WorldWideScience

Sample records for wavelength background light

  1. First-Light Galaxies or Intrahalo Stars: Multi-Wavelength Measurements of the Infrared Background Anisotropies

    Science.gov (United States)

    Cooray, Asantha

    The research program described in this proposal can be broadly described as data analysis, measurement, and interpretation of the spatial fluctuations of the unresolved cosmic IR background. We will focus primarily on the background at optical and near-IR wavelengths as probed by Hubble and Spitzer. As absolute background intensity measurements are challenging, the focus is on the spatial fluctuations similar to the anisotropiesof the cosmic microwave background (CMB). Measurements of the unresolved Spitzer fluctuations by two independent teams on multiple fields agree within the measurement errors. However, there are now two interpretations on the origin of the unresolved IRAC fluctuations. One involves a population of faint sources at very high redshifts (z > 6) during the epoch of reionization. The second interpretation involves the integrated emission from intrahalo light associated with diffuse stars in the outskirts of z of 1 to 3 dark matter halos of galaxies. We now propose to further test these two interpretations with a new set of measurements at shorter IR and optical wavelengths with HST/ACS and WFC3 overlapping with deep IRAC surveys. A multi-wavelength study from 0.5 to 4.5 micron will allow us to independently determine the relative contribution of intrahalo light and z > 8 faint galaxies to the unresolved IR fluctuations. We will also place strong limits on the surface density of faint sources at z > 8. Such a limit will be useful for planning deep surveys with JWST. Moving to the recent wide IRAC fields with the warm mission, we propose to study fluctuations at tens of degree angular scales. At such large angular scales IRAC fluctuations should trace diffuse Galactic light (DGL), ISM dust-scattered starlight in our Galaxy. We will measure the amplitude and slope of the DGL power spectrum and compare them to measurements of the Galactic dust power spectrum from IRAS and Planck and study if the large degree-scale fluctuations seen in CIBER can be

  2. An Empirical Determination of the Intergalactic Background Light from UV to FIR Wavelengths Using FIR Deep Galaxy Surveys and the Gamma-ray Opacity of the Universe

    OpenAIRE

    Stecker, FW; Scully, ST; Malkan, MA

    2016-01-01

    We have previously calculated the intergalactic background light (IBL) as a function of redshift in the far ultraviolet to near infrared range, based purely on data from deep galaxy surveys. Here we utilize similar methods to determine the mid- and far infrared IBL out to a wavelength of 850 microns. Our approach enables us to constrain the range of photon densities, based on the uncertainties from observationally determined luminosity densities and colors. By also including...

  3. An Empirical Determination of the Intergalactic Background Light from UV to FIR Wavelengths Using FIR Deep Galaxy Surveys and the Gamma-ray Opacity of the Universe

    CERN Document Server

    Stecker, Floyd W; Malkan, Matthew A

    2016-01-01

    We have previously calculated the intergalactic background light (IBL) as a function of redshift in the far ultraviolet to near infrared range, based purely on data from deep galaxy surveys. Here we utilize similar methods to determine the mid- and far infrared IBL out to a wavelength of 850 microns. Our approach enables us to constrain the range of photon densities, based on the uncertainties from observationally determined luminosity densities and colors. By also including the effect of the 2.7 K cosmic background photons, we determine 68% confidence upper and lower limits on the opacity of the universe to gamma-rays up to PeV energies. Our direct results on the IBL are consistent with those from complimentary gamma-ray analyses using observations from the Fermi $\\gamma$-ray space telescope and the H.E.S.S. air Cherenkov telescope. Thus, we find no evidence of previously suggested processes for the modification of gamma-ray spectra other than that of absorption by pair production alone.

  4. Light on curved backgrounds

    Science.gov (United States)

    Batic, D.; Nelson, S.; Nowakowski, M.

    2015-05-01

    We consider the motion of light on different spacetime manifolds by calculating the deflection angle, lensing properties and by probing into the possibility of bound states. The metrics in which we examine the light motion include, among other items, a general relativistic dark matter metric, a dirty black hole, and a worm hole metric, the last two inspired by noncommutative geometry. The lensing in a holographic screen metric is discussed in detail. We study also the bending of light around naked singularities like, e.g., the Janis-Newman-Winicour metric and include other cases. A generic property of light behavior in these exotic metrics is pointed out. For the standard metric like the Schwarzschild and Schwarzschild-de Sitter cases, we improve the accuracy of the lensing results for the weak and strong regimes.

  5. Light on curved backgrounds

    CERN Document Server

    Batic, D; Nowakowski, M

    2014-01-01

    We consider the motion of light on different spacetime manifolds by calculating the deflection angle, lensing properties and by probing into the possibility of bound states. The metrics in which we examine the light motion include, among other, a general relativistic Dark Matter metric, a dirty Black Hole and a Worm Hole metric, the last two inspired by non-commutative geometry. The lensing in a Holographic Screen metric is discussed in detail. We study also the bending of light around naked singularities like, e.g., the Janis-Newman-Winicour metric and include other cases. A generic property of light behaviour in these exotic metrics is pointed out. For the standard metric like the Schwarzschild and Schwarzschild-de Sitter cases we improve the accuracy of the lensing results for the weak and strong regime.

  6. Cosmic Infrared Background Fluctuations and Zodiacal Light

    CERN Document Server

    Arendt, Richard G; Moseley, S H; Mather, J

    2016-01-01

    We have performed a specific observational test to measure the effect that the zodiacal light can have on measurements of the spatial fluctuations of the near-IR background. Previous estimates of possible fluctuations caused by zodiacal light have often been extrapolated from observations of the thermal emission at longer wavelengths and low angular resolution, or from IRAC observations of high latitude fields where zodiacal light is faint and not strongly varying with time. The new observations analyzed here target the COSMOS field, at low ecliptic latitude where the zodiacal light intensity varies by factors of $\\sim2$ over the range of solar elongations at which the field can be observed. We find that the white noise component of the spatial power spectrum of the background is correlated with the modeled zodiacal light intensity. Roughly half of the measured white noise is correlated with the zodiacal light, but a more detailed interpretation of the white noise is hampered by systematic uncertainties that ...

  7. Extragalactic Background Light: Measurements and Applications

    CERN Document Server

    Cooray, Asantha

    2016-01-01

    This review covers the measurements related to the extragalactic background light (EBL) intensity from gamma-rays to radio in the electromagnetic spectrum over 20 decades in the wavelength. The cosmic microwave background (CMB) remains the best measured spectrum with an accuracy better than 1%. The measurements related to the cosmic optical background (COB), centered at 1 microns, are impacted by the large zodiacal light associated with interplanetary dust in the inner Solar system. The best measurements of COB come from an indirect technique involving Gamma-ray spectra of bright blazars with an absorption feature resulting from pair-production off of COB photons. The cosmic infrared background (CIB) peaking at around 100 microns established an energetically important background with an intensity comparable to the optical background. This discovery paved the path for large aperture far-infrared and sub-millimeter observations resulting in the discovery of dusty, starbursting galaxies. Their role in galaxy for...

  8. Cosmic Infrared Background Fluctuations and Zodiacal Light

    Science.gov (United States)

    Arendt, Richard G.; Kashlinsky, A.; Moseley, S. H.; Mather, J.

    2017-01-01

    We performed a specific observational test to measure the effect that the zodiacal light can have on measurements of the spatial fluctuations of the near-IR (near-infrared)background. Previous estimates of possible fluctuations caused by zodiacal light have often been extrapolated from observations of the thermal emission at longer wavelengths and low angular resolution or from IRAC (Infrared Array Camera) observations of high-latitude fields where zodiacal light is faint and not strongly varying with time. The new observations analyzed here target the COSMOS (Cosmic Evolution Survey) field at low ecliptic latitude where the zodiacal light intensity varies by factors of approximately 2 over the range of solar elongations at which the field can be observed. We find that the white-noise component of the spatial power spectrum of the background is correlated with the modeled zodiacal light intensity. Roughly half of the measured white noise is correlated with the zodiacal light, but a more detailed interpretation of the white noise is hampered by systematic uncertainties that are evident in the zodiacal light model. At large angular scales (greater than or approximately equal to 100 arcseconds) where excess power above the white noise is observed, we find no correlation of the power with the modeled intensity of the zodiacal light. This test clearly indicates that the large-scale power in the infrared background is not being caused by the zodiacal light.

  9. Cosmic Infrared Background Fluctuations and Zodiacal Light

    Science.gov (United States)

    Arendt, Richard G.; Kashlinsky, A.; Moseley, S. H.; Mather, J.

    2017-01-01

    We performed a specific observational test to measure the effect that the zodiacal light can have on measurements of the spatial fluctuations of the near-IR (near-infrared)background. Previous estimates of possible fluctuations caused by zodiacal light have often been extrapolated from observations of the thermal emission at longer wavelengths and low angular resolution or from IRAC (Infrared Array Camera) observations of high-latitude fields where zodiacal light is faint and not strongly varying with time. The new observations analyzed here target the COSMOS (Cosmic Evolution Survey) field at low ecliptic latitude where the zodiacal light intensity varies by factors of approximately 2 over the range of solar elongations at which the field can be observed. We find that the white-noise component of the spatial power spectrum of the background is correlated with the modeled zodiacal light intensity. Roughly half of the measured white noise is correlated with the zodiacal light, but a more detailed interpretation of the white noise is hampered by systematic uncertainties that are evident in the zodiacal light model. At large angular scales (greater than or approximately equal to 100 arcseconds) where excess power above the white noise is observed, we find no correlation of the power with the modeled intensity of the zodiacal light. This test clearly indicates that the large-scale power in the infrared background is not being caused by the zodiacal light.

  10. Reduction of background clutter in structured lighting systems

    Science.gov (United States)

    Carlson, Jeffrey J.; Giles, Michael K.; Padilla, Denise D.; Davidson, Jr., Patrick A.; Novick, David K.; Wilson, Christopher W.

    2010-06-22

    Methods for segmenting the reflected light of an illumination source having a characteristic wavelength from background illumination (i.e. clutter) in structured lighting systems can comprise pulsing the light source used to illuminate a scene, pulsing the light source synchronously with the opening of a shutter in an imaging device, estimating the contribution of background clutter by interpolation of images of the scene collected at multiple spectral bands not including the characteristic wavelength and subtracting the estimated background contribution from an image of the scene comprising the wavelength of the light source and, placing a polarizing filter between the imaging device and the scene, where the illumination source can be polarized in the same orientation as the polarizing filter. Apparatus for segmenting the light of an illumination source from background illumination can comprise an illuminator, an image receiver for receiving images of multiple spectral bands, a processor for calculations and interpolations, and a polarizing filter.

  11. Wavelength-tunable duplex integrated light source

    Science.gov (United States)

    Okamoto, Hiroshi; Yasaka, Hiroshi; Oe, Kunishige

    1996-04-01

    A monolithically integrated opto-electronic device is proposed as a fast wavelength-switching light source. This tunable duplex integrated light source comprises two wavelength-tunable distributed Bragg reflector (DBR) laser diodes (LDs), two MQW-electro-absorption optical switches, a Y-shaped waveguide coupler, a MQW-electro-absorption modulator, and two thermal drift compensators (TDCs). The wavelength-switching time of the optical switches was estimated to be 60 ps including a 50-ps rise time for the electrical-pulse generator. The wavelength of a 10-Gbit/s NRZ-modulated optical signal can be switched without bit loss. The function of the TDCs is to keep the device-chip temperature constant. Thermal-transient- induced wavelength drift with a millisecond-order time constant, which has been reported for DBR-LDs, and thermal crosstalk between the tuning regions of the integrated LDs, which causes wavelength fluctuation, are effectively suppressed by thermal-drift-compensation operation using the TDCs.

  12. Extragalactic background light measurements and applications.

    Science.gov (United States)

    Cooray, Asantha

    2016-03-01

    This review covers the measurements related to the extragalactic background light intensity from γ-rays to radio in the electromagnetic spectrum over 20 decades in wavelength. The cosmic microwave background (CMB) remains the best measured spectrum with an accuracy better than 1%. The measurements related to the cosmic optical background (COB), centred at 1 μm, are impacted by the large zodiacal light associated with interplanetary dust in the inner Solar System. The best measurements of COB come from an indirect technique involving γ-ray spectra of bright blazars with an absorption feature resulting from pair-production off of COB photons. The cosmic infrared background (CIB) peaking at around 100 μm established an energetically important background with an intensity comparable to the optical background. This discovery paved the way for large aperture far-infrared and sub-millimetre observations resulting in the discovery of dusty, starbursting galaxies. Their role in galaxy formation and evolution remains an active area of research in modern-day astrophysics. The extreme UV (EUV) background remains mostly unexplored and will be a challenge to measure due to the high Galactic background and absorption of extragalactic photons by the intergalactic medium at these EUV/soft X-ray energies. We also summarize our understanding of the spatial anisotropies and angular power spectra of intensity fluctuations. We motivate a precise direct measurement of the COB between 0.1 and 5 μm using a small aperture telescope observing either from the outer Solar System, at distances of 5 AU or more, or out of the ecliptic plane. Other future applications include improving our understanding of the background at TeV energies and spectral distortions of CMB and CIB.

  13. Intrinsically stable light source at telecom wavelengths

    CERN Document Server

    Monteiro, Fernando; Sanguinetti, Bruno; Zbinden, Hugo

    2013-01-01

    We present a highly stable light source at telecom wavelengths, based on a short erbium doped fiber. The high stability arises from the high inversion of the Er3+ion population. This source is developed to work as a stable reference in radiometric applications and is useful in any application where high stability and/or a large bandwidth are necessary. The achieved long-term stability is 10 ppm.

  14. Effects of light wavelength and coherence in structured light sensors

    Science.gov (United States)

    Harding, Kevin; Ramamurthy, Rajesh; Zhai, Zirong; Han, Jie; Yang, Dongmin

    2016-05-01

    Structured light methods are used by many commercial products on the market today. Many such systems using white light projectors while many line gages use standard red laser diodes. However, in recent years there has been much claimed about using blue light, polarized light and partially coherent systems to obtain better performance. Unlike interferometers, moving from red to blue light for a system using only geometric shape information does not gain an automatic advantage from the shorter wavelength. The sensitivity metric does not have a wavelength component to it. But there are other factors that can improve gage performance. The ability to measure some feature is also a function of other parameters such as signal to noise ratio, reflectivity variations, and depth-of-field over which a clear pattern can be seen. This paper will explore the theoretical and experimental data relating to what works and what can be expected from variations on the old methods.

  15. Human wavelength discrimination of monochromatic light explained by optimal wavelength decoding of light of unknown intensity.

    Directory of Open Access Journals (Sweden)

    Li Zhaoping

    Full Text Available We show that human ability to discriminate the wavelength of monochromatic light can be understood as maximum likelihood decoding of the cone absorptions, with a signal processing efficiency that is independent of the wavelength. This work is built on the framework of ideal observer analysis of visual discrimination used in many previous works. A distinctive aspect of our work is that we highlight a perceptual confound that observers should confuse a change in input light wavelength with a change in input intensity. Hence a simple ideal observer model which assumes that an observer has a full knowledge of input intensity should over-estimate human ability in discriminating wavelengths of two inputs of unequal intensity. This confound also makes it difficult to consistently measure human ability in wavelength discrimination by asking observers to distinguish two input colors while matching their brightness. We argue that the best experimental method for reliable measurement of discrimination thresholds is the one of Pokorny and Smith, in which observers only need to distinguish two inputs, regardless of whether they differ in hue or brightness. We mathematically formulate wavelength discrimination under this wavelength-intensity confound and show a good agreement between our theoretical prediction and the behavioral data. Our analysis explains why the discrimination threshold varies with the input wavelength, and shows how sensitively the threshold depends on the relative densities of the three types of cones in the retina (and in particular predict discriminations in dichromats. Our mathematical formulation and solution can be applied to general problems of sensory discrimination when there is a perceptual confound from other sensory feature dimensions.

  16. Lethal effects of short-wavelength visible light on insects.

    Science.gov (United States)

    Hori, Masatoshi; Shibuya, Kazuki; Sato, Mitsunari; Saito, Yoshino

    2014-12-09

    We investigated the lethal effects of visible light on insects by using light-emitting diodes (LEDs). The toxic effects of ultraviolet (UV) light, particularly shortwave (i.e., UVB and UVC) light, on organisms are well known. However, the effects of irradiation with visible light remain unclear, although shorter wavelengths are known to be more lethal. Irradiation with visible light is not thought to cause mortality in complex animals including insects. Here, however, we found that irradiation with short-wavelength visible (blue) light killed eggs, larvae, pupae, and adults of Drosophila melanogaster. Blue light was also lethal to mosquitoes and flour beetles, but the effective wavelength at which mortality occurred differed among the insect species. Our findings suggest that highly toxic wavelengths of visible light are species-specific in insects, and that shorter wavelengths are not always more toxic. For some animals, such as insects, blue light is more harmful than UV light.

  17. Additivity of dichromatic color matches to short-wavelength lights.

    Science.gov (United States)

    Nagy, A L

    1984-11-01

    The additivity of color matches to short-wavelength lights was examined in observers who behaved as red-green dichromats under the stimulus conditions used. Color matches were obtained at several luminance levels and on several different adapting backgrounds. The range of mixtures acceptable as a match and the midpoint of this range varied considerably over different conditions. However, for each observer, a set of mixtures that remained a match under all conditions could always be found. Results suggest that the additivity laws hold for these observers in the sense that there is a color match that remains a match under all conditions.

  18. Propagation of light in area metric backgrounds

    Energy Technology Data Exchange (ETDEWEB)

    Punzi, Raffaele; Wohlfarth, Mattias N R [Zentrum fuer Mathematische Physik und II. Institut fuer Theoretische Physik, Universitaet Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany); Schuller, Frederic P, E-mail: raffaele.punzi@desy.d, E-mail: fps@aei.mpg.d, E-mail: mattias.wohlfarth@desy.d [Max Planck Institut fuer Gravitationsphysik, Albert Einstein Institut, Am Muehlenberg 1, 14467 Potsdam (Germany)

    2009-02-07

    The propagation of light in area metric spacetimes, which naturally emerge as refined backgrounds in quantum electrodynamics and quantum gravity, is studied from first principles. In the geometric-optical limit, light rays are found to follow geodesics in a Finslerian geometry, with the Finsler norm being determined by the area metric tensor. Based on this result, and an understanding of the nonlinear relation between ray vectors and wave covectors in such refined backgrounds, we study light deflection in spherically symmetric situations and obtain experimental bounds on the non-metricity of spacetime in the solar system.

  19. Dynamic wavelength conversion in copropagating slow-light pulses.

    Science.gov (United States)

    Kondo, K; Baba, T

    2014-06-06

    Dynamic wavelength conversion (DWC) is obtained by controlling copropagating slow-light signal and control pulse trajectories. Our method is based on the understanding that conventional resonator-based DWC can be generalized, and is linked to cross-phase modulation. Dispersion-engineered Si photonic crystal waveguides produce such slow-light pulses. Free carriers generated by two-photon absorption of the control pulse dynamically shift the signal wavelength. Matching the group velocities of the two pulses enhances the shift, elongating the interaction length. We demonstrate an extremely large wavelength shift in DWC (4.9 nm blueshift) for the signal wavelength. Although DWC is similar to the Doppler effect, we highlight their essential differences.

  20. EFFECTS OF LIGHT WAVELENGTHS AND COHERENCE ON BASIDIOSPORES GERMINATION

    Directory of Open Access Journals (Sweden)

    Natalia Poyedinok

    2015-02-01

    Full Text Available The effects of light wavelengths and coherence on basidiospore germination of Agaricus bisporus, Flammulina velutipes, Ganoderma applanatum, Ganoderma lucidum, Hericium erinaceus, Lentinus edodes and Pleurotus ostreatus have been studied. Short-term low-intensity irradiation by coherent (laser light wavelength 488.0 nm and 632.8 nm at doses 45 and 230 mJ/cm2 has significantly increased the number of germinated basidiospores. It has established that there are differences in the photosensitivity not only between species but also between strains. Spores irradiation by 514.5 nm light has been either neutral or inhibitory. A comparative analysis of basidiospores sensitivity to laser and LED light has also been conducted. To stimulate germination of basidiospores and growth of monokaryons the most suitable solution was to use red coherent and incoherent light of 632.8 nm and 660,0 nm for A. bisporus, G. applanatum and P. ostreatus, red and blue coherent light of 632.8 nm and 488,0 nm for F. velutipes, and both red and blue laser and LED light G. lucidum and H. erinaceus and for L. edodes. No essential difference of a continuous wave mode and intermittent mode light effect at the same doses and wavelength on spore germination were revealed. Light influence has reduced germination time and formation of aerial mycelium on agar medium as compared to the original value and increased the growth rate of monosporous isolates. Characterization of basidiospores photosensitivity and development of environmentally friendly stimulating methods of their germination is important for creating highly effective technologies of mushrooms selection and cultivation.

  1. Propagation of light pseudoscalar particles in a cosmological background.

    Science.gov (United States)

    Tinebra, F.

    1995-12-01

    The interaction between light pseudoscalar particles, having properties much like those of the invisible axion, and the cosmic-microwave-background electromagnetic field is considered in a simple cosmic evolutionary scenario. The quantum theory of this interaction is hence canonically developed and applied to study seed, possibly of cosmological origin, extragalactic radiation fields. After looking at the issue of anisotropies in the microwave cosmic-background radiation spectrum, the main arguments setting limits on the couplings of the right, popular, invisible axion are briefly reviewed. By allowing for a minimal extension of the Big Bang Standard Cosmology, namely by a primordial magnetic field, the author argues that a hypothetical, very light pseudoscalar particle, not too different from the recently proposed alternate version of the invisible axion, could give rise to very peculiar observational effects in the microwave cosmic background radiation sector. In a quite simplified version of such a model, the most important effect which emerges is the issue of a highly polarized, wavelength-dependent quadrupolar-like anisotropy. This prediction could be feeling with the claimed, at present well-established observation of a quadrupolar component in the cosmic microwave background radiation by COBE satellite.

  2. Plant lighting system with five wavelength-band light-emitting diodes providing photon flux density and mixing ratio control

    Directory of Open Access Journals (Sweden)

    Yano Akira

    2012-11-01

    Full Text Available Abstract Background Plant growth and development depend on the availability of light. Lighting systems therefore play crucial roles in plant studies. Recent advancements of light-emitting diode (LED technologies provide abundant opportunities to study various plant light responses. The LED merits include solidity, longevity, small element volume, radiant flux controllability, and monochromaticity. To apply these merits in plant light response studies, a lighting system must provide precisely controlled light spectra that are useful for inducing various plant responses. Results We have developed a plant lighting system that irradiated a 0.18 m2 area with a highly uniform distribution of photon flux density (PFD. The average photosynthetic PFD (PPFD in the irradiated area was 438 micro-mol m–2 s–1 (coefficient of variation 9.6%, which is appropriate for growing leafy vegetables. The irradiated light includes violet, blue, orange-red, red, and far-red wavelength bands created by LEDs of five types. The PFD and mixing ratio of the five wavelength-band lights are controllable using a computer and drive circuits. The phototropic response of oat coleoptiles was investigated to evaluate plant sensitivity to the light control quality of the lighting system. Oat coleoptiles irradiated for 23 h with a uniformly distributed spectral PFD (SPFD of 1 micro-mol m–2 s–1 nm–1 at every peak wavelength (405, 460, 630, 660, and 735 nm grew almost straight upwards. When they were irradiated with an SPFD gradient of blue light (460 nm peak wavelength, the coleoptiles showed a phototropic curvature in the direction of the greater SPFD of blue light. The greater SPFD gradient induced the greater curvature of coleoptiles. The relation between the phototropic curvature (deg and the blue-light SPFD gradient (micro-mol m–2 s–1 nm–1 m–1 was 2 deg per 1 micro-mol m–2 s–1 nm–1 m–1. Conclusions The plant lighting system, with a computer with a

  3. Time-multiplexed measurements of nonclassical light at telecom wavelengths

    Science.gov (United States)

    Harder, G.; Silberhorn, C.; Rehacek, J.; Hradil, Z.; Motka, L.; Stoklasa, B.; Sánchez-Soto, L. L.

    2014-10-01

    We report the experimental reconstruction of the statistical properties of an ultrafast pulsed type II parametric down-conversion source in a periodically poled potassium titanyl phosphate waveguide at telecom wavelengths, with almost perfect photon-number correlations. We use a photon-number-resolving time-multiplexed detector based on a fiber-optical setup and a pair of avalanche photodiodes. By resorting to a germane data-pattern tomography, we assess the properties of the nonclassical light states with unprecedented precision.

  4. Light-induced melatonin suppression at night after exposure to different wavelength composition of morning light.

    Science.gov (United States)

    Kozaki, Tomoaki; Kubokawa, Ayaka; Taketomi, Ryunosuke; Hatae, Keisuke

    2016-03-11

    Bright nocturnal light has been shown to suppress melatonin secretion. However, bright light exposure during the day might reduce light-induced melatonin suppression at night. The human circadian system is sensitive to short wavelength light. This study evaluated the preventive effect of different wavelengths of daytime light on light-induced melatonin suppression at night. Twelve male subjects were exposed to various light conditions (dim, white, and bluish white light) between the hours of 09:00 and 10:30 (daytime light conditions). They were then exposed to light (300lx) again between 01:00 and 02:30 (night-time light exposure). Subjects provided saliva samples before (00:55) and after night-time light exposure (02:30). A two-tailed paired t-test yielded significant decrements in melatonin concentrations after night-time light exposure under daytime dim and white light conditions. No significant differences were found in melatonin concentrations between pre- and post-night-time light exposure with bluish-white light. Present findings suggest that daytime blue light exposure has an acute preventive impact on light-induced melatonin suppression in individuals with a general life rhythm (sleep/wake schedule). These findings may be useful for implementing artificial light environments for humans in, for example, hospitals and underground shopping malls to reduce health risks.

  5. Semiconductor light source with electrically tunable emission wavelength

    Energy Technology Data Exchange (ETDEWEB)

    Belenky, Gregory (Port Jefferson, NY); Bruno, John D. (Bowie, MD); Kisin, Mikhail V. (Centereach, NY); Luryi, Serge (Setauket, NY); Shterengas, Leon (Centereach, NY); Suchalkin, Sergey (Centereach, NY); Tober, Richard L. (Elkridge, MD)

    2011-01-25

    A semiconductor light source comprises a substrate, lower and upper claddings, a waveguide region with imbedded active area, and electrical contacts to provide voltage necessary for the wavelength tuning. The active region includes single or several heterojunction periods sandwiched between charge accumulation layers. Each of the active region periods comprises higher and lower affinity semiconductor layers with type-II band alignment. The charge carrier accumulation in the charge accumulation layers results in electric field build-up and leads to the formation of generally triangular electron and hole potential wells in the higher and lower affinity layers. Nonequillibrium carriers can be created in the active region by means of electrical injection or optical pumping. The ground state energy in the triangular wells and the radiation wavelength can be tuned by changing the voltage drop across the active region.

  6. The North Ecliptic Pole Extragalactic Background LIght Fluctuations Survey

    Science.gov (United States)

    Bock, James; Zemcov, Michael; Cooray, Asantha; Smidt, Joseph; Serjeant, Stephen; Malkan, Matt; Matsuhara, Hideo; Matsumoto, Toshia; Matsuura, Shuji; Clements, David; Pearson, Chris; Im, Myung Shin

    2013-10-01

    We propose to image 6 deg^2 in the North Ecliptic Pole (NEP) with IRAC to determine the origin of Extragalactic Background Light (EBL) fluctuations. These Spitzer images will be combined with CIBER data at 1.1 and 1.6 um, and Akari data at 2.4, 3.2, and 4.1 um, to probe the spectrum and band-to-band correlations of the fluctuations. The fluctuations have been reported by Spitzer and Akari, and are now positively detected in new and CIBER data, but their origin is controversial. This multi-wavelength analysis will allow us to determine if EBL fluctuations arise from epoch of reionization galaxies or diffuse intra-halo light emission both by measuring their spectral energy distribution (SED) from 1.0 to 4.5 um, and by measuring the cross-correlation between different bands. The analysis uses multiple field combinations in Spitzer, CIBER and Akari data to carry out a robust measurement with multiple data combinations for internal consistency tests. In addition, the proposed survey will be used in conjunction with Akari and Herschel data in the NEP survey that has the most comprehensive multi-band infrared coverage of any degree-scale field on the sky and the best available constraints on dust phases (e.g. PAH, silicate absorption, AGN dust tori, GMCs) in galaxies. We will use this multi-wavelength coverage to cross-identify IRAC counterparts to Herschel and Akari sources and obtain SEDs of dusty, star bursting galaxies at z ~ 1 to 3 from the UV to radio, and obtain accurate PAH luminosities of Akari 7.7 um-rest detected galaxies and AGNs.

  7. New Measurements of the Cosmic Background Radiation Temperature at3.3 mm Wavelength

    Energy Technology Data Exchange (ETDEWEB)

    Witebsky, C.; Smoot, G.; De Amici, G.; Friedman, S.D.

    1986-02-01

    We have measured the temperature of the cosmic background radiation (CBR) at 3.3 mm wavelength in 1982, 1983, and 1984 as part of a larger project to determine the CBR temperature at five wavelengths from 12 cm to 3.3 mm (Smoot et al. 1985). The 3.3-mm measurements yield a brightness temperature of 2.57 K with a 1{sigma} uncertainty of 20.12 K. This paper describes the instrument, the measurement techniques, and the data-analysis procedures used. Our result is in good agreement with recent measurements at comparable wavelengths by Meyer and Jura (1985) and by Peterson, Richards, and Timusk (1985), but it disagrees with the temperatures reported by Woody and Richards (1981).

  8. Light Readout Optimisation using Wavelength Shifter - Reflector Combinations

    Energy Technology Data Exchange (ETDEWEB)

    Mavrokoridis, Konstantinos, E-mail: k.mavrokoridis@liverpool.ac.uk [Department of Physics, University of Liverpool, Oliver Lodge Lab, Oxford Street, Liverpool, L69 7ZE (United Kingdom)

    2011-07-25

    The use of reflectors coated with a wavelength shifter (WLS) along with standard bialkali PMTs is an economical method for an efficient readout system for vacuum ultra violet (VUV) light produced in large liquid argon detectors. Various thicknesses of tetraphenyl butadiene (TPB) were deposited by spraying and vacuum evaporation onto both specular 3M{sup TM}-foil and diffuse Tetratex{sup TM} (TTX) reflectors. 128 nm VUV light generated in 1 bar argon gas by a 5.4 MeV {alpha} source was detected by a 3-inch bialkali borosilicate PMT within a 1 m tube lined internally with a TPB coated reflector. The light collection was recorded as a function of separation between source and PMT for each combination of coating and reflector for distances up to 1m. Reflection coefficients of TPB coated reflectors were measured using a spectroradiometer. WLS coating on the PMT window was also studied. The optimum coating and reflector combination was TPB evaporated on TTX. Measurements with coating thicknesses of 0.2 mg/cm{sup 2} and 1.0 mg/cm{sup 2} yielded a similar performance. The best PMT window coating is obtained by TPB evaporation of 0.05 mg/cm{sup 2}.

  9. Marginal eyespots on butterfly wings deflect bird attacks under low light intensities with UV wavelengths.

    Directory of Open Access Journals (Sweden)

    Martin Olofsson

    Full Text Available BACKGROUND: Predators preferentially attack vital body parts to avoid prey escape. Consequently, prey adaptations that make predators attack less crucial body parts are expected to evolve. Marginal eyespots on butterfly wings have long been thought to have this deflective, but hitherto undemonstrated function. METHODOLOGY/PRINCIPAL FINDINGS: Here we report that a butterfly, Lopinga achine, with broad-spectrum reflective white scales in its marginal eyespot pupils deceives a generalist avian predator, the blue tit, to attack the marginal eyespots, but only under particular conditions-in our experiments, low light intensities with a prominent UV component. Under high light intensity conditions with a similar UV component, and at low light intensities without UV, blue tits directed attacks towards the butterfly head. CONCLUSIONS/SIGNIFICANCE: In nature, birds typically forage intensively at early dawn, when the light environment shifts to shorter wavelengths, and the contrast between the eyespot pupils and the background increases. Among butterflies, deflecting attacks is likely to be particularly important at dawn when low ambient temperatures make escape by flight impossible, and when insectivorous birds typically initiate another day's search for food. Our finding that the deflective function of eyespots is highly dependent on the ambient light environment helps explain why previous attempts have provided little support for the deflective role of marginal eyespots, and we hypothesize that the mechanism that we have discovered in our experiments in a laboratory setting may function also in nature when birds forage on resting butterflies under low light intensities.

  10. Light dilution via wavelength management for efficient high-density photobioreactors.

    Science.gov (United States)

    Ooms, Matthew D; Graham, Percival J; Nguyen, Brian; Sargent, Edward H; Sinton, David

    2017-02-06

    The spectral distribution of light influences microalgae productivity; however, development of photobioreactors has proceeded largely without regard to spectral optimization. Here we use monochromatic light to quantify the joint influence of path length, culture density, light intensity and wavelength on productivity and efficiency in Synechococcus elongatus. The productivity of green light was ∼4 x that of red at the highest levels of culture density, depth and light intensity. This performance is attributed to the combination of increased dilution and penetration of this weakly absorbed wavelength over a larger volume fraction of the reactor. In contrast, red light outperformed other wavelengths in low-density cultures with low light intensities. Low density cultures also adapted more rapidly to reduce absorption of longer wavelengths, allowing for prolonged cultivation. Taken together, these results indicate that, particularly for artificially lit photobioreactors, wavelength needs to be included as a critical operational parameter to maintain optimal performance. This article is protected by copyright. All rights reserved.

  11. Prototype for Long Wavelength Array Sees First Light

    Science.gov (United States)

    2007-03-01

    Astronomers at the Naval Research Laboratory have produced the first images of the sky from a prototype of the Long Wavelength Array (LWA), a revolutionary new radio telescope to be constructed in southwestern New Mexico. The images show emissions from the center of our Galaxy, a supermassive black hole, and the remnant of a star that exploded in a supernova over 300 years ago. Not only a milestone in the development of the LWA, the images are also a first glimpse through a new window on the cosmos. "First light" is an astronomical term for the first image produced with a telescope. It is a key milestone for any telescope because it indicates that all of the individual components are working in unison as planned. Once completed, the LWA will provide an entirely novel view of the sky, in the radio frequency range of 20-80 MHz, currently one of the most poorly explored regions of the electromagnetic spectrum in astronomy. The LWA will be able to make sensitive high-resolution images, and scan the sky rapidly for new and transient sources of radio waves, which might represent the explosion of distant, massive stars, the emissions from planets outside of our own solar system or even previously unknown objects or phenomena. "The LWA will allow us to make the sharpest images ever possible using very long wavelength radio waves. This newly opened window on the universe will help us understand the acceleration of relativistic particles in a variety of extreme astrophysical environments including from the most distant supermassive black holes. But perhaps most exciting is the promise of new source classes waiting to be discovered," says Dr. Namir Kassim, an NRL astronomer in the Remote Sensing Division and LWA Project Scientist. Dr. Tracy Clarke, of Interferometrics, Inc. in Herndon, Virginia, another astronomer on the NRL team adds, "By detecting distant clusters of galaxies the LWA may also provide new insights on the cosmological evolution of the mysterious dark matter

  12. Joint Light Tactical Vehicle (JLTV): Background and Issues for Congress

    Science.gov (United States)

    2017-01-10

    3 Information in this section is taken from the Army Product Manager , Joint Light Tactical Vehicle website, http://peocscss.tacom.army.mil...10 Information in this section, unless otherwise noted is taken from a briefing from the Project Manager ...Joint Light Tactical Vehicle (JLTV): Background and Issues for Congress Andrew Feickert Specialist in Military Ground Forces January 10, 2017

  13. Cost-effective wavelength selectable light source using DFB fiber laser array

    DEFF Research Database (Denmark)

    Liu, Fenghai; Xueyan, Zheng; Pedersen, Rune Johan Skullerud

    2000-01-01

    A cost-effective wavelength selectable light source comprising a distributed feedback (DFB) fibre laser array is proposed. A large number of wavelengths can be selected via optical space switches using only one shared pump laser. The structure is a good candidate for use as a wavelength selectabl...

  14. Enhanced UV light detection using wavelength-shifting properties of Silicon nanoparticles

    CERN Document Server

    Magill, S; Fizari, M; Malloy, J; Maximenko, Y; Xie, J; Yu, H

    2015-01-01

    Detection of UV photons is becoming increasingly necessary with the use of noble gases and liquids in elementary particle experiments. Cerenkov light in crystals and glasses, scintillation light in neutrino, dark matter, and rare decay experiments all require sensitivity to UV photons. New sensor materials are needed that can directly detect UV photons and/or absorb UV photons and re-emit light in the visible range measurable by existing photosensors. It has been shown that silicon nanoparticles are sensitive to UV light in a wavelength range around ~200 nm. UV light is absorbed and re-emitted at wavelengths in the visible range depending on the size of the nanoparticles. Initial tests of the wavelength-shifting properties of silicon nanoparticles are presented here that indicate by placing a film of nanoparticles in front of a standard visible-wavelength detecting photosensor, the response of the sensor is significantly enhanced at wavelengths < 320 nm.

  15. Observation of two output light pulses from a partial wavelength converter preserving phase of an input light at a single-photon level.

    Science.gov (United States)

    Ikuta, Rikizo; Kobayashi, Toshiki; Kato, Hiroshi; Miki, Shigehito; Yamashita, Taro; Terai, Hirotaka; Fujiwara, Mikio; Yamamoto, Takashi; Sasaki, Masahide; Wang, Zhen; Koashi, Masato; Imoto, Nobuyuki

    2013-11-18

    We experimentally demonstrate that both of the two output light pulses of different wavelengths from a wavelength converter with various branching ratios preserve phase information of an input light at a single-photon level. In our experiment, we converted temporally-separated two coherent light pulses with average photon numbers of ∼ 0.1 at 780 nm to light pulses at 1522 nm by using difference-frequency generation in a periodically-poled lithium niobate waveguide. We observed an interference between temporally-separated two modes for both the converted and the unconverted light pulses at various values of the conversion efficiency. We observed interference visibilities greater than 0.88 without suppressing the background noises for any value of the conversion efficiency the wavelength converter achieves. At a conversion efficiency of ∼ 0.5, the observed visibilities are 0.98 for the unconverted light and 0.99 for the converted light. Such a phase-preserving wavelength converter with high visibilities will be useful for manipulating quantum states encoded in the frequency degrees of freedom.

  16. Light use efficiency at different wavelengths in rose plants

    OpenAIRE

    Paradiso, R.; Meinen, E.; Snel, J.F.H.; Marcelis, L. F. M.; Ieperen, van, W.; Hogewoning, S.W.

    2011-01-01

    Current knowledge about the spectral dependence of leaf light use efficiency of leaf photosynthesis (LUE; rate of leaf photosynthesis per unit incident light energy) is based on investigations of mostly arable crops. The leaf LUE depends on the optical properties of the leaf (light absorption), on the fraction of light energy absorbed by photosynthetically active pigments and on the excitation balance of the two photosystems. These properties have hardly been investigated on modern vegetable ...

  17. Light use efficiency at different wavelengths in rose plants

    NARCIS (Netherlands)

    Paradiso, R.; Meinen, E.; Snel, J.F.H.; Marcelis, L.F.M.; Ieperen, van W.; Hogewoning, S.W.

    2011-01-01

    Current knowledge about the spectral dependence of leaf light use efficiency of leaf photosynthesis (LUE; rate of leaf photosynthesis per unit incident light energy) is based on investigations of mostly arable crops. The leaf LUE depends on the optical properties of the leaf (light absorption), on t

  18. Constraining Extragalactic Background Light From TeV Blazars

    OpenAIRE

    Yang, Jianping; Wang, Jiancheng

    2010-01-01

    Our goal is to research the upper limits on the extragalactic background light (EBL). The upper limits on the extragalactic background light (EBL), using the Fermi and very high energy (VHE) spectra recently observed in TeV blazars, are presented. We use an assumption that the VHE intrinsic photon index cannot be harder than the Fermi index measured by the Fermi-LAT. Totally, these upper limits on the EBL are compatible with ones given by most of EBL models. However, the models of high EBL de...

  19. Multi-wavelength holography with a single spatial light modulator for ultracold atom experiments.

    Science.gov (United States)

    Bowman, David; Ireland, Philip; Bruce, Graham D; Cassettari, Donatella

    2015-04-06

    We demonstrate a method to independently and arbitrarily tailor the spatial profile of light of multiple wavelengths and we show possible applications to ultracold atoms experiments. A single spatial light modulator is programmed to create a pattern containing multiple spatially separated structures in the Fourier plane when illuminated with a single wavelength. When the modulator is illuminated with overlapped laser beams of different wavelengths, the position of the structures is wavelength-dependent. Hence, by designing their separations appropriately, a desired overlap of different structures at different wavelengths is obtained. We employ regional phase calculation algorithms and demonstrate several possible experimental scenarios by generating light patterns with 670 nm, 780 nm and 1064 nm laser light which are accurate to the level of a few percent. This technique is easily integrated into cold atom experiments, requiring little optical access.

  20. Laser warning receiver to identify the wavelength and angle of arrival of incident laser light

    Science.gov (United States)

    Sinclair; Michael B.; Sweatt, William C.

    2010-03-23

    A laser warning receiver is disclosed which has up to hundreds of individual optical channels each optically oriented to receive laser light from a different angle of arrival. Each optical channel has an optical wedge to define the angle of arrival, and a lens to focus the laser light onto a multi-wavelength photodetector for that channel. Each multi-wavelength photodetector has a number of semiconductor layers which are located in a multi-dielectric stack that concentrates the laser light into one of the semiconductor layers according to wavelength. An electrical signal from the multi-wavelength photodetector can be processed to determine both the angle of arrival and the wavelength of the laser light.

  1. Optomechanical Light-Matter Interface with Optical Wavelength Conversion

    Science.gov (United States)

    2015-07-21

    Conversion Hailin Wang Department of Physics , University of Oregon, Eugene, OR 97403 Lin Tian School of Natural Science, University of California...the physical process can be exactly mapped to a cooling equation where the mechanical noise is extracted away from the system. In the physical ... electromechanical systems. Mechanically-mediated 14 DISTRIBUTION A: Distribution approved for public release. optical wavelength conversion, including

  2. Laser wavelength effect on nanosecond laser light reflection in ablation of metals

    Science.gov (United States)

    Benavides, O.; de la Cruz May, L.; Mejia, E. B.; Ruz Hernandez, J. A.; Flores Gil, A.

    2016-12-01

    Reflection of nanosecond laser pulses with different wavelengths (1.06 and 0.69 µm) in ablation of titanium in air is studied experimentally. The laser wavelength effect on reflection is essential at low laser fluence values. However, it becomes negligible for laser fluence values by about an order of magnitude higher than the plasma ignition threshold. We speculate that the disappearance of the wavelength effect is explained by counter-acting processes of the laser light absorption in plasma, which increases with laser wavelength, and absorption in the surface layer, which decreases with increasing laser wavelength.

  3. Propagation of light and fluids in string backgrounds

    CERN Document Server

    Punzi, Raffaele; Wohlfarth, Mattias N R

    2007-01-01

    The propagation of light in area metric spacetimes, which emerge as refined backgrounds from string theory, is studied from first principles. In the geometric-optical limit, the path taken by light rays is found to be governed by a Finsler geometry derived from the area metric spacetime structure. It is shown that precisely the same Finsler geometry determines the motion of string fluids that admit a point particle fluid limit. Based on these phenomenologically important results, we study light deflection and planetary motion in spherically symmetric situations, and obtain experimental bounds on the non-metricity of spacetime in the solar system.

  4. Stray light analysis of the Diffuse Infrared Background Experiment (DIRBE)

    Science.gov (United States)

    Breault, R. P.

    1984-01-01

    The straylight analysis of the diffuse infrared background experiment (DIRBE) on the cosmic background explorer (COBE) mission is discussed. From the statement of work (SOW), the purpose of DIRBE is to measure, or set upper limits on, the spectral and spatial character of the diffuse extra galactic infrared radiation. Diffuse infrared sources within our own galaxy are measured. The required reduction of the unwanted radiation imposes severe design and operating restrictions on the DIRBE instrument. To accomplish its missions, it will operate at a multitude of wavelengths ranging from 1.25 um out to 200 to 300 microns. The operating bands and the required point source normalized irradiance transmittance (PSNIT) are shown. The important straylight concepts in the DIRBE design are reviewed. The model and assumptions used in APART analysis are explained. The limitations due to the scalar theory used in the analysis are outlined.

  5. CALDER: Cryogenic light detectors for background-free searches

    Science.gov (United States)

    Cardani, L.; Bellini, F.; Casali, N.; Castellano, M. G.; Colantoni, I.; Coppolecchia, A.; Cosmelli, C.; Cruciani, A.; Di Domizio, S.; Tomei, C.; Vignati, M.

