WorldWideScience

Sample records for visible spectral range

  1. Airborne hyperspectral imaging in the visible-to-mid wave infrared spectral range by fusing three spectral sensors

    Science.gov (United States)

    Jakovels, Dainis; Filipovs, Jevgenijs; Erinš, Gatis; Taskovs, Juris

    2014-10-01

    Airborne hyperspectral imaging is widely used for remote sensing of environment. The choice of spectral region usually depends on the availability and cost of the sensor. Visible-to-near infrared (400-1100 nm) spectral range corresponds to spectral sensitivity of relatively cheap Si detectors therefore it is the most commonly used. The implementation of shortwave infrared (1100-3000 nm) requires more expensive solutions, but can provide valuable information about the composition of the substance. Mid wave infrared (3000-8000 nm) is rarely used for civilian applications, but it provides information on the thermal emission of materials. The fusion of different sensors allows spectral analysis of a wider spectral range combining and improving already existing algorithms for the analysis of chemical content and classification. Here we introduce our Airborne Surveillance and Environmental Monitoring System (ARSENAL) that was developed by fusing seven sensors. The first test results from the fusion of three hyperspectral imaging sensors in the visible-to-mid wave infrared (365-5000 nm) are demonstrated. Principal component analysis (PCA) is applied to test correlation between principal components (PCs) and common vegetation indices.

  2. Silicon nitride PhC nanocavities as versatile platform for visible spectral range devices

    Science.gov (United States)

    Pisanello, F.; Martiradonna, L.; Qualtieri, A.; Stomeo, T.; Grande, M.; Pompa, P. P.; Cingolani, R.; Bramati, A.; De Vittorio, M.

    2012-06-01

    We propose silicon nitride two-dimensional photonic crystal resonators as flexible platform to realize photonic devices based on spontaneous emission engineering of nanoemitters in the visible spectral range. The versatility of our approach is demonstrated by coupling the two dipole-like modes of a closed band gap H1 nanocavity with: (i) DNA strands marked with Cyanine 3 organic dyes, (ii) antibodies bounded to fluorescent proteins and (iii) colloidal semiconductor nanocrystals localized in the maximum of the resonant electric field. The experimental results are in good agreement with the numerical simulations, highlighting the good coupling of the nanocavities with both organic and inorganic light emitters.

  3. Continuous Spatial Tuning of Laser Emissions in a Full Visible Spectral Range

    Directory of Open Access Journals (Sweden)

    Mi-Yun Jeong

    2011-03-01

    Full Text Available In order to achieve a continuous tuning of laser emission, the authors designed and fabricated three types of cholesteric liquid crystal cells with pitch gradient, a wedge cell with positive slope, a wedge cell with negative slope, and a parallel cell. The length of the cholesteric liquid crystal pitch could be elongated up to 10 nm, allowing the lasing behavior of continuous or discontinuous spatial tuning determined by the boundary conditions of the cholesteric liquid crystal cell. In the wedge cell with positive slope, the authors demonstrated a continuous spatial laser tuning in the near full visible spectral range, with a tuning resolution less than 1 nm by pumping with only a single 355 nm laser beam. This continuous tuning behavior is due to the fact that the concentration of pitch gradient matches the fixed helical pitch determined by the cell thickness. This characteristic continuous spatial laser tuning could be confirmed again by pumping with a 532 nm laser beam, over 90 nm in the visible spectral range. The scheme of the spatial laser tuning in the wedge cell bearing a pitch gradient enabled a route to designing small-sized optical devices that allow for a wide tunability of single-mode laser emissions.

  4. Broadband black phosphorus optical modulator in visible to mid-infrared spectral range

    CERN Document Server

    Zhang, Rui; Yu, Haohai; Zhang, Huaijin; Yang, Ruinong; Yang, Bingchao; Liu, Zhongyuan; Wang, Jiyang

    2015-01-01

    Black phosphorous (BP), a two-dimensional (2D) material, has a direct bandgap, which fills up the bandgap lacuna left by graphene topological insulators and transition-metal dichalcogenides because of its dependence on the layers and applied strains. Theoretically, the direct and tunable band gap indicates the broadband applications in optoelectronics with high efficiencies in the spectral range from visible to mid-infrared. Here, a BP broadband optical modulator is experimentally constructed and the passively modulated lasers at 639 nm (red), 1.06 um (near-infrared) and 2.1 um (mid-infrared) are realized by using the BP optical modulator as the saturable absorber in bulk lasers. The obtained results provide a promising alternative for rare broadband optical modulators and broaden the application range of BP in photonics.

  5. Rare earth-transition metal compound-based MOSLM for the visible spectral range

    International Nuclear Information System (INIS)

    We have demonstrated a magneto-optical spatial light modulator in which functionality is realized by (i) heating up to Curie temperature (Tc) magneto-optical elements (pixels) with a semiconductor laser and (ii) application of a switching magnetic field. The pixels were made of films of amorphous rare earth-transition metal compounds (TbFe films with Tc=403 K and DyFe films with Tc=343 K) having good magneto-optical responses for wavelengths from the visible spectral range. We have found that the magnetization direction of pixels can be modulated with a laser radiation density of 5 mJ/cm2 and in a switching magnetic field of 15 Oe.

  6. Detector calibration in the spectral range from vacuum-ultraviolet to visible

    International Nuclear Information System (INIS)

    The Electrotechnical Laboratory is responsible for establishing optical units in Japan. Optical units are classified into photometric units which are weighted by human eye responsivity such as candela and radiometric units which are pure physical units such as watt. In this report, the overview of the techniques to determine the radiometric scales for detectors in the spectral region from ultraviolet to visible is described. The characteristics of semiconductor photodiodes as the primary standard detector and rare gas ionization chambers as another example of the primary standard detector are discussed. For characterizing the response of detectors, quantum efficiency or responsivity is used. The definitions of both are given. In order to realize a detector standard, the calibration with a primary standard detector the use of a primary standard radiation source and an efficiency-evaluated monochromatizing component, or the extension of spectral range of an existing detector standard by using a thermal detector is carried out. Noble gas ionization chambers as the primary standard detector in vacuum ultraviolet region, the self-calibration method, and semiconductor photodiodes as the absolute detector are described. (K.I.)

  7. Optical constants of liquid UO2 in the visible spectral range obtained from reflectivity measurements

    International Nuclear Information System (INIS)

    The optical constants, n,k, of liquid urania were determined from reflectivity measurements with plane-polarized light. Measurements were made with an integrating-sphere laser reflectometer in the wavelength range 450-750 nm at temperatures between 3000 and 4000 K. Consistent results have been obtained for different angles of incidence. The optical constants show little variation with the wavelength and temperature. Liquid urania proves to be opaque to radiation in the whole spectral range studied. Average values of n = 1.7 and k = 0.8 are given for the temperature range 3100-3600 K. From this result it is concluded that internal thermal radiation cannot cause a significant increase in thermal conductivity urania upon melting. (orig.)

  8. Blackbody-based calibration for temperature calculations in the visible and near-IR spectral ranges using a spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Shahla Keyvan; Rodney Rossow; Carlos Romero [University of Missouri-Columbia, Columbia, MO (United States). Department of Mechanical and Aerospace Engineering, Center for Artificial Intelligence in Engineering and Education

    2006-03-15

    This paper presents, the results of a method used to create a blackbody-based referenced calibration curve for a spectrometer in the visible and near-IR range. This method would allow the use of optical temperature measurements in high temperature furnaces when distance, environment, and emissivity effects are not accurately known. A probe containing a lens connected to a fiber-optic cable is inserted into a furnace and aimed toward a hot wall source. Spectral intensity data is fed back to a spectrometer and then to a monitoring computer. Initial data is taken along with another method to measure the source temperature, usually a thermocouple or IR-gun. The spectral data is compared to the blackbody intensities generated from the source temperature to create the calibration curve. This calibration curve is then used to correct intensities for temperature calculations using a spectrometer where furnace conditions are similar to those of the calibration data. This calibration method provides much more accurate temperature measurement results than the common practice of using a halogen reference. The results in the visible range compare favorably with those taken in the near-IR range under the same conditions. 17 refs., 7 figs.

  9. Evidence for graphene plasmons in the visible spectral range probed by molecules

    CERN Document Server

    Lange, Philipp; Severin, Nikolai; Benson, Oliver; Rabe, Jürgen P

    2014-01-01

    Graphene is considered to be plasmon active only up to the infrared based on combined tight binding model and random phase approximation calculations. Here we show that the optical properties of graphene as measured by ellipsometry and simulated by density functional theory imply the existence of strongly localized graphene plasmons in the visible with a line width of 0.1 eV. Using small emitters that provide the high wavevectors necessary to excite graphene plasmons at optical frequencies we demonstrate graphene plasmon induced excitation enhancement by nearly 3 orders of magnitude.

  10. Analysis of global water vapour trends from satellite measurements in the visible spectral range

    Directory of Open Access Journals (Sweden)

    S. Mieruch

    2008-02-01

    Full Text Available Global water vapour total column amounts have been retrieved from spectral data provided by the Global Ozone Monitoring Experiment (GOME flying on ERS-2, which was launched in April 1995, and the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY onboard ENVISAT launched in March 2002. For this purpose the Air Mass Corrected Differential Optical Absorption Spectroscopy (AMC-DOAS approach has been used. The combination of the data from both instruments provides us with a long-term global data set spanning more than 11 years with the potential of extension up to 2020 by GOME-2 data on MetOp.

    Using linear and non-linear methods from time series analysis and standard statistics the trends of H2O columns and their errors have been calculated. In this study, factors affecting the trend such as the length of the time series, the magnitude of the variability of the noise, and the autocorrelation of the noise are investigated. Special emphasis has been placed on the calculation of the statistical significance of the observed trends, which reveal significant local changes from ?5% per year to +5% per year. These significant trends are distributed over the whole globe. Increasing trends have been calculated for Greenland, East Europe, Siberia and Oceania, whereas decreasing trends have been observed for the northwest USA, Central America, Amazonia, Central Africa and the Arabian Peninsular.

  11. Asymmetric one-dimensional photonic crystal for optical sensing in the visible spectral range

    Science.gov (United States)

    Lalova, A.; Todorov, R.

    2014-05-01

    A gas sensor based on an asymmetric one-dimensional (1D) photonic band gap structure with one defect layer was designed and fabricated through layer-by-layer deposition of spin-coated poly methyl methacrylate (PMMA) and vacuum-deposited As2S3. Initially, the thickness variations, ?d, were determined of the thin films resulting from the poly methyl methacrylate exposure to chloroform vapor in the concentration range 100 - 9000 ppm. It was found that the value of ?d depends on the gas concentration and the exposure time. A two-layer structure was prepared consisting of PMMA and vacuum-deposited As2S3. Further, the permeability of thin As2S3 films to chloroform vapors was investigated. The asymmetric photonic structure consisted of 11 alternating layers of As2S3 and PMMA. The defect PMMA layer was located before the last high-refractive-index film of chalcogenide glass. The thickness of the defect layer of PMMA was pre-calculated so that the pass band be centered at the wavelength of 550 nm. An offset was observed of the position of the pass band to the larger wavelengths after exposure to chloroform vapor. The multilayered structure proposed is promising for optical sensor applications.

  12. Asymmetric one-dimensional photonic crystal for optical sensing in the visible spectral range

    International Nuclear Information System (INIS)

    A gas sensor based on an asymmetric one-dimensional (1D) photonic band gap structure with one defect layer was designed and fabricated through layer-by-layer deposition of spin-coated poly methyl methacrylate (PMMA) and vacuum-deposited As2S3. Initially, the thickness variations, Δd, were determined of the thin films resulting from the poly methyl methacrylate exposure to chloroform vapor in the concentration range 100 – 9000 ppm. It was found that the value of Δd depends on the gas concentration and the exposure time. A two-layer structure was prepared consisting of PMMA and vacuum-deposited As2S3. Further, the permeability of thin As2S3 films to chloroform vapors was investigated. The asymmetric photonic structure consisted of 11 alternating layers of As2S3 and PMMA. The defect PMMA layer was located before the last high-refractive-index film of chalcogenide glass. The thickness of the defect layer of PMMA was pre-calculated so that the pass band be centered at the wavelength of 550 nm. An offset was observed of the position of the pass band to the larger wavelengths after exposure to chloroform vapor. The multilayered structure proposed is promising for optical sensor applications.

  13. TiN/(Al,Sc)N metal/dielectric superlattices and multilayers as hyperbolic metamaterials in the visible spectral range

    Science.gov (United States)

    Saha, Bivas; Naik, Gururaj V.; Saber, Sammy; Akatay, Cem; Stach, Eric A.; Shalaev, Vladimir M.; Boltasseva, Alexandra; Sands, Timothy D.

    2014-09-01

    Hyperbolic metamaterials (HMMs) based on metal/dielectric multilayers have garnered attention in recent years due to their extraordinary optical properties emanating from hyperbolic dispersion of isofrequency surfaces. We have developed a new class of epitaxial metal/dielectric superlattice HMMs based on transition-metal nitrides—titanium nitride (TiN) and aluminum scandium nitride (AlxSc1-xN)—that could potentially lead to better HMM performance without requiring any traditional plasmonic materials such as gold (Au) and silver (Ag). Our results suggest that the TiN/(Al,Sc)N superlattices grown on (001) MgO substrates are nominally monocrystalline and pseudomorphic, exhibiting sharp interfaces with interface roughnesses of about one to two atomic layers. HMMs deposited on (0001) sapphire substrates grow in 111 orientation with local epitaxy inherent to individual grains, while on (001) Si substrates, the HMMs are polycrystalline. The HMM properties extracted with effective medium theory along with nonlocal field corrections indicate that the TiN/(Al,Sc)N superlattices grown on MgO substrates have both transverse negative (type-I) and transverse positive (type-II) hyperbolic dispersion of the isofrequency surfaces in the visible to near-IR spectral regions. The carrier concentration of TiN layers was varied deliberately by tuning the deposition conditions, thereby shifting the spectral range of both type-I and type-II HMM dispersions. The epitaxial thin-film-based HMMs developed here mark the beginning of a new generation of optical metamaterials with enhanced electromagnetic properties.

  14. The interaction of alcohol radicals with human hemoglobin. Pt. 1. Spectral properties of hemoglobin in the visible range

    International Nuclear Information System (INIS)

    Aqueous deoxyhemoglobin solutions (2 mg/ml) were gamma-irradiated by a 60Co source in the presence of methanol, ethanol, 1-butanol and t-butanol under N2O or argon. The effects of the interaction of the particular alcohol radical species with hemoglobin were determined according to the detected spectral alterations in the visible range. The amounts of stable final products in the form of methemoglobin (MetHb) and the sum of hemichromes and cholehemichromes (Hemichr) were estimated in irradiated preparations. For preparations irradiated under N2O, the radiation yield for MetHb formation was three-fold lower in the presence of ethanol and 1-butanol [G(MetHb) = 0.33[ compared with preparations irradiated in the presence of t-butanol or without alcohol [G(MetHb) = 1.00[. The yield of hemichromes and cholehemichromes in preparations irradiated under N2O increased in the order: ethanol (G = 0.38), 1-butanol (B = 0.52), t-butanol (G = 0.59), and in the absence of alcohol (G 0.72). The high effectivity of t-butanol radicals for iron oxidation and Hb destruction is apparently due to their oxidative properties, compared with the other radicals. It was also shown that ethanol radicals reduce MetHb 10 times more effectively [G(Fe(II)) = 2.5[ compared with t-butanol radicals [G(Fe(II)) = 0.24[. For samples irradiated under argon all the observed changes were similar, regardless of the presence of alcohols. This effect can be attributed to reconstruction reactions of Hb molecules in the presence of both oxidizing (OH or t-but.) and reducing agents (e-aq). The following sequence of effectivities of water radiolysis products and secondary alcohol radicals for hemoglobin destruction has been identified: meth., eth. ? 1-but. ? e-aq ? t-but. ? .OH. (orig.)

  15. Emission intensity in the visible and IR spectral ranges from Si-based structures formed by direct bonding with simultaneous doping with erbium (Er) and europium (Eu)

    Energy Technology Data Exchange (ETDEWEB)

    Mezdrogina, M. M., E-mail: margaret.m@mail.ioffe.ru; Kostina, L. S.; Beliakova, E. I.; Kuzmin, R. V. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)

    2013-09-15

    The photo- and electroluminescence spectra of silicon-based structures formed by direct bonding with simultaneous doping with rare-earth metals are studied. It is shown that emission in the visible and IR spectral ranges can be obtained from n-Si:Er/p-Si and n-Si:Eu/p-Si structures fabricated by the method suggested in the study. The results obtained make this method promising for the fabrication of optoelectronic devices.

  16. Enhanced optical transmission through a star-shaped bull's eye at dual resonant-bands in UV and the visible spectral range.

    Science.gov (United States)

    Nazari, Tavakol; Khazaeinezhad, Reza; Jung, Woohyun; Joo, Boram; Kong, Byung-Joo; Oh, Kyunghwan

    2015-07-13

    Dual resonant bands in UV and the visible range were simultaneously observed in the enhanced optical transmission (EOT) through star-shaped plasmonic structures. EOTs through four types of polygonal bull's eyes with a star aperture surrounded by the concentric star grooves were analyzed and compared for 3, 4, 5, and 6 corners, using finite difference time domain (FDTD) method. In contrast to plasmonic resonances in the visible range, the UV-band resonance intensity was found to scale with the number of corners, which is related with higher order multipole interactions. Spectral positions and relative intensities of the dual resonances were analyzed parametrically to find optimal conditions to maximize EOT in UV-visible dual bands. PMID:26191917

  17. Optical, spectral and phase-matching properties of BIBO, BBO and LBO crystals for optical parametric oscillation in the visible and near-infrared wavelength ranges

    Science.gov (United States)

    Akbari, R.; Major, A.

    2013-03-01

    The phase-matching properties of BIBO, BBO and LBO crystals for optical parametric oscillators (OPO) with wavelength tuning in the visible and near infrared spectral ranges were numerically investigated. The phase-matching configurations with a pump wavelength of 520 nm that provide the largest effective nonlinearity in each crystal were considered and compared. In addition, dispersive characteristics, including the group velocity mismatch and group velocity dispersion, which are of significant importance in femtosecond OPOs, were calculated. Finally, the attainable gain bandwidths for each crystal were estimated.

  18. Optical, spectral and phase-matching properties of BIBO, BBO and LBO crystals for optical parametric oscillation in the visible and near-infrared wavelength ranges

    International Nuclear Information System (INIS)

    The phase-matching properties of BIBO, BBO and LBO crystals for optical parametric oscillators (OPO) with wavelength tuning in the visible and near infrared spectral ranges were numerically investigated. The phase-matching configurations with a pump wavelength of 520 nm that provide the largest effective nonlinearity in each crystal were considered and compared. In addition, dispersive characteristics, including the group velocity mismatch and group velocity dispersion, which are of significant importance in femtosecond OPOs, were calculated. Finally, the attainable gain bandwidths for each crystal were estimated. (paper)

  19. Ion-induced effects in GEM and GEM/MHSP gaseous photomultipliers for the UV and the visible spectral range

    International Nuclear Information System (INIS)

    We report on the progress in the study of cascaded GEM and GEM/MHSP gas avalanche photomultipliers operating at atmospheric pressure, with CsI and bialkali photocathodes. They have single-photon sensitivity, ns time resolution and good localization properties. We summarize operational aspects and results, with the highlight of a high-gain stable gated operation of a visible-light device. Of particular importance are the results of a recent ion-backflow reduction study in different cascaded multipliers, affecting the detector's stability and the photocathode's lifetime. We report on the significant progress in ion-blocking and provide first results on bialkali-photocathode aging under gas multiplication

  20. Ion-induced effects in GEM & GEM/MHSP gaseous photomultipliers for the UV and the visible spectral range

    CERN Document Server

    Breskin, Amos; Lyashenko, A; Chechik, R; Amaro, F D; Maia, J M; Veloso, J F C; Dos Santos, J M F

    2005-01-01

    We report on the progress in the study of cascaded GEM and GEM/MHSP gas avalanche photomultipliers operating at atmospheric pressure, with CsI and bialkali photocathodes. They have single-photon sensitivity, ns time resolution and good localization properties. We summarize operational aspects and results, with the highlight of a high-gain stable gated operation of a visible-light device. Of particular importance are the results of a recent ion-backflow reduction study in different cascaded multipliers, affecting the detector's stability and the photocathode's liftime. We report on the significant progress in ion-blocking and provide first results on bialkali-photocathode aging under gas multiplication.

  1. Aerosol radiative effects in the ultraviolet, visible, and near-infrared spectral ranges using long-term aerosol data series over the Iberian Peninsula

    Directory of Open Access Journals (Sweden)

    D. Mateos

    2014-04-01

    Full Text Available A better understanding of the aerosol radiative properties is a crucial challenge for climate change studies. This study aims to provide a complete characterization of aerosol radiative effects in different spectral ranges within the shortwave (SW solar spectrum. For this purpose, long-term datasets of aerosol properties from six AERONET stations located in the Iberian Peninsula (Southwestern Europe are analyzed in term of climatology characterization and trends. Aerosol information is used as input to the libRadtran model in order to determine the aerosol radiative effect at the surface in the ultraviolet (AREUV, visible (AREVIS, near-infrared (ARENIR, and the entire SW range (ARESW under cloud-free conditions. Over the whole Iberian Peninsula, aerosol radiative effects in the different spectral ranges are: ?1.1 UV ?2, ?5.7 VIS ?2, ?2.8 NIR ?2, and ?9.5 SW ?2. The four variables showed positive statistically significant trends between 2004 and 2012, e.g., ARESW increased +3.6 W m?2 per decade. This fact is linked to the decrease in the aerosol load, which presents a trend of ?0.04 per unit of aerosol optical depth at 500 nm per decade, hence a reduction of aerosol effect on solar radiation at the surface is seen. Monthly means of ARE show a seasonal pattern with larger values in spring and summer. The aerosol forcing efficiency (AFE, ARE per unit of aerosol optical depth, is also evaluated in the four spectral ranges. AFE exhibits a dependence on single scattering albedo and a weaker one on Ångström exponent. AFE is larger (in absolute value for small and absorbing particles. The contributions of the UV, VIS, and NIR ranges to the SW efficiency vary with the aerosol types. Aerosol size determines the fractions of AFEVIS/AFESW and AFENIR/AFESW. VIS range is the dominant region for all types, although non-absorbing large particles cause a more equal contribution of VIS and NIR intervals. The AFEUV / AFESW ratio shows a higher contribution for absorbing fine particles.

  2. Spectral aerosol extinction (SpEx): a new instrument for in situ ambient aerosol extinction measurements across the UV/visible wavelength range

    Science.gov (United States)

    Jordan, C. E.; Anderson, B. E.; Beyersdorf, A. J.; Corr, C. A.; Dibb, J. E.; Greenslade, M. E.; Martin, R. F.; Moore, R. H.; Scheuer, E.; Shook, M. A.; Thornhill, K. L.; Troop, D.; Winstead, E. L.; Ziemba, L. D.

    2015-11-01

    We introduce a new instrument for the measurement of in situ ambient aerosol extinction over the 300-700 nm wavelength range, the spectral aerosol extinction (SpEx) instrument. This measurement capability is envisioned to complement existing in situ instrumentation, allowing for simultaneous measurement of the evolution of aerosol optical, chemical, and physical characteristics in the ambient environment. In this work, a detailed description of the instrument is provided along with characterization tests performed in the laboratory. Measured spectra of NO2 and polystyrene latex spheres (PSLs) agreed well with theoretical calculations. Good agreement was also found with simultaneous aerosol extinction measurements at 450, 530, and 630 nm using CAPS PMex instruments in a series of 22 tests including nonabsorbing compounds, dusts, soot, and black and brown carbon analogs. SpEx measurements are expected to help identify the presence of ambient brown carbon due to its 300 nm lower wavelength limit compared to measurements limited to longer UV and visible wavelengths. Extinction spectra obtained with SpEx contain more information than can be conveyed by a simple power law fit (typically represented by Ångström exponents). Planned future improvements aim to lower detection limits and ruggedize the instrument for mobile operation.

  3. Spectral Aerosol Extinction (SpEx: a new instrument for in situ ambient aerosol extinction measurements across the UV/visible wavelength range

    Directory of Open Access Journals (Sweden)

    C. E. Jordan

    2015-06-01

    Full Text Available We introduce a new instrument for the measurement of in situ ambient aerosol extinction over the 300–700 nm wavelength range, the Spectral Aerosol Extinction (SpEx instrument. This measurement capability is envisioned to complement existing in situ instrumentation, allowing for simultaneous measurement of the evolution of aerosol optical, chemical, and physical characteristics in the ambient environment. In this work, a detailed description of the instrument is provided along with characterization tests performed in the laboratory. Measured spectra of NO2 and polystyrene latex spheres (PSLs agreed well with theoretical calculations. Good agreement was also found with simultaneous aerosol extinction measurements at 450, 530, and 630 nm using CAPS PMex instruments in a series of 22 tests including non-absorbing compounds, dusts, soot, and black and brown carbon analogs. SpEx can more accurately distinguish the presence of brown carbon from other absorbing aerosol due to its 300 nm lower wavelength limit compared to measurements limited to visible wavelengths. Extinction spectra obtained with SpEx contain more information than can be conveyed by a simple power law fit (typically represented by Ångström Exponents. Planned future improvements aim to lower detection limits and ruggedize the instrument for mobile operation.

  4. An Impurity Emission Survey in the near UV and Visible Spectral Ranges of Electron Cyclotron Heated (ECH) Plasma in the TJ-II Stellarator

    Energy Technology Data Exchange (ETDEWEB)

    McCarthy, K. J.; Zurro, B.; Baciero, A.

    2001-07-01

    We report on a near-ultraviolet and visible spectroscopic survey (220-600 nm) of electron cyclotron resonance (ECR) heated plasmas created in the TJ-II stellarator, with central electron temperatures up to 2 keV and central electron densities up to 1.7 x 10 ''19 m''-3. Approximately 1200 lines from thirteen elements have been identified. The purpose of the work is to identify the principal impurities and spectral lines present in TJ-II plasmas, as well as their possible origin to search for transitions from highly ionised ions. This work will act as a base for identifying suitable transitions for following the evolution of impurities under different operating regimens and multiplet systems for line polarisation studies. It is intended to use the database creates as a spectral line reference for comparing spectra under different operating and plasma heating regimes. (Author)

  5. An Impurity Emission Survey in the near UV and Visible Spectral Ranges of Electron Cyclotron Heated (ECH) Plasma in the TJ-II Stellarator

    International Nuclear Information System (INIS)

    We report on a near-ultraviolet and visible spectroscopic survey (220-600 nm) of electron cyclotron resonance (ECR) heated plasmas created in the TJ-II stellarator, with central electron temperatures up to 2 keV and central electron densities up to 1.7 x 10 ''19 m''-3. Approximately 1200 lines from thirteen elements have been identified. The purpose of the work is to identify the principal impurities and spectral lines present in TJ-II plasmas, as well as their possible origin to search for transitions from highly ionised ions. This work will act as a base for identifying suitable transitions for following the evolution of impurities under different operating regimens and multiplet systems for line polarisation studies. It is intended to use the database creates as a spectral line reference for comparing spectra under different operating and plasma heating regimes. (Author)

  6. Temporal behavior of light-emission in the visible spectral range from a Ti-K{sub 2}CO{sub 3}-H cell

    Energy Technology Data Exchange (ETDEWEB)

    Mills, R.L. [BlackLight Power, Inc., Cranbury, NJ (United States)

    2001-04-01

    We report the generation of a hydrogen plasma and extreme ultraviolet emission as recorded via the hydrogen Balmer emission in the visible range. Typically, a hydrogen plasma is generated and the emission of extreme ultraviolet light from hydrogen gas is achieved via a discharge at high voltage, a high-power inductively coupled plasma, or a plasma created and heated to extreme temperatures by RF coupling (e.g. >10{sup 6} K) with confinement provided by a toroidal magnetic field. The observed plasma formed at low temperatures (e.g. {approx_equal} 10{sup 3} K) from atomic hydrogen generated at a tungsten filament that heated a titanium dissociator coated with potassium carbonate. The temporal behavior of the plasma was recorded via hydrogen Balmer {alpha} line emission when all power into the cell was terminated. A 2 s decay of the plasma was observed after a fast decay of the electric field to zero. The persistence of emission following the removal of all of the power to the cell indicates that a novel chemical power source is present that forms an energetic plasma in hydrogen. No unusual behavior was observed with the control sodium carbonate. (author)

  7. Electromagnetic cloaking in the visible frequency range

    CERN Document Server

    Smolyaninov, I I; Davis, C C

    2007-01-01

    Electromagnetic metamaterials provide unprecedented freedom and flexibility to introduce new devices, which control electromagnetic wave propagation in very unusual ways. Very recently theoretical design of an "invisibility cloak" has been suggested, which has been realized at microwave frequencies in a two-dimensional cylindrical geometry. In this communication we report on the experimental realization of the dielectric permittivity distribution required for non-magnetic cloaking in the visible frequency range.

  8. Analysis of visible spectral lines in LHD helium discharge

    International Nuclear Information System (INIS)

    In this study, visible spectral lines in LHD helium discharges are analyzed and it was found that they could be well fitted with gaussian profile. The results reveal a simple mechanism of helium atom recycling. Ion temperatures were also derived from the fitting. A typical value of the ion temperature obtained was about 6 eV. (author)

  9. Globally integrated measurements of the Earth's visible spectral albedo

    CERN Document Server

    Montanes-Rodriguez, P; Goode, P R; Hickey, J; Koonin, S E

    2005-01-01

    We report spectroscopic observations of the earthshine reflected from the Moon. By applying our photometry methodology to spectroscopy, we were able to precisely determine the Earth's reflectance, and its variation as a function of wavelength through a single night as the Earth rotates. These data imply that planned regular monitoring of earthshine spectra will yield valuable, new inputs for climate models, which would be complementary to those from the more standard broadband measurements of satellite platforms. The mean spectroscopic albedo over the visible is consistent with simultaneous broadband photometric measurements. We found no evidence for an appreciable "red" or "vegetation edge" in the Earth's spectral albedo, and no evidence for changes in this spectral region (700 -740 nm) over the 40 degrees of Earth's rotation covered by our observations.

  10. A Molecular Chameleon: Reversible pH- and Cation-Induced Control of the Optical Properties of Phthalocyanine-Based Complexes in the Visible and Near-Infrared Spectral Ranges.

    Science.gov (United States)

    Safonova, Evgeniya A; Martynov, Alexander G; Nefedov, Sergey E; Kirakosyan, Gayane A; Gorbunova, Yulia G; Tsivadze, Aslan Yu

    2016-03-01

    A series of novel nonperipherally substituted tetra-15-crown-5-dibutoxyoxanthrenocyanines (H2, Mg, Zn), acting as chameleons with the unique properties of switchable absorption and emission in the near-infrared (NIR) spectral range have been synthesized and characterized by X-ray diffraction. The attachment of 15-crown-5-?-dibutoxyoxanthreno moieties to phthalocyanine is responsible for the high solubility of the resulting molecules and the red shift of the Q band to the NIR region and offers a unique possibility for postsynthetic modification of the optical properties of the molecules. Both aggregation of phthalocyanine and its participation in an acid-base equilibrium strongly alter their optical properties. For example, the absorption of complexes can be reversibly tuned from 686 up to 1028 nm because of the cation-induced formation of supramolecular dimers or subsequent protonation of meso-N atoms orf macrocycle, in contrast to peripherally substituted tetra-15-crown-5-phthalocyanines without oxanthrene moieties. The reversibility of these processes can be controlled by the addition of [2.2.2]cryptand or amines. All investigated compounds exhibit fluorescence with moderate quantum yield, which can also be switched between the ON and OFF states by the action of similar agents. PMID:26910047

  11. Visible spectral imager for occultation and nightglow (VISION) for the PICASSO Mission

    Science.gov (United States)

    Saari, Heikki; Näsilä, Antti; Holmlund, Christer; Mannila, Rami; Näkki, Ismo; Ojanen, Harri J.; Fussen, Didier; Pieroux, Didier; Demoulin, Philippe; Dekemper, Emmanuel; Vanhellemont, Filip

    2015-10-01

    PICASSO - A PICo-satellite for Atmospheric and Space Science Observations is an ESA project led by the Belgian Institute for Space Aeronomy, in collaboration with VTT, Clyde Space Ltd. (UK), and the Centre Spatial de Liège (BE). VTT Technical Research Centre of Finland Ltd. will deliver the Visible Spectral Imager for Occultation and Nightglow (VISION) for the PICASSO mission. The VISION targets primarily the observation of the Earth's atmospheric limb during orbital Sun occultation. By assessing the radiation absorption in the Chappuis band for different tangent altitudes, the vertical profile of the ozone is retrieved. A secondary objective is to measure the deformation of the solar disk so that stratospheric and mesospheric temperature profiles are retrieved by inversion of the refractive raytracing problem. Finally, occasional full spectral observations of polar auroras are also foreseen. The VISION design realized with commercial of the shelf (CoTS) parts is described. The VISION instrument is small, lightweight (~500 g), Piezo-actuated Fabry-Perot Interferometer (PFPI) tunable spectral imager operating in the visible and near-infrared (430 - 800 nm). The spectral resolution over the whole wavelength range will be better than 10 nm @ FWHM. VISION has is 2.5° x 2.5° total field of view and it delivers maximum 2048 x 2048 pixel spectral images. The sun image size is around 0.5° i.e. ~500 pixels. To enable fast spectral data image acquisition VISION can be operated with programmable image sizes. VTT has previously developed PFPI tunable filter based AaSI Spectral Imager for the Aalto-1 Finnish CubeSat. In VISION the requirements of the spectral resolution and stability are tighter than in AaSI. Therefore the optimization of the of the PFPI gap control loop for the operating temperature range and vacuum conditions has to be improved. VISION optical, mechanical and electrical design is described.

  12. Brightness Control in Dynamic Range Constrained Visible Light OFDM Systems

    OpenAIRE

    Yu, Z; Baxley, R. J.; Zhou, G. T.

    2013-01-01

    Visible light communication (VLC) systems can provide illumination and communication simultaneously via light emitting diodes (LEDs). Orthogonal frequency division multiplexing (OFDM) waveforms transmitted in a VLC system will have high peak-to-average power ratios (PAPRs). Since the transmitting LED is dynamic-range limited, OFDM signal has to be scaled and biased to avoid nonlinear distortion. Brightness control is an essential feature for the illumination function. In thi...

  13. Measuring black carbon spectral extinction in the visible and infrared

    Science.gov (United States)

    Smith, A. J. A.; Peters, D. M.; McPheat, R.; Lukanihins, S.; Grainger, R. G.

    2015-09-01

    This work presents measurements of the spectral extinction of black carbon aerosol from 400 nm to 15 ?m. The aerosol was generated using a Miniature Combustion Aerosol Standard soot generator and then allowed to circulate in an aerosol cell where its extinction was measured using a grating spectrometer in the visible and a Fourier transform spectrometer in the infrared. Size distribution, number concentration, and mass extinction cross sections have also been obtained using single-particle aerosol samplers. A mean mass extinction cross section at 550 nm of 8.3 ± 1.6 m2 g-1 is found which, assuming a reasonable single scatter albedo of 0.2, corresponds to a mass absorption cross section of 6.6 ± 1.3 m2 g-1. This compares well with previously reported literature values. Computer analysis of electron microscope images of the particles provides independent confirmation of the size distribution as well as fractal parameters of the black carbon aerosol. The aerosol properties presented in this work are representative of very fresh, uncoated black carbon aerosol. After atmospheric processing of such aerosols (which could include mixing with other constituents and structural changes), different optical properties would be expected.

  14. HIGHLY SENSITIVE LASER SPECTROMETERS FOR NEAR INFRARED AND VISIBLE RANGES

    Directory of Open Access Journals (Sweden)

    A. S. Stasheuski

    2015-04-01

    Full Text Available Laser spectrometers for registration of luminescent signals with nanosecond temporal resolution are presented. The versatile spectrometer is capable to operate with up to tenth of nanometer resolution in wide spectral range. The specialized spectrometer for singlet oxygen luminescence measuring in vitro and in vivo possesses unique sensitivity in the near infrared region. Experimental results confirming high technical capacities of the setups are presented.

  15. The refractive index of human hemoglobin in the visible range

    International Nuclear Information System (INIS)

    Because the refractive index of hemoglobin in the visible range is sensitive to the hemoglobin concentration, optical investigations of hemoglobin are important for medical diagnostics and treatment. Direct measurements of the refractive index are, however, challenging; few such measurements have previously been reported, especially in a wide wavelength range. We directly measured the refractive index of human deoxygenated and oxygenated hemoglobin for nine wavelengths between 400 and 700 nm for the hemoglobin concentrations up to 140 g l-1. This paper analyzes the results and suggests a set of model functions to calculate the refractive index depending on the concentration. At all wavelengths, the measured values of the refractive index depended on the concentration linearly. Analyzing the slope of the lines, we determined the specific refraction increments, derived a set of model functions for the refractive index depending on the concentration, and compared our results with those available in the literature. Based on the model functions, we further calculated the refractive index at the physiological concentration within the erythrocytes of 320 g l-1. The results can be used to calculate the refractive index in the visible range for arbitrary concentrations provided that the refractive indices depend on the concentration linearly.

  16. The refractive index of human hemoglobin in the visible range

    Energy Technology Data Exchange (ETDEWEB)

    Zhernovaya, O; Tuchin, V [International Research-Educational Center of Optical Technologies for Industry and Medicine ' Photonics' , Saratov State University, 83 Astrakhanskaya str., 410012 Saratov (Russian Federation); Sydoruk, O [Optical and Semiconductor Devices Group, Department of Electrical and Electronic Engineering, South Kensington Campus, Imperial College London, London SW7 2AZ (United Kingdom); Douplik, A, E-mail: alexandre.douplik@aot.uni-erlangen.de [Medical Photonics Engineering Group, Chair of Photonic Technologies, Friedrich-Alexander University Erlangen-Nuremberg, Paul-Gordan-Strasse 3, 91052 Erlangen (Germany)

    2011-07-07

    Because the refractive index of hemoglobin in the visible range is sensitive to the hemoglobin concentration, optical investigations of hemoglobin are important for medical diagnostics and treatment. Direct measurements of the refractive index are, however, challenging; few such measurements have previously been reported, especially in a wide wavelength range. We directly measured the refractive index of human deoxygenated and oxygenated hemoglobin for nine wavelengths between 400 and 700 nm for the hemoglobin concentrations up to 140 g l{sup -1}. This paper analyzes the results and suggests a set of model functions to calculate the refractive index depending on the concentration. At all wavelengths, the measured values of the refractive index depended on the concentration linearly. Analyzing the slope of the lines, we determined the specific refraction increments, derived a set of model functions for the refractive index depending on the concentration, and compared our results with those available in the literature. Based on the model functions, we further calculated the refractive index at the physiological concentration within the erythrocytes of 320 g l{sup -1}. The results can be used to calculate the refractive index in the visible range for arbitrary concentrations provided that the refractive indices depend on the concentration linearly.

  17. A review of visible-range Fabry-Perot microspectrometers in silicon for the industry

    Science.gov (United States)

    Carmo, João Paulo; Rocha, Rui Pedro; Bartek, Marian; de Graaf, Ger; Wolffenbuttel, Reinoud F.; Correia, José Higino

    2012-10-01

    This review presents microspectrometers in silicon for the industry for measuring light in the visible range, using the Fabry-Perot interferometric technique. The microspectrometers are devices able to do the analysis of the individual spectral components in a given signal and are extensively used on spectroscopy. The analysis of the interaction between the matter and the radiated energy can found huge applications in the industrial sector. The microspectrometers can be divided on three types, determined by the dispersion element or the used approach and can be found microspectrometers based on prisms, gratings interferometers. Both types of microspectrometers can be used to analyze the spectral content ranging from the ultraviolet (UV, below 390 nm), passing into the visible region of the electromagnetic spectrum (VIS, 390-760 nm) up to the infrared (IR, above 760 nm). The microspectrometers in silicon are versatile microinstruments because silicon-compatible techniques can be used to assembly both the optical components with the readout and control electronics, thus resulting high-volume with high-reproducibility and low-cost batch fabrications. A compensation technique for minimizing the scattered light effects on interferometers was implemented and is also a contribution of this paper. Fabry-Perot microspectrometers for the visible range are discussed in depth for use in industrial applications.

  18. New fractal structures for frequencies close to the visible range

    DEFF Research Database (Denmark)

    Malureanu, Radu; Sandru, A.

    2011-01-01

    In this paper we present a new type of fractal resonator to be used in the red/NIR region of the spectra. The structure presents high-transmission band in 795-825nm range. The stop band is in the 683-731 nm range. Due to the huge difference in the spectra within such a short range, the structure can be used as an efficient sensor, both in transmission as well as in reflection. Thus, a variation of only 0.09 in the refraction index will for example change the structure’s behaviour from 90% reflection to 90% transmission. Such resonances lead to a sensitivity of 780 nm/RIU. Another advantage of this resonator is the independency of the incidence angle - in the spectral re-gion of interest; the incidence angle has very little influence over the response.

  19. Passive signatures concealed objects recorded by multispectral and hyperspectral systems in visible, infrared and terahertz range

    Science.gov (United States)

    Kastek, Mariusz; Kowalski, Marcin; Polakowski, Henryk; Lagueux, Philippe; Gagnon, Marc-André

    2014-06-01

    Risks to the safety of public zones (generally available for people) are related mainly to the presence of hidden dangerous objects (such as knives, guns, bombs etc.) and their usage. Modern system for the monitoring of such zones attempt to detect dangerous tools using multispectral cameras working in different spectral ranges: the visible radiation, near, medium and long range infrared and recently also in terahertz range. In order to develop methods and algorithms to detect hidden objects it is necessary to determine the thermal signatures of such objects of interest. The laboratory measurements were conducted to determine the thermal signatures of dangerous tools hidden under various clothes in different ambient conditions. Cameras used for measurements were working in spectral range 0.6-12.5 µm. An infrared imaging Fourier transform spectroradiometer was also used, working in spectral range 7.7-11.7 µm. Analysis of registered thermograms and hyperspectral datacubes has yielded the thermal signatures for: two types of guns, two types of knives and home-made explosive bombs. The determined thermal signatures will be used in the development of method and algorithms of image analysis implemented in proposed monitoring systems.

  20. Visible and Near Infrared Fluorescence Spectral Flow Cytometry

    OpenAIRE

    Nolan, John P.; Condello, Danilo; DUGGAN, ERIKA; Naivar, Mark; Novo, David

    2012-01-01

    There is a long standing interest in measuring complete emission spectra from individual cells in flow cytometry. We have developed flow cytometry instruments and analysis approaches to enable this to be done routinely and robustly. Our spectral flow cytometers use a holographic grating to disperse light from single cells onto a CCD for high speed, wavelength-resolved detection. Customized software allows the single cell spectral data to be displayed and analyzed to produce new spectra-derive...

  1. New horizons of optics of the midinfrared spectral range

    Science.gov (United States)

    Mitrofanov, A. V.; Sidorov-Biryukov, D. A.; Voronin, A. A.; Pugžlys, A.; Lanin, A. A.; Fedotov, A. B.; Panchenko, V. Ya.; Baltuška, A.; Zheltikov, A. M.

    2015-10-01

    Optical physics and laser technologies are rapidly moving in the direction of exploring the midinfrared spectral range. New methods of mid-IR ultrashort pulse generation allow forming very short flashes of electromagnetic radiation with record high peak power for this range. The first experiments conducted with such systems make possible implementing new regimes of laser-matter interaction and shed light on unusual properties of the nonlinear-optical response of materials in the mid-IR spectral range.

  2. A Wide Spectral Range Reflectance and Luminescence Imaging System

    Directory of Open Access Journals (Sweden)

    Tapani Hirvonen

    2013-10-01

    Full Text Available In this study, we introduce a wide spectral range (200–2500 nm imaging system with a 250 ?m minimum spatial resolution, which can be freely modified for a wide range of resolutions and measurement geometries. The system has been tested for reflectance and luminescence measurements, but can also be customized for transmittance measurements. This study includes the performance results of the developed system, as well as examples of spectral images. Discussion of the system relates it to existing systems and methods. The wide range spectral imaging system that has been developed is however highly customizable and has great potential in many practical applications.

  3. Evaluating Potential Spectral Impacts of Various Artificial Lights on Melatonin Suppression, Photosynthesis, and Star Visibility

    OpenAIRE

    Aubé, Martin; Roby, Johanne; Kocifaj, Miroslav

    2013-01-01

    Artificial light at night can be harmful to the environment, and interferes with fauna and flora, star visibility, and human health. To estimate the relative impact of a lighting device, its radiant power, angular photometry and detailed spectral power distribution have to be considered. In this paper we focus on the spectral power distribution. While specific spectral characteristics can be considered harmful during the night, they can be considered advantageous during the day. As an example...

  4. Investigation into the ways of tuning parametric oscillators of visible and IR ranges

    International Nuclear Information System (INIS)

    Different versions of optical parametric oscillator (OPO) schemes were experimentally realised and investigated, which utilise AgGaS2, LiNbO3 and HgGa2S4 single crystals as well as an Hg1-xCdxGa2S4 solid solution. The OPOs generate radiation in the 1.2-5.7-?m range and make use of different ways of output wavelength tuning, including fast wavelength tuning (in a time shorter than 0.1 ms) with the help of an acoustooptical deflector. The output spectral line was narrowed by means of an intracavity acoustooptical filter. An OPO for the visible range with an electrodynamic tuning to an arbitrary wavelength in this range in a time of 5ms was implemented employing a BBO single crystal. (invited paper)

  5. Precise Measurement of Lunar Spectral Irradiance at Visible Wavelengths.

    Science.gov (United States)

    Cramer, C E; Lykke, K R; Woodward, J T; Smith, A W

    2013-01-01

    We report a measurement of lunar spectral irradiance with an uncertainty below 1 % from 420 nm to 1000 nm. This measurement uncertainty meets the stability requirement for many climate data records derived from satellite images, including those for vegetation, aerosols, and snow and ice albedo. It therefore opens the possibility of using the Moon as a calibration standard to bridge gaps in satellite coverage and validate atmospheric retrieval algorithms. Our measurement technique also yields detailed information about the atmosphere at the measurement site, suggesting that lunar observations are a possible solution for aerosol monitoring during the polar winter and can provide nighttime measurements to complement aerosol data collected with sun photometers. Our measurement, made with a novel apparatus, is an order of magnitude more accurate than the previous state-of-the-art and has continuous spectral coverage, removing the need to interpolate between filter passbands. PMID:26401440

  6. Hyper-Spectral Imager in visible and near-infrared band for lunar compositional mapping

    Indian Academy of Sciences (India)

    A S Kiran Kumar; A Roy Chowdhury

    2005-12-01

    India ’s ?rst lunar mission,Chandrayaan-1,will have a Hyper-Spectral Imager in the visible and near-infrared spectral bands along with other instruments.The instrument will enable mineralogical mapping of the Moon ’s crust in a large number of spectral channels.The planned Hyper-Spectral Imager will be the ?rst instrument to map the lunar surface with the capability of resolving the spectral region,0.4 to 0.92 m in 64 continuous bands with a resolution of better than 15 nm and a spatial resolution of 80 m.Spectral separation will be done using a wedge ?lter and the image will be mapped onto an area detector.The detector output will be processed in the front-end processor to generate the 64-band data with 12-bit quantization.This paper gives a description of the Hyper-Spectral Imager instrument.

  7. Passive ranging of dynamic rocket plumes using infrared and visible oxygen attenuation

    Science.gov (United States)

    Vincent, R. Anthony; Hawks, Michael R.

    2011-05-01

    Atmospheric oxygen absorption bands in observed spectra of boost phase missiles can be used to accurately estimate range from sensor to target. One method is to compare observed values of band averaged absorption to radiative transfer models. This is most effective using bands where there is a single absorbing species. This work compares spectral attenuation of two oxygen absorption bands in the near-infrared (NIR) and visible (Vis) spectrum, centered at 762 nm and 690 nm, to passively determine range. Spectra were observed from a static test of a full-scale solid rocket motor at a 900m range. The NIR O2 band provided range estimates accurate to within 3%, while the Vis O2 band had a range error of 15%. A Falcon 9 rocket launch at an initial range of 13km was also tracked and observed for 90 seconds after ignition. The NIR O2 band provided in-flight range estimates accurate to within 2% error for the first 30 seconds of tracked observation. The Vis O2 band also provided accurate range estimates with an error of approximately 4%. Rocket plumes are expected to be significantly brighter at longer wavelengths, but absorption in the NIR band is nearly ten times stronger than the Vis band, causing saturation at shorter path lengths. An atmospheric band is considered saturated when all the in-band frequencies emitted from the rocket plume are absorbed before reaching the sensor.

  8. Studies of the ECR plasma in the visible light range

    International Nuclear Information System (INIS)

    High resolution visible light (VL) plasma photographs were taken at the ATOMKI-ECRIS by an 8 mega-pixel digital camera. Plasmas were generated from gases of He, methane, N, O, Ne, Ar, Kr, Xe and from their mixtures. The analysis of the photo series gave many qualitative and numerous valuable physical information on the nature of ECR plasmas. VL photos convey information mainly on the cold electron component of the plasma. Cold electrons are confined in the central part of the plasma. It is a further challenging task to understand the colors of this special type of plasmas. The colors can be determined by the VL electron transitions of the plasma atoms and ions combined with the human eye sensitivity. There is a good visual agreement between the calculated normalized color and the real color of the plasmas. Through the examples of He and Xe we analyze the physical processes which affect the characteristic colors of these plasmas. The paper is followed by the slides of the presentation. (authors)

  9. New fractal structures for frequencies close to the visible range

    DEFF Research Database (Denmark)

    Malureanu, Radu; Sandru, A.; Andryieuski, Andrei; Lavrinenko, Andrei

    2011-01-01

    In this paper we present a new type of fractal resonator to be used in the red/NIR region of the spectra. The structure presents high-transmission band in 795-825nm range. The stop band is in the 683-731 nm range. Due to the huge difference in the spectra within such a short range, the structure can be used as an efficient sensor, both in transmission as well as in reflection. Thus, a variation of only 0.09 in the refraction index will for example change the structure’s behaviour from 90% reflec...

  10. Innovative static spectropolarimeter concept for wide spectral ranges: tolerancing study

    CERN Document Server

    Pertenais, Martin; Parès, Laurent; Petit, Pascal

    2015-01-01

    Developing an efficient and robust polarimeter for wide spectral ranges and space applications is a main issue in many projects. As part of the UVMag consortium created to develop UV facilities in space (e.g. the Arago mission proposed to ESA), we are studying an innovative concept of polarimeter that is robust, simple, and efficient on a wide spectral range. The idea, based on the article by Sparks et al. (2012), is to use polarization scramblers to create a spatial modulation of the polarization. Along the height of the wedges of the scramblers, the thickness of the birefringent material crossed by the light, and thus the retardance, vary continuously. This variation creates an intensity modulation of the light related to the entrance polarization state. Analyzing this modulation with a linear polarizer, and dispersing the light spectrally in the orthogonal spatial direction, enables the measurement of the full Stokes vector over the entire spectrum. This determination is performed with a single-shot measur...

  11. Diamond photonic crystals for the IR spectral range.

    Science.gov (United States)

    Kononenko, T V; Dyachenko, P N; Konov, V I

    2014-12-15

    2D photonic crystals formed inside monocrystalline diamond to operate in the IR spectral range are reported. The photonic structures consisting of 150-μm-long graphitized wires arranged in a square matrix with a period of 4 μm were produced by laser writing with ultrashort pulses. Transmittance spectra (λ=1-14  μm) measured for the structures with increasing thickness demonstrate the occurrence of few minima being different for TM and TE polarization modes. Complex refraction index of the laser-modified material was evaluated for the first time in order to be used in computer simulation of the structures. PMID:25503041

  12. Wide spectral range characterization of antireflective coatings and their optimization

    Science.gov (United States)

    Franta, Daniel; Ne?as, David; Ohlídal, Ivan; Jankuj, Ji?í

    2015-09-01

    Development of antireflective coatings realized by thin film systems requires their characterization and optimization of their properties. Functional properties of such interference devices are determined by optical constants and thicknesses of the individual films and various defects taking place in these systems. In optics industry the characterization of the films is mostly performed in a relatively narrow spectral range using simple dispersion models and, moreover, the defects are not taken into account at all. This manner of characterization fails if applied to real-world non-ideal thin film systems because the measured data do not contain sufficient information about all the parameters describing the system including imperfections. Reliable characterization requires the following changes: extension of spectral range of measurements, combination of spectrophotometry and ellipsometry, utilization of physically correct dispersion models (Kramers-Kronig consistency, sum rules), inclusion of structural defects instrument imperfection into the models and simultaneous processing of all experimental data. This enables us to remove or reduce a correlation among the parameters searched so that correct and sufficiently precise determination of parameter values is achieved. Since the presence and properties of the defects are difficult to control independently by tuning of the deposition conditions, the optimization does not in general involve the elimination of defects. Instead they are taken into account in the design of the film systems. The outlined approach is demonstrated on the characterization and optimization of ultraviolet antireflective coating formed by double layer of Al2O3 and MgF2 deposited on fused silica.

  13. Composition, mineralogy, and porosity of multiple asteroid systems from visible and near-infrared spectral data

    Science.gov (United States)

    Lindsay, S. S.; Marchis, F.; Emery, J. P.; Enriquez, J. E.; Assafin, M.

    2015-02-01

    We aim to provide a taxonomic and compositional characterization of Multiple Asteroid Systems (MASs) located in the main belt (MB) using visible (0.45-0.85 ?m) and near-infrared (0.7-2.5 ?m) spectral data of 42 MB MASs. The compositional and mineralogical analysis is applied to determine meteorite analogs for the MASs, which, in turn, are applied to the MAS density measurements of Marchis et al. (Marchis et al. [2012]. Icarus 221, 1130-1161) to estimate the porosity of the systems. The macroporosities are used to evaluate the primary MAS formation hypotheses. Our spectral survey consists of visible and near-infrared spectral data. The visible observing campaign includes 25 MASs obtained using the Southern Astrophysical Research (SOAR) telescope with the Goodman High Throughput Spectrometer. The infrared observing campaign includes 34 MASs obtained using the NASA Infrared Telescope Facility (IRTF) with the SpeX spectragraph. For completeness, both visible and NIR data sets are supplemented with publicly available data, and the data sets are combined where possible. The MASs are classified using the Bus-DeMeo taxonomic system. In order to determine mineralogy and meteorite analog, we perform a NIR spectral band parameter analysis using a new analysis routine, the Spectral Analysis Routine for Asteroids (SARA). The SARA routine determines band centers, areas, and depths by utilizing the diagnostic absorption features near 1- and 2-?m due to Fe2+ crystal field transitions in olivine + pyroxene and pyroxene, respectively. The band parameter analysis provides the Gaffey subtype for the S-complex MASs; the relative abundance olivine-to-pyroxene ratio; and olivine and pyroxene modal abundances for S-complex and V-type MASs. This mineralogical information is then applied to determine meteorite analogs. Through applying calibration studies, we are able to determine the H, L, and LL meteorite analogs for 15 MASs with ordinary chondrite-like (OC) mineralogies. We observe an excess (10/15) of LL-like mineralogies. Of the ten MASs with LL-like mineralogies, seven are consistent with Flora family membership, supporting the hypothesis that the Flora family is a source of LL-like NEAs and LL chondrites on Earth. Our band parameter analysis is unable to clearly distinguish between the HED subgroups for the 6 V-type MASs. Using the measured densities of the meteorite analog and the MAS densities from Marchis et al. (Marchis et al. [2012]. Icarus 221, 1130-1161), we estimate the macroporosity for 13 MASs. We find that all of the MASs with estimated macroporosities are in agreement with formation hypotheses.

  14. Composition, Mineralogy, and Porosity of Multiple Asteroid Systems from Visible and Near-infrared Spectral Data

    CERN Document Server

    Lindsay, Sean S; Emery, Joshua P; Enriquez, J Emilio; Assafin, Marcelo

    2014-01-01

    We provide a taxonomic and compositional characterization of Multiple Asteroid Systems (MASs) located in the main belt (MB) using visible and near-infrared (0.45-2.5 um) spectral data of 42 MB MASs. The mineralogical analysis is applied to determine meteorite analogs for the MASs, which, in turn, are applied to the MAS density measurements of Marchis et al. (2012) to estimate the system porosity. The macroporosities are used to evaluate the primary MAS formation hypotheses. The visible observing campaign includes 25 MASs obtained using the SOAR telescope with the Goodman High Throughput Spectrometer. The infrared observing campaign includes 34 MASs obtained using the NASA IRTF with the SpeX spectragraph. The MASs are classified using the Bus-DeMeo taxonomic system. We perform a NIR spectral band parameter analysis using a new analysis routine, the Spectral Analysis Routine for Asteroids (SARA). The SARA routine determines band centers, areas, and depths by utilizing the diagnostic absorption features near 1- ...

  15. Measurements of the Reflectivity in the Ultraviolet and Visible Wavelength Range in a Mountainous Region

    International Nuclear Information System (INIS)

    The reflectivity distribution of the surrounding area of Zugspitze (2964 m) was measured within the scope of the EU project CUVRA. The albedo measurements were performed in the UVA and visible range by using a CCD camera and a UVA sensor. First results of the albedo distribution in the visible wavelength range of the surrounding areas are shown. The reflectivity of snow, rocks and of vegetation and its dependence on illumination are studied. The albedo of snow surfaces ranges between 0.4 in the shade and values up to 2 when the orientation of the facet is favourable. Reflectivity of rocks and forests lies between 0.1 and 0.25. Further work on the albedo in the UV wavelength range will be carried out. First, a relationship between UV albedo and visible albedo will be established. (author)

  16. Visible spectroscopy of the Polana-Eulalia family complex: Spectral homogeneity

    Science.gov (United States)

    de León, J.; Pinilla-Alonso, N.; Delbo, M.; Campins, H.; Cabrera-Lavers, A.; Tanga, P.; Cellino, A.; Bendjoya, P.; Gayon-Markt, J.; Licandro, J.; Lorenzi, V.; Morate, D.; Walsh, K. J.; DeMeo, F.; Landsman, Z.; Alí-Lagoa, V.

    2016-03-01

    The Polana-Eulalia family complex is located in the inner part of the asteroid belt, bounded by the ν6 and the 3:1 resonances, where we can find another three collisional families of primitive asteroids (Erigone, Clarissa, and Sulamitis), and a low-albedo population of background objects. This region of the belt is believed to be the most likely origin of the two primitive near-Earth asteroids that are the current targets of two sample return missions: NASA's OSIRIS-REx and JAXA's Hayabusa 2 to Asteroids (101955) Bennu and (162173) Ryugu (also known as 1999 JU3), respectively. Therefore, understanding these families will enhance the scientific return of these missions. We present the results of a spectroscopic survey of asteroids in the region of the Polana-Eulalia family complex, and also asteroids from the background population of low-albedo, low-inclination objects. We obtained visible spectra of a total of 65 asteroids, using the 10.4 m Gran Telescopio Canarias (GTC) and the 3.6 m Telescopio Nazionale Galileo (TNG), both located at the El Roque de Los Muchachos Observatory, in the island of La Palma (Spain), and the 3.6 m New Technology Telescope (NTT), located at the European Southern Observatory of La Silla, in Chile. From the spectral analysis of our sample we found that, in spite of the presence of distinct dynamical groups, the asteroids in this region present spectral homogeneity at visible wavelengths, showing a continuum of spectral slopes, from blue to moderately red, typical of primitive asteroids classified as B- and C-types. We conclude that visible spectra cannot be used to distinguish between members of the Polana and the Eulalia families, or members of the background population. The visible spectra of the two targets of sample return missions, Asteroids Bennu and Ryugu, are compatible with the spectra of the asteroids in this region, supporting previous studies that suggested either the Polana family or the background population as the most likely origins of these NEAs.

  17. Photofragmentation of colloidal solutions of gold nanoparticles under femtosecond laser pulses in IR and visible ranges

    Science.gov (United States)

    Danilov, P. A.; Zayarnyi, D. A.; Ionin, A. A.; Kudryashov, S. I.; Lednev, V. N.; Makarov, S. V.; Pershin, S. M.; Rudenko, A. A.; Saraeva, I. N.; Yurovskikh, V. I.

    2015-05-01

    The specific features of photofragmentation of sols of gold nanoparticles under focused femtosecond laser pulses in IR (1030 nm) and visible (515 nm) ranges is experimentally investigated. A high photofragmentation efficiency of nanoparticles in the waist of a pulsed laser beam in the visible range (at moderate radiation scattering) is demonstrated; this efficiency is related to the excitation of plasmon resonance in nanoparticles on the blue shoulder of its spectrum, in contrast to the regime of very weak photofragmentation in an IR-laser field of comparable intensity. Possible mechanisms of femtosecond laser photofragmentation of gold nanoparticles are discussed.

  18. Visible and near-infrared spectral signatures for adulteration assessment of extra virgin olive oil

    Science.gov (United States)

    Mignani, A. G.; Ciaccheri, L.; Ottevaere, H.; Thienpont, H.; Conte, L.; Marega, M.; Cichelli, A.; Attilio, C.; Cimato, A.

    2010-04-01

    Because of its high price, the extra virgin olive oil is frequently target for adulteration with lower quality oils. This paper presents an innovative optical technique capable of quantifying the adulteration of extra virgin olive oil caused by lowergrade olive oils. It relies on spectral fingerprinting the test liquid by means of diffuse-light absorption spectroscopy carried out by optical fiber technology in the wide 400-1700 nm spectral range. Then, a smart multivariate processing of spectroscopic data is applied for immediate prediction of adulterant concentration.

  19. Retrieval of absorptive gas columnar amounts using atmospheric hyper-spectral irradiance measurements within visible spectrum

    Science.gov (United States)

    Xu, Hua; Li, Zhengqiang; Li, Donghui; Xie, Yisong; Li, Kaitao; Qie, Lili; Zhang, Ying; Chen, Xingfeng; Zheng, Xiaobin; Li, Xin; Zhang, Yanna

    2015-10-01

    A hyper spectral ground-based instrument named Atmosphere-Surface Radiation Automatic Instrument (ASRAI) has been developed for the purpose of in-situ calibration of satellites. The apparatus has both upward and downward looking views, and thus can observe both the atmosphere and land surface. The solar transmitted irradiance can be derived from the measured full spectral irradiance and diffused spectral irradiance of atmosphere within visible spectrum (0.4-1.0?m). A method similar to that of King et al. which originally intended to apply to multi-wavelength measurements, is adopted to determine absorptive gaseous columnar amount from hyper spectrum. The solar irradiance at top of atmosphere and absorption coefficients of water vapor (H2O), ozone (O3), oxygen (O2) and nitrogen dioxide (NO2) are recalculated at an instrumental spectral resolution by convolution method. Based on the gaseous characteristics of absorption, the total columnar amounts of water vapor and oxygen are first inferred from solar transmitted irradiance at strong absorption wavelength of 0.934?m and 0.763?m respectively. The total columnar amounts of ozone and nitrogen dioxide, together with aerosol optical depth, are determined by a nonlinear least distance fitting method which minimizes a ?2 statistic to obtain optimal solutions. ASRAI was deployed for observation in Dunhuang site in China in August of 2014. Our results demonstrate that the algorithm is reasonable. Although the validation is preliminary, the hyper spectrum measured by ASRAI exhibits good ability to retrieve the abundance of absorptive gases and aerosols.

  20. Experimental demonstration of a broadband array of invisibility cloaks in the visible frequency range

    CERN Document Server

    Smolyaninova, V N; Ermer, H K

    2012-01-01

    Very recently Farhat et al. [1] have suggested that arrays of invisibility cloaks may find important applications in low-interference communication, noninvasive probing, sensing and communication networks, etc. We report on the first experimental realization of such an array of broadband invisibility cloaks, which operates in the visible frequency range. Wavelength and angular dependencies of the cloak array performance have been studied.

  1. Separate photosensitizers mediate degradation of the 32-kDa photosystem II reaction center protein in the visible and UV spectral regions.

    OpenAIRE

    Greenberg, B.M.; Gaba, V.; Canaani, O; Malkin, S; Mattoo, A.K.; Edelman, M

    1989-01-01

    A component of the photosystem II reaction center, the 32-kDa protein, is rapidly turned over in the light. The mechanism of its light-dependent metabolism is largely unknown. We quantified the rate of 32-kDa protein degradation over a broad spectral range (UV, visible, and far red). The quantum yield for degradation was highest in the UVB (280-320 nm) region. Spectral evidence demonstrates two distinctly different photosensitizers for 32-kDa protein degradation. The data implicate the bulk p...

  2. Micro- and nanophotonic structures in the visible and near infrared spectral region for optical devices

    Science.gov (United States)

    Pham, Van Hoi; Bui, Huy; Van Nguyen, Thuy; Nguyen, The Anh; Son Pham, Thanh; Cam Hoang, Thi Hong; Ngo, Quang Minh

    2013-06-01

    In this paper we present some research results on the micro and nano-photonic structures in the visible and near infrared spectral region for optical devices that have been done within the framework of Nanoscience and Nanotechnology Program of Institute of Materials Science. In the first part, we report the design and fabrication of 1D photonic structure based on porous silicon layers fabricated by electrochemical etching method and some of their potential applications such as optical filters, microcavity and optical sensors for distinguishing the content of bio-gasoline. In addition, we demonstrate some results on preparation of the 2D and 3D nanophotonic structures based on silica opal layers prepared by sol-gel and self-assembled methods. In the second part, we demonstrate the results of lasing emissions of erbium ions in the visible and near infrared zone from microcavity. The observation of emission of single-mode green light at the wavelength of 537 nm from erbium ions in the microcavity is interesting for the study of atom-photon interaction phenomenon. In the last part, we will show some new results of design and fabrication of nanocomposite based on nanoscale TiO2 and/or ZnO and nanoparticles of semiconductors and metals, which are oriented to the fabrication of energy conversion and photo-reactor devices. Invited talk at the 6th International Workshop on Advanced Materials Science and Nanotechnology IWAMSN2012, 30 October-2 November, 2012, Ha Long, Vietnam.

  3. Micro- and nanophotonic structures in the visible and near infrared spectral region for optical devices

    International Nuclear Information System (INIS)

    In this paper we present some research results on the micro and nano-photonic structures in the visible and near infrared spectral region for optical devices that have been done within the framework of Nanoscience and Nanotechnology Program of Institute of Materials Science. In the first part, we report the design and fabrication of 1D photonic structure based on porous silicon layers fabricated by electrochemical etching method and some of their potential applications such as optical filters, microcavity and optical sensors for distinguishing the content of bio-gasoline. In addition, we demonstrate some results on preparation of the 2D and 3D nanophotonic structures based on silica opal layers prepared by sol–gel and self-assembled methods. In the second part, we demonstrate the results of lasing emissions of erbium ions in the visible and near infrared zone from microcavity. The observation of emission of single-mode green light at the wavelength of 537 nm from erbium ions in the microcavity is interesting for the study of atom–photon interaction phenomenon. In the last part, we will show some new results of design and fabrication of nanocomposite based on nanoscale TiO2 and/or ZnO and nanoparticles of semiconductors and metals, which are oriented to the fabrication of energy conversion and photo-reactor devices. (review)

  4. A feasibility study for the retrieval of the total column precipitable water vapour from satellite observations in the blue spectral range

    Directory of Open Access Journals (Sweden)

    T. Wagner

    2013-10-01

    Full Text Available We present a new algorithm for satellite retrievals of the atmospheric water vapour column in the blue spectral range. The water vapour absorption cross section in the blue spectral range is much weaker than in the red spectral range. Thus the detection limit and the uncertainty of individual observations are systematically larger than for retrievals at longer wavelengths. Nevertheless, water vapour retrievals in the blue spectral range have also several advantages: since the surface albedo in the blue spectral range is similar over land and ocean, water vapour retrievals are more consistent than for longer wavelengths. Compared to retrievals at longer wavelengths, the sensitivity for atmospheric layers close to the surface is higher due to the (typically 2 to 3 times higher ocean albedo in the blue. Water vapour retrievals in the blue spectral range are also possible for satellite sensors, which do not measure at longer wavelengths of the visible spectral range like the Ozone Monitoring Instrument (OMI. We investigated details of the water vapour retrieval in the blue spectral range based on radiative transfer simulations and observations from the Global Ozone Monitoring Experiment 2 (GOME-2 and OMI. It is demonstrated that it is possible to retrieve the atmospheric water vapour column density in the blue spectral range over most parts of the globe. The findings of our study are of importance also for future satellite missions (e.g. Sentinel 4 and 5.

  5. A feasibility study for the retrieval of the total column precipitable water vapor from satellite observations in the blue spectral range

    Directory of Open Access Journals (Sweden)

    T. Wagner

    2013-04-01

    Full Text Available We present a new algorithm for satellite retrievals of the atmospheric water vapor column in the blue spectral range. The water vapor absorption cross section in the blue spectral range is much weaker than in the red spectral range. Thus the detection limit and the uncertainty of individual observations is systematically larger than for retrievals at longer wavelengths. Nevertheless, water vapor retrievals in the blue spectral range have also several advantages: since the surface albedo in the blue spectral range is similar over land and ocean, water vapor retrievals are more consistent than for longer wavelengths. Compared to retrievals at longer wavelengths, over ocean the sensitivity for atmospheric layers close to the surface is higher due to the (typically 2 to 3 times higher ocean albedo in the blue. Water vapor retrievals in the blue spectral range are also possible for satellite sensors, which do not measure at longer wavelengths of the visible spectral range like the Ozone Monitoring instrument (OMI. We investigated details of the water vapor retrieval in the blue spectral range based on radiative transfer simulations and observations from the Global Ozone Monitoring Experiment 2 (GOME-2 and OMI. It is demonstrated that it is possible to retrieve the atmospheric water vapor column density in the blue spectral range over most parts of the globe. The findings of our study are of importance also for future satellite missions like e.g. Sentinel 4 and 5.

