WorldWideScience

Sample records for visible spectral range

  1. Spectroscopy of fullerenes, fulleranes and PAHs in the UV, visible and near infrared spectral range

    F. Cataldo; Garcia-Hernandez, D. A.; Manchado, A.; Iglesias-Groth, S.

    2013-01-01

    The spectra of fullerenes C60 and C70, higher fullerenes C76, C78 and C84 and hydrogenated fullerenes (fulleranes) were studied in laboratory in the UV and in the visible spectral range and could be used for searching and recognizing these molecules in space. Furthermore, the radical cation spectra of all the mentioned fullerene series and also of a series of large and very large polycyclic aromatic hydrocarbons (PAHs) were generated in laboratory and studied in the near infrared spectral range.

  2. Scattering in remote sensing in the visible and microwave spectral range and in traffic control

    Böttger, U.; Kühne, R.; Thiessenhusene, K.-U.

    2003-05-01

    The treatment of scattering processes in remote sensing for interpretation of satellite data is demonstrated in the visible and microwave spectral range comparing the two spectral ranges. Analogies and distinctions in the treatment of the scattering processes are shown. Based on this cognition an approach for traffic simulation is outlined. Simulating the traffic of a part of a city, a whole city or a larger area in an acceptable time is one of the tasks in recent traffic research. One possible approach is the areal treatment of the road network. That means that single streets are not resolved but are introduced into simulations only by parameters that correspond to a specific traffic area resistance. The aim of this work is to outline such a possibility using experiences obtained from the theory of radiative transport to simulate scattering processes and applying them to the very complex system of traffic simulation.

  3. Scattering in remote sensing in the visible and microwave spectral range and in traffic control

    U. Böttger

    2003-01-01

    Full Text Available The treatment of scattering processes in remote sensing for interpretation of satellite data is demonstrated in the visible and microwave spectral range comparing the two spectral ranges. Analogies and distinctions in the treatment of the scattering processes are shown. Based on this cognition an approach for traffic simulation is outlined. Simulating the traffic of a part of a city, a whole city or a larger area in an acceptable time is one of the tasks in recent traffic research. One possible approach is the areal treatment of the road network. That means that single streets are not resolved but are introduced into simulations only by parameters that correspond to a specific traffic area resistance. The aim of this work is to outline such a possibility using experiences obtained from the theory of radiative transport to simulate scattering processes and applying them to the very complex system of traffic simulation.

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

    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.

  5. MMI-based MOEMS FT spectrometer for visible and IR spectral ranges

    Al-Demerdash, Bassem M.; Medhat, Mostafa; Sabry, Yasser M.; Saadany, Bassam; Khalil, Diaa

    2014-03-01

    MEMS spectrometers have very strong potential in future healthcare and environmental monitoring applications, where Michelson interferometers are the core optical engine. Recently, MEMS Michelson interferometers based on using silicon interface as a beam splitter (BS) has been proposed [7, 8]. This allows having a monolithically-integrated on-chip FTIR spectrometer. However silicon BS exhibits high absorption loss in the visible range and high material dispersion in the near infrared (NIR) range. For this reason, we propose in this work a novel MOEMS interferometer allowing operation over wider spectral range covering both the infrared (IR) and the visible ranges. The proposed architecture is based on spatial splitting and combining of optical beams using the imaging properties of Multi-Mode Interference MMI waveguide. The proposed structure includes an optical splitter for spatial splitting an input beam into two beams and a combiner for spatial combining the two interferometer beams. A MEMS moveable mirror is provided to produce an optical path difference between the two beams. The new interferometer is fabricated using DRIE technology on an SOI wafer. The movable mirror is metalized and attached to a comb-drive actuator fabricated in the same lithography step in a self-aligned manner on chip. The novel interferometer is tested as a Fourier transform spectrometer. Red laser, IR laser and absorption spectra of different materials are measured with a resolution of 2.5 nm at 635-nm wavelength. The structure is a very compact one that allows its integration and fabrication on a large scale with very low cost.

  6. Spectral estimation of soil water content in visible and near infra-red range

    Attila Nagy

    2014-08-01

    Full Text Available Soils can be examined on the basis of spectral data, using such methods with which the reflected radiation can be divided into a large number of (several hundreds small spectral channel (some nm. Based on the spectral characteristics of the soils, or the different index numbers calculated from hyperspectral data water content of soils can be well characterized. The examined soil samples were coming from different apple orchards of which soils had different physical characteristics (sandy loamy and clay. The goals of my experiments were the evaluation of spectral measurement method for soil content detection, and to carry out algorithms for fast field scale spectral evaluation of different soil water content. The spectral measuring was carried out by laboratory scale AvaSpec 2048 spectrometer at 400 – 1000 nm wavelength interval with 0.6 nm spectral resolutions and by ASD FieldSpec Junior at 350 – 2500 nm. After drying, dry soil samples were watered by 2.5 m/m% till maximal saturation, and each wetting was measured spectrally. Based on spectral properties, reflectances were decreased in the whole spectral range within the continuous wetting due to the high absorption characteristics of water. The most water sensitive spectral ranges were selected by principal component, and such algorithms were created, with which the water content can be detectable in the certain soil. The algorithms can facilitate farmers for irrigation scheduling of their orchards. These results can also be utilizable in precision water management, since it can be a basis for such integrated active sensors with LED or laser light source, measuring reflectance at the certain spectral range, which can facilitate real time water status assessment of orchards.

  7. Absorption spectroscopy in the ultraviolet and visible spectral range of hexavalent chromium aqueous solutions

    Mignani, Anna G.; Spadoni, Lorenzo

    1999-09-01

    In order to demonstrate the possibility of performing direct absorption spectroscopy of Hexavalent Chromium aqueous solutions, absorption measurements were performed at the dual- beam spectrophotometer in the 250 - 850 nm spectral range, with 10 mm and 100 mm path lengths. Low concentration (26 - 520 (mu) g/l) (and high concentration (2.6 - 52 mg/l) solutions were analyzed, showing that it is possible to implement a basic instrumentation for risk condition monitoring and a more advanced instrumentation for quantitative measurements.

  8. Detection of cotton lint trash within the ultraviolet-visible spectral range.

    Zhou, Fei; Ding, Tianhuai

    2010-08-01

    Cotton lint trash is a serious problem in the textile industry. The principle upon which this research is based is that different materials have different spectral absorption, excitation, and emission characteristics. Although white-light imaging is widely used to detect colored foreign-matter contaminants, or "trash", it is almost useless for detecting white trash. The objective of the research described in this paper was to achieve the best trash detection result possible in the spectral range from 250 to 850 nm. Diffuse reflection spectroscopy indicated that the differences in gray value between lint and white trash become significant in the ultraviolet (UV) range, especially from 250 to 350 nm. Fluorescence spectroscopy gave reliable evidence that the UV-induced fluorescence intensity of white trash is much stronger than that of lint. To detect several types of trash simultaneously, the interaction of white-light imaging and UV-induced fluorescence imaging was studied. To avoid the spectral interference caused by white light in fluorescence imaging, a novel method--an alternating imaging detection method--is proposed. Experiments indicated that the advantages of both white-light imaging and UV-induced fluorescence imaging were preserved in the method. The novel method could effectively detect both colored and white trash in real time. This method can also be applied to trash detection in seed cotton, wool, tea leaf, and tobacco leaf. PMID:20719059

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

    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.)

  10. Development of high-gain gaseous photomultipliers for the visible spectral range

    Lyashenko, A. V.; Breskin, A.; Chechik, R.; Santos, J. M. F. dos; Amaro, F. D.; Veloso, J. F. C. A.

    2009-01-01

    We summarize the development of visible-sensitive gaseous photomultipliers, combining a semitransparent bi-alkali photocathode with a state-of-the-art cascaded electron multiplier. The latter has high photoelectron collection efficiency and a record ion blocking capability. We describe in details the system and methods of photocathode production and characterization, their coupling with the electron multiplier and the gaseous-photomultiplier operation and characterization in a continuous mode...

  11. Wide-Band Spatially Tunable Photonic Bandgap in Visible Spectral Range and Laser based on a Polymer Stabilized Blue Phase

    Lin, Jia-De; Wang, Tsai-Yen; Mo, Ting-Shan; Huang, Shuan-Yu; Lee, Chia-Rong

    2016-07-01

    This work successfully develops a largely-gradient-pitched polymer-stabilized blue phase (PSBP) photonic bandgap (PBG) device with a wide-band spatial tunability in nearly entire visible region within a wide blue phase (BP) temperature range including room temperature. The device is fabricated based on the reverse diffusion of two injected BP-monomer mixtures with a low and a high chiral concentrations and afterwards through UV-curing. This gradient-pitched PSBP can show a rainbow-like reflection appearance in which the peak wavelength of the PBG can be spatially tuned from the blue to the red regions at room temperature. The total tuning spectral range for the cell is as broad as 165 nm and covers almost the entire visible region. Based on the gradient-pitched PSBP, a spatially tunable laser is also demonstrated in this work. The temperature sensitivity of the lasing wavelength for the laser is negatively linear and approximately ‑0.26 nm/°C. The two devices have a great potential for use in applications of photonic devices and displays because of their multiple advantages, such as wide-band tunability, wide operated temperature range, high stability and reliability, no issue of hysteresis, no need of external controlling sources, and not slow tuning speed (mechanically).

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

    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.

  13. The program complex for computation of spectroscopic characteristics of atomic and molecular gases in UV, visible and IR spectral ranges for a wide range of temperatures and pressures

    The program complex intended for calculations, on the personal computer, of spectroscopic properties of separate gases and their mixes in UV, visible and IR ranges is submitted in this work. It consists of algorithms describing spectroscopic characteristics of the neutral and ionized atoms and molecules; banks of initial data, physical, thermodynamic and spectroscopic constants, parameters and package of applied programs. The complex allows the computation of parameters of fine and hyperfine structure in electronic-vibrational-rotational spectrums of diatomic molecules, such as wave numbers, Hoenl-London factors, intensities and half-widths of rotational lines; absorption coefficients, absorption cross-sections and emissivity of the heated-up gases with the account of Λ-doubling in ranges of temperatures 200-10 000 K, pressure 10-5-10 atm and wavelengths 0.1-25.0 μm at anyone spectral intervals of averaging

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

    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.

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

    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.)

  16. Uas Based Tree Species Identification Using the Novel FPI Based Hyperspectral Cameras in Visible, NIR and SWIR Spectral Ranges

    Näsi, R.; Honkavaara, E.; Tuominen, S.; Saari, H.; Pölönen, I.; Hakala, T.; Viljanen, N.; Soukkamäki, J.; Näkki, I.; Ojanen, H.; Reinikainen, J.

    2016-06-01

    Unmanned airborne systems (UAS) based remote sensing offers flexible tool for environmental monitoring. Novel lightweight Fabry-Perot interferometer (FPI) based, frame format, hyperspectral imaging in the spectral range from 400 to 1600 nm was used for identifying different species of trees in a forest area. To the best of the authors' knowledge, this was the first research where stereoscopic, hyperspectral VIS, NIR, SWIR data is collected for tree species identification using UAS. The first results of the analysis based on fusion of two FPI-based hyperspectral imagers and RGB camera showed that the novel FPI hyperspectral technology provided accurate geometric, radiometric and spectral information in a forested scene and is operational for environmental remote sensing applications.

  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

    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)

  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

    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.

  19. Review of an assortment of IR materials-devices technologies used for imaging in spectral bands ranging from the visible to very long wavelengths

    DeWames, Roger E.

    2016-05-01

    In this paper we review the intrinsic and extrinsic technological properties of the incumbent technology, InP/In0.53Ga0.47As/InP, for imaging in the visible- short wavelength spectral band, InSb and HgCdTe for imaging in the mid-wavelength spectral band and HgCdTe for imaging in the long wavelength spectral band. These material systems are in use for a wide range of applications addressing compelling needs in night vision imaging, low light level astronomical applications and defense strategic satellite sensing. These materials systems are direct band gap energy semiconductors hence the internal quantum efficiency η, is near unity over a wide spectral band pass. A key system figure of merit of a shot noise limited detector technology is given by the equation (1+Jdark. /Jphoton), where Jdark is the dark current density and Jphoton ~qηΦ is the photocurrent density; Φ is the photon flux incident on the detector and q is the electronic charge. The capability to maintain this factor for a specific spectral band close to unity for low illumination conditions and low temperature onset of non-ideal dark current components, basically intrinsic diffusion limited performance all the way, is a marker of quality and versatility of a semiconductor detector technology. It also enables the highest temperature of operation for tactical illumination conditions. A purpose of the work reported in this paper is to explore the focal plane array data sets of photodiode detector technologies widely used to bench mark their fundamental and technology properties and identify paths for improvements.

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

    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

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

    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.

  2. Coloring elimination in Sr1 - x Ce x F2 + x crystals in the visible spectral range during growth from melt

    Karimov, D. N.; Ivanovskaya, N. A.; Samsonova, N. V.; Sorokin, N. I.; Sobolev, B. P.; Popov, P. A.

    2013-09-01

    Crystals of the Sr1 - x Ce x F2 + x compositions close to the congruent one ( x ˜ 0.3) are fabricated by the vertical directional crystallization. It is shown that the use of CF4 to form a fluorinating atmosphere during growth leads to additional spurious absorption in the crystals in the range 350-600 nm. The use of PbF2 and ZnF2 for fluorination makes it possible to obtain colorless Sr1 - x Ce x F2 + x crystals of the desired optical quality from melt. The thermal conductivity of crystal with x ˜ 0.28 in the temperature range 80-500 K lies within 1.50 ± 0.03 W m-1 K-1. High ionic conductivity makes the Sr1 - x Ce x F2 + x crystals promising for application in solid-state ionics.

  3. On-chip visible-to-infrared supercontinuum generation with more than 495 THz spectral bandwidth

    Epping, J.P.; Hellwig, T.; Hoekman, M.; Mateman, R.; Leinse, A.; Heideman, R.G.; Rees, van A.; Slot, van der P.J.M.; Lee, C.J.; Fallnich, C.; Boller, K-J.

    2015-01-01

    We report ultra-broadband supercontinuum generation in high-confinement Si3N4 integrated optical waveguides. The spectrum extends through the visible (from 470 nm) to the infrared spectral range (2130 nm) comprising a spectral bandwidth wider than 495 THz, which is the widest supercontinuum spectrum

  4. [Visible-NIR spectral feature of citrus greening disease].

    Li, Xiu-hua; Li, Min-zan; Won Suk, Lee; Reza, Ehsani; Ashish, Ratn Mishra

    2014-06-01

    Citrus greening (Huanglongbing, or HLB) is a devastating disease caused by Candidatus liberibacter which uses psyllids as vectors. It has no cure till now, and poses a huge threat to citrus industry around the world. In order to diagnose, assess and further control this disease, it is of great importance to first find a quick and effective way to detect it. Spectroscopy method, which was widely considered as a fast and nondestructive way, was adopted here to conduct a preliminary exploration of disease characteristics. In order to explore the spectral differences between the healthy and HLB infected leaves and canopies, this study measured the visible-NIR spectral reflectance of their leaves and canopies under lab and field conditions, respectively. The original spectral data were firstly preprocessed with smoothing (or moving average) and cluster average procedures, and then the first derivatives were also calculated to determine the red edge position (REP). In order to solve the multi-peak phenomenon problem, two interpolation methods (three-point Lagrangian interpolation and four-point linear extrapolation) were adopted to calculate the REP for each sample. The results showed that there were, obvious differences at the visible & NIR spectral reflectance between the healthy and HLB infected classes. Comparing with the healthy reflectance, the HLB reflectance was higher at the visible bands because of the yellowish symptoms on the infected leaves, and lower at NIR bands because the disease blocked water transportation to leaves. But the feature at NIR bands was easily affected by environmental factors such as light, background, etc. The REP was also a potential indicator to distinguish those two classes. The average REP was slowly moving toward red bands while the infection level was getting higher. The gap of the average REPs between the healthy and HLB classes reached to a maximum of 20 nm. Even in the dataset with relatively lower variation, the classification

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

    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.

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

    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 μm. 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.

  7. Adaptive camouflage in the VIS and IR spectral range: main principles and mechanisms

    Schwarz, Alexander

    2015-10-01

    This paper presents a survey of main applicable technical principles and mechanisms for adaptive camouflage in the visible (VIS) and infrared (IR) spectral ranges. All principles are described by their operation method and technical data such as the active spectral range, the degree and speed of adaptation, weight, power consumption, robustness, usability, lifetime, technology readiness level (TRL) etc.. The paper allows to compare the different principles and to assess them with regard to an application to an adaptive camouflage system.

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

    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.

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

    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.

  10. The optical properties of mouse skin in the visible and near infrared spectral regions.

    Sabino, Caetano P; Deana, Alessandro M; Yoshimura, Tania M; da Silva, Daniela F T; França, Cristiane M; Hamblin, Michael R; Ribeiro, Martha S

    2016-07-01

    Visible and near-infrared radiation is now widely employed in health science and technology. Pre-clinical trials are still essential to allow appropriate translation of optical methods into clinical practice. Our results stress the importance of considering the mouse strain and gender when planning pre-clinical experiments that depend on light-skin interactions. Here, we evaluated the optical properties of depilated albino and pigmented mouse skin using reproducible methods to determine parameters that have wide applicability in biomedical optics. Light penetration depth (δ), absorption (μa), reduced scattering (μ's) and reduced attenuation (μ't) coefficients were calculated using the Kubelka-Munk model of photon transport and spectrophotometric measurements. Within a broad wavelength coverage (400-1400nm), the main optical tissue interactions of visible and near infrared radiation could be inferred. Histological analysis was performed to correlate the findings with tissue composition and structure. Disperse melanin granules present in depilated pigmented mouse skin were shown to be irrelevant for light absorption. Gender mostly affected optical properties in the visible range due to variations in blood and abundance of dense connective tissue. On the other hand, mouse strains could produce more variations in the hydration level of skin, leading to changes in absorption in the infrared spectral region. A spectral region of minimal light attenuation, commonly referred as the "optical window", was observed between 600 and 1350nm. PMID:27101274

  11. Spectral Characterization of a Prototype SFA Camera for Joint Visible and NIR Acquisition

    Thomas, Jean-Baptiste; Lapray, Pierre-Jean; Gouton, Pierre; Clerc, Cédric

    2016-01-01

    Multispectral acquisition improves machine vision since it permits capturing more information on object surface properties than color imaging. The concept of spectral filter arrays has been developed recently and allows multispectral single shot acquisition with a compact camera design. Due to filter manufacturing difficulties, there was, up to recently, no system available for a large span of spectrum, i.e., visible and Near Infra-Red acquisition. This article presents the achievement of a prototype of camera that captures seven visible and one near infra-red bands on the same sensor chip. A calibration is proposed to characterize the sensor, and images are captured. Data are provided as supplementary material for further analysis and simulations. This opens a new range of applications in security, robotics, automotive and medical fields. PMID:27367690

  12. The role of geological surfaces in determining visible-near infra red spectral signatures

    Sommer, S. E.; Buckingham, W. F.

