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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. Optical Thermal Ratchet

    NASA Astrophysics Data System (ADS)

    Faucheux, L. P.; Bourdieu, L. S.; Kaplan, P. D.; Libchaber, A. J.

    1995-02-01

    We present an optical realization of a thermal ratchet. Directed motion of Brownian particles in water is induced by modulating in time a spatially periodic but asymmetric optical potential. The net drift shows a maximum as a function of the modulation period. The experimental results agree with a simple theoretical model based on diffusion.

  4. 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. PMID:27557260

  5. Fiber optic thermal detection of composite delaminations

    NASA Astrophysics Data System (ADS)

    Wu, Meng-Chou; Winfree, William P.

    2011-05-01

    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.

  6. 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.

  7. 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.

  8. 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.

  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. Structural-Thermal-Optical Program (STOP)

    NASA Technical Reports Server (NTRS)

    Lee, H. P.

    1972-01-01

    A structural thermal optical computer program is developed which uses a finite element approach and applies the Ritz method for solving heat transfer problems. Temperatures are represented at the vertices of each element and the displacements which yield deformations at any point of the heated surface are interpolated through grid points.

  14. Embedded Optical Sensors for Thermal Barrier Coatings

    SciTech Connect

    David R. Clarke

    2006-07-31

    The third year of this program on developing embedded optical sensors for thermal barrier coatings has been devoted to two principal topics: (i) continuing the assessment of the long-term, thermal cycle stability of the Eu{sup 3+} doped 8YSZ temperature sensor coatings, and (ii) improving the fiber-optic based luminescence detector system. Following the earlier, preliminary findings, it has been found that not only is the luminescence from the sensors not affected by prolonged thermal cycling, even after 195 hours at 1425 C, but the variation in luminescence lifetime with temperature remains unchanged. As the temperature of 1425 C is much higher than present engines attain or even planned in the foreseeable future, our findings indicate that the Eu{sup 3+} doped thermal barrier coating sensors are very robust and have the potential of being stable throughout the life of coatings. Investigation of Eu{sup 3+} doped coatings prepared by plasma-spraying exhibited the same luminescence characteristics as those prepared by electron-beam evaporation. This is of major significance since thermal barrier coatings can be prepared by both process technologies. A fiber-optic based luminescence system has been constructed in which the hottest section of fiber operates to at least 1250 C.

  15. 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.

  16. A porous silicon thermally tunable optical filter

    NASA Astrophysics Data System (ADS)

    Song, Da; Tokranova, Natalya; Gracias, Alison; Castracane, James

    2008-02-01

    Porous silicon (PSi) is a promising material for the creation of optical components for chip-to-chip interconnects because of its unique optical properties, flexible fabrication methods and integration with conventional CMOS material sets. In this paper, we present a novel active optical filter made of PSi to select desired optical wavelengths. The tunable membrane type optical filter is based on a Fabry-Perot interferometer employing two Bragg reflectors separated by an adjustable air gap, which can be thermally controlled. The Bragg reflectors contain alternating layers of high and low porosities. These layers were created by electrochemical etching of p+ type silicon wafers by varying the applied current during etching process. Micro bimorph actuators are designed to control the movement of the top DBR mirror, which changes the cavity thickness. By varying the applied current, the proposed filter can tune the transmitted wavelength of the optical signal. Various geometrical shapes and sizes ranging from 100μm to 1mm of the active filtering region have been realized for specific applications. The MOEMS technology-based device fabrication is fully compatible with the existing IC mass fabrication processes, and can be integrated with a variety of active and passive optical components to realize inter-chip or intra-chip communication at the system level at a relatively low cost.

  17. Graphene optical-to-thermal converter

    NASA Astrophysics Data System (ADS)

    Manjavacas, Alejandro; Thongrattanasiri, Sukosin; Greffet, Jean-Jacques; Garcia de Abajo, Javier

    2015-03-01

    Infrared plasmons in doped graphene nanostructures produce large optical absorption that can be used for narrow-band thermal light emission at tunable frequencies that strongly depend on the doping charge. By virtue of Kirchhoff's law, thermal light emission is proportional to the absorption, thus resulting in narrow emission lines associated with the electrically controlled plasmons of heated graphene. Here we show that realistic designs of graphene plasmonic structures can release over 90% of the emission through individual infrared lines with 1% bandwidth. We examine anisotropic graphene structures in which efficient heating can be produced upon optical pumping tuned to a plasmonic absorption resonance situated in the blue region relative to the thermal emission. An incoherent thermal light converter is thus achieved. Our results open a new approach for designing tunable nanoscale infrared light sources. A.M. acknowledges financial support from the Welch foundation through the J. Evans Attwell-Welch Postdoctoral Fellowship Program of the Smalley Institute of Rice University (Grant L-C-004).

  18. Thermal modeling for an optical refrigerator

    NASA Astrophysics Data System (ADS)

    Martin, K. W.; Schomacker, J.; Fraser, T.; Dodson, C.

    2015-03-01

    Optical refrigeration is currently the only completely solid state cooling method capable of reaching cryogenic temperatures from room temperature. Optical cooling utilizing Yb:YLF as the refrigerant crystal has resulted in temperatures lower than 123K measured via a fluorescence thermometry technique. However, to be useful as a refrigerator this cooling crystal must be attached to a sensor or other payload. The phenomenology behind laser cooling, known as anti-Stokes fluorescence, has a relatively low efficiency which makes the system level optimization and limitation of parasitic losses imperative. We propose a variety of potential designs for a final optical refrigerator, enclosure and thermal link; calculate conductive and radiative losses, and estimate direct fluorescence reabsorption. Our simulated designs show losses between 60 and 255 mW, depending on geometry and enclosure choice, with a lower bound as low as 23 mW.

  19. Thermal shock testing of lapped optical glass

    NASA Astrophysics Data System (ADS)

    Zhang, Yingrui; Wu, Yuansun; Liu, Han; Lambropoulos, John C.

    2007-09-01

    We have measured and modeled the thermal shock fracture of the commercially available BK-7 borosilicate crown optical glass as a function of surface finish prior to thermal shock testing. For surfaces lapped with alumina abrasives in the range 5 μm to 40 μm, the critical temperature drop for fracture in thin disk samples increases with diminishing abrasive size, and changes from 123.7+/-1.1 °C (for surfaces lapped with 40 μm abrasives) to 140.2+/-2.8 °C (for surfaces lapped with 5 μm abrasives.) We correlate the measured thermal shock (critical) temperature drop with the glass thermal and mechanical properties, including the fracture toughness, and the depth of surface cracks induced by the lapping process. We distinguish between "severe" and "mild" thermal shock conditions in terms of the applicable heat transfer coefficient and Biot number. We estimate that the depth of the strength controlling cracks on the edge of the disk samples was about 55-70 μm.

  20. Optical switching by stimulated thermal Rayleigh scattering

    NASA Astrophysics Data System (ADS)

    Peterson, Lauren M.

    1986-06-01

    Preliminary experiments were conducted whose ultimate goal is to develop all-optical control functions useful in an all-optical or optical-electronic hybrid digital computer or for optical interconnects. Stimulated thermal Rayleigh scattering (STRS) based upon generator experiments was pursued for scattering angles of 90 deg and 180 deg (backscattering). A pulsed nitrogen laser pumped dye laser served as the radiation source and the interaction medium was a liquid to which an absorbing dye was added. STRS amplifier experiments were successful and gain was observed and studied parametrically using eosine dye in ethanol. The gain was found to increase (although the gain coefficient decreased) with increasing pump power and the gain was found to be a maximum at an absorption coefficient of about 2.6 per cm. The generator experiments did not lead to stimulated scattering due to the limited output power of the laser and its multi-longitudinal spectral mode content. These studies will be continued along with analytical modeling in order to characterize the interaction and to enable the optimization of the scattering process.

  1. Optical and mechanical properties of thermally evaporated fluoride thin films

    SciTech Connect

    Zhang, K.; Fahey, R.; Jasinski, D.; Scarpino, C.; Dziendziel, R.; Burger, S.; DePoy, D.

    1998-06-08

    As a result of health and safety issues surrounding the use of radioactive materials on coated optical components, there has been renewed interest in coating materials whose optical and mechanical properties approach those offered by their radioactive counterparts. Due to the radioactive nature of ThF{sub 4} and its widespread use in optical coatings, the coating industry is examining other low index and non-radioactive fluorides as possible alternatives. In this paper, the authors present the results of an experimental study on the optical and mechanical properties of thermally evaporated ThF{sub 4}, DyF{sub 3}, CeF{sub 3}, LiF, HfF{sub 4}, IRX, and IRB thin films, where the materials were deposited at different substrate temperatures. The objective is to examine this series of fluorides under comparable deposition conditions and with respect to such material properties as: n and k, film stress, and environmental stability. The optical constants of these fluorides were evaluated over the wavelength region from 1.0 {micro}m to 12.5 {micro}m.

  2. 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.

  3. Multi-wavelength optical measurement to enhance thermal/optical analysis for carbonaceous aerosol

    NASA Astrophysics Data System (ADS)

    Chen, L.-W. A.; Chow, J. C.; Wang, X. L.; Robles, J. A.; Sumlin, B. J.; Lowenthal, D. H.; Zimmermann, R.; Watson, J. G.

    2015-01-01

    A thermal/optical carbon analyzer equipped with seven-wavelength light source/detector (405-980 nm) for monitoring spectral reflectance (R) and transmittance (T) of filter samples allowed "thermal spectral analysis (TSA)" and wavelength (λ)-dependent organic-carbon (OC)-elemental-carbon (EC) measurements. Optical sensing was calibrated with transfer standards traceable to absolute R and T measurements, adjusted for loading effects to report spectral light absorption (as absorption optical depth (τa, λ)), and verified using diesel exhaust samples. Tests on ambient and source samples show OC and EC concentrations equivalent to those from conventional carbon analysis when based on the same wavelength (~ 635 nm) for pyrolysis adjustment. TSA provides additional information that evaluates black-carbon (BC) and brown-carbon (BrC) contributions and their optical properties in the near infrared to the near ultraviolet parts of the solar spectrum. The enhanced carbon analyzer can add value to current aerosol monitoring programs and provide insight into more accurate OC and EC measurements for climate, visibility, or health studies.

  4. Multi-wavelength optical measurement to enhance thermal/optical analysis for carbonaceous aerosol

    NASA Astrophysics Data System (ADS)

    Chen, L.-W. A.; Chow, J. C.; Wang, X. L.; Robles, J. A.; Sumlin, B.; Lowenthal, D. H.; Zimmermann, R.; Watson, J. G.

    2014-09-01

    A thermal/optical carbon analyzer equipped with seven-wavelength light source/detector (405-980 nm) for monitoring spectral reflectance (R) and transmittance (T) of filter samples allows "thermal spectral analysis (TSA)" and wavelength (λ)-dependent organic carbon (OC)-elemental carbon (EC) measurements. Optical sensing is calibrated with transfer standards traceable to absolute R and T measurements and adjusted for loading effects to determine spectral light absorption (as absorption optical depth [τa, λ]) using diesel exhaust samples as a reference. Tests on ambient and source samples show OC and EC concentrations equivalent to those from conventional carbon analysis when based on the same wavelength (~635 nm) for pyrolysis adjustment. TSA provides additional information that evaluates black carbon (BC) and brown carbon (BrC) contributions and their optical properties in the near-IR to the near-UV parts of the solar spectrum. The enhanced carbon analyzer can add value to current aerosol monitoring programs and provide insight into more accurate OC and EC measurements for climate, visibility, or health studies.

  5. 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.

  6. 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

  7. Optical Coatings and Thermal Noise in Precision Measurement

    NASA Astrophysics Data System (ADS)

    Harry, Gregory; Bodiya, Timothy P.; DeSalvo, Riccardo

    2012-01-01

    1. Theory of thermal noise in optical mirrors Y. Levin; 2. Coating technology S. Chao; 3. Compendium of thermal noises in optical mirrors V. B. Braginsky, M. L. Gorodetsky and S. P. Vyatchanin; 4. Coating thermal noise I. Martin and S. Reid; 5. Direct measurements of coating thermal noise K. Numata; 6. Methods of improving thermal noise S. Ballmer and K. Somiya; 7. Substrate thermal noise S. Rowan and I. Martin; 8. Cryogenics K. Numata and K. Yamamoto; 9. Thermo-optic noise M. Evans and G. Ogin; 10. Absorption and thermal issues P. Willems, D. Ottaway and P. Beyersdorf; 11. Optical scatter J. R. Smith and M. E. Zucker; 12. Reflectivity and thickness optimisation I. M. Pinto, M. Principe and R. DeSalvo; 13. Beam shaping A. Freise; 14. Gravitational wave detection D. Ottaway and S. D. Penn; 15. High-precision laser stabilisation via optical cavities M. J. Martin and J. Ye; 16. Quantum optomechanics G. D. Cole and M. Aspelmeyer; 17. Cavity quantum electrodynamics T. E. Northup.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Integrated thermal disturbance analysis of optical system of astronomical telescope

    NASA Astrophysics Data System (ADS)

    Yang, Dehua; Jiang, Zibo; Li, Xinnan

    2008-07-01

    During operation, astronomical telescope will undergo thermal disturbance, especially more serious in solar telescope, which may cause degradation of image quality. As drives careful thermal load investigation and measure applied to assess its effect on final image quality during design phase. Integrated modeling analysis is boosting the process to find comprehensive optimum design scheme by software simulation. In this paper, we focus on the Finite Element Analysis (FEA) software-ANSYS-for thermal disturbance analysis and the optical design software-ZEMAX-for optical system design. The integrated model based on ANSYS and ZEMAX is briefed in the first from an overview of point. Afterwards, we discuss the establishment of thermal model. Complete power series polynomial with spatial coordinates is introduced to present temperature field analytically. We also borrow linear interpolation technique derived from shape function in finite element theory to interface the thermal model and structural model and further to apply the temperatures onto structural model nodes. Thereby, the thermal loads are transferred with as high fidelity as possible. Data interface and communication between the two softwares are discussed mainly on mirror surfaces and hence on the optical figure representation and transformation. We compare and comment the two different methods, Zernike polynomials and power series expansion, for representing and transforming deformed optical surface to ZEMAX. Additionally, these methods applied to surface with non-circular aperture are discussed. At the end, an optical telescope with parabolic primary mirror of 900 mm in diameter is analyzed to illustrate the above discussion. Finite Element Model with most interested parts of the telescope is generated in ANSYS with necessary structural simplification and equivalence. Thermal analysis is performed and the resulted positions and figures of the optics are to be retrieved and transferred to ZEMAX, and thus

  13. Magneto-optical media for thermal sensing

    NASA Astrophysics Data System (ADS)

    Chervonenkis, Andrey Y.; Kirykhin, Nikolay N.; Randoshkin, Vladimir V.

    1990-10-01

    Several types of magnetooptical (MO) media, possessing "memory" effect are discussed for the purpose of thermal sensing. These are high coercive garnet films, trad.itionaly used. for therrnoxnagnetic re- cording, films with configurational phase transitions between dife- rent types of the domain structure produced by local heating and films with artifially formed pixel arrays. It's shown that structures of the latter type are most suitable for thermal sensing.

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

    NASA Technical Reports Server (NTRS)

    Skinner, S. Ballou

    1992-01-01

    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).

  15. 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.

  16. Nonlinear optical Galton board: Thermalization and continuous limit

    NASA Astrophysics Data System (ADS)

    Di Molfetta, Giuseppe; Debbasch, Fabrice; Brachet, Marc

    2015-10-01

    The nonlinear optical Galton board (NLOGB), a quantum walk like (but nonlinear) discrete time quantum automaton, is shown to admit a complex evolution leading to long time thermalized states. The continuous limit of the Galton board is derived and shown to be a nonlinear Dirac equation (NLDE). The (Galerkin-truncated) NLDE evolution is shown to thermalize toward states qualitatively similar to those of the NLOGB. The NLDE conserved quantities are derived and used to construct a stochastic differential equation converging to grand canonical distributions that are shown to reproduce the (microcanonical) NLDE thermalized statistics. Both the NLOGB and the Galerkin-truncated NLDE are thus demonstrated to exhibit spontaneous thermalization.

  17. Thermal mirror spectrometry: An experimental investigation of optical glasses

    NASA Astrophysics Data System (ADS)

    Zanuto, V. S.; Herculano, L. S.; Baesso, M. L.; Lukasievicz, G. V. B.; Jacinto, C.; Malacarne, L. C.; Astrath, N. G. C.

    2013-03-01

    The Thermal mirror technique relies on measuring laser-induced nanoscale surface deformation of a solid sample. The amplitude of the effect is directly dependent on the optical absorption and linear thermal expansion coefficients, and the time evolution depends on the heat diffusion properties of the sample. Measurement of transient signals provide direct access to thermal, optical and mechanical properties of the material. The theoretical models describing this effect can be formulated for very low optical absorbing and for absorbing materials. In addition, the theories describing the effect apply for semi-infinite and finite samples. In this work, we apply the Thermal mirror technique to measure physical properties of optical glasses. The semi-infinite and finite models are used to investigate very low optical absorbing glasses. The thickness limit for which the semi-infinite model retrieves the correct values of the thermal diffusivity and amplitude of the transient is obtained using the finite description. This procedure is also employed on absorbing glasses, and the semi-infinite Beer-Lambert law model is used to analyze the experimental data. The experimental data show the need to use the finite model for samples with very low bulk absorption coefficients and thicknesses L < 1.5 mm. This analysis helped to establish limit values of thickness for which the semi-infinite model for absorbing materials could be used, L > 1.0 mm in this case. In addition, the physical properties of the samples were calculated and absolute values derived.

  18. 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.

  19. Effect of static, dynamic, thermal, and humidity loading on fatigue life of fiber optic cables

    NASA Astrophysics Data System (ADS)

    El-Sabbagh, Adel; Baz, Amr M.

    2004-07-01

    Health monitoring of aircraft structures with optical fiber sensors requires that the fibers remain functional for the lifetime of these structures as repairs are generally very costly and time consuming. Thus, the feasibility of using optical fibers in various aircraft structures depends heavily on the durability of these fibers under adverse loading conditions. It is well known that silica optical fibers are vulnerable to applied mechanical and thermal loads that make flaws grow rapidly and eventually lead to fiber failure. In this paper, we investigate theoretically and experimentally the combined effect of the mechanical, thermal, and moisture loading on the aging process of fiber optic cables in an attempt to assess the expected lifetime of these cables in a naval aviation environment. It is also important to note that there is a pressing need for such an investigation, as all the studies available in the literature address the individual rather than the combined effects of these parameters on the lifetime of the cables.

  20. Thermal/structural/optical integrated design for optical window of a high-speed aerial optical camera

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    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 149.6 nm, which is under PV <=1 4λ .The simulation result meets the requirements of optical design very well. The above study can be used as an important reference for other optical window designs.

  1. 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.

  2. Thermally driven continuous-wave and pulsed optical vortex.

    PubMed

    Ding, Yitian; Xu, Miaomiao; Zhao, Yongguang; Yu, Haohai; Zhang, Huaijin; Wang, Zhengping; Wang, Jiyang

    2014-04-15

    We demonstrated a continuous-wave (cw) and pulsed optical vortex with topological charges driven by heat generated during the lasing process without introducing the astigmatism effect and reducing lasing efficiency. During the lasing process, the topological charges were changeable by the thermal-induced lens and selected by the mode-matching between the pump and oscillating beams. With a graphene sample as the saturable absorber, a pulsed optical vortex was achieved at a wavelength of 1.36 μm, which identified that graphene could be used as a pulse modulator for the generation of a pulsed optical vortex. Thermally driven cw and pulsed optical vortexes should have various promising applications based on the compact structure, changeable topological charges, and specific wavelength. PMID:24978994

  3. 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.

  4. 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.

  5. Optical and thermal performance of a remote phosphor plate

    NASA Astrophysics Data System (ADS)

    Mou, Xi; Narendran, Nadarajah; Zhu, Yiting; Perera, Indika U.

    2014-09-01

    The objective of this study was to understand how optical and thermal performances are impacted in a remote phosphor LED (light-emitting diode) system when the phosphor plate thickness and phosphor concentration change with a fixed amount of a commonly used YAG:Ce phosphor. In the first part of this two-part study, an optical raytracing analysis was carried out to quantify the optical power and the color properties as a function of remote phosphor plate thickness, and a laboratory experiment was conducted to verify the results obtained from the raytracing analysis and also to examine the phosphor temperature variation due to thickness change.

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

    SciTech Connect

    Kuzay, T.M.

    1990-06-29

    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.

  7. 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

  8. 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).

  9. 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.

  10. Oxyfluorotellurite glasses doped by dysprosium ions. Thermal and optical properties

    NASA Astrophysics Data System (ADS)

    Klimesz, Barbara; Ryba-Romanowski, Witold; Lisiecki, Radosław

    2015-04-01

    The paper shows results of investigation of thermal and optical properties of oxyfluorotellurite (65 - x)TeO2-20ZnF2-12Pb2O5-3Nb2O5-xDy2O3 (x = 0.5, 2 and 5) glass systems. Thermal stability and the onset of crystallization of the materials were monitored by differential thermal analysis (DTA). It was found that characteristic parameters, namely glass transition temperatures (Tg), onset of crystallization temperatures (Tc) and thermal stability criteria ΔT and H' increased with increasing Dy2O3 content indicating that the incorporation of dysprosium ions improves substantially thermal stability of glass system under study. Optical absorption and emission spectra of Dy3+ ions in oxyfluorotellurite glass were investigated at room temperature in the visible (VIS) and near-infrared (NIR) region. Oscillator strengths, phenomenological Judd-Ofelt (JO) intensity parameters Ω2,4,6, radiative transition probabilities, branching ratios and radiative lifetimes of luminescent levels were determined. Decay curves of the 4F9/2 luminescence of incorporated Dy3+ ions were recorded and analysed. Lifetimes and the luminescence dynamics were studied as a function of the Dy2O3 concentration. It was concluded that good thermal stability combined with desirable spectroscopic parameters of investigated dysprosium-doped oxyfluorotellurite glass point at the suitability of this material for the design of UV-excited visible phosphors.

  11. 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.

  12. 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.

  13. Electro-optical and pyroelectrical thermal analysis of novel nonlinear optical side-chain polymers with high thermal stability

    NASA Astrophysics Data System (ADS)

    Gerhard-Multhaupt, Reimund; Bauer, Stefan; Molzow, Wolf-Dietrich; Ren, W.; Wirges, Werner; Yilmaz, S.; Oertel, U.; Haenel, B.; Haeussler, L.; Komber, H.; Lunkwitz, K.

    1994-01-01

    Polymers containing nonlinear optical moieties were prepared on the basis of maleic anhydride copolymers. Azo dyes such as Disperse Red 1 (DR 1) were attached to the polymer backbones via esterification, amidization, or imidization. Optimal poling conditions for the side-chain polymers were determined by means of thermal analysis. After electrode poling with a bias voltage of 200 V at a temperature of 185 degree(s)C, the spin-coated samples were slowly cooled down to room temperature with the poling field still applied. The thermal stabilities of the poled polymer films were measured by means of electro-optical (EOTA) and pyro- electrical (PTA) thermal analysis and compared to the respective responses of DR 1/polymethylmethacrylate (PMMA) guest/host polymer samples. Both experimental techniques (EOTA and PTA) are discussed in some detail together with the experimental results.

  14. Thermal characterization of optical fibers using wavelength-sweeping interferometry

    SciTech Connect

    Perret, Luc; Pfeiffer, Pierre; Serio, Bruno; Twardowski, Patrice

    2010-06-20

    In this paper, we report a new method of thermal characterization of optical fibers using wavelength-sweeping interferometry and discuss its advantages compared to other techniques. The setup consists of two temperature-stabilized interferometers, a reference Michelson and a Mach-Zehnder, containing the fiber under test. The wavelength sweep is produced by an infrared tunable laser diode. We obtained the global phase shift coefficients of a large effective area fiber and gold-coated fiber optics with a 10{sup -7} accuracy.

  15. 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.

  16. 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.

  17. 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.

  18. Thermal refocusing method for spaceborne high-resolution optical imagers.

    PubMed

    Selımoglu, Ozgur; Ekinci, Mustafa; Karcı, Ozgur

    2016-05-20

    We describe the design of a thermal refocusing method for spaceborne high-resolution imagers where Korsch optical design is usually implemented. The secondary mirror is made of aluminum, a high thermal expansion coefficient material, instead of conventional zero-expansion glass ceramics. In this way, the radius of the curvature can be controlled by means of temperature change of the mirror. Change in the radius of curvature also changes the effective focal length of the camera which is used for compensation of the defocus that occurred in space. We show that the 30 μm despace of the secondary mirror in the optical system can be compensated by an ∼10°C temperature change of the mirror while the image quality is maintained. PMID:27411138

  19. 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.

  20. Determines the Thermal and Optical Properties of Fenestration Systems

    1995-01-27

    WINDOW4.1 computes the thermal properties of windows and other fenestration elements used in typical residential and commercial buildings. Manufactures, specifiers, architects, consumers, and the energy code specialists all need to know these properties (U-values, Solar Heat Gain Coefficients, optical properties). The use of this program to calculate these properties is typically much more cost effective than laboratory test procedures. Properties of complete window systems are based on libraries (or user input) component data.

  1. Low Temperature Thermal Vacuum Test Facility for Optical Instruments

    NASA Astrophysics Data System (ADS)

    Sollner, B.

    2012-07-01

    The challenging goals for current and future scientific missions require further improvements and investigations on space simulation on earth. As a present example for the efforts to be undertaken in order to fulfil those requirements, a specific test set up including the installation of a complete new thermal vacuum test facility is presented, which is designed in the framework of the JWST Near-Infrared Spectrograph (NIRSpec) test campaign at IABG mbH. The qualification tests for the NIRSpec Optical Assembly require temperatures below 20K on three independent heat sinks as well as a helium cooled shroud which surrounds the test object. Furthermore low vibration levels in a clean class5 environment, combined with a long term stability of the parameters to be determined are necessary. Additional specific devices are introduced into the test setup and the test chamber, to allow temporary thermal decoupling, short- term optical access and high optical isolation. Moreover, major improvements on the levelling and positioning of the test setup inside the thermal vacuum chamber are implemented.

  2. Structural health monitoring with fiber optic sensors

    NASA Astrophysics Data System (ADS)

    Güemes, Alfredo; Fernandez-Lopez, Antonio

    2014-05-01

    SHM is defined as the process of acquiring and analyzing data from on-board sensors to evaluate the health of a structure. Most common damages on aircrafts are local cracks and delaminations, that do not change strongly the overall strain field, but that will act as the failure initiation point. Fiber optic sensors act primarily as strain sensors, so unless damage happens very close to the sensor location, it may go undetected. Currently, three main approaches for detecting damage from strain measurements are being investigated: 1) High resolution fibre optic distributed sensing (OFDR Rayleigh scattering). 2) Strain mapping with a dense network of sensors. Statistical analysis tools, like PCA, have been successfully used. 3) Hybrid FBG/PZT systems. FBGs must detect the ultrasonic elastic waves.

  3. Modelling thermal parasitic load lines for an optical refrigerator

    NASA Astrophysics Data System (ADS)

    Martin, K. W.; Shomacker, J.; Fraser, T.; Dodson, C.

    2015-12-01

    Optical refrigeration is currently the only completely solid state cooling method capable of reaching cryogenic temperatures from room temperature. Optical cooling utilizing Yb:YLF as the refrigerant crystal has resulted in temperatures lower than 123K measured via a fluorescence thermometry technique. However, to be useful as a refrigerator this cooling crystal must be attached to a sensor or other payload. The phenomenology behind laser cooling, known as anti-Stokes fluorescence, has a relatively low efficiency which makes the system level optimization and limitation of parasitic losses imperative. We propose and model a variety of potential designs for a final optical refrigerator, enclosure and thermal link; calculate conductive and radiative losses, and estimate direct fluorescence reabsorption. We generate parasitic load-lines; these curves define temperature-dependent minimum heat lift thresholds that must be achieved to generate cooling for detectors.

  4. Integration of an intensity-modulated optical fiber temperature sensor into ceramic coating obtained by wire flame thermal spray

    NASA Astrophysics Data System (ADS)

    Yi, Duo; Pfeiffer, Pierre; Serio, Bruno; Costil, Sophie

    2015-05-01

    Temperature sensing is one of the key requirements for Structure Health Monitoring (SHM) in various applications. The intensity modulated optical fiber sensors are excellent candidate for this area of applications due to their relatively low cost, simple structure and diversity of applications. This work relates mainly to the feasibility evaluation of embedding optical fiber sensor into ceramic coating obtained by thermal spray process and the thermal response of the embedded sensor. The sensor principle and the specimen configuration are firstly presented, a 3D model is then built up in order to evaluate the effects of temperature variation on deformations of the optical fiber sensor which finally lead to the variation of optical intensity. First results of thermal response are discussed.

  5. 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.

  6. Effect of Annealing on Thermal & Optical Properties of Polypyrrole

    NASA Astrophysics Data System (ADS)

    Saxena, Rashmi; Dixit, Manasvi; Sharma, Kananbala; Saxena, Narendra S.; Sharma, Thaneshwar P.

    2008-04-01

    Pure polypyrrole sample (S1) was synthesized by chemical oxidation method using NaOH as reducing agent in aqueous HCl medium. The polypyrrole pellet sample (S2) was then annealed at 200 °C for 4 hrs. The amorphous nature of both annealed and as- prepared polypyrrole samples was confirmed by XRD. FTIR spectra of both samples were taken, which indicate the significant change in annealed sample (S2) compared to as prepared sample. Temperature dependence of effective thermal conductivity of both samples (S1, S2) was studied by Transient plane source (TPS) technique. The effective thermal conductivity (λe) obtained for S1 & S2 exhibits a variation with temperature and a peak was observed for the two samples at 150 °C & 120 °C with a value 0.17 W/mK & 0.18 W/mK respectively. The shift of thermal conductivity peak of annealed sample towards the lower temperature side is explained on the basis of removal of voids and defects on annealing. The absorption spectra of these samples were recorded by USB-2000 spectrophotometer at room temperature in the wavelength range 300-800 nm. From the analysis of absorption spectra, optical band gap of S1 & S2 were determined. It was found that the values of optical band gap for sample S1 & S2 are 2.39 eV&2.24 eV respectively.

  7. 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

  8. Low temperature thermal expansion measurements on optical materials.

    PubMed

    Browder, J S; Ballard, S S

    1969-04-01

    A three-terminal capacitance type dilatometer has been developed for investigating the thermal expansion of optical materials at low temperatures. The method is applicable when only small sample lengths (13 mm or less) are available. The thermal expansion coefficients of six polycrystalline materials (the Irtrans) and of one nonoxide glass have been determined in the range from room temperature down to about 60 K. Minute changes of the length of a sample produce a change of the spacing of a parallel plate capacitor with guard ring; the resulting change of capacitance is measured on a highly sensitive bridge. The expansion coefficients are then determined by relating the change of capacitance to the change of dimensions of the sample.