    2015-08-01

    The development of background-free detectors is essential for experiments searching for rare events. Bolometers, that are among the most competitive devices for the study of neutrino-less double beta decay (0νDBD) and Dark Matter interactions, suffer from the absence of techniques that allow to identify the nature of the interacting particles. This limit can be overcome by coupling the bolometer to an independent device for the measurement of the light emitted by interactions, as the combined read-out of the bolometric and light signals allows to identify and reject particles different from those of interest. CUORE, the most advanced bolometric experiment for 0νDBD searches, could disentangle the electrons produced by 0νDBD from the dangerous background due to α particles, by measuring the (tiny) Cherenkov light emitted by electrons and not by α's. LUCIFER, a project based on ZnSe scintillating bolometers for the study of 82Se 0νDBD, would be competitive also in the search of Dark Matter interactions if equipped with light detectors that allow to distinguish and reject the background due to electrons and γ's. These advances require cryogenic detectors characterized by noise lower than 20 eV, large active area, wide temperature range of operation, high radio-purity and ease in fabricating hundreds of channels. The CALDER collaboration aims to develop such detectors by exploiting the superb energy resolution and natural multiplexed read-out provided by Kinetic Inductance Detectors.

  6. Light Extraction Efficiency in OLED with Sub-wavelength Structures

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    By simulating with finite-difference time-domain(FDTD) method, it is proved that two kinds of new photonic crystal slab(PCS) structures could enhance the light extraction efficiency of OLED. By comparing the results, the most effective PCS structure with maximum light extraction efficiency(Er=1.99) is got. The optimized geometric parameters and optimized performance parameters of the PCS structures are also obtained.

  7. The cosmic infrared background experiment-2 (CIBER-2) for studying the near-infrared extragalactic background light

    Science.gov (United States)

    Shirahata, Mai; Arai, Toshiaki; Battle, John; Bock, James; Cooray, Asantha; Enokuchi, Akito; Hristov, Viktor; Kanai, Yoshikazu; Kim, Min Gyu; Korngut, Phillip; Lanz, Alicia; Lee, Dae-Hee; Mason, Peter; Matsumoto, Toshio; Matsuura, Shuji; Morford, Tracy; Ohnishi, Yosuke; Park, Won-Kee; Sano, Kei; Takeyama, Norihide; Tsumura, Kohji; Wada, Takehiko; Wang, Shiang-Yu; Zemcov, Michael

    2016-07-01

    We present the current status of the Cosmic Infrared Background ExpeRiment-2 (CIBER-2) project, whose goal is to make a rocket-borne measurement of the near-infrared Extragalactic Background Light (EBL), under a collaboration with U.S.A., Japan, South Korea, and Taiwan. The EBL is the integrated light of all extragalactic sources of emission back to the early Universe. At near-infrared wavelengths, measurement of the EBL is a promising way to detect the diffuse light from the first collapsed structures at redshift z˜10, which are impossible to detect as individual sources. However, recently, the intra-halo light (IHL) model is advocated as the main contribution to the EBL, and our new result of the EBL fluctuation from CIBER-1 experiment is also supporting this model. In this model, EBL is contributed by accumulated light from stars in the dark halo regions of low- redshift (zCIBER- 1 experiment, we are now developing a new instrument CIBER-2, which is comprised of a 28.5-cm aluminum telescope and three broad-band, wide-field imaging cameras. The three wide-field (2.3×2.3 degrees) imaging cameras use the 2K×2K HgCdTe HAWAII-2RG arrays, and cover the optical and near-infrared wavelength range of 0.5-0.9 μm, 1.0-1.4 μm and 1.5-2.0 μm, respectively. Combining a large area telescope with the high sensitivity detectors, CIBER-2 will be able to measure the spatial fluctuations in the EBL at much fainter levels than those detected in previous CIBER-1 experiment. Additionally, we will use a linear variable filter installed just above the detectors so that a measurement of the absolute spectrum of the EBL is also possible. In this paper, the scientific motivation and the expected performance for CIBER-2 will be presented. The detailed designs of the telescope and imaging cameras will also be discussed, including the designs of the mechanical, cryogenic, and electrical systems.

  8. Effects of light wavelengths on extracellular and capsular polysaccharide production by Nostoc flagelliforme.

    Science.gov (United States)

    Han, Pei-pei; Sun, Ying; Jia, Shi-ru; Zhong, Cheng; Tan, Zhi-lei

    2014-05-25

    The influences of different wavelengths of light (red 660nm, yellow 590nm, green 520nm, blue 460nm, purple 400nm) and white light on extracellular polysaccharide (EPS) and capsular polysaccharide (CPS) production by Nostoc flagelliforme in liquid culture were demonstrated in this study. The results showed that, compared with white light, red and blue lights significantly increased both EPS and CPS production while yellow light reduced their production; purple and green lights stimulated EPS production but inhibited CPS formation. Nine constituent monosaccharides and one uronic acid were detected in both EPS and CPS, and their ratios showed significant differences among treatment with different light wavelengths. However, the advanced structure of EPS and CPS from various light conditions did not present obvious difference through Fourier transform infrared spectroscopy and X-ray diffraction characterization. These findings establish a basis for development of high-yielding polysaccharide production process and understanding their regulation. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Continuous background light significantly increases flashing-light enhancement of photosynthesis and growth of microalgae.

    Science.gov (United States)

    Abu-Ghosh, Said; Fixler, Dror; Dubinsky, Zvy; Iluz, David

    2015-01-01

    Under specific conditions, flashing light enhances the photosynthesis rate in comparison to continuous illumination. Here we show that a combination of flashing light and continuous background light with the same integrated photon dose as continuous or flashing light alone can be used to significantly enhance photosynthesis and increase microalgae growth. To test this hypothesis, the green microalga Dunaliella salina was exposed to three different light regimes: continuous light, flashing light, and concomitant application of both. Algal growth was compared under three different integrated light quantities; low, intermediate, and moderately high. Under the combined light regime, there was a substantial increase in all algal growth parameters, with an enhanced photosynthesis rate, within 3days. Our strategy demonstrates a hitherto undescribed significant increase in photosynthesis and algal growth rates, which is beyond the increase by flashing light alone.

  10. CALDER: Cryogenic light detectors for background-free searches

    Energy Technology Data Exchange (ETDEWEB)

    Cardani, L. [Dipartimento di Fisica - Sapienza Università di Roma, Roma - Italy and Physics Department, Princeton University, Princeton, NJ (United States); Bellini, F.; Casali, N.; Coppolecchia, A.; Cosmelli, C.; Cruciani, A.; Vignati, M. [Dipartimento di Fisica - Sapienza Università di Roma and INFN - Sezione di Roma, Roma - Italy (Italy); Castellano, M. G. [Istituto di Fotonica e Nanotecnologie - CNR, Roma - Italy (Italy); Colantoni, I. [Dipartimento di Fisica - Sapienza Università di Roma (Italy); Di Domizio, S. [Dipartimento di Fisica, Università di Genova, Genova - Italy and INFN Sezione di Genova, Genova - Italy (Italy); Tomei, C. [INFN - Sezione di Roma, Roma - Italy (Italy)

    2015-08-17

    The development of background-free detectors is essential for experiments searching for rare events. Bolometers, that are among the most competitive devices for the study of neutrino-less double beta decay (0νDBD) and Dark Matter interactions, suffer from the absence of techniques that allow to identify the nature of the interacting particles. This limit can be overcome by coupling the bolometer to an independent device for the measurement of the light emitted by interactions, as the combined read-out of the bolometric and light signals allows to identify and reject particles different from those of interest. CUORE, the most advanced bolometric experiment for 0νDBD searches, could disentangle the electrons produced by 0νDBD from the dangerous background due to α particles, by measuring the (tiny) Cherenkov light emitted by electrons and not by α’s. LUCIFER, a project based on ZnSe scintillating bolometers for the study of {sup 82}Se 0νDBD, would be competitive also in the search of Dark Matter interactions if equipped with light detectors that allow to distinguish and reject the background due to electrons and γ’s. These advances require cryogenic detectors characterized by noise lower than 20 eV, large active area, wide temperature range of operation, high radio-purity and ease in fabricating hundreds of channels. The CALDER collaboration aims to develop such detectors by exploiting the superb energy resolution and natural multiplexed read-out provided by Kinetic Inductance Detectors.

  11. The Gamma Ray Opacity of the Universe -- Indirect Measurements of the Extragalactic Background Light

    CERN Document Server

    Krennrich, F

    2014-01-01

    Indirect constraints on the intensity of the Extragalactic Background Light (EBL) were provided by recent studies of extragalactic sources emitting sub-TeV to multi-TeV photons. These constraints are provided thanks to the absorption of gamma rays by soft photons from the EBL (UV/optical/IR) via pair production by gamma - gamma interactions. This paper provides an overview of recent results that have led to substantially reduced uncertainties on the EBL intensity over a wide range of wavelengths from 0.1 to 15 micron.

  12. Measuring Light from the Epoch of Reionization with CIBER, the Cosmic Infrared Background Experiment

    CERN Document Server

    Zemcov, Michael; Battle, John; Bock, James J; Cooray, Asantha; Hristov, Viktor; Keating, Brian; Kim, Min-Gyu; Lee, Dae-Hee; Levenson, Louis; Mason, Peter; Matsumoto, Toshio; Matsuura, Shuji; Mitchell-Wynne, Ketron; Nam, Uk Won; Renbarger, Tom; Smidt, Joseph; Sullivan, Ian; Tsumura, Kohji; Wada, Takehiko

    2011-01-01

    Ultraviolet emission from the first generation of stars in the Universe ionized the intergalactic medium in a process which was completed by z~6; the wavelength of these photons has been redshifted by (1+z) into the near infrared today and can be measured using instruments situated above the Earth's atmosphere. First flying in February 2009, the Cosmic Infrared Background Experiment (CIBER) comprises four instruments housed in a single reusable sounding rocket borne payload. CIBER will measure spatial anisotropies in the extragalactic IR background caused by cosmological structure from the epoch of reionization using two broadband imaging instruments, make a detailed characterization of the spectral shape of the IR background using a low resolution spectrometer, and measure the absolute brightness of the Zodical light foreground with a high resolution spectrometer in each of our six science fields. This paper presents the scientific motivation for CIBER and details of its first two flights, including a review...

  13. Phase response of the Arabidopsis thaliana circadian clock to light pulses of different wavelengths.

    Science.gov (United States)

    Ohara, Takayuki; Fukuda, Hirokazu; Tokuda, Isao T

    2015-04-01

    Light is known as one of the most powerful environmental time cues for the circadian system. The quality of light is characterized by its intensity and wavelength. We examined how the phase response of Arabidopsis thaliana depends on the wavelength of the stimulus light and the type of light perturbation. Using transgenic A. thaliana expressing a luciferase gene, we monitored the rhythm of the bioluminescence signal. We stimulated the plants under constant red light using 3 light perturbation treatments: (1) increasing the red light intensity, (2) turning on a blue light while turning off the red light, and (3) turning on a blue light while keeping the red light on. To examine the phase response properties, we generated a phase transition curve (PTC), which plots the phase after the perturbation as a function of the phase before the perturbation. To evaluate the effect of the 3 light perturbation treatments, we simulated PTCs using a mathematical model of the plant circadian clock and fitted the simulated PTCs to the experimentally measured PTCs. Among the 3 treatments, perturbation (3) provided the strongest stimulus. The results indicate that the color of the stimulus light and the type of pulse administration affect the phase response in a complex manner. Moreover, the results suggest the involvement of interaction between red and blue light signaling pathways in resetting of the plant circadian clock. © 2015 The Author(s).

  14. Workshop on scientific applications of short wavelength coherent light sources

    Energy Technology Data Exchange (ETDEWEB)

    Spicer, W.; Arthur, J.; Winick, H.

    1993-02-01

    This report contains paper on the following topics: A 2 to 4nm High Power FEL On the SLAC Linac; Atomic Physics with an X-ray Laser; High Resolution, Three Dimensional Soft X-ray Imaging; The Role of X-ray Induced Damage in Biological Micro-imaging; Prospects for X-ray Microscopy in Biology; Femtosecond Optical Pulses ; Research in Chemical Physics Surface Science, and Materials Science, with a Linear Accelerator Coherent Light Source; Application of 10 GeV Electron Driven X-ray Laser in Gamma-ray Laser Research; Non-Linear Optics, Fluorescence, Spectromicroscopy, Stimulated Desorption: We Need LCLS' Brightness and Time Scale; Application of High Intensity X-rays to Materials Synthesis and Processing; LCLS Optics: Selected Technological Issues and Scientific Opportunities; Possible Applications of an FEL for Materials Studies in the 60 eV to 200 eV Spectral Region.

  15. Workshop on scientific applications of short wavelength coherent light sources

    Energy Technology Data Exchange (ETDEWEB)

    Spicer, W.; Arthur, J.; Winick, H.

    1993-02-01

    This report contains paper on the following topics: A 2 to 4nm High Power FEL On the SLAC Linac; Atomic Physics with an X-ray Laser; High Resolution, Three Dimensional Soft X-ray Imaging; The Role of X-ray Induced Damage in Biological Micro-imaging; Prospects for X-ray Microscopy in Biology; Femtosecond Optical Pulses?; Research in Chemical Physics Surface Science, and Materials Science, with a Linear Accelerator Coherent Light Source; Application of 10 GeV Electron Driven X-ray Laser in Gamma-ray Laser Research; Non-Linear Optics, Fluorescence, Spectromicroscopy, Stimulated Desorption: We Need LCLS` Brightness and Time Scale; Application of High Intensity X-rays to Materials Synthesis and Processing; LCLS Optics: Selected Technological Issues and Scientific Opportunities; Possible Applications of an FEL for Materials Studies in the 60 eV to 200 eV Spectral Region.

  16. Technical study of visible light wavelength division multiplexing using polymer optical fiber

    Institute of Scientific and Technical Information of China (English)

    Yongsheng Zhang; Hui Ma; Tao Zhang; Zhuo Wang; Dong Wang; Rongsheng Zheng; Haipeng Yang; Hai Ming

    2005-01-01

    Visible light wavelength division multiplexing (VWDM) experiment was performed using polymer optical fiber (POF). Lights of two different wavelengths (650 and 530 nm) were sent to a single POF. Red light (650 nm) was used for 100-Mb/s full duplex IP data transmission and green light (530 nm) was used for voice signal transmission. Light sources are light-emitting diodes (LEDs). A POF coupler (splitter) and the prisms were employed as multiplexer and demultiplexer, respectively. The channel isolation and insert loss were measured, which are 20.5 and 17.65 dB for 650-nm channel respectively, and 19.16 and 20.55 dB for 530 nm one respectively.

  17. Modeling the role of mid-wavelength cones in circadian responses to light.

    Science.gov (United States)

    Dkhissi-Benyahya, Ouria; Gronfier, Claude; De Vanssay, Wena; Flamant, Frederic; Cooper, Howard M

    2007-03-01

    Nonvisual responses to light, such as photic entrainment of the circadian clock, involve intrinsically light-sensitive melanopsin-expressing ganglion cells as well as rod and cone photoreceptors. However, previous studies have been unable to demonstrate a specific contribution of cones in the photic control of circadian responses to light. Using a mouse model that specifically lacks mid-wavelength (MW) cones we show that these photoreceptors play a significant role in light entrainment and in phase shifting of the circadian oscillator. The contribution of MW cones is mainly observed for light exposures of short duration and toward the longer wavelength region of the spectrum, consistent with the known properties of this opsin. Modeling the contributions of the various photoreceptors stresses the importance of considering the particular spectral, temporal, and irradiance response domains of the photopigments when assessing their role and contribution in circadian responses to light.

  18. The Extragalactic Background Light and Absorption in Gamma Ray Spectra

    Science.gov (United States)

    Gilmore, Rudy C.

    2008-03-01

    Recent state-of-the-art semi-analytic models (SAMs) can now accurately model the history of galaxy formation and evolution. These SAMs utilize a 'forward evolution' approach and include all of the important processes for determining photon emission from galaxies, such as cooling and shock heating of gas, galaxy mergers, star formation and aging, supernova and AGN feedback, and the reprocessing of light by dust. I will be presenting our group's latest prediction of the extra-galactic background light based on this work and will discuss the implications for the attenuation of VHE gamma rays from distant sources due to pair-production. These results will be compared to recent limits placed on the EBL by observations of GeV and TeV blazar spectra by experiments such as H.E.S.S., MAGIC and VERITAS. The implications for reconstructing the intrinsic spectra of distant blazars will be addressed.

  19. Light Trapping Textures Designed by Electromagnetic Optimization for Sub-Wavelength Thick Solar Cells

    CERN Document Server

    Ganapati, Vidya; Yablonovitch, Eli

    2013-01-01

    Light trapping in solar cells allows for increased current and voltage, as well as reduced materials cost. It is known that in geometrical optics, a maximum 4n^2 absorption enhancement factor can be achieved by randomly texturing the surface of the solar cell, where n is the material refractive index. This ray-optics absorption enhancement limit only holds when the thickness of the solar cell is much greater than the optical wavelength. In sub-wavelength thin films, the fundamental questions remain unanswered: (1) what is the sub-wavelength absorption enhancement limit and (2) what surface texture realizes this optimal absorption enhancement? We turn to computational electromagnetic optimization in order to design nanoscale textures for light trapping in sub-wavelength thin films. For high-index thin films, in the weakly absorbing limit, our optimized surface textures yield an angle- and frequency-averaged enhancement factor ~39. They perform roughly 30% better than randomly textured structures, but they fall...

  20. Effect of light with different wavelengths on Nostoc flagelliforme cells in liquid culture.

    Science.gov (United States)

    Dai, Yu-Jie; Li, Jing; Wei, Shu-Mei; Chen, Nan; Xiao, Yu-Peng; Tan, Zhi-Lei; Jia, Shi-Ru; Yuan, Nan-Nan; Tan, Ning; Song, Yi-Jie

    2013-04-01

    The effects of lights with different wavelengths on the growth and the yield of extracellular polysaccharides of Nostoc flagelliforme cells were investigated in a liquid cultivation. N. flagelliforme cells were cultured for 16 days in 500 ml conical flasks containing BG11 culture medium under 27 micromol·m-2·s-1 of light intensity and 25 degrees C on a rotary shaker (140 rpm). The chlorophyll a, phycocyanin, allophycocyanin, and phycoerythrin contents in N. flagelliforme cells under the lights of different wavelengths were also measured. It was found that the cell biomass and the yield of polysaccharide changed with different wavelengths of light. The biomass and the yield of extracellular polysaccharides under the red or violet light were higher than those under other light colors. Chlorophyll a, phycocyanin, and allophycocyanin are the main pigments in N. flagelliforme cells. The results showed that N. flagelliforme, like other cyanobacteria, has the ability of adjusting the contents and relative ratio of its pigments with the light quality. As a conclusion, N. flagelliforme cells favor red and violet lights and perform the complementary chromatic adaptation ability to acclimate to the changes of the light quality in the environment.

  1. Cosmic Infrared Background ExpeRiment (CIBER): A Probe of Extragalactic Background Light from Reionization

    CERN Document Server

    Cooray, Asantha; Kawada, Mitsunobu; Keating, Brian; Lange, Andrew; Lee, Dae-Hee; Levenson, Louis; Matsumoto, Toshio; Matsuura, Shuji; Renbarger, Tom; Sullivan, Ian; Tsumura, Kohji; Wada, Takehiko; Zemcov, Michael

    2009-01-01

    The Cosmic Infrared Background ExpeRiment (CIBER) is a rocket-borne absolute photometry imaging and spectroscopy experiment optimized to detect signatures of first-light galaxies present during reionization in the unresolved IR background. CIBER-I consists of a wide-field two-color camera for fluctuation measurements, a low-resolution absolute spectrometer for absolute EBL measurements, and a narrow-band imaging spectrometer to measure and correct scattered emission from the foreground zodiacal cloud. CIBER-I was successfully flown on February 25th, 2009 and has one more planned flight in early 2010. We propose, after several additional flights of CIBER-I, an improved CIBER-II camera consisting of a wide-field 30 cm imager operating in 4 bands between 0.5 and 2.1 microns. It is designed for a high significance detection of unresolved IR background fluctuations at the minimum level necessary for reionization. With a FOV 50 to 2000 times largerthan existing IR instruments on satellites, CIBER-II will carry out ...

  2. Cosmic Infrared Background ExpeRiment (CIBER): A probe of Extragalactic Background Light from reionization

    Science.gov (United States)

    Cooray, Asantha; Bock, Jamie; Kawada, Mitsunobu; Keating, Brian; Lange, Andrew; Lee, Dae-Hee; Levenson, Louis; Matsumoto, Toshio; Matsuura, Shuji; Renbarger, Tom; Sullivan, Ian; Tsumura, Kohji; Wada, Takehiko; Zemcov, Michael

    2012-08-01

    The Cosmic Infrared Background ExpeRiment (CIBER) is a rocket-borne absolute photometry imaging and spectroscopy experiment optimized to detect signatures of first-light galaxies present during reionization in the unresolved IR background. CIBER-I consists of a wide-field two-color camera for fluctuation measurements, a low-resolution absolute spectrometer for absolute EBL measurements, and a narrow-band imaging spectrometer to measure and correct scattered emission from the foreground zodiacal cloud. CIBER-I was successfully flown in February 2009 and July 2010 and four more flights are planned by 2014, including an upgrade (CIBER-II). We propose, after several additional flights of CIBER-I, an improved CIBER-II camera consisting of a wide-field 30 cm imager operating in 4 bands between 0.5 and 2.1 microns. It is designed for a high significance detection of unresolved IR background fluctuations at the minimum level necessary for reionization. With a FOV 50 to 2000 times larger than existing IR instruments on satellites, CIBER-II will carry out the definitive study to establish the surface density of sources responsible for reionization.

  3. Multi-wavelength mid-IR light source for gas sensing

    Science.gov (United States)

    Karioja, Pentti; Alajoki, Teemu; Cherchi, Matteo; Ollila, Jyrki; Harjanne, Mikko; Heinilehto, Noora; Suomalainen, Soile; Viheriälä, Jukka; Zia, Nouman; Guina, Mircea; Buczyński, Ryszard; Kasztelanic, Rafał; Kujawa, Ireneusz; Salo, Tomi; Virtanen, Sami; Kluczyński, Paweł; Sagberg, Hâkon; Ratajczyk, Marcin; Kalinowski, Przemyslaw

    2017-02-01

    Cost effective multi-wavelength light sources are key enablers for wide-scale penetration of gas sensors at Mid-IR wavelength range. Utilizing novel Mid-IR Si-based photonic integrated circuits (PICs) filter and wide-band Mid-IR Super Luminescent Light Emitting Diodes (SLEDs), we show the concept of a light source that covers 2.5…3.5 μm wavelength range with a resolution of price can be lowered in high volumes by utilizing tailored molded IR lens technology and automated packaging and assembling technologies. The status of the development of the key components of the light source are reported. The PIC is based on the use of micron-scale SOI technology, SLED is based on AlGaInAsSb materials and the lenses are tailored heavy metal oxide glasses fabricated by the use of hot-embossing. The packaging concept utilizing automated assembly tools is depicted. In safety and security applications, the Mid-IR wavelength range covered by the novel light source allows for detecting several harmful gas components with a single sensor. At the moment, affordable sources are not available. The market impact is expected to be disruptive, since the devices currently in the market are either complicated, expensive and heavy instruments, or the applied measurement principles are inadequate in terms of stability and selectivity.

  4. Magnetic orientation of migratory robins, Erithacus rubecula, under long-wavelength light.

    Science.gov (United States)

    Wiltschko, Roswitha; Denzau, Susanne; Gehring, Dennis; Thalau, Peter; Wiltschko, Wolfgang

    2011-09-15

    The avian magnetic compass is an inclination compass that appears to be based on radical pair processes. It requires light from the short-wavelength range of the spectrum up to 565 nm green light; under longer wavelengths, birds are disoriented. When pre-exposed to longer wavelengths for 1 h, however, they show oriented behavior. This orientation is analyzed under 582 nm yellow light and 645 nm red light in the present study: while the birds in spring prefer northerly directions, they do not show southerly tendencies in autumn. Inversion of the vertical component does not have an effect whereas reversal of the horizontal component leads to a corresponding shift, indicating that a polar response to the magnetic field is involved. Oscillating magnetic fields in the MHz range do not affect the behavior but anesthesia of the upper beak causes disorientation. This indicates that the magnetic information is no longer provided by the radical pair mechanism in the eye but by the magnetite-based receptors in the skin of the beak. Exposure to long-wavelength light thus does not expand the spectral range in which the magnetic compass operates but instead causes a different mechanism to take over and control orientation.

  5. Short-Wavelength Light Enhances Cortisol Awakening Response in Sleep-Restricted Adolescents

    Directory of Open Access Journals (Sweden)

    Mariana G. Figueiro

    2012-01-01

    Full Text Available Levels of cortisol, a hormone produced by the adrenal gland, follow a daily, 24-hour rhythm with concentrations reaching a minimum in the evening and a peak near rising time. In addition, cortisol levels exhibit a sharp peak in concentration within the first hour after waking; this is known as the cortisol awakening response (CAR. The present study is a secondary analysis of a larger study investigating the impact of short-wavelength (λmax≈470 nm light on CAR in adolescents who were sleep restricted. The study ran over the course of three overnight sessions, at least one week apart. The experimental sessions differed in terms of the light exposure scenarios experienced during the evening prior to sleeping in the laboratory and during the morning after waking from a 4.5-hour sleep opportunity. Eighteen adolescents aged 12–17 years were exposed to dim light or to 40 lux (0.401 W/m2 of 470-nm peaking light for 80 minutes after awakening. Saliva samples were collected every 20 minutes to assess CAR. Exposure to short-wavelength light in the morning significantly enhanced CAR compared to dim light. Morning exposure to short-wavelength light may be a simple, yet practical way to better prepare adolescents for an active day.

  6. Dark matter powered stars: Constraints from the extragalactic background light

    CERN Document Server

    Maurer, A; Kneiske, T; Elsässer, D; Hauschildt, P H; Horns, D

    2012-01-01

    The existence of predominantly cold non-baryonic dark matter is unambiguously demonstrated by several observations (e.g., structure formation, big bang nucleosynthesis, gravitational lensing, and rotational curves of spiral galaxies). A candidate well motivated by particle physics is a weakly interacting massive particle (WIMP). Self-annihilating WIMPs would affect the stellar evolution especially in the early universe. Stars powered by self-annihilating WIMP dark matter should possess different properties compared with standard stars. While a direct detection of such dark matter powered stars seems very challenging, their cumulative emission might leave an imprint in the diffuse metagalactic radiation fields, in particular in the mid-infrared part of the electromagnetic spectrum. In this work the possible contributions of dark matter powered stars (dark stars; DSs) to the extragalactic background light (EBL) are calculated. It is shown that existing data and limits of the EBL intensity can already be used to...

  7. Short-wavelength attenuated polychromatic white light during work at night : Limited melatonin suppression without substantial decline of alertness

    NARCIS (Netherlands)

    van de Werken, Maan; Giménez, Marina C; de Vries, Bonnie; Beersma, Domien G M; Gordijn, Marijke C M

    Exposure to light at night increases alertness, but light at night (especially short-wavelength light) also disrupts nocturnal physiology. Such disruption is thought to underlie medical problems for which shiftworkers have increased risk. In 33 male subjects we investigated whether short-wavelength

  8. The effect of incident angle of pumping light on Cholesteric Liquid Crystal tunable laser wavelength

    CERN Document Server

    Yin, Xiangbao

    2014-01-01

    One notable feature of dye doped cholesteric liquid crystal is the variation of pitch and refractive index as the incidence angle of the pumping light shifts. Based on this feature, this paper studies the effects of pumping light's incidence angle on emission properties of the dye doped cholesteric liquid crystal tunable laser. First, we investigated the relationship among the concentration of chiral reagent, the incidence angle of the pumping light, and the pitch of liquid-crystal display (LCD); then we made a tunable-wavelength laser and pumped the prepared sample with 532nm laser outputted from the Nd: YAG multi-frequency pulse laser. As the incident angle of the pumping light shifts between 20 {\\deg} ~ 90 {\\deg}, the tuning range of the wavelength emitted by the laser reaches 10.73nm, ranging between 647.38nm and 658.11nm.

  9. Sparsity based sub-wavelength imaging with partially incoherent light via quadratic compressed sensing

    CERN Document Server

    Shechtman, Yoav; Szameit, Alexander; Segev, Mordechai

    2011-01-01

    We demonstrate that sub-wavelength optical images borne on partially-spatially-incoherent light can be recovered, from their far-field or from the blurred image, given the prior knowledge that the image is sparse, and only that. The reconstruction method relies on the recently demonstrated sparsity-based sub-wavelength imaging. However, for partially-spatially-incoherent light, the relation between the measurements and the image is quadratic, yielding non-convex measurement equations that do not conform to previously used techniques. Consequently, we demonstrate new algorithmic methodology, referred to as quadratic compressed sensing, which can be applied to a range of other problems involving information recovery from partial correlation measurements, including when the correlation function has local dependencies. Specifically for microscopy, this method can be readily extended to white light microscopes with the additional knowledge of the light source spectrum.

  10. Extragalactic Background Light and Gamma-Ray Attenuation

    CERN Document Server

    Primack, Joel R; Gilmore, Rudy C; Somerville, Rachel S

    2011-01-01

    Data from (non-) attenuation of gamma rays from active galactic nuclei (AGN) and gamma ray bursts (GRBs) give upper limits on the extragalactic background light (EBL) from the UV to the mid-IR that are only a little above the lower limits from observed galaxies. These upper limits now rule out some EBL models and purported observations, with improved data likely to provide even stronger constraints. We present EBL calculations both based on multiwavelength observations of thousands of galaxies and also based on semi-analytic models, and show that they are consistent with these lower limits from observed galaxies and with the gamma-ray upper limit constraints. Such comparisons "close the loop" on cosmological galaxy formation models, since they account for all the light, including that from galaxies too faint to see. We compare our results with those of other recent works, and discuss the implications of these new EBL calculations for gamma ray attenuation. Catching a few GRBs with groundbased atmospheric Cher...

  11. Influence of Peak Wavelengths on Properties of Mixed-LED White-Light Sources

    Directory of Open Access Journals (Sweden)

    Snjezana Soltic

    2010-01-01

    Full Text Available The purpose of this investigation is to quantify the influence of the peak wavelength shifts in commercially available LEDs on the characteristics of the mixed-LED white-light sources. For this purpose, a tetrachromatic spectrum was optimized and then subjected to deviations in the peak wavelengths. A total of 882 combinations of peak wavelength values were evaluated, and the results are reported in terms of correlated colour temperature, colour-rendering properties, and radiant luminous efficacy. The results show that there can be significant changes in the characteristics of the source under these conditions. Such changes are highly likely to present problems when dealing with applications where an effective and accurate white-light source is important.

  12. Analysis of complex samples using a portable multi-wavelength light emitting diode (LED) fluorescence spectrometer

    Science.gov (United States)

    Spectroscopic analysis of chemically complex samples often requires an increase n the dimensionality of the measured response surface. This often involves the measurement of emitted light intensities as functions of both wavelengths of excitation and emission resulting in the generation of an excita...

  13. Molecular genetic response to varied wavelengths of light in Xiphophorus maculatus skin.

    Science.gov (United States)

    Chang, Jordan; Lu, Yuan; Boswell, William T; Boswell, Mikki; Caballero, Kaela L; Walter, Ronald B

    2015-12-01

    Xiphophorus fishes represent a model often utilized to study UVB induced tumorigenesis. Recently, varied genetic responses to UVB exposure have been documented in the skin of female and male Xiphophorus, as have differences in UVB response in the skin of different parental species and for interspecies hybrids produced from crossing them. Additionally, it has been shown that exposure to "cool white" fluorescent light induces a shift in the genetic profiles of Xiphophorus skin that is nearly as robust as the UVB response, but involves a fundamentally different set of genes. Given these results and the use of Xiphophorus interspecies hybrids as an experimental model for UVB inducible melanoma, it is of interest to characterize genes that may be transcriptionally modulated in a wavelength specific manner. The global molecular genetic response of skin upon exposure of the intact animal to specific wavelengths of light has not been investigated. Herein, we report results of RNA-Seq experiments from the skin of male Xiphophorus maculatus Jp 163 B following exposure to varied 50nm wavelengths of light ranging from 300-600nm. We identify two specific wavelength regions, 350-400nm (88 genes) and 500-550nm (276 genes), that exhibit transcriptional modulation of a significantly greater number of transcripts than any of the other 50nm regions in the 300-600nm range. Observed functional sets of genes modulated within these two transcriptionally active light regions suggest different mechanisms of gene modulation.

  14. Magic wavelengths of Ca+ ion for linearly and circularly polarized light

    Science.gov (United States)

    Jiang, Jun; Jiang, Li; Wang, Xia; Shaw, Peter; Zhang, Deng-Hong; Xie, Lu-You; Dong, Chen Zhong

    2017-07-01

    The dynamic dipole polarizabilities of the low-lying states of Ca$^{+}$ for linearly and circularly polarized light are calculated by using relativistic configuration interaction plus core polarization (RCICP) approach. The magic wavelengths, at which the two levels of the transitions have the same ac Stark shifts, for $4s$-$4p_{j,m}$ and $4s$-$3d_{j,m}$ magnetic sublevels transitions are determined. The present magic wavelengths for linearly polarized light agree with the available results excellently. The polarizability for the circularly polarized light has the scalar, vector and tensor components. The dynamic polarizability is different for each of magnetic sublevels of the atomic state. Additional magic wavelengths have been found for the circularly polarized light. We recommend that the measurement of the magic wavelength near 850 nm for $4s-4p_{\\frac32,m=\\pm\\frac32,\\pm\\frac12}$ could be able to determine the oscillator strength ratio of $f_{4p_{\\frac32} \\to 3d_{\\frac32}}$ and $f_{4p_{\\frac32} \\to 3d_{\\frac52}}$.

  15. Sub-wavelength surface gratings for light redirection in transparent substrates

    DEFF Research Database (Denmark)

    Buss, Thomas; Smith, Cameron; Christiansen, Mads Brøkner

    2012-01-01

    based on diffraction and ray-optics, and complemented by numerical simulations. We show that our approach is suitable for redirecting and guiding light over a broad range of incident angles and wavelengths in transparent substrates. The technique has potential applications for solar harvesting in window...

  16. Radio Wavelength Constraints on the Sources of the Far Infrared Background

    CERN Document Server

    Haarsma, D B

    1998-01-01

    The cosmic far infrared background detected recently by the COBE-DIRBE team is presumably due, in large part, to the far infrared (FIR) emission from all galaxies. We take the well-established correlation between FIR and radio luminosity for individual galaxies and apply it to the FIR background. We find that these sources make up about half of the extragalactic radio background, the other half being due to AGN. This is in agreement with other radio observations, which leads us to conclude that the FIR-radio correlation holds well for the very faint sources making up the FIR background, and that the FIR background is indeed due to star-formation activity (not AGN or other possible sources). If these star-forming galaxies have a radio spectral index between 0.4 and 0.8, and make up 40 to 60% of the extragalactic radio background, we find that they have redshifts between roughly 1 and 2, in agreement with recent estimates by Madau et al. of the redshift of peak star-formation activity. We compare the observed e...

  17. Growth and development of Arabidopsis thaliana under single-wavelength red and blue laser light

    KAUST Repository

    Ooi, Amanda Siok Lee

    2016-09-23

    Indoor horticulture offers a sensible solution for sustainable food production and is becoming increasingly widespread. However, it incurs high energy and cost due to the use of artificial lighting such as high-pressure sodium lamps, fluorescent light or increasingly, the light-emitting diodes (LEDs). The energy efficiency and light quality of currently available horticultural lighting is suboptimal, and therefore less than ideal for sustainable and cost-effective large-scale plant production. Here, we demonstrate the use of high-powered single-wavelength lasers for indoor horticulture. They are highly energy-efficient and can be remotely guided to the site of plant growth, thus reducing on-site heat accumulation. Furthermore, laser beams can be tailored to match the absorption profiles of different plant species. We have developed a prototype laser growth chamber and demonstrate that plants grown under laser illumination can complete a full growth cycle from seed to seed with phenotypes resembling those of plants grown under LEDs reported previously. Importantly, the plants have lower expression of proteins diagnostic for light and radiation stress. The phenotypical, biochemical and proteome data show that the single-wavelength laser light is suitable for plant growth and therefore, potentially able to unlock the advantages of this next generation lighting technology for highly energy-efficient horticulture.

  18. Growth and development of Arabidopsis thaliana under single-wavelength red and blue laser light.

    Science.gov (United States)

    Ooi, Amanda; Wong, Aloysius; Ng, Tien Khee; Marondedze, Claudius; Gehring, Christoph; Ooi, Boon S

    2016-09-23

    Indoor horticulture offers a sensible solution for sustainable food production and is becoming increasingly widespread. However, it incurs high energy and cost due to the use of artificial lighting such as high-pressure sodium lamps, fluorescent light or increasingly, the light-emitting diodes (LEDs). The energy efficiency and light quality of currently available horticultural lighting is suboptimal, and therefore less than ideal for sustainable and cost-effective large-scale plant production. Here, we demonstrate the use of high-powered single-wavelength lasers for indoor horticulture. They are highly energy-efficient and can be remotely guided to the site of plant growth, thus reducing on-site heat accumulation. Furthermore, laser beams can be tailored to match the absorption profiles of different plant species. We have developed a prototype laser growth chamber and demonstrate that plants grown under laser illumination can complete a full growth cycle from seed to seed with phenotypes resembling those of plants grown under LEDs reported previously. Importantly, the plants have lower expression of proteins diagnostic for light and radiation stress. The phenotypical, biochemical and proteome data show that the single-wavelength laser light is suitable for plant growth and therefore, potentially able to unlock the advantages of this next generation lighting technology for highly energy-efficient horticulture.

  19. Growth and development of Arabidopsis thaliana under single-wavelength red and blue laser light

    Science.gov (United States)

    Ooi, Amanda; Wong, Aloysius; Ng, Tien Khee; Marondedze, Claudius; Gehring, Christoph; Ooi, Boon S.

    2016-01-01

    Indoor horticulture offers a sensible solution for sustainable food production and is becoming increasingly widespread. However, it incurs high energy and cost due to the use of artificial lighting such as high-pressure sodium lamps, fluorescent light or increasingly, the light-emitting diodes (LEDs). The energy efficiency and light quality of currently available horticultural lighting is suboptimal, and therefore less than ideal for sustainable and cost-effective large-scale plant production. Here, we demonstrate the use of high-powered single-wavelength lasers for indoor horticulture. They are highly energy-efficient and can be remotely guided to the site of plant growth, thus reducing on-site heat accumulation. Furthermore, laser beams can be tailored to match the absorption profiles of different plant species. We have developed a prototype laser growth chamber and demonstrate that plants grown under laser illumination can complete a full growth cycle from seed to seed with phenotypes resembling those of plants grown under LEDs reported previously. Importantly, the plants have lower expression of proteins diagnostic for light and radiation stress. The phenotypical, biochemical and proteome data show that the single-wavelength laser light is suitable for plant growth and therefore, potentially able to unlock the advantages of this next generation lighting technology for highly energy-efficient horticulture. PMID:27659906

  20. Axion decay and anisotropy of near-IR extragalactic background light

    CERN Document Server

    Gong, Yan; Mitchell-Wynne, Ketron; Chen, Xuelei; Zemcov, Michael; Smidt, Joseph

    2015-01-01

    The extragalactic background light is expected to be comprised of the cumulative radiation from all galaxies and active galactic nuclei over the cosmic history. In addition to point sources, EBL also contains information from diffuse sources of radiation. An example is the intra-halo light, associated with diffuse stars in dark matter halos resulting from galaxy mergers and tidal interactions, identified based on measurements involving the angular power spectrum of infrared background anisotropies. The angular power spectra of the near-infrared intensities could still contain additional signals and a complete understanding of the nature of the IR background is still lacking in the literature. Here we explore the constraints that can be placed on the decay products associated with particle decays, especially candidate dark matter models involving axions that trace dark matter halos of galaxies. Axions with a mass around a few eV will decay via two photons with wavelengths in the near-IR band, and will leave a ...

  1. Multiplexed single-mode wavelength-to-time mapping of multimode light

    Science.gov (United States)

    Chandrasekharan, Harikumar K.; Izdebski, Frauke; Gris-Sánchez, Itandehui; Krstajić, Nikola; Walker, Richard; Bridle, Helen L.; Dalgarno, Paul A.; MacPherson, William N.; Henderson, Robert K.; Birks, Tim A.; Thomson, Robert R.

    2017-01-01

    When an optical pulse propagates along an optical fibre, different wavelengths travel at different group velocities. As a result, wavelength information is converted into arrival-time information, a process known as wavelength-to-time mapping. This phenomenon is most cleanly observed using a single-mode fibre transmission line, where spatial mode dispersion is not present, but the use of such fibres restricts possible applications. Here we demonstrate that photonic lanterns based on tapered single-mode multicore fibres provide an efficient way to couple multimode light to an array of single-photon avalanche detectors, each of which has its own time-to-digital converter for time-correlated single-photon counting. Exploiting this capability, we demonstrate the multiplexed single-mode wavelength-to-time mapping of multimode light using a multicore fibre photonic lantern with 121 single-mode cores, coupled to 121 detectors on a 32 × 32 detector array. This work paves the way to efficient multimode wavelength-to-time mapping systems with the spectral performance of single-mode systems.

  2. Pupillary responses to short-wavelength light are preserved in aging

    Science.gov (United States)

    Rukmini, A. V.; Milea, Dan; Aung, Tin; Gooley, Joshua J.

    2017-01-01

    With aging, less blue light reaches the retina due to gradual yellowing of the lens. This could result in reduced activation of blue light-sensitive melanopsin-containing retinal ganglion cells, which mediate non-visual light responses (e.g., the pupillary light reflex, melatonin suppression, and circadian resetting). Herein, we tested the hypothesis that older individuals show greater impairment of pupillary responses to blue light relative to red light. Dose-response curves for pupillary constriction to 469-nm blue light and 631-nm red light were compared between young normal adults aged 21–30 years (n = 60) and older adults aged ≥50 years (normal, n = 54; mild cataract, n = 107; severe cataract, n = 18). Irrespective of wavelength, pupillary responses were reduced in older individuals and further attenuated by severe, but not mild, cataract. The reduction in pupillary responses was comparable in response to blue light and red light, suggesting that lens yellowing did not selectively reduce melanopsin-dependent light responses. Compensatory mechanisms likely occur in aging that ensure relative constancy of pupillary responses to blue light despite changes in lens transmission. PMID:28266650

  3. Dual-wavelength excitation to reduce background fluorescence for fluorescence spectroscopic quantitation of erythrocyte zinc protoporphyrin-IX and protoporphyrin-IX from whole blood and oral mucosa

    Science.gov (United States)

    Hennig, Georg; Vogeser, Michael; Holdt, Lesca M.; Homann, Christian; Großmann, Michael; Stepp, Herbert; Gruber, Christian; Erdogan, Ilknur; Hasmüller, Stephan; Hasbargen, Uwe; Brittenham, Gary M.

    2014-02-01

    Erythrocyte zinc protoporphyrin-IX (ZnPP) and protoporphyrin-IX (PPIX) accumulate in a variety of disorders that restrict or disrupt the biosynthesis of heme, including iron deficiency and various porphyrias. We describe a reagent-free spectroscopic method based on dual-wavelength excitation that can measure simultaneously both ZnPP and PPIX fluorescence from unwashed whole blood while virtually eliminating background fluorescence. We further aim to quantify ZnPP and PPIX non-invasively from the intact oral mucosa using dual-wavelength excitation to reduce the strong tissue background fluorescence while retaining the faint porphyrin fluorescence signal originating from erythrocytes. Fluorescence spectroscopic measurements were made on 35 diluted EDTA blood samples using a custom front-face fluorometer. The difference spectrum between fluorescence at 425 nm and 407 nm excitation effectively eliminated background autofluorescence while retaining the characteristic porphyrin peaks. These peaks were evaluated quantitatively and the results compared to a reference HPLC-kit method. A modified instrument using a single 1000 μm fiber for light delivery and detection was used to record fluorescence spectra from oral mucosa. For blood measurements, the ZnPP and PPIX fluorescence intensities from the difference spectra correlated well with the reference method (ZnPP: Spearman's rho rs = 0.943, p erythrocyte ZnPP and PPIX.

  4. Proliferation of chicken fibroblasts induced by light-emitting diodes: a comparative trial for different wavelengths

    Science.gov (United States)

    Vinck, Elke; Cagnie, B.; Declercq, H.; Cornelissen, R.; Cambier, D.

    2003-12-01

    The effectiveness and applicability of a variety of light sources, in the treatment of wounds has thoroughly been investigated, in vitro as well as in vivo. The current commercial availability of Light Emitting Diode (LED) sources therefore also invites research to explore the effect of low power infrared, red and green light on wound healing, e.g. by means of fibroblast proliferation. Therefore a controlled and randomized study on cultured embryonic chicken fibroblasts was conducted. The fibroblasts were irradiated during three consecutive days, at several wavelengths (950 nm, 660 nm and 570 nm) and a respective power output of 160 mW, 80 mW or 10 mW. Treatment duration varied from 1 minute to 3 minutes to obtain a surface energy density of 0.9 J/cm2 (infrared and red light) or 0.2 J/cm2 (green light). Statistical analysis revealed that LED irradiation for all three wavelengths induced a higher rate of proliferation in comparison of the control group. This difference was statistically significant (p cells, than the red (p < .001) an the infrared probe (p < .001). Furthermore, the red probe provided a higher increase (p < .001) than the IR probe. LED irradiation results in an increased fibroblast proliferation in vitro. This outcome postulates beneficial stimulatory effects of LED at the applied wavelength, energy density and power output on wound healing in vivo. Further investigation is necessary to examine this hypothesis.