    1981-01-01

    The goal of the study described here is to determine new criteria for improved target discrimination in areas of hydrothermal mineralization. It is noted that the portion of materials, that is, geological surfaces detected by sensing devices, must be accurately determined before elemental and mineralogical characterization. The depth from which visible-near infrared radiation is reflected from target surfaces depends on composition and fabric. Reflectance spectra are obtained from binary mixtures of hematite, goethite, kaolinite and montmorillonite with a reflecting sphere spectrometer over a wavelength range of 400-2500 nm. The reflection (or absorption) intensity is plotted vs. the sample thickness (determined by scanning electron microscopy) to determine the sample thickness at which absorption saturates. The optical depth is seen to vary as a function of mineralogy and wavelength. In general, the maximum depth from which reflection features are discerned is from 12 to 47 microns measured in the visible-near infrared spectral region.

  13. Spectral Characterization of a Prototype SFA Camera for Joint Visible and NIR Acquisition

    Jean-Baptiste Thomas

    2016-06-01

    Full Text Available Multispectral acquisition improves machine vision since it permits capturing more information on object surface properties than color imaging. The concept of spectral filter arrays has been developed recently and allows multispectral single shot acquisition with a compact camera design. Due to filter manufacturing difficulties, there was, up to recently, no system available for a large span of spectrum, i.e., visible and Near Infra-Red acquisition. This article presents the achievement of a prototype of camera that captures seven visible and one near infra-red bands on the same sensor chip. A calibration is proposed to characterize the sensor, and images are captured. Data are provided as supplementary material for further analysis and simulations. This opens a new range of applications in security, robotics, automotive and medical fields.

  14. Spectral Characterization of a Prototype SFA Camera for Joint Visible and NIR Acquisition.

    Thomas, Jean-Baptiste; Lapray, Pierre-Jean; Gouton, Pierre; Clerc, Cédric

    2016-01-01

    Multispectral acquisition improves machine vision since it permits capturing more information on object surface properties than color imaging. The concept of spectral filter arrays has been developed recently and allows multispectral single shot acquisition with a compact camera design. Due to filter manufacturing difficulties, there was, up to recently, no system available for a large span of spectrum, i.e., visible and Near Infra-Red acquisition. This article presents the achievement of a prototype of camera that captures seven visible and one near infra-red bands on the same sensor chip. A calibration is proposed to characterize the sensor, and images are captured. Data are provided as supplementary material for further analysis and simulations. This opens a new range of applications in security, robotics, automotive and medical fields. PMID:27367690

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

    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-μm 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)

  16. Spectral Aging Model Applied to Meteosat First Generation Visible Band

    Ilse Decoster

    2014-03-01

    Full Text Available The Meteosat satellites have been operational since the early eighties, creating so far a continuous time period of observations of more than 30 years. In order to use this data for climate data records, a consistent calibration is necessary between the consecutive instruments. Studies have shown that the Meteosat First Generation (MFG satellites (1982–2006 suffer from in-flight degradation which is spectral of nature and is not corrected by the official calibration of EUMETSAT. Continuing on previous published work by the same authors, this paper applies the spectral aging model to a set of clear-sky and cloudy targets, and derives the model parameters for all six MFG satellites (Meteosat-2 to -7. Several problems have been encountered, both due to the instrument and due to geophysical occurrences, and these are discussed and illustrated here in detail. The paper shows how the spectral aging model is an improvement compared to the EUMETSAT calibration method with a stability of 1%–2% for Meteosat-4 to -7, which increases up to 6% for ocean sites using the full MFG time period.

  17. Spectral slopes of the absorption coefficient of colored dissolved and detrital material inverted from UV-visible remote sensing reflectance

    Wei, Jianwei; Lee, Zhongping; Ondrusek, Michael; Mannino, Antonio; Tzortziou, Maria; Armstrong, Roy

    2016-03-01

    The spectral slope of the absorption coefficient of colored dissolved and detrital material (CDM), Scdm (units: nm-1), is an important optical parameter for characterizing the absorption spectral shape of CDM. Although highly variable in natural waters, in most remote sensing algorithms, this slope is either kept as a constant or empirically modeled with multiband ocean color in the visible domain. In this study, we explore the potential of semianalytically retrieving Scdm with added ocean color information in the ultraviolet (UV) range between 360 and 400 nm. Unique features of hyperspectral remote sensing reflectance in the UV-visible wavelengths (360-500 nm) have been observed in various waters across a range of coastal and open ocean environments. Our data and analyses indicate that ocean color in the UV domain is particularly sensitive to the variation of the CDM spectral slope. Here, we used a synthesized dataset to show that adding UV wavelengths to the ocean color measurements will improve the retrieval of Scdm from remote sensing reflectance considerably, while the spectral band settings of past and current satellite ocean color sensors cannot fully account for the spectral variation of remote sensing reflectance. Results of this effort support the concept to include UV wavelengths in the next generation of satellite ocean color sensors.

  18. Characterisation of red supergiants in the Gaia spectral range

    Dorda, Ricardo; Negueruela, Ignacio

    2016-01-01

    The infrared Calcium Triplet and its nearby spectral region have been used for spectral and luminosity classification of late-type stars, but the samples of cool supergiants (CSGs) used have been very limited (in size, metallicity range, and spectral types covered). The spectral range of the Gaia Radial Velocity Spectrograph (RVS) covers most of this region but does not reach the main TiO bands in this region, whose depths define the M sequence. We study the behaviour of spectral features around the Calcium Triplet and develop effective criteria to identify and classify CSGs, comparing their efficiency with other methods previously proposed. We measure the main spectral features in a large sample (almost 600) of CSGs from three different galaxies, and we analyse their behaviour through a principal component analysis. Using the principal components, we develop an automatised method to differentiate CSGs from other bright late-type stars, and to classify them. The proposed method identifies a high fraction of t...

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

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

  20. Short Range Correlations and Spectral Functions in Asymmetric Nuclear Matter

    Konrad, P; Lenske, H.; Mosel, U.

    2005-01-01

    Dynamical correlations in asymmetric infinite nuclear matter are investigates in a transport theoretical approach. Self-energies due to short range correlations and their influence on the nucleon spectral functions are described in an approach accounting for a realistic treatment of mean-field dynamics and a self-consistently derived quasi-particle interaction. Landau-Migdal theory is used to derived the short range interaction from a phenomenological Skyrme energy density functional. The spe...

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

    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)

  2. Retrieving Soil Hydraulic Properties by Diffuse Spectral Reflectance Data in Vis-NIR-SWIR Range

    Babaeian, E.; Homaee, M.; Vereecken, H.; Montzka, C.; Norouzi, A. A.; Van Genuchten, M.

    2014-12-01

    Information about the soil water characteristics is necessary for modeling water flow and solute transport processes in vadose zone. Soil spectroscopy in the visible, near-infrared and shortwave infrared (Vis-NIR-SWIR) range has been widely used as a rapid, cost-effective and non-destructive technique to predict basic soil properties. In this paper we used three different approaches to retrieve soil hydraulic parameters from spectral data in the visible, near-infrared and shortwave-infrared (Vis-NIR-SWIR) region and basic soil properties. Using stepwise multiple linear statistics coupled with bootstrapping, we derived and validated three types of point and parametric transfer functions: i) spectral transfer functions (STFs), ii) pedotransfer functions (PTFs) and iii) spectral pedotransfer functions (SPTFs) which respectively used spectral data, basic soil properties and spectral based basic soil predictions as their inputs. We further evaluated a direct fit of the van Genuchten (VG) and Brooks-Corey (BC) retention models to the predicted water contents obtained with each approach. According to the results, soil water contents, the VG and BC parameters as well as basic soil properties showed significant (p<0.01) correlation with spectral reflectance values, especially for the SWIR region. The STFs performed slightly better than the PTFs in terms of R2 and RMSE in estimating water contents in the mid and dry parts of retention curve. In the wet range, PTFs were found to perform better than the other two approaches. Compared to the STFs, however, better water content estimates were obtained using the SPTFs in the wet range. The parametric STFs and SPTFs of both the VG and BC models developed from spectral data performed slightly better than parametric PTFs for the retention curve. The best predictions were obtained with a direct fit of the retention models to soil water contents estimated with point transfer functions. Our findings suggest that spectral information

  3. Sb2O3 nanobelt networks for excellent visible-light-range photodetectors

    Excellent photoconductive properties have been found in Sb2O3 nanobelts synthesized by a surfactant-assisted solvothermal method. Visible-light photodetectors have been designed from Sb2O3 nanobelt networks using micrometer-wide gold wires as masks. Photodetectors show high sensitivity to visible light, high stability, and reproducibility. Fast response and decay times (2O3 nanobelt networks can indeed serve as high-performance photodetectors in the visible light range.

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

    A S Kiran Kumar; A Roy Chowdhury

    2005-12-01

    India ’s first 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 first 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 filter 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.

  5. Multispectral interference filter arrays with compensation of angular dependence or extended spectral range.

    Frey, Laurent; Masarotto, Lilian; Armand, Marilyn; Charles, Marie-Lyne; Lartigue, Olivier

    2015-05-01

    Thin film Fabry-Perot filter arrays with high selectivity can be realized with a single patterning step, generating a spatial modulation of the effective refractive index in the optical cavity. In this paper, we investigate the ability of this technology to address two applications in the field of image sensors. First, the spectral tuning may be used to compensate the blue-shift of the filters in oblique incidence, provided the filter array is located in an image plane of an optical system with higher field of view than aperture angle. The technique is analyzed for various types of filters and experimental evidence is shown with copper-dielectric infrared filters. Then, we propose a design of a multispectral filter array with an extended spectral range spanning the visible and near-infrared range, using a single set of materials and realizable on a single substrate. PMID:25969271

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

    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...

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

    Pertenais, Martin; Neiner, Coralie; Parès, Laurent; Petit, Pascal

    2015-09-01

    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 measurement and without any moving parts in the system. After a quick introduction to the concept and optical design, this article presents the tolerancing study of the optical bench using this spectropolarimeter. The impact of different error sources, such as, birefringence uncertainty or decenter of the wedges, is investigated.

  8. Radical protection by differently composed creams in the UV/VIS and IR spectral ranges.

    Meinke, Martina C; Syring, Felicia; Schanzer, Sabine; Haag, Stefan F; Graf, Rüdiger; Loch, Manuela; Gersonde, Ingo; Groth, Norbert; Pflücker, Frank; Lademann, Jürgen

    2013-01-01

    Modern sunscreens are well suited to provide sufficient protection in the UV range because the filter substances absorb or scatter UV radiation. Although up to 50% of radicals are formed in the visible and infrared spectral range during solar radiation protection strategies are not provided in this range. Previous investigations of commercially available products have shown that in addition to physical filters, antioxidants (AO) are necessary to provide protective effects in the infrared range by neutralizing already formed radicals. In this study, the efficacy of filter substances and AO to reduce radical formation in both spectral ranges was investigated after UV/VIS or IR irradiation. Optical properties and radical protection were determined for the investigated creams. It was found that organic UV filters lower radical formation in the UV/VIS range to 35% compared to untreated skin, independent of the presence of AO. Further reduction to 14% was reached by addition of 2% physical filters, whereas physical filters alone were ineffective in the UV/VIS range due to the low concentration. In contrast, this filter type reduced radical formation in the IR range significantly to 65%; similar effects were aroused after application of AO. Sunscreens which contain organic UV filters, physical filters and AO ensure protection in the complete solar spectrum. PMID:23844556

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

    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- ...

  10. Ultraviolet-visible spectral properties of nanometer zinc oxide colloidal solution

    刘建本; 陈上; 吴竹青; 肖卓炳; 张永康; 黄伯云

    2003-01-01

    Nanometer zinc oxide was prepared by solid phase reaction. And the ultraviolet-visi-ble spectral properties of nanometer zinc oxide colloidal solution dispersed in both water and oilphases were studied. The results show that the absorbance of the colloidal solution to ultravioletlight increases with the decrease of wavelength and reaches about 2.5 at the wavelength of 200nm. When the mass fraction of nanometer zinc oxide becomes lower, the transmittance of the col-loidal solution to visible light gets higher, and it is much higher than that of normal zinc oxide un-der the same conditions, indicating that nanometer zinc oxide dispersed in both water and oil pha-ses has high transmittance to visible light and good shield to ultraviolet light. Therefore it is suit-able for the replacement of organic ultraviolet absorber and titanium dioxide in cosmetics.

  11. Method for detection and imaging over a broad spectral range

    Yefremenko, Volodymyr; Gordiyenko, Eduard; Pishko, legal representative, Olga; Novosad, Valentyn; Pishko, deceased; Vitalii

    2007-09-25

    A method of controlling the coordinate sensitivity in a superconducting microbolometer employs localized light, heating or magnetic field effects to form normal or mixed state regions on a superconducting film and to control the spatial location. Electron beam lithography and wet chemical etching were applied as pattern transfer processes in epitaxial Y--Ba--Cu--O films. Two different sensor designs were tested: (i) a 3 millimeter long and 40 micrometer wide stripe and (ii) a 1.25 millimeters long, and 50 micron wide meandering-like structure. Scanning the laser beam along the stripe leads to physical displacement of the sensitive area, and, therefore, may be used as a basis for imaging over a broad spectral range. Forming the superconducting film as a meandering structure provides the equivalent of a two-dimensional detector array. Advantages of this approach are simplicity of detector fabrication, and simplicity of the read-out process requiring only two electrical terminals.

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

    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

  13. Investigation of oxygen impurity transport using the O4+ visible spectral line in the Aditya tokamak

    Intense visible lines from Be-like oxygen impurity are routinely observed in the Aditya tokamak. The spatial profile of brightness of a Be-like oxygen spectral line (2p3p 3D3–2p3d 3F4) at 650.024 nm is used to investigate oxygen impurity transport in typical discharges of the Aditya tokamak. A 1.0 m multi-track spectrometer (Czerny–Turner) capable of simultaneous measurements from eight lines of sight is used to obtain the radial profile of brightness of O4+ spectral emission. The emissivity profile of O4+ spectral emission is obtained from the spatial profile of brightness using an Abel-like matrix inversion. The oxygen transport coefficients are determined by reproducing the experimentally measured emissivity profiles of O4+, using a one-dimensional empirical impurity transport code, STRAHL. Much higher values of the diffusion coefficient compared with the neo-classical values are observed in both the high magnetic field edge region (Dinboardmax∼30 m2 s-1) and the low magnetic field edge region (Doutboardmax∼45 m2 s-1) of typical Aditya ohmic plasmas, which seems to be due to fluctuation-induced transport. The diffusion coefficient at the limiter radius in the low-field (outboard) region is typically ∼ twice as high as that at the limiter radius in the high-field (inboard) region. (paper)

  14. 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

    Gurlit, W.; Bösch, H.; Bovensmann, H.; Burrows, J.P.; A. Butz; Camy-Peyret, C.; Dorf, M.; Gerilowski, K.; Lindner, A.; S. Noël; U. Platt; F. Weidner; Pfeilsticker, K.

    2004-01-01

    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...

  15. [The effect of spectral range on the measurement of ozone in the atmosphere by DOAS].

    Fu, Qiang; Peng, Fu-Min; Liu, Wen-Qing; Xie, Pin-Hua; Luo, Tao; Si, Fu-Qi; Li, Su-Wen

    2009-08-01

    Ozone (O3) often serves as the benchmark for the overall pollution level of a given airshed and it is critical that the measurement technique be accurate and precise, In the DOAS measurement, the accuracy of O3 concentration is determined by the selected spectral range. The present paper focuses on the effect of spectral range on the detected characteristic absorption structure of O3, and the variation of differential cross section of O3 with the change in spectral range and the source of interference in different spectral range. The effect of practical atmospheric light extinction on the light intensities of different spectral ranges was deduced; the effect of spectral range on the accuracy was determined by detecting the standard gases at different concentration and different spectral resolution. The optimized spectral range was determined for O3, which can yield high sensitivity, good selectivity and a reasonable time resolution for the accurate qualitative and quantitative analysis of O3. PMID:19839323

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

    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.

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

    Smolyaninova, V. N.; Smolyaninov, I. I.; 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.

  18. Statistical Analysis of Partial Discharges in SF6 Gas via Optical Detection in Various Spectral Ranges

    Ming Ren

    2016-03-01

    Full Text Available Partial discharge (PD detection is essential to the operation of high-voltage systems. In this context, we investigate the basic characteristics of light emission during PDs in SF6 gas from the perspective of insulation diagnosis. A synchronous system is constructed using three optical photoelectric instruments with separate wavelength responses in the ultraviolet (UV, 189–352 nm, visible (VIS, 381–675 nm, and near-infrared (NIR, 737–920 nm spectral ranges and a wide-band PD current pulse detector with a response of 1 pC. The results indicate that light emission depends upon the type of insulation defect and discharge energy. An increase in PD charge gives rise to more components in the spectral range from UV to VIS, and the presence of an insulator surface in discharges yields a more complex VIS-to-NIR spectrum. The phase-resolved partial discharge pattern (PRPD of UV light pulses can reasonably reflect the electroluminescence process in the presence of the insulator surface and weak corona at negative voltage points. The PRPD of VIS light describes the features of the actual PD pattern in most cases. In comparison with the other two spectral ranges, light intensity in the VIS range is more sensitive to changes in gas-pressure-normalized voltage (Vrms/p. The linear fitting analysis of the relationships between the light intensity and PD charge shows that UV light detection has a greater sensitivity to the PD charge and that UV detection exhibits a greater degree of linearity. NIR detection is applicable only to severe PDs. We believe that our findings can significantly aid in application of optical PD diagnosis in SF6 gas insulated systems.

  19. Multi-spectral laser detection and ranging for range profiling and surface characterization

    Wallace, A. M.; Buller, G. S.; Sung, R. C. W.; Harkins, R. D.; McCarthy, A.; Hernandez-Marin, S.; Gibson, G. J.; Lamb, R.

    2005-06-01

    We describe a new multi-spectral system for range profiling and surface characterization based on time-correlated single photon counting (TCSPC). This system has six laser diode sources with discrete wavelengths in the range 630-972 nm arranged around the circumference of the aperture of a receiving Schmidt-Cassegrain telescope that focuses the multiple wavelength return onto an optical fibre. Single photon avalanche diodes are used to detect the six independent wavelength channels, separated by an optical routing module. We also describe two methods for detecting the numbers, positions, heights and shape parameters of signal returns in the spectra returned from several surfaces within the sensor field of view. The first method has two principal stages, non-parametric bump hunting and maximum likelihood estimation using Poisson statistics. Recently we have adopted a reversible jump Markov chain Monte Carlo approach that has the potential for better detecting hidden or closely overlapping returns.

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

    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)

  1. Driver steering dynamics measured in car simulator under a range of visibility and roadmaking conditions

    Allen, R. W.; Mcruer, D. T.