  9. 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.

  10. 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. PMID:23455291

  11. Changes in optical properties of rat skin during thermal coagulation

    NASA Astrophysics Data System (ADS)

    Thomsen, Sharon L.; Vijverberg, Helene; Huang, Robert; Schwartz, Jon A.

    1993-07-01

    Thermal coagulation of albino rat skin heated in vitro results in prominent changes of light scattering but relatively little in light absorption based on measurements using an integrating sphere spectrometer. The reduced scattering coefficients, (mu) s(1-g), gradually increase as temperatures increase from room temperature to 55 degree(s)C then rapidly decrease to plateau after 70 degree(s)C is reached. The differences among the (mu) s(1-g) values for the different wavelengths were greater at the lower temperatures than at higher temperatures. The absorption coefficient, (mu) a, changed very little over the test temperature range (room temperature to 90 degree(s)C) and then only at higher temperatures and for longer wavelengths. The optical property changes were associated with thermally induced light microscopic and ultrastructural changes in the dermal collagen, a major tissue component of skin.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Thermally detected optical absorption in sophisticated nitride structures

    NASA Astrophysics Data System (ADS)

    Vasson, A.; Shubina, T. V.; Leymarie, J.

    2005-02-01

    The thermally detected optical absorption (TDOA) is applied to elucidate peculiarities of absorption in nitride structures of unusual morphology like GaN nanocolumns or InN layers with various imperfections. A study of GaN structures permits us to establish position of an absorption edge in TDOA spectra. We demonstrate that the absorption edge is different in GaN regions of opposite polarities. In InN with metallic In inclusions, this technique enable separation of InN interband absorption and extinction related to the Mie resonances, if the latter are below the principal absorption edge.

  17. Modelling thermal transfer in optically stimulated luminescence of quartz

    NASA Astrophysics Data System (ADS)

    Pagonis, V.; Chen, R.; Wintle, A. G.

    2007-02-01

    A previously published kinetic model for the production of luminescence signals in quartz is used to investigate the production of thermally transferred optically stimulated luminescence (TT-OSL) signals. This paper provides a mathematical description of the thermal transfer mechanism for two different phenomena that have been observed in previously published experiments (Aitken and Smith 1988 Quat. Sci. Rev. 7 387-93). The starting point is the model proposed by Bailey (2001 Radiat. Meas. 33 17-45). The numerical values of some of the parameters are varied so that they match the experimental data. The effect caused by varying these values is investigated. The first of these phenomena takes place after storing optically bleached samples at room temperature; this involves the traps responsible for the 110 °C thermoluminescence (TL) peak of quartz acting as a refuge trap. The second phenomenon concerns OSL signals that are induced by heating the samples after the bleaching of the OSL signal and involves a putative TL peak at ~230 °C associated with the refuge trap; specifically, the paper presents a simulation of the temperature dependence of the OSL signal measured by successively heating the quartz samples to higher temperatures up to ~400 °C.

  18. Thermal and optical properties of new organic nonlinear optical single crystals

    NASA Astrophysics Data System (ADS)

    Menezes, Anthoni Praveen; Jayarama, A.

    2014-04-01

    Nonlinear optical (NLO) materials are useful in a number of industrial applications. Organic NLO single crystals of 3-(4-chlorophenyl)-1-(pyridin-3-yl) prop-2-en-1-one (4-Chloro chalcone, 4CC) and 3-(4-bromophenyl)-1-(pyridin-3-yl) prop-2-en-1-one (4-bromo chalcone, 4BC), having large second harmonic generation efficiency (SHG), were grown by slow evaporation technique. The thermal analysis reveals that these chalcone derivatives possess better thermal stability in comparison with urea. Both the crystals 4CC and 4BC are non-linear optically active with SHG efficiencies of 4 and 1.4 times that of urea respectively. The UV-Visible spectrum reveals that the crystals are transparent in the entire visible region. The substitution of a chloro group at the para position of the phenylene moiety is better in increasing the SHG efficiency of the crystal compared to a bromo group. Good thermal stability, optical transparency and SHG response make the crystals useful for frequency doubling of diode laser down to 435nm.

  19. Optical-thermal light-tissue interactions during photoacoustic imaging

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    Photoacoustic imaging (PAI) has grown rapidly as a biomedical imaging technique in recent years, with key applications in cancer diagnosis and oximetry. In spite of these advances, the literature provides little insight into thermal tissue interactions involved in PAI. To elucidate these basic phenomena, we have developed, validated, and implemented a three-dimensional numerical model of tissue photothermal (PT) response to repetitive laser pulses. The model calculates energy deposition, fluence distributions, transient temperature and damage profiles in breast tissue with blood vessels and generalized perfusion. A parametric evaluation of these outputs vs. vessel diameter and depth, optical beam diameter, wavelength, and irradiance, was performed. For a constant radiant exposure level, increasing beam diameter led to a significant increase in subsurface heat generation rate. Increasing vessel diameter resulted in two competing effects - reduced mean energy deposition in the vessel due to light attenuation and greater thermal superpositioning due to reduced thermal relaxation. Maximum temperatures occurred either at the surface or in subsurface regions of the dermis, depending on vessel geometry and position. Results are discussed in terms of established exposure limits and levels used in prior studies. While additional experimental and numerical study is needed, numerical modeling represents a powerful tool for elucidating the effect of PA imaging devices on biological tissue.

  20. 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.

  1. Evaluation of Thermal Stability of Organic Electro-Optic Device by Using Thermally Stimulated Current.

    PubMed

    Ikemoto, Ryoma; Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa; Yamada, Toshiki; Otomo, Akira

    2016-04-01

    Thermally stimulated current (TSC) measurement was employed to study the thermal stability of electro-optic (EO) polymers, i.e., guest/host polymer DR1/PMMA and side-chain polymer PMMA-co-DR1. Here the isothermal relaxation test showed that the relaxation time τ (85 °C) of side-chain polymer PMMA-co-DR1 is longer than that of guest/host polymer DR1/PMMA. TSC peaks appeared symmetrically in proportion to the poling electric field Ep, indicating that DR1 molecules make a dominant contribution to dipolar depolarization. Thermal sampling (TS) method showed that the activation energy of the DR1/PMMA is around 1 eV, while that of the PMMA-co-DR1 is distributed >1 eV. Results suggested that side-chain polymer is preferable to the guest/host polymer in the thermal stability. TSC measurement is helpful as a conventional method for studying the life time of EO polymers in terms of dipolar motion. PMID:27451636

  2. Structural, optical and thermal properties of silver colloidal nanoparticles

    NASA Astrophysics Data System (ADS)

    Naderi, S.; Ghaderi, A.; Solaymani, S.; Golzan, M. M.

    2012-05-01

    In this paper, colloidal silver nanoparticles were prepared by chemical reduction of AgNO3 and pure Sn in a new and simple method. The type of crystallite lattice and the size of nanopowders were estimated by X-Ray Diffraction (XRD) analysis. The geometric, heterogeneous and mixing structure of synthesized nanopowders were studied by Scanning Electron Microscopy (SEM). Optical properties such as plasmon absorption and frequency of soluble colloidal nanopowders in two solutions of distilled water and oil were investigated by UV-Visible spectroscopy, which was developed to calculate the absorbance spectra of nanoparticles solution containing a size distribution of particles using the Mie theory. Dipole and quadrupole plasmons related to molecular structure of water and oil were found by absorbance spectra. Also, Differential Scanning Calorimetry (DSC) analysis was used for determining the thermal behavior, endothermic and exothermic peaks of Ag nanopowder.

  3. Optical Disc Simulation Program Unified by Electromagnetic and Thermal Distributions

    NASA Astrophysics Data System (ADS)

    Yamakawa, Yuzo; Kurihara, Kazuma; Kuwahara, Masashi; Shima, Takayuki; Nakano, Takashi; Tominaga, Junji

    2006-02-01

    We developed a novel simulation program unified by electromagnetic and thermal distributions for a rotating optical disc on the basis of the three-dimensional finite-difference time-domain (FDTD) method. We applied this simulation to super-resolution near-field structure (super-RENS) read-only-memory (ROM) discs and elucidated that the temperature distribution is not only dependent on disc structure and pit shape, but also on incident laser light polarization. We obtained the result that the temperature at the pit became higher than the surrounding temperature for the first time using our simulation program. We believe that our program will aid our understanding of the phenomena behind the super-resolution readout of super-RENS discs.

  4. A simple method for characterizing and engineering thermal relaxation of an optical microcavity

    NASA Astrophysics Data System (ADS)

    Chen, Weijian; Zhu, Jiangang; Özdemir, Şahin Kaya; Peng, Bo; Yang, Lan

    2016-08-01

    Thermal properties of a photonic resonator are determined not only by intrinsic properties of materials, such as thermo-optic coefficient, but also by the geometry and structure of the resonator. Techniques for characterization and measurement of thermal properties of individual photonic resonator will benefit numerous applications. In this work, we demonstrate a method to optically measure the thermal relaxation time and effective thermal conductance of a whispering gallery mode microcavity using optothermal effect. Two nearby optical modes within the cavity are optically probed, which allows us to quantify the thermal relaxation process of the cavity by analyzing changes in the transmission spectra induced by optothermal effect. We show that the effective thermal conductance can be experimentally deduced from the thermal relaxation measurement, and it can be tailored by changing the geometric parameters of the cavity. The experimental observations are in good agreement with the proposed analytical modeling. This method can be applied to various resonators in different forms.

  5. 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.

  6. Nonlinear optical materials: Synthesis, characterizations, thermal stability and electro-optical properties

    SciTech Connect

    Qiu Fengxian . E-mail: fxqiuchem@163.com; Xu Hongliang; Cao Yonglin; Jiang Yan; Zhou Yuming; Liu Juzheng; Zhang Xuping

    2007-03-15

    Two series of thermal stable polyimides and polyimide/silica hybrid materials have been synthesized. The silica content in the hybrid materials was varied from 0 to 22.5 wt.% and SiO{sub 2} phase was well dispersed in the polymer matrix. The glass transition temperature (T {sub g}) and the decomposition temperature (T {sub d}) were in the range 226-382 deg. C and 345-499 deg. C, respectively, for materials. The polymer solutions could be spin coated on the indium-tin-oxide (ITO) glass or other substrates to form optical quality thin films. The electro-optic coefficients ({gamma} {sub 33}) at the wavelength of 832 nm for polymer thin films poled were in the range of 12-25 pm/V and the values remained well (retained > 85% for more than 100 h). The heat capacities of some materials were in the range of 0.9755-1.1821 J K{sup -1} g{sup -1} for the temperature 273 and 363 K. No thermal anomaly was found in this temperature range. Most of them showed high thermal stability.

  7. 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. PMID:27244403

  8. 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.

  9. 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.

  10. Ultraviolet and visible BRDF data on spacecraft thermal control and optical baffle materials

    NASA Technical Reports Server (NTRS)

    Viehmann, W.; Predmore, R. E.

    1987-01-01

    Bidirectional scattering functions of numerous optical baffle materials and of spacecraft thermal control coatings and surfaces are presented. Measurements were made at 254 nm and at 633 nm. The coatings and surfaces include high-reflectance white paints, low-reflectance optical blacks, thermal control blankets, and various conversion coatings on aluminum.

  11. 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.

  12. An analytical study of thermal invariance of polymeric nanolayer gradient index optical components

    NASA Astrophysics Data System (ADS)

    Fein, Howard; Ponting, Michael

    2016-05-01

    Specially formulated Gradient-Index polymeric optical materials offer capabilities not possible in conventional GRIN or homogenous optics. A novel technology that enables large scale processing of nanolayered polymer films into real, performance-enhancing lenses and other optical components for Defense-related optical systems is currently being employed. Polymeric nanoLayer GRIN materials (LGRIN) offer the ability to design and fabricate optics with custom gradient refractive index profiles in optical components up to 90 mm in diameter and approaching 5 cm thick. High performance achromatic singlet lenses were designed using specially developed ZEMAX design tools and exceptionally high quality lenses were fabricated from the LGRIN materials. Optical performance of LGRIN optics is shown to be significantly better than with conventional monolithic optics while also significantly reducing optical system mass, volume, and optical element count. Understanding the thermal behavior of such optical components is essential to their operational capability. An experimental study of the effects of elevated operational environments to validate the feasibility of deploying LGRIN optics into real-world operational environments was carried out. Interferometric and physical measurements of structure and optical performance of LGRIN lenses was completed over a 30° - 50°C temperature range. It is shown that nanolayered LGRIN optics and components exhibit no significant variation in optical performance with temperature as compared with commercial, homogenous acrylic optics in the designed operational thermal range.

  13. Thermal effects in the Input Optics of the Enhanced Laser Interferometer Gravitational-Wave Observatory interferometers.

    PubMed

    Dooley, Katherine L; Arain, Muzammil A; Feldbaum, David; Frolov, Valery V; Heintze, Matthew; Hoak, Daniel; Khazanov, Efim A; Lucianetti, Antonio; Martin, Rodica M; Mueller, Guido; Palashov, Oleg; Quetschke, Volker; Reitze, David H; Savage, R L; Tanner, D B; Williams, Luke F; Wu, Wan

    2012-03-01

    We present the design and performance of the LIGO Input Optics subsystem as implemented for the sixth science run of the LIGO interferometers. The Initial LIGO Input Optics experienced thermal side effects when operating with 7 W input power. We designed, built, and implemented improved versions of the Input Optics for Enhanced LIGO, an incremental upgrade to the Initial LIGO interferometers, designed to run with 30 W input power. At four times the power of Initial LIGO, the Enhanced LIGO Input Optics demonstrated improved performance including better optical isolation, less thermal drift, minimal thermal lensing, and higher optical efficiency. The success of the Input Optics design fosters confidence for its ability to perform well in Advanced LIGO.

  14. Results from the TOM3 testbed: thermal deformation of optics at the picometer Level

    NASA Technical Reports Server (NTRS)

    Goullioud, Renaud; Lindensmith, C. A.; Hahn, I.

    2006-01-01

    We have discussed the TOM3 testbed developed to assess the thermo-opto-mechanical stability of optical assembly such as SIM's siderostat and telescope in flight-like thermal conditions. Although limited by the metrology sensor noise, test results show that optical wavefront stability of SIM's optical assembly is compatible with single micro-arcsecond astrometry.

  15. 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.

  16. 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. PMID:27351668

  17. Optical properties of rubrene thin film prepared by thermal evaporation

    NASA Astrophysics Data System (ADS)

    Chen, Liang; Deng, Jin-Xiang; Kong, Le; Cui, Min; Chen, Ren-Gang; Zhang, Zi-Jia

    2015-04-01

    Rubrene thin films are deposited on quartz substrates and silver nanoparticles (Ag NPs) films by the thermal evaporation technique. The optical properties of rubrene thin film are investigated in a spectral range of 190 nm-1600 nm. The analysis of the absorption coefficient (α) reveals direct allowed transition with a corresponding energy of 2.24 eV. The photoluminescence (PL) peak of the rubrene thin film is observed to be at 563 nm (2.21 eV). With the use of Ag NPs which are fabricated by radio-frequency (RF) magnetron sputtering on the quartz, the PL intensity is 8.5 times that of as-deposited rubrene thin film. It is attributed to the fact that the surface plasmon enhances the photoluminescence. Project supported by the Funding for the Development Project of Beijing Municipal Education Commission of Science and Technology, China (Grant No. KZ201410005008), the Natural Science Foundation of Beijing City, China (Grant No. 4102014), and the Graduate Science Fund of the Beijing University of Technology, China (Grant No. ykj-2013-9835).

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. Synthesis, structural, optical and thermal studies of an organic nonlinear optical 4-aminopyridinium maleate single crystal

    NASA Astrophysics Data System (ADS)

    Pandi, P.; Peramaiyan, G.; Kumar, M. Krishna; Kumar, R. Mohan; Jayavel, R.

    2012-03-01

    Synthesis and growth of a novel organic nonlinear optical (NLO) crystal of 4-aminopyridinium maleate (4APM) in larger size by the slow evaporation solution growth technique are reported. Single crystal and powder X-ray diffraction analyses reveal that 4APM crystallizes in monoclinic system with space group P21 with cell parameters a = 8.140(4) Å, b = 5.457(5) Å, c = 10.926(10) Å and volume = 481.4(7) Å3. The grown crystal has been characterized by Fourier transform infrared and UV-visible spectral analyses. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) have been carried out to study its thermal properties. Dielectric measurements have been carried out to study the distribution of charges within the crystal. The mechanical strength of the crystal has been studied by using Vickers' microhardness test. The etching studies have been carried out on the grown crystal. The Kurtz and Perry powder SHG technique confirms the NLO property of the grown crystal and the SHG efficiency of 4APM was found to be 4.8 times greater than that of KDP crystal.

  6. Optical and thermal properties of some indolenine cyanine dyes used as optical recording materials

    NASA Astrophysics Data System (ADS)

    Sun, Shuqing; Chen, Ping; Zheng, Deshui; Okasaki, Tsuneki; Hayami, Masaaki

    1998-08-01

    Compact Disc Recordable (CD-R) and Digital Versatile Disc Recordable (DVD-R) are discs where enormous mounts of digital data can be recorded. The reflection, absorption and transmission rate of laser beam in the layer of CD-R at 780 nm and DVD-R at 650 nm with no reflecting layer were numerically calculated and optical properties of a dye film was measured. The results indicate that it is preferable to use dye as the recording media with n and k value in the range of 2.0 to 2.8 and 0.02 to 0.22, respectively. Thermal properties of these dye materials were analyzed by Differential Scanning Calorie method. The decomposition temperature of dyes were varied from 200 to 300 degree(s)C resulted from different methine length, substitutes and counter anions. The optical recording mechanism of CD-R and DVD-R were also briefly discussed based on the above results.

  7. 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.

  8. 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

  9. Determination of the coefficient of thermal expansion with embedded long-gauge fiber optic sensors

    NASA Astrophysics Data System (ADS)

    Feng, Xin; Sun, Changsen; Zhang, Xiaotan; Ansari, Farhad

    2010-06-01

    A novel methodology for the determination of the coefficient of thermal expansion (CTE) is proposed by using long-gauge fiber optic sensors. Current approaches either neglect the shear-lag effects or do not compensate for the thermo-optic effects in optical fibers leading to precision errors. The embedded long-gauge sensor measures not only the thermo-optic effect due to temperature fluctuations, but also the strain-optic effect created by thermal stresses. However, it is difficult to directly separate these two effects in the measurements. Given that only the strain-optic effect correlates to the CTE of a host material, it is necessary to compensate for the thermo-optic effect. An additional error is attributed to the fact that the shear-lag effect is ignored, i.e. assumption is made that the strain distribution in the optical fiber is the same as that in the host material. This study reports on the development of a methodology for the computation of the coefficient of thermal expansion in structural materials using long-gauge fiber optic sensors. The proposed formulations account for both the shear-lag and thermo-optic effects.

  10. 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.

  11. 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.

  12. Overview of Optical and Thermal Laser-Tissue Interaction and Nomenclature

    NASA Astrophysics Data System (ADS)

    Welch, Ashley J.; van Gemert, Martin J. C.

    The development of a unified theory for the optical and thermal response of tissue to laser radiation is no longer in its infancy, though it is still not fully developed. This book describes our current understanding of the physical events that can occur when light interacts with tissue, particularly the sequence of formulations that estimate the optical and thermal responses of tissue to laser radiation. This overview is followed by an important chapter that describes the basic interactions of light with tissue. Part I considers basic tissue optics. Tissue is treated as an absorbing and scattering medium and methods are presented for calculating and measuring light propagation, including polarized light. Also, methods for estimating tissue optical properties from measurements of reflection and transmission are discussed. Part II concerns the thermal response of tissue owing to absorbed light, and rate reactions are presented for predicting the extent of laser induced thermal damage. Methods for measuring temperature, thermal properties, rate constants, pulsed ablation and laser tissue interactions are detailed. Part III is devoted to examples that use the theory presented in Parts I and II to analyze various medical applications of lasers. Discussions of Optical Coherence Tomography (OCT), forensic optics, and light stimulation of nerves are also included.

  13. Optical layer development for thin films thermal conductivity measurement by pulsed photothermal radiometry

    SciTech Connect

    Martan, J.

    2015-01-15

    Measurement of thermal conductivity and volumetric specific heat of optically transparent thin films presents a challenge for optical-based measurement methods like pulsed photothermal radiometry. We present two approaches: (i) addition of an opaque optical layer to the surface and (ii) approximate correction of the mathematical model to incorporate semitransparency of the film. Different single layer and multilayer additive optical layers were tested. The materials of the optical layers were chosen according to analysis and measurement of their optical properties: emissivity and absorption coefficient. Presented are thermal properties’ measurement results for 6 different thin films with wide range of thermal conductivity in three configurations of surface: as deposited, added Ti layer, and added Ti/TiAlSiN layer. Measurements were done in dependence on temperature from room temperature to 500 °C. The obtained thermal effusivity evolution in time after the laser pulse shows different effects of the surface layers: apparent effusivity change and time delay. Suitability of different measurement configurations is discussed and results of high temperature testing of different optical layers are presented.

  14. Analytical model of optical field distribution of thin disk laser with thermal-optical aberration gain medium

    NASA Astrophysics Data System (ADS)

    Zhu, Guangzhi; Qiu, Yuli; Wang, Zexiong; Zhu, Xiao; Zhu, Changhong

    2016-08-01

    An analytical model is developed to analyze the optical field distribution of thin disk laser with a thermal-optical aberration gain medium. The fundamental mode field distribution is calculated by using the eigenvector method of the resonator transit matrix for different pumping parameters. The analytical results show that the uniformity of the pumping spot is an important factor that impacts the beam quality of thin disk laser. The uniform pumping spot is beneficial to decrease thermal aberration and Optical Path Difference (OPD) of thin disk crystal, and to improve the beam quality. However, the beam quality still decreases slightly with the increasing of pumping intensity under the uniform pumping condition. The main reason for degradation of beam quality is the aspherical part of OPD which leads to diffraction losses of the resonator and wavefront deformation.

  15. Molecular structure-property correlations from optical nonlinearity and thermal-relaxation dynamics.

    PubMed

    Bhattacharyya, Indrajit; Priyadarshi, Shekhar; Goswami, Debabrata

    2009-02-01

    We apply ultrafast single beam Z-scan technique to measure saturation absorption coefficients and nonlinear-refraction coefficients of primary alcohols at 1560 nm. The nonlinear effects result from vibronic transitions and cubic nonlinear-refraction. To measure the pure total third-order nonlinear susceptibility, we removed thermal effects with a frequency optimized optical-chopper. Our measurements of thermal-relaxation dynamics of alcohols, from 1560 nm thermal lens pump and 780 nm probe experiments revealed faster and slower thermal-relaxation timescales, respectively, from conduction and convection. The faster timescale accurately predicts thermal-diffusivity, which decreases linearly with alcohol chain-lengths since thermal-relaxation is slower in heavier molecules. The relation between thermal-diffusivity and alcohol chain-length confirms structure-property relationship.

  16. Optical and Thermal Analysis of the Time Evolution of Curing in Resins by Photothermal Techniques

    NASA Astrophysics Data System (ADS)

    Martínez-Torres, P.; Zambrano-Arjona, M.; Aguilar, G.; Alvarado-Gil, J. J.

    2012-11-01

    Four shades of a commercial visible-light curing dental resin are analyzed using photothermal techniques. The thermal effusivities of the dental resin shades before curing are measured using a variant of the conventional photoacoustic technique. The thermal diffusivities before and after curing are measured using infrared photothermal radiometry in the forward emission configuration. The time evolution process of the photocuring resin is monitored by photothermal radiometry in the forward and backward emission configurations. Inversion of the time evolution signal of the different configurations used permits one to obtain the time evolution of the thermal and optical properties during the photocuring. The thermal effusivity and thermal diffusivity exhibit exponential growth, while the optical absorption decreases exponentially due to the curing process. The relationship of these phenomena with the decrease of monomer concentration induced by the curing is discussed.

  17. Simultaneous measurement of thermal diffusivity and optical absorption coefficient using photothermal radiometry. II Multilayered solids

    NASA Astrophysics Data System (ADS)

    Salazar, Agustín; Fuente, Raquel; Apiñaniz, Estibaliz; Mendioroz, Arantza; Celorrio, R.

    2011-08-01

    The aim of this work is to analyze the ability of modulated photothermal radiometry to retrieve the thermal diffusivity and the optical absorption coefficient of layered materials simultaneously. First, we extend the thermal quadrupole method to calculate the surface temperature of semitransparent multilayered materials. Then, this matrix method is used to evaluate the influence of heat losses by convection and radiation, the influence of the use of thin paint layers on the accuracy of thermal diffusivity measurements, and the effect of lateral heat diffusion due to the use of Gaussian laser beams. Finally, we apply the quadrupole method to retrieve (a) the thermal contact resistance in glass stacks and (b) the thermal diffusivity and optical absorption coefficient depth profiles in heterogeneous materials with continuously varying physical properties, as is the case of functionally graded materials and partially cured dental resins.

  18. Thermal dissipation modeling in optical components modules for electrical power consumption optimization

    NASA Astrophysics Data System (ADS)

    Sabot, Germain; Chaudenson, Julien; Raulin, Franck; Jacquet, Jo"l.

    2010-02-01

    In a semi-conductor optical amplifier (SOA) as in any other optical devices, the performances that can be reached is strongly dependent on the chip temperature. For example, the optical output power of a laser or the optical gain in a SOA is reduced when the temperature of the junction increases. This latter can be controlled or monitored thanks to a thermo-electronic cooler (or a Peltier element) and a thermistor. In this paper, we first have calculated the thermal resistance of various semiconductor structures such as buried or ridge waveguides lasers. We then calculate the Peltier consumption necessary to maintain a given temperature. The influence of the thermistor position as well as the module conception have been investigated in these calculation. The size of the different mechanical elements, the nature and thermal properties of the material use for the module fabrication have been found to play an important role in the thermal performance of the optical modules. The Peltier size is defined by maximizing its efficiency. It depends on the power to be dissipated as well as the temperature operation of the device. The latter depends on the performance expected by the optical devices. We discussed the optimization of the device structure associated to its packaging to find the best compromise between performance and electrical consumption. The trade-off found depends on the temperature at which the device operates as well as on the thermal power to be dissipated.

  19. Thermal contacts through mechanical moving parts in low thermal budget optical cryogenic assemblies

    NASA Astrophysics Data System (ADS)

    Testard, O. A.

    Ball bearings or mechanical reductors constitute thermal impedances that can reach the known poor level of thermal radiative exchange at low temperatures, 6 × 10 4 Km -2 W -1. This can induce unacceptable hoop stresses when cooling down high heat capacity components or create thermal heterogeneities on scientific experiments and superconducting devices which are supposed to be cold and isothermic. Soft metallic contacts afford good thermal contacts but cause higher mechanical torque and then increase the heat flux through the contact line. The developments described here were made on one of the four Infrared Space Observatory experiments.

  20. 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.

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

    NASA Astrophysics Data System (ADS)

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

    1995-03-01

    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.

  2. Thermal Emission from Transiting Very Hot Jupiters: Prospects for Ground-based Detection at Optical Wavelengths

    NASA Astrophysics Data System (ADS)

    López-Morales, Mercedes; Seager, Sara

    2007-10-01

    Very hot Jupiters (VHJs) are defined as Jupiter-mass extrasolar planets with orbital periods shorter than 3 days. For low albedos the effective temperatures of irradiated VHJs can reach 2500-3000 K. Thermal emission from VHJs is therefore potentially strong at optical wavelengths. We explore the prospects of detecting optical-wavelength thermal emission during secondary eclipse with existing ground-based telescopes. We show that OGLE-TR-56b and OGLE-TR-132b are the best-suited candidates for detection and that the prospects are highest around z' band (~0.9 μm). We also speculate that any newly discovered VHJs with the right combination of orbital separation and host star parameters could be thermally detected in the optical. The lack of detections would still provide constraints on the planetary albedos and reradiation factors.

  3. 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.

  4. Thermal lens microscope sensitivity enhancement using a passive Fabry–Perot-type optical cavity

    NASA Astrophysics Data System (ADS)

    Cabrera, H.; Cedeño, E.; Grima, P.; Marín, E.; Calderón, A.; Delgado, O.

    2016-05-01

    We developed a thermal lens microscope equipped with a passive optical cavity, which provides an optical feedback for the multiple pass of the probe laser beam to enhance sensitivity. Considering the maximum absorption peak for Fe(II) at 532 nm wavelength, we have achieved a 6.6-fold decrease in the limit of detection (LOD) to a level of 0.077 μg · l‑1 without a cavity. The possibilities to use thermal lens detection combined with an optical resonator was proposed and a drastic thermal lens signal enhancement was achieved using very low excitation power. The corresponding LOD for Fe(II) was further decreased to the level of 0.006 μg · l‑1 which represents an 85-fold decrease of the LOD value. This setup is a promising device, which can be applied as a sensitive tool for detecting chemical traces in small volumes of solutions.

  5. 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.

  6. Novel thermal lens for remote heating/cooling designed with transformation optics.

    PubMed

    Liu, Yichao; Sun, Fei; He, Sailing

    2016-03-21

    Remote thermal focusing/refrigeration by suppressing thermal diffusion can be achieved with the help of the novel thermal lens proposed in this paper. Our thermal lens is designed using transformation optics, and has several advantages. Firstly, it is a remote controlling device, i.e. the temperature is increased or decreased only in the heat/cold source and the target points, and the temperature in the area between the source and target points is not influenced. Secondly, the heat/cold sources can move freely inside the lens, and hence the focused points outside the lens can be adjusted dynamically. Numerical simulations are given to verify the novel properties (such as thermal focusing effect, remote refrigeration and remote thermal diffusion suppressing) of the proposed device, which cannot be achieved by any other traditional method. PMID:27136765

  7. Measurement of black carbon (BC) by an optical method and a thermal-optical method: Intercomparison for four sites

    NASA Astrophysics Data System (ADS)

    Ahmed, Tanveer; Dutkiewicz, Vincent A.; Shareef, Akhtar; Tuncel, Gurdal; Tuncel, Semra; Husain, Liaquat

    2009-12-01

    Comparison of black carbon (BC) measurements obtained by two methods was performed for aerosols samples collected on Whatman 41 (W-41) filters, using an optical method (Magee Scientific Optical Transmissometer Model OT-21) and a thermal-optical method (Sunset Laboratory Thermal-optical analyzer). Samples were collected from four sites: Albany (a small urban site, NY), Antalya (coastal site, Turkey), Whiteface Mountain (remote site, NY) and Mayville (rural site, NY). At Albany, comparison between the two methods showed excellent agreement; a least-squares regression line yielded a slope of 1.02, and r2 = 0.88. Similar comparisons at Antalya (slope of 1.02, r2 = 0.5) and Whiteface Mountain (slope of 0.92 and r2 = 0.58) also gave very good relationship. At Mayville, the relationship between the two methods yielded somewhat lower regression: a slope of 0.75, and r2 = 0.44. The data from the four locations, when plotted together, yielded an excellent agreement: a slope of 0.91, and r2 of 0.84. Based on our measurements, it appears that optical measurement using the OT-21 can be successfully applied to determination of BC in W-41 filters. However, because of the variability in the chemical composition of BC aerosol at different locations, it is suggested that the calibration of OT-21 when using W-41 filters should be performed with a statistically significant numbers of samples for specific sites.