  5. Discontinuous space variant sub-wavelength structures for generating radially polarized light in visible region

    Science.gov (United States)

    Ghadyani, Z.; Dmitriev, S.; Lindlein, N.; Leuchs, G.; Rusina, O.; Harder, I.

    2011-08-01

    A discontinuous space variant sub-wavelength dielectric grating is designed and fabricated for generating radially polarized light in visible region (l = 632.8 nm). The design is based on sub-wavelength silicon nitride structures introducing a retardation of p/2 by form birefringence, with space variant orientation of the optical axis. The pattern is divided into concentric ring segments with constant structural parameters, therefore reducing electron-beam writing time significantly. The design avoids the technological challenges encountered in the generation of a continuous space variant grating while maintaining good quality of the resulting polarization mode.

  6. Effect of multi-wavelength irradiation on color characterization with light-emitting diodes (LEDs)

    Science.gov (United States)

    Park, Hyeong Ju; Song, Woosub; Lee, Byeong-Il; Kim, Hyejin; Kang, Hyun Wook

    2017-06-01

    In the current study, a multi-wavelength light-emitting diode (LED)-integrated CMOS imaging device was developed to investigate the effect of various wavelengths on multiple color characterization. Various color pigments (black, red, green, and blue) were applied on both white paper and skin phantom surfaces for quantitative analysis. The artificial skin phantoms were made of polydimethylsiloxane (PDMS) mixed with coffee and TiO2 powder to emulate the optical properties of the human dermis. The customized LED-integrated imaging device acquired images of the applied pigments by sequentially irradiating with the LED lights in the order of white, red, green, and blue. Each color pigment induced a lower contrast during illumination by the light with the equivalent color. However, the illumination by light with the complementary (opposite) color increased the signal-to-noise ratio by up to 11-fold due to the formation of a strong contrast ( i.e., red LED = 1.6 ± 0.3 vs. green LED = 19.0 ± 0.6 for red pigment). Detection of color pigments in conjunction with multi-wavelength LEDs can be a simple and reliable technique to estimate variations in the color pigments quantitatively.

  7. Light-emitting-diode induced retinal damage and its wavelength dependency in vivo.

    Science.gov (United States)

    Shang, Yu-Man; Wang, Gen-Shuh; Sliney, David H; Yang, Chang-Hao; Lee, Li-Ling

    2017-01-01

    To examine light-emitting-diode (LED)-induced retinal neuronal cell damage and its wavelength-driven pathogenic mechanisms. Sprague-Dawley rats were exposed to blue LEDs (460 nm), green LEDs (530 nm), and red LEDs (620 nm). Electroretinography (ERG), Hematoxylin and eosin (H&E) staining, transmission electron microscopy (TEM), terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), and immunohistochemical (IHC) staining, Western blotting (WB) and the detection of superoxide anion (O2(-)·), hydrogen peroxide (H2O2), total iron, and ferric (Fe(3+)) levels were applied. ERG results showed the blue LED group induced more functional damage than that of green or red LED groups. H&E staining, TUNEL, IHC, and TEM revealed apoptosis and necrosis of photoreceptors and RPE, which indicated blue LED also induced more photochemical injury. Free radical production and iron-related molecular marker expressions demonstrated that oxidative stress and iron-overload were associated with retinal injury. WB assays correspondingly showed that defense gene expression was up-regulated after the LED light exposure with a wavelength dependency. The study results indicate that LED blue-light exposure poses a great risk of retinal injury in awake, task-oriented rod-dominant animals. The wavelength-dependent effect should be considered carefully when switching to LED lighting applications.

  8. The extragalactic background and its fluctuations in the far-infrared wavelengths

    CERN Document Server

    Lagache, G; Abergel, A; Bouchet, F R; Boulanger, F; Ciliegi, P; Clements, D L; Césarsky, C J; Désert, F X; Dole, H; Elbaz, D; Franceschini, A; Gispert, R; Guiderdoni, B; Haffner, L M; Harwit, M; Laureijs, R J; Lemke, D; Moorwood, A F M; Oliver, S; Reach, W T; Reynolds, R J; Rowan-Robinson, M; Stickel, M; Tufte, S L

    2000-01-01

    A Cosmic Far-InfraRed Background (CFIRB) has long been predicted that wouldtraces the intial phases of galaxy formation. It has been first detected byPuget et al.(1996) using COBE data and has been later confirmed by severalrecent studies (Fixsen et al. 1998, Hauser et al. 1998, Lagache et al. 1999).We will present a new determination of the CFIRB that uses for the first time,in addition to COBE data, two independent gas tracers: the HI survey ofLeiden/Dwingeloo (hartmann, 1998) and the WHAM H$_{\\alpha}$ survey (Reynolds etal 1998). We will see that the CFIRB above 100 micron is now very wellconstrained. The next step is to see if we can detect its fluctuations. Tosearch for the CFIRB fluctuations, we have used the FIRBACK observations.FIRBACK is a deep cosmological survey conducted at 170 micron with ISOPHOT(Dole et al., 2000). We show that the emission of unresolved extra-galacticsources clearly dominates, at arcminute scales, the background fluctuations inthe lowest galactic emission regions. This is the f...

  9. Integrated Wavelength-Tunable Light Source for Optical Gas Sensing Systems

    Directory of Open Access Journals (Sweden)

    Bin Li

    2015-01-01

    Full Text Available A compact instrument consisting of a distributed feedback laser (DFB at 1.65 μm was developed as a light source for gas sensing systems using tunable diode laser absorption spectroscopy (TDLAS technique. The wavelength of laser is tuned by adjusting the laser working temperature and injection current, which are performed by self-developed temperature controller and current modulator respectively. Stability test shows the fluctuation of the laser temperature is within the range of ±0.02°C. For gas detection experiments, the wavelength is tuned around the gas absorption line by adjusting laser temperature and is then shifted periodically to scan across the absorption line by the laser current modulator, which generates a 10 Hz saw wave signal. In addition, the current modulator is able to generate sine wave signal for gas sensing systems using wavelength modulation spectroscopy (WMS technique involving extraction of harmonic signals. The spectrum test proves good stability that the spectrum was measured 6 times every 10 minutes at the constant temperature and current condition. This standalone instrument can be applied as a light source for detection systems of different gases by integrating lasers at corresponding wavelength.

  10. Mid-IR fiber optic light source around 6 micron through parametric wavelength translation

    CERN Document Server

    Barh, A; Varshney, R K; Pal, B P; Sanghera, J; Shaw, L B; Aggarwal, I D

    2014-01-01

    We report numerically designed highly nonlinear all glass chalcogenide microstructured optical fiber for efficient generation of light around 6 micron through degenerate four wave mixing by considering continuous wave CO laser of 5 to 10 Watts power emitting at 5.6 micron as the pump. By tuning the pump wavelength, pump power, fiber dispersion and nonlinear properties, narrow and broad band mid-IR all-fiber light source could be realized. Parametric amplification of more than 20 decibel is achievable for the narrow band source at 6.46 micron with a maximum power conversion efficiency of 33 percent while amplification of 22 decibel is achievable for a B-band source over the wavelength range of 5 to 6.3 micron with a conversion efficiency of 40 percent.

  11. The 2010 Eruption of the Recurrent Nova U Scorpii: The Multi-Wavelength Light Curve

    CERN Document Server

    Pagnotta, Ashley; Clem, James L; Landolt, Arlo U; Handler, Gerald; Page, Kim L; Osborne, Julian P; Schlegel, Eric M; Hoffman, Douglas I; Kiyota, Seiichiro; Maehara, Hiroyuki

    2015-01-01

    The recurrent nova U Scorpii most recently erupted in 2010. Our collaboration observed the eruption in bands ranging from the Swift XRT and UVOT w2 (193 nm) to K-band (2200 nm), with a few serendipitous observations stretching down to WISE W2 (4600 nm). Considering the time and wavelength coverage, this is the most comprehensively observed nova eruption to date. We present here the resulting multi-wavelength light curve covering the two months of the eruption as well as a few months into quiescence. For the first time, a U Sco eruption has been followed all the way back to quiescence, leading to the discovery of new features in the light curve, including a second, as-yet-unexplained, plateau in the optical and near-infrared. Using this light curve we show that U Sco nearly fits the broken power law decline predicted by Hachisu & Kato, with decline indices of -1.71 +/- 0.02 and -3.36 +/- 0.14. With our unprecedented multi-wavelength coverage, we construct daily spectral energy distributions and then calcul...

  12. Easier detection of invertebrate "identification-key characters" with light of different wavelengths

    Directory of Open Access Journals (Sweden)

    Koken Marcel HM

    2011-10-01

    Full Text Available Abstract The marine α-taxonomist often encounters two problems. Firstly, the "environmental dirt" that is frequently present on the specimens and secondly the difficulty in distinguishing key-features due to the uniform colours which fixed animals often adopt. Here we show that illuminating animals with deep-blue or ultraviolet light instead of the normal white-light abrogates both difficulties; dirt disappears and important details become clearly visible. This light regime has also two other advantages. It allows easy detection of very small, normally invisible, animals (0.1 μm range. And as these light wavelengths can induce fluorescence, new identification markers may be discovered by this approach.

  13. Dual-wavelength light scattering for selective detection of volcanic ash particles

    Science.gov (United States)

    Jurányi, Z.; Burtscher, H.; Loepfe, M.; Nenkov, M.; Weingartner, E.

    2015-08-01

    A new method is presented in this paper which analyses the scattered light of individual aerosol particles simultaneously at two different wavelengths in order to retrieve information on the particle type. We show that dust-like particles, such as volcanic ash, can be unambiguously discriminated from water droplets on a single particle level. As a future application of this method, the detection of volcanic ash particles should be possible in a humid atmosphere in the presence of cloud droplets. We show an example, how the characteristic behaviour of pure water's refractive index can be used to separate water droplets and dust-like particles which are commonly found in the micrometer size-range in the ambient air. The low real part of the water's refractive index around 2700-2800 nm results in low scattered light intensities compared to e.g. the visible wavelength range and this feature can be used for the particle identification. The two-wavelength measurement setup was theoretically and experimentally tested and studied. Theoretical calculations were done using Mie theory. Comparing the ratio of the scattered light at the two wavelengths (R value) for water droplets and different dust types (basalt, andesite, African mineral dust, sand, volcanic ash, pumice) showed at least 9 times higher values (on average 70 times) for water droplets than for the dust types at any diameter within the particle size range of 2-20 μm. The envisaged measurement setup was built up into a laboratory prototype and was tested with different types of aerosols. We generated aerosols from the following powders simulating dust-like particles: cement dust, ISO 12103-1 A1 Ultrafine Test Dust and Ash from the 2012 eruption of the Etna volcano. Our measurements verified the theoretical considerations, the median experimental R value is 8-21 times higher for water than for the "dust" particles.

  14. Principles of stray light suppression and conceptual application to the design of the Diffuse Infrared Background Experiment for NASA's Cosmic Background Explorer

    Science.gov (United States)

    Evans, D. C.

    1983-01-01

    The Diffuse Infrared Background Experiment (DIRBE) is a 10 band filter photometer that will operate at superfluid helium temperatures. Diffuse galactic and extragalactic infrared radiation in the 1-300 micrometer wavelength region will be measured by the instrument. Polarization measurements will be made for 3 bands in the 1-4 micrometer spectral region. The main sources of unwanted radiation are the sun, earth, thermal radiation from an external sun shield, the moon, the brighter planets and stars, and sky light itself from outside the instrument's nominal one degree square field of view. The system level engineering concepts and the principles of stray light suppression that resulted in the instrument design are presented.

  15. Deep sub-wavelength nanofocusing of UV-visible light by hyperbolic metamaterials.

    Science.gov (United States)

    Kim, Minkyung; So, Sunae; Yao, Kan; Liu, Yongmin; Rho, Junsuk

    2016-12-07

    Confining light into a sub-wavelength area has been challenging due to the natural phenomenon of diffraction. In this paper, we report deep sub-wavelength focusing via dispersion engineering based on hyperbolic metamaterials. Hyperbolic metamaterials, which can be realized by alternating layers of metal and dielectric, are materials showing opposite signs of effective permittivity along the radial and the tangential direction. They can be designed to exhibit a nearly-flat open isofrequency curve originated from the large-negative permittivity in the radial direction and small-positive one in the tangential direction. Thanks to the ultraflat dispersion relation and curved geometry of the multilayer stack, hyperlens can magnify or demagnify an incident beam without diffraction depending on the incident direction. We numerically show that hyperlens-based nanofocusing device can compress a Gaussian beam down to tens-of-nanometers of spot size in the ultraviolet (UV) and visible frequency range. We also report four types of hyperlenses using different material combinations to span the entire range of visible frequencies. The nanofocusing device based on the hyperlens, unlike conventional lithography, works under ordinary light source without complex optics system, giving rise to practical applications including truly nanoscale lithography and deep sub-wavelength scale confinement.

  16. Background and Scattered-Light Subtraction in the High-Resolution Echelle Modes of the Space Telescope Imaging Spectrograph

    Science.gov (United States)

    Howk, J. Christopher; Sembach, Kenneth R.

    2000-05-01

    We present a simple, effective approach for estimating the on-order backgrounds of spectra taken with the highest resolution modes of the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope. Our scheme for determining the on-order background spectrum for STIS E140H and E230H observations uses moderate-order polynomial fits to the interorder scattered light visible in the two-dimensional STIS MAMA images. We present a suite of high-resolution STIS spectra to demonstrate that our background-subtraction routine produces the correct overall zero point as judged by the small residual flux levels in the centers of strongly saturated interstellar absorption lines. Although there are multiple sources of background light in STIS echelle mode data, this simple approach works very well for wavelengths longward of Lyα (λ>~1215 Å). At shorter wavelengths, the smaller order separation and generally lower signal-to-noise ratios of the data can reduce the effectiveness of our background estimation procedure. Slight artifacts in the background-subtracted spectrum can be seen in some cases, particularly at wavelengths of B2B and the GHRS first-order G160M observations of the early-type star HD 218915. We find no significant differences between the GHRS data and the STIS data reduced with our method in either case. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

  17. The extragalactic background light revisited and the cosmic photon-photon opacity

    Science.gov (United States)

    Franceschini, Alberto; Rodighiero, Giulia

    2017-07-01

    Context. In addition to its relevant astrophysical and cosmological significance, the extragalactic background light (EBL) is a fundamental source of opacity for cosmic high energy photons, as well as a limitation for the propagation of high-energy particles in the Universe. Aims: We review our previously published determinations of the EBL photon density in the Universe and its evolution with cosmic time, in the light of recent surveys of IR sources at long wavelengths. Methods: We exploit deep survey observations by the Herschel Space Observatory and the Spitzer telescope, matched to optical and near-IR photometric and spectroscopic data, to re-estimate number counts and luminosity functions longwards of a few microns, and the contribution of resolved sources to the EBL. Results: These new data indicate slightly lower photon densities in the mid- and far-infrared and sub-millimeter compared to previous determinations. This implies slightly lower cosmic opacity for photon-photon interactions. Conclusions: The new data do not modify previously published EBL modeling in the UV-optical and near-IR up to several microns, while reducing the photon density at longer wavelengths. This improved model of the EBL alleviates some tension that had emerged in the interpretation of the highest-energy TeV observations of local blazars, reducing the case for new physics beyond the standard model (like violations of the Lorenz Invariance, LIV, at the highest particle energies), or for exotic astrophysics, that had sometimes been called for to explain it. Applications of this improved EBL model on current data are considered, as well as perspectives for future instrumentation, the Cherenkov Telescope Array (CTA) in particular.

  18. Multiplexed Single-Mode Wavelength-to-Time Mapping of Multimode Light

    CERN Document Server

    Chandrasekharan, Harikumar K; Gris-Sánchez, Itandehui; Krstajić, Nikola; Walker, Richard; Bridle, Helen L; Dalgarno, Paul A; MacPherson, William N; Henderson, Robert K; Birks, Tim A; Thomson, Robert R

    2016-01-01

    We demonstrate that photonic lanterns based on tapered multicore fibres provide an efficient way to couple multimode states of light to a two-dimensional array of Single-Photon Avalanche Detectors (SPADs), each of which has its own Time-to-Digital Converter (TDC) for Time-Correlated Single-Photon-Counting (TCSPC). Exploiting this capability, we demonstrate multiplexed single-mode wavelength-to-time conversion of multimode states of light using a multicore-fibre photonic lantern with 121 single-mode cores, coupled in a one-to-one fashion to 121 SPADS on a 32 $\\times$ 32 pixel CMOS SPAD array. The application of photonic lanterns for coupling multimode light to SPAD arrays in this manner may find wide-ranging applications in areas such as Raman spectroscopy, coherent LIDAR and quantum optics.

  19. Performance study of wavelength shifting acrylic plastic for Cherenkov light detection

    Energy Technology Data Exchange (ETDEWEB)

    Beckford, B., E-mail: beckford@aps.org [American Physical Society, One Physics Ellipse, College Park, MD 20740 (United States); De la Puente, A. [TRIUMF Laboratory, 4004 Wesbrook Mall, Vancouver, BC, Canada V6T 2A3 (Canada); Fujii, Y.; Hashimoto, O.; Kaneta, M.; Kanda, H.; Maeda, K.; Matsumura, A.; Nakamura, S.N. [Department of Physics, Tohoku University, Sendai 980-8578 (Japan); Perez, N.; Reinhold, J. [Department of Physics, Florida International University, Miami, FL 33199 (United States); Tang, L. [Department of Physics, Hampton University, Hampton, VA 23668 (United States); Tsukada, K. [Department of Physics, Tohoku University, Sendai 980-8578 (Japan)

    2014-01-21

    The collection efficiency for Cherenkov light incident on a wavelength shifting plate (WLS) has been determined during a beam test at the Proton Synchrotron facility located in the National Laboratory for High Energy Physics (KEK), Tsukuba, Japan. The experiment was conducted in order to determine the detector's response to photoelectrons converted from photons produced by a fused silica radiator; this allows for an approximation of the detector's quality. The yield of the photoelectrons produced through internally generated Cherenkov light as well as light incident from the radiator was measured as a function of the momentum of the incident hadron beam. The yield is proportional to sin{sup 2}θ{sub c}, where θ{sub c} is the opening angle of the Cherenkov light created. Based on estimations and results from similar conducted tests, where the collection efficiency was roughly 39%, the experimental result was expected to be around 40% for internally produced light from the WLS. The results of the experiment determined the photon collection response efficiency of the WLS to be roughly 62% for photons created in a fused silica radiator and 41% for light created in the WLS.

  20. Pigment-targeted light wavelength and intensity promotes efficient photoautotrophic growth of Cyanobacteria.

    Science.gov (United States)

    Bland, Erik; Angenent, Largus T

    2016-09-01

    A consensus is lacking whether monochromatic rather than broad-spectrum illumination is more efficient for photosynthetic microbe production platforms. Light wavelength and intensity were tuned to pigment composition for growth of the Cyanobacterium Synechocystis PCC 6803. Phycocyanin (PC)-targeting LEDs (620nm) provided more than 6times the peak efficiency of white LEDs, with peak efficiency growth rates of 0.063h(-1) at 81μEm(-2)s(-1) and 0.039h(-1) at 126μEm(-2)s(-1) for red and white LEDs, respectively. Chlorophyll a (Chl a)-targeting LEDs (680- and 440-nm) performed poorly. Indeed, 10 times greater mass abundance was observed for PC than Chl a. PC levels did not change while Chl a levels decreased when Synechocystis transitioned from white light at 50μEm(-2)s(-1) to 250μEm(-2)s(-1) with 620nm, 680nm, or white LEDs. This work demonstrates that light wavelengths and intensity need to be optimized for each strain.

  1. Photodecomposition of tetrabromobisphenol A in aqueous humic acid suspension by irradiation with light of various wavelengths.

    Science.gov (United States)

    Han, Sang Kuk; Yamasaki, Toshihide; Yamada, Ken-ichi

    2016-03-01

    The reactive species generated in aqueous 3,3',5,5'-tetrabromobisphenol A (TBBPA)/humic acid (HA) suspensions above the TBBPA pKa (∼7.4), under various light-irradiation conditions, namely ambient and ultraviolet light, were investigated using electron paramagnetic resonance (EPR) spectroscopy and liquid chromatography-mass spectrometry (LC-MS). We confirmed that singlet oxygen and OH radicals are the key reactive oxygen species generated at wavelengths greater than 400 and 300 nm, respectively. The amount of 2,6-dibromo-p-benzosemiquinone anion radicals (2,6-DBSQ(•-)) formed under irradiation at 400 nm increased linearly with respect to irradiation time; the initial reaction rate was 7.03 × 10(-9) mol g(-1) HA s(-1). The rate increased with increasing pH and light intensity. LC-MS and EPR spectroscopy showed that tribromohydroxybisphenol A was formed under irradiation at 300 nm via reaction of OH radicals with TBBPA. This study, for the first time, shows that the main byproducts formed during irradiation at wavelengths above 300 nm are 2,6-DBSQ(•-) and tribromohydroxybisphenol A, generated from singlet oxygen ((1)O2) and OH radicals, respectively. Photodecomposition of TBBPA in the environment may occur by formation of (1)O2 and OH radicals.

  2. Room temperature all-silicon photonic crystal nanocavity light emitting diode at sub-bandgap wavelengths

    CERN Document Server

    Shakoor, A; Cardile, P; Portalupi, S L; Gerace, D; Welna, K; Boninelli, S; Franzo, G; Priolo, F; Krauss, T F; Galli, M; Faolain, L O

    2013-01-01

    Silicon is now firmly established as a high performance photonic material. Its only weakness is the lack of a native electrically driven light emitter that operates CW at room temperature, exhibits a narrow linewidth in the technologically important 1300- 1600 nm wavelength window, is small and operates with low power consumption. Here, an electrically pumped all-silicon nano light source around 1300-1600 nm range is demonstrated at room temperature. Using hydrogen plasma treatment, nano-scale optically active defects are introduced into silicon, which then feed the photonic crystal nanocavity to enahnce the electrically driven emission in a device via Purcell effect. A narrow ({\\Delta}{\\lambda} = 0.5 nm) emission line at 1515 nm wavelength with a power density of 0.4 mW/cm2 is observed, which represents the highest spectral power density ever reported from any silicon emitter. A number of possible improvements are also discussed, that make this scheme a very promising light source for optical interconnects a...

  3. The Cosmic Infrared Background Experiment (CIBER): A Sounding Rocket Payload to Study the Near Infrared Extragalactic Background Light

    CERN Document Server

    Zemcov, M; Battle, J; Bock, J; Cooray, A; Hristov, V; Keating, B; Kim, M G; Lee, D H; Levenson, L R; Mason, P; Matsumoto, T; Matsuura, S; Nam, U W; Renbarger, T; Sullivan, I; Suzuki, K; Tsumura, K; Wada, T

    2011-01-01

    The Cosmic Infrared Background Experiment (CIBER) is a suite of four instruments designed to study the near infrared (IR) background light from above the Earth's atmosphere. The instrument package comprises two imaging telescopes designed to characterize spatial anisotropy in the extragalactic IR background caused by cosmological structure during the epoch of reionization, a low resolution spectrometer to measure the absolute spectrum of the extragalactic IR background, and a narrow band spectrometer optimized to measure the absolute brightness of the Zodiacal light foreground. In this paper we describe the design and characterization of the CIBER payload. The detailed mechanical, cryogenic, and electrical design of the system are presented, including all system components common to the four instruments. We present the methods and equipment used to characterize the instruments before and after flight, and give a detailed description of CIBER's flight profile and configurations. CIBER is designed to be recover...

  4. Wavelength-Tunable Electroluminescent Light Sources from Individual Ga-Doped ZnO Microwires.

    Science.gov (United States)

    Jiang, Mingming; He, Gaohang; Chen, Hongyu; Zhang, Zhenzhong; Zheng, Lingxia; Shan, Chongxin; Shen, Dezhen; Fang, Xiaosheng

    2017-03-07

    Electrically driven wavelength-tunable light emission from biased individual Ga-doped ZnO microwires (ZnO:Ga MWs) is demonstrated. Single crystalline ZnO:Ga MWs with different Ga-doping concentrations have been synthesized using a one-step chemical vapor deposition method. Strong electrically driven light emission from individual ZnO:Ga MW based devices is realized with tunable colors, and the emission region is localized toward the center of the wires. Increasing Ga-doping concentration in the MWs can lead to the redshift of electroluminescent emissions in the visible range. Interestingly, owing to the lack of rectification characteristics, relevant electrical measurement results show that the alternating current-driven light emission functions excellently on the ZnO:Ga MWs. Consequently, individual ZnO:Ga MWs, which can be analogous to incandescent sources, offer unique possibilities for future electroluminescence light sources. This typical multicolor emitter can be used to rival and complement other conventional semiconductor devices in displays and lighting.

  5. Intermittent long-wavelength red light increases the period of daily locomotor activity in mice

    Directory of Open Access Journals (Sweden)

    Hughes Amanda M

    2005-05-01

    Full Text Available Abstract Background We observed that a dim, red light-emitting diode (LED triggered by activity increased the circadian periods of lab mice compared to constant darkness. It is known that the circadian period of rats increases when vigorous wheel-running triggers full-spectrum lighting; however, spectral sensitivity of photoreceptors in mice suggests little or no response to red light. Thus, we decided to test the following hypotheses: dim red light illumination triggered by activity (LEDfb increases the circadian period of mice compared to constant dark (DD; covering the LED prevents the effect on period; and DBA2/J mice have a different response to LEDfb than C57BL6/J mice. Methods The irradiance spectra of the LEDs were determined by spectrophotometer. Locomotor activity of C57BL/6J and DBA/2J mice was monitored by passive-infrared sensors and circadian period was calculated from the last 10 days under each light condition. For constant dark (DD, LEDs were switched off. For LED feedback (LEDfb, the red LED came on when the mouse was active and switched off seconds after activity stopped. For taped LED the red LED was switched on but covered with black tape. Single and multifactorial ANOVAs and post-hoc t-tests were done. Results The circadian period of mice was longer under LEDfb than under DD. Blocking the light eliminated the effect. There was no difference in period change in response to LEDfb between C57BL/6 and DBA/2 mice. Conclusion An increase in mouse circadian period due to dim far-red light (1 lux at 652 nm exposure was unexpected. Since blocking the light stopped the response, sound from the sensor's electronics was not the impetus of the response. The results suggest that red light as background illumination should be avoided, and indicator diodes on passive infrared motion sensors should be switched off.

  6. All-Dielectric Antenna Wavelength Router with Bidirectional Scattering of Visible Light.

    Science.gov (United States)

    Li, Jiaqi; Verellen, Niels; Vercruysse, Dries; Bearda, Twan; Lagae, Liesbet; Van Dorpe, Pol

    2016-07-13

    An optical antenna forms the subwavelength bridge between free space optical radiation and localized electromagnetic energy. Its localized electromagnetic modes strongly depend on its geometry and material composition. Here, we present the design and experimental realization of a novel V-shaped all-dielectric antenna based on high-index amorphous silicon with a strong magnetic dipole resonance in the visible range. As a result, it exhibits extraordinary bidirectional scattering into diametrically opposite directions. The scattering direction is effectively controlled by the incident wavelength, rendering the antenna a passive bidirectional wavelength router. A detailed multipole decomposition analysis reveals that the excitation and abrupt phase change of an out-of-plane polarized magnetic dipole and an in-plane electric quadrupole are essential for the directivity switching. Previously, noble metals have been extensively exploited for plasmonic directional nanoantenna design. However, these inevitably suffer from high intrinsic ohmic losses and a relatively weak magnetic response to the incident light. Compared to a similar gold plasmonic nanoantenna design, we show that the silicon-based antennas demonstrate stronger magnetic scattering with minimal absorption losses. Our results indicate that all-dielectric antennas will open exciting possibilities for efficient manipulation of light-matter interactions.

  7. Effect of light wavelength on motility and magnetic sensibility of the magnetotactic multicellular prokaryote 'Candidatus Magnetoglobus multicellularis'.

    Science.gov (United States)

    de Azevedo, Lyvia Vidinho; de Barros, Henrique Lins; Keim, Carolina Neumann; Acosta-Avalos, Daniel

    2013-09-01

    'Candidatus Magnetoglobus multicellularis' is a magnetotactic microorganism composed of several bacterial cells. Presently, it is the best known multicellular magnetotactic prokaryote (MMP). Recently, it has been observed that MMPs present a negative photoresponse to high intensity ultraviolet and violet-blue light. In this work, we studied the movement of 'Candidatus Magnetoglobus multicellularis' under low intensity light of different wavelengths, measuring the average velocity and the time to reorient its trajectory when the external magnetic field changes its direction (U-turn time). Our results show that the mean average velocity is higher for red light (628 nm) and lower for green light (517 nm) as compared to yellow (596 nm) and blue (469 nm) light, and the U-turn time decreased for green light illumination. The light wavelength velocity dependence can be understood as variation in flagella rotation speed, being increased by the red light and decreased by the green light relative to yellow and blue light. It is suggested that the dependence of the U-turn time on light wavelength can be considered a form of light-dependent magnetotaxis, because this time represents the magnetic sensibility of the magnetotactic microorganisms. The cellular and molecular mechanisms for this light-dependent velocity and magnetotaxis are unknown and deserve further studies to understand the biochemical interactions and the ecological roles of the different mechanisms of taxis in MMPs.

  8. Study on the color merging of white light and transmission properties of wavelength division multiplexing visible light communication system based on RGB light-emitting diodes

    Science.gov (United States)

    Wang, Guangye; Gao, Yingming; Wang, Jinpeng; Chen, Ailin; Li, Ping; Zou, Nianyu

    2016-10-01

    Visible light communication (VLC) systems have an advantage for simultaneously achieving communication and illumination. To strengthen the performance of VLC by using RGB light-emitting diodes (LEDs) while meeting the lighting requirements, the channel capacity and the transmission capability of the system are improved by utilizing the wavelength division multiplexing (WDM) technology. We make the chromaticity of the merged white light suitable for human eyes by the experiment. The parameters of merged white light based on RGB LEDs and the merging ratio data measured by the experiment are given. Hence, we study and analyze the eye diagrams and bit error rate (BER) of different optical channels. The simulation results show that maximum transmission rate of the output signal is up to 3.3 Gbit/s, and the BER is less than 10-5 with a transmission distance of 2.5 m while meeting standard illumination requirements.

  9. Modular sub-wavelength diffractive light modulator for high-definition holographic displays

    Science.gov (United States)

    Stahl, Richard; Rochus, Veronique; Rottenberg, Xavier; Cosemans, Stefan; Haspeslagh, Luc; Severi, Simone; Van der Plas, Geert; Lafruit, Gauthier; Donnay, Stephane

    2013-02-01

    Holography is undoubtedly the ultimate 3D visualization technology, offering true 3D experience with all the natural depth cues, without the undesirable side-effects of current stereoscopic systems (uncomfortable glasses, strained eyes, fatiguing experience). Realization of a high-definition holographic display however requires a number of breakthroughs from existing prototypes. One of the main challenges lies in technology scaling, as holography is based on light diffraction and interference - to achieve wide viewing angles, the light-modulating pixels need to be spaced close to or below the wavelength of the used visible light. Furthermore, achieving high 3D image quality, hundreds of millions of such individually programmable pixels are needed. As a solution, we develop a modular sub-wavelength light modulator, consisting of three main sub-systems: the optical sub-system, comprising a 2D array of sub-wavelength pixels; the driver sub-system for individual pixel control, and the holographic computational engine. Based on conclusions from our state-of-the art studies, numerous experiments and holographic demonstrators, we have focused on reflective phase-modulating MEMS-based system and its scaling beyond 500nm pitch. We have devised a unique binary-programmable phase-modulating pixel architecture realizing vertical pixel displacement of up to 150nm at 500nm by 500nm pixel pitch, while sustaining low operating voltages compatible with CMOS driver circuitry. IMEC SiGe MEMS technology enables integration of the CMOS pixel-line drivers, scan-line drivers and I/O circuits underneath the 2D MEMS array, resulting in a compact and modular single-chip system design. Refresh rates of few hundred frames per second are achieved using our patented segmented driver-array architecture. Integrated circuits implementing parallel holographic computational engines can be added to the module using advanced 3D stacking technology. Herein we further report on our progress in realizing

  10. Effect of different light wavelengths on the growth and ochratoxin A production in Aspergillus carbonarius and Aspergillus westerdijkiae.

    Science.gov (United States)

    Cheong, Khai Khuang; Strub, Caroline; Montet, Didier; Durand, Noël; Alter, Pascaline; Meile, Jean-Christophe; Schorr Galindo, Sabine; Fontana, Angélique

    2016-05-01

    The effects of light at different wavelengths and photoperiod on growth and ochratoxin A production of Aspergillus carbonarius and Aspergillus westerdijkiae were studied: far-red (740 nm), red (625 nm), blue (445 nm), and UV-A (366 nm). Fungal growth was not significantly affected by photoperiod or light wavelength; the only exception was A. westerdijkiae which showed reduced growth under UV-A light (366 nm). Short-wavelength blue light (445 nm) and UV-A light caused a reduction in ochratoxin A production of both fungal species. However, long-wavelength red light (625 nm) and far-red light (740 nm) reduced ochratoxin A production only in A. westerdijkiae but not in A. carbonarius. It is believed that this difference in reactivity to light is due to differences in the melanin content of the two fungal species: A. carbonarius is a black fungus with higher melanin content than A. westerdijkiae, a yellow fungus. Other possible explanations for the reduction of ochratoxin A production by light were also discussed.

  11. Measurements of the anisotropy of the cosmic background radiation and diffuse galactic emission at millimeter and submillimeter wavelengths

    Science.gov (United States)

    Halpern, Mark; Benford, Richard; Meyer, Stephan; Muehlner, Dirk; Weiss, Rainer

    1988-01-01

    The results of a balloon-borne observing program to measure the large angular scale brightness distribution of the 2.7 K cosmic background radiation (CBR) at millimeter and submillimeter wavelengths are reported. A new determination of the dipole anisotropy of the CBR is found with 3.40 + or - 0.42 mK toward alpha = 12.1 + or - 0.24 hr, delta = - 23 + or - 5 deg in a 1.2 to 8/cm band and 4.7 + or - 1.4 mK toward alpha = 9.9 + 1.7 or - 1.1 hr, delta = - 38 + or - 21 deg between 5 and 18/cm, where the amplitudes are listed as thermodynamic temperatures. New estimates of the absolute temperature in these two bands of 2.86 + or - 0.26 K and 3.01 + or - 0.31 are obtained under the assumption that the CBR has a Planck spectrum. The diffuse Galactic emission is fitted by a secant distribution in Galactic latitude, and the resulting Galactic pole antenna temperatures are given. Maps of sky brightness, measurements of zodiacal emission, and measurements of fluctuations of the atmospheric emission which dominates the noise budget are also presented.

  12. Treatment of attention deficit hyperactivity disorder insomnia with blue wavelength light-blocking glasses

    Directory of Open Access Journals (Sweden)

    Fargason RE

    2013-01-01

    Full Text Available Rachel E Fargason, Taylor Preston, Emily Hammond, Roberta May, Karen L GambleDepartment of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham School of Medicine, Birmingham, AL, USABackground: The aim of this study was to examine a nonmedical treatment alternative to medication in attention deficit hyperactivity disorder (ADHD insomnia, in which blue wavelength light-blocking glasses are worn during the evening hours to counteract the phase-delaying effect of light. Outcome measures included sleep quality and midsleep time. The capacity of ADHD subjects to comply with treatment using the glasses was assessed.Methods: Daily bedtime, wake-up time, and compliance diaries were used to assess sleep quality and timing during a baseline observation week and a 2-week intervention period. The Pittsburgh Sleep Quality Index (PSQI was administered following baseline and intervention. The intervention protocol consisted of use of blue wavelength-blocking glasses and a moderate lighting environment during evening hours.Results: Partial and variable compliance were noted, with only 14 of 22 subjects completing the study due to nonadherence with wearing the glasses and diary completion. Despite the minimum 3-hour recommendation, glasses were worn, on average, for 2.4 hours daily. Lighting was reduced for only 58.7% of the evening. Compared with baseline, the intervention resulted in significant improvement in global PSQI scores, PSQI subcomponent scores, and sleep diary measures of morning refreshment after sleep (P = 0.037 and night-time awakenings (P = 0.015. Global PSQI scores fell from 11.15 to 4.54, dropping below the cut-off score of 5 for clinical insomnia. The more phase-delayed subjects, ie, those with an initial midsleep time after 4:15 am, trended towards an earlier midsleep time by 43.2 minutes following the intervention (P = 0.073. Participants reported less anxiety following the intervention (P = 0.048.Conclusions

  13. Red Light-Dose or Wavelength-Dependent Photoresponse of Antioxidants in Herb Microgreens

    Science.gov (United States)

    Samuolienė, Giedė; Brazaitytė, Aušra; Viršilė, Akvilė; Jankauskienė, Julė; Sakalauskienė, Sandra; Duchovskis, Pavelas

    2016-01-01

    The purpose of this study was to evaluate the role of 638-nm and 665-nm LEDs on changes of antioxidants of basil (Ocimum basilicum) and parsley (Petroselinum crispum), and to assess the effect of light quality on antioxidative status. Plants were grown in peat substrate for 19 days (21/17 ±2°C, 16 h). Experiments were performed in (I) a controlled-environment: B455,R638,R665,FR731(control); B455,R*638,R665,FR731; B455,R638,R*665,FR731; R638; R665 (B–blue, R- red, FR–far-red light). PPFD was set from 231 during growth, upto 300 μmol m-2 s-1 during 3-day treatment changing R638 or R665 PPFD level; in (II) greenhouse (November): high-pressure sodium lamps (HPS) (control—300 μmol m−2s−1); and HPS + 638 (HPS generated 90 and red LEDs—210 μmol m−2s−1). In general, under supplemental or increased red 638 nm light, amounts of tested antioxidants were greater in basil, whereas sole 665 nm or sole 638 nm is more favourable for parsley. Increased or supplemental red light significantly increased contents of phenolics, α-tocopherol, ascorbic acid and DPPH• but suppressed accumulation of lutein and β-carotene in basil, whereas an increase of β-carotene and DPPH• was observed in parsley. Hereby, the photoresponse of antioxidant compounds suggests that photoprotective mechanism is stimulated by both light-dose-dependent and wavelength-dependent reactions. PMID:27677090

  14. The discrete dipole approximation for simulation of light scattering by particles much larger than the wavelength

    CERN Document Server

    Yurkin, Maxim A; Hoekstra, Alfons G

    2007-01-01

    In this manuscript we investigate the capabilities of the Discrete Dipole Approximation (DDA) to simulate scattering from particles that are much larger than the wavelength of the incident light, and describe an optimized publicly available DDA computer program that processes the large number of dipoles required for such simulations. Numerical simulations of light scattering by spheres with size parameters x up to 160 and 40 for refractive index m=1.05 and 2 respectively are presented and compared with exact results of the Mie theory. Errors of both integral and angle-resolved scattering quantities generally increase with m and show no systematic dependence on x. Computational times increase steeply with both x and m, reaching values of more than 2 weeks on a cluster of 64 processors. The main distinctive feature of the computer program is the ability to parallelize a single DDA simulation over a cluster of computers, which allows it to simulate light scattering by very large particles, like the ones that are...

  15. Characterization of Plant Growth under Single-Wavelength Laser Light Using the Model Plant Arabidopsis Thaliana

    KAUST Repository

    Ooi, Amanda

    2016-12-01

    Indoor horticulture offers a promising solution for sustainable food production and is becoming increasingly widespread. However, it incurs high energy and cost due to the use of artificial lighting such as high-pressure sodium lamps, fluorescent light or increasingly, the light-emitting diodes (LEDs). The energy efficiency and light quality of currently available lighting is suboptimal, therefore less than ideal for sustainable and cost-effective large-scale plant production. Here, we demonstrate the use of high-powered single-wavelength lasers for indoor horticulture. Lasers are highly energy-efficient and can be remotely guided to the site of plant growth, thus reducing on-site heat accumulation. Besides, laser beams can be tailored to match the absorption profiles of different plants. We have developed a prototype laser growth chamber and demonstrate that laser-grown plants can complete a full growth cycle from seed to seed with phenotypes resembling those of plants grown under LEDs. Importantly, the plants have lower expression of proteins diagnostic for light and radiation stress. The phenotypical, biochemical and proteomic data show that the singlewavelength laser light is suitable for plant growth and therefore, potentially able to unlock the advantages of this next generation lighting technology for highly energy-efficient horticulture. Furthermore, stomatal movement partly determines the plant productivity and stress management. Abscisic acid (ABA) induces stomatal closure by promoting net K+-efflux from guard cells through outwardrectifying K+ (K+ out) channels to regulate plant water homeostasis. Here, we show that the Arabidopsis thaliana guard cell outward-rectifying K+ (ATGORK) channel is a direct target for ABA in the regulation of stomatal aperture and hence gas exchange and transpiration. Addition of (±)-ABA, but not the biologically inactive (−)-isomer, increases K+ out channel activity in Vicia faba guard cell protoplast. A similar ABA

  16. At-wavelength metrology of x-ray optics at Diamond Light Source

    Science.gov (United States)

    Wang, Hongchang; Berujon, Sebastien; Sutter, John; Alcock, Simon G.; Sawhney, Kawal

    2014-09-01

    Modern, third-generation synchrotron radiation sources provide coherent and extremely bright beams of X-ray radiation. The successful exploitation of such beams depends to a significant extent on imperfections and misalignment of the optics employed on the beamlines. This issue becomes even more critical with the increasing use of active optics, and the desire to achieve diffraction-limited and coherence-preserving X-ray beams. In recent years, significant progress has been made to improve optic testing and optimization techniques, especially those using X-rays for so-called atwavelength metrology. These in-situ and at-wavelength metrology methods can be used not only to optimize the performance of X-ray optics, but also to correct and minimize the collective distortions of upstream beamline optics, including monochromators, and transmission windows. An overview of at-wavelength metrology techniques implemented at Diamond Light Source is presented, including grating interferometry and X-ray near-field speckle based techniques. Representative examples of the application of these techniques are also given, including in-situ and atwavelength calibration and optimization of: active, piezo bimorph mirrors; Kirkpatrick-Baez (KB) mirrors; and refractive optics such as compound refractive lenses.

  17. Study of the Dependence of Photoenhanced Nonlinear Acoustic Surface Wave Interactions on the Wavelength of Light.

    Science.gov (United States)

    1977-05-10

    CenterRockwell International SC5027.4FR 5.0 APPEND IX a) Participating Sci enti fic Personnel: Dr. Edgar A. Kraut Dr. T. C. Lim Mr. Fran k J. Morin Mr. John...Research Triangle Park, North Carolina 27709 JUN 23 19fl _ / L~. Co-Inve stigators F— 0 . Edgar A. Kraut Dr. Te g C. Lim ___________ 4nr...INTERACTIONS ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ON THE WAVELENGTH OF LIGHT~ I sc~o~i.~ p. /7 QR(a,) ~~~~~O~~TRA~~’T O R GRA NT NUMBER(S) Dr. Edgar A

  18. Group III nitride semiconductors for short wavelength light-emitting devices

    Science.gov (United States)

    Orton, J. W.; Foxon, C. T.

    1998-01-01

    The group III nitrides (AlN, GaN and InN) represent an important trio of semiconductors because of their direct band gaps which span the range 1.95-6.2 eV, including the whole of the visible region and extending well out into the ultraviolet (UV) range. They form a complete series of ternary alloys which, in principle, makes available any band gap within this range and the fact that they also generate efficient luminescence has been the main driving force for their recent technological development. High brightness visible light-emitting diodes (LEDs) are now commercially available, a development which has transformed the market for LED-based full colour displays and which has opened the way to many other applications, such as in traffic lights and efficient low voltage, flat panel white light sources. Continuously operating UV laser diodes have also been demonstrated in the laboratory, exciting tremendous interest for high-density optical storage systems, UV lithography and projection displays. In a remarkably short space of time, the nitrides have therefore caught up with and, in some ways, surpassed the wide band gap II-VI compounds (ZnCdSSe) as materials for short wavelength optoelectronic devices. The purpose of this paper is to review these developments and to provide essential background material in the form of the structural, electronic and optical properties of the nitrides, relevant to these applications. We have been guided by the fact that the devices so far available are based on the binary compound GaN (which is relatively well developed at the present time), together with the ternary alloys AlGaN and InGaN, containing modest amounts of Al or In. We therefore concentrate, to a considerable extent, on the properties of GaN, then introduce those of the alloys as appropriate, emphasizing their use in the formation of the heterostructures employed in devices. The nitrides crystallize preferentially in the hexagonal wurtzite structure and devices have so

  19. The Cosmic Infrared Background Experiment (CIBER): A Sounding Rocket Payload to Study the near Infrared Extragalactic Background Light

    Science.gov (United States)

    Zemcov, M.; Arai, T.; Battle, J.; Bock, J.; Cooray, A.; Hristov, V.; Keating, B.; Kim, M. G.; Lee, D. H.; Levenson, L. R.; Mason, P.; Matsumoto, T.; Matsuura, S.; Nam, U. W.; Renbarger, T.; Sullivan, I.; Suzuki, K.; Tsumura, K.; Wada, T.