    1977-01-01

    A simulation experiment was conducted to determine the effect of reduced visibility on driver lateral (steering) control. The simulator included a real car cab and a single lane road image projected on a screen six feet in front of the driver. Simulated equations of motion controlled apparent car lane position in response to driver steering actions, wind gusts, and road curvature. Six drivers experienced a range of visibility conditions at various speeds with assorted roadmaking configurations (mark and gap lengths). Driver describing functions were measured and detailed parametric model fits were determined. A pursuit model employing a road curvature feedforward was very effective in explaining driver behavior in following randomly curving roads. Sampled-data concepts were also effective in explaining the combined effects of reduced visibility and intermittent road markings on the driver's dynamic time delay. The results indicate the relative importance of various perceptual variables as the visual input to the driver's steering control process is changed.

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

    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.

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

    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.

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

    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 ...

  5. Experimental Demonstration of Non-Resonant Hyperlens in the Visible Range

    Sun, Jingbo; Litchinitser, Natalia M

    2014-01-01

    A metamaterial hyperlens offers a unique solution to overcome the diffraction limit by transforming evanescent waves responsible for imaging subwavelength features of an object into propagating waves. However, the first realizations of optical hyperlenses were limited by a narrow working bandwidth and significant resonance-induced loss. Here, we report the first experimental demonstration of a non-resonant waveguide-coupled hyperlens operating in the visible wavelength range. A detailed investigation of various materials systems proves that a radial fan-shaped configuration is superior to the concentric layer-based configuration in that it relies on non-resonant negative dielectric response, and, as a result, enables broadband and low-loss performance in the visible range.

  6. A visibility matching tone reproduction operator for high dynamic range scenes

    Larson, G.W. [Lawrence Berkeley National Lab., CA (United States); Rushmeier, H. [International Business Machines Corp., Yorktown Heights, NY (United States). Thomas J. Watson Research Center; Piatko, C. [National Inst. of Standards and Technology, Gaithersburg, MD (United States)

    1997-01-15

    The authors present a tone reproduction operator that preserves visibility in high dynamic range scenes. The method introduces a new histogram adjustment technique, based on the population of local adaptation luminances in a scene. To match subjective viewing experience, the method incorporates models for human contrast sensitivity, glare, spatial acuity and color sensitivity. They compare the results to previous work and present examples the techniques applied to lighting simulation and electronic photography.

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

    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)

  8. Polymeric Inverse Glasses for Development of Noniridescent Structural Colors in Full Visible Range.

    Lee, Gun Ho; Sim, Jae Young; Kim, Shin-Hyun

    2016-05-18

    Amorphous colloidal array with short-range order displays noniridescent structural colors due to the isotropic nature of the colloidal arrangement. The low angle dependence renders the colloidal glasses, which is promising for various coloration applications. Nevertheless, the colloidal glasses are difficult to develop red structural color due to strong cavity-like resonance from individual particles in the blue region. To suppress the cavity mode and develop the colors in the full visible range, we prepare inverse glasses composed of amorphous array of air cavities with short-range order. To produce the structures in a simple and reproducible manner, monodisperse silica particles are dispersed in a photocurable resin of poly(ethylene glycol) dimethacrylate (PEGDMA) at a volume fraction of 0.3. The particles spontaneously form the amorphous array with short-range order, which is rapidly captured in polymeric films by photopolymerization of the resin. Selective removal of silica particles from the polymerized resin leaves behind amorphous array of air cavities. The inverse glasses display structural colors with negligible backscattering in blue due to short optical path and low index in each cavity. Therefore, the colors can be tuned in full visible range by simply controlling the cavity size. The photocurable suspensions of silica particles can be patterned by photolithography, which enables the production of freestanding films containing patterned inverse glasses with noniridescent structural colors. PMID:27124719

  9. Single-order operation of lamellar multilayer gratings in the soft x-ray spectral range

    Meer, van der R.; Kozhevnikov, I.V.; Krishnan, B.; Huskens, J.; Hegeman, P.E.; Brons, C.; Vratzov, B.; Bastiaens, H.M.J.; Boller, K-J.; Bijkerk, F.

    2013-01-01

    We demonstrate single-order operation of Lamellar Multilayer Gratings in the soft x-ray spectral range. The spectral resolution was found to be 3.8 times higher than from an unpatterned multilayer mirror, while there were no significant spectral sideband structures adjacent to the main Bragg peak. T

  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

    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

    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. Single-order operation of lamellar multilayer gratings in the soft x-ray spectral range

    Robert van der Meer

    2013-01-01

    Full Text Available We demonstrate single-order operation of Lamellar Multilayer Gratings in the soft x-ray spectral range. The spectral resolution was found to be 3.8 times higher than from an unpatterned multilayer mirror, while there were no significant spectral sideband structures adjacent to the main Bragg peak. The measured spectral bandwidths and peak reflectivities were in good agreement with our theoretical calculations.

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

    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...

  14. Photonic crystal cavity modes in the visible range characterized by scattering spectroscopy

    We fabricate L3 cavities in a silicon nitride photonic crystal, with cavity modes in the visible range. We demonstrate a noninvasive method to characterize the cavities: the sample is illuminated on its edge and the upward-scattering spectrum is measured. We determine the modes' wavelengths, polarizations, and quality factors. We find modes between 700 and 830 nm with quality factors up to 280, polarized along or perpendicular to the cavity. The tuning of the cavity characteristics by means of its geometric parameters (holes sizes and shift) is discussed. The results are analyzed and compared with numerical simulations.

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

    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

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

    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.

  18. Supercontinuum generation using a selectively water-filled photonic crystal fiber for enhancement in the visible spectral region

    Yoshida, Eiichi; Wada, Akira; Karasawa, Naoki

    2016-07-01

    We generated a supercontinuum from a selectively water-filled photonic crystal fiber (PCF) for enhancement in the visible spectral region using an optical pulse from a Ti:sapphire oscillator at 804 nm. We prepared a 7-cm-long fused silica PCF, where the holes adjacent to the central core were filled with water, using a UV-curable adhesive to close holes selectively before filling holes with water by capillary force. Compared with that of the PCF without water, the group velocity dispersion curve of the selectively water-filled PCF became flatter near 800 nm and the intensity in the visible spectral region of the supercontinuum became higher and more uniform. The spectra simulated using the calculated dispersion properties of the selectively water-filled PCF showed good agreement with the experimental spectra.

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

    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 ...

  20. Infrared Spectroscopy with Visible Light

    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.

  1. Infrared spectroscopy with visible light

    Kalashnikov, Dmitry A.; Paterova, Anna V.; Kulik, Sergei P.; Krivitsky, Leonid A.

    2016-02-01

    Spectral measurements in the infrared optical range provide unique fingerprints of materials, which are useful for material analysis, environmental sensing and health diagnostics. Current infrared spectroscopy techniques require the use of optical equipment suited for operation in the infrared range, components of which face challenges of inferior performance and high cost. Here, we develop a technique that allows spectral measurements in the infrared range using visible-spectral-range components. The technique is based on nonlinear interference of infrared and visible photons, produced via spontaneous parametric down conversion. The intensity interference pattern for a visible photon depends on the phase of an infrared photon travelling through a medium. This allows the absorption coefficient and refractive index of the medium in the infrared range to be determined from the measurements of visible photons. The technique can substitute and/or complement conventional infrared spectroscopy and refractometry techniques, as it uses well-developed components for the visible range.

  2. Unattended real-time re-establishment of visibility in high dynamic range video and stills

    Abidi, B.

    2014-05-01

    We describe a portable unattended persistent surveillance system that corrects for harsh illumination conditions, where bright sun light creates mixed contrast effects, i.e., heavy shadows and washouts. These effects result in high dynamic range scenes, where illuminance can vary from few luxes to a 6 figure value. When using regular monitors and cameras, such wide span of illuminations can only be visualized if the actual range of values is compressed, leading to the creation of saturated and/or dark noisy areas and a loss of information in these areas. Images containing extreme mixed contrast cannot be fully enhanced from a single exposure, simply because all information is not present in the original data. The active intervention in the acquisition process is required. A software package, capable of integrating multiple types of COTS and custom cameras, ranging from Unmanned Aerial Systems (UAS) data links to digital single-lens reflex cameras (DSLR), is described. Hardware and software are integrated via a novel smart data acquisition algorithm, which communicates to the camera the parameters that would maximize information content in the final processed scene. A fusion mechanism is then applied to the smartly acquired data, resulting in an enhanced scene where information in both dark and bright areas is revealed. Multi-threading and parallel processing are exploited to produce automatic real time full motion corrected video. A novel enhancement algorithm was also devised to process data from legacy and non-controllable cameras. The software accepts and processes pre-recorded sequences and stills, enhances visible, night vision, and Infrared data, and successfully applies to night time and dark scenes. Various user options are available, integrating custom functionalities of the application into intuitive and easy to use graphical interfaces. The ensuing increase in visibility in surveillance video and intelligence imagery will expand the performance and

  3. Visible luminescence peculiar to sintered silica nanoparticles: Spectral and decay properties

    We report that the sintering at 1000 °C of silica nanoparticles (an average diameter of 14 nm) produces a transparent sample that exhibits a bright visible emission under UV excitation. The use of time resolved luminescence spectroscopy and a tunable laser source allows us to single out three contributions centered at 1.96 eV, 2.41 eV and 3.43 eV. The excitation spectra of these emissions evidence bell shaped bands consistent with transitions between localized defects’ states. For each emission we study the intensity and the lifetime in the temperature range from 300 K down to 10 K, thus evidencing the competition between radiative and non-radiative processes in the optical cycle of luminescent centers. The comparison with the luminescence properties of silica, both nanoparticles and bulk, points out that the observed emissions are peculiar to the sintered silica network. - Highlights: • Solid-phase sintering at 1000 °C of silica nanoparticles produces a transparent sample. • Sintered silica nanoparticles emit a bright luminescence under UV excitation. • Three emissions, centered around 2.0 V, 2.4 eV and 3.4 eV, are distinguished on the basis of the excitation and decay properties. • The observed excitation/emission bands originate from localized defect states peculiar to the sintered silica network. • The luminescence efficiency decreases with temperature due to the activation of non-radiative channels

  4. Statistical analysis of the impact of spectral correlation on observed formation constants from UV-visible spectroscopic measurements.

    Meinrath, Günther; Lis, Stefan; Piskula, Zbigniew

    2004-01-01

    Information retrieved from UV-visible spectroscopic data by application of a self-modelling factor analysis algorithm showed apparently systematically shifted thermodynamic properties for the same chemical system as a function of spectral slit widths. This empirical observation triggered a systematic investigation into the likely effects of residual and spectral correlation on the numerical results from quantitative spectroscopic investigations. If slit width was a nuisance factor it would reduce the comparability of information evaluated from spectroscopic data. The influence of spectral slit width was investigated by simulation, i.e. by generating and evaluating synthetic spectra with known properties. The simulations showed that increasing spectral correlation may introduce bias into factor analysis evaluations. By evaluation of the complete measurement uncertainty budget using threshold bootstrap target factor (TB CAT) analysis, the apparent shifts are insignificant relative to the total width of the quantity's measurement uncertainty. Increasing the slit widths causes some systematic effects, for example broadening of the registered spectral bands and reduction of spectral noise, because of higher light intensity passing to the detector. Hence, the observed systematic shifts in mean values might be caused by some latent correlation. As a general conclusion, slit width does not affect bias. However, the simulations show that spectral correlation and residual correlation may cause bias. Residual correlation can be taken into account by computer-intensive statistical methods, for example moving block or threshold bootstrap analysis. Spectral correlation is a property of the chemical system under study and cannot be manipulated. As a major result, evidence is given showing that stronger spectral correlation ( r<-0.7) causes non-negligible bias in the evaluated thermodynamic information from such a system. PMID:14615865

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

    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.

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

    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.

  7. Simulation study on reconstruction model of three-dimensional temperature distribution within visible range in furnace

    Liu Dong; Wang Fei; Huang Qun-Xing; Yan Jian-Hua; Chi Yong; Cen Ke-Fa

    2008-01-01

    This paper presents a reconstruction model of three-dimensional temperature distribution in furnace based on radiative energy images captured by charge-coupled device (CCD) cameras within the visible wavelength range. Numerical simulation case was used in this study and a zigzag eccentric temperature distribution was assumed to verify the model. Least square QR-factorization (LSQR) method was introduced to deal with reconstruction equation. It is found that the reconstructed temperature distributions in low-temperature areas had some fluctuations and high-temperature areas were reconstructed well The whole reconstruction relative error was mainly due to errors in low-temperature areas and the relative error for highest-temperature reconstruction was quite small.

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

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

    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.

  10. Retrieval of aerosol optical depth in the visible range with a Brewer spectrophotometer in Athens

    Diémoz, Henri; Eleftheratos, Kostas; Kazadzis, Stelios; Amiridis, Vassilis; Zerefos, Christos S.

    2016-04-01

    A MkIV Brewer spectrophotometer has been operating in Athens since 2004. Direct-sun measurements originally scheduled for nitrogen dioxide retrievals were reprocessed to provide aerosol optical depths (AODs) at a wavelength of about 440 nm. A novel retrieval algorithm was specifically developed and the resulting AODs were compared to those obtained from a collocated Cimel filter radiometer belonging to the Aerosol Robotic Network (AERONET). The series are perfectly correlated, with Pearson's correlation coefficients being as large as 0.996 and with 90 % of AOD deviations between the two instruments being within the World Meteorological Organisation (WMO) traceability limits. In order to reach such a high agreement, several instrumental factors impacting the quality of the Brewer retrievals must be taken into account, including sensitivity to the internal temperature, and the state of the external optics and pointing accuracy must be carefully checked. Furthermore, the long-term radiometric stability of the Brewer was investigated and the performances of in situ Langley extrapolations as a way to track the absolute calibration of the Brewer were assessed. Other sources of error, such as slight shifts of the wavelength scale, are discussed and some recommendations to Brewer operators are drawn. Although MkIV Brewers are rarely employed to retrieve AODs in the visible range, they represent a key source of information about aerosol changes in the past three decades and a potential worldwide network for present and future coordinated AOD measurements. Moreover, a better understanding of the AOD retrieval at visible wavelengths will also contribute in improving similar techniques in the more challenging UV range.

  11. Light polarizer in visible and THz range based on single-wall carbon nanotubes embedded into poly(methyl methacrylate) film

    Arutyunyan, N. R.; Kanygin, M. A.; Pozharov, A. S.; Kubarev, V. V.; Bulusheva, L. G.; Okotrub, A. V.; Obraztsova, E. D.

    2016-06-01

    Poly(methyl metacrylate) samples with uniformly dispersed single-wall carbon nanotubes (SWCNTs) were mechanicaly stretched up to 4 times at 150 °C. As a result, SWCNTs were oriented preferentially along the stretch direction. The width of the angular distribution of the SWCNT orientation determined by polarized Raman scattering and THz absorption spectroscopy was 15 and 12°, respectively. Both methods revealed a high anisotropy of optical response of the composite film. Its application as an efficient polarizer in a wide spectral range from visible to THz is promising.

  12. Set Up For Filter And Mirror Efficiencies Measurements In The UV and VUV Spectral Range

    Pouey, M.; Malherbe, A.

    1986-10-01

    A vacuum reflectometer for the UV and VUV spectral range was developed for qualification of optical components below 400 nm. Typical performances, in the 120-320 nm spectral range, of filters and mirrors offered by MATRA will be presented. Fitted with various gratings and sources this device allows reflecting, transmitting power as well as scattered or diffracted flux measurements (gratings efficiency measurements) until 25 nm.

  13. Ultrahigh-brightness, spectrally-flat, short-wave infrared supercontinuum source for long-range atmospheric applications.

    Yin, Ke; Zhu, Rongzhen; Zhang, Bin; Jiang, Tian; Chen, Shengping; Hou, Jing

    2016-09-01

    Fiber based supercontinuum (SC) sources with output spectra covering the infrared atmospheric window are very useful in long-range atmospheric applications. It is proven that silica fibers can support the generation of broadband SC sources ranging from the visible to the short-wave infrared region. In this paper, we present the generation of an ultrahigh-brightness spectrally-flat 2-2.5 μm SC source in a cladding pumped thulium-doped fiber amplifier (TDFA) numerically and experimentally. The underlying physical mechanisms behind the SC generation process are investigated firstly with a numerical model which includes the fiber gain and loss, the dispersive and nonlinear effects. Simulation results show that abundant soliton pulses are generated in the TDFA, and they are shifted towards the long wavelength side very quickly with the nonlinearity of Raman soliton self-frequency shift (SSFS), and eventually the Raman SSFS process is halted due to the silica fiber's infrared loss. A spectrally-flat 2-2.5 μm SC source could be generated as the result of the spectral superposition of these abundant soliton pulses. These simulation results correspond qualitatively well to the following experimental results. Then, in the experiment, a cladding pumped large-mode-area TDFA is built for pursuing a high-power 2-2.5 μm SC source. By enhancing the pump strength, the output SC spectrum broadens to the long wavelength side gradually. At the highest pump power, the obtained SC source has a maximum average power of 203.4 W with a power conversion efficiency of 38.7%. It has a 3 dB spectral bandwidth of 545 nm ranging from 1990 to 2535 nm, indicating a power spectral density in excess of 370 mW/nm. Meanwhile, the output SC source has a good beam profile. This SC source, to the best of our knowledge, is the brightest spectrally-flat 2-2.5 μm light source ever reported. It will be highly desirable in a lot of long-range atmospheric applications, such as broad-spectrum LIDAR, free

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

    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

  15. Dense two-dimensional silver single and double nanoparticle arrays with plasmonic response in wide spectral range.

    Drozdowicz-Tomsia, Krystyna; Baltar, Henrique T M C M; Goldys, Ewa M

    2012-06-19

    We report the properties of plasmons in dense planar arrays of silver single and double nanostructures with various geometries fabricated by electron beam lithography (EBL) as a function of their size and spacing. We demonstrate a strong plasmon coupling mechanism due to near-field dipolar interactions between adjacent nanostructures, which produces a major red shift of the localized surface plasmon resonance (LSPR) in silver nanoparticles and leads to strong maximum electric field enhancements in a broad spectral range. The extinction spectra and maximum electric field enhancements are theoretically modeled by using the finite element method. Our modeling revealed that strong averaged electric field enhancements of up to 60 in visible range and up to 40 in mid-infrared result from hybridization of multipolar resonances in such dense nanostructures; these are important for applications in surface enhanced spectroscopies. PMID:22439753

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

    Johansson, Sandra; Andersen, Martin; Tidemand-Lichtenberg, Peter;

    We propose a novel generic approach for generation of pulsed light in the visible spectrum based on sum-frequency generation between the high circulating intra-cavity power of a high finesse CW laser and a single-passed pulsed laser. For demonstration, we used a CW 1342 nm laser mixed with a pass...

  17. Detection of wavelengths in the visible range using fiber optic sensors

    Díaz, Leonardo; Morales, Yailteh; Mattos, Lorenzo; Torres, Cesar O.