  8. Thermal and optical characterization of natural and artificial marble for roof and external floor installations

    NASA Astrophysics Data System (ADS)

    Asdrubali, F.; Baldinelli, G.; Bianchi, F.; Presciutti, A.; Rossi, F.; Schiavoni, S.

    2015-11-01

    Some types of buildings need to use certain materials for aesthetic reasons, like churches or mosques. Marble is one of the most common materials usually installed on roofs and floors. The measurement of the thermal and optical characteristics can be useful to understand its behaviour when it is subjected to thermal loads such as solar radiation or high temperature winds. The paper shows a comparison study between natural and artificial types of marble, to investigate the thermal characteristics both in steady-state and transient conditions. Optical properties and surface emissivity were evaluated, in order to calculate the Solar Reflectance Index (SRI); the specific heat, the thermal conductivity and the density were measured to define the thermophysical properties useful for the dynamic analysis. Finally, a test bench was created to check the marble behaviour under known artificial irradiation.

  9. 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

  10. Photothermal absorption measurements for improved thermal stability of high-power laser optics

    NASA Astrophysics Data System (ADS)

    Stubenvoll, M.; Schäfer, B.; Mann, K.; Walter, A.; Zittel, L.

    2013-11-01

    An absorption measurement system was set up deploying a Hartmann-Shack wavefront sensor with extreme sensitivity to accomplish spatially resolved monitoring of thermally induced wavefront distortions. Photothermal absorption measurements in the near-infrared range were performed for both the characterization of optical materials and complete F-Theta lenses, utilizing a 500 W Yb fiber laser (λ = 1070 nm) to induce thermal load. Different combinations of bulk materials and AR coatings were examined to minimize absorption and to evaluate potential approaches for thermal compensation. Additionally, bulk and surface / coating absorption coefficients were determined by means of curve-fitting procedures. Furthermore, F-Theta lenses were tested to gain understanding of the thermal behavior of the entire optical system.

  11. 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. PMID:25063109

  12. A study of the optical and thermal properties of nonlinear mercury thiogallate crystals

    SciTech Connect

    Badikov, Valerii V; Kuzmin, Nikolai V; Laptev, Vladimir B; Malinovsky, Aleksandr L; Ryabov, Evgenii A; Mitin, Konstantin V; Nazarov, Gennadii S; Seryogin, A M; Schebetova, Nadezhda I

    2004-05-31

    The technology of growing mercury thiogallate crystals (HgGa{sub 2}S{sub 4}) is improved and high-quality bulk samples are produced. The basic optical and thermal properties of these crystals are studied. The transmission spectra of mercury thiogallate are measured and its nonlinear characteristics such as the quadratic susceptibility, tuning curves, and the optical-damage resistance are also determined. The specific heat and thermal conductivity of HgGa{sub 2}S{sub 4} are measured. It is concluded that the combined properties of HgGa{sub 2}S{sub 4} crystals can provide for them a leading position among the materials used in nonlinear-optical devices for mid-IR-frequency conversion. (nonlinear optical phenomena)

  13. Thermo-optically driven adaptive mirror based on thermal expansion: preparation and resolution

    NASA Astrophysics Data System (ADS)

    Reinert, Felix; Lüthy, W.

    2005-12-01

    A thermo-optically driven adaptive mirror is presented. It is based on the thermal expansion of a thin film heated with a light pattern. We describe a procedure for the preparation of a silicon elastomer with a high-quality optical surface. This material, Sylgard 184, has a high linear thermal expansion coefficient of 3.1μ10-4 K-1. Surface modulations are recorded in an interferometer. Modulations of 350 nm result at an intensity of 370 mW/cm2. The resolution is measured with a line pattern. The contrast drops to 30 % at 1.6 line pairs per millimeter (lp/mm).

  14. Thermo-optically driven adaptive mirror based on thermal expansion: preparation and resolution.

    PubMed

    Reinert, Felix; Lüthy, W

    2005-12-26

    A thermo-optically driven adaptive mirror is presented. It is based on the thermal expansion of a thin film heated with a light pattern. We describe a procedure for the preparation of a silicon elastomer with a high-quality optical surface. This material, Sylgard 184, has a high linear thermal expansion coefficient of 3.110-4 K-1. Surface modulations are recorded in an interferometer. Modulations of 350 nm result at an intensity of 370 mW/cm2. The resolution is measured with a line pattern. The contrast drops to 30 % at 1.6 line pairs per millimeter (lp/mm).

  15. Embedding properties of optical fibers integrated into ceramic coatings obtained by wire flame thermal spray

    NASA Astrophysics Data System (ADS)

    Duo, Yi; Costil, Sophie; Pfeiffer, Pierre; Serio, Bruno

    2015-03-01

    The elaboration of smart materials with optical fiber sensors embedded into several dissimilar layers is capable of monitoring various system parameters inside the layered structure without damaging the host structure itself. This work mainly concentrates on the thermal elaboration process used to embed optical fibers into ceramic coating layers and their characterization. A new mechanical holder is first proposed in order to maintain the optical fiber during the thermal spray process and protect it from the strong atmospheric turbulence caused by the heat flux. Wire flame thermal spray where particles are propelled on the substrate at a temperature of more than 2000 °C is chosen as the elaboration process and the favorable elaboration conditions are evaluated. The microscopic characteristics of both the surface and cross-section of the embedding structure are evaluated, and the mechanical adhesion strength of the embedded optical fiber is then measured and discussed. The results show that the optical fiber remains undamaged after the thermal spray process and keeps perfect adhesion with the ceramic coating, making the former a competitive method to elaborate the embedded hybrid structure.

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

    NASA Astrophysics Data System (ADS)

    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.

  17. Estimation of thermal conductivity of amorphous silicon thin films from the optical reflectivity measurement.

    PubMed

    Moon, Seung-Jae; Choi, Jung Hyun

    2013-09-01

    Amorphous silicon (a-Si) thin film material is widely used in liquid crystal display and solar cell applications. Knowledge of its properties is important in enhancing device performance. The properties of a-Si thin film have not been well understood due to the lack of periodicity of the structure. Furthermore, thermal conductivity of a-Si thin film is a key parameter to understand the complex phase transformation mechanism from a-Si thin film to polysilicon thin film by analyzing the transient temperature during the laser recrystallization process. In this work, thermal conductivity of a-Si thin film was determined by measuring optical reflectivity. A-Si thin film was irradiated with a KrF excimer laser beam to raise its temperature. The raised film temperature affects temperature-dependent optical properties such as refractive indices and extinction coefficients. The temperature-dependent optical properties of refractive indices and extinction coefficients of a-Si thin film were measured by ellipsometry. In-situ transient reflectivity at the wavelength of 633 nm was obtained during the excimer laser irradiation. The numerical simulation of one-dimensional conduction equation was solved so that transient reflectivities were calculated with temperature-dependent optical properties combined with thin film optics. Therefore, a well-fitted thermal conductivity was determined by comparing the numerically obtained transient reflectivity with the experimentally measured reflectivity data. The determined thermal conductivity of a-Si thin films was 1.5 W/mK.

  18. 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.

  19. 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.

  20. Optical and thermal depth profile reconstructions of inhomogeneous photopolymerization in dental resins using photothermal waves

    NASA Astrophysics Data System (ADS)

    Martínez-Torres, P.; Mandelis, A.; Alvarado-Gil, J. J.

    2010-09-01

    Photopolymerization is a process that depends, among other factors, on the optical properties of polymerized materials. In turn, this process affects longitudinal light transport in these materials, thereby altering their optical absorption coefficient which is thus expected to exhibit depth dependence. Furthermore, polymerization affects the thermal properties of these materials. A robust theoretical approach to the study of the depth-dependent optical absorption coefficient, β(x ), and thermal diffusivity, α(x ), in materials exhibiting depth profiles of these parameters has been developed through the photothermal inverse problem based on the concept of the thermal-harmonic oscillator. Using this concept in the frequency-domain nonhomogeneous photothermal-wave boundary-value problem, the simultaneous reconstruction of arbitrary simultaneous optical and thermal depth profiles was achieved using a multiparameter fitting method to the experimental amplitude and phase. As a first application of the theory to partially polymerized Alert Composite (shade A3) dental resin, with curing induced by a blue light-emitting diode, the β(x ) and α(x ) depth profiles were reconstructed from photothermal radiometric frequency-scanned data. A strong anticorrelation of these two depth profiles was observed and was interpreted in terms of photochemical processes occurring during the optical (photocuring) creation of long polymeric chains in the resin. The photothermally reconstructed depth profiles may have implications for the optimization of blue light curing methods using such resins in dental clinical practice.

  1. Estimation of thermal conductivity of amorphous silicon thin films from the optical reflectivity measurement.

    PubMed

    Moon, Seung-Jae; Choi, Jung Hyun

    2013-09-01

    Amorphous silicon (a-Si) thin film material is widely used in liquid crystal display and solar cell applications. Knowledge of its properties is important in enhancing device performance. The properties of a-Si thin film have not been well understood due to the lack of periodicity of the structure. Furthermore, thermal conductivity of a-Si thin film is a key parameter to understand the complex phase transformation mechanism from a-Si thin film to polysilicon thin film by analyzing the transient temperature during the laser recrystallization process. In this work, thermal conductivity of a-Si thin film was determined by measuring optical reflectivity. A-Si thin film was irradiated with a KrF excimer laser beam to raise its temperature. The raised film temperature affects temperature-dependent optical properties such as refractive indices and extinction coefficients. The temperature-dependent optical properties of refractive indices and extinction coefficients of a-Si thin film were measured by ellipsometry. In-situ transient reflectivity at the wavelength of 633 nm was obtained during the excimer laser irradiation. The numerical simulation of one-dimensional conduction equation was solved so that transient reflectivities were calculated with temperature-dependent optical properties combined with thin film optics. Therefore, a well-fitted thermal conductivity was determined by comparing the numerically obtained transient reflectivity with the experimentally measured reflectivity data. The determined thermal conductivity of a-Si thin films was 1.5 W/mK. PMID:24205662

  2. Thermal expansion data for eight optical materials from 60 K to 300 K.

    PubMed

    Browder, J S; Ballard, S S

    1977-12-01

    Coefficients of linear thermal expansion are reported, in the range 60 K to room temperature, for eight optical materials: Polytran potassium chloride and Polytran calcium fluoride-Harshaw; chemical-vapor-deposited (CVD) zinc sulfide and zinc selenide-Raytheon; germanium (single-crystal and polycrystal); crystalline magnesium fluoride, potassium dihydrogen phosphate (KDP), and lithium niobate-Harshaw. The last three are anisotropic crystals; thermal expansion was measured both parallel and perpendicular to the c axis. PMID:20174331

  3. Thermal optical surface properties and high-temperature solar energy conversion

    NASA Technical Reports Server (NTRS)

    Wen, L.

    1978-01-01

    The effects of thermal surface properties on the performance of representative point focusing solar power plants are assessed in this paper. The tradeoff relationships are presented in terms of normalized system performance as a function of thermal optical design parameters. Crucial surface properties include solar reflectance, specular spreading due to microscopic roughness, surface error due to manufacturing slope tolerance or waviness and concentrator pointing accuracy. Two representative power conversion systems, a Rankine steam cycle and an open air Brayton cycle, are considered.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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 Å3 with space group I42d (1 2 2)). 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.

  10. 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.

  11. Integrated thermal-optical simulations of a GNSS Retroreflector Array

    NASA Astrophysics Data System (ADS)

    Boni, A.; Cantone, C.; Dell'Agnello, S.; Ciocci, E.; Contessa, S.; Delle Monache, G. O.; Lops, C.; Maiello, M.; Martini, M.; Mondaini, C.; Patrizi, G.; Porcelli, L.; Salvatori, L.; Tibuzzi, M.; Tuscano, P.; Vittori, R.; Bianco, G.

    2015-07-01

    Satellite Laser Ranging (SLR) is one of the most precise and cost effective satellite positioning techniques, used for many years on geodetic, Earth observation and scientific satellites. In the last decades it has been applied on radio-navigation satellites as well, however still in a limited way. The benefits that such technique could bring to these satellites are many, but, in order to support at best their tracking, some improvements need to be done; one is the enhancement of optical response of SLR payloads throughout the orbit. INFN-LNF with the ASI-INFN project ETRUSCO-2 studied hardware and software solution to optimize the optical response of such payloads, with the design and fabrication of a GNSS Retroreflector Array (GRA). We simulated the performance of a model of the GRA in a specific orbit of Galileo, showing contained variation of optical intensity, approximately 5%, throughout the orbit. A comparison between two polarization states, linear and circular, proves how a circularly polarized beam could reduce, up to 3 times, intensity fluctuations at a fixed velocity aberration.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. Development and characterization of thermally stable electro-optic polymers and devices (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Otomo, Akira; Aoki, Isao; Yamada, Chiyumi; Yamada, Toshiki

    2015-10-01

    Electro-optic (EO) polymers are key materials for next generation optical communications not only in wide area network but also in local area and storage area network because EO polymer modulator can be operated at fast speed more than 100 GHz with low energy consumption and can be miniaturized in combination with silicon photonics. In practical applications, thermal stability is one of the important issues to be considered for developing EO polymers. Since EO activity of the polymer is proportional to dipole orientation factor of the EO moieties, electric field assisted poling around glass transition temperature (Tg) of the polymer is necessary. However, the poled order of the molecules relaxes gradually at finite temperature, and then EO activity decreases after long period of time. We have successfully developed thermally stable EO polymers that have high-Tg up to 180 °C. They show excellent thermal stability with the Telcordia thermal test. Thermal stability is also characterized by thermally stimulated depolarization current (TSDC) measurement. Analyzing the TSDC, we can estimate the activation energy and relaxation time of polarization at any temperature. We will discuss thermal stability of the high-Tg EO polymers and devices.

  17. 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.

  18. Dimensional stability testing in thermal vacuum of the CHEOPS optical telescope assembly

    NASA Astrophysics Data System (ADS)

    Klop, W. A.; Verlaan, A. L.

    2016-07-01

    The CHEOPS mission (CHaracterising ExOPlanet Satellite) is dedicated to searching for exoplanetary transits by performing ultra-high precision photometry on bright stars already known to host planets. A 32cm diameter on-axis Ritchey-Chrétien telescope is used for imaging onto a single cooled detector. With integration times up to 48 hours the thermal stability of the telescope and its structure are key to the performance. Using a multi-lateration interferometer setup TNO has successfully demonstrated the μm-level stability of the Structural Thermal Model (STM2) of the Optical Telescope Assembly (OTA) in thermal vacuum. This OTA was later upgraded to become the Flight Model. Experiments comprise thermal vacuum cycling, thermal vacuum stability testing where axial and lateral deformations are measured to the nm-level sensitivity.

  19. 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. PMID:26479672

  20. 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.

  1. Thermal conduction properties of Mo/Si multilayers for extreme ultraviolet optics

    NASA Astrophysics Data System (ADS)

    Bozorg-Grayeli, Elah; Li, Zijian; Asheghi, Mehdi; Delgado, Gil; Pokrovsky, Alexander; Panzer, Matthew; Wack, Daniel; Goodson, Kenneth E.

    2012-10-01

    Extreme ultraviolet (EUV) lithography requires nanostructured optical components, whose reliability can be influenced by radiation absorption and thermal conduction. Thermal conduction analysis is complicated by sub-continuum electron and phonon transport and the lack of thermal property data. This paper measures and interprets thermal property data, and their evolution due to heating exposure, for Mo/Si EUV mirrors with 6.9 nm period and Mo/Si thickness ratios of 0.4/0.6 and 0.6/0.4. We use time-domain thermoreflectance and the 3ω method to estimate the thermal resistance between the Ru capping layer and the Mo/Si multilayers (RRu-Mo/Si = 1.5 m2 K GW-1), as well as the out-of-plane thermal conductivity (kMo/Si 1.1 W m-1 K-1) and thermal anisotropy (η = 13). This work also reports the impact of annealing on thermal conduction in a co-deposited MoSi2 layer, increasing the thermal conductivity from 1.7 W m-1 K-1 in the amorphous phase to 2.8 W m-1 K-1 in the crystalline phase.

  2. 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.

  3. Thermal annealing of thin PECVD silicon-oxide films for airgap-based optical filters

    NASA Astrophysics Data System (ADS)

    Ghaderi, M.; de Graaf, G.; Wolffenbuttel, R. F.

    2016-08-01

    This paper investigates the mechanical and optical properties of thin PECVD silicon-oxide layers for optical applications. The different deposition parameters in PECVD provide a promising tool to manipulate and control the film structure. Membranes for use in optical filters typically are of ~λ/4n thickness and should be slightly tensile for remaining flat, thus avoiding scattering. The effect of the thermal budget of the process on the mechanical characteristics of the deposited films was studied. Films with compressive stress ranging from  ‑100 to 0 MPa were deposited. Multiple thermal annealing cycles were applied to wafers and the in situ residual stress and ex situ optical properties were measured. The residual stress in the films was found to be highly temperature dependent. Annealing during the subsequent process steps results in tensile stress from 100 to 300 MPa in sub-micron thick PECVD silicon-oxide films. However, sub-100 nm thick PECVD silicon-oxide layers exhibit a lower dependence on the thermal annealing cycles, resulting in lower stress variations in films after the annealing. It is also shown that the coefficient of thermal expansion, hence the residual stress in layers, varies with the thickness. Finally, several free-standing membranes were fabricated and the results are compared.

  4. 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

  5. Generalized 1D photopyroelectric technique for optical and thermal characterization of liquids

    NASA Astrophysics Data System (ADS)

    Balderas-López, J. A.

    2012-06-01

    The analytical solution for the one-dimensional heat diffusion problem for a three-layer system, in the Beer-Lambert model for light absorption, is used for the implementation of a photopyroelectric (PPE) methodology for thermal and optical characterization of pigments in liquid solution, even for those ones potentially harmful to the pyroelectric sensor, taking the liquid sample's thickness as the only variable. Exponential decay of the PPE amplitude followed by a constant PPE phase for solutions at low pigment concentration, and exponential decay of the PPE amplitude but a linear decrease of the PPE phase for the concentrated ones are theoretically shown, allowing measurements of the optical absorption coefficient (at the wavelength used for the analysis) and the thermal diffusivity for the liquid sample, respectively. This PPE methodology was tested by measuring the thermal diffusivity of a concentrated solution of methylene blue in distilled water and the optical absorption coefficient, at two wavelengths (658 and 785 nm), of water solutions of copper sulfate at various concentrations. These optical parameters were used for measuring the molar absorption coefficient of this last pigment in water solution at these two wavelengths. This last optical property was also measured using a commercial spectrometer, finding very good agreement with the corresponding ones using this PPE technique.

  6. Thermal and Optical Activation Mechanisms of Nanospring-Based Chemiresistors

    PubMed Central

    Dobrokhotov, Vladimir; Oakes, Landon; Sowell, Dewayne; Larin, Alexander; Hall, Jessica; Barzilov, Alexander; Kengne, Alex; Bakharev, Pavel; Corti, Giancarlo; Cantrell, Timothy; Prakash, Tej; Williams, Joseph; Bergman, Leah; Huso, Jesse; McIlroy, David

    2012-01-01

    Chemiresistors (conductometric sensor) were fabricated on the basis of novel nanomaterials—silica nanosprings ALD coated with ZnO. The effects of high temperature and UV illumination on the electronic and gas sensing properties of chemiresistors are reported. For the thermally activated chemiresistors, a discrimination mechanism was developed and an integrated sensor-array for simultaneous real-time resistance scans was built. The integrated sensor response was tested using linear discriminant analysis (LDA). The distinguished electronic signatures of various chemical vapors were obtained at ppm level. It was found that the recovery rate at high temperature drastically increases upon UV illumination. The feasibility study of the activation method by UV illumination at room temperature was conducted. PMID:22778604

  7. 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}.

  8. 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.

  9. 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.

  10. 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. PMID:23089651

  11. Nonreciprocal phase shift caused by magnetic-thermal coupling of a polarization maintaining fiber optic gyroscope.

    PubMed

    Zhang, Dengwei; Zhao, Yuxiang; Fu, Wenlan; Zhou, Wenqing; Liu, Cheng; Shu, Xiaowu; Che, Shuangliang

    2014-03-15

    A theory for nonreciprocal phase shift caused by cross coupling generated in a polarization maintaining (PM) fiber optic gyroscope (FOG) under the combined action of magnetic and temperature fields is proposed. The magnetic-thermal coupling in the FOG originates from the interaction of the magnetic field, fiber twist, birefringence caused by thermal stress, and the intrinsic and bending birefringence of the fiber. The cross coupling changes with temperature. When the PM fiber has a diameter of 250 μm, beat length of 3 mm, length of 500 m, twist rate of 1  rad/m, and optical source wavelength of 1310 nm, the maximum degree of magnetic-thermal coupling generated by a 1 mT radial magnetic field within the temperature range of -20°C  to 60°C is -5.47%.

  12. Third-order optical intensity correlation measurements of pseudo-thermal light

    NASA Astrophysics Data System (ADS)

    Chen, Xi-Hao; Wu, Wei; Meng, Shao-Ying; Li, Ming-Fei

    2014-09-01

    Third-order Hanbrury Brown—Twiss and double-slit interference experiments with a pseudo-thermal light are performed by recording intensities in single, double and triple optical paths, respectively. The experimental results verifies the theoretical prediction that the indispensable condition for achieving a interference pattern or ghost image in Nth-order intensity correlation measurements is the synchronous detection of the same light field by each reference detector, no matter the intensities recorded in one, or two, or N optical paths. It is shown that, when the reference detectors are scanned in the opposite directions, the visibility and resolution of the third-order spatial correlation function of thermal light is much better than that scanned in the same direction, but it is no use for obtaining the Nth-order interference pattern or ghost image in the thermal Nth-order interference or ghost imaging.

  13. Optical testing technique for the evaluation of mechanical mount thermal stability

    NASA Astrophysics Data System (ADS)

    Tapply, Jon K.

    1999-09-01

    Precise optical stability requirements for a military laser required the establishment of detailed error and tolerance budgets of the mechanical system. In order to verify these budgets and also to fully understand the true dynamic stability of the mechanical mounts, extensive thermal testing was performed. This paper present a test technique established to provide a consistent testing process from which results could be used with confidence. Utilizing a readily available optical measurement device and impose test fixtures, this technique provides the designer with a powerful evaluation tool to verify design performance. Various types of result can be obtained using this technique, such as: optical element distortion at temperature, unrecoverable static shifting to the mount, dynamic movement effects and repeatability. These results can be further extrapolated into qualitative assessments of the thermal stability of specific mount design technique. When compiled into a design database, this will provide invaluable information for future design choices.

  14. 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

  15. 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

  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. 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.

  18. 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

  19. 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

  20. 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. PMID:22163816

  1. Optical Fiber Sensors for Aircraft Structural Health Monitoring.

    PubMed

    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

  2. Optical and thermal studies of starch/methylcellulose blends

    NASA Astrophysics Data System (ADS)

    Ragab, H. S.; Abd El-Kader, M. F. H.

    2013-02-01

    Starch and methylcellulose (MC) homopolymers and their blends were prepared using a casting technique. The samples were investigated by infrared (Fourier transform infrared (IR)), ultraviolet/visible (UV/VIS), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Significant changes in IR spectra of blend samples were observed, which indicated the occurrence of an intermolecular interactions between starch and MC. UV/VIS analyses revealed that the values of the optical band gap decreased with increasing MC content in blend samples. The positions of the investigated samples on the chromaticity diagram and the color parameters, such as L*, U*, V*, C*, hue and Ye, reflected the presence of a high color gradient and were composition dependent. A single glass transition temperature for each poly-blend sample was observed, which supported the existence of compatibility in such a system. The kinetic thermodynamic parameters, such as activation energy, enthalpy, entropy and Gibbs free energy, were evaluated from thermogravimetric analysis data using the Coats-Redfern relation.

  3. 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.

  4. Thermal beam of metastable krypton atoms produced by optical excitation

    SciTech Connect

    Ding, Y.; Hu, S.-M.; Bailey, K.; Davis, A. M.; Dunford, R. W.; Lu, Z.-T.; O'Connor, T. P.; Young, L.

    2007-02-15

    A room-temperature beam of krypton atoms in the metastable 5s[3/2]{sub 2} level is demonstrated via an optical excitation method. A Kr-discharge lamp is used to produce vacuum ultraviolet photons at 124 nm for the first-step excitation from the ground level 4p{sup 6} {sup 1}S{sub 0} to the 5s[3/2]{sub 1} level. An 819 nm Ti:sapphire laser is used for the second-step excitation from 5s[3/2]{sub 1} to 5s[3/2]{sub 2} followed by a spontaneous decay to the 5s[3/2]{sub 2} metastable level. A metastable atomic beam with an angular flux density of 3x10{sup 14} s{sup -1} sr{sup -1} is achieved at the total gas flow rate of 0.01 cm{sup 3}/s at STP (or 3x10{sup 17} at./s). The dependences of the flux on the gas flow rate, laser power, and lamp parameters are investigated.

  5. 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

  6. 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.

  7. 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

  8. Active thermal lensing elements for mode matching optimization in optical systems

    NASA Astrophysics Data System (ADS)

    Fulda, Paul

    2014-03-01

    In interferometric gravitational wave detectors of the advanced era and beyond, the high laser powers used lead to the generation of thermal lenses in the optics. This can lead to a reduction in the coupling between the various optical cavities comprising the detector, thus reducing its overall sensitivity. We present here an active device which can be used to compensate for such thermal effects, as well as static mismatches between cavities. The device uses a 4 segmented heater to heat a transmissive optic, generating a spherical or astigmatic lens which can be used to compensate other thermal lenses within an optical system. We report on in-vacuum tests of the device, including an interferometric measurement of the wavefront distortions induced by the device, and measurements of the dynamic range and response time. The device was shown to have no observable detrimental effect on wavefront distortion, a focal power dynamic range of 0 to -40 mD, and a response time of the order 1000 s. Supported by NSF grant PHY-1205512.

  9. Multi-mirror adaptive optics for control of thermally induced aberrations in extreme ultraviolet lithography

    NASA Astrophysics Data System (ADS)

    Habets, Michel; Scholten, Joni; Weiland, Siep; Coene, Wim

    2016-03-01

    The imaging quality of the projection optics of an extreme ultraviolet lithography scanner degrades under the influence of thermally induced deformations of its mirrors. Wavefronts of different reticle points encounter different parts of the deformed mirrors, resulting in a field dependent wavefront error. This paper presents how ideas from multi-conjugate adaptive optics can be used to reduce these thermally induced aberrations. To this end a generic deformable mirror model is implemented. Linear actuator sensitivities are derived directly, based on nominal ray locations and directions, enabling fast prototyping. An integrated opto-thermo-mechanical mirror heating model is used to determine the evolution of thermally induced abberations over time. This transient simulation is used to analyze four different adaptive optics configurations and two different control algorithms. It is shown that by employing the multi-objective goal-attainment method, it is possible to improve the optical performance significantly when compared to minimizing the l2-norm of the total residual wavefront error vector.

  10. 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.

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

    PubMed

    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

  12. 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

  13. 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.

  14. 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. PMID:26931831

  15. 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.

  16. Modeling simulation of the thermal radiation for high-speed flight vehicles' aero-optical windows

    NASA Astrophysics Data System (ADS)

    Chen, Lei; Zhang, Liqin; Guo, Mingjiang

    2015-10-01

    When high-speed flight vehicles fly in the atmosphere, they can generate serious aero-optical effect. The optical window temperature rises sharply because of aerodynamic heating. It will form radiation interference that can lead infrared detectors to producing non-uniform radiation backgrounds, decreasing system SNR and detection range. Besides, there exits temperature difference due to uneven heating. Under the thermo-optical and elastic-optical effects, optical windows change into inhomogeneous mediums which influence the ray propagation. In this paper, a model of thermal radiation effect was built by a finite element analysis method. Firstly, the optical window was divided into uniform grids. Then, radiation distribution on the focal planes at different angles of the window's normal line and optical axis was obtained by tracing light rays of each grid. Finally, simulation results indicate that radiation distribution reflects the two directions-the length and width-of temperature distribution, and the change of angle causes the center of radiation distribution to shift to one direction of the image surface under the same window temperature.

  17. Fiber-content dependency of the optical transparency and thermal expansion of bacterial nanofiber reinforced composites

    NASA Astrophysics Data System (ADS)

    Nogi, Masaya; Ifuku, Shinsuke; Abe, Kentaro; Handa, Keishin; Nakagaito, Antonio Norio; Yano, Hiroyuki

    2006-03-01

    We produced transparent nanocomposite reinforced with bacterial cellulose having a wide range of fiber contents, from 7.4to66.1wt%, by the combination of heat drying and organic solvent exchange methods. The addition of only 7.4wt% of bacterial cellulose nanofibers, which deteriorated light transmittance by only 2.4%, was able to reduce the coefficient of thermal expansion of acrylic resin from 86×10-6to38×10-6K-1. As such, the nanofiber network of bacterial cellulose has an extraordinary potential as a reinforcement to obtain optically transparent and low thermal expansion materials.

  18. Measurements of the thermal expansion of six optical materials, from room temperature to 250 degrees C.

    PubMed

    Ballard, S S; Brown, S E; Browder, J S

    1978-04-01

    Coefficients of linear thermal expansion are reported in the range from room temperature to 250 degrees C for six optical materials: Polytran potassium chloride and Polytran calcium fluoride-Harshaw; chemical-vapordeposited (CVD) zinc selenide and zinc sulfide-Raytheon; single-crystal germanium-Eagle-Picher; and lithium niobate-Harshaw. For the last named, an anisotropic crystal, thermal expansion was measured both parallel and perpendicular to the c axis. Curves are given to illustrate the expansion behavior of the materials over the 60-500-K range. PMID:20197949

  19. A practical approach to LWIR wafer-level optics for thermal imaging systems

    NASA Astrophysics Data System (ADS)

    Symmons, Alan; Pini, Ray

    2013-06-01

    The development and implementation of wafer level packaging for commercial microbolometers has opened the pathway towards full wafer-based thermal imaging systems. The next challenge in development is moving from discrete element LWIR imaging systems to a wafer based optical system, similar to lens assemblies found in cell phone cameras. This paper will compare a typical high volume thermal imaging design manufactured from discrete lens elements to a similar design optimized for manufacture through a wafer based approach. We will explore both performance and cost tradeoffs as well as review the manufacturability of all designs.