  6. Integrated visible to near infrared, short wave infrared, and long wave infrared spectral analysis for surface composition mapping near Mountain Pass, California

    Science.gov (United States)

    McDowell, Meryl L.; Kruse, Fred A.

    2015-05-01

    We have developed new methods for enhanced surface material identification and mapping that integrate visible to near infrared (VNIR, ~0.4 - 1 ?m), short wave infrared (SWIR, ~1 - 2.5 ?m), and long wave infrared (LWIR, ~8 - 12 ?m) multispectral and hyperspectral imagery. This approach produces a single map of surface composition derived from the full spectral range. We applied these methods to a spectrally diverse region around Mountain Pass, CA. A comparison of the integrated results with those obtained from analyzing the spectral ranges individually reveals compositional information not exhibited by the VNIR, SWIR or LWIR data alone. We also evaluate the benefit of hyperspectral rather than multispectral LWIR data for this integrated approach.

  7. Separate photosensitizers mediate degradation of the 32-kDa photosystem II reaction center protein in the visible and UV spectral regions

    International Nuclear Information System (INIS)

    A component of the photosystem II reaction center, the 32-kDa protein, is rapidly turned over in the light. The mechanism of its light-dependent metabolism is largely unknown. We quantified the rate of 32-kDa protein degradation over a broad spectral range (UV, visible, and far red). The quantum yield for degradation was highest in the UVB (280-320 nm) region. Spectral evidence demonstrates two distinctly different photosensitizers for 32-kDa protein degradation. The data implicate the bulk photosynthetic pigments (primarily chlorophyll) in the visible and far red regions, and plastoquinone (in one or more of its redox states) in the UV region. A significant portion of 32-kDa protein degradation in sunlight is attributed to UVB irradiance

  8. Thermal radiative and thermodynamic properties of solid and liquid uranium and plutonium carbides in the visible-near infrared range

    CERN Document Server

    Fisenko, Anatoliy I

    2016-01-01

    The knowledge of thermal radiative and thermodynamic properties of uranium and plutonium carbides under extreme conditions is essential for designing a new metallic fuel materials for next generation of a nuclear reactor. The present work is devoted to the study of the thermal radiative and thermodynamic properties of liquid and solid uranium and plutonium carbides at their melting/freezing temperatures. The Stefan-Boltzmann law, total energy density, number density of photons, Helmholtz free energy density, internal energy density, enthalpy density, entropy density, heat capacity at constant volume, pressure, and normal total emissivity are calculated using experimental data for the frequency dependence of the normal spectral emissivity of liquid and solid uranium and plutonium carbides in the visible-near infrared range. It is shown that the thermal radiative and thermodynamic functions of uranium carbide have a slight difference during liquid-to-solid transition. Unlike UC, such a difference between these ...

  9. Experimental demonstration of a broadband array of invisibility cloaks in the visible frequency range

    International Nuclear Information System (INIS)

    Very recently Farhat et al (2011, Phys. Rev. B 84 235105) suggested that arrays of invisibility cloaks may find important applications in low-interference communication, noninvasive probing, sensing and communication networks and so on. We report on the first experimental realization of such an array of broadband invisibility cloaks that operates in the visible frequency range. The wavelength and angular dependences of the cloak array performance have been studied. (paper)

  10. The UV-A and visible solar irradiance spectrum: inter-comparison of absolutely calibrated, spectrally medium resolution solar irradiance spectra from balloon- and satellite-borne measurements

    Directory of Open Access Journals (Sweden)

    W. Gurlit

    2004-12-01

    Full Text Available Within the framework of the ENVISAT/-SCIAMACHY satellite validation, solar irradiance spectra are absolutely measured at moderate resolution in the UV/visible spectral range (in the UV from 316.7–418 nm and the visible from 400–652 nm at a full width half maximum resolution of 0.55 nm and 1.48 nm, respectively from aboard the azimuth-controlled LPMA/DOAS balloon gondola at around 32 km balloon float altitude. After accounting for the atmospheric extinction due to Rayleigh scattering and gaseous absorption (O3, and NO2, the measured solar spectra are compared with previous observations. Our solar irradiance is +1.6% larger than the re-calibrated Kurucz et al. (1984 solar spectrum (Fontenla et al., 1999, called MODTRAN 3.5 in the visible spectral range (435–650 nm, +1.5% larger in the (370–415 nm wavelength interval, but ?4% smaller in the UV spectral range (316.7–370 nm, when the Kurucz spectrum is convolved to the spectral resolution of our instrument. The same comparison with the SOLSPEC solar spectrum (Thuillier et al., 1997, 1998a, b confirms the somewhat larger solar irradiance (+1.7% measured by the balloon instrument from 435–500 nm, but not from 500–650 nm, where the SOLSPEC is ?1.3% lower than MODTRAN 3.5. Comparison of the SCIAMACHY solar spectrum from channels 1 to 4 (– re-calibrated by the University of Bremen – with MODTRAN 3.5 indicates an agreement of +0.2% in the visible spectral range (435–585 nm. With this calibration, the SCIAMACHY solar spectrum is congruent with the balloon observations (?1% in the 316.7–370 nm wavelength range, but both are up to ?5%/?3% smaller than MODTRAN 3.5 and SOLSPEC, respectively. In agreement with findings of Skupin et al. (2002 our study emphasizes that the present ESA SCIAMACHY level 1 calibration is systematically +15% larger in the considered wavelength intervals when compared to all available other solar irradiance measurements.

  11. Using Visible Spectral Information to Predict Long-Wave Infrared Spectral Emissivity: A Case Study over the Sokolov Area of the Czech Republic with an Airborne Hyperspectral Scanner Sensor

    Directory of Open Access Journals (Sweden)

    Gila Notesco

    2013-11-01

    Full Text Available Remote-sensing platforms are often comprised of a cluster of different spectral range detectors or sensors to benefit from the spectral identification capabilities of each range. Missing data from these platforms, caused by problematic weather conditions, such as clouds, sensor failure, low temporal coverage or a narrow field of view (FOV, is one of the problems preventing proper monitoring of the Earth. One of the possible solutions is predicting a detector or sensor’s missing data using another detector/sensor. In this paper, we propose a new method of predicting spectral emissivity in the long-wave infrared (LWIR spectral region using the visible (VIS spectral region. The proposed method is suitable for two main scenarios of missing data: sensor malfunctions and narrow FOV. We demonstrate the usefulness and limitations of this prediction scheme using the airborne hyperspectral scanner (AHS sensor, which consists of both VIS and LWIR spectral regions, in a case study over the Sokolov area, Czech Republic.

  12. Polylogarithmic representation of radiative and thermodynamic properties of thermal radiation in a given spectral range: II. Real-body radiation

    CERN Document Server

    Fisenko, Anatoliy I

    2015-01-01

    The general analytical expressions for the thermal radiative and thermodynamic properties of a real-body are obtained in a finite range of frequencies at different temperatures. The frequency dependence of the spectral emissivity is represented as a power series. The Stefan-Boltzmann law, total energy density, number density of photons, Helmholtz free energy density, internal energy density, enthalpy density, entropy density, heat capacity at constant volume, pressure, and total emissivity are expressed in terms of the polylogarithm functions. The general expressions for the thermal radiative and thermodynamic functions are applied for the study of thermal radiation of liquid and solid zirconium carbide. These functions are calculated using experimental data for the frequency dependence of the normal spectral emissivity in the visible-near infrared range at the melting (freezing) point. The gaps between the thermal radiative and thermodynamic functions of liquid and solid zirconium carbide are observed. The g...

  13. The UV-A and visible solar irradiance spectrum: inter-comparison of absolutely calibrated, spectrally medium resolution solar irradiance spectra from balloon- and satellite-borne measurements

    Directory of Open Access Journals (Sweden)

    W. Gurlit

    2005-01-01

    Full Text Available Within the framework of the ENVISAT/-SCIAMACHY satellite validation, solar irradiance spectra are absolutely measured at moderate resolution in the UV/visible spectral range (in the UV from 316.7-418 nm and the visible from 400-652 nm at a full width half maximum resolution of 0.55 nm and 1.48 nm, respectively from aboard the azimuth-controlled LPMA/DOAS balloon gondola at around 32 km balloon float altitude. After accounting for the atmospheric extinction due to Rayleigh scattering and gaseous absorption (O3 and NO2, the measured solar spectra are compared with previous observations. Our solar irradiance spectrum perfectly agrees within +0.03% with the re-calibrated Kurucz et al. (1984 solar spectrum (Fontenla et al., 1999, called MODTRAN 3.7 in the visible spectral range (415-650 nm, but it is +2.1% larger in the (370-415 nm wavelength interval, and -4% smaller in the UV-A spectral range (316.7-370 nm, when the Kurucz spectrum is convolved to the spectral resolution of our instrument. Similar comparisons of the SOLSPEC (Thuillier et al., 1997, 1998a, b and SORCE/SIM (Harder et al., 2000 solar spectra with MODTRAN 3.7 confirms our findings with the values being -0.5%, +2%, and -1.4% for SOLSPEC -0.33%, -0.47%, and -6.2% for SORCE/SIM, respectively. Comparison of the SCIAMACHY solar spectrum from channels 1 to 4 (- re-calibrated by the University of Bremen - with MODTRAN 3.7 indicates an agreement within -0.4% in the visible spectral range (415-585 nm, -1.6% within the 370-415 nm, and -5.7% within 325-370 nm wavelength interval, in agreement with the results of the other sensors. In agreement with findings of Skupin et al. (2002 our study emphasizes that the present ESA SCIAMACHY level 1 calibration is systematically +15% larger in the considered wavelength intervals when compared to all available other solar irradiance measurements.

  14. Magnesium as Novel Material for Active Plasmonics in the Visible Wavelength Range.

    Science.gov (United States)

    Sterl, Florian; Strohfeldt, Nikolai; Walter, Ramon; Griessen, Ronald; Tittl, Andreas; Giessen, Harald

    2015-12-01

    Investigating new materials plays an important role for advancing the field of nanoplasmonics. In this work, we fabricate nanodisks from magnesium and demonstrate tuning of their plasmon resonance throughout the whole visible wavelength range by changing the disk diameter. Furthermore, we employ a catalytic palladium cap layer to transform the metallic Mg particles into dielectric MgH2 particles when exposed to hydrogen gas. We prove that this transition can be reversed in the presence of oxygen. This yields plasmonic nanostructures with an extinction spectrum that can be repeatedly switched on or off or kept at any intermediate state, offering new perspectives for active plasmonic metamaterials. PMID:26312401

  15. Observation of the fine structure for rovibronic spectral lines in visible part of emission spectra of $D_2$

    CERN Document Server

    Lavrov, B P; Zhukov, A S

    2011-01-01

    For the first time the fine structure of rovibronic spectral lines in visible part of emission spectra of $D_2$ molecule has been observed. Observed splitting in visible doublets is about 0.2 cm$^{-1}$ in good accordance with previous observations in the infrared part of the spectrum ($a^3\\Sigma_g^+ \\to c^3\\Pi_u$ electronic transition) by means of FTIR and laser spectroscopy. Relative intensities of the fine structure components are in agreement with our calculations of adiabatic line strengths for Hund's case "b" coupling scheme.

  16. Scientometric analyses of the international visibility of German psychology researchers and their range of specialization

    Directory of Open Access Journals (Sweden)

    Clemens B. Fell

    2012-06-01

    Full Text Available With reference to the role of networking, accelerated by current developments within large parts of the scientific community, the assumption is examined that the range of specialization of scientists in terms of membership in professional sections of scientific societies is related to the international impact of their publications. The sample consists of 2,788 German psychologists enrolled in the German Psychological Society (Deutsche Gesellschaft für Psychologie, DGPs. A log-linear model suggests that the citation pattern of DGPs members with no citations of their papers published in 2000 or 2005 respectively in the time intervals 2000-2004 or 2005-2009 generally differs from that of their colleagues across four ranges of specialization categories. Configural Frequency Analysis led to the identification of distinct subgroups of scientific specialization and international visibility, i.e., citations by others. Specifically, for those individuals who enjoy international visibility, one key to success seems to be multiple professional specializations with reference to different subdisciplines of psychology.

  17. Dose dependence of visible range diffuse reflectivity for Si+ and C+ ion implanted polymers

    Science.gov (United States)

    Balabanov, S.; Tsvetkova, T.; Borisova, E.; Avramov, L.; Bischoff, L.

    2008-05-01

    Detailed insight into the near-surface area of the ion beam modified polymer is supplied by the measured diffuse reflectivity spectra. The near-surface layer (50÷150 nm) of bulk polymer samples have been implanted with silicon (Si+) and carbon (C+) ions at low energies (E = 30 keV) and a wide range of ion doses (D = 5.1012-2.1017 cm+2). The polymer materials studied were: ultra-high-molecular-weight polyethylene (UHMWPE), poly-propylene (PP), and poly-tetra-fluor-ethylene (PTFE). The diffuse optical reflectivity spectra Rd = f(?) of the implanted samples have been measured in the visible range (? = 400÷830 nm). In this paper the dose dependences of the size and sign of the diffuse reflectivity changes ?Rd = f(D) have been analyzed.

  18. Tunable femtosecond laser in the visible range with an intracavity frequency-doubled optical parametric oscillator

    Science.gov (United States)

    Zhu, Jiang-Feng; Xu, Liang; Lin, Qing-Feng; Zhong, Xin; Han, Hai-Nian; Wei, Zhi-Yi

    2013-05-01

    We demonstrated experimentally a synchronously pumped intracavity frequency-doubled femtosecond optical parametric oscillator (OPO) using a periodically-poled lithium niobate (PPLN) as the nonlinear material in combination with a lithium triborate (LBO) as the doubling crystal. A Kerr-lens-mode-locked (KLM) Ti:sapphire oscillator at the wavelength of 790 nm was used as the pump source, which was capable of generating pulses with a duration as short as 117 fs. A tunable femtosecond laser covering the 624-672 nm range was realized by conveniently adjusting the OPO cavity length. A maximum average output power of 260 mW in the visible range was obtained at the pump power of 2.2 W, with a typical pulse duration of 205 fs assuming a sech2 pulse profile.

  19. Calibration of a high dynamic range, low light level visible source

    Science.gov (United States)

    La Veigne, Joe; Szarlan, Todd; Radtke, Nate

    2011-05-01

    Usage of image intensified (I2) and other low light level devices have grown considerably over the past decade1,2 As the systems have become more common place, the demand for production line test equipment has also grown. Accurate measurements of device response are a key part of determining acceptable system operation. However, differences in the spectral response of the unit under test (UUT) devices and the control detector; and the spectral distribution of the source, can lead to errors in test accuracy. These errors can be compounded by spectral variation in the source (or color temperature shifts) as a function of attenuation. These issues are often further confused by test system requirements that are not consistent with the desired parameter to be measured. For example, source requirements are often specified in illuminance while the UUT actually measures irradiance. We report on the calibration of a large dynamic range light source test system (> 7 orders), and discuss output compensation approaches for systems which control in a band different than the UUT being tested.

  20. Squared visibility estimator. Calibrating biases to reach very high dynamic range

    CERN Document Server

    Perrin, G

    2005-01-01

    In the near infrared where detectors are limited by read-out noise, most interferometers have been operated in wide band in order to benefit from larger photon rates. We analyze in this paper the biases caused by instrumental and turbulent effects to $V^2$ estimators for both narrow and wide band cases. Visibilities are estimated from samples of the interferogram using two different estimators, $V^{2}_1$ which is the classical sum of the squared modulus of Fourier components and a new estimator $V^{2}_2$ for which complex Fourier components are summed prior to taking the square. We present an approach for systematically evaluating the performance and limits of each estimator, and to optimizing observing parameters for each. We include the effects of spectral bandwidth, chromatic dispersion, scan length, and differential piston. We also establish the expression of the Signal-to-Noise Ratio of the two estimators with respect to detector and photon noise. The $V^{2}_1$ estimator is insensitive to dispersion and ...

  1. Infrared Spectroscopy with Visible Light

    CERN Document Server

    Kalashnikov, Dmitry A; Kulik, Sergei P; Krivitsky, Leonid A

    2015-01-01

    Spectral measurements in the infrared (IR) optical range provide unique fingerprints of materials which are useful for material analysis, environmental sensing, and health diagnostics. Current IR spectroscopy techniques require the use of optical equipment suited for operation in the IR range, which faces challenges of inferior performance and high cost. Here we develop a spectroscopy technique, which allows spectral measurements in the IR range using visible spectral range components. The technique is based on nonlinear interference of infrared and visible photons, produced via Spontaneous Parametric Down Conversion (SPDC). The intensity interference pattern for a visible photon depends on the phase of an IR photon, which travels through the media. This allows determining properties of the media in the IR range from the measurements of visible photons. The technique can substitute and/or complement conventional IR spectroscopy techniques, as it uses well-developed optical components for the visible range.

  2. Characterizing aerosol extinction in the UV-NIR spectral range

    Science.gov (United States)

    Gimmestad, Gary; Roberts, David

    2011-06-01

    The Georgia Tech Research Institute (GTRI) is developing a transportable multi-lidar system known as the Integrated Atmospheric Characterization System (IACS). The system will comprise three lidars: an imaging lidar for profiling refractive turbulence, a Raman lidar for profiling water vapor, and an aerosol lidar operating at 0.355, 1.064, and 1.625 microns for profiling aerosol extinction. All of the lidar transmit/receive optics will be co-aligned on a common mount, pointable at any elevation angle from below horizontal to vertical. The entire system will be computer controlled to facilitate pointing and automatic data acquisition. The purpose of IACS is to characterize optical propagation paths during outdoor tests of electro-optical systems. The tests are anticipated to include ground-to-ground, air-to-ground, and ground-to-air scenarios, so the system must accommodate arbitrary slant paths through the atmosphere with maximum measurement ranges of 5-10 km. Elevation angle scans will be used to calibrate the atmospheric extinction profiles and data from the three wavelengths will be used to determine the aerosol Angstrom coefficient, enabling interpolation of results to other wavelengths in the 0.355 to 1.6 micron region. Some of the lidar engineering challenges and solutions are presented here.

  3. Quantitative analysis of the UV-visible spectral profile of hemoglobin after exposure to microwave radiation

    International Nuclear Information System (INIS)

    Adult male albino mice were exposed to 950 MHz continuous microwave field 2 h/ day, 3 days/week for total period of two weeks. The selected power density range was 0.25 mW/ cm2 equivalent to specific absorption rate (SAR) 0.1 W/ kg body wt. The effects of microwave radiation on the conformation of the hemoglobin were investigated through analysis of the UV-visible absorption spectrum. The following parameters were calculated: maximum and total molar absorption coefficient, total absorption cross-section, dipole strength, transition dipole moment, dipole length and oscillator strength. The recorded hemoglobin spectrum of the exposed group showed significant increase in the maximum and integrated absorption coefficient of all characteristic peaks compared to the control group. The Sort and Qo bands, exhibited significant increase in all calculated parameters. The obtained results showed that the exposure to microwave fields could affect the conformation of the hemoglobin molecule through re-orientation of the molecular dipole moments

  4. Tuning light emission of PbS nanocrystals from infrared to visible range by cation exchange

    Science.gov (United States)

    Binetti, Enrico; Striccoli, Marinella; Sibillano, Teresa; Giannini, Cinzia; Brescia, Rosaria; Falqui, Andrea; Comparelli, Roberto; Corricelli, Michela; Tommasi, Raffaele; Agostiano, Angela; Curri, M. Lucia

    2015-10-01

    Colloidal semiconductor nanocrystals, with intense and sharp-line emission between red and near-infrared spectral regions, are of great interest for optoelectronic and bio-imaging applications. The growth of an inorganic passivation layer on nanocrystal surfaces is a common strategy to improve their chemical and optical stability and their photoluminescence quantum yield. In particular, cation exchange is a suitable approach for shell growth at the expense of the nanocrystal core size. Here, the cation exchange process is used to promote the formation of a CdS passivation layer on the surface of very small PbS nanocrystals (2.3 nm in diameter), blue shifting their optical spectra and yielding luminescent and stable nanostructures emitting in the range of 700–850 nm. Structural, morphological and compositional investigation confirms the nanocrystal size contraction after the cation-exchange process, while the PbS rock-salt crystalline phase is retained. Absorption and photoluminescence spectroscopy demonstrate the growth of a passivation layer with a decrease of the PbS core size, as inferred by the blue-shift of the excitonic peaks. The surface passivation strongly increases the photoluminescence intensity and the excited state lifetime. In addition, the nanocrystals reveal increased stability against oxidation over time. Thanks to their absorption and emission spectral range and the slow recombination dynamics, such highly luminescent nano-objects can find interesting applications in sensitized photovoltaic cells and light-emitting devices.

  5. Tuning light emission of PbS nanocrystals from infrared to visible range by cation exchange

    KAUST Repository

    Binetti, Enrico

    2015-10-27

    Colloidal semiconductor nanocrystals, with intense and sharp-line emission between red and near-infrared spectral regions, are of great interest for optoelectronic and bio-imaging applications. The growth of an inorganic passivation layer on nanocrystal surfaces is a common strategy to improve their chemical and optical stability and their photoluminescence quantum yield. In particular, cation exchange is a suitable approach for shell growth at the expense of the nanocrystal core size. Here, the cation exchange process is used to promote the formation of a CdS passivation layer on the surface of very small PbS nanocrystals (2.3 nm in diameter), blue shifting their optical spectra and yielding luminescent and stable nanostructures emitting in the range of 700–850 nm. Structural, morphological and compositional investigation confirms the nanocrystal size contraction after the cation-exchange process, while the PbS rock-salt crystalline phase is retained. Absorption and photoluminescence spectroscopy demonstrate the growth of a passivation layer with a decrease of the PbS core size, as inferred by the blue-shift of the excitonic peaks. The surface passivation strongly increases the photoluminescence intensity and the excited state lifetime. In addition, the nanocrystals reveal increased stability against oxidation over time. Thanks to their absorption and emission spectral range and the slow recombination dynamics, such highly luminescent nano-objects can find interesting applications in sensitized photovoltaic cells and light-emitting devices.

  6. Tailoring Metallodielectric Structures for Super Resolution and Superguiding Applications in the Visible and Near IR Ranges

    CERN Document Server

    De Ceglia, D; Cappeddu, M G; Centini, M; Akozbek, N; DOrazio, A; Haus, J W; Bloemer, M J; Scalora, M

    2008-01-01

    We discuss propagation effects in realistic, transparent, metallo-dielectric photonic band gap structures in the context of negative refraction and super-resolution in the visible and near infrared ranges. In the resonance tunneling regime, we find that for transverse-magnetic incident polarization, field localization effects contribute to a waveguiding phenomenon that makes it possible for the light to remain confined within a small fraction of a wavelength, without any transverse boundaries, due to the suppression of diffraction. This effect is related to negative refraction of the Poynting vector inside each metal layer, balanced by normal refraction inside the adjacent dielectric layer: The degree of field localization and material dispersion together determine the total momentum that resides within any given layer, and thus the direction of energy flow. We find that the transport of evanescent wave vectors is mediated by the excitation of quasi-stationary, low group velocity surface waves responsible for...

  7. Photocatalysis in the visible range of sub-stoichiometric anatase films prepared by MOCVD

    Energy Technology Data Exchange (ETDEWEB)

    Justicia, I. [ICMAB/CSIC, Campus UAB, 08193 Bellaterra (Spain); Garcia, G. [ICMAB/CSIC, Campus UAB, 08193 Bellaterra (Spain)]. E-mail: gemma@icmab.es; Battiston, G.A. [ICIS/CNR, Corso Stati Uniti 4, 35127 Padova (Italy); Gerbasi, R. [ICIS/CNR, Corso Stati Uniti 4, 35127 Padova (Italy); Ager, F. [CNA/CSIC Parque Tecnologico Cartuja 93, Avda Thomas A, Edison, 41092 Sevilla (Spain); Guerra, M. [IIQAB/CSIC Jordi Girona, 18 08034 Barcelona (Spain); Caixach, J. [IIQAB/CSIC Jordi Girona, 18 08034 Barcelona (Spain); Pardo, J.A. [ICMAB/CSIC, Campus UAB, 08193 Bellaterra (Spain); Rivera, J. [IIQAB/CSIC Jordi Girona, 18 08034 Barcelona (Spain); Figueras, A. [ICMAB/CSIC, Campus UAB, 08193 Bellaterra (Spain); Instituto de Fisica, UNAM, Campus UNAM Juriquilla, 76230 Queretaro (Mexico)

    2005-08-25

    Anatase phase of titanium oxide is the most promising photocatalyst material for organic pollutant degradation. However, due to its large band gap energy (3.2 eV) it is not viable to use sunlight as an energy source for the photocatalysis activation, and so, ultraviolet (UV) radiation below the wavelength of 380 nm is required. This paper focuses on the experimental demonstration of the reduction of this large band gap energy by inducing defects in the anatase structure under the form of oxygen sub-stoichiometry. TiO{sub 2} thin films were prepared in a metal organic chemical vapour deposition (MOCVD) reactor. The samples stoichiometry was measured by the Rutherford backscattering spectrometry (RBS) technique. Optical characterisation was also performed and the photodegradation activity in the visible range was tested using nonylphenol, which is one of the most harmful pollutants present in waste waters.

  8. Photocatalysis in the visible range of sub-stoichiometric anatase films prepared by MOCVD

    International Nuclear Information System (INIS)

    Anatase phase of titanium oxide is the most promising photocatalyst material for organic pollutant degradation. However, due to its large band gap energy (3.2 eV) it is not viable to use sunlight as an energy source for the photocatalysis activation, and so, ultraviolet (UV) radiation below the wavelength of 380 nm is required. This paper focuses on the experimental demonstration of the reduction of this large band gap energy by inducing defects in the anatase structure under the form of oxygen sub-stoichiometry. TiO2 thin films were prepared in a metal organic chemical vapour deposition (MOCVD) reactor. The samples stoichiometry was measured by the Rutherford backscattering spectrometry (RBS) technique. Optical characterisation was also performed and the photodegradation activity in the visible range was tested using nonylphenol, which is one of the most harmful pollutants present in waste waters

  9. Practical Atmospheric Correction Algorithms for a Multi-Spectral Sensor From the Visible Through the Thermal Spectral Regions

    Energy Technology Data Exchange (ETDEWEB)

    Borel, C.C.; Villeneuve, P.V.; Clodium, W.B.; Szymenski, J.J.; Davis, A.B.

    1999-04-04

    Deriving information about the Earth's surface requires atmospheric corrections of the measured top-of-the-atmosphere radiances. One possible path is to use atmospheric radiative transfer codes to predict how the radiance leaving the ground is affected by the scattering and attenuation. In practice the atmosphere is usually not well known and thus it is necessary to use more practical methods. The authors will describe how to find dark surfaces, estimate the atmospheric optical depth, estimate path radiance and identify thick clouds using thresholds on reflectance and NDVI and columnar water vapor. The authors describe a simple method to correct a visible channel contaminated by a thin cirrus clouds.

  10. Visibilidad de Alcance Limitado en Polígonos Escalera / Visibility of limited range in staircase polygons

    Scientific Electronic Library Online (English)

    Santiago, Canales Cano; Gregorio, Hernández Peñalver.

    2009-06-01

    Full Text Available La definición de visibilidad en el Problema de Galerías de Arte utiliza guardias o luces que pueden ver o iluminar sin limitación en el alcance. En este artículo consideramos luces que tienen un alcance limitado L . Presentamos algunos resultados sobre polígonos escalera con luces situadas en sus vé [...] rtices. En el resultado principal se demuestra que si P es un polígono escalera con n vértices, [n/4]+O(l) luces vértice de alcance L son siempre suficiente y a veces necesarias para iluminar P con L[r/2,r), donde r es el radio de P . Abstract in english The usual definition of visibility in Art Gallery Problems uses guards or light sources that can watch or illuminate with unlimited range. In this paper we consider light sources having a limited range L . We present some results about staircase polygons with light sources placed in its vertices. Th [...] e main result that we prove is that if P is a staircase polygon of n vertices, then [n/4]+O(l) vertex light sources with range L are always sufficient and sometimes necessary to illuminate P when L [r/,2r), where r is the radius of P .

  11. Wide spectral range imaging acousto-optic turnable filter used in outer space probe

    Science.gov (United States)

    Zhang, Zehong; Wang, Liangqiu; He, Xiaoliang; Zhou, Yong

    2014-02-01

    This article introduces a wide spectral range imaging acousto-optic turnable filter made of two transducers. "Mismatch rate" was firstly put forward to represent the degree to which the impedance mismatch and a three stage matching circuit was designed for the filter to improve its spectral range and operating bandwidth. Now the spectral range is from 0.4?m to 1.1?m, the overall operating bandwidth reaches 1.14 octave, the diffraction efficiency over 60%, spectral resolution from 1.3nm to 7.5nm. To get rid of " tin pest", alloy material was used to make bonding layer material instead of pure tin, making the storage temperature of the acousto-optic turnable filter ranges from -65 °C to 85 °C, and the operating temperature from -35 °C to 70 °C.

  12. External quantum efficiency of Pt/n-GaN Schottky diodes in the spectral range 5-500nm

    International Nuclear Information System (INIS)

    The external quantum efficiency in the spectral wavelength range 5-500nm of a large active area Pt/n-type GaN Schottky photodiode that exhibits low reverse bias leakage current, is reported. The Schottky photodiodes were fabricated from n-/n+ epitaxial layers grown by low pressure metalorganic vapour phase epitaxy on single crystal c-plane sapphire. The current-voltage (I-V) characteristics of several 0.25cm2 devices are presented together with the capacitance-voltage (C-V) characteristics of one of these devices. A leakage current as low as 14 pA at 0.5V reverse bias is reported, for a 0.25cm2 diode. The ultraviolet quantum efficiency measurements show that the diodes can be used as radiation hard detectors for the 5-365nm spectral range without the use of visible blocking filters. A peak responsivity of 77.5mA/W at 320nm is reported for one of the fabricated devices, corresponding to a spectral detectivity, D*=1.5x1014cmHz1/2W-1. The average detectivity between 250 and 350nm, for the same device, is reported to be D-bar*=1.3x1014cmHz1/2W-1. The spatial responsivity uniformity variation was established, using H2 Lyman-? radiation, to be +/-3% across the surface of a typical 0.25cm2 diode

  13. Demonstration of a spatial-spectral holographic LIDAR range-Doppler processor

    International Nuclear Information System (INIS)

    We present a new approach to laser interferometric Doppler and ranging (LIDAR) processing using spatial-spectral holography (SSH). In this approach, broadband optical signals from a random noise or frequency-modulated laser are transmitted and reflected off remote targets. The return signals interfere spatially and spectrally with a local copy of the original transmit signal in an SSH medium, resulting in spectral gratings that have a spectral period inversely proportional to the LIDAR target's range and a position proportional to the target's Doppler (or velocity). These gratings are subsequently read out by a slowly chirped source onto a parallel detector array, and the velocity and range of the targets are inferred. We present the theoretical framework that describes the function of the LIDAR processor, as well as proof-of-concept experimental results

  14. Partially Transparent Petaled Mask/Occulter for Visible-Range Spectrum

    Science.gov (United States)

    Shiri, Ron Shahram; Wasylkiwskyj, Wasyl

    2013-01-01

    The presence of the Poisson Spot, also known as the spot of Arago, has been known since the 18th century. This spot is the consequence of constructive interference of light diffracted by the edge of the obstacle where the central position can be determined by symmetry of the object. More recently, many NASA missions require the suppression of this spot in the visible range. For instance, the exoplanetary missions involving space telescopes require telescopes to image the planetary bodies orbiting central stars. For this purpose, the starlight needs to be suppressed by several orders of magnitude in order to image the reflected light from the orbiting planet. For the Earth-like planets, this suppression needs to be at least ten orders of magnitude. One of the common methods of suppression involves sharp binary petaled occulters envisioned to be placed many thousands of miles away from the telescope blocking the starlight. The suppression of the Poisson Spot by binary sharp petal tips can be problematic when the thickness of the tips becomes smaller than the wavelength of the incident beam. First they are difficult to manufacture and also it invalidates the laws of physical optics. The proposed partially transparent petaled masks/occulters compensate for this sharpness with transparency along the surface of the petals. Depending on the geometry of the problem, this transparency can be customized such that only a small region of the petal is transparent and the remaining of the surface is opaque. This feature allows easy fabrication of this type of occultation device either as a mask or occulter. A partially transparent petaled mask/ occulter has been designed for the visible spectrum range. The mask/occulter can suppress the intensity along the optical axis up to ten orders of magnitude. The design process can tailor the mask shape, number of petals, and transparency level to the near-field and farfield diffraction region. The mask/occulter can be used in space astronomy, ground-based telescope, and high-energy laser systems, and optical lithography to eliminate the Poisson Spot.

  15. Multi range spectral feature fitting for hyperspectral imagery in extracting oilseed rape planting area

    Science.gov (United States)

    Pan, Zhuokun; Huang, Jingfeng; Wang, Fumin

    2013-12-01

    Spectral feature fitting (SFF) is a commonly used strategy for hyperspectral imagery analysis to discriminate ground targets. Compared to other image analysis techniques, SFF does not secure higher accuracy in extracting image information in all circumstances. Multi range spectral feature fitting (MRSFF) from ENVI software allows user to focus on those interesting spectral features to yield better performance. Thus spectral wavelength ranges and their corresponding weights must be determined. The purpose of this article is to demonstrate the performance of MRSFF in oilseed rape planting area extraction. A practical method for defining the weighted values, the variance coefficient weight method, was proposed to set up criterion. Oilseed rape field canopy spectra from the whole growth stage were collected prior to investigating its phenological varieties; oilseed rape endmember spectra were extracted from the Hyperion image as identifying samples to be used in analyzing the oilseed rape field. Wavelength range divisions were determined by the difference between field-measured spectra and image spectra, and image spectral variance coefficient weights for each wavelength range were calculated corresponding to field-measured spectra from the closest date. By using MRSFF, wavelength ranges were classified to characterize the target's spectral features without compromising spectral profile's entirety. The analysis was substantially successful in extracting oilseed rape planting areas (RMSE ≤ 0.06), and the RMSE histogram indicated a superior result compared to a conventional SFF. Accuracy assessment was based on the mapping result compared with spectral angle mapping (SAM) and the normalized difference vegetation index (NDVI). The MRSFF yielded a robust, convincible result and, therefore, may further the use of hyperspectral imagery in precision agriculture.

  16. Algorithm development with visible-near-infrared spectral for detection of poultry feces and injesta

    Science.gov (United States)

    The USDA Agricultural Research Service has developed a method and a hyperspectral imaging system to detect feces (from duodenum, ceca and colon) and ingesta on poultry carcasses. The method first involves the use of multivariate data analysis on visible/near-infrared (Vis/NIR) reflectance spectra o...

  17. [Influence of human body target's spectral characteristics on visual range of low light level image intensifiers].

    Science.gov (United States)

    Zhang, Jun-Ju; Yang, Wen-Bin; Xu, Hui; Liu, Lei; Tao, Yuan-Yaun

    2013-11-01

    To study the effect of different human target's spectral reflective characteristic on low light level (LLL) image intensifier's distance, based on the spectral characteristics of the night-sky radiation and the spectral reflective coefficients of common clothes, we established a equation of human body target's spectral reflective distribution, and analyzed the spectral reflective characteristics of different human targets wearing the clothes of different color and different material, and from the actual detection equation of LLL image intensifier distance, discussed the detection capability of LLL image intensifier for different human target. The study shows that the effect of different human target's spectral reflective characteristic on LLL image intensifier distance is mainly reflected in the average reflectivity rho(-) and the initial contrast of the target and the background C0. Reflective coefficient and spectral reflection intensity of cotton clothes are higher than polyester clothes, and detection capability of LLL image intensifier is stronger for the human target wearing cotton clothes. Experimental results show that the LLL image intensifiers have longer visual ranges for targets who wear cotton clothes than targets who wear same color but polyester clothes, and have longer visual ranges for targets who wear light-colored clothes than targets who wear dark-colored clothes. And in the full moon illumination conditions, LLL image intensifiers are more sensitive to the clothes' material. PMID:24555382

  18. Air-suspended TiO2-based HCG reflectors for visible spectral range

    Science.gov (United States)

    Hashemi, Ehsan; Bengtsson, Jörgen; Gustavsson, Johan; Carlsson, Stefan; Rossbach, Georg; Haglund, Åsa

    2015-02-01

    For GaN-based microcavity light emitters, such as vertical-cavity surface-emitting lasers (VCSELs) and resonant cavity light emitting diodes (RCLEDs) in the blue-green wavelength regime, achieving a high reflectivity wide bandwidth feedback mirror is truly challenging. The material properties of the III-nitride alloys are hardly compatible with the conventional distributed Bragg reflectors (DBRs) and the newly proposed high-contrast gratings (HCGs). Alternatively, at least for the top outcoupling mirror, dielectric materials offer more suitable material combinations not only for the DBRs but also for the HCGs. HCGs may offer advantages such as transverse mode and polarization control, a broader reflectivity spectrum than epitaxially grown DBRs, and the possibility to set the resonance wavelength after epitaxial growth by the grating parameters. In this work we have realized an air-suspended TiO2 grating with the help of a SiO2 sacrificial layer. The deposition processes for the dielectric layers were fine-tuned to minimize the residual stress. To achieve an accurate control of the grating duty cycle, a newly developed lift-off process, using hydrogen silesquioxan (HSQ) and sacrificial polymethyl-methacrylate (PMMA) resists, was applied to deposit the hard mask, providing sub-10 nm resolution. The finally obtained TiO2/air HCGs were characterized in a micro-reflectance measurement setup. A peak power reflectivity in excess of 95% was achieved for TM polarization at the center wavelength of 435 nm, with a reflectivity stopband width of about 80 nm (FWHM). The measured HCG reflectance spectra were compared to corresponding simulations obtained from rigorous coupled-wave analysis and very good agreement was found.

  19. Time-resolved photoluminescence spectroscopy of semiconductors for optical applications beyond the visible spectral range

    Energy Technology Data Exchange (ETDEWEB)

    Chernikov, Alexey A.

    2011-07-01

    The work discussed in this thesis is focused on the experimental studies regarding these three steps: (1) investigation of the fundamental effects, (2) characterization of new material systems, and (3) optimization of the semiconductor devices. In all three cases, the experimental technique of choice is photoluminescence (PL) spectroscopy. The thesis is organized as follows. Chapter 2 gives a summary of the PL properties of semiconductors relevant for this work. The first section deals with the intrinsic processes in an ideal direct band gap material, starting with a brief summary of the theoretical background followed by the overview of a typical PL scenario. In the second part of the chapter, the role of the lattice-vibrations, the internal electric fields as well as the influence of the band-structure and the dielectric environment are discussed. Finally, extrinsic PL properties are presented in the third section, focusing on defects and disorder in real materials. In chapter 3, the experimental realization of the spectroscopic studies is discussed. The time-resolved photoluminescence (TRPL) setup is presented, focusing on the applied excitation source, non-linear frequency mixing, and the operation of the streak camera used for the detection. In addition, linear spectroscopy setup for continous-wave (CW) PL and absorption measurements is illustrated. Chapter 4 aims at the study of the interactions between electrons and lattice-vibrations in semiconductor crystals relevant for the proper description of carrier dynamics as well as the heat-transfer processes. The presented discussion covers the experimental studies of many-body effects in phonon-assisted emission of semiconductors due to the carriercarrier Coulomb-interaction. The corresponding theoretical background is discussed in detail in chapter 2. The investigations are focused on the two main questions regarding electron-hole plasma contributions to the phonon-assisted light-matter interaction as well as the impact of Coulomb-correlations on the carrier-phonon scattering. The experiments presented in chapter 5 deal with the characterization of recently synthesizedmaterial systems: ZnO/(ZnMg)O heterostructures, GaN quantum wires (QWires), as well as (GaAs)Bi quantum wells (QWs). TRPL spectroscopy is applied to gain insight as well as a better understanding of the respective carrier relaxation and recombination processes crucial for the device operation. The aim of the studies is the systematic investigation of carrier dynamics influenced by disorder. The measurements are supported by kinetic Monte- Carlo simulations, providing a quantitative analysis of carrier localization effects. In chapter 6, optimization and characterization studies of semiconductor lasers, based on the well-studied (GaIn)As material system designed for NIR applications, are performed. The device under investigation is the so-called vertical-external-cavity surface emitting laser (VECSEL). The experiments focus on the study of the thermal properties of a high-power VECSEL. The distribution and removal of the excess heat as well as the optimization of the laser for increased performance are addressed applying different heat-spreading and heat-transfer approaches. Based on these investigations, the possibility for power-scaling is evaluated and the underlying restrictions are analyzed. The latter investigations are performed applying spatially-resolved PL spectroscopy. An experimental setup is designed for monitoring the spatial distribution of heat in the semiconductor structure during laser operation.

  20. AlGaInP quantum dots for optoelectronic applications in the visible spectral range

    International Nuclear Information System (INIS)

    The scope of this work is the fabrication and characterization of AlGaInP quantum dots on GaP an GaAs substrates. Based on such quantum dots, semiconductor lasers have been realized, emitting between 660 nm and 730 nm at room temperature. The examination of broad-area lasers processed on these structures suggests that active layers of larger quantum dots with higher aluminium contents lead to lasers with better performance at similar emission wavelength. Additionally, quantum dots grown on GaP substrates have been characterized, that were embedded in AlGaP barriers. Since these barriers exhibit an indirect bandgap, a non-trivial band alignment within these structures is expected. In this work, numerical 3D-simulations are employed to calculate the band alignment including strain and internal fields. Also, ground state wavefunctions of charge carriers have been determined. A thorough comparison between theory and experiment connects the measured emission wavelength and luminescence intensities with calculated transition energies and wavefunction overlaps.

  1. Continuous Spatial Tuning of Laser Emissions in a Full Visible Spectral Range

    OpenAIRE

    Mi-Yun Jeong; Jeong Weon Wu

    2011-01-01

    In order to achieve a continuous tuning of laser emission, the authors designed and fabricated three types of cholesteric liquid crystal cells with pitch gradient, a wedge cell with positive slope, a wedge cell with negative slope, and a parallel cell. The length of the cholesteric liquid crystal pitch could be elongated up to 10 nm, allowing the lasing behavior of continuous or discontinuous spatial tuning determined by the boundary conditions of the cholesteric liquid crystal cell. In the w...

  2. MEMS-based Tunable Optical Filter Arrays for Nano-Spectrometer in the Visible Spectral Range

    OpenAIRE

    Setyawati, Onny

    2012-01-01

    Optische Spektrometer sind bekannte Instrumente für viele Anwendungen in Life Sciences, Produktion und Technik aufgrund ihrer guten Selektivität und Sensitivität zusammen mit ihren berührungslosen Messverfahren. MEMS (engl. Micro-electro-mechanical system)-basierten Spektrometer werden als disruptive Technologie betrachtet, in der miniaturisierte Fabry-Pérot Filter als sehr attraktiv für die optische Kommunikation und 'Smart Personal Environments', einschließlich des medizinischen Anwendun...

  3. Time-resolved photoluminescence spectroscopy of semiconductors for optical applications beyond the visible spectral range

    OpenAIRE

    Chernikov, Alexey A.

    2012-01-01

    Since the development of the first light-emitting diodes (LEDs) in the early 1960’s [1, 2], opto-electronic technology based on the semiconducting materials evolved rapidly in the last half of the century. Today, barely all aspects of the generation, control, and detection of light are potentially covered by the solid-state semiconductor devices. The reason is a unique combination of flexibility, low-cost fabrication, as well as c...

  4. Generation of pulsed light in the visible spectral region based on non-linear cavity dumping

    DEFF Research Database (Denmark)

    Johansson, Sandra; Andersen, Martin; Tidemand-Lichtenberg, Peter; Janousek, Jiri; Buchhave, Preben; Laurell, Fredrik

    passively Q-switched 1064 nm laser to generate pulsed light at 593 nm. Light sources in the yellow spectral region have several applications, e.g. dermatology, laser displays and flow cytometry. Traditionally, copper-vapor lasers at 578 nm and dye lasers are used in this spectral region. These are however...... bulky, inefficient and contain highly toxic gasses and liquids. Different approaches to replace these are: frequency-doubled semiconductor lasers1, sum-frequency generation between solid-state lasers in both in CW2 and Q-switched3 operation and Raman lasers4. An intra-cavity 1342 nm Nd:YVO4 laser acted...

  5. Comparison of plasma visible spectral emissions between Nova-UNICAMP and TCABR tokamaks

    International Nuclear Information System (INIS)

    A comparison between the visible spectrum emissions observed on the Nova-UNICAMP and TCABR tokamak plasmas has been made in this work using a hand top HR4000 Ocean Optics spectrometer equipped with a CCD detector. A number of 58 emission lines, in which 22 are common to both machines, have been observed and identified. The differences in the observed spectrum can be explained by the difference in the time integration used in these measurements and by the materials compositions of the limiter and electrode in the TCABR tokamak. Nearby peak emissions have been separated using multi-peak Gaussian fit curves obtaining separation between peak centres with the same order of the spectrometer resolution. The HR4000 spectrometer can be routinely used to monitor the impurity species in the visible spectrum from the different tokamak windows.

  6. Comparison of Plasma Visible Spectral Emissions Between Nova-UNICAMP and TCABR Tokamaks

    Science.gov (United States)

    do Nascimento, F.; Machida, M.; Ronchi, G.; Schmutzler, L. M. F.; Severo, J. H. F.; Nascimento, I. C.; Sanada, E. K.

    2014-05-01

    A comparison between the visible spectrum emissions observed on the Nova-UNICAMP and TCABR tokamak plasmas has been made in this work using a hand top HR4000 Ocean Optics spectrometer equipped with a CCD detector. A number of 58 emission lines, in which 22 are common to both machines, have been observed and identified. The differences in the observed spectrum can be explained by the difference in the time integration used in these measurements and by the materials compositions of the limiter and electrode in the TCABR tokamak. Nearby peak emissions have been separated using multi-peak Gaussian fit curves obtaining separation between peak centres with the same order of the spectrometer resolution. The HR4000 spectrometer can be routinely used to monitor the impurity species in the visible spectrum from the different tokamak windows.

  7. Dispersion model for optical thin films applicable in wide spectral range

    Science.gov (United States)

    Franta, Daniel; Ne?as, David; Ohlídal, Ivan; Giglia, Angelo

    2015-09-01

    In the optics industry thin film systems are used to construct various interference devices such as antireflective coatings, high-reflectance mirrors, beam splitters and filters. The optical characterization of complex optical systems can not be performed by measurements only in the short spectral range in which the interference devices will be employed because the measured data do not contain sufficient information about all relevant parameters of these systems. The characterization of film materials requires the extension of the spectral range of the measurements to the IR region containing phonon absorption and to the UV region containing the electronic excitations. However, this leads to necessity of a dispersion model suitable for the description of the dielectric response in the wide spectral range. Such model must respect the physical conditions following from theory of dispersion, particularly Kramers-Kronig relations and integrability imposed by sum rules. This work presents the construction of a universal dispersion model composed from individual contributions representing both electronic and phonon excitations. The efficiency of presented model is given by the fact that all the contributions are described by analytical expressions. It is shown that the model is suitable for precise modeling of spectral dependencies of optical constants of a broad class of materials used in the optical industry for thin film systems such as MgF2, SiO2, Al2O3, HfO2, Ta2O5 and TiO2 in the spectral range from far IR to vacuum UV.

  8. Polylogarithmic Representation of Radiative and Thermodynamic Properties of Thermal Radiation in a Given Spectral Range: II. Real-Body Radiation

    Science.gov (United States)

    Fisenko, Anatoliy I.; Lemberg, Vladimir

    2015-10-01

    There are several classes of materials and space objects for which the frequency dependence of the spectral emissivity is represented as a power series. Therefore, the study of the properties of thermal radiation for these real bodies is an important task for both fundamental science and industrial applications. The general analytical expressions for the thermal radiative and thermodynamic functions of a real body are obtained in a finite range of frequencies at different temperatures. The Stefan-Boltzmann law, total energy density, number density of photons, Helmholtz free energy density, internal energy density, enthalpy density, entropy density, heat capacity at constant volume, pressure, and total emissivity are expressed in terms of the polylogarithm functions. The obtained general expressions for the thermal radiative and thermodynamic functions are applied for the study of thermal radiation of liquid and solid zirconium carbide. These functions are calculated using experimental data for the frequency dependence of the normal spectral emissivity in the visible and near-infrared range at the melting (freezing) point. The gaps between the thermal radiative and thermodynamic functions of liquid and solid zirconium carbide are observed. The general analytical expressions obtained can easily be presented in the wavenumber domain.

  9. Visible light optical coherence tomography for in vivo imaging the spectral contrasts of the retinal nerve fiber layer

    Science.gov (United States)

    Zhang, Xiangyang; Hu, Jianming; Knighton, Robert W.; Huang, Xiang-Run; Puliafito, Carmen A.; Jiao, Shuliang

    2012-01-01

    The ultimate goal of the study is to provide an imaging tool to detect the earliest signs of glaucoma before clinically visible damage occurs to the retinal nerve fiber layer (RNFL). Studies have shown that the optical reflectance of the damaged RNFL at short wavelength (RNFL. To image the spectral contrasts we built a dual-band spectral-domain optical coherence tomography (SD-OCT) with centered wavelength of 415nm (VIS) and 808nm (NIR), respectively. The light at the two bands was provided by the fundamental and frequency-doubled outputs of a broadband Ti: Sapphire laser. The depth resolutions of the VIS and NIR OCT systems are 12.2?m and 4.7?m in the air. The system was applied to imaging the rat retina in vivo. Significantly different appearances between the OCT cross sectional images at the two bands are observed. The experimental results showed that the dual-band OCT system is feasible for imaging the spectral contrasts of the RNFL.

  10. Fabrication of Wide–Range–Visible Photocatalyst Bi2WO6?x nanoplates via Surface Oxygen Vacancies

    Science.gov (United States)

    Lv, Yanhui; Yao, Wenqing; Zong, Ruilong; Zhu, Yongfa

    2016-01-01

    Bi2WO6 as a high visible-light-driven catalyst has been aroused broad interest. However, it can only be excitated by the light with ??range–visible photoresponse Bi2WO6?x nanoplates were fabricated by introducing surface oxygen vacancies through the controllable hydrogen reduction method. The visible photoresponse wavelength range is extended from 450?nm to more than 600?nm. In addition, the photocatalytic activity of Bi2WO6?x is also increased and is 2.1 times as high as that of pristine Bi2WO6. The extending of the photoresponse range and the enhancement of the photoactivity both can be attributed to the surface-oxygen-vacancy states. This is because surface-oxygen–vacancy states generated above and partly overlapping of with the valence band (VB) will result in the rising of valence band maximum (VBM), thus broadening the VB width. This approach is proposed to develop many types of wide–range–visible optical materials and to be applicable to many narrow and wide bandgap materials. PMID:26777609

  11. Fabrication of Wide-Range-Visible Photocatalyst Bi2WO6-x nanoplates via Surface Oxygen Vacancies.

    Science.gov (United States)

    Lv, Yanhui; Yao, Wenqing; Zong, Ruilong; Zhu, Yongfa

    2016-01-01

    Bi2WO6 as a high visible-light-driven catalyst has been aroused broad interest. However, it can only be excitated by the light with ??range-visible photoresponse Bi2WO6-x nanoplates were fabricated by introducing surface oxygen vacancies through the controllable hydrogen reduction method. The visible photoresponse wavelength range is extended from 450?nm to more than 600?nm. In addition, the photocatalytic activity of Bi2WO6-x is also increased and is 2.1 times as high as that of pristine Bi2WO6. The extending of the photoresponse range and the enhancement of the photoactivity both can be attributed to the surface-oxygen-vacancy states. This is because surface-oxygen-vacancy states generated above and partly overlapping of with the valence band (VB) will result in the rising of valence band maximum (VBM), thus broadening the VB width. This approach is proposed to develop many types of wide-range-visible optical materials and to be applicable to many narrow and wide bandgap materials. PMID:26777609

  12. First Experiences Using Small Unmanned Aerial Vehicles for Volcano Observation in the Visible Range

    Science.gov (United States)

    Buschmann, M.; Krüger, L.; Bange, J.

    2007-05-01

    Many of the most active volcanoes in the world are located in Middle and South America. While permanently installed sensors for seismicity give reliable supervision of volcanic activities, they lack the possibility to determine occurrence and extent of surface activities. Both from the point of science and civil protection, visible documentation of activities is of great interest. While satellites and manned aircraft already offer many possibilities, they also have disadvantages like delayed or poor image data availability or high costs. The Institute of Aerospace Systems of the Technical University of Braunschweig, in collaboration with the spin-off company Mavionics, developed a family of extremely small and lightweight Unmanned Aerial Vehicles (UAV), with the smallest aircraft weighting only 550~g (19~ounces) at a wing span of 50 cm (20~inch). These aircraft are operating completely automatically, controlled by a highly miniaturized autopilot system. Flight mission is defined by a list of GPS waypoints using a conventional notebook. While in radio range, current position and status of the aircraft is displayed on the notebook and waypoints can easily be changed by the user. However, when radio connection is not available, the aircraft operates on its on, completing the flight mission automatically. This greatly increases the operating range of the system. Especially for the purpose of volcano observation in South America, the aircraft Carolo~P330 was developed, weighting 5~kg (11~pounds) at a wing span of 3.3~m ( 11~ft). The whole system can be easily carried by car and the electric propulsion system avoids handling of flammable liquids. The batteries can be recharged in the field. Carolo~P330 has an endurance of up to 90~minutes at a flight speed of 25~m/s, giving it a maximum range of 67 km (41~miles). It was especially designed to operate under harsh conditions. The payload is a digital still camera, which delivers aerial images with a resolution of up to 8~megapixel. On a field campaign in 2005, the performance of the system was evaluated at the two active Ecuadorian volcanoes Cotopaxi and El~Reventador. After hand-launch at Mt. Cotopaxi, the autopilot brought the aircraft up to 7,000~m above sea level (starting from a plateau on 4,500~m a.s.l.), with temperatures around the freezing point. At El~Reventador active lava flows were documented in the tropical montane rain forest. Since the position and attitude of the aircraft is recorded within the autopilot system, the single aerial images can be referenced automatically after the flight to form a mosaic of images. The whole processing chain from mission planning to image mosaic takes less than half a day. Besides the technical details of this cost-effective remote sensing system, the results of the measurement campaign in 2005 will be presented. An outlook will discuss the installation of other payload for thermal imaging or air sampling.

  13. Optical properties of human colon tissues in the 350 – 2500 nm spectral range

    Energy Technology Data Exchange (ETDEWEB)

    Bashkatov, A N; Genina, E A; Kochubey, V I; Kolesnikova, E A; Tuchin, V V [N.G. Chernyshevsky Saratov State University, Saratov (Russian Federation); Rubtsov, V S [V.I.Razumovsky Saratov State Medical University, Saratov (Russian Federation)

    2014-08-31

    We present the optical characteristics of the mucosa and submucosa of human colon tissue. The experiments are performed in vitro using a LAMBDA 950 spectrophotometer in the 350 – 2500 nm spectral range. The absorption and scattering coefficients and the scattering anisotropy factor are calculated based on the measured diffuse reflectance and total and collimated transmittance spectra using the inverse Monte Carlo method. (laser biophotonics)

  14. Composite multi-lobe descriptor for cross spectral face recognition: matching active IR to visible light images

    Science.gov (United States)

    Cao, Zhicheng; Schmid, Natalia A.

    2015-05-01

    Matching facial images across electromagnetic spectrum presents a challenging problem in the field of biometrics and identity management. An example of this problem includes cross spectral matching of active infrared (IR) face images or thermal IR face images against a dataset of visible light images. This paper describes a new operator named Composite Multi-Lobe Descriptor (CMLD) for facial feature extraction in cross spectral matching of near-infrared (NIR) or short-wave infrared (SWIR) against visible light images. The new operator is inspired by the design of ordinal measures. The operator combines Gaussian-based multi-lobe kernel functions, Local Binary Pattern (LBP), generalized LBP (GLBP) and Weber Local Descriptor (WLD) and modifies them into multi-lobe functions with smoothed neighborhoods. The new operator encodes both the magnitude and phase responses of Gabor filters. The combining of LBP and WLD utilizes both the orientation and intensity information of edges. Introduction of multi-lobe functions with smoothed neighborhoods further makes the proposed operator robust against noise and poor image quality. Output templates are transformed into histograms and then compared by means of a symmetric Kullback-Leibler metric resulting in a matching score. The performance of the multi-lobe descriptor is compared with that of other operators such as LBP, Histogram of Oriented Gradients (HOG), ordinal measures, and their combinations. The experimental results show that in many cases the proposed method, CMLD, outperforms the other operators and their combinations. In addition to different infrared spectra, various standoff distances from close-up (1.5 m) to intermediate (50 m) and long (106 m) are also investigated in this paper. Performance of CMLD is evaluated for of each of the three cases of distances.

  15. Evaluation of water-use efficiency in foxtail millet (Setaria italica) using visible-near infrared and thermal spectral sensing techniques.

    Science.gov (United States)

    Wang, Meng; Ellsworth, Patrick Z; Zhou, Jianfeng; Cousins, Asaph B; Sankaran, Sindhuja

    2016-05-15

    Water limitations decrease stomatal conductance (gs) and, in turn, photosynthetic rate (Anet), resulting in decreased crop productivity. The current techniques for evaluating these physiological responses are limited to leaf-level measures acquired by measuring leaf-level gas exchange. In this regard, proximal sensing techniques can be a useful tool in studying plant biology as they can be used to acquire plant-level measures in a high-throughput manner. However, to confidently utilize the proximal sensing technique for high-throughput physiological monitoring, it is important to assess the relationship between plant physiological parameters and the sensor data. Therefore, in this study, the application of rapid sensing techniques based on thermal imaging and visual-near infrared spectroscopy for assessing water-use efficiency (WUE) in foxtail millet (Setaria italica (L.) P. Beauv) was evaluated. The visible-near infrared spectral reflectance (350-2500nm) and thermal (7.5-14µm) data were collected at regular intervals from well-watered and drought-stressed plants in combination with other leaf physiological parameters (transpiration rate-E, Anet, gs, leaf carbon isotopic signature-δ(13)Cleaf, WUE). Partial least squares regression (PLSR) analysis was used to predict leaf physiological measures based on the spectral data. The PLSR modeling on the hyperspectral data yielded accurate and precise estimates of leaf E, gs, δ(13)Cleaf, and WUE with coefficient of determination in a range of 0.85-0.91. Additionally, significant differences in average leaf temperatures (~1°C) measured with a thermal camera were observed between well-watered plants and drought-stressed plants. In summary, the visible-near infrared reflectance data, and thermal images can be used as a potential rapid technique for evaluating plant physiological responses such as WUE. PMID:26992551

  16. Development of a Compact Range-gated Vision System to Monitor Structures in Low-visibility Environments

    International Nuclear Information System (INIS)

    Image acquisition in disaster area or radiation area of nuclear industry is an important function for safety inspection and preparing appropriate damage control plans. So, automatic vision system to monitor structures and facilities in blurred smoking environments such as the places of a fire and detonation is essential. Vision systems can't acquire an image when the illumination light is blocked by disturbance materials, such as smoke, fog and dust. To overcome the imaging distortion caused by obstacle materials, robust vision systems should have extra-functions, such as active illumination through disturbance materials. One of active vision system is a range-gated imaging system. The vision system based on the range-gated imaging system can acquire image data from the blurred and darken light environments. Range-gated imaging (RGI) is a direct active visualization technique using a highly sensitive image sensor and a high intensity illuminant. Currently, the range-gated imaging technique providing 2D and range image data is one of emerging active vision technologies. The range-gated imaging system gets vision information by summing time sliced vision images. In the RGI system, a high intensity illuminant illuminates for ultra-short time and a highly sensitive image sensor is gated by ultra-short exposure time to only get the illumination light. Here, the illuminant illuminates objects by flashing strong light through disturbance materials, such as smoke particles and dust particles. In contrast to passive conventional vision systems, the RGI active vision technology enables operation even in harsh environments like low-visibility smoky environment. In this paper, a compact range-gated vision system is developed to monitor structures in low-visibility environment. The system consists of illumination light, a range-gating camera and a control computer. Visualization experiments are carried out in low-visibility foggy environment to see imaging capability

  17. Aerosol Retrieval from Multiangle Multispectral Photopolarimetric Measurements: Importance of Spectral Range and Angular Resolution

    Science.gov (United States)

    Wu, L.; Hasekamp, O.; Van Diedenhoven, B.; Cairns, B.

    2015-01-01

    We investigated the importance of spectral range and angular resolution for aerosol retrieval from multiangle photopolarimetric measurements over land. For this purpose, we use an extensive set of simulated measurements for different spectral ranges and angular resolutions and subsets of real measurements of the airborne Research Scanning Polarimeter (RSP) carried out during the PODEX and SEAC4RS campaigns over the continental USA. Aerosol retrievals performed from RSP measurements show good agreement with ground-based AERONET measurements for aerosol optical depth (AOD), single scattering albedo (SSA) and refractive index. Furthermore, we found that inclusion of shortwave infrared bands (1590 and/or 2250 nm) significantly improves the retrieval of AOD, SSA and coarse mode microphysical properties. However, accuracies of the retrieved aerosol properties do not improve significantly when more than five viewing angles are used in the retrieval.

  18. Radiometric calibration of optical microscopy and microspectroscopy apparata over a broad spectral range using a special thin-film luminescence standard

    Directory of Open Access Journals (Sweden)

    J. Valenta

    2015-04-01

    Full Text Available Application capabilities of optical microscopes and microspectroscopes can be considerably enhanced by a proper calibration of their spectral sensitivity. We propose and demonstrate a method of relative and absolute calibration of a microspectroscope over an extraordinary broad spectral range covered by two (parallel detection branches in visible and near-infrared spectral regions. The key point of the absolute calibration of a relative spectral sensitivity is application of the standard sample formed by a thin layer of Si nanocrystals with stable and efficient photoluminescence. The spectral PL quantum yield and the PL spatial distribution of the standard sample must be characterized by separate experiments. The absolutely calibrated microspectroscope enables to characterize spectral photon emittance of a studied object or even its luminescence quantum yield (QY if additional knowledge about spatial distribution of emission and about excitance is available. Capabilities of the calibrated microspectroscope are demonstrated by measuring external QY of electroluminescence from a standard poly-Si solar-cell and of photoluminescence of Er-doped Si nanocrystals.

  19. Metasurfaces based on Gallium Nitride High Contrast Gratings at Visible Range

    Science.gov (United States)

    Wang, Zhenhai; He, Shumin; Liu, Qifa; Wang, Wei; Wang, Yongjin; Zhu, Hongbo; Grünberg Research Centre Team

    2015-03-01

    Metasurfaces are currently attracting global attention due to their ability to achieve full control of light propagation. However, these metasurfaces have thus far been constructed mostly from metallic materials, which greatly limit the diffraction efficiencies because of the ohmic losses. Semiconducting metasurfaces offer one potential solution to the issue of losses. Besides, the use of semiconducting materials can broaden the applicability of metasurfaces, as they enable facile integration with electronics and mechanical systems and can benefit from mature semiconductor fabrication technologies. We have proposed visible-light metasurfaces (VLMs) capable of serving as lenses and beam deflecting elements based on gallium nitride (GaN) high contrast gratings (HCGs). By precisely manipulating the wave-fronts of the transmitted light, we theoretically demonstrate an HCG focusing lens with transmissivity of 83.0% and numerical aperture of 0.77, and a VLM with beam deflection angle of 6.03° and transmissivity as high as 93.3%. The proposed metasurfaces are promising for GaN-based visible light-emitting diodes (LEDs), which would be robust and versatile for controlling the output light propagation and polarization, as well as enhancing the extraction efficiency of the LEDs.

  20. Study on the Incidence of Opportunity Crime on Residential Streets Considering Traffic Volume and Visible Range

    Directory of Open Access Journals (Sweden)

    Chiaki MATSUNAGA

    2011-11-01

    Full Text Available As a basic step, in this study we propose a model to describe the snatchincident on residential streets. This model is based on one of themethodologies of social science and the Crime Prevention ThroughEnvironmental Design’s concept. The objective variable is the feasibility ofsnatch and explanatory variables are physical factors concerning roadnetwork design and traffic regulation, like traffic volume and visible rangeon streets.As the result of the application to actual situations, the model providedreasonable predictions for distribution of point of incidence in a streetsection. It is possible to examine the influence that road network design andtraffic regulation have on snatch by extending this model to road network.

  1. Eta Carinae across the 2003.5 Minimum: Analysis in the Visible and Near Infrared Spectral Region

    Science.gov (United States)

    Nielsen, K. E.; Kober, G. Vieira; Weis, K.; Gull, T. R.; Stahl, O.; Bomans, D. J.

    2009-01-01

    We present an analysis of the visible through near infrared spectrum of Eta Car and its ejecta obtained during the "Eta Car Campaign with the Ultraviolet and Visual Echelle Spectrograph (UVES) at the ESO Very Large Telescope (VLT)". This is a part of the larger effort to present a complete Eta Car spectrum, and extends the previously presented analyses with the Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS) in the UV (1240-3159 Angstrom) to 10,430 Angstrom. The spectrum in the mid and near UV is characterized by the ejecta absorption. At longer wavelengths, stellar wind features from the central source and narrow emission lines from the Weigelt condensations dominate the spectrum. However, narrow absorption lines from the circumstellar shells are present. This paper provides a description of the spectrum between 3060 and 10,430 Angstroms, including line identifications of the ejecta absorption spectrum, the emission spectrum from the Weigelt condensations and the P-Cygni stellar wind features. The high spectral resolving power of VLT/UVES enables equivalent width measurements of atomic and molecular absorption lines for elements with no transitions at the shorter wavelengths. However, the ground based seeing and contributions of nebular scattered radiation prevent direct comparison of measured equivalent widths in the VLT/UVES and HST/STIS spectra. Fortunately, HST/STIS and VLT/UVES have a small overlap in wavelength coverage which allows us to compare and adjust for the difference in scattered radiation entering the instruments' apertures. This paper provides a complete online VLT/UVES spectrum with line identifications and a spectral comparison between HST/STIS and VLT/UVES between 3060 and 3160 Angstroms.

  2. ETA CARINAE ACROSS THE 2003.5 MINIMUM: ANALYSIS IN THE VISIBLE AND NEAR-INFRARED SPECTRAL REGION

    International Nuclear Information System (INIS)

    We present an analysis of the visible through near-infrared spectrum of Eta Carinae (? Car) and its ejecta obtained during the '? Car Campaign with the Ultraviolet and Visual Echelle Spectrograph (UVES) at the ESO Very Large Telescope (VLT)'. This is a part of larger effort to present a complete ? Car spectrum, and extends the previously presented analyses with the Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS) in the UV (1240-3159 A) to 10,430 A. The spectrum in the mid- and near-UV is characterized by the ejecta absorption. At longer wavelengths, stellar wind features from the central source and narrow-emission lines from the Weigelt condensations dominate the spectrum. However, narrow absorption lines from the circumstellar shells are present. This paper provides a description of the spectrum between 3060 and 10,430 A, including line identifications of the ejecta absorption spectrum, the emission spectrum from the Weigelt condensations and the P Cygni stellar wind features. The high spectral resolving power of VLT/UVES enables equivalent width measurements of atomic and molecular absorption lines for elements with no transitions at the shorter wavelengths. However, the ground-based seeing and contributions of nebular-scattered radiation prevent direct comparison of measured equivalent widths in the VLT/UVES and HST/STIS spectra. Fortunately, HST/STIS and VLT/UVES have a small overlap in wavelength coverage which allows us to compare and adjust for the difference in scattered radiation entering the instruments' apertures. This paper provides a complete online VLT/UVES spectrum with line identifications and a spectral comparison between HST/STIS and VLT/UVES between 3060 and 3160 A.

  3. Integration of visible-through microwave-range multispectral image data sets for geologic mapping

    Science.gov (United States)

    Kruse, Fred A.; Dietz, John B.

    1991-01-01

    Multispectral remote sensing data sets collected during the Geologic Remote Sensing Field Experiment (GRSFE) conducted during 1989 in the southwestern U.S. were used to produce thematic image maps showing details of the surface geology. LANDSAT TM (Thematic Mapper) images were used to map the distribution of clays, carbonates, and iron oxides. AVIRIS (Airborne Visible/Infrared Imaging Spectrometer) data were used to identify and map calcite, dolomite, sericite, hematite, and geothite, including mixtures. TIMS (Thermal Infrared Multispectral Scanner) data were used to map the distribution of igneous rock phases and carbonates based on their silica contents. AIRSAR (Airborne Synthetic Aperture Radar) data were used to map surface textures related to the scale of surface roughness. The AIRSAR also allowed identification of previously unmapped fault segments and structural control of lithology and minerology. Because all of the above data sets were geographically referenced, combination of different data types and direct comparison of the results with conventional field and laboratory data sets allowed improved geologic mapping of the test site.

  4. Eta Carinae across the 2003.5 Minimum: Analysis in the visible and near infrared spectral region

    CERN Document Server

    Nielsen, K E; Weis, K; Gull, T R; Stahl, O; Bomans, D J

    2009-01-01

    We present an analysis of the visible through near infrared spectrum of Eta Carinae and its ejecta obtained during the "Eta Carinae Campaign with the UVES at the ESO VLT". This is a part of larger effort to present a complete Eta Carinae spectrum, and extends the previously presented analyses with the HST/STIS in the UV (1240-3159 A) to 10,430 A. The spectrum in the mid and near UV is characterized by the ejecta absorption. At longer wavelengths, stellar wind features from the central source and narrow emission lines from the Weigelt condensations dominate the spectrum. However, narrow absorption lines from the circumstellar shells are present. This paper provides a description of the spectrum between 3060 and 10,430 A, including line identifications of the ejecta absorption spectrum, the emission spectrum from the Weigelt condensations and the P-Cygni stellar wind features. The high spectral resolving power of VLT/UVES enables equivalent width measurements of atomic and molecular absorption lines for element...