    2013-11-01

    This paper shows the design and implementation of a fiber optic sensor for detecting and identifying wavelengths in the visible range. The system consists of a diffuse optical fiber, a conventional laser diode 650nm, 2.5mW of power, an ambient light sensor LX1972, a PIC 18F2550 and LCD screen for viewing. The principle used in the detection of the lambda is based on specular reflection and absorption. The optoelectronic device designed and built used the absorption and reflection properties of the material under study, having as active optical medium a bifurcated optical fiber, which is optically coupled to an ambient light sensor, which makes the conversion of light signals to electricas, procedure performed by a microcontroller, which acquires and processes the signal. To verify correct operation of the assembly were utilized the color cards of sewing thread and nail polish as samples for analysis. This optoelectronic device can be used in many applications such as quality control of industrial processes, classification of corks or bottle caps, color quality of textiles, sugar solutions, polymers and food among others.

  18. Low-loss optical waveguides for the near ultra-violet and visible spectral regions with Al2O3 thin films from atomic layer deposition

    In this work, we report low-loss single-mode integrated optical waveguides in the near ultra-violet and visible spectral regions with aluminum oxide (Al2O3) films using an atomic layer deposition (ALD) process. Alumina films were deposited on glass and fused silica substrates by the ALD process at substrate/chamber temperatures of 200 oC and 300 oC. Transmission spectra and waveguide measurements were performed in our alumina films with thicknesses in the range of 210-380 nm for the optical characterization. Those measurements allowed us to determine the optical constants (nw and kw), propagation loss, and thickness of the alumina films. The experimental results from the applied techniques show good agreement and demonstrate a low-loss optical waveguide. Our alumina thin-film waveguides are well transparent in the whole visible spectral region and also in an important region of the UV; the measured propagation loss is below 4 dB/cm down to a wavelength as short as 250 nm. The low propagation loss of these alumina guiding films, in particular in the near ultra-violet region which lacks materials with high optical performance, is extremely useful for several integrated optic applications.

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

    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.

  20. Analysis of the Intrinsic Mid-Infrared L-band to Visible--Near-Infrared Flux Ratios in Spectral Synthesis Models of Composite Stellar Populations

    Kim, Duho; Windhorst, Rogier A

    2016-01-01

    We analyze the intrinsic flux ratios of various visible--near-infrared filters with respect to 3.5micron for simple and composite stellar populations, and their dependence on age, metallicity and star formation history. UV/optical light from stars is reddened and attenuated by dust, where different sightlines across a galaxy suffer varying amounts of extinction. Tamura et al. (2009) developed an approximate method to correct for dust extinction on a pixel-by-pixel basis, dubbed the "beta_V" method, by comparing the observed flux ratio to an empirical estimate of the intrinsic ratio of visible and ~3.5micron data. Through extensive modeling, we aim to validate the "beta_V" method for various filters spanning the visible through near-infrared wavelength range, for a wide variety of simple and composite stellar populations. Combining Starburst99 and BC03 models, we built spectral energy distributions (SEDs) of simple (SSP) and composite (CSP) stellar populations for various realistic star formation histories (SF...

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

    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.

  2. Micro-optical elements functioning in non-visible spectral range

    Wang, Qin; Zhang, Andy Z. Z.; Bergström, Andreas; Huo, Vicky Z. J.; Almqvist, Susanne; Kaplan, Wlodek; Andersson, Jan Y.

    2010-05-01

    Nowadays novel micro-fabrication and wafer-based manufacturing approach allows realizing micro-optics in a way scientists have dreamt for generations, in particular, utilizing nano-imprint lithography as fabrication tooling enables greatly accelerating the micro-optics technology to its frontier. In this report, we present wafer-scale fabrication of various types of micro-optical elements based on photoresist, benzocyclobutene, photocurable imprint resist, and semiconductor materials by using thermal reflow, reactive ion etching, and imprint techniques. Especially, several concave or convex 3-dimensional micro-optical structures shaped by imprint method are detailed. These micro-optical elements can be monolithically or hybrid integrated onto optoelectronics devices, such as photodetectors and emitters as optical beam focuser, collimator, filter, or anti-reflectance elements. As application examples, polymer microlenses were integrated directly on the top of UV dual functional devices and quantum dot long wavelength infrared photodetectors, respectively.

  3. Luminescence of nuclear-induced rare-gas plasmas in near infrared spectral range

    Abramov, A. A.; Gorbunov, V. V.; Melnikov, S. P.; Mukhamatullin, A. Kh.; Pikulev, A. A.; Sinitsyn, A. V.; Sinyanskii, A. A.; Tsvetkov, V. M.

    2006-05-01

    The investigation results of the spectral-luminescent characteristics of rare gases He, Ne, Ar, Kr, and Xe and their binary mixtures He-Ne(Ar,Kr,Xe), Ne-Ar(Kr,Xe), Ar-Kr(Xe), and Kr-Xe under high pressures in the 740-1100 nm spectral range are presented. Excitation of gas media was carried out by uranium fission fragments. The information on the absolute intensities of the spectral lines belonging to the transitions of Nel, An, KrI, and XeI was obtained. The lines belonging to atomic transitions of 0, N, and C were also observed.

  4. Stark Broadening of several Ar I Spectral Lines in the Visible Part of the Spectrum

    Dimitrijevic, Milan S; Simic, Zoran; Sahal-Brechot, Sylvie

    2012-01-01

    In order to complete data on Stark broadening parameters for Ar I line in the visible spectrum, we determined Stark widths and shifts due to electron, proton, and ionized helium impacts, for nine lines (4191.0, 4259.4, 5912.1, 6043.2, 6045.0, 6752.9, 7503.9, 7514.6, 7724.2 {\\AA}), using jK coupling and semiclassical-perturbation theory. The obtained results will enter the STARK-B database, which is a part of Virtual Atomic and Molecular Data Center.

  5. High-q microring resonator with narrow free spectral range for pulse repetition rate multiplication

    Pu, Minhao; Ji, Hua; Frandsen, Lars Hagedorn;

    2009-01-01

    We demonstrate a silicon-on-insulator microring resonator with a free-spectral-range of 0.32 nm, an extinction ratio of 27 dB, and a quality factor of ~140900 at 1550 nm that is used for pulse repetition-rate multiplication from 10 to 40 GHz.......We demonstrate a silicon-on-insulator microring resonator with a free-spectral-range of 0.32 nm, an extinction ratio of 27 dB, and a quality factor of ~140900 at 1550 nm that is used for pulse repetition-rate multiplication from 10 to 40 GHz....

  6. UV and visible reflection spectral study of CO adsorption on the surface of yttrium, erbium, and holmium oxides

    Diffuse reflection spectroscopy in the UV and visible ranges was used to study the surface compounds formed upon the adsorption of CO on Y2O3, Er2O3, and Ho2-O3. The adsorption of CO at 300 K on a surface aged at 1073 K is accompanied by the appearance of bands at 340, 350, and 450 nm, which are related to dioxoketenes (C2O3)2-, croconates (CO)52-, and rhodizonates (CO)62-

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

    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

  8. Sb-free quantum cascade lasers in the 3–4 μm spectral range

    In this work, the design and implementation of Sb-free short wavelength strain-compensated quantum cascade lasers in the 3–4 μm spectral range is presented. Due to the presence of highly strained AlAs-barrier layers, the optimization of the epitaxial growth process is firstly discussed. The used active region design is then presented together with the observed laser performance. Watt-level room temperature emission at 3.3 μm is shown for Fabry–Perot devices and laser operation in pulsed mode is observed above 350 K. The laser performance is comparable with Sb-containing quantum cascade lasers. Spectral tuning of the lasers in an external cavity configuration over more than 275 cm−1 is achieved with an emission wavelength as short as 3.15 μm. For the first time in this spectral range, results on single-mode buried heterostructure distributed feedback lasers are shown. (paper)

  9. Multi-Nucleon Short-Range Correlation Model for Nuclear Spectral Functions: I. Theoretical Framework

    Artiles, Oswaldo

    2016-01-01

    We develop a theoretical approach for nuclear spectral functions at high missing momenta and removal energy based on the multi-nucleon short-range correlation~(SRC) model. The approach is based on the effective Feynman diagrammatic method which allows to account for the relativistic effects important in the SRC domain. In addition to two-nucleon SRC with center of mass motion we derived also the contribution of three-nucleon SRCs to the nuclear spectral functions. The latter is modeled based on the assumption that 3N SRCs are a product of two sequential short range NN interactions. This approach allowed us to express the 3N SRC part of the nuclear spectral function as a convolution of two NN SRCs. Thus the knowledge of 2N SRCs allows us to model both two- and three-nucleon SRC contribution to the spectral function. The derivations of the spectral functions are based on the two theoretical frameworks in evaluating covariant Feynman diagrams: In the first, referred as virtual nucleon approximation, we reduce Fe...

  10. Stability of curcumin in different solvent and solution media: UV-visible and steady-state fluorescence spectral study.

    Mondal, Satyajit; Ghosh, Soumen; Moulik, Satya P

    2016-05-01

    In aqueous solution, curcumin is photodegradable (light sensitive), it is also self-degradable in the dark. In basic medium, the second process is enhanced. The dark process has been studied in water and also in a number of protic and aprotic solvents, and aqueous solutions of ionic liquids, pluronics, reverse micelles and salt. The kinetics of the process followed the first order rate law; a comparative as well as individual assessment of which has been made. The kinetics of curcumin self-degradation has been found to be fairly dependent on salt (NaCl) concentration. Curcumin molecules in solution may remain in the enol or keto-enol form. From the visible spectral analysis, an estimate of the proportions of these forms in aqueous ethanol medium has been made. The temperature effect on the visible and fluorescence spectra of curcumin has been also studied. The steady state fluorescence anisotropy of the photoactive curcumin has been evaluated in different solvent and solution media. The reversibility of the steady state fluorescence anisotropy of curcumin on heating and cooling conditions has been examined. The results herein presented are new and ought to be useful as the study of physicochemistry of curcumin has been gaining importance in the light of its biological importance. PMID:26985735

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

    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

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

    Ahn, Yong-Jin; Park, Seung-Kyu; Baik, Sung-Hoon; Kim, Dong-Lyul; Choi, Young-Soo; Jeong, Kyung-Min [KAERI, Daejeon (Korea, Republic of)

    2015-05-15

    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.

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

    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

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

    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.

  15. Materials Pushing the Application Limits of Wire Grid Polarizers further into the Deep Ultraviolet Spectral Range

    Siefke, Thomas; Pfeiffer, Kristin; Puffky, Oliver; Dietrich, Kay; Franta, Daniel; Ohlídal, Ivan; Szeghalmi, Adriana; Kley, Ernst-Bernhard; Tünnermann, Andreas

    2016-01-01

    Wire grid polarizers (WGPs), periodic nano-optical meta-surfaces, are convenient polarizing elements for many optical applications. However, they are still inadequate in the deep ultraviolet spectral range. We show that to achieve high performance ultraviolet WGPs a material with large absolute value of the complex permittivity and extinction coefficient at the wavelength of interest has to be utilized. This requirement is compared to refractive index models considering intraband and interband absorption processes. We elucidate why the extinction ratio of metallic WGPs intrinsically humble in the deep ultraviolet, whereas wide bandgap semiconductors are superior material candidates in this spectral range. To demonstrate this, we present the design, fabrication and optical characterization of a titanium dioxide WGP. At a wavelength of 193 nm an unprecedented extinction ratio of 384 and a transmittance of 10 % is achieved.

  16. Against the long-range spectral leakage of the cosine window family

    Chen, Kui Fu; Jiang, Jing Tao; Crowsen, Stephen

    2009-06-01

    Suppressing spectral leakage in the fast Fourier transform (FFT) has been investigated for over 30 years. Regarding the frequently used cosine window family, it is observed that the long-range leakage sampled by FFT spectral lines follow a flat trajectory. Consequently, the long-range leakage is approximated by polynomials in this paper. In light of this parametric model, the interpolating formula is presented with up to nine-point for a cosine window with maximum side lobe decaying. Its expression is general in the window order and number of interpolating points. Some well-known formulas of the modulus-based interpolated FFT are parallel to special cases of the new formula, but the former are susceptible to significant bias at coherent sampling conditions. The new formula was tested with real-valued signals containing a single tone and then duel tones. It is demonstrated the new formula is easy to implement and is free of the significant bias aforementioned.

  17. High-dynamic-range quantitative phase imaging with spectral domain phase microscopy

    Zhang, Jun; Rao, Bin; Yu, Lingfeng; Chen, Zhongping

    2009-01-01

    Phase microscopy for high-dynamic-range quantitative phase-contrast imaging of a transparent phase object was demonstrated. Using a common path Fourier domain optical coherence tomography system, this technique is capable of displacement measurement with a sensitivity of 34 pm. The limitation of 2 π ambiguity restriction was overcome by the use of a phase retrieval approach performed in spectral domain. Two-dimensional quantitative phase imaging of human neonatal dermal keratinocyte cells was...

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

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

    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.

  20. Measurement and processing of signatures in the visible range using a calibrated video camera and the CAMDET software package

    Sheffer, Dan

    1997-06-01

    A procedure for calibration of a color video camera has been developed at EORD. The RGB values of standard samples, together with the spectral radiance values of the samples, are used to calculate a transformation matrix between the RGB and CIEXYZ color spaces. The transformation matrix is then used to calculate the XYZ color coordinates of distant objects imaged in the field. These, in turn, are used in order to calculate the CIELAB color coordinates of the objects. Good agreement between the calculated coordinates and those obtained from spectroradiometric data is achieved. Processing of the RGB values of pixels in the digital image of a scene using the CAMDET software package which was developed at EORD, results in `Painting Maps' in which the true apparent CIELAB color coordinates are used. The paper discusses the calibration procedure, its advantages and shortcomings and suggests a definition for the visible signature of objects. The Camdet software package is described and some examples are given.

  1. Application of microspectrometry in the visible range to differentiation of car paints for forensic purposes

    Trzcińska, B.; Zięba-Palus, J.; Kościelniak, P.

    2009-04-01

    The first step to be taken in forensic investigation of paint samples is their comparative analysis in terms of colour. Microspectrometers allow an objective measurement of colour as opposed to the subjective results of visual colour comparison. In this paper, results of assessment of the usefulness of spectral information obtained by Vis microspectrometry in differentiation of small paint coat fragments for criminalistic purposes are presented. Fragments of red, blue, brown and green car paints were measured in reflectance mode both directly on a cross-section of the paint chip and via the top layer using a light beam falling perpendicular to the top surface of the sample, and in transmittance mode. It was found that the results obtained were reproducible. The variation in colour of paint samples measured via the top layer was greater. The reflectance curve obtained constitutes a representation of colour.

  2. A sharp and visible range plasmonic in heavily doped metal oxide films

    As alternatives to conventional metals, metal oxide semiconductors offer many advantages in the field of plasmonic applications. Herein, the influence of antimony doping on the plasmon resonance properties of tin oxide films prepared by spray pyrolysis has been investigated. The colour of heavily doped antimony tin oxide films was tuned from colourless (transparent) to dark bluish. The crystallinity and morphology of these films were studied by x-ray diffraction and scanning electron microscopy. X-ray diffraction reveals that these films have purely cassetirite structure and no secondary phases of tin and antimony oxides are present. The surface morphology shows films have grainy structure which decreases with increase in antimony content. The Hall effect and electrical conductivity measurements show that the majority carriers are electrons and conductivity decreases by three orders of magnitude with increase in antimony content up to 50 wt%. The optical absorption shows that with increase in doping the plasmon peak becomes sharp and shifts to the visible region. Such plasmonic features are rarely reported on such materials. These results are analysed in terms of classical theory of surface plasmon resonance. The better plasmonic features, low cost, ease of synthesis and good chemical stability make these materials potential candidates for plasmonic applications. (papers)

  3. Model-based deduction of CMYK surface coverages from visible and infrared spectral measurements of halftone prints

    Bugnon, Thomas; Brichon, Mathieu; Hersch, Roger David

    2007-01-01

    The Yule-Nielsen modified Spectral Neugebauer reflection prediction model enhanced with an ink spreading model provides high accuracy when predicting reflectance spectra from ink surface coverages. In the present contribution, we try to inverse the model, i.e. to deduce the surface coverages of a printed color halftone patch from its measured reflectance spectrum. This process yields good results for cyan, magenta, and yellow inks, but unstable results when simultaneously fitting cyan, magenta, yellow, and black inks due to redundancy between these four inks: black can be obtained by printing either the black ink or similar amounts of the cyan, magenta, and yellow inks. To overcome this problem, we use the fact that the black pigmented ink absorbs light in the infrared domain, whereas cyan, magenta, and yellow inks do not. Therefore, with reflection spectra measurements spanning both the visible and infrared domain, it is possible to accurately deduce the black ink coverage. Since there is no redundancy anymore, the cyan, magenta, yellow, and pigmented black ink coverages can be recovered with high accuracy.

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

    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. Comparison of Free Spectral Range and Quality Factor for Two-Dimensional Square and Circular Microcavities

    国伟华; 黄永箴; 陆巧银; 于丽娟

    2004-01-01

    Free spectral range of whispering-gallery (WG)-like modes in a two-dimensional (2D) square microcavity is found to be twice that in a 2D circular microcavity. The quality factor of the WG-like mode with the low mode number in a 2D square microcavity, calculated by the finite-difference time-domain (FDTD) technique and the Pade approximation method, is found to exceed that of the WG mode in 2D circular microcavity with the same cavity dimension and close mode wavelength.

  6. Cytochrome c oxidase as a primary photoacceptor when laser irradiating cell culture by visible and near IR-range light

    Studies on laser effect of visible and near IR-range light on HeLa cell culture are carried out with the purpose of proving the assumption that cytochrome c oxidase cultivated in cells in-vitro is a primary photoacceptor. It is shown that light absorption by certain chromophores in cytochrome oxidase molecule (CuA, CuB, hemes a and a3) changes the rate of their oxidation, i.e. influences oxidations velocity (and, probably its mechanism) of electrons transfer inside the molecule. It is supposed that these reactions are connected with molecular mechanism of strict laser therapy at the single cell level. 15 refs., 1 fig

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

    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.

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

    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

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

    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.

  10. Range performance of the DARPA AWARE wide field-of-view visible imager.

    Nichols, J M; Judd, K P; Olson, C C; Novak, K; Waterman, J R; Feller, S; McCain, S; Anderson, J; Brady, D

    2016-06-01

    In a prior paper, we described a new imaging architecture that addresses the need for wide field-of-view imaging combined with the resolution required to identify targets at long range. Over the last two years substantive improvements have been made to the system, both in terms of the size, weight, and power of the camera as well as to the optics and data management software. The result is an overall improvement in system performance, which we demonstrate via a maritime target identification experiment. PMID:27411206

  11. Facility for fast mapping of total scattering and transmission in the spectral range from DUV- NIR

    Kadkhoda, P.; Jensen, L.; Ristau, D.