    2013-08-01

    The Cosmic Infrared Background Experiment (CIBER) is a suite of four instruments designed to study the near infrared (IR) background light from above the Earth's atmosphere. The instrument package comprises two imaging telescopes designed to characterize spatial anisotropy in the extragalactic IR background caused by cosmological structure during the epoch of reionization, a low resolution spectrometer to measure the absolute spectrum of the extragalactic IR background, and a narrow band spectrometer optimized to measure the absolute brightness of the zodiacal light foreground. In this paper we describe the design and characterization of the CIBER payload. The detailed mechanical, cryogenic, and electrical design of the system are presented, including all system components common to the four instruments. We present the methods and equipment used to characterize the instruments before and after flight, and give a detailed description of CIBER's flight profile and configurations. CIBER is designed to be recoverable and has flown four times, with modifications to the payload having been informed by analysis of the first flight data. All four instruments performed to specifications during the subsequent flights, and the scientific data from these flights are currently being analyzed.

  20. THE COSMIC INFRARED BACKGROUND EXPERIMENT (CIBER): A SOUNDING ROCKET PAYLOAD TO STUDY THE NEAR INFRARED EXTRAGALACTIC BACKGROUND LIGHT

    Energy Technology Data Exchange (ETDEWEB)

    Zemcov, M.; Bock, J.; Hristov, V.; Levenson, L. R.; Mason, P. [Department of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Arai, T.; Matsumoto, T.; Matsuura, S.; Tsumura, K.; Wada, T. [Department of Space Astronomy and Astrophysics, Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara, Kanagawa 252-5210 (Japan); Battle, J. [Jet Propulsion Laboratory (JPL), National Aeronautics and Space Administration (NASA), Pasadena, CA 91109 (United States); Cooray, A. [Center for Cosmology, University of California, Irvine, Irvine, CA 92697 (United States); Keating, B.; Renbarger, T. [Department of Physics, University of California, San Diego, San Diego, CA 92093 (United States); Kim, M. G. [Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Lee, D. H.; Nam, U. W. [Korea Astronomy and Space Science Institute (KASI), Daejeon 305-348 (Korea, Republic of); Sullivan, I. [Department of Physics, The University of Washington, Seattle, WA 98195 (United States); Suzuki, K., E-mail: zemcov@caltech.edu [Instrument Development Group of Technical Center, Nagoya University, Nagoya, Aichi 464-8602 (Japan)

    2013-08-15

    The Cosmic Infrared Background Experiment (CIBER) is a suite of four instruments designed to study the near infrared (IR) background light from above the Earth's atmosphere. The instrument package comprises two imaging telescopes designed to characterize spatial anisotropy in the extragalactic IR background caused by cosmological structure during the epoch of reionization, a low resolution spectrometer to measure the absolute spectrum of the extragalactic IR background, and a narrow band spectrometer optimized to measure the absolute brightness of the zodiacal light foreground. In this paper we describe the design and characterization of the CIBER payload. The detailed mechanical, cryogenic, and electrical design of the system are presented, including all system components common to the four instruments. We present the methods and equipment used to characterize the instruments before and after flight, and give a detailed description of CIBER's flight profile and configurations. CIBER is designed to be recoverable and has flown four times, with modifications to the payload having been informed by analysis of the first flight data. All four instruments performed to specifications during the subsequent flights, and the scientific data from these flights are currently being analyzed.

  1. Toxicity of Chlorophyllin against Lymnaea acuminata at Different Wavelengths of Visible Light.

    Science.gov (United States)

    Chaturvedi, Divya; Singh, Vinay Kumar

    2016-08-01

    Fasciolosis is a water and food-borne disease caused by the liver fluke Fasciola hepatica and Fasciola gigantica. This disease is widespread in different parts of the world. Lymnaeidae and Planorbidae snails are the intermediate hosts of these flukes. Snail population management is a good tool to control fasciolosis because gastropods represent the weakest link in the life-cycle of trematodes. Chlorophyll can be extracted from any green plant. Chlorophyllin was prepared from spinach in 100% ethanol by using different types of chemicals. The chlorophyll obtained from spinach was transformed into water-soluble chlorophyllin. In the present paper, toxicity of chlorophyllin against the snail Lymnaea acuminata was time and concentration dependent. The toxicity of extracted and pure chlorophyllin at continuous 4 h exposure of sunlight was highest with lethal concentration (LC50) of 331.01 mg/L and 2.60 mg/L, respectively, than discontinuous exposure of sunlight up to 8 h with LC50 of 357.04 mg/L and 4.94 mg/L, respectively. Toxicity of extracted chlorophyllin was noted in the presence of different monochromatic visible lights. The highest toxicity was noted in yellow light (96 h, LC50 392.77 mg/L) and the lowest in green light (96 h, LC50 833.02 mg/L). Chlorophyllin in combination with solar radiation or different wavelength of monochromatic visible lights may become a latent remedy against the snail L. acuminata. It was demonstrated that chlorophyllin was more toxic in sunlight. Chlorophyllin is ecologically safe and more economical than synthetic molluscicides which have the potential to control the incidence of fasciolosis in developing countries.

  2. Toxicity of Chlorophyllin against Lymnaea acuminata at Different Wavelengths of Visible Light

    Science.gov (United States)

    Chaturvedi, Divya; Singh, Vinay Kumar

    2016-01-01

    Fasciolosis is a water and food-borne disease caused by the liver fluke Fasciola hepatica and Fasciola gigantica. This disease is widespread in different parts of the world. Lymnaeidae and Planorbidae snails are the intermediate hosts of these flukes. Snail population management is a good tool to control fasciolosis because gastropods represent the weakest link in the life-cycle of trematodes. Chlorophyll can be extracted from any green plant. Chlorophyllin was prepared from spinach in 100% ethanol by using different types of chemicals. The chlorophyll obtained from spinach was transformed into water-soluble chlorophyllin. In the present paper, toxicity of chlorophyllin against the snail Lymnaea acuminata was time and concentration dependent. The toxicity of extracted and pure chlorophyllin at continuous 4 h exposure of sunlight was highest with lethal concentration (LC50) of 331.01 mg/L and 2.60 mg/L, respectively, than discontinuous exposure of sunlight up to 8 h with LC50 of 357.04 mg/L and 4.94 mg/L, respectively. Toxicity of extracted chlorophyllin was noted in the presence of different monochromatic visible lights. The highest toxicity was noted in yellow light (96 h, LC50 392.77 mg/L) and the lowest in green light (96 h, LC50 833.02 mg/L). Chlorophyllin in combination with solar radiation or different wavelength of monochromatic visible lights may become a latent remedy against the snail L. acuminata. It was demonstrated that chlorophyllin was more toxic in sunlight. Chlorophyllin is ecologically safe and more economical than synthetic molluscicides which have the potential to control the incidence of fasciolosis in developing countries. PMID:27688849

  3. Deep modulation of second-harmonic light by wavelength detuning of a laser diode

    DEFF Research Database (Denmark)

    Christensen, Mathias; Hansen, Anders Kragh; Noordegraaf, Danny

    2017-01-01

    Power modulated visible lasers are interesting for a number of applications within areas such as laser displays and medical laser treatments. In this paper, we present a system for modulating the second-harmonic light generated by single-pass frequency doubling of a distributed feedback (DFB) mas....... The bandwidth of the modulation is limited by the electronics. This method has the potential to decrease the size as well as cost of modulated visible lasers. The achievable optical powers will increase as DFB MOPAs are further developed. (C) 2017 Optical Society of America......Power modulated visible lasers are interesting for a number of applications within areas such as laser displays and medical laser treatments. In this paper, we present a system for modulating the second-harmonic light generated by single-pass frequency doubling of a distributed feedback (DFB......) master oscillator power amplifier (MOPA) laser diode with separate electrical contacts for the MO and the PA. A modulation depth in excess of 97% from 0.1 Hz to 10 kHz is demonstrated. This is done by wavelength tuning of the laser diode using only a 40 mA adjustment of the current through the MO...

  4. Wavelength-scale light concentrator made by direct 3D laser writing of polymer metamaterials

    Science.gov (United States)

    Moughames, J.; Jradi, S.; Chan, T. M.; Akil, S.; Battie, Y.; Naciri, A. En; Herro, Z.; Guenneau, S.; Enoch, S.; Joly, L.; Cousin, J.; Bruyant, A.

    2016-10-01

    We report on the realization of functional infrared light concentrators based on a thick layer of air-polymer metamaterial with controlled pore size gradients. The design features an optimum gradient index profile leading to light focusing in the Fresnel zone of the structures for two selected operating wavelength domains near 5.6 and 10.4 μm. The metamaterial which consists in a thick polymer containing air holes with diameters ranging from λ/20 to λ/8 is made using a 3D lithography technique based on the two-photon polymerization of a homemade photopolymer. Infrared imaging of the structures reveals a tight focusing for both structures with a maximum local intensity increase by a factor of 2.5 for a concentrator volume of 1.5 λ3, slightly limited by the residual absorption of the selected polymer. Such porous and flat metamaterial structures offer interesting perspectives to increase infrared detector performance at the pixel level for imaging or sensing applications.

  5. Wavelength-scale light concentrator made by direct 3D laser writing of polymer metamaterials

    Science.gov (United States)

    Moughames, J.; Jradi, S.; Chan, T. M.; Akil, S.; Battie, Y.; Naciri, A. En; Herro, Z.; Guenneau, S.; Enoch, S.; Joly, L.; Cousin, J.; Bruyant, A.

    2016-01-01

    We report on the realization of functional infrared light concentrators based on a thick layer of air-polymer metamaterial with controlled pore size gradients. The design features an optimum gradient index profile leading to light focusing in the Fresnel zone of the structures for two selected operating wavelength domains near 5.6 and 10.4 μm. The metamaterial which consists in a thick polymer containing air holes with diameters ranging from λ/20 to λ/8 is made using a 3D lithography technique based on the two-photon polymerization of a homemade photopolymer. Infrared imaging of the structures reveals a tight focusing for both structures with a maximum local intensity increase by a factor of 2.5 for a concentrator volume of 1.5 λ3, slightly limited by the residual absorption of the selected polymer. Such porous and flat metamaterial structures offer interesting perspectives to increase infrared detector performance at the pixel level for imaging or sensing applications. PMID:27698476

  6. Synchronization of video recording and laser pulses including background light suppression

    Science.gov (United States)

    Kalshoven, Jr., James E. (Inventor); Tierney, Jr., Michael (Inventor); Dabney, Philip W. (Inventor)

    2004-01-01

    An apparatus for and a method of triggering a pulsed light source, in particular a laser light source, for predictable capture of the source by video equipment. A frame synchronization signal is derived from the video signal of a camera to trigger the laser and position the resulting laser light pulse in the appropriate field of the video frame and during the opening of the electronic shutter, if such shutter is included in the camera. Positioning of the laser pulse in the proper video field allows, after recording, for the viewing of the laser light image with a video monitor using the pause mode on a standard cassette-type VCR. This invention also allows for fine positioning of the laser pulse to fall within the electronic shutter opening. For cameras with externally controllable electronic shutters, the invention provides for background light suppression by increasing shutter speed during the frame in which the laser light image is captured. This results in the laser light appearing in one frame in which the background scene is suppressed with the laser light being uneffected, while in all other frames, the shutter speed is slower, allowing for the normal recording of the background scene. This invention also allows for arbitrary (manual or external) triggering of the laser with full video synchronization and background light suppression.

  7. Multi-Color Anisotropy Measurements of the Cosmic Near-Infrared Extragalactic Background Light with CIBER2

    Science.gov (United States)

    Bock, James

    fluctuations at the design sensitivity of CIBER-2. The CIBER-2 instrument is optimized for sensitivity to surface brightness in a short sounding rocket flight. The instrument consists of a 28 cm wide-field telescope operating in 6 spectral bands between 0.5 and 2.0 um, cooled to a temperature of 77 K with a liquid-nitrogen-cooled cryostat. Images are composed using 3 focal plane assemblies operating H2RG detector arrays. The instrument is currently being fabricated with international partners and nearing completion. CIBER-2 will extend the CIBER-1 anisotropy meausurements from the near-infrared into the optical, where the EOR and IHL components of the extragalactic background can be cleanly distinguished and separated. We will study the history of IHL production by implementing a multi-band cross-correlation analysis, and use this information to carry out a deep search for an EOR component. We plan joint observations with weak lensing maps, with an optimized set of filter bands to measure spectral cross-correlations, to fully elucidate the history of IHL light production. In addition, our international partners will measure the absolute brightness of the background at optical to near-infrared wavelengths using 3 specialized linear-variable filter spectrometers.

  8. In Vitro Bactericidal Effects of 625, 525, and 425 nm Wavelength (Red, Green, and Blue) Light-Emitting Diode Irradiation

    Science.gov (United States)

    Kim, SangWoo; Kim, JiSun; Lim, WonBong; Jeon, SangMi; Kim, OkSu; Koh, Jeong-Tae; Kim, Chang-Su; Choi, HongRan

    2013-01-01

    Abstract Objective: The purpose of this study was to evaluate the relationship of 625, 525, and 425 nm wavelengths, providing average power output and effects on three common pathogenic bacteria. Background data: Ultraviolet (UV) light kills bacteria, but the bactericidal effects of UV may not be unique, as 425 nm produces a similar effect. The bactericidal effects of light-emitting diode (LED) wavelengths such as 625 and 525 nm have not been described. Before conducting clinical trials, the appropriate wavelength with reasonable dose and exposure time should be established. Materials and methods: The bactericidal effects of 625, 525, and 425 nm wavelength LED irradiation were investigated in vitro for the anaerobic bacterium Porphyromonas gingivalis and two aerobes (Staphylococcus aureus and Escherichia coli DH5α). Average power output was 6 mW/cm2 for 1 h. The bacteria were exposed to LED irradiation for 1, 2, 4, and 8 h (21.6, 43.2, 86.4, and 172.8 J/cm2, respectively). LED irradiation was performed during growth on agar and in broth. Control bacteria were incubated without LED irradiation. Bacterial growth was expressed in colony-forming units (CFU) and at an optical density at 600 nm in agar and broth. Results: The bactericidal effect of LED phototherapy depended upon wavelength, power density, bacterial viable number, and bacteria species. The bactericidal effect of 425 and 525 nm irradiation varied depending upon the bacterial inoculation, compared with unirradiated samples and samples irradiated with red light. Especially, P. gingivalis and E. coli DH5α were killed by 425 nm, and S. aureus growth was inhibited by 525 nm. However, the wavelength of 625 nm was not bactericidal for P. gingivalis, E. coli DH5α, or S. aureus. Conclusions: Irradiation at 625 nm light was not bactericidal to S. aureus, E. coli, and P. gingivalis, whereas wavelengths of 425 and 525 nm had bactericidal effects. S. aureus was also killed at 525

  9. Influence of exposure in ovo to different light wavelengths on the lateralization of social response in zebrafish larvae.

    Science.gov (United States)

    Sovrano, Valeria Anna; Bertolucci, Cristiano; Frigato, Elena; Foà, Augusto; Rogers, Lesley J

    2016-04-01

    Exposure of the chick embryo to different wavelengths of light of the same intensity has shown that only certain wavelengths may be important in generating visual asymmetries. This study aimed to detect the possible influence of different wavelengths of light on development of asymmetry of social recognition in zebrafish larvae, tested using the fish's mirror image as the stimulus. From fertilization until day 10 post-hatching zebrafish were kept in five different lighting conditions: natural light/dark (LD) cycle, complete darkness (DD), and artificial LD cycles with 14 h of monochromatic light (red, green, or violet light) and 10 h of darkness (rLD 14:10, gLD 14:10, vLD 14:10, respectively). On day 10 after hatching, the zebrafish larvae were subjected to a mirror test. A preference for using the left eye to scrutinize their mirror image was apparent only in zebrafish larvae exposed to and reared under a natural LD cycle, and not following exposure to any of other lighting conditions. These results are discussed with reference to other evidence of brain lateralization.

  10. Implications for photonic applications of diatom growth and frustule nanostructure changes in response to different light wavelengths

    DEFF Research Database (Denmark)

    Su, Yanyan; Lundholm, Nina; Friis, Søren Michael Mørk

    2015-01-01

    Diatoms are unicellular algae enclosed in intricate bio - silicified walls with repetitive nanostructures in a size range which makes them potentially relevant for a broad spectrum of industrial applications. How to optimize the nano - scale structures of the frustule for utilization of diatoms...... applications. In this study, we tested the influence of light quality on the nanostructure of the frustule of Coscinodiscus granii and compared this to growth rate response. The results showed that colored light (red, yellow, green and blue) at 300 μmol photons m - 2 s - 1 resulted in a statistically...... in the photonics properties of the frustule. The wavelength had no effect on the growth rate at high light intensity (300 μmol photons m - 2 s - 1 ). However, at 100 μmol photons m - 2 s - 1 , yellow, red - orange and green light resulted in significantly lower maximum growth rates than the other wavelengths...

  11. The wavelength composition and temporal modulation of ambient lighting strongly affect refractive development in young tree shrews.

    Science.gov (United States)

    Gawne, Timothy J; Siegwart, John T; Ward, Alexander H; Norton, Thomas T

    2016-12-12

    Shortly after birth, the eyes of most animals (including humans) are hyperopic because the short axial length places the retina in front of the focal plane. During postnatal development, an emmetropization mechanism uses cues related to refractive error to modulate the growth of the eye, moving the retina toward the focal plane. One possible cue may be longitudinal chromatic aberration (LCA), to signal if eyes are getting too long (long [red] wavelengths in better focus than short [blue]) or too short (short wavelengths in better focus). It could be difficult for the short-wavelength sensitive (SWS, "blue") cones, which are scarce and widely spaced across the retina, to detect and signal defocus of short wavelengths. We hypothesized that the SWS cone retinal pathway could instead utilize temporal (flicker) information. We thus tested if exposure solely to long-wavelength light would cause developing eyes to slow their axial growth and remain refractively hyperopic, and if flickering short-wavelength light would cause eyes to accelerate their axial growth and become myopic. Four groups of infant northern tree shrews (Tupaia glis belangeri, dichromatic mammals closely related to primates) began 13 days of wavelength treatment starting at 11 days of visual experience (DVE). Ambient lighting was provided by an array of either long-wavelength (red, 626 ± 10 nm) or short-wavelength (blue, 464 ± 10 nm) light-emitting diodes placed atop the cage. The lights were either steady, or flickering in a pseudo-random step pattern. The approximate mean illuminance (in human lux) on the cage floor was red (steady, 527 lux; flickering, 329 lux), and blue (steady, 601 lux; flickering, 252 lux). Refractive state and ocular component dimensions were measured and compared with a group of age-matched normal animals (n = 15 for refraction (first and last days); 7 for ocular components) raised in broad spectrum white fluorescent colony lighting (100-300 lux). During the 13 day

  12. Installation and Commissioning of a 6-Tesla Superconducting Wavelength Shifter at Taiwan Light Source

    Science.gov (United States)

    Chang, C. H.; Chang, H. P.; Chen, Jenny; Chen, J. R.; Fan, T. C.; Hwang, C. S.; Hsiung, G. Y.; Hsu, K. T.; Kuo, C. C.; Luo, G. H.; Wang, D. J.; Wang, M. H.

    2005-09-01

    The Taiwan Light Source (TLS) is the first third-generation light source in Asia. The storage ring has six straight sections one section for injection, one for the RF cavities and diagnostic instrumentation and four sections for insertion devices, which are U5, U9, EPU and W20. Generating high-energy X-ray photons is a high priority at TLS. A single hybrid type wiggler is associated with three beam lines to serve X-ray users. The installed Superconducting Wavelength Shifter (SWLS) is very compact in size and can produce very high-energy photons. The injection section at TLS can barely accommodate the SWLS. The expected multipole components of the SWLS are strong, shrink the dynamic aperture; perturb the beta function, and reduce the beam lifetime. The increase in the synchrotron radiation by the SWLS also changes beam emittance and increases the energy spread. The influence of SWLS on the low-energy, 1.5 GeV, storage-ring should not be neglected. The downstream kicker with the water-cooled copper mask must be modified to prevent a potential meltdown of the welding junction of the ceramic chamber because the heat load is high. The 1.2 μs half-sine pulse field of the kicker is then altered by the copper-made radiation mask, which is installed inside the ceramic chamber. The operating capability of cryogenic system is established to ensure the smooth commissioning of the SWLS. The magnetic field mapping, the dynamic aperture simulation data and commissioning results will be presented and discussed herein.

  13. LIGHT MODULATION: Quasi-collinear tunable acousto-optic paratellurite crystal filters for wavelength division multiplexing and optical channel selection

    Science.gov (United States)

    Molchanov, V. Ya; Voloshinov, V. B.; Makarov, O. Yu

    2009-04-01

    Quasi-collinear acousto-optic interaction is studied in acoustically and optically anisotropic paratellurite crystals. The possible applications of this interaction in acousto-optic tunable filters with a high spectral resolution are discussed. Different modifications of devices are compared and variants of devices intended for processing light beams and selection of light signals in fibreoptic communication systems with wavelength division multiplexing (WDM) at λ simeq 1550 nm are considered.

  14. Effective nonlinear refractive index of nano-porous silicon and its dependence on porosity and light wavelength

    Science.gov (United States)

    Bazaru, Tatiana; Vlad, Valentin I.; Petris, Adrian; Miu, Mihaela

    2010-05-01

    In this paper, we study the dependence of effective optical linear and nonlinear refractive indices of nano-porous silicon layers on crystalline silicon substrates on fill fraction, at different light wavelengths in visible and near-infrared. Simple approximative formulae, in the frame of Bruggeman's formalism, that describe the dependences of effective optical linear and nonlinear refractive indices of nano-porous silicon on fill fractions and on wavelength, in the range of 620 - 1000 nm, are derived. Experimental results with reflection intensity scan show a good agreement with the data provided by our formulae and the exact results of Boyd-Bruggeman's formalism for the third order nonlinearity, in the case nanoporous silicon with different porosity and at light wavelengths in the mentioned spectral range.

  15. Purifying Synthetic High-Strength Wastewater by Microalgae Chlorella Vulgaris Under Various Light Emitting Diode Wavelengths and Intensities

    Directory of Open Access Journals (Sweden)

    Zhigang Ge

    2013-06-01

    Full Text Available The high-strength wastewater is now well known as a threat to the natural water since it is highly possible to arouse water eutrophication or algal blooms. The effects of various light emitting diode wavelengths and intensities on the microalgae biological wastewater treatment system was studied in this research. The various nutrient removals and economic efficiencies represented similar variation trends, and these variations under both high C and N loading treatments were similar too. The order for microalgae C. vulgaris reproduction in terms of dry weight and nutrient removal efficiency both were red > white > yellow > blue, under high carbon and nitrogen loading treatments, indicating that the red light was the optimum light wavelength. Furthermore, considering the optimal light intensity in terms of nutrient removal efficiency was 2500 and 2000 μmol/m2•s, while in terms of economic efficiency was 1000, 1500 and 2000 μmol/m2•s. Therefore, the optimum light intensity was found to be 2000 μmol/m2•s. In addition, the optimal experimental illumination time was determined as 120 h. The Chlorella vulgaris microalgae biological wastewater treatment system utilized in this research was able to purify the high-strength carbon and nitrogen wastewater effectively under optimum light wavelength and intensity.

  16. Short wavelength light filtering by the natural human lens and IOLs -- implications for entrainment of circadian rhythm

    DEFF Research Database (Denmark)

    Brøndsted, Adam Elias; Lundeman, Jesper Holm; Kessel, Line

    2013-01-01

    Photoentrainment of circadian rhythm begins with the stimulation of melanopsin containing retinal ganglion cells that respond directly to blue light. With age, the human lens becomes a strong colour filter attenuating transmission of short wavelengths. The purpose of the study was to examine...

  17. Microlensing of Sub-parsec Massive Binary Black Holes in Lensed QSOs: Light Curves and Size-Wavelength Relation

    Science.gov (United States)

    Yan, Chang-Shuo; Lu, Youjun; Yu, Qingjuan; Mao, Shude; Wambsganss, Joachim

    2014-04-01

    Sub-parsec binary massive black holes (BBHs) have long been thought to exist in many QSOs but remain observationally elusive. In this paper, we propose a novel method to probe sub-parsec BBHs through microlensing of lensed QSOs. If a QSO hosts a sub-parsec BBH in its center, it is expected that the BBH is surrounded by a circumbinary disk, each component of the BBH is surrounded by a small accretion disk, and a gap is opened by the secondary component in between the circumbinary disk and the two small disks. Assuming such a BBH structure, we generate mock microlensing light curves for some QSO systems that host BBHs with typical physical parameters. We show that microlensing light curves of a BBH QSO system at the infrared-optical-UV bands can be significantly different from those of corresponding QSO system with a single massive black hole (MBH), mainly because of the existence of the gap and the rotation of the BBH (and its associated small disks) around the center of mass. We estimate the half-light radii of the emission region at different wavelengths from mock light curves and find that the obtained half-light radius versus wavelength relations of BBH QSO systems can be much flatter than those of single MBH QSO systems at a wavelength range determined by the BBH parameters, such as the total mass, mass ratio, separation, accretion rates, etc. The difference is primarily due to the existence of the gap. Such unique features on the light curves and half-light radius-wavelength relations of BBH QSO systems can be used to select and probe sub-parsec BBHs in a large number of lensed QSOs to be discovered by current and future surveys, including the Panoramic Survey Telescope and Rapid Response System, the Large Synoptic Survey telescope, and Euclid.

  18. Manipulation of light wavelength at appropriate growth stage to enhance biomass productivity and fatty acid methyl ester yield using Chlorella vulgaris.

    Science.gov (United States)

    Kim, Dae Geun; Lee, Changsu; Park, Seung-Moon; Choi, Yoon-E

    2014-05-01

    LEDs light offer several advantages over the conventional lamps, thereby being considered as the optimal light sources for microalgal cultivation. In this study, various light-emitting diodes (LEDs) especially red and blue color with different light wavelengths were employed to explore the effects of light source on phototrophic cultivation of Chlorella vulgaris. Blue light illumination led to significantly increased cell size, whereas red light resulted in small-sized cell with active divisions. Based on the discovery of the effect of light wavelengths on microalgal biology, we then applied appropriate wavelength at different growth stages; blue light was illuminated first and then shifted to red light. By doing so, biomass and lipid productivity of C. vulgaris could be significantly increased, compared to that in the control. These results will shed light on a novel approach using LED light for microalgal biotechnology.

  19. Wavelength-tunable and white-light emission from polymer-converted micropixellated InGaN ultraviolet light-emitting diodes

    Science.gov (United States)

    Heliotis, G.; Gu, E.; Griffin, C.; Jeon, C. W.; Stavrinou, P. N.; Dawson, M. D.; Bradley, D. D. C.

    2006-07-01

    We report the use of light-emitting conjugated polymer materials to wavelength-convert the emission from a two-dimensional array of micropixellated InGaN light-emitting diodes (LEDs). We demonstrate hybrid organic/inorganic light-emitting devices that can operate across the entire visible spectrum, and we also fabricate white-emitting versions of these devices by employing single layers of carefully adjusted polymer blends in which cascade non-radiative energy transfer occurs between the constituent materials. Additional colours may be easily obtained by tuning the composition of the polymer blends. Our work demonstrates that the combination of conjugated polymers and UV micro-LED arrays provides an attractive approach to developing microscale wavelength-tunable light sources and may provide a route to low-cost full-colour microdisplays and other instrumentation devices.

  20. Visible light stimulating dual-wavelength emission and O vacancy involved energy transfer behavior in luminescence for coaxial nanocable arrays

    Science.gov (United States)

    Yang, Lei; Dong, Jiazhang; Jiang, Zhongcheng; Pan, Anlian; Zhuang, Xiujuan

    2014-06-01

    We report a strategy to investigate O vacancy (VO) involved energy transfer and dual-wavelength yellow emission in coaxial nanocable. By electric field deposition and subsequent sol-gel template approach, ZnO:Tb/Y2O3:Eu coaxial nanocable arrays are synthesized. After visible light excitation, system is promoted to O vacancy charge transfer state of VO(0/+). In the following cross relaxation, energy transfer from VO to the excitation energy level of Tb3+ in ZnO:Tb core area. While in Y2O3:Eu shell area, energy transfer to the excitation energy level of Eu3+. Subsequently, dual-wavelength emission is observed. By constructing nanocable with dual-wavelength emission, yellow luminescence is obtained. Adjust doping concentration of Eu3+ or Tb3+ in the range of 0.01-0.05, chromaticity coordinates of ZnO:Tb/Y2O3:Eu nanocable stably stays at yellow region in color space except ZnO:Tb0.01/Y2O3:Eu0.01. As Vo states act as media in energy transfer process in nanocablers, visible light can stimulate dual-wavelength emissions. Yellow luminescent nanocable arrays will have great applications in light-emitting diode luminescence.

  1. Sterilization effect of UV light on Bacillus spores using TiO2 films depends on wavelength

    OpenAIRE

    Nhung, Le Thi Tuyet; Nagata, Hirofumi; Takahashi, Akira; Aihara, Mutsumi; Okamoto, Toshihiro; Shimohata, Takaaki; Mawatari, Kazuaki; Akutagawa, Masatake; Kinouchi, Yohsuke; Haraguchi, Masanobu

    2012-01-01

    UV light and photocatalysts such as titanium dioxide (TiO2) and silver (Ag) are useful for disinfection of water and surfaces. However, the effect of UV wavelength on photocatalytic disinfection of spores is not well understood. Inactivation of Bacillus spores has been examined using different UV wavelengths and TiO2 or TiO2/Ag composite materials. The level of UVA disinfection of Bacillus anthracis and Bacillus brevis vegetative cells increased with the presence of the TiO2 and Ag photocatal...

  2. Rapid production of large-area deep sub-wavelength hybrid structures by femtosecond laser light-field tailoring

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Lei; Chen, Qi-Dai, E-mail: chenqd@jlu.edu.cn, E-mail: hbsun@jlu.edu.cn; Yang, Rui; Xu, Bin-Bin; Wang, Hai-Yu [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Yang, Hai; Huo, Cheng-Song; Tu, Hai-Ling [General Research Institute for Nonferrous Metals, Beijing 100088 (China); Sun, Hong-Bo, E-mail: chenqd@jlu.edu.cn, E-mail: hbsun@jlu.edu.cn [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); College of Physics, Jilin University, 119 Jiefang Road, Changchun 130023 (China)

    2014-01-20

    The goal of creation of large-area deep sub-wavelength nanostructures by femtosecond laser irradiation onto various materials is being hindered by the limited coherence length. Here, we report solution of the problem by light field tailoring of the incident beam with a phase mask, which serves generation of wavelets. Direct interference between the wavelets, here the first-order diffracted beams, and interference between a wavelet and its induced waves such as surface plasmon polariton are responsible for creation of microgratings and superimposed nanogratings, respectively. The principle of wavelets interference enables extension of uniformly induced hybrid structures containing deep sub-wavelength nanofeatures to macro-dimension.

  3. Wavelength agile nonmechanical laser beam steering from Fresnel zone plates imprinted on a liquid crystal spatial light modulator

    Science.gov (United States)

    Lindle, James R.; Watnik, Abbie T.; Cassella, Vincent A.

    2016-09-01

    Multibeam, multicolor, large-angle beam-steering is demonstrated in the visible spectral region by imprinting Fresnel zone plates (FZP) on a liquid crystal spatial light modulator. Spectral dispersion, both diffractive and refractive, is observed but does not prevent the use of this technology for beam steering applications. The experimental results show that while diffractive dispersion dominates over refractive dispersion, wavelength-specific FZPs can be rendered to direct those beams on target, either simultaneously or consecutively. Only a slight correction in the FZP positon is necessary to compensate for refractive dispersion. The position, intensity, and wavelength of each beam can be controlled independently.

  4. Implications for photonic applications of diatom growth and frustule nanostructure changes in response to different light wavelengths

    Institute of Scientific and Technical Information of China (English)

    Yanyan Su[1; Nina Lundholm[2; Sφren M. M. Friis[3; Marianne Ellegaard[1

    2015-01-01

    Diatoms are unicellular algae enclosed in intricate bio-silicified walls with repetitive nanostructures in a size range which makes them potentially relevant for a broad spectrum of industrial applications. How to optimize the nano-scale structures of the frustule for utilization of diatoms in nanotechnology is one of the technological challenges for these applications. Light is one of the most important abiotic factors for algal photosynthetic growth, and the frustule may play an important role in mediating light for these biological functions, as well as being central for its nano-technological applications. In this study we tested the influence of light quality on the nanostructure of the frustule of Coscinodiscus granii and compared this to growth rate response. The results showed that colored light (red, yellow, green and blue) at 300μmol photons m-2-s-1 resulted in a statistically significant change in nanostructure compared to white light. Green light at 100 μmol photon m-2.s-1 led to a significant decrease in mean frustule diameter and mean foramen diameter. Numerical simulations confirmed that the morphological changes obtained were sufficient to induce clear differences in the photonics properties of the frustule. The wavelength had no effect on the growth rate at high light intensity (300 μmol photons m-2.s-1). However, at 100 μmol photons m-2.s-1, yellow, red-orange and green light resulted in significantly lower maximum growth rates than the other wavelengths. This response of the frustule structure to different light treatment indicates the possibility of a light-based frustule nanostructure manipulation method, which is simple and environmentally friendly.

  5. Enhanced UV light detection using a p-terphenyl wavelength shifter

    CERN Document Server

    Joosten, S; Ungaro, M; Rehfuss, M; Johnston, K; Meziani, Z -E

    2016-01-01

    UV-glass photomultiplier tubes (PMTs) have poor photon detection efficiency for wavelengths below $300\\,\\text{nm}$ due to the opaqueness of the window material. Costly quartz PMTs could be used to enhance the efficiency below $300\\,\\text{nm}$. A less expensive solution that dramatically improves this efficiency is the application of a thin film of a p-terphenyl (PT) wavelength shifter on UV-glass PMTs. This improvement was quantified for Photonis XP4500B PMTs for wavelengths between $200\\,\\text{nm}$ and $400\\,\\text{nm}$. The gain factor ranges up to 5.4 $\\pm$ 0.5 at a wavelength of $215\\,\\text{nm}$, with a material load of $110\\pm10\\,\\mu\\text{g}/\\text{cm}^2$ ($894\\,\\text{nm}$). The wavelength shifter was found to be fully transparent for wavelengths greater than $300\\,\\text{nm}$. The resulting gain in detection efficiency, when used in a typical Cherenkov counter, was estimated to be of the order of 40\\%. Consistent coating quality was assured by a rapid gain testing procedure using narrow-band UV LEDs. Based...

  6. Asymmetrically filled slits in a metal film that split a light beam into two depending on its wavelength

    CERN Document Server

    Huang, Danhong

    2012-01-01

    By applying a scattering-wave theory, the electromagnetic response of an arbitrary array of multiple slits perforated on a metallic film and filled with different slit dielectric materials can be studied in an analytical way. Here, the wavelength-dependent splitting of a light beam into two by asymmetrically filled slits in a metal film using intra- and inter-slit dual-wave interferences is fully explored. We consider a triple-slit structure perforated on a gold film, where the middle slit is used for the surface-plasmon excitation by a narrow Gaussian beam while the two side slits are used for the detection of a transmitted surface-plasmon wave propagated from the middle opaque slit either at a particular wavelength or at double that wavelength, respectively. For this proposed simple structure, we show that only one of the two side observation slits can be in a passing state for a particular wavelength, but the other blocked slit will change to a passing state at double that wavelength with a specific design...

  7. Thermo-driven light controller by using thermal modulation of diffraction wavelength in holographic polymer dispersed liquid crystal grating

    Science.gov (United States)

    Ogiwara, Akifumi; Kakiuchida, Hiroshi

    2014-02-01

    A microperiodic structure composed of polymer and liquid crystal (LC) phases, called holographic polymer dispersed liquid crystal (HPDLC), was fabricated based on a photo-induced phase separation technique by laser interferometric exposure. The diffraction wavelength of HPDLC gratings formed by different LC composites and grating structures was experimentally investigated by spectroscopic measurements as a function of temperature at around 30 °C. The HPDLC gratings composed of nematic LC having low nematic to isotropic temperature (TNI) and film thickness of 25 μm showed the switch of diffraction wavelength between visible and infrared lights by the change of temperature. The optical characteristics achieved in HPDLC gratings are expected to be applicable for the basis of diffractive type of thermodriven light controller which can supply visibility constantly for solar-ray control windows.

  8. Long Wavelength Electromagnetic Light Bullets Generated by a 10.6 micron CO2 Ultrashort Pulsed Source

    Science.gov (United States)

    2016-11-29

    GRANT NUMBER FA9550-15-1-0272 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Dr . Jerome V. Moloney, Professor of Optical Sciences University of Arizona...afosr.reports.sgizmo.com/s3/> Subject: Final Report to Dr . Arje Nachman Contract/Grant Title: Long Wavelength Electromagnetic Light Bullets Generated by a 10.6...kilometer ranges. Our in- house ultrashort pulse simulation tool was used to provide basic research support for studying atmospheric propagation of a

  9. The effect of increased ambient lighting on detection accuracy in uniform and anatomical backgrounds

    Science.gov (United States)

    Pollard, Benjamin J.; Chawla, Amarpreet S.; Hashimoto, Noriyuki; Samei, Ehsan

    2008-03-01

    Under typical dark conditions found in reading rooms, a reader's pupils will contract and dilate as the visual focus intermittently shifts between the high luminance monitor and the darker background wall, resulting in increased visual fatigue and the degradation of diagnostic performance. A controlled increase of ambient lighting may, however, minimize these visual adjustments and potentially improve reader comfort and accuracy. This paper details results from two psychophysical studies designed to determine the effect of a controlled ambient lighting increase on observer detection of subtle objects and lesions viewed on a DICOM-calibrated medical-grade LCD. The first study examined the effect of increased ambient lighting on detection of subtle objects embedded within a uniform background, while the second study examined observer detection performance of subtle cancerous lesions in mammograms and chest radiographs. In both studies, observers were presented with images under a dark room condition (1 lux) and an increased room illuminance level (50 lux) for which the luminance level of the diffusely reflected light from the background wall was approximately equal to that of the displayed image. The display was calibrated to an effective luminance ratio of 409 for both lighting conditions. Observer detection performance under each room illuminance condition was then compared. Identification of subtle objects embedded within the uniform background improved from 59% to 67%, while detection time decreased slightly with additional illuminance. An ROC analysis of the anatomical image results revealed that observer AUC values remained constant while detection time decreased under increased illuminance. The results provide evidence that an ambient lighting increase may be possible without compromising diagnostic efficacy.

  10. Effects of different wavelengths of light on the biology, behavior, and production of grow-out Pekin ducks.

    Science.gov (United States)

    Campbell, C L; Colton, S; Haas, R; Rice, M; Porter, A; Schenk, A; Meelker, A; Fraley, S M; Fraley, G S

    2015-08-01

    Previous research has shown that red light conditions may improve growth and decrease aggressive behaviors in chickens and turkeys; however, more recent studies suggest that blue-green light may improve production of broilers over red light. To date, no research has been conducted to examine whether different wavelengths of light have an impact on production in the Pekin duck. To determine this, we raised Pekin ducks under aviary conditions that were similar to standard commercial barns. The ducks were kept in 3 different pens: red light (approximately 625 nm), blue light (approximately 425 nm), and white light. Light sources in each pen were standardized to produce a peak energy at 1.6 × 10³ μM photons/m²/s at the level of the ducks' heads. Ducks were given ad libitum access to water and commercial duck diet, and were housed on pine shavings at a density of 0.43 m²/duck. Ducks were evaluated weekly for BW and condition and a subjective measure of the duck's anxiety levels was determined. We found that ducks housed under blue light had significantly (P < 0.01) reduced BW at every age until the end of the study (processing age; 35 d). Unlike ducks housed under red or white light, ducks housed in the blue pen showed a higher level of anxiety; while evaluators were in the pen a majority of them began panting, they were much less inquisitive than other ducks, they took longer to exhibit normal social behavior once evaluation was completed, and they frequently "swarmed" when no people were present. There were no differences in any measurements between the red and white-lighted pens. These data suggest that unlike the chicken, blue lights may be inappropriate for raising Pekin ducks in a commercial setting.

  11. Wavelength-dependent degradation of ochratoxin and citrinin by light in vitro and in vivo and its implications on Penicillium.

    Science.gov (United States)

    Schmidt-Heydt, Markus; Cramer, Benedikt; Graf, Irina; Lerch, Sandra; Humpf, Hans-Ulrich; Geisen, Rolf

    2012-12-14

    It has previously been shown that the biosynthesis of the mycotoxins ochratoxin A and B and of citrinin by Penicillium is regulated by light. However, not only the biosynthesis of these mycotoxins, but also the molecules themselves are strongly affected by light of certain wavelengths. The white light and blue light of 470 and 455 nm are especially able to degrade ochratoxin A, ochratoxin B and citrinin after exposure for a certain time. After the same treatment of the secondary metabolites with red (627 nm), yellow (590 nm) or green (530 nm) light or in the dark, almost no degradation occurred during that time indicating the blue light as the responsible part of the spectrum. The two derivatives of ochratoxin (A and B) are degraded to certain definitive degradation products which were characterized by HPLC-FLD-FTMS. The degradation products of ochratoxin A and B did no longer contain phenylalanine however were still chlorinated in the case of ochratoxin A. Citrinin is completely degraded by blue light. A fluorescent band was no longer visible after detection by TLC suggesting a higher sensitivity and apparently greater absorbance of energy by citrinin. The fact that especially blue light degrades the three secondary metabolites is apparently attributed to the absorption spectra of the metabolites which all have an optimum in the short wave length range. The absorption range of citrinin is, in particular, broader and includes the wave length of blue light. In wheat, which was contaminated with an ochratoxin A producing culture of Penicillium verrucosum and treated with blue light after a pre-incubation by the fungus, the concentration of the preformed ochratoxin A reduced by roughly 50% compared to the control and differed by > 90% compared to the sample incubated further in the dark. This indicates that the light degrading effect is also exerted in vivo, e.g., on food surfaces. The biological consequences of the light instability of the toxins are discussed.

  12. Dual-wavelength light-scattering technique for selective detection of volcanic ash particles in the presence of water droplets

    Science.gov (United States)

    Jurányi, Z.; Burtscher, H.; Loepfe, M.; Nenkov, M.; Weingartner, E.

    2015-12-01

    A new method is presented in this paper which analyses the scattered light of individual aerosol particles simultaneously at two different wavelengths in order to retrieve information on the particle type. We show that dust-like particles, such as volcanic ash, can be unambiguously discriminated from water droplets on a single-particle level. As a future application of this method, the detection of volcanic ash particles should be possible in a humid atmosphere in the presence of cloud droplets. The characteristic behaviour of pure water's refractive index can be used to separate water droplets and dust-like particles which are commonly found in the micrometre size range in the ambient air. The low real part of the water's refractive index around 2700-2800 nm results in low scattered light intensities compared to e.g. the visible wavelength range, and this feature can be used for the desired particle identification. The two-wavelength measurement set-up was theoretically and experimentally tested and studied. Theoretical calculations were done using Mie theory. Comparing the ratio of the scattered light at the two wavelengths (visible-to-IR (infrared), R value) for water droplets and different dust types (basalt, andesite, African mineral dust, sand, volcanic ash, pumice) showed at least 9-times-higher values (on average 70 times) for water droplets than for the dust types at any diameter within the particle size range of 2-20 μm. The envisaged measurement set-up was built up into a laboratory prototype and was tested with different types of aerosols. We generated aerosols from the following powders, simulating dust-like particles: cement dust, ISO 12103-1 A1 Ultrafine Test Dust and ash from the 2012 eruption of the Etna volcano. Our measurements verified the theoretical considerations; the median experimental R value is 8-21 times higher for water than for the "dust" particles.

  13. Dual-wavelength light-scattering technique for selective detection of volcanic ash particles in the presence of water droplets

    Directory of Open Access Journals (Sweden)

    Z. Jurányi

    2015-12-01

    Full Text Available A new method is presented in this paper which analyses the scattered light of individual aerosol particles simultaneously at two different wavelengths in order to retrieve information on the particle type. We show that dust-like particles, such as volcanic ash, can be unambiguously discriminated from water droplets on a single-particle level. As a future application of this method, the detection of volcanic ash particles should be possible in a humid atmosphere in the presence of cloud droplets. The characteristic behaviour of pure water's refractive index can be used to separate water droplets and dust-like particles which are commonly found in the micrometre size range in the ambient air. The low real part of the water's refractive index around 2700–2800 nm results in low scattered light intensities compared to e.g. the visible wavelength range, and this feature can be used for the desired particle identification. The two-wavelength measurement set-up was theoretically and experimentally tested and studied. Theoretical calculations were done using Mie theory. Comparing the ratio of the scattered light at the two wavelengths (visible-to-IR (infrared, R value for water droplets and different dust types (basalt, andesite, African mineral dust, sand, volcanic ash, pumice showed at least 9-times-higher values (on average 70 times for water droplets than for the dust types at any diameter within the particle size range of 2–20 μm. The envisaged measurement set-up was built up into a laboratory prototype and was tested with different types of aerosols. We generated aerosols from the following powders, simulating dust-like particles: cement dust, ISO 12103-1 A1 Ultrafine Test Dust and ash from the 2012 eruption of the Etna volcano. Our measurements verified the theoretical considerations; the median experimental R value is 8–21 times higher for water than for the "dust" particles.

