(2,4,6-trimethoxyphenyl) prop-2-en-1-one (C2) and 1-(pyridin-4-yl)-3-(2,4,6-trimethoxyphenyl) prop-2-en-1-one (C3) were grown by slow evaporation technique. The thermal analysis reveals that the chalcone derivatives possess good thermal and chemical stability. Crystal C1 is nonlinear optically (NLO) active with SHG efficiency of 0.7 times that of KDP. The position of nitrogen in the pyridine ring has a significant effect on thermal, structural and NLO properties of these materials. The UV-Visible spectrum discloses that the crystals have adequate transmission in the entire visible region. Due to good thermal stability, optical transparency and SHG response, crystal C1 is an useful candidate for NLO applications such as frequency doubling down to 433 nm.

  1. Theoretical and experimental on the Shupe-like bias caused by thermal stress of fiber optic gyros

    NASA Astrophysics Data System (ADS)

    Wang, Yueze; Ma, Lin; Zhao, Jingjing; Wu, Wei; Qiao, Liwei

    2016-10-01

    The fiber optic gyroscope has became to one of the most important sensors in developing due to light in quality, high accuracy, compact in dimension and long life and has played a very important role in both military and civil use. The fiber coil, as one of the most critical components in FOG, is extremely sensitive to changes in temperature. In this paper, at first, by studying the thermal stress of fiber optic gyros, the element model of the fiber coil was built based on the discrete mathematics formulae of Shupe error in FOG. Then based on the temperature distribution model mentioned above, the effects of the Shupe-like bias caused by thermal stress and the Shupe bias caused by temperature gradient are simulated. A turn-by-turn quantization bias error model is established. Theoretical analysis and experimental results show the Shupe-like bias caused by thermal stress and the Shupe bias caused by temperature gradient had seriously affected the temperature performance of FOG. By optimizing the winding method of fiber coil, the Shupe error of fiber coils can be reduced. At the same time, Shupe-like bias caused by thermal stress can be reduced too.

  2. Surface temperature measurement by optical self-interference of laser beam at the edge of a thermally sensitive thin film

    NASA Astrophysics Data System (ADS)

    Do, Phuong; Touabia, Mohamed; Hache, Alain

    2013-03-01

    Measurement of surface temperature is problematic when the thermal mass of the probe (e.g. thermocouple or thermometer) is large relative to that of the sampled volume (e.g. thin film). With the goal of reducing thermal mass error, we developed a method using thermal probes in the form of thin films with materials exhibiting large physical and optical changes with temperature. Using chitosan, a polymer, as test material, we show that thermal expansion and refractive index changes in the film are detectable optically with a laser beam. When half of the Gaussian-shaped beam travels through the edge of the film and half of it does not, self-interference in the form of a fringe pattern is observed in the far field. With the fringe displacement correlated to phase variations and temperature changes, the calibration can be used to probe surface temperature on other samples. With the laser beam focused to 50 μm and chitosan films as thin as 100 nm, the method is adequate to measure temperature in the near vicinity of the surface. We provide a theory and numerical simulations to determine the ideal experimental conditions and parameters.

  3. Structural, optical, and transport properties of nanocrystalline bismuth telluride thin films treated with homogeneous electron beam irradiation and thermal annealing

    NASA Astrophysics Data System (ADS)

    Takashiri, Masayuki; Asai, Yuki; Yamauchi, Kazuki

    2016-08-01

    We investigated the effects of homogeneous electron beam (EB) irradiation and thermal annealing treatments on the structural, optical, and transport properties of bismuth telluride thin films. Bismuth telluride thin films were prepared by an RF magnetron sputtering method at room temperature. After deposition, the films were treated with homogeneous EB irradiation, thermal annealing, or a combination of both the treatments (two-step treatment). We employed Williamson-Hall analysis for separating the strain contribution from the crystallite domain contribution in the x-ray diffraction data of the films. We found that strain was induced in the thin films by EB irradiation and was relieved by thermal annealing. The crystal orientation along c-axis was significantly enhanced by the two-step treatment. Scanning electron microscopy indicated the melting and aggregation of nano-sized grains on the film surface by the two-step treatment. Optical analysis indicated that the interband transition of all the thin films was possibly of the indirect type, and that thermal annealing and two-step treatment methods increased the band gap of the films due to relaxation of the strain. Thermoelectric performance was significantly improved by the two-step treatment. The power factor reached a value of 17.2 μW (cm-1 K-2), approximately 10 times higher than that of the as-deposited thin films. We conclude that improving the crystal orientation and relaxing the strain resulted in enhanced thermoelectric performance.

  4. Study of spectral characteristics of radiation from a thermal wake of a pulsating optical discharge in a supersonic air flow

    SciTech Connect

    Malov, A N; Orishich, A M; Terent'eva, Ya S

    2015-10-31

    The spectral characteristics of the thermal wake of a pulsating optical discharge (POD) in a supersonic air flow are studied. The POD is stimulated by radiation of a mechanically Q-switched, repetitively pulsed CO{sub 2} laser with a pulse repetition rate of 7 – 150 kHz and a power up to 4.5 kW. The flow is produced by means of the supersonic aerodynamic MAU-M setup having a conic nozzle with a critical cross-section size of 50 mm, the Mach number being 1.3 – 1.6. We describe in detail the system of optical diagnostics that allows the detection of the spectrum of the weak thermal wake glow against the background of high-power POD radiation. The glow of the thermal wake is due to the emission of light by atoms and ions of nitrogen and oxygen, carried by the flow in the form of hot low-density gas clouds (caverns). The wavelengths of the thermal wake emission and the data on the transitions, corresponding to the spectral lines are presented. (laser applications and other topics in quantum electronics)

  5. Optical properties of normal and thermally coagulated chicken liver tissue measured ex-vivo with diffuse reflectance

    NASA Astrophysics Data System (ADS)

    Hafeez-Ullah; Atif, M.; Firdous, S.; Mehmood, M. S.; Hamza, M. Y.; Imran, M.; Hussain, G.; Ikram, M.

    2011-02-01

    The purpose of the present study is to determine the optical properties of normal and thermally coagulated chicken liver at 720, 740, 770, 810, 825 and 840 nm wavelengths of laser irradiation. So, we were able to evaluate these optical properties (absorption and scattering coefficients) with ex-vivo study using Kubelka Munk Model (KMM) from the radial dependence of the diffuse reflectance with femtosecond pulsed laser in near IR region. These coefficients were significantly increased with coagulation. The penetration depths of the diffused light have been reported to a maximum value of 8.12 ± 0.36 mm in normal liver and 2.49 ± 0.17 mm in coagulated liver at 840 nm showing increasing behavior towards IR region. The Monte Carlo simulation was used to check the theoretical validation of measured optical properties of the tissue that showed a good match with our experimental results. We believe that these differences in optical properties will be helpful for the understanding arid optimal use of laser applications in medicine and differential diagnosis of tissues by using different optical methods. Especially for the investigation of biological tissue for photodynamic therapy (PDT), the knowledge of the specific optical properties and their thermo-induced changes is important.

  6. A practical algorithm for estimating surface soil moisture using combined optical and thermal infrared data

    NASA Astrophysics Data System (ADS)

    Leng, Pei; Song, Xiaoning; Duan, Si-Bo; Li, Zhao-Liang

    2016-10-01

    Surface soil moisture (SSM) is a critical variable for understanding the energy and water exchange between the land and atmosphere. A multi-linear model was recently developed to determine SSM using ellipse variables, namely, the center horizontal coordinate (x0), center vertical coordinate (y0), semi-major axis (a) and rotation angle (θ), derived from the elliptical relationship between diurnal cycles of land surface temperature (LST) and net surface shortwave radiation (NSSR). However, the multi-linear model has a major disadvantage. The model coefficients are calculated based on simulated data produced by a land surface model simulation that requires sufficient meteorological measurements. This study aims to determine the model coefficients directly using limited meteorological parameters rather than via the complicated simulation process, decreasing the dependence of the model coefficients on meteorological measurements. With the simulated data, a practical algorithm was developed to estimate SSM based on combined optical and thermal infrared data. The results suggest that the proposed approach can be used to determine the coefficients associated with all ellipse variables based on historical meteorological records, whereas the constant term varies daily and can only be determined using the daily maximum solar radiation in a prediction model. Simulated results from three FLUXNET sites over 30 cloud-free days revealed an average root mean square error (RMSE) of 0.042 m3/m3 when historical meteorological records were used to synchronously determine the model coefficients. In addition, estimated SSM values exhibited generally moderate accuracies (coefficient of determination R2 = 0.395, RMSE = 0.061 m3/m3) compared to SSM measurements at the Yucheng Comprehensive Experimental Station.

  7. Structural, optical, opto-thermal and thermal properties of ZnS–PVA nanofluids synthesized through a radiolytic approach

    PubMed Central

    Faraji, Nastaran; Mat Hussin, Roslina; Saion, Elias; Yunus, W Mahmood Mat; Behzad, Kasra

    2015-01-01

    Summary This work describes a fast, clean and low-cost approach to synthesize ZnS–PVA nanofluids consisting of ZnS nanoparticles homogeneously distributed in a PVA solution. The ZnS nanoparticles were formed by the electrostatic force between zinc and sulfur ions induced by gamma irradiation at a dose range from 10 to 50 kGy. Several experimental characterizations were conducted to investigate the physical and chemical properties of the samples. Fourier transform infrared spectroscopy (FTIR) was used to determine the chemical structure and bonding conditions of the final products, transmission electron microscopy (TEM) for determining the shape morphology and average particle size, powder X-ray diffraction (XRD) for confirming the formation and crystalline structure of ZnS nanoparticles, UV–visible spectroscopy for measuring the electronic absorption characteristics, transient hot wire (THW) and photoacoustic measurements for measuring the thermal conductivity and thermal effusivity of the samples, from which, for the first time, the values of specific heat and thermal diffusivity of the samples were then calculated. PMID:25821695

  8. Modifying optical properties of reduced/graphene oxide with controlled ozone and thermal treatment in aqueous suspensions

    NASA Astrophysics Data System (ADS)

    Tanvir Hasan, Md; Senger, Brian J.; Mulford, Price; Ryan, Conor; Doan, Hung; Gryczynski, Zygmunt; Naumov, Anton V.

    2017-02-01

    Graphene possesses a number of advantageous properties, however, does not exhibit optical emission, which limits its use in optoelectronics. Unlike graphene, its functional derivative, graphene oxide (GO) exhibits fluorescence emission throughout the visible. Here, we focus on controlled methods for tuning the optical properties of GO. We introduce ozone treatment of reduced graphene oxide (RGO) in order to controllably transform it from non-emissive graphene-like material into GO with a specific fluorescence emission response. Solution-based treatment of RGO for 5-45 min with ˜1.2 g l-1 ozone/oxygen gas mixture yields a drastic color change, bleaching of the absorption in the visible and the stepwise increase in fluorescence intensity and lifetime. This is attributed to the introduction of oxygen-containing functional groups to RGO graphitic platform as detected by the infrared spectroscopy. A reverse process: controllable quenching of this fluorescence is achieved by the thermal treatment of GO in aqueous suspension up to 90 °C. This methodology allows for the wide range alteration of GO optical properties starting from the dark-colored non-emissive RGO material up to nearly transparent highly ozone-oxidized GO showing substantial fluorescence emission. The size of the GO flakes is concomitantly altered by oxidation-induced scission. Semi-empirical PM3 theoretical calculations on HyperChem models are utilized to explore the origins of optical response from GO. Two models are considered, attributing the induced emission either to the localized states produced by oxygen-containing addends or the islands of graphitic carbon enclosed by such addends. Band gap values calculated from the models are in the agreement with experimentally observed transition peak maxima. The controllable variation of GO optical properties in aqueous suspension by ozone and thermal treatments shown in this work provides a route to tune its optical response for particular optoelectronics

  9. Modifying optical properties of reduced/graphene oxide with controlled ozone and thermal treatment in aqueous suspensions.

    PubMed

    Hasan, Md Tanvir; Senger, Brian J; Mulford, Price; Ryan, Conor; Doan, Hung; Gryczynski, Zygmunt; Naumov, Anton V

    2017-02-10

    Graphene possesses a number of advantageous properties, however, does not exhibit optical emission, which limits its use in optoelectronics. Unlike graphene, its functional derivative, graphene oxide (GO) exhibits fluorescence emission throughout the visible. Here, we focus on controlled methods for tuning the optical properties of GO. We introduce ozone treatment of reduced graphene oxide (RGO) in order to controllably transform it from non-emissive graphene-like material into GO with a specific fluorescence emission response. Solution-based treatment of RGO for 5-45 min with ∼1.2 g l(-1) ozone/oxygen gas mixture yields a drastic color change, bleaching of the absorption in the visible and the stepwise increase in fluorescence intensity and lifetime. This is attributed to the introduction of oxygen-containing functional groups to RGO graphitic platform as detected by the infrared spectroscopy. A reverse process: controllable quenching of this fluorescence is achieved by the thermal treatment of GO in aqueous suspension up to 90 °C. This methodology allows for the wide range alteration of GO optical properties starting from the dark-colored non-emissive RGO material up to nearly transparent highly ozone-oxidized GO showing substantial fluorescence emission. The size of the GO flakes is concomitantly altered by oxidation-induced scission. Semi-empirical PM3 theoretical calculations on HyperChem models are utilized to explore the origins of optical response from GO. Two models are considered, attributing the induced emission either to the localized states produced by oxygen-containing addends or the islands of graphitic carbon enclosed by such addends. Band gap values calculated from the models are in the agreement with experimentally observed transition peak maxima. The controllable variation of GO optical properties in aqueous suspension by ozone and thermal treatments shown in this work provides a route to tune its optical response for particular

  10. Luminescence-Based Diagnostics of Thermal Barrier Coating Health and Performance

    NASA Technical Reports Server (NTRS)

    Eldridge, Jeffrey I.

    2013-01-01

    Thermal barrier coatings (TBCs) are typically composed of translucent ceramic oxides that provide thermal protection for metallic components exposed to high-temperature environments in both air- and land-based turbine engines. For advanced turbine engines designed for higher temperature operation, a diagnostic capability for the health and performance of TBCs will be essential to indicate when a mitigating action needs to be taken before premature TBC failure threatens engine performance or safety. In particular, it is shown that rare-earth-doped luminescent sublayers can be integrated into the TBC structure to produce luminescence emission that can be monitored to assess TBC erosion and delamination progression, and to map surface and subsurface temperatures as a measure of TBC performance. The design and implementation of these TBCs with integrated luminescent sublayers are presented.

  11. Analysis of the Effects of Thermal Environment on Optical Systems for Navigation Guidance and Control in Supersonic Aircraft Based on Empirical Equations.

    PubMed

    Cheng, Xuemin; Yang, Yikang; Hao, Qun

    2016-10-17

    The thermal environment is an important factor in the design of optical systems. This study investigated the thermal analysis technology of optical systems for navigation guidance and control in supersonic aircraft by developing empirical equations for the front temperature gradient and rear thermal diffusion distance, and for basic factors such as flying parameters and the structure of the optical system. Finite element analysis (FEA) was used to study the relationship between flying and front dome parameters and the system temperature field. Systematic deduction was then conducted based on the effects of the temperature field on the physical geometry and ray tracing performance of the front dome and rear optical lenses, by deriving the relational expressions between the system temperature field and the spot size and positioning precision of the rear optical lens. The optical systems used for navigation guidance and control in supersonic aircraft when the flight speed is in the range of 1-5 Ma were analysed using the derived equations. Using this new method it was possible to control the precision within 10% when considering the light spot received by the four-quadrant detector, and computation time was reduced compared with the traditional method of separately analysing the temperature field of the front dome and rear optical lens using FEA. Thus, the method can effectively increase the efficiency of parameter analysis and computation in an airborne optical system, facilitating the systematic, effective and integrated thermal analysis of airborne optical systems for navigation guidance and control.

  12. Analysis of the Effects of Thermal Environment on Optical Systems for Navigation Guidance and Control in Supersonic Aircraft Based on Empirical Equations

    PubMed Central

    Cheng, Xuemin; Yang, Yikang; Hao, Qun

    2016-01-01

    The thermal environment is an important factor in the design of optical systems. This study investigated the thermal analysis technology of optical systems for navigation guidance and control in supersonic aircraft by developing empirical equations for the front temperature gradient and rear thermal diffusion distance, and for basic factors such as flying parameters and the structure of the optical system. Finite element analysis (FEA) was used to study the relationship between flying and front dome parameters and the system temperature field. Systematic deduction was then conducted based on the effects of the temperature field on the physical geometry and ray tracing performance of the front dome and rear optical lenses, by deriving the relational expressions between the system temperature field and the spot size and positioning precision of the rear optical lens. The optical systems used for navigation guidance and control in supersonic aircraft when the flight speed is in the range of 1–5 Ma were analysed using the derived equations. Using this new method it was possible to control the precision within 10% when considering the light spot received by the four-quadrant detector, and computation time was reduced compared with the traditional method of separately analysing the temperature field of the front dome and rear optical lens using FEA. Thus, the method can effectively increase the efficiency of parameter analysis and computation in an airborne optical system, facilitating the systematic, effective and integrated thermal analysis of airborne optical systems for navigation guidance and control. PMID:27763515

  13. Thermal optical path difference analysis of off-axis lens ray trace foot-print at Cassegrain telescope correct lens assembly

    NASA Astrophysics Data System (ADS)

    Hsu, Ming-Ying; Lin, Yu-Chuan; Chan, Chia-Yen; Lin, Wei-Cheng; Chan, Shenq-Tsong; Huang, Ting-Ming

    2012-10-01

    The Cassegrain telescope system in this study, is discussion correct lens thermal OPD (Optical Path Difference) effect optical performance. The correct lens assembly are includes several components such as correct lens, lens mount, spacer, mount barrel and retainer. The heat transfer from surrounding to the correct lens barrel will causes optical system aberration. Meanwhile, the off-axis rays path of the OPD must consider lens incidence point and emergence point. The correct lens temperature distribution is calculate the lens barrel heat transfer analysis, the thermal distortion and stress are solve by FEM (Finite Element Method) software. The temperature calculation results can be weighting to each incidence ray path and calculate thermal OPD. The thermal OPD on Z-direction can be fitted by rigid body motion and Zernike polynomial. The fitting results can be used to evaluate the thermal effect on correct lens assembly in telescope system.