    2015-09-01

    A system for two dimensional mapping of Total Scattering (TS) and Transmission (T) of optical flat surfaces in the spectral range from deep UV to NIR will be introduced. The adaptation of the scatter detector concept for the special requirements of the DUV range will be discussed. Also, the specifications of the set-up such as working ambient, background level, and data calibration procedure demonstrate the performance of the system for the analytical tasks in industrial optics production. On the basis of the presented measurement facility, the essential properties of bare flat optics in respect of their polishing state, roughness level, state of cleaning and defect distribution can be investigated with the TS system in a nondestructive way. The homogeneity of the whole surface of an optical component can be tested with a defined lateral resolution. The knowledge of the inhomogeneity is an important indication for the quality evaluation of optical components. We present the TS result and the calculated defect density distributions of selected components, which are handled by different cleaning procedures. Also, additional effects in TS and T will be outlined and compared with spectral photometric measurement.

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

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

    2006-01-01

    integrated optical waveguides. Polymethylinethacrylate (PMMA) is dissolved in anisole and 'doped' with styrene-arcylonitrile copolymer to vary the refractive index. The doped PMMA with a higher refractive index is then spin coated onto a PMMA substrate with a lower refractive index to provide waveguide......Polymer waveguides fabricated from photoresist have an inherent high propagation loss in the short visible wavelength range caused by absorption due to the added photosensitizers. We have addressed this problem by development of two novel methods for the fabrication of microfluidic systems with...... 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...

  13. Fluorescent dye labeled DNA size standards for molecular mass detection in visible/infrared range

    Sreelakshmi Yellamaraju

    2011-01-01

    Full Text Available Abstract Background Targeting Induced Local Lesions in Genomes (TILLING is a high throughput reverse genetics tool which detects mismatches (single point mutations or small indels in large number of individuals of mutagenized populations. Currently, TILLING is intensively used for genomics assisted molecular breeding of several crop plants for desired traits. Most commonly used platform for mutation detection is Li-COR DNA Analyzer, where PCR amplified products treated with single strand mismatch specific nuclease are resolved on denaturing gels. The molecular size of any cut product can be easily estimated by comparing with IR dye labeled markers of known sizes. Similar fluorescent dye labeled size markers are also used for several genotyping experiments. Currently, commercially available size standards are expensive and are restricted up to only 700 bp which renders estimation of products of sizes greater than 700 bases inaccurate. Findings A simple protocol was developed for labeling 5' end of multiple DNA size markers with fluorescent dyes. This method involves cloning a pool of different size markers of DNA in a plasmid vector. PCR amplification of plasmid using IR dye labeled universal primers generates 5' fluorescent labeled products of various sizes. The size of products constituting the ladder can be customized as per the need. The generated size markers can be used without any further purification and were found to be stable up to one year at -20°C. Conclusions A simple method was developed for generating fluorescent dye labeled size standards. This method can be customized to generate different size standards as per experimental needs. The protocol described can also be adapted for developing labeled size standards for detection on platforms other than Li-COR i.e. other than infra red range of the spectrum.

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

    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

  15. Resonance-spacing tuning over whole free spectral range in a single microring resonator

    Gao, Ge; Yuan, Shuai; Li, Danping; Xia, Jinsong

    2016-03-01

    In this paper, we present a single microring resonator structure formed by incorporating a reflectivity-tunable loop mirror for the tuning of resonance spacing. Based on the optical mode-splitting in the resonator structure, spacing between two adjacent resonances can be tuned from zero to one whole free spectral range (FSR) by controlling the coupling strength between the two counter-propagating degenerate modes in the microring resonator. In experiment, by integrating metallic microheater, the resonance-spacing tuning over the whole FSR (1.17 nm) is achieved within 9.82 mW heating power dissipation. The device is expected to have potential applications in reconfigurable optical filtering and microwave photonics.

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

    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.

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

    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)

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

    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.

  19. Bremsstrahlung of Fast Charged Particles on Clusters in a Wide Spectral Range

    Within the framework of the first Born approximation and a simple model of the structural factor, the bremsstrahlung of fast charged particles on polyatomic clusters is calculated and analyzed with regard to the polarization mechanism in a wide spectral range including a domain of high frequencies. The role of cooperative phenomena in the static and polarization channels of bremsstrahlung is investigated. It is established that these phenomena, being negligible for static bremsstrahlung, substantially influence the polarization bremsstrahlung. It is shown that the constructive interference between the contributions of the atoms of a cluster to the polarization bremsstrahlung substantially increases its intensity and changes its dependence on the basic parameters of the problem compared with the case of bremsstrahlung on an isolated atom

  20. Bremsstrahlung of fast charged particles when scattering on clusters in wide spectral range

    Within the framework of the first Born approximation and a simple model of the structural factor, the bremsstrahlung of fast charged particles on polyatomic clusters is calculated and analyzed with regard to the polarization mechanism in a wide spectral range including a domain of high frequencies. The role of cooperative phenomena in the static and polarization channels of bremsstrahlung is investigated. It is established that these phenomena, being negligible for static bremsstrahlung, substantially influence the polarization bremsstrahlung. It is shown that the constructive interference between the contributions of the atoms of a cluster to the polarization bremsstrahlung substantially increases its intensity and changes its dependence on the basic parameters of the problem compared with the case of bremsstrahlung on an isolated atom

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

    Wooden, D. H.; Cook, A.; Colaprete, A.; Shirley, M.; Vargo, K.; Elphic, R. C.; Hermalyn, B.; Stubbs, T. J.; Glenar, D. A.

    2014-12-01

    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 [1, 2]. 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 [2,3,4]. On the dark side of the moon, "Sodium Tail" activities pointed the limb-viewing telescope in the direction of the Moon's sodium tail (~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 (~100 nm) dust grains in the tail. Correlations are sought between dust in the sodium tail and meteor streams [5] and magnetotail [3] crossings to investigate impact- versus electrostatic-lofting [6]. Once lofted, nanoparticles can become charged and picked up by the solar wind [7,8]. The LADEE UVS Occultation, Inertial Limb, and Sodium Tail spectral datasets provide

  2. Plasmonic Gold Helices for the visible range fabricated by oxygen plasma purification of electron beam induced deposits

    Haverkamp, Caspar; Jäckle, Sara; Manzoni, Anna; Christiansen, Silke

    2016-01-01

    Electron beam induced deposition (EBID) currently provides the only direct writing technique for truly three-dimensional nanostructures with geometrical features below 50 nm. Unfortunately, the depositions from metal-organic precursors suffer from a substantial carbon content. This hinders many applications, especially in plasmonics where the metallic nature of the geometric surfaces is mandatory. To overcome this problem a post-deposition treatment with oxygen plasma at room temperature was investigated for the purification of gold containing EBID structures. Upon plasma treatment, the structures experience a shrinkage in diameter of about 18 nm but entirely keep their initial shape. The proposed purification step results in a core-shell structure with the core consisting of mainly unaffected EBID material and a gold shell of about 20 nm in thickness. These purified structures are plasmonically active in the visible wavelength range as shown by dark field optical microscopy on helical nanostructures. Most no...

  3. Effect of spectral range in surface inactivation of Listeria innocua using broad-spectrum pulsed light.

    Woodling, Sarah E; Moraru, Carmen I

    2007-04-01

    Pulsed light (PL) treatment is an alternative to traditional thermal treatment that has the potential to achieve several log-cycle reductions in the concentration of microorganisms. One issue that is still debated is related to what specifically causes cell death after PL treatments. The main objective of this work was to elucidate which portions of the PL range are responsible for bacterial inactivation. Stainless steel coupons with controlled surface properties were inoculated with a known concentration of Listeria innocua in the stationary growth phase and treated with 1 to 12 pulses of light at a pulse rate of 3 pulses per s and a pulse width of 360 micros. The effects of the full spectrum (lambda = 180 to 1,100 nm) were compared with the effects obtained when only certain regions of UV, visible, and near-infrared light were used. The effectiveness of the treatments was determined in parallel by the standard plate count and most-probable-number techniques. At a fluence of about 6 J/cm(2), the full-spectrum PL treatment resulted in a 4.08-log reduction of L. innocua on a Mill finish surface, the removal of lambda 400 nm). This work provides additional supporting evidence that cell death in PL treatment is due to exposure to UV light. Additionally, it was shown that even a minor modification of the light path or the UV light spectrum in PL treatments can have a significant negative impact on the treatment intensity and effectiveness. PMID:17477260

  4. Pulsed, all solid-state light source in the visible spectral region based on non-linear cavity dumping

    Tidemand-Lichtenberg, Peter; Andersen, Martin; Johansson, Sandra;

    We propose a novel generic approach for generation of pulsed light in the visible spectrum, based on SFG between the high circulating intra-cavity power of a high finesse CW laser and a single-passed pulsed laser....

  5. Retrieval interval mapping, a tool to optimize the spectral retrieval range in differential optical absorption spectroscopy

    Vogel, L.; Sihler, H.; Lampel, J.; Wagner, T.; Platt, U.

    2012-06-01

    Remote sensing via differential optical absorption spectroscopy (DOAS) has become a standard technique to identify and quantify trace gases in the atmosphere. The technique is applied in a variety of configurations, commonly classified into active and passive instruments using artificial and natural light sources, respectively. Platforms range from ground based to satellite instruments and trace-gases are studied in all kinds of different environments. Due to the wide range of measurement conditions, atmospheric compositions and instruments used, a specific challenge of a DOAS retrieval is to optimize the parameters for each specific case and particular trace gas of interest. This becomes especially important when measuring close to the detection limit. A well chosen evaluation wavelength range is crucial to the DOAS technique. It should encompass strong absorption bands of the trace gas of interest in order to maximize the sensitivity of the retrieval, while at the same time minimizing absorption structures of other trace gases and thus potential interferences. Also, instrumental limitations and wavelength depending sources of errors (e.g. insufficient corrections for the Ring effect and cross correlations between trace gas cross sections) need to be taken into account. Most often, not all of these requirements can be fulfilled simultaneously and a compromise needs to be found depending on the conditions at hand. Although for many trace gases the overall dependence of common DOAS retrieval on the evaluation wavelength interval is known, a systematic approach to find the optimal retrieval wavelength range and qualitative assessment is missing. Here we present a novel tool to determine the optimal evaluation wavelength range. It is based on mapping retrieved values in the retrieval wavelength space and thus visualize the consequence of different choices of retrieval spectral ranges, e.g. caused by slightly erroneous absorption cross sections, cross correlations and

  6. Long-range high-speed visible light communication system over 100-m outdoor transmission utilizing receiver diversity technology

    Wang, Yiguang; Huang, Xingxing; Shi, Jianyang; Wang, Yuan-quan; Chi, Nan

    2016-05-01

    Visible light communication (VLC) has no doubt become a promising candidate for future wireless communications due to the increasing trends in the usage of light-emitting diodes (LEDs). In addition to indoor high-speed wireless access and positioning applications, VLC usage in outdoor scenarios, such as vehicle networks and intelligent transportation systems, are also attracting significant interest. However, the complex outdoor environment and ambient noise are the key challenges for long-range high-speed VLC outdoor applications. To improve system performance and transmission distance, we propose to use receiver diversity technology in an outdoor VLC system. Maximal ratio combining-based receiver diversity technology is utilized in two receivers to achieve the maximal signal-to-noise ratio. A 400-Mb/s VLC transmission using a phosphor-based white LED and a 1-Gb/s wavelength division multiplexing VLC transmission using a red-green-blue LED are both successfully achieved over a 100-m outdoor distance with the bit error rate below the 7% forward error correction limit of 3.8×10-3. To the best of our knowledge, this is the highest data rate at 100-m outdoor VLC transmission ever achieved. The experimental results clearly prove the benefit and feasibility of receiver diversity technology for long-range high-speed outdoor VLC systems.

  7. All-semiconductor plasmonic gratings for biosensing applications in the mid-infrared spectral range.

    Barho, Franziska B; Gonzalez-Posada, Fernando; Milla-Rodrigo, Maria-José; Bomers, Mario; Cerutti, Laurent; Taliercio, Thierry

    2016-07-11

    We propose 1D periodic, highly doped InAsSb gratings on GaSb substrates as biosensing platforms applicable for surface plasmon resonance and surface enhanced infrared absorption spectroscopies. Based on finite-difference time-domain simulations, the electric field enhancement and the sensitivity on refractive index variations are investigated for different grating geometries. The proposed, optimized system achieves sensitivities of 900 nm RIU-1. A clear red shift of the plasmon resonance as well as the enhancement of an absorption line are presented for 2 nm thin adlayers in simulations. We experimentally confirm the high sensitivity of the InAsSb grating by measurements of the wavelength shift induced by a 200 nm thin polymethylmethacrylate layer and demonstrate an enhancement of vibrational signals. A comparison to a gold grating with equivalent optical properties in the mid-infrared is performed. Our simulations and experimental results underline the interest in the alternative plasmonic material InAsSb for highly sensitive biosensors for the mid-infrared spectral range. PMID:27410884

  8. Relative calibration of photodiodes in the soft-x-ray spectral range

    A method of obtaining a relative calibration of Si photodiodes for the spectral range of soft x rays (1--30 keV) is presented. A simple mathematical model of the p-n diode is adopted which allows the response to be described in terms of a small set of parameters. The diffusion length as well as the thickness of a dead layer below the front surface of the diodes are obtained from measurements of angular dependences of the photoinduced current. It is shown that a precise characterization of the diode response and an accurate relative calibration can be obtained using this method. However, it was found that the presence of a dead layer a few tenths of a micrometer thick can pose severe restrictions on the use of planar diode arrays in x-ray tomography systems where uniformity of response is crucial. The method has been applied to the diode arrays equipping the x-ray tomography system built for the TCV tokamak, a magnetic fusion research device. copyright 1995 American Institute of Physics

  9. A diffraction-limited scanning system providing broad spectral range for laser scanning microscopy

    Yu, Jiun-Yann; Liao, Chien-Sheng; Zhuo, Zong-Yan; Huang, Chen-Han; Chui, Hsiang-Chen; Chu, Shi-Wei

    2009-11-01

    Diversified research interests in scanning laser microscopy nowadays require broadband capability of the optical system. Although an all-mirror-based optical design with a suitable metallic coating is appropriate for broad-spectrum applications from ultraviolet to terahertz, most researchers prefer lens-based scanning systems despite the drawbacks of a limited spectral range, ghost reflection, and chromatic aberration. One of the main concerns is that the geometrical aberration induced by off-axis incidence on spherical mirrors significantly deteriorates image resolution. Here, we demonstrate a novel geometrical design of a spherical-mirror-based scanning system in which off-axis aberrations, both astigmatism and coma, are compensated to reach diffraction-limited performance. We have numerically simulated and experimentally verified that this scanning system meets the Marechà l condition and provides high Strehl ratio within a 3°×3° scanning area. Moreover, we demonstrate second-harmonic-generation imaging from starch with our new design. A greatly improved resolution compared to the conventional mirror-based system is confirmed. This scanning system will be ideal for high-resolution linear/nonlinear laser scanning microscopy, ophthalmoscopic applications, and precision fabrications.

  10. In-flight validation and calibration of the spectral and radiometric characteristics of the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS)

    Green, Robert O.; Conel, James E.; Margolis, Jack S.; Carrere, Veronique; Bruegge, Carol J.; Rast, Michael; Hoover, Gordon

    1990-01-01

    Through an in-flight calibration experiment at Rogers Dry Lake, California on September 20, 1989, the radiometric and spectral properties of AVIRIS were determined. In-flight spectral channel positions and the spectral response function in 10 regions of the AVIRIS spectral range, taking in all four spectrometers, are shown to agree closely with the corresponding parameters measured in the laboratory. The intraflight stability for the Rogers Dry Lake calibration site is better than 2 percent with the exception of the strong atmospheric water absorptions where the measured radiance is close to zero. This experiment has provided both direct generation of an in-flight spectral and radiometric calibration and validation of the laboratory calibration at the reported level accuracy.

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

    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.

  12. Characterization of spectral hole depth in Tm3+ :YAG within the cryogenic temperature range

    Chen Lei; Ma Xiu-Rong; Wang Wei; Zhang Shuang-Gen; Mu Kuan-Lin; Wang Xia-Yang; Zhang Shi-Yu

    2013-01-01

    In this paper,spectral hole depth dependence on temperature below 10 K in Tm3+∶YAG crystal is investigated in detail.A novel model is proposed to analyze the temperature dependence on the spectral hole.By using the proposed model,we theoretically deduce the temperature dependence of spectral hole depth.The results are compared with experimental results and they are in good agreement.According to the theoretic results,the optimum temperature in experiment can be found.

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

    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...

  14. High-resolution and nondestructive profile measurement by spectral-domain optical coherence tomography with a visible broadband light source for optical-device fabrication

    Nishi, Tsuyoshi; Ozaki, Nobuhiko; Oikawa, Yoichi; Miyaji, Kunio; Ohsato, Hirotaka; Watanabe, Eiichiro; Ikeda, Naoki; Sugimoto, Yoshimasa

    2016-08-01

    We developed a spectral-domain optical coherence tomography (OCT) using a visible broadband light source (vis-OCT) for application to high-resolution and nondestructive profile measurement and imaging in semiconductor optical-device fabrication. By using visible broadband light centered at 625 nm and with spectral bandwidth of 260 nm, an axial resolution of 0.69 µm in air was obtained. This was effective for inspection of a transparent photoresist film with thickness of 1–2 µm coated on a semiconductor wafer; the interface between the photoresist film and its substrate and the interface between the photoresist and air were resolved, and the film thickness was measured. In addition, the interface between an opaque epitaxially grown semiconductor layer (Al0.35Ga0.65As) and a GaAs substrate was also detected by vis-OCT. Here we propose a thickness-measurement technique that combines finite-difference time-domain simulation with vis-OCT. This method enables us to determine the thickness of even an optically absorbent epitaxial layer and offers a profile-measurement method that is particularly suitable for the fabrication of semiconductor optical devices.

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

    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.

  16. Optical performance of B-layer ultra-shallow-junction silicon photodiodes in the VUV spectral range

    Shi, L.; Sarubbi, F.; Nanver, L.K.; Kroth, U.; Gottwald, A.; Nihtianov, S.

    2010-01-01

    In recent work, a novel silicon-based photodiode technology was reported to be suitable for producing radiation detectors for 193 nm deep-ultraviolet light and for the extreme-ultraviolet (EUV) spectral range. The devices were developed and fabricated at the Delft Institute of Microsystems and Nanoe

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

    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

  18. First observation of SASE radiation using the compact wide-spectral-range XUV spectrometer at FLASH2

    Tanikawa, T.; Hage, A.; Kuhlmann, M.; Gonschior, J.; Grunewald, S.; Plönjes, E.; Düsterer, S.; Brenner, G.; Dziarzhytski, S.; Braune, M.; Brachmanski, M.; Yin, Z.; Siewert, F.; Dzelzainis, T.; Dromey, B.; Prandolini, M. J.; Tavella, F.; Zepf, M.; Faatz, B.