  14. SXDF-ALMA 2 Arcmin^2 Deep Survey: Resolving and Characterizing the Infrared Extragalactic Background Light Down to 0.5 mJy

    CERN Document Server

    Yamaguchi, Yuki; Kohno, Kotaro; Aretxaga, Itziar; Dunlop, James S; Hatsukade, Bunyo; Hughes, David; Ikarashi, Soh; Ishii, Shun; Ivison, Rob J; Izumi, Takuma; Kawabe, Ryohei; Kodama, Tadayuki; Lee, Minju; Makiya, Ryu; Matsuda, Yuichi; Nakanishi, Kouichiro; Ohta, Kouji; Rujopakarn, Wiphu; Tadaki, Ken-ichi; Umehata, Hideki; Wang, Wei-Hao; Wilson, Grant W; Yabe, Kiyoto; Yun, Min S

    2016-01-01

    We present a multi-wavelength analysis of five submillimeter sources (S_1.1mm = 0.54-2.02 mJy) that were detected during our 1.1-mm-deep continuum survey in the SXDF-UDS-CANDELS field (2 arcmin^2, 1sigma = 0.055 mJy beam^-1) using the Atacama Large Millimeter/submillimeter Array (ALMA). The two brightest sources correspond to a known single-dish (AzTEC) selected bright submillimeter galaxy (SMG), whereas the remaining three are faint SMGs newly uncovered by ALMA. If we exclude the two brightest sources, the contribution of the ALMA-detected faint SMGs to the infrared extragalactic background light is estimated to be ~ 4.1^{+5.4}_{-3.0} Jy deg^{-2}, which corresponds to ~ 16^{+22}_{-12}% of the infrared extragalactic background light. This suggests that their contribution to the infrared extragalactic background light is as large as that of bright SMGs. We identified multi-wavelength counterparts of the five ALMA sources. One of the sources (SXDF-ALMA3) is extremely faint in the optical to near-infrared region...

  15. Visible-light wavelength matched microsphere assembly of TiO{sub 2} superfine nanorods and the enhanced photovoltaic performance

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Xiyun; Wang, Yumin; Zhang, Xiang; Sun, Hongxia; Zhang, Qingsong; Niu, Laiyou; Liu, Juan; Zhou, Xingfu, E-mail: Zhouxf@njtech.edu.cn

    2015-05-15

    Graphical abstract: A novel visible-light wavelength matched microspheres assembly of TiO{sub 2} superfine nanorods with a diameter of ∼5 nm was fabricated via a hydrothermal method. The as-prepared rutile TiO{sub 2} microspheres have a uniform diameter of ∼450 nm and show a good light-trapping performance. Dye-sensitized solar cell based on this sample shows a satisfactory energy conversion efficiency of 6.59% and is the highest PCE reported for intrinsic rutile TiO{sub 2}. The further optimized DSSC shows a conversion efficiency of 8.3%, though the internal resistance is higher and the dye absorption is lower than that of widely used anatase TiO{sub 2} nanoparticles. - Highlights: • Microsphere assembly of TiO{sub 2} nanorods with a diameter of ∼5 nm was fabricated. • TiO{sub 2} microspheres size is well matched with the visible light wavelength. • TiO{sub 2} microsphere enhances the light-scattering ability. • Rutile TiO{sub 2} microsphere shows an energy conversion efficiency of 6.59%. • The highest PCE reported for intrinsic rutile TiO{sub 2} is obtained. - Abstract: According to the Mie scattering theory, spheres with the size matched with light wavelength are most suitable for light scattering and enhance the light trapping ability. In this paper, a novel visible-light wavelength matched sphere assembly of TiO{sub 2} superfine nanorods was fabricated via a simple one-step hydrothermal method. The morphology and the structure were examined by field emission scanning electron microscopy (FESEM), X-ray powder diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). The visible subwavelength TiO{sub 2} microsphere resembling an immature chinese chestnut is composed of countless superfine TiO{sub 2} nanorods, the diameter of these building blocks of superfine TiO{sub 2} nanorods is ∼5 nm. The obtained TiO{sub 2} sphere has an average diameter of ca. 450 nm, which matches well with the visible light wavelength and cause the

  16. Light yield measurements in a liquid scintillator detector with wavelength-shifting fibre readout

    CERN Document Server

    Doucet, M; Grégoire, G; Panman, J; Zucchelli, P

    2001-01-01

    A technique based on liquid scintillator with wavelength-shiftingfibre readout is interesting for large-mass neutrino detectors. In this paper, we present results obtained with a laboratoryprototype assembled at CERN. Mixtures made of economical chemicalcomponents were compared to commercial liquid scintillators. Thelight yield was also studied as a function of fibre diameter, fibreposition, and surface quality of the container.

  17. Probing the Light Speed Anisotropy with respect to the Cosmic Microwave Background Radiation Dipole

    CERN Document Server

    Gurzadyan, V G; Kashin, A L; Margarian, A T; Bartalini, O; Bellini, V; Castoldi, M; D'Angelo, A; Didelez, J P; Salvo, R D; Fantini, A; Gervino, G; Ghio, F; Girolami, B; Giusa, A; Hourany, E; Knyazyan, S; Kuznetsov, V E; Lapik, A; Levi-Sandri, P; Llères, A; Mehrabyan, S S; Moricciani, D; Nedorezov, V; Perrin, C; Rebreyend, D; Russo, G; Rudnev, N; Schärf, C; Sperduto, M L; Sutera, M C; Turinge, A

    2005-01-01

    We have studied the angular fluctuations in the speed of light with respect to the apex of the dipole of Cosmic Microwave Background (CMB) radiation using the experimental data obtained with GRAAL facility, located at the European Synchrotron Radiation Facility (ESRF) in Grenoble. The measurements were based on the stability of the Compton edge of laser photons scattered on the 6 GeV monochromatic electron beam. The results enable to obtain a conservative constraint on the anisotropy in the light speed variations \\Delta c(\\theta)/c < 3 10^{-12}, i.e. with higher precision than from previous experiments.

  18. Effects of Wavelength and Defect Density on the Efficiency of (In,Ga)N-Based Light-Emitting Diodes

    Science.gov (United States)

    Pristovsek, Markus; Bao, An; Oliver, Rachel A.; Badcock, Tom; Ali, Muhammad; Shields, Andrew

    2017-06-01

    We measure the electroluminescence of light-emitting diodes (LEDs) on substrates with low dislocation densities (LDD) at 106 cm-2 and low 108 cm-2 , and compare them to LEDs on substrates with high dislocation densities (HDD) closer to 1010 cm-2 . The external quantum efficiencies (EQEs) are fitted using the A B C model with and without localization. The nonradiative-recombination (NR) coefficient A is constant for HDD LEDs, indicating that the NR is dominated by dislocations at all wavelengths. However, A strongly increases for LDD LEDs by a factor of 20 when increasing the emission wavelength from 440 to 540 nm. We attribute this to an increased density of point defects due to the lower growth temperatures used for longer wavelengths. The radiative recombination coefficient B follows the squared wave-function overlap for all samples. Using the observed coefficients, we calculate the peak efficiency as a function of the wavelength. For HDD LEDs the change of wave-function overlap (i.e., B ) is sufficient to reduce the EQE as observed, while for LDD LEDs also the NR coefficient A must increase to explain the observed EQEs. Thus, reducing NR is important to improving the EQEs of green LEDs, but this cannot be achieved solely by reducing the dislocation density: point defects must also be addressed.

  19. On the origin of near-infrared extragalactic background light anisotropy.

    Science.gov (United States)

    Zemcov, Michael; Smidt, Joseph; Arai, Toshiaki; Bock, James; Cooray, Asantha; Gong, Yan; Kim, Min Gyu; Korngut, Phillip; Lam, Anson; Lee, Dae Hee; Matsumoto, Toshio; Matsuura, Shuji; Nam, Uk Won; Roudier, Gael; Tsumura, Kohji; Wada, Takehiko

    2014-11-07

    Extragalactic background light (EBL) anisotropy traces variations in the total production of photons over cosmic history and may contain faint, extended components missed in galaxy point-source surveys. Infrared EBL fluctuations have been attributed to primordial galaxies and black holes at the epoch of reionization (EOR) or, alternately, intrahalo light (IHL) from stars tidally stripped from their parent galaxies at low redshift. We report new EBL anisotropy measurements from a specialized sounding rocket experiment at 1.1 and 1.6 micrometers. The observed fluctuations exceed the amplitude from known galaxy populations, are inconsistent with EOR galaxies and black holes, and are largely explained by IHL emission. The measured fluctuations are associated with an EBL intensity that is comparable to the background from known galaxies measured through number counts and therefore a substantial contribution to the energy contained in photons in the cosmos.

  20. Morphological background detection and illumination normalization of text image with poor lighting.

    Directory of Open Access Journals (Sweden)

    Guocheng Wang

    Full Text Available In this paper, some morphological transformations are used to detect the unevenly illuminated background of text images characterized by poor lighting, and to acquire illumination normalized result. Based on morphologic Top-Hat transform, the uneven illumination normalization algorithm has been carried out, and typically verified by three procedures. The first procedure employs the information from opening based Top-Hat operator, which is a classical method. In order to optimize and perfect the classical Top-Hat transform, the second procedure, featuring the definition of multi direction illumination notion, utilizes opening by reconstruction and closing by reconstruction based on multi direction structuring elements. Finally, multi direction images are merged to the final even illumination image. The performance of the proposed algorithm is illustrated and verified through the processing of different ideal synthetic and camera collected images, with backgrounds characterized by poor lighting conditions.

  1. On the Light Speed Anisotropy vs Cosmic Microwave Background Dipole: European Synchrotron Radiation Facility Measurements

    CERN Document Server

    Gurzadyan, V G; Kashin, A; Margarian, A T; Bartalini, O; Bellini, V; Castoldi, M; D'Angelo, A; Didelez, J P; Salvo, R D; Fantini, A; Gervino, G; Ghio, F; Girolami, B; Giusa, A; Guidal, M; Hourany, E; Knyazyan, S; Kouznetsov, V; Kunne, Ronald Alexander; Lapik, A; Levi-Sandri, P; Llères, A; Mehrabyan, S S; Moricciani, D; Nedorezov, V; Perrin, C; Rebreyend, D; Russo, G; Rudnev, N; Schärf, C; Sperduto, M L; Sutera, M C; Turinge, A

    2007-01-01

    The measurement of the Compton edge of the scattered electrons in GRAAL facility in European Synchrotron Radiation Facility (ESRF) in Grenoble with respect to the Cosmic Microwave Background dipole reveals up to 10 sigma variations larger than the statistical errors. We now show that the variations are not due to the frequency variations of the accelerator. The nature of Compton edge variations remains unclear, thus outlining the imperative of dedicated studies of light speed anisotropy.

  2. An empirical approach to the extragalactic background light from AEGIS galaxy SED-type fractions

    OpenAIRE

    Domínguez, Alberto

    2011-01-01

    The extragalactic background light (EBL) is of fundamental importance both for understanding the entire process of galaxy evolution and for gamma-ray astronomy. However, the overall spectrum of the EBL between 0.1 and 1000 microns has never been determined directly neither from observed luminosity functions (LFs), over a wide redshift range, nor from any multiwavelength observation of galaxy spectral energy distributions (SEDs). The evolving, overall spectrum of the EBL is derived here utiliz...

  3. High efficiency AlGaInN-based light emitting diode in the 360-380 nm wavelength range

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Hisao; Wang, Hong-Xing; Sato, Daisuke; Takaki, Ryohei; Wada, Naoki; Tanahashi, Tetsuya; Yamashita, Kenji; Kawano, Shunsuke; Mizobuchi, Takashi; Dempo, Akihiko; Morioka, Kenji; Kimura, Masahiro; Nohda, Suguru [Nitride Semiconductors Co., Ltd., 115-7 Itayajima, Akinokami, Seto-cho, Naruto, Tokushima 771-0360 (Japan); Sugahara, Tomoya [Satellite Venture Business Laboratory, The University of Tokushima (Japan); Sakai, Shiro [Department of Electrical and Electronic Engineering, The University of Tokushima, 2-1 Minami-josanjima, Tokushima 770-8506 (Japan)

    2003-11-01

    High performance LEDs emitting in the wavelength range 360-380 nm, are fabricated on sapphire substrates by one-time metalorganic chemical vapor deposition (MOCVD) without using epitaxial lateral overgrowth (ELO) or similar techniques. By improving layer structures and growth conditions, the output power of the LEDs was much improved. The light output power of the LEDs at an injection current of 20 mA is 3.2 mW, 2.5 mW and 1 mW at wavelengths of 378 nm, 373 nm and 363 nm, which correspond to an external quantum efficiency of 4.8%, 3.8% and 1.4%, respectively. (copyright 2003 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. A fiber optic, ultraviolet light-emitting diode-based, two wavelength fluorometer for monitoring reactive adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Granz, Christopher D.; Whitten, James E., E-mail: James-Whitten@uml.edu [Department of Chemistry, University of Massachusetts Lowell, Lowell, Massachusetts 01854 (United States); Schindler, Bryan J. [Leidos, Inc., P.O. Box 68, Gunpowder, Maryland 21010 (United States); Peterson, Gregory W. [U.S. Army Edgewood Chemical and Biological Center, Aberdeen Proving Ground, Maryland 21010 (United States)

    2016-03-15

    Construction and use of an ultraviolet light-emitting diode-based fluorometer for measuring photoluminescence (PL) from powder samples with a fiber optic probe is described. Fluorescence at two wavelengths is detected by miniature photomultiplier tubes, each equipped with a different band pass filter, whose outputs are analyzed by a microprocessor. Photoluminescent metal oxides and hydroxides, and other semiconducting nanoparticles, often undergo changes in their emission spectra upon exposure to reactive gases, and the ratio of the PL intensities at two wavelengths is diagnostic of adsorption. Use of this instrument for reactive gas sensing and gas filtration applications is illustrated by measuring changes in the PL ratio for zirconium hydroxide and zinc oxide particles upon exposure to air containing low concentrations of sulfur dioxide.

  5. Chemistry as a prism: a review of light-emitting materials having tunable emission wavelengths.

    Science.gov (United States)

    Kim, Eunha; Park, Seung Bum

    2009-11-02

    Photoluminescent materials have been extensively applied in various fields of science because of their numerous advantages, such as excellent sensitivity, good specificity, a large linear range of analysis, ease of handling, and so on. Many strategies have been used to understand and manipulate the photophysical properties of photoluminescent materials. This Focus Review describes recent progress focused on tuning the photophysical properties, especially the emission wavelengths of pi-conjugated oligomers, photoluminescent organometallic complexes, and fluorescent organic dyes by chemical modification.

  6. A multi-wavelength scattered light analysis of the dust grain population in the GG Tau circumbinary ring

    Energy Technology Data Exchange (ETDEWEB)

    Duchene, G; McCabe, C; Ghez, A; Macintosh, B

    2004-02-04

    We present the first 3.8 {micro}m image of the dusty ring surrounding the young binary system GG Tau, obtained with the W. M. Keck II 10m telescope's adaptive optics system. THis is the longest wavelength at which the ring has been detected in scattered light so far, allowing a multi-wavelength analysis of the scattering proiperties of the dust grains present in this protoplanetary disk in combination with previous, shorter wavelengths, HST images. We find that the scattering phase function of the dust grains in the disk is only weakly dependent on the wavelength. This is inconsistent with dust models inferred from observations of the interstellar medium or dense molecular clouds. In particular, the strongly forward-throwing scattering phase function observed at 3.8 {micro}m implies a significant increase in the population of large ({approx}> 1 {micro}m) grains, which provides direct evidence for grain growth in the ring. However, the grain size distribution required to match the 3.8 {micro}m image of the ring is incompatible with its published 1 {micro}m polarization map, implying that the dust population is not uniform throughout the ring. We also show that our 3.8 {micro}m image of the ring is incompatible with its published 1 {micro}m polarization map, implying that the dust population is not uniform throughout the ring. We also show that our 3.8 {micro}m scattered light image probes a deeper layer of the ring than previous shorter wavelength images, as demonstrated by a shift in the location of the inner edge of the disk's scattered light distribution between 1 and 3.8 {micro}m. We therefore propose a stratified structure for the ring in which the surface layers, located {approx} 50 AU above the ring midplane, contain dust grains that are very similar to those found in dense molecular clouds, while the region of the ring located {approx} 25 AU from the midplane contains significantly larger grains. This stratified structure is likely the result of

  7. Dim-light photoreceptor of chub mackerel Scomber japonicus and the photoresponse upon illumination with LEDs of different wavelengths.

    Science.gov (United States)

    Jang, Jun-Chul; Choi, Mi-Jin; Yang, Yong-Soo; Lee, Hyung-Been; Yu, Young-Moon; Kim, Jong-Myoung

    2016-06-01

    To study the absorption characteristics of rhodopsin, a dim-light photoreceptor, in chub mackerel (Scomber japonicus) and the relationship between light wavelengths on the photoresponse, the rod opsin gene was cloned into an expression vector, pMT4. Recombinant opsin was transiently expressed in COS-1 cells and reconstituted with 11-cis-retinal. Cells containing the regenerated rhodopsin were solubilized and subjected to UV/Vis spectroscopic analysis in the dark and upon illumination. Difference spectra from the lysates indicated an absorption maximum of mackerel rhodopsin around 500 nm. Four types of light-emitting diode (LED) modules with different wavelengths (red, peak 627 nm; cyan, 505 nm; blue, 442 nm; white, 447 + 560 nm) were constructed to examine their effects on the photoresponse in chub mackerel. Behavioral responses of the mackerels, including speed and frequencies acclimated in the dark and upon LED illumination, were analyzed using an underwater acoustic camera. Compared to an average speed of 22.25 ± 1.57 cm/s of mackerel movement in the dark, speed increased to 22.97 ± 0.29, 24.66 ± 1.06, 26.28 ± 2.28, and 25.19 ± 1.91 cm/s upon exposure to red, blue, cyan, and white LEDs, respectively. There were increases of 103.48 ± 1.58, 109.37 ± 5.29, 118.48 ± 10.82, and 109.43 ± 3.92 %, respectively, in the relative speed of the fishes upon illumination with red, blue, cyan, and white LEDs compared with that in the dark (set at 100 %). Similar rate of wavelength-dependent responses was observed in a frequency analysis. These results indicate that an LED emitting a peak wavelength close to an absorption maximum of rhodopsin is more effective at eliciting a response to light.

  8. Extraction of Surface Roughness from the Central δ-peak of Light Scattering Using a Multi-wavelength Ar+ Laser

    Institute of Scientific and Technical Information of China (English)

    LIU Deli; QI Dongping; CHENG Chuanfu

    2000-01-01

    In this paper, a new light scattering method for measuring the roughness of random surfaces is proposed. The method is based on the relation between the specularly reflected intensity Is, i.e., the central δ-peak intensity and wave vector component kz. The linear fit of the logarithm graph of the normalized central δ-peak intensity Isr versus k2z, whose variation is induced by changing illuminating wavelength, gives the square of the surface roughness w. The roughnesses of 6 silicon backside samples were measured.

  9. Steering light by a sub-wavelength metallic grating from transformation optics.

    Science.gov (United States)

    Xu, Yadong; Fu, Yangyang; Chen, Huanyang

    2015-07-17

    Transformation optics has shown great ability in designing devices with novel functionalities, such as invisibility cloaking. A recent work shows that it can also be used to design metasurfaces which usually come from the concept of phase discontinuities. However, metasurfaces from transformation optics have very complicated material parameters. Here in this work, we propose a practical design, a sub-wavelength metallic grating with discrete and gradient index materials. Such a design not only inherits some functionalities of metasurfaces from phase discontinuities, but also shows richer physics. Our work will also provide a guidance to recent activities of acoustic metasurfaces, especially for those made of extremely anisotropic metamaterials.

  10. First Light for the First Station of the Long Wavelength Array

    CERN Document Server

    Taylor, G B; Kassim, N E; Craig, J; Dowell, J; Wolfe, C N; Hartman, J; Bernardi, G; Clarke, T; Cohen, A; Dalal, N P; Erickson, W C; Hicks, B; Greenhill, L J; Jacoby, B; Lane, W; Lazio, J; Mitchell, D; Navarro, R; Ord, S M; Pihlstrom, Y; Polisensky, E; Ray, P S; Rickard, L J; Schinzel, F K; Schmitt, H; Sigman, E; Soriano, M; Stewart, K P; Stovall, K; Tremblay, S; Wang, D; Weiler, K W; White, S; Wood, D L

    2012-01-01

    The first station of the Long Wavelength Array (LWA1) was completed in April 2011 and is currently performing observations resulting from its first call for proposals in addition to a continuing program of commissioning and characterization observations. The instrument consists of 258 dual-polarization dipoles, which are digitized and combined into beams. Four independently-steerable dual-polarization beams are available, each with two "tunings" of 16 MHz bandwidth that can be independently tuned to any frequency between 10 MHz and 88 MHz. The system equivalent flux density for zenith pointing is ~3 kJy and is approximately independent of frequency; this corresponds to a sensitivity of ~5 Jy/beam (5sigma, 1 s); making it one of the most sensitive meter-wavelength radio telescopes. LWA1 also has two "transient buffer" modes which allow coherent recording from all dipoles simultaneously, providing instantaneous all-sky field of view. LWA1 provides versatile and unique new capabilities for Galactic science, puls...

  11. Effect of Longitudinally Varying Cloud Coverage on Visible Wavelength Reflected-Light Exoplanet Phase Curves

    CERN Document Server

    Webber, Matthew W; Marley, Mark; Morley, Caroline; Fortney, Jonathan; Cahoy, Kerri

    2015-01-01

    We use a planetary albedo model to investigate variations in visible wavelength phase curves of exoplanets. The presence of clouds on these exoplanets significantly alters their planetary albedo spectra. We confirm that non-uniform cloud coverage on the dayside of tidally locked exoplanets will manifest as changes to the magnitude and shift of the phase curve. In this work, we first investigate a test case of our model using a Jupiter-like planet, at temperatures consistent to 2.0 AU insolation from a solar type star, to consider the effect of H2O clouds. We then extend our application of the model to the exoplanet Kepler-7b and consider the effect of varying cloud species, sedimentation efficiency, particle size, and cloud altitude. We show that, depending on the observational filter, the largest possible shift of the phase curve maximum will be 2-10 deg for a Jupiter-like planet, and up to 30 deg (0.08 in fractional orbital phase) for hot-Jupiter exoplanets at visible wavelengths as a function of dayside cl...

  12. A Comparison between Two Heterodyne Light Sources Using Different Electro-Optic Modulators for Optical Temperature Measurements at Visible Wavelengths

    Directory of Open Access Journals (Sweden)

    Ruey-Ching Twu

    2010-10-01

    Full Text Available In this paper we have successfully demonstrated a z-propagating Zn-indiffused lithium niobate electro-optic modulator used for optical heterodyne interferometry. Compared to a commercial buck-type electro-optic modulator, the proposed waveguide-type modulator has a lower driving voltage and smaller phase variation while measuring visible wavelengths of 532 nm and 632.8 nm. We also demonstrate an optical temperature measurement system using a homemade modulator. The results show that the measurement sensitivities are almost the same values of 25 deg/°C for both the homemade and the buck-type modulators for a sensing light with a wavelength of 632.8 nm. Because photorefractive impacts are essential in the buck-type modulator at a wavelength of 532 nm, it is difficult to obtain reliable phase measurements, whereas the stable phase operation of the homemade one allows the measurement sensitivity to be improved up to 30 deg/°C with the best measurement resolution at about 0.07 °C for 532 nm.

  13. Complete Control of Polarization and Phase of Light with High Efficiency and Sub-wavelength Spatial Resolution

    CERN Document Server

    Arbabi, Amir; Bagheri, Mahmood; Faraon, Andrei

    2014-01-01

    Meta-surfaces are planar structures that locally change polarization, phase, and amplitude of light, thus enabling flat, lithographically patterned free-space optical components with functionalities controlled by design. Several types of meta-surfaces have been reported, but low efficiency and the inability to provide simultaneous phase and polarization control have limited their applications. Here we demonstrate a platform based on high-contrast dielectric elliptical nano-posts providing complete and efficient control of polarization and phase with sub-wavelength spatial resolution. The unprecedented freedom in manipulating light not only enables realization of conventional free-space transmissive optical elements such as phase-plates, wave-plates and beam-splitters, but also elements with novel functionalities such as general polarization switchable phase holograms and arbitrary vector beam generators which will change the design paradigms for free-space optical systems.

  14. An optical system adopting liquid crystals with electrical tunability of wavelength and energy density for low level light therapy

    Science.gov (United States)

    Chang, Chia-Ming; Wang, Yu-Jen; Chen, Hung-Shan; Lin, Yi-Hsin; Srivastava, Abhishek K.; Chigrinov, Vladimir G.

    2015-09-01

    We have developed a bistable negative lens by integrating a polarization switch of ferroelectric liquid crystals (FLCs) with a passively anisotropic focusing element. The proposed lens not only exhibits electrically tunable bistability but also fast response time of sub-milliseconds, which leads to good candidate of optical component in optical system for medical applications. In this paper, we demonstrate an optical system consisting of two FLC phase retarders and one LC lenses that exhibits both of electrically tunable wavelength and size of exposure area. The operating principles and the experimental results are discussed. The tunable spectrum, exposure area size and tunable irradiance are illustrated. Compared to conventional lenses with mechanical movements in the medical light therapy system, our electrically switchable optical system is more practical in the portable applications of light therapy (LLLT).

  15. EFFECT OF LONGITUDE-DEPENDENT CLOUD COVERAGE ON EXOPLANET VISIBLE WAVELENGTH REFLECTED-LIGHT PHASE CURVES

    Energy Technology Data Exchange (ETDEWEB)

    Webber, Matthew W.; Lewis, Nikole K.; Cahoy, Kerri [Department of Earth, Atmospheric, and Planetary Sciences. Massachusetts Institute of Technology (MIT) Cambridge, MA (United States); Marley, Mark [NASA Ames Research Center, Moffett Field, CA (United States); Morley, Caroline; Fortney, Jonathan J. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)

    2015-05-10

    We use a planetary albedo model to investigate variations in visible wavelength phase curves of exoplanets. Thermal and cloud properties for these exoplanets are derived using one-dimensional radiative-convective and cloud simulations. The presence of clouds on these exoplanets significantly alters their planetary albedo spectra. We confirm that non-uniform cloud coverage on the dayside of tidally locked exoplanets will manifest as changes to the magnitude and shift of the phase curve. In this work, we first investigate a test case of our model using a Jupiter-like planet, at temperatures consistent to 2.0 AU insolation from a solar type star, to consider the effect of H{sub 2}O clouds. We then extend our application of the model to the exoplanet Kepler-7b and consider the effect of varying cloud species, sedimentation efficiency, particle size, and cloud altitude. We show that, depending on the observational filter, the largest possible shift of the phase curve maximum will be ∼2°–10° for a Jupiter-like planet, and up to ∼30° (∼0.08 in fractional orbital phase) for hot-Jupiter exoplanets at visible wavelengths as a function of dayside cloud distribution with a uniformly averaged thermal profile. The models presented in this work can be adapted for a variety of planetary cases at visible wavelengths to include variations in planet–star separation, gravity, metallicity, and source-observer geometry. Finally, we tailor our model for comparison with, and confirmation of, the recent optical phase-curve observations of Kepler-7b with the Kepler space telescope. The average planetary albedo can vary between 0.1 and 0.6 for the 1300 cloud scenarios that were compared to the observations. Many of these cases cannot produce a high enough albedo to match the observations. We observe that smaller particle size and increasing cloud altitude have a strong effect on increasing albedo. In particular, we show that a set of models where Kepler-7b has roughly half of

  16. Light wavelength influence on surface plasmon resonance in citrate-gold nanosystems

    Science.gov (United States)

    Lupusoru, Raoul-Vasile; Pricop, Daniela A.; Andries, Maria; Creanga, Dorina

    2016-12-01

    Citrate-gold particles were yielded according to classical method of auric salt reduction in two different synthesis media aiming to use them further applications in biomedical and environmental domains. The analysis of citrate-gold interaction was done through UV-vis and IR spectroscopy as well as by Transmission Electron Microscopy (TEM) and Dark Field (DF) Microscopy. Average particle size was higher for citrate-gold NPs synthesized with NaOH (32.5 nm) than for NPs synthesized with NaCl (15 nm). Dimensional histograms of one year aged colloidal suspensions presented mean size of 29 nm and respectively 18 nm. The influence of 90 min light exposure, analyzed by UV-vis, evidenced that for both NaOH synthesis protocol and NaCl protocol, plasmon band maxima at 528 nm and respectively 538 nm didn't changed, neither for white nor for green light. For one year aged samples this band shifted to 540 nm for green light irradiation in the case of citrate-gold NPs synthesized with NaOH. Also, for these NPs, both green and white light exposures resulted in plasmon band intensity changes for native as well as for aged samples. FTIR investigation showed also different changes at the level of the intensity of main vibration bands of citrate-gold after exposure to light, suggesting stronger adsorption of citrate in the case of NaCl addition in the initial reaction medium than in the case of NaOH. Finally, the utilization of NaCl in the synthesis protocol seems to favor the synthesis of more stable and lower toxicity colloidal suspensions, both during time and under the light irradiation.

  17. Short-wavelength light beam in situ monitoring growth of InGaN/GaN green LEDs by MOCVD.

    Science.gov (United States)

    Sun, Xiaojuan; Li, Dabing; Song, Hang; Chen, Yiren; Jiang, Hong; Miao, Guoqing; Li, Zhiming

    2012-05-31

    In this paper, five-period InGaN/GaN multiple quantum well green light-emitting diodes (LEDs) were grown by metal organic chemical vapor deposition with 405-nm light beam in situ monitoring system. Based on the signal of 405-nm in situ monitoring system, the related information of growth rate, indium composition and interfacial quality of each InGaN/GaN QW were obtained, and thus, the growth conditions and structural parameters were optimized to grow high-quality InGaN/GaN green LED structure. Finally, a green LED with a wavelength of 509 nm was fabricated under the optimal parameters, which was also proved by ex situ characterization such as high-resolution X-ray diffraction, photoluminescence, and electroluminescence. The results demonstrated that short-wavelength in situ monitoring system was a quick and non-destroyed tool to provide the growth information on InGaN/GaN, which would accelerate the research and development of GaN-based green LEDs.

  18. The Imprint of The Extragalactic Background Light in the Gamma-Ray Spectra of Blazars

    CERN Document Server

    ,

    2012-01-01

    The light emitted by stars and accreting compact objects through the history of the Universe is encoded in the intensity of the extragalactic background light (EBL). Knowledge of the EBL is important to understand the nature of star formation and galaxy evolution, but direct measurements of the EBL are lim- ited by Galactic and other foreground emissions. Here we report an absorption feature seen in the combined spectra of a sample of gamma-ray blazars out to a redshift of z$\\sim$1.6. This feature is caused by attenuation of gamma rays by the EBL at optical to UV frequencies, and allowed us to measure the EBL flux density in this frequency band.

  19. Lights and shadows: multi-wavelength analysis of young stellar objects and their protoplanetary discs

    Science.gov (United States)

    Rigon, Laura

    2016-03-01

    Stars form from the collapse of molecular clouds and evolve in an environment rich in gas and dust before becoming Main Sequence stars. During this phase, characterised by the presence of a protoplanetary disc, stars manifest changes in the structure and luminosity. This thesis performs a multi-wavelength analysis, from optical to mm range, on a sample of young stars (YSOs), mainly Classical T Tauri (CTTS). The purpose is to study optical and infrared variability and its relation with the protoplanetary disc. Longer wavelength, in the mm range, are used instead to investigate the evolution of the disc, in terms of dust growth. In optical, an F-test on a sample of 39 CTTS reveals that 67% of the stars are variable. The variability, quantified through pooled sigma, is visible both in magnitude amplitudes and changes over time. Time series analysis applied on the more variable stars finds the presence of quasi periodicity, with periods longer than two weeks, interpreted either as eclipsing material in the disc happening on a non-regular basis, or as a consequence of star-disc interaction via magnetic field lines. The variability of YSOs is confirmed also in infrared, even if with lower amplitude. No strong correlations are found between optical and infrared variability, which implies a different cause or a time shift in the two events. By using a toy model to explore their origin, I find that infrared variations are likely to stem from emissions in the inner disc. The evolution of discs in terms of dust growth is confirmed in most discs by the analysis of the slope of the spectral energy distribution (SED), after correcting for wind emission and optical depth effects. However, the comparison with a radiative transfer model highlights that a number of disc parameters, in particular disc masses and temperature, dust size distribution and composition, can also affect the slope of the SED.

  20. Harnessing structural darkness in the visible and infrared wavelengths for a new source of light

    KAUST Repository

    Huang, Jianfeng

    2015-10-19

    Engineering broadband light absorbers is crucial to many applications, including energy-harvesting devices and optical interconnects. The performances of an ideal absorber are that of a black body, a dark material that absorbs radiation at all angles and polarizations. Despite advances in micrometre-thick films, the absorbers available to date are still far from an ideal black body. Here, we describe a disordered nanostructured material that shows an almost ideal black-body absorption of 98-99% between 400 and 1,400 nm that is insensitive to the angle and polarization of the incident light. The material comprises nanoparticles composed of a nanorod with a nanosphere of 30 nm diameter attached. When diluted into liquids, a small concentration of nanoparticles absorbs on average 26% more than carbon nanotubes, the darkest material available to date. By pumping a dye optical amplifier with nanosecond pulses of 100 mW power, we harness the structural darkness of the material and create a new type of light source, which generates monochromatic emission (5 nm wide) without the need for any resonance. This is achieved through the dynamics of light condensation in which all absorbed electromagnetic energy spontaneously generates single-colour energy pulses. © 2016 Macmillan Publishers Limited. All rights reserved.

  1. Harnessing structural darkness in the visible and infrared wavelengths for a new source of light

    Science.gov (United States)

    Huang, Jianfeng; Liu, Changxu; Zhu, Yihan; Masala, Silvia; Alarousu, Erkki; Han, Yu; Fratalocchi, Andrea

    2016-01-01

    Engineering broadband light absorbers is crucial to many applications, including energy-harvesting devices and optical interconnects. The performances of an ideal absorber are that of a black body, a dark material that absorbs radiation at all angles and polarizations. Despite advances in micrometre-thick films, the absorbers available to date are still far from an ideal black body. Here, we describe a disordered nanostructured material that shows an almost ideal black-body absorption of 98-99% between 400 and 1,400 nm that is insensitive to the angle and polarization of the incident light. The material comprises nanoparticles composed of a nanorod with a nanosphere of 30 nm diameter attached. When diluted into liquids, a small concentration of nanoparticles absorbs on average 26% more than carbon nanotubes, the darkest material available to date. By pumping a dye optical amplifier with nanosecond pulses of ˜100 mW power, we harness the structural darkness of the material and create a new type of light source, which generates monochromatic emission (˜5 nm wide) without the need for any resonance. This is achieved through the dynamics of light condensation in which all absorbed electromagnetic energy spontaneously generates single-colour energy pulses.

  2. Constraints on the Extragalactic Background Light from Very High Energy Gamma-Ray Observations of Blazars

    OpenAIRE

    Finke, Justin D.; Razzaque, Soebur

    2009-01-01

    The extragalactic background light (EBL) from the infrared to the ultraviolet is difficult to measure directly, but can be constrained with a variety of methods. EBL photons absorb gamma-rays from distant blazars, allowing one to use blazar spectra from atmospheric Cherenkov telescopes (ACTs) to put upper limits on the EBL by assuming a blazar source spectrum. Here we apply a simple technique, similar to the one developed by Schroedter (2005), to the most recent very-high energy (VHE) gamma-r...

  3. Assembling the Infrared Extragalactic Background Light with CIBER-2: Probing Inter-Halo Light and the Epoch of Reionization.

    Science.gov (United States)

    Bock, James

    We propose to carry out a program of observations with the Cosmic Infrared Background Experiment (CIBER-2). CIBER-2 is a near-infrared sounding rocket experiment designed to measure spatial fluctuations in the extragalactic background light. CIBER-2 scientifically follows on the detection of fluctuations with the CIBER-1 imaging instrument, and will use measurement techniques developed and successfully demonstrated by CIBER-1. With high-sensitivity, multi-band imaging measurements, CIBER-2 will elucidate the history of interhalo light (IHL) production and carry out a deep search for extragalactic background fluctuations associated with the epoch of reionization (EOR). CIBER-1 has made high-quality detections of large-scale fluctuations over 4 sounding rocket flights. CIBER-1 measured the amplitude and spatial power spectrum of fluctuations, and observed an electromagnetic spectrum that is close to Rayleigh-Jeans, but with a statistically significant turnover at 1.1 um. The fluctuations cross-correlate with Spitzer images and are significantly bluer than the spectrum of the integrated background derived from galaxy counts. We interpret the CIBER-1 fluctuations as arising from IHL, low-mass stars tidally stripped from their parent galaxies during galaxy mergers. The first generation of stars and their remnants are likely responsible for the for the reionization of the intergalactic medium, observed to be ionized out to the most distant quasars at a redshift of 6. The total luminosity produced by first stars is uncertain, but a lower limit can be placed assuming a minimal number of photons to produce and sustain reionization. This 'minimal' extragalactic background component associated with reionization is detectable in fluctuations at the design sensitivity of CIBER-2. The CIBER-2 instrument is optimized for sensitivity to surface brightness in a short sounding rocket flight. The instrument consists of a 28 cm wide-field telescope operating in 6 spectral bands

  4. Biohydrogen production by isolated halotolerant photosynthetic bacteria using long-wavelength light-emitting diode (LW-LED)

    Energy Technology Data Exchange (ETDEWEB)

    Kawagoshi, Yasunori; Oki, Yukinori; Nakano, Issei; Fujimoto, Aya [Graduate School of Science and Technology, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555 (Japan); Takahashi, Hirokazu [Environmental Business DivisionDaiki Ataka Engineering Co. Ltd., 2-1-9 Nishiku-Urihori, Osaka 550-0012 (Japan)

    2010-12-15

    Biohydrogen is expected as one of the alternative energy to fossil fuel. In this study, halotolerant photosynthetic hydrogen producing bacteria (ht-PHB) were isolated from a sediment of tideland, and hydrogen gas (H{sub 2}) production by isolated ht-PHB from mixed short-chain fatty acids (SFAs) using a long-wavelength light emitting diode (LW-LED) was investigated. The isolated ht-PHB grow on a culture containing three kinds of SFAs (lactic acid, acetic acid, butyric acid) and produced H{sub 2} with their complete consumption at NaCl concentration in the 0-3% range in the light of tungsten lamp. The isolated ht-PHB was phylogenetically identified as Rhodobacter sp. KUPB1. The KUPB1 showed well growth and H{sub 2} production even under LW-LED light irradiation, indicating that LW-LED is quite useful as an energy-saving light source for photosynthetic H{sub 2} production. (author)

  5. Synergistic Effects of Long Wavelength Ultraviolet A1 and Visible Light on Pigmentation and Erythema.

    Science.gov (United States)

    Kohli, I; Chaowattanapanit, S; Mohammad, T F; Nicholson, C L; Fatima, S; Jacobsen, G; Kollias, N; Lim, H W; Hamzavi, I H

    2017-09-06

    Visible light (VL) induces multiple cutaneous effects. Sunscreen testing protocols recommended by regulatory bodies throughout the world require the use of solar simulators with spectral output in ultraviolet (UV) domain only. However, sunlight contains VL and infrared radiation also. This study aimed to evaluate the contributions of VL and UVA on pigmentation and erythema, and optimize parameters for in-vivo testing. Ten subjects with Fitzpatrick skin phototype IV-VI were enrolled. Subjects were irradiated on their back with VL using two light sources: one containing pure VL and one containing VL with less than 0.5% UVA1 (VL+UVA1). Four different irradiances were administered to investigate reciprocity behaviour. Assessments, including photography, investigator's global assessment, colorimetry, and spectroscopy, were performed immediately, 24 hours, 7 days and 14 days post-irradiation. Pigmentation was observed with both light sources; however, pigment intensity was greater with VL+UVA1 than pure VL. Reciprocity was observed in pure VL sites, but not VL+UVA1. Variation in spectral output had greater impact on pigment intensity than irradiance. Clinical erythema was observed on the VL+UVA1 side, but not on the pure VL side. Protocol for testing photoprotection product efficacy against VL induced effects has been proposed. The findings suggest a synergistic relationship between VL and UVA1 and emphasize the need for developing means of photoprotection against VL. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  6. Let there be no light: the effect of bedside light on sleep quality and background electroencephalographic rhythms

    OpenAIRE

    Cho, Jounhong Ryan; Joo, Eun Yeon; Koo, Dae Lim; Hong, Seung Bong

    2013-01-01

    Objectives: Artificial lighting has been beneficial to society, but unnecessary light exposure at night may cause various health problems. We aimed to investigate how whole-night bedside light can affect sleep quality and brain activity. Patients and methods: Ten healthy sleepers underwent two polysomnography (PSG) sessions, one with the lights off and one with the lights on. PSG variables related to sleep quality were extracted and compared between lights-off and lights-on sleep. Sp...

  7. Toxicity of chlorophyllin in different wavelengths of visible light against Fasciola gigantica larvae.

    Science.gov (United States)

    Singh, Divya Jyoti; Singh, D K

    2015-03-01

    Toxicity of chlorophyllin against redia and cercaria larvae of Fasciola gigantica was studied under irradiation of visible light. Highest and lowest toxicity of chlorophyllin against both larvae was noted under red (redia - 8 h LC₅₀ 7.88 mg/10 mL and cercaria - 11.99 mg/10 mL) and green (redia - 8 h LC₅₀ 32.12 mg/10 mL and cercaria - 8 h LC₅₀ 43.80 mg/10 mL) light irradiation respectively. The highest toxicity of chlorophyllin under red light irradiation against redia (8h LC₅₀ 7.88 mg/10 mL)/cercaria (8h LC₅₀ 11.99 mg/10 mL) was followed by white (8 h LC₅₀ redia - 20.48 mg/10 mL, 8 h LC₅₀ cercaria - 18.0 3mg/10 mL), blue (8 h LC₅₀ redia - 33.10 mg/10 mL/ 8 h LC₅₀ cercaria - 19.98 mg/10 mL) and yellow (8 h LC₅₀ redia - 23.87 mg/10 mL/ 8 h LC₅₀ cercaria - 23.48 mg/10 mL). Chlorophyllin treatment in darkness (control I) and without treatment of chlorophyllin, while all other conditions were same as treatment group (control II) caused no mortality of redia/cercaria larva. Chlorophyllin might be a promising new safe strategy to replace synthetic larvicide in fasciolosis control programme.

  8. Response of vegetable organisms to quasi-monochromatic light of different duration, intensity and wavelength

    Energy Technology Data Exchange (ETDEWEB)

    Budagovsky, A V; Solovykh, N V [I.V.Michurin All-Russian Recearch Institute of Fruit Crops Genetics and Breeding (Russian Federation); Budagovskaya, O N [I.V.Michurin All-Russia Research and Development Institute of Gardening, Michurinsk, Tambov region (Russian Federation); Budagovsky, I A [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    2015-04-30

    By the example of vegetable organisms differing in structure and functional properties it is shown that their response to the action of quasi-monochromatic light from laser sources does not obey the Bunsen – Roscoe dose law. The dependence of biological effect on the irradiation time has the multimodal (multiextremal) form with alternating maxima and minima of the stimulating effect. Such a property manifests itself in the spectral ranges, corresponding to photoinduced conversion of chromoproteins of photocontrol systems and is probably related to the cyclic variations of metabolic activity in vegetable cells. (biophotonics)

  9. Development of at-wavelength metrology using grating-based shearing interferometry at Diamond Light Source

    Science.gov (United States)

    Wang, Hongchang; Berujon, Sebastien; Sawhney, Kawal

    2013-03-01

    The grating-based shearing interferometer has been established and further developed on B16 at Diamond Light Source. The beamline performances of both an X-ray plane mirror and a compound refractive lens (CRL) have been investigated using this technique. The slope error of the X-ray mirror was retrieved from the wavefront phase gradient, which was measured using two different processing schemes: phase stepping and moiré fringe analysis. The interferometer has demonstrated a high sensitivity with sub-microradian accuracy. Some of the advantages, disadvantages and limitations for the two approaches will also be presented.

  10. The Extragalactic Background Light and the Gamma-ray Opacity of the Universe

    Science.gov (United States)

    Dwek, Eli; Krennrich, Frank

    2012-01-01

    The extragalactic background light (EBL) is one of the fundamental observational quantities in cosmology. All energy releases from resolved and unresolved extragalactic sources, and the light from any truly diffuse background, excluding the cosmic microwave background (CMB), contribute to its intensity and spectral energy distribution. It therefore plays a crucial role in cosmological tests for the formation and evolution of stellar objects and galaxies, and for setting limits on exotic energy releases in the universe. The EBL also plays an important role in the propagation of very high energy gamma-rays which are attenuated en route to Earth by pair producing gamma-gamma interactions with the EBL and CMB. The EBL affects the spectrum of the sources, predominantly blazars, in the approx 10 GeV to 10 TeV energy regime. Knowledge of the EBL intensity and spectrum will allow the determination of the intrinsic blazar spectrum in a crucial energy regime that can be used to test particle acceleration mechanisms and VHE gamma-ray production models. Conversely, knowledge of the intrinsic gamma-ray spectrum and the detection of blazars at increasingly higher redshifts will set strong limits on the EBL and its evolution. This paper reviews the latest developments in the determination of the EBL and its impact on the current understanding of the origin and production mechanisms of gamma-rays in blazars, and on energy releases in the universe. The review concludes with a summary and future directions in Cherenkov Telescope Array techniques and in infrared ground-based and space observatories that will greatly improve our knowledge of the EBL and the origin and production of very high energy gamma-rays.