  14. Phase matching, X-Ray topography, optical and thermal analysis of L-alanine cadmium chloride monohydrate: a nonlinear optical material

    NASA Astrophysics Data System (ADS)

    Krishna, Anuj; Vijayan, N.; Riscob, B.; Gour, B. S.; Haranath, D.; Philip, J.; Verma, S.; Jayalakshmy, M. S.; Bhagavannarayana, G.; Halder, S. K.

    2014-03-01

    A potential semiorganic nonlinear optical material, L-alanine cadmium chloride monohydrate has been successfully synthesised and single crystals have been grown by slow evaporation solution growth technique at room temperature by using double distilled water as the solvent. The lattice dimensions of the grown crystal have been analysed by adopting powder X-ray diffraction technique and found that it crystallised in monoclinic system with space group C2. The crystalline perfection of the as-grown crystal has been assessed by high resolution X-ray diffraction and X-ray topography techniques and observed that the quality of the grown specimen is reasonably good. Its optical properties were examined by UV-Vis and photoluminescence techniques and found that there is no absorption in the entire visible range. Its functional groups were identified from FT-Raman and observed that there is no incorporation of other impurities during crystallisation. Its relative second harmonic generation efficiency has been tested with different particle size by Kurtz powder technique and found that within the coherence length the title compound is phase matchable. Its various thermal properties like thermal conductivity, specific heat, thermal effusivity, etc. have been evaluated by photopyroelectric technique and compared with other organic and inorganic materials. To confirm its piezoelectric response, its piezoelectric charge coefficient was measured using piezometer and found low. Its optical homogeneity as well as birefringence measurement of the grown specimen has been carried out by interferometric technique. The surface defects of the grown LACCM single crystal were analysed with etching at room temperature using water as an etchant.

  15. Structural, thermal and optical characterization of a Schiff base as a new organic material for nonlinear optical crystals and films with reversible noncentrosymmetry.

    PubMed

    Rodríguez, Mario; Ramos-Ortíz, Gabriel; Maldonado, José Luis; Herrera-Ambriz, Víctor M; Domínguez, Oscar; Santillan, Rosa; Farfán, Norberto; Nakatani, Keitaro

    2011-09-01

    Macroscopic single crystals of (E)-5-(diethylamino)-2-((3,5-dinitrophenylimino)methyl)phenol (DNP) were obtained from slow cooling of chloroform or dichlorometane saturated solutions at controlled temperature. X-ray diffraction analysis showed that this compound crystallizes in a noncentrosymmetric space group (P2(1)2(1)2(1)). Thermal analysis was performed and indicated that the crystals are stable until 260 °C. Second-order nonlinear optical properties of DNP were experimentally investigated in solution through EFISH technique and in solid state through the Kurtz-Perry powder technique. Crystals of compound DNP exhibited a second-harmonic signals 39 times larger than of the technologically useful potassium dihydrogenphosphate (KDP) under excitation at infrared wavelengths. In addition, the second-order nonlinear optical properties of DNP were also studied at visible wavelengths through the photorefractive effect and applied to demonstrate dynamic holographic reconstruction.

  16. Effect of thermal treatments on third-order nonlinear optical properties of hollow Cu nanoclusters

    NASA Astrophysics Data System (ADS)

    Wang, Y. H.; Jiang, C. Z.; Ren, F.; Wang, Q. Q.; Chen, D. J.; Fu, D. J.

    2006-06-01

    Metal nanocluster composites prepared by Cu ion implantation have been studied. The formation of nanoclusters has been evidenced by optical absorption spectra and transmission electron microscopy (TEM). Fast nonlinear optical refraction and nonlinear optical absorption coefficients were measured at 790 nm for Cu nanocluster composites by the Z-scan technique. With the increase of annealing temperature, the size of nanoclusters increased significantly, and optical nonlinearities was enhanced. It is suggested that by changing the ingredient configuration of metal nanoclusters in silica, different optical nonlinear properties could be selectively obtained.

  17. Optical and thermal testing of convection reduction mechanisms in a new 1.2X CPC solar collector

    NASA Astrophysics Data System (ADS)

    Carvalho, Maria J.; Collares-Pereira, Manuel; de Oliveira, Joao C.; Mendes, Joao F.; Haeberle, A.; Wittwer, Volker

    1994-09-01

    A new non-evacuated solar collector of the CPC type, developed and manufactured in Portugal, is now commercially available. Its design features are unique and deserve a careful study, both of its optical and of its thermal characteristics. The optics is interesting given the unusual shape and the opportunity to test different convection suppression schemes and determine their impacts on the collector's optical performance. As for the collector's thermal behavior it is very interesting to test how simple (and potential marketable) different convection suppression ideas can improve an already very good collector from the heat loss point of view (FUL equals 4.0 W/( degree(s)C.m2)). In the course of the paper a brief description of the collector is given and testing results are presented for the testing carried out in the following situations: (1) (i) measurement of its optical and thermal performance (instantaneous efficiency curve) measured both in E.W. and N.S. collector orientation (the collector has a very wide acceptance angle allowing it to work in N.S. orientation and, thus, function in a thermosyphon mode like any regular flat plate collector, (ii) measurement of its angular acceptance function; (2) measurement of the instantaneous efficiency curve after the introduction of (i) a thin Teflon high transmissivity film below the glass cover, (ii) transparent insulation of the capillary type, inserted also under the glass cover, (iii) measurement of the acceptance angle function in this last situation. In this paper it is shown that the addition of the film reduces the heat loss coefficient by a factor of 1.3 W/( degree(s)C.m2) and the transparent insulation leads only to an improvement of 1.0 W/( degree(s)C.m2) in that same coefficient.

  18. Temperature calibration of fiber optic strain sensor for structural health monitoring

    NASA Astrophysics Data System (ADS)

    Kesavan, K.; Ravisankar, K.; Narayanan, T.; Parivallal, S.; Sreeshylam, P.; Aravindan, P. K.

    2003-10-01

    Major civil engineering structures, such as bridges constitute a significant portion of national wealth, and the cost of maintenance of these structures is very high. Structural health monitoring is a cost effective method of maintenance, and it predicts the structural integrity by early detection of degradation of health of the structure. One of the best ways of structural health monitoring is by the use of fiber optic strain sensors, which are eminently suitable for long term monitoring. However, the apparent strain due to variations in temperature at different measurement times may be very large and has to be accounted for. The apparent strain calibration curves of fiber optic strain sensors bonded to three structural materials, namely, steel, aluminum and concrete are obtained from laboratory experiments which can be used for correcting the temperature induced apparent strain from the total strain measured in the structures.

  19. THE OPTIMIZATION OF THERMAL OPTICAL ANALYSIS FOR THE MEASUREMENT OF BLACK CARBON IN REGIONAL PM2.5: A CHEMOMETRIC APPROACH REPORT

    EPA Science Inventory

    In thermal-optical analysis (TOA), particulate organic carbon (OC) as well as black carbon (BC) must be quantified. Both the BC that is native to the filter and instrument-produced OC char are products of incomplete combustion and have similar optical as well as chemical properti...

  20. Predicting ambient aerosol thermal-optical reflectance (TOR) measurements from infrared spectra: organic carbon

    NASA Astrophysics Data System (ADS)

    Dillner, A. M.; Takahama, S.

    2015-03-01

    Organic carbon (OC) can constitute 50% or more of the mass of atmospheric particulate matter. Typically, organic carbon is measured from a quartz fiber filter that has been exposed to a volume of ambient air and analyzed using thermal methods such as thermal-optical reflectance (TOR). Here, methods are presented that show the feasibility of using Fourier transform infrared (FT-IR) absorbance spectra from polytetrafluoroethylene (PTFE or Teflon) filters to accurately predict TOR OC. This work marks an initial step in proposing a method that can reduce the operating costs of large air quality monitoring networks with an inexpensive, non-destructive analysis technique using routinely collected PTFE filter samples which, in addition to OC concentrations, can concurrently provide information regarding the composition of organic aerosol. This feasibility study suggests that the minimum detection limit and errors (or uncertainty) of FT-IR predictions are on par with TOR OC such that evaluation of long-term trends and epidemiological studies would not be significantly impacted. To develop and test the method, FT-IR absorbance spectra are obtained from 794 samples from seven Interagency Monitoring of PROtected Visual Environment (IMPROVE) sites collected during 2011. Partial least-squares regression is used to calibrate sample FT-IR absorbance spectra to TOR OC. The FTIR spectra are divided into calibration and test sets by sampling site and date. The calibration produces precise and accurate TOR OC predictions of the test set samples by FT-IR as indicated by high coefficient of variation (R2; 0.96), low bias (0.02 μg m-3, the nominal IMPROVE sample volume is 32.8 m3), low error (0.08 μg m-3) and low normalized error (11%). These performance metrics can be achieved with various degrees of spectral pretreatment (e.g., including or excluding substrate contributions to the absorbances) and are comparable in precision to collocated TOR measurements. FT-IR spectra are also

  1. Optic phonon bandwidth and lattice thermal conductivity: The case of Li2X ( X=O , S, Se, Te)

    DOE PAGES

    Mukhopadhyay, S.; Lindsay, L.; Parker, D. S.

    2016-06-07

    Here, we examine the lattice thermal conductivities ( l) of Li2X (X=O, S, Se, Te) using a first-principles Peierls-Boltzmann transport methodology. We find low l values ranging between 12 and 30 W/m-K despite light Li atoms, a large mass difference between constituent atoms and tightly bunched acoustic branches, all features that give high l in other materials including BeSe (630 W/m-1K-1), BeTe (370 W/m-1K-1) and cubic BAs (3150 W/m-1K-1). Together these results suggest a missing ingredient in the basic guidelines commonly used to understand and predict l. Unlike typical simple systems (e.g., Si, GaAs, SiC), the dominant resistance to heat-carryingmore » acoustic phonons in Li2Se and Li2Te comes from interactions of these modes with two optic phonons. These interactions require significant bandwidth and dispersion of the optic branches, both present in Li2X materials. Finally, these considerations are important for the discovery and design of new materials for thermal management applications, and give a more comprehensive understanding of thermal transport in crystalline solids.« less

  2. "METHOD": A tool for mechanical, electrical, thermal, and optical characterization of single lens module design

    NASA Astrophysics Data System (ADS)

    Besson, Pierre; Dominguez, Cesar; Voarino, Philippe; Garcia-Linares, Pablo; Weick, Clement; Lemiti, Mustapha; Baudrit, Mathieu

    2015-09-01

    The optical characterization and electrical performance evaluation are essential in the design and optimization of a concentrator photovoltaic system. The geometry, materials, and size of concentrator optics are diverse and different environmental conditions impact their performance. CEA has developed a new concentrator photovoltaic system characterization bench, METHOD, which enables multi-physics optimization studies. The lens and cell temperatures are controlled independently with the METHOD to study their isolated effects on the electrical and optical performance of the system. These influences can be studied in terms of their effect on optical efficiency, focal distance, spectral sensitivity, electrical efficiency, or cell current matching. Furthermore, the irradiance map of a concentrator optic can be mapped to study its variations versus the focal length or the lens temperature. The present work shows this application to analyze the performance of a Fresnel lens linking temperature to optical and electrical performance.

  3. Principles for new optical techniques in medical diagnostics for mHealth applications

    NASA Astrophysics Data System (ADS)

    Balsam, Joshua Michael

    Medical diagnostics is a critical element of effective medical treatment. However, many modern and emerging diagnostic technologies are not affordable or compatible with the needs and conditions found in low-income and middle-income countries and regions. Resource-poor areas require low-cost, robust, easy-to-use, and portable diagnostics devices compatible with telemedicine (i.e. mHealth) that can be adapted to meet diverse medical needs. Many suitable devices will need to be based on optical technologies, which are used for many types of biological analyses. This dissertation describes the fabrication and detection principles for several low-cost optical technologies for mHealth applications including: (1) a webcam based multi-wavelength fluorescence plate reader, (2) a lens-free optical detector used for the detection of Botulinum A neurotoxin activity, (3) a low cost micro-array reader that allows the performance of typical fluorescence based assays demonstrated for the detection of the toxin staphylococcal enterotoxin (SEB), and (4) a wide-field flow cytometer for high throughput detection of fluorescently labeled rare cells. This dissertation discusses how these technologies can be harnessed using readily available consumer electronics components such as webcams, cell phones, CCD cameras, LEDs, and laser diodes. There are challenges in developing devices with sufficient sensitivity and specificity, and approaches are presented to overcoming these challenges to create optical detectors that can serve as low cost medical diagnostics in resource-poor settings for mHealth.

  4. Health monitoring of electric power communication line using a distributed optical fiber sensor

    NASA Astrophysics Data System (ADS)

    Lu, Lidong; Liang, Yun; Li, Binglin; Guo, Jinghong; Zhang, Hao; Zhang, Xuping

    2014-11-01

    Optical fiber ground wire (OPGW) is used for both the earth line and communication line in electric power systems. It is important to find an effective to monitor the status of OPGW and diagnose some possible damages. Fault location of the optical fiber transmission line, lightning stroke location and early-warning of ice covering of OPGW are common tasks for OPGW health monitoring and maintenance. As to these issues, Brillouin optical time domain reflectometry (BOTDR) is employed for the health monitoring of OPGW. In experiment, a positive electrode with high pulsed current and a negative electrode are adopted to form a lightning impulse system with duration time of 200ms for simulation of the lightning stroke process, and a tensile force loading apparatus is also constructed to simulate the strain influence of the ice covering on the OPGW. Experimental results demonstrate that the BOTDR can sensitively locate the lightning stroke incidents with the quantity of electric discharging larger than 100C and the strain component has little interference on temperature monitoring as the fiber contained in the OPGW is generally free of strain, and in the ice covering condition the strain feature appears only when the extra tensile force on the OPGW is over 30kN. In addition, the vibration of OPGW does not disturb both the temperature and strain monitoring. As to further applications of distributed optical fiber sensors (DOFS) for the OPGW health monitoring, it is important to enhance its spatial resolution.

  5. Determination of elemental carbon in lake sediments using a thermal-optical transmittance (TOT) method

    NASA Astrophysics Data System (ADS)

    Khan, A. J.; Swami, Kamal; Ahmed, Tanveer; Bari, A.; Shareef, Akhtar; Husain, Liaquat

    2009-12-01

    An improved chemical oxidation pretreatment method has been developed for the determination of elemental carbon (EC) [also known as black carbon (BC) or soot] in lake sediments, using a thermal-optical transmittance (TOT) carbon analyzer. The method employs six steps: (1) removal of carbonates by treatment with HCl; (2) removal of silicates by treatment with HF + HCl; (3) removal of any remaining carbonates by treatment with HCl; (4) removal of humic acids by treatment with NaOH; and (5) oxidation of kerogens by K 2Cr 2O 7 + H 2SO 4. A critical step of zinc chloride treatment was added; this apparently changes EC's morphology and enhances retention on quartz fiber filter, resulting in several-fold increased chemical yield. EC was determined using the TOT method with modified combustion timings. Carbon black (acetylene) and four NIST standard reference materials (SRMs) were used for quality control, and to assess the precision of the analysis. The EC recoveries from 18 carbon black samples varied from 90 to 111%, with a mean value of 99 ± 6%. The high EC recoveries confirmed the validity of the method. Char reference materials (i.e. chestnut wood and grass char) were used to determine potential contribution to EC in our measurements. The char references containing about 700 mg total organic carbon (OC) contributed ˜1.5% EC. The measured EC values from four NIST standards were 17.0 ± 0.6, 24.2 ± 3.2, 5.6, and 1.9 ± 0.1 mg g dw-1 for SRM-1648, SRM-1649a, SRM-1941b and SRM-8704, respectively. These values in SRMs were in agreement (<±4%) with the previously reported values. The method was applied to determine the EC in sediment cores from an urban lake and a remote mountain lake in the Northeastern United States. The EC concentrations in two lakes mimic the model EC emissions from the industrial revolution in United States.

  6. Effect of cantilever geometry on the optical lever sensitivities and thermal noise method of the atomic force microscope

    SciTech Connect

    Sader, John E.; Lu, Jianing; Mulvaney, Paul

    2014-11-15

    Calibration of the optical lever sensitivities of atomic force microscope (AFM) cantilevers is especially important for determining the force in AFM measurements. These sensitivities depend critically on the cantilever mode used and are known to differ for static and dynamic measurements. Here, we calculate the ratio of the dynamic and static sensitivities for several common AFM cantilevers, whose shapes vary considerably, and experimentally verify these results. The dynamic-to-static optical lever sensitivity ratio is found to range from 1.09 to 1.41 for the cantilevers studied – in stark contrast to the constant value of 1.09 used widely in current calibration studies. This analysis shows that accuracy of the thermal noise method for the static spring constant is strongly dependent on cantilever geometry – neglect of these dynamic-to-static factors can induce errors exceeding 100%. We also discuss a simple experimental approach to non-invasively and simultaneously determine the dynamic and static spring constants and optical lever sensitivities of cantilevers of arbitrary shape, which is applicable to all AFM platforms that have the thermal noise method for spring constant calibration.

  7. The influence of temperature calibration on the OC-EC results from a dual optics thermal carbon analyzer

    NASA Astrophysics Data System (ADS)

    Pavlovic, J.; Kinsey, J. S.; Hays, M. D.

    2014-04-01

    Thermal-optical analysis (TOA) is a widely used technique that fractionates carbonaceous aerosol particles into organic and elemental carbon (OC and EC), or carbonate. Thermal sub-fractions of evolved OC and EC are also used for source identification and apportionment; thus, oven temperature accuracy during TOA analysis is essential. Evidence now indicates that the "actual" sample (filter) temperature and the temperature measured by the built-in oven thermocouple (or set-point temperature) can differ by as much as 50 °C. This difference can affect the OC-EC split point selection and consequently the OC and EC fraction and sub-fraction concentrations being reported, depending on the sample composition and in-use TOA method and instrument. The present study systematically investigates the influence of an oven temperature calibration procedure for TOA. A dual-optical carbon analyzer that simultaneously measures transmission and reflectance (TOT and TOR) is used, functioning under the conditions of both the NIOSH 5040 and IMPROVE protocols. Application of the oven calibration procedure to our dual optics instrument significantly changed NIOSH 5040 carbon fractions (OC and EC) and the IMPROVE OC fraction. In addition, the well-known OC-EC split difference between NIOSH and IMPROVE methods is even further perturbed following the instrument calibration. Further study is needed to determine if the wide-spread application of this oven temperature calibration procedure will indeed improve accuracy and our ability to compare among carbonaceous aerosol studies that use TOA.