    2016-09-01

    The Free-electron LASer in Hamburg (FLASH) has been extended with a new undulator line FLASH2 in 2014. A compact grazing-incident wide-spectral-range spectrometer based on spherical-variable-line-spacing (SVLS) gratings in the extreme ultraviolet (XUV) region was constructed to optimize and characterize the free-electron laser (FEL) performance at FLASH2. The spectrometer is equipped with three different concave SVLS gratings covering a spectral range from 1 to 62 nm to analyze the spectral characteristics of the XUV radiation. Wavelength calibration and evaluation of the spectral resolution were performed at the plane grating monochromator beamline PG2 at FLASH1 before the installation at FLASH2, and compared with analytical simulations. The first light using self-amplified spontaneous emission from FLASH2 was observed by the spectrometer during a simultaneous operation of both undulator lines-FLASH1 and FLASH2. In addition, the spectral resolution of the spectrometer was evaluated by comparing the measured spectrum from FLASH2 with FEL simulations.

  19. Efficient noncollinear parametric amplification of weak femtosecond pulses in the visible and near-infrared spectral range.

    Krylov, V; Ollikainen, O; Gallus, J; Wild, U; Rebane, A; Kalintsev, A

    1998-01-15

    We report measurement of efficient amplification of weak femtosecond supercontinuum seed pulses by use of a noncollinear optical parametric process in BBO crystal pumped with 150-fs pulses from a frequency-doubled regenerative-amplified Ti:sapphire laser at 390nm . The highest amplification factor, 10(8) , was achieved for 3x10(-16)J energy seed pulses at wavelength of 560nm. PMID:18084425

  20. Cu-Fe-S Nanocrystals Exhibiting Tunable Localized Surface Plasmon Resonance in the Visible to NIR Spectral Ranges.

    Gabka, Grzegorz; Bujak, Piotr; Ostrowski, Andrzej; Tomaszewski, Waldemar; Lisowski, Wojciech; Sobczak, Janusz W; Pron, Adam

    2016-07-01

    Cu-Fe-S nanocrystals exhibiting a strong localized surface plasmon resonance (LSPR) effect were synthesized for the first time. The elaborated reproducible preparation procedure involved copper(II) oleate, iron(III) stearate, and sulfur powder dissolved in oleylamine (OLA) as precursors. The wavelength of the plasmonic resonance maximum could be tuned by changing the Cu/Fe ratio in the resulting nanocrystals, being the most energetic for the 1:1 ratio (486 nm) and undergoing a bathochromic shift to ca. 1200 nm with an increase to 6:1. LSPR could also be observed in nanocrystals prepared from the same metal precursors and sulfur powder dissolved in 1-octadecene (ODE), provided that the sulfur precursor was taken in excess. Detailed analysis of the reaction mixture by chromatographic techniques, supplemented by mass spectrometry and (1)H NMR spectroscopy enabled the identification of the true chemical nature of the sulfur precursor in S/OLA, namely, (C18H35NH3(+))(C18H35NH-S8(-)), a reactive product of the reduction of elemental sulfur by the amine groups of OLA. In the case of the S/ODE precursor, the true precursors are much less reactive primary or secondary thioethers and dialkyl polysulfides. PMID:27300320

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

    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...

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

    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.

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

    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.

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

    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.

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

    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.

  6. THE SECOND STAGE OF FERMI@ELETTRA: A SEEDED FEL IN THE SOFT X-RAY SPECTRAL RANGE

    Allaria, E.; DeNinno, G.; Fawley, W. M.

    2009-08-14

    The second stage of the FERMI FEL, named FEL-2, is based on the principle of high-gain harmonic generation and relies on a double-seeded cascade. Recent developments stimulated a revision of the original setup, which was designed to cover the spectral range between 40 and 10 nm. The numerical simulations we present here show that the nominal (expected) electron-beam performance allows extension of the FEL spectral range down to 4 nm. A significant amount of third harmonic power can be also expected. We also show that the proposed setup is flexible enough for exploiting future developments of new seed sources, e.g., high harmonic generation in gases.

  7. THE SECOND STAGE OF FERMI at ELETTRA: A SEEDED FEL IN THE SOFT X-RAY SPECTRAL RANGE

    The second stage of the FERMI FEL, named FEL-2, is based on the principle of high-gain harmonic generation and relies on a double-seeded cascade. Recent developments stimulated a revision of the original setup, which was designed to cover the spectral range between 40 and 10 nm. The numerical simulations we present here show that the nominal (expected) electron-beam performance allows extension of the FEL spectral range down to 4 nm. A significant amount of third harmonic power can be also expected. We also show that the proposed setup is flexible enough for exploiting future developments of new seed sources, e.g., high harmonic generation in gases.

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

    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

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

    Darginavičius, 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...

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

    Jung, J; Kim, Y. J.; Lee, K Y.; M. G. -Cayetano; T. Batmunkh; J.-H. Koo; Kim, J.

    2010-01-01

    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 ...

  11. 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)

    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)

  12. [Ultraviolet-visible (UV-Vis) and fluorescence spectral characteristics of soil dissolved organic matter (DOM) in typical agricultural watershed of Three Gorges Reservoir Region].

    Wang, Qi-Lei; Jiang, Tao; Zhao, Zheng; Mu, Zhi-Jian; Wei, Shi-Qiang; Yan, Jin-Long; Liang, Jian

    2015-03-01

    As an important geo-factor to decide the environmental fate of pollutants in watershed, soil dissolved organic matter (DOM) sampled from a typical agricultural watershed in the Three Gorges Reservoir area was investigated using ultraviolet-visible (UV-Vis) and fluorescence spectroscopies, to analyze and discuss the effect of different land uses including forest, cropland, vegetable field and residence, on soil DOM geochemical characteristics. The results showed that significant differences in DOM samples amongst different land uses were observed, and DOM from forest had the highest aromaticity and humification degree, followed by DOM from cropland. Although DOM from vegetable field and residence showed the highest dissolved organic carbon (DOC) concentration (average values 0.81 g x kg(-1) and 0.89 g x kg(-1), respectively), but the aromaticity was lower indicating lower humification, which further suggested that the non-chromophoric component in these DOM samples contributed significantly to total DOM compositions. Additionally, in all DOM samples that were independent of land uses, fluorescence index (FI) values were between 1.4 (terrigenous) and 1.9 (authigenic) , evidently indicating both the allochthonous and autochthonous sources contributed to DOM characteristics. Meanwhile, r(T/C) values in most of samples were higher than 2.0, suggesting that soil DOM in this agricultural watershed was heavily affected by anthropogenic activities such as agricultural cultivation, especially, vegetable field was a good example. Additionally, sensitivities of different special spectral parameters for reflecting the differences of DOM characteristics amongst different land uses were not identical. For example, neither spectral slope ratio (S(R)) nor humification index (HIX) could clearly unveil the various geochemical characteristics of soil DOM from different sources. Thus, simple and single special spectral parameter cannot comprehensively provide the detailed information

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

    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%.

  14. Fourier transform measurements of H218O and HD18O in the spectral range 1000-2300 cm-1

    The spectra of water vapor enriched by 18O were recorded in the 1000-2300 cm-1 spectral range, which corresponds to the spectral region studied by IASI instrument (Infrared Atmospheric Sounding Spectrometer) instrument. The spectra were recorded by a step by step Fourier Transform Spectrometer (FTS) at room temperature with absorption path lengths up to 36 m. Positions, intensities and self broadening coefficients of about 1800 lines of H218O and 900 of HD18O were analyzed and all the transitions were assigned. This paper focuses on lines intensities and comparisons with data from literature are presented. An average difference of 10% with HITRAN2008 database H218O line intensities is found with a maximum discrepancy of about 25% for the ν1-ν2 band.

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

    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 μm spectral range. ► Emissivity increases linearly with temperature, with the same slope for λ > 10 μm. ► 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 μm to about 0.10 at 22 μm. 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.

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

    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.

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

    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, σabs(=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.

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

    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.

  19. Phototransformation of 2,4,6-trinitrotoluene: Sensitized by riboflavin under different irradiation spectral range

    Yang Xin [Department of Biology, Jackson State University, Jackson, MS 39217 (United States); Beijing Institute of Pharmacology and Toxicology, Beijing 100850 (China); Zhao Xueheng [Department of Biology, Jackson State University, Jackson, MS 39217 (United States); Hwang, H.-M. [Department of Biology, Jackson State University, Jackson, MS 39217 (United States)]. E-mail: hwang@jsums.edu

    2007-05-08

    Riboflavin-sensitized phototransformation of 2,4,6-trinitrotoluene (TNT) under natural sunlight was investigated with reverse-phase high performance liquid chromatography/mass spectrometry (HPLC/MS) and gas chromatography/mass spectrometry (GC/MS). The effect of different spectral region of sunlight on TNT phototransformation in the absence or presence of riboflavin was also investigated by using optical filters with cut-off at 400 or 455 nm. The concentration of riboflavin in the phototransformation of TNT was optimized. Concentration of riboflavin and TNT was 1.0 and 50 {mu}M, respectively. The rates of phototransformation of TNT under natural sunlight in the presence or absence of riboflavin were conformed to initial pseudo-first-order rate equation. The photolysis half life of TNT in the presence of riboflavin was 21.87 min, compared to 39 min in the absence of riboflavin under natural sunlight. Two major phototransformation products of TNT, 3,5-dinitroaniline (3,5-DNA) and 1,3,5-trinitrobenzene (1,3,5-TNB), were detected in the samples in the presence of riboflavin receiving irradiation at full wavelength or wavelength >400 nm. The results indicate that riboflavin mediates TNT sensitized-phototransfomation under natural sunlight or near-UV-vis light.

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

    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.

  1. Optical properties of parietal peritoneum in the spectral range 350-2500 nm

    Kozintseva, Marina D.; Bashkatov, Alexey N.; Kochubey, Vyacheslav I.; Genina, Elina A.; Gorodkov, Sergey Y.; Morozov, Dmitry A.; Tuchin, Valery V.

    2014-01-01

    The wide application of optical methods in the areas of diagnostics, therapy and surgery of modern medicine has stimulated the investigation of optical properties of various biological tissues. Numerous investigations related to determination of tissue optical properties are available; however, the optical properties of many tissues have not been studied in a wide wavelength range. In this work the optical properties of parietal peritoneum in the wavelength range 350-2500 nm were measured. Measurement of the diffuse reflectance, total and collimated transmittance were performed using LAMBDA 950 (Perkin Elmer, USA) spectrophotometer with an integrating sphere, and values of absorption and scattering coefficients, and the scattering anisotropy factor were calculated by inverse Monte Carlo Method.

  2. Long range wind lidars based on novel high spectral brilliance all-fibered sources

    Lombard, L.; Dolfi-Bouteyre, A.; Besson, C.; Augère, B.; Bourdon, P.; Durécu, A.; Goular, D.; Le Gouët, J.; Planchat, C.; Renard, W.; Valla, M.; Canat, G.

    2015-10-01

    New Lidar applications related to aircraft safety in the area of an airport include mapping wind velocity and monitoring turbulences within a radius longer than 8km in a short acquisition time (360° map in 1 minute). During landing and takeoff, a minimal distance separation between aircrafts is set by referring to wake turbulence categories. However, it was shown that wake vortices can dissipate quicker because of atmospheric turbulence (characterized by eddy dissipation rate - EDR) or can be transported out of the way on oncoming traffic by cross-winds. Long range scanning Lidars provide radial wind data that can be used to calculate EDR. To reach long range within a short acquisition time, coherent wind Lidars require high power (~kW), narrow linewidth (few MHz) pulsed laser sources with nearly TF limited pulse duration (~1μs). Eyesafe, all-fiber laser sources based on MOPFA (master oscillator, power fiber amplifier) architecture offer many advantages over bulk sources such as low sensitivity to vibrations, efficiency and versatility. However, narrow linewidth pulsed fiber lasers and amplifiers are usually limited by nonlinear effects such as stimulated Brillouin scattering (SBS) to 300W with commercial fibers. We investigated various solutions to push this limit further. For example, a source based on a new fiber composition yielded a peak power of 1120W for 650ns pulse duration with excellent beam quality. Based on these innovative solutions we built a Lidar with a record range of 16km in 0.1s averaging time. In this proceeding, we present some recent results obtained with our wind Lidars based on these high power sources with record ranges. EDR measurements using the developed algorithm based on structure function calculation are presented, as well as its validation with simulations and measurements campaign results.

  3. Spectral Analysis of a Two Body Problem with Zero Range Perturbation

    Correggi, M; Antonio, G; Finco, D.

    2007-01-01

    We consider a class of singular, zero-range perturbations of the Hamiltonian of a quantum system composed by a test particle and a harmonic oscillators in dimension one, two and three and we study its spectrum. In facts we give a detailed characterization of point spectrum and its asymptotic behavior with respect to the parameters entering the Hamiltonian. We also partially describe the positive spectrum and scattering properties of the Hamiltonian.

  4. Wideband range-Doppler processing and beamforming using electro-optic arrays and spectral hole burning materials.

    Braker, Benjamin; Wagner, Kelvin

    2010-07-01

    Ubiquitous radar systems look everywhere at all times and require both parallel radar processors and parallel beamformers. Current systems operate with subgigahertz bandwidths and produce a handful of angle-of-arrival (AOA) beams. We present an electro-optic radar processor that combines the multigigahertz wideband capabilities of a spectral hole burning correlator with wideband Doppler processing and the thousands of parallel channels available from an electro-optical beamformer. Preliminary experiments demonstrate 150 MHz bandwidth range correlations across 20 AOA beams. PMID:20648114

  5. Picosecond optically reconfigurable filters exploiting full free spectral range tuning of single ring and Vernier effect resonators.

    Bruck, Roman; Mills, Ben; Thomson, David J; Troia, Benedetto; Passaro, Vittorio M N; Mashanovich, Goran Z; Reed, Graham T; Muskens, Otto L

    2015-05-01

    We demonstrate that phase shifts larger than 2π can be induced by all-optical tuning in silicon waveguides of a few micrometers in length. By generating high concentrations of free carriers in the silicon employing absorption of ultrashort, ultraviolet laser pulses, the refractive index of silicon can be drastically reduced. As a result, the resonance wavelength of optical resonators can be freely tuned over the full free spectral range. This allows for active integrated optic devices that can be switched with GHz frequencies into any desired state by all-optical means. PMID:25969332

  6. Integrated chip-scale Si3N4 wavemeter with narrow free spectral range and high stability.

    Xiang, Chao; Tran, Minh A; Komljenovic, Tin; Hulme, Jared; Davenport, Michael; Baney, Doug; Szafraniec, Bogdan; Bowers, John E

    2016-07-15

    We designed, fabricated, and characterized an integrated chip-scale wavemeter based on an unbalanced Mach-Zehnder interferometer with 300 MHz free spectral range. The wavemeter is realized in the Si3N4 platform, allowing for low loss with ∼62  cm of on-chip delay. We also integrated an optical hybrid to provide phase information. The main benefit of a fully integrated wavemeter, beside its small dimensions, is increased robustness to vibrations and temperature variations and much improved stability over fiber-based solutions. PMID:27420522

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

    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.

  8. Morfology of SEE spectral features in a wide pump wave frequency range

    Sergeev, E. N.; Frolov, V. L.; Grach, S. M.; Kotov, P. V.

    Systematic study of stimulated electromagnetic emission (SEE) stationary spectrum dependence on the pump wave (PW) frequency f_0 was continued. Investigations were performed at the SURA facility for the PW frequency range 4.3≤ f_0 ≤ 9.5 MHz with stepping of ≈ 5-50 kHz including the vicinities of the electron gyroharmonics nfce from n=4 to n=7 for most prominent SEE features like downshifted maximum (DM) and its satellites, narrow and broad continua (NC and BC), upshifted maximum (UM), broad upshifted maximum (BUM), and broad upshifted structure (BUS) (for references see, e.g., Leyser et al., J. Geophys. Res., 1993, v. 98, p. 17597, 1994, Frolov et al., Geophys. Res. Lett., 2001, v. 28, p. 3103). Main attention was paid to maximal and integral intensities of the SEE features and their frequency shifts Δ f from f_0. The results can be summarized as follows. (i) While the SEE qualitative behaviour periodically repeats between successive gyroharmonics, maximal intensity for all of the SEE features is observed for 4fce5fce (except of narrow range below 6 and 7fce) the BC is replaced by a set of DM satellites in the SEE spectrum. (iii) DM intensity decreases with f_0 and DM peak frequency shift increases with f_0 as Δ fDM ˜ 2 f_0\\cdot10-3 across the whole f_0 frequency range, except of narrow ranges near f_0 ≃ nfce, where the DM intensity falls up to the noise level, and Δ fDM decreases up to ≈ 9 kHz. (iv) The UM behaviour is similar for the DM one, but for f_0≃ nfce the maximal UM and minimal DM intensities occur for the same f_0, while the minimal UM is observed for f_0 less by 10-20 kHz in comparison with f_0 for the minimal DM. (v) Maximal BUM intensity is observed for f_0 just above nfce where the frequency shift of BUM peak Δ fBUM ≃ 20 kHz; for f_0 ≳ nfce+30 kHz Δ fBUM linearly increases as Δ fBUM ≃ f_0 - nfce. (vi) The BUS is observed for f_0 well above nfce (n=3-5) in the PW frequency range nfce+150 kHz ≲ f_0 ≲ (n+1/2)fce. BUS

  9. Visibility studies and orbit determination of space debris objects for a combined passive-optical and laser ranging station

    Radtke, Jonas

    2012-01-01

    At the Institute of Technical Physics at the German Aerospace Center (DLR-TP), a proposed concept combines two methods of well established orbital observations: First, optical observations using passive reflection of sunlight, which is in constant use for characterizing space debris in GEO regions. Second, an active satellite range laser ranging, which has been used for decades to measure distances to cooperative LEO and MEO objects at accuracies down to few millimeters. In ...

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

    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.

  11. Space-time Resolved Spectroscopic System Based on a Rotating Hexahedral Mirror for Measurement of Visible and Ultraviolet Spectral Line Emissions

    Wu Zhenwei; Wan Baonian; Zhou Qian; Huang Juan

    2005-01-01

    By using a rotating hexahedral mirror placed in front of the objective lens and two sets of visible and ultraviolet monochromators coupled with a branchy quartz fiber bundle, a spacetime resolved spectroscopic system has been developed on the HT-7 superconducting tokamak. A center monitoring system has been used including a Helium-Neon laser and a photodiode detector to indicate the absolute position of the measurement in order to reduce the error caused by the uncertain emissive position of the plasma. By using the asymmetric Abel inversion, the spacetime resolved local emission coefficients of the spectroscopic line emissions have been obtained.Presented in this article are simultaneous measurements of two spectral line emissions such as CV ~ 227.1 nm and OV ~ 278.1 nm during a single plasma discharge on the HT-7. Experimental results indicate that the time resolution is better than 3 ms, the space resolution is better than 1.5 cm, the ratio of signal to background is better than 10:1, and the relative error of chord-integrated emission profile is less than 10%. Compared to traditional multichannel detecting systems, this system has considerably improved measurement efficiency, reduced uncertainty, and is therefore suitable for transport studies of global particles and impurities.