  11. Background light in potential sites for the ANTARES undersea neutrino telescope

    CERN Document Server

    Amram, P; Aslanides, Elie; Aubert, Jean-Jacques; Azoulay, R; Basa, S; Benhammou, Ya; Bernard, F; Bertin, V; Billault, M; Blanc, P E; Blanc, F; Bland, R; Blondeau, F; Bottu, N; Boulesteix, J; Brooks, B; Brunner, J; Calzas, A; Cârloganu, C; Carmona, F E; Carr, J; Carton, P H; Cartwright, S L; Cases, R; Cassol, F; Compere, C; Cooper, S; Coustillier, G; De Botton, N R; Deck, P; Desages, F E; Destelle, J J; Dispau, G; Drogou, J F; Drouhin, F; Duval, P Y; Feinstein, F; Festy, D; Fopma, J; Fuda, J L; Goret, P; Gosset, L G; Gournay, J F; Hernández, J J; Herrouin, G; Hubaut, F; Hubbard, John R; Huss, D; Jaquet, M; Jelley, N A; Kajfasz, E; Karolak, M; Kouchner, A; Kudryavtsev, V A; Lachartre, D; Lafoux, H; Lamare, P; Languillat, J C; Laugier, D; Laugier, J P; Le Guen, Y; Le Provost, H; Le Van-Suu, A; Lemoine, L; Liotard, P L; Loucatos, Sotirios S; Magnier, P; Marcelin, M; Martin, L; Massol, A; Mazeau, B; Mazure, A; Mazéas, F; McMillan, J; Millot, C; Mols, P; Montanet, François; Morel, J P; Moscoso, L; Navas, S; Olivetto, C; Palanque-Delabrouille, Nathalie; Pallarès, A; Payre, P; Perrin, P; Pohl, A; Poinsignon, J; Potheau, R; Queinec, Y; Racca, C; Raymond, M; Rolin, J F; Sacquin, Yu; Schuller, J P; Schuster, W; Spooner, N J C; Stolarczyk, T; Tabary, A; Talby, M; Tao, Charling; Tayalati, Y; Thompson, L F; Triay, R; Tzvetanov, T; Valdy, P; Vernin, P; Vigeolas, E; Vignaud, D; Vilanova, D; Wark, D; Zghiche, A; Zúñiga, J

    2000-01-01

    The ANTARES collaboration has performed a series of {\\em in situ} measurements to study the background light for a planned undersea neutrino telescope. Such background can be caused by $^{40}$K decays or by biological activity. We report on measurements at two sites in the Mediterranean Sea at depths of 2400~m and 2700~m, respectively. Three photomultiplier tubes were used to measure single counting rates and coincidence rates for pairs of tubes at various distances. The background rate is seen to consist of three components: a constant rate due to $^{40}$K decays, a continuum rate that varies on a time scale of several hours simultaneously over distances up to at least 40~m, and random bursts a few seconds long that are only correlated in time over distances of the order of a meter. A trigger requiring coincidences between nearby photomultiplier tubes should reduce the trigger rate for a neutrino telescope to a manageable level with only a small loss in efficiency.

  12. Background light in potential sites for the ANTARES undersea neutrino telescope

    Science.gov (United States)

    Amram, P.; Anvar, S.; Aslanides, E.; Aubert, J.-J.; Azoulay, R.; Basa, S.; Benhammou, Y.; Bernard, F.; Bertin, V.; Billault, M.; Blanc, P.-E.; Blanc, F.; Bland, R. W.; Blondeau, F.; Bottu, N.; Boulesteix, J.; Brooks, B.; Brunner, J.; Calzas, A.; Carloganu, C.; Carmona, E.; Carr, J.; Carton, P.-H.; Cartwright, S.; Cases, R.; Cassol, F.; Compere, C.; Cooper, S.; Coustillier, G.; de Botton, N.; Deck, P.; Desages, F. E.; Destelle, J.-J.; Dispau, G.; Drogou, J. F.; Drouhin, F.; Duval, P.-Y.; Feinstein, F.; Festy, D.; Fopma, J.; Fuda, J.-L.; Goret, P.; Gosset, L.; Gournay, J.-F.; Hernández, J. J.; Herrouin, G.; Hubaut, F.; Hubbard, J. R.; Huss, D.; Jaquet, M.; Jelley, N.; Kajfasz, E.; Karolak, M.; Kouchner, A.; Kudryavtsev, V.; Lachartre, D.; Lafoux, H.; Lamare, P.; Languillat, J.-C.; Laugier, D.; Laugier, J.-P.; Le Guen, Y.; Le Provost, H.; Le van Suu, A.; Lemoine, L.; Liotard, P. L.; Loucatos, S.; Magnier, P.; Macelin, M.; Martin, L.; Massol, A.; Mazeau, B.; Mazure, A.; Mazéas, F.; McMillan, J.; Millot, C.; Mols, P.; Montanet, F.; Morel, J. P.; Moscoso, L.; Navas, S.; Olivetto, C.; Palanque-Delabrouille, N.; Pallares, A.; Payre, P.; Perrin, P.; Pohl, A.; Poinsignon, J.; Potheau, R.; Queinec, Y.; Racca, C.; Raymond, M.; Rolin, J. F.; Sacquin, Y.; Schuller, J.-P.; Schuster, W.; Spooner, N.; Stolarczyk, T.; Tabary, A.; Talby, M.; Tao, C.; Tayalati, Y.; Thompson, L. F.; Triay, R.; Tzvetanov, T.; Valdy, P.; Vernin, P.; Vigeolas, E.; Vignaud, D.; Vilanova, D.; Wark, D.; Zghiche, A.; Zúñiga, J.; ANTARES Collaboration

    2000-05-01

    The ANTARES collaboration has performed a series of in-situ measurements to study the background light for a planned undersea neutrino telescope. Such background can be caused by 40K decays or by biological activity. We report on measurements at two sites in the Mediterranean Sea at depths of 2400 m and 2700 m, respectively. Three photomultiplier tubes were used to measure single counting rates and coincidence rates for pairs of tubes at various distances. The background rate is seen to consist of three components: a constant rate due to 40K decays, a continuum rate that varies on a time scale of several hours simultaneously over distances up to at least 40 m, and random bursts a few seconds long that are only correlated in time over distances of the order of a meter. A trigger requiring coincidences between nearby photomultiplier tubes should reduce the trigger rate for a neutrino telescope to a manageable level with only a small loss in efficiency.

  13. Phototropin 1 and cryptochrome action in response to green light in combination with other wavelengths.

    Science.gov (United States)

    Wang, Yihai; Maruhnich, Stefanie A; Mageroy, Melissa H; Justice, Jessica Rodean; Folta, Kevin M

    2013-01-01

    Genetic studies have shown the effects of various photoreceptors on early photomorphogenic processes, defining the precise time course of red (RL), far-red (FrL) and blue light (BL) action. In this study, the effect of green wavebands in conjunction with these responses is examined. Longer-term (end point; 24-96 h) analysis of hypocotyl elongation in enriched green environments shows an increase in growth compared to seedlings under blue, red or both together. The effect was only observed at lower fluence rates (Green light (GL) treatments antagonize RL and FrL-mediated hypocotyl inhibition. The GL opposition of RL responses persists in phyA, phyB, cry1cry2 and phot2 mutants. The response requires phot1 and NPH3, suggesting that this is not a GL response, but instead a response to extremely low-fluence rate BL. Tests with dim BL (green environments may adjust RL and BL photomorphogenic responses through both the crys and phot1 receptors, and define a new role for phot1 in stem growth promotion.

  14. A wide-angle metamaterial narrow-band-stop filter for 532 nm wavelength green light

    CERN Document Server

    Yue, Liyang; Yan, Bing; Tung, Nguyen Thanh; Lam, Vu Dinh; Wang, Zengbo

    2016-01-01

    Traditional optical interference narrow-band-stop filters do not possess wide-angle property, because peaks and troughs of filter spectrum would be moved at a non-normal angle of incidence (AOI), which could result in functional failure in particular cases, e.g. blocking of laser for pilot in cockpit during premeditated laser pointer direct. For this reason, we designed a wide-angle metamaterial narrow-band-stop filter assembled by cross shaped units to block 532 nm green light, which is firstly reported in the world. Unnecessary shift of spectrum caused by AOI change is effectively inhibited, and angular tolerance of wide-angle capability achieves to 35 degrees non-normal AOIs.

  15. Effects of melatonin and green-wavelength LED light on the physiological stress and immunity of goldfish, Carassius auratus, exposed to high water temperature.

    Science.gov (United States)

    Jung, Seo Jin; Kim, Na Na; Choi, Young Jae; Choi, Ji Yong; Choi, Young-Ung; Heo, Youn Seong; Choi, Cheol Young

    2016-10-01

    This study investigated the effects of increasing water temperature (22-30 °C) on the physiological stress response and immunity of goldfish, Carassius auratus, and the ability of green light-emitting diode (LED) irradiation or melatonin injections to mitigate this temperature-induced stress. To evaluate the effects of either green-wavelength LED light or melatonin on stress in goldfish, we measured plasma triiodothyronine (T3), thyroxine (T4), and thyroid hormone receptor (TR) mRNA expression; plasma cortisol and glucose; and immunoglobulin M (IgM) and lysozyme mRNA expression. The thyroid hormone activities, TR mRNA expression, and plasma cortisol and glucose were higher in goldfish exposed to high-temperature water, but were lower after exposure to melatonin or green-wavelength LED light. Lysozyme mRNA expression and plasma IgM activity and protein expression were lower after exposure to high water temperatures and higher after melatonin or green-wavelength LED light treatments. Therefore, high water temperature induced stress and decreased immunity; however, green-wavelength LED light and melatonin treatments mitigated the effects of stress and enhanced immunity. The benefits of melatonin decreased with time, whereas those of green-wavelength LED treatment did not.

  16. Modeling the multi-wavelength light curves of PSR B1259-63/SS 2883

    CERN Document Server

    Kong, S W; Huang, Y F; Cheng, K S

    2011-01-01

    PSR B1259-63/SS 2883 is a binary system in which a 48-ms pulsar orbits around a Be star in a high eccentric orbit with a long orbital period of about 3.4 yr. Extensive broadband observational data are available for this system from radio band to very high energy (VHE) range. The multi-frequency emission is unpulsed and nonthermal, and is generally thought to be related to the relativistic electrons accelerated from the interaction between the pulsar wind and the stellar wind, where X-ray emission is from the synchrotron process and the VHE emission is from the inverse Compton (IC) scattering process. Here a shocked wind model with variation of the magnetic parameter $\\sigma$ is developed for explaining the observations. By choosing proper param- eters, our model could reproduce two-peak profile in X-ray and TeV light curves. The effect of the disk exhibits an emission and an absorption components in the X-ray and TeV bands respectively. We suggest that some GeV flares will be produced by Doppler boosting the ...

  17. Effect of high wavelengths low intensity light during dark period on physical exercise performance, biochemical and haematological parameters of swimming rats.

    Science.gov (United States)

    Beck, W; Gobatto, C

    2016-03-01

    Nocturnal rodents should be assessed at an appropriate time of day, which leads to a challenge in identifying an adequate environmental light which allows animal visualisation without perturbing physiological homeostasis. Thus, we analysed the influence of high wavelength and low intensity light during dark period on physical exercise and biochemical and haematological parameters of nocturnal rats. We submitted 80 animals to an exhaustive exercise at individualised intensity under two different illuminations during dark period. Red light (> 600 nm; experiments.

  18. Aerosol source apportionment based on multi-wavelength photoacoustic light absorption measurements: a simulation method for system's optimisation

    Science.gov (United States)

    Simon, Károly; Ajtai, Tibor; Kiss-Albert, Gergely; Utry, Noémi; Pintér, Máté; Szabó, Gábor; Bozóki, Zoltán

    2017-04-01

    Aerosol source apportionment is currently one of the outstanding challenges for environmental monitoring. In most cases atmospheric aerosol is a heterogeneous mixture as it typically originates from various sources. Consequently, each aerosol type has distinct chemical and physical properties. Contrary to chemical properties, optical absorption and size distribution of airborne particles can be measured in real time with high time resolution i.e. their measurement facilitates real time source apportionment (Favez et al (2009), Ajtai et al (2011), Favez et al (2010)). The wavelength dependency of the optical absorption coefficient (OAC) is usually characterised by the Absorption Angström Exponent (AAE). So far, the selection of light sources (lasers) into a photoacoustic aerosol measuring system was based on rule of thumb type estimations only. Recently, we proposed a simulation method that can be used to estimate the accuracy of aerosol source apportionment in case of a dual wavelength photoacoustic system (Simon et al., (2017)). This simulation is based on the assumption that the atmospheric aerosol load is dominated by two distinct sources and each of them is strongly light absorbing with specific AAE values. This is a typical scenario e.g. for urban measurements under wintry conditions when dominating aerosol sources are fossil fuel and wood burning with characteristic AAE 1 and 2, respectively. The wavelength pair of 405 and 1064 nm was found to be optimal for source apportionment in this case. In the presented study we investigated the situation when there are aerosol components with only slightly different AAE values and searched for a photoacoustic system which is optimal for distinguishing these components. Ajtai, T.; Filep, Á.; Utry, N.; Schnaiter, M.; Linke, C.; Bozóki, Z.; Szabó, G. and Leisner T. (2011) Journal of Aerosol Science 42, 859-866. Favez, O.; Cachier, H.; Sciare, J.; Sarda-Estève, R. and Martinon, L. (2009) Atmospheric Environment 43

  19. Highly photoresponsive and wavelength-selective circularly-polarized-light detector based on metal-oxides hetero-chiral thin film.

    Science.gov (United States)

    Lee, Seung Hee; Singh, Dhruv Pratap; Sung, Ji Ho; Jo, Moon-Ho; Kwon, Ki Chang; Kim, Soo Young; Jang, Ho Won; Kim, Jong Kyu

    2016-01-22

    A highly efficient circularly-polarized-light detector with excellent wavelength selectivity is demonstrated with an elegant and simple microelectronics-compatible way. The circularly-polarized-light detector based on a proper combination of the geometry-controlled TiO2-SnO2 hetero-chiral thin film as an effective chiroptical filter and the Si active layer shows excellent chiroptical response with external quantum efficiency as high as 30% and high helicity selectivity of ~15.8% in an intended wavelength range. Furthermore, we demonstrated the ability of manipulating both bandwidth and responsivity of the detector simultaneously in whole visible wavelength range by a precise control over the geometry and materials constituting hetero-chiral thin film. The high efficiency, wavelength selectivity and compatibility with conventional microelectronics processes enabled by the proposed device can result in remarkable developments in highly integrated photonic platforms utilizing chiroptical responses.

  20. Highly photoresponsive and wavelength-selective circularly-polarized-light detector based on metal-oxides hetero-chiral thin film

    Science.gov (United States)

    Lee, Seung Hee; Singh, Dhruv Pratap; Sung, Ji Ho; Jo, Moon-Ho; Kwon, Ki Chang; Kim, Soo Young; Jang, Ho Won; Kim, Jong Kyu

    2016-01-01

    A highly efficient circularly-polarized-light detector with excellent wavelength selectivity is demonstrated with an elegant and simple microelectronics-compatible way. The circularly-polarized-light detector based on a proper combination of the geometry-controlled TiO2-SnO2 hetero-chiral thin film as an effective chiroptical filter and the Si active layer shows excellent chiroptical response with external quantum efficiency as high as 30% and high helicity selectivity of ~15.8% in an intended wavelength range. Furthermore, we demonstrated the ability of manipulating both bandwidth and responsivity of the detector simultaneously in whole visible wavelength range by a precise control over the geometry and materials constituting hetero-chiral thin film. The high efficiency, wavelength selectivity and compatibility with conventional microelectronics processes enabled by the proposed device can result in remarkable developments in highly integrated photonic platforms utilizing chiroptical responses. PMID:26795601

  1. Near-infrared background anisotropies from diffuse intrahalo light of galaxies.

    Science.gov (United States)

    Cooray, Asantha; Smidt, Joseph; De Bernardis, Francesco; Gong, Yan; Stern, Daniel; Ashby, Matthew L N; Eisenhardt, Peter R; Frazer, Christopher C; Gonzalez, Anthony H; Kochanek, Christopher S; Kozłowski, Szymon; Wright, Edward L

    2012-10-25

    Unresolved anisotropies of the cosmic near-infrared background radiation are expected to have contributions from the earliest galaxies during the epoch of reionization and from faint, dwarf galaxies at intermediate redshifts. Previous measurements were unable to pinpoint conclusively the dominant origin because they did not sample spatial scales that were sufficiently large to distinguish between these two possibilities. Here we report a measurement of the anisotropy power spectrum from subarcminute to one-degree angular scales, and find the clustering amplitude to be larger than predicted by the models based on the two existing explanations. As the shot-noise level of the power spectrum is consistent with that expected from faint galaxies, a new source population on the sky is not necessary to explain the observations. However, a physical mechanism that increases the clustering amplitude is needed. Motivated by recent results related to the extended stellar light profile in dark-matter haloes, we consider the possibility that the fluctuations originate from intrahalo stars of all galaxies. We find that the measured power spectrum can be explained by an intrahalo light fraction of 0.07 to 0.2 per cent relative to the total luminosity in dark-matter haloes of 10(9) to 10(12) solar masses at redshifts of about 1 to 4.

  2. Probing the peak of the star formation rate density with the extragalactic background light

    CERN Document Server

    Raue, Martin

    2012-01-01

    The extragalactic background light (EBL), i.e., the diffuse meta-galactic photon field in the ultraviolet to infrared, is dominated by the emission from stars in galaxies. It is, therefore, intimately connected with the integrated star formation rate density (SFRD). In this paper, the SFRD is constrained using recent limits on the EBL density derived from observations of distant sources of high and very-high energy gamma-rays. The stellar EBL contribution is modeled utilizing simple stellar population spectra including dust attenuation and emission. A wide range of values for the different model parameters (SFRD(z), metallicity, dust absorption) is investigated and their impact on the resulting EBL is studied. The calculated EBL densities are compared with the specific EBL density limits and constraints on the SFRD are derived. For the fiducial model, adopting a Chabrier initial mass function (IMF), the SFRD is constrained to ~< 0.1 M_solar yr^-1 Mpc^-3 and < 0.2 M_solar yr^-1 Mpc^-3 for a redshift of z...

  3. Effects of spatial fluctuations in the extragalactic background light on hard gamma-ray spectra

    Science.gov (United States)

    Kudoda, A. M.; Faltenbacher, A.

    2017-05-01

    This study investigates the impact of the fluctuations in the extragalactic background light (EBL) on the attenuation of the hard γ-ray spectra of distant blazars. EBL fluctuations occur on the scales up to 100 Mpc and are caused by the clustering of galaxies. The EBL photons interact with high-energy γ-rays via the electron-positron pair production mechanism: γ + γ΄ → e+ + e-. The attenuation of γ-rays depends on their energy and the density of the intervening EBL photon field. Using a simple model for the evolution of the mean EBL photon density, we implement an analytical description of the EBL fluctuations. We find that the amplitudes of the EBL energy density can vary by ±1 per cent as a function of environment. The EBL fluctuations lead to mild alterations of the optical depth or equivalently the transmissivity for γ-rays from distant blazars. Our model predicts maximum changes of ±10 per cent in the γ-ray transmissivity. However, this translates into marginal differences in the power-law slopes of currently observed γ-ray spectra. The slopes of deabsorbed γ-ray spectra differ by not more than ±1 per cent if EBL fluctuations are included.

  4. Fermi-LAT high-z active galactic nuclei and the extragalactic background light

    Science.gov (United States)

    Armstrong, Thomas; Brown, Anthony M.; Chadwick, Paula M.

    2017-10-01

    Observations of distant gamma-ray sources are hindered by the presence of the extragalactic background light (EBL). In order to understand the physical processes that result in the observed spectrum of sources, it is imperative that a good understanding of the EBL is included. In this work, an investigation into the imprint of the EBL on the observed spectra of high-redshift Fermi-LAT active galactic nuclei is presented. By fitting the spectrum below ˜10 GeV, an estimation of the unabsorbed intrinsic source spectrum is obtained; by applying this spectrum to data up to 300 GeV, it is then possible to derive a scaling factor for different EBL models. A second approach uses five sources (PKS 0426-380, 4C +55.17, Ton 116, PG 1246+586 and RBS 1432) that were found to exhibit very high energy (VHE) emission (Eγ > 100 GeV). Through Monte Carlo simulations, it is shown that the observation of VHE photons, despite the large distances of these objects, is consistent with current EBL models. Many of these sources would be observable with the upcoming ground-based observatory, the Cherenkov Telescope Array, leading to a better understanding of the EBL.

  5. Estimation of the extragalactic background light using TeV observations of BL Lac objects

    Energy Technology Data Exchange (ETDEWEB)

    Sinha, Atreyee; Acharya, B. S. [Department of High Energy Physics, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India); Sahayanathan, S.; Godambe, S. [Astrophysical Sciences Division, Bhabha Atomic Research Center, Mumbai (India); Misra, R., E-mail: atreyee@tifr.res.in, E-mail: acharya@tifr.res.in, E-mail: sunder@barc.ernet.in, E-mail: gsagar@barc.ernet.in, E-mail: rmisra@iucaa.ernet.in [Inter-University Center for Astronomy and Astrophysics, Post Bag 4, Ganeshkhind, Pune 411007 (India)

    2014-11-01

    The very high-energy (VHE) gamma-ray spectral index of high-energy peaked blazars correlates strongly with its corresponding redshift, whereas no such correlation is observed in the X-ray or GeV bands. We attribute this correlation to photon-photon absorption of TeV photons with the extragalactic background light (EBL), and utilizing this we compute the allowed flux range for the EBL, which is independent of previous estimates. The observed VHE spectrum of the sources in our sample can be well approximated by a power law, and if the de-absorbed spectrum is also assumed to be a power law, then we show that the spectral shape of EBL will be εn(ε) ∼ klog (ε/ε {sub p}). We estimate the range of values for the parameters defining the EBL spectrum, k and ε {sub p}, such that the correlation of the intrinsic VHE spectrum with redshift is nullified. The estimated EBL depends only on the observed correlation and the assumption of a power-law source spectrum. Specifically, it does not depend on the spectral modeling or radiative mechanism of the sources or on any theoretical shape of the EBL spectrum obtained through cosmological calculations. The estimated EBL spectrum is consistent with the upper and lower limits imposed by different observations. Moreover, it also agrees closely with the theoretical estimates obtained through cosmological evolution models.

  6. ABSOLUTE ASYMMETRIC SYNTHESIS. I. ON THE MECHANISM OF THEPHOTOCHEMICAL ABSOLUTE ASYMMETRIC SYNTHESIS OF HELICENES WITH CIRCULARLYPOLARIZED LIGHT. . WAVELENGTH DEPENDENCE OF THE OPTICAL YIELD OFOCTAHELICENE.

    Energy Technology Data Exchange (ETDEWEB)

    Bernstein, William J.; Calvin, Melvin; Buchardt, Ole.

    1971-05-01

    The synthesis of nonracemic yields of hexa-, hepta-, octa-, and nonhelicene with circular light was observed, and the structural and wavelength dependence of the induced optical yields was examined. The results obtained, together with a detailed consideration of the mechanism of helicene synthesis from the parent diarylolefins, indicate that the induced optical activity is due to selective reaction of enantiomeric conformations of the parent cis diarylolefins by circular light.

  7. Phosphorus Doping in Si Nanocrystals/SiO2 msultilayers and Light Emission with Wavelength compatible for Optical Telecommunication.

    Science.gov (United States)

    Lu, Peng; Mu, Weiwei; Xu, Jun; Zhang, Xiaowei; Zhang, Wenping; Li, Wei; Xu, Ling; Chen, Kunji

    2016-03-09

    Doping in semiconductors is a fundamental issue for developing high performance devices. However, the doping behavior in Si nanocrystals (Si NCs) has not been fully understood so far. In the present work, P-doped Si NCs/SiO2 multilayers are fabricated. As revealed by XPS and ESR measurements, P dopants will preferentially passivate the surface states of Si NCs. Meanwhile, low temperature ESR spectra indicate that some P dopants are incorporated into Si NCs substitutionally and the incorporated P impurities increase with the P doping concentration or annealing temperature increasing. Furthermore, a kind of defect states will be generated with high doping concentration or annealing temperature due to the damage of Si crystalline lattice. More interestingly, the incorporated P dopants can generate deep levels in the ultra-small sized (~2 nm) Si NCs, which will cause a new subband light emission with the wavelength compatible with the requirement of the optical telecommunication. The studies of P-doped Si NCs/SiO2 multilayers suggest that P doping plays an important role in the electronic structures and optoelectronic characteristics of Si NCs.

  8. Suppression of cucumber powdery mildew by UV-B is affected by background light quality

    Science.gov (United States)

    Brief (5-10 min) exposure to UV-B radiation (280-300 nm) suppressed powdery mildew (Podosphaera xanthii) on Cucumis sativus. The effect was enhanced by red light (600-660 nm), but offset by blue light (420-500 nm) and UV-A (300-420 nm). Compared to untreated controls, 2 h red light from specific lig...

  9. The effect of background galaxy contamination on the absolute magnitude and light curve speed class of type Ia supernovae

    Science.gov (United States)

    Boisseau, John R.; Wheeler, J. Craig

    1991-01-01

    Observational data are presented in support of the hypothesis that background galaxy contamination is present in the photometric data of Ia supernovae and that this effect can account for the observed dispersion in the light curve speeds of most of Ia supernovae. The implication is that the observed dispersion in beta is artificial and that most of Ia supernovae have nearly homogeneous light curves. The result supports the notion that Ia supernovae are good standard candles.

  10. Background and muon counting rates in underground muon measurements with a plastic scintillator counter based on a wavelength shifting fibre and a multi-pixel avalanche photodiode readout

    National Research Council Canada - National Science Library

    Volchenko, Vladimir I; Akhrameev, Evgeniy V; Bezrukov, Leonid B; Dzaparova, Irina M; Davitashvili, Irakliy Sh; Enqvist, Timo; Fynbo, Hans; Guliev, Zhamal Sh; Inzhechik, Lev V; Izmaylov, Alexander O; Joutsenvaara, Jari; Khabibullin, Marat M; Khotjantsev, Alexey N; Kudenko, Yuri G; Kuusiniemi, Pasi; Lubsandorzhiev, Bayarto K; Lubsandorzhiev, Nima B; Mineev, Oleg V; Olanterä, Lauri; Petkov, Valeriy B; Poleshuk, Roman V; Räihä, Tomi; Shaibonov, Bator A. M; Sarkamo, Juho; Shaykhiev, Alexey T; Trzaska, Wladyslaw; Volchenko, Galina V; Yanin, Alexey F; Yershov, Nikolay V

    2010-01-01

    ...×3.0 cm3 size scintillator counter with a wavelength shifting fibre and a multi-pixel Geiger mode avalanche photodiode readout in the Baksan underground laboratory at a depth of 200 metres of water equivalent...

  11. SXDF-ALMA 2 arcmin2 deep survey: Resolving and characterizing the infrared extragalactic background light down to 0.5 mJy

    Science.gov (United States)

    Yamaguchi, Yuki; Tamura, Yoichi; Kohno, Kotaro; Aretxaga, Itziar; Dunlop, James S.; Hatsukade, Bunyo; Hughes, David; Ikarashi, Soh; Ishii, Shun; Ivison, Rob J.; Izumi, Takuma; Kawabe, Ryohei; Kodama, Tadayuki; Lee, Minju; Makiya, Ryu; Matsuda, Yuichi; Nakanishi, Kouichiro; Ohta, Kouji; Rujopakarn, Wiphu; Tadaki, Ken-ichi; Umehata, Hideki; Wang, Wei-Hao; Wilson, Grant W.; Yabe, Kiyoto; Yun, Min S.

    2016-10-01

    We present a multiwavelength analysis of five submillimeter sources (S1.1mm = 0.54-2.02 mJy) that were detected during our 1.1 mm deep continuum survey in the Subaru/XMM-Newton Deep Survey Field (SXDF)-UDS-CANDELS field (2 arcmin2, 1σ = 0.055 mJy beam-1) using the Atacama Large Millimeter/submillimeter Array (ALMA). The two brightest sources correspond to a known single-dish (AzTEC) selected bright submillimeter galaxy (SMG), whereas the remaining three are faint SMGs newly uncovered by ALMA. If we exclude the two brightest sources, the contribution of the ALMA-detected faint SMGs to the infrared extragalactic background light is estimated to be ˜ 4.1^{+5.4}_{-3.0}Jy deg-2, which corresponds to ˜ 16^{+22}_{-12}% of the infrared extragalactic background light. This suggests that their contribution to the infrared extragalactic background light is as large as that of bright SMGs. We identified multiwavelength counterparts of the five ALMA sources. One of the sources (SXDF-ALMA3) is extremely faint in the optical to near-infrared region despite its infrared luminosity (L_IR˜eq 1× 10^{12} L_{⊙} or SFR ≃ 100 M⊙ yr-1). By fitting the spectral energy distributions at the optical-to-near-infrared wavelengths of the remaining four ALMA sources, we obtained the photometric redshifts (zphoto) and stellar masses (M*): zphoto ≃ 1.3-2.5, M* ≃ (3.5-9.5) × 1010 M⊙. We also derived their star formation rates (SFRs) and specific SFRs as ≃30-200 M⊙ yr-1 and ≃0.8-2 Gyr-1, respectively. These values imply that they are main sequence star-forming galaxies.

  12. Effects of melatonin injection or green-wavelength LED light on the antioxidant system in goldfish (Carassius auratus) during thermal stress.

    Science.gov (United States)

    Jung, Seo Jin; Choi, Young Jae; Kim, Na Na; Choi, Ji Yong; Kim, Bong-Seok; Choi, Cheol Young

    2016-05-01

    We tested the mitigating effects of melatonin injections or irradiation from green-wavelength light-emitting diodes (LEDs) on goldfish (Carassius auratus) exposed to thermal stress (high water temperature, 30 °C). The effects of the two treatments were assessed by measuring the expression and activity levels of the antioxidant enzymes, superoxide dismutase and catalase, plasma hydrogen peroxide, lipid hydroperoxide, and lysozyme. In addition, a comet assay was conducted to confirm that high water temperature damaged nuclear DNA. The expression and activity of the antioxidant enzymes, plasma hydrogen peroxide, and lipid hydroperoxide were significantly higher after exposure to high temperature and were significantly lower in fish that received melatonin or LED light than in those that received no mitigating treatment. Plasma lysozyme was significantly lower after exposure to high temperature and was significantly higher after exposure to melatonin or LED light. The comet assay revealed that thermal stress caused a great deal of damage to nuclear DNA; however, treatment with melatonin or green-wavelength LED light prevented a significant portion of this damage from occurring. These results indicate that, although high temperatures induce oxidative stress and reduce immune system strength in goldfish, both melatonin and green-wavelength LED light inhibit oxidative stress and boost the immune system. LED treatment increased the antioxidant and immune system activity more significantly than did melatonin treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Fabrication of a nano-cone array on a p-GaN surface for enhanced light extraction efficiency from GaN-based tunable wavelength LEDs.

    Science.gov (United States)

    Soh, C B; Wang, B; Chua, S J; Lin, Vivian K X; Tan, Rayson J N; Tripathy, S

    2008-10-08

    We report on the fabrication of a nano-cone structured p-GaN surface for enhanced light extraction from tunable wavelength light emitting diodes (LEDs). Prior to p-contact metallization, self-assembled colloidal particles are deposited and used as a mask for plasma etching to create nano-cone structures on the p-GaN layer of LEDs. A well-defined periodic nano-cone array, with an average cone diameter of 300 nm and height of 150 nm, is generated on the p-GaN surface. The photoluminescence emission intensity recorded from the regions with the nano-cone array is increased by two times as compared to LEDs without surface patterning. The light output power from the LEDs with surface nano-cones shows significantly higher electroluminescence intensity at an injection current of 70 mA. This is due to the internal multiple scattering of light from the nano-cone sidewalls. Furthermore, we have shown that with an incorporation of InGaN nanostructures in the quantum well, the wavelength of these surface-patterned LEDs can be tuned from 517 to 488 nm with an increase in the injection current. This methodology may serve as a practical approach to increase the light extraction efficiency from wavelength tunable LEDs.

  14. Performance of three microalgal strains in biogas slurry purification and biogas upgrade in response to various mixed light-emitting diode light wavelengths.

    Science.gov (United States)

    Zhao, Yongjun; Sun, Shiqing; Hu, Changwei; Zhang, Hui; Xu, Jie; Ping, Lifeng

    2015-01-01

    The three microalgal strains were cultivated, namely, Chlorella vulgaris, Scenedesmus obliquus, and Neochloris oleoabundans, by applying mixed light-emitting diode wavelength treatments to biogas slurry in a photobioreactor bag. This study aims to compare the growth and nutrient removal efficiency of the algae and determine their roles for biogas upgrading. At red:blue=5:5, S. obliquus and C. vulgaris efficiently removed COD and TP, respectively. S. obliquus demonstrated high N removal efficiency at red:blue=7:3. The same strain significantly improved removal capacity for all nutrients compared with C. vulgaris and N. oleoabundans, particularly at red:blue=5:5, 7:3, and 3:7. For biogas upgrade, CH4 contents were higher than 75% (v/v) for all strains. The algae exhibited particularly good CH4 enrichment at red:blue=7:3, 5:5. Results show that microalgal biomass production offers real opportunities for addressing issues, such as nutrient reduction, CO2 removal, and biogas enrichment. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Antireflective sub-wavelength structures for improvement of the extraction efficiency and color rendering index of monolithic white light-emitting diode

    DEFF Research Database (Denmark)

    Ou, Yiyu; Corell, Dennis Dan; Dam-Hansen, Carsten

    2011-01-01

    simulation results show that a moth-eye structure enhances the light extraction efficiency over the entire visible light range with an extraction efficiency enhancement of up to 26 %. Also for the first time to our best knowledge, the influence of sub-wavelength structures on both the color rendering index......We have theoretically investigated the influence of antireflective sub-wavelength structures on a monolithic white light-emitting diode (LED). The simulation is based on the rigorous coupled wave analysis (RCWA) algorithm, and both cylinder and moth-eye structures have been studied in the work. Our...... (CRI) and the correlated color temperature (CCT) of the monolithic white LED have been demonstrated. The CRI of the monolithic white LED could be improved from 92.68 to around 94 by applying a cylinder structure, and the CCT could be modified in a very large range with appropriate design...

  16. Atom interferometer gyroscope with spin-dependent phase shifts induced by light near a tune-out wavelength.

    Science.gov (United States)

    Trubko, Raisa; Greenberg, James; Germaine, Michael T St; Gregoire, Maxwell D; Holmgren, William F; Hromada, Ivan; Cronin, Alexander D

    2015-04-10

    Tune-out wavelengths measured with an atom interferometer are sensitive to laboratory rotation rates because of the Sagnac effect, vector polarizability, and dispersion compensation. We observed shifts in measured tune-out wavelengths as large as 213 pm with a potassium atom beam interferometer, and we explore how these shifts can be used for an atom interferometer gyroscope.

  17. Atom Interferometer Gyroscope with Spin-Dependent Phase Shifts Induced by Light near a Tune-Out Wavelength

    CERN Document Server

    Trubko, Raisa; Germaine, Michael T St; Gregoire, Maxwell D; Holmgren, William F; Hromada, Ivan; Cronin, Alexander D

    2015-01-01

    Tune-out wavelengths measured with an atom interferometer are sensitive to laboratory rotation rates because of the Sagnac effect, vector polarizability, and dispersion compensation. We observed shifts in measured tune-out wavelengths as large as 213 pm with a potassium atom beam interferometer, and we explore how these shifts can be used for an atom interferometer gyroscope.

  18. Testing the ultra-light axion hypothesis using cosmic microwave background and galaxy clustering data

    Science.gov (United States)

    Grin, Daniel

    2015-08-01

    Ultra-light axions emerge from string theory and are attractive dark matter and dark energy candidates. After reviewing the motivation for ultra-light axions, I will discuss the cosmological observables in ultra-light axion cosmological scenarios, and then lay forth the methods and results of a recent search for such axions using CMB anisotropies and the clustering of galaxies, calling on Planck CMB data and the WiggleZ galaxy survey, respectively. I will then explain how isocurvature fluctuations in the CMB lead to an interesting tension between ultra-light axion dark matter and high-scale inflation, leading to interesting connections between the hunt for primordial CMB B-mode polarization and the ultra-light axion hypothesis. I will then survey the range of interesting future observational probes of the ultra-light axion dark matter hypothesis..

  19. Designing optically pumped InGaN quantum wells with long wavelength emission for a phosphor-free device with polarized white-light emission

    Science.gov (United States)

    Kowsz, Stacy J.; Pynn, Christopher D.; Wu, Feng; Farrell, Robert M.; Speck, James S.; DenBaars, Steven P.; Nakamura, Shuji

    2016-02-01

    We report a semipolar III-nitride device in which an electrically injected blue light emitting diode optically pumps monolithic long wavelength emitting quantum wells (QWs) to create polarized white light. We have demonstrated an initial device with emission peaks at 440 nm and 560 nm from the electrically injected and optically pumped QWs, respectively. By tuning the ratio of blue to yellow, white light was measured with a polarization ratio of 0.40. High indium content InGaN is required for long wavelength emission but is difficult to achieve because it requires low growth temperatures and has a large lattice mismatch with GaN. This device design incorporates optically pumped QWs for long wavelength emission because they offer advantages over using electrically injected QWs. Optically pumped QWs do not have to be confined within a p-n junction, and carrier transport is not a concern. Thus, thick GaN barriers can be incorporated between multiple InGaN QWs to manage stress. Optically pumping long wavelength emitting QWs also eliminates high temperature steps that degrade high indium content InGaN but are required when growing p-GaN for an LED structure. Additionally, by eliminating electrical injection, the doping profile can instead be engineered to affect the emission wavelength. We discuss ongoing work focused on improving polarized white light emission by optimizing the optically pumped QWs. We consider the effects of growth conditions, including: trimethylindium (TMI) flow rate, InGaN growth rate, and growth temperature. We also examine the effects of epitaxial design, including: QW width, number of QWs, and doping.

  20. Effects of different wavelengths of light on lignin peroxidase production by the white-rot fungi Phanerochaete chrysosporium grown in submerged cultures.

    Science.gov (United States)

    Ramírez, David A; Muñoz, Sandra V; Atehortua, Lucia; Michel, Frederick C

    2010-12-01

    In this study, the effects of different wavelengths of light (UV, blue, green, yellow, red) and white light on lignin peroxidase (LiP), protein, biomass and exo-polysaccharide production and glucose uptake by Phanerochaete chrysosporium BKM-F-1767 were determined. The experiments were conducted under aerated (CS) and oxygenated (RS) culture conditions. The results showed that only green light significantly increased maximum LiP production (by 20% and 27% in CS and RS cultures respectively). Green light also increased biomass production in oxygenated cultures (RS). Blue and UV light both significantly reduced maximum LiP activity. Yellow, red and white lights had mixed effects on culture properties. This is the first time that the effects of different wavelengths of light on lignin peroxidase production and other culture properties have been investigated. The novel findings may be important in improving the yield of lignin modifying enzymes for biomass conversion processes and understanding their regulation. 2010 Elsevier Ltd. All rights reserved.

  1. A temporal model for early vision that explains detection thresholds for light pulses on flickering backgrounds

    NARCIS (Netherlands)

    Snippe, H.P.; Poot, L.; Hateren, J.H. van

    2000-01-01

    A model is presented for the early (retinal) stages of temporal processing of light inputs in the visual system. The model consists of a sequence of three adaptation processes, with two instantaneous nonlinearities in between. The three adaptation processes are, in order of processing of the light

  2. Broadly wavelength- and pulse width-tunable high-repetition rate light pulses from soliton self-frequency shifting photonic crystal fiber integrated with a frequency doubling crystal.

    Science.gov (United States)

    Lanin, Aleksandr A; Fedotov, Andrei B; Zheltikov, Aleksei M

    2012-09-01

    Soliton self-frequency shift (SSFS) in a photonic crystal fiber (PCF) pumped by a long-cavity mode-locked Cr:forsterite laser is integrated with second harmonic generation (SHG) in a nonlinear crystal to generate ultrashort light pulses tunable within the range of wavelengths from 680 to 1800 nm at a repetition rate of 20 MHz. The pulse width of the second harmonic output is tuned from 70 to 600 fs by varying the thickness of the nonlinear crystal, beam-focusing geometry, and the wavelength of the soliton PCF output. Wavelength-tunable pulses generated through a combination of SSFS and SHG are ideally suited for coherent Raman microspectroscopy at high repetition rates, as verified by experiments on synthetic diamond and polystyrene films.

  3. Inactivation and potential reactivation of pathogenic Escherichia coli O157:H7 in apple juice following ultraviolet light exposure at three monochromatic wavelengths.

    Science.gov (United States)

    Yin, Fugui; Zhu, Yan; Koutchma, Tatiana; Gong, Joshua

    2015-04-01

    Ultraviolet (UV) light irradiation at 254 nm is considered as a novel non-thermal method for decontamination of foodborne pathogenic bacteria. However, lower penetration depth of UV light at 254 nm in apple juice resulted in higher UV dose consumption during apple juice decontamination. In addition, no studies are available on the reactivation of pathogens following exposure to UV light in drinks and beverages. Two novel monochromatic UV light sources (λ = 222 and 282 nm) have been developed for bacterial disinfection. However, the inactivation of pathogenic Escherichia coli O157:H7 following exposure to these UV wavelengths is still unclear. Therefore, the present study was conducted to determine the inactivation and reactivation potential of pathogenic E. coli O157:H7 in apple juice following exposure to UV light at three monochromatic wavelengths: Far UV (λ = 222 nm), Far UV+ (λ = 282 nm) and UVC light (λ = 254 nm). The results showed that E. coli O157:H7 is acid-resistant, and up to 99.50% of cells survived in apple juice when incubated at 20 °C for 24 h. Inactivation of E. coli O157:H7 following exposure to Far UV light (2.81 Log reduction) was higher (P exposure to UV light as determined by the regular plating method. In addition, the exposure to Far UV light at 222 nm followed by incubating at 37 °C significantly decreased (P < 0.05) the survival of E. coli O157:H7 during dark incubation phase compared to that of UVC and Far UV+ light.

  4. Effects of irradiance, wavelength, and thermal emission of different light curing units on the Knoop and Vickers hardness of a composite resin.

    Science.gov (United States)

    Torno, Vladja; Soares, Paulo; Martin, Juliana M H; Mazur, Rui F; Souza, Evelise M; Vieira, Sérgio

    2008-04-01

    The aim of this study was to evaluate the effects of irradiance, light emission wavelength, and heating of different light curing units on the Knoop and Vickers hardness of a hybrid composite resin. The specimens were irradiated during 40 s with ten different light curing units, LEDs, and halogen lights. The spectral emission of each light curing unit was assessed by a spectrometer, the irradiance was measured by two commercial radiometers, and the heating measured with a thermocouple. After 48 h of storage in a dark recipient under a 100% humidity condition, the Knoop and Vickers hardness tests were carried out. The hardness results were analyzed by ANOVA, and Tukey HSD test (p surface hardness of the composite resin depends not only on the irradiance, but strongly on the emission wavelength and heating of the light curing units. It was observed, a linear correlation between the conversion degree and radiant exposure. In addition, it is suggested that the well known base to top surface hardness ratio convention of 80-90% is not appropriate to evaluate curing efficiency of composites, since the top surface is not always sufficiently polymerized.

  5. Antibacterial effect of light emitting diodes of visible wavelengths on selected foodborne pathogens at different illumination temperatures.

    Science.gov (United States)

    Ghate, Vinayak S; Ng, Kheng Siang; Zhou, Weibiao; Yang, Hyunsoo; Khoo, Gek Hoon; Yoon, Won-Byong; Yuk, Hyun-Gyun

    2013-09-16

    The antibacterial effect of light emitting diodes (LEDs) in the visible region (461, 521 and 642 nm) of the electromagnetic spectrum was investigated on Escherichia coli O157:H7, Salmonella typhimurium, Listeria monocytogenes and Staphylococcus aureus. The irradiances of the 461, 521 and 642 nm LEDs were 22.1, 16 and 25.4 mW/cm², respectively. Bacterial cultures suspended in tryptic soy broth were illuminated by 10-watt LEDs at a distance of 4.5 cm for 7.5h at 20, 15 and 10 °C. Regardless of the bacterial strains, bacterial inactivation was observed with the range of 4.6-5.2 logCFU/ml at 10 and 15 °C after illumination with the 461 nm LED, while illumination with the 521 nm LED resulted in only 1.0-2.0 log reductions after 7.5h. On the other hand, no antibacterial effect was observed using the 642 nm LED treatment. The photodynamic inactivation by 461 and 521 nm LEDs was found to be greater at the set temperatures of 10 and 15 °C than at 20 °C. The D-values for the four bacterial strains at 10 and 15 °C after the illumination of 461 nm LED ranged from 1.29 to 1.74 h, indicating that there was no significant difference in the susceptibility of the bacterial strains to the LED illumination between 10 and 15 °C, except for L. monocytogenes. Regardless of the illumination temperature, sublethal injury was observed in all bacterial strains during illumination with the 461 and the 521 nm LED and the percentage of injured cells increased as the treatment time increased. Thus, the results show that the antibacterial effect of the LEDs was highly dependent on the wavelength and the illumination temperature. This study suggests the potential of 461 and 521 nm LEDs in combination with chilling to be used as a novel food preservation technology.