  8. Study of the thermal distribution in vocal cords irradiated by an optical source for the treatment of voice disabilities

    NASA Astrophysics Data System (ADS)

    Arce-Diego, José L.; Fanjul-Vélez, Félix; Borragán-Torre, Alfonso

    2006-02-01

    Vocal cords disorders constitute an important problem for people suffering from them. Particularly the reduction of mucosal wave movement is not appropriately treated by conventional therapies, like drugs administration or surgery. In this work, an alternative therapy, consisting in controlled temperature increases by means of optical sources is proposed. The distribution of heat inside vocal cords when an optical source illuminates them is studied. Optical and thermal properties of tissue are discussed, as a basis for the appropriate knowledge of its behaviour. Propagation of light is shown using the Radiation Transfer Theory (RTT) and a numerical Monte Carlo model. A thermal transfer model, that uses the results of the propagation of radiation, determines the distribution of temperature in the tissue. Two widely used lasers are considered, Nd:YAG (1064 nm) and KTP (532 nm). Adequate amounts of radiation, resulting in temperature rise, must be achieved in order to avoid damage in vocal cords and so to assure an improvement in the vocal functions of the patient. The limits in temperature should be considered with a combined temperature-time and Arrhenius analysis.

  9. Effect of cantilever geometry on the optical lever sensitivities and thermal noise method of the atomic force microscope.

    PubMed

    Sader, John E; Lu, Jianing; Mulvaney, Paul

    2014-11-01

    Calibration of the optical lever sensitivities of atomic force microscope (AFM) cantilevers is especially important for determining the force in AFM measurements. These sensitivities depend critically on the cantilever mode used and are known to differ for static and dynamic measurements. Here, we calculate the ratio of the dynamic and static sensitivities for several common AFM cantilevers, whose shapes vary considerably, and experimentally verify these results. The dynamic-to-static optical lever sensitivity ratio is found to range from 1.09 to 1.41 for the cantilevers studied - in stark contrast to the constant value of 1.09 used widely in current calibration studies. This analysis shows that accuracy of the thermal noise method for the static spring constant is strongly dependent on cantilever geometry - neglect of these dynamic-to-static factors can induce errors exceeding 100%. We also discuss a simple experimental approach to non-invasively and simultaneously determine the dynamic and static spring constants and optical lever sensitivities of cantilevers of arbitrary shape, which is applicable to all AFM platforms that have the thermal noise method for spring constant calibration.

  10. Crystal structure, optical and thermal studies of a new organic nonlinear optical material: L-Histidinium maleate 1.5-hydrate

    SciTech Connect

    Gonsago, C. Alosious; Albert, Helen Merina; Karthikeyan, J.; Sagayaraj, P.; Pragasam, A. Joseph Arul

    2012-07-15

    Highlights: ► L-Histidinium maleate 1.5-hydrate, a new organic crystal has been grown for the first time. ► The crystal structure is reported for the first time (CCDC 845975). ► The crystal belongs to monoclinic system with space group P2{sub 1}, Z = 4, a = 11.4656(7) Å, b = 8.0530(5) Å, c = 14.9705(9) Å and β = 101.657(2)°. ► The optical absorption study substantiates the complete transparency of the crystal. ► Kurtz powder SHG test confirms the nonlinear property of the crystal. -- Abstract: A new organic nonlinear optical material L-histidinium maleate 1.5-hydrate (LHM) with the molecular formula C{sub 10}H{sub 16}N{sub 3}O{sub 7.5} has been successfully synthesized from aqueous solution by slow solvent evaporation method. The structural characterization of the grown crystal was carried out by single crystal X-ray diffraction at 293(2) K. In the crystal, molecules are linked through inter and intramolecular N-H⋯O and O-H⋯O hydrogen bonds, generate edge fused ring motif. The hydrogen bonded motifs are linked to each other to form a three dimensional network. The FT-IR spectroscopy was used to identify the functional groups of the synthesized compound. The optical behavior of the grown crystal was examined by UV–visible spectral analysis, which shows that the optical absorption is almost negligible in the wavelength range 280–1300 nm. The nonlinear optical property was confirmed by the powder technique of Kurtz and Perry. The thermal behavior of the grown crystal was analyzed by thermogravimetric analysis.

  11. Application methods of infrared thermal images in the health care field of traditional Chinese medicine

    NASA Astrophysics Data System (ADS)

    Li, Ziru; Zhang, Xusheng

    2008-12-01

    Infrared thermal imaging (ITI) is the potential imaging technique for the health care field of traditional Chinese medicine (TCM). Successful application demands obeying the characteristics and regularity of the ITI of human body and designing rigorous trials. First, the influence of time must be taken into account as the ITI of human body varies with time markedly. Second, relative magnitude is preferred to be the index of the image features. Third, scatter diagrams and the method of least square could present important information for evaluating the health care effect. A double-blind placebo-controlled randomized trial was undertaken to study the influences of Shengsheng capsule, one of the TCM health food with immunity adjustment function, on the ITI of human body. The results showed that the effect of Shengsheng capsule to people with weak constitution or in the period of being weak could be reflected objectively by ITI. The relative efficacy rate was 81.3% for the trial group and 30.0% for the control group, there was significant difference between the two groups (P=0.003). So the sensitivity and objectivity of ITI are of great importance to the health care field of TCM.

  12. Health Monitoring Technology for Thermal Protection Systems on Reusable Hypersonic Vehicles

    NASA Technical Reports Server (NTRS)

    Milos, Frank S.; Watters, D. G.; Heinemann, J. M.; Karunaratne, K. S.; Arnold, Jim (Technical Monitor)

    2001-01-01

    Integrated subsystem health diagnostics is an area where major improvements have been identified for potential implementation into the design of new reusable launch vehicles (RLVs) in order to reduce life cycle costs, to increase safety margins, and to improve mission reliability. This talk summarizes a joint effort between NASA Ames and industry partners to develop rapid non-contact diagnostic tools for health and performance monitoring of thermal protection systems (TPS) on future RLVs. The specific goals for TPS health monitoring are to increase the speed and reliability of TPS inspections for improved operability at lower cost. The technology being developed includes a 3-D laser scanner for examining the exterior surface of the TPS, and a subsurface microsensor suite for monitoring the health and performance of the TPS. The sensor suite consists of passive overlimit sensors and sensors for continuous parameter monitoring in flight. The sensors are integrated with radio-frequency identification (RFID) microchips to enable wireless communication of-the sensor data to an external reader that may be a hand-held scanner or a large portal. Prototypes of the laser system and both types of subsurface sensors have been developed. The laser scanner was tested on Shuttle Orbiter Columbia and was able to dimension surface chips and holes on a variety of TPS materials. The temperature-overlimit microsensor has a diameter under 0.05 inch (suitable for placement in gaps between ceramic TPS tiles) and can withstand 700 F for 15 minutes.

  13. Analysis of bias thermal stability of interferometer fiber-optic gyroscope using a solid-core polarization-maintaining photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Zuoming, Sun; Shuhua, Wang; Junwei, Li; Yazhou, Zhang; Dapeng, Chen

    2016-12-01

    Bias thermal stability of a fiber-optic gyroscope using polarization-maintaining photonic crystal (PM-PCF) was studied. The thermal sensitivity of birefringence in PM-PCF and polarization cross talking in fiber coil was measured. Using an OCDP method, the polarization cross talking causing phase error of the fiber-optic gyroscope (FOG) was analyzed. The contrast experiment result of the FOGs with the PM-PCF coil and PMF coil showed that using PM-PCF instead of PMF can improve the FOG's bias thermal stability by about 50 %.

  14. Research on the aero-thermal effects by 3D analysis model of the optical window of the infrared imaging guidance

    NASA Astrophysics Data System (ADS)

    Xu, Bo; Li, Lin; Zhu, Ying

    2014-11-01

    Researches on hypersonic vehicles have been a hotspot in the field of aerospace because of the pursuits for higher speed by human being. Infrared imaging guidance is playing a very important role in modern warfare. When an Infrared Ray(IR) imaging guided missile is flying in the air at high speed, its optical dome suffers from serious aero-optic effects because of air flow. The turbulence around the dome and the thermal effects of the optical window would cause disturbance to the wavefront from the target. Therefore, detected images will be biased, dithered and blurred, and the capabilities of the seeker for detecting, tracking and recognizing are weakened. In this paper, methods for thermal and structural analysis with Heat Transfer and Elastic Mechanics are introduced. By studying the aero-thermal effects and aero-thermal radiation effects of the optical window, a 3D analysis model of the optical window is established by using finite element method. The direct coupling analysis is employed as a solving strategy. The variation regularity of the temperature field is obtained. For light with different incident angles, the influence on the ray propagation caused by window deformation is analyzed with theoretical calculation and optical/thermal/structural integrated analysis method respectively.

  15. Novel solid-state solar thermal simulator supplying 30,000 suns by a fibre optical probe.

    PubMed

    Alwahabi, Zeyad T; Kueh, Kimberley C Y; Nathan, Gus J; Cannon, Scott

    2016-10-31

    An efficient 3.168 kW solid-state solar thermal simulator (SSSTS), capable of supplying ~30,000 suns at a focal plane via a fibre optical delivery, has been developed. The source consists of 41 diode lasers, each operated at a wavelength and power of ~915 nm and ~80 watt, respectively. The SSSTS provides a semi-top hat radiation profile and can be focused to a diameter of ~10.5 mm. The electro-optical power efficiency of the SSSTS was evaluated to be 55%, where the maximum value of the uniform radiation flux exceeds 36.6MW/m2. As such, the present technology is relevant to solar thermal applications that are not wavelength-sensitive or where narrow line-width is desirable. Additionally, the fibre optical delivery feature enables ease of direction onto a suitable target, without the need of large ellipsoidal reflectors usually employed for the conventional arc solar simulators. To demonstrate the new SSSTS, ZnO:Zn particles were introduced into the path of the radiation to investigate the change in their own temperature by using the laser induced phosphorescence technique (LIP). The temperature of the averaged particles was measured at a different radiation flux over a ~87 mm2 cross sectional area. A change in the average particle temperature of up to 225°C was detected within the measurement volume when the SSSTS was operated at a flux of ~30,000 suns. The unique characteristics of the SSSTS, namely, the uniformity, high power flux, efficiency, ease of delivery, and precise control of the radiation flux responds to the current demands of solar thermal research.

  16. Synthesis, growth, structural, optical, thermal, electrical and mechanical properties of hydrogen bonded organic salt crystal: Triethylammonium-3, 5-dinitrosalicylate

    NASA Astrophysics Data System (ADS)

    Rajkumar, Madhu; Chandramohan, Angannan

    2017-04-01

    Triethylammonium-3, 5-dinitrosalicylate, an organic salt was synthesized and single crystals grown by slow solvent evaporation solution growth technique using methanol as a solvent. The presence of various functional groups and mode of vibrations has been confirmed by FT-IR spectroscopic technique. The UV-vis-NIR Spectrum was recorded in the range 200-1200 nm to find optical transmittance window and lower cut off wavelength of the title crystal. The formation of the salt and the molecular structure was confirmed by NMR spectroscopic technique. Crystal system, crystalline nature, cell parameters and hydrogen bonding interactions of the grown crystal were determined by single crystal x-ray diffraction analysis. The thermal characteristics of grown crystal were analyzed by thermo gravimetric and differential thermal analyses. Dielectric studies were carried out to study the distribution of charges within the crystal. The mechanical properties of the title crystal were studied by Vicker's microhardness technique.

  17. Dielectric and thermal effects on the optical properties of natural dyes: a case study on solvated cyanin.

    PubMed

    Malcıoğlu, Osman Bariş; Calzolari, Arrigo; Gebauer, Ralph; Varsano, Daniele; Baroni, Stefano

    2011-10-05

    The optical properties of the flavylium state of the cyanin dye are simulated numerically by combining Car-Parrinello molecular dynamics and linear-response time-dependent density functional theory calculations. The spectrum of the dye calculated in the gas phase is characterized by two peaks in the yellow and in the blue (green and violet), using a GGA-PBE (hybrid-B3LYP) DFT functional, which would bring about a greenish (bright orange) color incompatible with the dark purple hue observed in nature. Describing the effect of the water solvent through a polarizable continuum model does not modify qualitatively the resulting picture. An explicit simulation of both solvent and thermal effects using ab initio molecular dynamics results instead in a spectrum that is compatible with the observed coloration. This result is analyzed in terms of the spectroscopic effects of the molecular distortions induced by thermal fluctuations.

  18. Effects of particle size and hydro-thermal treatment of feed on performance and stomach health in fattening pigs.

    PubMed

    Liermann, Wendy; Berk, Andreas; Böschen, Verena; Dänicke, Sven

    2015-01-01

    Effects of grinding and hydro-thermal treatment of feed on growth performance, slaughter traits, nutrient digestibility, stomach content and stomach health were examined by using 96 crossbred fattening pigs. Pigs were fed a grain-soybean meal-based diet processed by various technical treatments. Feeding groups differed in particle size after grinding (finely vs. coarsely ground feed) and hydro-thermal treatment (without hydro-thermal treatment, pelleting, expanding, expanding and pelleting). Fine grinding and hydro-thermal treatment showed significant improvements on the digestibility of crude nutrients and content of metabolisable energy. Hydro-thermal treatment influenced average daily gain (ADG) and average daily feed intake (DFI) significantly. Finely ground pelleted feed without expanding enhanced performances by increasing ADG and decreasing feed-to-gain ratio (FGR) of fattening pigs. Coarsely ground feed without hydro-thermal treatment resulted in the highest ADG and DFI, however also in the highest FGR. Expanded feed decreased DFI and ADG. Slaughter traits were not affected by treatments. Coarsely ground feed without hydro-thermal treatment had protective effects on the health of gastric pars nonglandularis, however, pelleting increased gastric lesions. Hydro-thermal treatment, especially expanding, resulted in clumping of stomach content which possibly induced satiety by slower ingesta passage rate and thus decreased feed intake. Pigs fed pelleted feed showed less pronounced development of clumps in stomach content compared with expanded feed.

  19. Thermal-induced phase-shift error of a fiber-optic gyroscope due to fiber tail length asymmetry.

    PubMed

    Zhang, Yunhao; Zhang, Yonggang; Gao, Zhongxing

    2017-01-10

    As a high-precision angular sensor, the fiber-optic gyroscope (FOG) usually shows high sensitivity to disturbances of the environmental temperature. Research on thermal-induced error of the FOG is meaningful to improve its robust performance and reliability in practical applications. In this paper, thermal-induced nonreciprocal phase-shift error of the FOG due to asymmetric fiber tail length is discussed in detail, based on temperature diffusion theory. Theoretical analysis shows that the increase of thermal-induced nonreciprocal phase shift of the FOG is proportional to the asymmetric tail length. Moreover, experiments with temperature ranging from -40°C to 60°C are performed to confirm the analysis. The analysis and experiment results indicate that we may compensate the asymmetry of fiber coil due to imperfect winding and the assembly process by adjusting the fiber tail length, which can reduce the thermal-induced phase-shift error and further improve the adaptability of the FOG in a changing ambient temperature.

  20. Fiber-optic thermometry using thermal radiation from Tm end doped SiO{sub 2} fiber sensor

    SciTech Connect

    Morita, Kentaro; Katsumata, Toru; Komuro, Shuji; Aizawa, Hiroaki

    2014-04-15

    Fiber-optic thermometry based on temperature dependence of thermal radiation from Tm{sup 3+} ions was studied using Tm end doped SiO{sub 2} fiber sensor. Visible light radiation peaks due to f-f transition of Tm{sup 3+} ion were clearly observed at λ = 690 and 790 nm from Tm end doped SiO{sub 2} fibers sensor at the temperature above 600 °C. Thermal radiation peaks are assigned with f-f transition of Tm{sup 3+} ion, {sup 1}D{sub 2}-{sup 3}H{sub 6}, and {sup 1}G{sub 4}-{sup 3}H{sub 6}. Peak intensity of thermal radiation from Tm{sup 3+} ion increases with temperature. Intensity ratio of thermal radiation peaks at λ = 690 nm against that at λ = 790 nm, I{sub 790/690}, is suitable for the temperature measurement above 750 °C. Two-dimensional temperature distribution in a flame is successfully evaluated by Tm end doped SiO{sub 2} fiber sensor.

  1. Thermally Induced Nano-Structural and Optical Changes of nc-Si:H Deposited by Hot-Wire CVD.

    PubMed

    Arendse, C J; Malgas, G F; Muller, T F G; Knoesen, D; Oliphant, C J; Motaung, D E; Halindintwali, S; Mwakikunga, B W

    2009-01-21

    We report on the thermally induced changes of the nano-structural and optical properties of hydrogenated nanocrystalline silicon in the temperature range 200-700 degrees C. The as-deposited sample has a high crystalline volume fraction of 53% with an average crystallite size of ~3.9 nm, where 66% of the total hydrogen is bonded as identical withSi-H monohydrides on the nano-crystallite surface. A growth in the native crystallite size and crystalline volume fraction occurs at annealing temperatures >/=400 degrees C, where hydrogen is initially removed from the crystallite grain boundaries followed by its removal from the amorphous network. The nucleation of smaller nano-crystallites at higher temperatures accounts for the enhanced porous structure and the increase in the optical band gap and average gap.

  2. Effect of L-cysteine on optical, thermal and mechanical properties of ADP crystal for NLO application

    NASA Astrophysics Data System (ADS)

    Shaikh, R. N.; Shirsat, M. D.; Koinkar, P. M.; Hussaini, S. S.