  5. Spectral distribution of UV range diffuse reflectivity for Si+ ion implanted polymers

    Science.gov (United States)

    Balabanov, S.; Tsvetkova, T.; Borisova, E.; Avramov, L.; Bischoff, L.

    2008-05-01

    The analysis of the UV range spectral characteristics can supply additional information on the formed sub-surface buried layer with implanted dopants. The near-surface layer (50÷150 nm) of bulk polymer samples have been implanted with silicon (Si+) ions at low energies (E = 30 keV) and a wide range of ion doses (D = 1.1013 ÷ 1, 2.1017 cm-2). The studied polymer materials were: ultra-high-molecular-weight polyethylene (UHMWPE), poly-methyl-metacrylate (PMMA) and poly-tetra-fluor-ethylene (PTFE). The diffuse optical reflectivity spectra Rd = f(?) of the ion implanted samples have been measured in the UV range (? = 220÷350 nm). In this paper the dose dependences of the size and sign of the diffuse optical reflectivity changes ?Rd = f(D) have been analysed.

  6. Infrared absolute intensities of ozone in the 10 and 5 ?m spectral range: New investigations

    International Nuclear Information System (INIS)

    Infrared high resolution spectra of ozone 16O3 have been recorded in the 10 and 5 ?m spectral ranges in order to derive their absolute intensities with a best achievable accuracy. Spectra have been recorded with the home made stepping mode FTS of GSMA (Reims). In the two spectral regions, we use UV-IR crossed beam cell. The quantification of ozone is achieved using UV cross section at 253.65 nm. A check of this UV calibration is also performed using direct pressure measurements of quasi-pure samples of O3. The intensities are derived from infrared spectra using multifit procedure already tested. In the 10 ?m range, where 12 different spectra have been recorded, 65 well selected lines led to a good agreement (better than 0.3%) with the HITRAN 2008 (or 2004) values, confirming our previous work [De Backer-Barilly MR, Barbe A. Absolute intensities of the 10 ?m bands of 16O3. J Mol Spectrosc 305:2001;43-53]. In the 5 ?m range, where 18 transitions are selected, we also note a correct agreement with HITRAN 2008, despite a slightly larger averaged value between (1.9%) experimental and theoretical (HITRAN). As conclusion, authors suggest the use of current HITRAN 2008 data for atmospheric retrievals.

  7. Photonic crystals and Bragg gratings for the mid-IR and terahertz spectral ranges

    Energy Technology Data Exchange (ETDEWEB)

    Usikova, A. A., E-mail: usikova@mail.ioffe.ru; Il’inskaya, N. D.; Matveev, B. A.; Shubina, T. V.; Kop’ev, P. S. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)

    2013-12-15

    A method for the fabrication of 2D periodic structures by contact optical photolithography with image inversion is reported. The optical properties of photonic crystals and Bragg gratings for mid-IR and terahertz emitters are considered. The possibility of raising the integral emission intensity of light-emitting diodes for the mid-IR spectral range is demonstrated. The requirements to gratings for the output of terahertz emission generated by surface plasmons excited in layers of narrow-gap degenerate semiconductors with an accumulation layer are determined.

  8. Spectral broadening due to long-range Coulomb interactions in the molecular metal TTF-TCNQ

    International Nuclear Information System (INIS)

    We employ density-functional theory to calculate realistic parameters for an extended Hubbard model of the molecular metal TTF-TCNQ. Considering both intra- and intermolecular screening in the crystal, we find that longer-range Coulomb interactions along the molecular stacks, as well as inter-stack coupling are of importance. Contrary to past belief, these terms do not lead to the formation of a Wigner lattice, but simply broaden the spectral function. We show how this can be understood already in perturbation theory. Moreover we calculate the effect of the nearest neighbor repulsion on the Luttinger parameter. (orig.)

  9. Spectral broadening due to long-range Coulomb interactions in the molecular metal TTF-TCNQ

    Energy Technology Data Exchange (ETDEWEB)

    Koch, E.; Dolfen, A. [Inst. fuer Festkoerperforschung, Forschungszentrum Juelich (Germany); Cano-Cortes, L.; Merino, J. [Univ. Autonona de Madrid (Spain); Behler, J.; Reuter, K. [Fritz-Haber-Inst., Berlin (Germany); Delley, B. [Paul-Scherrer-Inst., Villigen (Switzerland)

    2007-07-01

    We employ density-functional theory to calculate realistic parameters for an extended Hubbard model of the molecular metal TTF-TCNQ. Considering both intra- and intermolecular screening in the crystal, we find that longer-range Coulomb interactions along the molecular stacks, as well as inter-stack coupling are of importance. Contrary to past belief, these terms do not lead to the formation of a Wigner lattice, but simply broaden the spectral function. We show how this can be understood already in perturbation theory. Moreover we calculate the effect of the nearest neighbor repulsion on the Luttinger parameter. (orig.)

  10. Dispersion properties and low infrared optical losses in epitaxial AlN on sapphire substrate in the visible and infrared range

    Energy Technology Data Exchange (ETDEWEB)

    Soltani, A., E-mail: ali.soltani@iemn.univ-lille1.fr; Stolz, A.; Gerbedoen, J.-C.; Rousseau, M.; Bourzgui, N.; De Jaeger, J.-C. [Institut d' Électronique, Microélectronique et Nanotechnologie, UMR-CNRS 8520, PRES Université Lille Nord de France, Cité Scientifique, Avenue Poincaré, CS 60069, 59652 Villeneuve d' Ascq Cedex (France); Charrier, J. [Fonctions Optiques pour les Technologies de l' informatiON, UMR-CNRS 6082, ENSSAT 6, rue de Kerampont, CS 80518, 22305 Lannion Cedex (France); Mattalah, M. [Laboratoire de Microélectronique, Université Djilali Liabes, 22000 Sidi Bel Abbes (Algeria); Barkad, H. A. [Institut Universitaire Technologique Industriel, Université de Djibouti, Avenue Georges Clémenceau, BP 1904 Djibouti (Djibouti); Mortet, V. [Institute of Physics of Academy of Sciences of Czech Republic, Fyzikální ústav AV CR, v.v.i., Na Slovance 1999/2 (Czech Republic); BenMoussa, A. [Solar Terrestrial Center of Excellence, Royal Observatory of Belgium, Circular 3, B-1180 Brussels (Belgium)

    2014-04-28

    Optical waveguiding properties of a thick wurtzite aluminum nitride highly [002]-textured hetero-epitaxial film on (001) basal plane of sapphire substrate are studied. The physical properties of the film are determined by X-ray diffraction, atomic force microscopy, microRaman, and photocurrent spectroscopy. The refractive index and the thermo-optic coefficients are determined by m-lines spectroscopy using the classical prism coupling technique. The optical losses of this planar waveguide are also measured in the spectral range of 450–1553 nm. The lower value of optical losses is equal to 0.7 dB/cm at 1553 nm. The optical losses due to the surface scattering are simulated showing that the contribution is the most significant at near infrared wavelength range, whereas the optical losses are due to volume scattering and material absorption in the visible range. The good physical properties and the low optical losses obtained from this planar waveguide are encouraging to achieve a wide bandgap optical guiding platform from these aluminum nitride thin films.

  11. Dispersion properties and low infrared optical losses in epitaxial AlN on sapphire substrate in the visible and infrared range

    Science.gov (United States)

    Soltani, A.; Stolz, A.; Charrier, J.; Mattalah, M.; Gerbedoen, J.-C.; Barkad, H. A.; Mortet, V.; Rousseau, M.; Bourzgui, N.; BenMoussa, A.; De Jaeger, J.-C.

    2014-04-01

    Optical waveguiding properties of a thick wurtzite aluminum nitride highly [002]-textured hetero-epitaxial film on (001) basal plane of sapphire substrate are studied. The physical properties of the film are determined by X-ray diffraction, atomic force microscopy, microRaman, and photocurrent spectroscopy. The refractive index and the thermo-optic coefficients are determined by m-lines spectroscopy using the classical prism coupling technique. The optical losses of this planar waveguide are also measured in the spectral range of 450-1553 nm. The lower value of optical losses is equal to 0.7 dB/cm at 1553 nm. The optical losses due to the surface scattering are simulated showing that the contribution is the most significant at near infrared wavelength range, whereas the optical losses are due to volume scattering and material absorption in the visible range. The good physical properties and the low optical losses obtained from this planar waveguide are encouraging to achieve a wide bandgap optical guiding platform from these aluminum nitride thin films.

  12. Spectral characterisation of Sm{sup 3+} ions doped Oxy-fluoroborate glasses for visible orange luminescent applications

    Energy Technology Data Exchange (ETDEWEB)

    Mahamuda, Sk.; Swapna, K.; Venkateswarlu, M. [Department of Physics, KL University, Green Fields, Vaddeswaram 522502, Guntur (Dt.), AP (India); Srinivasa Rao, A., E-mail: drsrallam@gmail.com [Department of Physics, KL University, Green Fields, Vaddeswaram 522502, Guntur (Dt.), AP (India); Department of Applied Physics, Delhi Technological University, Bawana Road, New Delhi 110042 (India); Shakya, Suman; Vijaya Prakash, G. [Nanophotonics Laboratory, Department of Physics, Indian Institute of Technology-Delhi, Hauz Khas, New Delhi 110016 (India)

    2014-10-15

    Oxy-fluoroborate (OFB) glasses doped with different concentrations of Sm{sup 3+} ions have been prepared using conventional melt quenching technique and characterised for their lasing potentialities using spectroscopic techniques such as FTIR, optical absorption, emission and emission decay measurements. The FTIR spectrum has been recorded to determine the various functional groups present in the OFB base glass. From the absorption spectra, the bonding parameters (?) were evaluated to find the bonding nature present between Sm{sup 3+} ions with its neighbouring ligands. The Judd–Ofelt intensity (J–O) parameters (?{sub ?}, where ?=2, 4, and 6), measured from the experimental oscillator strengths of the absorption spectral futures, are used to evaluate the radiative parameters for the fluorescent transitions {sup 4}G{sub 5/2}?{sup 6}H{sub 5/2}, {sup 4}G{sub 5/2}?{sup 6}H{sub 7/2}, {sup 4}G{sub 5/2}?{sup 6}H{sub 9/2} and {sup 4}G{sub 5/2}?{sup 6}H{sub 11/2} of Sm{sup 3+} ions in OFB glasses. The asymmetric ratio has been evaluated to understand the local disorder of Sm{sup 3+} ions in the glass network. The experimental lifetimes (?{sub exp}) measured from the decay curves are coupled with radiative lifetimes (?{sub rad}) to measure quantum efficiency (?) of the prepared glasses. The experimental lifetimes (?{sub exp}) for {sup 4}G{sub 5/2} emission state decrease with increase in Sm{sup 3+} ion concentration due to energy transfer. In order to elucidate the nature of energy transfer mechanism, the non-exponential decay curves are well fitted to the Inokuti–Hirayama model for S=6, which indicates that the energy transfer mechanism is of dipole–dipole type. The branching ratio (?{sub R}), stimulated emission cross-section (?{sub se}) and quantum efficiency (?) values measured for the most intense emission transition {sup 4}G{sub 5/2}?{sup 6}H{sub 7/2} (598 nm) optimise the concentration of Sm{sup 3+} ions as 1 mol% to produce bright visible orange lasing emission from these OFB glasses. - highlights: • Sm{sup 3+} doped OFB glasses have been synthesised using melt quenching technique. • From the absorption spectra, J–O parameters have been calculated using the J–O theory. • Emission cross-sections and efficiencies are calculated for laser transitions. • CIE colour co-ordinates were evaluated using emission spectra. • OFBSm1.0 glass was found to be the best for laser action in the visible orange region.

  13. Large dynamic range SPR measurements in the visible using a ZnSe prism

    CERN Document Server

    Canning, John; Cook, Kevin

    2015-01-01

    Large dynamic index measurement range (n = 1 to n = 1.7) using surface plasmon resonance (SPR) shifts is demonstrated with a ZnSe prism at 632.8 nm, limited by the available high index liquid hosts. In contrast to borosilicate based SPR measurements where angular limitations restrict solvent use to water and requires considerable care dealing with Fresnel reflections, the ZnSe approach allows SPR spectroscopies to be applied to a varied range of solvents An uncertainty in angular resolution between 1.5 and 6 deg, depending on the solvent and SPR angle, was estimated. The refractive index change for a given glucose concentration in water was measured to be n = (0.114 to 0.007) per precentage C6H12O6 conc. Given the transmission properties of ZnSe the processes can be readily extended into the mid infrared.

  14. Transparency of GaN substrates in the mid-infrared spectral range

    Energy Technology Data Exchange (ETDEWEB)

    Welna, M.; Kudrawiec, R.; Motyka, M.; Misiewicz, J. [Institute of Physics, Wroclaw University of Technology (Poland); Kucharski, R.; Zajac, M.; Doradzinski, R.; Dwilinski, R. [AMMONO S.A., Warsaw (Poland); Rudzinski, M. [Institute of Electronic Materials Technology, Warsaw (Poland)

    2012-03-15

    Transparency of truly bulk GaN substrates obtained by ammonothermal method was measured in the mid infrared spectral range by Fourier spectroscopy. The same measurements were performed for GaN templates grown by metalorganic vapour phase epitaxy on sapphire and SiC substrates. It has been clearly observed that truly bulk GaN substrates are transparent up to {proportional_to}7 {mu}m whereas GaN templates grown on sapphire and SiC are transparent only up to {proportional_to}6.5 and {proportional_to}5.5 {mu}m, respectively, due to non-transparency of sapphire and SiC in this spectral range. It has been shown that the transparency ''cut off'' at {proportional_to}7 {mu}m for GaN crystals results from the absorption of light by the second harmonic of optical phonons, which is very significant due to the strong electron-phonon coupling in this material. Also it has been clearly presented that the absorption ''cut-off'' in the infrared spectral region can be easily tuned by increasing of free carrier concentration in GaN. It was observed that the infrared transparency can be shifted from {proportional_to}7 to {proportional_to}2 {mu}m or even shorter wavelengths when the electron concentration is increased up to {proportional_to}10{sup 19} cm{sup -3}. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Rotationally resolved overtone transitions of CHD3 in the visible range

    Science.gov (United States)

    Ben Kraiem, H.; Campargue, A.; Chenevier, M.; Stoeckel, F.

    1989-08-01

    Absorption spectra in the 14 900-18 700 cm-1 range have been recorded for gaseous CHD3 at high resolution using the intracavity laser absorption spectroscopy (ICLAS) technique. The observed transitions correspond to the N=6 and 7 overtones of the C-H chromophore. Five bands were identified and rotational constants determined for four of them. The comparison of our experimental data with the calculated band origins and rotational constants obtained by Lewerenz and Quack is discussed. Absolute band intensities are given for seven bands corresponding to the N=5, 6, and 7 polyads.

  16. Intensity modulation photonic crystal fiber based refractometer in the visible wavelength range

    Science.gov (United States)

    Liu, Yun; Chen, Shimeng; Zhang, Xinpu; Gong, Zhenfeng; Peng, Wei

    2014-11-01

    A novel evanescent field refractometer based on a two-core photonic crystal fiber (TWPCF) sandwiched between multimode fibers(MMFs) is demonstrated. Through splicing a short piece of TWPCF between two MMFs, a simple structure and high sensitivity RI sensor can be constructed. Instead of using wavelength information as sensor signal, we focus more on the light intensity signal different from most PCF based RI sensor. The TWPCF section functions as a tailorable bridge between the excited high order modes and the surrounding refractive index (SRI). With a light filter inserting in the front of white light, the transmission spectrum of the light through the sensing region occurs in a welldefined wavelength bands. As a result, the peak power of the transmission light is tailored with the SRI perturbation via the MMF-TWPCF-MMF structure. The experiment result shows a quadratic relation between the light intensity and samples within RI range of 1.33-1.41 while a linear response can be achieved from the 1.33-1.35 which is a most used RI range for biologically sensing.

  17. LADEE UVS (UltraViolet Visible Spectrometer) and the Search for Lunar Exospheric Dust: A Detailed Spectral Analysis

    Science.gov (United States)

    Wooden, Diane H.; Cook, Amanda; Colaprete, Anthony; Shirley, Mark; Vargo, Kara; Elphic, Richard C.; Hermalyn, Brendan; Stubbs, Timothy John; Glenar, David A.

    2014-01-01

    The Lunar Atmosphere and Dust Environment Explorer (LADEE) executed science observations in lunar orbit spanning 2013-Oct-16- 2014-04-18 UT. LADEE's Ultraviolet/Visible Spectrometer (UVS) studies the composition and temporal variations of the tenuous lunar exosphere and dust environment, utilizing two sets of optics: a limb-viewing telescope, and a solar-viewer. The limb-viewing telescope observes illuminated dust and emitting gas species while the Sun is just behind the lunar limb. The solar viewer, with its diffuser, allows UVS to also stare directly at the solar disk as it approaches the limb, sampling progressively lower exosphere altitudes. Solar viewer "Occultation" activities occur at the lunar sunrise limb, as the LADEE spacecraft passes into the lunar night side, facing the Sun (the spacecraft orbit is near-equatorial retrograde). A loss of transmission of sunlight occurs by the occultation of dust grains along the line-of-sight. So-called "Inertial Limb" activities have the limb-viewing telescope pointed at the lit exosphere just after the Sun has set. Inertial Limb activities follow a similar progression of diminishing sampling altitudes but hold the solar elongation angle constant so the zodiacal light contribution remains constant while seeking to observe the weak lunar horizon glow. On the dark side of the moon, "Sodium Tail" activities pointed the limb-viewing telescope in the direction of the Moon's sodium tail (similar to anti-sunward), during different lunar phases. Of the UVS data sets, these show the largest excess of scattered blue light, indicative of the presence of small (approximately 100 nm) dust grains in the tail. Correlations are sought between dust in the sodium tail and meteor streams and magnetotail crossings to investigate impact- versus electrostatic-lofting. Once lofted, nanoparticles can become charged and picked up by the solar wind. The LADEE UVS Occultation, Inertial Limb, and Sodium Tail spectral datasets provide evidence of a lunar dust exosphere.

  18. Intercomparison of reflectances observed by GOME and SCIAMACHY in the visible wavelength range

    Science.gov (United States)

    Tilstra, Lieuwe G.; Stammes, Piet

    2006-06-01

    We compare the Earth reflectances of the spectrometers Global Ozone Monitoring Experiment (GOME) and Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) over their overlapping wavelength range (240-800 nm). The goal is to investigate the quality of the radiometric calibration of SCIAMACHY using calibrated GOME data as a reference. However, severe degradation of the GOME instrument in the UV since 2001 prevents it from being a reliable reference below 500 nm. Above 500 nm, GOME is reliable and we find substantial disagreement between GOME and SCIAMACHY, of the order of 15%-20%, which we can attribute completely to the current calibration problems of SCIAMACHY. These numbers are supported by a previous study in which SCIAMACHY was compared with the imager Medium Resolution Imaging Spectrometer (MERIS) onboard the Envisat satellite.

  19. Spectral Decay Characteristics in High Frequency Range of Observed Records from Crustal Large Earthquakes

    Science.gov (United States)

    Tsurugi, M.; Kagawa, T.; Irikura, K.

    2010-12-01

    Spectral decay characteristics in high frequency range of observed records from crustal large earthquakes occurred in Japan is examined. It is very important to make clear spectral decay characteristics in high frequency range for strong ground motion prediction. Target earthquakes are three events, the 2003 Miyagi-Ken Hokubu earthquake (Mw : 6.1), the 2005 Fukuoka-Ken Seiho-oki earthquake (Mw 6.6), and the 2008 Iwate-Miyagi Nairiku earthquake (Mw 6.9). The borehole data of each event are used in the analysis. The Butterworth type high-cut filter with cut-off frequency, fmax and its power coefficient of high-frequency decay, s [Boore(1983)], are assumed to express the high-cut frequency characteristics of ground motions. The four parameters such as seismic moment, corner frequency, cut-off frequency and its power coefficient of high-frequency decay are estimated by comparing observed spectra at rock sites with theoretical spectra. The theoretical spectra are calculated based on the omega squared source characteristics convolved with propagation-path effects and high-cut filter shapes. In result, the fmax’s of the records from each earthquakes are estimated from 6.5Hz to 8.4Hz, and the power coefficient, s, are estimated from 0.90 to 0.96, respectively. The fmax filter shapes of these earthquakes are almost same. The average characteristics of the three fmax filter shapes express in fmax is 7.64Hz, the power coefficient, s, is 0.91, respectively. The obtained results in this study may contribute to strong ground motion prediction in high frequency range. References: Hanks,T.C.: fmax, Bulletin of Seismological Society of America, 72, 1867-1879, 1982. Boore,D.M.: Stochastic simulation of high-frequency ground motion based on seismological models of the radiated spectra, Bulletin of Seismological Society of America, 73, 1865-1894, 1983.

  20. Spectral Decay Characteristics in High Frequency Range of Observed Records from Crustal Large Earthquakes (Part 2)

    Science.gov (United States)

    Tsurugi, M.; Kagawa, T.; Irikura, K.

    2012-12-01

    Spectral decay characteristics in high frequency range of observed records from crustal large earthquakes occurred in Japan is examined. It is very important to make spectral decay characteristics clear in high frequency range for strong ground motion prediction in engineering purpose. The authors examined spectral decay characteristics in high frequency range of observed records among three events, the 2003 Miyagi-Ken Hokubu earthquake (Mw 6.1), the 2005 Fukuoka-Ken Seiho-oki earthquake (Mw 6.6), and the 2008 Iwate-Miyagi Nairiku earthquake (Mw 6.9) in previous study [Tsurugi et al.(2010)]. Target earthquakes in this study are two events shown below. *EQ No.1 Origin time: 2011/04/11 17:16, Location of hypocenter: East of Fukushima pref., Mj: 7.0, Mw: 6.6, Fault type: Normal fault *EQ No.2 Origin time: 2011/03/15 22:31, Location of hypocenter: East of Shizuoka pref., Mj: 6.4, Mw: 5.9, Fault type: Strike slip fault The borehole data of each event are used in the analysis. The Butterworth type high-cut filter with cut-off frequency, fmax and its power coefficient of high-frequency decay, s [Boore(1983)], are assumed to express the high-cut frequency characteristics of ground motions. The four parameters such as seismic moment, corner frequency, cut-off frequency and its power coefficient of high-frequency decay are estimated by comparing observed spectra at rock sites with theoretical spectra. The theoretical spectra are calculated based on the omega squared source characteristics convolved with propagation-path effects and high-cut filter shapes. In result, the fmax's of the records from the earthquakes are estimated 8.0Hz for EQ No.1 and 8.5Hz for EQ No.2. These values are almost same with those of other large crustal earthquakes occurred in Japan. The power coefficient, s, are estimated 0.78 for EQ No.1 and 1.65 for EQ No.2. The value for EQ No.2 is notably larger than those of other large crustal earthquakes. It is seems that the value of the power coefficient, s, became large under the effect of complex ground structure and volcanic front. The obtained results may contribute to strong ground motion prediction in high frequency range for crustal earthquakes. Acknowledgement: This study commissioned by Japan Nuclear Energy Safety Organization. We thank the National Research Institute for Earth Science Disaster Prevention to provide the strong-motion data. References: Hanks,T.C. : fmax, Bulletin of Seismological Society of America, 72, 1867-1879, 1982. Boore,D.M. : Stochastic simulation of high-frequency ground motion based on seismological models of the radiated spectra, Bulletin of Seismological Society of America, 73, 1865-1894, 1983. Tsurugi,M., Kagawa,T., and Irikura,K. : Spectral Decay Characteristics in High Frequency Range of Observed Records from Crustal Large Earthquakes, AGU Fall Meeting, 2010.

  1. Broadband semiconductor optical amplifiers of the spectral range 750 – 1100 nm

    Energy Technology Data Exchange (ETDEWEB)

    Andreeva, E V; Il' chenko, S N; Lobintsov, A A; Shramenko, M V [Superlum Diodes Ltd., Moscow (Russian Federation); Ladugin, M A [' Sigm Plyus' Ltd, Moscow (Russian Federation); Marmalyuk, A A [Open Joint-Stock Company M.F. Stel' makh Polyus Research Institute, Moscow (Russian Federation); Yakubovich, S D [Moscow State Institute of Radio-Engineering, Electronics and Automation (Technical University), Moscow (Russian Federation)

    2013-11-30

    A line of travelling-wave semiconductor optical amplifiers (SOAs) based on heterostructures used for production of broadband superluminescent diodes is developed. The pure small-signal gains of the developed SOA modules are about 25 dB, while the gain bandwidths at a level of –10 dB reach 50 – 100 nm. As a whole, the SOA modules cover the IR spectral range from 750 to 1100 nm. The SOAs demonstrate a high reliability at a single-mode fibre-coupled cw output power up to 50 mW. Examples of application of two of the developed SOA modules as active elements of broadband fast-tunable lasers are presented. (lasers)

  2. Circuit model optimization of a nano split ring resonator dimer antenna operating in infrared spectral range

    Energy Technology Data Exchange (ETDEWEB)

    Gneiding, N., E-mail: Natalia.Gneiding@physik.uni-erlangen.de [Erlangen Graduate School in Advanced Optical Technologies (SAOT), University of Erlangen-Nuremberg, 91052 Erlangen (Germany); Zhuromskyy, O.; Peschel, U. [Institute of Optics, Information and Photonics, University of Erlangen-Nuremberg, 91058 Erlangen (Germany); Shamonina, E. [Department of Engineering Science, University of Oxford, Parks Road, OX1 3PJ Oxford (United Kingdom)

    2014-10-28

    Metamaterials are comprised of metallic structures with a strong response to incident electromagnetic radiation, like, for example, split ring resonators. The interaction of resonator ensembles with electromagnetic waves can be simulated with finite difference or finite elements algorithms, however, above a certain ensemble size simulations become inadmissibly time or memory consuming. Alternatively a circuit description of metamaterials, a well developed modelling tool at radio and microwave frequencies, allows to significantly increase the simulated ensemble size. This approach can be extended to the IR spectral range with an appropriate set of circuit element parameters accounting for physical effects such as electron inertia and finite conductivity. The model is verified by comparing the coupling coefficients with the ones obtained from the full wave numerical simulations, and used to optimize the nano-antenna design with improved radiation characteristics.

  3. Broadband semiconductor optical amplifiers of the spectral range 750 – 1100 nm

    International Nuclear Information System (INIS)

    A line of travelling-wave semiconductor optical amplifiers (SOAs) based on heterostructures used for production of broadband superluminescent diodes is developed. The pure small-signal gains of the developed SOA modules are about 25 dB, while the gain bandwidths at a level of –10 dB reach 50 – 100 nm. As a whole, the SOA modules cover the IR spectral range from 750 to 1100 nm. The SOAs demonstrate a high reliability at a single-mode fibre-coupled cw output power up to 50 mW. Examples of application of two of the developed SOA modules as active elements of broadband fast-tunable lasers are presented. (lasers)

  4. Complex Refractive Index of Ammonium Nitrate in the 2-20 micron Spectral Range

    Science.gov (United States)

    Jarzembski, Maurice A.; Norman, Mark L.; Fuller, Kirk A.; Srivastava, Vandana; Cutten, Dean R.

    2002-01-01

    Using high resolution Fourier Transform Infrared Spectroscopy (FTIR) absorbance/transmittance spectral data for ammonium sulfate (AMS), calcium carbonate (CAC) and ammonium nitrate (AMN), comparisons were made with previously published complex refractive indices data for AMS and CAC to infer experimental parameters to determine the imaginary refractive index for AMN in the infrared wavelength range from 2 to 20 microns. Kramers-Kronig mathematical relations were applied to calculate the real refractive index for the three compositions. Excellent agreement for AMS and CAC with the published values was found, validating the complex refractive indices obtained for AMN. Backscatter calculations using a lognormal size distribution for AMS, AMN, and CAC aerosols were performed to show differences in their backscattered spectra.

  5. Estimation of a radiative transfer model in the longwave spectral range: sensitivity study and application to real cases

    OpenAIRE

    Sicard, Michaël; Bertolín Martínez, Santiago; Mallet, Marc; Dubuisson, Philippe; Comerón Tejero, Adolfo

    2013-01-01

    The aerosol radiative effect in the longwave spectral range is often neglected in atmospheric aerosol forcing studies, hence very few researches are conducted in this field at local scale, and even less at regional scale. However, strong absorbing aerosols, like mineral dust, can have a small, but non-negligible heating effect in the longwave spectral range which can slightly counteract the aerosol cooling effect in the shortwave. The objective of this research is to perform a sensitivity stu...

  6. A panoply of insertion devices at SOLEIL for a wide spectral range and flexible polarisation

    International Nuclear Information System (INIS)

    The SOLEIL storage ring presents a very high fraction of its circumference dedicated to accommodate Insertion Devices (ID). Over the 25 presently planned insertion devices presenting a large variety of systems, 16 have been already installed and commissioned in September 2009. The UV-VUV region is covered with electromagnetic devices, offering tuneable polarisations. An electromagnet/permanent magnet undulator using copper sheets coils for fast switching of the helicity is under construction. 13 APPLE-II type undulators, with period ranging from 80 down to 36 mm, provide photons in the 0.1-10 keV region, some of them featuring tapering or quasi-periodicity. Five U20 in vacuum undulators cover typically the 3-30 keV range whereas an in vacuum wiggler, with compensation of the magnetic forces via adequate springs will cover the 10-50 keV spectral domain. R and D on cryogenic in-vacuum undulator is also under progress. A magnetic chicane using permanent magnet dipoles has also been designed in order to accommodate two canted undulators on the same straight section. A wiggler dedicated to slicing (production of femto second long pulses) is also being designed, its radiation will also serve for an X-ray beamline.

  7. Development of ultraviolet- and visible-light one-shot spectral domain optical coherence tomography and in situ measurements of human skin

    Science.gov (United States)

    Hirayama, Heijiro; Nakamura, Sohichiro

    2015-07-01

    We have developed ultraviolet (UV)- and visible-light one-shot spectral domain (SD) optical coherence tomography (OCT) that enables in situ imaging of human skin with an arbitrary wavelength in the UV-visible-light region (370-800 nm). We alleviated the computational burden for each color OCT image by physically dispersing the irradiating light with a color filter. The system consists of SD-OCT with multicylindrical lenses; thus, mechanical scanning of the mirror or stage is unnecessary to obtain an OCT image. Therefore, only a few dozens of milliseconds are necessary to obtain single-image data. We acquired OCT images of one subject's skin in vivo and of a skin excision ex vivo for red (R, 650±20 nm), green (G, 550±20 nm), blue (B, 450±20 nm), and UV (397±5 nm) light. In the visible-light spectrum, R light penetrated the skin and was reflected at a lower depth than G or B light. On the skin excision, we demonstrated that UV light reached the dermal layer. We anticipated that basic knowledge about the spectral properties of human skin in the depth direction could be acquired with this system.

  8. A feasibility study for the retrieval of the total column precipitable water vapour from satellite observations in the blue spectral range

    OpenAIRE

    Wagner, T; Beirle, S; Sihler, H.; Mies, K.

    2013-01-01

    We present a new algorithm for satellite retrievals of the atmospheric water vapour column in the blue spectral range. The water vapour absorption cross section in the blue spectral range is much weaker than in the red spectral range. Thus the detection limit and the uncertainty of individual observations are systematically larger than for retrievals at longer wavelengths. Nevertheless, water vapour retrievals in the blue spectral range have also several advantages: since the surface albedo i...

  9. Spectral modeling in the VNIR range of 67P/Churyumov-Gerasimenko nucleus from VIRTIS-M onboard Rosetta

    OpenAIRE

    Raponi, A.; Ciarnello, M.; Capaccioni, F.; Filacchione, G.; De Sanctis, M.C.; Erard, S.; Leyrat, C.; Bockelee-Morvan, D; Tosi, F.; Capria, M. T.; Piccioni, G...; Palomba, E.; Longobardo, A.; Drossart, P; Quirico, E.

    2015-01-01

    Topic of this work is the analysis of the surface composition of comet 67P/Churyumov-Gerasimenko using the data obtained by the VIRTIS instrument onboard the Rosetta spacecraft. We have focused on the VNIR spectral range (0.4 - 2.5 ?m) which presents a nearly flat spectrum with quite uniform spectral slopes across the entire comet surface. In this work we report about the spectral modeling of CG VIS-IR spectra by means of Hapke’s radiative transfer model.

  10. Spectral modeling in the VNIR range of 67P/Churyumov-Gerasimenko nucleus from VIRTIS-M onboard Rosetta

    Science.gov (United States)

    Raponi, A.; Ciarniello, M.; Capaccioni, F.; Filacchione, G.; De Sanctis, M. C.; Erard, S.; Leyrat, C.; Bockelée-Morvan, D.; Tosi, F.; Capria, M. T.; Piccioni, G.; Palomba, E.; Longobardo, A.; Drossart, P.; Quirico, E.; Beck, P.; Schmitt, B.; Barucci, A.; Arnold, G.; Blecka, M.

    2015-10-01

    Topic of this work is the analysis of the surface composition of comet 67P/Churyumov-Gerasimenko using the data obtained by the VIRTIS instrument [1] onboard the Rosetta spacecraft. We have focused on the VNIR spectral range (0.4 - 2.5 ?m) which presents a nearly flat spectrum with quite uniform spectral slopes across the entire comet surface. In this work we report about the spectral modeling of CG VIS-IR spectra by means of Hapke's radiative transfer model.

  11. Using Visible Spectral Information to Predict Long-Wave Infrared Spectral Emissivity: A Case Study over the Sokolov Area of the Czech Republic with an Airborne Hyperspectral Scanner Sensor

    OpenAIRE

    Gila Notesco; Eyal Ben-Dor; Simon Adar; Yoel Shkolnisky

    2013-01-01

    Remote-sensing platforms are often comprised of a cluster of different spectral range detectors or sensors to benefit from the spectral identification capabilities of each range. Missing data from these platforms, caused by problematic weather conditions, such as clouds, sensor failure, low temporal coverage or a narrow field of view (FOV), is one of the problems preventing proper monitoring of the Earth. One of the possible solutions is predicting a detector or sensor’s missing data using an...

  12. Justification of choice of the spectral range for the study of combustion processes with the use of thermography in the middle IR range

    Science.gov (United States)

    Agafontsev, M. V.; Loboda, E. L.; Reyno, V. V.; Anufriev, I. S.

    2015-11-01

    The paper presents the emission spectra of flame formed during combustion of different fuels and gives the grounds for application of various narrow spectral ranges in the mid-infrared region to record the temperature fields in flame and flame screened objects.

  13. Spectral conditions for strong local nondeterminism and exact Hausdorff measure of ranges of Gaussian random fields

    CERN Document Server

    Luan, Nana

    2011-01-01

    Let $X= \\{X(t), t \\in \\R^N\\}$ be a Gaussian random field with values in $\\R^d$ defined by \\[ X(t) = \\big(X_1(t),..., X_d(t)\\big),\\qquad t \\in \\R^N, \\] where $X_1, ..., X_d$ are independent copies of a real-valued, centered, anisotropic Gaussian random field $X_0$ which has stationary increments and the property of strong local nondeterminism. In this paper we determine the exact Hausdorff measure function for the range $X([0, 1]^N)$. We also provide a sufficient condition for a Gaussian random field with stationary increments to be strongly locally nondeterministic. This condition is given in terms of the spectral measures of the Gaussian random fields which may contain either an absolutely continuous or discrete part. This result strengthens and extends significantly the related theorems of Berman (1973, 1988), Pitt (1978) and Xiao (2007, 2009), and will have wider applicability beyond the scope of the present paper.

  14. Widely bandwidth-tunable silicon filter with an unlimited free-spectral range.

    Science.gov (United States)

    St-Yves, Jonathan; Bahrami, Hadi; Jean, Philippe; LaRochelle, Sophie; Shi, Wei

    2015-12-01

    Next-generation high-capacity optical networks require flexible allocation of spectrum resources, for which low-cost optical filters with an ultra-wide bandwidth tunability beyond 100 GHz are desired. We demonstrate an integrated band-pass filter with the bandwidth continuously tuned across 670 GHz (117-788 GHz) which, to the best of our knowledge, is the widest tuning span ever demonstrated on a silicon chip. The filter also features simultaneous wavelength tuning and an unlimited free spectral range. We measured an out-of-band contrast of up to 55 dB, low in-band ripples of less than 0.3 dB, and in-band group delay variation of less than 8 ps. This result was achieved using cascaded Bragg-grating-assisted contra-directional couplers and micro-heaters on the 220 nm silicon-on-insulator platform with a very compact footprint of less than 7000???m2. Another design with the bandwidth continuously tunable from 50 GHz to 1 THz is also presented. PMID:26625028

  15. Spatial distribution of spectral parameters of high latitude geomagnetic disturbances in the Pc5/Pi3 frequency range

    Directory of Open Access Journals (Sweden)

    V. A. Pilipenko

    2010-09-01

    Full Text Available We analyze spectral parameters of the geomagnetic disturbances within the 1–4 mHz (Pc5/Pi3 frequency range for 29 observatories from polar to auroral latitudes. The main object of this study is the broadband (noise background under quiet and moderately disturbed conditions. To obtain a quantitative description of background high-latitude long period ULF activity the log-log dependence of the spectral power on frequency is expanded over Legendre polynomials, and the coefficients of this expansion (spectral moments are used to describe the most common features of these spectra. Not only the spectral power, but also the spectral slope and higher spectral moments, averaged over relatively long time intervals, demonstrate a systematic dependence on corrected geomagnetic (CGM latitude, ?, and magnetic local time, MLT. The 2-D distributions of the spectral moments in ?-MLT coordinates are characterized by existence of structures, narrow in latitude and extended in MLT, which can be attributed to the projections of different magnetospheric domains. Spatio-temporal distributions of spectral power of elliptically (P-component and randomly (N-component polarized signal are similar, but not identical. The N-component contribution to the total signal becomes non-negligible in regions with a high local activity, such as the auroral oval and dayside polar cusp. The spectral slope indicates a larger relative contribution of higher frequencies upon the latitude decrease, probably, as a result of the resonant effects in the ULF noise. The higher spectral moments are also controlled mostly by CGM latitude and MLT and are fundamentally different for the polarized and non-polarized components. This study is a step towards the construction of an empirical model of the ULF wave power in Earth's magnetosphere.

  16. Cloud spectral transmittance in the UV and visible at Ushuaia (54 degrees 49 minutes S, 68 degrees 19 minutes W)

    Science.gov (United States)

    Diaz, Susana B.; Vigliarolo, Paula; Vera, Carolina; Deferrari, Guillermo

    2002-01-01

    The presence of clouds is responsible for an important variation in the UV and visible radiation at the Earth's surface. Although for practical purposes cloud transmittance is often considered plane in the UV and visible, a wavelength dependence is observed. In this paper we performed a statistical study of cloud transmittance at Ushuaia for wavelengths between 295 and 600 nm, following different procedures. A decrease of the transmittance for increasing wavelengths in the UVA and the visible was observed (0 to 50% decrease at 600 nm regarding to 340 nm) in good agreement with the observations made by other authors. Nevertheless, for wavelengths below 320 nm our results show discrepancy with other papers. Since Ushuaia is a small town n a fairly unpolluted area, a possible reason for this differences is that, as a consequence of low ozone amounts in the troposphere, Rayleigh scatter is more important than ozone absorption, even in this part of the spectrum.

  17. Fabry-Perot Based Ranging Interferometer Receiver for High Spectral Resolution Lidar Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Michigan Aerospace Corporation (MAC) is pleased to present the following Phase II proposal for a Fabry-Perot Based Interferometer Receiver for the High Spectral...

  18. Investigation of the formation and analytical properties of 12-molybdogallium heteropoly complex in the near ultraviolet and visible spectral regions

    International Nuclear Information System (INIS)

    The conditions of the formation of 12-molybdogallium heteropoly complex were investigated in order to use the absorption of this compound in the near ultraviolet and visible regions of the spectrum in gallium determination in the samples containing a high concentration of this element. The possibility of gallium determination at the concentrations of 10-3 and 10-2 M without isolation of the same amounts of aluminium, indium, and thallium was shown. 8 refs.; 4 figs

  19. Optically visible post-AGB/RGB stars and young stellar objects in the Small Magellanic Cloud: candidate selection, spectral energy distributions and spectroscopic examination

    CERN Document Server

    Kamath, D; Van Winckel, H

    2014-01-01

    We have carried out a search for optically visible post-AGB candidates in the Small Magellanic Cloud (SMC). We used mid-IR observations from the Spitzer Space Telescope to select optically visible candidates with a mid-IR excess. We obtained low-resolution optical spectra for 801 candidates. After removing contaminants and poor quality spectra, the final sample comprised of 63 post-AGB/RGB candidates of A - F spectral type. Using the spectra, we estimated the stellar parameters: effective temperature, surface gravity and [Fe/H]. We also estimated the reddening and deduced the luminosity using the stellar parameters combined with photometry. Based on a luminosity criterion, 42 of these 63 sources were classified as post-RGB candidates and the remaining as post-AGB candidates. From the spectral energy distributions we found that 6 of the 63 post-AGB/RGB candidates have a circumstellar shell suggesting that they are single stars, while 27 of them have a surrounding disc, suggesting that they are binaries. For th...

  20. Dispersed fluorescence spectrometry from the VIS to VUV spectral range for experiments at heavy-ion storage facilities

    Science.gov (United States)

    Reiß, Philipp; Schmidt, Philipp; Ozga, Christian; Knie, André; Ehresmann, Arno

    2015-11-01

    For the electronic- and charge-state specific determination of VUV–VIS fluorescence emission cross sections after collisions between heavy ions and neutral gases or electrons a fluorescence spectrometer for the VUV–VIS spectral range is planned. Tentative experiments showed that signal rates after collisions between Xe atoms and {{Xe}}54+ ions are high enough to allow efficient experiments.

  1. Third-harmonic generation with a more than 500?nm tunable spectral range in a step-index tellurite fiber

    International Nuclear Information System (INIS)

    We demonstrate third-harmonic generation (THG) with a tunable spectral range of more than 500?nm in a step-index tellurite fiber. Third-harmonic (TH) signals with a peak wavelength from 524 to 1043?nm are obtained in a 3?cm-long fiber when the fundamental wavelength shifts from 1560 to 3100?nm. To our knowledge, the tunable spectral range covering almost one octave is the widest tunable range of THG in fibers so far. The far-field patterns of the TH signals by 1560?nm to 2100?nm pumping are recorded by a charge coupled device camera, which are close to the fundamental mode profile. The THG in such a wide tunable range is attributable to the high nonlinearity of the tellurite fiber and the high pump peak power of the pump pulse. (letters)

  2. High spectral resolution observations of Martian atmosphere in infrared - submillimeter range from ground-based instruments.

    Science.gov (United States)

    Nakagawa, Hiromu; Kasaba, Yasumasa; Aoki, Shohei; Murata, Isao; Maezawa, Hiroyuki; Okano, Shoichi; Sagawa, Hideo; Kasai, Yasuko

    2010-05-01

    With increased knowledge on our "neighbor" planets Mars and Venus, based on recent aggressive explorations by the US and Europe, our image on them is changing significantly. In particular, Mars is called ‘a frozen water planet'. It is almost certain that Mars once had duration with warm and wet climate [Head et al., 1999; Donahue, 1995; Parker et al., 1993]. It still conserves a large amount of water ice under the surface [Boynton et al., 2002; Mitrofanov et al., 2002; Feldman et al., 2002]. The question "Why and when did they diverge?" is essential for their environments which potentially could create and keep the life or not. Many molecules in planetary atmospheres show transitions in the mid infrared - submillimeter region. Thus, high-resolution spectroscopy in this region is significantly indispensable to study planetary atmospheres. We searched sulfur oxide (SO2 and SO) in the Martian atmosphere by the Atacama Submillimeter Telescope Experiment (ASTE). Sulfur oxide is one of the most evident species in terrestrial volcanic gases. Although it has not yet been detected at Mars, this detection can constraint the Martian crustal and volcanic activities. We observed northern winter of Mars on 26/Dec./2007 (Ls=8.1) in 346 GHz range with ~ 1h integration, and got the upper limit of the SO2 mixing ratio, 2 ppb. We concluded that the crustal or volcanic gas produced into the atmosphere is tenuous in northern winter [Nakagawa et al., 2009]. Infrared heterodyne spectroscopy has proven to be a powerful tool for astrophysical studies. To achieve highest spectral resolution and sensitivity as well as compact instrumentation heterodyne systems are advantageous over direct-detection methods. Our group in Tohoku University has developed own heterodyne system for infrared spectrometer for Earth's atmosphere over the past 20 years. The failure of earlier attempts to build tunable systems using tunable diode lasers was due mostly to insufficient laser power. Recently, quantum cascade lasers (QCLs) offer sufficient optical output power of several milliwatts to guarantee an efficient heterodyning process and high system sensitivity. The use of QCLs in our system led to a breakthrough giving the heterodyne infrared spectrometer for planetary atmosphere. We report experiments evaluating the feasibility of QCLs at mid-infrared wavelengths for use as local oscillator (LO) in a heterodyne receiver. Performance tests with the QCL provided by Hamamatsu Photonics (operating at 7.7 um), and QCL provided by Maxion Technologies (operating at 10.6 um in room temperature) were evaluated.

  3. Characterization of planar Ti:LiNbO3 optical waveguides in the visible and near-infrared spectral range

    International Nuclear Information System (INIS)

    Several Ti:LiNbO3 waveguides have been fabricated in dry and wet atmosphere, varying the diffusion time. The effect of water vapor on the diffusion process has been investigated. Effective indices and attenuation at ? = 0.6328, 1.15, and 1.52 ?m have been measured. In the dry case, the Ti in-diffusion proceeds more rapidly than in the wet case, and the two diffusion coefficients have been calculated. Also, it has been observed that the presence of water vapor in the atmosphere does not completely prevent the phenomenon of Li2O out-diffusion, while the importance of the boat and the furnace materials in this process has been verified. Attenuation measurements showed that particular care must be taken, when working with waveguides diffused for short times, for two reasons. (1) The ratio diffusion length/wavelength, i.e., the normalized frequency v, decreases, and modes approach the cutoff, becoming more lossy. Of course, this is more evident working at long wavelength. (2) The surface roughness can strongly affect the attenuation value

  4. Natural variability of bio-optical properties in Case 1 waters: attenuation and reflectance within the visible and near-UV spectral domains, as observed in South Pacific and Mediterranean waters

    Directory of Open Access Journals (Sweden)

    A. Morel

    2007-07-01

    Full Text Available The optical properties of Case 1 waters have been empirically related to the chlorophyll concentration, [Chl], historically used as an index of the trophic state and of the abundance of the biological materials. The natural variability around the mean statistical relationships is here examined by comparing the apparent optical properties (spectral downward irradiance attenuation and reflectance as a function of [Chl] which were determined in two environments, the Pacific and Mediterranean waters. These oceanic zones apparently form two extremes of the bio-optical variability range. The systematic deviations, in both directions with respect to the average laws, mainly result from the differing contents in non-algal detrital materials and dissolved colored substance for a given [Chl] level. These contents are higher and lower than the average, in the Mediterranean Sea and Pacific Ocean, respectively. The divergences between the two water bodies, detected in the visible spectral domain, are considerably accentuated in the UV domain. The bio-optical properties in this spectral domain (310–400 nm are systematically explored. Their prediction based on the sole [Chl] index is problematic; although it is probably possible on a regional scale, an ubiquitous relationship does not seem to exist for the global scale.

  5. Estudio de la respuesta espectral en el visible de películas delgadas de ZnSe / Study of the Spectral Response in the Visible Spectral Region the ZnSe thin Films

    Scientific Electronic Library Online (English)

    A, Pardo; H.G, Castro-Lora; J, Torres; L.D, López-Carreño; H. M, Martínez; N. T, Ramírez.

    2014-07-30

    Full Text Available En este trabajo es presentado el estudio de la fotoconductividad en películas delgadas de ZnSe depositadas sobre sustratos de vidrio a diferentes temperaturas, en condiciones de alto vacío usando la técnica de evaporación térmica. El efecto de la temperatura de sustrato sobre la fotoconductividad es [...] pectral y las propiedades morfológicas de las películas delgadas de ZnSe fueron estudiados. Para las medidas de fotoconductividad se depositaron contactos de cobre sobre las muestras. Se midieron las respuestas espectrales para las muestras para el rango comprendido entre 290 y 500 nm. En todas las muestras la señal presento dos contribuciones asociadas a las transiciones con valores promedio de energía de 3,35 y 2,80 eV, respectivamente. El tiempo de respuesta de las muestras está asociado a la morfología de la muestras. En las muestras preparadas a bajas temperaturas se obtuvieron tiempos de respuesta del orden de los segundos, mientras que, el tiempo disminuye en un orden de magnitud en las muestras preparadas a temperatura de sustrato de 250°C. Abstract in english In this work are presented results in the study of photoconductivity of ZnSe thin films deposited on glass substrate. The effect of substrate temperature on the spectral photoconductivity and morphological properties of ZnSe thin films were studied. The Spectral response appeared between 290 and 500 [...] nm. In the spectral responses were found two contributions associated with transitions labeled , with energy values of 3:35 and 2:80 eV, respectively. The response time of the sample is associated with the morphology of the samples. In the samples prepared at lower temperatures were obtained response times on the order of seconds, whereas the time decreases by one magnitude order in the samples prepared at the substrate temperature of 250°C.

  6. Effect of vegetation density and vegetation conditions on the spectral backscattering in the visible and the near infrared

    Science.gov (United States)

    Fahsi, Ahmed; Tsegaye, Teferi D.; Rajbhandari, Narayan B.; Tadesse, Wubishet; Coleman, Tommy L.

    1999-12-01

    The work presented in this paper investigates the sensitivity of the hyperspectral remotely sensed data to the vegetation density under different soil moisture conditions. The research testbed comprised four corn plots with 4 different densities, one grass plot, and one bare soil plot. For this purpose, the hyperspectral data were recorded simultaneously as the field measurements, which included soil moisture and temperature, soil characterization (gravimetric soil moisture, bulk density, surface roughness), and vegetation measurements (biomass; plant height; leaf orientations, length, thickness; dielectric constant of stalks and leaves; stalk diameter and height). The findings of this study showed that physical and physiological aspects, as well as the structure of the vegetation, have noticeable effects on its spectral response. The results showed distinct spectral response among the different vegetation densities, thus biomass. They also showed that hyperspectral data are effective in detecting soil moisture variability and discriminating among vegetation densities and conditions. The hyperspectral data were in agreement with the ground data and discriminated among small variations in soil moisture and vegetation densities and conditions. This study also showed that the variation in the spectral variability from different vegetation densities becomes negligible when the vegetation leaves cover completely the ground surface.

  7. Surface compositional mapping by spectral ratioing of ERTS-1 MSS data in the Wind River Basin and Range, Wyoming

    Science.gov (United States)

    Vincent, R. K. (principal investigator); Salmon, B. C.; Pillars, W. W.; Harris, J. E.

    1975-01-01

    The author has identified the following significant results. ERTS data collected in August and October 1972 were processed on digital and special purpose analog recognition computers using ratio enhancement and pattern recognition. Ratios of band-averaged laboratory reflectances of some minerals and rock types known to be in the scene compared favorably with ratios derived from the data by ratio normalization procedures. A single ratio display and density slice of the visible channels of ERTS MSS data, Channel 5/Channel 4 (R5,4), separated the Triassic Chugwater formation (redbeds) from other formations present and may have enhanced iron oxide minerals present at the surface in abundance. Comparison of data sets collected over the same area at two different times of the year by digital processing indicated that spectral variation due to environmental factors was reduced by ratio processing.

  8. Photoinduced catalytic adsorption of model contaminants on Bi/Cu pillared montmorillonite in the visible light range

    Science.gov (United States)

    Montmorillonite K10 clay was pillared with BiCl3 and Cu(NO3)2 to extend its applicability as catalytic adsorbent to degrade aqueous solution of anionic azo-dye Methyl Orange (MO) in the presence of visible light irradiation. The preparation of Bi/Cu-montmorillonite utilized benig...

  9. The spectral opacity of triatomic carbon measured in a graphite tube furnace over the 280 to 600 nm wavelength range

    Science.gov (United States)

    Snow, W. L.; Wells, W. L.

    1980-01-01

    The paper presents the measurements of linear triatomic carbon opacity (C3) made in a graphite tube furnace to extend the wavelength range of Brewer and Engelke (1962) to the 280-600 nm range. An electrooptical method was used to determine C3 absorption in argon at 2720 to 3060 K; a quartic polynomial regression expression was derived to provide a complete temperature profile from pyrometer measurements. The C3 spectra were plotted for several opacity levels. It was concluded that the extension of the spectral range to the near u.v. levels made it easier to identify C3 particles.

  10. A Tape Method for Fast Characterization and Identification of Active Pharmaceutical Ingredients in the 2-18 THz Spectral Range

    Science.gov (United States)

    Kissi, Eric Ofosu; Bawuah, Prince; Silfsten, Pertti; Peiponen, Kai-Erik

    2015-03-01

    In order to find counterfeit drugs quickly and reliably, we have developed `tape method' a transmission spectroscopic terahertz (THz) measurement technique and compared it with a standard attenuated total reflection (ATR) THz spectroscopic measurement. We used well-known training samples, which include commercial paracetamol and aspirin tablets to check the validity of these two measurement techniques. In this study, the spectral features of some active pharmaceutical ingredients (APIs), such as aspirin and paracetamol are characterized for identification purpose. This work covers a wide THz spectral range namely, 2-18 THz. This proposed simple but novel technique, the tape method, was used for characterizing API and identifying their presence in their dosage forms. By comparing the spectra of the APIs to their dosage forms (powder samples), all distinct fingerprints present in the APIs are also present in their respective dosage forms. The positions of the spectral features obtained with the ATR techniques were akin to that obtained from the tape method. The ATR and the tape method therefore, complement each other. The presence of distinct fingerprints in this spectral range has highlighted the possibility of developing fast THz sensors for the screening of pharmaceuticals. It is worth noting that, the ATR method is applicable to flat faced tablets whereas the tape method is suitable for powders in general (e.g. curved surface tablets that require milling before measurement). Finally, we have demonstrated that ATR techniques can be used to screen counterfeit antimalarial tablets.

  11. Application of prominent spectral lines in the 125-180 nm range for inductively coupled plasma optical emission spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, O.; Heitland, P. [Spectro Analytical Instruments GmbH, Kleve (Germany)

    2001-12-01

    A new axially viewed ICP optical emission spectrometer featuring an argon-filled optic and CCD detectors was evaluated for the application of prominent spectral lines in the 125-180 nm range. This wavelength range was investigated for several analytical applications of inductively coupled plasma optical emission spectrometry (ICP-OES). There are different advantages for the application of spectral lines below 180 nm. A number of elements, such as Al, Br, Cl, Ga, Ge, I, In, N, P, Pb, Pt, S and Te, were found to have the most intense spectral lines in the wavelength range from 125-180 nm. Compared with lines above 180 nm higher signal-to-background ratios were found. Low limits of detection using pneumatic nebulization of aqueous solutions for sample introduction were calculated for Al II 167.080 nm (0.04 {mu}g L{sup -1}), Br I 154.065 nm (9 {mu}g L{sup -1}), Cl I 134.724 nm (19 {mu}g L{sup -1}), Ga II 141.444 nm (0.8 {mu}g L{sup -1}), Ge II 164.919 nm (1.3 {mu}g L{sup -1}), I I 142.549 nm (13 {mu}g L{sup -1}), In II 158.583 nm (0.2 {mu}g L{sup -1}), P I 177.500 nm (0.9 {mu}g L{sup -1}), Pb II 168.215 nm (1.5 {mu}g L{sup -1}), Pt II 177.709 nm (2.6 {mu}g L{sup -1}), S I 180.731 nm (1.9 {mu}g L{sup -1}) and Te I 170.00 nm (4.6 {mu}g L{sup -1}). Numerous application examples for the use of those lines and other important spectral lines below 180 nm are given. Because of fewer emission lines from transition elements, such as Fe, Co, Cr, lines below 180 nm often offer freedom from spectral interferences. Additional lines of lower intensity for the determination of higher elemental concentrations are also available in the vacuum ultraviolet spectral range. This is specially useful when the concentrations are not in the linear range of calibration curves obtained with commonly used lines. (orig.)

  12. Development of on-line sorting system for detection of infected seed potatoes using visible near-infrared transmittance spectral technique

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dae Yong; Cho, Byoung Kwan [Dept. of Biosystems Engineering, Chungnam National University, Daejeon (Korea, Republic of); Mo, Chang Yeun [Rural Development Administration, National Institute of Agricultural Engineering, Jeonju (Korea, Republic of); Kang, Jun Soon [Dept. of Horticultural Bioscience, Pusan National University, Pusan (Korea, Republic of)

    2015-02-15

    In this study, an online seed potato sorting system using a visible and near infrared (40 1100 nm) transmittance spectral technique and statistical model was evaluated for the nondestructive determination of infected and sound seed potatoes. Seed potatoes that had been artificially infected with Pectobacterium atrosepticum, which is known to cause a soil borne disease infection, were prepared for the experiments. After acquiring transmittance spectra from sound and infected seed potatoes, a determination algorithm for detecting infected seed potatoes was developed using the partial least square discriminant analysis method. The coefficient of determination(R{sup 2}{sub p}) of the prediction model was 0.943, and the classification accuracy was above 99% (n = 80) for discriminating diseased seed potatoes from sound ones. This online sorting system has good potential for developing a technique to detect agricultural products that are infected and contaminated by pathogens.

  13. Development of on-line sorting system for detection of infected seed potatoes using visible near-infrared transmittance spectral technique

    International Nuclear Information System (INIS)

    In this study, an online seed potato sorting system using a visible and near infrared (40 1100 nm) transmittance spectral technique and statistical model was evaluated for the nondestructive determination of infected and sound seed potatoes. Seed potatoes that had been artificially infected with Pectobacterium atrosepticum, which is known to cause a soil borne disease infection, were prepared for the experiments. After acquiring transmittance spectra from sound and infected seed potatoes, a determination algorithm for detecting infected seed potatoes was developed using the partial least square discriminant analysis method. The coefficient of determination(R2p) of the prediction model was 0.943, and the classification accuracy was above 99% (n = 80) for discriminating diseased seed potatoes from sound ones. This online sorting system has good potential for developing a technique to detect agricultural products that are infected and contaminated by pathogens.

  14. TESIS experiment on study of solar corona in EUV spectral range (CORONAS-PHOTON project)

    International Nuclear Information System (INIS)

    A new orbital station, namely: the CORONAS-PHOTON one (to be launched in 2006) equipped with systems to explore Sun at the intensification period of the solar activity 24-th cycle and at its peak is being designed within the framework of the CORONAS National Sun Space Exploration Program. The station equipment consists of systems to observe Sun within the spectral soft X-ray and vacuum ultraviolet bands. Paper lists and describes the TESIS experiment tools designed for the CORONAS-PHOTON Project to ensure the Sun atmospheric research within short-wave band

  15. Three and four wave parametric interactions for ultrashort pulse generation in the ultraviolet, near and mid-infrared spectral range

    OpenAIRE

    Darginavi?ius, Julius

    2013-01-01

    In this thesis we investigated and developed three- and four-wave interaction-based frequency conversion methods for ultrashort pulse generation in the ultraviolet (UV), near and mid-infrared (IR) spectral ranges. In particular, efficient generation of Nd:glass laser harmonics was demonstrated experimentally, through noncollinear four-wave difference-frequency mixing in isotropic media. Also, broadband optical parametric amplification in the UV was investigated theoretically and achieved expe...

  16. INFRARED SPECTROSCOPY OF GAS-PHASE POLYCYCLIC AROMATIC HYDROCARBON CATIONS IN THE 10–50 ?m SPECTRAL RANGE

    International Nuclear Information System (INIS)

    The gas-phase infrared spectra of four polycyclic aromatic hydrocarbon (PAH) cations have been recorded in the 10-50 ?m (or 1000-200 cm–1) spectral range via IR multiple photon dissociation (IRMPD) spectroscopy. Ionized PAHs are formed by UV laser ionization in an effusive beam and subsequently irradiated with a single pulse of narrowband tunable infrared light produced by the Free-Electron Laser for IntraCavity Experiments FELICE. The ion population is then analyzed in a time-of-flight mass spectrometer. Upon resonance, dissociation is induced so that IR spectra can be recorded by monitoring either the depleted parent ion intensity or the appearance of fragment ions as a function of the wavelength. The intracavity IR fluence enables the recording of IRMPD spectra of strongly bound PAH cations in the hitherto inaccessible far-IR spectral range. Experimental spectra are presented for the radical cations of anthracene, tetracene, pentacene, and coronene. Spectra calculated with density functional theory at the B3LYP/6-311g(2df,2pd) level reproduce IR frequencies reasonably accurately in this spectral range when a uniform scaling factor of 0.94 over the complete 10-50 ?m spectral range is employed. We show that even vibrational modes with a calculated IR intensity lower than 1 km mol–1 can be observed. For the catacondensed PAH cations we find CH out-of-plane bending vibrations involving four adjacent CH groups within a few wavenumbers of 733 cm–1, closely matching the 13.6 ?m UIR band. For the larger systems, pentacene and coronene, we observe a continuous structureless background absorption above 400 cm–1 which is attributed to the high density of IR dipole allowed combination modes for these systems.

  17. Directional visible light scattering by silicon nanoparticles

    CERN Document Server

    Fu, Yuan Hsing; Miroshnichenko, Andrey E; Yu, Ye Feng; Lukiyanchuk, Boris

    2012-01-01

    Directional light scattering by spherical silicon nanoparticles in the visible spectral range is experimentally demonstrated for the first time. These unique scattering properties arise due to simultaneous excitation and mutual interference of magnetic and electric dipole resonances inside a single nanosphere. Directivity of the far-field radiation pattern can be controlled by changing light wavelength and the nanoparticle size. Forward-to-backward scattering ratio above 6 can be experimentally obtained at visible wavelengths. These unique properties of silicon nanoparticles make them promising for design of novel low-loss visible- and telecom-range nanoantenna devices.

  18. Spectral synthesis provides 2-D videos on a 1-D screen with 360{\\deg}-visibility and mirror-immunity

    CERN Document Server

    Grusche, Sascha

    2014-01-01

    Spatial-light-modulator (SLM)-based tunable sources have complex setups. A simpler setup, comprising an SLM-projector and a dispersive element, synthesizes light as effectively, based on a Superposition of Newtonian Spectra (SNS). As a generalization of SNS, two-dimensional (2-D) grayscale videos are spectrally encoded on a one-dimensional (1-D), translucent screen, and viewed through another dispersive element. This Projected-Image Circumlineascopy (PICS) produces semitransparent, rainbow-coloured, virtual 2-D videos that face every viewer anywhere around the 1-D screen. They are invariant under reflection of the 1-D screen in mirrors parallel to it. SNS bandwidth and PICS image geometry are calculated using geometric optics and Dispersion Diagrams.

  19. Using the electron synchrotron radiation for the calibration of the spectral density in UV and long-wave vacuum UV range (160 nm to 340 nm)

    International Nuclear Information System (INIS)

    Electron synchrotron radiation was investigated with a view to the development of methods for the calibration of the spectral density in the UV and long-wave vacuum UV spectral regions. The relative spectral radiation flow of a synchrotron can be calculated over a wide spectral region. In order to determine the absolute radiation flow in the vaccum UV, the synchrotron radiation in the visible region is compared with a reference source (calibrated tungsten filament lamp). Between 160 nm and 340 nm, the spectral beam density calibration with the synchrotron radiation is uncertain by about +- 5%. Between 280 nm and 340 nm, calibrations of deuterium lamps at the synchrotron and at a cavity radiator vary by less than 10%. (orig./WL)

  20. Wide spectral range multiple orders and half-wave achromatic phase retarders fabricated from two lithium tantalite single crystal plates

    Science.gov (United States)

    Emam-Ismail, M.

    2015-11-01

    In a broad spectral range (300-2500 nm), we report the use of channeled spectra formed from the interference of polarized white light to extract the dispersion of the phase birefringence ?np(?) of the x- and y-cuts of lithium tantalite (LiTaO3:LT) plates. A new method named as wavenumber difference method is used to extract the spectral behavior of the phase birefringence of the x- and y- cuts of LT plates. The correctness of the obtained birefringence data is confirmed by using Jones vector method through recalculating the plates thicknesses. The spectral variation of the phase birefringence ?np(?) of the x- and y-cuts of LT plates is fitted to Cauchy dispersion function with relative error for both x- and y-cuts of order 2.4×10-4. The group birefringence dispersion ?ng (?) of the x- and y-cuts of LT plates is also calculated and fitted to Ghosh dispersion function with relative error for both x- and y-cuts of order 2.83×10-4. Furthermore, the phase retardation introduced by the x- and y-cuts of LT plates is also calculated. It is found that the amount of phase retardation confirms that the x- and y-cuts of LT plates can act as a multiple order half- and quarter-wave plates working at many different wavelengths through the spectral range 300-2500 nm. For the x- and y-cuts of LT plates, a large difference between group and phase birefringence is observed at a short wavelength (?=300 nm); while such difference progressively diminished at longer wavelength (?=2000 nm). In the near infrared region (NIR) region (700-2500 nm), a broad spectral full width at half maximum (FWHM) is observed for either x- or y-cut of LT plate which can act as if it is working as a zero order wave plate. Finally, an achromatic half-wave plate working at 598 nm and covering a wide spectral range (300-900 nm) is demonstrated experimentally by combining both x- and y-cuts of LT plates.

  1. Spectral Unmixing of Forest Crown Components at Close Range, Airborne and Simulated Sentinel-2 and EnMAP Spectral Imaging Scale

    Directory of Open Access Journals (Sweden)

    Anne Clasen

    2015-11-01

    Full Text Available Forest biochemical and biophysical variables and their spatial and temporal distribution are essential inputs to process-orientated ecosystem models. To provide this information, imaging spectroscopy appears to be a promising tool. In this context, the present study investigates the potential of spectral unmixing to derive sub-pixel crown component fractions in a temperate deciduous forest ecosystem. However, the high proportion of foliage in this complex vegetation structure leads to the problem of saturation effects, when applying broadband vegetation indices. This study illustrates that multiple endmember spectral mixture analysis (MESMA can contribute to overcoming this challenge. Reference fractional abundances, as well as spectral measurements of the canopy components, could be precisely determined from a crane measurement platform situated in a deciduous forest in North-East Germany. In contrast to most other studies, which only use leaf and soil endmembers, this experimental setup allowed for the inclusion of a bark endmember for the unmixing of components within the canopy. This study demonstrates that the inclusion of additional endmembers markedly improves the accuracy. A mean absolute error of 7.9% could be achieved for the fractional occurrence of the leaf endmember and 5.9% for the bark endmember. In order to evaluate the results of this field-based study for airborne and satellite-based remote sensing applications, a transfer to Airborne Imaging Spectrometer for Applications (AISA and simulated Environmental Mapping and Analysis Program (EnMAP and Sentinel-2 imagery was carried out. All sensors were capable of unmixing crown components with a mean absolute error ranging between 3% and 21%.

  2. High dynamic range measurement of spectral responsivity and linearity of a radiation thermometer using a super-continuum laser and LEDs

    Science.gov (United States)

    Yoo, Y. S.; Lee, D. H.; Park, C. W.; Park, S. N.

    2013-09-01

    To realize the temperature scale above the freezing point of silver according to the definition of ITS-90, the dynamic range of the spectral responsivity is one of the most important factors which limit its uncertainty. When the residual spectral response at both side bands of a spectral band is not negligible, a significant uncertainty can be caused by a low dynamic range of the spectral responsivity measurement. In general, incandescent lamps are used to measure the spectral responsivity and the linearity. The dynamic range of the spectral responsivity measurement is often limited by a trade-off with the desired spectral resolution, which is less than 6 decades. Nonlinearity is another limiting fact of uncertainties of the temperature scale. Tungsten lamps have disadvantage in the nonlinearity measurements in terms of adjustability of radiance level and spectral selectivity. We report spectral responsivity measurements of which the measurable dynamic range is enhanced 50 times after replacing a QTH lamp with a super continuum laser. We also present a spectrally selected linearity measurement over a wide dynamic range using high-brightness light emitting diode arrays to observe a slight saturation of linearity.

  3. High dynamic range measurement of spectral responsivity and linearity of a radiation thermometer using a super-continuum laser and LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Y. S.; Lee, D. H.; Park, C. W.; Park, S. N. [Korea Research Institute of Standards and Science 209 Gajeong-Ro, Yuseong-Gu, Daejon 305-340 (Korea, Republic of)

    2013-09-11

    To realize the temperature scale above the freezing point of silver according to the definition of ITS-90, the dynamic range of the spectral responsivity is one of the most important factors which limit its uncertainty. When the residual spectral response at both side bands of a spectral band is not negligible, a significant uncertainty can be caused by a low dynamic range of the spectral responsivity measurement. In general, incandescent lamps are used to measure the spectral responsivity and the linearity. The dynamic range of the spectral responsivity measurement is often limited by a trade-off with the desired spectral resolution, which is less than 6 decades. Nonlinearity is another limiting fact of uncertainties of the temperature scale. Tungsten lamps have disadvantage in the nonlinearity measurements in terms of adjustability of radiance level and spectral selectivity. We report spectral responsivity measurements of which the measurable dynamic range is enhanced 50 times after replacing a QTH lamp with a super continuum laser. We also present a spectrally selected linearity measurement over a wide dynamic range using high-brightness light emitting diode arrays to observe a slight saturation of linearity.