  20. Optical fiber biocompatible sensors for monitoring selective treatment of tumors via thermal ablation

    NASA Astrophysics Data System (ADS)

    Tosi, Daniele; Poeggel, Sven; Dinesh, Duraibabu B.; Macchi, Edoardo G.; Gallati, Mario; Braschi, Giovanni; Leen, Gabriel; Lewis, Elfed

    2015-09-01

    Thermal ablation (TA) is an interventional procedure for selective treatment of tumors, that results in low-invasive outpatient care. The lack of real-time control of TA is one of its main weaknesses. Miniature and biocompatible optical fiber sensors are applied to achieve a dense, multi-parameter monitoring, that can substantially improve the control of TA. Ex vivo measurements are reported performed on porcine liver tissue, to reproduce radiofrequency ablation of hepatocellular carcinoma. Our measurement campaign has a two-fold focus: (1) dual pressure-temperature measurement with a single probe; (2) distributed thermal measurement to estimate point-by-point cells mortality.

  1. The optical control system of dispersed phase properties in thermal spray process

    NASA Astrophysics Data System (ADS)

    Dolmatov, A. V.; Gulyaev, I. P.; Jordan, V. I.

    2015-04-01

    The models of measuring the velocity and temperature of particles using the processing of their track images are introduced. The method of brightness pyrometry of moving objects uses the calibration procedure based on the static temperature standard. Performance of the statistical analysis of thermal data by means of optical control system of the particles properties in gas-thermal spraying flow equals to 2200-2700 particles per second. Investigation of stationary plasma spraying process allowed to obtain the distributions of velocity and temperature of particles over the volume of spraying jet. The error in determining the velocity of the particles was 1%, and the error in determining the temperature is 3%.

  2. Contribution of thermal noise to frequency stability of rigid optical cavity via Hertz-linewidth lasers

    SciTech Connect

    Notcutt, Mark; Ma, L.-S.; Ludlow, Andrew D.; Foreman, Seth M.; Ye Jun; Hall, John L.

    2006-03-15

    We perform detailed studies of state-of-the-art laser stabilization to high finesse optical cavities, revealing fundamental mechanical thermal noise-related length fluctuations. We compare the frequency noise of lasers tightly locked to the resonances of a variety of rigid Fabry-Perot cavities of differing lengths and mirror substrate materials. The results are in agreement with the theoretical model proposed in K. Numata, A. Kemery, and J. Camp [Phys. Rev. Lett. 93, 250602 (2004)]. The results presented here on the fundamental limits of FP references will impact planning and construction of next generation ultrastable optical cavities.

  3. New-generation concentrator modules based on cascade solar cells: Design and optical and thermal properties

    NASA Astrophysics Data System (ADS)

    Andreev, V. M.; Davidyuk, N. Yu.; Malevski, D. A.; Pan'chak, A. N.; Rumyantsev, V. D.; Sadchikov, N. A.; Chekalin, A. V.; Luque, A.

    2014-11-01

    New-generation concentrator modules use III-V nanoheterostructure cascade solar cells the efficiency of which can be raised to 50% for the number of cascades exceeding three. To obtain a high overall efficiency of photovoltaic conversion in power plants and extend their service time, it is necessary that the design of the modules be optimal in terms of optics and thermal engineering. In this work, main challenges in designing solar modules, such as optical concentration of radiation and residual heat removal, are considered. The results of pilot works that have been recently done in the Ioffe Physical Technical Institute are primarily reported.

  4. Space Science Payloads Optical Properties Monitor (OPM) Mission Flight Anomalies Thermal Analyses

    NASA Technical Reports Server (NTRS)

    Schmitz, Craig P.

    2001-01-01

    The OPM was the first space payload that measured in-situ the optical properties of materials and had data telemetered to ground. The OPM was EVA mounted to the Mir Docking Module for an eight-month stay where flight samples were exposed to the Mir induced and natural environments. The OPM was comprised of three optical instruments; a total hemispherical spectral reflectometer, a vacuum ultraviolet spectrometer, and a total integrated scatterometer. There were also three environmental monitors; an atomic oxygen monitor, solar and infrared radiometers, and two temperature-controlled quartz crystal microbalances (to monitor contamination). Measurements were performed weekly and data telemetered to ground through the Mir data system. This paper will describe the OPM thermal control design and how the thermal math models were used to analyze anomalies which occurred during the space flight mission.

  5. Optical characterization of thermal-stress induced by spin waves in thin-film ferrimagnetic structures

    NASA Astrophysics Data System (ADS)

    Kolokoltsev, O. V.; Ordóñez-Romero, C. L.; Qureshi, N.; Ortega-Martinez, R.; Grimalsky, V.

    2007-04-01

    It is shown that intense spin-dipole waves (SDWs) excited in thin yttrium iron garnet (YIG) films induce an in-plane thermal stress (σ) of 1-2 MPa in a YIG/GGG structure (where GGG is gadolinium gallium garnet). In YIG/GGG with normal magnetization, σ shifts its ferromagnetic resonance frequency by ≈1 MHz, which is comparable to the linewidth of the absorption curve of YIG/GGG resonators. The effect was characterized by an optical technique that detects σ in the GGG substrate. It was also demonstrated that this effect can be used for the optical-microwave spectroscopy of spin waves in thin ferromagnetic films, by using thermal mapping of SDWs in the substrate. We have shown that this opens up the possibility of determining the contribution of the two-particle magneto-elastic interaction to the microwave heating of the sample.

  6. Assessment of chronic wounds by three-dimensional optical imaging based on integrating geometrical, chromatic, and thermal data.

    PubMed

    Barone, S; Paoli, A; Razionale, A V

    2011-02-01

    Chronic wounds represent a particular debilitating health care problem, mainly affecting elderly people. A full and correct diagnosis of tissue damage should be carried out considering both dimensional, chromatic, and thermal parameters. A great variety of methods have been proposed with the aim of producing objective assessment of skin lesions, but none of the existing technologies seem to be robust enough to work for all ulcer typologies. This paper describes an innovative and non-invasive system that allows the automatic measurement of non-healing chronic wounds. The methodology involves the integration of a three-dimensional (3D) optical scanner, based on a structured light approach, with a thermal imager. The system enables the acquisition of geometrical data, which are directly related to chromatic and temperature patterns through a mapping procedure. Damaged skin areas are detected by combining visible and thermal imaging. This approach allows for the automatic measurement of extension and depth of ulcers, even in the absence of significant and well-defined chromatic patterns. The proposed technology has been tested in the measurement of ulcers on human legs. Clinical tests have demonstrated the effectiveness of this methodology in supporting medical experts for the assessment of chronic wounds. PMID:21428152

  7. Investigations on the electrical, thermal and optical properties of the nonlinear optical allylthiourea mercury chloride single crystals

    SciTech Connect

    Sreekanth, G.; Chandralingam, S.; Philip, Jacob; Jayalakshmy, M.S.; Philip, Reji; Sridharan, Kishore; Santhosh Kumar, R.; Joseph, Ginson P.

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► The single crystals of dimension 10 × 5 × 5 mm{sup 3} of allylthiourea mercury chloride are synthesized using slow evaporation technique. ► The bandgap of allylthiourea mercury chloride crystal is found to be about 3.18 eV. ► The optical nonlinearity of the crystal sample are studied using the open aperture Z-scan technique employing a nanosecond laser at 532 nm, and three photon absorption effect has been found. ► An improved photo pyroelectric is used to find the thermal parameters of the crystal. ► The piezoelectric charge coefficient is determined. -- Abstract: Single crystals of dimension 10 × 5 × 5 mm{sup 3} of allylthiourea mercury chloride were synthesized from aqueous solution using slow evaporation technique at ambient temperature. The grown crystals are confirmed by elemental analysis. The band gap of Allylthiourea mercury chloride crystal was found to be about 3.18 eV. The optical nonlinearity of the crystal sample was studied using the open aperture Z-scan technique employing a nanosecond laser at 532 nm, and a three-photon absorption effect has been found. The electrical properties such as dielectric constant, dielectric loss and ac conductivity of the sample were carried out by Agillent E 4980 A LCR meter at different temperatures. An improved photopyroelectric technique was used to find the thermal parameters of the crystal. The piezo electric charge coefficient is also determined.

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

    SciTech Connect

    Chang-Hwan Kim

    2003-12-12

    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.

  9. Optical absorption characteristics in thermally reduced Er:LiNbO 3 crystals

    NASA Astrophysics Data System (ADS)

    Zhang, De-Long; Ma, Rui; Pun, E. Y. B.

    2006-03-01

    Influence of thermal reduction on intrinsic (bipolarons), extrinsic (Er3+) defects and OH- groups in Er:LiNbO3 crystals, which were as-grown and VTE-treated (VTE: vapor transport equilibration) before being reduced, was studied by measuring the polarised or unpolarised optical absorption in visible and near infrared regions. A wide and strong band extending from the optical absorption edge up to the infrared region and peaking around 500 nm (∼2.5 eV), resulting from the absorption of reduction-induced bipolarons, is observed. Meanwhile, the thermal reduction also induces an additional, relatively much narrow absorption band around 370 nm in a crystal whether it is Er-doped or undoped and whether it is congruent or originally VTE-treated. Both the 500 nm and the 370 nm bands show similar polarisation dependence. The thermal reduction treatment hardly influences Er3+ spectroscopic properties such as absorption amplitude, linewidth, peaking position and polarisation dependence. The original VTE effects on the spectroscopic properties of Er:LiNbO3 crystal are essentially retained still. The thermal reduction has a similar effect on the OH- absorption to a strong VTE treatment: the removal of the OH- groups contained in the crystal.

  10. Thermal and optical characterization of photonic integrated circuits by thermoreflectance microscopy

    NASA Astrophysics Data System (ADS)

    Farzaneh, Maryam; Summers, J. A.; Greenberg, K.; Lueerssen, D.; Ram, Rajeev; Hudgings, Janice

    2010-04-01

    One of the biggest challenges in operation of sub-micrometer sized optoelectronic devices is the generation of excess heat that can create hot spots and affect the device performance. In addition, size reduction and monolithic integration of a large number of optoelectronic devices on a photonic integrated circuit (PIC) restrict direct access to optical signals of each component, which renders the characterization of individual elements difficult. In this talk we report on application of the high resolution, all optical thermal imaging technique of thermoreflectance microscopy in characterization of a PIC comprised of cascaded semiconductor optical amplifiers. A combination of thermal imaging with a comprehensive heat exchange model allows us to obtain internal optical power distribution of the individual devices on a PIC under operating conditions. Other applications of the thermoreflectance technique will also be reviewed. http://meetings.aps.org/link/BAPS.2010.OSS.B1.3

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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 (...

  16. Damage detection in bridges through fiber optic structural health monitoring

    NASA Astrophysics Data System (ADS)

    Doornink, J. D.; Phares, B. M.; Wipf, T. J.; Wood, D. L.

    2006-10-01

    A fiber optic structural health monitoring (SHM) system was developed and deployed by the Iowa State University (ISU) Bridge Engineering Center (BEC) to detect gradual or sudden damage in fracture-critical bridges (FCBs). The SHM system is trained with measured performance data, which are collected by fiber optic strain sensors to identify typical bridge behavior when subjected to ambient traffic loads. Structural responses deviating from the trained behavior are considered to be signs of structural damage or degradation and are identified through analytical procedures similar to control chart analyses used in statistical process control (SPC). The demonstration FCB SHM system was installed on the US Highway 30 bridge near Ames, IA, and utilizes 40 fiber bragg grating (FBG) sensors to continuously monitor the bridge response when subjected to ambient traffic loads. After the data is collected and processed, weekly evaluation reports are developed that summarize the continuous monitoring results. Through use of the evaluation reports, the bridge owner is able to identify and estimate the location and severity of the damage. The information presented herein includes an overview of the SHM components, results from laboratory and field validation testing on the system components, and samples of the reduced and analyzed data.

  17. Measuring thermal diffusivity of mechanical and optical grades of polycrystalline diamond using an AC laser calorimetry method

    SciTech Connect

    Rule, Toby D.; Cai, Wei; Wang, Hsin

    2013-01-01

    Because of its extremely high thermal conductivity, measuring the thermal conductivity or diffusivity of optical-grade diamond can be challenging. Various methods have been used to measure the thermal conductivity of thick diamond films. For the purposes of commercial quality control, the AC laser calorimetry method is appealing because it enables fairly rapid and convenient sample preparation and measurement. In this paper, the method is used to measure the thermal diffusivity of optical diamond. It is found that sample dimensions and measurement parameters are critical, and data analysis must be performed with great care. The results suggest that the method as it is applied to optical-grade diamond could be enhanced by a more powerful laser, higher frequency beam modulation, and post-processing based on 2D thermal simulation.

  18. Analytical predictions for lightweight optics in a gravitational and thermal environment

    NASA Astrophysics Data System (ADS)

    Pepi, John W.

    1987-01-01

    The design of high-performance quality lightweight mirrors necessitated by payload requirements must be shown to be capable of resisting environmental-load-induced distortion. Such loading can include thermal gradients in the presence of flux loading, or extreme thermal soak in the cryogenic environments demanded by IR systems. Additionally, for aircraft systems, the optics may be subject to a changing gravitational vector, causing performance error. For orbital systems, gravitational error is a major concern as well, as it is necessary to perform meaningful ground tests prior to the zero-g release condition. These mirrors must exhibit excellent stiffness and thermal expansion characteristics, particularly in a passive system, and often in an active system as the mirror size increases but the aerial density requirement does not. To meet the stringent requirements, analyses for mirrors of various sizes, both solid and lightweight, are presented to show the effects of material properties and inhomogeneities on performance characteristics in the presence of a thermal and gravitational environment. Included is the effect of kinematic mount location and coefficient of thermal expansion uncertainties. Passive and active focus performance is compared, and design points are indicated for actively controlled deformable mirror requirements.

  19. Health Risk Assessment of Inhalable Particulate Matter in Beijing Based on the Thermal Environment

    PubMed Central

    Xu, Lin-Yu; Yin, Hao; Xie, Xiao-Dong

    2014-01-01

    Inhalable particulate matter (PM10) is a primary air pollutant closely related to public health, and an especially serious problem in urban areas. The urban heat island (UHI) effect has made the urban PM10 pollution situation more complex and severe. In this study, we established a health risk assessment system utilizing an epidemiological method taking the thermal environment effects into consideration. We utilized a remote sensing method to retrieve the PM10 concentration, UHI, Normalized Difference Vegetation Index (NDVI), and Normalized Difference Water Index (NDWI). With the correlation between difference vegetation index (DVI) and PM10 concentration, we utilized the established model between PM10 and thermal environmental indicators to evaluate the PM10 health risks based on the epidemiological study. Additionally, with the regulation of UHI, NDVI and NDWI, we aimed at regulating the PM10 health risks and thermal environment simultaneously. This study attempted to accomplish concurrent thermal environment regulation and elimination of PM10 health risks through control of UHI intensity. The results indicate that urban Beijing has a higher PM10 health risk than rural areas; PM10 health risk based on the thermal environment is 1.145, which is similar to the health risk calculated (1.144) from the PM10 concentration inversion; according to the regulation results, regulation of UHI and NDVI is effective and helpful for mitigation of PM10 health risk in functional zones. PMID:25464132

  20. Health risk assessment of inhalable particulate matter in Beijing based on the thermal environment.

    PubMed

    Xu, Lin-Yu; Yin, Hao; Xie, Xiao-Dong

    2014-12-01

    Inhalable particulate matter (PM10) is a primary air pollutant closely related to public health, and an especially serious problem in urban areas. The urban heat island (UHI) effect has made the urban PM10 pollution situation more complex and severe. In this study, we established a health risk assessment system utilizing an epidemiological method taking the thermal environment effects into consideration. We utilized a remote sensing method to retrieve the PM10 concentration, UHI, Normalized Difference Vegetation Index (NDVI), and Normalized Difference Water Index (NDWI). With the correlation between difference vegetation index (DVI) and PM10 concentration, we utilized the established model between PM10 and thermal environmental indicators to evaluate the PM10 health risks based on the epidemiological study. Additionally, with the regulation of UHI, NDVI and NDWI, we aimed at regulating the PM10 health risks and thermal environment simultaneously. This study attempted to accomplish concurrent thermal environment regulation and elimination of PM10 health risks through control of UHI intensity. The results indicate that urban Beijing has a higher PM10 health risk than rural areas; PM10 health risk based on the thermal environment is 1.145, which is similar to the health risk calculated (1.144) from the PM10 concentration inversion; according to the regulation results, regulation of UHI and NDVI is effective and helpful for mitigation of PM10 health risk in functional zones.

  1. Thermally induced distortion of a high-average-power laser system by an optical transport system

    NASA Astrophysics Data System (ADS)

    Chow, Robert; Ault, Linda E.; Taylor, John R.; Jedlovec, Don

    1999-11-01

    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 will be reported on optics made from fused silica and Zerodur substrate materials.

  2. Synthesized some 4-(2-thiazolylazo)resorcinol complexes: Characterization, thermal and optical properties

    NASA Astrophysics Data System (ADS)

    Karipcin, Fatma; Kabalcilar, Eser; Ilican, Saliha; Caglar, Yasemin; Caglar, Mujdat

    2009-07-01

    Some transition metal complexes of the type [ML 2]· nH 2O ( n = 0 or 2) of the title ligand, 4-(2-thiazolylazo)resorcinol, HL (TAR) have been synthesized and characterized by various analytical and physicochemical (elemental, thermal analyses, AAS, electrolytic conductance and magnetic susceptibility measurements) and spectral (UV-vis and IR) techniques for structure determination and optical properties. The complexes have the formulae [ML 2] for M = Fe(II), Cu(II) and Zn(II); [CdL 2]·2H 2O. An octahedral structure is proposed for all complexes. IR spectra show that the ligand is coordinated to the metal ions in a tridentate manner with ONN donor sites of the resorcinol OH, azo N and thiazole N. The effect of varying pH and solvent on the absorption behavior of the ligand and complexes has been investigated. The optical constants such as, refractive index, extinction coefficient, dielectric constant were determined for the ligand and its complexes. These parameters changed with different metal complexes. The optical absorption data revealed that the band gap of the films was direct transitions. The optical band gap and Urbach energy of the films were determined using the known theory. The optical dispersion parameters were determined according to Wemple and DiDomenico method.

  3. 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...

  4. 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...

  5. Synthesis, structural, optical, thermal and dielectric studies on new organic nonlinear optical crystal by solution growth technique

    NASA Astrophysics Data System (ADS)

    Prakash, M.; Geetha, D.; Lydia Caroline, M.

    2013-04-01

    Single crystals of L-phenylalanine-benzoic acid (LPBA) were successfully grown from aqueous solution by solvent evaporation technique. Purity of the crystals was increased by the method of recrystallization. The XRD analysis confirms that the crystal belongs to the monoclinic system with noncentrosymmetric space group P21. The chemical structure of compound was established by FT-NMR technique. The presence of functional groups was estimated qualitatively by Fourier transform infrared analysis (FT-IR). Ultraviolet-visible spectral analyses showed that the crystal has low UV cut-off at 254 nm combined with very good transparency of 90% in a wide range. The optical band gap was estimated to be 6.91 eV. Thermal behavior has been studied with TGA/DTA analyses. The existence of second harmonic generation (SHG) efficiency was found to be 0.56 times the value of KDP. The dielectric behavior of the sample was also studied for the first time.

  6. Synthesis, structural, optical, thermal and dielectric studies on new organic nonlinear optical crystal by solution growth technique.

    PubMed

    Prakash, M; Geetha, D; Lydia Caroline, M

    2013-04-15

    Single crystals of L-phenylalanine-benzoic acid (LPBA) were successfully grown from aqueous solution by solvent evaporation technique. Purity of the crystals was increased by the method of recrystallization. The XRD analysis confirms that the crystal belongs to the monoclinic system with noncentrosymmetric space group P21. The chemical structure of compound was established by FT-NMR technique. The presence of functional groups was estimated qualitatively by Fourier transform infrared analysis (FT-IR). Ultraviolet-visible spectral analyses showed that the crystal has low UV cut-off at 254 nm combined with very good transparency of 90% in a wide range. The optical band gap was estimated to be 6.91 eV. Thermal behavior has been studied with TGA/DTA analyses. The existence of second harmonic generation (SHG) efficiency was found to be 0.56 times the value of KDP. The dielectric behavior of the sample was also studied for the first time.

  7. 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.

  8. Time-Resolved Magneto-Optical Kerr Effect of Magnetic Thin Films for Ultrafast Thermal Characterization.

    PubMed

    Chen, Jun-Yang; Zhu, Jie; Zhang, Delin; Lattery, Dustin M; Li, Mo; Wang, Jian-Ping; Wang, Xiaojia

    2016-07-01

    Thermomagnetic and magneto-optical effects are two fundamental but unique phenomena existing in magnetic materials. In this work, we demonstrate ultrafast time-resolved magneto-optical Kerr effect (TR-MOKE) as an advanced thermal characterization technique by studying the original factors of the MOKE signal from four magnetic transducers, including TbFe, GdFeCo, Co/Pd, and CoFe/Pt. A figure of merit is proposed to evaluate the performance of the transducer layers, corresponding to the degree of the signal-to-noise ratio in TR-MOKE measurements. We observe improved figure of merit for rare-earth transition-metal-based TbFe and GdFeCo transducers and attribute this improvement to their relatively larger temperature-dependent magnetization and the Kerr rotation angle at the saturated magnetization state. Furthermore, an optimal thickness of TbFe is found to be ∼18.5 nm to give the best performance. Our findings will facilitate the nanoscale thermal characterization and the device design where the thermo-magneto-optical coupling plays an important role. PMID:27269127

  9. Nanocomposites for high-speed optical modulators and plasmonic thermal mid-infrared emitters

    NASA Astrophysics Data System (ADS)

    Demir, Veysi

    Demand for high-speed optical modulators and narrow-bandwidth infrared thermal emitters for numerous applications continues to rise and new optical devices are needed to deal with massive data flows, processing powers, and fabrication costs. Conventional techniques are usually hindered by material limitations or electronic interconnects and advances in organic nanocomposite materials and their integration into photonic integrated circuits (PICs) have been acknowledged as a promising alternative to single crystal techniques. The work presented in this thesis uses plasmonic and magneto-optic effects towards the development of novel optical devices for harnessing light and generating high bandwidth signals (>40GHz) at room and cryogenic temperatures (4.2°K). Several publications have resulted from these efforts and are listed at the end of the abstract. In our first published research we developed a narrow-bandwidth mid-infrared thermal emitter using an Ag/dielectric/Ag thin film structure arranged in hexagonal planar lattice structures. PECVD produced nanoamorphous carbon (NAC) is used as a dielectric layer. Spectrally tunable (>2 mum) and narrow bandwidth (<0.5 mum) emission peaks in the range of 4-7 mum were demonstrated by decreasing the resistivity of NAC from 1012 and 109 O.cm with an MoSi2 dopant and increasing the emitter lattice constant from 4 to 7 mum. This technique offers excellent flexibility for developing cost-effective mid-IR sources as compared to costly fiber and quantum cascade lasers (QCLs). Next, the effect of temperature on the Verdet constant for cobalt-ferrite polymer nanocomposites was measured for a series of temperatures ranging from 40 to 200°K with a Faraday rotation polarimeter. No visual change was observed in the films during thermal cycling, and ˜4x improvement was achieved at 40°K. The results are promising and further analysis is merited at 4.2°K to assess the performance of this material for cryogenic magneto-optic modulators

  10. 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.

  11. 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.

  12. Global forecasting of thermal health hazards: the skill of probabilistic predictions of the Universal Thermal Climate Index (UTCI).

    PubMed

    Pappenberger, F; Jendritzky, G; Staiger, H; Dutra, E; Di Giuseppe, F; Richardson, D S; Cloke, H L

    2015-03-01

    Although over a hundred thermal indices can be used for assessing thermal health hazards, many ignore the human heat budget, physiology and clothing. The Universal Thermal Climate Index (UTCI) addresses these shortcomings by using an advanced thermo-physiological model. This paper assesses the potential of using the UTCI for forecasting thermal health hazards. Traditionally, such hazard forecasting has had two further limitations: it has been narrowly focused on a particular region or nation and has relied on the use of single 'deterministic' forecasts. Here, the UTCI is computed on a global scale, which is essential for international health-hazard warnings and disaster preparedness, and it is provided as a probabilistic forecast. It is shown that probabilistic UTCI forecasts are superior in skill to deterministic forecasts and that despite global variations, the UTCI forecast is skilful for lead times up to 10 days. The paper also demonstrates the utility of probabilistic UTCI forecasts on the example of the 2010 heat wave in Russia.

  13. Global forecasting of thermal health hazards: the skill of probabilistic predictions of the Universal Thermal Climate Index (UTCI)

    NASA Astrophysics Data System (ADS)

    Pappenberger, F.; Jendritzky, G.; Staiger, H.; Dutra, E.; Di Giuseppe, F.; Richardson, D. S.; Cloke, H. L.

    2015-03-01

    Although over a hundred thermal indices can be used for assessing thermal health hazards, many ignore the human heat budget, physiology and clothing. The Universal Thermal Climate Index (UTCI) addresses these shortcomings by using an advanced thermo-physiological model. This paper assesses the potential of using the UTCI for forecasting thermal health hazards. Traditionally, such hazard forecasting has had two further limitations: it has been narrowly focused on a particular region or nation and has relied on the use of single `deterministic' forecasts. Here, the UTCI is computed on a global scale, which is essential for international health-hazard warnings and disaster preparedness, and it is provided as a probabilistic forecast. It is shown that probabilistic UTCI forecasts are superior in skill to deterministic forecasts and that despite global variations, the UTCI forecast is skilful for lead times up to 10 days. The paper also demonstrates the utility of probabilistic UTCI forecasts on the example of the 2010 heat wave in Russia.

  14. 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.

  15. Optical Solar Reflector - A stable, low alpha(s)/epsilon(IR), electrically conducting thermal control surface

    NASA Astrophysics Data System (ADS)

    Palanisamy, R.; Bhojaraj, H.; Nagendra, C. L.; Thutupalli, G. K. M.

    1991-08-01

    Experimental studies related to the development of a stable, low alpha(s)/epsilon(IR) thermal control surface have been carried out for space applications. Systematic studies have been performed to overcome inherent problem of poor adhesion and environmental degradation of silver. The influence of the deposition parameters and post annealing temperatures on the electrical and optical properties of Indium Tin Oxide (ITO) film (used as transparent conductive coating) has been investigated. The test results indicate excellent stability of the coatings with adhesion and abrasion tests in accordance with military standards and also against prolonged exposure to humidity, thermal cycling, and thermo vacuum hot and cold soak tests. In addition, a summary of laboratory simulated exposure to ultraviolet, electron and proton irradiation are presented.

  16. 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.

  17. 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. PMID:25089381

  18. Optical, thermal and surface microtopography studies of MoTe2 single crystals

    NASA Astrophysics Data System (ADS)

    Patel, D. D.; Desai, P. F.; Bhavsar, D. N.; Jani, A. R.

    2013-06-01

    Single crystals of MoTe2 grown by chemical vapour transport technique were used here. X-ray diffraction technique reveals that the MoTe2 crystals belong to hexagonal crystal structure. The optical response of these crystals has been obtained by UV-VIS-NIR spectroscopy. The transmittance of MoTe2 crystal has been used to calculate the refractive index (n), the extinction co-efficient (k) and both real(ɛr) and imaginary (ɛi) components of the dielectric constant as function of wavelength at room temperature. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were carried out for MoTe2 single crystals. The detailed surface microtopographic studies of these crystals by means of optical microscopy showed that the layer mechanism is predominant during growth. Even spiral growth is equally common on the as-grown faces.

  19. Characterization of thermal inkjet technology TNT deposits by fiber optic-grazing angle probe FTIR spectroscopy

    NASA Astrophysics Data System (ADS)

    Primera-Pedrozo, Oliva M.; Pacheco-Londono, Leonardo; Ruiz, Orlando; Ramirez, Michael; Soto-Feliciano, Yadira M.; De La Torre-Quintana, Luis F.; Hernandez-Rivera, Samuel P.

    2005-05-01

    Fiber Optic Coupled/Grazing Angle Probe Fourier Transform Infrared Spectroscopy has made possible to develop new methods for detection of traces of chemical compounds on surfaces. Thermal Inkjet Technology is able to deposit very small amounts of chemical compounds, including energetic materials, in a specific location on a surface. Aliquots of TNT solutions were deposited on stainless steel film. A thin coating of TNT can be produced by controlling the concentration of TNT, the number of drops dispensed and the distribution of drops over the surface. A Vector 22, a Bruker Optics FTIR fiber coupled to a Remspec Corp. grazing angle head was used for the experiments. The spectra were recorded at 4 cm-1 resolution and 50 scans. The results of the experiments gave intense absorption bands in the fingerprint region of the infrared spectra that were used for quantification. Chemometrics routines were applied in the enhancement of the quantitative analysis.

  20. Orbital atomic oxygen effects on thermal control and optical materials - STS-8 results

    NASA Technical Reports Server (NTRS)

    Whitaker, A. F.; Little, S. A.; Harwell, R. J.; Griner, D. B.; Dehaye, R. F.; Fromhold, A. T., Jr.

    1985-01-01

    The effects of exposing 23 specimens of optical and thermal control materials to space at 120 km altitude for over 40 hrs during the STS-8 mission are discussed. Ten samples of paint targeted for the Space Telescope (ST) and the Tethered Satellite were exposed, and included polyurethane, oxide, silicone, and glossy black and white samples which were scanned for alterations in the optical properties after being retrieved. Nine mirror-type materials were also investigated, along with silver specimens typical of solar cell interconnects. The oxygen flow at the orbital altitude was 3.5 x 10 to the 20th atoms/cu cm. The exposures caused no degradation of the magnesium fluoride mirror coatings, while the Kapton coating for the ST solar cell panels showed evidence of losing thickness. The Ag solar cell contacts will require coatings to extend their lifetimes. Overcoatings were also proven necessary for inhibiting degradation of painted surfaces.