    2015-06-01

    The ammonium dihydrogen phosphate (ADP) crystal doped with amino acid L-cysteine (LC) was grown by a slow evaporation technique. The grown crystal was transparent in the entire visible region, which is an essential requirement for a nonlinear crystal. The LC doping enhances the optical band gap of ADP (5.35 eV). The TG/DTA analysis of LC doped ADP crystal confirms the optimum thermal stability of grown crystal. The enhancement in the mechanical stability after LC doping was confirmed by Vicker's microhardness test. The LC doping showed significant impact on dielectric properties (dielectric constant and dielectric loss) of grown crystal. The third order nonlinear behavior of LC doped ADP crystal was investigated using a Z-scan technique at 632.8 nm and effective nonlinear optical parameters were evaluated.

  3. Design and Operation of an Optically-Accessible Modular Reactor for Diagnostics of Thermal Thin Film Deposition Processes

    PubMed Central

    Kimes, W. A.; Sperling, B. A.; Maslars, J. E.

    2015-01-01

    The design and operation of a simple, optically-accessible modular reactor for probing thermal thin film deposition processes, such as atomic layer deposition processes (ALD) and chemical vapor deposition (CVD), is described. This reactor has a nominal footprint of 225 cm2 and a mass of approximately 6.6 kg, making it small enough to conveniently function as a modular component of an optical train. The design is simple, making fabrication straightforward and relatively inexpensive. Reactor operation is characterized using two infrared absorption measurements to determine exhaust times for tetrakis(dimethylamino)titanium and water, proto-typical ALD precursors, in a pressure and flow regime commonly used for ALD. PMID:26958438

  4. Improved performance of thermal-optic switch using polymer/silica hybrid and air trench waveguide structures.

    PubMed

    Liu, Yu-Fen; Wang, Xi-Bin; Sun, Jing-Wen; Sun, Jian; Wang, Fei; Chen, Chang-Ming; Sun, Xiao-Qiang; Cui, Zhan-Chen; Zhang, Da-Ming

    2015-05-01

    By exploiting the polymer/silica hybrid and the air trench waveguide structures, we demonstrate a new type of low-power consuming and high-speed thermal-optic (TO) switch. Such a design provides an effective means to shorten the switching time of the TO switches, as well as to reduce the power consumption at the same time. This TO switch operated with less than 150 μs of switching time via a polymer/silica hybrid waveguide structure. Meanwhile, the power consumption was reduced to be 3.4 mW by introducing the air trench structure.

  5. Growth, structural, spectral, optical, and thermal studies on amino acid based new NLO single crystal: L-phenylalanine-4-nitrophenol

    NASA Astrophysics Data System (ADS)

    Prakash, M.; Lydia Caroline, M.; Geetha, D.

    2013-05-01

    A new organic nonlinear optical single crystal, L-phenylalanine-4-nitrophenol (LPAPN) belonging to the amino acid group has been successfully grown by slow evaporation technique. The lattice parameters of the grown crystal have been determined by X-ray diffraction studies. FT-IR spectrum was recorded to identify the presence of functional group and molecular structure was confirmed by NMR spectrum. Thermal strength of the grown crystal has been studied using TG-DTA analyses. The grown crystals were found to be transparent in the entire visible region. The existence of second harmonic generation signals was observed using Nd:YAG laser with fundamental wavelength of 1064 nm.

  6. Growth, structural, spectral, optical, and thermal studies on amino acid based new NLO single crystal: L-phenylalanine-4-nitrophenol.

    PubMed

    Prakash, M; Lydia Caroline, M; Geetha, D

    2013-05-01

    A new organic nonlinear optical single crystal, L-phenylalanine-4-nitrophenol (LPAPN) belonging to the amino acid group has been successfully grown by slow evaporation technique. The lattice parameters of the grown crystal have been determined by X-ray diffraction studies. FT-IR spectrum was recorded to identify the presence of functional group and molecular structure was confirmed by NMR spectrum. Thermal strength of the grown crystal has been studied using TG-DTA analyses. The grown crystals were found to be transparent in the entire visible region. The existence of second harmonic generation signals was observed using Nd:YAG laser with fundamental wavelength of 1064 nm.

  7. Fiber optic thermal/fast neutron and gamma ray scintillation detector

    DOEpatents

    Neal, John S.; Mihalczo, John T.

    2006-11-28

    A detector system that combines a .sup.6Li loaded glass fiber scintillation thermal neutron detector with a fast scintillation detector in a single layered structure. Detection of thermal and fast neutrons and ionizing electromagnetic radiation is achieved in the unified detector structure. The fast scintillator replaces the polyethelene moderator layer adjacent the .sup.6Li loaded glass fiber panel of the neutron detector and acts as the moderator for the glass fibers. Fast neutrons, x-rays and gamma rays are detected in the fast scintillator. Thermal neutrons, x-rays and gamma rays are detected in the glass fiber scintillator.

  8. 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.

  9. All-optically driven system in ultrasonic wave-based structural health monitoring

    NASA Astrophysics Data System (ADS)

    Bi, Siwen; Wu, Nan; Zhou, Jingcheng; Zhang, Haifeng; Wang, Xingwei

    2016-04-01

    Ultrasonic wave based structural health monitoring (SHM) is an innovative method for nondestructive detection and an area of growing interest. This is due to high demands for wireless detection in the field of structural engineering. Through optically exciting and detecting ultrasonic waves, electrical wire connections can be avoided, and non-contact SHM can be achieved. With the combination of piezoelectric transducer (PZT) (which possesses high heat resistance) and the noncontact detection, this system has a broad range of applications, even in extreme conditions. This paper reports an all-optically driven SHM system. The resonant frequencies of the PZT transducers are sensitive to a variety of structural damages. Experimental results have verified the feasibility of the all-optically driven SHM system.

  10. Fiber-optic thermometer application of thermal radiation from rare-earth end-doped SiO{sub 2} fiber

    SciTech Connect

    Katsumata, Toru Morita, Kentaro; Komuro, Shuji; Aizawa, Hiroaki

    2014-08-15

    Visible light thermal radiation from SiO{sub 2} glass doped with Y, La, Ce, Pr, Nd, Eu, Tb, Dy, Ho, Er, Tm, Yb, and Lu were studied for the fiber-optic thermometer application based on the temperature dependence of thermal radiation. Thermal radiations according to Planck's law of radiation are observed from the SiO{sub 2} fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu at the temperature above 1100 K. Thermal radiations due to f-f transitions of rare-earth ions are observed from the SiO{sub 2} fibers doped with Nd, Dy, Ho, Er, Tm, and Yb at the temperature above 900 K. Peak intensities of thermal radiations from rare-earth doped SiO{sub 2} fibers increase sensitively with temperature. Thermal activation energies of thermal radiations by f-f transitions seen in Nd, Dy, Ho, Er, Tm, and Yb doped SiO{sub 2} fibers are smaller than those from SiO{sub 2} fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu. Thermal radiation due to highly efficient f-f transitions in Nd, Dy, Ho, Er, Tm, and Yb ions emits more easily than usual thermal radiation process. Thermal radiations from rare-earth doped SiO{sub 2} are potentially applicable for the fiber-optic thermometry above 900 K.

  11. Growth, structural, optical, thermal and mechanical properties of cytosinium hydrogen selenite: A novel nonlinear optical single crystal

    SciTech Connect

    Jaikumar, P.; Sathiskumar, S.; Balakrishnan, T.; Ramamurthi, K.

    2016-06-15

    Highlights: • Growth of bulk single crystals of cytosinium hydrogen selenite (CHS) is reported. • Dielectric constant of CHS is measured as a function of Frequency and temperature. • Lower cut off value of UV–vis-NIR spectrum of CHS crystal is observed at 210 nm. • Meyer’s index value of CHS crystal calculated identifies it as a soft material. • Powder SHG efficiency of CHS is about 1.5 times that of KDP crystal. - Abstract: A novel nonlinear optical single crystal of cytosinium hydrogen selenite was grown from aqueous solution of cytosinium hydrogen selenite by slow solvent evaporation method at room temperature. The structural properties of grown crystal have been studied by single crystal and powder X-ray diffraction analysis. Presence of various functional groups was identified from Fourier transform infrared spectroscopy. The optical transmittance and absorbance spectra were recorded by UV–vis-NIR spectrometer and the grown crystal possesses good transparency in the entire visible region. The dielectric constant and dielectric loss of the crystal were calculated as a function of frequency at different temperatures. The mechanical strength of the cytosinium hydrogen selenite crystal was estimated using Vicker’s microhardness tester. Etch patterns of the cytosinium hydrogen selenite crystal were obtained using distilled water as etchant for different etching time. Second harmonic generation efficiency tested using Nd:YAG laser is about 1.5 times that of KDP.

  12. Direct frequency comb optical frequency standard based on two-photon transitions of thermal atoms

    PubMed Central

    Zhang, S. Y.; Wu, J. T.; Zhang, Y. L.; Leng, J. X.; Yang, W. P.; Zhang, Z. G.; Zhao, J. Y.

    2015-01-01

    Optical clocks have been the focus of science and technology research areas due to their capability to provide highest frequency accuracy and stability to date. Their superior frequency performance promises significant advances in the fields of fundamental research as well as practical applications including satellite-based navigation and ranging. In traditional optical clocks, ultrastable optical cavities, laser cooling and particle (atoms or a single ion) trapping techniques are employed to guarantee high stability and accuracy. However, on the other hand, they make optical clocks an entire optical tableful of equipment, and cannot work continuously for a long time; as a result, they restrict optical clocks used as very convenient and compact time-keeping clocks. In this article, we proposed, and experimentally demonstrated, a novel scheme of optical frequency standard based on comb-directly-excited atomic two-photon transitions. By taking advantage of the natural properties of the comb and two-photon transitions, this frequency standard achieves a simplified structure, high robustness as well as decent frequency stability, which promise widespread applications in various scenarios. PMID:26459877

  13. Direct frequency comb optical frequency standard based on two-photon transitions of thermal atoms.

    PubMed

    Zhang, S Y; Wu, J T; Zhang, Y L; Leng, J X; Yang, W P; Zhang, Z G; Zhao, J Y

    2015-10-13

    Optical clocks have been the focus of science and technology research areas due to their capability to provide highest frequency accuracy and stability to date. Their superior frequency performance promises significant advances in the fields of fundamental research as well as practical applications including satellite-based navigation and ranging. In traditional optical clocks, ultrastable optical cavities, laser cooling and particle (atoms or a single ion) trapping techniques are employed to guarantee high stability and accuracy. However, on the other hand, they make optical clocks an entire optical tableful of equipment, and cannot work continuously for a long time; as a result, they restrict optical clocks used as very convenient and compact time-keeping clocks. In this article, we proposed, and experimentally demonstrated, a novel scheme of optical frequency standard based on comb-directly-excited atomic two-photon transitions. By taking advantage of the natural properties of the comb and two-photon transitions, this frequency standard achieves a simplified structure, high robustness as well as decent frequency stability, which promise widespread applications in various scenarios.

  14. Effects of thermal deformations on the sensitivity of optical systems for space application

    NASA Astrophysics Data System (ADS)

    Segato, Elisa; Da Deppo, Vania; Debei, Stefano; Cremonese, Gabriele; Cherubini, Giovanni

    2010-07-01

    In this paper the results of the thermo-elastic analysis performed on the Stereo Imaging Channel of the imaging system SIMBIO-SYS for the BepiColombo ESA mission to Mercury is presented. The aim of the work is to determine the expected stereo reconstruction accuracy of the surface of the planet Mercury, i.e. the target of BepiColombo mission, due to the effects of the optics misalignments and deformations induced by temperature changes during the mission lifetime. The camera optics and their mountings are modeled and processed by a thermo-mechanical Finite Element Model (FEM) program, which reproduces the expected optics and structure thermo-elastic variations in the instrument foreseen operative temperature range, i.e. between -20 °C and 30 °C. The FEM outputs are elaborated using a MATLAB optimization routine: a non-linear least square algorithm is adopted to determine the surface equation (plane, spherical, nth polynomial) which best fits the deformed optical surfaces. The obtained surfaces are then directly imported into ZEMAX raytracing code for sequential raytrace analysis. Variations of the optical center position, boresight direction, focal length and distortion are then computed together with the corresponding image shift on the detector. The overall analysis shows the preferable use of kinematic constraints, instead of glue classical solution, for optical element mountings, this minimize the uncertainty on the Mercury Digital Terrain Model (DTM) reconstructed via a stereo-vision algorithm based on the triangulation from two optical channels.

  15. Method for studying the effects of thermal deformations on optical systems for space application.

    PubMed

    Segato, Elisa; Da Deppo, Vania; Debei, Stefano; Naletto, Giampiero; Cremonese, Gabriele; Flamini, Enrico

    2011-06-20

    In this paper, the results of the thermo-elastic analysis performed on the stereo channel of the imaging system Integrated Observatory System for the BepiColombo European Space Agency mission to Mercury are presented. The aim of the work is to determine the effects of ambient parameter variations on the equipment performance; the optical performance is changing during the mission lifetime primarily because of the optics misalignments and deformations induced by temperature variations. The camera optics and their mountings are modeled and processed by a thermo-mechanical finite element model (FEM) program, which reproduces the expected optics and structure thermo-elastic deformations in the instrument foreseen operative temperature range, i.e., between -20 °C and 30 °C. The FEM outputs are elaborated using a MATLAB optimization routine: an algorithm based on nonlinear least square data fitting is adopted to determine the surface equation (plane, spherical, nth polynomial) which best fits the deformed optical surfaces. The obtained surfaces are then directly imported into a ZEMAX code for sequential ray-tracing analysis. Variations of the optical spot diagrams, modulation transfer function curves, and ensquared energy are then computed. The overall analysis shows that the preferred solution for mounting the optical elements is adopting the kinematic constraints instead of using the classical glue solution.

  16. Fiber Optic Cable Assemblies for Space Flight 2: Thermal and Radiation Effects

    NASA Technical Reports Server (NTRS)

    Ott, Melanie N.

    1998-01-01

    Goddard Space Flight Center is conducting a search for space flight worthy fiber optic cable assemblies that will benefit all projects at all of the NASA centers. This paper is number two in a series of papers being issued as a result of this task to define and qualify space grade fiber optic cable assemblies. Though to qualify and use a fiber optic cable in space requires treatment of the cable assembly as a system, it is very important to understand the design and behavior of its parts. This paper addresses that need, providing information on cable components shrinkage testing and radiation testing results from recent experiments at Goddard Space Flight Center.

  17. Thermally induced all-optical inverter and dynamic hysteresis loops in graphene oxide dispersions.

    PubMed

    Melle, Sonia; Calderón, Oscar G; Egatz-Gómez, Ana; Cabrera-Granado, E; Carreño, F; Antón, M A

    2015-11-01

    We experimentally study the temporal dynamics of amplitude-modulated laser beams propagating through a water dispersion of graphene oxide sheets in a fiber-to-fiber U-bench. Nonlinear refraction induced in the sample by thermal effects leads to both phase reversing of the transmitted signals and dynamic hysteresis in the input-output power curves. A theoretical model including beam propagation and thermal lensing dynamics reproduces the experimental findings.

  18. Study of the Photodegradation Process of Vitamin E Acetate by Optical Absorption, Fluorescence, and Thermal Lens Spectroscopy

    NASA Astrophysics Data System (ADS)

    Tiburcio-Moreno, J. A.; Marcelín-Jiménez, G.; Leanos-Castaneda, O. L.; Yanez-Limon, J. M.; Alvarado-Gil, J. J.

    2012-11-01

    The stability of vitamin E acetate exposed to ultraviolet (UV) light was studied using three spectroscopic methods. An ethanol solution of vitamin E acetate was treated with either UVC light (254 nm) or UVA light (366 nm) during a period of 10 min followed by a study of UV-Vis optical absorption, then by fluorescence spectroscopy excitation by UV radiation at either 290 nm or 368 nm and, finally the solution was studied by thermal lens spectroscopy. Immediately, the same solution of vitamin E acetate was subjected to the UV irradiation process until completion of six periods of irradiation and measurements. UVC light treatment induced the appearance of a broad absorption band in the range of 310 nm to 440 nm with maximum absorbance at 368 nm, which progressively grew as the time of the exposure to UVC light increases. In contrast, UVA light treatment did not affect the absorption spectra of vitamin E acetate. Fluorescence spectra of the vitamin E acetate (without UV light treatment) showed no fluorescence when excited with 368 nm while exciting with 290 nm, an intense and broad emission band (300 nm to 440 nm) with a maximum at 340 nm appeared. When vitamin E acetate was treated with UVC light, this emission band progressively decreased as the time of the UVC light irradiation grew. No signal from UV-untreated vitamin E acetate could be detected by the thermal lens method. Interestingly, as the time of the UVC light treatment increased, the thermal lens signal progressively grew. Additional experiments performed to monitor the time evolution of the process during continuous UVC treatment of the vitamin E acetate using thermal lens spectroscopy exhibited a progressive increase of the thermal lens signal reaching a plateau at about 8000 s. This study shows that the vitamin E acetate is stable when it is irradiated with UVA light, while the irradiation with UVC light induces the formation of photodegradation products. Interestingly, this photodegradation process using

  19. Modeling Climate Change and Thermal Restoration Strategies in a Northern California Stream Using HEAT SOURCE and Distributed Temperature Sensing Fiber-optics

    NASA Astrophysics Data System (ADS)

    Bond, R. M.; Stubblefield, A. P.