  4. High dynamic range measurement of spectral responsivity and linearity of a radiation thermometer using a super-continuum laser and LEDs

    International Nuclear Information System (INIS)

    To realize the temperature scale above the freezing point of silver according to the definition of ITS-90, the dynamic range of the spectral responsivity is one of the most important factors which limit its uncertainty. When the residual spectral response at both side bands of a spectral band is not negligible, a significant uncertainty can be caused by a low dynamic range of the spectral responsivity measurement. In general, incandescent lamps are used to measure the spectral responsivity and the linearity. The dynamic range of the spectral responsivity measurement is often limited by a trade-off with the desired spectral resolution, which is less than 6 decades. Nonlinearity is another limiting fact of uncertainties of the temperature scale. Tungsten lamps have disadvantage in the nonlinearity measurements in terms of adjustability of radiance level and spectral selectivity. We report spectral responsivity measurements of which the measurable dynamic range is enhanced 50 times after replacing a QTH lamp with a super continuum laser. We also present a spectrally selected linearity measurement over a wide dynamic range using high-brightness light emitting diode arrays to observe a slight saturation of linearity

  5. Spectral optical properties of long-range transport Asian dust and pollution aerosols over Northeast Asia in 2007 and 2008

    Directory of Open Access Journals (Sweden)

    J. Jung

    2010-06-01

    Full Text Available As a part of the IGAC (International Global Atmospheric Chemistry Mega-cities program, aerosol physical and optical properties were continuously measured from March 2007 to March 2008 at an urban site (37.57° N, 126.94° E in Seoul, Korea. Spectral optical properties of long-range transported Asian dust and pollution aerosols have been investigated based on the year long measurement data. Optically measured black carbon/thermally measured elemental carbon (BC/EC ratio showed clear monthly variation with high values in summer and low values in winter mainly due to the enhancement of light attenuation by the internal mixing of EC. Novel approach has been suggested to retrieve the spectral light absorption coefficient (babs from Aethalometer raw data by using BC/EC ratio. Mass absorption efficiency, σabs (=babs/EC at 550 nm was determined to be 9.0±1.3, 8.9±1.5, 9.5±2.0, and 10.3±1.7 m2 g−1 in spring, summer, fall, and winter, respectively with an annual mean of 9.4±1.8 m2 g−1. Threshold values to classify severe haze events were suggested in this study. Increasing trend of aerosol single scattering albedo (SSA with wavelength was observed during Asian dust events while little spectral dependence of SSA was observed during long-range transport pollution (LTP events. Satellite aerosol optical thickness (AOT and Hysplit air mass backward trajectory analyses as well as chemical analysis were performed to characterize the dependence of spectral optical properties on aerosol type. Results from this study can provide useful information for studies on regional air quality and aerosol's effects on climate change.

  6. Infrared normal spectral emissivity of Ti-6Al-4V alloy in the 500-1150 K temperature range

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Fernandez, L. [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain); Industria de Turbo Propulsores, S.A., Planta de Zamudio, Edificio 300, 48170 Zamudio, Bizkaia (Spain); Risueno, E. [CIC Energigune, Parque Tecnologico, Albert Einstein 48, 01510 Minano, Alava, Spain. (Spain); Perez-Saez, R.B., E-mail: raul.perez@ehu.es [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain); Instituto de Sintesis y Estudio de Materiales, Universidad del Pais Vasco, Apdo. 644,48080 Bilbao, Spain. (Spain); Tello, M.J. [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain); Instituto de Sintesis y Estudio de Materiales, Universidad del Pais Vasco, Apdo. 644,48080 Bilbao, Spain. (Spain)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer First heating cycle acts as a annealing, relieving the surface stresses. Black-Right-Pointing-Pointer Stress relieving occurs mainly above 900 K. Black-Right-Pointing-Pointer Emissivity decreases between 0.35 and 0.10 in the 2.5-22 {mu}m spectral range. Black-Right-Pointing-Pointer Emissivity increases linearly with temperature, with the same slope for {lambda} > 10 {mu}m. Black-Right-Pointing-Pointer Good agreement between resistivity and emissivity by means of Hagen-Rubens relation. - Abstract: Thermal radiative emissivity is related to the optical and electrical properties of materials, and it is a key parameter required in a large number of industrial applications. In the case of Ti-6Al-4V, spectral emissivity experimental data are not available for the range of temperatures between 400 and 1200 K, where almost all industrial applications take place. The experimental results in this paper show that the normal spectral emissivity decreases with wavelength from a value of about 0.35 at 2.5 {mu}m to about 0.10 at 22 {mu}m. At the same time, the spectral emissivity shows a slight linear increase with temperature between 500 and 1150 K, with approximately the same slope for all wavelengths. Additionally, the influence of the samples thermal history on the emissivity is studied. A strong decrease in the emissivity values appears due to the effect of surface stress relaxation processes. This means that the radiative properties of this alloy strongly depend on the surface stress state. A thermal treatment to relieve the surface stress should be carried out to achieve a steady state of the radiative properties. In addition, a good qualitative agreement is found between the temperature dependence of the electrical resistivity obtained using conventional measurements and the one obtained from the emissivity experimental results by using the Hagen-Rubens equation.

  7. Spectral optical properties of long-range transport Asian dust and pollution aerosols over Northeast Asia in 2007 and 2008

    Directory of Open Access Journals (Sweden)

    J. Jung

    2010-02-01

    Full Text Available As a part of the IGAC (International Global Atmospheric Chemistry Mega-cities program, aerosol physical and optical properties were continuously measured from March 2007 to March 2008 at an urban site (37.57° N, 126.94° E in Seoul, Korea. Spectral optical properties of long-range transported Asian dust and pollution aerosols have been investigated based on the year long measurement data. Optically measured black carbon/thermally measured elemental carbon (BC/EC ratio showed clear monthly variation with high values in summer and low values in winter mainly due to the enhancement of light attenuation by the internal mixing of EC. Novel approach has been suggested to retrieve the spectral light absorption coefficient (babs from Aethalometer raw data by using BC/EC ratio. Mass absorption efficiency, ?abs(=babs/EC at 550 nm at the measurement site was determined to be 9.0±1.3, 8.9±1.5, 9.5±2.0, and 10.3±1.7 m2 g?1 in spring, summer, fall, and winter, respectively with an annual mean of 9.4±1.8 m2 g?1. Threshold values to classify severe haze events were suggested in this study. Increasing trend of aerosol single scattering albedo (SSA with wavelength was observed during Asian dust events while little spectral dependence of SSA was observed during long-range transport pollution (LTP events. Satellite aerosol optical thickness (AOT and Hysplit air mass backward trajectory analyses as well as chemical analysis were performed to characterize the dependence of spectral optical properties on aerosol type. Results from this study can provide useful information for studies on regional air quality and aerosol's effects on climate change.

  8. Infrared normal spectral emissivity of Ti–6Al–4V alloy in the 500–1150 K temperature range

    International Nuclear Information System (INIS)

    Highlights: ? First heating cycle acts as a annealing, relieving the surface stresses. ? Stress relieving occurs mainly above 900 K. ? Emissivity decreases between 0.35 and 0.10 in the 2.5–22 ?m spectral range. ? Emissivity increases linearly with temperature, with the same slope for ? > 10 ?m. ? Good agreement between resistivity and emissivity by means of Hagen–Rubens relation. - Abstract: Thermal radiative emissivity is related to the optical and electrical properties of materials, and it is a key parameter required in a large number of industrial applications. In the case of Ti–6Al–4V, spectral emissivity experimental data are not available for the range of temperatures between 400 and 1200 K, where almost all industrial applications take place. The experimental results in this paper show that the normal spectral emissivity decreases with wavelength from a value of about 0.35 at 2.5 ?m to about 0.10 at 22 ?m. At the same time, the spectral emissivity shows a slight linear increase with temperature between 500 and 1150 K, with approximately the same slope for all wavelengths. Additionally, the influence of the samples thermal history on the emissivity is studied. A strong decrease in the emissivity values appears due to the effect of surface stress relaxation processes. This means that the radiative properties of this alloy strongly depend on the surface stress state. A thermal treatment to relieve the surface stress should be carried out to achieve a steady state of the radiative properties. In addition, a good qualitative agreement is found between the temperature dependence of the electrical resistivity obtained using conventional measurements and the one obtained from the emissivity experimental results by using the Hagen–Rubens equation.

  9. Nonlinear spectral imaging of biological tissues

    OpenAIRE

    J. A. Palero

    2007-01-01

    The work presented in this thesis demonstrates live high resolution 3D imaging of tissue in its native state and environment. The nonlinear interaction between focussed femtosecond light pulses and the biological tissue results in the emission of natural autofluorescence and second-harmonic signal. Because biological intrinsic emission is generally very weak and extends from the ultraviolet to the visible spectral range, a broad-spectral range and high sensitivity 3D spectral imaging system i...

  10. A new undulator for the extension of the spectral range of the CLIO FEL

    International Nuclear Information System (INIS)

    We built a new undulator in order to extend the lasing range of the CLIO infrared FEL. Presently, CLIO operates in the wavelength range 2 - 17 ?m. Beyond 14 ?m, the power decreases rapidly, because of the diffraction losses of the vacuum chamber (7 mm height and 2 m long). Thus, lasing at higher wavelengths implies installing a chamber with a height approximately twice. Then the minimum gap is increased and the maximum deflection parameter, K, is reduced from 2 to 1 : the laser tunability is greatly reduced. This is why a new undulator has been built

  11. A new undulator for the extension of the spectral range of the CLIO FEL

    Energy Technology Data Exchange (ETDEWEB)

    Marcouille, O.; Berset, J.M.; Glotin, F. [LURE, Orsay (France)] [and others

    1995-12-31

    We built a new undulator in order to extend the lasing range of the CLIO infrared FEL. Presently, CLIO operates in the wavelength range 2 - 17 {mu}m. Beyond 14 {mu}m, the power decreases rapidly, because of the diffraction losses of the vacuum chamber (7 mm height and 2 m long). Thus, lasing at higher wavelengths implies installing a chamber with a height approximately twice. Then the minimum gap is increased and the maximum deflection parameter, K, is reduced from 2 to 1 : the laser tunability is greatly reduced. This is why a new undulator has been built.

  12. Microbolometer-based infrared camera for the 3-5 ?m spectral range

    Science.gov (United States)

    Budzier, Helmut; Krause, Volker; Gerlach, Gerald; Wassiliew, Dimitar

    2005-10-01

    Until now Microbolometer cameras have been operated only in the long-wave infrared range (LWIR). Since microbolometers are now available with broadband windows and acceptable absorption in the mid-wave infrared range (MWIR), they are becoming more and more interesting for the MWIR range. Primarily for industrial applications, this wavelength range offers many advantages, e.g., for the measuring of glass temperatures or for supervision of furnace rooms. To achieve a sufficiently high measuring accuracy, such crucial MWIR peculiarities like carbon dioxide absorption lines and water-vapor absorption must be known. Such problems can be avoided by usage of narrowband filters. Usually, they have to be adjusted to the particular measurement task. The newly developed camera system is based on a 320 x 240 pixels LWIR microbolometer camera system. The optical channel had to be adapted to the microbolometer. In addition, special correction and calibrating procedures were implemented for the MWIR. The camera system is suitable for stationary use in harsh industrial environments. The robust housing may be completed by integrating water-cooling and air purge for the lens system. The camera is equipped with two trigger inputs for the synchronization with the process to be measured.

  13. The spectral characteristics of Gd2SiO5:Eu3+ in VUV-UV range

    International Nuclear Information System (INIS)

    Synchrotron radiation source was used to investigated the spectral characteristics of Gd2SiO5:Eu3+ in VUV-UV range. The various energy transfers at room temperature and 10 K, including from host or Gd3+ ions to Eu3+ ions and transfer between Eu3+ ions at two different lattice sites, were discussed. In addition the emission spectra under 186 nm and 276 nm excitation were compared from the view of quantum cutting. The results indicate that Gd2SiO5:Eu3+ is a kind of material with potential high efficiency quantum cutting

  14. WDM/TDM PON experiments using the AWG free spectral range periodicity to transmit unicast and multicast data

    Science.gov (United States)

    Bock, Carlos; Prat, Josep

    2005-04-01

    A hybrid WDM/TDM PON architecture implemented by means of two cascaded Arrayed Waveguide Gratings (AWG) is presented. Using the Free Spectral Range (FSR) periodicity of AWGs we transmit unicast and multicast traffic on different wavelengths to each Optical Network Unit (ONU). The OLT is equipped with two laser stacks, a tunable one for unicast transmission and a fixed one for multicast transmission. We propose the ONU to be reflective in order to avoid any light source at the Costumer Premises Equipment (CPE). Optical transmission tests demonstrate correct transmission at 2.5 Gbps up to 30 km.

  15. Influence of temperature on Pr:YAlO3 laser operation in the orange and near-infrared spectral range

    International Nuclear Information System (INIS)

    Continuous wave Pr:YAlO3 laser behavior in the orange (622 nm) and near-infrared (747 nm) spectral range down to cryogenic temperature is reported. To minimize resonator losses, dielectric films were deposited on the crystal facets to form a microchip geometry. More than 300 mW of output power at 747 nm wavelength with a slope efficiency close to the quantum limit is demonstrated. Furthermore, the first diode-pumped Pr:YAlO3 orange laser is described, as we believe. (letter)

  16. Influence of temperature on Pr:YAlO3 laser operation in the orange and near-infrared spectral range

    Science.gov (United States)

    Fibrich, M.; Šulc, J.; Jelínková, H.

    2014-10-01

    Continuous wave Pr:YAlO3 laser behavior in the orange (622 nm) and near-infrared (747 nm) spectral range down to cryogenic temperature is reported. To minimize resonator losses, dielectric films were deposited on the crystal facets to form a microchip geometry. More than 300 mW of output power at 747 nm wavelength with a slope efficiency close to the quantum limit is demonstrated. Furthermore, the first diode-pumped Pr:YAlO3 orange laser is described, as we believe.

  17. Long- and Short-Range Electrostatic Fields in GFP Mutants: Implications for Spectral Tuning.

    Science.gov (United States)

    Drobizhev, M; Callis, P R; Nifosì, R; Wicks, G; Stoltzfus, C; Barnett, L; Hughes, T E; Sullivan, P; Rebane, A

    2015-01-01

    The majority of protein functions are governed by their internal local electrostatics. Quantitative information about these interactions can shed light on how proteins work and allow for improving/altering their performance. Green fluorescent protein (GFP) and its mutation variants provide unique optical windows for interrogation of internal electric fields, thanks to the intrinsic fluorophore group formed inside them. Here we use an all-optical method, based on the independent measurements of transition frequency and one- and two-photon absorption cross sections in a number of GFP mutants to evaluate these internal electric fields. Two physical models based on the quadratic Stark effect, either with or without taking into account structural (bond-length) changes of the chromophore in varying field, allow us to separately evaluate the long-range and the total effective (short- and long-range) fields. Both types of the field quantitatively agree with the results of independent molecular dynamic simulations, justifying our method of measurement. PMID:26286372

  18. The relationship between professional operatic soprano voice and high range spectral energy

    Science.gov (United States)

    Barnes, Jennifer J.; Davis, Pamela; Oates, Jennifer; Chapman, Janice

    2004-07-01

    Operatic sopranos need to be audible over an orchestra yet they are not considered to possess a singer's formant. As in other voice types, some singers are more successful than others at being heard and so this work investigated the frequency range of the singer's formant between 2000 and 4000 Hz to consider the question of extra energy in this range. Such energy would give an advantage over an orchestra, so the aims were to ascertain what levels of excess energy there might be and look at any relationship between extra energy levels and performance level. The voices of six operatic sopranos (national and international standard) were recorded performing vowel and song tasks and subsequently analyzed acoustically. Measures taken from vowel data were compared with song task data to assess the consistency of the approaches. Comparisons were also made with regard to two conditions of intended projection (maximal and comfortable), two song tasks (anthem and aria), two recording environments (studio and anechoic room), and between subjects. Ranking the singers from highest energy result to lowest showed the consistency of the results from both vowel and song methods and correlated reasonably well with the performance level of the subjects. The use of formant tuning is considered and examined.

  19. Exploring negative refraction conditions for quantum cascade semiconductor metamaterials in the terahertz spectral range

    Science.gov (United States)

    Daničić, A.; Radovanović, J.; Ramović, S.; Milanović, V.

    2016-03-01

    In order to avoid losses in metamaterial unit cells at frequencies of interest, caused by metallic inclusions, an active medium design has been proposed. As candidate structures for this active medium, we have chosen quantum cascade lasers because of their high output gain. Here we analyze and compare two quantum cascade structures that emit at 4.6 THz and 3.9 THz, respectively, placed under the influence of a strong magnetic field. We first solve the full system of rate equations for all relevant Landau levels, and obtain the necessary information about carrier distribution among the levels, after which we are able to evaluate the permittivity component along the growth direction of the structure. With these data one can determine the conditions under which negative refraction occurs, and calculate the values of the refractive index of the structure, as well as the range of frequencies at which the structure exhibits negative refraction for a predefined total electron sheet density.

  20. Measurement of the luminescence decay times of PbS quantum dots in the near-IR spectral range

    Science.gov (United States)

    Parfenov, P. S.; Litvin, A. P.; Baranov, A. V.; Ushakova, E. V.; Fedorov, A. V.; Prudnikov, A. V.; Artemyev, M. V.

    2012-06-01

    Methods for recording luminescence decay times of semiconductor PbS quantum dots (QDs) with optical transitions in the near-IR spectral range have been analyzed. A measuring complex for spectral and kinetic analysis in the near-IR range (0.8-2.0 ?m) in the time interval from several tens of nanoseconds to several tens of microseconds is described. In this complex, a semiconductor picosecond laser is used as an excitation source; luminescence decay times are recorded by a fast InGaAs photodiode, a high-speed amplifier, and a high-frequency oscilloscope; and the measurement results are multiply averaged (up to a million times) by a program. The technical features of this method are discussed and compared with the characteristics of techniques based on photon counting or application of more powerful radiation sources, and the limitations on sensitivity are analyzed. The results of measuring the luminescence decay kinetics of PbS QDs 2.7-7.6 nm in size prepared in the form of solutions and incorporated into matrices are reported.

  1. Temperature-dependent dielectric function of germanium in the UV–vis spectral range: A first-principles study

    International Nuclear Information System (INIS)

    The study of temperature dependence of thermophysical parameter dielectric function is key to understanding thermal radiative transfer in high-temperature environments. Limited by self-radiation and thermal oxidation, however, it is difficult to directly measure the high-temperature dielectric function of solids with present experimental technologies. In this work, we implement two first-principles methods, the ab initio molecular dynamics (AIMD) and density functional perturbation theory (DFPT), to study the temperature dependence of dielectric function of germanium (Ge) in the UV–vis spectral range in order to provide data of high-temperature dielectric function for radiative transfer study in high-temperature environments. Both the two methods successfully predict the temperature dependence of dielectric function of Ge. Moreover, the good agreement between the calculated results of the AIMD approach and experimental data at 825 K enables us to predict the high-temperature dielectric function of Ge with the AIMD method in the UV–vis spectral range. - Highlights: • The temperature dependence of dielectric function of germanium (Ge) is investigated with two first-principles methods. • The temperature effect on dielectric function of Ge is discussed. • The high-temperature dielectric function of Ge is predicted

  2. Chlorine detection in cement with laser-induced breakdown spectroscopy in the infrared and ultraviolet spectral range

    International Nuclear Information System (INIS)

    A significant parameter to monitor the status of concrete buildings like bridges or parking garages is the determination of the depth profile of the chlorine concentration below the exposed concrete surface. This information is required to define the needed volume of restoration for a construction. Conventional methods like wet chemical analysis are time- and cost-intensive so an alternative method is developed using laser-induced breakdown spectroscopy (LIBS). The idea is to deploy LIBS to analyze drill cores by scanning the sample surface with laser pulses. Chlorine spectral lines in the infrared (IR) and ultraviolet (UV)-range were studied for chlorine detection in hydrated cement samples. The excitation energies of these spectral lines are above 9.2 eV. Hence high plasma temperatures and pulse energies in the range of some hundred millijoules are needed to induce sufficient line intensity levels at the required working distance. To further increase the line intensity and to lower the detection limit (LOD) of chlorine a measuring chamber is used where different ambient pressures and gases can be chosen for the measurements. The influences on the line intensity for pressures between 5 mbar and 400 mbar using helium as process gas and the influence of different laser burst modi like single and collinear double pulses are investigated. For the first time a LOD according to DIN 32 645 of 0.1 mass% was achieved for chlorine in hydrated cement using the UV line 134.72 nm.

  3. Tuning of resonance spacing over whole free spectral range based on Autler-Townes splitting in a single microring resonator.

    Science.gov (United States)

    Gao, Ge; Li, Danping; Zhang, Yong; Yuan, Shuai; Armghan, Ammar; Huang, Qingzhong; Wang, Yi; Yu, Jinzhong; Xia, Jinsong

    2015-10-19

    In this paper, a single microring resonator structure formed by incorporating a reflectivity-tunable loop mirror is demonstrated for the tuning of resonance spacing. Autler-Townes splitting in the resonator is utilized to tune the spacing between two adjacent resonances by controlling the strength of coupling between the two counter-propagating degenerate modes in the microring resonator. A theoretical model based on the transfer matrix method is built to analyze the device. The theoretical analysis indicates that the resonance spacing can be tuned from zero to one free spectral range (FSR). In experiment, by integrating metallic microheater, the tuning of resonance spacing in the range of the whole FSR (1.17 nm) is achieved within 9.82 mW heating power dissipation. The device has potential for applications in reconfigurable optical filtering and microwave photonics. PMID:26480351

  4. Calculation of spectral shifts in UV–visible region and photoresponsive behaviour of fluorinated liquid crystals: Effect of solvent and substituent

    International Nuclear Information System (INIS)

    The photoresponsive behaviour of fluorinated liquid crystals p-phenylene-4-methoxy benzoate-4-trifluoromethylbenzoate (FLUORO1), and 4-propyloxyphenyl-4-(4-trifluoromethylbenzoyloxy) benzoate (FLUORO2) has been systematically investigated using the CNDO/S + CI and INDO/S + CI methods. These methods have been employed to calculate/analyze the spectral shifts, and absorbance measurements in UV–visible region of the systems. The electronic transitions, absorption wavelength, HOMO (highest occupied molecular orbital), and LUMO (lowest unoccupied molecular orbital) energies have been calculated. Further, ultraviolet (UV) stability of the molecules has been discussed in the light of absorption wavelength and electronic transition oscillator strength (f). The effect of different solvent media and substituents on transition energies, oscillator strength, and other absorption parameters have also been reported. The present article provides valuable information regarding enhancing the UV stability of molecules by marinating their conductivity. Highlights: ► The strongest bands of FLUORO molecules can be assigned as π → π∗ transitions. ► A small red-shift indicates a weak exciton coupling of chromophores. ► No n → π∗ transition occurs due to the rigidity of the ring system of the molecules. ► The HOMO, LUMO, and Eg values have been found to be independent of solvent effect.

  5. Novel SO2 spectral evaluation scheme using the 360–390 nm wavelength range

    Directory of Open Access Journals (Sweden)

    T. Wagner

    2010-03-01

    Full Text Available Differential Optical Absorption Spectroscopy (DOAS is a well established spectroscopic method to determine trace gases in the atmosphere. During the last decade, passive DOAS, which uses solar radiation scattered in the atmosphere as a light source, has become a standard tool to determine SO2 column densities and emission fluxes from volcanoes and other large sources by ground based as well as satellite measurements. For the determination of SO2 column densities, the structured absorption of the molecule in the 300–330 nm region (due to the A1B1?X1A1 transition is used. However, there are several problems limiting the accuracy of the technique in this particular application. Here we propose to use an alternative wavelength region (360–390 nm due to the spin-forbidden a3B2?X1A1 transition for the DOAS evaluation of SO2 in conditions where high SO2 column densities prevail. We show this range to have considerable advantages in such cases, in particular when the particle content of the plume is high and when measurements are performed at large distances from the area of interest.

  6. An in-vacuum wiggler for SOLEIL Hard X-rays spectral range

    International Nuclear Information System (INIS)

    The production of Hard X-rays has become a tricky problem on medium energy storage rings. It requires Insertion Devices (IDs) with high magnetic field and a large number of periods. To cover the 20-50 keV photon energy range at SOLEIL (2.75 GeV), an in-vacuum wiggler (WSV50) has been preferred to a superconducting ID. The wiggler is composed of 38 periods of 50 mm producing a 2.1 T field at a minimum magnetic gap of 5.5 mm. To minimize the magnetic forces acting between magnet arrays (8.5 tons), a compensation system composed of non magnetic springs has been mounted apart from the magnet system to reduce the mechanical deformations. The wiggler has been assembled step by step by means of a genetic algorithm which minimizes the magnetic errors measured with a flipping coil. This paper presents the mechanical and magnetic design of the wiggler as well as the construction and the magnetic measurements.

  7. Spectral shift by half free-spectral-range for microring resonator employing the phase jump phenomenon in coupled-waveguide and application on all-microring wavelength interleaver.

    Science.gov (United States)

    Shih, Chih T'sung; Chao, Shiuh

    2009-05-11

    Using coupled-mode theory, we have shown that there is a pi phase jump between the input and the through/drop fields of a codirectional coupler when the gap width between the coupled-waveguides reaches certain values such that the length of the coupler equals to the odd integer (for through field) or even integer (for drop field) times of the Transfer Distance. We introduced an efficient numerical method based on combining the scattering matrix method and FDTD method for analyzing a microring that has material loss. By applying this method, we found that the phase jump phenomenon also occurs in a half-ring coupler when the gap width between the coupled half-ring waveguides reaches a critical value. We showed that, for a given operating bandwidth, it is important that the gap width between the rings has to be larger than a certain value in order to avoid the phase jump, or smaller in order to take advantage of the phase jump. Based on the phase jump phenomenon, we found that the through and the drop spectra of the single-arm and the double-arm microring can be manipulated to shift about one half free spectral range by selecting appropriate gap widths. A novel all-microring wavelength interleaver, based on the phase jump phenomenon, is proposed and numerically demonstrated. PMID:19434107

  8. Direct milling and casting of polymer-based optical waveguides for improved transparency in the visible range

    DEFF Research Database (Denmark)

    Snakenborg, Detlef; Perozziello, Gerardo; Klank, Henning; Geschke, Oliver; Kutter, Jörg Peter

    2006-01-01

    properties. Direct micromilling enabled us to fabricate 100 mu m wide optical waveguides. Propagation losses of less than 1 dB cm(-1) could be achieved throughout the entire visual range down to a wavelength of 400 nm. A casting process amenable to high number production of such devices was furthermore...

  9. Photometric calibration of soft x-ray and p-terphenyl coated visible photodiodes in the 180--1500 eV range for fusion plasma spectroscopy

    International Nuclear Information System (INIS)

    The efficiencies of x-ray ultraviolet silicon, and p-terphenyl coated visible photodiodes have been measured in the 180--1500 eV range using a K radiation-Manson source. It is found that the quantum efficiency (electrons/photon) of the silicon diode varies between 25 and 400 in the above-mentioned range; the p-terphenyl coated diode is by two orders of magnitude less performing at the high-energy end of the range considered, but approaches the efficiency of the silicon diode at 100 A. Such diodes with built-in amplifiers, coated with scintillator and thin layers of metal films, can be efficiently used in spectroscopic diagnostics of magnetically confined plasmas

  10. Development and testing of a fast Fourier transform high dynamic-range spectral diagnostics for millimeter wave characterization

    International Nuclear Information System (INIS)

    A fast Fourier transform (FFT) based wide range millimeter wave diagnostics for spectral characterization of scattered millimeter waves in plasmas has been successfully brought into operation. The scattered millimeter waves are heterodyne downconverted and directly digitized using a fast analog-digital converter and a compact peripheral component interconnect computer. Frequency spectra are obtained by FFT in the time domain of the intermediate frequency signal. The scattered millimeter waves are generated during high power electron cyclotron resonance heating experiments on the TEXTOR tokamak and demonstrate the performance of the diagnostics and, in particular, the usability of direct digitizing and Fourier transformation of millimeter wave signals. The diagnostics is able to acquire 4 GHz wide spectra of signals in the range of 136-140 GHz. The rate of spectra is tunable and has been tested between 200 000 spectra/s with a frequency resolution of 100 MHz and 120 spectra/s with a frequency resolution of 25 kHz. The respective dynamic ranges are 52 and 88 dB. Major benefits of the new diagnostics are a tunable time and frequency resolution due to postdetection, near-real time processing of the acquired data. This diagnostics has a wider application in astrophysics, earth observation, plasma physics, and molecular spectroscopy for the detection and analysis of millimeter wave radiation, providing high-resolution spectra at high temporal resolution and large dynamic range.

  11. An SPR-based sensor with an extremely large dynamic range of refractive index measurements in the visible region

    Science.gov (United States)

    Mishra, Akhilesh K.; Mishra, Satyendra K.; Verma, Rajneesh K.

    2015-11-01

    A promising GaP prism-based surface plasmon resonance sensor in the Kretschmann configuration with an extremely large dynamic range of refractive index detection is proposed. The prism base is coated with a gold layer and then a thin layer of silicon. The sensor is studied theoretically in terms of sensitivity and detection accuracy. The proposed sensor shows the potential of sensing media with a refractive index varying from gaseous to very dense liquid with appreciably high sensitivity.

  12. Satellite monitoring of different vegetation types by differential optical absorption spectroscopy (DOAS in the red spectral range

    Directory of Open Access Journals (Sweden)

    T. Wagner

    2007-01-01

    Full Text Available A new method for the satellite remote sensing of different types of vegetation and ocean colour is presented. In contrast to existing algorithms relying on the strong change of the reflectivity in the red and near infrared spectral region, our method analyses weak narrow-band (few nm reflectance structures (i.e. "fingerprint" structures of vegetation in the red spectral range. It is based on differential optical absorption spectroscopy (DOAS, which is usually applied for the analysis of atmospheric trace gas absorptions. Since the spectra of atmospheric absorption and vegetation reflectance are simultaneously included in the analysis, the effects of atmospheric absorptions are automatically corrected (in contrast to other algorithms. The inclusion of the vegetation spectra also significantly improves the results of the trace gas retrieval. The global maps of the results illustrate the seasonal cycles of different vegetation types. In addition to the vegetation distribution on land, they also show patterns of biological activity in the oceans. Our results indicate that improved sets of vegetation spectra might lead to more accurate and more specific identification of vegetation type in the future.

  13. New methods of highly efficient controlled generation of radiation by liquid crystal nanostructures in a wide spectral range

    International Nuclear Information System (INIS)

    We report the recent results of research focused on a new kind of soft matter-the liquid-crystal nanocomposites with controllable mechanical and nonlinear optical properties. These are promising media for implementation of ultra-compact photonic devices and efficient sources of coherent radiation in a wide spectral range. We overview the technology of preparation of nematic-liquid-crystal media saturated with disclination defects. The defects were formed in different ways: by embedding nanoparticles and molecular objects, by exposure to alpha-particle flux. The defect locations were controlled by applying an electric field. We also present and discuss the recently discovered features of nematic-liquid-crystal media: a thermal orientation effect leading to the fifth-order optical nonlinearity, enormous second-order susceptibility revealed by measurements, and structural changes upon exposure to laser radiation. We report on efficient generation of harmonics, sum and difference optical frequencies in nematic-liquid-crystal media. In addition, transformation of laser radiation spectra to spectral supercontinua, and filamentation of laser beams were also observed in nematic-liquid-crystal media. We conclude that most nonlinear optical effects result from changes of the orientational order in the examined nematic liquid crystals. These changes lead to the symmetry breaking and disclination appearances.

  14. Fully automated dual-frequency three-pulse-echo 2DIR spectrometer accessing spectral range from 800 to 4000 wavenumbers

    Energy Technology Data Exchange (ETDEWEB)

    Leger, Joel D.; Nyby, Clara M.; Varner, Clyde; Tang, Jianan; Rubtsova, Natalia I.; Yue, Yuankai; Kireev, Victor V.; Burtsev, Viacheslav D.; Qasim, Layla N.; Rubtsov, Igor V., E-mail: irubtsov@tulane.edu [Department of Chemistry, Tulane University, New Orleans, Louisiana 70118 (United States); Rubtsov, Grigory I. [Institute for Nuclear Research of the Russian Academy of Sciences, Moscow 117312 (Russian Federation)

    2014-08-15

    A novel dual-frequency two-dimensional infrared instrument is designed and built that permits three-pulse heterodyned echo measurements of any cross-peak within a spectral range from 800 to 4000 cm{sup ?1} to be performed in a fully automated fashion. The superior sensitivity of the instrument is achieved by a combination of spectral interferometry, phase cycling, and closed-loop phase stabilization accurate to ?70 as. The anharmonicity of smaller than 10{sup ?4} cm{sup ?1} was recorded for strong carbonyl stretching modes using 800 laser shot accumulations. The novel design of the phase stabilization scheme permits tuning polarizations of the mid-infrared (m-IR) pulses, thus supporting measurements of the angles between vibrational transition dipoles. The automatic frequency tuning is achieved by implementing beam direction stabilization schemes for each m-IR beam, providing better than 50 ?rad beam stability, and novel scheme for setting the phase-matching geometry for the m-IR beams at the sample. The errors in the cross-peak amplitudes associated with imperfect phase matching conditions and alignment are found to be at the level of 20%. The instrument can be used by non-specialists in ultrafast spectroscopy.

  15. A HIGH-RESOLUTION, MULTI-EPOCH SPECTRAL ATLAS OF PECULIAR STARS INCLUDING RAVE, GAIA , AND HERMES WAVELENGTH RANGES

    International Nuclear Information System (INIS)

    We present an Echelle+CCD, high signal-to-noise ratio, high-resolution (R = 20,000) spectroscopic atlas of 108 well-known objects representative of the most common types of peculiar and variable stars. The wavelength interval extends from 4600 to 9400 A and includes the RAVE, Gaia, and HERMES wavelength ranges. Multi-epoch spectra are provided for the majority of the observed stars. A total of 425 spectra of peculiar stars, which were collected during 56 observing nights between 1998 November and 2002 August, are presented. The spectra are given in FITS format and heliocentric wavelengths, with accurate subtraction of both the sky background and the scattered light. Auxiliary material useful for custom applications (telluric dividers, spectrophotometric stars, flat-field tracings) is also provided. The atlas aims to provide a homogeneous database of the spectral appearance of stellar peculiarities, a tool useful both for classification purposes and inter-comparison studies. It could also serve in the planning and development of automated classification algorithms designed for RAVE, Gaia, HERMES, and other large-scale spectral surveys. The spectrum of XX Oph is discussed in some detail as an example of the content of the present atlas.

  16. Quantum efficiency of cesium iodide photocathodes in the 120-220 nm spectral range traceable to a primary detector standard

    CERN Document Server

    Rabus, H; Richter, M; Ulm, G; Friese, J; Gernhäuser, R; Kastenmüller, A; Maier-Komor, P; Zeitelhack, K

    1999-01-01

    Differently prepared CsI samples have been investigated in the 120-220 nm spectral range for their quantum efficiency, spatial uniformity and the effect of radiation aging. The experiments were performed at the PTB radiometry laboratory at the Berlin synchrotron radiation facility BESSY. A calibrated GaAsP Schottky photodiode was used as transfer detector standard to establish traceability to the primary detector standard, because this type of photodiode - unlike silicon p-on-n photodiodes - proved to be of sufficiently stable response when exposed to vacuum ultraviolet radiation. The paper reviews the experimental procedures that were employed to characterize and calibrate the GaAsP photodiode and reports the results that were obtained on the investigated CsI photocathodes.

  17. Spectral line lists of a nitrogen gas discharge for wavelength calibration in the range $4500-11000$cm$^{-1}$

    CERN Document Server

    Boesch, A

    2015-01-01

    A discharge of nitrogen gas, as created in a microwave-induced plasma, exhibits a very dense molecular emission line spectrum. Emission spectra of this kind could serve as wavelength calibrators for high-resolution astrophysical spectrographs in the near-infrared, where only very few calibration sources are currently available. The compilation of a spectral line list and the characterization of line intensities and line density belong to the initial steps when investigating the feasibility of potential wavelength calibration sources. Although the molecular nitrogen spectrum was extensively studied in the past, to our knowledge, no line list exists that covers a continuous range of several thousand wavenumbers in the near-infrared. We recorded three high-resolution ($\\Delta \\tilde{\

  18. Spectral counting assessment of protein dynamic range in cerebrospinal fluid following depletion with plasma-designed immunoaffinity columns

    Directory of Open Access Journals (Sweden)

    Borg Jacques

    2011-06-01

    Full Text Available Abstract Background In cerebrospinal fluid (CSF, which is a rich source of biomarkers for neurological diseases, identification of biomarkers requires methods that allow reproducible detection of low abundance proteins. It is therefore crucial to decrease dynamic range and improve assessment of protein abundance. Results We applied LC-MS/MS to compare the performance of two CSF enrichment techniques that immunodeplete either albumin alone (IgYHSA or 14 high-abundance proteins (IgY14. In order to estimate dynamic range of proteins identified, we measured protein abundance with APEX spectral counting method. Both immunodepletion methods improved the number of low-abundance proteins detected (3-fold for IgYHSA, 4-fold for IgY14. The 10 most abundant proteins following immunodepletion accounted for 41% (IgY14 and 46% (IgYHSA of CSF protein content, whereas they accounted for 64% in non-depleted samples, thus demonstrating significant enrichment of low-abundance proteins. Defined proteomics experiment metrics showed overall good reproducibility of the two immunodepletion methods and MS analysis. Moreover, offline peptide fractionation in IgYHSA sample allowed a 4-fold increase of proteins identified (520 vs. 131 without fractionation, without hindering reproducibility. Conclusions The novelty of this study was to show the advantages and drawbacks of these methods side-to-side. Taking into account the improved detection and potential loss of non-target proteins following extensive immunodepletion, it is concluded that both depletion methods combined with spectral counting may be of interest before further fractionation, when searching for CSF biomarkers. According to the reliable identification and quantitation obtained with APEX algorithm, it may be considered as a cheap and quick alternative to study sample proteomic content.

  19. Turbulent spectra and spectral kinks in the transition range from MHD to kinetic Alfv\\'en turbulence

    CERN Document Server

    Voitenko, Yuriy

    2011-01-01

    A weakly dispersive sub-range (WDR) of kinetic Alfv\\'en turbulence is distinguished and investigated for the first time in the context of MHD/kinetic turbulence transition. We found perpendicular wavenumber spectra ~ k^{-3} and ~ k^{-4} formed in WDR by strong and weak turbulence of kinetic Alfv\\'en waves (KAWs), respectively. These steep WDR spectra connect shallower spectra in the MHD and strongly dispersive KAW sub-ranges, which results in a specific double-kink (2-k) pattern often seen in observed turbulent spectra. The first kink occurs where MHD turbulence transforms into weakly dispersive KAW turbulence; the second one is between weakly and strongly dispersive KAW sub-ranges. Our analysis suggests that the partial turbulence dissipation due to amplitude-dependent super-adiabatic ion heating may occur in the vicinity of the first spectral kink. A threshold-like nature of this process results in a conditional selective dissipation affecting only largest over-threshold amplitudes and decreasing intermitte...

  20. Ultra-wide-range measurements of thin-film filter optical density over the visible and near-infrared spectrum.

    Science.gov (United States)

    Lequime, Michel; Liukaityte, Simona; Zerrad, Myriam; Amra, Claude

    2015-10-01

    We present the improved structure and operating principle of a spectrophotometric mean that allows us for the recording of the transmittance of a thin-film filter over an ultra-wide range of optical densities (from 0 to 11) between 400 and 1000 nm. The operation of this apparatus is based on the combined use of a high power supercontinuum laser source, a tunable volume hologram filter, a standard monochromator and a scientific grade CCD camera. The experimentally recorded noise floor is in good accordance with the optical density values given by the theoretical approach. A demonstration of the sensitivity gain provided by this new set-up with respect to standard spectrophotometric means is performed via the characterization of various types of filters (band-pass, long-pass, short-pass, and notch). PMID:26480197

  1. A quantitative comparison of {sup {alpha}}-A turbidity parameter retrieved in different spectral ranges based on spectroradiometer solar radiation measurements

    Energy Technology Data Exchange (ETDEWEB)

    Cachorro, V.E.; Vergaz, R.; Frutos, A.M. de [University of Valladolid (Spain). Atmospheric Optics Group

    2001-07-01

    Spectroradiometric direct irradiance measurements in the 300-1100nm wavelength range with a spectral resolution of 6.2nm have been used in a study of the variation in the Angstrom turbidity parameter {alpha} and its dependence on the spectral range used in its determination. The measurements have been carried out under clear sky conditions at two different climate stations in Spain. Least-square fits of the experimental spectral aerosol optical depth (AOD) to the Angstrom formula in different spectral ranges, selected for convenience depending on the objective or application (e.g., UV-VIS (350-400nm), VIS (400-670nm), VIS-NIR (370-870nm), etc.), result in different sets for the {alpha} parameter. Due to this dependence on the spectral range, where the {alpha}-values are determined, a quantitative comparative analysis is carried out in order to assess the differences for a given data-base covering very different atmospheric conditions. The study reveals the necessity of a 'standard spectral range' to achieve confident data comparisons. We show some applications that are relevant for aerosol studies, from UV absorption by aerosols to satellite remote sensing. (author)

  2. Multispectral measurement of contrast in tissue-mimicking phantoms in near-infrared spectral range of 650 to 1600 nm.

    Science.gov (United States)

    Salo, Daniel; Zhang, Hairong; Kim, David M; Berezin, Mikhail Y

    2014-08-01

    In order to identify the optimal imaging conditions for the highest spatial contrast in biological tissue, we explored the properties of a tissue-mimicking phantom as a function of the wavelengths in a broad range of near-infrared spectra (650 to 1600 nm). Our customized multispectral hardware, which featured a scanning transmission microscope and imaging spectrographs equipped with silicon and InGaAs charge-coupled diode array detectors, allowed for direct comparison of the Michelson contrast obtained from a phantom composed of a honeycomb grid, Intralipid, and India ink. The measured contrast depended on the size of the grid, luminance, and the wavelength of measurements. We demonstrated that at low thickness of the phantom, a reasonable contrast of the objects can be achieved at any wavelength between 700 and 1400 nm and between 1500 and 1600 nm. At larger thicknesses, such contrast can be achieved mostly between 1200 and 1350 nm. These results suggest that distinguishing biological features in deep tissue and developing contrast agents for in vivo may benefit from imaging in this spectral range. PMID:25104414

  3. Observing ice clouds in the submillimeter spectral range: the CloudIce mission proposal for ESA's Earth Explorer 8

    Directory of Open Access Journals (Sweden)

    S. A. Buehler

    2012-02-01

    Full Text Available Passive submillimeter-wave sensors are a way to obtain urgently needed global data on ice clouds, particularly on the so far poorly characterized "essential climate variable" ice water path (IWP and on ice particle size. CloudIce was a mission proposal to the European Space Agency ESA in response to the call for Earth Explorer 8 (EE8, which ran in 2009/2010. It proposed a passive submillimeter-wave sensor with channels ranging from 183 GHz to 664 GHz. The article describes the CloudIce mission proposal, with particular emphasis on describing the algorithms for the data-analysis of submillimeter-wave cloud ice data (retrieval algorithms and demonstrating their maturity. It is shown that we have a robust understanding of the radiative properties of cloud ice in the millimeter/submillimeter spectral range, and that we have a proven toolbox of retrieval algorithms to work with these data. Although the mission was not selected for EE8, the concept will be useful as a reference for other future mission proposals.

  4. Valid ranges for using the cross-power spectral density phase angle for moderator temperature coefficient sign determination

    International Nuclear Information System (INIS)

    The value of the moderator temperature coefficient (MTC) of reactivity is contained in correlations between fluctuations of the neutron flux and core-exit coolant temperature. The absolute magnitude of the MTC is obtained from noise analysis by using the root-mean-square method and the frequency response function technique. Both approaches are used in conjunction with the phase angle method, which determines the MTC sign, to obtain complete information about the MTC. Analytical expressions that are derived show that a limitation exists on the range of MTC values for which the cross-power spectral density phase angle can be used to establish the MTC sign. This research shows that small positive values of the MTC (an unstable condition) can result in a -180-deg phase angle shift, contrary to earlier studies that indicated a stable reactor. The range of sign determinate MTC values is dependent on the driving noise source. Simulated noise data are generated for different MTC values and analyzed to verify the theoretical work. A comparison of the indeterminate regions to allowable MTC values for an operating pressurized water reactor is also presented

  5. Visible Light Induces Melanogenesis in Human Skin through a Photoadaptive Response

    OpenAIRE

    Randhawa, Manpreet; Seo, InSeok; Liebel, Frank; Southall, Michael D.; Kollias, Nikiforos; Ruvolo, Eduardo

    2015-01-01

    Visible light (400–700 nm) lies outside of the spectral range of what photobiologists define as deleterious radiation and as a result few studies have studied the effects of visible light range of wavelengths on skin. This oversight is important considering that during outdoors activities skin is exposed to the full solar spectrum, including visible light, and to multiple exposures at different times and doses. Although the contribution of the UV component of sunlight to skin damage has been ...

  6. Visible-range hybrid femtosecond systems based on a XeF(C-A) amplifier: state of the art and prospects

    Energy Technology Data Exchange (ETDEWEB)

    Alekseev, S V; Aristov, A I; Grudtsyn, Ya V; Ivanov, N G; Koval' chuk, B M; Losev, B F; Mamaev, S B; Mesyats, Gennadii A; Mikheev, L D; Panchenko, Yu N; Polivin, A V; Stepanov, S G; Ratakhin, N A; Yalovoi, V I; Yastremskii, Arkadii G

    2013-03-31

    Results of experimental and theoretical investigations of the hybrid (solid state/gas) visible-range femtosecond systems THL-100 (IHCE SB RAS) and THL-30 (P.N. Lebedev Physics Institute) based on a Ti : sapphire front end and a photochemical XeF(C-A) amplifier are reported. The front end generates 50-fs optical pulses with the second-harmonic (475 nm) energy of up to 5 mJ. The active medium of the amplifier is produced in a mixture XeF{sub 2} - N{sub 2} subjected to VUV radiation of xenon excited by an electron beam. The computer model is developed for calculating parameters of the XeF(C - A) amplifier, which is in a good agreement with experiments. In the THL-100 system with the 25-cm output aperture of the XeF(C-A) amplifier, a record visible-range femtosecond radiation peak power of 14 GW was obtained in a 50-fs pulse with the time contrast of above 10{sup 8}. The measured power of an amplified spontaneous emission of the XeF(C-A) amplifier in the angle of 0.2 mrad was 32 W. The result obtained testifies that the hybrid approach to the development of ultrahigh-power systems provides a high time contrast of radiation (greater than 10{sup 12} for the projected peak power of 100 TW). In the THL-30 system, prospects for shortening an amplified femtosecond pulse are studied and it is experimentally shown that by compensating a third-order dispersion in a hybrid system one can obtain pulses with duration of at least 27 fs with a recompression of amplified pulses in bulk glass. Also, a new phenomenon was observed of spectrum broadening and self-compression of negatively chirped femtosecond pulses in the visible range under a nonlinear interaction of wide-aperture beams with fused silica. This result opens prospects for development of the new methods of selfcompression for femtosecond pulses that are lacking physical limitations on pulse energy and realisation of self-compression of amplified pulses in the output window of the XeF(C-A) amplifier. (extreme light fields and their applications)

  7. A new facility for the synchrotron radiation-based calibration of transfer radiation sources in the ultraviolet and vacuum ultraviolet spectral range

    Energy Technology Data Exchange (ETDEWEB)

    Thornagel, Reiner; Fliegauf, Rolf; Klein, Roman, E-mail: roman.klein@ptb.de; Kroth, Simone; Paustian, Wolfgang; Richter, Mathias [Physikalisch-Technische Bundesanstalt (PTB), Berlin (Germany)

    2015-01-15

    The Physikalisch-Technische Bundesanstalt (PTB) has a long tradition in the calibration of radiation sources in the ultraviolet and vacuum ultraviolet spectral range, with traceability to calculable synchrotron radiation. Within this context, new instrumentation in the PTB laboratory at the Metrology Light Source (MLS) has been put into operation that opens up extended and improved calibration possibilities. A new facility for radiation source calibrations has been set up in the spectral range from 7 nm to 400 nm based on a combined normal incidence-grazing incidence monochromator. The facility can be used for the calibration of transfer sources in terms of spectral radiant intensity or mean spectral radiance, with traceability to the MLS primary source standard. We describe the design and performance of the experimental station and give examples of some commissioning results.

  8. X-ray grating spectrometer for opacity measurements in the 50 eV to 250 eV spectral range at the LULI 2000 laser facilitya)

    Science.gov (United States)

    Reverdin, Charles; Thais, Frédéric; Loisel, Guillaume; Busquet, M.; Bastiani-Ceccotti, S.; Blenski, T.; Caillaud, T.; Ducret, J. E.; Foelsner, W.; Gilles, D.; Gilleron, F.; Pain, J. C.; Poirier, M.; Serres, F.; Silvert, V.; Soullie, G.; Turck-Chieze, S.; Villette, B.

    2012-10-01

    An x-ray grating spectrometer was built in order to measure opacities in the 50 eV to 250 eV spectral range with an average spectral resolution ?E/?E? ˜ 50. It has been used at the LULI-2000 laser facility at École Polytechnique (France) to measure the ?n = 0, n = 3 transitions of several elements with neighboring atomic number: Cr, Fe, Ni, and Cu in the same experimental conditions. Hence a spectrometer with a wide spectral range is required. This spectrometer features one line of sight looking through a heated sample at backlighter emission. It is outfitted with one toroidal condensing mirror and several flat mirrors cutting off higher energy photons. The spectral dispersion is obtained with a flatfield grating. Detection consists of a streak camera sensitive to soft x-ray radiation. Some experimental results showing the performance of this spectrometer are presented.

  9. A new facility for the synchrotron radiation-based calibration of transfer radiation sources in the ultraviolet and vacuum ultraviolet spectral range

    Science.gov (United States)

    Thornagel, Reiner; Fliegauf, Rolf; Klein, Roman; Kroth, Simone; Paustian, Wolfgang; Richter, Mathias

    2015-01-01

    The Physikalisch-Technische Bundesanstalt (PTB) has a long tradition in the calibration of radiation sources in the ultraviolet and vacuum ultraviolet spectral range, with traceability to calculable synchrotron radiation. Within this context, new instrumentation in the PTB laboratory at the Metrology Light Source (MLS) has been put into operation that opens up extended and improved calibration possibilities. A new facility for radiation source calibrations has been set up in the spectral range from 7 nm to 400 nm based on a combined normal incidence-grazing incidence monochromator. The facility can be used for the calibration of transfer sources in terms of spectral radiant intensity or mean spectral radiance, with traceability to the MLS primary source standard. We describe the design and performance of the experimental station and give examples of some commissioning results.

  10. Feroxyhyte nanoflakes coupled to up-converting carbon nanodots: a highly active, magnetically recoverable, Fenton-like photocatalyst in the visible-NIR range.

    Science.gov (United States)

    Ortega-Liebana, M C; Hueso, J L; Larrea, A; Sebastian, V; Santamaria, J

    2015-12-01

    We demonstrate the enhanced photocatalytic response of a novel Fenton-like heterogeneous catalyst obtained through the assembly of superparamagnetic feroxyhyte nanoflakes synthesized by continuous gas-slug microfluidics and carbon nanodots obtained by pyrolysis from a natural organic source. The novel nanohybrids enable the utilization of the visible and near-infrared ranges due to the active role of the carbon nanodots as up-converting photo-sensitizers. This novel photocatalyst is magnetically recoverable and maintains an excellent response after multiple reutilization cycles. In addition, its synthesis is based on inexpensive and abundant raw materials and its photocatalytic response is evaluated in the presence of energy efficient, affordable light-emitting diodes (LEDs), thereby providing a promising and feasible alternative to the homogeneous Fenton process. PMID:26421733

  11. GaInN/GaN quantum well laser structures emitting in the blue-green spectral range

    International Nuclear Information System (INIS)

    Presently, GaN-based laser diodes are limited to the violet-blue region of the spectrum. Our aim is to obtain laser emission in the blue-green spectral range. In order to study GaInN-based laser structures, low pressure MOVPE was used to grow such structures on a variety of substrates (freestanding GaN, GaN templates, and SiC). This allows investigations of the influence of the substrate related dislocation densities on gain, losses and carrier recombination. Our samples were investigated by optical gain spectroscopy using the variable stripe length method. In order to reach wavelengths longer than 450 nm an increase of the indium concentration to more than 25 % is needed. Such high In content requires careful optimization of the growth conditions in order to avoid damaging of the quantum wells by thermal stress. Combining the results of the gain measurement with a theoretical calculation of the gain spectra we determine the threshold power, carrier density and the carrier recombination times of the sample. On bulk GaN substrates we find threshold power levels as low as 20 kW/cm2. Up to now we obtain optical gain up to a peak wavelength of 465 nm with losses of about 30 cm-1. Our next targets are a wavelength of 480 nm as well as a further reduction of the threshold power

  12. Optimal spectral inversion of atmospheric radiometric measurements in the near-UV to near-IR range: A case study

    Science.gov (United States)

    Fussen, Didier; Vanhellemont, Filip; Bingen, Christine

    2002-01-01

    WWe present a general analysis of the error budget in the spectral inversion of atmospheric radiometric measurements. By focussing on the case of an occultation experiment, we simplify the problem through a reduced number of absorbers in a linearized formalism. However, our analysis is quite general and applies to many other situations. For a spectrometer having an infinite spectral resolution, we discuss the origin of systematic and random errors. In particular, the difficult case of aerosols is investigated and several inversion techniques are compared. We underline the importance of carefully simulating the spectral inversion as a function of the target constituent to be retrieved, and the required accuracy level.

  13. Evidence for Alteration in Chemical and Physical Properties of Water and Modulation of its Biological Functions by Sunlight Transmitted through Color Ranges of the Visible Spectrum-A Novel Study

    OpenAIRE

    M. Rajeswara Rao; Angel, Michael F.; Das, Suman K.; Koelle, Margot S.; Don Obenhuber; William L. Reno; Asit Panja; Hari H. P. Cohly

    2005-01-01

    We investigated the changes in the properties of water when exposed to sunlight for 40 days. We hypothesize and prove that solar irradiation to water entraps electromagnetic radiation as potential energy, which becomes kinetic energy in various systems. It is postulated that photochemically-induced energy transfers, associated with individual spectral emission of visible spectrum of solar light, exert diverse influences on biological systems. Bottles of distilled water, individually wrapped i...

  14. ZnO/a-Si Distributed Bragg Reflectors for Light Trapping in Thin Film Solar Cells from Visible to Infrared Range

    CERN Document Server

    Chen, Aqing; Zhu, Kaigui

    2015-01-01

    Distributed bragg reflectors (DBRs) consisting of ZnO and amorphous silicon (a-Si) were prepared by magnetron sputtering method for selective light trapping. The quarter-wavelength ZnO/a-Si DBRs with only 6 periods exhibit a peak reflectance of above 99% and have a full width at half maximum that is greater than 347 nm in the range of visible to infrared. The 6-pair reversed quarter-wavelength ZnO/a-Si DBRs also have a peak reflectance of 98%. Combination of the two ZnO/a-Si DBRs leads to a broader stopband from 686 nm to 1354 nm. Using the ZnO/a-Si DBRs as the rear reflector of a-Si thin film solar cells significantly increases the photocurrent in the spectrum range of 400 nm to 1000 nm, in comparison with that of the cells with Al reflector. The obtained results suggest that ZnO/a-Si DBRs are promising reflectors of a-Si thin-film solar cells for light trapping.

  15. Electron storage ring BESSY as a radiometric source of calculable spectral radiant power between 0.5 and 1000 nm

    International Nuclear Information System (INIS)

    The spectral radiant power of the electron storage ring BESSY was measured absolutely in the infrared and visible, and its angular distribution in the infrared, visible, and soft-x-ray ranges. The results prove BESSY to be a standard of calculable spectral radiant power, at least for wavelengths from 0.5 to 1000 nm

  16. Influence of the number of atomic levels on the spectral opacity of low temperature nickel and iron in the spectral range 50–300 eV

    Directory of Open Access Journals (Sweden)

    Busquet M.

    2013-11-01

    Full Text Available Opacity is a fundamental ingredient for the secular evolution of stars. The calculation of the stellar plasma absorption coefficients is complex due to the composition of these plasmas, generally an H /He dominated mixture with a low concentration of partially ionized heavy ions (the iron group. The international collaboration OPAC recently presented extensive comparisons of spectral opacities of iron and nickel for temperatures between 15 and 40 eV and for densities of ? 3 mg/cm3, relevant to the stellar envelope conditions [1, 2]. The role of Configuration Interaction (CI and the influence of the number of atomic levels on the opacity using the recently improved version of HULLAC atomic code [3, 4] are illustrated in this article. Comparisons with theoretical predictions already presented in [1] are discussed.

  17. Choice of a Spectral Range for Measuring Temperature Fields in a Flame and Recording High-temperature Objects Screened by the Flame Using IR Diagnostic Methods

    Science.gov (United States)

    Loboda, E. L.; Reino, V. V.; Agafontsev, M. V.

    2015-06-01

    Results of experimental investigations of radiation spectra of flame produced from combustion of different fuels are presented. Based on an analysis of the spectra, the well-founded choice of spectral ranges for IR diagnostic methods is performed to measure temperature fields in the flame and to record high-temperature objects screened by the flame.

  18. An Empirically-derived non-LTE XUV-Visible Spectral Synthesis Model of the M1 V Exoplanet Host Star GJ832

    Science.gov (United States)

    Linsky, Jeffrey; Fontenla, Juan; Witbrod, Jesse; France, Kevin

    2016-01-01

    GJ832 (HD 204961) is a nearby M1 V host star with two exoplanets: a Jovian mass planet and a super-Earth. We have obtained near-UV and far-UV spectra of GJ832 with the STIS and COS instruments on HST as part of the Cycle 19 MUSCLES pilot program (France et al. 2013). Our objective is to obtain the first accurate physical model for a representative M-dwarf host star in order to understand the stellar radiative emission at all wavelengths and to infer the radiation environment of their exoplanets that drives their atmospheric photochemistry.We have calculated a full non-LTE model for GJ 832 including the photosphere, chromosphere, transition region, and corona to fit the observed emission lines formed over a wide range of temperatures and the X-ray flux. Our one-dimensional semi-empirical model uses the Solar-Stellar Physical Modelling tools that are an offspring of the tools used by Fontenla and collaborators for computing solar models. For this model of GJ832, we calculate the populations of 52 atoms and ions and 20 molecules with 2 million spectral lines. We find excellent agreement with the observed H-alpha, CaII, MgII, CII, SiIV, CIV, and NV lines. Our model for GJ832 has a temperature minimum in the lower chromosphere much cooler than the Sun and then a steep temperature rise different from the Sun. The different thermal structure of GJ832 compared to the Sun results in the formation regions of the emission lines being different for the two stars. We also compute theradiative cooling rates as a function of height and temperature in the atmosphere of GJ832.This work is supported by grants from STScI to the University of Colorado.

  19. Design of a sun tracker for the automatic measurement of spectral irradiance and construction of an irradiance database in the 330-1100 nm range

    Energy Technology Data Exchange (ETDEWEB)

    Canada, J.; Maj, A. [Departamento de Termodinamica Aplicada, Universidad Politecnica de Valencia, Camino de Vera, s/n. 46022 Valencia (Spain); Utrillas, M.P.; Martinez-Lozano, J.A.; Pedros, R.; Gomez-Amo, J.L. [Departamento de Fisica de la Tierra y Termodinamica, Facultat de Fisica, Universitat de Valencia, 46100 Burjassot (Valencia) (Spain)

    2007-10-15

    An automatic global and direct solar spectral irradiance system has been designed based on two LICOR spectro radiometers equipped with fibre optics and remote cosine sensors. To measure direct irradiance a sun tracker based on step motors has been developed. The whole system is autonomous and works continuously. From the measurements provided by this system a spectral irradiance database in the 330-1100 nm range has been created. This database contains normal direct and global horizontal irradiances as well as diffuse irradiance on a horizontal plane, together with total atmospheric optical thickness and aerosol optical depth. (author)

  20. Validation of HITEMP-2010 for carbon dioxide and water vapour at high temperatures and atmospheric pressures in 450-7600cm-1 spectral range

    DEFF Research Database (Denmark)

    Alberti, Michael; Weber, Roman; Mancini, Marco; Fateev, Alexander; Clausen, Sønnik

    2015-01-01

    The objective of the work is validation of HITEMP-2010 at atmospheric pressures and temperatures reaching 1770K. To this end, spectral transmissivities at 1cm-1 resolution and excellent signal-to-noise-ratio have been measured for 22 CO2/H2O/N2 mixtures. In this paper we consider the 450cm-1-7600cm-1 spectral range. The LbL calculations and their comparison with the measured spectra have clearly shown that HITEMP-2010 is an excellent database (superior to previous versions) for calculating emiss...

  1. Validation of HITEMP-2010 for carbon dioxide and water vapour at high temperatures and atmospheric pressures in 450-7600cm-1 spectral range

    DEFF Research Database (Denmark)

    Alberti, Michael; Weber, Roman

    2015-01-01

    The objective of the work is validation of HITEMP-2010 at atmospheric pressures and temperatures reaching 1770K. To this end, spectral transmissivities at 1cm-1 resolution and excellent signal-to-noise-ratio have been measured for 22 CO2/H2O/N2 mixtures. In this paper we consider the 450cm-1-7600cm-1 spectral range. The LbL calculations and their comparison with the measured spectra have clearly shown that HITEMP-2010 is an excellent database (superior to previous versions) for calculating emissivities and absorption coefficients for CO2 and H2O molecules in the 500-1770K range. Several absorption lines listed in HITEMP-2010 have not been observed in the measured spectra and/or are wrongly scaled with temperature. The complete (there are no missing bands) spectra spanning the 450-7600cm-1 range are appended as Supplementary Material.

  2. Validation of HITEMP-2010 for carbon dioxide and water vapour at high temperatures and atmospheric pressures in 450-7600 cm-1 spectral range

    Science.gov (United States)

    Alberti, Michael; Weber, Roman; Mancini, Marco; Fateev, Alexander; Clausen, Sønnik

    2015-05-01

    The objective of the work is validation of HITEMP-2010 at atmospheric pressures and temperatures reaching 1770 K. To this end, spectral transmissivities at 1 cm-1 resolution and excellent signal-to-noise-ratio have been measured for 22 CO2 /H2 O /N2 mixtures. In this paper we consider the 450 cm-1-7600 cm-1 spectral range. The LbL calculations and their comparison with the measured spectra have clearly shown that HITEMP-2010 is an excellent database (superior to previous versions) for calculating emissivities and absorption coefficients for CO2 and H2 O molecules in the 500-1770 K range. Several absorption lines listed in HITEMP-2010 have not been observed in the measured spectra and/or are wrongly scaled with temperature. The complete (there are no missing bands) spectra spanning the 450 - 7600cm-1 range are appended as Supplementary Material.

  3. Use of the near vacuum UV spectral range for the analysis of W-based materials for fusion applications using LIBS

    Science.gov (United States)

    Pribula, M.; Krištof, J.; Sucho?ová, M.; Hor?á?ková, M.; Plav?an, J.; Hakola, A.; Veis, P.

    2016-02-01

    The vacuum UV (VUV)-near Infrared (NIR) laser induced breakdown spectroscopy (LIBS) technique was applied to investigate the composition of W-based samples with a protective carbon layer. The sample was analyzed under pressures from 5 to 105 Pa and atmosphere (air, He). The spectra were recorded with three spectrometers at delays from 200 ns to 10 ?s at atmospheric pressures and from 100 to 500 ns at low pressures. The electron density was determined from the measured spectra using Stark broadening and the electron temperature from the W I–W III Saha–plot in the VUV–NIR spectral range. The better precision was achieved due to usage W III spectral lines of tungsten. The achieved results are more reliable than results obtained without W III spectral lines. The calibration free LIBS method was then applied to determine the W and C contents of the analyzed sample.

  4. Spectrometry of minor planets. Spectral curve of the 3 Juno asteroid in the 0.44-0.56 ?m range

    International Nuclear Information System (INIS)

    The absorption band near 0.5 ?m has been found in the 3 Juno spectrum obtained with ? 25 A resolution. This band is caused by d-electrons transitions of Fe2+ ion in pyroxene. Taking into account the location of the asteroid on the spectral parameters diagrams for light stony meteorites it is concluded that in the surface material of the 3 Juno olivine abundance is much less than pyroxene one and the metallic phase is probably present

  5. Uranium plasma emission coefficient in the visible and near UV.

    Science.gov (United States)

    Mack, J. M., Jr.; Usher, J. L.; Schneider, R. T.; Campbell, H. D.

    1971-01-01

    Measurements of the specific emission coefficient in the near ultra-violet and visible region of a uranium arc plasma are reported. Spatial unfolding of the intensity profile is used to determine the emission coefficient in the spectral range of 2000 A to 6000 A. The uranium partial pressure is estimated to range between .001 and .01 atmosphere, and the corresponding temperature range is 5000 - 10,000 K.

  6. Composite films prepared by plasma ion-assisted deposition (IAD) for design and fabrication of antireflection coatings in visible and near-infrared spectral regions

    Science.gov (United States)

    Tsai, Rung-Ywan; Ho, Fang C.

    1994-11-01

    Ion-assisted deposition (IAD) processes configured with a well-controlled plasma source at the center base of a vacuum chamber, which accommodates two independent e-gun sources, is used to deposition TiO2MgF2 and TiO2-SiO2 composite films of selected component ratios. Films prepared by this technology are found durable, uniform, and nonabsorbing in visible and near-IR regions. Single- and multilayer antireflection coatings with refractive index from 1.38 to 2.36 at (lambda) equals 550 nm are presented. Methods of enhancement in optical performance of these coatings are studied. The advantages of AR coatings formed by TiO2-MgF2 composite films over those similar systems consisting of TiO2-SiO2 composite films in both visible and near-IR regions are also presented.

  7. Searching for the spectral features of minerals on the surface and in the dust of the comet 67P/Churyumov-Gerasimenko in NIR spectral range of VIRTIS-M data

    Science.gov (United States)

    B??cka, M. I.; Capaccioni, F.; Filacchione, G.; Raponi, A.; Ciarniello, M.; Arnold, G.; De Sanctis, M. C.; Erard, S.; Bockelée-Morvan, D. D.; Tosi, F.; Capria, M. T.; Piccioni, G.; Palomba, E.; Fonti, S.; Longobardo, A.; Drossart, P.; Schmitt, B.; Quirico, E.; Rinaldi, G.; Wawrzaszek, A.

    2015-10-01

    The main subject of the paper is constraining the composition of the surface and possibly of the dust on the comet 67P/Churyumov-Gerasimenko by means of comparison between the data from the VIRTIS instrument [1] onboard Rosetta and adopted model of the surface of asteroids [9]. As a first step we have taken into account the spectral range 2.0 - 4.0 ?m. For our calculations Mie and Hapke's models have been considered.

  8. Searching for the spectral features of minerals on the surface and in the dust of the comet 67P/Churyumov-Gerasimenko in NIR spectral range of VIRTIS-M data

    OpenAIRE

    Blecka, M.; Capaccioni, F.; Filacchione, G.; Raponi, A.; Ciarnello, M.; Arnold, Gabriele; De Sanctis, M.C.; Erard, S.; Bockelee-Morvan, D; Tosi, F.; Capria, M. T.; Piccioni, G...; Palomba, E.; Fonti, S.; Longobardo, A.

    2015-01-01

    The main subject of the paper is constraining the composition of the surface and possibly of the dust on the comet 67P/Churyumov-Gerasimenko by means of comparison between the data from the VIRTIS instrument onboard Rosetta and adopted model of the surface of asteroids [9]. As a first step we have taken into account the spectral range 2.0 - 4.0 ?m. For our calculations Mie and Hapke’s models have been considered.

  9. VNIIOFI Spectroradiometer Based on a Circular Variable Filter for the Spectral Range from 2.5 ?m up to 14 ?m

    Science.gov (United States)

    Morozova, S. P.; Morozov, P. A.; Sapritsky, V. I.; Lisiansky, B. E.; Dovgilov, N. L.

    2003-09-01

    The VNIIOFI Spectroradiometer (VSR) has been developed for the Medium Background Facility which is intended for calibrations and comparisons of low-temperature sources in the temperature range from -60 °C up to +80 °C. The VSR is designed to measure the radiance temperature of the blackbody sources in the spectral range from 2.5 ?m up to 14 ?m in a cryogenic vacuum environment (liquid nitrogen cooled shroud). The VSR is based on the Circular Variable Filter (CVF) assembly with a slit aperture and an InSb-CdHgTe two color sandwich detector with an integral Stirling cooler. The Circular Variable Filter covers the 2.5 ?m to 14.1 ?m region in three segments. The width of the slit equal to 1.2 mm provides a spectral resolution from 80 nm to 360 nm for the spectral range from 2.5 ?m to 14.1 ?m accordingly. The Circular Variable Filter assembly is rotated by a stepper motor. The Cassegrain telescope is used as a foreoptic unit. Radiation passes through the CVF and is focused on the detector with help of the ellipsoidal mirror. Radiation from a low-temperature (77 K) blackbody is used as a reference level of radiation. The instrument has a field of view of 8.9 mrad with a distance to the object being equal to 2250 mm. The spectral and temporal characterizations of the spectroradiometer are reported. The facility for CVF calibration is described. Temperature resolutions for the calibrated sources are given for different temperatures and for different wavelengths. A brief description of the design, operation principles and specifications of the main parts of the spectroradiometer such as the Cassegrain telescope, CVF and detector assembly are presented. The measurement uncertainties of radiance temperature associated with spectral bandwidth are discussed.