  1. The optical length effect, diffraction pattern and thermal lensing of Disperse Orange 25

    NASA Astrophysics Data System (ADS)

    Salmani, S.; Ara, M. H. Majles

    2016-08-01

    The nonlinear responses of an azo dye, Disperse Orange 25 (DO25), are investigated under two irradiation of continuous Lasers at 532 and 632 nm wavelengths and the third order refractive index is measured by use of Z-scan technique. At 632 nm wavelength (far from the absorption peak), the close z-scan plots show that this material has a very good nonlinear response with negative sign indicating self-defocusing. The effect of optical length and concentration of samples in nonlinear responses have been investigated experimentally. Also, the radius variation at far field observed due to thermal lens effect. Finally, at other wavelength, 532 nm (near from the absorption peak), the nonlinear optical responses increase sharply so the diffraction rings appear and the numbers of rings increase with the incident laser power.

  2. Structural and thermal response of 30 cm diameter ion thruster optics

    NASA Technical Reports Server (NTRS)

    Macrae, G. S.; Zavesky, R. J.; Gooder, S. T.

    1989-01-01

    Tabular and graphical data are presented which are intended for use in calibrating and validating structural and thermal models of ion thruster optics. A 30 cm diameter, two electrode, mercury ion thruster was operated using two different electrode assembly designs. With no beam extraction, the transient and steady state temperature profiles and center electrode gaps were measured for three discharge powers. The data showed that the electrode mount design had little effect on the temperatures, but significantly impacted the motion of the electrode center. Equilibrium electrode gaps increased with one design and decreased with the other. Equilibrium displacements in excess of 0.5 mm and gap changes of 0.08 mm were measured at 450 W discharge power. Variations in equilibrium gaps were also found among assemblies of the same design. The presented data illustrate the necessity for high fidelity ion optics models and development of experimental techniques to allow their validation.

  3. 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.

  4. 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.

  5. 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. PMID:26782243

  6. 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.

  7. 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.

  8. 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.

  9. Direct laser writing of polymeric nanostructures via optically induced local thermal effect

    NASA Astrophysics Data System (ADS)

    Tong, Quang Cong; Nguyen, Dam Thuy Trang; Do, Minh Thanh; Luong, Mai Hoang; Journet, Bernard; Ledoux-Rak, Isabelle; Lai, Ngoc Diep

    2016-05-01

    We demonstrate the fabrication of desired structures with feature size below the diffraction limit by use of a positive photoresist. The direct laser writing technique employing a continuous-wave laser was used to optically induce a local thermal effect in a positive photoresist, which then allowed the formation of solid nanostructures. This technique enabled us to realize multi-dimensional sub-microstructures by use of a positive photoresist, with a feature size down to 57 nm. This mechanism acting on positive photoresists opens a simple and low-cost way for nanofabrication.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Nanoreactors for simultaneous remote thermal activation and optical monitoring of chemical reactions.

    PubMed

    Vázquez-Vázquez, Carmen; Vaz, Belén; Giannini, Vincenzo; Pérez-Lorenzo, Moisés; Alvarez-Puebla, Ramon A; Correa-Duarte, Miguel A

    2013-09-18

    We report herein the design of plasmonic hollow nanoreactors capable of concentrating light at the nanometer scale for the simultaneous performance and optical monitoring of thermally activated reactions. These reactors feature the encapsulation of plasmonic nanoparticles on the inner walls of a mesoporous silica capsule. A Diels-Alder cycloaddition reaction was carried out in the inner cavities of these nanoreactors to evidence their efficacy. Thus, it is demonstrated that reactions can be accomplished in a confined volume without alteration of the temperature of the bulk solvent while allowing real-time monitoring of the reaction progress.

  15. Sun-tracking optical element realized using thermally activated transparency-switching material.

    PubMed

    Apostoleris, Harry; Stefancich, Marco; Lilliu, Samuele; Chiesa, Matteo

    2015-07-27

    We present a proof of concept demonstration of a novel optical element: a light-responsive aperture that can track a moving light beam. The element is created using a thermally-activated transparency-switching material composed of paraffin wax and polydimethylsiloxane (PDMS). Illumination of the material with a focused beam causes the formation of a localized transparency at the focal spot location, due to local heating caused by absorption of a portion of the incident light. An application is proposed in a new design for a self-tracking solar collector. PMID:26367692

  16. Creating second-order nonlinearity in pure synthetic silica optical fibers by thermal poling.

    PubMed

    An, Honglin; Fleming, Simon

    2007-04-01

    A twin-hole optical fiber with pure synthetic silicate glass between the two electrode holes was thermally poled. The induced second-order nonlinearity (SON) was located at the core-cladding interface sections that were nearly parallel to the poling electric field. The polarization dependence of the induced SON suggests that nonlinearity was due to the presence of a space-charge field, which was probably formed by electron migration among the defects located at the core-cladding interface. The magnitude of the induced SON was measured to be approximately 0.06 pm /V.

  17. Structural, vibrational, thermal and optical studies of organic single crystal: Benzotriazolium p-toluene sulfonate (BTPTS)

    NASA Astrophysics Data System (ADS)

    Kumar, R. Ramesh; Sathya, P.; Gopalakrishnan, R.

    2016-05-01

    Benzotriazolium p-toluene sulfonate (BTPTS) was grown by solution growth technique. The powder X-ray diffraction analysis was carried out to evaluate crystal system of the compound. LeBail Profile fitting analysis was performed to extract the individual peak intensities. FTIR spectrum analysis was recorded to study vibration frequencies of the prepared organic salt. Thermal studies were carried out using TG-DSC analysis. Optical absorption and energy band gap of the title compound was evaluated by UV-Vis spectral study.

  18. 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).

  19. 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.

  20. Development and Validation of High Precision Thermal, Mechanical, and Optical Models for the Space Interferometry Mission

    NASA Technical Reports Server (NTRS)

    Lindensmith, Chris A.; Briggs, H. Clark; Beregovski, Yuri; Feria, V. Alfonso; Goullioud, Renaud; Gursel, Yekta; Hahn, Inseob; Kinsella, Gary; Orzewalla, Matthew; Phillips, Charles

    2006-01-01

    SIM Planetquest (SIM) is a large optical interferometer for making microarcsecond measurements of the positions of stars, and to detect Earth-sized planets around nearby stars. To achieve this precision, SIM requires stability of optical components to tens of picometers per hour. The combination of SIM s large size (9 meter baseline) and the high stability requirement makes it difficult and costly to measure all aspects of system performance on the ground. To reduce risks, costs and to allow for a design with fewer intermediate testing stages, the SIM project is developing an integrated thermal, mechanical and optical modeling process that will allow predictions of the system performance to be made at the required high precision. This modeling process uses commercial, off-the-shelf tools and has been validated against experimental results at the precision of the SIM performance requirements. This paper presents the description of the model development, some of the models, and their validation in the Thermo-Opto-Mechanical (TOM3) testbed which includes full scale brassboard optical components and the metrology to test them at the SIM performance requirement levels.

  1. Thermoreflectance of metal transducers for optical pump-probe studies of thermal properties.

    PubMed

    Wilson, R B; Apgar, Brent A; Martin, Lane W; Cahill, David G

    2012-12-17

    We report measurements of the temperature dependence of the optical reflectivity, dR/dT of fifteen metallic elements at a wavelength of λ = 1.03 μm by time-domain thermoreflectance (TDTR); and the thermoreflectance of thin-films of Pt, Ta, Al, Au, SrRuO(3), and LaNiO(3) over the wavelength range 0.4 < λ < 1.6 μm using variable angle spectroscopic ellipsometry. At λ = 1.03 μm, Al, Ta, Re, Ru, have high values of thermoreflectance, dR/dT > 6∙10(-5) K(-1), and are good choices as optical transducers for TDTR experiments using a Yb:fiber laser oscillator. If low optical reflectivity and the associated high degree of steady-state heating are not a concern, LaNiO(3) provides an exceptionally sensitive thermometer in the infrared; (1/R)(dR/dT) > 2.5∙10(-4) K(-1) in the wavelength range 0.85 < λ < 1.3 μm. This compilation of data will assist in the design and interpretation of optical pump-probe studies of thermal properties.

  2. Thermally controlled optical shutter in an inter-molecular hydrogen bonded liquid crystal

    NASA Astrophysics Data System (ADS)

    Vijayakumar, V. N.; Madhu Mohan, M. L. N.

    2011-11-01

    Novel homologs series of supra-molecular liquid crystals have been isolated. Hydrogen bond is formed between mandelic acid (MD) and various homologs of p- n-alkyloxy benzoic acids (nOBA) and has been confirmed by FTIR studies. Optical polarizing microscopic observations show that all these materials exhibit rich liquid crystallinity with various mesophases. Phase transition temperatures and enthalpy values are experimentally evaluated by DSC studies and the phase diagram of homologous series has been constructed. An interesting feature is the observation of thermally controlled reversible optical shuttering action in one of the homolog, wherein with the increment of temperature the homeotropic texture changes to homogenous texture of smectic F. Thus, this optical shuttering phenomenon is reversible. Optical tilt angle data of two homologs have been fitted to power law equation and it is found that the mean field theory prediction is valid. The light intensity profile in homeotropic region of smectic F in one complex has been experimentally analyzed and a steep sudden decrement of the intensity of light manifesting the distortion of the molecular alignment is experimentally found.

  3. 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.

  4. 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

  5. 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

  6. Nanoscale Probing of Thermal, Stress, and Optical Fields under Near-Field Laser Heating

    PubMed Central

    Tang, Xiaoduan; Xu, Shen; Wang, Xinwei

    2013-01-01

    Micro/nanoparticle induced near-field laser ultra-focusing and heating has been widely used in laser-assisted nanopatterning and nanolithography to pattern nanoscale features on a large-area substrate. Knowledge of the temperature and stress in the nanoscale near-field heating region is critical for process control and optimization. At present, probing of the nanoscale temperature, stress, and optical fields remains a great challenge since the heating area is very small (∼100 nm or less) and not immediately accessible for sensing. In this work, we report the first experimental study on nanoscale mapping of particle-induced thermal, stress, and optical fields by using a single laser for both near-field excitation and Raman probing. The mapping results based on Raman intensity variation, wavenumber shift, and linewidth broadening all give consistent conjugated thermal, stress, and near-field focusing effects at a 20 nm resolution (<λ/26, λ = 32 nm). Nanoscale mapping of near-field effects of particles from 1210 down to 160 nm demonstrates the strong capacity of such a technique. By developing a new strategy for physical analysis, we have de-conjugated the effects of temperature, stress, and near-field focusing from the Raman mapping. The temperature rise and stress in the nanoscale heating region is evaluated at different energy levels. High-fidelity electromagnetic and temperature field simulation is conducted to accurately interpret the experimental results. PMID:23555566

  7. Formation of thermally reversible optically transparent emulsion-based delivery systems using spontaneous emulsification.

    PubMed

    Saberi, Amir Hossein; Fang, Yuan; McClements, David Julian

    2015-12-28

    Transparent emulsion-based delivery systems suitable for encapsulating lipophilic bioactive agents can be fabricated using low-energy spontaneous emulsification methods. These emulsions are typically fabricated from non-ionic surfactants whose hydrophilic head groups are susceptible to dehydration upon heating. This phenomenon may promote emulsion instability due to enhanced droplet coalescence at elevated temperatures. Conversely, the same phenomenon can be used to fabricate optically transparent emulsions through the phase inversion temperature (PIT) method. The purpose of the current study was to examine the influence of oil phase composition and surfactant-to-oil ratio on the thermal behavior of surfactant-oil-water systems containing limonene, medium chain triglycerides (MCT), and Tween 60. Various types of thermal behavior (turbidity versus temperature profiles) were exhibited by these systems depending on their initial composition. For certain compositions, thermoreversible emulsions could be formed that were opaque at high temperatures but transparent at ambient temperatures. These systems may be particularly suitable for the encapsulation of bioactive agents in applications where optical clarity is important. PMID:26431057

  8. Temperature driven evolution of thermal, electrical, and optical properties of Ti–Al–N coatings

    PubMed Central

    Rachbauer, Richard; Gengler, Jamie J.; Voevodin, Andrey A.; Resch, Katharina; Mayrhofer, Paul H.

    2012-01-01

    Monolithic single phase cubic (c) Ti1−xAlxN thin films are used in various industrial applications due to their high thermal stability, which beneficially effects lifetime and performance of cutting and milling tools, but also find increasing utilization in electronic and optical devices. The present study elucidates the temperature-driven evolution of heat conductivity, electrical resistivity and optical reflectance from room temperature up to 1400 °C and links them to structural and chemical changes in Ti1−xAlxN coatings. It is shown that various decomposition phenomena, involving recovery and spinodal decomposition (known to account for the age hardening phenomenon in c-Ti1−xAlxN), as well as the cubic to wurtzite phase transformation of spinodally formed AlN-enriched domains, effectively increase the thermal conductivity of the coatings from ∼3.8 W m−1 K−1 by a factor of three, while the electrical resistivity is reduced by one order of magnitude. A change in the coating color from metallic grey after deposition to reddish-golden after annealing to 1400 °C is related to the film structure and discussed in terms of film reflectivity. PMID:23482424

  9. 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.

  10. Nanoscale probing of thermal, stress, and optical fields under near-field laser heating.

    PubMed

    Tang, Xiaoduan; Xu, Shen; Wang, Xinwei

    2013-01-01

    Micro/nanoparticle induced near-field laser ultra-focusing and heating has been widely used in laser-assisted nanopatterning and nanolithography to pattern nanoscale features on a large-area substrate. Knowledge of the temperature and stress in the nanoscale near-field heating region is critical for process control and optimization. At present, probing of the nanoscale temperature, stress, and optical fields remains a great challenge since the heating area is very small (~100 nm or less) and not immediately accessible for sensing. In this work, we report the first experimental study on nanoscale mapping of particle-induced thermal, stress, and optical fields by using a single laser for both near-field excitation and Raman probing. The mapping results based on Raman intensity variation, wavenumber shift, and linewidth broadening all give consistent conjugated thermal, stress, and near-field focusing effects at a 20 nm resolution (<λ/26, λ = 32 nm). Nanoscale mapping of near-field effects of particles from 1210 down to 160 nm demonstrates the strong capacity of such a technique. By developing a new strategy for physical analysis, we have de-conjugated the effects of temperature, stress, and near-field focusing from the Raman mapping. The temperature rise and stress in the nanoscale heating region is evaluated at different energy levels. High-fidelity electromagnetic and temperature field simulation is conducted to accurately interpret the experimental results.

  11. 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.

  12. Directivity patterns of laser-generated sound in solids: Effects of optical and thermal parameters.

    PubMed

    Krylov, Victor V

    2016-07-01

    In the present paper, directivity patterns of laser-generated sound in solids are investigated theoretically. Two main approaches to the calculation of directivity patterns of laser-generated sound are discussed for the most important case of thermo-optical regime of generation. The first approach, which is widely used in practice, is based on the simple modelling of the equivalent thermo-optical source as a mechanical dipole comprising two horizontal forces applied to the surface in opposite directions. The second approach is based on the rigorous theory that takes into account all acoustical, optical and thermal parameters of a solid material and all geometrical and physical parameters of a laser beam. Directivity patterns of laser-generated bulk longitudinal and shear elastic waves, as well as the amplitudes of generated Rayleigh surface waves, are calculated for different values of physical and geometrical parameters and compared with the directivity patterns calculated in case of dipole-source representation. It is demonstrated that the simple approach using a dipole-source representation of laser-generated sound is rather limited, especially for description of generated longitudinal acoustic waves. A practical criterion is established to define the conditions under which the dipole-source representation gives predictions with acceptable errors. It is shown that, for radiation in the normal direction to the surface, the amplitudes of longitudinal waves are especially sensitive to the values of thermal parameters and of the acoustic reflection coefficient from a free solid surface. A discussion is given on the possibility of using such a high sensitivity to the values of the reflection coefficient for investigation of surface properties of real solids.

  13. 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.

  14. Directivity patterns of laser-generated sound in solids: Effects of optical and thermal parameters.

    PubMed

    Krylov, Victor V

    2016-07-01

    In the present paper, directivity patterns of laser-generated sound in solids are investigated theoretically. Two main approaches to the calculation of directivity patterns of laser-generated sound are discussed for the most important case of thermo-optical regime of generation. The first approach, which is widely used in practice, is based on the simple modelling of the equivalent thermo-optical source as a mechanical dipole comprising two horizontal forces applied to the surface in opposite directions. The second approach is based on the rigorous theory that takes into account all acoustical, optical and thermal parameters of a solid material and all geometrical and physical parameters of a laser beam. Directivity patterns of laser-generated bulk longitudinal and shear elastic waves, as well as the amplitudes of generated Rayleigh surface waves, are calculated for different values of physical and geometrical parameters and compared with the directivity patterns calculated in case of dipole-source representation. It is demonstrated that the simple approach using a dipole-source representation of laser-generated sound is rather limited, especially for description of generated longitudinal acoustic waves. A practical criterion is established to define the conditions under which the dipole-source representation gives predictions with acceptable errors. It is shown that, for radiation in the normal direction to the surface, the amplitudes of longitudinal waves are especially sensitive to the values of thermal parameters and of the acoustic reflection coefficient from a free solid surface. A discussion is given on the possibility of using such a high sensitivity to the values of the reflection coefficient for investigation of surface properties of real solids. PMID:26851995

  15. 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.

  16. Measurement-induced disturbance and thermal negativity in 1D optical lattice chain

    SciTech Connect

    Guo, Jin-Liang; Lin-Wang; Long, Gui-Lu

    2013-03-15

    We study the measurement-induced disturbance (MID) in a 1D optical lattice chain with nonlinear coupling. Special attention is paid to the difference between the thermal entanglement and MID when considering the influences of the linear coupling constant, nonlinear coupling constant and external magnetic field. It is shown that MID is more robust than thermal entanglement against temperature T and external magnetic field B, and MID may reveal more properties about quantum correlations of the system, which can be seen from the point of view that MID can be nonzero when there is no thermal entanglement and MID can detect the critical point of quantum phase transition at finite temperature. - Highlights: Black-Right-Pointing-Pointer The nonlinear coupling constant can strengthen the quantum correlation. Black-Right-Pointing-Pointer MID is more robust than entanglement against temperature and magnetic field. Black-Right-Pointing-Pointer MID exhibits more information about quantum correlation than entanglement. Black-Right-Pointing-Pointer MID can detect the critical point of quantum phase transition at finite temperature.

  17. 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.

  18. 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.

  19. 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

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

    PubMed

    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

  1. 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

  2. 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.

  3. 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

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

    PubMed

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

    2015-06-15

    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. PMID:25766476

  5. 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.

  6. Characteristics of a Low F-Number Broadband Visible Thermal Optical Limiter

    NASA Astrophysics Data System (ADS)

    Swartzlander, G. A.; Justus, B. L.; Huston, A. L.; Campillo, A. J.; Law, C. T.

    The operation of a wide field-of-view optical limiter is described for self-defocusing type nonlinear refractive materials, and design strategies were developed with the aid of numerical modeling. Experiments with a cell thickness on the order of the Rayleigh length (25-100 µm) were conducted with 6 and 30 nsec pulse lengths (single shot) at a wavelength of 532 nm. Broadband optical limiting with the transmitted fluence below the eye MPE (maximum permissible exposure) level was achieved using nigrosin dye dissolved in CS2, owing to the large thermal nonlinearity of the solvent, and the large changes in the refractive index allowed by a liquid. The device performance was accurately predicted by the numerical model up to the point of dielectric breakdown. Using 6 nsec pulses, we measured a limiting threshold energy of 40 nJ, which corresponds to a fluence of only 100 mJ/cm2 in the solution, in an f/5 optical system with neutral gray transmission of ~ 50%.

  7. 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.

  8. Chemical Modification of Cellulose Nanofibers for the Production of Highly Thermal Resistant and Optically Transparent Nanopaper for Paper Devices.

    PubMed

    Yagyu, Hitomi; Saito, Tsuguyuki; Isogai, Akira; Koga, Hirotaka; Nogi, Masaya

    2015-10-01

    Optically transparent cellulose nanopaper is one of the best candidate substrates for flexible electronics. Some types of cellulose nanopaper are made of mechanically or chemically modified cellulose nanofibers. Among these, nanopapers produced from chemically modified cellulose nanofibers are the most promising substrate because of their lower power consumption during fabrication and higher optical transparency (lower haze). However, because their thermal durability is as low as plastics, paper devices using chemically modified nanopaper often do not have sufficiently high performance. In this study, by decreasing the carboxylate content in the cellulose nanofibers, the thermal durability of chemically modified nanopaper was drastically improved while maintaining high optical transparency, low coefficient of thermal expansion, and low power consumption during fabrication. As a result, light-emitting diode lights illuminated on the chemically modified nanopaper via highly conductive lines, which were obtained by printing silver nanoparticle inks and high-temperature heating. PMID:26402324

  9. 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}.

  10. 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.

  11. 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.

  12. Synthesis, structural, optical, thermal and dielectric studies on new organic nonlinear optical crystal by solution growth technique.

    PubMed

    Prakash, M; Geetha, D; Lydia Caroline, M

    2013-04-15

    Single crystals of L-phenylalanine-benzoic acid (LPBA) were successfully grown from aqueous solution by solvent evaporation technique. Purity of the crystals was increased by the method of recrystallization. The XRD analysis confirms that the crystal belongs to the monoclinic system with noncentrosymmetric space group P21. The chemical structure of compound was established by FT-NMR technique. The presence of functional groups was estimated qualitatively by Fourier transform infrared analysis (FT-IR). Ultraviolet-visible spectral analyses showed that the crystal has low UV cut-off at 254 nm combined with very good transparency of 90% in a wide range. The optical band gap was estimated to be 6.91 eV. Thermal behavior has been studied with TGA/DTA analyses. The existence of second harmonic generation (SHG) efficiency was found to be 0.56 times the value of KDP. The dielectric behavior of the sample was also studied for the first time. PMID:23416904

  13. 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.

  14. 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.

  15. Laser induced surface damage, thermal transport and microhardness studies on certain organic and semiorganic nonlinear optical crystals

    NASA Astrophysics Data System (ADS)

    Manivannan, S.; Dhanuskodi, S.; Tiwari, S. K.; Philip, J.

    2008-03-01

    N-alkyl-2,6-dimethyl-4(1H)-pyridinones, salts of 4-dimethylaminopyridine and 2-amino-5-nitropyridine are considered to be potential candidates for nonlinear optical (NLO) applications, in particular for the generation of blue-green laser radiation. Single crystals were grown following the slow evaporation technique at constant temperature. Single-shot laser-induced surface damage thresholds in the range 3-10 GW/cm2 were measured using a 18 ns Q-switched Nd:YAG laser. The surface morphologies of the damaged crystals were examined under an optical microscope and the nature of damage identified. The Vicker’s microhardness was determined at a load of 98.07 mN. The thermal transport properties, thermal diffusivity (α), thermal effusivity (e), thermal conductivity (K) and heat capacity (Cp), of the grown crystals were measured by an improved photopyroelectric technique at room temperature. All the results are presented and discussed.

  16. 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

  17. Optical characterization and feasibility study of multifunctional polylactic-co-glycolic acid (PLGA) nanoparticles designed for photo-thermal optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Subhash, Hrebesh M.; Xie, Hui; Smith, Jeffrey W.; McCarty, Owen

    2011-06-01

    Nanoparticles with plasmon-resonance absorption in the near-IR (NIR) optical range are of great interest in optical coherence tomography (OCT) for contrast enhancement and diagnostic interventions in molecular imaging. In this study, we characterized the optical properties of multifunctional NIR dye-loaded PLGA nanoparticles (approved by the U.S. Food and Drug Administration) to assess the feasibility of using contrast agent for photo-thermal OCT (PT-OCT) imaging. Tissue phantoms containing NIR dye-doped PLGA nanoparticles were prepared in 2% agarose solution. To study the feasibility of detecting the particles using PT-OCT, imaging was performed with a custom built PT-OCT system, and specific contrast was obtained with the prepared tissue mimicking phantoms. The excellent photo-thermal properties in combination with the positive tissue phantom results qualify the feasibility of dye-loaded PLGA particles as promising candidate for PT-OCT imaging applications.

  18. 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.

  19. Effect of thermal annealing on structure and optical band gap of Se66Te25In9 thin films

    NASA Astrophysics Data System (ADS)

    Dwivedi, D. K.; Pathak, H. P.; Shukla, Nitesh; Kumar, Vipin

    2015-05-01

    Thin films of a-Se66Te25In9 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 (Eg) of a-Se66Te25In9 have been studied.

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

    NASA Astrophysics Data System (ADS)

    Stolz, Christopher J.; Yoshiyama, J. M.; Salleo, Alberto; Wu, Zhouling; Green, John; Krupka, Rene

    1998-04-01

    Multilayer coatings manufactured from metallic hafnium and silica sources by reactive electron beam deposition, are being developed for high fluence optics in a fusion lasers 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 defects 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 micrometers step size and a 3 micrometers pump beam diameter, were 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.

  1. 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.

  2. Optical fiber embedding in thermal spray coating promises new smart materials design able to operate under harsh environment

    NASA Astrophysics Data System (ADS)

    Duo, Yi; Costil, Sophie; Pfeiffer, Pierre; Serio, Bruno

    2014-05-01

    The in-situ detection of temperature or stresses produced by the thermal spraying process is important for both the optimization of the elaboration conditions and the subsequent service monitoring of these systems. Optical fiber sensors are excellent candidates for this area of application since they can be embedded into the layers of several dissimilar materials of smart structures. This work relates mainly to the process of embedding optical fibers into ceramic coatings and to the characteristics of the embedded fiber. Firstly, thermal flame spraying is chosen as the elaboration process. Next, a thermal model is proposed in order to evaluate the thermal strain variation with the temperature during the elaboration process in the structure. Finally, a microscopic observation of the embedded optical fiber in the ceramic coating is reported, the mechanical adhesion strength of the embedded fiber is evaluated and the results of the optical attenuation change during the elaboration process are given. They show that no significant fluctuation of the optical power transmitted in the fiber is observed.

  3. Time-domain optical and thermal properties of blood undergoing laser photocoagulation

    NASA Astrophysics Data System (ADS)

    Black, John F.; Barton, Jennifer K.

    2001-07-01

    We have examined the temporal characteristics of the optical properties of blood undergoing laser-induced photocoagulation during long pulse (10 ms) 532-nm irradiation. The time-domain optical properties were probed at 532 nm, 594 nm, 633 nm and 1064 nm using a newly developed pump-probe technique in a double integrating sphere apparatus. During the 10 ms illumination period, blood evolves from liquid to a liquid blood-coagulum mixture to a system at the liquid/vapor transition in an essentially adiabatic manner. As with previous studies, a sharp rise in the 532 nm signal remitted from the sample can be linked to the onset of coagulation and a concomitant increase in scattering caused by microscopic coagulum particles. We also observe a subsequent decay in this remittance and, at sufficiently high radiant exposures, acoustic and visual transients indicating the onset of microvaporization. Probing the sample at the other wavelengths, we show that the optical properties of the system display highly complex behavior in multiple time frames. We believe that this rich behavior results from the interplay of: i) a time/temperature-dependent red-shift in the absorption spectrum of the oxy-hemoglobin chromophore, ii) coagulation dynamics occurring on at least two distinct time and length scales, and, iii) the creation of at least one new chemical species possessing a different absorption spectrum to that of oxy-hemoglobin. The thermal properties of the system were measured in a time- and spatially-resolved manner using a newly developed technique, and modeled using finite-element analysis incorporating the effects of time-dependent changes in the absorption coefficients of the blood, and phase changes representing coagulation and the liquid/vapor transition. Cross-correlating the optical and thermal studies, we show that the temporal properties of the 532 nm and 633 nm remittance signals can potentially be used to develop a sensitive real-time probe of the onset of

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Optical, thermal, and electrical performance of low-CR solar arrays. [Concentration Ratio

    NASA Technical Reports Server (NTRS)

    French, E. P.; Mills, M. W.; Backovsky, Z.

    1983-01-01

    This paper describes the analysis and testing of a photovoltaic low-CR concentrator shaped like a truncated pyramid with an aperture of 0.5 m on a side and a geometric concentration ratio of six. The truncated base plane is covered by either silicon (Si) or gallium arsenide (GaAs) solar cells. Ray-trace analysis of the concentrator predicts a peak optical efficiency of 0.77, which falls off only gradually with pointing error. A coupled thermal-electrical analysis of the system shows that the moderately nonuniform illumination produced by the concentrator does not result in significant mismatch losses, provided the solar cells are connected in parallel groups. The results of ground tests involving a full-scale prototype concentrator conform well with theoretical predictions.

  9. 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.

  10. Influence of Fe ions on structural, optical and thermal properties of SnO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Ahmed, Ateeq; Tripathi, P.; Khan, Wasi; Dar, Abid Ahmed; Ali, Tinku

    2016-05-01

    In the present work, Fe doped SnO2 nanoparticles with the composition Sn1-xFexO2 (x = 0, 0.02, 0.04 and 0.06) have been successfully synthesized using sol-gel auto combustion technique. The samples are characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray analysis (EDAX), Ultraviolet (UV-Visible) absorption spectroscopy and thermal gravimetric analysis (TGA). The XRD study shows that all the samples have been found in tetragonal rutile structure without any extra phase and average crystallite size which lies in the range of 6-17 nm. The EDAX spectrum confirmed the doping of Fe ion into tin oxide nanomaterial. The optical band gap of doped SnO2 is found to decrease with increasing Fe ion concentration, which is due to the formation of donor energy levels in the actual band gap of SnO2.

  11. 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.

  12. Hollow Silica as an Optically Transparent and Thermally Insulating Polymer Additive.

    PubMed

    Ernawati, Lusi; Ogi, Takashi; Balgis, Ratna; Okuyama, Kikuo; Stucki, Mario; Hess, Samuel C; Stark, Wendelin J

    2016-01-12

    We present an improved synthesis route to hollow silica particles starting from tetramethyl orthosilicate (TMOS) instead of the traditionally used ethyl ester. The silica was first deposited onto polystyrene (PS) particles that were later removed. The here introduced, apparently minor modification in synthesis, however, allowed for a very high purity material. The improved, low density hollow silica particles were successfully implemented into polymer films and permitted maintaining optical transparency while significantly improving the heat barrier properties of the composite. Mechanistic investigations revealed the dominant role of here used methanol as a cosolvent and its role in controlling the hydrolysis rate of the silicic ester, and subsequent formation of hollow silica particles. Systematic experiments using various reaction parameters revealed a transition between regions of inhomogeneous material production at fast hydrolysis rate and reliable silica deposition on the surface of PS as a core-shell structured particle. The shell-thickness was controlled from 6.2 to 17.4 nm by increasing TMOS concentration and the diameter from 95 to 430 nm through use of the different sizes of PS particles. Hollow silica particle with the shell-thickness about 6.2 nm displayed a high light transmittance intensity up to 95% at 680 nm (length of light path ∼ 1 cm). Polyethersulfone (PES)/hollow silica composite films (35 ± 5 μm thick) exhibited a much lower thermal conductivity (0.03 ± 0.005 W m·K(-1)) than pure polymer films. This indicates that the prepared hollow silica is able to be used for cost and energy effective optical devices requiring thermal insulation.