    2013-12-01

    Land uses which modify stream channel structure and riparian vegetation can alter the mechanisms of heat transfer within a stream. Stream temperature is a crucial abiotic factor which governs aquatic biota quantity, distribution, and overall health. The IPCC has projected stream temperature to increase with changes in global climate due to elevated air temperature and changes in precipitation patterns. Stream temperature modeling can investigate current and future stream temperature conditions. Heat Source, developed by Oregon Department of Environmental Quality (DEQ), was applied to a one kilometer section of the North Fork of the Salmon River, a tributary of the Klamath River, northern California, USA. Heat Source accounts for internal and external thermal energy transfers to predict stream temperature at point locations. Inputs include meteorologic, geomorphologic, hydrologic and topographic measurements from the study site. The Salmon River watershed has a legacy of historic hydraulic gold mining which has changed channel morphology and created extensive denuded gravel bars. The Salmon River is listed as thermally impaired under California's List of Impaired Water Bodies 303(d) with mainstem temperature commonly exceeding salmonid temperature thresholds. The objective of this research was to utilize Heat Source to predict effects of climate change, riparian management, and channel geometry on stream temperature. This study employed Distributed Temperature Sensing fiber-optics (DTS) to detect stream heating and cooling at one meter resolution which was then used to calibrate Heat Source at the study reach. Predicted values closely matched DTS measurements reflecting shifting responses to air temperature, riparian vegetation distribution, and channel geometry conditions. Heat Source modeling of climate change scenarios using forecasted 2049 and 2099 elevated air temperatures are presented. Furthermore, temperature impacts of increased riparian vegetation density

  20. Few layers graphene as thermally activated optical modulator in the visible-near IR spectral range.

    PubMed

    Benítez, J L; Hernández-Cordero, Juan; Muhl, S; Mendoza, D

    2016-01-01

    We report the temperature modulation of the optical transmittance of a few layers of graphene (FLG). The FLG was heated either by the Joule effect of the current flowing between coplanar electrodes or by the absorption of a continuous-wave 532 nm laser. The optical signals used to evaluate the modulation of the FLG were at 633, 975, and 1550 nm; the last wavelengths are commonly used in optical communications. We also evaluated the effect of the substrate on the modulation effect by comparing the performance of a freely suspended FLG sample with one mounted on a glass substrate. Our results show that the modulation of the optical transmittance of FLG can be from millihertz to kilohertz.

  1. Rad-Tolerant, Thermally Stable, High-Speed Fiber-Optic Network for Harsh Environments

    NASA Technical Reports Server (NTRS)

    Leftwich, Matt; Hull, Tony; Leary, Michael; Leftwich, Marcus

    2013-01-01

    Future NASA destinations will be challenging to get to, have extreme environmental conditions, and may present difficulty in retrieving a spacecraft or its data. Space Photonics is developing a radiation-tolerant (rad-tolerant), high-speed, multi-channel fiber-optic transceiver, associated reconfigurable intelligent node communications architecture, and supporting hardware for intravehicular and ground-based optical networking applications. Data rates approaching 3.2 Gbps per channel will be achieved.

  2. Characterization of a graphite epoxy optical bench during thermal vacuum cycling

    NASA Technical Reports Server (NTRS)

    Hansen, Patricia A.; Jenkins, Teresa K.; Maag, Carl R.; Taylor, Daniel M.

    1988-01-01

    In-situ monitoring of the Wide-Field/Planetary Camera, a Hubble Space Telescope science instrument, was performed in a vacuum environment to better understand the formation of ice on cooled optical detectors. Several diagnostic instruments were mounted on an access plate to view the interior of the instrument housing and the graphite epoxy optical bench. The instrumentation chosen and the rationale for choosing the instrumentation are discussed. In addition, the performance of the instrumentation during monitoring operations is discussed.

  3. Evaluation of the Use of Optical Fiber Thermometers for Thermal Control of the Quench Module Insert

    NASA Technical Reports Server (NTRS)

    Jones, Matthew R.; Farmer, Jeffrey T.; Breeding, Shawn P.

    1999-01-01

    Issues regarding the use of optical fiber thermometers to control heater settings in a microgravity vacuum furnace are addressed. It is desirable to use these probes in environments such as the International Space Station, because they can be operated without re-calibration for extended periods. However, the analysis presented in this paper shows that temperature readings obtained using optical fiber thermometers are corrupted due to emissions from the fiber when extended portions of the probe are exposed to elevated temperatures.

  4. Evaluation of the Use of Optical Fiber Thermometers for Thermal Control of the Quench Module Insert

    NASA Technical Reports Server (NTRS)

    Jones, Matthew R.; Farmer, Jeffrey T.; Breeding, Shawn P.

    2001-01-01

    Issues regarding the use of optical fiber thermometers to control heater settings in a microgravity vacuum furnace are addressed. It is desirable to use these probes in environments such as the International Space Station, because they can be operated without re-calibration for extended periods. However, the analysis presented in this paper shows that temperature readings obtained using optical fiber thermometers can be corrupted by emissions from the fiber when extended portions of the probe are exposed to elevated temperatures.

  5. Photoacoustic detection and optical spectroscopy of high-intensity focused ultrasound-induced thermal lesions in biologic tissue

    SciTech Connect

    Alhamami, Mosa; Kolios, Michael C.; Tavakkoli, Jahan

    2014-05-15

    Purpose: The aims of this study are: (a) to investigate the capability of photoacoustic (PA) method in detecting high-intensity focused ultrasound (HIFU) treatments in muscle tissuesin vitro; and (b) to determine the optical properties of HIFU-treated and native tissues in order to assist in the interpretation of the observed contrast in PA detection of HIFU treatments. Methods: A single-element, spherically concaved HIFU transducer with a centre frequency of 1 MHz was utilized to create thermal lesions in chicken breast tissuesin vitro. To investigate the detectability of HIFU treatments photoacoustically, PA detection was performed at 720 and 845 nm on seven HIFU-treated tissue samples. Within each tissue sample, PA signals were acquired from 22 locations equally divided between two regions of interest within two volumes in tissue – a HIFU-treated volume and an untreated volume. Optical spectroscopy was then carried out on 10 HIFU-treated chicken breast specimens in the wavelength range of 500–900 nm, in 1-nm increments, using a spectrophotometer with an integrating sphere attachment. The authors’ optical spectroscopy raw data (total transmittance and diffuse reflectance) were used to obtain the optical absorption and reduced scattering coefficients of HIFU-induced thermal lesions and native tissues by employing the inverse adding-doubling method. The aforementioned interaction coefficients were subsequently used to calculate the effective attenuation coefficient and light penetration depth of HIFU-treated and native tissues in the wavelength range of 500–900 nm. Results: HIFU-treated tissues produced greater PA signals than native tissues at 720 and 845 nm. At 720 nm, the averaged ratio of the peak-to-peak PA signal amplitude of HIFU-treated tissue to that of native tissue was 3.68 ± 0.25 (mean ± standard error of the mean). At 845 nm, the averaged ratio of the peak-to-peak PA signal amplitude of HIFU-treated tissue to that of native tissue was 3.75

  6. 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.

  7. Optical and structural characterization of thermal oxidation effects of erbium thin films deposited by electron beam on silicon

    SciTech Connect

    Kamineni, Himani S.; Kamineni, Vimal K.; Moore, Richard L.; Gallis, Spyros; Diebold, Alain C.; Huang Mengbing; Kaloyeros, Alain E.

    2012-01-01

    Thermal oxidation effects on the structural, compositional, and optical properties of erbium films deposited on silicon via electron beam evaporation were analyzed by x-ray diffraction, x-ray photoelectron spectroscopy, Auger electron spectroscopy, and spectroscopic ellipsometry. A gradual rise in oxidation temperature from 700 to 900 deg. C resulted in a transition from ErO- to Er{sub 2}O{sub 3}-rich phase. Additional increase in oxidation temperature above 1000 deg. C led to the formation of erbium silicate due to further oxygen incorporation, as well as silicon out-diffusion from the substrate. A silicon oxide interfacial layer was also detected, with its thickness increasing with higher oxidation temperature. Additionally, film refractive index decreased, while its Tauc bandgap value increased from {approx}5.2 eV to {approx}6.4 eV, as the oxidation temperature was raised from 700 deg. C to above 900 deg. C. These transformations were accompanied by the appearance of an intense and broad absorption band below the optical gap. Thermal oxidation effects are discussed in the context of film structural characteristics and defect states.

  8. Decadal Trends and Common Dynamics of the Bio-Optical and Thermal Characteristics of the African Great Lakes

    PubMed Central

    Loiselle, Steven; Cózar, Andrés; Adgo, Enyew; Ballatore, Thomas; Chavula, Geoffrey; Descy, Jean Pierre; Harper, David M.; Kansiime, Frank; Kimirei, Ismael; Langenberg, Victor; Ma, Ronghua; Sarmento, Hugo; Odada, Eric

    2014-01-01

    The Great Lakes of East Africa are among the world’s most important freshwater ecosystems. Despite their importance in providing vital resources and ecosystem services, the impact of regional and global environmental drivers on this lacustrine system remains only partially understood. We make a systematic comparison of the dynamics of the bio-optical and thermal properties of thirteen of the largest African lakes between 2002 and 2011. Lake surface temperatures had a positive trend in all Great Lakes outside the latitude of 0° to 8° south, while the dynamics of those lakes within this latitude range were highly sensitive to global inter-annual climate drivers (i.e. El Niño Southern Oscillation). Lake surface temperature dynamics in nearly all lakes were found to be sensitive to the latitudinal position of the Inter Tropical Convergence Zone. Phytoplankton dynamics varied considerably between lakes, with increasing and decreasing trends. Intra-lake differences in both surface temperature and phytoplankton dynamics occurred for many of the larger lakes. This inter-comparison of bio-optical and thermal dynamics provides new insights into the response of these ecosystems to global and regional drivers. PMID:24699528

  9. Multicycle rapid thermal annealing optimization of Mg-implanted GaN: Evolution of surface, optical, and structural properties

    SciTech Connect

    Greenlee, Jordan D.; Feigelson, Boris N.; Anderson, Travis J.; Hite, Jennifer K.; Mastro, Michael A.; Eddy, Charles R.; Hobart, Karl D.; Kub, Francis J.; Tadjer, Marko J.

    2014-08-14

    The first step of a multi-cycle rapid thermal annealing process was systematically studied. The surface, structure, and optical properties of Mg implanted GaN thin films annealed at temperatures ranging from 900 to 1200 °C were investigated by Raman spectroscopy, photoluminescence, UV-visible spectroscopy, atomic force microscopy, and Nomarski microscopy. The GaN thin films are capped with two layers of in-situ metal organic chemical vapor deposition -grown AlN and annealed in 24 bar of N{sub 2} overpressure to avoid GaN decomposition. The crystal quality of the GaN improves with increasing annealing temperature as confirmed by UV-visible spectroscopy and the full widths at half maximums of the E{sub 2} and A{sub 1} (LO) Raman modes. The crystal quality of films annealed above 1100 °C exceeds the quality of the as-grown films. At 1200 °C, Mg is optically activated, which is determined by photoluminescence measurements. However, at 1200 °C, the GaN begins to decompose as evidenced by pit formation on the surface of the samples. Therefore, it was determined that the optimal temperature for the first step in a multi-cycle rapid thermal anneal process should be conducted at 1150 °C due to crystal quality and surface morphology considerations.

  10. Effect of intermediate oxide (Y2O3) on thermal, structural and optical properties of lithium borosilicate glasses

    NASA Astrophysics Data System (ADS)

    Singh, Satwinder; Kalia, Gaurav; Singh, K.

    2015-04-01

    Glass and glass ceramic samples with composition 55SiO2-30B2O3-(x)Li2O-(15 - x)Y2O3, where x = 0, 5, 10, 15 are prepared by conventional melt-quench technique. The structural, physical, thermal, optical, mechanical and conducting properties of these glasses are studied using X-ray diffraction (XRD), Differential Thermal Analyzer (DTA), Fourier Transform Infrared spectroscopy (FTIR), UV-visible spectroscopy and Impedance spectroscopy. Theoretical elastic moduli are calculated for the better understanding of the glass network strength. All samples, except with x = 0 glass, are amorphous in nature. Two broad halos are observed in x = 5 and x = 10 glasses, indicating phase separation in these glasses. Optical band gap of the samples decreases with increasing Y2O3 content. The lowest band gap is observed ∼3.60 eV for x = 15 glass. Urbach energy increased with an increase in Y2O3 concentration. Y2O3 played different roles at different concentrations and enhanced the phase separation tendency in glass. The typical conductivity was observed ∼10-6 S/cm at 620 °C for x = 10 glass.

  11. Thermo-optic coefficients and thermal lensing in Nd-doped KGd(WO4)2 laser crystals.

    PubMed

    Loiko, Pavel A; Yumashev, Konstantin V; Kuleshov, Nikolai V; Pavlyuk, Anatoly A

    2010-12-01

    We measured the thermo-optic coefficients dn/dT of anisotropic Nd:KGd(WO(4))(2) crystals at the wavelengths of 1.064 μm and 532 nm (300 K) by a beam deflection method. The values of dn/dT are determined to be dn(p)/dT = -16.0 × 10(-6) K(-1), dn(m)/dT = -11.8 × 10(-6) K(-1), and dn(g)/dT = -19.5 × 10(-6) K(-1) (at 1.064 μm) and dn(p)/dT = -14.3 × 10(-6) K(-1), dn(m)/dT = -10.0 × 10(-6) K(-1), and dn(g)/dT = -15.0 × 10(-6) K(-1) (at 532 nm). Thermal lensing in the flashlamp-pumped N(p)- and N(g)-cut Nd:KGd(WO(4))(2) laser rods was studied at 1.064 μm by a probe beam technique in the nonlasing conditions, and the contribution of the photoelastic term to the thermal lens optical power was estimated. Athermal propagation directions with the definitions dn/dT + (n-1)α(T) = 0 and dn/dT + nα(T) = 0 were found in Nd:KGd(WO(4))(2).

  12. Thermal stress characterization using the impedance-based structural health monitoring system

    NASA Astrophysics Data System (ADS)

    Zhu, Xuan; Lanza di Scalea, Francesco; Fateh, Mahmood

    2016-04-01

    Structural health monitoring (SHM) has attracted researchers' interests for the past two decades to reinforce the maintenance of the aging infrastructure systems all over the world. As one of the potential solutions, the electro-mechanical impedance (EMI) method was introduced in the early 1990s and has a great number of potential applications in the SHM of civil, mechanical and aerospace industries. This paper studied the impedance-based technique with the presence of environmental/operational variability, especially the influences of temperature and uniaxial stress on the admittance signature-based features. A comprehensive analytical model is established and provides satisfactory agreements with the experimental results. The stress and temperature sensitivities of all the proposed features are quantified using the experimental measurements, with discussions on their advantages and disadvantages. The final results illustrate that the EMI method can potentially provide effective measure for thermal stress.

  13. Low-cost high-manufacturability and thermal stability optical front-end for 10-Gb ethernet applications

    NASA Astrophysics Data System (ADS)

    Lee, Shin-Ge; Lee, Chun-Hsing; Liao, Li-Chun; Tsai, Cheng-Hung; Chen, Chih-Li; Huang, Min-Fa; Hsu, Chih-Hao; Cheng, Fu-Yi; Kao, Min-Sheng; Wang, Chiung-Hung

    2004-05-01

    With the drastic expansion of internet usage, the demand of 10Gb/s transmission optoelectronic devices for local-area-network (LAN) and storage-area-network (SAN) are increasing. The key issues of these applications are to improve cost, manufacturability and reliability of optoelectronic devices in high speed transmission. The authors have demonstrated extremely low cost, high manufacturability and thermal stability optical fron-end for 10Gb/s Ethernet applications in this paper. High performance and high sensitivity of 10Gb/s transmitter optical sub-assembly (TOSA) and receiver optical sub-assembly (ROSA) with TO-Can packages are discussed and demonstrated to overcome the critical points in high speed applications, respectively. Moreover, 10km interconnection of 10Gb/s optical front-end without isolated elements inside are also proved to be error free at 10.3125Gb/s. In order to improve the signal integrity and manufacturability of 10Gb/s OSA in small form factor transceiver modules assembly, the authors also integrate high speed flex board and OSA package to extend the signal path, and to minimize the effect of crosstalk in modules. Furthermore, the integration of flex board and OSA package more release the difficulties in conjuunction OSA and electrical sub-assembly (ESA) in module to fulfill the request of 10Gb/s transeivers' Multi-Source Agreement (MSA). The performance of temperature stabilized TOSA over wide case temperature range is also experimented. The optical eye diagram of 10Gb/s TOSA developed in this study showing excellent eye quality passing 10Gb/s Ethernet mask test between 0°C to 85°C.

  14. Modeling of Optical Waveguide Poling and Thermally Stimulated Discharge (TSD) Charge and Current Densities for Guest/Host Electro Optic Polymers

    NASA Technical Reports Server (NTRS)

    Watson, Michael D.; Ashley, Paul R.; Abushagur, Mustafa

    2004-01-01

    A charge density and current density model of a waveguide system has been developed to explore the effects of electric field electrode poling. An optical waveguide may be modeled during poling by considering the dielectric charge distribution, polarization charge distribution, and conduction charge generated by the poling field. These charge distributions are the source of poling current densities. The model shows that boundary charge current density and polarization current density are the major source of currents measured during poling and thermally stimulated discharge These charge distributions provide insight into the poling mechanisms and are directly related to E(sub A), and, alpha(sub r). Initial comparisons with experimental data show excellent correlation to the model results.

  15. Integration of Thermal Indoor Conditions into Operational Heat Health Warning Systems

    NASA Astrophysics Data System (ADS)

    Koppe, C.; Becker, P.; Pfafferott, J.