  10. Final report on the key comparison CCPR-K2.c-2003: Spectral responsivity in the range of 200 nm to 400 nm

    Science.gov (United States)

    Werner, Lutz

    2014-01-01

    The CCPR K2.c key comparison of spectral power responsivity of detectors in the ultraviolet spectral range from 200 nm to 400 nm was carried out in the framework of the CIPM Mutual Recognition Arrangement by 14 participating national metrology institutes. The key comparison was piloted by the Physikalisch-Technische Bundesanstalt (PTB). The comparison was carried out through the calibration of sets of transfer detectors. Three types of transfer detectors based on two types of photodiodes have been used to handle probable changes of the spectral responsivity of the detectors in the ultraviolet spectral range. The results of the key comparison in the wavelength range from 200 nm to 240 nm are based on single-element windowless PtSi/n-Si Schottky photodiodes while in the range from 250 nm to 400 nm the results are based on single-element photodiode detectors and three-element reflection trap detectors, both made up of windowless Si pn junction photodiodes. The comparison was organized in a star pattern and conducted in three groups of participants. The report describes the measurements made by the pilot laboratory, summarizes the reports submitted by the participants and describes the data analysis carried out to determine the key comparison reference values and degrees of equivalence. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCPR, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  11. Relative spectral response measurement of spectrometers using undulator radiation

    International Nuclear Information System (INIS)

    Undulator radiation with known spectral characteristics is recognized as an excellent light source that can be used to measure the spectral response of a variety of spectral measurement devices in a wide range from infrared to x-ray. This technique has been developed at Duke Free-Electron Laser (FEL) Laboratory to successfully measure the spectral response of several spectrometers in the near-infrared, visible, and ultraviolet regions. In this paper, we present both simulation and experimental results of the spectral response measurement, with a focus on high-accuracy spectral response reconstruction. Using simulation studies, we have tested and confirmed the validity of the spectral response measurement method while taking into account major sources of errors. Especially, it shows that the spectral response reconstruction technique developed in this work is rather robust against the spectral broadening of undulator radiation. The usefulness of this spectral response measurement method is also confirmed with the experimental study on a spectrometer in the visible region. Overall, we have achieved good results with the measured spectral response, with an RMS uncertainty of about 2.7% in the range from 414 to 591 nm. Using multiple measurements, the reproducibility of this method has also been tested with a relative difference of about 2.3% (RMS in the range from 415 to 590 nm). For high-accuracy measurements of a broad radiation spectrum, the knowledge of the spectral response of the spectrometer is critical. In this paper, we will show that the details of the measured undulator radiation spectra can be properly restored by correcting the raw spectrum using the measured spectral response. The method of spectral response measurement using undulator radiation is also useful to calibrate spectral devices in extreme spectral ranges such as VUV and x-ray

  12. All-fiber femtosecond Cherenkov laser at visible wavelengths

    DEFF Research Database (Denmark)

    Liu, Xiaomin; Lægsgaard, Jesper; Møller, Uffe Visbech; Tu, Haohua; Boppart, Stephen A.; Turchinovich, Dmitry

    2013-01-01

    to be as low as -103 dBc/Hz. This is 2 orders of magnitudes lower noise as compared to spectrally-sliced supercontinuum, which is the current standard of ultrafast fiber-optic generation at visible wavelength. The layout of the laser system is shown in Fig. 1(a). The system consists of two parts: an......Fiber-optic Cherenkov radiation (CR), also known as dispersive wave generation or non-solitonic radiation, is produced in small-core photonic crystal fibers (PCF) when a soliton perturbed by fiber higher-order dispersion co-propagates with a dispersive wave fulfilling a certain phase...... electrically tunable femtosecond CR output in the visible (VIS) spectral range of 580-630 nm, with the 3 dB spectral bandwidth not exceeding 36 nm, with average power in the milliwatt range. Relative intensity noise (RIN) of this laser, affecting the sensitivity of bio-imaging and microscopy systems, is found...

  13. VERUCLAY – a new type of photo-adsorbent active in the visible light range: modification of montmorillonite surface with organic surfactant

    Science.gov (United States)

    Montmorillonite K10 was treated with VeruSOL-3, a biodegradable and food-grade surfactant mixture of coconut oil, castor oil and citrus extracts, to manufacture a benign catalytic adsorbent that is active in the visible light. Veruclay was characterized by SEM, XRD, TGA, UVDRS, a...

  14. Experimental and theoretical investigation of silver-coated ZnO nanorod arrays as antennas for the visible and near-IR spectral range

    Science.gov (United States)

    Kaidashev, E. M.; Lyanguzov, N. V.; Lerer, A. M.; Raspopova, E. A.

    2014-04-01

    A new design of optical antennas consisting of zinc oxide (ZnO) nanorods covered by a thin metal film is proposed. Arrays of highly oriented ZnO nanorods perpendicular to a substrate and covered by a thin silver film have been obtained using methods of carbothermal synthesis and magnetron sputtering. The problems of electromagnetic wave diffraction on a single metal/dielectric nanovibrator (situated at the interface of dielectrics) and on a two-dimensional periodic array of these nanovibrators have been solved. The results of calculations of the electrodynamic characteristics of optical antennas with various lengths have been compared to experimental data.

  15. AlGaInP quantum dots for optoelectronic applications in the visible spectral range; AlGaInP-Quantenpunkte fuer optoelektronische Anwendungen im sichtbaren Spektralbereich

    Energy Technology Data Exchange (ETDEWEB)

    Gerhard, Sven

    2013-01-10

    The scope of this work is the fabrication and characterization of AlGaInP quantum dots on GaP an GaAs substrates. Based on such quantum dots, semiconductor lasers have been realized, emitting between 660 nm and 730 nm at room temperature. The examination of broad-area lasers processed on these structures suggests that active layers of larger quantum dots with higher aluminium contents lead to lasers with better performance at similar emission wavelength. Additionally, quantum dots grown on GaP substrates have been characterized, that were embedded in AlGaP barriers. Since these barriers exhibit an indirect bandgap, a non-trivial band alignment within these structures is expected. In this work, numerical 3D-simulations are employed to calculate the band alignment including strain and internal fields. Also, ground state wavefunctions of charge carriers have been determined. A thorough comparison between theory and experiment connects the measured emission wavelength and luminescence intensities with calculated transition energies and wavefunction overlaps.

  16. UV—visible spectral characterization and density functional theory simulation analysis on laser-induced crystallization of amorphous silicon thin films

    International Nuclear Information System (INIS)

    The effect of laser energy density on the crystallization of hydrogenated intrinsic amorphous silicon (a-Si:H) thin films was studied both theoretically and experimentally. The thin films were irritated by a frequency-doubled (? = 532 nm) Nd:YAG pulsed nanosecond laser. An effective density functional theory model was built to reveal the variation of bandgap energy influenced by thermal stress after laser irradiation. Experimental results establish correlation between the thermal stress and the shift of transverse optical peak in Raman spectroscopy and suggest that the relatively greater shift of the transverse optical (TO) peak can produce higher stress. The highest crystalline fraction (84.5%) is obtained in the optimized laser energy density (1000 mJ/cm2) with a considerable stress release. The absorption edge energy measured by the UV-visible spectra is in fairly good agreement with the bandgap energy in the density functional theory (DFT) simulation

  17. Third-harmonic generation in silicon and photonic crystals of macroporous silicon in the spectral intermediate-IR range; Erzeugung der Dritten Harmonischen in Silizium und Photonischen Kristallen aus makroporoesem Silizium im spektralen mittleren IR-Bereich

    Energy Technology Data Exchange (ETDEWEB)

    Mitzschke, Kerstin

    2007-11-01

    Nonlinear optical spectroscopy is a powerful method to study surface or bulk properties of condensed matter. In centrosymmetric materials like silicon even order nonlinear optical processes are forbidden. Besides self-focussing or self phase modulation third-harmonic-generation (THG) is the simplest process that can be studied. This work demonstrates that THG is a adapted non-contact and non-invasive optical method to get information about bulk structures of silicon and Photonic crystals (PC), consisting of silicon. Until now most studies are done in the visible spectral range being limited by the linear absorption losses. So the extension of THG to the IR spectral range is extremely useful. This will allow the investigation of Photonic Crystals, where frequencies near a photonic bandgap are of special interest. 2D- photonic structures under investigation were fabricated via photoelectrochemical etching of the Si (100) wafer (thickness 500 {mu}m) receiving square and hexagonal arranged pores. The typical periodicity of the structures used is 2 {mu}m and the length of the pores reached to 400 {mu}m. Because of stability the photonic structures were superimposed on silicon substrate. The experimental set-up used for the THG experiments generates tuneable picosecond IR pulses (tuning range 1500-4000 cm{sup -1}). The IR-pulse hit the sample either perpendicular to the sample surface or under an angle {theta}. The sample can be rotated (f) around the surface normal. The generated third harmonic is analysed by a polarizer, spectrally filtered by a polychromator and registered by a CCD camera. The setup can be used either in transmission or in reflection mode. Optical transmission and reflection spectra of the Si bulk correspond well with the theoretical description, a 4-fold and a 8-fold dependencies of the azimuth angle resulting in the structure of the x{sup (3)}-tensor of (100)-Si. The situation changes dramatically if the PC with hexagonal structure is investigated. In reflection mode a six fold symmetry is observed. This can only be explained by the symmetry of the Photonic Crystal. Changing the transmission mode the result depends on the mount of the PC - fundamental entering from the structure side or fundamental entering from the bulk side. Common to both results are there six maxima. To explain the difference between the transmission and reflection results one has to recognise, that the effective interaction length is limited: so in the reflection geometry of generated TH is from the structured region, whereas in the transmission cases a combination of the structure and the bulk has to be taken into account. This work gives a first theoretical description of this effects. (orig.)

  18. Transmittance and optical constants of Lu films in the 3-1800 eV spectral range

    OpenAIRE

    García-Cortés, S.; Rodríguez-de Marcos, L.; Larruquert, Juan Ignacio; Aznárez, José Antonio; Méndez, José Antonio; L. Poletto; Frassetto, F.; Malvezzi, A.M.; Giglia, A.; Mahne, N.; Nannarone, S.

    2010-01-01

    The optical constants n and k of lutetium (Lu) films were obtained in the 3-1800 eV range from transmittance measurements performed at room temperature. These are the first experimental optical constant data of Lu in the whole range. Thin films of Lu with various thicknesses were deposited by evaporation in ultrahigh vacuum conditions and their transmittance was measured in situ. Lu films were deposited onto grids coated with a thin, C support film. Transmittance measurements were used to obt...

  19. Spectral and scattering theory for a Schrödinger operator with a class of momentum-dependent long-range potentials

    Science.gov (United States)

    Muthuramalingam, Pl.

    1982-07-01

    Let H = - tfrac{1}{2}\\vartriangle + sumnolimits_{j = 1}^n {W_j (Q)P_j + W_0 (Q)} be the selfadjoint operator for the static electromagnetic field where W j for 0, 1, 2, ..., n is a sum of (i) a short-range potential and (ii) a smooth long-range potential decreasing at ? as |x|-? with ? in (0, 1]. Then for ?>1/2, asymptotic completeness holds for the scattering system ( H, H 0).

  20. A cylindrical guarded capacitor for spectral permittivity measurements of hard rock samples in the MHz-range

    Science.gov (United States)

    Schmidt, V.; Wilting, W.; Gruse, M.; Wagner, N.

    2015-10-01

    A shielded and guarded capacitor for non-destructive measurement of the complex permittivity of cylindrical rock samples has been developed. In combination with a vector network analyzer, the measurement system allows for rapid determination of spectral permittivity. The geometrical construction of the capacitor allows for scanning the properties of cylindrical samples, such as drill cores, and determination of anisotropy. The complex permittivity is calculated from the scattering parameters, which are determined using a network analyzer. The calculation is based on a ?-network model for the cell and takes stray capacitances and capacitances related to the guard electrode into account. Using this method, good measurement accuracy is achieved between 10?MHz and 200?MHz. The validity of this method was proven by finite element modeling of the field distributions in the cell based on 3D electromagnetic simulation. The influence of typical geometrical imperfections of drill cores, such as varying diameter, finite length and heterogeneities has been studied and quantified by extensive measurements of test samples. These tests confirmed that due to the short shielded electrode, spatial variations in permittivity can be resolved on a sub-centimeter scale.

  1. Reflectance measurements of leaves for detecting visible and non-visible ozon damage to crops

    International Nuclear Information System (INIS)

    Spring wheat (Triticum aestivum cv. Turbo), white clover (Trifolium repens cv. Karina) and maize (Zea mays cv. Bonny) plants were exposed for 20–30 days in open top chambers to charcoal-filtered air (CF, control) and CF air supplied with O3 for 8–12 h/per day in the concentration range of 180–240 ?g O3/m3 (8–12 h/day treatment mean). At the end of the O3 treatment spectral reflectance measurements were made on single leaves of all 3 species and on canopies of wheat and clover using a CCD (Charged Coupled Device) camera and wavelength filters with 11 wavelength bands ranging from 450 nm to 950 nm. Different vegetation indices such as the normalized difference vegetation index (NDVI) and the ?main inflection point? (MIP) were calculated. Based on these results it was shown that visible O3 damages were correlated to the spectral reflectance changes: Both leaves and canopies showed an increased reflectance of visible light after ozone treatment. While clover and maize leaves as well as clover and wheat canopies showed a decreased near infrared (NIR) reflectance, the NIR reflectance of wheat leaves did not change, even if the leaves had visible symptoms. A decreased infrared reflectance was detectable for all clover leaves after O3 treatment although for part of the leaves no visible foliar damage symptoms could be observed

  2. Spectral and scattering theory for a Schroedinger operator with a class of momentum-dependent long-range potentials

    International Nuclear Information System (INIS)

    Let H = -1/2 ? + ?sub(j)sup(n) = 1 Wsub(j)(Q)Psub(j) + W0(Q) be the selfadjoint operator for the static electromagnetic field where Wsub(j) for 0, 1, 2, ..., n is a sum of (I) a short-range potential and (II) a smooth long-range potential decreasing at infinity as vertical stroke x vertical stroke sup(-delta) with delta in (0, 1). Then for delta > 1/2, asymptotic completeness holds for the scattering system (H, H0). (orig.)

  3. Spectral and scattering theory for a Schroedinger operator with a class of momentum-dependent long-range potentials

    Energy Technology Data Exchange (ETDEWEB)

    Muthuramalingam, P. (Indian Statistical Inst., New Delhi)

    1982-07-01

    Let H = -1/2 ..delta.. + ..sigma..sub(j)sup(n) = 1 Wsub(j)(Q)Psub(j) + W/sub 0/(Q) be the selfadjoint operator for the static electromagnetic field where Wsub(j) for 0, 1, 2, ..., n is a sum of (I) a short-range potential and (II) a smooth long-range potential decreasing at infinity as vertical stroke x vertical stroke sup(-delta) with delta in (0, 1). Then for delta > 1/2, asymptotic completeness holds for the scattering system (H, H/sub 0/).

  4. Polarizers for a spectral range centered at 121.6 nm operating by reflectance or by transmittance

    Science.gov (United States)

    Larruquert, Juan I.; Malvezzi, A. Marco; Giglia, Angelo; Aznárez, José A.; Rodríguez-de Marcos, Luis; Méndez, José A.; Miotti, Paolo; Frassetto, Fabio; Massone, Giuseppe; Capobianco, Gerardo; Fineschi, Silvano; Nannarone, Stefano

    2015-05-01

    Polarimetry is a powerful tool to interpret how the coronal plasma is involved in the energy transfer processes from the Sun's inner parts to the outer space. Space polarimetry in the far ultraviolet (FUV) provides essential information of processes governed by the Doppler and Hanle resonant electron scattering effects. Among the key FUV spectral lines to observe these processes, H I Lyman α (121.6 nm) is the most intense. Some developing or proposed solar physics missions, such as CLASP, SolmeX, and COMPASS, plan to perform polarimetry at 121.6 nm. Classical solutions, such as a parallel plate of a transparent material, either MgF2 or LiF, result in a modest efficiency of the passing polarization component. The development of more efficient linear polarizers at this wavelength will benefit future space instruments. A research has been conducted to develop polarizers based on (Al/MgF2)n multilayer coatings in a band containing 121.6 nm, to obtain a significant efficiency increase over plates. Coatings operating by reflectance resulted in a high efficiency after approximately one year of storage under nitrogen. In parallel, coating polarizers operating by transmittance have been prepared for the first time. Transmissive polarizers have the advantage that they involve no deviation of the beam. As a further benefit, the developed transmittance polarizers additionally incorporate filtering properties to help reject wavelengths both shortwards and longwards of a band containing 121.6 nm. Hence a polarizer combined with a filter is obtained with a single device. The combined polarizer-filter could enable a higher performance polarimeter for solar physics if the use of a separate filter to isolate Lyman α turns unnecessary.

  5. Construction of TSL lector equipment with spectral resolution for the determination of thermally stimulated luminescence (TSL) properties of NaCl: Tl+ induced by UV-visible radiation

    International Nuclear Information System (INIS)

    A revision of physical models of thermally stimulated luminescence (TSL) in crystals induced by both ionizing and non-ionizing radiation is presented. Particular emphasis is given to the connection of TSL with other thermally stimulated processes and physico-chemical phenomena because basic information on physical mechanics for TSL can be obtained through them. Glow curves of TSL induced by UV-visible radiation in NaCl: Tl+ were measured. Additionally, the following spectrums were obtained for the same samples: optical absorption, excitation, fluorescent emission, and TSL emission. An optical absorption peak was correlated with the Thallium ion concentration. With respect to the TSL emission spectrums, some peaks associated to Thallium dimmers were at 298 and at 480 nm; others which were attributed to NaCl intrinsic properties were at 365, 430, 450 and 525 nm. Also TSL glow curves were studied as a function of the Thallium ion concentration (0.8 ppm to 14.8 ppm). They were de convoluted so as to calculate the activation energy, the frequency factor and the kinetic order for each separate TSL peak. Anomalous values were observed for some frequency factors. A method and TSL lector equipment to obtain TSL emission spectra were developed. (Author)

  6. Ultrawideband coherent noise lidar range-Doppler imaging and signal processing by use of spatial-spectral holography in inhomogeneously broadened absorbers.

    Science.gov (United States)

    Li, Youzhi; Hoskins, Alan; Schlottau, Friso; Wagner, Kelvin H; Embry, Carl; Babbitt, William Randall

    2006-09-01

    We introduce a new approach to coherent lidar range-Doppler sensing by utilizing random-noise illuminating waveforms and a quantum-optical, parallel sensor based on spatial-spectral holography (SSH) in a cryogenically cooled inhomogeneously broadened absorber (IBA) crystal. Interference between a reference signal and the lidar return in the spectrally selective absorption band of the IBA is used to sense the lidar returns and perform the front-end range-correlation signal processing. Modulating the reference by an array of Doppler compensating frequency shifts enables multichannel Doppler filtering. This SSH sensor performs much of the postdetection signal processing, increases the lidar system sensitivity through range-correlation gain before detection, and is capable of not only Doppler processing but also parallel multibeam reception using the high-spatial resolution of the IBA crystals. This approach permits the use of ultrawideband, high-power, random-noise, cw lasers as ranging waveforms in lidar systems instead of highly stabilized, injection-seeded, and amplified pulsed or modulated laser sources as required by most conventional coherent lidar systems. The capabilities of the IBA media for many tens of gigahertz bandwidth and resolution in the 30-300 kHz regime, while using either a pseudo-noise-coded waveform or just a high-power, noisy laser with a broad linewidth (e.g., a truly random noise lidar) may enable a new generation of improved lidar sensors and processors. Preliminary experimental demonstrations of lidar ranging and simulation on range-Doppler processing are presented. PMID:16912777

  7. Study of wave chaos in a randomly-inhomogeneous oceanic acoustic waveguide: spectral analysis of the finite-range evolution operator

    CERN Document Server

    Makarov, D V; Uleysky, M Yu; Petrov, P S

    2012-01-01

    The proplem of sound propagation in an oceanic waveguide is considered. Scattering on random inhomogeneity of the waveguide leads to wave chaos. Chaos reveals itself in spectral properties of the finite-range evolution operator (FREO). FREO describes transformation of a wavefield in course of propagation along a finite segment of a waveguide. We study transition to chaos by tracking variations in spectral statistics with increasing length of the segment. Analysis of the FREO is accompanied with ray calculations using the one-step Poincar\\'e map which is the classical counterpart of the FREO. Underwater sound channel in the Sea of Japan is taken for an example. Several methods of spectral analysis are utilized. In particular, we approximate level spacing statistics by means of the Berry-Robnik and Brody distributions, explore the spectrum using the procedure elaborated by A. Relano with coworkers (Relano et al, Phys. Rev. Lett., 2002; Relano, Phys. Rev. Lett., 2008), and analyze modal expansions of the eigenfu...

  8. Arecibo Spectral Line Scan of the Hot Molecular Core in W51: Results from the C-Band High Frequency Range

    Science.gov (United States)

    Araya, Esteban; Arce, H. G.; Minchin, R. F.; Ghosh, T.; Salter, C. J.; Lebron Santos, M. E.; De Vries, C. H.

    2013-06-01

    In 2010 we began an ambitious project with the 305m Arecibo Telescope: a spectral line scan of the W51 hot molecular core covering all available frequency bands, from 1 to 10 GHz. The observations were taken in the summers of 2010, 2011, and 2012. All frequency bands were observed with the Mock spectrometer, which allowed simultaneous observations of 14 adjacent spectral windows, 8192 channels each, ~0.3 km/s channel width. In this update report we concentrate on results from the C-Band High frequency range, from 6.0 to 8.2 GHz. We achieved a typical rms of ~15 mJy. We report detection of more than 70 spectral lines; among the most prominent are radio recombination lines, including alpha, beta, gamma, delta and epsilon hydrogen lines; emission and absorption lines of excited hydroxyl transitions at 6.030, 6.035 and 6.049 GHz; and methanol masers and absorption of the 6.67 GHz transition.

  9. Transmittance and optical constants of Ho films in the 3-1340 eV spectral range

    OpenAIRE

    Fernández Perea, Mónica; Larruquert, Juan Ignacio; Aznárez, José Antonio; Méndez, José Antonio; L. Poletto; Frassetto, F.; Malvezzi, A.M.; Bajoni, D.; Giglia, A.; Mahne, N.; Nannarone, S.

    2011-01-01

    The optical constants n and k of holmium (Ho) films were obtained in the 3-1340-eV range from transmittance measurements performed at room temperature. Thin films of Ho with various thicknesses were deposited by evaporation in ultra high vacuum conditions and their transmittance was measured in situ. Ho films were deposited onto thin C-film substrates supported on high transmittance grids. Transmittance measurements were used to obtain the extinction coefficient k of Ho films. The refractive ...

  10. Parametric modeling of the dielectric function and identification of the critical point of a CdMgTe alloy in the vacuum ultraviolet spectral range

    International Nuclear Information System (INIS)

    We report the parameters necessary to construct the dielectric functions of Cd1-xMgxTe ternary alloys at room temperature for arbitrary compositions from x = 0 to x = 0.5. The experimental spectra were measured by using vacuum ultraviolet spectroscopic ellipsometry in the spectral range from 0.7 to 9.0 eV. By performing a band structure calculation with the linear augmented Slatertype orbital method, we newly identify the four higher band gaps as E2 + Δ2, E2(Δ), E2(Σ), and E'1 transitions.

  11. Monolithic integration of InGaN segments emitting in the blue, green, and red spectral range in single ordered nanocolumns

    International Nuclear Information System (INIS)

    This work reports on the selective area growth by plasma-assisted molecular beam epitaxy and characterization of InGaN/GaN nanocolumnar heterostructures. The optimization of the In/Ga and total III/V ratios, as well as the growth temperature, provides control on the emission wavelength, either in the blue, green, or red spectral range. An adequate structure tailoring and monolithic integration in a single nanocolumnar heterostructure of three InGaN portions emitting in the red-green-blue colors lead to white light emission.

  12. Monolithic integration of InGaN segments emitting in the blue, green, and red spectral range in single ordered nanocolumns

    Energy Technology Data Exchange (ETDEWEB)

    Albert, S.; Bengoechea-Encabo, A.; Sanchez-Garcia, M. A.; Calleja, E. [ISOM and Dept. Ingenieria Electronica, ETSI Telecomunicacion, Universidad Politecnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain); Kong, X.; Trampert, A. [Paul-Drude-Institut fuer Festkoeperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany)

    2013-05-06

    This work reports on the selective area growth by plasma-assisted molecular beam epitaxy and characterization of InGaN/GaN nanocolumnar heterostructures. The optimization of the In/Ga and total III/V ratios, as well as the growth temperature, provides control on the emission wavelength, either in the blue, green, or red spectral range. An adequate structure tailoring and monolithic integration in a single nanocolumnar heterostructure of three InGaN portions emitting in the red-green-blue colors lead to white light emission.

  13. Adjustment of a goniometer for X-rays optics calibration in the spectral range 1.5-20 KeV

    International Nuclear Information System (INIS)

    The aim of this memoir is the adjustment of a (?, 2?) goniometer coupled to X-rays source to calibrate mirrors (single layers like C, Ni, Au, etc... and multilayers like C/W, Si/W, etc...) in the spectral range 1.5 - 20 keV. For each kind of tested optics the adjustment of the goniometer include the procedure alignment of the different components (X-ray source, collimation slits, optics, detectors) and the first reflectivity measurements. Those measurements are compared those realized at LURE, using synchrotron radiation provided by SUPER ACO storage ring, and to a theoretical simulation

  14. Annual Variation of Local Photon Emissions’ Spectral Power within the mHz Range Overlaps with Seismic-Atmospheric Acoustic Oscillations

    OpenAIRE

    Persinger, Michael A.

    2012-01-01

    Spheroidal modes of seismic and acoustic oscillations in the atmosphere occur within the 2 to 7 mHz range with peak-to-peak variations in the order of 10–12 to 10–11 m·s–2. Previous research indicated the amplitudes for 230 s and 270 s periods peak during the summer months. In the present study the amplitudes of a reliably apparent 3 mHz increment from spectral analyses of minute-to-minute measurements of background photon e...

  15. Transmittance and optical constants of erbium films in the 3:25 - 1580 eV spectral range

    OpenAIRE

    Larruquert, Juan Ignacio; Frassetto, F.; García-Cortés, S.; Vidal-Dasilva, M.; Fernández Perea, Mónica; Aznárez, José Antonio; Méndez, José Antonio; Nannarone, S.

    2011-01-01

    The optical constants of erbium (Er) films were obtained in the 3:25-1580 eV range from transmittance measurements performed at room temperature. Thin films of Er were deposited by evaporation in ultra high vacuum conditions and their transmittance was measured in situ. Substrates consisted of a thin C film supported on a grid. Transmittance measurements were used to obtain the extinction coefficient k of the Er films. The refractive index n of Er was calculated using the Kramers-Krönig analy...

  16. Evidence for Alteration in Chemical and Physical Properties of Water and Modulation of its Biological Functions by Sunlight Transmitted through Color Ranges of the Visible Spectrum-A Novel Study

    Directory of Open Access Journals (Sweden)

    M. Rajeswara Rao

    2005-08-01

    Full Text Available We investigated the changes in the properties of water when exposed to sunlight for 40 days. We hypothesize and prove that solar irradiation to water entraps electromagnetic radiation as potential energy, which becomes kinetic energy in various systems. It is postulated that photochemically-induced energy transfers, associated with individual spectral emission of visible spectrum of solar light, exert diverse influences on biological systems. Bottles of distilled water, individually wrapped in spectral-colored cellophane were exposed to sunlight and compared to an unwrapped bottle to determine chemical and physical changes as well as modifications of biological properties. Each bottle of water was named according to the color of cellophane paper with letter E (stands for exposed as a prefix with (E-violet, E-indigo, E-blue, E-green, E-yellow, E-orange, and Ered. E-control (without wrap was exposed to polychromatic sunlight. This study addresses two main issues viz., the chemical and physical changes in E-water and its effect on biological activities. Chemical and physical composition analysis using inductively coupled plasma atomic emission spectrometry; physical conductance by a Wheatstone Bridge type conductivity meter; osmolarity by a vapor pressure osmometer; and, salt solubility profile of 10% sodium bicarbonate were determined. Furthermore, testing the effect of E-waters on human lymphocyte proliferation, mosquito larvae hatching and seed germination determined the functional role of solar radiation through specific spectrum/s of visible light on various biological processes. We found that water exposed to visible spectral emissions of sunlight had an altered elemental composition, electrical conductance, osmolarity and salt-solubility, as well as differences in bio-modulatory effects. A gradual increase in leaching of Boron from Eviolet to E-red was noted. E-indigo showed maximal increase in electrical conductance and maximal salt solubility of sodium bicarbonate. E-blue inhibited phyto-hemagglutinin-induced immune cell proliferation and mosquito larvae hatching. E-orange stimulated root elongation in seed germination. We conclude that 40-day exposure of water to specific solar spectrum changes chemical and physical properties and influences on biological activity.

  17. Sensitivity Gains, Linearity, and Spectral Reproducibility in Nonuniformly Sampled Multidimensional MAS NMR Spectra of High Dynamic Range.

    Energy Technology Data Exchange (ETDEWEB)

    Suiter, Christopher L.; Paramasivam, Sivakumar; Hou, Guangjin; Sun, Shangjin; Rice, David M.; Hoch, Jeffrey C.; Rovnyak, David S.; Polenova, Tatyana E.

    2014-04-22

    Recently, we have demonstrated that considerable inherent sensitivity gains are attained in MAS NMR spectra acquired by nonuniform sampling (NUS) and introduced maximum entropy interpolation (MINT) processing that assures the linearity of transformation between the time and frequency domains. In this report, we examine the utility of the NUS/MINT approach in multidimensional datasets possessing high dynamic range, such as homonuclear 13C–13C correlation spectra. We demonstrate on model compounds and on 1–73-(U-13C,15N)/74–108-(U-15N) E. coli thioredoxin reassembly, that with appropriately constructed 50 % NUS schedules inherent sensitivity gains of 1.7–2.1-fold are readily reached in such datasets. We show that both linearity and line width are retained under these experimental conditions throughout the entire dynamic range of the signals. Furthermore, we demonstrate that the reproducibility of the peak intensities is excellent in the NUS/MINT approach when experiments are repeated multiple times and identical experimental and processing conditions are employed. Finally, we discuss the principles for design and implementation of random exponentially biased NUS sampling schedules for homonuclear 13C–13C MAS correlation experiments that yield high quality artifact-free datasets.

  18. Transmittance and optical constants of erbium films in the 3.25-1580 eV spectral range.

    Science.gov (United States)

    Larruquert, Juan I; Frassetto, Fabio; García-Cortés, Sergio; Vidal-Dasilva, Manuela; Fernández-Perea, Mónica; Aznárez, José A; Méndez, José A; Poletto, Luca; Malvezzi, A Marco; Giglia, Angelo; Nannarone, Stefano

    2011-05-20

    The optical constants of erbium (Er) films were obtained in the 3.25-1580 eV range from transmittance measurements performed at room temperature. Thin films of Er were deposited by evaporation in ultra high vacuum conditions and their transmittance was measured in situ. Substrates consisted of a thin C film supported on a grid. Transmittance measurements were used to obtain the extinction coefficient k of the Er films. The refractive index n of Er was calculated using the Kramers-Krönig analysis. k data were extrapolated both on the high- and low-energy parts of the spectrum by using experimental data and calculated k values available in the literature. Er, similar to other lanthanides, has a low-absorption band below the O(2,3) edge onset; the smallest absorption was measured at ~22.5 eV. Therefore, Er is a promising material for filters and multilayer coatings in the energy range below the O(2,3) edge, in which materials typically have an absorption stronger than at other energies. Good consistency of the data resulted from the application of f and inertial sum rules. PMID:21614114

  19. Modification of modulated plasma plumes for the quasi-phase-matching of high-order harmonics in different spectral ranges

    International Nuclear Information System (INIS)

    We demonstrate the technique allowing the fine tuning of the distance between the laser-produced plasma plumes on the surfaces of different materials, as well as the variation of the sizes of these plumes. The modification of plasma formations is based on the tilting of the multi-slit mask placed between the heating laser beam and target surface, as well as the positioning of this mask in the telescope placed on the path of heating radiation. The modulated plasma plumes with the sizes of single plume ranging between 0.1 and 1?mm were produced on the manganese and silver targets. Modification of the geometrical parameters of plasma plumes proved to be useful for the fine tuning of the quasi-phase-matched high-order harmonics generated in such structures during propagation of the ultrashort laser pulses. We show the enhancement of some groups of harmonics along the plateau range and the tuning of maximally enhanced harmonic by variable modulation of the plasma

  20. High resolution spectral survey of symbiotic stars in the near-IR over the GAIA wavelength range

    CERN Document Server

    Marrese, P M; Munari, U; Marrese, Paola M.; Sordo, Rosanna; Munari, Ulisse

    2002-01-01

    High resolution (R~20,000), high signal-to-noise (S/N~100) spectra were collected for ~40 symbiotic stars with the Asiago echelle spectrograph over the same 8480-8740 Ang wavelength range covered by the ESA Cornerstone mission GAIA, centered on the near-IR CaII triplet and the head of the Paschen series. A large number (~140) of cool MKK giant and supergiant templates were observed with the same instrumentation to serve as a reference and classification grid. The spectra offer bright prospects in classifying and addressing the nature of the cool component of symbiotic stars (deriving T(eff), log g, [Fe/H], [alpha/Fe], V(rot)sin i both via MDM-like methods and syntetic atmosphere modeling) and mapping the physical condition and kinematics of the gas regions responsible for the emission lines.

  1. A Novel Smart Pan/Tilt/Zoom Visible/Infrared Sensor for UAV On-Board Video Surveillance of Launch Range Project

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA has a pressing need for increasing the efficiency of launch range surveillance during mission launch operations. Difficulty in verifying a cleared range causes...

  2. Simulation of laser propagation through a three-layer human skin model in the spectral range from 1000 to 1900 nm.

    Science.gov (United States)

    Nasouri, Babak; Murphy, Thomas E; Berberoglu, Halil

    2014-01-01

    For understanding the mechanisms of low-level laser/light therapy (LLLT), accurate knowledge of light interaction with tissue is necessary. We present a three-dimensional, multilayer reduced-variance Monte Carlo simulation tool for studying light penetration and absorption in human skin. Local profiles of light penetration and volumetric absorption were calculated for uniform as well as Gaussian profile beams with different spreads over the spectral range from 1000 to 1900 nm. The results showed that lasers within this wavelength range could be used to effectively and safely deliver energy to specific skin layers as well as achieve large penetration depths for treating deep tissues, without causing skin damage. In addition, by changing the beam profile from uniform to Gaussian, the local volumetric dosage could increase as much as three times for otherwise similar lasers. We expect that this tool along with the results presented will aid researchers in selecting wavelength and laser power in LLLT. PMID:25003752

  3. Large-Scale Structure of the Molecular Gas in Taurus Revealed by High Linear Dynamic Range Spectral Line Mapping

    CERN Document Server

    Goldsmith, Paul F; Narayanan, Gopal; Snell, Ronald; Li, Di; Brunt, Chris

    2008-01-01

    We report the results of a 100 square degree survey of the Taurus Molecular Cloud region in the J = 1-0 transition of 12CO and 13CO. The image of the cloud in each velocity channel includes ~ 3 million Nyquist sampled pixels on a 20" grid. The high sensitivity and large linear dynamic range of the maps in both isotopologues reveal a very complex, highly structured cloud morphology. There are large scale correlated structures evident in 13CO emission having very fine dimensions, including filaments, cavities, and rings. The 12CO emission shows a quite different structure, with particularly complex interfaces between regions of greater and smaller column density defining the boundaries of the largest-scale cloud structures. The axes of the striations seen in the 12CO emission from relatively diffuse gas are aligned with the direction of the magnetic field. Using a column density-dependent model for the CO fractional abundance, we derive the mass of the region mapped to be 24,000 solar masses, a factor of three ...

  4. Simulation of a surface plasmon resonance-based fiber-optic sensor for gas sensing in visible range using films of nanocomposites

    International Nuclear Information System (INIS)

    A surface plasmon resonance-based fiber-optic sensor coated with nanocomposite film for sensing small concentrations of gases in the visible region of the electromagnetic spectrum has been analyzed. The nanocomposites considered are nanoparticles of Ag, Au and indium tin oxide (ITO) with their varying fraction dispersed in the host dielectric matrix of WO3, SnO2 and TiO2. For analysis, the effective indices of nanocomposites are calculated by adopting the Maxwell–Garnett model for nanoparticles of dimensions much smaller than the wavelength of radiation used for investigation. The effects of the volume fraction of nanoparticles in different nanocomposites and the thickness of the nanocomposite layer on the sensitivity of the sensor have been studied. It has been found that the sensor with the ITO–TiO2 coated nanocomposite with a small volume fraction and optimized film thickness possesses higher sensitivity

  5. Spectral Modulation Effect in Teleseismic P-waves from North Korean Nuclear Tests Recorded in Broad Azimuthal Range and Possible Source Depth Estimation

    Science.gov (United States)

    Gitterman, Y.; Kim, S. G.; Hofstetter, R.

    2015-09-01

    Three underground nuclear explosions, conducted by North Korea in 2006, 2009 and 2013, are analyzed. The last two tests were recorded by the Israel Seismic Network. Pronounced coherent minima (spectral nulls) at 1.2-1.3 Hz were revealed in the spectra of teleseismic P-waves. For a ground-truth explosion with a shallow source depth, this phenomenon can be interpreted in terms of the interference between the down-going P-wave and the pP phase reflected from the Earth's surface. This effect was also observed at ISN stations for a Pakistan nuclear explosion at a different frequency 1.7 Hz and the PNE Rubin-2 in West Siberia at 1 Hz, indicating a source-effect and not a site-effect. Similar spectral minima having essentially the same frequency, as at ISN, were observed in teleseismic P-waves for all the three North Korean explosions recorded at networks and arrays in Kazakhstan (KURK), Norway (NNSN), Australia (ASAR, WRA) and Canada (YKA), covering a broad azimuthal range. Data of 2009 and 2013 tests at WRA and KURK arrays showed harmonic spectral modulation with three multiple minima frequencies, evidencing the clear interference effect. These observations support the above-mentioned interpretation. Based on the null frequency dependency on the near-surface acoustic velocity and the source depth, the depth of the North Korean tests was estimated about 2.0-2.1 km. It was shown that the observed null frequencies and the obtained source depth estimates correspond to P-pP interference phenomena in both cases of a vertical shaft or a horizontal drift in a mountain. This unusual depth estimation needs additional validation based on more stations and verification by other methods.

  6. Human Contrast Threshold and Astronomical Visibility

    CERN Document Server

    Crumey, Andrew

    2014-01-01

    The standard visibility model in light pollution studies is the formula of Hecht (1947), as used e.g. by Schaefer (1990). However it is applicable only to point sources and is shown to be of limited accuracy. A new visibility model is presented for uniform achromatic targets of any size against background luminances ranging from zero to full daylight, produced by a systematic procedure applicable to any appropriate data set (e.g Blackwell (1946)), and based on a simple but previously unrecognized empirical relation between contrast threshold and adaptation luminance. The scotopic luminance correction for variable spectral radiance (colour index) is calculated. For point sources the model is more accurate than Hecht's formula and is verified using telescopic data collected at Mount Wilson by Bowen (1947), enabling the sky brightness at that time to be determined. The result is darker than the calculation by Garstang (2004), implying that light pollution grew more rapidly in subsequent decades than has been sup...

  7. Synthesis, spectral (FT-IR, UV-visible, NMR) features, biological activity prediction and theoretical studies of 4-Amino-3-(4-hydroxybenzyl)-1H-1,2,4-triazole-5(4H)-thione and its tautomer

    Science.gov (United States)

    Srivastava, Ambrish Kumar; Kumar, Abhishek; Misra, Neeraj; Manjula, P. S.; Sarojini, B. K.; Narayana, B.

    2016-03-01

    Triazole compounds constitute an important class of organic chemistry due to their various biological and corrosion inhibition activities. The synthesis scheme of a new triazole compound namely, 4-Amino-3-(4-hydroxybenzyl)-1H-1,2,4-triazole-5(4H)-thione (4AHT) has been theoretically analyzed. Our density functional theory (DFT) based calculations show that the synthesis of 4AHT is energetically feasible at the room temperature as the reaction is exothermic, spontaneous as well as favored in forward direction. The calculated bond-lengths are found to be in good agreement with corresponding crystallographic values. We have considered two possible tautomers of 4AHT viz. thione and thiol forms. The FT-IR (KBr disc), UV-visible (ethanol) and 1H-NMR (DMSO) spectra of 4AHT have been recorded. The vibrational modes have been assigned on the basis of their potential energy distributions and scaled wavenumbers agree well with the FT-IR wavenumbers. Time dependent DFT calculations are performed to analyze the electronic transitions for various excited states which reproduce the experimental peak observed in UV-visible spectrum. Using gauge independent atomic orbital method 1H-NMR chemical shifts have been calculated and correlated with the experimental chemical shifts with the linear correlation coefficient of 0.9453. Our spectral analyses reveal the dominance of thione over thiol form of 4AHT. The chemical reactivity of 4AHT has been discussed by molecular electrostatic potential surface as well as various electronic parameters. The biological activities of 4AHT have also been explored theoretically and it has been found that the title molecule can act as a potential inhibitor of cyclin-dependent kinase 5 enzyme. These findings may guide the synthesis and design of new triazole compounds with interesting biological activity.

  8. The potential for extending the spectral range accessible to the european X-ray free electron laser in the direction of longer wavelengths

    CERN Document Server

    Saldin, E L; Yurkov, M V

    2004-01-01

    The baseline specifications of European XFEL give a range of wavelengths between 0.1 nm and 2 nm. This wavelength range at fixed electron beam energy 17.5 GeV can be covered by operating the SASE FEL with three undulators which have different period and tunable gap. A study of the potential for the extending the spectral range accessible to the XFEL in the direction of longer wavelengths is presented. The extension of the wavelength range to 6 nm would be cover the water window in the VUV region, opening the facility to a new class of experiments. There are at least two possible sources of VUV radiation associated with the X-ray FEL; the "low (2.5 GeV) energy electron beam dedicated" and the " 17.5 GeV spent beam parasitic" (or "after-burner") source modes. The second alternative, "after-burner undulator" is the one we regard as most favorable. It is possible to place an undulator as long as 80 meters after 2 nm undulator. Ultimately, VUV undulator would be able to deliver output power approaching 100 GW. A b...

  9. The Herschel/HIFI spectral survey of OMC-2 FIR 4 (CHESS): An overview of the 480 to 1902 GHz range

    CERN Document Server

    Kama, M; Dominik, C; Ceccarelli, C; Fuente, A; Caux, E; Higgins, R; Tielens, A G G M; Alonso-Albi, T

    2013-01-01

    Broadband spectral surveys of protostars offer a rich view of the physical, chemical and dynamical structure and evolution of star-forming regions. The Herschel Space Observatory opened up the terahertz regime to such surveys, giving access to the fundamental transitions of many hydrides and to the high-energy transitions of many other species. A comparative analysis of the chemical inventories and physical processes and properties of protostars of various masses and evolutionary states is the goal of the Herschel CHEmical Surveys of Star forming regions (CHESS) key program. This paper focusses on the intermediate-mass protostar, OMC-2 FIR 4. We obtained a spectrum of OMC-2 FIR 4 in the 480 to 1902 GHz range with the HIFI spectrometer onboard Herschel and carried out the reduction, line identification, and a broad analysis of the line profile components, excitation, and cooling. We detect 719 spectral lines from 40 species and isotopologs. The line flux is dominated by CO, H2O, and CH3OH. The line profiles ar...

  10. Visible spectroscopy on ASDEX

    International Nuclear Information System (INIS)

    In this report visible spectroscopy and impurity investigations on ASDEX are reviewed and several sets of visible spectra are presented. As a basis for identification of metallic impurity lines during plasma discharges spectra from a stainless steel - Cu arc have been recorded. In a next step a spectrum overview of ASDEX discharges is shown which reveals the dominating role of lines from light impurities like carbon and oxygen throughout the UV and visible range (2000 A ? ? ? 8000 A). Metallic impurity lines of neutrals or single ionized atoms are observed near localized surfaces. The dramatic effect of impurity reduction by boronization of the vessel walls is demonstrated in a few examples. In extension to some ivesti-gations already published, further diagnostic applications of visible spectroscopy are presented. Finally, the hardware and software system used on ASDEX are described in detail. (orig.)

  11. Gallium Phosphide as a material for visible and infrared optics

    OpenAIRE

    Václavík J.; Vápenka D.

    2013-01-01

    Gallium phosphide is interesting material for optical system working in both visible and MWIR or LWIR spectral ranges. Number of a material available for these applications is limited. They are typically salts, fluorides or sulphides and usually exhibit unfavorable properties like brittleness; softness; solubility in water and small chemical resistance. Although GaP has do not offer best optical parameters excels over most other material in mechanical and chemical resistance. The article...

  12. Depolarization effect in rare-earth doped Y{sub 2}O{sub 3} films in blue and UV spectral range

    Energy Technology Data Exchange (ETDEWEB)

    Gasimov, Naghi; Mammadov, Eldar; Babayev, Sardar; Mamedova, Irada; Mamedov, Nazim [Department of Ellipsometry, Institute of Physics, Azerbaijan National Academy of Sciences, H. Javid ave. 33, Baku-1143 (Azerbaijan); Joudrier, Anne L.; Andriamiadamanana, Christian; Naghavi, Negar; Guillemoles, Jean F. [Institute for Research and Development of Photovoltaic Energy, 6 Quai Watier, 78401 Chatou, Paris (France)

    2015-06-15

    The 200 to 300 nm thick, Er and Er,Yb doped Y{sub 2}O{sub 3} films deposited onto silicon substrate by spin coating have been studied by spectroscopic ellipsometry over the 192-1680 nm spectral range at room temperature. All samples have been found to be strongly depolarizing in the blue and UV part of the spectrum. Complimentary examination of the sample surfaces, using confocal photoluminescence microscopy has disclosed the non-uniform distribution of the rare-earth dopants. The depolarization effects have then been modeled and found to be best reproduced by taking the thickness non-uniformity as the main source of depolarization. The optical constants of the studied films have been determined after four-step modeling with sequential decrease of the mean square error. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Light-Emitting-Diodes based on ordered InGaN nanocolumns emitting in the blue, green and yellow spectral range

    International Nuclear Information System (INIS)

    The growth of ordered arrays of InGaN/GaN nanocolumnar light emitting diodes by molecular beam epitaxy, emitting in the blue (441 nm), green (502 nm), and yellow (568 nm) spectral range is reported. The device active region, consisting of a nanocolumnar InGaN section of nominally constant composition and 250 to 500 nm length, is free of extended defects, which is in strong contrast to InGaN (planar) layers of similar composition and thickness. Electroluminescence spectra show a very small blue shift with increasing current (almost negligible in the yellow device) and line widths slightly broader than those of state-of-the-art InGaN quantum wells. (paper)

  14. The Herschel/HIFI spectral survey of OMC-2 FIR 4 (CHESS). An overview of the 480 to 1902 GHz range

    Science.gov (United States)

    Kama, M.; López-Sepulcre, A.; Dominik, C.; Ceccarelli, C.; Fuente, A.; Caux, E.; Higgins, R.; Tielens, A. G. G. M.; Alonso-Albi, T.

    2013-08-01

    Context. Broadband spectral surveys of protostars offer a rich view of the physical, chemical and dynamical structure and evolution of star-forming regions. The Herschel Space Observatory opened up the terahertz regime to such surveys, giving access to the fundamental transitions of many hydrides and to the high-energy transitions of many other species. Aims: A comparative analysis of the chemical inventories and physical processes and properties of protostars of various masses and evolutionary states is the goal of the Herschel CHEmical Surveys of Star forming regions (CHESS) key program. This paper focusses on the intermediate-mass protostar, OMC-2 FIR 4. Methods: We obtained a spectrum of OMC-2 FIR 4 in the 480 to 1902 GHz range with the HIFI spectrometer onboard Herschel and carried out the reduction, line identification, and a broad analysis of the line profile components, excitation, and cooling. Results: We detect 719 spectral lines from 40 species and isotopologs. The line flux is dominated by CO, H2O, and CH3OH. The line profiles are complex and vary with species and upper level energy, but clearly contain signatures from quiescent gas, a broad component likely due to an outflow, and a foreground cloud. Conclusions: We find abundant evidence for warm, dense gas, as well as for an outflow in the field of view. Line flux represents 2% of the 7 L? luminosity detected with HIFI in the 480 to 1250 GHz range. Of the total line flux, 60% is from CO, 13% from H2O and 9% from CH3OH. A comparison with similar HIFI spectra of other sources is set to provide much new insight into star formation regions, a case in point being a difference of two orders of magnitude in the relative contribution of sulphur oxides to the line cooling of Orion KL and OMC-2 FIR 4. Appendix A is available in electronic form at http://www.aanda.org

  15. General approach to high power, coherent visible and ultraviolet light sources

    OpenAIRE

    Andersen, Martin Thalbitzer

    2010-01-01

    The main goal of this project is to develop a generic approach to synthesise any wavelength in the visible and UV spectral region based on sum frequency generation. The approach is based on a hybrid system combining solid state and semiconductor technology. The generation of light in the UV spectral region require nonlinear materials with a transparency range extending into the ultraviolet, the ability to sustain high photon energies and with the ability to obtain phasematch...

  16. General approach to high power, coherent visible and ultraviolet light sources

    OpenAIRE

    Andersen, Martin Thalbitzer; Tidemand-Lichtenberg, Peter; Pedersen, Christian

    2009-01-01

    The main goal of this project is to develop a generic approach to synthesise any wavelength in the visible and UV spectral region based on sum frequency generation. The approach is based on a hybrid system combining solid state and semiconductor technology. The generation of light in the UV spectral region require nonlinear materials with a transparency range extending into the ultraviolet, the ability to sustain high photon energies and with the ability to obtain phasematching for the desire...

  17. The Swift-UVOT ultraviolet and visible grism calibration

    CERN Document Server

    Kuin, N P M; Breeveld, A A; Page, M J; James, C; Lamoureux, H; Mehdipour, M; Still, M; Yershov, V; Brown, P J; Carter, M; Mason, K O; Kennedy, T; Marshall, F; Roming, P W A; Siegel, M; Oates, S; Smith, P J; De Pasquale, M

    2015-01-01

    We present the calibration of the Swift UVOT grisms, of which there are two, providing low-resolution field spectroscopy in the ultraviolet and optical bands respectively. The UV grism covers the range 1700-5000 Angstrom with a spectral resolution of 75 at 2600 Angstrom for source magnitudes of u=10-16 mag, while the visible grism covers the range 2850-6600 Angstrom with a spectral resolution of 100 at 4000 Angstrom for source magnitudes of b=12-17 mag. This calibration extends over all detector positions, for all modes used during operations. The wavelength accuracy (1-sigma) is 9 Angstrom in the UV grism clocked mode, 17 Angstrom in the UV grism nominal mode and 22 Angstrom in the visible grism. The range below 2740 Angstrom in the UV grism and 5200 Angstrom in the visible grism never suffers from overlapping by higher spectral orders. The flux calibration of the grisms includes a correction we developed for coincidence loss in the detector. The error in the coincidence loss correction is less than 20%. The...

  18. Spectral Tagging

    International Nuclear Information System (INIS)

    This research examines the feasibility of spectral tagging, which involves modifying the spectral signature of a target, e.g. by mixing an additive with the target's paint. The target is unchanged to the human eye, but the tag is revealed when viewed with a spectrometer. This project investigates a layer of security that is not obvious, and therefore easy to conceal. The result is a tagging mechanism that is difficult to counterfeit. Uniquely tagging an item is an area of need in safeguards and security and non-proliferation. The powdered forms of the minerals lapis lazuli and olivine were selected as the initial test tags due to their availability and uniqueness in the visible to near-infrared spectral region. They were mixed with paints and applied to steel. In order to verify the presence of the tags quantitatively, the data from the spectrometer was input into unmixing models and signal detection algorithms. The mixture with the best results was blue paint mixed with lapis lazuli and olivine. The tag had a 0% probability of false alarm and a 100% probability of detection. The research proved that spectral tagging is feasible, although certain tag/paint mixtures are more detectable than others

  19. UVMag: Space UV and visible spectropolarimetry

    CERN Document Server

    Pertenais, Martin; Pares, Laurent; Petit, Pascal; Snik, Frans; van harten, Gerard

    2014-01-01

    UVMag is a project of a space mission equipped with a high-resolution spectropolarimeter working in the UV and visible range. This M-size mission will be proposed to ESA at its M4 call. The main goal of UVMag is to measure the magnetic fields, winds and environment of all types of stars to reach a better understanding of stellar formation and evolution and of the impact of stellar environment on the surrounding planets. The groundbreaking combination of UV and visible spectropolarimetric observations will allow the scientists to study the stellar surface and its environment simultaneously. The instrumental challenge for this mission is to design a high-resolution space spectropolarimeter measuring the full-Stokes vector of the observed star in a huge spectral domain from 117 nm to 870 nm. This spectral range is the main difficulty because of the dispersion of the optical elements and of birefringence issues in the FUV. As the instrument will be launched into space, the polarimetric module has to be robust and...

  20. Spectral range calculation inside the Research Irradiating Facility Army Technology Center using code MCNPX and comparison with the spectra of energy Caesium 137 raised in laboratory

    International Nuclear Information System (INIS)

    Using the MCNPX code, the objective was to calculate by means of computer simulation spectroscopy range inside the irradiation chamber upper radiator gamma research irradiating facility Army Technology Center (CTEx). The calculations were performed in the spectral range usual 2 points for research purposes irradiating the energy spectra of gamma rays from the source of Cesium chloride 137. Sought the discretization of the spectrum in 100 channels at points of upper bound of 1cm higher and lower dose rates previously known. It was also conducted in the laboratory lifting the spectrum of Cesium-137 source using NaI scintillator detector and multichannel analyzer. With the source spectrum Cesium-137 contained in the literature and raised in the laboratory, both used as reference for comparison and analysis in terms of probability of emission maximum of 0.661 MeV The spectra were quite consistent in terms of the behavior of the energy distributions with scores. The position of maximum dose rate showed absorption detection almost maximum energy of 0.661 MeV photopeak In the spectrum of the position of minimum dosage rate, it was found that due to the removal of the source point of interest, some loss detection were caused by Compton scattering. (author)

  1. A new method to extract gas concentrations in the ultraviolet and visible wavelength ranges, based on differential optical absorption technique and Fourier transform

    International Nuclear Information System (INIS)

    By combining differential optical absorption technique with Fourier transformation we obtain a measuring method exhibiting high sensitivity, good accuracy and good robustness against wavelength displacements in the spectrum obtained. The method also separates different gases in the absorption spectrum from each other in an effective way. The above mentioned features make this method attractive. The ability to separate gases is especially rewarding; it means that we need not know which gases are present when we start to measure. The only prerequisite is that the gases involved absorb in the wavelength range that is to be measured. The method appears to be well suited for the detection of atmospheric pollutions

  2. Salinity and spectral reflectance of soils

    Science.gov (United States)

    Szilagyi, A.; Baumgardner, M. F.

    1991-01-01

    The basic spectral response related to the salt content of soils in the visible and reflective IR wavelengths is analyzed in order to explore remote sensing applications for monitoring processes of the earth system. The bidirectional reflectance factor (BRF) was determined at 10 nm of increments over the 520-2320-nm spectral range. The effect of salts on reflectance was analyzed on the basis of 162 spectral measurements. MSS and TM bands were simulated within the measured spectral region. A strong relationship was found in variations of reflectance and soil characteristics pertaining to salinization and desalinization. Although the individual MSS bands had high R-squared values and 75-79 percent of soil/treatment combinations were separable, there was a large number of soil/treatment combinations not distinguished by any of the four highly correlated MSS bands under consideration.

  3. Determination of Seed Soundness in Conifers Cryptomeria japonica and Chamaecyparis obtusa Using Narrow-Multiband Spectral Imaging in the Short-Wavelength Infrared Range.

    Science.gov (United States)

    Matsuda, Osamu; Hara, Masashi; Tobita, Hiroyuki; Yazaki, Kenichi; Nakagawa, Toshinori; Shimizu, Kuniyoshi; Uemura, Akira; Utsugi, Hajime

    2015-01-01

    Regeneration of planted forests of Cryptomeria japonica (sugi) and Chamaecyparis obtuse (hinoki) is the pressing importance to the forest administration in Japan. Low seed germination rate of these species, however, has hampered low-cost production of their seedlings for reforestation. The primary cause of the low germinability has been attributed to highly frequent formation of anatomically unsound seeds, which are indistinguishable from sound germinable seeds by visible observation and other common criteria such as size and weight. To establish a method for sound seed selection in these species, hyperspectral imaging technique was used to identify a wavelength range where reflectance spectra differ clearly between sound and unsound seeds. In sound seeds of both species, reflectance in a narrow waveband centered at 1,730 nm, corresponding to a lipid absorption band in the short-wavelength infrared (SWIR) range, was greatly depressed relative to that in adjacent wavebands on either side. Such depression was absent or less prominent in unsound seeds. Based on these observations, a reflectance index SQI, abbreviated for seed quality index, was formulated using reflectance at three narrow SWIR wavebands so that it represents the extent of the depression. SQI calculated from seed area-averaged reflectance spectra and spatial distribution patterns of pixelwise SQI within each seed area were both proven as reliable criteria for sound seed selection. Enrichment of sound seeds was accompanied by an increase in germination rate of the seed lot. Thus, the methods described are readily applicable toward low-cost seedling production in combination with single seed sowing technology. PMID:26083366

  4. Visible Light Induces Melanogenesis in Human Skin through a Photoadaptive Response.

    Science.gov (United States)

    Randhawa, Manpreet; Seo, InSeok; Liebel, Frank; Southall, Michael D; Kollias, Nikiforos; Ruvolo, Eduardo

    2015-01-01

    Visible light (400-700 nm) lies outside of the spectral range of what photobiologists define as deleterious radiation and as a result few studies have studied the effects of visible light range of wavelengths on skin. This oversight is important considering that during outdoors activities skin is exposed to the full solar spectrum, including visible light, and to multiple exposures at different times and doses. Although the contribution of the UV component of sunlight to skin damage has been established, few studies have examined the effects of non-UV solar radiation on skin physiology in terms of inflammation, and limited information is available regarding the role of visible light on pigmentation. The purpose of this study was to determine the effect of visible light on the pro-pigmentation pathways and melanin formation in skin. Exposure to visible light in ex-vivo and clinical studies demonstrated an induction of pigmentation in skin by visible light. Results showed that a single exposure to visible light induced very little pigmentation whereas multiple exposures with visible light resulted in darker and sustained pigmentation. These findings have potential implications on the management of photo-aggravated pigmentary disorders, the proper use of sunscreens, and the treatment of depigmented lesions. PMID:26121474

  5. Nonlinear spectral imaging of biological tissues

    Science.gov (United States)

    Palero, J. A.

    2007-07-01

    The work presented in this thesis demonstrates live high resolution 3D imaging of tissue in its native state and environment. The nonlinear interaction between focussed femtosecond light pulses and the biological tissue results in the emission of natural autofluorescence and second-harmonic signal. Because biological intrinsic emission is generally very weak and extends from the ultraviolet to the visible spectral range, a broad-spectral range and high sensitivity 3D spectral imaging system is developed. Imaging the spectral characteristics of the biological intrinsic emission reveals the structure and biochemistry of the cells and extra-cellular components. By using different methods in visualizing the spectral images, discrimination between different tissue structures is achieved without the use of any stain or fluorescent label. For instance, RGB real color spectral images of the intrinsic emission of mouse skin tissues show blue cells, green hair follicles, and purple collagen fibers. The color signature of each tissue component is directly related to its characteristic emission spectrum. The results of this study show that skin tissue nonlinear intrinsic emission is mainly due to the autofluorescence of reduced nicotinamide adenine dinucleotide (phosphate), flavins, keratin, melanin, phospholipids, elastin and collagen and nonlinear Raman scattering and second-harmonic generation in Type I collagen. In vivo time-lapse spectral imaging is implemented to study metabolic changes in epidermal cells in tissues. Optical scattering in tissues, a key factor in determining the maximum achievable imaging depth, is also investigated in this work.

  6. Tethys - Geological and Spectral Properties

    Science.gov (United States)

    Stephan, Katrin; Jaumann, Ralf; Wagner, Roland; Clark, Roger N.; Cruikshank, Dale P.; Dalle Ore, Cristina; Brown, Robert H.; Giese, Bernd; Roatsch, Thomas; Matson, Dennis; Baines, Kevin H.; Filacchione, Gianrico; Capaccione, Fabrizio; Burratti, Bonnie J.; Nicholson, Phil D.; Rodriguez, Sebastian

    2015-04-01

    Despite the spectral dominance of H2O ice on Tethys' surface, distinct spectral variations derived by the Cassini VIMS instrument could be detected. The ice infrared absorption strengths are very different from what was expected from the visible albedo derived from Voyager and Cassini camera data. Although on Tethys, the major ice absorptions at 1.5 and 2µm are general stronger on the leading hemisphere of the satellite similar to that seen on the neighboring satellites Dione and Rhea, the detailed mapping shows a more complex pattern. Two relatively narrow N/S trending bands enriched in H2O ice of relatively large particle size separate the Saturn-facing and the anti-Saturnian hemisphere. The largest impact crater Odysseus (33°N/129°W) is included in the N/S trending band of deeper H2O absorptions on the leading hemisphere, whereas the geologically older and fourth largest impact crater Penelope (11°S/249°W) is excluded from the 'icy' band on the trailing hemisphere - supporting an exogenic origin of these bands. The oval shaped dark albedo unit observed by Voyager in the equatorial region of Tethys' leading hemisphere, which could be related to magnetospheric 'dust' impacting the surface, exhibits slightly surpressed H2O ice absorptions compared to their surrounding regions. Variations in the spectral slope from the visible to the ultra-violet wavelength range are similar to the variations observed by Cassini ISS. The spectral slope is steepest (i.e. the effect of an ultra-violet absorber other than H2O ice is strongest) on the leading as well on the trailing hemisphere. No spectral properties could be exclusively associated with Tethys' extended graben system Ithaca Chasma. Local variations, i.e. local deepening of H2O ice absorptions, are mostly related to several probably fresh impact craters and to locations where topographic slope is high like crater walls. However, only a few such fresh impact craters could be observed.

  7. Predicting visibility of aircraft.

    Science.gov (United States)

    Watson, Andrew; Ramirez, Cesar V; Salud, Ellen

    2009-01-01

    Visual detection of aircraft by human observers is an important element of aviation safety. To assess and ensure safety, it would be useful to be able to be able to predict the visibility, to a human observer, of an aircraft of specified size, shape, distance, and coloration. Examples include assuring safe separation among aircraft and between aircraft and unmanned vehicles, design of airport control towers, and efforts to enhance or suppress the visibility of military and rescue vehicles. We have recently developed a simple metric of pattern visibility, the Spatial Standard Observer (SSO). In this report we examine whether the SSO can predict visibility of simulated aircraft images. We constructed a set of aircraft images from three-dimensional computer graphic models, and measured the luminance contrast threshold for each image from three human observers. The data were well predicted by the SSO. Finally, we show how to use the SSO to predict visibility range for aircraft of arbitrary size, shape, distance, and coloration. PMID:19462007

  8. Correlation of Spectral Solar Irradiance with solar activity as measured by VIRGO

    OpenAIRE

    Wehrli, C.; Schmutz, W.; Shapiro, A. I.

    2013-01-01

    Context. The variability of Solar Spectral Irradiance over the rotational period and its trend over the solar activity cycle are important for understanding the Sun-Earth connection as well as for observational constraints for solar models. Recently the SIM experiment on SORCE has published an unexpected negative correlation with Total Solar Irradiance of the visible spectral range. It is compensated by a strong and positive variability of the near UV range. Aims. We aim to ...

  9. Comparison between visible and near-IR flame spectra from natural gas-fired furnace for blackbody temperature measurements

    Energy Technology Data Exchange (ETDEWEB)

    Shahla Keyvan; Rodney Rossow; Carlos Romero; Xianchang Li [University of Missouri, Columbia, MO (United States). Department of Mechanical and Aerospace Engineering

    2004-06-01

    This paper reports the results from investigating the feasibility of calculating flame temperature from a natural gas-fired furnace based on blackbody radiation in the visible spectral range. If successful, the visible spectral range would provide data for multi-task applications such as emission line analysis and temperature calculation simultaneously. A probe containing a lens connected to the fiber-optic cables is inserted into the furnace and pointed towards the flame. Spectral intensity data are fed back to a spectrometer and then to a monitoring computer. The approach is first applied to various furnace types using the visible range to establish a baseline for the technique. The results for temperature calculations in the visible range are then compared with those taken in the near-IR (NIR) range under the same conditions. This comparison indicates that temperatures calculated from visible region could be as accurate as the one obtained from NIR region. Challenges associated with this technique are also discussed. 17 refs., 5 figs., 1 tab.

  10. Morphology of the spectral resonance structure of the electromagnetic background noise in the range of 0.1–4 Hz at L = 5.2

    Directory of Open Access Journals (Sweden)

    J. Manninen

    Full Text Available Continuous observations of fluctuations of the geomagnetic field at Sodankylä Geophysical Observatory (L = 5.2 were used for a comprehensive morphological study of the spectral resonance structure (SRS seen in the background electromagnetic noise in the frequency range of 0.1–4.0 Hz. It is shown that the occurrence rate of SRS is higher in the nighttime than in the daytime. The occurrence rate is higher in winter than in summer. The SRS frequencies and the difference between neighbouring eigenfrequencies (the frequency scale increase towards nighttime and decrease towards daytime. Both frequency scale and occurrence rate exhibit a clear tendency to decrease from minimum to maximum of the solar activity cycle. It is found that the occurrence rate of SRS decreases when geomagnetic activity increases. The SRS is believed to be a consequence of a resonator for Alfvén waves, which is suggested to exist in the upper ionosphere. According to the theory of the ionospheric Alfvén resonator (IAR, characteristics of SRS crucially depend on electron density in the F-layer maximum, as well as on the altitudinal scale of the density decay above the maximum.We compared the SRS morphological properties with predictions of the IAR theory. The ionospheric parameters needed for calculation were obtained from the ionosphere model (IRI-95, as well as from measurements made with the ionosonde in Sodankylä. We conclude that, indeed, the main morphological properties of SRS are explained on the basis of the IAR theory. The measured parameters of SRS can be used for improving the ionospheric models.Key words. Ionosphere (auroral ionosphere; wave propagation – Radio Science (electromagnetic noise and interference

  11. Gold nanoparticles as a saturable absorber for visible 635 nm Q-switched pulse generation.

    Science.gov (United States)

    Wu, Duanduan; Peng, Jian; Cai, Zhiping; Weng, Jian; Luo, Zhengqian; Chen, Nan; Xu, Huiying

    2015-09-01

    Gold nanoparticle (GNP) possesses saturable absorption bands in the visible region induced by surface plasmon resonance (SPR). We firstly applied the GNP as a visible saturable absorber (SA) for the red Q-switched pulse generation. The GNPs were embedded in polyvinyl alcohol (PVA) for film-forming and inserted into a praseodymium (Pr3+)-doped fiber laser cavity to achieve 635 nm passive Q-switching. The visible 635 nm Q-switched fiber laser has a wide range of pulse-repetition-rate from 285.7 to 546.4 kHz, and a narrow pulse width of 235 ns as well as the maximum output power of 11.1 mW. The results indicate that the GNPs-based SA is available for pulsed operation in the visible spectral range. PMID:26368498

  12. Specific features of diffuse reflection of human face skin for laser and non-laser sources of visible and near-IR light

    International Nuclear Information System (INIS)

    The specific features of diffuse reflection from different areas of human face skin for laser and non-laser sources of visible and near-IR light have been investigated to localise the closed-eye (eyelid) region. In the visible spectral range the reflection from the eyelid skin surface can be differentiated by measuring the slope of the spectral dependence of the effective optical density of skin in the wavelength range from 650 to 700nm. In the near-IR spectral range the reflectances of the skin surface at certain wavelengths, normalised to the forehead skin reflectance, can be used as a criterion for differentiating the eyelid skin. In this case, a maximum discrimination is obtained when measuring the skin reflectances at laser wavelengths of 1310 and 1470nm, which correspond to the spectral ranges of maximum and minimum water absorption. (optical technologies in biophysics and medicine)

  13. Monitoring Urban Wastewaters’ Characteristics by Visible and Short Wave Near-Infrared Spectroscopy

    Directory of Open Access Journals (Sweden)

    Ignacio Melendez-Pastor

    2013-12-01

    Full Text Available On-line monitoring of wastewater parameters is a major scientific and technical challenge because of the great variability of wastewater characteristics and the extreme physical-chemical conditions that endure the sensors. Wastewater treatment plant managers require fast and reliable information about the input sewage and the operation of the different treatment stages. There is a great need for the development of sensors for the continuous monitoring of wastewater parameters. In this sense, several optical systems have been evaluated. This article presents an experimental laboratory-based approach to quantify commonly employed urban wastewater parameters, namely biochemical oxygen demand in five days (BOD5, chemical oxygen demand (COD, total suspended solids (TSS, and the ratio BOD5:COD, with a visible and short wave near infrared (V/SW-NIR spectrometer (400–1000 nm. Partial least square regression (PLSR models were developed in order to quantify the wastewater parameters with the recorded spectra. PLSR models were developed for the full spectral range and also for the visible and near infrared spectral ranges separately. Good PLSR models were obtained with the visible spectral range for BOD5 (RER = 9.64, COD (RER = 10.88, and with the full spectral range for the TSS (RER = 9.67. The results of this study show that V/SW-NIR spectroscopy is a suitable technique for on-line monitoring of wastewater parameters.