  13. Ambient organic carbon to elemental carbon ratios: influence of the thermal-optical temperature protocol and implications.

    PubMed

    Cheng, Yuan; He, Ke-bin; Duan, Feng-kui; Du, Zhen-yu; Zheng, Mei; Ma, Yong-liang

    2014-01-15

    Ambient organic carbon (OC) to elemental carbon (EC) ratios are strongly associated with not only the radiative forcing due to aerosols but also the extent of secondary organic aerosol (SOA) formation. An inter-comparison study was conducted based on fine particulate matter samples collected during summer in Beijing to investigate the influence of the thermal-optical temperature protocol on the OC to EC ratio. Five temperature protocols were used such that the NIOSH (National Institute for Occupational Safety and Health) and EUSAAR (European Supersites for Atmospheric Aerosol Research) protocols were run by the Sunset carbon analyzer while the IMPROVE (the Interagency Monitoring of Protected Visual Environments network)-A protocol and two alternative protocols designed based on NIOSH and EUSAAR were run by the DRI analyzer. The optical attenuation measured by the Sunset carbon analyzer was more easily biased by the shadowing effect, whereas total carbon agreed well between the Sunset and DRI analyzers. The EC(IMPROVE-A) (EC measured by the IMPROVE-A protocol; similar hereinafter) to EC(NIOSH) ratio and the EC(IMPROVE-A) to EC(EUSAAR) ratio averaged 1.36 ± 0.21 and 0.91 ± 0.10, respectively, both of which exhibited little dependence on the biomass burning contribution. Though the temperature protocol had substantial influence on the OC to EC ratio, the contributions of secondary organic carbon (SOC) to OC, which were predicted by the EC-tracer method, did not differ significantly among the five protocols. Moreover, the SOC contributions obtained in this study were comparable with previous results based on field observation (typically between 45 and 65%), but were substantially higher than the estimation provided by an air quality model (only 18%). The comparison of SOC and WSOC suggests that when using the transmittance charring correction, all of the three common protocols (i.e., IMPROVE-A, NIOSH and EUSAAR) could be reliable for the estimation of SOC by the EC

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Crystal Growth, Thermal, Optical, and Dielectric Properties of L-Lysine Doped Kdp Crystals

    NASA Astrophysics Data System (ADS)

    Parikh, Ketan D.; Dave, Dipak J.; Joshi, Mihir J.

    Single crystals of pure and various amount of L-lysine doped KDP crystals were grown from aqueous solution. The doping of L-lysine was confirmed by CHN analysis and FT-IR spectroscopy. Powder XRD was carried out to assess the single phase nature of the samples. The effect of doping on thermal stability of the crystals was carried out by TGA and the kinetic and thermodynamic parameters of dehydration were evaluated. It was found that as the amount of doping of amino acid, L-lysine, increased the thermal stability of the grown crystals decreased. However, the second-harmonic generation (SHG) efficiency of Nd:YAG laser and UV-vis spectroscopy studies indicated that as the L-lysine doping increased in KDP crystals the SHG efficiency and optical transmission percentage increased. The dielectric constant and the dielectric loss of L-lysine doped KDP crystals are lower than the pure KDP crystals. Hence L-lysine doped KDP crystals are found to be more beneficial from an application point of view as compared to pure KDP crystals. The results are discussed.

  19. Comparison of thermal corneal lesions by optical coherence tomography (OCT) and polarization histology

    NASA Astrophysics Data System (ADS)

    Koop, Norbert; Brinkmann, Ralf; Kaftan, Bjorn; Asiyo-Vogel, Mary; Engelhardt, Ralf; Birngruber, Reginald

    1996-12-01

    Corneal thermal lesions as typically applied in laser thermokeratoplasty were investigated with optical coherence tomography (OCT) and polarization microscopy. Both methods were used to compare the lesions with respect to the extent and degree of thermal denaturation. The coagulations wee applied on enucleated porcine eyes using a continuously emitting laser diode at a wavelength of 1.86 micrometers . The self developed OCT-system has an axial and lateral resolution of 15-20 micrometers and 26-48 micrometers , respectively, and was used to perform cross sections through the lesions. After OCT on the intact globe, the sections were fixed in formalin and embedded in paraffin. The sections were stained with sirius red and analyzed by polarization light microscopy. The comparison of the backscattered light of the OCT image with the changes in birefringence detected with the polarization microscopy technique found to be in good agreement. Up to four changes in birefringence detected with the polarization microscopy technique found to be in good agreement.Up to four different degrees of denaturation zones could be classified in both methods. OCT findings taken from a noninvasive method and correlated with histological experiences can be used to control the extent and degree of corneal lesions and monitor their healing response.

  20. 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.

  1. 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

    2016-07-01

    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.

  2. Modelling of thermally detected optical absorption and luminescence of (In,Ga)N/GaN heterostructures

    NASA Astrophysics Data System (ADS)

    Siozade, L.; Leymarie, J.; Disseix, P.; Vasson, A.; Mihailovic, M.; Grandjean, N.; Leroux, M.; Massies, J.

    2000-08-01

    Thermally detected optical absorption (TDOA) and photoluminescence (PL) experiments are performed at 0.35 and 4 K, respectively, on In xGa 1- xN ( x≤0.12) layers grown on GaN by molecular beam epitaxy. The modelling of absorption allows us to extract the absorption coefficients and bandgap energies of (In,Ga)N alloy. A bowing parameter equal to 2.4 eV is deduced. The knowledge of the GaN complex refractive index, previously measured, enables us to account for the Fabry-Perot interferences which structure the TDOA and PL spectra. A procedure is proposed to remove the latter in the PL spectrum of nitride based heterostructures. The model is based on the description of the light propagation in an active layer sandwiched between two heterostructures. The parameters deduced from the absorption line shape adjustment are used to take the absorption and optical path into account in the different layers of the samples.

  3. 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.

  4. 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.

  5. 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.

  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. Thermally induced passage and current of particles in a highly unstable optical potential

    NASA Astrophysics Data System (ADS)

    Ryabov, Artem; Zemánek, Pavel; Filip, Radim

    2016-10-01

    We discuss the statistics of first-passage times of a Brownian particle moving in a highly unstable nonlinear potential proportional to an odd power of position. We observe temperature-induced shortening of the mean first-passage time and its dependence on the power of nonlinearity. We propose a passage-time fraction as both a simple and experimentally detectable witness of the nonlinearity. It is advantageously independent of all other parameters of the experiment and observable for a small number of trajectories. To better characterize the stochastic passage in the unstable potential, we introduce an analogy of the signal-to-noise ratio for the statistical distribution of the first-passage times. Interestingly, the upper bound for the signal-to-noise ratio is temperature independent in the unstable potential. Finally, we describe the nonequilibrium steady state of the particle cyclically passing through unstable odd nonlinearity. The maximum of the steady-state probability distribution shifts against the directions of the current and this counterintuitive effect increases with temperature. All these thermally induced effects are very promising targets for experimental tests of highly nonlinear stochastic dynamics of particles placed into optical potential landscapes of shaped optical tweezers.

  8. Structural and optical properties of thermally evaporated Ga-In-Se thin films

    NASA Astrophysics Data System (ADS)

    Işik, Mehmet; Güllü, Hasan Hüseyin

    2014-05-01

    In this paper, structural and optical properties of Ga-In-Se (GIS) thin films deposited by thermal evaporation technique have been investigated. The effect of annealing was also studied for samples annealed at temperatures between 300°C and 500°C. X-ray diffraction, energy dispersive X-ray analysis and scanning electron microscopy have been used for structural characterization. It was reported that increase of annealing temperature results with better crystallization and chemical composition of the films were almost same. Optical properties of the films were studied by transmission measurements in the wavelength range of 320-1100 nm. The direct bandgap transitions with energies in the range of 1.52 eV and 1.65 eV were revealed for the investigated GIS films. Photon energy dependence of absorption coefficient showed that there exist three distinct transition regions for films annealed at 400°C and 500°C. The quasicubic model was applied for these transitions to calculate crystal-field splitting and spin-orbit splitting energy values.

  9. 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.

  10. 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.

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

    PubMed

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

    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.

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

    PubMed

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

    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. PMID:26590551

  13. Thermal and optical behavior of sapphire fiber tips for laser angioplasty

    NASA Astrophysics Data System (ADS)

    Ashley, Simon; Brooks, Stephen G.; Gehani, Abdurrazak A.; Kester, Ralph C.; Rees, Michael R.

    1990-07-01

    Atraumatic rounded contact probes made from artificial sapphire crystal were developed for general laser surgery and are currently being evaluated for use in percutaneous laser angioplasty utilising continuous wave (cw) Nd-YAG energy (1064nm). The thermal and optical characteristics of five different types of rounded sapphire probe [Surgical Laser Technologies (SLT) - SMTR (1.8mm), MTh (2.2mm), MTRL (3.0mm); Living Technology - LT (2.2mm), OS (2.2mm)] were investigated and related to efficiency of contact ablation of arterial wall in vitro. The sapphire probes were mounted on catheters containing a 0.6 mm quartz optical fiber, coupled to a cw Nd-YAG laser. All probes produced a similar beam profile but there was some variation in their forward transmission of energy (54-85%).Probe heating occurs due to energy absorption within the sapphire and was measured in air by infrared thermography. There was a high temperature gradient from the front surface of the sapphires to the probe rim. But, at energy settings used clinically (10 J pulses, 10 Watts for 1 second) the SMTR, MTR, and MTRL probes exhibited a higher mean temperature rise (63-74 C) than the OS and LT probes (20 C) [3-way ANOVA pthermal injury to surrounding vessel. These properties enhanced contact ablation by the MTR probe relative to the other 2.2mm probes when applied with a downward force of 80 g, perpendicular to fresh porcine aortic segments immersed in whole blood. Penetration efficiencies at energy levels producing the most efficient ablation by each probe were as follows [mean (SD) microns/JI:- MTR 50 (7), LT 9 (5), 05 4 (2), (p

  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. 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.

  16. 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...

  17. Long-range interatomic forces can minimize heat transfer: From slowdown of longitudinal optical phonons to thermal conductivity minimum

    NASA Astrophysics Data System (ADS)

    Han, Haoxue; Feng, Lei; Xiong, Shiyun; Shiga, Takuma; Shiomi, Junichiro; Volz, Sebastian; Kosevich, Yuriy A.

    2016-08-01

    We investigate the role of interatomic forces beyond the nearest neighbors on the thermal transport through an atomic junction with a heavy isotope impurity and in a silicon-germanium-like alloy with atomistic calculations. The thermal conductance of the junction incorporating second-nearest-neighbors forces reaches its minimum when the longitudinal optical phonon resonances in the phonon transmission are minimized. We relate the weakening of the optical phonon resonance with the flattening of the longitudinal optical phonon band of the infinite diatomic lattice with second-nearest-neighbors forces, which is the limit of an extended junction. We emphasize that the bypass of the heavy-atom components in the diatomic lattice by long-range interatomic bonds is crucial for the realization of the minimum in bulk thermal conductivity. We highlight the connection between the minimal thermal conductivity of a SiGe-like alloy with the flattening of the longitudinal optical phonon band of the diatomic lattice due to the second-nearest-neighbors forces, in combination with enhanced anharmonic phonon processes and phonon localizations.

  18. ESTE: Verification of Portable Optical and Thermal Imaging Devices for Leak Detection at Petroleum Refineries and Chemical Plants

    EPA Science Inventory

    This is an ESTE project summary brief. EPA’s Environmental Technology Verification Program (ETV) is verifying the performance of portable optical and thermal imaging devices for leak detection at petroleum refineries and chemical plans. Industrial facilities, such as chemical p...

  19. 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 (...

  20. 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...

  1. 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.

  2. 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.

  3. Thermal casting of polymers in centrifuge for producing X-ray optics

    DOEpatents

    Hill, Randy M.; Decker, Todd A.

    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.

  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. Development of a Black Carbon Standard for Thermal-OpticalAnalysis

    SciTech Connect

    Kirchstetter, Thomas

    2006-01-30

    Carbonaceous aerosols affect air quality and climate, but measurements of black (BC) and organic (OC) carbon concentrations are very uncertain. Many variants of the thermal-optical analysis (TOA) method exist, and more than a decade of research has not resolved the differences in their estimates of OC and BC (i.e., the OC/BC split). This is largely due to the lack of a BC standard. Without a BC standard, the accuracy of TOA measurements of OC and BC cannot be determined. The research goal is to develop a method of producing BC standards that can be used to determine the accuracy in TOA measurements of OC and BC. The uncertainty in TOA measurements is due to the presence of both OC and BC in particulate matter. Whereas measuring total carbon (TC) is straightforward, OC pyrolysis and charring and premature evolution of BC render determination of the OC/BC split uncertain (and method dependent) (1,2,3). If a particulate matter sample containing only OC or BC was analyzed by TOA, there would be little uncertainty in the measurement. Our approach to developing a standard for TOA, therefore, is to (1) generate particulate matter composed only of BC and fully characterize the physical and optical properties of the BC, (2) demonstrate that this BC can be collected in known amounts on filters and (3) reproduce filter samples with known amounts of BC mixed with other aerosol species, most notably OC. These filters, having known amounts of BC, could be used as standards for determining the accuracy of TOA measurements of BC and the OC/BC split. TOA methods could then be optimized for accuracy.

  6. Amorphous Silicon Thin-Film Thermal Property and Optical Damage Investigations by Non-Contact Laser Methods

    NASA Astrophysics Data System (ADS)

    Kuo, Bob Shih-Wei

    The objective of this investigation is to develop a reliable optical system for determining the thermal properties of thin solid-film materials and to study the effects of these properties on laser damage threshold. The system is tested with actually measuring the thermal conductivity and interface resistance of a set of well-studied silicon film samples and these results are related to the damage thresholds. In the first part, an in situ, non-contact, photothermal displacement (PTD) interferometer for performing thermal conductivity measurements is established. Localized transient surface motion is generated through photothermoelastic coupling of a short, heating laser pulse to the sample under investigation. The maximum surface displacement is found to be linearly dependent on the laser power. The thermal conductivity, on the other hand, determines the proportionality of the linear dependence. Both thin-film thermal conductivity and film/substrate interface thermal resistance are derived from the measured, effective thermal diffusivity by employing simple heat-flow analysis. Wedge -shaped Si films, vacuum deposited on single crystal Si wafers are studied with this technique. A sample prepared by ion bombardment of the wafer surface prior to film deposition shows the same film diffusivity as a sample film deposited on an as-cast wafer, while the uncleaned sample exhibits higher interface thermal resistance. It is found that the thin-film thermal conductivity is somewhat lower than the bulk value. However, the existence of an interface thermal resistance, when combined with film thermal diffusivity, can result in an effective thermal diffusivity as low as two orders of magnitude lower than the bulk value. To substantiate the PTD measurements, laser damage tests are performed on these same samples following the derivation of thermal data. These damage-test results show the significant roles of the thermal properties of the samples on their respective damage

  7. Tooth structural health monitoring with a fiber optic microbend sensor

    NASA Astrophysics Data System (ADS)

    Kishen, A.; Rafique, A.

    2006-02-01

    The purpose of this study is to monitor structural response in intact teeth and teeth with structural loss using a noninvasive fiber optic microbend (FOMB) sensor. In this study a miniature fiber optic microbend sensor is fabricated and tested on intact tooth specimens, tooth specimens in which one-third crown structure was removed, tooth specimens in which access cavity was prepared and tooth specimens in which access cavity and root canal were prepared. The microbend sensor displayed a direct relationship between the applied load and the output light intensity. The rate of change in light intensity with increase in loads corresponded with the structural response of the tooth. This experiment highlights the potential of FOMB sensor technology to quantitatively monitor tooth structural loss during post endodontic restorations.

  8. Thermally stable J-type phthalocyanine dimers as new non-linear absorbers for low-threshold optical limiters.

    PubMed

    Tolbin, Alexander Yu; Savelyev, Mikhail S; Gerasimenko, Alexander Yu; Tomilova, Larisa G; Zefirov, Nikolay S

    2016-06-21

    The possibility of developing new advanced optical limiters of laser radiation at 532 nm with low limiting thresholds has been demonstrated on thermally stable phthalocyanine J-type dimeric complexes of Mg, Zn, Cu, Ni, and Co. A new "threshold" model based on radiative transfer phenomena in nonlinear optical media was suggested for the exact definition of nonlinear absorption coefficient β and optical limiting threshold Ic. This model allows the determination of the optical characteristics of the limiter in the same active material with layers of different thicknesses, as well as the use of different parameters of laser radiation, such as cross-sectional spatial profiles of the laser beam and shapes of the laser pulse over time. The maximum value of the nonlinear absorption coefficient (β = 360 cm GW(-1)) and the lowest limiting threshold (Ic = 0.03 J cm(-2)) were estimated for a J-type zinc phthalocyanine dimer. PMID:27241278

  9. 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%.

  10. Studies on the growth, structural, thermal, mechanical and optical properties of the semiorganic nonlinear optical crystal L-glutamic acid hydrobromide

    NASA Astrophysics Data System (ADS)

    Dhanasekaran, P.; Srinivasan, K.

    2013-07-01

    Single crystals of optically significant L-glutamic acid hydrobromide were grown from aqueous solutions and their various properties were characterized. The title compound was synthesized with stoichiometric ratio 1:1, purified by recrystallization, confirmed by powder X-ray diffraction and its solubility in double distilled water in the temperature range 30-80 °C was determined by the gravimetric method. Large dimensional (45×26×14 mm3) optically transparent single crystal of the compound was grown by a controlled slow cooling method combined with the reversible seed rotation technique. The morphological importance of the grown crystal was studied in accordance with equilibrium morphology. Samples of the grown crystal were subjected to single crystal X-ray diffraction study for structural analysis, Fourier transform infrared spectroscopy for functional group analysis, TG-DTA/DSC for thermal analysis, Vickers microhardness study for mechanical strength, UV-vis-NIR spectral analysis for optical transparency and the Kurtz powder method for SHG efficiency of the grown crystal. Results indicate that the grown crystal has significant improvement in its thermal, optical and SHG properties when compared to pure L-glutamic acid polymorphs.

  11. Research on reverse association mechanism of the thermal control performance of conducting optical solar reflector and its antistatic properties

    NASA Astrophysics Data System (ADS)

    Chang, Tianhai; Wu, Shuling; Xing, Zheng; Wei, Xiaoqun

    2014-12-01

    As we know, optical solar reflector (OSR) is used as the thermal control element for communications satellites and other spacecraft. The solar absorption, infrared emissivity and their ratio of OSR, are considered as the main standard of its thermal control performance. OSR is divided into conducting OSR and non-conducting OSR. When using the indium tin oxide (ITO) film coated on the surface of conducting OSR's glass substrate, ITO film will improve OSR's solar absorption rate and reduce the infrared emissivity. That means the thermal control performance will be declined. The paper is aimed to revealing the reverse association mechanism between the thermal control performance of conducting OSR used for spacecraft and the antistatic properties of ITO film. First, we combined the Drude theory with the Thermal radiation theorem to analyze how the antistatic parameters of ITO film impact the solar absorption and the infrared emissivity of OSR. Then,based on the theoretic analysis of main antistatic parameters of ITO, including the surface square resistance, secondary electron emission characteristic, solar absorption rate, infrared emissivity and other optical and electrical parameters. It illustrated that those factors have a strong reverse connection with the thermal control parameters of OSR, and influenced the solar absorption, infrared emissivity and their ratio of OSR. Comparison of the predicted and experimental results demonstrate that when reducing the surface square resistance of the ITO film, the antistatic properties was declined, and increased the value of the OSR solar absorption. On the contrary, reducing the infrared emissivity, It would result in the degradation of OSR's thermal control performance. The study has performed that the reverse association mechanism of conducting OSR can't be ignored. And apparently it shows that if we want to keep its application in the spacecraft thermal control environment and antistatic properties long-term stable, the

  12. Fiber optic sensors for health monitoring of morphing airframes: I. Bragg grating strain and temperature sensor

    NASA Astrophysics Data System (ADS)

    Wood, Karen; Brown, Timothy; Rogowski, Robert; Jensen, Brian

    2000-04-01

    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 to infer integrity of the aircraft structure. Part 1 of this two part series describes sensors that will measure load and temperature signatures of these structures. In some cases a single fiber may be used for measuring these parameters. Part 2 will describe techniques for using optical fibers to monitor composite cure in real time during manufacture and to monitor in-service integrity of composite structures using a single fiber optic sensor capable of measuring multiple chemical and physical parameters. The facilities for fabricating optical fiber and associated sensors and the methods of demodulating Bragg gratings for strain measurement will be described.

  13. Relevance of thermal environment to human health: a case study of Ondo State, Nigeria

    NASA Astrophysics Data System (ADS)

    Omonijo, Akinyemi Gabriel; Adeofun, Clement Olabinjo; Oguntoke, Olusegun; Matzarakis, Andreas

    2013-07-01

    The interconnection between weather and climate and the performance, well-being, and human health cannot be overemphasized. The relationship between them is of both local and global significance. Information about weather, climate, and thermal environment is very important to human health and medical practitioners. The most crucial environmental information needed by medical practitioners and for maintaining human health, performance, and well-being are thermal conditions. The study used meteorological variables: air temperature, relative humidity, wind speed, solar radiation, and RayMan model as an analytical tool to compute physiologically equivalent temperature (PET) in order to assess thermo-physiological thresholds in Ondo State. The study revealed that there are marked spatial and seasonal variations in the environmental thermal conditions in the study area. The results of physiologically equivalent temperature for different grades of thermal sensation and physiological stress on human beings indicate that about 60 % of the total study period (1998-2008) fall under physiological stress level of moderate heat stress (PET 31-36 °C). In derived savannah, 32.6 % out of the total study period was under strong heat stress. In view of this, the study concluded that Ondo State may likely be prone to heat-related ailments and that some of the death recorded in the State, in recent times, may be heat-related mortality, but this is difficult to ascertain because there is no postmortem records in Nigeria where it could be confirmed. This type of study is relevant to help government to improve health care interventions and achieve Millennium Development Goals in health sector.

  14. 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.

  15. 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.

  16. 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. PMID:26353558

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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.

  2. 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. PMID:25133250

  3. Evaluating distributed fibre optic sensors integrated into thermoplastic composites for structural health monitoring

    NASA Astrophysics Data System (ADS)

    Schilder, Constanze; Schukar, Marcus; Steffen, Milan; Krebber, Katerina

    2014-05-01

    Strain sensors used for structural health monitoring (SHM) must provide reliable measurement data during their entire service lifetime. To achieve this for fibre optic sensors integrated into composites, the integration of the sensor has to be adapted according to the process conditions. This paper describes the fabrication of thermoplastic composite samples with integrated distributed fibre optic sensors (DFOS) based on copper-nickel and polyimide coated silica optical fibres. The performance of these DFOS as SHM sensors is evaluated in terms of reliability by measurements derived from comparative measurements with resistance strain gauges and from fatigue tests with 10 million load cycles.

  4. Design and Operation of an Optically-Accessible Modular Reactor for Diagnostics of Thermal Thin Film Deposition Processes.

    PubMed

    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 cm(2) 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.

  5. 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. PMID:26642449

  6. 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.

  7. 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.

  8. Investigation of optical and thermal properties of N-(alkyl-substituted) maleimides for use in zero-zero-birefringence polymer.

    PubMed

    Beppu, Shotaro; Hotta, Hikaru; Shafiee, Houran; Tagaya, Akihiro; Koike, Yasuhiro

    2015-02-01

    N-(alkyl-substituted) maleimides (RMIs) were proposed as materials useful for the development of a zero-zero-birefringence polymer that exhibits no birefringence. We analyzed the optical and thermal properties of poly(RMI)s, such as the refractive index, birefringence, and glass transition temperature. The characteristics of the obtained polymers varied significantly because the shift of the density and polarizability derived from the change of the substituent structure influenced the optical properties, and the bulkiness of the substituents influenced the thermal properties. We also designed a zero-zero-birefringence polymer using N-ethyl maleimide (EMI) as a comonomer, and the obtained copolymer had no birefringence, relatively high heat resistance, and high transparency. PMID:25967788

  9. Thermal lens study of thermo-optical properties and concentration quenching of Er3+-doped lead pyrophosphate based glasses

    SciTech Connect

    Santos, C. C.; Rocha, U.; Guedes, Ilde; Vermelho, M. V. D.; Boatner, Lynn A; Jacinto, C.

    2012-01-01

    In this work, we have used the thermal lens technique combined with conventional spectroscopy to characterize the thermo-optical properties of Er3+-doped lead pyrophosphate-based glasses. More precisely, we have investigated and quantified experimentally the fluorescence quantum efficiencies of the Er3+ levels, and we describe the role of concentration quenching effects. The fluorescence quantum efficiency of the 4I13/2 level is very high when compared to other phosphate glasses, while that of the green-coupled levels is very small. Other important photonic materials parameters, such as the thermal diffusivity and temperature coefficient of the optical path length change, were obtained and compared with those of other glass systems. The cumulative results obtained here for the Er-doped lead pyrophosphate glass show that this material is a good candidate for photonic applications with a characteristic Er3+ infrared emission around 1550 nm.

  10. Growth of N-Glycyl-L-Valine (GV) single crystal and its spectral, thermal and optical characterization

    NASA Astrophysics Data System (ADS)

    Janarthanan, S.; Sugaraj Samuel, R.; Rajan, Y. C.; Suresh, P.; Thangaraj, K.

    2013-03-01

    A nonlinear optical crystal of N-Glycyl-L-Valine (GV) single crystals was grown by slow evaporation solution growth technique from an aqueous solution. The unit cell parameters and the crystal structure were determined by single crystal X-ray diffraction study. The Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (1H NMR) spectral studies were carried out to identify the functional groups of the grown crystals. The ultraviolet visible near infrared (UV-Vis-NIR) spectrum was recorded to study the optical transparency of the grown crystal. The thermogravimetric (TG) and differential thermal (DTA) analyses revealed the thermal stability of the sample. The presence of second harmonic generation (SHG) for the grown crystal was confirmed by Kurtz-Perry powder technique.

  11. 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.

  12. Thermal/Optical Methods for Elemental Carbon Quantification in Soils and Urban Dusts: Equivalence of Different Analysis Protocols

    PubMed Central

    Han, Yongming; Chen, Antony; Cao, Junji; Fung, Kochy; Ho, Fai; Yan, Beizhan; Zhan, Changlin; Liu, Suixin; Wei, Chong; An, Zhisheng

    2013-01-01

    Quantifying elemental carbon (EC) content in geological samples is challenging due to interferences of crustal, salt, and organic material. Thermal/optical analysis, combined with acid pretreatment, represents a feasible approach. However, the consistency of various thermal/optical analysis protocols for this type of samples has never been examined. In this study, urban street dust and soil samples from Baoji, China were pretreated with acids and analyzed with four thermal/optical protocols to investigate how analytical conditions and optical correction affect EC measurement. The EC values measured with reflectance correction (ECR) were found always higher and less sensitive to temperature program than the EC values measured with transmittance correction (ECT). A high-temperature method with extended heating times (STN120) showed the highest ECT/ECR ratio (0.86) while a low-temperature protocol (IMPROVE-550), with heating time adjusted for sample loading, showed the lowest (0.53). STN ECT was higher than IMPROVE ECT, in contrast to results from aerosol samples. A higher peak inert-mode temperature and extended heating times can elevate ECT/ECR ratios for pretreated geological samples by promoting pyrolyzed organic carbon (PyOC) removal over EC under trace levels of oxygen. Considering that PyOC within filter increases ECR while decreases ECT from the actual EC levels, simultaneous ECR and ECT measurements would constrain the range of EC loading and provide information on method performance. Further testing with standard reference materials of common environmental matrices supports the findings. Char and soot fractions of EC can be further separated using the IMPROVE protocol. The char/soot ratio was lower in street dusts (2.2 on average) than in soils (5.2 on average), most likely reflecting motor vehicle emissions. The soot concentrations agreed with EC from CTO-375, a pure thermal method. PMID:24358286

  13. Optical characterization of vitreous structure in health and disease

    NASA Astrophysics Data System (ADS)

    Sampathkumar, Ashwin; Khoshnevis, Matin; Ketterling, Jeffrey A.; Sebag, J.

    2015-03-01

    Patients with myopic vitreopathy (MV) and posterior vitreous detachment (PVD) see floaters, which often can degrade contrast sensitivity to a significant extent. The floaters are associated with irregularly shaped vitreous opacities. In contrast, asteroid hyalosis (AH), which is characterized by microscopic, spherical, white asteroid bodies (ABs) that move with vitreous displacement during eye movements, does not interfere significantly with vision. We hypothesize that the irregular surface of vitreous opacities associated with MV distinguish MV from AH and its smooth-surfaced ABs. A finite-element model was developed to characterize the light-scattering field of vitreous opacities in MV and AH. Vitreous opacities were modeled as spherical bodies and illuminated by a plane wave of light in the optical wavelength of 400-1000 nm. The model has provisions to add random perturbations to the spherical surfaces to vary light-scattering properties and mimic disturbances in vision from simple diffraction rings to more-complex patterns. Samples of ex vivo porcine vitreous (0.4-0.5 ml) were placed in a custom spectrophotometer and the static, light-scattering field of the sample was measured in the spectral range of 400-1000 nm with a resolution of 0.3 nm. Model solutions mimicking healthy vitreous and AH were experimentally validated using a laboratory optical apparatus. Model-based estimates of scattering cross-sections of calibrated gold nanoparticles were found to be in good agreement with experimental measurements. Simulation results potentially can complement experimental data to quantitatively characterize vitreous opacities and distinguish between structures that significantly impact vision, such as those due to myopic vitreopathy and aging, from those that have little impact, like ABs. Such techniques to determine the structural significance of vitreous opacification would be very useful in selecting patients for surgery as well as evaluating the efficacy of

  14. 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

  15. Intercomparison of thermal and optical measurement methods for elemental carbon and black carbon at an urban location.