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

    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

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

    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.

  14. Laser optogalvanic spectroscopy of lanthanum in spectral range of Rhodamine 6G

    Full text: Hyperfine structure studies of some of the allowed transitions of La I has been carried out by high resolution Doppler limited laser optogalvanic spectroscopy. A narrow bandwidth (500 KHz) autoscan ring dye laser (899-29) pumped by argon ion laser model Innova series 200 (coherent Corp) has been employed to investigate the hyperfine structure in the wavelength range 5600-6200 AA of Rhodamine 6G in connection with a commercially available hollow cathode. Sixteen transitions of La I have been observed involving twenty five levels, twelve with odd and thirteen with even parity. A comparison with the previous data available in the literature has also been made. The recorded spectra were analyzed using Casimir's formula which yields the expression for the shift of a hyperfine component from the center of the gravity. Then we formulate four simultaneous equations for the four unknown quantities A, B, A' and B' according to the expression. i.e; Δν12 = A(K1-K2)/2 + (3B/8) x [K1(K1+1)-K2(K2+1)]/[(IJ(2I-1)(2J-1)] + A'(K1'-K2')/2 + (3B'/8) x [K1'(K'+1)-K2'(K2'+1)]/[IJ'(2I-1)(2J'-1)]. A computer program based on Gauss elimination technique is then employed to determine the hyperfine structure constants i.e. A, B, A' and B' for lower and upper energy levels. The curve obtained through the utilization of these empirically evaluated hyperfine structure constants is then matched with the experimental data through another computer program for the best-fit values. Here we present the analyzed data of only few transitions. Experimentally obtained hyperfine structure constants (in MHz) of these transitions along with the transition wavelengths are shown in a table. (author)

  15. Spectral EMG changes in vastus medialis muscle following short range of motion isokinetic training.

    Barak, Yaron; Ayalon, Moshe; Dvir, Zeevi

    2006-10-01

    This study was aimed at exploring the carryover effect of short range of motion (RoM) isokinetic conditioning on vastus medialis (VM) motor unit recruitment (MUR) across the full RoM. Fifty-five women were randomly assigned to one of four groups: G1 (n = 14) and G2 (n = 14) trained concentrically at 30 and 90 degrees /s, respectively whereas G3 (n = 13) and G4 (n = 14) trained similarly but using the eccentric mode. All 4 groups trained within 30-60 degrees of knee flexion. The training protocol consisted of 4 sets of 10 maximal repetitions, 3 times a week for 6 weeks. sEMG was recorded from the VM for analysis of mean frequency of the EMG power spectrum prior to the training period and 2 days after its termination. The EMG assessments took place during dynamic contractions within 3 angular RoM's: 85-60 degrees (R1), 60-30 degrees (R2) and 30-5 degrees (R3). In addition MUR was evaluated during isometric contractions at 10 degrees , 45 degrees and 80 degrees . Significant increases were observed in the MUR at R1, R2, and R3 during dynamic contractions as well as in all 3 angles during isometric contractions. These findings applied equally regardless of the mode of contraction and motion speed during training. The fact that MUR increased significantly within untrained RoM's may point out to the potential benefits of short RoM conditioning, particularly in those cases where, during specific phases of rehabilitation, a wider RoM may be contraindicative. PMID:16324851

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

    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−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 10−4 cm−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 μrad 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

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

    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.

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

    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.

  19. Design concepts of monolithic metamorphic vertical-cavity surface-emitting lasers for the 1300–1550 nm spectral range

    Possible design concepts for long-wavelength vertical-cavity surface-emitting lasers for the 1300–1550 nm spectral range on GaAs substrates are suggested. It is shown that a metamorphic GaAs–InGaAs heterostructure with a thin buffer layer providing rapid transition from the lattice constant of GaAs to that of InxGa1–xAs with an indium fraction of x < 0.3 can be formed by molecular-beam epitaxy. Analysis by transmission electron microscopy demonstrated the effective localization of mismatch dislocations in the thin buffer layer and full suppression of their penetration into the overlying InGaAs metamorphic layer

  20. Effects of external intermittency and mean shear on the spectral inertial-range exponent in a turbulent square jet

    Zhang, J.; Xu, M.; Pollard, A.; Mi, J.

    2013-05-01

    This study investigates by experiment the dependence of the inertial-range exponent m of the streamwise velocity spectrum on the external intermittency factor γ (≡ the fraction of time the flow is fully turbulent) and the mean shear S in a turbulent square jet. Velocity measurements were made using hot-wire anemometry in the jet at 15 Zoran Zariç Memorial Conference, edited by S. J. Kline and N. H. Afgan (Hemisphere Publishing Corp., Washington, DC, 1990), pp. 911-931] is discussed and applied to estimate the intermittency factor from velocity signals. It is shown that m depends strongly on γ but negligibly on S. More specifically, m varies with γ following m=mt+(lnγ-0.0173)1/2, where mt denotes the spectral exponent found in fully turbulent regions.

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

    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{\

  2. Design optimization of superlattice type-II IR-detection modules with temporal signal coincidence in two spectral ranges

    Breiter, R.; Lutz, H.; Scheibner, R.; Wendler, J.; Hofmann, K.; Ziegler, J.; Walther, M.; Rehm, R.

    2008-04-01

    3rd Generation IR detectors providing e.g. dual-color capability are of great benefit for applications like aircraft missile approach warning systems using this feature for achieving low false alarm rates by separating the hot CO2 missile plume from background and clutter. AIM and IAF selected antimonide based type II Superlattices (SL) for such kind of applications. The type II SL technology provides an accurate engineering of sensitive layers by MBE with very good homogeneity and yield. IAF and AIM already managed to realize a dual-color 384x288 IR-Module based on this technology. It combines spectral selective detection in the 3-4 μm wavelength range and 4-5 μm wavelength range in each pixel with coincident integration in a 384x288x2 format and 40 μm pitch. Excellent thermal resolution with NETD crosstalk between the two colors the layer thickness of the SL-layer was optimized. This paper is intended to present the current status and trends at AIM on antimonide type II Superlattices (SL) IR module developments for ground and airborne applications in the high performance range, where rapidly changing scenes - like e.g. in case of missile warning applications for airborne platforms - require temporal signal coincidence with integration times of typically 1ms.

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

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

    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.

    2013-03-01

    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 XeF2 - N2 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 108. 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 1012 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.

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

    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.

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

    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/δE⟩ ˜ 50. It has been used at the LULI-2000 laser facility at École Polytechnique (France) to measure the Δn = 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.

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

    Reverdin, Charles; Caillaud, T.; Gilleron, F.; Pain, J. C.; Silvert, V.; Soullie, G.; Villette, B. [CEA, DAM, DIF, 91297 Arpajon (France); Thais, Frederic; Loisel, Guillaume; Blenski, T.; Poirier, M. [CEA, DSM, IRAMIS, Service Photons, Atomes et Molecules, 91191 Gif-sur-Yvette (France); Busquet, M. [ARTEP Inc, Ellicott City, Maryland 21042 (United States); Bastiani-Ceccotti, S.; Serres, F. [LULI, Ecole Polytechnique, CNRS, CEA, UPMC, route de Saclay, 91128 Palaiseau (France); Ducret, J. E. [CELIA, UMR5107, CEA, CNRS, Universite de Bordeaux, 33400 Talence (France); Foelsner, W. [Max Planck Instituet fuer Quantum Optik, 85748 Garching (Germany); Gilles, D.; Turck-Chieze, S. [CEA, DSM, IRFU, Service d' astrophysique, 91191 Gif-sur-Yvette (France)

    2012-10-15

    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 {approx} 50. It has been used at the LULI-2000 laser facility at Ecole Polytechnique (France) to measure the {Delta}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.

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

    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 ∼ 50. It has been used at the LULI-2000 laser facility at École Polytechnique (France) to measure the Δn = 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. PMID:23126955

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

    Draeger, Daniel; Rossow, Uwe; Joenen, Holger; Hangleiter, Andreas [Institute of Applied Physics, Technical University of Braunschweig (Germany); Schenk, David; Duboz, Jean-Yves [CRHEA-CNRS, Valbonne (France)

    2008-07-01

    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/cm{sup 2}. Up to now we obtain optical gain up to a peak wavelength of 465 nm with losses of about 30 cm{sup -1}. Our next targets are a wavelength of 480 nm as well as a further reduction of the threshold power.

  10. A high resolution, multi-epoch spectral atlas of peculiar stars including RAVE, GAIA and HERMES wavelength ranges

    Tomasella, L; Zwitter, T

    2010-01-01

    We present an Echelle+CCD, high S/N, 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 Ang, and includes the RAVE, Gaia and HERMES wavelength ranges. Multi-epoch spectra are provided for the majority of observed stars. A total of 425 spectra of peculiar stars are presented, which have been collected during 56 observing nights between November 1998 and August 2002. 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, spectro-photometric 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 the planning for and training...

  11. Multiple fiber Bragg grating sensor network with a rapid response and wide spectral dynamic range using code division multiple access

    Kim, Youngbok; Jeon, Sie-Wook; Park, Chang-Soo

    2011-05-01

    Fiber Bragg grating (FBG) sensor networks have been intensively researched in optical sensor area and it developed in wavelength division multiplexing (WDM) and time division multiplexing (TDM) technologies which was adopted for its interrogating many optical sensors. In particular, WDM technology can be easily employed to interrogate FBG sensor however, the number of FBG sensors is limited. On the other hand, the TDM technique can extremely expand the number of sensor because the FBG sensors have same center wavelength. However, it suffers from a reduced sensor output power due to low reflectivity of FBG sensor. In this paper, we proposed and demonstrated the FBG sensor network based on code division multiple access (CDMA) with a rapid response and wide spectral dynamic range. The reflected semiconductor optical amplifier (RSOA) as a light source was directly modulated by the generated pseudorandom binary sequence (PRBS) code and the modulated signal is amplified and goes through FBG sensors via circulator. When the modulated optical signal experienced FBG sensor array, the optical signal which was consistent with center wavelength of FBGs is reflected and added from each sensors. The added signal goes into dispersion compensating fiber (DCF) as a dispersion medium. After through the DCF, the optical signal is converted into electrical signal by using photodetector (PD). For separate individual reflected sensor signal, the sliding correlation method was used. The proposed method improves the code interference and it also has advantages such as a large number of sensors, continuously measuring individual sensors, and decreasing the complexity of the sensor network.

  12. A climatology of visible surface reflectance spectra

    Zoogman, Peter; Liu, Xiong; Chance, Kelly; Sun, Qingsong; Schaaf, Crystal; Mahr, Tobias; Wagner, Thomas

    2016-09-01

    We present a high spectral resolution climatology of visible surface reflectance as a function of wavelength for use in satellite measurements of ozone and other atmospheric species. The Tropospheric Emissions: Monitoring of Pollution (TEMPO) instrument is planned to measure backscattered solar radiation in the 290-740 nm range, including the ultraviolet and visible Chappuis ozone bands. Observation in the weak Chappuis band takes advantage of the relative transparency of the atmosphere in the visible to achieve sensitivity to near-surface ozone. However, due to the weakness of the ozone absorption features this measurement is more sensitive to errors in visible surface reflectance, which is highly variable. We utilize reflectance measurements of individual plant, man-made, and other surface types to calculate the primary modes of variability of visible surface reflectance at a high spectral resolution, comparable to that of TEMPO (0.6 nm). Using the Moderate-resolution Imaging Spectroradiometer (MODIS) Bidirection Reflectance Distribution Function (BRDF)/albedo product and our derived primary modes we construct a high spatial resolution climatology of wavelength-dependent surface reflectance over all viewing scenes and geometries. The Global Ozone Monitoring Experiment-2 (GOME-2) Lambertian Equivalent Reflectance (LER) product provides complementary information over water and snow scenes. Preliminary results using this approach in multispectral ultraviolet+visible ozone retrievals from the GOME-2 instrument show significant improvement to the fitting residuals over vegetated scenes.

  13. ZnO/a-Si distributed Bragg reflectors for light trapping in thin film solar cells from visible to infrared range

    Chen, Aqing; Yuan, Qianmin; Zhu, Kaigui

    2016-01-01

    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 400-1000 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.

  14. 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

    M. Rajeswara Rao; Angel, Michael F.; Das, Suman K.; Margot S. Koelle; Don Obenhuber; Reno, William L.; 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...

  15. A single-shot nonlinear autocorrelation approach for time-resolved physics in the vacuum ultraviolet spectral range

    In this work, a single-shot temporal metrology scheme operating in the vacuum-extreme ultraviolet spectral range has been designed and experimentally implemented. Utilizing an anti-collinear geometry, a second-order intensity autocorrelation measurement of a vacuum ultraviolet pulse can be performed by encoding temporal delay information on the beam propagation coordinate. An ion-imaging time-of-flight spectrometer, offering micrometer resolution has been set-up for this purpose. This instrument enables the detection of a magnified image of the spatial distribution of ions exclusively generated by direct two-photon absorption in the combined counter-propagating pulse focus and thus obtain the second-order intensity autocorrelation measurement on a single-shot basis. Additionally, an intense VUV light source based on high-harmonic generation has been experimentally realized. It delivers intense sub-20 fs Ti:Sa fifth-harmonic pulses utilizing a loose-focusing geometry in a long Ar gas cell. The VUV pulses centered at 161.8 nm reach pulse energies of 1.1 μJ per pulse, while the corresponding pulse duration is measured with a second-order, fringe-resolved autocorrelation scheme to be 18 ± 1 fs on average. Non-resonant, two-photon ionization of Kr and Xe and three-photon ionization of Ne verify the fifth-harmonic pulse intensity and indicate the feasibility of multi-photon VUV pump/VUV probe studies of ultrafast atomic and molecular dynamics. Finally, the extended functionally of the counter-propagating pulse metrology approach is demonstrated by a single-shot VUV pump/VUV probe experiment aiming at the investigation of ultrafast dissociation dynamics of O2 excited in the Schumann-Runge continuum at 162 nm.

  16. A single-shot nonlinear autocorrelation approach for time-resolved physics in the vacuum ultraviolet spectral range

    Rompotis, Dimitrios

    2016-02-15

    In this work, a single-shot temporal metrology scheme operating in the vacuum-extreme ultraviolet spectral range has been designed and experimentally implemented. Utilizing an anti-collinear geometry, a second-order intensity autocorrelation measurement of a vacuum ultraviolet pulse can be performed by encoding temporal delay information on the beam propagation coordinate. An ion-imaging time-of-flight spectrometer, offering micrometer resolution has been set-up for this purpose. This instrument enables the detection of a magnified image of the spatial distribution of ions exclusively generated by direct two-photon absorption in the combined counter-propagating pulse focus and thus obtain the second-order intensity autocorrelation measurement on a single-shot basis. Additionally, an intense VUV light source based on high-harmonic generation has been experimentally realized. It delivers intense sub-20 fs Ti:Sa fifth-harmonic pulses utilizing a loose-focusing geometry in a long Ar gas cell. The VUV pulses centered at 161.8 nm reach pulse energies of 1.1 μJ per pulse, while the corresponding pulse duration is measured with a second-order, fringe-resolved autocorrelation scheme to be 18 ± 1 fs on average. Non-resonant, two-photon ionization of Kr and Xe and three-photon ionization of Ne verify the fifth-harmonic pulse intensity and indicate the feasibility of multi-photon VUV pump/VUV probe studies of ultrafast atomic and molecular dynamics. Finally, the extended functionally of the counter-propagating pulse metrology approach is demonstrated by a single-shot VUV pump/VUV probe experiment aiming at the investigation of ultrafast dissociation dynamics of O{sub 2} excited in the Schumann-Runge continuum at 162 nm.

  17. Spectral Imaging by Upconversion

    Dam, Jeppe Seidelin; Pedersen, Christian; Tidemand-Lichtenberg, Peter

    We present a method to obtain spectrally resolved images using upconversion. By this method an image is spectrally shifted from one spectral region to another wavelength. Since the process is spectrally sensitive it allows for a tailored spectral response. We believe this will allow standard...... silicon based cameras designed for visible/near infrared radiation to be used for spectral images in the mid infrared. This can lead to much lower costs for such imaging devices, and a better performance....

  18. The non-contact detection and identification of blood stained fingerprints using visible wavelength hyperspectral imaging: Part II effectiveness on a range of substrates.

    Cadd, Samuel; Li, Bo; Beveridge, Peter; O'Hare, William T; Campbell, Andrew; Islam, Meez

    2016-05-01

    Biological samples, such as blood, are regularly encountered at violent crime scenes and successful identification is critical for criminal investigations. Blood is one of the most commonly encountered fingerprint contaminants and current identification methods involve presumptive tests or wet chemical enhancement. These are destructive however; can affect subsequent DNA sampling; and do not confirm the presence of blood, meaning they are susceptible to false positives. A novel application of visible wavelength reflectance hyperspectral imaging (HSI) has been used for the non-contact, non-destructive detection and identification of blood stained fingerprints across a range of coloured substrates of varying porosities. The identification of blood was based on the Soret γ band absorption of haemoglobin between 400nm and 500nm. Ridge detail was successfully visualised to the third depletion across light coloured substrates and the stain detected to the tenth depletion on both porous and non-porous substrates. A higher resolution setup for blood stained fingerprints on black tiles, detected ridge detail to the third depletion and the stain to the tenth depletion, demonstrating considerable advancements from previous work. Diluted blood stains at 1500 and 1000 fold dilutions for wet and dry stains respectively were also detected on pig skin as a replica for human skin. PMID:27162017

  19. Visible and infrared linear detector arrays for the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS)

    The Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) instrument uses four separate focal plane assemblies consisting of line array detectors that are multiplexed to a common J-FET preamp using a FET switch multiplexing (MUX) technique. A 32-element silicon line array covers the spectral range from 0.41 to 0.70 microns. Three additional 64-element indium antimonide (InSb) line arrays cover the spectral range from 0.68 to 2.45 microns. The spectral sampling interval per detector element is nominally 9.8 nm, giving a total of 224 spectral channels. All focal planes operate at liquid nitrogen temperature and are housed in separate dewars. Electrical performance characteristics include a read noise of less than 1000 e(-) in all channels, response and dark nonuniformity of 5 percent peak to peak, and quantum efficiency of greater than 60 percent

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

    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)

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

    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.