  14. Visible Light Communication

    Directory of Open Access Journals (Sweden)

    Rajan Sagotra, Reena Aggarwal

    2013-04-01

    Full Text Available Visible light communication (VLC is becoming an alternative choice for next-generation wireless technology by offering low cost, unregulated bandwidth and ubiquitous infrastructures support. This technology is envisioned to be used in a wide range of applications both indoor as well as outdoor. Visible Light Communication (VLC uses light emitting diodes (LEDs, for the dual role of illumination and data transmission. With this leading edge technology, data including video and audio, internet traffic etc can be transmitted at high speeds using LED light. Using LEDs is helping to drive this technology in the form of Visible Light Communication (VLC. In this paper, a visible light communications system is proposed that employs wavelength division multiplexing, to transmit multiple data streams from different data sources simultaneously andtransmission of audio song and also an image was demonstrated by using LED light. Not limit to this, multiple source signals simultaneously in different frequency bands were transmitted through the LED circuitry, and the signals were recovered successfully. This demonstrates the feasibility studies of our design in signals broadcasting

  15. Machine vision beyond visible spectrum

    CERN Document Server

    Hammoud, Riad I; McMillan, Robert W

    2011-01-01

    The material of this book encompasses many disciplines, including visible, infrared, far infrared, millimeter wave, microwave, radar, synthetic aperture radar, and electro-optical sensors as well as the very dynamic topics of image processing, computer vision and pattern recognition. This book is composed of six parts: advanced background modeling for surveillance; advances in Tracking in Infrared imagery; methods for Pose estimation in Ultrasound and LWIR imagery; recognition in multi-spectral and synthetic aperture radar; fusion of disparate sensors; and smart Sensors.

  16. Validation of HITEMP-2010 for carbon dioxide and water vapour at high temperatures and atmospheric pressures in 450-7600cm-1 spectral range

    DEFF Research Database (Denmark)

    Alberti, Michael; Weber, Roman; Mancini, Marco; Fateev, Alexander; Clausen, Sønnik

    2015-01-01

    The objective of the work is validation of HITEMP-2010 at atmospheric pressures and temperatures reaching 1770K. To this end, spectral transmissivities at 1cm-1 resolution and excellent signal-to-noise-ratio have been measured for 22 CO2/H2O/N2 mixtures. In this paper we consider the 450cm-1-7600cm...

  17. Resonant Visible Light Modulation with Graphene

    CERN Document Server

    Yu, Renwen; de Abajo, F Javier Garcia

    2015-01-01

    Fast modulation and switching of light at visible and near-infrared (vis-NIR) frequencies is of utmost importance for optical signal processing and sensing technologies. No fundamental limit appears to prevent us from designing wavelength-sized devices capable of controlling the light phase and intensity at gigaherts (and even terahertz) speeds in those spectral ranges. However, this problem remains largely unsolved, despite recent advances in the use of quantum wells and phase-change materials for that purpose. Here, we explore an alternative solution based upon the remarkable electro-optical properties of graphene. In particular, we predict unity-order changes in the transmission and absorption of vis-NIR light produced upon electrical doping of graphene sheets coupled to realistically engineered optical cavities. The light intensity is enhanced at the graphene plane, and so is its absorption, which can be switched and modulated via Pauli blocking through varying the level of doping. Specifically, we explor...

  18. Spectral homogenization techniques for the hyperspectral image projector

    Science.gov (United States)

    Hillberry, Logan E.; Rice, Joseph P.

    2015-05-01

    In an effort to improve technology for performance testing and calibration of multispectral and hyperspectral imagers, the National Institute of Standards and Technology (NIST) has been developing a Hyperspectral Image Projector (HIP) capable of projecting dynamic scenes than include distinct, programmable spectra in each of its 1024x768 spatial pixels. The HIP is comprised of a spectral engine, which is a light source capable generating the spectra in the scene, coupled to a spatial engine, capable of projecting the spectra into the correct locations of the scene. In the prototype HIP, the light exiting the Visible-Near-Infrared (VNIR) / Short-Wavelength Infrared (SWIR) spectral engine is spectrally dispersed and needs to be spectrally homogenized before it enters the spatial engine. In this paper we describe the results from a study of several different techniques for performing this spectral homogenization. These techniques include an integrating sphere, a liquid light guide, a randomized fiber bundle, and an engineered diffuser, in various combinations. The spectral uniformity of projected HIP scenes is measured and analyzed using the spectral angle mapper (SAM) algorithm over the VNIR spectral range. The SAM provides a way to analyze the spectral uniformity independently from the radiometric uniformity. The goal of the homogenizer is a spectrally uniform and bright projected image. An integrating sphere provides the most spectrally uniform image, but at a great loss of light compared with the other methods. The randomized fiber bundle generally outperforms the liquid light guide in both spectral homogenization and brightness. Using an engineered diffuser with the randomized fiber bundle increases the spectral uniformity by a factor of five, with a decrease in brightness by a factor of five, compared with the randomized fiber bundle alone. The combination of an engineered diffuser with a randomized fiber bundle provides comparable spectral uniformity to the integrating sphere while enabling 40 times greater brightness.

  19. Validation of line and continuum spectroscopic parameters with measurements of atmospheric emitted spectral radiance from far to mid infrared wave number range

    International Nuclear Information System (INIS)

    The latest release of a high-resolution transmission molecular absorption database along with two improved models of water vapor continuum absorption are used to check their impact on the improvement of state-of-art radiative transfer. Radiative transfer performance has been assessed using high mountains atmospheric emitted spectral downwelling radiance observations in the 360-1200 cm-1 spectral regions. These high mountains observations are particularly suited to check the behavior and performance in the water vapor rotation band. In addition, they also have allowed us to gain insight into understanding the quality of recent new compilation of lines and related treatment for the ?2 CO2 band and the O3 band at 9.6?m. Comparisons are made between forward calculations of atmospheric transmission spectra and spectral radiances measured using two ground-based Fourier transform instruments. The results demonstrate that water vapor absorption largely benefits from the recent improvement in the related continuum (both self and foreign). In addition, ozone absorption is very accurately reproduced and, although to a less extent, this is also the case of CO2 absorption in the long wave ?2 band.

  20. The Visible and Near Infrared module of EChO

    OpenAIRE

    Adriani, A.;; Bellucci, G.; Gambicorti, L.; Focardi, M; Oliva, E.; M. Farina; di Giorgio, A.M.; Santoli, F.; Pace, E.; Piccioni, G...; Filacchione, G.; Pancrazzi, M.; Tozzi, A; Micela, G.

    2014-01-01

    The Visible and Near Infrared (VNIR) is one of the modules of EChO, the Exoplanets Characterization Observatory proposed to ESA for an M-class mission. EChO is aimed to observe planets while transiting by their suns. Then the instrument had to be designed to assure a high efficiency over the whole spectral range. In fact, it has to be able to observe stars with an apparent magnitude Mv= 9-12 and to see contrasts of the order of 10-4 - 10-5 necessary to reveal the characteristics of the atmosp...

  1. Gallium Phosphide as a material for visible and infrared optics

    Directory of Open Access Journals (Sweden)

    Václavík J.

    2013-05-01

    Full Text Available Gallium phosphide is interesting material for optical system working in both visible and MWIR or LWIR spectral ranges. Number of a material available for these applications is limited. They are typically salts, fluorides or sulphides and usually exhibit unfavorable properties like brittleness; softness; solubility in water and small chemical resistance. Although GaP has do not offer best optical parameters excels over most other material in mechanical and chemical resistance. The article describes its most important characteristics and outlines some applications where GaP should prove useful.

  2. PlanetCam UPV/EHU: A Two-channel Lucky Imaging Camera for Solar System Studies in the Spectral Range 0.38–1.7 μm

    Science.gov (United States)

    Mendikoa, Iñigo; Sánchez-Lavega, Agustín; Pérez-Hoyos, Santiago; Hueso, Ricardo; Félix Rojas, José; Aceituno, Jesús; Aceituno, Francisco; Murga, Gaizka; De Bilbao, Lander; García-Melendo, Enrique

    2016-03-01

    We present PlanetCam UPV/EHU, an astronomical camera designed fundamentally for high-resolution imaging of Solar System planets using the “lucky imaging” technique. The camera observes in a wavelength range from 380 nm to 1.7 μm and the driving science themes are atmosphere dynamics and vertical cloud structure of Solar System planets. The design comprises two configurations that include one channel (visible wavelengths) or two combined channels (visible and short wave infrared) working simultaneously at selected wavelengths by means of a dichroic beam splitter. In this paper the camera components for the two configurations are described, as well as camera performance and the different tests done for the precise characterization of its radiometric and astrometric capabilities at high spatial resolution. Finally, some images of solar system objects are presented as well as photometric results and different scientific cases on astronomical targets.

  3. Demonstration of Magnetic Dipole Resonances of Dielectric Nanospheres in the Visible Region

    DEFF Research Database (Denmark)

    Evlyukhin, A. B.; Novikov, S. M.; Zywietz, U.; Eriksen, R. L.; Reinhardt, C.; Bozhevolnyi, S. I.; Chichkov, B. N.

    2012-01-01

    Strong resonant light scattering by individual spherical Si nanoparticles is experimentally demonstrated, revealing pronounced resonances associated with the excitation of magnetic and electric modes in these nanoparticles. It is shown that the low-frequency resonance corresponds to the magnetic...... dipole excitation. Due to high permittivity, the magnetic dipole resonance is observed in the visible spectral range for Si nanoparticles with diameters of similar to 200 nm, thereby opening a way to the realization of isotropic optical metamaterials with strong magnetic responses in the visible region....

  4. Visible light scatter as quantitative information source on milk constituents

    DEFF Research Database (Denmark)

    Melentieva, Anastasiya; Kucheryavskiy, Sergey; Bogomolov, Andrey

    2012-01-01

    VISIBLE LIGHT SCATTER AS A QUANTITATIVE INFORMATION SOURCE ON MILK CONSTITUENTS A. Melenteva 1, S. Kucheryavski 2, A. Bogomolov 1,31Samara State Technical University, Molodogvardeyskaya Street 244, 443100 Samara, Russia. 2Aalborg University, campus Esbjerg, Niels Bohrs vej 8, 6700 Esbjerg, Denmark...... analysis. The main task here is to extract individual quantitative information on milk fat and total protein content from spectral data. This is particularly challenging problem in the case of raw natural milk, where the fat globule sizes may essentially differ depending on source. Fig. 1. Spots of light...... data analysis stage. The region of visible (Vis) light (400-800 nm) is economically attractive, because it offers a range of inexpensive light sources, optics and detectors. At present, however, it is commonly considered useless, because of the light scatter by fat globules (1-10 ?m) and protein...

  5. A Fourier transform Raman spectrometer with visible laser excitation

    CERN Document Server

    Dzsaber, S; Bernáth, B; Gyüre, B; Fehér, T; Kramberger, C; Pichler, T; Simon, F

    2014-01-01

    We present the development and performance of a Fourier transformation (FT) based Raman spectrometer working with visible laser (532 nm) excitation. It is generally thought that FT-Raman spectrometers are not viable in the visible range where shot-noise limits the detector performance and therein they are outperformed by grating based, dispersive ones. We show that contrary to this common belief, the recent advances of high-performance interference filters makes the FT-Raman design a valid alternative to dispersive Raman spectrometers for samples which do not luminesce. We critically compare the performance of our spectrometer to two dispersive ones: a home-built single channel and a state-of-the-art CCD based instruments. We demonstrate a similar or even better sensitivity than the CCD based dispersive spectrometer particularly when the laser power density is considered. The instrument possesses all the known advantages of the FT principle of spectral accuracy, high throughput, and economic design. We also d...

  6. COLLI - a Monte Carlo program for calculating neutron spectral fluences in the energy range 10 keV to 20 MeV - description and application

    International Nuclear Information System (INIS)

    The program described can be applied to calculating the transport of neutrons through an arrangement of bodies that can be extensively varied in geometry and materials. The information obtainable by this program includes data on the spectral fluence of scattered neutrons for a set of up to 10 random measuring points. Fortran IV is the programming language. For the calculation of neutron interactions, point cross sections of the ENDF data library are used, either in the original version or in a condensed form. The data are processed for the following elements: Hydrogen, carbon, nitrogen, oxygen, aluminum, silicon, calcium, iron, copper, tungsten, and lead. (orig./HP)

  7. Validation of H2O continuum absorption models in the wave number range 180-600 cm(-1) with atmospheric emitted spectral radiance measured at the Antarctica Dome-C site.

    Science.gov (United States)

    Liuzzi, Giuliano; Masiello, Guido; Serio, Carmine; Palchetti, Luca; Bianchini, Giovanni

    2014-07-14

    This work presents the results concerning the analysis of a set of atmospheric emitted (down welling) spectral radiance observations in the spectral range 180 to 1100 cm(-1) acquired at the Dome-C site in Antarctica during an extensive field campaign in 2011-2012. The work has been mainly focused on retrieving and validating the coefficients of the foreign contribution to the water vapour continuum absorption, within a spectral range overlapping the water vapour rotational band. Retrievals have been performed by using a simultaneous physical retrieval procedure for atmospheric and spectroscopic parameters. Both day (summer) and night (winter) spectra have been used in our analysis. This new set of observations in the far infrared range has allowed us to extend validation and verification of state-of-art water vapour continuum absorption models down to 180 cm(-1). Results show that discrepancies between measurements and models are less than 10% in the interval 350-590 cm(-1), while they are slightly larger at wave numbers below 350 cm(-1). On overall, our study shows a good consistency between observations and state-of-art models and provides evidence toward needing to adjust absorptive line strengths. Finally, it has been found that there is a good agreement between the coefficients retrieved using either summer or winter spectra, which are acquired in far different meteorological conditions. PMID:25090497

  8. Spectral mixture analysis of multispectral thermal infrared images

    International Nuclear Information System (INIS)

    Remote spectral measurements of light reflected or emitted from terrestrial scenes is commonly integrated over areas sufficiently large that the surface comprises more than one component. Techniques have been developed to analyze multispectral or imaging spectrometer data in terms of a wide range of mixtures of a limited number of components. Spectral mixture analysis has been used primarily for visible and near-infrared images, but it may also be applied to thermal infrared data. Two approaches are reviewed: binary mixing and a more general treatment for isothermal mixtures of a greater number of components

  9. The Shining Future of UV Spectral Synthesis

    OpenAIRE

    Pellerin, Anne; Finkelstein, Steven L.

    2009-01-01

    With the coming generation of instruments and telescopes capable of spectroscopy of high redshift galaxies, the spectral synthesis technique in the rest-frame UV and Far-UV range will become one of a few number of tools remaining to study their young stellar populations in detail. The rest-frame UV lines and continuum of high redshift galaxies, observed with visible and infrared telescopes on Earth, can be used for accurate line profile fitting such as PV@1118,1128A, CIII@1176A, and CIV@1550A...

  10. Electric dipole-free interaction of visible light with pairs of subwavelength-size silver particles

    OpenAIRE

    Grahn, Patrick; Shevchenko, Andriy; Kaivola, Matti

    2012-01-01

    In subwavelength-sized particles, light-induced multipole moments of orders higher than the electric dipole are usually negligibly small, which allows for the light-matter interaction to be accurately treated within the electric dipole approximation. In this work we show that in a specially designed meta-atom, a disc metadimer, the electric quadrupole and magnetic dipole can be the only excitable multipoles. This condition is achieved in a narrow but tunable spectral range of visible light bo...

  11. Electric dipole-free interaction of visible light with silver metadimers

    OpenAIRE

    Grahn, P.; Shevchenko, A.; Kaivola, M.

    2012-01-01

    In subwavelength-sized particles, light-induced multipole moments of orders higher than the electric dipole are usually negligibly small, which allows for the light-matter interaction to be accurately treated within the electric dipole approximation. In this work we show that in a specially designed meta-atom, a disc metadimer, the electric quadrupole and magnetic dipole can be the only excitable multipoles. This condition is achieved in a narrow but tunable spectral range of visible light bo...

  12. Glasses for seeing beyond visible.

    Science.gov (United States)

    Zhang, XiangHua; Bureau, Bruno; Lucas, Pierre; Boussard-Pledel, Catherine; Lucas, Jacques

    2008-01-01

    Conventional glasses based on oxides have a transparency limited by phonon absorption in the near IR region and have a limited interest for analyzing information located far beyond the visible. The IR spectral domain is nevertheless of prime interest, since it covers fundamental wavelength ranges used for thermal imaging as well as molecular vibrational signatures. Besides spectacular advances in the field of IR detectors, the main significant progresses are related to the development of IR glass optics, such as lenses or IR optical fibres. The field of IR glasses is almost totally dominated by glasses formed from heavy atoms such as the chalcogens S, Se and Te. Their transparency extends up to 12, 16 and 28 microm for sulfide-, selenide- and the new generation of telluride-based glasses, respectively. They cover the atmospheric transparency domains, 3-5 and 8-13 microm, respectively, at which the IR radiation can propagate allowing thermal imaging and night-vision operations through thick layers of atmosphere. The development of new glass compositions will be discussed on the basis of structural consideration with the objective of moulding low-cost lenses for IR cameras used, for instance, in car-driving assistance. Additionally, multimode, single-index, optical fibres operating in the 3 to 12 microm window developed for in situ remote evanescent-wave IR spectroscopy will also be mentioned. The detection of molecular IR signatures is applied to environmental monitoring for investigating the pollution of underground water with toxic molecules. The extension of this technique to the investigation of biomolecules in three different studies devoted to liver tissues analysis, bio-film formation, and cell metabolism will also be discussed. Finally we will mention the developments in the field of single-mode fibres operating around 10 mum for the Darwin space mission, which is aiming at discovering, signs of biological life in telluric earth-like exoplanets throughout the universe. PMID:18067106

  13. Feature Point Descriptors: Infrared and Visible Spectra

    OpenAIRE

    Pablo Ricaurte; Carmen Chilán; Cristhian A. Aguilera-Carrasco; Vintimilla, Boris X.; Sappa, Angel D.

    2014-01-01

    This manuscript evaluates the behavior of classical feature point descriptors when they are used in images from long-wave infrared spectral band and compare them with the results obtained in the visible spectrum. Robustness to changes in rotation, scaling, blur, and additive noise are analyzed using a state of the art framework. Experimental results using a cross-spectral outdoor image data set are presented and conclusions from these experiments are given.

  14. Si nanocrystals embedded in SiO2: Optical studies in the vacuum ultraviolet range

    DEFF Research Database (Denmark)

    Pankratov, V.; Osinniy, Viktor; Kotlov, A.; Nylandsted Larsen, Arne; Bech Nielsen, Brian

    2011-01-01

    Photoluminescence excitation and transmission spectra of Si nanocrystals of different diameters embedded in a SiO2 matrix have been investigated in the broad visible-vacuum ultraviolet spectral range using synchrotron radiation. The dependence of the photoluminescence excitation spectra on the...

  15. Dynamic range and mass accuracy of wide-scan direct infusion nanoelectrospray fourier transform ion cyclotron resonance mass spectrometry-based metabolomics increased by the spectral stitching method

    OpenAIRE

    Southam, Andrew D; Payne, Tristan G; Cooper, Helen J.; Arvanitis, Theodoros N.; Viant, Mark R.

    2007-01-01

    Direct infusion nanoelectrospray Fourier transform ion cyclotron resonance mass spectrometry (DI nESI FT-ICR MS)offers high mass accuracy and resolution for analyzing complex metabolite mixtures. High dynamic range across a wide mass range, however, can only be achieved at the expense of mass accuracy, since the large numbers of ions entering the ICR detector induce adverse spacecharge effects. Here we report an optimized strategy for wide-scan DI nESI FT-ICR MS that increases dynamic range b...

  16. Analysis of the influence of the plasma thermodynamic regime in the spectrally resolved and mean radiative opacity calculations of carbon plasmas in a wide range of density and temperature

    International Nuclear Information System (INIS)

    In this work the spectrally resolved, multigroup and mean radiative opacities of carbon plasmas are calculated for a wide range of plasma conditions which cover situations where corona, local thermodynamic and non-local thermodynamic equilibrium regimes are found. An analysis of the influence of the thermodynamic regime on these magnitudes is also carried out by means of comparisons of the results obtained from collisional-radiative, corona or Saha–Boltzmann equations. All the calculations presented in this work were performed using ABAKO/RAPCAL code. -- Highlights: ? Spectrally resolved, multigroup and mean radiative opacities of carbon plasmas are calculated. ? Corona, local thermodynamic and non-local thermodynamic equilibrium regimes are analyzed. ? Simulations performed using the computational package ABAKO/RAPCAL. ? A criterion for the establishment of the thermodynamic regime is proposed.

  17. First INTEGRAL observations of V404 Cygni during the 2015 outburst : spectral behavior in the 20 - 650 keV energy range

    CERN Document Server

    Roques, Jean-Pierre; Bazzano, Angela; Fiocchi, Mariateresa; Natalucci, Lorenzo; Ubertini, Pietro

    2015-01-01

    In June 2015, the source V404 Cygni (= GS2023+38) underwent an extraordinary outburst. We present the results obtained during the first revolution dedicated to this target by the INTEGRAL mission, and focus on the spectral behavior in the hard X-ray domain, using both SPI and IBIS instruments. The source exhibits extreme variability, and reaches fluxes of several tens of Crab. However, the emission between 20 and 650 keV can be understood in terms of two main components, varying on all the observable timescales, similar to what is observed in the persistent black hole system Cyg X-1. The low energy component (up to ~ 200 keV) presents a rather unusual shape, probably due to the intrinsic source variability. Nonetheless, a satisfactory description is obtained with a Comptonization model, if an unusually hot population of seed photons ($kT_0$ ~ 7 keV) is introduced. Above this first component, a clear excess extending up to 400-600 keV leads us to investigate a scenario where an additional (cutoff) power law co...

  18. The Visible and Near Infrared module of EChO

    CERN Document Server

    Adriani, A; Gambicorti, L; Focardi, M; Oliva, E; Farina, M; Di Giorgio, A M; Santoli, F; Pace, E; Piccioni, G; Filacchione, G; Pancrazzi, M; Tozzi, A; Micela, G

    2014-01-01

    The Visible and Near Infrared (VNIR) is one of the modules of EChO, the Exoplanets Characterization Observatory proposed to ESA for an M-class mission. EChO is aimed to observe planets while transiting by their suns. Then the instrument had to be designed to assure a high efficiency over the whole spectral range. In fact, it has to be able to observe stars with an apparent magnitude Mv= 9-12 and to see contrasts of the order of 10-4 - 10-5 necessary to reveal the characteristics of the atmospheres of the exoplanets under investigation. VNIR is a spectrometer in a cross-dispersed configuration, covering the 0.4-2.5 micron spectral range with a resolving power of about 330 and a field of view of 2 arcsec. It is functionally split into two channels respectively working in the 0.4-1 and 1.0-2.5 micron spectral ranges. Such a solution is imposed by the fact the light at short wavelengths has to be shared with the EChO Fine Guiding System (FGS) devoted to the pointing of the stars under observation. The spectromete...

  19. First INTEGRAL Observations of V404 Cygni during the 2015 Outburst: Spectral Behavior in the 20-650 keV Energy Range

    Science.gov (United States)

    Roques, Jean-Pierre; Jourdain, Elisabeth; Bazzano, Angela; Fiocchi, Mariateresa; Natalucci, Lorenzo; Ubertini, Pietro

    2015-11-01

    In 2015 June, the source V404 Cygni (= GS2023+38) underwent an extraordinary outburst. We present the results obtained during the first revolution dedicated to this target by the INTEGRAL mission and focus on the spectral behavior in the hard X-ray domain, using both SPI and IBIS instruments. The source exhibits extreme variability and reaches fluxes of several tens of Crab. However, the emission between 20 and 650 keV can be understood in terms of two main components, varying on all the observable timescales, similar to what is observed in the persistent black hole system Cyg X-1. The low-energy component (up to ˜200 keV) presents a rather unusual shape, probably due to the intrinsic source variability. Nonetheless, a satisfactory description is obtained with a Comptonization model, if an unusually hot population of seed photons (kT0 ˜ 7 keV) is introduced. Above this first component, a clear excess extending up to 400-600 keV leads us to investigate a scenario where an additional (cutoff) power law could correspond to the contribution of the jet synchrotron emission, as proposed in Cyg X-1. A search for an annihilation feature did not provide any firm detection, with an upper limit of 2 × 10-4 ph cm-2 s-1 (2?) for a narrow line centered at 511 keV, on the averaged obtained spectrum. Based on observations with INTEGRAL, an ESA project with instruments and science data center funded by ESA member states (especially the PI countries: Denmark, France, Germany, Italy, Spain, and Switzerland), Czech Republic, and Poland with the participation of Russia and USA.

  20. Visible Human Project

    Science.gov (United States)

    ... Sites Tools Media Productions Related Projects The Visible Human Project ® Overview The Visible Human Project ® is an outgrowth of the NLM's 1986 ... dimensional representations of the normal male and female human bodies. Acquisition of transverse CT, MR and cryosection ...

  1. Visible photon multiplication in Ce3+–Tb3+ doped borate glasses for enhanced solar cells

    International Nuclear Information System (INIS)

    Visible photon multiplication is exposed in the Ce3+–Tb3+ doped alkaline-earth borate (LKZBSB) glass system. Efficient green and blue fluorescences originate from Tb3+ and Ce3+ emitting centres, respectively. Evaluation of absolute spectral parameters reveals that the quantum yield of Tb3+ single doped LKZBSB glasses is ?8% under UVA radiation. Furthermore, with the introduction of Ce3+ into the Tb3+ doping system, the effective excitation wavelength range and the emission intensity of Tb3+ in LKZBSB glasses are remarkably expanded and improved by a maximum sensitization factor of ?52 in the UVB spectral region. These results demonstrate that the Ce3+–Tb3+ doped LKZBSB glass system has promising potential as an efficient UV ? Visible radiation conversion layer for the enhancement of solar cell efficiency, including cells employed in outer space. (paper)

  2. Spectral filtering for plant production

    Science.gov (United States)

    Young, Roy E.; Mcmahon, Margaret J.; Rajapakse, Nihal C.; Decoteau, Dennis R.

    1994-01-01

    Both plants and animals have one general commonality in their perception of light. They both are sensitive primarily to the 400 to 700 nm wavelength portion of the electromagnetic spectrum. This is referred to as the visible spectrum for animals and as the photosynthetically active radiation (PAR) spectrum for plants. Within this portion of the spectrum, animals perceive colors. Relatively recently it has been learned that within this same spectral range plants also demonstrate varying responses at different wavelengths, somewhat analogous to the definition of various colors at specific wavelengths. Although invisible to the human eye, portions of the electromagnetic spectrum on either side of the visible range are relatively inactive photosynthetically but have been found to influence important biological functions. These portions include the ultraviolet (UV approximately equal to 280-400 nm) and the far-red (FR approximately equal to 700-800 nm). The basic photoreceptor of plants for photosynthesis is chlorophyll. It serves to capture radiant energy which combined with carbon dioxide and water produces oxygen and assimulated carbon, used for the synthesis of cell wall polysaccarides, proteins, membrane lipids and other cellular constituents. The energy and carbon building blocks of photosynthesis sustain growth of plants. On the other hand, however, there are other photoreceptors, or pigments, that function as signal transducers to provide information that controls many physiological and morphological responses of how a plant grows. Known photomorphogenic receptors include phytochrome (the red/far-red sensor in the narrow bands of 655-665 nm and 725-735 nm ranges, respectively) and 'cryptochrome' (the hypothetical UV-B sensor in the 280-320 nm range). Since the USDA team of W. L. Butler, S. B. Hendricks, H. A. Borthwick, H. A. Siegleman and K. Norris in Beltsville, MD detected by spectroscopy, extracted and identified phytochrome as a protein in the 1950's, many other investigators have found evidence of its control functions in plants. Considerably less, however, is known about the yet non-isolated cryptochrome. The information-transferring roles of photoreceptors in plants at specific spectral ranges quite naturally stimulated plant scientists and engineers to consider physically manipulating light to achieve desired physiological and morphological characteristics. One way to manipulate light is to filter it through materials that selectively transmit portions of the sun's spectrum in and near the PAR range.

  3. A new passive polarimetric imaging system collecting polarization signatures in the visible and infrared bands

    Science.gov (United States)

    Lavigne, Daniel A.; Breton, Mélanie; Fournier, Georges; Pichette, Mario; Rivet, Vincent

    2009-05-01

    Electro-optical imaging systems are frequently employed during surveillance operations and search and rescue missions to detect various targets of interest in both the civilian and military communities. By incorporating the polarization of light as supplementary information to such electro-optical imaging systems, it may be possible to increase the target discrimination performance considering that man-made objects are known to depolarize light in different manners than natural backgrounds. Consequently, many passive Stokes-vector imagers have been developed over the years. These sensors generally operate using one single spectral band at a time, which limits considerably the polarization information collected across a scene over a predefined specific spectral range. In order to improve the understanding of the phenomena that arise in polarimetric signatures of man-made targets, a new passive polarimetric imaging system was developed at Defence Research and Development Canada - Valcartier to collect polarization signatures over an extended spectral coverage. The Visible Infrared Passive Spectral Polarimetric Imager for Contrast Enhancement (VIP SPICE) operates four broad-band cameras concomitantly in the visible (VIS), the shortwave infrared (SWIR), the midwave infrared (MWIR), and the longwave infrared (LWIR) bands. The sensor is made of four synchronously-rotating polarizers mounted in front of each of the four cameras. Polarimetric signatures of man-made objects were acquired at various polarization angles in the four spectral bands. Preliminary results demonstrate the utility of the sensor to collect significant polarimetric signatures to discriminate man-made objects from their background.

  4. A Visible, Spatially-Modulated Imaging Fourier Transform Spectrometer (SMIFTS) for Astronomical Applications

    Science.gov (United States)

    Rafert, J. B.; Holbert, E. T.; Rusk, E. T.; Durham, S. E.; Caudill, E.; Keating, D.; Newby, H.

    1992-12-01

    We have constructed several visible, Spatially-Modulated Imaging Fourier Transform Spectrometers (SMIFTS) for spatially resolved spectral imaging in the visible wavelength region based on work by several authors including Yoshihara and Kitade (1967), Okamoto et al. (1984), Barnes (1985) and Smith and Schempp (1991). Our spectrometers require no moving parts, are compact and enjoy a number of advantages over the other spectral data collection technologies. The unique combination of characteristics define an important niche for astronomical, remote sensing, and reconnaissance spectral data acquisition. Our SMIFTS simultaneously acquires hundreds or thousands of spectral bands for hundreds or thousands of spectral channesl. This type of sensor has been called a "hyperspectral" sensor to emphasize the major quantitative difference between this type of sensor and multispectral imagers which collect only a few spectral bands. The SMIFTS consists of input optics (a telescope), a field limiting aperture, a beamsplitter which divides the input beam into two paths, two mirrors which redirect the split beams through the same path, a collimating lens which forms the interferogram of the input aperture on the detector plane, and a cylindrical imaging lens. Thus on the detector array one axis contains spatial information and the other axis contains the spectral information for each point of the spatial axis. The result of this arrangement is that each row of the detector array contains the interferogram of the corresponding point on the aperture or slit. This slit can be fixed upon the target, or the slit can be scanned across the target to build up a second axis of spatial information resulting in a data set with four dimensions: two spatial, one spectral, and one temporal. We present sample data for both astronomical and remote sensing applications taken with the Malabar SMIFTS. Barnes, T.H. "Photodiode Array Fourier Transform Spectrometer with Improved Dynamic Range", Appl. Opt, 24, 3702, (1985)

  5. Spectral properties of vaguely elliptic pseudodifferential operators with momentum-dependent long-range potentials using time-dependent scattering theory

    Science.gov (United States)

    Muthuramalingam, Pl.

    1984-06-01

    (a) Absence of singular continuous spectrum for H and unitary equivalence of h0(P) with the absolutely continuous part of H is proved for the self-adjoint operator H=h0(P)+WS(Q, P) +WL(Q, P) on L2(Rn), where (i) h0 is a smooth, nonnegative, real valued function on Rn of at most polynomial growth with h0(?)=?, (ii) the critical values of h0 has a countable closure, (iii) the symbol WS(x, ?) is a smooth function of at most polynomial growth in ? and is of short range in x, and (iv) WL(x, ?) is a smooth real-valued function of x, ? with at most a polynomial growth in ? and O(||x||-?) at ? for some ?>0. Further we have (b) essential spectra of H and h0(P) are equal and (c) eigenvalues of H can accumulate only at the critical values of h0.

  6. Recoupled long-range C-H dipolar dephasing in solid-state NMR, and its use for spectral selection of fused aromatic rings.

    Science.gov (United States)

    Mao, J-D; Schmidt-Rohr, K

    2003-05-01

    This work introduces a simple new solid-state 13C NMR method for distinguishing various types of aromatic residues, e.g. those of lignin from fused rings of charcoal. It is based on long-range dipolar dephasing, which is achieved by recoupling of long-range C-H dipolar interactions, using two 1H 180 degrees pulses per rotation period. This speeds up dephasing of unprotonated carbon signals approximately threefold compared to standard dipolar dephasing without recoupling and thus provides much more efficient differential dephasing. It also reduces the effects of spinning-speed dependent effective proton-proton dipolar couplings on the heteronuclear dephasing. Signals of unprotonated carbons with two or more protons at a two-bond distance dephase to dephasing among different unprotonated carbons is demonstrated in a substituted anthraquinone and 3-methoxy benzamide. The data yield a calibration curve for converting the dephasing rates into estimated distances from the carbon to the nearest protons. This can be used for peak assignment in heavily substituted or fused aromatic molecules. Compared to lignin, slow dephasing is observed for the aromatic carbons in wood charcoal, and even slower for inorganic carbonate. Direct 13C polarization is used on these structurally complex samples to prevent loss of the signals of interest, which by design originate from carbons that are distant from protons and therefore crosspolarize poorly. In natural organic matter such as humic acids, this combination of recoupled dipolar dephasing and direct polarization at 7-kHz MAS enables selective observation of signals from fused rings that are characteristic of charcoal. PMID:12762998

  7. USGS Digital Spectral Library splib06a

    Science.gov (United States)

    Clark, Roger N.; Swayze, Gregg A.; Wise, Richard A.; Livo, K. Eric; Hoefen, Todd M.; Kokaly, Raymond F.; Sutley, Stephen J.

    2007-01-01

    Introduction We have assembled a digital reflectance spectral library that covers the wavelength range from the ultraviolet to far infrared along with sample documentation. The library includes samples of minerals, rocks, soils, physically constructed as well as mathematically computed mixtures, plants, vegetation communities, microorganisms, and man-made materials. The samples and spectra collected were assembled for the purpose of using spectral features for the remote detection of these and similar materials. Analysis of spectroscopic data from laboratory, aircraft, and spacecraft instrumentation requires a knowledge base. The spectral library discussed here forms a knowledge base for the spectroscopy of minerals and related materials of importance to a variety of research programs being conducted at the U.S. Geological Survey. Much of this library grew out of the need for spectra to support imaging spectroscopy studies of the Earth and planets. Imaging spectrometers, such as the National Aeronautics and Space Administration (NASA) Airborne Visible/Infra Red Imaging Spectrometer (AVIRIS) or the NASA Cassini Visual and Infrared Mapping Spectrometer (VIMS) which is currently orbiting Saturn, have narrow bandwidths in many contiguous spectral channels that permit accurate definition of absorption features in spectra from a variety of materials. Identification of materials from such data requires a comprehensive spectral library of minerals, vegetation, man-made materials, and other subjects in the scene. Our research involves the use of the spectral library to identify the components in a spectrum of an unknown. Therefore, the quality of the library must be very good. However, the quality required in a spectral library to successfully perform an investigation depends on the scientific questions to be answered and the type of algorithms to be used. For example, to map a mineral using imaging spectroscopy and the mapping algorithm of Clark and others (1990a, 2003b), one simply needs a diagnostic absorption band. The mapping system uses continuum-removed reference spectral features fitted to features in observed spectra. Spectral features for such algorithms can be obtained from a spectrum of a sample containing large amounts of contaminants, including those that add other spectral features, as long as the shape of the diagnostic feature of interest is not modified. If, however, the data are needed for radiative transfer models to derive mineral abundances from reflectance spectra, then completely uncontaminated spectra are required. This library contains spectra that span a range of quality, with purity indicators to flag spectra for (or against) particular uses. Acquiring spectral measurements and performing sample characterizations for this library has taken about 15 person-years of effort. Software to manage the library and provide scientific analysis capability is provided (Clark, 1980, 1993). A personal computer (PC) reader for the library is also available (Livo and others, 1993). The program reads specpr binary files (Clark, 1980, 1993) and plots spectra. Another program that reads the specpr format is written in IDL (Kokaly, 2005). In our view, an ideal spectral library consists of samples covering a very wide range of materials, has large wavelength range with very high precision, and has enough sample analyses and documentation to establish the quality of the spectra. Time and available resources limit what can be achieved. Ideally, for each mineral, the sample analysis would include X-ray diffraction (XRD), electron microprobe (EM) or X-ray fluorescence (XRF), and petrographic microscopic analyses. For some minerals, such as iron oxides, additional analyses such as Mossbauer would be helpful. We have found that to make the basic spectral measurements, provide XRD, EM or XRF analyses, and microscopic analyses, document the results, and complete an entry of one spectral library sample, all takes about

  8. An analysis of visibility-based continuum subtraction.

    Science.gov (United States)

    Sault, R. J.

    1994-10-01

    Continuum emission is often a viewed as a contaminant in radio interferometric spectral-line imaging. At best, it makes the analysis of the spectral-line images difficult. At worst, it limits the dynamic range of the images. In recent papers, van Langevelde & Cotton (1990) introduced a visibility-based continuum subtraction technique to radio interferometry, and Cornwell et al. (1992) analysed its properties. The technique is based on modelling the continuum by a first-order polynomial in the visibility spectrum. We present a quantitative analysis of the technique, both in terms of the residual continuum and the sensitivity to noise. The analysis is for polynomial fits of arbitrary order. A less complete analysis of a related, image-based, continuum subtraction technique is also presented. We show that higher order polynomials can be useful for data with large field size and bandwidth, and that stability in the presence of noise is not a problem. Some errors in the papers cited above are corrected.

  9. Visibly Pushdown Automata

    DEFF Research Database (Denmark)

    Srba, Jiri

    2006-01-01

    We investigate the possibility of (bi)simulation-like preorder/equivalence checking on the class of visibly pushdown automata and its natural subclasses visibly BPA (Basic Process Algebra) and visibly one-counter automata. We describe generic methods for proving complexity upper and lower bounds for a number of studied preorders and equivalences like simulation, completed simulation, ready simulation, 2-nested simulation preorders/equivalences and bisimulation equivalence. Our main results are t...

  10. Spectral calibration for deriving surface mineralogy of Asteroid (25143) Itokawa from Hayabusa Near-Infrared Spectrometer (NIRS) Data

    CERN Document Server

    Bhatt, Megha; Corre, Lucille Le; Sanchez, Juan A; Dunn, Tasha; Izawa, Matthew R M; Li, Jian-Yang; Becker, Kris J; Weller, Lynn

    2015-01-01

    We present spectral calibration equations for determining mafic silicate composition of near-Earth asteroid (25143) Itokawa from visible/near-infrared spectra measured using the Near Infrared Spectrometer (NIRS), on board the Japanese Hayabusa spacecraft. Itokawa was the target of the Hayabusa sample return mission and has a surface composition similar to LL-type ordinary chondrites. Existing laboratory spectral calibrations use a spectral wavelength range that is wider (0.75-2.5 microns) than that of the NIRS instrument (0.85-2.1 microns) making them unfit for interpreting the Hayabusa spectral data currently archived in the Planetary Data System. We used laboratory measured near-infrared reflectance spectra of ordinary (H, L and LL) chondrites from the study of Dunn et al. (2010), which we resampled to the NIRS wavelength range. Using spectral parameters extracted from these resampled spectra we established a relationship between band parameters and their mafic silicate composition (olivine and low-Ca pyrox...

  11. Spectral Methods

    CERN Document Server

    Shen, Jie; Wang, Li-Lian

    2011-01-01

    Along with finite differences and finite elements, spectral methods are one of the three main methodologies for solving partial differential equations on computers. This book provides a detailed presentation of basic spectral algorithms, as well as a systematical presentation of basic convergence theory and error analysis for spectral methods. Readers of this book will be exposed to a unified framework for designing and analyzing spectral algorithms for a variety of problems, including in particular high-order differential equations and problems in unbounded domains. The book contains a large

  12. Dielectric function in the spectral range (0.5–8.5)eV of an (Al{sub x}Ga{sub 1?x}){sub 2}O{sub 3} thin film with continuous composition spread

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt-Grund, R., E-mail: Schmidt-Grund@physik.uni-leipzig.de; Kranert, C.; Wenckstern, H. von; Zviagin, V.; Lorenz, M.; Grundmann, M. [Fakultät für Physik und Geowissenschaften, Institut für Experimentelle Physik II, Universität Leipzig, Linnéstr. 5, D-04103 Leipzig (Germany)

    2015-04-28

    We determined the dielectric function of the alloy system (Al{sub x}Ga{sub 1?x}){sub 2}O{sub 3} by spectroscopic ellipsometry in the wide spectral range from 0.5?eV to 8.5?eV and for Al contents ranging from x?=?0.11 to x?=?0.55. For the composition range x?

  13. Visible and UV emission spectroscopy

    International Nuclear Information System (INIS)

    Visible and ultra-violet emission spectroscopy is a well established plasma diagnostic technique extensively used in contemporary fusion experiments. Theoretical plasma models are required to derive the relevant physical parameters. These models are reviewed in the first part of this paper. They allow spectral line intensities and radiative power losses to be calculated from the knowledge of the detailed atomic physics processes occurring in the plasma. In tokamak plasma experiments, impurity contamination and transport are important concerns. Basic spectroscopic methods used in their understanding are described. They include the determination of impurity concentrations either by line emission modelling (through the use of an impurity transport code), or by direct charge-exchange recombination measurement. They also include the evaluation of neutral particle fluxes at the plasma periphery. Finally, the experimental techniques used in the derivation of impurity transport coefficients are reported

  14. Spectral imager based on Fabry-Perot interferometer for Aalto-1 nanosatellite

    Science.gov (United States)

    Mannila, Rami; Näsilä, Antti; Viherkanto, Kai; Holmlund, Christer; Näkki, Ismo; Saari, Heikki

    2013-09-01

    The Aalto-1 is a 3U-cubesat project coordinated by Aalto University. The satellite, Aalto-1, will be mainly built by students as project assignments and thesis works. The Aalto-1 is planned to launch on 2014. VTT Technical Research Centre of Finland is developing the main Earth observation payload, a miniaturized spectral imager unit, for the satellite. The spectral imager unit contains a spectral imager, a visible RGB-camera and control electronics of the cameras. Detailed design of the spectral imager unit has been completed and assembly of the spectral imager unit will be done in the autumn 2013. The spectral imager is based on a tunable Fabry-Perot interferometer (FPI) accompanied by an RGB CMOS image sensor. The FPI consists of two highly reflective surfaces separated by a tunable air gap and it is based on a piezo-actuated structure. The piezo-actuated FPI uses three piezo-actuators and is controlled in a closed capacitive feedback loop. The spectral resolution of the imager will be 8-15 nm at full width at half maximum and it will operate in the wavelength range 500-900 nm. Imaging resolution of the spectral imager is 1024x1024 pixels and the focal length of the optics is 32 mm and F-number is 3.4. Mass of the spectral imager unit is approximately 600 grams, and dimensions are 97 mm x 97 mm x 48 mm.

  15. Spectral characterisation and discrimination of burnt areas

    OpenAIRE

    Pereira, José; Sá, Ana; Sousa, Adélia; Santos, Teresa; Carreiras, João

    1999-01-01

    Spectral properties of recent burns charaterised, in the visible, near infrared, mid-infrared, thermal infrared, and microwave spectral domains. Fire-induced reflectance changes are also compared for varios ecosystems and biomes, and discussed in terms of the cological effects of phytomass combustion. The spectral signaturess of combustion products and of burnt areas are compared with those of various plant material and land cover types, in order to graphically represent relevant aspects of b...

  16. Spectral properties of optical anisotropy induced by laser radiation in dye solutions

    International Nuclear Information System (INIS)

    Spectral studies of induced quasi-crystal properties (which can be quantitatively characterised by the difference in the refractive indices of ordinary and extraordinary waves, Δn=no-ne) in Rhodamine 6G and Rhodamine 4C solutions in glycerine excited in the visible and UV ranges of the absorption spectrum are presented. It is demonstrated that the observed spectral dependences of Δn of these dye solutions excited in the visible (long-wavelength) and UV (short-wavelength) ranges of the absorption spectrum can be interpreted in terms of an oscillator model of a molecule. The proposed method for the analysis of induced optical anisotropy in solutions of organic compounds allows the relative orientation of oscillators in a molecule and, thus, the relative orientation of electronic transitions in a molecule to be determined in a reliable way. (iv international conference on atom and molecular pulsed lasers (ampl'99))

  17. Spectral networks

    CERN Document Server

    Gaiotto, Davide; Neitzke, Andrew

    2012-01-01

    We introduce new geometric objects called spectral networks. Spectral networks are networks of trajectories on Riemann surfaces obeying certain local rules. Spectral networks arise naturally in four-dimensional N=2 theories coupled to surface defects, particularly the theories of class S. In these theories spectral networks provide a useful tool for the computation of BPS degeneracies: the network directly determines the degeneracies of solitons living on the surface defect, which in turn determine the degeneracies for particles living in the 4d bulk. Spectral networks also lead to a new map between flat GL(K,C) connections on a two-dimensional surface C and flat abelian connections on an appropriate branched cover Sigma of C. This construction produces natural coordinate systems on moduli spaces of flat GL(K,C) connections on C, which we conjecture are cluster coordinate systems.

  18. Miniaturized spectral imager for Aalto-1 nanosatellite

    Science.gov (United States)

    Mannila, Rami; Näsilä, Antti; Praks, Jaan; Saari, Heikki; Antila, Jarkko

    2011-11-01

    The Aalto-1 is a 3U-cubesat project coordinated by Aalto University. The satellite, Aalto-1, will be mainly built by students as project assignments and thesis works. VTT Technical Research Centre of Finland will develop the main Earth observation payload, a miniaturized spectral imager, for the satellite. It is a novel highly miniaturized tunable filter type spectral imager. Mass of the spectral imager will be less than 400 grams, and dimensions will be approximately 80 mm x 80 mm x 45 mm. The spectral imager is based on a tunable Fabry-Pérot interferometer (FPI) accompanied by an RGB CMOS image sensor. The FPI consists of two highly reflective surfaces separated by a tunable air gap and it is based either on a microelectromechanical (MEMS) or piezo-actuated structure. The MEMS FPI is a monolithic device, i.e. it is made entirely on one substrate in a batch process, without assembling separate pieces together. The gap is adjusted by moving the upper mirror with electrostatic force. Benefits of the MEMS FPI are low mass and small size. However, large aperture (2-10 mm) MEMS FPIs are currently under development, thus it is not yet known if their performance is adequate. The piezo-actuated FPI uses three piezo-actuators and is controlled in a closed capacitive feedback loop. The drawback of the piezo-actuated FPI is its higher mass. However, it has a large aperture which enables a shorter exposure times. Selection of the FPI type will be done after thorough evaluation. Depending on the selected FPI type, the spectral resolution of the imager will be 5 - 10 nm at full width at half maximum and it will operate in the visible and/or near infrared range.

  19. All-fiber femtosecond Cherenkov laser at visible wavelengths

    DEFF Research Database (Denmark)

    Liu, Xiaomin; Lægsgaard, Jesper

    2013-01-01

    Fiber-optic Cherenkov radiation (CR), also known as dispersive wave generation or non-solitonic radiation, is produced in small-core photonic crystal fibers (PCF) when a soliton perturbed by fiber higher-order dispersion co-propagates with a dispersive wave fulfilling a certain phase-matching condition [1]. The resonant ultrafast wave conversion via the fiber-optic CR mechanism is instrumental for applications in biophotonics such as bio-imaging and microscopy [2]. In this work, we demonstrate a highly-stable all-fiber, fully monolithic CR system based on an Yb-fiber femtosecond laser, producing electrically tunable femtosecond CR output in the visible (VIS) spectral range of 580-630 nm, with the 3 dB spectral bandwidth not exceeding 36 nm, with average power in the milliwatt range. Relative intensity noise (RIN) of this laser, affecting the sensitivity of bio-imaging and microscopy systems, is found to be as low as -103 dBc/Hz. This is 2 orders of magnitudes lower noise as compared to spectrally-sliced supercontinuum, which is the current standard of ultrafast fiber-optic generation at visible wavelength. The layout of the laser system is shown in Fig. 1(a). The system consists of two parts: an all-fiber selfstabilized Yb-doped femtosecond laser [3,4] operating at 1035 nm central wavelength and 26.7 MHz repetition rate used as the pump source; and a spliced-on small-core nonlinear PCF NL-3.0-850 (NKT Photonics A/S) with zero-dispersion wavelength around 850 nm, used for Cherenkov wave conversion [5]. Bridge fibers are used in the CR link to enhance the conversion efficiency. Fig. 1(b) shows the far-field saturated visible images of the CR emitted from the laser system, generated as the pump power increases in the range 150 mW - 300 mW. The emitted CR spectra corresponding to different average output powers are shown in Fig. 1(c). When the average emitted CR power is increasing from 0.46 mW to 4.2 mW, the central wavelength is shifting from 630 nm to 580 nm, and the 3 dB bandwidth of the spectrum increases from14 nm to 36 nm. The physical mechanism of wavelength tunability with changing the pump power is related to different linear and nonlinear compression conditions for weaker and stronger pump laser pulses in the hollow-core pulse compressor and CR stages of the laser (Fig. 1(a)). Fig. 1 (d) shows the autocorrelation (AC) of the CR with the output power of 1.7 mW. The FWHM of the AC trace for the generated CR pulse is 160 fs. The FWHM of the AC of the input pump pulse at 1035 nm is 832 fs. The CR pulse is more than 5 times shorter than the pump pulse, as a result of the nonlinear pump pulse compression in the CR fiber link. We are currently working on achieving an even broader electrical tunability of the CR output, ideally covering the significant part of the visible spectral range.

  20. Strong Ionic Hydrogen Bonding Causes a Spectral Isotope Effect in Photoactive Yellow Protein

    OpenAIRE

    Kaledhonkar, Sandip; Hara, Miwa; Stalcup, T. Page; Xie, Aihua; Hoff, Wouter D.

    2013-01-01

    Standard hydrogen bonds are of great importance for protein structure and function. Ionic hydrogen bonds often are significantly stronger than standard hydrogen bonds and exhibit unique properties, but their role in proteins is not well understood. We report that hydrogen/deuterium exchange causes a redshift in the visible absorbance spectrum of photoactive yellow protein (PYP). We expand the range of interpretable isotope effects by assigning this spectral isotope effect (SIE) to a functiona...

  1. Visible Human Project®

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Visible Human Project® is the creation of complete, anatomically detailed, three-dimensional representations of the normal male and female human bodies....

  2. SPECTRAL CHARACTERISTICS OF SELECTED HERMATYPIC CORALS FROM GULF OF KACHCHH, INDIA

    Directory of Open Access Journals (Sweden)

    N. Ray Chaudhury

    2012-07-01

    Full Text Available Hermatypic, scleractinian corals are the most important benthic substrates in a coral reef ecosystem. The existing, high (spatial resolution, broad-band, multi-spectral, space-borne sensors have limited capability to spatially detect and spectrally discriminate coral substrates. In situ hyperspectral signatures of eight coral targets were collected with the help of Analytical Spectral Devices FieldSpec spectroradiometer from Paga and Laku Point reefs of Gulf of Kachchh, India to study the spectral behaviour of corals. The eight coral targets consisted of seven live corals representing four distinct colony morphologies and one bleached coral target. The coral spectra were studied over a continuous range of 350 to 1350 nm. The corals strongly reflected in the NIR and MIR regions with regional central maximas located at 820 and 1070 nm respectively. In the visible region the live coral spectra conformed to "brown mode" of coral reflectance with triple-peaked pattern at 575, 600 and 650 nm. All coral spectra are characterized with two distinct absorption features: chlorophyll absorption at 675 nm and water absorption at 975 nm. The live and the bleached corals get distinguished in the visible region over 400 to 600 nm region. Water column over the targets modifies the spectral shape and magnitude. First and second-order derivatives help in identifying spectral windows to distinguish live and bleached corals.

  3. Ultraviolet and visible imaging and spectrographic imaging (UVISI) experiment

    International Nuclear Information System (INIS)

    The Ultraviolet and Visible Imaging and Spectrographic Imaging (UVISI) experiment consists of five spectrographic imagers and four imagers. These nine sensors provide spectrographic and imaging capabilities from ?110 nm to ?900 nm. The spectrographic imagers (SPIMs) share an off-axis parabolic design in which selectable slits (1.00 degree x0.10 degree or 1.00 degree x0.05 degree) provide spectral resolutions between ?0.5 nm and ?4.0 nm. SPIM image planes have programmable spectral dimensions with 68, 136 or 272 pixels and programmable spatial dimensions with 5, 10, 20, or 40 pixels. A scan mirror sweeps the slit through a second spatial dimension and generates a spectrographic image once every 5, 10, or 20 seconds. The four imagers provide narrow-field (1.3 degree x1.6 degree) and wide-field (13.1 degree x10.5 degree) viewing. Each imager has a six-position filter wheel that selects various spectral regimes and neutral densities. Each of the nine sensors use intensified CCD detectors that have an intrascene dynamic range of ?103 and an interscene dynamic range of ?105; neutral density filters provide and additional dynamic range of ?102-3. An automatic gain control adjusts the intensifiers to scenes of varying intensity. UVISI also includes an image processing system that uses the raw data from any single imager to acquire and track targets of various sizes, shapes, and brightnesses. The image processor relays its results to a master tracking system that uses the UVISI data (as well as other data) to point the satellite in real-time. UVISI will be launched on the MSX satellite in late 1994 and will investigate a multitude of celestial, atmospheric, and point sources during its planned five-year lifetime

  4. The visible and near infrared module of EChO

    Science.gov (United States)

    Adriani, A.; Bellucci, G.; Gambicorti, L.; Focardi, M.; Oliva, E.; Farina, M.; Di Giorgio, A. M.; Santoli, F.; Pace, E.; Piccioni, G.; Filacchione, G.; Pancrazzi, M.; Tozzi, A.; Micela, G.

    2015-12-01

    The Visible and Near Infrared (VNIR) is one of the modules of EChO, the Exoplanets Characterization Observatory proposed to ESA for an M-class mission. EChO is aimed to observe planets while transiting by their suns. Then the instrument had to be designed to assure a high efficiency over the whole spectral range. In fact, it has to be able to observe stars with an apparent magnitude Mv = 9-12 and to see contrasts of the order of 10-4-10-5 necessary to reveal the characteristics of the atmospheres of the exoplanets under investigation. VNIR is a spectrometer in a cross-dispersed configuration, covering the 0.4-2.5 μm spectral range with a resolving power of about 330 and a field of view of 2 arcsec. It is functionally split into two channels respectively working in the 0.4-1.0 μm and 1.0-2.5 μm spectral ranges. Such a solution is imposed by the fact the light at short wavelengths has to be shared with the EChO Fine Guiding System (FGS) devoted to the pointing of the stars under observation. The spectrometer makes use of a HgCdTe detector of 512 by 512 pixels, 18 μm pitch and working at a temperature of 45 K as the entire VNIR optical bench. The instrument has been interfaced to the telescope optics by two optical fibers, one per channel, to assure an easier coupling and an easier colocation of the instrument inside the EChO optical bench.

  5. Spectral curves of surface reflectance in some Antarctic regions

    International Nuclear Information System (INIS)

    Four surface reflectance models of solar radiation were determined by examining several sets of field measurements taken for clear-sky conditions at various sites in Antarctica. Each model consists of the mean spectral curve of surface reflectance in the 0.25-2.7 ?m wavelength range and of the dependence curve of total abedo on the solar elevation angle h, within the range from 50 to 550. The TNB (Terra Nova Bay) model refers to a rocky terrain where granites are predominant; the NIS (Nansen Ice Sheet) model to a glacier surface made uneven by sastrugi and streaked by irregular fractures; the HAP (High Altitude Plateau) model to a flat ice surface covered by fresh snow and scored by light sastrugi; and the RIS (Ross Ice Shelf) model to an area covered by the sea ice pack presenting many discontinuities in the reflectance features, due to melt water lakes, puddles, refrozen ice and snow pots. The reflectance curve obtained for the TNB model presents gradually increasing values as wavelength increases through the visible spectral range and almost constant values at infrared wavelengths, giving a total albedo value equal to 0.264 at = 300, which increases by about 80% through the lower range of h and decreases by 12% through the upper range. The reflectance curves of the NIS, HAP and RIS models are all peaked at visible wavelengths and exhibit decreasing values throughout the infrared spectral range, giving values of total albedo equal to 0.464, 0.738 and 0.426 at h 300, respectively. These values were estimated to increase by 8-14% as h decreases from 300 to 50 and to decrease by 2-4% only as h increases from 300 to 550

  6. [Design of full-polarized and multi-spectral imaging system based on LCVR].

    Science.gov (United States)

    Zhang, Ying; Zhao, Hui-jie; Cheng, Xuan; Xiong, Sheng-jun

    2011-05-01

    A new full-polarized multi-spectral imaging system is described, which uses electronically controlled LCVR (liquid crystal variable retarder) to modulate the full-polarized state of light in the visible to IR range. The system consisted of optical lenses, LCVRs, filters and CCD. Firstly, the system structure, working theory and optical design are introduced in the present paper. A polarization calibration method is provided and the calibration system was set up, which realized high-precision polarization calibration using a small polarized source. Then, a field experiment with the imaging system was carried out. Polarized spectral images with higher spectral and spatial resolution were collected. Finally, the data acquired were rough processed to get polarization degree image of the targets. It is concluded that the experiment has proved that the imaging system is effective in obtaining full-polarized and multi- spectral data. The image captured by the system can be applied to object identification and object classification. PMID:21800604

  7. Spectral Analysis

    CERN Document Server

    Cecconi, Jaures

    2011-01-01

    G. Bottaro: Quelques resultats d'analyse spectrale pour des operateurs differentiels a coefficients constants sur des domaines non bornes.- L. Garding: Eigenfuction expansions.- C. Goulaouic: Valeurs propres de problemes aux limites irreguliers: applications.- G. Grubb: Essential spectra of elliptic systems on compact manifolds.- J.Cl. Guillot: Quelques resultats recents en Scattering.- N. Schechter: Theory of perturbations of partial differential operators.- C.H. Wilcox: Spectral analysis of the Laplacian with a discontinuous coefficient.

  8. Biologically-inspired empirical mode decomposition fusion of visible and infrared images

    Science.gov (United States)

    Sissinto, Paterne Sena

    Visible and infrared image fusion technology effectively enhances image information content and rendering quality. They are many image fusion approaches that can be utilized to produce high quality fused images. Outdoor scenes exhibit no linearity, are random, and their images have independently distributed pixel colors. Many of the existing image fusion methods including but not limited to, Principal Component Analysis, Wavelet Transform based, make assumption of both image content linearity and dependent distribution and when applied to grayscale fusion. Empirical Mode Decomposition (EMD) represents input images as Instrinsic Mode Functions (IMFs) carrying their spatial and frequency components about each pixel with no a priori assumption. Visible and infrared signals lay in different spectrum ranges. Spectral emissivity and reflectivity, depending on wavelength, special contrast can be enhanced not only in visible video but also in infrared imagery. This work proposed a biologically-inspired fusion of visible and infrared images based on EMD and opponent processing (Bio-EMD). First, registered visible and infrared captures of the same scene are decomposed into Intrinsic Mode Functions through EMD. Then, the fused image is generated by opponent processing the source IMFs. Finally, the results are evaluated based on the amount on information transferred, the clarity of details, vividness of depictions, and range of meaning differences in lightness and chromaticity. Perceptual comparison of the results showed that opponent-processing-based techniques outperformed algorithms based on intensities, and some other techniques. Quantitative assessment confirmed that the proposed technique transferred twice information as much as the state-of-the-art methods did. Bio-EMD provided a high level sharpness, yielded more natural-looking colors, and produced a high magnitude of visually meaningful differences in lightness and chromaticity for the fusion of low-light visible and infrared images. These results were obtained without optimization of filters involved in the process.

  9. Two-dimensional material-based saturable absorbers: towards compact visible-wavelength all-fiber pulsed lasers

    Science.gov (United States)

    Luo, Zhengqian; Wu, Duanduan; Xu, Bin; Xu, Huiying; Cai, Zhiping; Peng, Jian; Weng, Jian; Xu, Shuo; Zhu, Chunhui; Wang, Fengqiu; Sun, Zhipei; Zhang, Han

    2015-12-01

    Passive Q-switching or mode-locking by placing a saturable absorber inside the laser cavity is one of the most effective and popular techniques for pulse generation. However, most of the current saturable absorbers cannot work well in the visible spectral region, which seriously impedes the progress of passively Q-switched/mode-locked visible pulsed fibre lasers. Here, we report a kind of visible saturable absorber--two-dimensional transition-metal dichalcogenides (TMDs, e.g. WS2, MoS2, MoSe2), and successfully demonstrate compact red-light Q-switched praseodymium (Pr3+)-doped all-fibre lasers. The passive Q-switching operation at 635 nm generates stable laser pulses with ~200 ns pulse duration, 28.7 nJ pulse energy and repetition rate from 232 to 512 kHz. This achievement is attributed to the ultrafast saturable absorption of these layered TMDs in the visible region, as well as the compact and all-fibre laser-cavity design by coating a dielectric mirror on the fibre end facet. This work may open a new route for next-generation high-performance pulsed laser sources in the visible (even ultraviolet) range.Passive Q-switching or mode-locking by placing a saturable absorber inside the laser cavity is one of the most effective and popular techniques for pulse generation. However, most of the current saturable absorbers cannot work well in the visible spectral region, which seriously impedes the progress of passively Q-switched/mode-locked visible pulsed fibre lasers. Here, we report a kind of visible saturable absorber--two-dimensional transition-metal dichalcogenides (TMDs, e.g. WS2, MoS2, MoSe2), and successfully demonstrate compact red-light Q-switched praseodymium (Pr3+)-doped all-fibre lasers. The passive Q-switching operation at 635 nm generates stable laser pulses with ~200 ns pulse duration, 28.7 nJ pulse energy and repetition rate from 232 to 512 kHz. This achievement is attributed to the ultrafast saturable absorption of these layered TMDs in the visible region, as well as the compact and all-fibre laser-cavity design by coating a dielectric mirror on the fibre end facet. This work may open a new route for next-generation high-performance pulsed laser sources in the visible (even ultraviolet) range. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06981e

  10. Visible photoluminescence of nanopowder of silicon, produced by silicon evaporation by powerful electron beam

    International Nuclear Information System (INIS)

    The silicon nanopowders, formed by the silicon massive sample evaporation by the electron beam in the argon atmosphere, are studied through the methods of the photoluminescence (PL) and combination light scattering (CS). The PL peak is identified at the room temperature in the visible spectral range of the powders, consisting of the silicon nanocrystals. The PL peak strong short-wave shift may be explained as the effect of the electrons and holes dimensional quantization in the silicon small-size (about 2 nm) nanocrystals. The silicon nanocrystals dimensions are determined through the analytical data on the CS photoluminescence and they coincided with the evaluations based on the photoluminescence data

  11. Visible Light Emission from Atomic Scale Patterns Fabricated by the Scanning Tunneling Microscope

    DEFF Research Database (Denmark)

    Thirstrup, C.; Sakurai, M.; Stokbro, Kurt; Aono, M.

    1999-01-01

    Scanning tunneling microscope (STM) induced light emission from artificial atomic scale structures comprising silicon dangling bonds on hydrogen-terminated Si(001) surfaces has been mapped spatially and analyzed spectroscopically in the visible spectral range. The light emission is based on a novel...... mechanism involving optical transitions between a tip state and localized states on the sample surface. The wavelength of the photons can be changed by the bias voltage of the STM. The spatial resolution of the photon maps is as good as that of STM topographic images and the photons are emitted from a...

  12. Comportamento espectral de folhas de Eucalyptus globulus (Labill.) atacadas por Mycosphaerella spp. nas regiões do visível e do infravermelho próximo do espectro eletromagnético / Spectral behavior of Eucalyptus globulus (Labill.) leaves attacked by Mycosphaerella spp. in regions of visible and infrared near the electromagnetic spectrum

    Scientific Electronic Library Online (English)

    Diogo Belmonte, Lippert; Ana Caroline Paim, Benedetti; Marlove Fatima Brião, Muniz; Rudiney Soares, Pereira; Carlos Alberto, Biernaski Junior; Elder, Finkenauer; Elias Fernando, Berra.

    2015-03-01

    Full Text Available O trabalho tem como objetivo analisar o comportamento espectral de folhas de Eucalyptus globulus atacadas em quatro diferentes níveis de severidade pelo fungo Mycosphaerella spp. em diferentes posições na copa da árvore, nas quatro estações climáticas, considerando duas regiões do espectro eletromag [...] nético: visível e infravermelho próximo. Foram realizadas coletas de material vegetativo em todas as estações climáticas, em diferentes posições na árvore (base, meio e extrato superior da copa). Em laboratório, as folhas foram classificadas em quatro níveis de severidade (sadio, pouco, medianamente e muito atacado) e posteriormente efetuadas as medidas de reflectância espectral com auxílio de um espectrorradiômetro. O comportamento espectral das folhas de Eucalyptus globulus é característico de acordo com o nível de severidade da doença, diferindo dos demais principalmente em altos níveis de infecção por Mycosphaerella spp. e diferenciam-se principalmente de folhas sadias e de folhas pouco atacadas, em ambas as regiões do espectro eletromagnético, esse comportamento ocorre para as diferentes posições da copa e estações climáticas variando a quantidade de energia refletida. Conclui-se que a reflectância das folhas de Eucalyptus globulus atacadas por Mycosphaerella spp. difere de acordo com a posição na copa da árvore e a estação climática em que foram coletadas e níveis avançados da severidade da doença. Abstract in english The study aims to analyze the spectral behavior of leaves of Eucalyptus globulus attacked in four different severity levels by Mycosphaerella spp. in different positions in the canopy of the tree in the four seasons, considering two regions of the electromagnetic spectrum: visible and near infrared. [...] The plant material was collected in all seasons, in different positions in the tree (base, middle and top of the canopy extract). In the laboratory, leaves were classified into four levels of severity (healthy, little, medium and heavy fire) and then made ??measurements of spectral reflectance measured with a spectroradiometer. The spectral behavior of Eucalyptus globules leaves is characteristic according to the severity degree of the disease, differing primarily in the other high levels of infection by Mycosphaerella spp. and differ mainly of healthy leaves and leaves which are little attacked, in both regions of the electromagnetic spectrum, this behavior occurs for different treetop positions and climate seasons, varying the amount of reflected energy. It is concluded that the reflectance of the Eucalyptus globules leaves attacked by Mycosphaerella spp. differs according to the position in the tree crown and the weather station when they were collected and to the advanced levels of disease severity.

  13. Spatial and spectral performance of a chromotomosynthetic hyperspectral imaging system.

    Science.gov (United States)

    Bostick, Randall L; Perram, Glen P

    2012-03-01

    The spatial and spectral resolutions achievable by a prototype rotating prism chromotomosynthetic imaging (CTI) system operating in the visible spectrum are described. The instrument creates hyperspectral imagery by collecting a set of 2D images with each spectrally projected at a different rotation angle of the prism. Mathematical reconstruction techniques that have been well tested in the field of medical physics are used to reconstruct the data to produce the 3D hyperspectral image. The instrument operates with a 100 mm focusing lens in the spectral range of 400-900 nm with a field of view of 71.6 mrad and angular resolution of 0.8-1.6 ?rad. The spectral resolution is 0.6 nm at the shortest wavelengths, degrading to over 10 nm at the longest wavelengths. Measurements using a point-like target show that performance is limited by chromatic aberration. The system model is slightly inaccurate due to poor estimation of detector spatial resolution, this is corrected based on results improving model performance. As with traditional dispersion technology, calibration of the transformed wavelength axis is required, though with this technology calibration improves both spectral and spatial resolution. While this prototype does not operate at high speeds, components exist which will allow for CTI systems to generate hyperspectral video imagery at rates greater than 100 Hz. PMID:22462909

  14. Photochemical investigation of a photochromic diarylethene compound that can be used as a wide range actinometer

    OpenAIRE

    Ribeiro Santos, André; Ballardini, Roberto; Belser, Peter; Gandolfi, Maria Teresa; Mahadevan Iyer, Vijay; Moggi, Luca

    2010-01-01

    The photochromic diarylethene derivative 1,2-bis(5-(4-ethynylphenyl)-2-methylthiophen-3-yl)perfluorocyclopentene (1) was submitted to photochemical, thermal stability and fatigue resistance studies in acetonitrile, also to evaluate its possible application as a new actinometer. This photochromic system covers a wide spectral absorption range, with intense bands in the UV and visible regions for the open-ring and closed-ring isomers, respectively. Very high ring-closure quantum yield values we...

  15. Ground-based atmospheric infrared and visible emission measurements

    Science.gov (United States)

    Baker, D. J.; Steed, A. J.; Ware, G. A.; Offermann, D.; Lange, G.; Lauche, H.

    1985-03-01

    Ground-based measurements of night-sky NIR and visible emissions were made at the Andenes, Norway, and Kiruna, Sweden, rocket launch sites during the Energy Budget Campaign of 1980. Optical measurements were made using visible and infrared photometers, a Michelson interometer and a grating spectrometer. The spectral range of the spectrometers was 0.85-1.7 microns. Photometer wavelength coverages were at 1.7 microns, 1.27, 6300 A, 5577 A, 5525 A and 3914 A. Emission intensities of OH, O2, N2(+) and O airglow and auroral species are presented. Correlations were observed between the O2(a1 delta-g) emission at 1.27 microns and the OH(8,5) emission at 1.3 microns, giving further evidence that the two species of the night airglow have an emission mechanism in common. Values of the roational temperatures of the OH airglow were derived which are indicative of the temporal history of the near-mesopause atmospheric temperature. Airglow intensities and temperatures are compared with indices of auroral zone geomagnetic activity and with key atmospheric measurements obtained in the campaign. Correlations were found with high significance levels. The trends in the observed mesopause temperature appear to be part of a general disturbance of the atmosphere due to planetary waves.