  6. Towards strong light-matter coupling at the single-resonator level with sub-wavelength mid-infrared nano-antennas

    Science.gov (United States)

    Malerba, M.; Ongarello, T.; Paulillo, B.; Manceau, J.-M.; Beaudoin, G.; Sagnes, I.; De Angelis, F.; Colombelli, R.

    2016-07-01

    We report a crucial step towards single-object cavity electrodynamics in the mid-infrared spectral range using resonators that borrow functionalities from antennas. Room-temperature strong light-matter coupling is demonstrated in the mid-infrared between an intersubband transition and an extremely reduced number of sub-wavelength resonators. By exploiting 3D plasmonic nano-antennas featuring an out-of-plane geometry, we observed strong light-matter coupling in a very low number of resonators: only 16, more than 100 times better than what reported to date in this spectral range. The modal volume addressed by each nano-antenna is sub-wavelength-sized and it encompasses only ≈4400 electrons.

  7. Towards strong light-matter coupling at the single-resonator level with sub-wavelength mid-infrared nano-antennas

    Energy Technology Data Exchange (ETDEWEB)

    Malerba, M.; De Angelis, F., E-mail: francesco.deangelis@iit.it [Istituto Italiano di Tecnologia, Via Morego, 30, I-16163 Genova (Italy); Ongarello, T.; Paulillo, B.; Manceau, J.-M.; Beaudoin, G.; Sagnes, I.; Colombelli, R., E-mail: raffaele.colombelli@u-psud.fr [Centre for Nanoscience and Nanotechnology (C2N Orsay), CNRS UMR9001, Univ. Paris Sud, Univ. Paris Saclay, 91405 Orsay (France)

    2016-07-11

    We report a crucial step towards single-object cavity electrodynamics in the mid-infrared spectral range using resonators that borrow functionalities from antennas. Room-temperature strong light-matter coupling is demonstrated in the mid-infrared between an intersubband transition and an extremely reduced number of sub-wavelength resonators. By exploiting 3D plasmonic nano-antennas featuring an out-of-plane geometry, we observed strong light-matter coupling in a very low number of resonators: only 16, more than 100 times better than what reported to date in this spectral range. The modal volume addressed by each nano-antenna is sub-wavelength-sized and it encompasses only ≈4400 electrons.

  8. Transmission of phototherapy through human skin: dosimetry adjustment for effects of skin color, body composition, wavelength, and light coupling to skin

    Science.gov (United States)

    Nussbaum, Ethne L.; Van Zuylen, Jeff

    2006-02-01

    Purpose: To examine factors that affect penetration of phototherapy. Methods: Age, sex, height, and weight were recorded; skin color, skinfold thickness, and light transmission through a skinfold were measured over biceps and triceps muscles, and at the anterior waistline. Light was generated using two 23-diode LED arrays at 840 nm and 660 nm with surface area of 7 cm2. Photon irradiation was measured using an Optical Power Meter consisting of a 1x1-cm2 light detector placed in the centre of the illuminated 7 cm2 spot. Transmission was measured using three skin-diode coupling conditions. Results: Penetration of LED irradiation increased when diodes were coupled to skin with pressure. Red light attenuated more rapidly than infrared light and the attenuation of red light increased as skin color darkened. Penetration of red and infrared light decreased as the amount of subcutaneous fat increased. There were gender effects on penetration of infrared light at normal and low BMI values. Conclusions: When using divergent light sources for phototherapy, radiant exposure should take into account individual physical characteristics, irradiation wavelength and diode configuration of the laser therapy system.

  9. Background story of the invention of efficient blue InGaN light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Shuji [University of California, Santa Barbara, CA (United States)

    2015-06-15

    Shuji Nakamura discovered p-type doping in Gallium Nitride (GaN) and developed blue, green, and white InGaN based light emitting diodes (LEDs) and blue laser diodes (LDs). His inventions made possible energy efficient, solid-state lighting systems and enabled the next generation of optical storage. Together with Isamu Akasaki and Hiroshi Amano, he is one of the three recipients of the 2014 Nobel Prize in Physics. In his Nobel lecture, Shuji Nakamura gives an overview of this research and the story of his inventions. (copyright 2015 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Wavelength-sensitive photocatalytic degradation of methyl orange in aqueous suspension over iron(III)-doped TiO2 nanopowders under UV and visible light irradiation.

    Science.gov (United States)

    Wang, X H; Li, J-G; Kamiyama, H; Moriyoshi, Y; Ishigaki, T

    2006-04-06

    Well-crystallized iron(III)-doped TiO2 nanopowders with controlled Fe3+ doping concentration and uniform dopant distribution, have been synthesized with plasma oxidative pyrolysis. The photocatalytic reactivity of the synthesized TiO2 nanopowders with a mean particle size of 50-70 nm was quantified in terms of the degradation rates of methyl orange (MO) in aqueous TiO2 suspension under UV (mainly 365 and 316 nm) and visible light irradiation (mainly 405 and 436 nm). The photodecomposition of MO over TiO2 nanopowders followed a distinct two-stage pseudo first order kinetics. Interestingly, the photocatalytic reactivity depends not only on the iron doping concentration but also on the wavelength of the irradiating light. Under UV irradiation, nominally undoped TiO2 had much higher reactivity than Fe3+ -doped TiO2, suggesting that Fe3+ doping (> 0.05 at. %) in TiO2 with a mean particle size of approximately 60 nm was detrimental to the photocatalytic decomposition of methyl orange. Whereas, under visible light irradiation, the Fe3+ -doped TiO2 with an intermediate iron doping concentration of approximately 1 at. % had the highest photocatalytic reactivity due to the narrowing of band gap so that it could effectively absorb the light with longer wavelength. A strategy for improving the photocatalytic reactivity of Fe3+ -doped TiO2 used in the visible light region is also proposed.

  11. Light-induced growth of monodisperse silver nanoparticles with tunable SPR properties and wavelength self-limiting effect

    Science.gov (United States)

    Zheng, Xianliang; Lombardi, John R.

    2008-08-01

    We present a technique for the tunable synthesis of a variety of monodisperse silver nanoparticles. Utilizing different optical wavelengths to irradiate initially grown seed crystals, the size and shape of the products can be controlled. Monitoring the absorption spectrum during growth, we observe that initially the absorption maximum shifts to longer wavelengths and broadens, indicating increasing particle size and dispersion. Remarkably, this effect gradually comes to a halt and reverses, displaying a shift to shorter wavelengths and simultaneously narrower bandwidths, until on completion, a final size and relatively narrow distribution is reached. The final morphology is found to depend on control of the laser wavelength and power. Discs, triangular prisms as well as pyramidal and pentagonal prisms may be produced. A process based on a wavelength dependent self-limiting mechanism governed by the surface plasmon resonance controlling the photochemical reduction of particles is suggested. By a similar mechanism, we show that by using a sodium lamp instead of a laser as an excitation source, a monodisperse sample of nanotetrahedra can be produced.

  12. Comparative action spectrum for ultraviolet light killing of mouse melanocytes from different genetic coat color backgrounds

    Energy Technology Data Exchange (ETDEWEB)

    Hill, H.Z.; Xin, P. [New Jersey Medical School, Newark (United States). Section of Cancer Biology; Hill, G.J. [New Jersey Medical School, Newark (United States). Division of Surgical Oncology; Cieszka, K.; Plonka, P.M. [Jagiellonian University, Cracow (Poland). Inst. of Molecular Biology; Mitchell, D.L. [University of Texas, Smithville (United States); Meyenhofer, M.F. [New Jersey Medical School, Newark (United States). Central EM Facility; Boissy, R.E. [University of Cincinnati, OH (United States). Dept. of Dermatology

    1997-06-01

    The photobiology of mouse melanocyte lines with different pigment genotypes was studied by measuring colony-forming ability after irradiation. The cell lines were wild-type black (melan-a) and the mutants brown (melan-b) and albino (melan-c). Four lamps emitting various UV wavelengths were used. These were germicidal (UVC, 200-280 nm), 82.3% output at 254 nm, TL01 (UVB, 280-320 nm), 64.2% at 310-311 nm, FS20, broadband with peak output at 312 nm and Alisun-S (UVA, 320-400 nm), broadband with peak output at 350-354 nm. Appropriate filtration reduced the contaminating UVC to nonlethal levels for the longer waverange lamps. It is clear from these studies that, in pigment cells, monochromatic results cannot predict polychromatic responses and that cell death from solar irradiations is a complex phenomenon that depends on more than DNA damage. (author).

  13. Measurement of the extragalactic background light imprint on the spectra of the brightest blazars observed with H.E.S.S.

    Science.gov (United States)

    H.E.S.S. Collaboration; Abramowski, A.; Acero, F.; Aharonian, F.; Akhperjanian, A. G.; Anton, G.; Balenderan, S.; Balzer, A.; Barnacka, A.; Becherini, Y.; Becker Tjus, J.; Bernlöhr, K.; Birsin, E.; Biteau, J.; Bochow, A.; Boisson, C.; Bolmont, J.; Bordas, P.; Brucker, J.; Brun, F.; Brun, P.; Bulik, T.; Carrigan, S.; Casanova, S.; Cerruti, M.; Chadwick, P. M.; Charbonnier, A.; Chaves, R. C. G.; Cheesebrough, A.; Cologna, G.; Conrad, J.; Couturier, C.; Dalton, M.; Daniel, M. K.; Davids, I. D.; Degrange, B.; Deil, C.; deWilt, P.; Dickinson, H. J.; Djannati-Ataï, A.; Domainko, W.; O'C. Drury, L.; Dubus, G.; Dutson, K.; Dyks, J.; Dyrda, M.; Egberts, K.; Eger, P.; Espigat, P.; Fallon, L.; Farnier, C.; Fegan, S.; Feinstein, F.; Fernandes, M. V.; Fernandez, D.; Fiasson, A.; Fontaine, G.; Förster, A.; Füßling, M.; Gajdus, M.; Gallant, Y. A.; Garrigoux, T.; Gast, H.; Giebels, B.; Glicenstein, J. F.; Glück, B.; Göring, D.; Grondin, M.-H.; Häffner, S.; Hague, J. D.; Hahn, J.; Hampf, D.; Harris, J.; Heinz, S.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hillert, A.; Hinton, J. A.; Hofmann, W.; Hofverberg, P.; Holler, M.; Horns, D.; Jacholkowska, A.; Jahn, C.; Jamrozy, M.; Jung, I.; Kastendieck, M. A.; Katarzyński, K.; Katz, U.; Kaufmann, S.; Khélifi, B.; Klochkov, D.; Kluźniak, W.; Kneiske, T.; Komin, Nu.; Kosack, K.; Kossakowski, R.; Krayzel, F.; Laffon, H.; Lamanna, G.; Lenain, J.-P.; Lennarz, D.; Lohse, T.; Lopatin, A.; Lu, C.-C.; Marandon, V.; Marcowith, A.; Masbou, J.; Maurin, G.; Maxted, N.; Mayer, M.; McComb, T. J. L.; Medina, M. C.; Méhault, J.; Menzler, U.; Moderski, R.; Mohamed, M.; Moulin, E.; Naumann, C. L.; Naumann-Godo, M.; de Naurois, M.; Nedbal, D.; Nguyen, N.; Niemiec, J.; Nolan, S. J.; Ohm, S.; de Oña Wilhelmi, E.; Opitz, B.; Ostrowski, M.; Oya, I.; Panter, M.; Parsons, D.; Paz Arribas, M.; Pekeur, N. W.; Pelletier, G.; Perez, J.; Petrucci, P.-O.; Peyaud, B.; Pita, S.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raue, M.; Reimer, A.; Reimer, O.; Renaud, M.; de los Reyes, R.; Rieger, F.; Ripken, J.; Rob, L.; Rosier-Lees, S.; Rowell, G.; Rudak, B.; Rulten, C. B.; Sahakian, V.; Sanchez, D. A.; Santangelo, A.; Schlickeiser, R.; Schulz, A.; Schwanke, U.; Schwarzburg, S.; Schwemmer, S.; Sheidaei, F.; Skilton, J. L.; Sol, H.; Spengler, G.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Stinzing, F.; Stycz, K.; Sushch, I.; Szostek, A.; Tavernet, J.-P.; Terrier, R.; Tluczykont, M.; Valerius, K.; van Eldik, C.; Vasileiadis, G.; Venter, C.; Viana, A.; Vincent, P.; Völk, H. J.; Volpe, F.; Vorobiov, S.; Vorster, M.; Wagner, S. J.; Ward, M.; White, R.; Wierzcholska, A.; Wouters, D.; Zacharias, M.; Zajczyk, A.; Zdziarski, A. A.; Zech, A.; Zechlin, H.-S.

    2013-02-01

    The extragalactic background light (EBL) is the diffuse radiation with the second highest energy density in the Universe after the cosmic microwave background. The aim of this study is the measurement of the imprint of the EBL opacity to γ-rays on the spectra of the brightest extragalactic sources detected with the High Energy Stereoscopic System (H.E.S.S.). The originality of the method lies in the joint fit of the EBL optical depth and of the intrinsic spectra of the sources, assuming intrinsic smoothness. Analysis of a total of ~105γ-ray events enables the detection of an EBL signature at the 8.8σ level and constitutes the first measurement of the EBL optical depth using very-high energy (E > 100 GeV) γ-rays. The EBL flux density is constrained over almost two decades of wavelengths [0.30 μm, 17 μm] and the peak value at 1.4 μm is derived as λFλ = 15 ± 2stat ± 3sys nW m-2 sr-1. Appendix A is available in electronic form at http://www.aanda.org

  14. Measurement of the extragalactic background light imprint on the spectra of the brightest blazars observed with H.E.S.S

    CERN Document Server

    :,; Acero, F; Aharonian, F; Akhperjanian, A G; Anton, G; Balenderan, S; Balzer, A; Barnacka, A; Becherini, Y; Tjus, J Becker; Bernlöhr, K; Birsin, E; Biteau, J; Bochow, A; Boisson, C; Bolmont, J; Bordas, P; Brucker, J; Brun, F; Brun, P; Bulik, T; Carrigan, S; Casanova, S; Cerruti, M; Chadwick, P M; Charbonnier, A; Chaves, R C G; Cheesebrough, A; Cologna, G; Conrad, J; Couturier, C; Dalton, M; Daniel, M K; Davids, I D; Degrange, B; Deil, C; deWilt, P; Dickinson, H J; Djannati-Ataï, A; Domainko, W; Drury, L O'C; Dubus, G; Dutson, K; Dyks, J; Dyrda, M; Egberts, K; Eger, P; Espigat, P; Fallon, L; Farnier, C; Fegan, S; Feinstein, F; Fernandes, M V; Fernandez, D; Fiasson, A; Fontaine, G; Förster, A; Füßling, M; Gajdus, M; Gallant, Y A; Garrigoux, T; Gast, H; Giebels, B; Glicenstein, J F; Glück, B; Göring, D; Grondin, M -H; Häffner, S; Hague, J D; Hahn, J; Hampf, D; Harris, J; Heinz, S; Heinzelmann, G; Henri, G; Hermann, G; Hillert, A; Hinton, J A; Hofmann, W; Hofverberg, P; Holler, M; Horns, D; Jacholkowska, A; Jahn, C; Jamrozy, M; Jung, I; Kastendieck, M A; Katarzyński, K; Katz, U; Kaufmann, S; Khélifi, B; Klochkov, D; Kluźniak, W; Kneiske, T; Komin, Nu; Kosack, K; Kossakowski, R; Krayzel, F; Laffon, H; Lamanna, G; Lenain, J -P; Lennarz, D; Lohse, T; Lopatin, A; Lu, C -C; Marandon, V; Marcowith, A; Masbou, J; Maurin, G; Maxted, N; Mayer, M; McComb, T J L; Medina, M C; Méhault, J; Menzler, U; Moderski, R; Mohamed, M; Moulin, E; Naumann, C L; Naumann-Godo, M; de Naurois, M; Nedbal, D; Nguyen, N; Niemiec, J; Nolan, S J; Ohm, S; Wilhelmi, E de Oña; Opitz, B; Ostrowski, M; Oya, I; Panter, M; Parsons, D; Arribas, M Paz; Pekeur, N W; Pelletier, G; Perez, J; Petrucci, P -O; Peyaud, B; Pita, S; Pühlhofer, G; Punch, M; Quirrenbach, A; Raue, M; Reimer, A; Reimer, O; Renaud, M; Reyes, R de los; Rieger, F; Ripken, J; Rob, L; Rosier-Lees, S; Rowell, G; Rudak, B; Rulten, C B; Sahakian, V; Sanchez, D A; Santangelo, A; Schlickeiser, R; Schulz, A; Schwanke, U; Schwarzburg, S; Schwemmer, S; Sheidaei, F; Skilton, J L; Sol, H; Spengler, G; Stawarz, Ł; Steenkamp, R; Stegmann, C; Stinzing, F; Stycz, K; Sushch, I; Szostek, A; Tavernet, J -P; Terrier, R; Tluczykont, M; Valerius, K; van Eldik, C; Vasileiadis, G; Venter, C; Viana, A; Vincent, P; Völk, H J; Volpe, F; Vorobiov, S; Vorster, M; Wagner, S J; Ward, M; White, R; Wierzcholska, A; Wouters, D; Zacharias, M; Zajczyk, A; Zdziarski, A A; Zech, A; Zechlin, H -S

    2012-01-01

    The extragalactic background light (EBL) is the diffuse radiation with the second highest energy density in the Universe after the cosmic microwave background. The aim of this study is the measurement of the imprint of the EBL opacity to gamma-rays on the spectra of the brightest extragalactic sources detected with the High Energy Stereoscopic System (H.E.S.S.). The originality of the method lies in the joint fit of the EBL optical depth and of the intrinsic spectra of the sources, assuming intrinsic smoothness. Analysis of a total of ~10^5 gamma-ray events enables the detection of an EBL signature at the 8.8 std dev level and constitutes the first measurement of the EBL optical depth using very-high energy (E>100 GeV) gamma-rays. The EBL flux density is constrained over almost two decades of wavelengths (0.30-17 microns) and the peak value at 1.4 micron is derived as 15 +/- 2 (stat) +/- 3 (sys) nW / m^2 sr.

  15. Background optimization for a new spherical gas detector for very light WIMP detection

    CERN Document Server

    Dastgheibi-Fard, Ali; Gerbierb, G; Derree, J; Gros, M; Magnier, P; Jourde, D; Bougamont, E; Navick, X-F; Papaevangelou, T; Galan, J; Tsiledakis, G; Piquemal, F; Zampaolo, M; Loaiza, P; Savvidis, I

    2014-01-01

    The Spherical gaseous detector (or Spherical Proportional Counter, SPC) is a novel type of par- ticle detector, with a broad range of applications. Its main features include a very low energy threshold independent of the volume (due to its very low capacitance), a good energy resolution, robustness and a single detection readout channel, in its simplest version. Applications range from radon emanation gas monitoring, neutron flux and gamma counting and spectroscopy to dark matter searches, in particular low mass WIMPs and coherent neutrino scattering measure- ment. Laboratories interested in these various applications share expertise within the NEWS (New Experiments With Sphere) network. SEDINE, a low background prototype installed at underground site of Laboratoire Souterrain de Modane is currently being operated and aims at measuring events at very low energy threshold, around 100 eV. We will present the energy cali- bration with 37Ar, the surface background reduction, the measurement of detector background...

  16. Single-wavelength-controlled in situ dynamic super-resolution fluorescence imaging for block copolymer nanostructures via blue-light-switchable FRAP.

    Science.gov (United States)

    Gong, Wen-Liang; Yan, Jie; Zhao, Ling-Xi; Li, Chong; Huang, Zhen-Li; Tang, Ben Zhong; Zhu, Ming-Qiang

    2016-11-02

    Photoswitchable fluorophores are promising in single-molecule optical devices and super-resolution fluorescence imaging, especially in single-molecule photo-activated localization microscopy (PALM) or stochastic optical reconstruction microscopy (STORM). However, the scarcity of current photoswitchable fluorophores stimulates researchers to develop complicated optical systems and processing software, in accordance with the limited photoswitchable fluorescent proteins and organic fluorophores. Previous efforts to develop synthetic photoswitchable fluorophores have exhibited their promising potential in super-resolution fluorescence imaging. Here, we have designed and synthesized a fluorescence molecular switch with reversible green emission, a napthalimide-hexaarylbiimidazole conjugate (NI-N-HABI), which exhibits strong fluorescence in the emissive state, with fast thermal fading of the photochromism and spontaneous fluorescence recovery after photobleaching (FRAP) induced by blue-light. The photoswitchable fluorophore enables the red-edge wavelength of the optical response to red-shift from the initial near-UV region at less than 400 nm, to 500 nm. The relatively fast fading speed of NI-N-HABI and its sensitivity to longer blue-light irradiation (400-500 nm) have allowed simplification of the optical microscopic system from a two-wavelength laser source to a single-wavelength laser. We applied NI-N-HABI in single-wavelength-controlled in situ dynamic super-resolution fluorescence imaging for the self-assembly and solvent annealing of amphiphilic block polymers, with 50 nm of optical resolution. Single-wavelength-controlled dynamic super-resolution fluorescence imaging facilitates nanoscale optical visualization for the dynamic physical and chemical fluctuation processes of stimuli-responsive nanostructures.

  17. Stray light test station for measuring point source transmission and thermal background of visible and infrared sensors

    Science.gov (United States)

    Peterson, Gary L.

    2008-08-01

    Breault Research Organization has designed and built a stray light test station. The station measures the point source transmission and background thermal irradiance of visible and infrared sensors. Two beam expanders, including a large 0.89 meter spherical mirror, expand and collimate light from laser sources at 0.658 and 10.6 µm. The large mirror is mounted on a gimbal to illuminate sensors at off-axis angles from 0° to 10°, and azimuths from 0° to 180°. Sensors with apertures as large as 0.3 meters can be tested with the existing facility. The large mirror is placed within a vacuum chamber so cryogenic infrared sensors can be tested in a vacuum environment. A dark cryogenic cold plate can be translated into the field of view of a sensor to measure its background thermal irradiance.

  18. New Spectral Evidence of an Unaccounted Component of the Near-infrared Extragalactic Background Light from the CIBER

    Science.gov (United States)

    Matsuura, Shuji; Arai, Toshiaki; Bock, James J.; Cooray, Asantha; Korngut, Phillip M.; Kim, Min Gyu; Lee, Hyung Mok; Lee, Dae Hee; Levenson, Louis R.; Matsumoto, Toshio; Onishi, Yosuke; Shirahata, Mai; Tsumura, Kohji; Wada, Takehiko; Zemcov, Michael

    2017-04-01

    The extragalactic background light (EBL) captures the total integrated emission from stars and galaxies throughout the cosmic history. The amplitude of the near-infrared EBL from space absolute photometry observations has been controversial and depends strongly on the modeling and subtraction of the zodiacal light (ZL) foreground. We report the first measurement of the diffuse background spectrum at 0.8-1.7 μm from the CIBER experiment. The observations were obtained with an absolute spectrometer over two flights in multiple sky fields to enable the subtraction of ZL, stars, terrestrial emission, and diffuse Galactic light. After subtracting foregrounds and accounting for systematic errors, we find the nominal EBL brightness, assuming the Kelsall ZL model, is {42.7}-10.6+11.9 nW m-2 sr-1 at 1.4 μm. We also analyzed the data using the Wright ZL model, which results in a worse statistical fit to the data and an unphysical EBL, falling below the known background light from galaxies at λ EBL brightness, we find an EBL brightness of {28.7}-3.3+5.1 nWm-2 sr-1 at 1.4 μm. While the derived EBL amplitude strongly depends on the ZL model, we find that we cannot fit the spectral data to ZL, Galactic emission, and EBL from solely integrated galactic light from galaxy counts. The results require a new diffuse component, such as an additional foreground or an excess EBL with a redder spectrum than that of ZL.

  19. Vapor intrusion attenuation factors relative to subslab and source, reconsidered in light of background data

    OpenAIRE

    Yao, Yijun; Wu, Yun; Suuberg, Eric M.; Provoost, Jeroen; Shen, Rui; Ma, Jianqing; Jing LIU

    2015-01-01

    The basis upon which recommended attenuation factors for vapor intrusion (VI) have been derived are reconsidered. By making a fitting curve to the plot showing the dependence of observed indoor air concentration (cin) on subslab concentration (css) for residences in EPA database, an analytical equation is obtained to identify the relationship among cin, css and the averaged background level. The new relationship indicates that subslab measurements may serve as a useful guide only if css is ab...

  20. Vapor intrusion attenuation factors relative to subslab and source, reconsidered in light of background data.

    Science.gov (United States)

    Yao, Yijun; Wu, Yun; Suuberg, Eric M; Provoost, Jeroen; Shen, Rui; Ma, Jianqing; Liu, Jing

    2015-04-09

    The basis upon which recommended attenuation factors for vapor intrusion (VI) have been derived are reconsidered. By making a fitting curve to the plot showing the dependence of observed indoor air concentration (c(in)) on subslab concentration (c(ss)) for residences in EPA database, an analytical equation is obtained to identify the relationship among c(in), css and the averaged background level. The new relationship indicates that subslab measurements may serve as a useful guide only if c(ss) is above 500 μg/m(3). Otherwise, c(in) is independent of c(ss), with a distribution in good agreements with other studies of background levels. Therefore, employing this screening value (500 μg/m(3)), new contaminant concentration attenuation factors are proposed for VI, and the values for groundwater-to-indoor and subslab-to-indoor air concentration attenuation factors are 0.004 and 0.02, respectively. The former is applied to examining the reported temporal variations of c(in) obtained during a long-term monitoring study. The results show that using this new groundwater-to-indoor air concentration attenuation factor also provides a reasonably conservative estimate of c(in).

  1. Vapor intrusion attenuation factors relative to subslab and source, reconsidered in light of background data

    Science.gov (United States)

    Yao, Yijun; Wu, Yun; Suuberg, Eric M.; Provoost, Jeroen; shen, Rui; Ma, Jianqing; Liu, Jing

    2016-01-01

    The basis upon which recommended attenuation factors for vapor intrusion (VI) have been derived are reconsidered. By making a fitting curve to the plot showing the dependence of observed indoor air concentration (cin) on subslab concentration (css) for residences in EPA database, an analytical equation is obtained to identify the relationship among cin, css and the averaged background level. The new relationship indicates that subslab measurements may serve as a useful guide only if css is above 500 μg / m3. Otherwise, cin is independent of css, with a distribution in good agreements with other studies of background levels. Therefore, employing this screening value (500 μg / m3), new contaminant concentration attenuation factors are proposed for VI, and the values for groundwater-to-indoor and subslab-to-indoor air concentration attenuation factors are 0.004 and 0.02, respectively. The former is applied to examining the reported temporal variations of cin obtained during a long-term monitoring study. The results show that using this new groundwater-to-indoor air concentration attenuation factor also provides a reasonably conservative estimate of cin. PMID:25618001

  2. Optical Properties of Nonspherical Particles of Size Comparable to the Wavelength of Light: Application to Comet Dust

    Science.gov (United States)

    Yanamandra-Fisher, Padmavati A.; Hanner, Martha S.

    1999-03-01

    Scattering calculations for nonspherical particles have been carried out in order to explain observed optical properties of cometary dust. We focused on two optical properties of cometary dust sensitive to particle shape: negative linear polarization at phase angles ≤21° and the 11.2-μm silicate emission feature. The discrete dipole approximation (DDA) method was employed to compute the scattering matrix for nonspherical silicate and absorbing particles of size comparable to the wavelength. Silicate particles with a variety of shapes and size parameterXeq∼2.5, corresponding to a linear dimension of 0.5-1.0 μm, can produce negative linear polarization at small phase angles, whereas carbon particles produce a strong positive maximum of polarization near phase angles of 90°. Mixtures of silicate and carbonaceous material, on a scale small compared to the wavelength, eliminate the negative polarization in this size range; however, macroscopic mixtures of silicate and carbon could yield the observed negative linear polarization at low phase angles (≤21°) and a maximum positive polarization at phase angle of 90°. The position of the 11.2-μm thermal emission peak observed in comets, attributed to crystalline olivine, depends strongly on particle shape even for particles much smaller than the wavelength and can be matched with anisotropic Mg-rich olivine for our model tetrahedra or moderately elongated bricks. Spheres and extreme shapes, such as disks or needles, appear to be ruled out. Approximately 20% crystalline olivine and 80% disordered olivine reproduces the observed spectra of comets with comparable peaks at 10 and 11.2μm, e.g., P/Halley, Bradfield 1987 XXIX, Mueller, Levy 1990 XX, and C/1995 O1 (Hale-Bopp). This study is an essential first step toward realistic modeling of comet dust as aggregates composed of nonspherical monomers having dimensions comparable to the wavelength of incident radiation.

  3. Expansion of a laser-produced silver plume in light background gases

    DEFF Research Database (Denmark)

    Amoruso, S.; Toftmann, B.; Schou, Jørgen

    2004-01-01

    The expansion of a silver ablation plume in a helium and an argon background gas has been studied over the pressure range 10(-6) to 1 mbar. The angular distribution of silver atoms deposited on an array of quartz-crystal microbalances as well as time-of-flight signals of the plume ions in both...... gases were measured. There is a distinct sharpening of the angular distribution of the ablated silver atoms in the helium gas within a narrow range from 0.2 to 0.4 mbar. In contrast, the width of the angular distribution in the argon gas increases throughout the interval. The time-of-flight signals show...

  4. Multiple-return single-photon counting of light in flight and sensing of non-line-of-sight objects at shortwave infrared wavelengths.

    Science.gov (United States)

    Laurenzis, Martin; Klein, Jonathan; Bacher, Emmanuel; Metzger, Nicolas

    2015-10-15

    Time-of-flight sensing with single-photon sensitivity enables new approaches for the localization of objects outside a sensor's field of view by analyzing backscattered photons. In this Letter, the authors have studied the application of Geiger-mode avalanche photodiode arrays and eye-safe infrared lasers, and provide experimental data of the direct visualization of backscattering light in flight, and direct vision and indirect vision of targets in line-of-sight and non-line-of-sight configurations at shortwave infrared wavelengths.

  5. Extragalactic background light: a measurement at 400 nm using dark cloud shadow - II. Spectroscopic separation of the dark cloud's light, and results★

    Science.gov (United States)

    Mattila, K.; Väisänen, P.; Lehtinen, K.; von Appen-Schnur, G.; Leinert, Ch.

    2017-09-01

    In a project aimed at measuring the optical extragalactic background light (EBL), we are using the shadow of a dark cloud. We have performed, with the ESO VLT/FORS, spectrophotometry of the surface brightness towards the high-galactic-latitude dark cloud Lynds 1642. A spectrum representing the difference between the opaque core of the cloud and several unobscured positions around the cloud was presented in Paper I. The topic of this paper is the separation of the scattered starlight from the dark cloud itself which is the only remaining foreground component in this difference. While the scattered starlight spectrum has the characteristic Fraunhofer lines and the discontinuity at 400 nm, typical of integrated light of galaxies, the EBL spectrum is a smooth one without these features. As template for the scattered starlight, we make use of the spectra at two semitransparent positions. The resulting EBL intensity at 400 nm is IEBL = 2.9 ± 1.1 10-9 erg cm-2 s-1 sr-1 Å-1 or 11.6 ± 4.4 nW m-2sr-1, which represents a 2.6σ detection; the scaling uncertainty is +20 per cent/-16 per cent. At 520 nm, we have set a 2σ upper limit of IEBL ≤4.5 10-9 erg cm-2 s-1 sr-1 Å-1 or ≤ 23.4 nW m-2sr-1 +20 per cent/-16 per cent. Our EBL value at 400 nm is ≳ 2 times as high as the integrated light of galaxies. No known diffuse light sources, such as light from Milky Way halo, intra-cluster or intra-group stars appear capable of explaining the observed EBL excess over the integrated light of galaxies.

  6. Effects of different light wavelengths from LEDs on oxidative stress and apoptosis in olive flounder (Paralichthys olivaceus) at high water temperatures.

    Science.gov (United States)

    Kim, Bong-Seok; Jung, Seo Jin; Choi, Young Jae; Kim, Na Na; Choi, Cheol Young; Kim, Jae-Woo

    2016-08-01

    We investigated how different light spectra affect thermal stress in olive flounder (Paralichthys olivaceus), using light emitting diodes (LEDs; blue, 450 nm; green, 530 nm; red, 630 nm) at two intensities (0.3 and 0.5 W/m(2)) at relatively high water temperatures (25 and 30 °C, compared to a control condition of 20 °C). We measured the expression and activity of antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT), and the levels of plasma hydrogen peroxide (H2O2) and lipid peroxidation (LPO). Furthermore, the levels and mRNA expression of caspase-3 were measured, and terminal transferase dUTP nick end labeling (TUNEL) assays of liver and comet assays were performed. The expression and activity of antioxidant enzymes, as well as plasma H2O2 and LPO levels were significantly higher after exposure to high temperatures, and significantly lower after exposure to green and blue light. Caspase-3 levels and mRNA expression showed a similar pattern. The TUNEL assay showed that apoptosis markedly increased at higher water temperatures, compared with the 20 °C control. In contrast, green light irradiation decreased apoptosis rate. Furthermore, the comet assays showed that nuclear DNA damage was caused by thermal stress, and that green light irradiation played a role in partially preventing this damage. Overall, these results suggest that light with green and blue wavelengths can reduce both high temperature-induced oxidative stress and apoptosis, and that particularly green light is efficient for this. Therefore, green light can play a role in protecting in olive flounder from thermal stress damage.

  7. From Darkness to Light: Signatures of the Universe's First Galaxies in the Cosmic 21-cm Background

    Science.gov (United States)

    Mirocha, Jordan

    Within the first billion years after the Big Bang, the intergalactic medium (IGM) underwent a remarkable transformation, from a uniform sea of cold neutral hydrogen gas to a fully ionized, metal-enriched plasma. Three milestones during this Epoch of Reionization -- the emergence of the first stars, black holes, and full-fledged galaxies -- are expected to manifest as spectral "turning points" in the sky-averaged ("global") 21-cm background. However, interpreting these measurements will be complicated by the presence of strong foregrounds and non-trivialities in the radiative transfer (RT) required to model the signal. In this thesis, I make the first attempt to build the final piece of a global 21-cm data analysis pipeline: an inference tool capable of extracting the properties of the IGM and the Universe's first galaxies from the recovered signal. Such a framework is valuable even prior to a detection of the global 21-cm signal as it enables end-to-end simulations of 21-cm observations that can be used to optimize the design of upcoming instruments, their observing strategies, and their signal extraction algorithms. En route to a complete pipeline, I found that (1) robust limits on the physical properties of the IGM, such as its temperature and ionization state, can be derived analytically from the 21-cm turning points within two-zone models for the IGM, (2) improved constraints on the IGM properties can be obtained through simultaneous fitting of the global 21-cm signal and foregrounds, though biases can emerge depending on the parameterized form of the signal one adopts, (3) a simple four-parameter galaxy formation model can be constrained in only 100 hours of integration provided a stable instrumental response over a broad frequency range (~80 MHz), and (4) frequency-dependent RT solutions in physical models for the global 21-cm signal will be required to properly interpret the 21-cm absorption minimum, as the IGM thermal history is highly sensitive to the

  8. Simultaneously upgrading biogas and purifying biogas slurry using cocultivation of Chlorella vulgaris and three different fungi under various mixed light wavelength and photoperiods.

    Science.gov (United States)

    Cao, Weixing; Wang, Xue; Sun, Shiqing; Hu, Changwei; Zhao, Yongjun

    2017-10-01

    In order to purify biogas slurry and biogas simultaneously, three different fungi, Pleurotus geesteranus (P. geesteranus), Ganoderma lucidum (G. lucidum), and Pleurotus ostreatus (P. ostreatus) were pelletized with Chlorella vulgaris (C. vulgaris). The results showed that the optimal light wavelength ratio for red:blue was 5:5 for these three different fungi-assisted C. vulgaris, resulting in higher specific growth rate as well as nutrient and CO2 removal efficiency compared with other ratios. G. lucidum/C. vulgaris was screened as the best fungi-mialgae for biogas slurry purification and biogas upgrading with light/dark ratio of 14h:10h, which was also confirmed by the economic efficiency analysis of the energy consumptions. These results will provide a theoretical foundation for large-scale biogas slurry purifying and biogas upgrading using microalgae. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Holographic recording and characterization of photorefractive Bi{sub 2}TeO{sub 5} crystals at 633 nm wavelength light

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Ivan de, E-mail: ivan@ft.unicamp.br [Grupo de Óptica e Modelagem Numérica (GOMNI)-Faculdade de Tecnologia/UNICAMP, Limeira-SP (Brazil); Carvalho, Jesiel F., E-mail: carvalho@if.ufg.br; Fabris, Zanine V. [Instituto de Física/Universidade Federal de Goiás, Goiânia-GO (Brazil); Frejlich, Jaime, E-mail: frejlich@ifi.unicamp.br [Instituto de Física “Gleb Wataghin”/UNICAMP, Campinas-SP (Brazil)

    2014-04-28

    We report on the holographic recording on photorefractive Bi{sub 2}TeO{sub 5} crystals using λ=633 nm wavelength light. We studied the behavior of this material under the action of this low photonic energy light and found out the presence of a fast and a slow hologram, both of photorefractive nature and exhibiting rather high diffraction efficiencies. The faster and the slower holograms are based on the excitation and diffusion of oppositely charged carriers (likely electrons and holes). Relevant parameters for the photoactive centers responsible for both kind of holograms were characterized using purely holographic techniques. No evidences of non-photosensitive ionic charge carriers being involved in the recording process at room temperature nor self-fixing effects were found.

  10. Add-Drop Filter Based on Wavelength-Dependent Light Interlink between Lithium-Niobate Microwaveguide Chip and Microfiber Knot Ring

    Directory of Open Access Journals (Sweden)

    Suxu Zhou

    2016-06-01

    Full Text Available In this paper, we experimentally demonstrate an add-drop filter based on wavelength-dependent light coupling between a lithium-niobate (LN microwaveguide chip and a microfiber knot ring (MKR. The MKR was fabricated from a standard single-mode fiber, and the LN microwaveguide chip works as a robust substrate to support the MKR. The guided light can be transmitted through add and drop functionality and the behaviors of the add-drop filter can be clearly observed. Furthermore, its performance dependence on the MKR diameter is also studied experimentally. The approach, using a LN microwaveguide chip as a platform to couple and integrate the MKR, may enable us to realize an optical interlink between the microstructured chip and the micro/nano fiber-optic device.

  11. Detection of fruit by the Cerrado's marmoset (Callithrix penicillata): modeling color signals for different background scenarios and ambient light intensities.

    Science.gov (United States)

    Perini, Eduardo Sosti; Pessoa, Valdir Filgueiras; Pessoa, Daniel Marques de Almeida

    2009-04-01

    Among placental mammals, only primates have trichromatic color vision, however this is not a uniform condition. Under different genetic status, Old World monkeys have routine trichromacy, while New World monkeys show a visual polymorphism, characterized by obligatory male dichromacy. The ecological role of this genetic difference still remains unclear, but some studies show that dichromats and trichromats appear to have different abilities in detecting colored targets against a background of leaves. The Cerrado's marmoset (Callithrix penicillata) is known to forage in brightly illuminated (savanna-like vegetation) and dimly illuminated (forests) environments, exploiting a high amount of dark fruits. Hence, it seems to be a good model for studying the differential advantages enjoyed by each color vision phenotype under natural conditions. Our aim was to verify how the different phenotypes of Cerrado's marmoset detect components of their diet, evaluating the existence of differential phenotype advantages. Under two different light conditions, visual signals of naturally consumed fruits were modeled against different backgrounds scenarios. Even though dichromats and trichromats appear to be equally suited for tasks involving fruit detection, phenotype differential advantages are observed in this marmoset. In many conditions trichromats are predicted to perform better than dichromats, but under low ambient light dichromats manage to outperform trichromats in some scenarios. Phenotypes that carry widely spaced and longer M/L pigments enjoy the most advantage. These differential performances of trichromatic phenotypes, together with overdominance selection, seem to explain the maintenance of the tri-allelic system found in callitrichids.

  12. Effect of light wavelength on cell growth, content of phenolic compounds and antioxidant activity in cell suspension cultures of Thevetia peruviana.

    Science.gov (United States)

    Arias, J P; Zapata, K; Rojano, B; Arias, M

    2016-10-01

    Thevetia peruviana (T. peruviana) has been considered as a potentially important plant for industrial and pharmacological application. Among the number of compounds which are produced by T. peruviana, antioxidants and polyphenols are of particular interest due to their benefits on human health. Cell suspension cultures of T. peruviana were established under different conditions: 1) constant illumination (24h/day) at different light wavelengths (red, green, blue, yellow and white), 2) darkness and 3) control (12h/12h: day light/dark) to investigate their biomass, substrate uptake, polyphenols production and oxidizing activity. The results showed biomass concentrations between 17.1g dry weight (DW)/l (green light) and 18.2g DW/l (control) after 13days. The cultures that grew under green light conditions consumed completely all substrates after 10days, while other cultures required at least 13days or more. The total phenolic content was between 7.21 and 9.46mg gallic acid (GA)/g DW for all light conditions. In addition the ferric reducing antioxidant power and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid antioxidant activity ranged from 5.41-6.58mg ascorbic acid (AA)/g DW and 82.93-110.39μmol Trolox/g DW, respectively. Interestingly, the samples which grew under the darkness presented a higher phenolic content and antioxidant capacity when compared to the light conditions. All together, these results demonstrate the extraordinary effect of different lighting conditions on polyphenols production and antioxidant compounds by T. peruviana. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. The effect of light-emitting diode irradiation at different wavelengths on calcification of osteoblast-like cells in 3D culture.

    Science.gov (United States)

    Chintavalakorn, Rochaya; Tanglitanont, Tatsanee; Khantachawana, Anak; Viravaidya-Pasuwat, Kwanchanok; Santiwong, Peerapong

    2015-08-01

    This study aimed to investigate the effect of four different light-emitting diode (LED) wavelengths on calcification and proliferation of osteoblast-like cells in vitro. MC3T3-E1 cells were seeded within three-dimensional collagen scaffolds and irradiated daily by LED light with peak emission wavelengths of 630-, 680-, 760- and 830-nm at constant fluency of 3.1 J/cm(2) (irradiance intensity 2 mW/cm(2)). Cultures were measured for calcium content at day 0, 7, 14, 21, 28, 35 and 42. The significant enhancement in calcium content was observed at the early stage of culture (days 7 and 14) (plight irradiation on osteoblastic cell calcification. Only 680-nm irradiated samples revealed a significant enhancement of calcium content until the late stages of culture (from days 21 to 42) (p<;0.001). The cyclin D mRNA expression that was investigated 3 hours after stimulation at day3 also show that the 680-nm LED irradiation can enhance cyclin D expression more than others. For enhancing bone mineralization, LED irradiation at the 680-nm is more effective than those at 630-, 760- and 830-nm. Further studies should be investigated in order to obtain the most effective parameters of LLLI on bone regeneration in clinical setting.

  14. Evaluation of light scattering properties and chromophore concentrations in skin tissue based on diffuse reflectance signals at isosbestic wavelengths of hemoglobin

    Science.gov (United States)

    Yokokawa, Takumi; Nishidate, Izumi

    2016-04-01

    We investigate a method to evaluate light-scattering properties and chromophore concentrations in human skin tissue through diffuse reflectance spectroscopy using the reflectance signals acquired at isosbestic wavelengths of hemoglobin (420, 450, 500, and 585 nm). In the proposed method, Monte Carlo simulation-based empirical formulas are used to specify the scattering parameters of skin tissue, such as the scattering amplitude a and the scattering power b, as well as the concentration of melanin C m and the total blood concentration C tb. The use of isosbestic wavelengths of hemoglobin enables the values of C m, C tb, a, and b to be estimated independently of the oxygenation of hemoglobin. The spectrum of the reduced scattering coefficient is reconstructed from the scattering parameters. Experiments using in vivo human skin tissues were performed to confirm the feasibility of the proposed method for evaluating the changes in scattering properties and chromophore concentrations in skin tissue. The experimental results revealed that light scattering is significantly reduced by the application of a glycerol solution, which indicates an optical clearing effect due to osmotic dehydration and the matching of the refractive indices of scatterers in the epidermis.

  15. Three-dimensional concentration of light in deeply sub-wavelength, laterally tapered gap-plasmon nanocavities

    Energy Technology Data Exchange (ETDEWEB)

    Tagliabue, Giulia [Laboratory of Thermodynamics in Emerging Technologies, ETH Zurich, Zurich 8092 (Switzerland); Thomas J. Watson, Sr. Laboratories of Applied Physics, California Institute of Technology, Pasadena, California 91125 (United States); Poulikakos, Dimos; Eghlidi, Hadi, E-mail: eghlidim@ethz.ch [Laboratory of Thermodynamics in Emerging Technologies, ETH Zurich, Zurich 8092 (Switzerland)

    2016-05-30

    Gap-plasmons (GP) in metal-insulator-metal (MIM) structures have shown exceptional performance in guiding and concentrating light within deep subwavelength layers. Reported designs to date exploit tapered thicknesses of the insulating layer in order to confine and focus the GP mode. Here, we propose a mechanism for the three dimensional concentration of light in planar MIM structures which exploits exclusively the lateral tapering of the front metallic layer while keeping a constant thickness of the insulating layer. We demonstrate that an array of tapered planar GP nanocavities can efficiently concentrate light in all three dimensions. A semi-analytical, one-dimensional model provides understanding of the underlying physics and approximately predicts the behavior of the structure. Three-dimensional simulations are then used to precisely calculate the optical behavior. Cavities with effective volumes as small as 10{sup −5} λ{sup 3} are achieved in an ultrathin MIM configuration. Our design is inherently capable of efficiently coupling with free-space radiation. In addition, being composed of two electrically continuous layers separated by an ultrathin dielectric spacer, it could find interesting applications in the area of active metamaterials or plasmonic photocatalysis where both electrical access and light concentration are required.