    PubMed

    Hitzenberger, R; Petzold, A; Bauer, H; Ctyroky, P; Pouresmaeil, P; Laskus, L; Puxbaum, H

    2006-10-15

    Despite intensive efforts during the past 20 years, no generally accepted standard method exists to measure black carbon (BC) or elemental carbon (EC). Data on BC and EC concentrations are method specific and can differ widely (e.g. Schmid et al., 2001, ten Brink et al., 2004). In this study, a comprehensive set of methods (both optical and thermal) is compared. Measurements were performed under urban background conditions in Vienna, Austria, a city heavily impacted by diesel emissions. Filter and impactor samples were taken during 3 weeks in summer 2002 and analyzed for EC with thermal methods: a modified Cachier method (Cachier et al., 1989), a thermal-optical method (Schmid et al., 2001), and the VDI method (VDI, 1996); for BC with optical methods: a filter transmission method and the integrating sphere method (Hitzenberger et al., 1996); and for total carbon (TC) with a combustion method (Puxbaum and Rendl, 1983). The online methods aethalometer (Hansen et al., 1984) and the multiangle absorption photometer MAAP (Petzold et al., 2002) to measure BC were also used. The average values of BC and EC obtained with the methods agreed within their standard deviations. A conversion table was set up to allow comparisons between data measured elsewhere under urban background conditions (with similar source characteristics) with different instruments. An approach to estimate the absorption coefficient from attenuation data is derived so that existing records of aethalometer data in urban environments may be used to obtain also the absorption coefficients.

  16. 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.

  17. Influence of pre-annealing on the thermal regeneration of fiber Bragg gratings in standard optical fibers.

    PubMed

    Holmberg, Patrik; Laurell, Fredrik; Fokine, Michael

    2015-10-19

    A detailed study of the dynamics during thermal regeneration of fiber Bragg gratings, written in hydrogen-loaded standard single-mode fibers using a ns pulsed 213 nm UV laser, is reported. Isothermal pre-annealing performed in the range 85 °C to 1100 °C, with subsequent grating regeneration at 1100 °C, resulted in a maximum refractive index modulation, Δn(m) ~1.4⋅10(-4), for gratings pre-annealed near 900 °C while a minimum value of Δn(m) ~2⋅10(-5) was achieved irrespective of pre-annealing temperature. This optimum denote an inflection point between opposing thermally triggered processes, which we ascribe to the reaction-diffusion mechanism of molecular water and hydroxyl species in silica. The results shed new light on the mechanisms underlying thermal grating regeneration in optical fibers. PMID:26480412

  18. 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.

  19. Thermal and optical characterization of liquid crystal 4‧-hexyl-4-biphenylcarbonitrile/4-hexylbenzoic acid mixtures

    NASA Astrophysics Data System (ADS)

    Okumuş, Mustafa; Özgan, Şükrü; Kırık, İhsan; Kerli, Süleyman

    2016-09-01

    We present the thermal and optical properties of binary mixtures formed from hydrogen-bonded liquid crystal 4-hexylbenzoic acid (6BA) and 4-hexyl-4‧-biphenylcarbonitrile (6CB) mesogens. Phase transition temperatures and enthalpy values are evaluated by differential scanning calorimetry (DSC) and phases identified by polarized optic microscopy (POM). The experimental results obviously show that the 6BA/6CB binary mixtures exhibit nematic and smectic phases. The most interesting result is that although the smectic phase is not observed in pure components 6BA and 6CB, it is observed in their some binary mixtures. The thermal properties like phase peak temperatures, enthalpy changes and thermal span of binary mixtures are affected by depending on the mixture ratio. The nematic range increase in the binary mixture compared to the individual mesogen, and also the phase transition temperature values and the nematic thermal stability factor increase as heating rate increases. Furthermore, the calculated activation energy values show that the reorientation of the molecules during the phase transitions of the mixture occurs on an orderly basis.

  20. 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. PMID:27389820

  1. Study of spectral characteristics of radiation from a thermal wake of a pulsating optical discharge in a supersonic air flow

    NASA Astrophysics Data System (ADS)

    Malov, A. N.; Orishich, A. M.; Terent'eva, Ya S.

    2015-10-01

    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 CO2 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.

  2. 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.

  3. 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.

  4. Structural, optical, opto-thermal and thermal properties of ZnS-PVA nanofluids synthesized through a radiolytic approach.

    PubMed

    Kharazmi, Alireza; Faraji, Nastaran; Mat Hussin, Roslina; Saion, Elias; Yunus, W Mahmood Mat; Behzad, Kasra

    2015-01-01

    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

  5. Structural, optical, opto-thermal and thermal properties of ZnS-PVA nanofluids synthesized through a radiolytic approach.

    PubMed

    Kharazmi, Alireza; Faraji, Nastaran; Mat Hussin, Roslina; Saion, Elias; Yunus, W Mahmood Mat; Behzad, Kasra

    2015-01-01

    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.

  6. 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

  7. Investigation on growth, structural, optical, thermal, dielectric and mechanical properties of organic L-prolinium trichloroacetate single crystals

    SciTech Connect

    Boopathi, K.; Rajesh, P.; Ramasamy, P.

    2012-09-15

    Graphical abstract: L-Prolinium trichloroacetate is an organic nonlinear optical crystal has been grown from the aqueous solution by slow evaporation solution growth technique. Single crystal X-ray diffraction analysis reveals that L-PTCA crystallizes in trigonal crystal system. The optical band gab is found to be 4.26 eV. Second harmonic conversion efficiency of L-PTCA has been found to be half that of KDP. Highlights: ► It deals with the synthesis, growth and characterization of L-PTCA an organic NLO crystal. ► Wide optical transparency window between 260 nm and 1100 nm. ► Thermal study reveals that the grown crystal is stable up to 127 °C. ► L-PTCA crystal exhibits the second order nonlinear optical properties. -- Abstract: A new organic nonlinear optical material L-prolinium trichloroacetate (L-PTCA) single crystal has been synthesized and grown by slow solvent evaporation technique at room temperature using water as solvent. Single-crystal X-ray diffractometer was utilized to measure unit cell parameters and to confirm lattice parameter. The powder X-ray diffraction pattern of the grown L-PTCA has been indexed. The modes of vibration of different molecular groups present in the sample were identified by the FTIR spectral analysis. The optical transmittance window and the lower cutoff wavelength of the L-PTCA have been identified by UV–vis–NIR studies. Thermal stability of the L-prolinium trichloroacetate was determined by TGA/DTA measurements. Dielectric measurements were carried out at various temperatures at frequency range 10–1 MHz. The mechanical properties of the grown crystals have been analyzed by Vickers microhardness method. The chemical etching studies were carried out on the grown crystals. Its SHG efficiency has been tested by Kurtz powder method.

  8. Brown carbon and thermal-optical analysis: A correction based on optical multi-wavelength apportionment of atmospheric aerosols

    NASA Astrophysics Data System (ADS)

    Massabò, D.; Caponi, L.; Bove, M. C.; Prati, P.

    2016-01-01

    Thermo-optical analysis is widely adopted for the quantitative determination of total, TC, organic, OC and elemental, EC, Carbon in aerosol samples collected on quartz fibre filters. Nevertheless, the methodology presents several issues in particular about the artefacts related to the formation of pyrolytic carbon. It is usually neglected the uncertainty due to the possible presence of brown carbon (BrC) in the sample under analysis, i.e. the optically active fraction of OC produced by biomass burning and with characteristics intermediate between OC and EC. We introduce here a novel correction to the standard thermo-optical protocol based on the determination of the fraction of the sample absorbance due to the (possible) presence of BrC. This is achievable thanks to the coupled use of the Multi Wavelength Absorbance Analyser (MWAA) of the University of Genoa and a standard Sunset Inc. EC/OC analyser. Our correction provides a firmer OC/EC separation as well as an operative quantification of the BrC mass. The methodology has been validated against independent determination of the levoglucosan content in the same filters sent to the Sunset analysis. Corrections up to 23% in the OC and EC values, determined via the standard and new thermo-optical analysis, have been found in a set of PM10 (i.e. Particulate Matter with aerodynamic diameter less than 10 μm) samples collected wintertime at a mountain site in Northern Italy.

  9. 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.

  10. 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.

  11. Optical cell with periodic resistive heating for the measurement of heat, mass, and thermal diffusions in liquid mixtures.

    PubMed

    Hartung, M; Köhler, W

    2007-08-01

    A new technique for the measurement of heat, mass, and thermal diffusions in liquids has been developed. Similar to laser induced dynamic gratings, a temperature grating is created in the sample. Thermal expansion transforms the temperature into a refractive-index grating, which is read by diffraction of a readout laser beam. In a multicomponent mixture an additional concentration grating is formed by thermal diffusion driven by the temperature gradients of the temperature grating. Differently to laser induced dynamic grating experiments we use Joule heating instead of optical heating. For that purpose we have built cuvettes which have a grating of transparent conducting strips on the inner side of one of their windows. If heated by an electric current a temperature grating will build up in the sample. Both the heat equation and the extended diffusion equation have been solved in two dimensions to allow for quantitative data analysis. Our apparatus and method of analysis have been validated by measurements of heat, mass, and thermal diffusions in pure and binary liquids. Heat diffusion can be correctly determined as was shown for pure toluene, pure dodecane, and the symmetric mixture of isobutylbenzene dodecane. Mass and thermal diffusions were studied in the three symmetric mixtures of dodecane, isobutylbenzene, and tetralin. The obtained diffusion and Soret coefficients agree with the literature values within the experimental errors. Uncompensated transient heating effects limit the resolution of the experimental technique.

  12. 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.

  13. 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.

  14. 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.

  15. "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.

  16. 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

  17. Estimation of soil moisture using optical/thermal infrared remote sensing in the Canadian Prairies

    NASA Astrophysics Data System (ADS)

    Rahimzadeh-Bajgiran, Parinaz; Berg, Aaron A.; Champagne, Catherine; Omasa, Kenji

    2013-09-01

    A new approach to estimate soil moisture (SM) based on evaporative fraction (EF) retrieved from optical/thermal infrared MODIS data is presented for Canadian Prairies in parts of Saskatchewan and Alberta. An EF model using the remotely sensed land surface temperature (Ts)/vegetation index concept was modified by incorporating North American Regional Reanalysis (NAAR) Ta data and used for SM estimation. Two different combinations of temperature and vegetation fraction using the difference between Ts from MODIS Aqua and Terra images and Ta from NARR data (Ts-Ta Aqua-day and Ts-Ta Terra-day, respectively) were proposed and the results were compared with those obtained from a previously improved model (ΔTs Aqua-DayNight) as a reference. For the estimation of SM from EF, two empirical models were tested and discussed to find the most appropriate model for converting MODIS-derived EF data to SM values. Estimated SM values were then correlated with in situ SM measurements and their relationships were statistically analyzed. Results indicated statistically significant correlations between SM estimated from all three EF estimation approaches and field measured SM values (R2 = 0.42-0.77, p values < 0.04) exhibiting the possibility to estimate SM from remotely sensed EF models. The proposed Ts-Ta MODIS Aqua-day and Terra-day approaches resulted in better estimations of SM (on average higher R2 values and similar RMSEs) as compared with the ΔTs reference approach indicating that the concept of incorporating NARR Ta data into Ts/Vegetation index model improved soil moisture estimation accuracy based on evaporative fraction. The accuracies of the predictions were found to be considerably better for intermediate SM values (from 12 to 22 vol/vol%) with square errors averaging below 11 (vol/vol%)2. This indicates that the model needs further improvements to account for extreme soil moisture conditions. The findings of this research can be potentially used to downscale SM

  18. Optic phonon bandwidth and lattice thermal conductivity: The case of L i2X (X =O , S, Se, Te)

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, S.; Lindsay, L.; Parker, D. S.

    2016-06-01

    We examine the lattice thermal conductivities (κl) of L i2X (X =O ,S ,Se ,Te ) using a first-principles Peierls-Boltzmann transport methodology. We find low κl values ranging between 12 and 30 W m-1K-1 despite light Li atoms, a large mass difference between constituent atoms, and tightly bunched acoustic branches, all features that give high κl in other materials including BeSe (630 W m-1K-1 ), BeTe (370 W m-1K-1 ), and cubic BAs (3170 W m-1K-1 ). Together these results suggest a missing ingredient in the basic guidelines commonly used to understand and predict κl. Unlike typical simple systems (e.g., Si, GaAs, SiC), the dominant resistance to heat-carrying acoustic phonons in L i2Se and L i2Te comes from interactions of these modes with two optic phonons. These interactions require significant bandwidth and dispersion of the optic branches, both present in L i2X materials. 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.

  19. 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

  20. Growth, spectral, optical, thermal, surface analysis and third order nonlinear optical properties of an organic single crystal: 1-(2-Methyl-6-nitro-4-phenyl-3-quinolyl) ethanone

    NASA Astrophysics Data System (ADS)

    Nirosha, M.; Kalainathan, S.; Sarveswari, S.; Vijayakumar, V.; Srikanth, A.

    2015-02-01

    Single crystal of 1-(2-Methyl-6-nitro-4-phenyl-3-quinolyl) ethanone was grown using slow evaporation solution growth technique. Single crystal X-ray diffraction study reveals the lattice parameters of the grown crystal. The modes of vibration of different molecular groups present in 2M6NQE were identified by FTIR spectral analysis. Its optical behavior was examined through UV-vis-NIR absorption and PL emission spectrum. They signify that the crystal has transparency in the region between 383 and 1100 nm. The PL spectrum of the title compound shows green emission in the crystal. From the thermal analysis, 2M6NQE has found to be thermally stable up to 263 °C, and the melting point of the material is 170 °C. The estimations of third order non-linear optical properties like non-linear absorption coefficient (β), non-linear refractive index (n2) and susceptibility [χ(3)] were calculated using Z-scan technique. It has observed that, crystal exhibits reverse saturation absorption and self-defocusing performance. Etching study was carried out for the grown crystal using different solvents.

  1. Long term structural health monitoring by Brillouin fibre-optic sensing: a real case

    NASA Astrophysics Data System (ADS)

    Minardo, Aldo; Persichetti, Gianluca; Testa, Genni; Zeni, Luigi; Bernini, Romeo

    2012-08-01

    We report the results of a long term structural health monitoring (SHM) test campaign performed on a concrete bridge. A one-year test campaign was performed by a portable prototype instrument based on stimulated Brillouin scattering in a single-mode optical fibre. The optical fibre sensor was attached along one arch of the bridge using two types of adhesive for comparison purposes. The attached fibre was able to provide the strain distribution along the structure during the one-year test campaign, with a spatial resolution of 1 m. A crack was revealed and correctly localized by the distributed sensor.

  2. Optical fiber based sensing system design for the health monitoring of multi-layered pavement structure

    NASA Astrophysics Data System (ADS)

    Liu, Wanqiu; Wang, Huaping; Zhou, Zhi; Li, Shiyu; Ni, Yuanbao; Wang, Geng

    2011-11-01

    This paper introduces an optical fiber based sensing system design for multi-layered pavement structural health monitoring. The co-line and integration design of FBG (Fiber Bragg Gating) sensors and BOTDR (Brillouin Optical Time Domain Reflectometry) sensors will ensure the large scale damage monitoring and local high accurate strain measurement. The function of pavement structure multi-scale shape measurement will provide real time subgrade settlement and rutting information. The sensor packaging methodology and strain transfer problem of the system will also be discussed in this paper. Primary lab tests prove the potential and feasibility of the practical application of the sensing system.

  3. Growth, crystalline perfection, optical, thermal, laser damage threshold and electrical characterization of melaminium levulinate monohydrate single crystal

    NASA Astrophysics Data System (ADS)

    Sivakumar, N.; Kanagathara, N.; Bhagavannarayana, G.; Kalainathan, S.; Anbalagan, G.

    2015-09-01

    Equimolar amounts of melamine and levulinic acid results an organic crystal of melaminium levulinate monohydrate (MLM) at room temperature. MLM belongs to a monoclinic crystal structure having P21/c space group which was confirmed by single crystal X-ray diffraction study. Functional groups present in the MLM crystal were identified by FT-IR spectral study. HRXRD study dictates the quality of MLM crystal. UV-visble spectrum of MLM reveals the lower cut-off wavelength of 293 nm with 55% optical transparency and optical band gap was found to be 4.20 eV for the prominent plane (1 0 -1). Refractive indices for the three axes of MLM crystal were found to be nx=2.6, ny=2.4 and nz=2.2 respectively. Further the thermal stability and melting point of MLM crystal were investigated by TG/DTA study. Dielectric permittivity tensor components were estimated for the planes (1 0 -1), (0 1 0) and (1 1 1) respectively. The thermal conductivity of the crystal by Wiedemann-Franz law was found to be 5.99×10-11 W/mK at 70 °C. LDT value (2.84 GW/cm2) of MLM was estimated for laser optical device applications.

  4. 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.

  5. 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.

  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. First-principles calculations of the structural, electronic, optical and thermal properties of the BNxAs1-x alloys

    NASA Astrophysics Data System (ADS)

    Hamioud, L.; Boumaza, A.; Touam, S.; Meradji, H.; Ghemid, S.; El Haj Hassan, F.; Khenata, R.; Omran, S. Bin

    2016-06-01

    The present paper aims to study the structural, electronic, optical and thermal properties of the boron nitride (BN) and BAs bulk materials as well as the BNxAs1-x ternary alloys by employing the full-potential-linearised augmented plane wave method within the density functional theory. The structural properties are determined using the Wu-Cohen generalised gradient approximation that is based on the optimisation of the total energy. For band structure calculations, both the Wu-Cohen generalised gradient approximation and the modified Becke-Johnson of the exchange-correlation energy and potential, respectively, are used. We investigated the effect of composition on the lattice constants, bulk modulus and band gap. Deviations of the lattice constants and the bulk modulus from the Vegard's law and the linear concentration dependence, respectively, were observed for the alloys where this result allows us to explain some specific behaviours in the electronic properties of the alloys. For the optical properties, the calculated refractive indices and the optical dielectric constants were found to vary nonlinearly with the N composition. Finally, the thermal effect on some of the macroscopic properties was predicted using the quasi-harmonic Debye model in which the lattice vibrations are taken into account.

  8. COMPONENTS AND PARAMETERS OF LASER SYSTEMS: Thermal depolarization of optical radiation in a laser active element made of GSGG:Cr3+:Nd3+ crystal

    NASA Astrophysics Data System (ADS)

    Danilov, A. A.; Nikol'skiĭ, M. Yu; Shcherbakov, Ivan A.

    1987-08-01

    Investigations were made of the thermal depolarization in a gadolinium scandium gallium garnet (GSGG) crystal doped with neodymium and chromium. It was found that at average optical pump powers higher than 250-300 W, inhomogeneities of the active medium make a substantial contribution to the thermal depolarization. A method is proposed for the control of the thermal depolarization by additional heating of the active element.

  9. Analytical thermal-optic model for laser heating of biological tissue using the hyperbolic heat transfer equation.

    PubMed

    Trujillo, Macarena; Rivera, María J; López Molina, Juan A; Berjano, Enrique J

    2009-09-01

    In this paper, we solve in an analytical way the thermal-optic coupled problem associated with a 1D model of non-perfused homogeneous biological tissue irradiated by a laser beam. We consider a laser pulse duration of 200 micros and study the temperatures of areas very close to the point of laser beam application. We consider that these values of the temporal and spatial variables mean that the problem has to be solved by means of the hyperbolic heat conduction model instead of the classic or parabolic model. We therefore obtain the solution using both models and apply the temperature profiles obtained to a specific biological tissue for comparison. Finally, we theoretically study the effect of the thermal relaxation time on the temperature profiles in the tissue for both heating and cooling phases (i.e. during and after laser application).

  10. Growth, structural, optical, thermal and laser damage threshold studies of an organic single crystal: 1,3,5 - triphenylbenzene (TPB)

    NASA Astrophysics Data System (ADS)

    Raja, R. Subramaniyan; Babu, G. Anandha; Ramasamy, P.

    2016-05-01

    Good quality single crystals of pure hydrocarbon 1,3,5-Triphenylbenzene (TPB) have been successfully grown using toluene as a solvent using controlled slow cooling solution growth technique. TPB crystallizes in orthorhombic structure with the space group Pna21. The structural perfection of the grown crystal has been analysed by high resolution X-ray diffraction measurements. The range and percentage of the optical transmission are ascertained by recording the UV-vis spectrum. Thermo gravimetric analysis (TGA) and differential thermal analysis (DTA) were used to study its thermal properties. Powder second harmonic generation studies were carried out to explore its NLO properties. Laser damage threshold value has been determined using Nd:YAG laser operating at 1064 nm.

  11. 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.

  12. 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

  13. 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.

  14. Structural, optical, thermal, mechanical and dielectric studies of Sulfamic acid single crystals: An influence of dysprosium (Dy3+) doping

    NASA Astrophysics Data System (ADS)

    Singh, Budhendra; Shkir, Mohd.; AlFaify, S.; Kaushal, Ajay; Nasani, Narendar; Bdikin, Igor; Shoukry, H.; Yahia, I. S.; Algarni, H.

    2016-09-01

    Sulfamic acid is a potential material that exhibits excellent optical properties. A good quality, pure and dysprosium (Dy3+) doped (2.5 and 5 mol %) Sulfamic acid (SA) single crystals were grown successfully by slow cooling method. Structural study revealed a slight change in its lattice parameters and volume, suggesting the successful incorporation of Dy3+ in crystal system. The existence of dysprosium in the system was also confirmed. Presence of various vibrational modes was confirmed. Optical transparency was found to have a significant effect with variation in the doping concentration. Furthermore, a marked enhancement in its mechanical parameters with doping was also identified by nanoindentation technique. Etching study was also performed on the grown crystals to study the etch-pit formation and growth mechanism. Effect of doping on the thermal stability was analysed. All the results were compared and discussed in detail to get insight of the effect of doping concentration on Sulfamic acid crystal.

  15. Optical and thermal properties of phosphors based on lead-silicate glass for high-power white LEDs

    NASA Astrophysics Data System (ADS)

    Shvaleva, M. A.; Tuzova, Yu. V.; Romanov, A. E.; Aseev, V. A.; Nikonorov, N. V.; Mynbaev, K. D.; Bugrov, V. E.

    2015-11-01

    A study is reported of the properties of a new phosphor material based on a highly refractive leadsilicate glass and microparticles of yttrium-aluminum garnet doped with cerium ions (YAG: Ce3+). The mass percentage fraction of YAG: Ce3+ microparticles in the material was varied from 50 to 90%. The optical properties of the phosphor were examined, as well as its thermal properties when used as a primary optical material in high-power light-emitting diode (LED) units. The results obtained reveal problems of excess heat removal from an LED structure, which appear on passing from phosphor binders based on silicone elastomers to glasses, and demonstrate that the phosphor developed in the study is promising for obtaining warm white light.

  16. 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.

  17. Coupled thermal/structural analyses of laser powered glass sealing methods for fiber optic and flat panel display applications

    SciTech Connect

    Chambers, R.S.; Gianoulakis, S.E.

    1996-12-31

    Glasses are used extensively by the electronics industry for packaging and in components. Because glasses have such low fracture toughness, glass components must maintain low tensile stresses to avoid cracking and ensure product stability. Modeling is a key tool for developing designs with low tensile stresses. Thermoelastic analyses are ideal for modeling slow, oven controlled processes where the temperature varies uniformly. Many processing environments, however, involve rapid heating and cooling cycles that produce nonhomogeneous temperature fields causing the volume and stresses in the glass to relax at different rates. This structural relaxation is an important nonlinear material behavior that gives rise to a point-to-point variability in effective properties of the material. To accurately model such stresses, a thermal analysis must be coupled to a structural analysis that employs a viscoelastic model of glass. Laser sealing of glasses is an example of a process where thermal history is an important factor in determining the residual stress state. Recent needs to consider laser sealing methods for fiber optic connectors and flat panel displays have spurred the development of coupled, three-dimensional thermal and structural finite element codes. Analyses of the temperatures and stresses generated in a flat panel display during a laser sealing operation are presented, an the idiosyncrasies and importance of modeling coupled thermal/structural phenomena are discussed.

  18. 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.

  19. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Thermally induced optical damage to barium-sodium niobate crystals

    NASA Astrophysics Data System (ADS)

    Baryshev, S. A.; Goncharova, I. F.; Konvisar, P. G.; Kuznetsov, V. A.

    1990-06-01

    Thermally induced optical damage (TIOD) was observed in undoped barium-sodium niobate (BSN) crystals as a result of changes in their temperature. This damage was deduced from the behavior of YAG:Nd3+ laser radiation when a BSN crystal was inserted in the resonator and also using a helium-neon laser probe beam. The experimental results were satisfactorily explained by the familiar pyroelectric model of TIOD and, in the crystals studied, an inhomogeneity of the conductivity rather than an inhomogeneity of the pyroelectric constant played the main role.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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

    2015-01-01

    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

  5. 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.

  6. 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.

  7. Thermal design of retroreflective stray light fore-baffles for spaceborne optical systems

    NASA Astrophysics Data System (ADS)

    Schneider, Edward

    2001-03-01

    The use of stray light fore-baffles in space-borne optical systems solves the problem of protecting the optical system from unwanted radiation. However, this introduces the problem of adding a large area black cavity at the system entrance aperture, and this cavity will run hot due to capture of solar, planetary albedo, and planetary emission radiation. The optical system may need to be baffled by a cool shield to keep system absolute temperatures sufficiently low. Alternately, a reflecting baffle system can be used that retro-reflects the input environment radiation. This reduces absorbed heat loads by the baffle system and reduces system absolute temperature levels.

  8. 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.

  9. 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.

  10. Load tracking and structural health monitoring of unmanned aerial vehicles using optical fiber sensors

    NASA Astrophysics Data System (ADS)

    Handelman, A.; Botsev, Y.; Balter, J.; Gud's, P.; Kressel, I.; Tur, M.; Gali, S.; Pillai, A. C. R.; Hari Prasad, M.; Yadav, A. Kumar; Gupta, Nitesh; Sathya, Sakthi; Sundaram, Ramesh

    2011-08-01

    An airborne, high resolution, load tracking and structural health monitoring system for unmanned aerial vehicles is presented. The system is based on embedded optical fiber Bragg sensors interrogated in real time during flight at 2.5 kHz. By analyzing the recorded vibration signature it is now possible to identify and trace the dynamic response of an airborne structure and track its loads.

  11. Load tracking and structural health monitoring of unmanned aerial vehicles using optical fiber sensors

    NASA Astrophysics Data System (ADS)

    Handelman, A.; Botsev, Y.; Balter, J.; Gud'S, P.; Kressel, I.; Tur, M.; Gali, S.; Pillai, A. C. R.; Hari Prasad, M.; Yadav, A. Kumar; Gupta, Nitesh; Sathya, Sakthi; Sundaram, Ramesh

    2010-12-01

    An airborne, high resolution, load tracking and structural health monitoring system for unmanned aerial vehicles is presented. The system is based on embedded optical fiber Bragg sensors interrogated in real time during flight at 2.5 kHz. By analyzing the recorded vibration signature it is now possible to identify and trace the dynamic response of an airborne structure and track its loads.

  12. 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.

  13. 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. PMID:26560566

  14. 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. PMID:26696185

  15. Optical and mechanical mode tuning in an optomechanical crystal with light-induced thermal effects

    SciTech Connect

    Navarro-Urrios, D.; Gomis-Bresco, J.; Alzina, F.; Capuj, N. E.; Griol, A.; Puerto, D.; Martínez, A.; Sotomayor-Torres, C. M.

    2014-09-07

    We report on the modification of the optical and mechanical properties of a silicon 1D optomechanical crystal cavity due to thermo-optic effects in a high phonon/photon population regime. The cavity heats up due to light absorption in a way that shifts the optical modes towards longer wavelengths and the mechanical modes to lower frequencies. By combining the experimental optical results with finite-difference time-domain simulations, we establish a direct relation between the observed wavelength drift and the actual effective temperature increase of the cavity. By assuming that the Young's modulus decreases accordingly to the temperature increase, we find a good agreement between the mechanical mode drift predicted using a finite element method and the experimental one.

  16. Meeting current public health needs: optical biosensors for pathogen detection and analysis

    NASA Astrophysics Data System (ADS)

    Yang, Minghui; Sapsford, Kim E.; Sergeev, Nikolay; Sun, Steven; Rasooly, Avraham

    2009-02-01

    Pathogen detection and analysis is critical for medicine, food safety, agriculture, public health and biosecurity. Many current microbial detection approaches are based on century-old culturing methods which, while reliable, are slow, provide relatively little information about the pathogens and are not adaptable to high throughput operations. Optical biodetection represents a potential alternative. Most ELISA and chromatography systems are based on optical methods that are also used for analysis of molecular interactions, such as DNA hybridization and protein-protein interactions (e.g. microarrays or SPR biosensors). Various optical biosensor platforms have been developed that have many of the characteristics essential for modern pathogen molecular analysis including sensitivity, speed of analysis, multi-channel capability, relative simplicity and low cost. Here we provide several examples of the use of optical biosensor technology for pathogen detection and analysis including high throughput DNA microarray analysis, SPR-based rapid direct detection of bacterial toxins, CCD-based fluorescent activity analysis of microbial toxins and a simple ECL-based CCD detection system. However, while effective for molecular analysis, most of these technologies are not as sensitive as traditional culturing methods for detecting microorganisms. There is a need to combine optical biosensors with traditional methods to speed culture-based detection and to provide more information regarding the pathogens.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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

  3. 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. PMID:26426163

  4. 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.

  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. The IMPROVE_A temperature protocol for thermal/optical carbon analysis: maintaining consistency with a long-term database.

    PubMed

    Chow, Judith C; Watson, John G; Chen, L W Antony; Chang, M C Oliver; Robinson, Norman F; Trimble, Dana; Kohl, Steven

    2007-09-01

    Thermally derived carbon fractions including organic carbon (OC) and elemental carbon (EC) have been reported for the U.S. Interagency Monitoring of PROtected Visual Environments (IMPROVE) network since 1987 and have been found useful in source apportionment studies and to evaluate quartz-fiber filter adsorption of organic vapors. The IMPROVE_A temperature protocol defines temperature plateaus for thermally derived carbon fractions of 140 degrees C for OC1, 280 degrees C for OC2, 480 degrees C for OC3, and 580 degrees C for OC4 in a helium (He) carrier gas and 580 degrees C for EC1, 740 degrees C for EC2, and 840 degrees C for EC3 in a 98% He/2% oxygen (O2) carrier gas. These temperatures differ from those used previously because new hardware used for the IMPROVE thermal/optical reflectance (IMPROVE_TOR) protocol better represents the sample temperature than did the old hardware. A newly developed temperature calibration method demonstrates that these temperatures better represent sample temperatures in the older units used to quantify IMPROVE carbon fractions from 1987 through 2004. Only the thermal fractions are affected by changes in temperature. The OC and EC by TOR are insensitive to the change in temperature protocol, and therefore the long-term consistency of the IMPROVE database is conserved. A method to detect small quantities of O2 in the pure He carrier gas shows that O2 levels above 100 ppmv also affect the comparability of thermal carbon fractions but have little effect on the IMPROVE_TOR split between OC and EC.