  16. Visible Epiglottis in Children

    OpenAIRE

    Jamaluddin Ahmed, Farooque; Shinohara, Andrá Luis; Bonifécio da Silva, Salete Moura; ANDREO, Jesus Carlos; RODRIGUES, Antonio de Castro

    2014-01-01

    Visible epiglottis is a rare anatomical variant which is usually asymptomatic without the need of any medical or surgical intervention. It is most commonly seen in children but there are some reports of its prevalence in adults too. Cases of visible epiglottis seem to be unfamiliar among dental professionals. In this report, we have attempted to present this anatomical variant of epiglottis in the feld of dentistry by describing a case of an 8-year-old girl who presented to the department of ...

  17. An improved version of the Visible and Near Infrared (VNIR) spectrometer of EChO

    Science.gov (United States)

    Bellucci, G.; Adriani, A.; Gambicorti, L.; Focardi, M.; Oliva, E.; Farina, M.; Di Giorgio, A. M.; Pace, E.; Piccioni, G.; Filacchione, G.; Pancrazzi, M.; Tozzi, A.; Micela, G.

    2014-08-01

    The Visible and Near Infrared (VNIR) is one of the modules of EChO, the Exoplanets Characterization Observatory proposed to ESA for an M-class mission. EChO is aimed to observe planets while transiting by their suns. Then the instrument has be designed to assure a high efficiency over the whole spectral range. In fact, it has to be able to observe stars with an apparent magnitude Mv= 9÷12 and able to see contrasts of 10-4÷10-5 in order to reveal the characteristics of the atmospheres of the exoplanets under investigation. VNIR was originally designed for covering the spectral range from 0.4 to 1.0 ?m [1] but now the design has been reviewed and its spectral range has been extended up to 2.5 ?m. It is a spectrometer in a cross-dispersed configuration that, then, uses the combination of a diffraction grating and a prism to spread the light in different wavelengths and in a useful number of orders of diffraction. Its resolving power is about 330 over the entire spectral range and its field of view is approximately 2 arcsec. The spectrometer is functionally split into two channels respectively working in the 0.4-1.0 ?m and 1.0-2.5 ?m spectral ranges. Such a solution is imposed by the fact the light at low wavelengths has to be shared with the EChO Fine Guiding System (FGS) devoted to the pointing of the stars under observation. The instrument works at 45K and its weight is 6 kg.

  18. Modelling rotational and cyclical spectral solar irradiance variations

    Science.gov (United States)

    Unruh, Yvonne

    Solar irradiance changes are highly wavelength dependent: solar-cycle variations in the UV can be on the order of tens of percent, while changes in the visible are typically only of the order of one or two permille. With the launch of a number of instruments to measure spectral solar irradiance, we are now for a first time in a good position to explore the changing solar irradiance over a large range of wavelengths and to test our irradiance models as well as some of their underlying assumptions. I will introduce some of the current modelling approaches and present model-data comparisons, using the SATIRE irradiance model and SORCE/SIM measurements as an example. I will conclude by highlighting a number of outstanding questions regarding the modelling of spectral irradiance and current approaches to address these.

  19. Spectral branes

    OpenAIRE

    ~Vassilevich, D. ~V.

    2001-01-01

    We study the objects (called spectral branes or S-branes) which are obtained by imposing non-local spectral boundary conditions at the boundary of the world sheet of the bosonic string. They possess many nice properties which make them an ideal test ground for the string theory methods. Depending on a particular choice of the boundary operator S-branes may be commutative or non-commutative. We demonstrate that projection of the B-field on the brane directions (i.e. on the components which act...

  20. Spectral Ranking

    CERN Document Server

    Vigna, Sebastiano

    2009-01-01

    This note tries to attempt a sketch of the history of spectral ranking, a general umbrella name for techniques that apply the theory of linear maps (in particular, eigenvalues and eigenvectors) to matrices that do not represent geometric transformations, but rather some kind of relationship between entities. Albeit recently made famous by the ample press coverage of Google's PageRank algorithm, spectral ranking was devised more than fifty years ago, almost exactly in the same terms, and has been studied in psychology and social sciences. I will try to describe it in precise and modern mathematical terms, highlighting along the way the contributions given by previous scholars.

  1. Solar Synthesis: Prospects in Visible Light Photocatalysis

    Science.gov (United States)

    Schultz, Danielle M.; Yoon, Tehshik P.

    2015-01-01

    Chemists have long aspired to synthesize molecules the way that plants do — using sunlight to facilitate the construction of complex molecular architectures. Nevertheless, the use of visible light in photochemical synthesis is fundamentally challenging because organic molecules tend not to interact with the wavelengths of visible light that are most strongly emitted in the solar spectrum. Recent research has begun to leverage the ability of visible light absorbing transition metal complexes to catalyze a broad range of synthetically valuable reactions. In this review, we highlight how an understanding of the mechanisms of photocatalytic activation available to these transition metal complexes, and of the general reactivity patterns of the intermediates accessible via visible light photocatalysis, has accelerated the development of this diverse suite of reactions. PMID:24578578

  2. Making Invisible Histories Visible

    Science.gov (United States)

    Hanssen, Ana Maria

    2012-01-01

    This article features Omaha Public Schools' "Making Invisible Histories Visible" program, or MIHV. Omaha's schools have a low failure rate among 8th graders but a high one among high school freshmen. MIHV was created to help at-risk students "adjust to the increased demands of high school." By working alongside teachers and mentors, the program's…

  3. Multimodal visible embolisation particles

    OpenAIRE

    Bartling, Sönke H.; Budjan, Johannes; Sadick, Maliha; Aviv, Hagit; Margel, Shlomo; Reis, Christian; Diehl, Steffen

    2011-01-01

    Embolisation - the blocking of vessels - is a key procedure in Interventional Radiology. It plays a steadily growing role in the treatment of various tumour lesions, with hepatic cellular carcinoma and uterine fibroids the main focus. We produced multimodal visible embolization particles, which can be visualized in X-ray based fluoroscopy and computer tomography (CT) as well as radiation free magnetic resonance imaging (MRI).

  4. Terrain visibility with multiple viewpoints

    OpenAIRE

    Hurtado Díaz, Fernando Alfredo; Löffler, Maarten; Matos, Inés P.; Sacristán Adinolfi, Vera; Saumell, Maria; Silveira, Rodrigo Ignacio; Staals, Frank

    2013-01-01

    We study the problem of visibility in polyhedral terrains in the presence of multiple viewpoints. We consider a triangulated terrain with $m>1$ viewpoints (or guards) located on the terrain surface. A point on the terrain is considered \\emph{visible} if it has an unobstructed line of sight to at least one viewpoint. We study several natural and fundamental visibility structures: (1) the visibility map, which is a partition of the terrain into visible and invisible regions; (...

  5. Spectral Experiments+

    CERN Document Server

    Rivin, Igor

    2014-01-01

    We describe extensive computational experiments on spectral properties of random objects - random cubic graphs, random planar triangulations, and Voronoi and Delaunay diagrams of random (uniformly distributed) point sets on the sphere). We look at bulk eigenvalue distribution, eigenvalue spacings, and locality properties of eigenvectors. In all cases we discover completely new (at least to this author) phenomena.

  6. Visibility of plasmonic particles embedded in transparent materials

    Science.gov (United States)

    Teulle, A.; Marty, R.; Girard, C.; Arbouet, A.; Dujardin, E.

    2013-03-01

    Recently, several experiments have shown that it is possible to visualize the optical near-field generated around individual plasmonic particles through the photo-induced structuration of polymer films. In this communication, we show that the particle visibility can be controlled at will down to the quasi-invisibility by tuning the incident wavelength around the plasmon frequency. This phenomenon occurs when the real part of the particle polarizability displays a sign change. This simple spectrally controlled visibility is an alternative to the more classical spatially controlled visibility approach.

  7. Multispectral concealed weapon detection in visible, infrared, and terahertz

    Science.gov (United States)

    Kowalski, Marcin; Kastek, Mariusz; Polakowski, Henryk; Palka, Norbert; Piszczek, Marek; Szustakowski, Mieczyslaw

    2014-05-01

    Detection of concealed dangerous objects is a very demanding problem of public safety. So far, the problem of detecting objects hidden under clothing was considered only in the case of airports but it is becoming more and more important for public places like metro stations, and government buildings. The development of imaging devices and exploration of new spectral bands is a chance to introduce new equipment for assuring public safety. It has been proved that objects hidden under clothing can be detected and visualized using terahertz (THz) cameras. However, passive THz cameras still offer too low image resolution for objects recognition. On the other hand new infrared cameras offer sufficient parameters to detect objects covered with fabrics in some conditions, as well as high image quality and big pixel resolutions. The purpose of the studies is to investigate the possibilities of using various cameras operating in different spectral ranges for detection of concealed objects. In the article, we present the measurement setup consisting of medium wavelength infrared (MWIR), long wavelength infrared (LWIR), THz and visible cameras and the initial results of measurements with various types of clothing and test objects.

  8. Correction of the recording artifacts and detection of the functional deviations in ECG by means of syndrome decoding with an automatic burst error correction of the cyclic codes using periodograms for determination of the code component spectral range

    Science.gov (United States)

    Adamovic, Evgenie D.; Aleksandrov, Pavel L.; Gradov, Oleg V.; Mamalyga, Leonid M.; Mamalyga, Maksim L.

    2016-01-01

    Aims This paper describes a novel approach to the analysis of electrocardiographic data based on the consideration of the repetitive P, Q, R, S, T sequences as cyclic codes. In Part I we introduce a principle similar to the syndrome decoding using the control numbers, which allows correcting the noise combinations. Materials and methods We propose to apply the burst-error-correcting algorithms for automatic detection of the ECG artifacts and the functional abnormalities, including those compared to the reference model. Our approach is compared to the symbolic dynamics methods. During the automated search of the code components (i.e. point values and spectral ranges one-to-one corresponding to P, Q, R, S, T) considered in Part II, the authors apply the Lomb-Scargle periodogram method with the phase control which allows to determine the code components not only from the main harmonics, but also using the sidebands, avoiding the phase errors. Results The results of the method testing on rats with the heart failure using a simplified telemetric recording from the implantable chips are given in Part III. A complete independence of the results of the determination of the code points (fingerprints) from the variables for which the calculation is performed is shown. We also prove the robustness of the above approach with respect to the most types of the non-adaptive filtration. Conclusion The above method can be useful not only for experimental medicine, but also for veterinary and clinical diagnostic practice. This method is adequately reproduced both on animals and human ECG, except for some constant values.

  9. Spectral analysis by correlation

    International Nuclear Information System (INIS)

    The spectral density of a signal, which represents its power distribution along the frequency axis, is a function which is of great importance, finding many uses in all fields concerned with the processing of the signal (process identification, vibrational analysis, etc...). Amongst all the possible methods for calculating this function, the correlation method (correlation function calculation + Fourier transformation) is the most promising, mainly because of its simplicity and of the results it yields. The study carried out here will lead to the construction of an apparatus which, coupled with a correlator, will constitute a set of equipment for spectral analysis in real time covering the frequency range 0 to 5 MHz. (author)

  10. Infrared and visible cooperative vehicle identification markings

    Science.gov (United States)

    O'Keefe, Eoin S.; Raven, Peter N.

    2006-05-01

    Airborne surveillance helicopters and aeroplanes used by security and defence forces around the world increasingly rely on their visible band and thermal infrared cameras to prosecute operations such as the co-ordination of police vehicles during the apprehension of a stolen car, or direction of all emergency services at a serious rail crash. To perform their function effectively, it is necessary for the airborne officers to unambiguously identify police and the other emergency service vehicles. In the visible band, identification is achieved by placing high contrast symbols and characters on the vehicle roof. However, at the wavelengths at which thermal imagers operate, the dark and light coloured materials have similar low reflectivity and the visible markings cannot be discerned. Hence there is a requirement for a method of passively and unobtrusively marking vehicles concurrently in the visible and thermal infrared, over a large range of viewing angles. In this paper we discuss the design, detailed angle-dependent spectroscopic characterisation and operation of novel visible and infrared vehicle marking materials, and present airborne IR and visible imagery of materials in use.

  11. Visibility graph motifs

    CERN Document Server

    Iacovacci, Jacopo

    2015-01-01

    Visibility algorithms transform time series into graphs and encode dynamical information in their topology, paving the way for graph-theoretical time series analysis as well as building a bridge between nonlinear dynamics and network science. In this work we introduce and study the concept of visibility graph motifs, smaller substructures that appear with characteristic frequencies. We develop a theory to compute in an exact way the motif profiles associated to general classes of deterministic and stochastic dynamics. We find that this simple property is indeed a highly informative and computationally efficient feature capable to distinguish among different dynamics and robust against noise contamination. We finally confirm that it can be used in practice to perform unsupervised learning, by extracting motif profiles from experimental heart-rate series and being able, accordingly, to disentangle meditative from other relaxation states. Applications of this general theory include the automatic classification a...

  12. Spectral Predictors

    Energy Technology Data Exchange (ETDEWEB)

    Ibarria, L; Lindstrom, P; Rossignac, J

    2006-11-17

    Many scientific, imaging, and geospatial applications produce large high-precision scalar fields sampled on a regular grid. Lossless compression of such data is commonly done using predictive coding, in which weighted combinations of previously coded samples known to both encoder and decoder are used to predict subsequent nearby samples. In hierarchical, incremental, or selective transmission, the spatial pattern of the known neighbors is often irregular and varies from one sample to the next, which precludes prediction based on a single stencil and fixed set of weights. To handle such situations and make the best use of available neighboring samples, we propose a local spectral predictor that offers optimal prediction by tailoring the weights to each configuration of known nearby samples. These weights may be precomputed and stored in a small lookup table. We show that predictive coding using our spectral predictor improves compression for various sources of high-precision data.

  13. Making Invisible Forces Visible

    DEFF Research Database (Denmark)

    Ratner, Helene; Pors, Justine Grønbæk

    2013-01-01

    This paper investigates managerial tactics of visualisation when a need to know and manage employees' values and attitudes is expressed. Using the Danish public school as a case study, we explore how school managers use teachers' emotions to render visible presumably invisible information about their 'true' attitudes and values. The paper draws on theories of affect as well as actor-network theory to analyse three incidents where managers turn their interpretations of teachers' emotions into suc...

  14. Spitzer Makes 'Invisible' Visible

    Science.gov (United States)

    2004-01-01

    Hidden behind a shroud of dust in the constellation Cygnus is a stellar nursery called DR21, which is giving birth to some of the most massive stars in our galaxy. Visible light images reveal no trace of this interstellar cauldron because of heavy dust obscuration. In fact, visible light is attenuated in DR21 by a factor of more than 10,000,000,000,000,000,000,000,000,000,000,000,000,000 (ten thousand trillion heptillion). New images from NASA's Spitzer Space Telescope allow us to peek behind the cosmic veil and pinpoint one of the most massive natal stars yet seen in our Milky Way galaxy. The never-before-seen star is 100,000 times as bright as the Sun. Also revealed for the first time is a powerful outflow of hot gas emanating from this star and bursting through a giant molecular cloud. The colorful image is a large-scale composite mosaic assembled from data collected at a variety of different wavelengths. Views at visible wavelengths appear blue, near-infrared light is depicted as green, and mid-infrared data from the InfraRed Array Camera (IRAC) aboard NASA's Spitzer Space Telescope is portrayed as red. The result is a contrast between structures seen in visible light (blue) and those observed in the infrared (yellow and red). A quick glance shows that most of the action in this image is revealed to the unique eyes of Spitzer. The image covers an area about two times that of a full moon.

  15. Spectral imaging for contamination detection in food

    DEFF Research Database (Denmark)

    Carstensen, Jens Michael Technical University of Denmark,

    Spectral imaging is a technique with a big potential for surface chemistry mapping of heterogeneous samples. It works by making a spectrum in every pixel of an image, and this spectrum may under the right circumstances be transformed into abundance maps for chemical components. One important application of the technique is finding anomalies I supposedly homogeneous matter or homogeneous mixtures. This application occurs frequently in the food industry when different types of contamination are to be detected. Contaminants could be e.g. foreign matter, process-induced toxins, and microbiological spoilage. Many of these contaminants may be detected in the wavelength range visible to normal silicium-based camera sensors i.e. 350-1050 nm with proper care during sample preparation, sample presentation, image acquisition and analysis. This presentation will give an introduction to the techniques behind the VideometerLab instrument, that implements the thoughts above, and show examples including fusarium detection inbarley, measuring microbial meat spoilage, and making humidity maps. It will also illustrate methodology for spectral image analysis.

  16. Can we match ultraviolet face images against their visible counterparts?

    Science.gov (United States)

    Narang, Neeru; Bourlai, Thirimachos; Hornak, Lawrence A.

    2015-05-01

    In law enforcement and security applications, the acquisition of face images is critical in producing key trace evidence for the successful identification of potential threats. However, face recognition (FR) for face images captured using different camera sensors, and under variable illumination conditions, and expressions is very challenging. In this paper, we investigate the advantages and limitations of the heterogeneous problem of matching ultra violet (from 100 nm to 400 nm in wavelength) or UV, face images against their visible (VIS) counterparts, when all face images are captured under controlled conditions. The contributions of our work are three-fold; (i) We used a camera sensor designed with the capability to acquire UV images at short-ranges, and generated a dual-band (VIS and UV) database that is composed of multiple, full frontal, face images of 50 subjects. Two sessions were collected that span over the period of 2 months. (ii) For each dataset, we determined which set of face image pre-processing algorithms are more suitable for face matching, and, finally, (iii) we determined which FR algorithm better matches cross-band face images, resulting in high rank-1 identification rates. Experimental results show that our cross spectral matching (the heterogeneous problem, where gallery and probe sets consist of face images acquired in different spectral bands) algorithms achieve sufficient identification performance. However, we also conclude that the problem under study, is very challenging, and it requires further investigation to address real-world law enforcement or military applications. To the best of our knowledge, this is first time in the open literature the problem of cross-spectral matching of UV against VIS band face images is being investigated.

  17. Design and fabrication of multiple airgap-based visible filters

    Science.gov (United States)

    Ghaderi, M.; Wolffenbuttel, R. F.

    2014-05-01

    The efficiency of a Bragg reflector design for implementation in optical resonators is highly dependent on the ratio between the high-index material and the low-index material used for the quarter-wavelength (QWOT) layers. A higher contrast implies that fewer layers are required to achieve a specified spectral selectivity over a wider spectral band. In turn, the reduced total thickness of the filter stack reduces the effect of optical absorption in the layers. The research presented here focuses on implementation of filters on top of silicon detectors that are already fabricated in a CMOS process. This implies that the constraints of process compatibility, such as the materials to be used, process temperature and cleanroom reentrance related to contamination, need to be considered. Silicon-dioxide is often used in CMOS-compatible designs, which has an index of refraction n~1.5, thus limiting nHi/nLo to about 2. This value can be improved by 50% when using air-films as the low-n material. Surface micromachining is used for the fabrication of such mirrors. Multiple layers of Si and SiO2 were alternatingly deposited, and subsequently the Si layers are selectively removed in a sacrificial etch. The width of the ?/4 air-gaps is about 100 nm, which is narrower as compared to the typical layer thickness that is used in surface micromachining for conventional MEMS applications. Moreover, a demanding optical design requires more layers than typically used in a conventional MEMS device. Since the number of stacked layers is significantly higher as compared to the conventional MEMS, fabricating such filters is a challenge. However, unlike a conventional MEMS, electrical contacting to the structural layers is not required in optical filter application, which, eases the fabrication of such filters. This paper presents the design of several 4-layer structures for use in the visible spectral range, along with the fabrication sequence and preliminary measurement results.

  18. Two-dimensional material-based saturable absorbers: towards compact visible-wavelength all-fiber pulsed lasers.

    Science.gov (United States)

    Luo, Zhengqian; Wu, Duanduan; Xu, Bin; Xu, Huiying; Cai, Zhiping; Peng, Jian; Weng, Jian; Xu, Shuo; Zhu, Chunhui; Wang, Fengqiu; Sun, Zhipei; Zhang, Han

    2015-12-23

    Passive Q-switching or mode-locking by placing a saturable absorber inside the laser cavity is one of the most effective and popular techniques for pulse generation. However, most of the current saturable absorbers cannot work well in the visible spectral region, which seriously impedes the progress of passively Q-switched/mode-locked visible pulsed fibre lasers. Here, we report a kind of visible saturable absorber-two-dimensional transition-metal dichalcogenides (TMDs, e.g. WS2, MoS2, MoSe2), and successfully demonstrate compact red-light Q-switched praseodymium (Pr(3+))-doped all-fibre lasers. The passive Q-switching operation at 635 nm generates stable laser pulses with ?200 ns pulse duration, 28.7 nJ pulse energy and repetition rate from 232 to 512 kHz. This achievement is attributed to the ultrafast saturable absorption of these layered TMDs in the visible region, as well as the compact and all-fibre laser-cavity design by coating a dielectric mirror on the fibre end facet. This work may open a new route for next-generation high-performance pulsed laser sources in the visible (even ultraviolet) range. PMID:26658877

  19. [VISIBLE LIGHT AND HUMAN SKIN (REVIEW)].

    Science.gov (United States)

    Tsibadze, A; Chikvaidze, E; Katsitadze, A; Kvachadze, I; Tskhvediani, N; Chikviladze, A

    2015-09-01

    Biological effect of a visible light depends on extend of its property to penetrate into the tissues: the greater is a wavelength the more is an effect of a radiation. An impact of a visible light on the skin is evident by wave and quantum effects. Quanta of a visible radiation carry more energy than infrared radiation, although an influence of such radiation on the skin is produced by the light spectrum on the boarder of the ultraviolet and the infrared rays and is manifested by thermal and chemical effects. It is determined that large doses of a visible light (405-436 nm) can cause skin erythema. At this time, the ratio of generation of free radicals in the skin during an exposure to the ultraviolet and the visible light range from 67-33% respectively. Visible rays of 400-500 nm length of wave cause an increase of the concentration of oxygen's active form and mutation of DNA and proteins in the skin. The urticaria in 4-18% of young people induced by photodermatosis is described. As a result of a direct exposure to sunlight photosensitive eczema is more common in elderly. Special place holds a hereditary disease - porphyria, caused by a visible light. In recent years, dermatologists widely use phototherapy. The method uses polychromatic, non-coherent (wavelength of 515-1200 nm) pulsating beam. During phototherapy/light treatment a patient is being exposed to sunlight or bright artificial light. Sources of visible light are lasers, LEDs and fluorescent lamps which have the full range of a visible light. Phototherapy is used in the treatment of acne vulgaris, seasonal affective disorders, depression, psoriasis, eczema and neurodermities. LED of the red and near infrared range also is characterized by the therapeutic effect. They have an ability to influence cromatophores and enhance ATP synthesis in mitochondria. To speed up the healing of wounds and stimulate hair growth light sources of a weak intensity are used. The light of blue-green spectrum is widely used for the treatment of neonatal hyperbilirubinemy. A photodynamic therapy takes a special place. The third generation of the blue (410 nm), yellow (595 nm) and red photosensitors are used. Photodynamic therapy is used in the treatment of cancer as well. PMID:26355315

  20. Visible-Near-Infrared Range Whispering Gallery Resonance from Photonic ?-Sphere Cavities Self-Assembled from a Blend of Polystyrene and Poly[4,7-bis(3-octylthiophene-2-yl)benzothiadiazole-co-2,6-bis(pyrazolyl)pyridine] Coordinated to Tb(acac)3.

    Science.gov (United States)

    Narayana, Yemineni S L V; Venkatakrishnarao, Dasari; Biswas, Arani; Mohiddon, Mahamad Ahamad; Viswanathan, Nirmal; Chandrasekar, Rajadurai

    2016-01-13

    A novel red emitting copolymer (P1) was prepared (Mn ? 10.7 kDa) by copolymerizing tridentate ligand, namely 2,6-bis(pyrazolyl)pyridine (BPP) with 4,7-bis(2-ethynyl-5-thienyl)-2,1,3-benzothiadiazole. This copolymer readily formed an orange yellow emitting metal containing conjugated polymer (P1.Tb) with Tb(acac)3. Further, a judicial blend of P1.Tb with polystyrene and its subsequent self-assembly in THF/water produced microspheres with smooth surface area. Interestingly, continuous wave laser excitation of a single microsphere displayed whispering-gallery-mode (WGM) resonance modes over a broad wavelength range covering visible (Vis) and near-infrared (NIR) regions (0.550-0.875 ?m). The estimated Q factor was up to 700, which is very high for a metal containing conjugated polymer (MCCP)-based optical gain medium. PMID:26694108

  1. Fast calculations of the spectral diffuse-to-global ratios for approximating spectral irradiance at the street canyon level

    Science.gov (United States)

    Carrasco-Hernandez, Roberto; Smedley, Andrew R. D.; Webb, Ann R.

    2015-05-01

    Two radiative transfer models are presented that simplify calculations of street canyon spectral irradiances with minimum data input requirements, allowing better assessment of urban exposures than can be provided by standard unobstructed radiation measurements alone. Fast calculations improve the computational performance of radiation models, when numerous repetitions are required in time and location. The core of the models is the calculation of the spectral diffuse-to-global ratios (DGR) from an unobstructed global spectral measurement. The models are based on, and have been tested against, outcomes of the SMARTS2 algorithm (i.e. Simple Model of the Atmospheric Radiative Transfer of Sunshine). The modelled DGRs can then be used to partition global spectral irradiance values into their direct and diffuse components for different solar zenith angles. Finally, the effects of canyon obstructions can be evaluated independently on the direct and diffuse components, which are then recombined to give the total canyon irradiance. The first model allows ozone and aerosol inputs, while the second provides a further simplification, restricted to average ozone and aerosol contents but specifically designed for faster calculations. To assess the effect of obstructions and validate the calculations, a set of experiments with simulated obstructions (simulated canyons) were performed. The greatest source of uncertainty in the simplified calculations is in the treatment of diffuse radiation. The measurement-model agreement is therefore dependent on the region of the sky obscured and ranges from <5 % at all wavelengths to 20-40 % (wavelength dependent) when diffuse sky only is visible from the canyon.

  2. Point-focus spectral splitting solar concentrator for multiple cells concentrating photovoltaic system

    CERN Document Server

    Maragliano, Carlo; Stefancich, Marco

    2015-01-01

    In this paper we present and experimentally validate a low-cost design of a spectral splitting concentrator for the efficient conversion of solar energy. The optical device consists of a dispersive prismatic lens made of polycarbonate designed to simultaneously concentrate the solar light and split it into its spectral components. With respect to our previous implementation, this device concentrates the light along two axes and generates a light pattern compatible with the dimensions of a set of concentrating photovoltaic cells while providing a higher concentration ratio. The mathematical framework and the constructive approach used for the design are presented and the device performance is simulated using ray-tracing software. We obtain spectral separation in the visible range within a 3x1 cm2 area and a maximum concentration of 210x for a single wavelength. The device is fabricated by injection molding and its performance is experimentally investigated. We measure an optical transmissivity above 90% in the...

  3. Hard X-Ray Imaging of Individual Spectral Components in Solar Flares

    CERN Document Server

    Caspi, Amir; McTiernan, James M; Krucker, Säm

    2015-01-01

    We present a new analytical technique, combining Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) high-resolution imaging and spectroscopic observations, to visualize solar flare emission as a function of spectral component (e.g., isothermal temperature) rather than energy. This computationally inexpensive technique is applicable to all spatially-invariant spectral forms and is useful for visualizing spectroscopically-determined individual sources and placing them in context, e.g., comparing multiple isothermal sources with nonthermal emission locations. For example, while extreme ultraviolet images can usually be closely identified with narrow temperature ranges, due to the emission being primarily from spectral lines of specific ion species, X-ray images are dominated by continuum emission and therefore have a broad temperature response, making it difficult to identify sources of specific temperatures regardless of the energy band of the image. We combine RHESSI calibrated X-ray visibilities wi...

  4. Filterless narrowband visible photodetectors

    Science.gov (United States)

    Lin, Qianqian; Armin, Ardalan; Burn, Paul L.; Meredith, Paul

    2015-10-01

    Wavelength-selective light detection is crucial for many applications, including imaging and machine vision. Narrowband spectral responses are required for colour discrimination, and current systems use broadband photodiodes combined with optical filters. This approach increases the architectural complexity and limits the quality of colour sensing. Here we report a method for tuning the spectral response to give filterless, narrowband red, green and blue photodiodes. The devices have simple planar junction architectures with the photoactive layer being a solution-processed mixture of either an organohalide perovskite or lead halide semiconductor and an organic (macro)molecule. The organic (macro)molecules modify the optical and electrical properties of the photodiode and facilitate charge collection narrowing of the device's external quantum efficiency. These red, green and blue photodiodes all possess full-width at half-maxima of <100?nm and performance metrics suitable for many imaging applications.

  5. WWW visibility in marketing

    OpenAIRE

    Ollila, T. (Timo)

    2013-01-01

    Social media is a vital channel for marketers nowadays. Customers are more empowered today than ever before and the Internet is accelerating the trend toward greater customer empowerment. In few years Web 2.0 has become a highly important media and it has changed the Web into platform where individuals can communicate, assemble and organize data. Web 2.0 also offers a variety of different “tools” for companies to be used in marketing. Because companies and products are visible and discussed i...

  6. Thioxanthone based 9-[2-(methyl-phenyl-amino)-acetyl]-thia-naphthacene-12-one as a visible photoinitiator

    Energy Technology Data Exchange (ETDEWEB)

    Do?ruyol, Sevnur Keskin [Department of Chemistry, Y?ld?z Technical University, Davutpasa Campus, Esenler, 34220 Istanbul (Turkey); Do?ruyol, Zekeriya [Department of Engineering Science, Istanbul University, 34850, Avc?lar, Istanbul (Turkey); Arsu, Nergis, E-mail: narsu@yildiz.edu.tr [Department of Chemistry, Y?ld?z Technical University, Davutpasa Campus, Esenler, 34220 Istanbul (Turkey)

    2013-06-15

    Photoinitiators that operate in the visible range of the electromagnetic spectrum have widespread applications. Thioxanthone based 9-[2-(methyl-phenyl-amino)-acetyl]-thia-naphthacene-12-one (TX-MPA) was synthesized and the characterization of this initiator was confirmed by spectral analysis methods. TX-MPA has excellent absorption properties in the visible range (?{sub 480} {sub nm}=3576 L/mol.cm). Photophysical studies; fluorescence quantum yield (?{sub f}=0.22, DPA), phosphorescence lifetime (?{sub p}=115 ms) and triplet lifetime (?=190 ns) were explored. To explore the initiation mechanism of TX-MPA, besides the photophysical and photochemical studies, the polymer (PMMA) obtained from the photopolymerization studies was subjected to a phosphorescence study and ?{sub p} was found to be 105 ms compared to 115 ms for the initiator TX-MPA which proved attachment of the initiator to the polymer. Possibly both intermolecular and intramolecular hydrogen abstraction, occur during the initiation stage depending on the concentration of the initiator. Highlights: ? Synthesis and photophysical properties of a visible photoinitiator (TX-MPA) are proposed. ? TX-MPA has high molar absorption values in the visible region. ? TX-MPA can initiate photopolymerization of methylmethacrylate monomer under UV and sunlight. ? Inter or intramolecular hydrogen abstraction mechanisms occur depending on initiator concentration.

  7. Thioxanthone based 9-[2-(methyl-phenyl-amino)-acetyl]-thia-naphthacene-12-one as a visible photoinitiator

    International Nuclear Information System (INIS)

    Photoinitiators that operate in the visible range of the electromagnetic spectrum have widespread applications. Thioxanthone based 9-[2-(methyl-phenyl-amino)-acetyl]-thia-naphthacene-12-one (TX-MPA) was synthesized and the characterization of this initiator was confirmed by spectral analysis methods. TX-MPA has excellent absorption properties in the visible range (?480nm=3576 L/mol.cm). Photophysical studies; fluorescence quantum yield (?f=0.22, DPA), phosphorescence lifetime (?p=115 ms) and triplet lifetime (?=190 ns) were explored. To explore the initiation mechanism of TX-MPA, besides the photophysical and photochemical studies, the polymer (PMMA) obtained from the photopolymerization studies was subjected to a phosphorescence study and ?p was found to be 105 ms compared to 115 ms for the initiator TX-MPA which proved attachment of the initiator to the polymer. Possibly both intermolecular and intramolecular hydrogen abstraction, occur during the initiation stage depending on the concentration of the initiator. Highlights: ? Synthesis and photophysical properties of a visible photoinitiator (TX-MPA) are proposed. ? TX-MPA has high molar absorption values in the visible region. ? TX-MPA can initiate photopolymerization of methylmethacrylate monomer under UV and sunlight. ? Inter or intramolecular hydrogen abstraction mechanisms occur depending on initiator concentration

  8. Application of Visible and Near-Infrared Hyperspectral Imaging to Determine Soluble Protein Content in Oilseed Rape Leaves

    OpenAIRE

    Chu Zhang; Fei Liu; Wenwen Kong; Yong He

    2015-01-01

    Visible and near-infrared hyperspectral imaging covering spectral range of 380–1030 nm as a rapid and non-destructive method was applied to estimate the soluble protein content of oilseed rape leaves. Average spectrum (500–900 nm) of the region of interest (ROI) of each sample was extracted, and four samples out of 128 samples were defined as outliers by Monte Carlo-partial least squares (MCPLS). Partial least squares (PLS) model using full spectra obtained dependable performance with the co...

  9. Comparison of visible and near-infrared Raman cross-sections of explosives in solution and in the solid state.

    Science.gov (United States)

    Emmons, Erik D; Guicheteau, Jason A; Fountain, Augustus W; Christesen, Steven D

    2012-06-01

    Raman cross-sections of explosives in solution and in the solid state have been measured using visible and near-infrared excitation via secondary calibration. These measurements are valuable for both fundamental scientific purposes and applications in the standoff detection of explosives. The explosive compounds RDX, HMX, TNT, 2,4-DNT, 2,6-DNT, and ammonium nitrate were measured using discrete excitation wavelengths ranging from 532 nm to 785 nm. A comparison of the spectral features and cross-sections between the solid state and solution was performed. Comparison is also made to cross-sections measured with deep ultraviolet excitation. PMID:22732533

  10. Liquid-Crystal Coats Help Make Flows Visible

    Science.gov (United States)

    Holmes, Bruce J.; Obara, Clifford J.

    1991-01-01

    Visible indication of transition of boundary layer from laminar to turbulent flow plays important role in aerodynamic tests in wind tunnels and in flight. In newly developed method, liquid-crystal coats used to make visible such features of boundary-layer flows as transitions, separations, and locations of shocks. Changes of color rapid and reversible. For flight applications, provides capability for making transitions visible throughout almost entire altitude and speed ranges of subsonic aircraft. Also applicable to visible indication of supersonic flows and suitable for general use in high- and low-speed wind-tunnel and water-tunnel testing.

  11. UVMag: stellar formation, evolution, structure and environment with space UV and visible spectropolarimetry

    CERN Document Server

    Neiner, C; Fullerton, A; Gry, C; Hussain, G; Lebre, A; Morin, J; Petit, P; Sundqvist, J O; ud-Doula, A; Vidotto, A A; Wade, G A

    2014-01-01

    Important insights into the formation, structure, evolution and environment of all types of stars can be obtained through the measurement of their winds and possible magnetospheres. However, this has hardly been done up to now mainly because of the lack of UV instrumentation available for long periods of time. To reach this aim, we have designed UVMag, an M-size space mission equipped with a high-resolution spectropolarimeter working in the UV and visible spectral range. The UV domain is crucial in stellar physics as it is very rich in atomic and molecular lines and contains most of the flux of hot stars. Moreover, covering the UV and visible spectral domains at the same time will allow us to study the star and its environment simultaneously. Adding polarimetric power to the spectrograph will multiply tenfold the capabilities of extracting information on stellar magnetospheres, winds, disks, and magnetic fields. Examples of science objectives that can be reached with UVMag are presented for pre-main sequence,...

  12. Ion irradiation of the Murchison meteorite: Visible to mid-infrared spectroscopic results

    Science.gov (United States)

    Lantz, C.; Brunetto, R.; Barucci, M. A.; Dartois, E.; Duprat, J.; Engrand, C.; Godard, M.; Ledu, D.; Quirico, E.

    2015-05-01

    Aims: The goal of this study is to simulate space weathering processes on primitive bodies. We use ion implantation as a simulation of solar wind irradiation, which has been suggested by several authors to be the major component of space weathering on main belt asteroids. The laboratory analogs we irradiate and analyze are carbonaceous chondrites; we started the study with the Allende CV meteorite and in this companion paper we present results on the Murchison CM meteorite. Methods: We performed irradiations on pressed pellets of Murchison with 40 keV He+ and Ar+ ions using fluences up to 3 × 1016 ions/cm2. Reflectance spectra were acquired ex situ before and after irradiation in the visible to mid-infrared range (0.4-16 ?m). A Raman analysis was also performed to investigate the modifications of the aromatic carbonaceous component. Results: Our results indicate that spectral variations after irradiation within the visible range are smaller than spectral variations due to sample grain size or viewing geometry of the Murchison meteorite. The aqueous alteration band profile near 3 ?m changes after irradiation, as adsorbed water is removed, and phyllosilicates are affected. Raman spectroscopy highlights the insoluble organic matter (IOM) modification under irradiation. We observe a shift of the silicates band at 9.9 ?m, probably due to a preferential loss of Mg (compared to Fe, the lighter Mg is more easily sputtered backward) and/or amorphization of Mg-rich materials. We compare our results to previous experiments on organic-rich materials (like asphaltite or carbonaceous chondrites), and on ordinary chondrites and olivine grains. We find that the reddening/darkening trend observed on silicate-rich surfaces is not valid for all carbonaceous chondrites, and that the spectral modifications after irradiation are a function of the initial albedo.

  13. Understanding Visible Perception

    Science.gov (United States)

    2003-01-01

    One concern about human adaptation to space is how returning from the microgravity of orbit to Earth can affect an astronaut's ability to fly safely. There are monitors and infrared video cameras to measure eye movements without having to affect the crew member. A computer screen provides moving images which the eye tracks while the brain determines what it is seeing. A video camera records movement of the subject's eyes. Researchers can then correlate perception and response. Test subjects perceive different images when a moving object is covered by a mask that is visible or invisible (above). Early results challenge the accepted theory that smooth pursuit -- the fluid eye movement that humans and primates have -- does not involve the higher brain. NASA results show that: Eye movement can predict human perceptual performance, smooth pursuit and saccadic (quick or ballistic) movement share some signal pathways, and common factors can make both smooth pursuit and visual perception produce errors in motor responses.

  14. Tuning the effective plasma frequency of nanorod metamaterials from visible to telecom wavelengths

    Science.gov (United States)

    Nasir, M. E.; Peruch, S.; Vasilantonakis, N.; Wardley, W. P.; Dickson, W.; Wurtz, G. A.; Zayats, A. V.

    2015-09-01

    Hyperbolic plasmonic metamaterials are important for designing sensing, nonlinear, and emission functionalities, which are, to a large extent, determined by the epsilon-near-zero behaviour observed close to an effective plasma frequency of the metamaterial. Here, we describe a method for tuning the effective plasma frequency of a gold nanorod-based metamaterial throughout the visible and near-infrared spectral ranges. These metamaterials, fabricated by two-step anodization in selenic acid and chemical post-processing, consist of nanorods with diameters of around 10 nm and interrod distances of around 100 nm and have a low effective plasma frequency down to a wavelength range below 1200 nm. Such metamaterials open up new possibilities for a variety of applications in the fields of bio- and chemical sensing, nonlinearity enhancement, and fluorescence control in the infrared.

  15. Electrically tunable selective reflection of light from ultraviolet to visible and infrared by heliconical cholesterics

    CERN Document Server

    Xiang, Jie; Li, Quan; Paterson, Daniel A; Storey, John M D; Imrie, Corrie T; Lavrentovich, Oleg D

    2015-01-01

    Cholesteric liquid crystals with helicoidal molecular architecture are known for their ability to selectively reflect light with the wavelength that is determined by the periodicity of molecular orientations. Here we demonstrate that by using a cholesteric with oblique helicoidal(heliconical) structure, as opposed to the classic right-angle helicoid, one can vary the wavelength of selectively reflected light in a broad spectral range, from ultraviolet to visible and infrared (360-1520 nm for the same chemical composition) by simply adjusting the electric field applied parallel to the helicoidal axis. The effect exists in a wide temperature range (including the room temperatures) and thus can enable many applications that require dynamically controlled transmission and reflection of electromagnetic waves, from energy-saving smart windows to tunable organic lasers, reflective color display, and transparent see-through displays.

  16. Near-infrared spectral imaging of the female breast for quantitative oximetry in optical mammography

    International Nuclear Information System (INIS)

    We present a hybrid continuous-wave, frequency-domain instrument for near-infrared spectral imaging of the female breast based on a tandem, planar scanning of one illumination optical fiber and one collection optical fiber configured in a transmission geometry. The spatial sampling rate of 25 points/cm2 is increased to 400 points/cm2 by postprocessing the data with a 2D cubic spline interpolation. We then apply a previously developed spatial second-derivative algorithm to an edge-corrected intensity image (N-image) to enhance the visibility and resolution of optical inhomogeneities in breast tissue such as blood vessels and tumors. The spectral data at each image pixel consist of 515-point spectra over the 650-900 nm wavelength range, thus featuring a spectral density of two data points per nanometer. We process the measured spectra with a paired-wavelength spectral analysis method to quantify the oxygen saturation of detected optical inhomogeneities, under the assumption that they feature a locally higher hemoglobin concentration. Our initial measurements on two healthy human subjects have generated high-resolution optical mammograms displaying a network of blood vessels with values of hemoglobin saturation typically falling within the 60%-95% range, which is physiologically reasonable. This approach to spectral imaging and oximetry of the breast has the potential to efficiently exploit the high intrinsic contrast provided by hemoglobin in breast tissue and to contribute a useful tool in the detection, diagnosis, and monitoring of breast pathologies

  17. Effects of Dopant Concentrations on Thin Films with Coherent Formulation at Visible Wavelengths

    Directory of Open Access Journals (Sweden)

    M. Omidpanah

    2012-01-01

    Full Text Available Semiconductor materials with coatings have a wide range of applications in MEMS and NEMS. This work uses transfer-matrix method for calculating the radiative properties. Dopped silicon is used and the coherent formulation is applied. The Drude model for the optical constants of doped silicon is employed. Results showed that for the visible wavelengths, more emittance occurs in high concentrations and the reflectance decreases as the concentration increases. In these wavelengths, transmittance is negligible. Donars and acceptors act similar in visible wavelengths. The effect of wave interference can be understood by plotting the spectral properties such as reflectance or transmittance of a thin dielectric film versus the film thickness and analyzing the oscillations of properties due to constructive and destructive interferences. But this effect has not been shown at visible wavelengths. At room temperature, the scattering process is dominated by lattice scattering for lightly doped silicon, and the impurity scattering becomes important for heavily doped silicon when the dopant concentration exceeds 1018cm-3.

  18. Non-Euclidean Visibility Problems

    Indian Academy of Sciences (India)

    Fernando Chamizo

    2006-05-01

    We consider the analog of visibility problems in hyperbolic plane (represented by Poincaré half-plane model $\\mathbb{H}$), replacing the standard lattice $\\mathbb{Z} \\times \\mathbb{Z}$ by the orbit $z = i$ under the full modular group $SL_2(\\mathbb{Z})$. We prove a visibility criterion and study orchard problem and the cardinality of visible points in large circles.

  19. Spectrally-Based Assessment of Crop Seasonal Performance and Yield

    Science.gov (United States)

    Kancheva, Rumiana; Borisova, Denitsa; Georgiev, Georgy

    The rapid advances of space technologies concern almost all scientific areas from aeronautics to medicine, and a wide range of application fields from communications to crop yield predictions. Agricultural monitoring is among the priorities of remote sensing observations for getting timely information on crop development. Monitoring agricultural fields during the growing season plays an important role in crop health assessment and stress detection provided that reliable data is obtained. Successfully spreading is the implementation of hyperspectral data to precision farming associated with plant growth and phenology monitoring, physiological state assessment, and yield prediction. In this paper, we investigated various spectral-biophysical relationships derived from in-situ reflectance measurements. The performance of spectral data for the assessment of agricultural crops condition and yield prediction was examined. The approach comprisesd development of regression models between plant spectral and state-indicative variables such as biomass, vegetation cover fraction, leaf area index, etc., and development of yield forecasting models from single-date (growth stage) and multitemporal (seasonal) reflectance data. Verification of spectral predictions was performed through comparison with estimations from biophysical relationships between crop growth variables. The study was carried out for spring barley and winter wheat. Visible and near-infrared reflectance data was acquired through the whole growing season accompanied by detailed datasets on plant phenology and canopy structural and biochemical attributes. Empirical relationships were derived relating crop agronomic variables and yield to various spectral predictors. The study findings were tested using airborne remote sensing inputs. A good correspondence was found between predicted and actual (ground-truth) estimates

  20. Search for Olivine Spectral Signatures on the Surface of Vesta

    Science.gov (United States)

    Palomba, E.; De Sanctis, M. C.; Ammannito, E.; Capaccioni, F.; Capria, M. T.; Farina, M.; Frigeri, A.; Longobardo, A.; Tosi, F.; Zambon, F.; McSween, H. Y.; Mittlefehldt, D. W.; Russell, C. T.; Raymond, C. A.; Sunshine, J.; McCord, T. B.

    2012-01-01

    The occurrence of olivines on Vesta were first postulated from traditional petrogenetic models which suggest the formation of olivine as lower crustal cumulates. An indirect confirmation is given by their presence as a minor component in some samples of diogenite meteorites, the harzburgitic diogenites and the dunitic diogenites, and as olivine mineral clasts in howardites. Another indication for this mineral was given by interpretations of groundbased and Hubble Space Telescope observations that suggested the presence of local olivine-bearing units on the surface of Vesta. The VIR instrument onboard the DAWN mission has been mapping Vesta since July 2011. VIR acquired hyperspectral images of Vesta s surface in the wavelength range from 0.25 to 5.1 m during Approach, Survey and High Altitude Mapping (HAMO) orbits that allowed a 2/3 of the entire asteroid surface to be mapped. The VIR operative spectral interval, resolution and coverage is suitable for the detection and mapping of any olivine rich regions that may occur on the Vesta surface. The abundance of olivine in diogenites is typically lower than 10% but some samples richer in olivine are known. However, we do not expect to have extensive exposures of olivine-rich material on Vesta. Moreover, the partial overlap of olivine and pyroxene spectral signatures will make olivine difficult to detect. Different spectral parameters have been used to map olivine on extraterrestrial bodies, and here we discuss the different approaches used, and develop new ones specifically for Vesta. Our new methods are based on combinations of the spectral parameters relative to the 1 and 2 micron bands (the most prominent spectral features of Vesta surface in the visible and the infrared), such as band center locations, band depths, band areas, band area ratios. Before the direct application to the VIR data, the efficiency of each approach is evaluated by means of analysis of laboratory spectra of HED meteorites, pyroxenes, olivines and their mixtures.

  1. Mechanism of yeast cell photoinactivation by visible light

    International Nuclear Information System (INIS)

    The nature of inactivation of visible light without sensitizers added to the cells has been investigated. In particular, the problem on the nature of intracellular sensitizers has been studied. Visible light is shown to inactivate the cells only in the presence of oxygen, that gives evidence that the process of photoinactivation is carried out according a photodynamic mechanism with participation of the endogenic sensitizer. The pigment - sensitizer is identified as the protoporphyrin on the basis of comparison of data obtained for the absorption spectrum structure and pigment fluorescence with the literature data on the spectral properties of porphyrin compounds

  2. Using Visible/Near-Infrared Spectroscopy to Identify Cryptotephra Layers

    Science.gov (United States)

    McCanta, M. C.; Thomson, B. J.; Fisher, E.

    2014-12-01

    Continually accumulating marine sediments incorporate tephra layers within their depositional record that can be linked to individual explosive volcanic events. These layers can range from several meters in thickness, to discrete layers invisible to the naked eye (cryptotephra). Identification of cryptotephra layers is paramount for complete characterization of the eruptive record of a volcanic center, not just the largest eruptive events. However, cryptotephra recognition is hampered by their small volume in most drill cores. A non-destructive method to distinguish tephra layers, particularly those of a high silica nature which may not be readily detectable with magnetic methods, is visible/near-infrared (Vis/NIR) spectroscopy. The Vis/NIR region of the light spectrum contains strong absorption features due to charge-transfer absorptions in transition metals (dominated by iron) and vibration and overtone bands due to hydroxyl and water (including near 1.4 ?m, 1.9 ?m, and 2.2-2.5 ?m). The exact position and nature of these bands provide a means to identify various carbonate-, hydroxyl-, iron-, phyllosilicate-, sulfate-, and water-bearing minerals (e.g., Pieters and Englert, 1993). We produced a series of mixtures of hemipelagic sediment and tephra which were used to identify band positions and features which strongly correlate with the presence of tephra (see figure). The addition of ~15-20 wt.% tephra to a sediment results in recognizable spectral changes. The mixture data was used to create a MATLAB program to run unknown sample analyses through. We then used an ASD FieldSpec to collect Vis/NIR data (0.39-2.5 ?m) on the upper 10 m of core collected during IODP 340 (U1396C) off the coast of Montserrat at 0.5 cm resolution and applied our tephra recognition program to this data. We identified 29 potential cryptotephra layers in the 10 m analyzed. Dissolution techniques are being completed to corroborate the spectral data.

  3. Improved low visibility forecasts at Amsterdam Airport

    Science.gov (United States)

    Wijngaard, J.; Vogelezang, D.; Maat, N.; van Bruggen, H.

    2009-09-01

    Accurate, reliable and unambiguous information concerning the actual and expected (low) visibility conditions at Amsterdam Airport Schiphol is very important for the available operational flow capacity. Therefore visibility forecast errors can have a negative impact on safety and operational expenses. KNMI has performed an update of the visibility forecast system in close collaboration with the main users of the forecasts (Air Traffic Control, the airport authorities and KLM airlines). This automatic forecasting system consists of a Numerical Weather Prediction Model (Hirlam) with a statistical post processing module on top of it. Output of both components is supplied to a human forecaster who issues a special probabilistic forecast bulletin. This bulletin is tailored to the specific requirements of the airport community. The improvements made to the forecast system are twofold: 1) In addition to the Meteorological Optical Range (MOR) values, RVR (Runway Visual Range) is forecasted. Since RVR depends on both MOR and the local Background Luminance, a (deterministic) statistical forecast for the latter has been developed. 2) Another improvement was achieved by calculating joint probabilities for specific combinations of visibility and cloud base height for thresholds which have direct impact on the flow capacity at the airport. The development of this new visibility forecast will be presented briefly. Also a few verification results will be shown to demonstrate the improvements made. Finally, the importance of explaining the user the use of the forecast information, in relation to their decision making process, will be discussed. For that reason, a simple guideline model to make a cost-optimal choice will be introduced.

  4. Quantitative study on appearance of microvessels in spectral endoscopic imaging

    Science.gov (United States)

    Yamaguchi, Hiroshi; Saito, Takaaki; Shiraishi, Yasushi; Arai, Fumihito; Morimoto, Yoshinori; Yuasa, Atsuko

    2015-03-01

    Increase in abnormal microvessels in the superficial mucosa is often relevant to diagnostic findings of neoplasia in digestive endoscopy; hence, observation of superficial vasculature is crucial for cancer diagnosis. To enhance the appearance of such vessels, several spectral endoscopic imaging techniques have been developed, such as narrow-band imaging and blue laser imaging. Both techniques exploit narrow-band blue light for the enhancement. The emergence of such spectral imaging techniques has increased the importance of understanding the relation of the light wavelength to the appearance of superficial vasculature, and thus a new method is desired for quantitative analysis of vessel visibility in relation to the actual structure in the tissue. Here, we developed microvessel-simulating phantoms that allowed quantitative evaluation of the appearance of 15-?m-thick vessels. We investigated the relation between the vascular contrast and light wavelength by the phantom measurements and also verified it in experiments with swine, where the endoscopically observed vascular contrast was investigated together with its real vascular depth and diameter obtained by microscopic observation of fluorescence-labeled vessels. Our study indicates that changing the spectral property even in the wavelength range of blue light may allow selective enhancement of the vascular depth for clinical use.

  5. Retrieval of spheroid particle size distribution from spectral extinction data in the independent mode using PCA approach

    International Nuclear Information System (INIS)

    An improved anomalous diffraction approximation (ADA) method is presented for calculating the extinction efficiency of spheroids firstly. In this approach, the extinction efficiency of spheroid particles can be calculated with good accuracy and high efficiency in a wider size range by combining the Latimer method and the ADA theory, and this method can present a more general expression for calculating the extinction efficiency of spheroid particles with various complex refractive indices and aspect ratios. Meanwhile, the visible spectral extinction with varied spheroid particle size distributions and complex refractive indices is surveyed. Furthermore, a selection principle about the spectral extinction data is developed based on PCA (principle component analysis) of first derivative spectral extinction. By calculating the contribution rate of first derivative spectral extinction, the spectral extinction with more significant features can be selected as the input data, and those with less features is removed from the inversion data. In addition, we propose an improved Tikhonov iteration method to retrieve the spheroid particle size distributions in the independent mode. Simulation experiments indicate that the spheroid particle size distributions obtained with the proposed method coincide fairly well with the given distributions, and this inversion method provides a simple, reliable and efficient method to retrieve the spheroid particle size distributions from the spectral extinction data. -- Highlights: ? Improved ADA is presented for calculating the extinction efficiency of spheroids. ? Selection principle about spectral extinction data is developed based on PCA. ? Improved Tikhonov iteration method is proposed to retrieve the spheroid PSD.

  6. Hybridization of optical plasmonics with terahertz metamaterials to create multi-spectral filters

    OpenAIRE

    McCrindle, I.J.H.; Grant, J.; Drysdale, T.D.; D. R. S. Cumming

    2013-01-01

    Multi-spectral imaging systems typically require the cumbersome integration of disparate filtering materials in order to work simultaneously in multiple spectral regions. We show for the first time how a single nano-patterned metal film can be used to filter multi-spectral content from the visible, near infrared and terahertz bands by hybridizing plasmonics and metamaterials. Plasmonic structures are well-suited to the visible band owing to the resonant dielectric properties of metals, wherea...

  7. Validation of UV-visible aerosol optical thickness retrieved from spectroradiometer measurements

    Directory of Open Access Journals (Sweden)

    C. Brogniez

    2008-02-01

    Full Text Available Global and diffuse UV-visible solar irradiances are routinely measured since 2003 with a spectroradiometer operated by the Laboratoire d'Optique Atmosphérique (LOA located in Villeneuve d'Ascq, France. The analysis of the direct irradiance derived by cloudless conditions enables retrieving the aerosol optical thickness (AOT spectrum in the 330–450 nm range. The site hosts also sunphotometers from the AERONET/PHOTONS network performing routinely measurements of the AOT at several wavelengths. On one hand, comparisons between the spectroradiometer and the sunphotometer AOT at 440 nm as well as, when available, at 340 and 380 nm, show good agreement. On the other hand, the AOT's spectral variations have been compared using the Angström exponents derived from AOT data at 340 and 440 nm for both instruments. The comparisons show that this parameter is difficult to retrieve accurately due to the small wavelength range and due to the weak AOT values. Thus, AOT derived at wavelengths outside the spectroradiometer range by means of an extrapolation using the Angström parameter would be of poor value, whereas, spectroradiometer's spectral AOT could be used for direct validation of other AOT, such as those provided by satellite instruments.

  8. Feasibility of radiation dosimetry with phosphorus-doped optical fibers in the ultraviolet and visible domain

    International Nuclear Information System (INIS)

    We investigated the feasibility of using phosphorus-doped optical fibers to monitor the levels of deposited dose during an irradiation. For this, we characterized their spectral and time dependence of the steady state 10 keV X-ray radiation-induced attenuation in the ultraviolet and visible range of wavelengths (200 nm-900 nm). Their radiation sensitivity is very high with losses exceeding 10 dB m-1 for doses larger than 10 Gy and wavelengths shorter than 550 nm. Our results reveal a sub linear dose dependence of the induced losses that also depends on the dose rate (1 Gy s-1 Gy s-1) between 350 nm and 900 nm. For this spectral domain, excess of attenuation is due to the phosphorus oxygen-hole centers. P2 defects are responsible for the induced losses around 300 nm that linearly increase with the dose at least until 1 kGy and without dose rate effect. We measured no noticeable influence of the temperature (5 degrees C - 50 degrees C) on the radiation-induced attenuation in the studied spectral domain. Our study shows that dosimetry with phosphorus-doped fibers seems possible in the ultraviolet (around 300 nm) with a sensitivity enhanced by a factor ? 100 compared to the one observed in the infrared region (? 900 nm). (authors)

  9. Visible-frequency hyperbolic metasurface

    Science.gov (United States)

    High, Alexander A.; Devlin, Robert C.; Dibos, Alan; Polking, Mark; Wild, Dominik S.; Perczel, Janos; de Leon, Nathalie P.; Lukin, Mikhail D.; Park, Hongkun

    2015-06-01

    Metamaterials are artificial optical media composed of sub-wavelength metallic and dielectric building blocks that feature optical phenomena not present in naturally occurring materials. Although they can serve as the basis for unique optical devices that mould the flow of light in unconventional ways, three-dimensional metamaterials suffer from extreme propagation losses. Two-dimensional metamaterials (metasurfaces) such as hyperbolic metasurfaces for propagating surface plasmon polaritons have the potential to alleviate this problem. Because the surface plasmon polaritons are guided at a metal-dielectric interface (rather than passing through metallic components), these hyperbolic metasurfaces have been predicted to suffer much lower propagation loss while still exhibiting optical phenomena akin to those in three-dimensional metamaterials. Moreover, because of their planar nature, these devices enable the construction of integrated metamaterial circuits as well as easy coupling with other optoelectronic elements. Here we report the experimental realization of a visible-frequency hyperbolic metasurface using single-crystal silver nanostructures defined by lithographic and etching techniques. The resulting devices display the characteristic properties of metamaterials, such as negative refraction and diffraction-free propagation, with device performance greatly exceeding those of previous demonstrations. Moreover, hyperbolic metasurfaces exhibit strong, dispersion-dependent spin-orbit coupling, enabling polarization- and wavelength-dependent routeing of surface plasmon polaritons and two-dimensional chiral optical components. These results open the door to realizing integrated optical meta-circuits, with wide-ranging applications in areas from imaging and sensing to quantum optics and quantum information science.

  10. Spectral Variability of FSRQs

    Indian Academy of Sciences (India)

    Minfeng Gu; Y. L. Ai

    2011-03-01

    The optical variability of 29 flat spectrum radio quasars in SDSS Stripe 82 region are investigated by using DR7 released multi-epoch data. All FSRQs show variations with overall amplitude ranging from 0.24 mag to 3.46 mag in different sources. About half of FSRQs show a bluer-when-brighter trend, which is commonly observed for blazars. However, only one source shows a redder-when-brighter trend, which implies it is rare in FSRQs. In this source, the thermal emission may be responsible for the spectral behaviour.

  11. Design of cloaking metamaterials using spectral representation theory

    Science.gov (United States)

    Lai Leung, Lai; Fung, Tai Hang; Yu, Kin Wah

    2008-03-01

    Controlling the propagation of electromagnetic (EM) waves, for instance in cloaking problem, has become an important topic in nanophotonics. So far, following the cloaking model proposed by Pendry et al. [1], the experimental realization was only limited to the microwave region [2]. Since practical application lies in the visible range, we have extended the investigation to that region by utilizing nanocomposites with reference to the material parameters proposed by Pendry et al. and Shalaev et al. [3]. The calculations can be made much simpler by invoking the spectral representation theory [4]. The loss and dispersion effects, as well as the propagation of EM waves are assessed for the designed cloaking models in order to investigate the cloaking performance. Further analyses show that our models can accomplish the desired cloaking effect in the visible range. Moreover, the loss and dispersion effects are found to be small and acceptable.[1] J. B. Pendry, D. Schurig, and D. R. Smith, Science 312, 1780 (2006). [2] D. Schurig, J. J. Mock, B. J. Justice, S. A. Cummer, J. B. Pendry, A. F. Starr, D. R. Smith Science 314, 5801 (2006). [3] Wenshan Cai, Uday K. Chettiar, Alexander V. Kildishev and Vladimir M. Shalaev, Nature photonics 1 (2007). [4] L. Dong, Mikko Karttunen, K. W. Yu, Phys. Rev. E 72, 016613 (2005).

  12. Effect of the surface roughness on the spectral distribution of photoemission current at the silver/solution contact

    Science.gov (United States)

    Kostecki, R.; Augustynski, J.

    1995-05-01

    The experimental evidence gathered pointed at the optically excited surface plasmons as the origin of the exceptionally strong electron emission from silver in the CO2 containing aqueous solutions. The reported measurements verified in particular that electrochemical roughening of the Ag surface, identical to that normally used before recording surface enhancement of Raman scattering (SERS) spectra, causes the strong enhancement of the photoemission current in the near-UV and, particularly, in the visible range. Moreover, roughening procedure was observed to extend the spectral range of optical excitations of surface plasmons on Ag into the wavelengths most often employed in SERS experiments.

  13. The visible spectrum of Pluto: secular and longitudinal variation

    Science.gov (United States)

    Lorenzi, Vania; Pinilla-Alonso, Noemí; Emery, Joshua P.; Licandro, Javier; Cruikshank, Dale P.; Grundy, Will; Binzel, Richard P.

    2015-11-01

    Continuous near-infrared spectroscopic observations during the last 30 years enabled the characterization of the Pluto's surface and the study of its variability. Nevertheless, only few data are available in the visible range, where the nature of the complex-organics can be studied.For this reason, we started an observational campaign to obtain the Pluto's relative reflectance in the visible range, with the aim of characterizing the different components of its surface, and providing ground based observations in support of the New Horizons mission. We observed Pluto on six nights in 2014, with the imager/spectrograph ACAM@WHT (La Palma, Spain). We obtained six spectra in the 0.40 – 0.93 µm range, that covered a whole Pluto's rotational period (6.4 days).To study longitudinal variations, we computed for all the spectra the spectral slope, and the position and the depth of the methane ice absorption bands. Also, to search for secular or seasonal variations we compared our data with previously published results.All the spectra present a red slope, indicating the presence of complex organics on Pluto's surface, and show the methane ice absorption bands between 0.73 and 0.90 ?m. We also report the detection of the CH4 absorption band at 0.62 ?m, already detected in the spectra of Makemake and Eris. The measurement of the band depth at 0.62 ?m in the new spectra of Pluto, and in the spectra of Makemake and Eris, permits us to estimate the Lambert coefficient, not measured yet at this wavelength, at a temperature of 30 K and 40 K.We find that all the CH4 bands present a blue shift. This shift is minimum at the Charon-facing hemisphere, where the CH4 is also more abundant, indicating a higher degree of saturation of CH4 in the CH4:N2 dilution at this hemisphere.Comparing with data in the literature, we found that the longitudinal and secular variations of the parameters measured in our spectra are in accordance with previous results and with the distribution of the dark and bright material as showed by the Pluto's albedo maps from New Horizons.In 2015, new observations were run quasi-simultaneously with the New Horizons flyby at 10 different Pluto longitudes (July 3 to 14) . The data are currently being reduced.

  14. Preliminary design of the full-Stokes UV and visible spectropolarimeter for UVMag/Arago

    Science.gov (United States)

    Pertenais, Martin; Neiner, Coralie; Parès, Laurent; Petit, Pascal; Snik, Frans; van Harten, Gerard

    2015-10-01

    The UVMag consortium proposed the space mission project Arago to ESA at its M4 call. Arago is dedicated to the study of the dynamic 3D environment of stars and planets. This space mission will be equipped with a high-resolution spectropolarimeter working from 119 to 888 nm. A preliminary optical design of the whole instrument has been prepared and is presented here. The design consists of the telescope, the instrument itself, and the focusing optics. Considering not only the scientific requirements, but also the cost and size constraints to fit an M-size mission, the telescope has a 1.3 m diameter primary mirror and is a classical Cassegrain-type telescope that allows a polarization-free focus. The polarimeter is placed at this Cassegrain focus. This is the key element of the mission and the most challenging one to be designed. The main challenge lies in the huge spectral range offered by the instrument; the polarimeter has to deliver the full Stokes vector with a high precision from the FUV (119 nm) to the NIR (888 nm). The polarimeter module is then followed by a high-resolution echelle-spectrometer achieving a resolution of 35000 in the visible range and 25000 in the UV. The two channels are separated after the echelle grating, allowing specific cross-dispersion and focusing optics for the UV and the visible ranges. Considering the large field of view and the high numerical aperture, the focusing optics for both the UV and the visible channels is a Three-Mirror-Anastigmatic (TMA) telescope, needed to focus the various wavelengths and many orders onto the detectors.

  15. Spectrally Resolved Two-Colour Femtosecond Photon Echoes

    Science.gov (United States)

    van Dao, Lap; Lincoln, Craig; Lowe, Martin; Hannaford, Peter

    We describe a potentially powerful multidimensional technique based on spectrally resolved 2-colour 3-pulse photon echoes in the visible region for probing vibrational and electronic dynamics in complex molecular systems on a femtosecond time scale. Recording of the spectrum of the photon echo signals yields detailed information about the temporal evolution of the amplitude of the nonlinear polarization induced in the sample by the three temporally separated femtosecond laser pulses. Suitable selection of the wavelengths of the three laser pulses allows different sets of energy levels to be selected and the dynamics of the ground and excited states to be separated and investigated. The technique is applied to studies of dynamical processes in a wide range of molecular systems, including the dye molecules Rhodamine 101, Rhodamine B and cresyl violet; the blue emitting semiconductor gallium nitride; semiconductor CdTe/ZnSe quantum dots; and the biomolecules myoglobin and carbonmonoxy myoglobin.

  16. Multi-spectral materials: hybridisation of optical plasmonic filters and a terahertz metamaterial absorber

    OpenAIRE

    McCrindle, Iain J.H.; Grant, James; Drysdale, Timothy D.; Cumming, David R.S.

    2014-01-01

    Multi-spectral materials, using hybridised plasmonic and metamaterial structures, can simultaneously exhibit unique resonant phenomena over several decades of wavelengths. A multi-spectral material that combines a plasmonic colour filter array and a terahertz metamaterial absorber into a single material is a promising prospect for a coaxial multi-spectral imager operating in the visible, near IR, and terahertz wavebands.

  17. Preliminary Geologic/spectral Analysis of LANDSAT-4 Thematic Mapper Data, Wind River/bighorn Basin Area, Wyoming

    Science.gov (United States)

    Lang, H. R.; Conel, J. E.; Paylor, E. D.

    1984-01-01

    A LIDQA evaluation for geologic applications of a LANDSAT TM scene covering the Wind River/Bighorn Basin area, Wyoming, is examined. This involves a quantitative assessment of data quality including spatial and spectral characteristics. Analysis is concentrated on the 6 visible, near infrared, and short wavelength infrared bands. Preliminary analysis demonstrates that: (1) principal component images derived from the correlation matrix provide the most useful geologic information. To extract surface spectral reflectance, the TM radiance data must be calibrated. Scatterplots demonstrate that TM data can be calibrated and sensor response is essentially linear. Low instrumental offset and gain settings result in spectral data that do not utilize the full dynamic range of the TM system.

  18. Visible Imaging Fourier Transform Spectrometer: Design and Calibration

    Energy Technology Data Exchange (ETDEWEB)

    Wishnow, E H; Wurtz, R; Blais-Ouellette, S; Cook, K H; Carr, D; Lewis, I; Grandmont, F; Stubbs, C W

    2002-09-19

    We present details of the design, operation and calibration of an astronomical visible-band imaging Fourier transform spectrometer (IFTS). This type of instrument produces a spectrum for every pixel in the field of view where the spectral resolution is flexible. The instrument is a dual-input/dual-output Michelson interferometer coupled to the 3.5 meter telescope at the Apache Point Observatory. Imaging performance and interferograms and spectra from calibration sources and standard stars are discussed.

  19. Using Delta-Sigma Modulators in Visible Light OFDM Systems

    OpenAIRE

    Yu, Zhenhua; Redfern, Arthur J.; Zhou, G. Tong

    2014-01-01

    Visible light communications (VLC) are motivated by the radio-frequency (RF) spectrum crunch and fast-growing solid-state lighting technology. VLC relies on white light emitting diodes (LEDs) to provide communication and illumination simultaneously. Simple two-level on-off keying (OOK) and pulse-position modulation (PPM) are supported in IEEE standard due to their compatibility with existing constant current LED drivers, but their low spectral efficiency have limited the ach...

  20. Multi-Spectral Solar Telescope Array

    Science.gov (United States)

    Walker, Arthur B. C., Jr.; Lindblom, Joakim F.; O'Neal, Ray H.; Allen, Maxwell J.; Barbee, Troy W., Jr.; Hoover, Richard B.

    1990-01-01

    This paper descibes the design and the characteristics of the Multispectral Solar Telescope Array (MSSTA), a new rocket spectroheliograph to be launched in August 1990. The MSSTA includes five multilayer Ritchey-Chretien telescopes covering the spectral range 150-300 A and eight multilayer Herschelian telescopes covering the spectral range 40-1550 A, making it possible to obtain spectrohelipgrams over the soft X-ray/extreme UV/FUV spectral range. The MSSTA is expected to obtain information regarding the structure and dynamics of the solar atmosphere in the temperature range 10 to the 4th-10 to the 7th K.