    2009-09-01

    The 2003 heat wave in Western Europe with altogether 35,000 to 50,000 deaths in Europe, several thousands of which occurred in Germany, has clearly pointed out the danger arising from long periods with high heat load. As a consequence, Germany, as many other European countries, has started to implement a Heat Health Warning System (HHWS). The German HHWS is based on the ‘Perceived Temperature'. The 'Perceived Temperature' is determined through a heat budget model of the human organism which includes the main thermophysiologically relevant mechanisms of heat exchange with the atmosphere. The most important meteorological ambience parameters included in the model are air temperature, humidity, wind speed and radiation fluxes in the short-wave and long-wave ranges. In addition to using a heat budget model for the assessment of the thermal load, the German HHWS also takes into account that the human body reacts in different ways to its thermal environment due to physiological adaptation (short-term acclimatisation) and short-term behavioural adaptation. The restriction of such an approach, like the majority of approaches used to issue heat warnings, is that the threshold for a warning is generally derived from meteorological observations and that warnings are issued on the basis of weather forecasts. Both, the observed data and the weather forecasts are only available for outside conditions. The group of people who are most at risk of suffering from a heat wave, however, are the elderly and frail who mainly stay inside. The indoor situation, which varies largely from the conditions outside, is not taken into account by most of the warning systems. To overcome this limitation the DWD, in co-operation with the Fraunhofer Institute for Solar Energy Systems, has developed a model which simulates the thermal conditions in the indoor environment. As air-conditioning in private housing in Germany is not very common, the thermal indoor conditions depend on the outside

  16. Optical fiber spectroscopy: A study of the luminescent properties of the europium ion for thermal sensors

    NASA Technical Reports Server (NTRS)

    Buoncristiani, A. Martin

    1992-01-01

    Recently, there has been interest in developing a distributed temperature sensor integrated into an optical fiber. Such a system would allow embedding of the optical fiber within or on a structural material to provide for continuous monitoring of the material's temperature. Work has already begun on the development of a temperature sensor using the temperature dependent emission spectra from the lanthanide rare earths doped into crystalline hosts. The lifetime, the linewidth and the integrated intensity of this emission are each sensitive to changes in the temperature and can provide a basis for thermometry. One concept for incorporating this phenomena into an optical fiber based sensor involves bonding the optically active material to the cladding of an optical fiber and allowing the luminescent light to couple into the the fiber by the evanescent wave. Experimental work developing this concept has already been reported. Measurements of the linewidth of Eu3+:Y2O3, diffused into a fiber, made by Albin clearly show a strong and regular dependence on temperature over the range of 300 to 1000 K. We report here on a study of the temperature dependence of the lineshape of the emission at 611 nm using the data in references. We focus attention on understanding the general behavior of the Eu3+:Y2O3 system. Building upon understanding of this system we will be able to establish the physical criterial for a good optical fiber based temperature sensor and then to examine available data on other lanthanide rare earths and transition metal ions to determine the best luminescent system for temperature sensing in an optical fiber.

  17. Thermal and Optical Modulation of the Carrier Mobility in OTFTs Based on an Azo-anthracene Liquid Crystal Organic Semiconductor.

    PubMed

    Chen, Yantong; Li, Chao; Xu, Xiuru; Liu, Ming; He, Yaowu; Murtaza, Imran; Zhang, Dongwei; Yao, Chao; Wang, Yongfeng; Meng, Hong

    2017-03-01

    One of the most striking features of organic semiconductors compared with their corresponding inorganic counterparts is their molecular diversity. The major challenge in organic semiconductor material technology is creating molecular structural motifs to develop multifunctional materials in order to achieve the desired functionalities yet to optimize the specific device performance. Azo-compounds, because of their special photoresponsive property, have attracted extensive interest in photonic and optoelectronic applications; if incorporated wisely in the organic semiconductor groups, they can be innovatively utilized in advanced smart electronic applications, where thermal and photo modulation is applied to tune the electronic properties. On the basis of this aspiration, a novel azo-functionalized liquid crystal semiconductor material, (E)-1-(4-(anthracen-2-yl)phenyl)-2-(4-(decyloxy)phenyl)diazene (APDPD), is designed and synthesized for application in organic thin-film transistors (OTFTs). The UV-vis spectra of APDPD exhibit reversible photoisomerizaton upon photoexcitation, and the thin films of APDPD show a long-range orientational order based on its liquid crystal phase. The performance of OTFTs based on this material as well as the effects of thermal treatment and UV-irradiation on mobility are investigated. The molecular structure, stability of the material, and morphology of the thin films are characterized by thermal gravimetric analysis (TGA), polarizing optical microscopy (POM), (differential scanning calorimetry (DSC), UV-vis spectroscopy, atomic force microscopy (AFM), and scanning tunneling microscopy (STM). This study reveals that our new material has the potential to be applied in optical sensors, memories, logic circuits, and functional switches.

  18. Structural, thermal, optical properties and cytotoxicity of PMMA/ZnO fibers and films: Potential application in tissue engineering

    NASA Astrophysics Data System (ADS)

    Balen, Rodrigo; da Costa, Wilian Vidotto; de Lara Andrade, Jéssica; Piai, Juliana Francis; Muniz, Edvani Curti; Companhoni, Mychelle Vianna; Nakamura, Tânia Ueda; Lima, Sandro Marcio; da Cunha Andrade, Luis Humberto; Bittencourt, Paulo Rodrigo Stival; Hechenleitner, Ana Adelina Winkler; Pineda, Edgardo Alfonso Gómez; Fernandes, Daniela Martins

    2016-11-01

    Films and fibers of PMMA/ZnO nanocomposites (100/0, 99/01, 97/03, 95/05, 90/10, and 85/15 wt.%) were produced by casting and electrospinning, respectively. Their structural, thermal, and optical properties were investigated by XRD, SEM, TGA, PAS, and PL. The incorporation of ZnO NPs reduced the diameter of PMMA fibers and the presence of beads. The surfaces of the fibers exhibited greater hydrophobicity, compared to the films, with contact angles of around 120° and 94°, respectively. PMMA films containing ZnO exhibited higher thermal stability than the pure polymer, while the corresponding fibers did not show any changes in thermal stability. The dispersion of the ZnO NPs at the surface and in the bulk of the nanocomposites appeared to be relatively homogeneous. ZnO improved the optical properties of the PMMA, with an intense absorption band near 370 nm observed for all the nanocomposites, which also exhibited luminescence with emission in the near-UV region, both attributed to ZnO. Biological tests demonstrated that fibers and films with up to 1% of ZnO exhibited good performance in the proliferation of fibroblast cells, indicating their potential for applications in tissue engineering. The fibers provided higher cell viability than the films, presumably due to their greater surface area and/or more suitable surface morphology. Nanocomposites with 15% ZnO inhibited cell proliferation, due to the cytotoxicity of the ZnO NPs. Although several applications of PMMA have been suggested by biomedical researchers, until now there have been no reports on the specific uses of fibers and films of PMMA/ZnO nanocomposites as scaffolds for fibroblast cell proliferation.

  19. Thermo-optically tuned photonic resonators with concurrent electrical connection and thermal isolation

    DOEpatents

    Lentine, Anthony L.; Kekatpure, Rohan Deodatta; Zortman, William A.; Savignon, Daniel J.

    2016-06-14

    A photonic resonator system is designed to use thermal tuning to adjust the resonant wavelength of each resonator in the system, with a separate tuning circuit associated with each resonator so that individual adjustments may be made. The common electrical ground connection between the tuning circuits is particularly formed to provide thermal isolation between adjacent resonators by including a capacitor along each return path to ground, where the presence of the capacitor's dielectric material provides the thermal isolation. The use of capacitively coupling necessarily requires the use of an AC current as an input to the heater element (conductor/resistor) of each resonator, where the RMS value of the AC signal is indicative of the amount of heat that is generated along the element and the degree of wavelength tuning that is obtained.

  20. Investigations of Thermal, Optical, and Electric Properties as a Function of Composition for {ZnS}x{Se}_{1-x} Crystals

    NASA Astrophysics Data System (ADS)

    Trefon-Radziejewska, D.; Bodzenta, J.; Toroń, B.; Drewniak, Ł.; Marasek, A.

    2015-09-01

    {ZnS}x{Se}_{1-x} single crystals with different S contents were examined. The crystals were grown by the modified Bridgman method. Thermal, optical, and electrical measurements for a solid solution of {ZnS}_{ x}{Se}_{1-x} crystals are presented and analyzed to determine the influence of composition on the thermal diffusivity, the electrical resistivity, the relative permittivity, and the energy gap. The thermal measurement was based on the thermal wave method with detection using the mirage effect. For interpretation of the experimental data, a thermal model of a layered system was adopted. The results showed that the thermal diffusivity of samples decreases with an increase of the S content x. The electrical resistivity of investigated samples was measured by the constant voltage method. The relative permittivity was determined by dielectric spectroscopy and decreased with increasing sulfur content in the ZnSe. Further, the optical bandgap of {ZnS}_{ x}{Se}_{1-x} was determined from photoluminescence spectra. Possible correlations between the thermal diffusivity, the optical bandgap, and electrical properties were studied. The obtained results showed a clear dependence of those parameters on the S concentration in the sample.

  1. Investigation of entrainment and thermal properties of a cryogenic dense-gas cloud using optical measurement techniques.

    PubMed

    Kunsch, J P; Rösgen, T

    2006-09-01

    Cryogenic dense-gas clouds have been investigated in a heavy-gas channel under controlled source and ambient conditions. Advantage is taken from new, non-intrusive optical measurement techniques (e.g. image correlation velocimetry, ICV, and background oriented Schlieren, BOS) providing detailed pictures of the temperature and velocity field in relevant regions of the cloud. The ice particles in the cloud, formed by nucleation, represent a natural seeding to be used as tracers, which have the advantage of behaving passively. Two layers can be identified in a cryogenic gas cloud: a lower cold layer, which is visible due to the presence of ice particles, and an invisible upper layer, where the ice particles have melted, mostly due to heat addition by air entrainment into the upper layer. A two-layer model has been applied to a generic element of the cloud, where detailed experimental data regarding velocity and temperature are available. Thermal- and dilution behaviour can be interpreted by means of the model which is presented in detail. A global entrainment parameter is deduced allowing a simple comparison with existing experimental information obtained by other traditional experimental techniques. The numerical values of the present entrainment parameter agree well with the correlations proposed by other authors. Thermal effects, such as heat transfer from the ground, appear to be very important. In addition, the visible height of the cloud can be predicted in relative good agreement with the experimental observations, by means of a thermal balance including the phase transition of the ice particles.

  2. Study of light-absorbing crystal birefringence and electrical modulation mechanisms for coupled thermal-optical effects.

    PubMed

    Zhou, Ji; He, Zhihong; Ma, Yu; Dong, Shikui

    2014-09-20

    This paper discusses Gaussian laser transmission in double-refraction crystal whose incident light wavelength is within its absorption wave band. Two scenarios for coupled radiation and heat conduction are considered: one is provided with an applied external electric field, the other is not. A circular heat source with a Gaussian energy distribution is introduced to present the crystal's light-absorption process. The electromagnetic field frequency domain analysis equation and energy equation are solved to simulate the phenomenon by using the finite element method. It focuses on the influence of different values such as wavelength, incident light intensity, heat transfer coefficient, ambient temperature, crystal thickness, and applied electric field strength. The results show that the refraction index of polarized light increases with the increase of crystal temperature. It decreases as the strength of the applied electric field increases if it is positive. The mechanism of electrical modulation for the thermo-optical effect is used to keep the polarized light's index of refraction constant in our simulation. The quantitative relation between thermal boundary condition and strength of applied electric field during electrical modulation is determined. Numerical results indicate a possible approach to removing adverse thermal effects such as depolarization and wavefront distortion, which are caused by thermal deposition during linear laser absorption.

  3. Fiber optic thermal/fast neutron and gamma ray scintillation detector

    DOEpatents

    Neal, John S.; Mihalczo, John T

    2007-10-30

    A system for detecting fissile and fissionable material originating external to the system includes: a .sup.6Li loaded glass fiber scintillator for detecting thermal neutrons, x-rays and gamma rays; a fast scintillator for detecting fast neutrons, x-rays and gamma rays, the fast scintillator conjoined with the glass fiber scintillator such that the fast scintillator moderates fast neutrons prior to their detection as thermal neutrons by the glass fiber scintillator; and a coincidence detection system for processing the time distributions of arriving signals from the scintillators.

  4. Synthesis, growth, thermal, optical and mechanical properties of new organic NLO crystal: L-alanine DL-malic acid

    NASA Astrophysics Data System (ADS)

    Jaikumar, D.; Kalainathan, S.; Bhagavanarayana, G.

    2009-12-01

    A new organic nonlinear optical crystal, L-alanine DL-malic acid (LADLMA), has been grown from aqueous solution by the slow cooling technique. L-alanine and DL-malic acid were used in the ratio 2:1 for synthesis. Crystals of size 24×13×8 mm 3 have been obtained in 26 days. Characterizations were carried out to study the structural, optical and mechanical properties of the grown crystals. Single crystal X-ray diffraction analysis shows that they belong to the orthorhombic system. To study the crystalline perfection of the grown crystals, high-resolution X-ray diffraction (HR-XRD) study was carried out. The vibrational frequencies of various functional groups have been derived from FTIR spectrum. Thermal behaviour of the crystal was investigated by TG-DTA analyses. Transmission spectrum has been recorded in the solution state and the cut-off frequency has been determined. Nonlinear optical property of the crystal has been confirmed using the Kurtz powder technique and a study of its second harmonic generation efficiency in comparison with KDP has been made. Knoop hardness test was carried out and its Young's modulus was calculated.

  5. Growth, spectral, optical, thermal, and mechanical behaviour of an organic single crystal: Quinolinium 2-carboxy 6-nitrophthalate monohydrate

    NASA Astrophysics Data System (ADS)

    Mohana, J.; Ahila, G.; Bharathi, M. Divya; Anbalagan, G.

    2016-09-01

    Organic single crystals of quinolinium 2-carboxy 6-nitrophthalate monohydrate (QN) were grown by slow evaporation solution growth technique using ethanol and water as a mixed solvent. X-ray powder diffraction analysis revealed that the crystal belongs to the monoclinic crystal system with space group of P21/c. The functional groups present in the crystallized material confirmed its molecular structure. The optical transparency range and the lower cutoff wavelength were identified from the UV-vis spectrum. The optical constants were determined by UV-visible transmission spectrum at normal incidence, measured over the 200-700 nm spectral range. The dispersion of the refractive index was discussed in terms of the single-oscillator Wemple and DiDomenico model. The calculated HOMO and LUMO energies show that the charge transfer occur within the molecule. Electronic excitation properties were discussed within the framework of two level model on the basis of an orbital analysis. The nonlinear optical absorption coefficient (β) and nonlinear refraction (n2) of QN was measured by Z-scan technique and reported here. Thermal stability of QN was determined using TGA/DSC curves. Vicker's microhardness studies were carried out on the (1 1 ̅0) plane to understand the mechanical properties of the grown crystal. The microhardness measurements showed a Vickers hardness value as 18.4 kg/mm2 which is comparable to well-known organic crystal, urea.

  6. Optical parameters of ternary Te15(Se100-xBix)85 thin films deposited by thermal evaporation

    NASA Astrophysics Data System (ADS)

    Kumar, Kameshwar; Sharma, Pankaj; Katyal, S. C.; Thakur, Nagesh

    2011-10-01

    Thin films of Te15(Se100-xBix)85 (x=0, 1, 2, 3, 4 and 5 at.%) glassy alloys were deposited by thermal evaporation (at 10-4 Pa) from bulk samples. Optical characterization of the films was done by analysing their transmission spectra taken in the spectral range 400-2300 nm. Swanepoel's method was used to calculate the refractive index (n) and extinction coefficient (k). It was found that the refractive index increases with an increase in Bi content. The Wemple-DiDomenico single-oscillator approach was used to calculate the average band gap energy (Eo), dispersion energy (Ed) and static refractive index (no). The absorption coefficient (α) and film thickness were calculated from the transmission spectra of the films. The optical band gap (Eg) was estimated using Tauc's extrapolation and was found to decrease from 1.37 to 1.21 eV with Bi addition from 0 to 5 at.% in glassy alloys. The decrease in optical band gap is explained on the basis of the decrease in cohesive energy of the samples and the difference of electronegativity of the atoms involved. The real (ɛr) and imaginary parts (ɛi) of the dielectric constant for the films were also calculated and reported.

  7. Synthesis, growth, structural, optical and thermal properties of a new organic nonlinear optical crystal: 2-amino 5-chloropyridinium-L-tartarate

    NASA Astrophysics Data System (ADS)

    Jayanalina, T.; Rajarajan, G.; Boopathi, K.; Sreevani, K.

    2015-09-01

    A new organic nonlinear optical crystal 2-amino-5-chloropyridinium-L-tartarate [2A5CPLTA] has been synthesized and the crystals were grown by slow evaporation solution technique at room temperature using methanol as solvent. The crystal structure of the title compound has been determined by the single crystal X-ray diffraction study and it belongs to the monoclinic system with noncentrosymmetric space group P21. The presence of functional groups was ascertained by Fourier transform infrared analysis. The transmittance and lower cut off of the grown crystal was ascertained by the UV-vis-NIR spectroscopy. Thermal studies reveled that 2A5CPLTA crystal is thermally stable up to 144 °C. The dielectric measurements of the grown crystal were carried out with different frequencies and temperatures. Vickers micro hardness measurement was carried out to study the mechanical behavior of the grown crystal. The second harmonic generation of the title crystal was confirmed by the Kurtz-Perry powder test employing the Nd: YAG laser as the source.

  8. Optically Induced Thermal Gradients for Protein Characterization in Nanolitre-scale Samples in Microfluidic Devices

    PubMed Central

    Sagar, D. M.; Aoudjane, Samir; Gaudet, Matthieu; Aeppli, Gabriel; Dalby, Paul A.

    2013-01-01

    Proteins are the most vital biological functional units in every living cell. Measurement of protein stability is central to understanding their structure, function and role in diseases. While proteins are also sought as therapeutic agents, they can cause diseases by misfolding and aggregation in vivo. Here we demonstrate a novel method to measure protein stability and denaturation kinetics, on unprecedented timescales, through optically-induced heating of nanolitre samples in microfluidic capillaries. We obtain protein denaturation kinetics as a function of temperature, and accurate thermodynamic stability data, from a snapshot experiment on a single sample. We also report the first experimental characterization of optical heating in controlled microcapillary flow, verified by computational fluid dynamics modelling. Our results demonstrate that we now have the engineering science in hand to design integrated all-optical microfluidic chips for a diverse range of applications including in-vitro DNA amplification, healthcare diagnostics, and flow chemistry. PMID:23823279

  9. Structural, optical, thermal and mechanical characterization of an organic nonlinear optical material: 4-methyl-3-nitrobenzoic acid single crystal

    NASA Astrophysics Data System (ADS)

    Bharathi, M. Divya; Ahila, G.; Mohana, J.; Chakkaravarthi, G.; Anbalagan, G.