  2. X-ray crystal spectrometer for opacity measurements in the 8-18 A spectral range at the LULI laser facility

    An x-ray crystal spectrometer was built in order to measure opacities in the 8-18 A spectral range with an average spectral resolution of ∼400. It has been successfully used at the LULI-2000 laser facility (See C. Sauteret, rapport LULI 2001, 88 (2002) at Ecole Polytechnique (France) to measure in the same experimental conditions the 2p-3d transitions of several elements with the neighboring atomic number Z: Fe, Ni, Cu, and Ge [G. Loisel et al., High Energy Density Phys. 5, 173 (2009)]. Hence, a spectrometer with a wide spectral range is needed. This spectrometer features two lines of sight. In this example, one line of sight looks through the sample and the other one is looking directly at the backlighter emission. Both are outfitted with a spherical condensing mirror. A TlAP crystal is used for spectral dispersion. Detection is made with an image plate Fuji BAS TR2025, which is sensitive to x rays. We present some experimental results showing the performances of this spectrometer.

  3. X-ray crystal spectrometer for opacity measurements in the 8-18 Å spectral range at the LULI laser facility.

    Reverdin, C; Thais, F; Loisel, G; Bougeard, M

    2010-10-01

    An x-ray crystal spectrometer was built in order to measure opacities in the 8-18 Å spectral range with an average spectral resolution of ∼ 400. It has been successfully used at the LULI-2000 laser facility (See C. Sauteret, rapport LULI 2001, 88 (2002) at École Polytechnique (France) to measure in the same experimental conditions the 2p-3d transitions of several elements with the neighboring atomic number Z: Fe, Ni, Cu, and Ge [G. Loisel et al., High Energy Density Phys. 5, 173 (2009)]. Hence, a spectrometer with a wide spectral range is needed. This spectrometer features two lines of sight. In this example, one line of sight looks through the sample and the other one is looking directly at the backlighter emission. Both are outfitted with a spherical condensing mirror. A TlAP crystal is used for spectral dispersion. Detection is made with an image plate Fuji BAS TR2025, which is sensitive to x rays. We present some experimental results showing the performances of this spectrometer. PMID:21034025

  4. X-ray crystal spectrometer for opacity measurements in the 8-18 Å spectral range at the LULI laser facilitya)

    Reverdin, C.; Thais, F.; Loisel, G.; Bougeard, M.

    2010-10-01

    An x-ray crystal spectrometer was built in order to measure opacities in the 8-18 Å spectral range with an average spectral resolution of ⟨λ /δλ⟩˜400. It has been successfully used at the LULI-2000 laser facility (See C. Sauteret, rapport LULI 2001, 88 (2002) at École Polytechnique (France) to measure in the same experimental conditions the 2p-3d transitions of several elements with the neighboring atomic number Z: Fe, Ni, Cu, and Ge [G. Loisel et al., High Energy Density Phys. 5, 173 (2009)]. Hence, a spectrometer with a wide spectral range is needed. This spectrometer features two lines of sight. In this example, one line of sight looks through the sample and the other one is looking directly at the backlighter emission. Both are outfitted with a spherical condensing mirror. A TlAP crystal is used for spectral dispersion. Detection is made with an image plate Fuji BAS TR2025, which is sensitive to x rays. We present some experimental results showing the performances of this spectrometer.

  5. Viewer Makes Radioactivity "Visible"

    Yin, L. I.

    1983-01-01

    Battery operated viewer demonstrates feasibility of generating threedimensional visible light simulations of objects that emit X-ray or gamma rays. Ray paths are traced for two pinhold positions to show location of reconstructed image. Images formed by pinholes are converted to intensified visible-light images. Applications range from radioactivity contamination surveys to monitoring radioisotope absorption in tumors.

  6. Examining the possibility of correcting imagery acquired for the purpose of obtaining spectral reflectance coefficients in the infrared range using photometric measurements

    A. Orych; P. Walczykowski; M. Kedzierski; A. Fryskowska

    2014-01-01

    The purpose of this paper is to determine the possibility of using photometric measurements in order to correct imagery acquired in the 900–1700 nm range. This imagery is acquired for the purpose of acquiring spectral reflectance coefficients in variable lighting conditions. This paper will present a series of experiments, the problems encountered and obtained results. The main aim of this research was to determine a link between these two quantities (luminance and irradiance) ...

  7. Spectral ellipsometry study in the range of electronic excitations and band structure of [(CH3)2CHNH3]4Cd3Cl10 crystals

    Optical dielectric functions ε(E) of the (IPA)4Cd3Cl10 crystal were measured in the spectral range of fundamental electronic excitations 3.5–10 eV and in the temperature range of 310–400 K containing the phase transition point between the orthorhombic phases Cmce and Pbca. Measurements were performed by spectroscopic ellipsometry with using of synchrotron radiation. Electronic band structure, density of states and dielectric functions ε(E) of (IPA)4Cd3Cl10 were calculated and analyzed on the basis of the density functional theory. Top valence and bottom conduction bands were found to be formed mainly by the cadmium–chlorine complexes of the crystals. - Highlights: ► Spectral ellipsometry in the VUV range is used for study of (IPA)4Cd3Cl10 crystals. ► Band structure of (IPA)4Cd3Cl10 crystal has been calculated for the first time. ► Origin of the lowest energy spectral band of dielectric function is determined. ► Width of temperature dependency of dielectric permittivity is large (near 50 K). ► Maximum of temperature dependency of dielectric permittivity is small (near 2%)

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

    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...

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

    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.

  10. Super dual auroral radar network observations of fluctuations in the spectral distribution of near range meteor echoes in the upper mesosphere and lower thermosphere

    Arnold, N.F.; Robinson, T.R.; Lester, M.; Byrne, P.B.; Chapman, P.J. [Dept. of Physics and Astronomy, Univ. of Leicester (United Kingdom)

    2001-04-01

    The Doppler shifts of meteor echoes measured by the SuperDARN HF radar network have been used in several studies to observe neutral winds in the upper mesosphere and lower thermosphere region. In the absence of accurate height information for individual meteors, it has been necessary to assume a statistical mean meteor layer where the variations in altitude were not correlated to changes in the horizontal winds. Observations of spectral width distribution variations made by the radars allow an independent determination of the systematic error in the height. We have investigated the dependence of this distribution on a number of factors including the radar geometry, diurnal and seasonal cycles, variations in solar UV irradiance and geomagnetic activity. Changes in the altitude of the mean meteor layer observed at different radar ranges provide us with some insight into the structure of the upper mesosphere and the lower thermosphere within which the meteors are being ablated. An examination of the spectral widths, as measured by the CUTLASS Finland radar, in the days preceding and following a Storm Sudden Commencement in April 1997, illustrates how the spectral properties of the observed region can be affected. The variations in the widths were consistent with model calculations of the changes to the temperature profile over this interval. Further refinements in the determination of the spectral width are outlined for future experiments. (orig.)

  11. Super Dual Auroral Radar Network observations of fluctuations in the spectral distribution of near range meteor echoes in the upper mesosphere and lower thermosphere

    N. F. Arnold

    Full Text Available The Doppler shifts of meteor echoes measured by the SuperDARN HF radar network have been used in several studies to observe neutral winds in the upper mesosphere and lower thermosphere region. In the absence of accurate height information for individual meteors, it has been necessary to assume a statistical mean meteor layer where the variations in altitude were not correlated to changes in the horizontal winds. Observations of spectral width distribution variations made by the radars allow an independent determination of the systematic error in the height. We have investigated the dependence of this distribution on a number of factors including the radar geometry, diurnal and seasonal cycles, variations in solar UV irradiance and geomagnetic activity. Changes in the altitude of the mean meteor layer observed at different radar ranges provide us with some insight into the structure of the upper mesosphere and the lower thermosphere within which the meteors are being ablated. An examination of the spectral widths, as measured by the CUT-LASS Finland radar, in the days preceding and following a Storm Sudden Commencement in April 1997, illustrates how the spectral properties of the observed region can be affected. The variations in the widths were consistent with model calculations of the changes to the temperature profile over this interval. Further refinements in the determination of the spectral width are outlined for future experiments.

    Key words. Meterology and atmospheric dynamics (middle atmosphere dynamics; thermospheric dynamics; instruments and techniques

  12. Lasing of multiperiod quantum-cascade lasers in the spectral range of (5.6–5.8)-μm under current pumping

    Egorov, A. Yu., E-mail: anton@beam.ioffe.ru; Babichev, A. V.; Karachinsky, L. Ya.; Novikov, I. I. [Ioffe Institute (Russian Federation); Nikitina, E. V. [St. Petersburg Academic University (Russian Federation); Tchernycheva, M. [University Paris Sud XI, Institut d’Electronique Fondamentale (France); Sofronov, A. N.; Firsov, D. A.; Vorobjev, L. E. [Peter the Great St. Petersburg Polytechnic University (Russian Federation); Pikhtin, N. A.; Tarasov, I. S. [Ioffe Institute (Russian Federation)

    2015-11-15

    The lasing of multiperiod quantum-cascade lasers in the spectral range of (5.6–5.8)-μm under current pumping are demonstrated. The quantum-cascade laser heterostructure is grown by molecular-beam epitaxy technique. Despite the relatively short laser cavity length and high level of external loss the laser shows the lasing in the temperature range of 80–220 K. The threshold current density below 4 kA/cm{sup 2} at 220 K with the characteristic temperature T{sub 0} = 123 K was demonstrated.

  13. Lasing of multiperiod quantum-cascade lasers in the spectral range of (5.6–5.8)-μm under current pumping

    The lasing of multiperiod quantum-cascade lasers in the spectral range of (5.6–5.8)-μm under current pumping are demonstrated. The quantum-cascade laser heterostructure is grown by molecular-beam epitaxy technique. Despite the relatively short laser cavity length and high level of external loss the laser shows the lasing in the temperature range of 80–220 K. The threshold current density below 4 kA/cm2 at 220 K with the characteristic temperature T0 = 123 K was demonstrated

  14. Modifying ultrafast optical response of sputtered VOX nanostructures in a broad spectral range by altering post annealing atmosphere

    Kürüm, U.; Yaglioglu, H. G.; Küçüköz, B.; Oksuzoglu, R. M.; Yıldırım, M.; Yağcı, A. M.; Yavru, C.; Özgün, S.; Tıraş, T.; Elmali, A.

    2015-01-01

    Nanostructured VOX thin films were grown in a dc magnetron sputter system under two different Ar:O2 gas flow ratios. The films were annealed under vacuum and various ratios of O2/N2 atmospheres. The insulator-to-metal transition properties of the thin films were investigated by temperature dependent resistance measurement. Photo induced insulator-to-metal transition properties were investigated by Z-scan and ultrafast white light continuum pump probe spectroscopy measurements. Experiments showed that not only insulator-to-metal transition, but also wavelength dependence (from NIR to VIS) and time scale (from ns to ultrafast) of nonlinear optical response of the VOX thin films could be fine tuned by carefully adjusting post annealing atmosphere despite different initial oxygen content in the production. Fabricated VO2 thin films showed reflection change in the visible region due to photo induced phase transition. The results have general implications for easy and more effective fabrication of the nanostructured oxide systems with controllable electrical, optical, and ultrafast optical responses.

  15. Visibles Revisited

    Bridger, Mark; Zelevinsky, Andrei

    2005-01-01

    Within the set of points in the plane with integer coordinates, one point is said to be visible from another if no other point in the set lies between them. This study of visibility draws in topics from a wide variety of mathematical areas, including geometry, number theory, probability, and combinatorics.

  16. 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

    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

  17. Spectral reflectance from plant canopies and optimum spectral channels in the near infrared

    Allen, W. A.; Gausman, H. W.; Wiegand, C. L.

    1970-01-01

    Theoretical and experimental aspects of the interaction of light with a typical plant canopy are considered. Both theoretical and experimental results are used to establish optimum electromagnetic wavelength channels for remote sensing in agriculture. The spectral range considered includes half of the visible and much of the near-infrared regions.

  18. Narrow-band near-field nanoscopy in the spectral range from 1.3 to 8.5 THz

    Kuschewski, F.; von Ribbeck, H.-G.; Döring, J.; Winnerl, S.; Eng, L. M.; Kehr, S. C.

    2016-03-01

    Nano-spectroscopy in the terahertz frequency range remains challenging despite recent technological progress in developing both THz emitter sources and near-field optical microscopy (SNOM). Here, we combine scattering-type SNOM with a free-electron laser light source, to tune into the 1.3-8.5 THz range. A significant portion of this range, namely, the frequencies above ˜3 THz, is not covered by previously reported near-field microscopy systems. However, it constitutes an indispensable regime where many elementary processes in solids including collective lattice excitations, charge, and spin transport occur. Our approach of nano-spectroscopy and nano-imaging provides a versatile analysis of nanostructures as small as 50 nm, hence beating the optical diffraction limit by λ/4600.

  19. Full anterior segment biometry with extended imaging range spectral domain optical coherence tomography at 1340 nm

    Li, Peng; Johnstone, Murray; Ruikang K Wang

    2014-01-01

    Abstract. We demonstrate an extended-imaging-range anterior-segment optical coherence tomography (eAS-OCT) system for the biometric assessment of full AS in human eye. This newly developed eAS-OCT operating at 1340-nm wavelength band is simultaneously capable of an imaging speed of 120 kHz A-line scan rate, an axial resolution of 7.2 μm, and an extended imaging range of up to 16 mm in air. Imaging results from three healthy subjects and one subject with a narrow-angle demonstrate the instrume...

  20. Improved EDGE2D-EIRENE simulations of JET ITER-like wall L-mode discharges utilising poloidal VUV/visible spectral emission profiles

    Lawson, K.D., E-mail: Kerry.Lawson@ccfe.ac.uk [CCFE, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Groth, M. [Aalto University, Association EURATOM-Tekes, Espoo (Finland); Belo, P. [CCFE, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Brezinsek, S. [Forschungszentrum Jülich, IEK-4 Plasmaphysik, Jülich (Germany); Corrigan, G. [CCFE, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Czarnecka, A. [Institute of Plasma Physics and Laser Microfusion, Association EURATOM-IPPLM, Warsaw (Poland); Delabie, E. [FOM Institute DIFFER, Nieuwegein (Netherlands); Drewelow, P. [MPI für Plasmaphysik, EURATOM Association, Greifswald (Germany); Harting, D. [Forschungszentrum Jülich, IEK-4 Plasmaphysik, Jülich (Germany); Książek, I. [Institute of Physics, Opole University, ul.Oleska 48, 45-052 Opole (Poland); Maggi, C.F. [MPI für Plasmaphysik, EURATOM Association, D-85748 Garching (Germany); Marchetto, C. [Istituto di Fisica del Plasma, CNR, Milano (Italy); Meigs, A.G. [CCFE, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Menmuir, S. [Euratom/VR Association, KTH Royal Institute of Technology, SE-100 44 Stockholm (Sweden); Stamp, M.F. [CCFE, Culham Science Centre, Abingdon OX14 3DB (United Kingdom); Wiesen, S. [Forschungszentrum Jülich, IEK-4 Plasmaphysik, Jülich (Germany)

    2015-08-15

    A discrepancy in the divertor radiated powers between EDGE2D-EIRENE simulations, both with and without drifts, and JET-ILW experiments employing a set of NBI-heated L-mode discharges with step-wise density variation is investigated. Results from a VUV/visible poloidally scanning spectrometer are used together with bolometric measurements to determine the radiated power and its composition. The analysis shows the importance of D line radiation in contributing to the divertor radiated power, while contributions from D radiative recombination are smaller than expected. Simulations with W divertor plates underestimate the Be content in the divertor, since no allowance is made for Be previously deposited on the plates being re-eroded. An improved version of EDGE2D-EIRENE is used to test the importance of the deposited layer in which the sputtering yield from supposed pure Be divertor plates is reduced to match the spectroscopic signals, while keeping the sputtering yield for the Be main chamber walls unchanged.

  1. 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

    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)

  2. Study of the Spectral Properties of Nanocomposites with CdSe Quantum Dots in a Wide Range of Low Temperatures

    Magaryan K.A.; Eremchev I.Y.; Karimullin K.R.; Knyazev M.V.; Mikhailov M.A.; Vasilieva I.A.; Klimusheva G.V.

    2015-01-01

    Luminescence spectra of the colloidal solution of CdSe quantum dots (in toluene) were studied in a wide range of low temperatures. Samples were synthesized in the liquid crystal matrix of cadmium octanoate (CdC8). A comparative analysis of the obtained data with previous results was performed.

  3. Study of the Spectral Properties of Nanocomposites with CdSe Quantum Dots in a Wide Range of Low Temperatures

    Magaryan K.A.

    2015-01-01

    Full Text Available Luminescence spectra of the colloidal solution of CdSe quantum dots (in toluene were studied in a wide range of low temperatures. Samples were synthesized in the liquid crystal matrix of cadmium octanoate (CdC8. A comparative analysis of the obtained data with previous results was performed.

  4. Impact of cavity symmetry on mode suppression and increase of free spectral range in solid-state dye microlaser

    Sergei Popov; Sebastien Ricciardi; Ari T. Friberg; Sergey Sergeyev

    2007-01-01

    We describe modeling the solid-state dye laser with the microcavity size comparable to light wavelength.Certain symmetry in the allocation of gain material leads to depletion of odd longitudinal modes that,in turn, increases the tunability range of the microlaser. We provide simple physical explanation for the modeling results.

  5. Efficient ion blocking in gaseous detectors and its application to gas-avalanche photomultipliers sensitive in the visible-light range

    Lyashenko, A.; Breskin, A.; Chechik, R.; Santos, J. M. F. dos; Amaro, F. D.; Veloso, J. F. C. A.

    2009-01-01

    A novel concept for ion blocking in gas-avalanche detectors was developed, comprising cascaded micro-hole electron multipliers with patterned electrodes for ion defocusing. This leads to ion blocking at the 10^{-4} level, in DC mode, in operation conditions adequate for TPCs and for gaseous photomultipliers. The concept was validated in a cascaded visible-sensitive gas avalanche photomultiplier operating at atmospheric pressure of Ar/CH_{4} (95/5) with a bi-alkali photocathode. While in previ...

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

    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...

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

    The aim of this memoir is the adjustment of a (θ, 2θ) 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

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

    Bengoechea Encabo, Ana; Albert, Steven; López-Romero Moraleda, David; Lefebvre, P.; Barbagini, Francesca; Torres Pardo, Almudena; González Calbet, José María; Sánchez García, Miguel Angel; Calleja Pardo, Enrique

    2014-01-01

    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 layers (planar) of similar composition and thickness. The devices are driven under pulsed operation up ...

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

    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.

  10. Application of Optical Parametric Generator for Lidar Sensing of Minor Gas Components of the Atmosphere in 3-4 μm Spectral Range

    Romanovskii, O. A.; Sadovnikov, S. A.; Kharchenko, O. V.; Shumskii, V. K.; Yakovlev, S. V.

    2016-07-01

    Possibility of application of a laser system with parametric light generation based on a nonlinear KTA crystal for lidar sensing of the atmosphere in the 3-4 μm spectral range is investigated. A technique for lidar measurements of gas components in the atmosphere with the use of differential absorption lidar (DIAL) and differential optical absorption spectroscopy (DOAS) method is developed. The DIAL-DOAS technique is tested for estimating the possibility of laser sensing of minor gas components in the atmosphere.