  1. A single-layer wide-angle negative-index metamaterial at visible freque

    Energy Technology Data Exchange (ETDEWEB)

    Burgos, Stanley P. [California Inst. of Technology (CalTech), Pasadena, CA (United States); de Waele, Rene [FOM Inst. AMOLF, Amersterdam (Netherlands); Polman, Albert [FOM Inst. AMOLF, Amersterdam (Netherlands); Atwater, Harry A. [California Inst. of Technology (CalTech), Pasadena, CA (United States)

    2010-04-18

    Metamaterials are materials with artificial electromagnetic properties defined by their sub-wavelength structure rather than their chemical composition. Negative-index materials (NIMs) are a special class of metamaterials characterized by an effective negative index that gives rise to such unusual wave behaviour as backwards phase propagation and negative refraction. These extraordinary properties lead to many interesting functions such as sub-diffraction imaging and invisibility cloaking. So far, NIMs have been realized through layering of resonant structures, such as split-ring resonators, and have been demonstrated at microwave to infrared frequencies over a narrow range of angles-of-incidence and polarization. However, resonant-element NIM designs suffer from the limitations of not being scalable to operate at visible frequencies because of intrinsic fabrication limitations, require multiple functional layers to achieve strong scattering and have refractive indices that are highly dependent on angle of incidence and polarization. Here we report a metamaterial composed of a single layer of coupled plasmonic coaxial waveguides that exhibits an effective refractive index of -2 in the blue spectral region with a figure-of-merit larger than 8. The resulting NIM refractive index is insensitive to both polarization and angle-of-incidence over a ±50° angular range, yielding a wide-angle NIM at visible frequencies.

  2. A single-layer wide-angle negative-index metamaterial at visible frequencies.

    Science.gov (United States)

    Burgos, Stanley P; de Waele, Rene; Polman, Albert; Atwater, Harry A

    2010-05-01

    Metamaterials are materials with artificial electromagnetic properties defined by their sub-wavelength structure rather than their chemical composition. Negative-index materials (NIMs) are a special class of metamaterials characterized by an effective negative index that gives rise to such unusual wave behaviour as backwards phase propagation and negative refraction. These extraordinary properties lead to many interesting functions such as sub-diffraction imaging and invisibility cloaking. So far, NIMs have been realized through layering of resonant structures, such as split-ring resonators, and have been demonstrated at microwave to infrared frequencies over a narrow range of angles-of-incidence and polarization. However, resonant-element NIM designs suffer from the limitations of not being scalable to operate at visible frequencies because of intrinsic fabrication limitations, require multiple functional layers to achieve strong scattering and have refractive indices that are highly dependent on angle of incidence and polarization. Here we report a metamaterial composed of a single layer of coupled plasmonic coaxial waveguides that exhibits an effective refractive index of -2 in the blue spectral region with a figure-of-merit larger than 8. The resulting NIM refractive index is insensitive to both polarization and angle-of-incidence over a +/-50 degree angular range, yielding a wide-angle NIM at visible frequencies. PMID:20400955

  3. A single-layer wide-angle negative-index metamaterial at visible frequencies

    Science.gov (United States)

    Burgos, Stanley P.; de Waele, Rene; Polman, Albert; Atwater, Harry A.

    2010-05-01

    Metamaterials are materials with artificial electromagnetic properties defined by their sub-wavelength structure rather than their chemical composition. Negative-index materials (NIMs) are a special class of metamaterials characterized by an effective negative index that gives rise to such unusual wave behaviour as backwards phase propagation and negative refraction. These extraordinary properties lead to many interesting functions such as sub-diffraction imaging and invisibility cloaking. So far, NIMs have been realized through layering of resonant structures, such as split-ring resonators, and have been demonstrated at microwave to infrared frequencies over a narrow range of angles-of-incidence and polarization. However, resonant-element NIM designs suffer from the limitations of not being scalable to operate at visible frequencies because of intrinsic fabrication limitations, require multiple functional layers to achieve strong scattering and have refractive indices that are highly dependent on angle of incidence and polarization. Here we report a metamaterial composed of a single layer of coupled plasmonic coaxial waveguides that exhibits an effective refractive index of -2 in the blue spectral region with a figure-of-merit larger than 8. The resulting NIM refractive index is insensitive to both polarization and angle-of-incidence over a +/-50? angular range, yielding a wide-angle NIM at visible frequencies.

  4. Visibility regimes in mediatized publicness

    Directory of Open Access Journals (Sweden)

    Samuel Mateus

    2014-12-01

    Full Text Available Considering the relationship between politics, media and publicness, this paper ponders the consequences of visibility in the political field. Identifying some of its existing regimes, it will posit that today visibility plays an ambivalent function to politics: it can simultaneously operate as a synoptic monitoring and control of politicians; and at the same time it may stand as an opportunity to build a charismatic leadership. In fact, political visibilities are now negotiated between the boundaries of private and public realms, and they can take the form of a risk, or an opportunity to build on a charismatic leadership.

  5. Selective spectral detection of continuum terahertz radiation

    Science.gov (United States)

    Kaufmann, P.; Marcon, R.; Marun, A.; Kudaka, A. S.; Bortolucci, E.; Zakia, M. B.; Diniz, J. A.; Cassiano, M. M.; Pereyra, P.; Godoy, R.; Timofeevsky, A. V.; Nikolaev, V. A.; Pereira Alves da Silva, A. M.; Fernandes, L. O. T.

    2010-07-01

    The knowledge of THz continuum spectra is essential to investigate the emission mechanisms by high energy particle acceleration processes. Technical challenges appear for obtaining selective spectral sensing in the far infrared range to diagnose radiation produced by solar flare burst emissions measured from space as well as radiation produced by high energy electrons in laboratory accelerators. Efforts are been carried out intended for the development of solar flare high cadence radiometers at two THz frequencies to operate outside the terrestrial atmosphere (i.e. at 3 and 7 THz). One essential requirement is the efficient suppression of radiation in the visible and near infrared. Experimental setups have been assembled for testing (a) THz transmission of "low-pass" filters: rough surface mirrors; membranes Zitex G110G and TydexBlack; (b) a fabricated 2.4 THz resonant grid band-pass filter transmission response for polarization and angle of incidence; (c) radiation response from distinct detectors: adapted commercial microbolometer array using HRFZ-Si window, pyroelectric module and Golay cell; qualitative detection of solar radiation at a sub-THz frequency has been tested with a microbolometer array placed at the focus of the 1.5 m reflector for submillimeter waves (SST) at El Leoncito, Argentina Andes.

  6. General approach to high power, coherent visible and ultraviolet light sources

    DEFF Research Database (Denmark)

    Andersen, Martin Thalbitzer

    spectral region require nonlinear materials with a transparency range extending into the ultraviolet, the ability to sustain high photon energies and with the ability to obtain phasematching for the desired nonlinear conversion process. In this project experiments are conducted using three differently co...... can easily be frequency doubled in a single pass configuration, therefore the nonlinear cavity dumping approach is suggested for the generation of 340nm UV light, using 532nm pulses to cavity dump a 946nm Nd:YAG laser. Furthermore experiments are conducted tripling a Q-switched 1064nm laser to 355nm...... by cascaded second harmonic and sum frequency generation using periodically poled KTP and BBO for the SHG and SFG process, respectively. The 355nm light is used to promote different photo induced reactions. The main limitation of reaching any desired wavelength in the visible spectrum using sum...

  7. High-power fiber-coupled 100W visible spectrum diode lasers for display applications

    Science.gov (United States)

    Unger, Andreas; Küster, Matthias; Köhler, Bernd; Biesenbach, Jens

    2013-02-01

    Diode lasers in the blue and red spectral range are the most promising light sources for upcoming high-brightness digital projectors in cinemas and large venue displays. They combine improved efficiency, longer lifetime and a greatly improved color space compared to traditional xenon light sources. In this paper we report on high-power visible diode laser sources to serve the demands of this emerging market. A unique electro-optical platform enables scalable fiber coupled sources at 638 nm with an output power of up to 100 W from a 400 ?m NA0.22 fiber. For the blue diode laser we demonstrate scalable sources from 5 W to 100 W from a 400 ?m NA0.22 fiber.

  8. Experimental realization of a polarization-independent ultraviolet/visible coaxial plasmonic metamaterial.

    Science.gov (United States)

    van de Haar, M A; Maas, R; Schokker, H; Polman, A

    2014-11-12

    We report the experimental realization of an optical metamaterial composed of a hexagonal array of coaxial plasmonic metal/insulator/metal waveguides that shows strong polarization-independent optical mode index dispersion in the ultraviolet/blue. The metamaterial is composed of silicon coaxes with a well-defined diameter in the range of 150-168 nm with extremely thin sidewalls (13-15 nm), embedded in a silver film, fabricated using a combination of electron beam lithography, physical vapor deposition, reactive ion etching, and focused ion beam polishing. Using a Mach-Zehnder interferometer the phase advance is measured on several metamaterial samples with different dimensions in the UV/visible part of the spectrum. For all geometries the spectral features as well as the geometry dependence of the data correspond well with numerical finite-difference time domain simulations and the calculated waveguide dispersion diagram, showing a negative mode index between 440 and 500 nm. PMID:25310377

  9. UV-visible luminescence properties of the broad-band Yb:CALGO laser crystal

    Science.gov (United States)

    Jaffres, A.; Sharma, S. K.; Loiseau, P.; Viana, B.; Doualan, J. L.; Moncorgé, R.

    2015-03-01

    Yb:CALGO is now recognized to exhibit outstanding properties for the production of high-power and ultra-short laser pulses in the near infrared spectral range. However, various UV-visible absorption bands can be also observed due to different types of charge transfer mechanisms. Some of them are assigned to the formation of color centers due to small polarons and others to O2-?Yb3+ ligand-to-metal charge transfer (LMCT) transitions. The former can be removed by using adequate thermal treatments. The latter are intrinsic and they are very intense with cross sections of about two orders of magnitude larger that the near infrared ones. In fact, such LMCT absorption bands are responsible for relatively large changes of ionic polarizabilities and to non-negligible pseudo-nonlinear changes of refractive indices which should certainly affect the laser properties of Yb:CALGO at high pump power levels.

  10. Incremental Visualizer for Visible Objects

    DEFF Research Database (Denmark)

    Bukauskas, Linas; Bøhlen, Michael Hanspeter

    This paper discusses the integration of database back-end and visualizer front-end into a one tightly coupled system. The main aim which we achieve is to reduce the data pipeline from database to visualization by using incremental data extraction of visible objects in a fly-through scenarios. We...... also argue that passing only relevant data from the database will substantially reduce the overall load of the visualization system. We propose the system Incremental Visualizer for Visible Objects (IVVO) which considers visible objects and enables incremental visualization along the observer movement...... path. IVVO is the novel solution which allows data to be visualized and loaded on the fly from the database and which regards visibilities of objects. We run a set of experiments to convince that IVVO is feasible in terms of I/O operations and CPU load. We consider the example of data which uses...

  11. Visible spectroscopy of the new ESO Large Program on trans-Neptunian objects and Centaurs: final results

    CERN Document Server

    Fornasier, S; de Bergh, C; Alvarez-Candal, A; DeMeo, F; Merlin, F; Perna, D; Guilbert, A; Delsanti, A; Dotto, E; Doressoundiram, A

    2009-01-01

    A second large programme (LP) for the physical studies of TNOs and Centaurs, started at ESO Cerro Paranal on October 2006 to obtain high-quality data, has recently been concluded. In this paper we present the spectra of these pristine bodies obtained in the visible range during the last two semesters of the LP. We investigate the spectral behaviour of the TNOs and Centaurs observed, and we analyse the spectral slopes distribution of the full data set coming from this LP and from the literature. We computed the spectral slope for each observed object, and searched for possible weak absorption features. A statistical analysis was performed on a total sample of 73 TNOs and Centaurs to look for possible correlations between dynamical classes, orbital parameters, and spectral gradient. We obtained new spectra for 28 bodies, 15 of which were observed for the first time. All the new presented spectra are featureless, including 2003 AZ84, for which a faint and broad absorption band possibly attributed to hydrated sil...

  12. Generation of high-power femtosecond supercontinua in the near-IR spectral range using broadband parametric frequency conversion in LBO and DCDA crystals pumped at λ = 620 nm

    International Nuclear Information System (INIS)

    The pump wavelength of parametric amplifiers based on CLBO, DCDA and LBO crystals and pumped by the second harmonic of a femtosecond Cr : forsterite laser (620 nm) is close to optimal for broadband amplification because of the proximity of group velocities of interacting pulses. Injection of a broadband continuum into the range of the signal-wave gain in LBO and DCDA parametric amplifiers, pumped at λ = 620 nm, leads to generation of broadband femtosecond pulses with a spectrum ranging from 1050 to 1600 nm and peak powers up to 20 MW. (nonlinear optical phenomena)

  13. Generation of high-power femtosecond supercontinua in the near-IR spectral range using broadband parametric frequency conversion in LBO and DCDA crystals pumped at λ = 620 nm

    Science.gov (United States)

    Podshivalov, A. A.; Potemkin, F. V.; Sidorov-Biryukov, D. A.

    2014-09-01

    The pump wavelength of parametric amplifiers based on CLBO, DCDA and LBO crystals and pumped by the second harmonic of a femtosecond Cr : forsterite laser (620 nm) is close to optimal for broadband amplification because of the proximity of group velocities of interacting pulses. Injection of a broadband continuum into the range of the signal-wave gain in LBO and DCDA parametric amplifiers, pumped at λ = 620 nm, leads to generation of broadband femtosecond pulses with a spectrum ranging from 1050 to 1600 nm and peak powers up to 20 MW.

  14. Generation of high-power femtosecond supercontinua in the near-IR spectral range using broadband parametric frequency conversion in LBO and DCDA crystals pumped at λ = 620 nm

    Energy Technology Data Exchange (ETDEWEB)

    Podshivalov, A A; Sidorov-Biryukov, D A [International Laser Center, M. V. Lomonosov Moscow State University, Moscow (Russian Federation); Potemkin, F V [Department of Physics, M.V. Lomonosov Moscow State University (Russian Federation)

    2014-09-30

    The pump wavelength of parametric amplifiers based on CLBO, DCDA and LBO crystals and pumped by the second harmonic of a femtosecond Cr : forsterite laser (620 nm) is close to optimal for broadband amplification because of the proximity of group velocities of interacting pulses. Injection of a broadband continuum into the range of the signal-wave gain in LBO and DCDA parametric amplifiers, pumped at λ = 620 nm, leads to generation of broadband femtosecond pulses with a spectrum ranging from 1050 to 1600 nm and peak powers up to 20 MW. (nonlinear optical phenomena)

  15. Vesta and the HED Meteorites: Comparison of Spectral Properties

    Science.gov (United States)

    Ammannito, E.; De Sanctis, M. C.; Fonte, S.; Magni, G.; Capaccioni, F.; Tosi, F.; Capria, M. T.; Blewett, D.; Combe, J. P.; Farina, M.; McCoord, T. B.; Mittlefehldt, D. W.; Palomba, E.; McSween, H.; Pieters, C.; Sunshine, J.; Titus, T. N.; Toplis, M.; Russell, C. T.; Raymond, C. A.

    2012-01-01

    We present the main results obtained comparing the visible-near infrared (VIS-NIR) spectra Vesta s surface with howardites, eucrites, diogenites (HEDs). HEDs are commonly associated with Vesta based on spectral similarities. Because of such association, much effort is being made to merge the information from HEDs as well as Vestoids with that from Vesta to characterize the lithologic diversity of the surface of this asteroid and to infer clues regarding its thermal history. The Dawn spacecraft, orbiting around Vesta since July 2011, is performing detailed observations of this body and thus improving our knowledge of its properties. Dawn s scientific payload includes an imaging spectrometer, VIR-MS, sensitive to the VIS-NIR spectral range. VIR-MS began acquiring spectra during the approach phase that started in May 2011 and will continue its observations through July 2012 when the spacecraft will depart Vesta to travel to Ceres. The observations are uniformly distributed in latitude and longitude, allowing a global view of Vesta s crustal spectral properties. Using the information provided by VIR spectra, we studied the distribution of the spectral heterogeneities on the surface and used our findings to perform a comparison with HED spectra in the VIS-NIR spectral range searching for analogies and/or incompatibilities. In our analysis, we utilized a method to compare the results obtained at microscopic scale on HED samples and the one obtained at macroscopic scale on the surface of Vesta. The intent of this study is to improve our understanding of the connection between Vesta and the HEDs, which is one of the primary Dawn scientific objectives. Dawn VIR spectra are characterized by pyroxene absorptions and most of the surface materials exhibit howardite-like spectra. However, some large areas can be interpreted to be material richer in diogenite (based on pyroxenes band depths and band centers) and some others like eucrite-rich howardite terrains. In particular, VIR data strongly indicate in the south polar region (Rheasilvia) the presence of Mg-pyroxene-rich terrains. The hypothesis that Vesta is the HED parent body is consistent with, and strengthened by, the geologic and spectral context for pyroxene distribution provided by VIR on Dawn.

  16. Point-focus spectral splitting solar concentrator for multiple cells concentrating photovoltaic system

    Science.gov (United States)

    Maragliano, Carlo; Chiesa, Matteo; Stefancich, Marco

    2015-10-01

    In this paper we present and experimentally validate a low-cost design of a spectral splitting concentrator for the efficient conversion of solar energy. The optical device consists of a dispersive prismatic lens made of polycarbonate designed to simultaneously concentrate solar light and split it into its spectral components. With respect to our previous implementation, this device concentrates light along two axes and generates a light pattern compatible with the dimensions of a set of concentrating photovoltaic cells, while providing a higher concentration ratio. The mathematical framework and the constructive approach used for the design are presented and the device performance is simulated using ray-tracing software. We obtain spectral separation in the visible range within a 3 × 1 cm2 area and a maximum concentration of 210× for a single wavelength. The device is fabricated by injection molding and its performance is experimentally investigated. We measure an optical transmissivity above 90% in the range 400-800 nm and we observe a spectral distribution in good accordance with simulations. Our results demonstrate the feasibility of the device for cost effective high efficiency concentrated photovoltaic systems.

  17. Methods for measuring the spectral reflectivity of advanced materials at high temperature

    International Nuclear Information System (INIS)

    For investigation in the domain of advanced materials as well as for new technologies there is an urgent need for knowledge of the spectral reflectivity of the materials specially at high temperatures. However the methods available are mostly intended for measuring the model materials with specular or diffuse reflection surface. This is not quite correct since advanced materials have mixed specular diffuse reflection surfaces. New methods for reflectivity measurements of materials in the visible, near and middle infrared range at high temperature, regardless of surface texture, have been developed. The advantages of the methods proposed are as flows: (a) the facility of performing the reflectivity measurements for materials with mixed specular diffuse reflectance; (b) wide spectral range 0,38-8 micro m; (c) wide temperature range 300-3000 K; (d) high accuracy and rapid measurements. The methods are based on the following principals (i) Diffuse irradiation of the sample surface and the use of Helkholtz reciprocity principle to determine the directional hemispherical reflectivity ii) Pulse polychromatic probing of the sample by additional light source. The first principle excludes the influence of the angular reflection distribution of sample surface on data obtained. The second principle gives the possibility of simultaneous measurements of the reflectivity. The second principle gives the possibility of simultaneous measurements of the reflectivity in wide spectral range. On the basis of these principles for high temperature reflectometers have been developed and discussed here. (author)

  18. Recent variability of the solar spectral irradiance and its impact on climate modelling

    CERN Document Server

    Ermolli, I; de Wit, T Dudok; Krivova, N A; Tourpali, K; Weber, M; Unruh, Y C; Gray, L; Langematz, U; Pilewskie, P; Rozanov, E; Schmutz, W; Shapiro, A; Solanki, S K; Woods, T N

    2013-01-01

    The lack of long and reliable time series of solar spectral irradiance (SSI) measurements makes an accurate quantification of solar contributions to recent climate change difficult. Whereas earlier SSI observations and models provided a qualitatively consistent picture of the SSI variability, recent measurements by the SORCE satellite suggest a significantly stronger variability in the ultraviolet (UV) spectral range and changes in the visible and near-infrared (NIR) bands in anti-phase with the solar cycle. A number of recent chemistry-climate model (CCM) simulations have shown that this might have significant implications on the Earth's atmosphere. Motivated by these results, we summarize here our current knowledge of SSI variability and its impact on Earth's climate. We present a detailed overview of existing SSI measurements and provide thorough comparison of models available to date. SSI changes influence the Earth's atmosphere, both directly, through changes in shortwave (SW) heating and therefore, temp...

  19. Polarized spectral features of human breast tissues through wavelet transform and principal component analysis

    Indian Academy of Sciences (India)

    Anita Gharekhan; Ashok N Oza; M B Sureshkumar; Asima Pradhan; Prasanta K Panigrahi

    2010-12-01

    Fluorescence characteristics of human breast tissues are investigated through wavelet transform and principal component analysis (PCA). Wavelet transform of polarized fluorescence spectra of human breast tissues is found to localize spectral features that can reliably differentiate different tissue types. The emission range in the visible wavelength regime of 500–700 nm is analysed, with the excitation wavelength at 488 nm using laser as an excitation source, where flavin and porphyrin are some of the active fluorophores. A number of global and local parameters from principal component analysis of both high- and low-pass coefficients extracted in the wavelet domain, capturing spectral variations and subtle changes in the diseased tissues are clearly identifiable.

  20. Spectral dimensions from the spectral action

    CERN Document Server

    Alkofer, Natalia; Zanusso, Omar

    2014-01-01

    The generalised spectral dimension $D_s(T)$ provides a powerful tool for comparing different approaches to quantum gravity. In this work, we apply this formalism to the classical spectral actions obtained within the framework of almost-commutative geometry. Analysing the propagation of spin-0, spin-1 and spin-2 fields, we show that a non-trivial spectral dimension arises already at the classical level. The effective field theory interpretation of the spectral action yields a plateau-structures interpolating between a fixed spin-independent $D_s(T) = d_s$ for short and $D_s(T) = 4$ for long diffusion times $T$. Going beyond effective field theory the spectral dimension is completely dominated by the high-momentum properties of the spectral action, yielding $D_s(T)=0$ for all spins. Our results support earlier claims that high-energy bosons do not propagate.

  1. Determination of geographical origin of alcoholic beverages using ultraviolet, visible and infrared spectroscopy: A review

    Science.gov (United States)

    Uríčková, Veronika; Sádecká, Jana

    2015-09-01

    The identification of the geographical origin of beverages is one of the most important issues in food chemistry. Spectroscopic methods provide a relative rapid and low cost alternative to traditional chemical composition or sensory analyses. This paper reviews the current state of development of ultraviolet (UV), visible (Vis), near infrared (NIR) and mid infrared (MIR) spectroscopic techniques combined with pattern recognition methods for determining geographical origin of both wines and distilled drinks. UV, Vis, and NIR spectra contain broad band(s) with weak spectral features limiting their discrimination ability. Despite this expected shortcoming, each of the three spectroscopic ranges (NIR, Vis/NIR and UV/Vis/NIR) provides average correct classification higher than 82%. Although average correct classification is similar for NIR and MIR regions, in some instances MIR data processing improves prediction. Advantage of using MIR is that MIR peaks are better defined and more easily assigned than NIR bands. In general, success in a classification depends on both spectral range and pattern recognition methods. The main problem still remains the construction of databanks needed for all of these methods.

  2. The visible and near infrared (VNIR) spectrometer of EChO

    Science.gov (United States)

    Adriani, Alberto; Oliva, Ernesto; Piccioni, Giuseppe; Pace, Emanuele; Focardi, Mauro; Di Turi, Canio; Filacchione, Gianrico; Pancrazzi, Maurizio; Tozzi, Andrea; Ferruzzi, Debora; Del Vecchio, Ciro; Capaccioni, Fabrizio; Micela, Giusi

    2012-09-01

    The Visible and Near Infrared (VNIR) spectrometer of the EChO will cover the spectral range between 0.55 and 2.50 ?m. It has to be designed to assure a high efficiency over whole spectral range. It has to be able to observe stars with an apparent magnitude Mv= 9÷12 and able to see contrasts of the order of 10-4÷10-5 in order to measure characteristics of the exoplanets under investigation. VNIR would be a spectrometer in a cross-dispersed configuration by using a combination of a diffraction grating and a prism to spread the light in different wavelengths and in a useful number of orders of diffraction. It will use a Mercury Cadmium Telluride detector to satisfy the requirements of low thermal noise and the EChO system to operate at the working temperature of 40-45K. The instrument will be interfaced to the telescope optics by optical fibers to assure an easier coupling and an easier colocation of the instrument inside the EChO optical bench. The preliminary design of the instrument foresees a resolving power of about 330 with an entrance aperture of 2 arcsec.

  3. No-visible-scar cholecystectomy

    Directory of Open Access Journals (Sweden)

    Tadeusz M. Wróblewski

    2010-12-01

    Full Text Available Introduction: Single incision laparoscopic surgery (SILS is a laparoscopic method providing a good cosmetic effect,but requiring the application of special ports and instruments enabling the surgeon to perform the procedure.We report three-ports cholecystectomy through umbilical and suprapubic incisions performed with typical laparos -copic instruments which calls no-visible-scar cholecystectomy (NVSC.Material and methods: Twenty patients with symptomatic cholelithiasis were qualified for NVSC. Typical CO2 pneumoperitoneumwas done after umbilical skin incision. Two ports of 5 mm were inserted in the maximum externaledges of this incision. After cystic duct and cystic artery dissection the right one was exchanged for a port of 11 mm.The second incision for the 11-mm trocar for the laparoscope was done in the suprapubic median line within the hairarea.Results: Cholecystectomies were performed without any conversion to classical laparoscopic cholecystectomy (LCHor open surgery. They were not technically identical due to the gradual improvement in the access and manipulationof instruments. The time of the intervention ranged from 2 hours during the introduction of the new method to 50 minfor the last procedures. No postoperative complications were observed and all patients were discharged not later thanafter conventional LCH.Conclusions: NVSC is a three-port laparoscopic intervention performed with typical laparoscopic instruments. It ismore convenient for the surgeon than single incision LCH, because the placement of the optic in the suprapubic regiongives more space for the instruments. It also provides a very good cosmetic effect of the intervention. The describedprocedure is easy to learn and in case of technical problems additional ports can be applied (as in typical LCH.

  4. Detection of visibility conditions through use of onboard cameras

    OpenAIRE

    HAUTIERE,N; LABAYRADE,R; Aubert, D

    2005-01-01

    An atmospheric visibility measurement system capable of quantifying the most common operating range of onboard exteroceptive sensors is a key parameter in the creation of driving assistance systems. This information is then utilized to adapt sensor operations and processing or to alert the driver that the onboard assistance system is momentarily inoperative. Moreover, a system capable of either detecting the presence of fog or estimating visibility distances constitutes in itself a driving as...

  5. Visible light communication for advanced driver assistant systems

    OpenAIRE

    Kumar, Navin; Nero, Luis Alves; Rui L. Aguiar

    2009-01-01

    VIsible light communication for advanced Driver Assistant Systems (VIDAS) is an outdoor application using the visible spectrum of light emitting diodes (LED). A simple traffic light set up based on LED traffic lights for traffic information transmission has been analyzed in this paper. Various important design parameters have been optimized through intensive investigation based on gain variation over 100 m of transmission range. This process is expected to simplify the front-end receiver desi...

  6. Ultraviolet-visible transmittance techniques for rapid analysis of sugar content and soluble solids content of fresh navel orange juices

    Science.gov (United States)

    Liu, Yande; Ouyang, Aiguo; Luo, Ji; Ying, Yibin

    2005-11-01

    Sugar content (SC) and soluble solids content (SSC) are very important factors of navel orange internal quality and can be measured non-invasively by ultraviolet-visible spectroscopy techniques. The feasibility and methods of ultraviolet-visible spectroscopic techniques for rapid quantifying SC and SSC of navel orange fresh juices was investigated by its spectral transmittance. A total 55 juice samples were used to develop the calibration and prediction models. Different spectra correction algorithms (constant, multiplicative signal correction (MSC) and standard normal variate (SNV) were compared in our work. Three different kinds of mathematical spectra treatments (original, first derivative and second derivative) of spectra in the range of 200-800 nm and two kinds of reference standards were also investigated. Three kinds of models including partial least square regression (PLSR), stepwise multiple linear regression (SMLR) and principle component regression (PCR) were evaluated for the determination of SC and SSC in navel orange juice. Calibration models based on the different spectral ranges were also compared. Performance of different models was assessed in terms of root mean square errors of prediction (RMSEP) and correlation coefficient (r) of prediction set of samples. The correlation coefficients of calibration models for SC and SSC were 0.965 and 0.961, the correlation coefficients of prediction models for SC and SSC were 0.857 and 0.888, and the corresponding RMSEP were 0.562 and 0.492 respectively. The results show that ultraviolet-visible transmittance technique is a feasible method for non-invasive estimation of fruit juice SC and SSC.

  7. Visibility reduction and accompanying aerosol evolution downwind of St. Louis

    International Nuclear Information System (INIS)

    Under the auspices of Project METROMEX, studies of visibility deterioration downwind of St. Louis were conducted during August 1976. Estimates of horizontal visibility and aerosol measurements were acquired upwind, over and downwind of the St. Louis metropolitan area, by means of airborne transects and standard meteorological data.Reductions amounting to 50% of regional upwind visibilities have been observed; during a weekend study when light, urban vehicular and industrial activity was observed, visibilities within the anomaly were reduced by only 20%. The anomalies were situated between distances corresponding to 2--4 h travel time downwind for an air parcel moving with the mean transport wind. Several case studies noted improvement in the visual range after 4--5 h downwind.The regions of minimum visibility do not coincide with locations of Aitken nucleus concentrations at 2--4 h downwind. Aerosol surface volume distributions indicate a general growth in the accumulation mode (0.1--1.0 ?m) with maximum values in a much narrower size range within the mode of 0.2--0.3 ?m diameter. These increases in the accumulation mode correspond to the size range in which particles are optically significant. Collaborative evidence from current literature suggests gas-to-particle reactions and/or gravitational sedimentation and coagulation as cause of the aerosol growth.The ramifications of visibility deteroration near large metropolitan areas are demonstrated by a conceptual model

  8. On the Visibility of Prominence Fine Structures at Radio Millimeter Wavelengths

    Science.gov (United States)

    Heinzel, P.; Berlicki, A.; Bárta, M.; Karlický, M.; Rudawy, P.

    2015-07-01

    Prominence temperatures have so far mainly been determined by analyzing spectral line shapes, which is difficult when the spectral lines are optically thick. The radio spectra in the millimeter range offer a unique possibility to measure the kinetic temperature. However, studies in the past used data with insufficient spatial resolution to resolve the prominence fine structures. The aim of this article is to predict the visibility of prominence fine structures in the submillimeter/millimeter (SMM) domain, to estimate their brightness temperatures at various wavelengths, and to demonstrate the feasibility and usefulness of future high-resolution radio observations of solar prominences with ALMA ( Atacama Large Millimeter-submillimeter Array). Our novel approach is the conversion of H coronagraphic images into microwave spectral images. We show that the spatial variations of the prominence brightness both in the H line and in the SMM domain predominantly depend on the line-of-sight emission measure of the cool plasma, which we derive from the integrated intensities of the observed H line. This relation also offers a new possibility to determine the SMM optical thickness from simultaneous H observations with high resolution. We also describe how we determine the prominence kinetic temperature from SMM spectral images. Finally, we apply the ALMA image-processing software Common Astronomy Software Applications (CASA) to our simulated images to assess what ALMA would detect at a resolution level that is similar to the coronagraphic H images used in this study. Our results can thus help in preparations of first ALMA prominence observations in the frame of science and technical verification tests.

  9. Spectral variability on primitive asteroids of the Themis and Beagle families: space weathering effects or parent body heterogeneity?

    CERN Document Server

    Fornasier, S; Perna, D; Campins, H; Barucci, M A; Nesvorny, D

    2016-01-01

    Themis is an old and statistically robust asteroid family populating the outer main belt, and resulting from a catastrophic collision that took place 2.5$\\pm$1.0 Gyr ago. Within the old Themis family a young sub-family, Beagle, formed less than 10 Myr ago, has been identified. We present the results of a spectroscopic survey in the visible and near infrared range of 22 Themis and 8 Beagle families members. The Themis members investigated exhibit a wide range of spectral behaviors, while the younger Beagle family members look spectrally bluer with a smaller spectral slope variability. The best meteorite spectral analogues found for both Themis and Beagle families members are carbonaceous chondrites having experienced different degrees of aqueous alteration, prevalently CM2 but also CV3 and CI, and some of them are chondrite samples being unusual or heated. We extended the spectral analysis including the data available in the literature on Themis and Beagle families members, and we looked for correlations betwe...

  10. Visible light scatter as quantitative information source on milk constituents

    DEFF Research Database (Denmark)

    Melentieva, Anastasiya; Kucheryavskiy, Sergey

    2012-01-01

    VISIBLE LIGHT SCATTER AS A QUANTITATIVE INFORMATION SOURCE ON MILK CONSTITUENTS A. Melenteva 1, S. Kucheryavski 2, A. Bogomolov 1,31Samara State Technical University, Molodogvardeyskaya Street 244, 443100 Samara, Russia. 2Aalborg University, campus Esbjerg, Niels Bohrs vej 8, 6700 Esbjerg, Denmark. 3J&M Analytik AG, Willy-Messerschmitt-Strasse 8, 73457 Essingen, Germany. bogomolov@j-m.de Fat and protein are two major milk nutrients that are routinely analyzed in the dairy industry. Growing food quality requirements promote the dissemination of spectroscopic analysis, enabling real-time monitoring of processes and products. Optical analysis is generally performed in near and middle infrared (NIR and MIR) regions and relies on the component absorbance and Beer’s Law. The light scatter effect is therefore considered as a disturbance to be avoided during the measurement or eliminated at the data analysis stage. The region of visible (Vis) light (400-800 nm) is economically attractive, because it offers a range of inexpensive light sources, optics and detectors. At present, however, it is commonly considered useless, because of the light scatter by fat globules (1-10 ?m) and protein micelles (80-200 ?m) that strongly dominates; therefore, making the classical absorbance analysis hardly applicable. At the same time, diffused light by itself delivers information on the milk composition, specifically, fat content as illustrated in Fig. 1, and can potentially be used for the quantitative analysis. The main task here is to extract individual quantitative information on milk fat and total protein content from spectral data. This is particularly challenging problem in the case of raw natural milk, where the fat globule sizes may essentially differ depending on source. Fig. 1. Spots of light transmitted through homogenized milk samples with different fat content. The preceding research [1] has shown that individual scatter patterns of fat and protein in non-homogenized milk can be distinguished, thus, enabling their quantitative multivariate analysis. In the present study, a representative designed set of raw milk samples with simultaneously varying fat, total protein and particle size distribution has been analyzed in the Vis spectral region. The feasibility of raw milk analysis by PLS regression on spectral data has been proved. The root mean-square errors below 0.10% and 0.04% for fat and protein, respectively, have been obtained. PLS components were interpreted in terms of captured information. The results obtained provide a basis for the replacement of traditional spectroscopy by custom optical analyzers, optimized for the purpose of milk analysis. Preliminary achievements in this new research area are presented and discussed. References: [1] A. Bogomolov, S. Dietrich, B. Boldrini, R.W. Kessler, Food Chemistry (2012), doi:10.1016/j.foodchem.2012.02.077.

  11. Spectral concentration in the nonrelativistic limit

    International Nuclear Information System (INIS)

    First order relativistic corrections to the Schroedinger operator according to Foldy and Wouthuysen are rigorously discussed in the framework of singular perturbation theory. For Coulomb plus short-range interactions we investigate the corresponding spectral properties and prove spectral concentration and existence of first order pseudoeigenvalues in the nonrelativistic limit. (Author)

  12. Spectral and spectral-polarization characteristics of potato leaves

    Science.gov (United States)

    Belyaev, B. I.; Belyaev, Yu. V.; Chumakov, A. V.; Nekrasov, V. P.; Shuplyak, V. I.

    2000-07-01

    The results of laboratory investigations of the spectral and spectral-polarization characteristics of radiation reflected from the leaves of potato (Solanum tuberosum) of different varieties are discussed. During the vegetation season of 1997, the angular dependence of the degree and azimuth of polarization of radiation reflected from potato leaves as well as the scattering indicatrices in the range 380 1080 nm were determined by a specially developed method with the use of a laboratory goniometric setup. The relationship between the spectral polarization characteristics of radiation and biological parameters of the potato has been obtained with the help of different methods of statistical analysis and explained on the basis of the known physical mechanisms.

  13. A preliminary assessment of a detailed two stream short-wave narrow-band model using spectral radiation measurements

    Energy Technology Data Exchange (ETDEWEB)

    Cachorro, V.E.; De Frutos, A.M. [Universidad de Valladolid (Spain). Departamento de Optica y Fisica Aplicada; Utrillas, M.P.; Martinez-Lozano, J.A. [Universitat de Valencia (Spain). Departamento de Termodinamica

    1997-10-01

    A data bank of measurements of global, direct and diffuse solar spectral irradiances at ground level for clear skies has been compiled for Valencia (Spain) dating back to December 1992. The measurements were made with a commercial Li-cor 1800 spectroradiometer with a range of 300-1100 nm and a spectral resolution of 6 nm. A preliminary comparative assessment has been carried out between the experimental data and model data. The chosen model was a detailed narrow-band model (208 spectral intervals from 0.2 to 4 {mu}m) developed at the Laboratoire d'Optique Atmospherique (LOA) of the University of Lille (France). This plane-parallel multilayer model uses a two-flux method to solve the radiative transfer equation and an exponential sum-fitting procedure to solve the absorption-scattering problem for finite spectral intervals. For this first comparative assessment we focused our attention on the capability of the LOA model to predict irradiance data (direct, global and diffuse) using four values of visibility (40, 23, 14 and 5 km) for two aerosol models (maritime and continental) in the boundary layer. These first results show the low sensitivity of global irradiance to different turbidity conditions. Conversely, the spectral direct and diffuse irradiances were highly influenced by the chosen aerosol model taking into account the visibility values. The spectral distribution of predicted global and direct irradiances are in relatively good agreement with the observed values. The diffuse data show larger discrepancies, which are in part due to the nature of the measurement process itself. However, the observed differences can be partially explained by taking into account the associated errors of the measured data, the elapsed time between the measured spectra and the prediction power of the LOA model. (author)

  14. Novel non-invasive distribution measurement of texture profile analysis (TPA) in salmon fillet by using visible and near infrared hyperspectral imaging.

    Science.gov (United States)

    Wu, Di; Sun, Da-Wen; He, Yong

    2014-02-15

    This study developed a pushbroom visible and near-infrared hyperspectral imaging system in the wavelength range of 400-1758 nm to determine the spatial distribution of texture profile analysis (TPA) parameters of salmon fillets. Six TPA parameters (hardness, adhesiveness, chewiness, springiness, cohesiveness, and gumminess) were analysed. Five spectral features (mean, standard deviation, skew, energy, and entropy) and 22 image texture features obtained from graylevel co-occurrence matrix (GLCM) were extracted from hyperspectral images. Quantitative models were established with the extracted spectral and image texture signatures of samples based on partial least squares regression (PLSR). The results indicated that spectral features had better ability to predict TPA parameters of salmon samples than image texture features, and Spectral Set I (400-1000 nm) performed better than Spectral II (967-1634 nm). On the basis of the wavelengths selected by regression coefficients of PLSR models, instrumental optimal wavelengths (IOW) and predictive optimal wavelengths (POW) were further chosen to reduce the high dimensionality of the hyperspectral image data. Our results show that hyperspectral imaging holds promise as a reliable and rapid alternative to traditional universal testing machines for measuring the spatial distribution of TPA parameters. PMID:24128497

  15. A versatile femtosecond stimulated Raman spectroscopy setup with tunable pulses in the visible to near infrared

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Liangdong [Department of Physics, Oregon State University, Corvallis, Oregon 97331 (United States); Liu, Weimin [Department of Chemistry, Oregon State University, Corvallis, Oregon 97331 (United States); Fang, Chong, E-mail: Chong.Fang@oregonstate.edu [Department of Physics, Oregon State University, Corvallis, Oregon 97331 (United States); Department of Chemistry, Oregon State University, Corvallis, Oregon 97331 (United States)

    2014-07-28

    We demonstrate a versatile and efficient setup to perform femtosecond stimulated Raman spectroscopy (FSRS). Technical innovations are implemented to achieve the wavelength tunability for both the picosecond narrowband Raman pump pulse and femtosecond broadband Raman probe pulse. Using a simplified one-grating scheme in a home-built second harmonic bandwidth compressor followed by a two-stage noncollinear optical parametric amplifier, we tune the Raman pump pulse from ca. 480 to 750?nm. To generate the suitable Raman probe pulse in tandem, we rely on our recently demonstrated broadband up-converted multicolor array technique that readily provides tunable broadband laser sidebands across the visible to near-infrared range. This unique setup has unparalleled flexibility for conducting FSRS. We measure the ground-state Raman spectra of a cyclohexane standard using tunable pump-probe pairs at various wavelengths across the visible region. The best spectral resolution is ?12?cm{sup ?1}. By tuning the pump wavelength closer to the electronic absorption band of a photoacid pyranine in water, we observe the pre-resonantly enhanced Raman signal. The stimulated Raman gain of the 1627?cm{sup ?1} mode is increased by over 15 times.

  16. Generation of tunable few optical-cycle pulses by visible-to-infrared frequency conversion

    Science.gov (United States)

    Darginavi?ius, J.; Tamošauskas, G.; Piskarskas, A.; Valiulis, G.; Dubietis, A.

    2012-07-01

    We demonstrate a simple method for infrared few optical-cycle pulse generation, which is based on collinear visible-to-infrared frequency conversion and involves difference-frequency generation and subsequent two-step optical parametric amplification. The numerical simulations and experiments using BBO crystals show an efficient frequency down conversion of visible ˜20 fs pulses from a commercial blue-pumped noncollinear optical parametric amplifier yielding 1.2-2.4 ?m tunable sub-100 ?J pulses with duration of 3 to 5 optical-cycles. The proposed method could be readily extended to generate few optical-cycle pulses in the mid-infrared spectral range (up to 5.5 ?m) using, e.g., LiIO3 and LiNbO3 crystals, as demonstrated by the numerical simulations. In these crystals, even shorter, two-optical-cycle mid-infrared pulses could be obtained at particular wavelengths where group velocity matching between the signal and idler waves is achieved.

  17. Aqueous alteration on main belt primitive asteroids: results from visible spectroscopy

    CERN Document Server

    Fornasier, S; Barucci, M A; Lazzarin, M

    2014-01-01

    This work focuses on the study of the aqueous alteration process which acted in the main belt and produced hydrated minerals on the altered asteroids. The aqueous alteration is particularly important for unraveling the processes occurring during the earliest times of the Solar System history, as it can give information both on the asteroids thermal evolution and on the localization of water sources in the asteroid belt. We present new spectral observations in the visible region of 80 asteroids belonging to the primitive classes C, G, F, B and P. We combine the present observations with the visible spectra of asteroids available in the literature for a total of 600 primitive main belt asteroids. Our analysis shows that the aqueous alteration sequence starts from the P-type objects, practically unaltered, and increases through the F, B, C, and G asteroids. Around 50% of the observed C-type asteroids show absorption features in the vis. range due to hydrated silicates, implying that more than 70% of them will ha...

  18. Spectral Classification Beyond M

    CERN Document Server

    Leggett, S K; Burgasser, A J; Jones, H R A; Marley, M S; Tsuji, T

    2004-01-01

    Significant populations of field L and T dwarfs are now known, and we anticipate the discovery of even cooler dwarfs by Spitzer and ground-based infrared surveys. However, as the number of known L and T dwarfs increases so does the range in their observational properties, and difficulties have arisen in interpreting the observations. Although modellers have made significant advances, the complexity of the very low temperature, high pressure, photospheres means that problems remain such as the treatment of grain condensation as well as incomplete and non-equilibrium molecular chemistry. Also, there are several parameters which control the observed spectral energy distribution - effective temperature, grain sedimentation efficiency, metallicity and gravity - and their effects are not well understood. In this paper, based on a splinter session, we discuss classification schemes for L and T dwarfs, their dependency on wavelength, and the effects of the parameters T_eff, f_sed, [m/H] and log g on optical and infra...

  19. Optical Spectral Variability of Blazars

    Indian Academy of Sciences (India)

    Haritma Gaur

    2014-09-01

    It is well established that blazars show flux variations in the complete electromagnetic (EM) spectrum on all possible time scales ranging from a few tens of minutes to several years. Here, we report the review of optical flux and spectral variability properties of different classes of blazars on IDV and STV time-scales. Our analysis show HSPs are less variable in optical bands as compared to LSPs. Also, we investigated the spectral slope variability and found that the average spectral slopes of LSPs showed a good agreement with the synchrotron self-Compton loss-dominated model. However, spectra of the HSPs and FSRQs have significant additional emission components. In general, spectra of BL Lacs get flatter when they become brighter, while for FSRQs the opposite trend appears to hold.

  20. Multispectral antireflection coating simultaneously effective in visible, diode laser, Nd-YAG and eye safe laser wavelength

    International Nuclear Information System (INIS)

    Multi-spectral antireflection coating effective in visible region for sighting system, Nd-YAG laser wavelength for designator/seeker system, both diode laser and eye safe laser wavelength for ranging purpose can use common objective/receiver optics highly useful for state of art laser instrumentation. In this paper, design and fabrication of antireflection coating simultaneously effective in visible region (500 to 650nm), diode laser at 904±25nm and Nd-YAG laser at 1064±25nm, and erbium-glass laser wavelength at 1540±25nm has been reported. Inhomogeneous refractive index profile as suggested by Southwell was used to design this coating. The inhomogeneous profile was then approximated with eleven steps from substrate to air medium in order to obtain desirable antireflection property in the visible and laser wavelengths. These steps were then converted into the available coating materials (titanium-di-oxide and magnesium fluoride) of twenty-two layer stack. The multilayer stack was fabricated by using electron beam gun evaporation system in Balzers BAK-600 vacuum coating unit. The result achieved were less than 2% average reflection (98% average transmission) from 500 to 650nm, 1.5% reflection (98.5% average transmission) at 904nm, 1064nm and 1540nm. The coated samples successfully passed the specifications of MIL-C-14806 tests

  1. New observation strategies for the solar UV spectral irradiance

    Directory of Open Access Journals (Sweden)

    Kretzschmar Matthieu

    2012-09-01

    Full Text Available Many applications in space weather and in space situational awareness require continuous solar spectral irradiance measurements in the UV, and to a lesser degree in the visible band. Most space-borne solar radiometers are made out of two different parts: (i a front filter that selects the passband and (ii a detector that is usually based on silicon technology. Both are prone to degradation, which may be caused either by the degradation of the filter coating due to local deposition or to structural changes, or by the degradation of the silicon detector by solar radiative and energetic particle fluxes. In this study, we provide a theoretical analysis of the filter degradation that is caused by structural changes such as pinholes; contamination-induced degradation will not be considered. We then propose a new instrumental concept, which is expected to overcome, at least partially, these problems. We show how most of the solar UV spectrum can be reconstructed from the measurement of only five spectral bands. This instrumental concept outperforms present spectrometers in terms of degradation. This new concept in addition overcomes the need for silicon-based detectors, which are replaced by wide band gap material detectors. Front filters, which can contribute to in-flight degradation, therefore are not required, except for the extreme-UV (EUV range. With a small weight and a low telemetry, this concept may also have applications in solar physics, in astrophysics and in planetology.

  2. Design of camouflage material for visible and near infrared based on thin film technology

    Science.gov (United States)

    Miao, Lei; Shi, Jia-ming; Zhao, Da-peng; Liu, Hao; Wang, Chao; Xu, Yan-liang

    2015-11-01

    Visible light and near infrared based camouflage materials achieve good stealth under traditional optical detection equipment but its spectral differences with green plants can be taken advantage of by high spectrum based detection technologies. Based on the thin structure of bandpass filter, we designed an optical film with both green and near infrared spectrum. We conducted simulations using transfer matrix methods and optimized the result by simplex methods. The spectral reflectance curve of the proposed thin film matches that of green plants, and experiments show that the proposed thin film achieve good invisibility under visible light and near infrared in a wide viewing angle.

  3. General approach to high power, coherent visible and ultraviolet light sources

    DEFF Research Database (Denmark)

    Andersen, Martin Thalbitzer

    2009-01-01

    The main goal of this project is to develop a generic approach to synthesise any wavelength in the visible and UV spectral region based on sum frequency generation. The approach is based on a hybrid system combining solid state and semiconductor technology. The generation of light in the UV spectral region require nonlinear materials with a transparency range extending into the ultraviolet, the ability to sustain high photon energies and with the ability to obtain phasematching for the desired nonlinear conversion process. In this project experiments are conducted using three differently co-doped GdCOB crystals. The crystals are optimized for noncritical phasematching in the blue-UV spectral region through co-doping with Lu and Sc, a nonlinear coefficient for these crystals of 0.78, 0.81 and 0.89 pm/V are measured, which is comparable to LBO. The ability to adjust the noncritical phasematching by co-doping of these crystals makes them promising candidates for generation of light in the blue-UV region. A novelmethod for cavity dumping based on nonlinear frequency conversion is investigated. A high finesse laser is constructed with an intracavity nonlinear material inserted in a beam waist. The nonlinear material is phasematched to support sum frequency generation between the 1342nm circulating field in the cavity and a single pass passively Q-Switched 1064nm laser, effectively converting the circulating power whenever a single pass pulse is present. Furthermore the Q-Switched laser can easily be frequency doubled in a single pass configuration, therefore the nonlinear cavity dumping approach is suggested for the generation of 340nm UV light, using 532nm pulses to cavity dump a 946nm Nd:YAG laser. Furthermore experiments are conducted tripling a Q-switched 1064nm laser to 355nm by cascaded second harmonic and sum frequency generation using periodically poled KTP and BBO for the SHG and SFG process, respectively. The 355nm light is used to promote different photo induced reactions. The main limitation of reaching any desired wavelength in the visible spectrum using sum frequency generation is the limited laser lines available from efficient solid state lasers. One fundamental way to overcome this limitation is to use semiconductor lasers to provide one of the fundamental fields. The problem of using semiconductor lasers for nonlinear frequency conversion has previously been the lag of coherence of these devices. This problem can, however, to a large extent be solved using external cavity tapered diode lasers, which allows for the generation of coherent radiation at the watt power level. Using differently doped semiconductor materials these devices can potentially cover the wavelength range from the red and into the infrared spectral range. These devices are very efficient, however, the available devices in the visible region are still very inefficient, therefore a generic approach using high finesse solid state lasers with intracavity nonlinear materials and single pass tapered diode was sought to cover the shorter wavelength range. In this project more then 300mW of 488nm power is generated by direct sum frequency mixing of a solid state laser and a single pass external cavity tapered diode laser. The performance of the device is compared to systems where the output of the tapered diode laser is spatially filtered and to an all solid state laser system based on mixing with a single frequency Ti:Sapphire laser. Finally experiments with a semiconductor disk laser used as the high finesse cavity laser and sum frequency mixing with a single pass solid state laser is coniv ducted. These experiments show that it is possible to design systems exploiting the benefits of semiconductor based lasers and nonlinear sum frequency generation to cover large parts of the optical spectrum, which has previously been difficult to access due to the lag of efficient, coherent light sources

  4. Light beam range finder

    Science.gov (United States)

    McEwan, Thomas E. (Livermore, CA)

    1998-01-01

    A "laser tape measure" for measuring distance which includes a transmitter such as a laser diode which transmits a sequence of electromagnetic pulses in response to a transmit timing signal. A receiver samples reflections from objects within the field of the sequence of visible electromagnetic pulses with controlled timing, in response to a receive timing signal. The receiver generates a sample signal in response to the samples which indicates distance to the object causing the reflections. The timing circuit supplies the transmit timing signal to the transmitter and supplies the receive timing signal to the receiver. The receive timing signal causes the receiver to sample the reflection such that the time between transmission of pulses in the sequence in sampling by the receiver sweeps over a range of delays. The transmit timing signal causes the transmitter to transmit the sequence of electromagnetic pulses at a pulse repetition rate, and the received timing signal sweeps over the range of delays in a sweep cycle such that reflections are sampled at the pulse repetition rate and with different delays in the range of delays, such that the sample signal represents received reflections in equivalent time. The receiver according to one aspect of the invention includes an avalanche photodiode and a sampling gate coupled to the photodiode which is responsive to the received timing signal. The transmitter includes a laser diode which supplies a sequence of visible electromagnetic pulses. A bright spot projected on to the target clearly indicates the point that is being measured, and the user can read the range to that point with precision of better than 0.1%.

  5. Measurement of dysprosium optical constants in the 2-830 eV spectral range using a transmittance method, and compilation of the revised optical constants of lanthanum, terbium, neodymium, and gadolinium

    International Nuclear Information System (INIS)

    The optical constants ?, ? of the complex refractive index (n=1-?+i?) of Dy were obtained in the 2-830 eV energy range using a novel transmittance method. Si/W/Dy/W films were deposited by dc-magnetron sputtering on Si photodiode substrates, and the transmittance was characterized using synchrotron radiation. The extinction coefficients ? of Dy and the transmittance of a Si capping layer and two W interface barrier layers as functions of energy were solved simultaneously using a nonlinear optimization routine. The measured transmittances of the capping and barrier layers were primarily used as indicators for any flaws in the transmittance results. The dispersion coefficients ? of Dy were calculated using the Kramers-Kronig integral, and a complete set of ? values required for this integral was obtained by combining the present data with data from the literature. Sum rule tests on Dy show some deficiencies in the present data, which may be attributed to lower film density compared with the bulk value. Similar procedures were applied to previously measured transmittances of B4C/La, Si/Tb, Si/Nd, and Si/Gd films, where B4C or Si were used as capping layers on those reactive rare-earth films. The improved sets of transmittance values of B4C and Si capping layers were used as input in the optimization routine to solve for more accurate ? values of La, Tb, Nd, and Gd. The revised optical constants of these materials, tested for consistency with partial sum rules, are also reported.

  6. Hard X-Ray Imaging of Individual Spectral Components in Solar Flares

    Science.gov (United States)

    Caspi, Amir; Shih, Albert Y.; McTiernan, James M.; Krucker, Säm

    2015-09-01

    We present a new analytical technique, combining Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) high-resolution imaging and spectroscopic observations, to visualize solar flare emission as a function of spectral component (e.g., isothermal temperature) rather than energy. This computationally inexpensive technique is applicable to all spatially invariant spectral forms and is useful for visualizing spectroscopically determined individual sources and placing them in context, e.g., comparing multiple isothermal sources with nonthermal emission locations. For example, while extreme ultraviolet images can usually be closely identified with narrow temperature ranges, due to the emission being primarily from spectral lines of specific ion species, X-ray images are dominated by continuum emission and therefore have a broad temperature response, making it difficult to identify sources of specific temperatures regardless of the energy band of the image. We combine RHESSI calibrated X-ray visibilities with spatially integrated spectral models including multiple isothermal components to effectively isolate the individual thermal sources from the combined emission and image them separately. We apply this technique to the 2002 July 23 X4.8 event studied in prior works, and image for the first time the super-hot and cooler thermal sources independently. The super-hot source is farther from the footpoints and more elongated throughout the impulsive phase, consistent with an in situ heating mechanism for the super-hot plasma.

  7. Visibility Management and the Body

    Science.gov (United States)

    Lasser, Jon; Wicker, Nichole

    2008-01-01

    The authors employed grounded theory to explore the high school experiences of gay, lesbian, and bisexual students in Central Texas. The central phenomenon that emerged from the study was Visibility Management, or decisions made regarding the disclosure of invisible traits. This article reviews the results of this research with an emphasis on the…

  8. Understanding and Approaching Muslim Visibilities

    DEFF Research Database (Denmark)

    Schmidt, Garbi

    2011-01-01

    Within Western nation-states such as Denmark, Islamic identities are often seen as inherently and divergently visible, an aspect that some argue is detrimental to the secular nation-state. From a research perspective, one way to nuance this position is by focusing on groups of 'invisible' Muslims...

  9. Magnetic Fields: Visible and Permanent.

    Science.gov (United States)

    Winkeljohn, Dorothy R.; Earl, Robert D.

    1983-01-01

    Children will be able to see the concept of a magnetic field translated into a visible reality using the simple method outlined. Standard shelf paper, magnets, iron filings, and paint in a spray can are used to prepare a permanent and well-detailed picture of the magnetic field. (Author/JN)

  10. Early Learning Theories Made Visible

    Science.gov (United States)

    Beloglovsky, Miriam; Daly, Lisa

    2015-01-01

    Go beyond reading about early learning theories and see what they look like in action in modern programs and teacher practices. With classroom vignettes and colorful photographs, this book makes the works of Jean Piaget, Erik Erikson, Lev Vygotsky, Abraham Maslow, John Dewey, Howard Gardner, and Louise Derman-Sparks visible, accessible, and easier…

  11. Visible-NIR Spectroscopic Evidence for the Composition of Low-Albedo Altered Soils on Mars

    Science.gov (United States)

    Murchie, S.; Merenyi, E.; Singer, R.; Kirkland, L.

    1996-03-01

    Spectroscopic studies of altered Martian soils at visible and at NIR wavelengths have generally supported the canonical model of the surface layer as consisting mostly of 2 components, bright red hematite-containing dust and dark gray pyroxene-containing sand. However several of the studies have also provided tantalizing evidence for distinct 1 micrometer Fe absorptions in discrete areas, particularly dark red soils which are hypothesized to consist of duricrust. These distinct absorptions have been proposed to originate from one or more non-hematitic ferric phases. We have tested this hypothesis by merging high spatial resolution visible- and NIR-wavelength data to synthesize composite 0.44-3.14 1lm spectra for regions of western Arabia and Margaritifer Terra. The extended wavelength coverage allows more complete assessment of ferric, ferrous, and H2O absorptions in both wavelength ranges. The composite data show that, compared to nearby bright red soil in Arabia, dark red soil in Oxia has a lower albedo, a more negative continuum slope, and a stronger 3 micrometer H2O absorption . However Fe absorptions are closely similar in position and depth. These results suggest that at least some dark red soils may differ from "normal" dust and mafic sand more in texture than in Fe mineralogy, although there appears to be enrichment in a water-containing phase and/or a dark, spectrally neutral phase. In contrast, there is clear evidence for enrichment of a low-albedo ferric mineral in dark gray soils composing Sinus Meridiani. These have visible- and NIR-wavelength absorptions consistent with crystalline hematite with relatively little pyroxene, plus a very weak 3 micrometer H2O absorption. These properties suggest a Ethology richer in crystalline hematite and less hydrated than both dust and mafic-rich sand.

  12. Two-dimensional solar spectropolarimetry with the KIS/IAA Visible Imaging Polarimeter

    CERN Document Server

    Beck, C; Kentischer, T J; Tritschler, A; Iniesta, J C del Toro

    2010-01-01

    Spectropolarimetry at high spatial and spectral resolution is a basic tool to characterize the magnetic properties of the solar atmosphere. We introduce the KIS/IAA Visible Imaging Polarimeter (VIP), a new post-focus instrument that upgrades the TESOS spectrometer at the German VTT into a full vector polarimeter. VIP is a collaboration between the KIS and the IAA. We describe the optical setup of VIP, the data acquisition procedure, and the calibration of the spectropolarimetric measurements. We show examples of data taken between 2005 and 2008 to illustrate the potential of the instrument. VIP is capable of measuring the four Stokes profiles of spectral lines in the range from 420 to 700 nm with a spatial resolution better than 0.5". Lines can be sampled at 40 wavelength positions in 60 s, achieving a noise level of about 2 x 10E-3 with exposure times of 300 ms and pixel sizes of 0.17" x 0.17" (2 x 2 binning). The polarization modulation is stable over periods of a few days, ensuring high polarimetric accura...

  13. Infrared and Visible Photodissociation Spectra of Rhodamine Ions at 3 K in the Gas Phase.

    Science.gov (United States)

    Jašík, Juraj; Navrátil, Rafael; N?mec, Ivan; Roithová, Jana

    2015-12-24

    Helium-tagging predissociation spectroscopy in the visible spectral range (He@VisPD) is shown for Rhodamine 123, Rhodamine 110, and Rhodamine 110's silver salt (silver carboxylate). It is shown that the spectra reflect single-photon absorption. The helium-tagged ions are in the ground vibrational state, and the He@VisPD spectra feature the Franck-Condon envelopes for the excitation to the first excited singlet state that agree very well with theoretical simulations. The S0 ? S1 excitation energies are 2.712 ± 0.006 eV for Rhodamine 123, 2.700 ± 0.006 eV for Rhodamine 110, and 2.751 ± 0.006 eV for the silver salt of Rhodamine 110. The determined energies can be slightly blue-shifted due to the binding energy of helium. The Rhodamine ions were also characterized by helium-tagging infrared photodissociation spectroscopy. The distinctive spectral features of the individual derivatives are described and the spectra are compared to the classical solid-state IR spectra. PMID:26595323

  14. Altered rock spectra in the visible and near infrared. [western Nevada

    Science.gov (United States)

    Hunt, G. R.; Ashley, R. P. (principal investigators)

    1979-01-01

    The author has identified the following significant results. Visible and near-infrared (0.35 to 2.5 micron m) bidirectional reflection spectra recorded for a suite of well-characterized hydrothermally altered rock samples typically display well defined bands caused by both electronic and vibrational processes in the individual mineral constituents. Electronic transitions in the iron-bearing constituent minerals produce diagnostic minima near 0.43, 0.65, 0.85, and 0.93 micron m. Vibrational transitions in clay and water-bearing mineral constituents produce characteristic single or multiple features over limited spectral ranges near 1.4, 1.75, 1.9, 2.2, and 2.35 micron m. The most abundant feature-producing minerals present in these rocks are hematite, goethite, and alunite. Others frequently present are jarosite, kaolinite, potassium micas, pyrophyllite, montmorillonite, diaspore, and gypsum. The spectral region near 2.2 micron m is particularly important for detecting altered rocks by remote sensing.

  15. Bright visible light emission from graphene

    Science.gov (United States)

    Kim, Young Duck; Kim, Hakseong; Cho, Yujin; Ryoo, Ji Hoon; Park, Cheol-Hwan; Kim, Pilkwang; Kim, Yong Seung; Lee, Sunwoo; Li, Yilei; Park, Seung-Nam; Shim Yoo, Yong; Yoon, Duhee; Dorgan, Vincent E.; Pop, Eric; Heinz, Tony F.; Hone, James; Chun, Seung-Hyun; Cheong, Hyeonsik; Lee, Sang Wook; Bae, Myung-Ho; Park, Yun Daniel

    2015-08-01

    Graphene and related two-dimensional materials are promising candidates for atomically thin, flexible and transparent optoelectronics. In particular, the strong light-matter interaction in graphene has allowed for the development of state-of-the-art photodetectors, optical modulators and plasmonic devices. In addition, electrically biased graphene on SiO2 substrates can be used as a low-efficiency emitter in the mid-infrared range. However, emission in the visible range has remained elusive. Here, we report the observation of bright visible light emission from electrically biased suspended graphene devices. In these devices, heat transport is greatly reduced. Hot electrons (˜2,800?K) therefore become spatially localized at the centre of the graphene layer, resulting in a 1,000-fold enhancement in thermal radiation efficiency. Moreover, strong optical interference between the suspended graphene and substrate can be used to tune the emission spectrum. We also demonstrate the scalability of this technique by realizing arrays of chemical-vapour-deposited graphene light emitters. These results pave the way towards the realization of commercially viable large-scale, atomically thin, flexible and transparent light emitters and displays with low operation voltage and graphene-based on-chip ultrafast optical communications.

  16. [Wavebands selection for rice information extraction based on spectral bands inter-correlation].

    Science.gov (United States)

    Wang, Fu-Min; Huang, Jing-Feng; Xu, Jun-Feng; Wang, Xiu-Zhen

    2008-05-01

    The hyperspectral remote sensing data usually involve hundreds or even thousands of narrow bands, which may be crucial for providing additional information with significant improvements over broad bands in quantifying biophysical and biochemical variables of agricultural crop. However, the huge data generated by hyperspectral systems, and the problems this presents for storage and analysis, have far prevented the routine use of such data. The objective of the present research was to identify the spectral bands in the visible and near-infrared range that were suitable for the study of rice. The hyperspectral reflectance of canopy in different development stages was measured in experimental field using a 1 nm-wide spectroradiometer but was aggregated to 10 nm-wide bandwidths to match the first spaceborne hyperspectral sensor, Hyperion. The correlation coefficients(r) between all the combinations of spectral bands were computed, and then they were converted to R2 , which constituted R2 matrices. The matrices were plotted against wavebands. The criterion of band selection is that the lower the R2 value, the less the redundancy between two wavebands while the higher R2 indicates that there is redundant information between two wavebands. According to the criterion, the wavebands corresponding to the first 100 minimum R2 values were selected from all canopy spectra collected on different dates. And then these bands were analyzed. The results indicate that the visible and infrared (NIR and SWIR) themselves contain redundant information. The wavebands containing abundant information of rice are located in specific bands in the longer wavelength portion of the visible region, with secondary clusters in red edge region, in strongly reflective near-infrared region with relatively higher reflectance, in one particular section of short wave near-infrared (SWIR) (1 530 nm) and in the second maximum reflectance region of SWIR (2 215 nm). Compared with the selected bands with other vegetation, rice seems to have three spectral regions of 400-410 nm, 630-650 nm and 1 520-1 540 nm, which exclusively depict the characteristics of rice. Moreover, this research identified 17 spectral bands in the visible and near-infrared region, which were 405, 565, 585, 605, 620, 640, 660, 680, 695, 705, 720, 740, 865, 910, 1 085, 1 530 and 2 215 nm. These bands contain the majority of the rice information content. A reduction in band number without significant information loss is important because it makes it possible to achieve fine spatial resolution without sacrificing the ability to characterize rice status. PMID:18720809

  17. Validation of GOMOS vertical profiles using the stratospheric balloon-borne AMON and SALOMON UV-Visible spectrometers

    Science.gov (United States)

    Renard, J. B.; Chartier, M.; Berthet, G.; Robert, C.; Lemaire, T.; Pepe, F.; George, M.; Pirre, M.

    2003-04-01

    The stratospheric balloon-borne UV-visible spectrometers AMON and SALOMON, which uses stars and Moon as light source, respectively, were involved in the validation of the UV-visible spectrometer GOMOS onboard ENVISAT, which uses also stars as light source. A low spectral resolution UV-visible spectrometer, AMON-RA, is also implanted in the AMON gondola, for the validation of the GOMOS algorithm dedicated to the correction of the chromatic scintillation effect. A flight of SALOMON occurred in September 19, 2002, at mid latitude from Aire sur l’Adour, France. The night-time SALOMON and GOMOS measurements were conducted at the same time (around 21h30 TU) and with a spatial coincidence less than 250 km. Comparison of vertical profiles was done for an altitude in the 15-40 km range. While the global shape of the GOMOS and SALOMON ozone profiles are quite in agreement, the GOMOS NO2 and NO3 profiles are unrealistic when compared to SALOMON profiles. A reanalysis of the GOMOS transmission using algorithms already developed for SALOMON shows that accurate NO2 and NO3 profiles can be retrieved if DOAS technique and dedicated spectral windows are used. An AMON (and AMON-RA) flight and a new SALOMON flight should occurred at high latitude from Kiruna (northern Sweden) in January and March 2003, respectively. The same analyses as for the September 2002 flight will be conducted, including this time the OClO and aerosols extinction coefficient retrievals. Taking into account the effect of the chromatic scintillation on the transmission spectra, recommendations will be proposed in order to improve the GOMOS retrievals.

  18. Bridging visible and telecom wavelengths with a single-mode broadband photon pair source

    International Nuclear Information System (INIS)

    We present a spectrally decorrelated photon pair source bridging the visible and telecom wavelength regions. Tailored design and fabrication of a solid-core photonic crystal fiber (PCF) lead to the emission of signal and idler photons into only a single spectral and spatial mode. Thus no narrowband filtering is necessary and the heralded generation of pure photon number states in ultrafast wave packets at telecom wavelengths becomes possible.

  19. Visible and Near-Infrared Multispectral Analysis of Rocks at Meridiani Planum, Mars, by the Mars Exploration Rover Opportunity

    OpenAIRE

    Knoll, Andrew; Yen, Albert S.; Watters, Wesley A.; Thompson, Shane D.; Soderblom, Jason; Morris, Richard V.; Grotzinger, John P; Squyres, Steven W.; Scott M. McLennan; Jolliff, Bradley L.; Johnson, Jeffrey R; Bell, James F. III; Farrand, William H.

    2007-01-01

    [1] Multispectral measurements in the visible and near infrared of rocks at Meridiani Planum by the Mars Exploration Rover Opportunity's Pancam are described. The Pancam multispectral data show that the outcrops of the Burns formation consist of two main spectral units which in stretched 673, 535, 432 nm color composites appear buff- and purple-colored. These units are referred to as the HFS and LFS spectral units based on higher and lower values of 482 to 535 nm slope. Spectral characteristi...

  20. Multidimensional spectral load balancing

    Energy Technology Data Exchange (ETDEWEB)

    Hendrickson, B.; Leland, R.

    1993-01-01

    We describe an algorithm for the static load balancing of scientific computations that generalizes and improves upon spectral bisection. Through a novel use of multiple eigenvectors, our new spectral algorithm can divide a computation into 4 or 8 pieces at once. These multidimensional spectral partitioning algorithms generate balanced partitions that have lower communication overhead and are less expensive to compute than those produced by spectral bisection. In addition, they automatically work to minimize message contention on a hypercube or mesh architecture. These spectral partitions are further improved by a multidimensional generalization of the Kernighan-Lin graph partitioning algorithm. Results on several computational grids are given and compared with other popular methods.