    2016-11-01

    Organic single crystals of 4-methyl-3-nitrobenzoic acid (4M3N) have been grown by slow evaporation solution growth technique at room temperature. The single crystal X-ray diffraction study reveals that 4M3N crystallizes in monoclinic system with space group P21/n. The crystalline perfection of the crystal was analyzed by high resolution X-ray diffraction (HRXRD) measurements. The functional groups present in 4M3N have been identified from FT-IR and FT-Raman spectra. The lower cut-off wavelength of 4M3N is found to be 404 nm and the optical band gap is calculated as 2.91 eV. The refractive index shows normal behavior with wavelength. The physio chemical changes, decomposition and stability of the 4M3N compound were established by TG-DTA studies. Vickers microhardness measurement concludes that 4M3N belongs to soft material (n=2.5) category. The LDT value is found to be higher than that of KDP and some of the important organic NLO materials. The third order nonlinear refractive index and nonlinear absorption coefficient of the 4M3N have been measured by Z-scan studies. The imaginary and real parts of the third-order susceptibility values were determined as Im χ3=9.129×10-11 esu and Re χ3=1.4034×10-9 esu respectively. The dislocation density was calculated to be 3.0448×106 cm-2 which indicates the quality of the crystal.

  10. Thermal modeling of the NASA-Ames Research Center Cryogenic Optical Test Facility and a single-arch, fused-natural-quartz mirror

    NASA Technical Reports Server (NTRS)

    Ng, Y. S.; Augason, Gordon C.; Young, Jeffrey A.; Howard, Steven D.; Melugin, Ramsey K.

    1990-01-01

    A thermal model of the dewar and optical system of the Cryogenic Optical Test Facility at NASA-Ames Research Center was developed using the computer codes SINDA and MONTE CARLO. The model was based on the geometry, boundary conditions, and physical properties of the test facility and was developed to investigate heat transfer mechanisms and temperatures in the facility and in test mirrors during cryogenic optical tests. A single-arch, fused-natural-quartz mirror was the first mirror whose thermal loads and temperature distributions were modeled. From the temperature distribution, the thermal gradients in the mirror were obtained. The model predicted that a small gradient should exist for the single arch mirror. This was later verified by the measurement of mirror temperatures. The temperatures, predicted by the model at various locations within the dewar, were in relatively good agreement with the measured temperatures. The model is applicable to both steady-state and transient cooldown operations.

  11. Temperature-Dependent Compensation and Optical Quenching by Thermal Oxygen Donors in Germanium

    NASA Technical Reports Server (NTRS)

    Watson, D.; Guptill, M.; Huffman, J.; Krabach, T.; Raines, S.

    1994-01-01

    Photothermal ionization spectroscopy of germanium, doped in the impurity-band conduction range with gallium acceptors and with thermal oxygen donors, reveals that the donors and acceptors compensate each other at temperatures higher than about 5K, but that the impurities coexist as neutral donors and acceptors at lower temperatures.

  12. Acoustic emission detection with fiber optical sensors for dry cask storage health monitoring

    NASA Astrophysics Data System (ADS)

    Lin, Bin; Bao, Jingjing; Yu, Lingyu; Giurgiutiu, Victor

    2016-04-01

    The increasing number, size, and complexity of nuclear facilities deployed worldwide are increasing the need to maintain readiness and develop innovative sensing materials to monitor important to safety structures (ITS). In the past two decades, an extensive sensor technology development has been used for structural health monitoring (SHM). Technologies for the diagnosis and prognosis of a nuclear system, such as dry cask storage system (DCSS), can improve verification of the health of the structure that can eventually reduce the likelihood of inadvertently failure of a component. Fiber optical sensors have emerged as one of the major SHM technologies developed particularly for temperature and strain measurements. This paper presents the development of optical equipment that is suitable for ultrasonic guided wave detection for active SHM in the MHz range. An experimental study of using fiber Bragg grating (FBG) as acoustic emission (AE) sensors was performed on steel blocks. FBG have the advantage of being durable, lightweight, and easily embeddable into composite structures as well as being immune to electromagnetic interference and optically multiplexed. The temperature effect on the FBG sensors was also studied. A multi-channel FBG system was developed and compared with piezoelectric based AE system. The paper ends with conclusions and suggestions for further work.

  13. Structural-Thermal-Optical-Performance (STOP) Model Development and Analysis of a Field-widened Michelson Interferometer

    NASA Technical Reports Server (NTRS)

    Scola, Salvatore J.; Osmundsen, James F.; Murchison, Luke S.; Davis, Warren T.; Fody, Joshua M.; Boyer, Charles M.; Cook, Anthony L.; Hostetler, Chris A.; Seaman, Shane T.; Miller, Ian J.; Welch, Wayne C.; Kosmer, Adam R.

    2014-01-01

    An integrated Structural-Thermal-Optical-Performance (STOP) model was developed for a field-widened Michelson interferometer which is being built and tested for the High Spectral Resolution Lidar (HSRL) project at NASA Langley Research Center (LaRC). The performance of the interferometer is highly sensitive to thermal expansion, changes in refractive index with temperature, temperature gradients, and deformation due to mounting stresses. Hand calculations can only predict system performance for uniform temperature changes, under the assumption that coefficient of thermal expansion (CTE) mismatch effects are negligible. An integrated STOP model was developed to investigate the effects of design modifications on the performance of the interferometer in detail, including CTE mismatch, and other three- dimensional effects. The model will be used to improve the design for a future spaceflight version of the interferometer. The STOP model was developed using the Comet SimApp'TM' Authoring Workspace which performs automated integration between Pro-Engineer®, Thermal Desktop®, MSC Nastran'TM', SigFit'TM', Code V'TM', and MATLAB®. This is the first flight project for which LaRC has utilized Comet, and it allows a larger trade space to be studied in a shorter time than would be possible in a traditional STOP analysis. This paper describes the development of the STOP model, presents a comparison of STOP results for simple cases with hand calculations, and presents results of the correlation effort to bench-top testing of the interferometer. A trade study conducted with the STOP model which demonstrates a few simple design changes that can improve the performance seen in the lab is also presented.

  14. Structural-Thermal-Optical-Performance (STOP) model development and analysis of a field-widened Michelson interferometer

    NASA Astrophysics Data System (ADS)

    Scola, Salvatore J.; Osmundsen, James F.; Murchison, Luke S.; Davis, Warren T.; Fody, Joshua M.; Boyer, Charles M.; Cook, Anthony L.; Hostetler, Chris A.; Seaman, Shane T.; Miller, Ian J.; Welch, Wayne C.; Kosmer, Adam R.

    2014-09-01

    An integrated Structural-Thermal-Optical-Performance (STOP) model was developed for a field-widened Michelson interferometer which is being built and tested for the High Spectral Resolution Lidar (HSRL) project at NASA Langley Research Center (LaRC). The performance of the interferometer is highly sensitive to thermal expansion, changes in refractive index with temperature, temperature gradients, and deformation due to mounting stresses. Hand calculations can only predict system performance for uniform temperature changes, under the assumption that coefficient of thermal expansion (CTE) mismatch effects are negligible. An integrated STOP model was developed to investigate the effects of design modifications on the performance of the interferometer in detail, including CTE mismatch, and other threedimensional effects. The model will be used to improve the design for a future spaceflight version of the interferometer. The STOP model was developed using the Comet SimApp™ Authoring Workspace which performs automated integration between Pro-Engineer®, Thermal Desktop®, MSC Nastran™, SigFit™, Code V™, and MATLAB®. This is the first flight project for which LaRC has utilized Comet, and it allows a larger trade space to be studied in a shorter time than would be possible in a traditional STOP analysis. This paper describes the development of the STOP model, presents a comparison of STOP results for simple cases with hand calculations, and presents results of the correlation effort to bench-top testing of the interferometer. A trade study conducted with the STOP model which demonstrates a few simple design changes that can improve the performance seen in the lab is also presented.

  15. Investigation of Thermal Effects of Photocoagulation on Retinal Tissue Using Fine-Motion-Sensitive Dynamic Optical Coherence Tomography

    PubMed Central

    Kurokawa, Kazuhiro; Makita, Shuichi; Yasuno, Yoshiaki

    2016-01-01

    To enable an objective evaluation of photocoagulation, we characterize thermal tissue changes induced by laser irradiation with different laser parameters using optical coherence tomography (OCT). Spectral-domain OCT with a newly developed image processing method was used to monitor the thermal changes of ex vivo porcine retina. A sequence of OCT B-scans was obtained at the same retinal position simultaneously with the photocoagulation. Cross-sectional tissue displacement maps with respect to an OCT image taken before laser irradiation were computed for images taken before, during, and after laser irradiation, by using a correlation-based custom algorithm. Cross-sectional correlation maps (OCT correlation maps) were also computed from an OCT image taken before laser irradiation as a base-line to visualize alterations of tissue microstructure induced by laser irradiation. By systematically controlling laser power and exposure times, tissue displacements and structural changes of 200 retinal regions of 10 porcine eyes were characterized. Thermal tissue changes were characterized by B-scan images, OCT correlation maps, and tissue displacement maps. Larger tissue deformation was induced with higher laser power and shorter exposure time, while the same total laser energy (10 mJ) was applied. The measured tissue displacements revealed the complicated dynamics of tissue displacements. Three types of dynamics were observed; lateral expansion, lateral constriction, and a type showing more complicated dynamics. The results demonstrated the ability of this OCT-based method to evaluate retinal changes induced by laser irradiation. This evaluation could lead to further understanding of thermal effects, and increasing reproducibility of photocoagulation therapy. PMID:27271952

  16. Laser geodynamic satellite thermal/optical/vibrational analyses and testing. Volume 1: Executive summary. [retroreflector performance

    NASA Technical Reports Server (NTRS)

    1975-01-01

    A program to study a LAGEOS retroreflector design change for optical performance improvement is described. The study objectives, the study approach, the principal assumptions, the type of basic data generated, and the significant results are discussed. Study limitations, implications for research, and suggested additional efforts are also summarized.

  17. Structural health monitoring for insulation panels of LNG carriers using fiber optic sensors

    NASA Astrophysics Data System (ADS)

    Kim, Myung Hyun; Son, Young Joo; Kang, Sung Won; Lee, Jae Myung; Na, Sung Soo

    2006-03-01

    The aim of this study is to investigate dynamic failure initiation and failure modes of insulation panels of LNG carriers. Insulation panels of LNG cargo tanks may include mechanical failures such as cracks as well as delaminations within the layers due to impact sloshing loads and fatigue loadings, and these failures cause a significant decrease of structural integrity. In this study, a structural health monitoring system, employing fiber optic sensors is developed for monitoring various failures that can occur in LNG insulation panels. Fiber optic sensors have the advantage of being embedded inside of insulation panels. The signal of embedded fiber optic sensors is used to calculate the strain of insulation panels and is processed by digital filtering to identify damage initiations. It has been observed that the presence of defects and delaminations produce noticeable changes in the strain measurement in a predictable manner. In addition, fiber optic sensors are used to measure static and dynamic strain variations of insulation panels with and without damage. It is expected that this study will be used as a fundamental study for the safety assessment of the LNG insulation panels.

  18. Effect of amino acid dopants on the spectral, optical, mechanical and thermal properties of potassium acid phthalate crystals for possible optoelectronic and frequency doubling applications

    NASA Astrophysics Data System (ADS)

    Prakash, J. Thomas Joseph; Gnanaraj, J. Martin Sam; Dhavud, S. Shek; Ekadevasena, S.

    2015-09-01

    Undoped and amino acid (L-Arginine and L-Valine) doped KAP crystals were grown by slow evaporation solution growth technique. The changes in the structural, spectral, optical, mechanical and thermal properties were observed. The sharp prominent peaks in the indexed powder XRD pattern confirms the crystalline nature of the sample. Optical studies reveal that the crystal is transparent in the entire visible light region. Thermal stability was checked by TG/DTA analysis. The mechanical stability was evaluated from Vicker's microhardness test. The SHG efficiency for the title materials was tested with different particle sizes by the Kurtz and Perry powder method, which established the existence of phase matching.

  19. Effect of thermal annealing on structure and optical band gap of Se{sub 66}Te{sub 25}In{sub 9} thin films

    SciTech Connect

    Dwivedi, D. K.; Pathak, H. P.; Shukla, Nitesh; Kumar, Vipin

    2015-05-15

    Thin films of a-Se{sub 66}Te{sub 25}In{sub 9} have been deposited onto a chemically cleaned glass substrate by thermal evaporation technique under vacuum. Glassy nature of the films has been ascertained by X-ray diffraction pattern. The analysis of absorption spectra, measured at normal incidence, in the spectral range 400-1100 nm has been used for the optical characterization of thin films under investigation. The effect of thermal annealing on structure and optical band gap (E{sub g}) of a-Se{sub 66}Te{sub 25}In{sub 9} have been studied.

  20. Surface Chemistry Manipulation of Gold Nanorods Displays High Cellular Uptake In Vitro While Preserving Optical Properties for Bio-Imaging and Photo-Thermal Applications

    DTIC Science & Technology

    2016-03-28

    PROPERTIES FOR BIO-IMAGING AND PHOTO-THERMAL APPLICATIONS ANTHONY B. POLITO III, Maj, USAF, BSC, PhD, MT(ASCP)SBB March 2016 Final Report for March...HIGH CELLULAR UPTAKE IN VITRO WHILE PRESERVING OPTICAL PROPERTIES FOR BIO-IMAGING AND PHOTO-THERMAL APPLICATIONS . 5a. CONTRACT NUMBER 5b...NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Air Force Institute of Technology (AFIT) Civilian Institution

  1. Pore size and concentration effect of mesoporous silica nanoparticles on the coefficient of thermal expansion and optical transparency of poly(ether sulfone) films.

    PubMed

    Vo, Nhat Tri; Patra, Astam K; Kim, Dukjoon

    2017-01-18

    Mesoporous silica nanoparticles (MSNs) with uniform size (<50 nm) yet with different pore diameters were synthesized, and used as fillers in poly(ether sulfone) (PES) films in order to decrease their coefficient of thermal expansion (CTE) without sacrificing optical transparency. Here, both CTE and optical transparency of the MSN/PES nanocomposite films gradually decreased with increasing MSN concentration. The PES films containing MSNs with larger pores showed the best performance in CTE and optical transparency. While the CTE decreased by 32.3% with increasing MSN content up to 0.5 wt%, the optical transparency decreased by only less than 6.9% because of the small and uniform particle size of less than 50 nm, which minimizes light scattering. This pore size effect is more clearly observed via an annealing process, which enables the polymer chains to slowly move and fill in the free volume in the pores of the MSN, and thus restricts the thermal motion. The effect of the silica nanoparticles was investigated not only on the thermal stability but also on the mechanical stability. We expect the MSNs synthesized in this study to be used as a promising filler to enhance the thermal and mechanical stability of the PES substrate without sacrificing its optical transparency.

  2. An all fiber-optic multi-parameter structure health monitoring system.

    PubMed

    Hu, Chennan; Yu, Zhihao; Wang, Anbo

    2016-09-05

    In this work, we present an all fiber-optics based multi-parameter structure health monitoring system, which is able to monitor strain, temperature, crack and thickness of metal structures. This system is composed of two optical fibers, one for laser-acoustic excitation and the other for acoustic detection. A nano-second 1064 nm pulse laser was used for acoustic excitation and a 2 mm fiber Bragg grating was used to detect the acoustic vibration. The feasibility of this system was demonstrated on an aluminum test piece by the monitoring of the temperature, strain and thickness changes, as well as the appearance of an artificial crack. The multiplexing capability of this system was also preliminarily demonstrated.

  3. Evaluation of the carbon content of aerosols from the burn- ing of biomass in the Brazilian Amazon using thermal, op- tical and thermal-optical analysis methods

    SciTech Connect

    Soto-Garcia, Lydia L.; Andreae, Meinrat O.; Andreae, Tracey W.; taxo, Paulo Ar-; Maenhaut, Willy; Kirchstetter, Thomas; Novakov, T.; Chow, Judith C.; Mayol-Bracero, Olga L.

    2011-06-03

    Aerosol samples were collected at a pasture site in the Amazon Basin as part of the project LBA-SMOCC-2002 (Large-Scale Biosphere-Atmosphere Experiment in Amazonia - Smoke Aerosols, Clouds, Rainfall and Climate: Aerosols from Biomass Burning Perturb Global and Regional Climate). Sampling was conducted during the late dry season, when the aerosol composition was dominated by biomass burning emissions, especially in the submicron fraction. A 13-stage Dekati low-pressure impactor (DLPI) was used to collect particles with nominal aerodynamic diameters (D{sub p}) ranging from 0.03 to 0.10 m. Gravimetric analyses of the DLPI substrates and filters were performed to obtain aerosol mass concentrations. The concentrations of total, apparent elemental, and organic carbon (TC, EC{sub a}, and OC) were determined using thermal and thermal-optical analysis (TOA) methods. A light transmission method (LTM) was used to determine the concentration of equivalent black carbon (BC{sub e}) or the absorbing fraction at 880 nm for the size-resolved samples. During the dry period, due to the pervasive presence of fires in the region upwind of the sampling site, concentrations of fine aerosols (D{sub p} < 2.5 {mu}m: average 59.8 {mu}g m{sup -3}) were higher than coarse aerosols (D{sub p} > 2.5 {mu}m: 4.1 {mu}g m{sup -3}). Carbonaceous matter, estimated as the sum of the particulate organic matter (i.e., OC x 1.8) plus BC{sub e}, comprised more than 90% to the total aerosol mass. Concentrations of EC{sub a} (estimated by thermal analysis with a correction for charring) and BCe (estimated by LTM) averaged 5.2 {+-} 1.3 and 3.1 {+-} 0.8 {mu}g m{sup -3}, respectively. The determination of EC was improved by extracting water-soluble organic material from the samples, which reduced the average light absorption {angstrom} exponent of particles in the size range of 0.1 to 1.0 {mu}m from > 2.0 to approximately 1.2. The size-resolved BC{sub e} measured by the LTM showed a clear maximum between 0.4 and

  4. Direct synthesis and characterization of optically transparent conformal zinc oxide nanocrystalline thin films by rapid thermal plasma CVD.