  7. Decadal trends and common dynamics of the bio-optical and thermal characteristics of the African Great Lakes.

    PubMed

    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.

  8. Decadal trends and common dynamics of the bio-optical and thermal characteristics of the African Great Lakes.

    PubMed

    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. Effect of air annealing on structural, optical, morphological and electrical properties of thermally evaporated CdSe thin films

    NASA Astrophysics Data System (ADS)

    Purohit, A.; Chander, S.; Nehra, S. P.; Dhaka, M. S.

    2015-05-01

    In this paper, a study on effect of air annealing on structural, optical, morphological and electrical properties of CdSe thin films is undertaken. The thin films of thickness 810 nm were deposited on glass and ITO coated glass substrates employing thermal evaporation technique. The glass substrates were used to find structural, optical and morphological properties while ITO coated glass substrates for electrical properties. The as-deposited films were subjected to thermal annealing in air atmosphere at different temperatures 100 °C, 200 °C and 300 °C. The X-ray diffraction pattern shows that the films have cubic phase with preferred orientation (111). The structural parameters like inter-planner spacing, lattice constant, grain size, dislocation density, strain and number of crystallites per unit area are calculated. The grain size is found in the range 27.11-34.03 nm and observed to be varied with air annealing. The dislocation density and strain vary with annealing in the range (0.86-1.36)×1011 cm-2 and 0.276-0.347 respectively. The extinction coefficient is found to be increased at lower annealing temperature and decreased at higher. The refractive index is also calculated and found in the range 2.75-2.80. The AFM studies show that roughness of thin films are increased with annealing. The electrical resistivity is found to be decreased with annealing temperature. The results are in good agreement with the standard data and available literature.

  10. 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.

  11. 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.

  12. 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.

  13. Evapotranspiration Retrieval through Optical/Thermal Satellite Imagery and Ground Measurements in the Green River Basin, Wyoming

    NASA Astrophysics Data System (ADS)

    Pradhan, N.; Hendrickx, J. M.; Ogden, F. L.; Wollf, S. W.

    2010-12-01

    Remote sensing methods are increasingly employed in combination with modeling for evapotranspiration estimation because they can provide multi-temporal, spatially-distributed estimates of key variables based on spatially distributed measurements. The approach for estimating evapotranspiration with remotely sensed data couples thermal and optical remote sensing with energy balance models such as: SEBAL, Surface Energy Balance Algorithms for Land, and METRICtm, Mapping Evapotranspiration at high Resolution using Internalized Calibration. The objective of this study is to investigate how ground measurements and satellite imagery at different scales can be combined to retrieve actual evapotranspiration over large watersheds. Scales of ground measurements are: (1) point scale that is typical for regular meteorological measurements such as air temperature, relative humidity, solar radiation, and wind speed; (2) footprint scale that varies from about 5,000 m2 for eddy-covariance measurements of sensible and latent heat fluxes to about 5,000,000 m2 for scintillometer sensible heat flux measurements when optical/thermal Landsat and MODIS satellites pass over around 10 am. In our analysis, we focused on evapotranspiration or consumptive use associated with irrigated agriculture in the Green River Basin in Wyoming that is the main headwater tributary of the entire Colorado River Basin. Ground-based meteorological stations, eddy-covariance and large-aperture scintillometers were set up in Pinedale, Green River basin, Wyoming to conduct the research. METRIC is used to retrieve evapotranspiration estimates from Landsat5 (30-120 m resolution) and MODIS (250-1000 m resolution) imagery.

  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. Synthesis and optical properties of a crosslinkable polymer system containing TCF and TCP chromophores with excellent electro-optic activity and thermal stability

    NASA Astrophysics Data System (ADS)

    Chen, Zhuo; Bo, Shuhui; Zhen, Zhen; Liu, Xinhou

    2012-10-01

    Crosslinkable polymer with side-chain system was investigated to increase the content of NLO chromophores and improve the stability of oriented chromophores. In this work, a series of crosslinkable copolymers which beared different concentrations of chromophores with the tricyanofurane (TCF) acceptor and a kind of crosslinkable copolymers beared chromophores with dendritic tricyanopyrroline (TCP) acceptor were successfully synthesized and characterized. The crosslinked EO polymers which beared chromophores with the tricyanofurane (TCF) acceptor revealed the highest EO coefficient (r33) of 47.0 pm/V at 1310 nm, which was similar with the r33 of uncrosslinked systems. Compared to the uncrosslinked EO polymer systems, the crosslinked ones exhibited significantly enhanced temporal stability. Keywords: Nonlinear optics; Crosslinkable system; Chromophore-containing copolymers; Side-chain; Crosslinking reaction; Thermally stable polymer

  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. The composition effect on the thermal and optical properties across CdZnTe crystals

    NASA Astrophysics Data System (ADS)

    Strzałkowski, K.

    2016-11-01

    Cd1‑x Zn x Te mixed crystals investigated in this work were grown from the melt using the vertical Bridgman–Stockbarger method in the whole range of composition 0  <  x  <  1 that is from one binary crystal (CdTe) to another (ZnTe). The real composition of grown crystals was measured with the SEM/EDS method along the growth axis. The segregation coefficient of Zn in a CdTe matrix has been evaluated as being close to unity. The energy gap as a function of the composition was determined from transmission spectroscopy. Thanks to that, the bowing parameter of this ternary alloy was found to be 0.458. In this work the systematical study of thermal properties of Cd1‑x Zn x Te alloys from one binary crystal (CdTe) to another (ZnTe) grown by the vertical Bridgman technique were undertaken for the first time. The thermal diffusivity and effusivity of the investigated crystals were derived from the experimental data and allowed the thermal conductivity to be calculated. Diagrams of the thermal conductivity versus composition were analyzed applying the model for mixed semiconducting crystals given by Sadao Adachi. Thanks to that, the contribution of the thermal resistivity arising from the lattice disorder to the total resistivity of the crystal has been determined.

  18. Depth profiling the optical absorption and thermal reflection coefficient via an analysis based on the method of images (abstract)

    NASA Astrophysics Data System (ADS)

    Power, J. F.

    2003-01-01

    The problem of depth profiling optical absorption in a thermally depth variable solid is a problem of direct interest for the analysis of complex structured materials. In this work, we introduce a new algorithm to solve this problem in a planar layered sample which is impulse irradiated. The sample is comprised of "N" model layers of thickness Δx, of constant diffusivity α, where the conductivity varies depth wise with each layer. This derivation extends to the general case of a depth variable thermal reflection coefficient with depth variable optical source density. In such a sample, at finite time, t, past excitation, thermal energy can only significantly penetrate NL model layers NL≈√4αt[-ln(ɛ)] /2Δx, where ɛ is a small error (ɛ⩽10-6) and a double transit through each layer is assumed. The depth profile of optical absorption in each layer, i, is approximated by δ(x-iΔx), weighted by the optical source density Si. The temperature at x=0- just inside a front medium contacting the sample is given by T(x=0,t)= ∑ i=12NL SiṡGR(x,x0=iΔx,t)]x=0, where GR(x,x0,t) represents an effective Green's function for optical absorption at the depth x0=iΔx in the sample. The method of images1 gives GR(x,x0=iΔx,t) in the following form: [GR(x,0Δx,t)GR(x,2Δx,t)…GR(x,2NLΔx,t)]=[A10A12 A14 A16 …..A1,2NL0A32A34 A36 …..A3,2NL….0……A2NL-1,2NL][G(x-0Δx,t)G(x-2Δx,t)……G(x-2NLΔx,t)]. The G(x-nΔx,t) are shifted image fields obtained from the infinite domain Green's function for one-dimensional heat conduction. They account for thermal wave reflection/transmission over the path length nΔx from the source (at interface i) to the surface (x=0). The Ain are lumped coefficients giving the efficiency of heat transmission from the ith source to the surface for each path order n. They are determined by a mapping procedure that identifies all propagation paths of each order, n, and computes the individual and lumped reflection coefficients. Equation (2) is

  19. 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.

  20. 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.

  1. 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.

  2. Thermal annealing induced structural and optical properties of Se72Te25In3 thin films

    NASA Astrophysics Data System (ADS)

    Pathak, H. P.; Shukla, Nitesh; Kumar, Vipin; Dwivedi, D. K.

    2016-05-01

    Thin films of a- Se72Te25In3 were prepared by vacuum evaporation technique in a base pressure of 10-6 Torr on to well cleaned glass substrate. a-Se72Te25In3 thin films were annealed at different temperatures below their crystallization temperatures for 2h. The structural analysis of the films has been investigated using X-ray diffraction technique. The optical absorption spectra of these films were measured in the wavelength range 400-1100 nm in order to derive the absorption coefficient of these films. The optical band gap of as prepared and annealed films as a function of photon energy has been studied. It has been found that the optical band gap decreases with increasing annealing temperatures in the present system.

  3. 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

  4. 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.

  5. Solvation and thermal effects on the optical properties of naturaldyes: a case study on the flavylium cyanin

    NASA Astrophysics Data System (ADS)

    Calzolari, Arrigo; Malcioglu, Baris; Gebauer, Ralph; Varsano, Daniele; Baroni, Stefano

    2011-03-01

    We present a first-principles study of the effects of both hydration and thermal dynamics on the optical properties of a natural anthocyanin dye, namely, cyanin (Cya), in aqueous solution. We combine Car-Parrinello molecular dynamics and time-dependent density functional theory (TDDFT) approaches to simulate the time evolution of UV-vis spectrum of the hydrated Cya molecule at room temperature [2,3]. The spectrum of the dye calculated in the gas phase is characterized by two peaks in the red and in the blue, which would bring about a greenish hue incompatible with the dark purple coloration 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 molecular distortions, induced by thermal fluctuations.

  6. Diffusion, thermalization, and optical pumping of YbF molecules in a cold buffer-gas cell

    NASA Astrophysics Data System (ADS)

    Skoff, S. M.; Hendricks, R. J.; Sinclair, C. D. J.; Hudson, J. J.; Segal, D. M.; Sauer, B. E.; Hinds, E. A.; Tarbutt, M. R.

    2011-02-01

    We produce YbF molecules with a density of 1018 m-3 using laser ablation inside a cryogenically cooled cell filled with a helium buffer gas. Using absorption imaging and absorption spectroscopy we study the formation, diffusion, thermalization, and optical pumping of the molecules. The absorption images show an initial rapid expansion of molecules away from the ablation target followed by a much slower diffusion to the cell walls. We study how the time constant for diffusion depends on the helium density and temperature and obtain values for the YbF-He diffusion cross section at two different temperatures. We measure the translational and rotational temperatures of the molecules as a function of time since formation, obtain the characteristic time constant for the molecules to thermalize with the cell walls, and elucidate the process responsible for limiting this thermalization rate. Finally, we make a detailed study of how the absorption of the probe laser saturates as its intensity increases, showing that the saturation intensity is proportional to the helium density. We use this to estimate collision rates and the density of molecules in the cell.

  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. 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.

  9. Studies on the synthesis, spectral, optical and thermal properties of l-Valine Zinc Sulphate: an organic inorganic hybrid nonlinear optical crystal.

    PubMed

    Puhal Raj, A; Ramachandra Raja, C

    2012-11-01

    Nonlinear optical (NLO) organic inorganic hybrid l-Valine Zinc Sulphate (LVZS) was synthesized and single crystals were obtained from saturated aqueous solution by slow evaporation method at 36°C using a constant temperature bath (CTB) with an accuracy of ±0.01°C. This crystal is reported with its characterization by single crystal and powder XRD, FTIR, UV-Vis-NIR, TG/DTA analysis and SHG test. Single crystal XRD study reveals that LVZS crystallizes in monoclinic system with the lattice constants a=9.969(3) Å, b=7.238(3) Å, c=24.334(9) Å and cell volume is 1736.00Å(3). Sharp peaks observed in powder X-ray diffraction studies confirm the high degree of crystallinity of grown crystal. The incorporation of sulphate ion with l-valine is confirmed by FTIR spectrum in LVZS crystal(.) A remarkable increase in optical transparency has been observed in LVZS when compared to l-valine and zinc sulphate heptahydrate Thermal properties of LVZS have been reported by using TG/DTA analysis. Kurtz powder second harmonic generation (SHG) test confirms NLO property of the crystal and SHG efficiency of LVZS was found to be 1.34 times more than pure l-valine.

  10. Application of photothermal probe beam deflection technique for the high-sensitive characterization of optical thin films with respect to their optical, thermal, and thermoelastic inhomgeneities

    NASA Astrophysics Data System (ADS)

    Welsch, Eberhard; Ettrich, K.; Peters, M.; Blaschke, Holger; Ziegler, W.; Bodemann, Axel; Reichling, Michael

    1994-11-01

    Two-dimensional cw photothermal surface displacement (PTD) scans with high spatial resolution provide a new quality for thin-film characterization. This is demonstrated for optical single-layer films of MgF2 and for 248 nm high-reflecting Al2O3/SiO2 multilayer coatings. Inhomogeneities of the films were detected with a lateral resolution better than 2 micrometers . Photothermal images reveal that Al2O3/SiO2 coatings with low damage thresholds differ above all in the amplitude of the PTD background signal whereas high-damage-threshold-coatings excel in a noticeable decrease in defect concentration. On the other hand, pulsed thermal MIRAGE technique is shown to be capable to yield complementary information with respect to the subdamage behavior as well as the onset of UV damage in Al2O3/SiO2 laser mirrors. Thus, the physical origin of the UV radiation breakdown in optical thin films can be elucidated.

  11. Studies on the synthesis, spectral, optical and thermal properties of L-Valine Zinc Sulphate: An organic inorganic hybrid nonlinear optical crystal

    NASA Astrophysics Data System (ADS)

    Puhal Raj, A.; Ramachandra Raja, C.

    2012-11-01

    Nonlinear optical (NLO) organic inorganic hybrid L-Valine Zinc Sulphate (LVZS) was synthesized and single crystals were obtained from saturated aqueous solution by slow evaporation method at 36 °C using a constant temperature bath (CTB) with an accuracy of ±0.01 °C. This crystal is reported with its characterization by single crystal and powder XRD, FTIR, UV-Vis-NIR, TG/DTA analysis and SHG test. Single crystal XRD study reveals that LVZS crystallizes in monoclinic system with the lattice constants a = 9.969(3) Å, b = 7.238(3) Å, c = 24.334(9) Å and cell volume is 1736.00 Å3. Sharp peaks observed in powder X-ray diffraction studies confirm the high degree of crystallinity of grown crystal. The incorporation of sulphate ion with L-valine is confirmed by FTIR spectrum in LVZS crystal. A remarkable increase in optical transparency has been observed in LVZS when compared to L-valine and zinc sulphate heptahydrate Thermal properties of LVZS have been reported by using TG/DTA analysis. Kurtz powder second harmonic generation (SHG) test confirms NLO property of the crystal and SHG efficiency of LVZS was found to be 1.34 times more than pure L-valine.

  12. Optical backscatter method for determining thermal denaturation of β-lactoglobulin and other whey proteins in milk.

    PubMed

    Lamb, Alisa; Payne, Fred; Xiong, Youling L; Castillo, Manuel

    2013-03-01

    The heat denaturation of whey proteins affects the functional properties of milk. Correlations of β-lactoglobulin (β-LG) denaturation to gelation time, gel firmness, and gel moisture content have been widely documented. Currently, no technique is available for quantifying β-LG denaturation in milk without altering its native composition or requiring a laborious procedure. The goal of this study was to establish if an optical backscatter response of whey protein denaturation during milk heat treatment could be determined that would be the basis for an inline optical measurement technology. The experimental design consisted of 1 factor (time at 80°C) and 6 levels (0, 3, 5, 7, 12, and 25 min). Physicochemical analysis performed indicated that β-LG denaturation followed a first-order response during thermal treatment. The light backscatter response, measured as a ratio of two 25-nm wave bands (832.5 nm/382.5 nm), significantly correlated to β-LG denaturation and had a 14% increase for milk with 75% β-LG denaturation. The strength of the optical response at the proposed wave bands and their correlation to denaturation suggests that light backscatter could potentially be used to measure β-LG and other whey protein denaturation inline.

  13. 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.

  14. Electronic, optical and thermal properties of TiCr2 and TiMn2 by ab initio simulations

    NASA Astrophysics Data System (ADS)

    Ali, M. S.; Roknuzzaman, M.; Parvin, R.; Islam, A. K. M. A.; Ostrikov, K.

    2015-10-01

    A theoretical study of TiX2 (X = Cr, Mn) with C14 Laves phase compounds has been performed by using the first-principles pseudopotential plane-wave method within the generalized gradient approximation (GGA). The electronic properties (Fermi surface and charge density) have been calculated and analyzed. The optical characteristics (dielectric functions, absorption spectrum, conductivity, energy-loss spectrum and reflectivity) are calculated and discussed. The calculated large positive static dielectric constant indicates good dielectric properties. The reflectivity of TiX2 (X = Cr, Mn) is high in the IR-Visible-UV region up to ˜13 eV showing promise as a good solar heating barrier material. The temperature and pressure dependence of bulk modulus, Debye temperature, specific heats and thermal expansion coefficient are obtained for T = 1200 K and P = 50 GPa through quasi-harmonic Debye model with phononic effects. Fermi surface, optical and thermodynamic properties are very important for practical applications of the materials in optical and other devices.

  15. 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.

  16. Thermal-optical analysis for the measurement of elemental carbon (EC) and organic carbon (OC) in ambient air a literature review

    NASA Astrophysics Data System (ADS)

    Karanasiou, A.; Minguillón, M. C.; Viana, M.; Alastuey, A.; Putaud, J.-P.; Maenhaut, W.; Panteliadis, P.; Močnik, G.; Favez, O.; Kuhlbusch, T. A. J.

    2015-09-01

    Thermal-optical analysis is currently under consideration by the European standardization body (CEN) as the reference method to quantitatively determine organic carbon (OC) and elemental carbon (EC) in ambient air. This paper presents an overview of the critical parameters related to the thermal-optical analysis including thermal protocols, critical factors and interferences of the methods examined, method inter-comparisons, inter-laboratory exercises, biases and artifacts, and reference materials. The most commonly used thermal protocols include NIOSH-like, IMPROVEA and EUSAAR2 protocols either with light transmittance or reflectance correction for charring. All thermal evolution protocols are comparable for total carbon (TC) concentrations but the results vary significantly concerning OC and especially EC concentrations. Thermal protocols with a rather low peak temperature in the inert mode like IMPROVEA and EUSAAR2 tend to classify more carbon as EC compared to NIOSH-like protocols, while charring correction based on transmittance usually leads to smaller EC values compared to reflectance. The difference between reflectance and transmittance correction tends to be larger than the difference between different thermal protocols. Nevertheless, thermal protocols seem to correlate better when reflectance is used as charring correction method. The difference between EC values as determined by the different protocols is not only dependent on the optical pyrolysis correction method, but also on the chemical properties of the samples due to different contributions from various sources. The overall conclusion from this literature review is that it is not possible to identify the "best" thermal-optical protocol based on literature data only, although differences attributed to the methods have been quantified when possible.

  17. 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.

  18. 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.

  19. Optical Resonance Shifts in the Fluorescence of Thermal and Cold Atomic Gases.

    PubMed

    Jenkins, S D; Ruostekoski, J; Javanainen, J; Bourgain, R; Jennewein, S; Sortais, Y R P; Browaeys, A

    2016-05-01

    We show that the resonance shifts in the fluorescence of a cold gas of rubidium atoms substantially differ from those of thermal atomic ensembles that obey the standard continuous medium electrodynamics. The analysis is based on large-scale microscopic numerical simulations and experimental measurements of the resonance shifts in a steady-state response in light propagation. PMID:27203321

  20. Distributed fiber-optic sensing system with OFDR and its applications to structural health monitoring

    NASA Astrophysics Data System (ADS)

    Murayama, H.; Kageyama, K.; Uzawa, K.; Igawa, H.; Omichi, K.; Machijima, Y.

    2009-07-01

    In the field of fiber-optic sensing technology, distributed sensors that return a value of the measurand as a function of linear position along an optical fiber are regarded as a promising sensor which can be applied to structural health monitoring (SHM). We have developed a distributed strain sensing technique using long gauge fiber Bragg grating (FBG) based on optical frequency domain reflectometry (OFDR). FBGs functioning as mirrors with wavelengthselective reflectivity have been used as strain or temperature sensors. OFDR is a technique designed to measure backreflections from optical fiber networks and components. In our system, we use a longer gauge FBG whose length is ordinarily more than 100 mm and we can measure strain at an arbitrary position along the FBG. Therefore, we can obtain continuous strain data along the FBG. Furthermore, since the spatial resolution in strain measurements is less than 1 mm, it enables us to measure the strain distribution of stress concentrated area, such as welded and bonded joints, precisely. In this paper, we describe the principle of the distributed sensing technique based on OFDR and the applications to strain monitoring of a bonded joint and a wing box structure.

  1. Annealing effects on InGaAsN/GaAs quantum wells analyzed using thermally detected optical absorption and ten band k -p calculations

    NASA Astrophysics Data System (ADS)

    Bouragba, T.; Mihailovic, M.; Reveret, F.; Disseix, P.; Leymarie, J.; Vasson, A.; Damilano, B.; Hugues, M.; Massies, J.; Duboz, J. Y.

    2007-04-01

    The effects of thermal annealing for In0.25Ga0.75As1-yNy/GaAs multiquantum wells (MQWs) have been investigated through thermally detected optical absorption. The QW transition energies have been calculated by using a ten-band k -p model including the band anticrossing model for the description of the InGaAsN band gap variation. The modification of the In concentration profile due to In-Ga interdiffusion during thermal annealing is taken into account through the Fick law. A good agreement is obtained between calculated and experimental energies of optical transitions. Our results show that the In-Ga interdiffusion phenomenon observed in a nitrogen free sample is moderately enhanced by the introduction of nitrogen. The blueshift of optical transitions induced by the annealing process is the result of both In-Ga interdiffusion and rearrangement of local nitrogen environment.

  2. 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.

  3. Minimally invasive non-thermal laser technology using laser-induced optical breakdown for skin rejuvenation.

    PubMed

    Habbema, Louis; Verhagen, Rieko; Van Hal, Robbert; Liu, Yan; Varghese, Babu

    2012-02-01

    We describe a novel, minimally invasive laser technology for skin rejuvenation by creating isolated microscopic lesions within tissue below the epidermis using laser induced optical breakdown. Using an in-house built prototype device, tightly focused near-infrared laser pulses are used to create optical breakdown in the dermis while leaving the epidermis intact, resulting in lesions due to cavitation and plasma explosion. This stimulates a healing response and consequently skin remodelling, resulting in skin rejuvenation effects. Analysis of ex-vivo and in-vivo treated human skin samples successfully demonstrated the safety and effectiveness of the microscopic lesion creation inside the dermis. Treatments led to mild side effects that can be controlled by small optimizations of the optical skin contact and treatment depth within the skin. The histological results from a limited panel test performed on five test volunteers show evidence of microscopic lesion creation and new collagen formation at the sites of the optical breakdown. This potentially introduces a safe, breakthrough treatment procedure for skin rejuvenation without damaging the epidermis with no or little social down-time and with efficacy comparable to conventional fractional ablative techniques.

  4. 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

  5. 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

  6. A comparison of thermal infrared to fiber-optic distributed temperature sensing for evaluation of groundwater discharge to surface water

    NASA Astrophysics Data System (ADS)

    Hare, D. K.; Briggs, M. A.; Rosenberry, D. O.; Boutt, D. F.; Lane, J. W., Jr.

    2015-12-01

    Groundwater has a predictable thermal signature that can be used to locate discrete zones of discharge to surface water. These inputs are important for numerous reasons, including habitat stability, refuge for thermally stressed-aquatic species, and focused contaminant or nutrient loading from aquifers. However, because detection and quantification at the appropriate scale can be difficult, many discrete areas of groundwater discharge are not identified. This study compares two increasingly common heat tracing methods that rely on either direct-contact measurements or remote sensing: fiber-optic distributed temperature sensing (FO-DTS) and thermal infrared (TIR). FO-DTS is used to make high spatial resolution thermal measurements through time within the water column using temperature-sensitive cables. These cables can range up to several kilometers long, and can be wrapped for higher spatial resolution (cm). The personnel requirements, and time to install and georeference the cables can be burdensome, and the control units need constant calibration. In contrast, TIR data collection, either from handheld, airborne, or satellite platforms, can quickly capture point-in-time evaluations of groundwater seepage zones across large scales. However the remote TIR measurements are adversely influenced by a number of environmental and physical factors, and the measurements are limited to the surface "skin" temperature of water features. We present case studies from a range of lentic to lotic aquatic systems to identify guidelines regarding the effectiveness of FO-DTS and TIR for evaluating groundwater discharge. FO-DTS performs well in all systems across seasons, but data collection was limited spatially by practical considerations. TIR is found to consistently locate groundwater seepage zones above and along the stream bank, but in summer submerged seepage zones are only well identified in <0.5 m depth systems with moderate flow.

  7. 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.

  8. Investigation of Thermal Effects of Photocoagulation on Retinal Tissue Using Fine-Motion-Sensitive Dynamic Optical Coherence Tomography.

    PubMed

    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

  9. An all fiber-optic multi-parameter structure health monitoring system.

    PubMed

    Hu, Chennan; Yu, Zhihao; Wang, Anbo

    2016-09-01

    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.

  10. An all fiber-optic multi-parameter structure health monitoring system.

    PubMed

    Hu, Chennan; Yu, Zhihao; Wang, Anbo

    2016-09-01

    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. PMID:27607635

  11. Health monitoring of full composite CNG tanks using long-gauge fiber optic sensors

    NASA Astrophysics Data System (ADS)

    Glisic, Branko; Inaudi, Daniele

    2004-07-01

    The Compressed Natural Gas (CNG) used as a carburant in automotive industry offers low cost and notably less pollution. Full composite tank used to store the CNG onboard features low weight and extended lifespan. However, the safety issues and maintenance fees remain a challenge for its use in ordinary cars. The structural health monitoring of tanks with accent to damage detection can significantly increase the safety and decrease the maintenance fees. Structural health monitoring and damage detection of composite tanks impose important challenges to the monitoring strategy and monitoring system to be used. The issues of non-intrusive installation of sensors, their topologies and network, and particularly analysis and interpretation of resulting data are very complex. The long-gage interferometric sensors of SOFO type, for direct embedding in the full composite tank during production are developed. The sensor consists of single mode optical fiber embedded into the very thin composite tape. Such packaging offers to optical fiber excellent protection during handling and embedding and makes sensor non-intrusive to the tank material. Appropriate topologies of the sensors are combined in single sensor network used to monitor strain state and damage. The results of monitoring are analyzed at several levels, and the damage is detected using algorithms combining the global deformation and changes in both the tank stiffness and sensors cross-correlation. The monitoring strategy, sensors used in full composite tank monitoring, installation issues and the results of the structural health monitoring performed in laboratory are presented in details in this paper.

  12. 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.

  13. 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.

  14. The study of the thermal annealing of the Bragg gratings induced in the hydrogenated birefringent optical fiber with an elliptical stress cladding

    NASA Astrophysics Data System (ADS)

    Munko, A. S.; Varzhel', S. V.; Arkhipov, S. V.; Gribaev, A. I.; Konnov, K. A.; Belikin, M. N.

    2016-08-01

    In this work the comparative results on the dynamics of fiber Bragg gratings inscription in both the conventional and the subjected to hydrogenation birefringent optical fiber with elliptical stress cladding as well as in the same type of lightguide with the increased GeO2 concentration are presented. Also the research on the thermal impact on the fiber Bragg gratings written in the birefringent fiber with elliptical stress cladding has been carried out. The dependences of the fiber Bragg reflectance coefficient on the time of the thermal impact, obtained by annealing of the refractive index gratings, induced in the optical fibers with increased photorefractivity, are shown.

  15. 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.

  16. SEMICONDUCTOR DEVICES Thermal analysis of the cavity facet for an 808 nm semiconductor laser by using near-field scanning optical microscopy

    NASA Astrophysics Data System (ADS)

    Lan, Rao; Guofeng, Song; Lianghui, Chen

    2010-10-01

    In order to analyze the thermal characteristics of the cavity facet of a semiconductor laser, a home-built near-field scanning optical microscopy (NSOM) is employed to probe the topography of the facet. By comparing the topographic images of two samples under different DC current injections, we can find that the thermal characteristic is related to its lifetime. We show that it is possible to predict the lifetime of the semiconductor laser diode with non-destructive tests.

  17. Direct synthesis and characterization of optically transparent conformal zinc oxide nanocrystalline thin films by rapid thermal plasma CVD

    PubMed Central

    2011-01-01

    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. PMID:22040295

  18. Optical and thermal modeling of ultraviolet-LED array packaging for curing application

    NASA Astrophysics Data System (ADS)

    Liu, Hai; Tang, Zirong; Shi, Tielin; Liao, Guanglan; Nie, Lei

    2008-12-01

    High power Ultraviolet Light-Emitting Diode (UV-LED) is currently in high demand for a variety of applications including lighting, printing, and polymer curing, with its' advantages of durability, reliability, non-hazardous and safety. Recently, the technology of Semiconductor Light Matrix (SLM) by multiple individual LEDs mounted on panels was put forward to obtain higher power for curing application. However, the illumination uniformity of high power LED arrays still remains an issue. On the other hand, it has been also predicted previously that the lifetime of a device decays exponentially as the temperature increases. Therefore, the thermal management of high power LEDs is also a critical factor to the development of high-power UV-LED array light source. This paper presents our latest investigations of illumination uniformity and thermal management to satisfy the requirements of packaging UV-LED arrays for curing application.

  19. Thermal behavior of a high power generator exciter bridge measured by optical fiber sensors

    NASA Astrophysics Data System (ADS)

    Probst, Werner K.; Bortolotti, Fernando; de Morais Sousa, Kleiton; Kalinowski, Hypolito José; Martelli, Cicero; Cardozo da Silva, Jean Carlos

    2013-05-01

    This paper presents temperature measurements taken at a 3-phase thyristor rectifier bridge in a synchronous generator using fiber Bragg grating (FBG) sensors applied directly on the thyristors upper surface. The results show the thermal behavior of the thyristors during the generator's start-up-phase and the period of time after the synchronization, with regulating operations as reaction to different load conditions. The temperature analysis is supported by current, voltage and power values of the hydroelectric power plant monitoring system. The trend of curves describes the typical behavior of thyristors which is proven with a four term transient thermal model. The different heat effect a thyristor experiences inside the switching-cabinet are also discussed.

  20. 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.