    PubMed

    Pedersen, Joachim D; Esposito, Heather J; Teh, Kwok Siong

    2011-10-31

    We report a rapid, self-catalyzed, solid precursor-based thermal plasma chemical vapor deposition process for depositing a conformal, nonporous, and optically transparent nanocrystalline ZnO thin film at 130 Torr (0.17 atm). Pure solid zinc is inductively heated and melted, followed by ionization by thermal induction argon/oxygen plasma to produce conformal, nonporous nanocrystalline ZnO films at a growth rate of up to 50 nm/min on amorphous and crystalline substrates including Si (100), fused quartz, glass, muscovite, c- and a-plane sapphire (Al2O3), gold, titanium, and polyimide. X-ray diffraction indicates the grains of as-deposited ZnO to be highly textured, with the fastest growth occurring along the c-axis. The individual grains are observed to be faceted by (103) planes which are the slowest growth planes. ZnO nanocrystalline films of nominal thicknesses of 200 nm are deposited at substrate temperatures of 330°C and 160°C on metal/ceramic substrates and polymer substrates, respectively. In addition, 20-nm- and 200-nm-thick films are also deposited on quartz substrates for optical characterization. At optical spectra above 375 nm, the measured optical transmittance of a 200-nm-thick ZnO film is greater than 80%, while that of a 20-nm-thick film is close to 100%. For a 200-nm-thick ZnO film with an average grain size of 100 nm, a four-point probe measurement shows electrical conductivity of up to 910 S/m. Annealing of 200-nm-thick ZnO films in 300 sccm pure argon at temperatures ranging from 750°C to 950°C (at homologous temperatures between 0.46 and 0.54) alters the textures and morphologies of the thin film. Based on scanning electron microscope images, higher annealing temperatures appear to restructure the ZnO nanocrystalline films to form nanorods of ZnO due to a combination of grain boundary diffusion and bulk diffusion.PACS: films and coatings, 81.15.-z; nanocrystalline materials, 81.07.Bc; II-VI semiconductors, 81.05.Dz.

  5. Distributed Fiber Optic Sensor for On-Line Monitoring of Coal Gasifier Refractory Health

    SciTech Connect

    Wang, Anbo; Yu, Zhihao

    2015-11-30

    This report summarizes technical progress on the program “Distributed Fiber Optic Sensor for On-Line Monitoring of Coal Gasifier Refractory Health,” funded by the National Energy Technology Laboratory of the U.S. Department of Energy, and performed by the Center for Photonics Technology of the Bradley Department of Electrical and Computer Engineering at Virginia Tech. The scope of work entails analyses of traveling grating generation technologies in an optical fiber, as well as the interrogation of the gratings to infer a distributed temperature along the fiber, for the purpose of developing a real-time refractory health condition monitoring technology for coal gasifiers. During the project period, which is from 2011-2015, three different sensing principles were studied, including four-wave mixing (FWM), coherent optical time-domain reflectometer (C-OTDR) and Brillouin optical time-domain analysis (BOTDA). By comparing the three methods, the BOTDA was selected for further development into a complete bench-top sensing system for the proposed high-temperature sensing application. Based on the input from Eastman Chemical, the industrial collaborator on this project, a cylindrical furnace was designed and constructed to simulate typical gasifier refractory temperature conditions in the laboratory, and verify the sensor’s capability to fully monitor refractory conditions on the back-side at temperatures up to 1000°C. In the later stages of the project, the sensing system was tested in the simulated environment for its sensing performance and high-temperature survivability. Through theoretical analyses and experimental research on the different factors affecting the sensor performance, a sensor field deployment strategy was proposed for possible future sensor field implementations.

  6. Martian mesoscale circulations induced by variations in surface optical and thermal characteristics: A numerical study

    NASA Technical Reports Server (NTRS)

    Siili, Tero; Savijarvi, H.

    1993-01-01

    According to Mariner 9 and Viking observations the surface albedo and the thermal inertia of Mars' surface vary substantially, and fairly large gradients also occur. The Syrtis Major region is bounded in the west by high-albedo cratered terrain and in the east by Isidis Planitia, a high-albedo plateau. Sinus Meridiani, centered at 0 degrees W 5 degrees S, is almost surrounded by higher albedo regions with sharp boundaries, and Acidalia Planitia, between 10 and 50 degrees W and north of 35 degrees N, has sharp albedo boundaries to the east and west. Observational and modeling studies, e.g., on Australian dry salt lake coasts, have shown that discontinuities and gradients in surface properties can induce mesoscale circulations. We have used a version of the DMUH mesoscale model to simulate atmospheric circulations induced by variations in the reflectivity and in the thermal inertia of the martian surface.

  7. Reentrant Structural and Optical Properties and Large Positive Thermal Expansion in Perovskite Formamidinium Lead Iodide.

    PubMed

    Fabini, Douglas H; Stoumpos, Constantinos C; Laurita, Geneva; Kaltzoglou, Andreas; Kontos, Athanassios G; Falaras, Polycarpos; Kanatzidis, Mercouri G; Seshadri, Ram

    2016-12-05

    The structure of the hybrid perovskite HC(NH2 )2 PbI3 (formamidinium lead iodide) reflects competing interactions associated with molecular motion, hydrogen bonding tendencies, thermally activated soft octahedral rotations, and the propensity for the Pb(2+) lone pair to express its stereochemistry. High-resolution synchrotron X-ray powder diffraction reveals a continuous transition from the cubic α-phase (Pm3‾ m, #221) to a tetragonal β-phase (P4/mbm, #127) at around 285 K, followed by a first-order transition to a tetragonal γ-phase (retaining P4/mbm, #127) at 140 K. An unusual reentrant pseudosymmetry in the β-to-γ phase transition is seen that is also reflected in the photoluminescence. Around room temperature, the coefficient of volumetric thermal expansion is among the largest for any extended crystalline solid.

  8. Thermal and optical study of semiconducting CNTs-doped nematic liquid crystalline material

    NASA Astrophysics Data System (ADS)

    Vimal, T.; Singh, D. P.; Gupta, S. K.; Pandey, S.; Agrahari, K.; Manohar, R.

    2016-06-01

    We report the thermal and spectroscopic analysis of the carbon nanotubes (CNTs)-doped nematic liquid crystal (NLC) material. The CNTs have been oriented in the p-ethoxybenzylidene p-butylaniline NLC. The thermal study of the CNTs doped nematic mixtures shows a significant decrease in the isotropic to nematic phase transition temperature. However higher doping concentration of CNTs has led to the further increase in transition temperature. The UV-Visible spectroscopy has been attempted on the CNTs/NLC mixtures at room temperature. The investigated NLC present one absorption band corresponding to π-π* electronic transition. A red shift of λmax with the increasing concentration of CNTs in the mixture has been observed. The band gap of NLC has been found to decrease after the doping of CNTs. The absorbance was measured for the UV light, polarized parallel and perpendicular to the LC director in the planar aligned cell.

  9. The influence of thermal annealing on the optical properties of nanocrystalline zinc sulfide films

    SciTech Connect

    Krylov, P. N.; Gilmutdinov, F. Z.; Romanov, E. A.; Fedotova, I. V.

    2011-11-15

    The influence of thermal annealing on the photoluminescence, electroluminescence, and the transmission and reflection spectra in nanocrystalline zinc sulfide films has been studied. All the samples exhibit a broad emission band, the intensity of which depends on the annealing temperature. It is shown that luminophors, the crystal lattice of which includes imperfections that appeared in the transition from wurtzite to sphalerite, feature the highest emission intensity.

  10. Following bioactive glass behavior beyond melting temperature by thermal and optical methods

    NASA Astrophysics Data System (ADS)

    Chatzistavrou, X.; Zorba, T.; Kontonasaki, E.; Chrissafis, K.; Koidis, P.; Paraskevopoulos, K. M.

    2004-04-01

    The thermal behavior of a well known bioactive glass, Bioglass®, is examined beyond its melting temperature as the crystallization and sintering of bioactive glass may influence its bioactivity and cellular reactions. Differential thermal analysis (DTA) followed by thermogravimetric analysis (TGA) was used to determine the glass transition (Tg), the crystallization (Tc), the melting (Tm) temperatures and the weight changes. The characterization of bioactive glass before and after the thermal treatment at different characteristic temperatures was accomplished with Fourier transform infrared spectroscopy (FTIR). All the phases, during the heating of the material until an exact temperature beyond its melting temperature were determined. A progressive increase of its crystallization degree was observed, during treatment up to 1200 °C. At this temperature a number of successive crystallizations and fusions take place. At higher temperatures the formation of amorphous Bioglass® with simultaneous appearance of new phases is observed, favouring the bioactivity that in glass-ceramics is influenced by the different phases present.

  11. Ultralow thermal sensitivity of phase and propagation delay in hollow core optical fibres

    PubMed Central

    Slavík, Radan; Marra, Giuseppe; Fokoua, Eric Numkam; Baddela, Naveen; Wheeler, Natalie V.; Petrovich, Marco; Poletti, Francesco; Richardson, David J.

    2015-01-01

    Propagation time through an optical fibre changes with the environment, e.g., a change in temperature alters the fibre length and its refractive index. These changes have negligible impact in many key fibre applications, e.g., telecommunications, however, they can be detrimental in many others. Examples are fibre-based interferometry (e.g., for precise measurement and sensing) and fibre-based transfer and distribution of accurate time and frequency. Here we show through two independent experiments that hollow-core photonic bandgap fibres have a significantly smaller sensitivity to temperature variations than traditional solid-core fibres. The 18 times improvement observed, over 3 times larger than previously reported, makes them the most environmentally insensitive fibre technology available and a promising candidate for many next-generation fibre systems applications that are sensitive to drifts in optical phase or absolute propagation delay. PMID:26490424

  12. Organic chromophore with enhanced optical nonlinearity and thermal stability by introducing julolidine as donor group.

    PubMed

    Ju, Hyun Kyung; Lee, Changjin; Kim, Dong Wook

    2009-12-01

    We prepared a nonlinear optical chromophore (Ju-TCF) with julolidine moiety as a donor and compared it with the chromophore (St-TCF) with the dialkyl-attached aminobenzene as a donor. The MOPAC calculations showed that the figure of merit (microbeta0) of Ju-TCF was estimated 70% larger than St-TCF. Based on the TGA result, Ju-TCF displayed on-set of degradation at 261 degrees C, which was about 30 degrees C higher than St-TCF (234 degrees C). The julolidine chromophore blended in the polymer exhibited 32 pm/V of electro-optic coefficient, which was 30% larger than St-TCF at the same molar chromophore content.

  13. Investigation of high thermal contact conductance at low contact pressure for high-heat-load optical elements of synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Takeuchi, T.; Tanaka, M.; Ohashi, H.; Goto, S.

    2013-09-01

    We measured the thermal-contact-conductance (TCC) of indirect cooling components in synchrotron radiation beamlines. To reduce the strain on the optical element, we explored conditions for insertion materials with a high TCC in region with low contact pressures of 0.1-1.0 MPa. We examined the TCC at the interface between oxygen-free copper (OFC) and insertion materials such as indium, graphite, and gold foil. The TCC depended on the hardness and thickness of the insertion material. Thin indium (20 μm thick) showed the highest TCC. Nickel and gold passivation on the OFC surface reduced the TCC to 30% of that for the bare OFC. Future work will involve exploring the passivation conditions of OFC for higher TCC is and measuring the TCC under cryogenic-cooling conditions.

  14. Synthesis, spectral, thermal, optical and theoretical studies of (2E,6E)-2-benzylidene-6-(4-methoxybenzylidene)cyclohexanone.

    PubMed

    Meenatchi, V; Muthu, K; Rajasekar, M; Meenakshisundaram, Sp

    2014-01-01

    Single crystals of (2E,6E)-2-benzylidine-6-(4-methoxybenzylidine)cyclohexanone are grown by slow evaporation of ethanolic solution at room temperature. The characteristic functional groups present in the molecule are confirmed by Fourier transform infrared and Fourier transform Raman analyses. The scanning electron microscopy study reveals the surface morphology of the material. Thermogravimetric/differential thermal analysis study reveals the purity of the material and the crystal is transparent in the visible region having a lower optical cut-off at ∼487nm. The second harmonic generation efficiency of as-grown material is estimated by Kurtz and Perry technique. Optimized geometry has been derived using Hartree-Fock calculations performed at the level 6-31G (d,p) and the first-order molecular hyperpolarizability (β) is estimated. The specimen is further characterized by nuclear magnetic resonance spectroscopy.

  15. Fiber-optic combined FPI/FBG sensors for monitoring of radiofrequency thermal ablation of liver tumors: ex vivo experiments.

    PubMed

    Tosi, Daniele; Macchi, Edoardo Gino; Braschi, Giovanni; Cigada, Alfredo; Gallati, Mario; Rossi, Sandro; Poeggel, Sven; Leen, Gabriel; Lewis, Elfed

    2014-04-01

    We present a biocompatible, all-glass, 0.2 mm diameter, fiber-optic probe that combines an extrinsic Fabry-Perot interferometry and a proximal fiber Bragg grating sensor; the probe enables dual pressure and temperature measurement on an active 4 mm length, with 40 Pa and 0.2°C nominal accuracy. The sensing system has been applied to monitor online the radiofrequency thermal ablation of tumors in liver tissue. Preliminary experiments have been performed in a reference chamber with uniform heating; further experiments have been carried out on ex vivo porcine liver, which allowed the measurement of a steep temperature gradient and monitoring of the local pressure increase during the ablation procedure.

  16. Design route and optical analysis of curved compound-eyes towards thermal reflow and hot embossing fabrication processes

    NASA Astrophysics Data System (ADS)

    Di, Si; Jin, Jian

    2016-10-01

    Compound-eyes have several characters such as big vision field angle, small volume and multi-channels imaging. Therefore, it is applicable in the field of machine vision. Based on the thermal reflow and hot embossing technology, this paper put forward a new route to design the compound-eyes imaging system and analysis the optical aberration by use of ray tracing. Furthermore, in order to getting the optimal imaging ability, non-homogeneous micro-lens array is adopted as the compound-eyes structure. The ray-tracing results show that the design scheme can reach the expected requirements. Therefore, this paper can guide the design of compound-eyes imaging system.

  17. Superior reinforcement effect of TEMPO-oxidized cellulose nanofibrils in polystyrene matrix: optical, thermal, and mechanical studies.

    PubMed

    Fujisawa, Shuji; Ikeuchi, Tomoyasu; Takeuchi, Miyuki; Saito, Tsuguyuki; Isogai, Akira

    2012-07-09

    Polystyrene (PS) composites reinforced with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibrils (TOCNs) with various weight ratios were fabricated by casting and vacuum-drying mixtures of PS/N,N-dimethylformamide (DMF) solution and TOCN/DMF dispersion. TOCNs of 3 to 4 nm width were dispersed homogeneously at the individual nanofibril level in the PS matrix, such that the TOCN/PS nanocomposite films exhibited high optical transparencies and their tensile strengths, elastic moduli, and thermal dimensional stabilities increased with increasing TOCN content. Dynamic mechanical analysis showed that the storage modulus of the TOCN/PS films increased significantly with TOCN content above the glass-transition temperature of PS by the formation of an interfibrillar network structure of TOCNs in the PS matrix, based on percolation theory. The outstanding and effective polymer reinforcement by TOCNs results from their high aspect ratio, high crystallinity, and nanodispersibility in the PS matrix.

  18. Surface plasmon resonances, optical properties, and electrical conductivity thermal hystersis of silver nanofibers produced by the electrospinning technique.

    PubMed

    Barakat, Nasser A M; Woo, Kee-Do; Kanjwal, Muzafar A; Choi, Kyung Eun; Khil, Myung Seob; Kim, Hak Yong

    2008-10-21

    In the present study, silver metal nanofibers have been successfully prepared by using the electrospinning technique. Silver nanofibers have been produced by electrospinning a sol-gel consisting of poly(vinyl alcohol) and silver nitrate. The dried nanofiber mats have been calcined at 850 degrees C in an argon atmosphere. The produced nanofibers do have distinct plasmon resonance compared with the reported silver nanoparticles. Contrary to the introduced shapes of silver nanoparticles, the nanofibers have a blue-shifted plasmon resonance at 330 nm. Moreover, the optical properties study indicated that the synthesized nanofibers have two band gap energies of 0.75 and 2.34 eV. An investigation of the electrical conductivity behavior of the obtained nanofibers shows thermal hystersis. These privileged physical features greatly widen the applications of the prepared nanofibers in various fields.

  19. Near-infrared fluorescent nanocapsules with reversible response to thermal/pH modulation for optical imaging.

    PubMed

    Chen, Yongping; Li, Xingde

    2011-12-12

    Polymeric near-infrared (NIR) fluorescent nanocapsules were developed, of which the fluorescence exhibited reversible response to local thermal/pH modulation. Our strategy was to use polymeric micelles made of temperature-sensitive Pluronic F-127 to encapsulate an amphiphilic NIR fluorescent dye-indocyanine green (ICG)-within the core and then cross-link the micelle corona by pH-sensitive poly(ethylenimine) (PEI). The size swelling/shrinking property of the micelles induced by temperature decrease/increase was used as a switch to control the fluorescence yield of the nanocapsules. It was found that the fluorescence yield significantly increased with the increase in temperature. The PEI cross-link made the fluorescence yield also sensitive to local pH change and enhanced intracellular delivery of the nanocapsules as well. Preliminary results suggest the NIR fluorescent probes could be potentially used as a contrast agent sensitive to local environment for translational optical imaging/sensing.

  20. Microwave-assisted arbitrary optical-pulse generation in a thermal vapor

    NASA Astrophysics Data System (ADS)

    Rajitha K., V.; Dey, Tarak N.

    2016-11-01

    The propagation of a weak optical field through an atomic system in closed Λ configuration is investigated in which the hyperfine levels are coupled by a microwave pulse. Under the three-photon resonance condition, it is observed that a new pulse of the shape of a microwave field is generated at the probe transition while the input probe is absorbed. The generated probe pulse follows the temporal position of the microwave pulse and maintains shape through the propagation. A simple propagation equation for the probe field in the Fourier domain has been employed to study this effect. This shape preservation of the probe pulse is due to the ground state coherence of the hyperfine transitions induced by the weaker intensity of the microwave field. The generation of an arbitrary shaped probe pulse is also possible at comparable strength of control and microwave fields. The intensity and detuning of the microwave field can play an important role to control probe pulse properties such as gain, broadening, and preservation of shape. The mechanism of efficient generation and manipulation of an optical pulse may have important applications in information science and optical communications.