  16. Effect of different wavelengths of light on the antioxidant and immunity status of juvenile rock bream, Oplegnathus fasciatus, exposed to thermal stress

    Science.gov (United States)

    Choe, Jong Ryeol; Shin, Yoon Sub; Choi, Ji Yong; Kim, Tae Hwan; Jung, Min-Min; Choi, Cheol Young

    2017-09-01

    We investigated the effect of light wavelengths on antioxidant and immunity parameters in juvenile rock bream, Oplegnathus fasciatus, exposed to thermal stress (25 and 30°C). We exposed the fish to light emitting diodes (LEDs) emitting green (520 nm) and red light (630 nm) of 0.25 and 0.5 W/m2 intensity, and measured the activity, and mRNA and protein expression levels of the antioxidant enzymes, superoxide dismutase, catalase, and glutathione peroxidase. We also determined the levels of plasma hydrogen peroxide (H2O2), melatonin, and lysozyme. Furthermore, the mRNA and protein levels of caspase-3 were measured and terminal transferase dUTP nick end labeling (TUNEL) assays were performed. We observed that mRNA expression and activities of antioxidant enzymes and plasma H2O2 levels were significantly higher after exposure to high temperatures. However, increases in these parameters were significantly lower after exposure to green LED light. The plasma melatonin and lysozyme levels were significantly lower in the different groups after exposure to high temperatures; however, in groups exposed to green LED light, their levels were significantly higher than those in the control group. The expression pattern of caspase-3 mRNA was similar to that of H2O2. The TUNEL assay showed that apoptosis was markedly higher at higher water temperatures than that at 20°C. These results indicate that high water temperatures induce oxidative stress and decrease the immunity in juvenile rock bream but green LED light inhibits the rise in oxidative stress and combats the decrease in immunity and should, thus, be useful in the culture of rock bream.

  17. Implications for photonic applications of diatom growth and frustule nanostructure changes in response to different light wavelengths

    OpenAIRE

    Su, Yanyan; Lundholm, Nina; Friis, Søren Michael Mørk; Ellegaard, Marianne

    2015-01-01

    Diatoms are unicellular algae enclosed in intricate bio - silicified walls with repetitive nanostructures in a size range which makes them potentially relevant for a broad spectrum of industrial applications. How to optimize the nano - scale structures of the frustule for utilization of diatoms in nanotechnology is one of the technological challenges for these applications. Light is one of the most important abiotic factors for algal photosynthetic growth, and the frustule may play an importa...

  18. Quantitative analysis with advanced compensated polarized light microscopy on wavelength dependence of linear birefringence of single crystals causing arthritis

    Science.gov (United States)

    Takanabe, Akifumi; Tanaka, Masahito; Taniguchi, Atsuo; Yamanaka, Hisashi; Asahi, Toru

    2014-07-01

    To improve our ability to identify single crystals causing arthritis, we have developed a practical measurement system of polarized light microscopy called advanced compensated polarized light microscopy (A-CPLM). The A-CPLM system is constructed by employing a conventional phase retardation plate, an optical fibre and a charge-coupled device spectrometer in a polarized light microscope. We applied the A-CPLM system to measure linear birefringence (LB) in the visible region, which is an optical anisotropic property, for tiny single crystals causing arthritis, i.e. monosodium urate monohydrate (MSUM) and calcium pyrophosphate dihydrate (CPPD). The A-CPLM system performance was evaluated by comparing the obtained experimental data using the A-CPLM system with (i) literature data for a standard sample, MgF2, and (ii) experimental data obtained using an established optical method, high-accuracy universal polarimeter, for the MSUM. The A-CPLM system was found to be applicable for measuring the LB spectra of the single crystals of MSUM and CPPD, which cause arthritis, in the visible regions. We quantitatively reveal the large difference in LB between MSUM and CPPD crystals. These results demonstrate the usefulness of the A-CPLM system for distinguishing the crystals causing arthritis.

  19. Microlensing of Sub-parsec Massive Binary Black Holes in Lensed QSOs: Light Curves and Size-Wavelength Relation

    CERN Document Server

    Yan, Chang-Shuo; Yu, Qingjuan; Mao, Shude; Wambsganss, Joachim

    2014-01-01

    Sub-parsec binary massive black holes (BBHs) are long anticipated to exist in many QSOs but remain observationally elusive. In this paper, we propose a novel method to probe sub-parsec BBHs through microlensing of lensed QSOs. If a QSO hosts a sub-parsec BBH in its center, it is expected that the BBH is surrounded by a circum-binary disk, each component of the BBH is surrounded by a small accretion disk, and a gap is opened by the secondary component in between the circum-binary disk and the two small disks. Assuming such a BBH structure, we generate mock microlensing light curves for some QSO systems that host BBHs with typical physical parameters. We show that microlensing light curves of a BBH QSO system at the infrared-optical-UV bands can be significantly different from those of corresponding QSO system with a single massive black hole (MBH), mainly because of the existence of the gap and the rotation of the BBH (and its associated small disks) around the center of mass. We estimate the half-light radii ...

  20. Long-Wavelength InAs/GaAs Quantum-Dot Light Emitting Sources Monolithically Grown on Si Substrate

    Directory of Open Access Journals (Sweden)

    Siming Chen

    2015-06-01

    Full Text Available Direct integration of III–V light emitting sources on Si substrates has attracted significant interest for addressing the growing limitations for Si-based electronics and allowing the realization of complex optoelectronics circuits. However, the high density of threading dislocations introduced by large lattice mismatch and incompatible thermal expansion coefficient between III–V materials and Si substrates have fundamentally limited monolithic epitaxy of III–V devices on Si substrates. Here, by using the InAlAs/GaAs strained layer superlattices (SLSs as dislocation filter layers (DFLs to reduce the density of threading dislocations. We firstly demonstrate a Si-based 1.3 µm InAs/GaAs quantum dot (QD laser that lases up to 111 °C, with a low threshold current density of 200 A/cm2 and high output power over 100 mW at room temperature. We then demonstrate the operation of InAs/GaAs QD superluminescent light emitting diodes (SLDs monolithically grown on Si substrates. The fabricated two-section SLD exhibits a 3 dB linewidth of 114 nm, centered at ~1255 nm with a corresponding output power of 2.6 mW at room temperature. Our work complements hybrid integration using wafer bonding and represents a significant milestone for direct monolithic integration of III–V light emitters on Si substrates.

  1. Wavelength-tuned light emission via modifying the band edge symmetry: Doped SnO2 as an example

    KAUST Repository

    Zhou, Hang

    2014-03-27

    We report the observation of ultraviolet photoluminescence and electroluminescence in indium-doped SnO2 thin films with modified "forbidden" bandgap. With increasing indium concentration in SnO 2, dominant visible light emission evolves into the ultraviolet regime in photoluminescence. Hybrid functional first-principles calculations demonstrate that the complex of indium dopant and oxygen vacancy breaks "forbidden" band gap to form allowed transition states. Furthermore, undoped and 10% indium-doped SnO2 layers are synthesized on p-type GaN substrates to obtain SnO2-based heterojunction light-emitting diodes. A dominant visible emission band is observed in the undoped SnO 2-based heterojunction, whereas strong near-ultraviolet emission peak at 398 nm is observed in the indium-doped SnO2-based heterojunction. Our results demonstrate an unprecedented doping-based approach toward tailoring the symmetry of band edge states and recovering ultraviolet light emission in wide-bandgap oxides. © 2014 American Chemical Society.

  2. A search for the Sunyaev-Zel'dovich effect at millimeter wavelengths. [cosmic background photon energy increase due to Compton scattering by high temperature galactic cluster plasma electrons

    Science.gov (United States)

    Meyer, S. S.; Jeffries, A. D.; Weiss, R.

    1983-01-01

    It is believed that X-ray emission from clusters of galaxies represents thermal bremsstrahlung from a hot plasma. According to Sunyaev and Zel'dovich (1972), the plasma column density and temperature derived from this model imply a measurable distortion of the cosmic background radiation (CBR) in the cluster direction. This distortion results from the Compton scattering of the CBR photons by the electrons in the plasma, resulting in an average increase of each photon. This process, known as the Sunyaev-Zel'dovich effect, is photon conserving and 'shifts' the CBR spectrum to higher frequencies. The result is a decrease of flux at frequencies below 7.5 per cm (the Rayleigh-Jeans region), and an increase above. The investigation is concerned with measurements of the Sunyaev-Zel'dovich effect at frequencies in the range from 3 to 10 per cm. Attention is given to the employed observing and analysis technique, and an initial null result for the cluster Abell 1795.

  3. Plasmonic color-graded nanosystems with achromatic sub-wavelength architectures for light filtering and advanced SERS detection

    KAUST Repository

    Proietti Zaccaria, Remo

    2016-03-09

    Plasmonic colour-graded systems are devices featuring a spatially variable plasmonic response over their surface. They are widely used as nanoscale colour filters; their typical size is small enough to allow integration with miniaturized electronic circuits paving the way to realize novel nanophotonic devices. Currently, most plasmonic colour-graded systems are intrinsically discrete, as their chromatic response exploits the tailored plasmon resonance of micro-architectures characterized by different size and/or geometry for each target colour. Here we report the realization of multifunctional plasmon-graded devices where continuously-graded chromatic response is achieved by smoothly tuning the composition of the resonator material while simultaneously maintaining an achromatic nanoscale geometry. The result is a new class of versatile materials: we show their application as plasmonic filters with a potential pixel size smaller than half of the exciting wavelength, but also as multiplexed surface-enhanced Raman spectroscopy (SERS) substrates. Many more implementations, like photovoltaic efficiency boosters or colour routers await, and will benefit from the low fabrication cost and intrinsic plasmonic flexibility of the presented systems.

  4. Growth Kinetic of Ag Clots Created by Laser Light of Various Wavelength on Microcrystals AgBr

    Directory of Open Access Journals (Sweden)

    Yu.М. Lopatkin

    2013-03-01

    Full Text Available In this paper the kinetics of the growth of Ag clusters in AgBr microcrystals of the photographic emulsion SP-1 with sensitivity 6 units GOST during illuminating with laser radiation λ = 490 nm, Р = 10 mW; λ = 633 nm, Р = 10 mW, Р = 2.5 mW, Р = 0.98 mW; λ = 850 nm, Р = 10 mW; λ = 325 nm, Р = 3 mW was investigated using the computer model and found that the influence of the laser light power on the growth of Ag clusters more efficiently than the photon energy.

  5. Effects of radiant exposure and wavelength spectrum of light-curing units on chemical and physical properties of resin cements

    Directory of Open Access Journals (Sweden)

    Adriano Fonseca Lima

    2016-11-01

    Full Text Available Objectives In this study, we evaluated the influence of different radiant exposures provided by single-peak and polywave light-curing units (LCUs on the degree of conversion (DC and the mechanical properties of resin cements. Materials and Methods Six experimental groups were established for each cement (RelyX ARC, 3M ESPE; LuxaCore Dual, Ivoclar Vivadent; Variolink, DMG, according to the different radiant exposures (5, 10, and 20 J/cm2 and two LCUs (single-peak and polywave. The specimens were made (7 mm in length × 2 mm in width × 1 mm in height using silicone molds. After 24 hours of preparation, DC measurement was performed using Fourier transform infrared spectrometry. The same specimens were used for the evaluation of mechanical properties (flexural strength, FS; elastic modulus, E by a three-point bending test. Data were assessed for normality, after which two-way analysis of variance (ANOVA and post hoc Tukey's test were performed. Results No properties of the Variolink cement were influenced by any of the considered experimental conditions. In the case of the RelyX ARC cement, DC was higher when polywave LCU was used; FS and E were not influenced by the conditions evaluated. The LuxaCore cement showed greater sensitivity to the different protocols. Conclusions On the basis of these results, both the spectrum of light emitted and the radiant exposure used could affect the properties of resin cements. However, the influence was material-dependent.

  6. The Diffuse Light of the Universe - On the Microwave Background Before and After Its Discovery: Open Questions

    Science.gov (United States)

    Bonnet-Bidaud, Jean-Marc

    2016-12-01

    In 1965, the discovery of a new type of uniform radiation, located between radiowaves and infrared light, was accidental. Known today as Cosmic Microwave background (CMB), this diffuse radiation is commonly interpreted as a fossil light released in an early hot and dense universe and constitutes today the main 'pilar' of the big bang cosmology. Considerable efforts have been devoted to derive fundamental cosmological parameters from the characteristics of this radiation that led to a surprising universe that is shaped by at least three major unknown components: inflation, dark matter and dark energy. This is an important weakness of the present consensus cosmological model that justifies raising several questions on the CMB interpretation. Can we consider its cosmological nature as undisputable? Do other possible interpretations exist in the context of other cosmological theories or simply as a result of other physical mechanisms that could account for it? In an effort to questioning the validity of scientific hypotheses and the under-determination of theories compared to observations, we examine here the difficulties that still exist on the interpretation of this diffuse radiation and explore other proposed tracks to explain its origin. We discuss previous historical concepts of diffuse radiation before and after the CMB discovery and underline the limit of our present understanding.

  7. Modulating dual-wavelength multiple quantum wells in white light emitting diodes to suppress efficiency droop and improve color rendering index

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yukun; Wang, Shuai; Zheng, Min; Ding, Wen [Key Laboratory of Physical Electronics and Devices of Ministry of Education and Shaanxi Provincial Key Laboratory of Photonics & Information Technology, Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China); Solid-State Lighting Engineering Research Center, Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China); Yun, Feng, E-mail: fyun2010@mail.xjtu.edu.cn [Key Laboratory of Physical Electronics and Devices of Ministry of Education and Shaanxi Provincial Key Laboratory of Photonics & Information Technology, Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China); Solid-State Lighting Engineering Research Center, Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China); Shaanxi Supernova Lighting Technology Co. Ltd, Xi' an, Shaanxi 710075 (China); Su, Xilin; Yang, Xiangrong; Liu, Shuo [Shaanxi Supernova Lighting Technology Co. Ltd, Xi' an, Shaanxi 710075 (China); Guo, Maofeng [Solid-State Lighting Engineering Research Center, Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China); Shaanxi Supernova Lighting Technology Co. Ltd, Xi' an, Shaanxi 710075 (China); Zhang, Ye [Solid-State Lighting Engineering Research Center, Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China)

    2015-10-14

    In this paper, gallium nitride (GaN) based white light-emitting diodes (WLEDs) with modulated quantities of blue (In{sub 0.15}Ga{sub 0.85}N) quantum wells (QWs) and cyan QWs (In{sub 0.18}Ga{sub 0.82}N) in multiple QW (MQW) structures have been investigated numerically and experimentally. It is demonstrated that the optical performance of LEDs is sensitive to the quantities of cyan QWs in dual-wavelength MQW structures. Compared to the LEDs with respective 0, 4, and 8 cyan QWs (12 QWs in total), the optical performance of the sample with 6 cyan QWs is the best. The deterioration of the optical performance in the sample with less (4 pairs) cyan QWs or more (8 pairs) cyan QWs than 6 cyan QWs may be ascribed to weakened reservoir effect or more defects induced. Compared to conventional blue LEDs (12 blue QWs), the sample with 6 cyan QWs could effectively suppress the efficiency droop (the experimental droop ratio decreases from 50.3% to 39.5% at 80 A/cm{sup 2}) and significantly improve the color rendering index (CRI, increases from 66.4 to 77.0) simultaneously. We attribute the droop suppression to the strengthened reservoir effect and carrier confinement of deeper QWs (higher indium composition) incorporated in the dual-wavelength MQW structures, which lead to the better hole spreading and enhanced radiative recombination. Meanwhile, the remarkable experimental CRI improvement may result from the wider full-width at half-maximum of electroluminescence spectra and higher cyan intensity in WLED chips with dual-wavelength MQW structures.

  8. Impact of brown and clear carbon on light absorption enhancement, single scatter albedo and absorption wavelength dependence of black carbon

    Directory of Open Access Journals (Sweden)

    D. A. Lack

    2010-01-01

    Full Text Available The presence of clear coatings on atmospheric black carbon (BC particles is known to enhance the magnitude of light absorption by the BC cores. Based on calculations using core/shell Mie theory, we demonstrate the enhancement of light absorption (EAbs by atmospheric black carbon (BC when coated in mildly absorbing material (CBrown is reduced, relative to the enhancement by non-absorbing coatings (CClear. This reduction, sensitive to CBrown shell thickness and imaginary refractive index (RI, can be up to 50% for 400 nm radiation and 25% averaged across the visible radiation spectrum for reasonable core/shell diameters. The enhanced direct radiative forcing possible due to the enhancement effect of CClear is therefore reduced if the coating is absorbing. Additionally, the need to explicitly treat BC as an internal, as opposed to external, mixture with CBrown is shown to be important to the calculated single scatter albedo only whensub models treat BC as large spherical cores (>50 nm. For smaller BC cores (or fractal agglomerates consideration of the BC and CBrown as an external mixture leads to relatively small errors in the particle single scatter albedo of <0.03. It is often assumed that observation of an absorption Angstrom exponent (AAE >1 indicates non-BC absorption. Here, it is shown that BC cores coated in CClearcan reasonably have an AAE of up to 1.6, a result that complicates the attribution of observed light absorption to CBrown within ambient particles. However, an AAE<1.6 does not exclude the possibility of CBrown, rather CBrown cannot be confidently assigned unless AAE>1.6. Comparison of these results to some ambient AAE data shows that large-scale attribution of CBrown is a challenging task using current in-situ measurement methods. We suggest that coincident measurements of particle core and

  9. 多光源白光干涉仪的最佳波长组合%The Optimum Wavelength Combination in Multi-Light-Source White-Light Interferometer

    Institute of Scientific and Technical Information of China (English)

    宋桂菊; 方祖捷; 王向朝

    2001-01-01

    The interference signal of white-light interferometer with several broadband light sources is the superposition of those only with one broadband light source. Then the signal intensity is redistributed. An optimum wavelength combination that makes the intensity difference between zero-order and first-order fringe increase is found by theoretical analysis and computer simulations. The use of the optimum wavelength combination results in the more accurate determination of zero-order fringe, the enhancement of the system resolution, and the decrease of the needed signal-noise-ratio for identifying zero-order fringe. The method to select the optimum wavelength combination is also presented.%使用多个宽带光源构成的组合光源的白光干涉仪,其干涉信号为单个光源干涉信号的叠加,从而使干涉信号强度重新分布。通过理论分析和计算机模拟,发现一个最佳波长组合,使干涉信号零级条纹与次级极大条纹的强度差变大,且由于它的使用可以更精确地确定零级中心条纹的位置,提高系统分辨率,降低对系统信噪比的要求。并提出了选择最佳波长组合的方法

  10. Novel InN/InGaN multiple quantum well structures for slow-light generation at telecommunication wavelengths

    Energy Technology Data Exchange (ETDEWEB)

    Naranjo, F.B.; Valdueza-Felip, S.; Gonzalez-Herraez, M. [Grupo de Ingenieria Fotonica, Departamento de Electronica, Escuela Politecnica Superior, Universidad de Alcala Campus Universitario, 28871 Alcala de Henares, Madrid (Spain); Kandaswamy, P.K.; Lahourcade, L.; Calvo, V.; Monroy, E. [CEA-Grenoble, INAC/SP2M, 17 rue des Martyrs, 38054 Grenoble cedex 9 (France); Martin-Lopez, S.; Corredera, P. [Departamento de Metrologia, Instituto de Fisica Aplicada (CSIC), 28006 Madrid (Spain)

    2010-01-15

    The third order susceptibility is responsible for a variety of optical non-linear phenomena - like self focusing, phase conjugation and four-wave mixing - with applications in coherent control of optical communication. InN is particularly attractive due to its near-IR bandgap and predicted high nonlinear effects. Moreover, the synthesis of InN nanostructures makes possible to taylor the absorption edge in the telecomunication spectral range and enhance nonlinear parameters thanks to carrier confinement. In this work, we assess the nonlinear optical behavior of InN/In{sub x}Ga{sub (1-x)}N (0.9 > x > 0.7) multiple-quantum-well (MQW) structures grown by plasma-assisted MBE on GaN-on-sapphire templates. Low-temperature (5 K) photoluminescence measurements show near-IR emission whose intensity increases with the In content in the barriers, which is explained in terms of the existence of piezoelectric fields in the structures. The nonlinear optical absorption coefficient, {alpha}{sub 2}, were measured at 1.55 {mu}m using the Z-scan method. We observe a strong dependence of the nonlinear absorption coefficient on the In content in the barriers. Saturable absorption is observed for the sample with x = 0.9, with {alpha}{sub 2} {proportional_to} -9 x 10{sub 3} cm/GW. For this sample, an optically controlled reduction of the speed of light by a factor S {proportional_to} 80 is obtained at 1.55 {mu}m (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Far field photoluminescence imaging of single AlGaN nanowire in the sub-wavelength scale using confinement of polarized light

    Energy Technology Data Exchange (ETDEWEB)

    Sivadasan, A.K.; Dhara, Sandip [Nanomaterials and Sensors Section, Surface and Nanoscience Division, Indira Gandhi Centre for Atomic Research, Homi Bhabha National Institute, Kalpakkam (India); Sardar, Manas [Theoretical Studies Section, Materials Physics Division, Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

    2017-03-15

    Till now the nanoscale focusing and imaging in the sub-diffraction limit is achieved mainly with the help of plasmonic field enhancement by confining the light assisted with noble metal nanostructures. Using far field imaging technique, we have recorded polarized spectroscopic photoluminescence (PL) imaging of a single AlGaN nanowire (NW) of diameter ∝100 nm using confinement of polarized light. It is found that the PL from a single NW is influenced by the proximity to other NWs. The PL intensity is proportional to 1/(l x d), where l and d are the average NW length and separation between the NWs, respectively. We suggest that the proximity induced PL intensity enhancement can be understood by assuming the existence of reasonably long lived photons in the intervening space between the NWs. A nonzero non-equilibrium population of such photons may cause stimulated emission leading to the enhancement of PL emission with the intensity proportional to 1/(l x d). The enhancement of PL emission facilitates far field spectroscopic imaging of a single semiconductor AlGaN NW of sub-wavelength dimension. (copyright 2016 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Extragalactic background light absorption signal in the 0.26-10 TeV spectra of blazars

    CERN Document Server

    Vasilev, V

    1999-01-01

    Recent observations of the TeV gamma-ray spectra of the two closest active galactic nuclei (AGNs), Markarian 501 (Mrk 501) and Markarian 421 (Mrk 421), by the Whipple and HEGRA collaborations have stimulated efforts to estimate or limit the spectral energy density (SED) of extragalactic background light (EBL) which causes attenuation of TeV photons via pair-production when they travel cosmological distances. In spite of the lack of any distinct cutoff-like feature in the spectra of Mrk 501 and Mrk 421 (in the interval 0.26-10 TeV) which could clearly indicate the presence of such a photon absorption mechanism, we demonstrate that strong EBL attenuation signal (survival probability of 10 TeV photon (~10^{-2}) may still be present in the spectra of these AGNs. This attenuation could escape detection due to a special form of SED of EBL and unknown intrinsic spectra of these blazars. Here we show how the proposed and existing experiments, VERITAS, HESS, MAGIC, STACEE and CELESTE may be able to detect or severely ...

  13. A QVGA-size CMOS time-of-flight range image sensor with background light charge draining structure

    Science.gov (United States)

    Ushinaga, Takeo; Halin, Izhal Abdul; Sawada, Tomonari; Kawahito, Shoji; Homma, Mitsuru; Maeda, Yasunari

    2006-02-01

    3-D imaging systems can be used in a variety of applications such as in automobile, medicine, robot vision systems, security and so on. Recently many kinds of range finding methods have been proposed for 3-D imaging systems. This paper presents a new type of CMOS range image sensor based on the Time-of-Flight (TOF)principle with a spatial resolution of 336 × 252 (QVGA) and pixels of 15 × 15 μm2 size. A pixel structure of the sensor consists of single layer polysilicon gates on thick field oxide and has a function of background light induced charge reduction. The chip was fabricated in a 0.35 μm standard CMOS process with two poly and three metal layers. The presented sensor achieves a minimum range resolution of 2.8cm at framerate of 30fps and the resolution is improved to 4.2mm for 10 frames averaging, which corresponds to 3fps.

  14. Synergetic effect of green tea on polymer gel dosimeter and determination of optimal wavelength to choose light source for optical computed tomography

    Directory of Open Access Journals (Sweden)

    Sathiya Raj

    2016-03-01

    Full Text Available Purpose: The ultimate aim of this study is to observe the effect of Green tea as a co-antioxidant in PAGAT gel dosimeter and evaluate the appropriate light source for scanning the PAGAT and NIPAM polymer gel.Methods: Both PAGAT (Poly Acrylamide Gelatin Tetrakis hydroxyl phosphonium chloride and NIPAM (N-Isopropyl acrylamide gel were prepared in normoxic condition. The green tea extract (GTE was prepared and tested only on PAGAT. Co-60 teletherapy machine has been used for irradiation purpose, and the gel samples were scanned using UV-Visible spectrophotometer. Water equivalency of the gel has been tested in terms of their electron density, effective atomic number and Ratio of oxygen and hydrogen (O/H. We have used NIST XCOM database to test the water equivalency.Results: In this study we found that the GTE added to the gel do not respond to the given doses. By adding sugar we can enhance the sensitivity of the gel. Further investigations are required to use Green tea as a co antioxidant concentration of THPC (Tetrakis hydroxymethyl phosphonium chloride. The optimal wavelength with different region for scanning the PAGAT is 450 to 480 nm (Blue region, for NIPAM it is 540 nm and 570 nm (Green and yellow region. The PAGAT and NIPAM showed better sensitivity at 510 nm. Both gels have their effective atomic number closer to water (NIPAM-7.2, PAGAT-7.379.Conclusion: As per our results, we concluded that GTE alone is not an effective co-antioxidant for polymer gels. When the GTE is combined with sugar and THPC, it protects the gel from pre-polymerization. This study strongly suggests that the blue light is an optimal source for scanning the PAGAT and green to yellow light for NIPAM gel. Though both gels were considered as water equivalent, the PAGAT is equivalent to water and the temporal stability of this gel is higher than NIPAM.

  15. Study on the Wavelength Shifts of GaN-based Light Emitting Diodes%GaN基发光二极管波长偏移的研究

    Institute of Scientific and Technical Information of China (English)

    庄榕榕; 蔡平

    2013-01-01

    Wavelength shifts of the GaN-based green light emitting diode (LED) were tested under different environment temperature and driving current. The results showed that when increasing either environment temperature or drive current, the junction temperature of LED will always rise along, while the variation of peak wavelength is different in either case. The peak wavelength of LED will blueshift when environmental temperature is constant and drive current increases. When drive current stay constant and environment temperature increases, the peak wavelength of LED becomes redshifted. The polarization built-in field intensity was estimated using polarization field coupling model theory. The polarization intensity in the well of In0.25GaN0.75 is 3.304 MVcm-1, the polarization field strength of barrier layer is -0.826 MVcm-1. Energy gap variable change rate relevant to junction temperature variation is introduced into analysis for the first time. Within the rated drive current of LED, the energy gap variable change rates relevant to junction temperature variation caused by heat effect and screening effect caused by carriers to the polarization built-in field is 3.637×10-4 evk-1 and 1.3025×10-3 evk-1 respectively. The study indicates that the energy gap change rate relevant to junction temperature variation caused by both effects determines the peak wavelength shifting direction.%在不同环境温度及不同驱动电流条件下,测试GaN基绿光发光二极管峰值波长的变化,结果表明,环境温度及驱动电流的增加,均会引起结温的增加,但是峰值波长的变化却有区别.在环境温度不变,驱动电流增加过程中,出现LED峰值波长的蓝移现象;在驱动电流不变、环境温度变化过程中,出现LED峰值波长的红移.用能带及极化场耦合模理论,分析实验结果,得到In0.25 GaN0.75阱层的极化场强为3.304MV/cm,垒层的极化场强为-0.826MV/cm;首次引入能隙变量随结温变化

  16. An Empirical Determination of the Intergalactic Background Light Using Near-Infrared Deep Galaxy Survey Data Out to 5 Micrometers and the Gamma-Ray Opacity of the Universe

    Science.gov (United States)

    Scully, Sean T.; Malkan, Matthew A.; Stecker, Floyd W.

    2014-01-01

    We extend our previous model-independent determination of the intergalactic background light, based purely on galaxy survey data, out to a wavelength of 5 micrometers. Our approach enables us to constrain the range of photon densities, based on the uncertainties from observationally determined luminosity densities and colors. We further determine a 68% confidence upper and lower limit on the opacity of the universe to gamma-rays up to energies of 1.6/(1 + z) terraelectron volts. A comparison of our lower limit redshift-dependent opacity curves to the opacity limits derived from the results of both ground-based air Cerenkov telescope and Fermi-LAT observations of PKS 1424+240 allows us to place a new upper limit on the redshift of this source, independent of IBL modeling.

  17. Light harvesting over a wide range of wavelength using natural dyes of gardenia and cochineal for dye-sensitized solar cells.

    Science.gov (United States)

    Park, Kyung-Hee; Kim, Tae-Young; Han, Shin; Ko, Hyun-Seok; Lee, Suk-Ho; Song, Yong-Min; Kim, Jung-Hun; Lee, Jae-Wook

    2014-07-15

    Two natural dyes extracted from gardenia yellow (Gardenia jasminoides) and cochineal (Dactylopius coccus) were used as sensitizers in the assembly of dye-sensitized solar cells (DSSCs) to harvest light over a wide range of wavelengths. The adsorption characteristics, electrochemical properties and photovoltaic efficiencies of the natural DSSCs were investigated. The adsorption kinetics data of the dyes were obtained in a small adsorption chamber and fitted with a pseudo-second-order model. The photovoltaic performance of a photo-electrode adsorbed with single-dye (gardenia or cochineal) or the mixture or successive adsorption of the two dyes, was evaluated from current-voltage measurements. The energy conversion efficiency of the TiO2 electrode with the successive adsorption of cochineal and gardenia dyes was 0.48%, which was enhanced compared to single-dye adsorption. Overall, a double layer of the two natural dyes as sensitizers was successfully formulated on the nanoporous TiO2 surface based on the differences in their adsorption affinities of gardenia and cochineal.

  18. Single wavelength light-mediated, synergistic bimodal cancer photoablation and amplified photothermal performance by graphene/gold nanostar/photosensitizer theranostics.

    Science.gov (United States)

    Wu, Chunhui; Li, Dan; Wang, Lianhui; Guan, Xiaotian; Tian, Yuan; Yang, Hong; Li, Shun; Liu, Yiyao

    2017-02-01

    Light-triggered nanotheranostics opens a fascinating but challenging avenue to achieve simultaneous and highly efficient anticancer outcomes for multimodal therapeutic and diagnostic modalities. Herein, a multifunctional phototheranostics based on a photosensitizer-assembled graphene/gold nanostar hybrid (GO/AuNS-PEG) was developed for cancer synergistic photodynamic (PDT) and photothermal therapy (PTT) as well as effective photothermal imaging. The stable and biocompatible GO/AuNS-PEG composite displayed a high photothermal conversion efficiency due to the enhanced optical absorbance of both graphene and gold nanostars in the near-infrared (NIR) range. By tuning the absorption wavelength of GO/AuNS-PEG to that of Chlorin e6 (Ce6), GO/AuNS-PEG/Ce6 completely eliminated the EMT6 xenograft tumors by the tremendous synergistic anticancer efficiency of simultaneous PDT and PTT under a single NIR laser irradiation (660nm) in vivo. The underlying mechanism may be the enhanced cytoplasmic uptake and accumulation of GO/AuNS-PEG/Ce6 and the subsequent photodestruction of the lysosomal membrane and mitochondria. Moreover, GO/AuNS-PEG/Ce6 exhibited negligible side-effects on the body and other organs. These results demonstrate that the graphene/gold nanostar nanoconstruct provides a versatile and reliable integrated platform for the photo-controlled cancer theragnostic applications.

  19. A WISE Measurement of the 2:4 mum Galaxy Luminosity Function and its Implications for the Extragalactic Background Light at 3:4 mum

    Science.gov (United States)

    Lake, Sean Earl

    2017-05-01

    The measurement of the the Extragalactic Background Light (EBL) has seen some controversy in recent works, with direct and indirect measures conflicting. Specifi- cally, upper limits based on analyzing the plausible opacity obscuring TeV spectra of blazars suggests that the density of radiation with wavelengths near 3.4 mum is onethirdtoonehalfasintenseasdirectmeasuresofthesame(forexample: Aharonian et al., 2006; Levenson et al., 2007; Matsumoto et al., 2005). The dominant contributor of the EBL at 3.4mum is expected to be ordinary starlight from relatively local, z EBL. While analyses of this sort have been done by others (Dominguez et al., 2011; Helgason et al., 2012), the full sky coverage of the AllWISE database has made it possible for us to improve the measurement of both the LF at 2.4 mum and the EBL using the large public spectroscopic redshift surveys. In order to do so, we had to develop a mathematical model for the measurement of a generalization of the LF, which is the density of galaxies per unit comoving volume per unit luminosity, to the Spectro-Luminosity Functional (SLF), which replaces the density per unit single luminosity, dL, with the density per luminosi- ii ties at all frequencies, DL nu. Our best combined analysis of the data yields present day Shechter Function LF parameters of: L⋆ = 6.4+/-[0.1 stat, 0.3sys]x1010 L2.4mum [solar mass](M⋆ = -21.67+/-[0.02 stat, 0.05sys] AB mag), φ⋆ = 5.8+/-[0.3stat, 0.3sys]x10 -3 Mpc-3, and alpha = -1.050 +/- [0.004stat, 0.03sys]; this implies a present day density of galaxies of 0.08 Mpc-3 brighter that 106 L2.4mum [solar mass] (10-3 Mpc-3 brighter than L⋆) and a luminosity density equivalent to 3.8 x 108 L2.4mum [solar mass] Mpc-3. The net EBL at 3.4mum that our synthesis model produces from galaxies closer than z = 5 is Inu = 9.0 +/- 0.5 kJy sr-1 (nuInu = 8.0 +/- 0.4 nW m-2 sr -1), largely in agreement with similar LF based estimates of the EBL.

  20. The Far Infrared and Submillimeter Diffuse Extragalactic Background

    CERN Document Server

    Hauser, M G

    2001-01-01

    The cosmic infrared background (CIB) radiation was a long-sought fossil of energetic processes associated with structure formation and chemical evolution since the Big Bang. The COBE Diffuse Infrared Background Experiment (DIRBE) and Far Infrared Absolute Spectrophotometer (FIRAS) were specifically designed to search for this background from 1.25 microns to millimeter wavelengths. These two instruments provided high quality, absolutely calibrated all-sky maps which have enabled the first detections of the CIB, initially at far infrared and submillimeter wavelengths, and more recently in the near infrared as well. The aim of this paper is to review the status of determinations of the CIB based upon COBE measurements. The results show that the energy in the CIB from far infrared to millimeter wavelengths is comparable to that in the integrated light of galaxies from UV to near infrared wavelengths: the universe had a luminous but dusty past. On the assumption that nucleosynthesis in stars is the energy source f...

  1. Interference comparator for laser diode wavelength and wavelength instability measurement

    Science.gov (United States)

    Dobosz, Marek; KoŻuchowski, Mariusz

    2016-04-01

    Method and construction of a setup, which allows measuring the wavelength and wavelength instability of the light emitted by a laser diode (or a laser light source with a limited time coherence in general), is presented. The system is based on Twyman-Green interferometer configuration. Proportions of phases of the tested and reference laser's interference fringe obtained for a set optical path difference are a measure of the unknown wavelength. Optical path difference in interferometer is stabilized. The interferometric comparison is performed in vacuum chamber. The techniques of accurate fringe phase measurements are proposed. The obtained relative standard uncertainty of wavelength evaluation in the tested setup is about 2.5 ṡ 10-8. Uncertainty of wavelength instability measurement is an order of magnitude better. Measurement range of the current setup is from 500 nm to 650 nm. The proposed technique allows high accuracy wavelength measurement of middle or low coherence sources of light. In case of the enlarged and complex frequency distribution of the laser, the evaluated wavelength can act as the length master in interferometer for displacement measurement.

  2. Background suppression in TeO{sub 2} bolometers with Neganov-Luke amplified cryogenic light detectors

    Energy Technology Data Exchange (ETDEWEB)

    Willers, Michael; Lanfranchi, Jean-Come; Oberauer, Lothar; Schoenert, Stefan [Technische Universitaet Muenchen, Physik Department E15, James Franck Strasse, 85748 Garching (Germany); Excellence Cluster Universe, Technische Universitaet Muenchen, Boltzmannstr. 2, 85748, Garching (Germany); Muenster, Andrea; Potzel, Walter; Roth, Sabine; Wawoczny, Stephan; Zoeller, Andreas [Technische Universitaet Muenchen, Physik Department E15, James Franck Strasse, 85748 Garching (Germany); Giuliani, Andrea [Centre de Sciences Nucleaires et de Sciences de la Matiere, 91405 Orsay Campus (France)

    2015-07-01

    The Neganov-Luke (NL) effect offers a promising way to increase the sensitivity of cryogenic light detectors at low energies. In this talk we show that a highly efficient discrimination between α and e{sup -}/γ induced events in TeO{sub 2} crystals (used in the search for the neutrinoless double beta decay) can be achieved by measuring the Cherenkov radiation emitted by high-energetic electrons within the crystal. By using NL amplified light detectors, a suppression of ∝99% of α-induced events with energies close to the Q-value of {sup 130}Te at ∝2.5 MeV has been achieved for the first time while simultaneously accepting 99.8% of all e{sup -}/γ-induced events.

  3. Disentangling the effects of nanoscale structural variations on the light emission wavelength of single nano-emitters: InGaN/GaN multiquantum well nano-LEDs for a case study.

    Science.gov (United States)

    Sarau, George; Heilmann, Martin; Latzel, Michael; Christiansen, Silke

    2014-10-21

    The scattering in the light emission wavelength of semiconductor nano-emitters assigned to nanoscale variations in strain, thickness, and composition is critical in current and novel nanotechnologies from highly efficient light sources to photovoltaics. Here, we present a correlated experimental and theoretical study of single nanorod light emitting diodes (nano-LEDs) based on InGaN/GaN multiquantum wells to separate the contributions of these intrinsic fluctuations. Cathodoluminescence measurements show that nano-LEDs with identical strain states probed by non-resonant micro-Raman spectroscopy can radiate light at different wavelengths. The deviations in the measured optical transitions agree very well with band profile calculations for quantum well thicknesses of 2.07-2.72 nm and In fractions of 17.5-19.5% tightly enclosing the growth values. The nanorod surface roughness controls the appearance of surface optical phonon modes with direct implications on the design of phonon assisted nano-LED devices. This work establishes a new, simple, and powerful methodology for fundamental understanding as well as quantitative analysis of the strain - light emission relationship and surface-related phenomena in the emerging field of nano-emitters.

  4. Role of light and heavy minerals on natural radioactivity level of high background radiation area, Kerala, India.

    Science.gov (United States)

    Ramasamy, V; Sundarrajan, M; Suresh, G; Paramasivam, K; Meenakshisundaram, V

    2014-02-01

    Natural radionuclides ((238)U, (232)Th and (40)K) concentrations and eight different radiological parameters have been analyzed for the beach sediments of Kerala with an aim of evaluating the radiation hazards. Activity concentrations ((238)U and (232)Th) and all the radiological parameters in most of the sites have higher values than recommended values. The Kerala beach sediments pose significant radiological threat to the people living in the area and tourists going to the beaches for recreation or to the sailors and fishermen involved in their activities in the study area. In order to know the light mineral characterization of the present sediments, mineralogical analysis has been carried out using Fourier transform infrared (FTIR) spectroscopic technique. The eight different minerals are identified and they are characterized. Among the various observed minerals, the minerals such as quartz, microcline feldspar, kaolinite and calcite are major minerals. The relative distribution of major minerals is determined by calculating extinction co-efficient and the values show that the amount of quartz is higher than calcite and much higher than microcline feldspar. Crystallinity index is calculated to know the crystalline nature of quartz present in the sediments. Heavy mineral separation analysis has been carried out to know the total heavy mineral (THM) percentage. This analysis revealed the presence of nine heavy minerals. The minerals such as monazite, zircon, magnetite and illmenite are predominant. Due to the rapid and extreme changes occur in highly dynamic environments of sandy beaches, quantities of major light and heavy minerals are widely varied from site to site. Granulometric analysis shows that the sand is major content. Multivariate statistical (Pearson correlation, cluster and factor) analysis has been carried out to know the effect of mineralogy on radionuclide concentrations. The present study concluded that heavy minerals induce the (238)U and (232)Th

  5. Wavelength sweepable laser source

    DEFF Research Database (Denmark)

    2014-01-01

    Wavelength sweepable laser source is disclosed, wherein the laser source is a semiconductor laser source adapted for generating laser light at a lasing wavelength. The laser source comprises a substrate, a first reflector, and a second reflector. The first and second reflector together defines...... and having a rest position, the second reflector and suspension together defining a microelectromechanical MEMS oscillator. The MEMS oscillator has a resonance frequency and is adapted for oscillating the second reflector on either side of the rest position.; The laser source further comprises electrical...... connections adapted for applying an electric field to the MEMS oscillator. Furthermore, a laser source system and a method of use of the laser source are disclosed....

  6. Sub-microsecond wavelength stabilization of tunable lasers with the internal wavelength locker

    Science.gov (United States)

    Kimura, Ryoga; Tatsumoto, Yudai; Sakuma, Kazuki; Onji, Hirokazu; Shimokozono, Makoto; Ishii, Hiroyuki; Kato, Kazutoshi

    2016-08-01

    We proposed a method of accelerating the wavelength stabilization after wavelength switching of the tunable distributed amplification-distributed feedback (TDA-DFB) laser using the internal wavelength locker to reduce the size and the cost of the wavelength control system. The configuration of the wavelength stabilization system based on this locker was as follows. At the wavelength locker, the light intensity after an optical filter is detected as a current by the photodiodes (PDs). Then, for estimating the wavelength, the current is processed by the current/voltage-converting circuit (IVC), logarithm amplifier (Log Amp) and field programmable gate array (FPGA). Finally, the laser current is tuned to the desired wavelength with reference to the estimated wavelength. With this control system the wavelength is stabilized within 800 ns after wavelength switching, which is even faster than that with the conventional control system.

  7. Photosystem II efficiency of the palisade and spongy mesophyll in Quercus coccifera using adaxial/abaxial illumination and excitation light sources with wavelengths varying in penetration into the leaf tissue.

    Science.gov (United States)

    Peguero-Pina, José Javier; Gil-Pelegrín, Eustaquio; Morales, Fermín

    2009-01-01

    The existence of major vertical gradients within the leaf is often overlooked in studies of photosynthesis. These gradients, which involve light heterogeneity, cell composition, and CO(2) concentration across the mesophyll, can generate differences in the maximum potential PSII efficiency (F (V)/F (M) or F (V)/F (P)) of the different cell layers. Evidence is presented for a step gradient of F (V)/F (P) ratios across the mesophyll, from the adaxial (palisade parenchyma, optimal efficiencies) to the abaxial (spongy parenchyma, sub-optimal efficiencies) side of Quercus coccifera leaves. For this purpose, light sources with different wavelengths that penetrate more or less deep within the leaf were employed, and measurements from the adaxial and abaxial sides were performed. To our knowledge, this is the first report where a low photosynthetic performance in the abaxial side of leaves is accompanied by impaired F (V)/F (P) ratios. This low photosynthetic efficiency of the abaxial side could be related to the occurrence of bundle sheath extensions, which facilitates the penetration of high light intensities deep within the mesophyll. Also, leaf morphology (twisted in shape) and orientation (with a marked angle from the horizontal plane) imply direct sunlight illumination of the abaxial side. The existence of cell layers within leaves with different photosynthetic efficiencies makes appropriate the evaluation of how light penetrates within the mesophyll when using Chl fluorescence or gas exchange techniques that use different wavelengths for excitation and/or for driving photosynthesis.

  8. Lighting

    Data.gov (United States)

    Federal Laboratory Consortium — Lighting Systems Test Facilities aid research that improves the energy efficiency of lighting systems. • Gonio-Photometer: Measures illuminance from each portion of...

  9. The effects of low-intensity narrow-band blue-light treatment compared to bright white-light treatment in sub-syndromal seasonal affective disorder

    OpenAIRE

    Meesters, Ybe; Winthorst, Wim H; Duijzer, Wianne B.; Hommes, Vanja

    2016-01-01

    Background The discovery of a novel photoreceptor in the retinal ganglion cells with a highest sensitivity of 470-490 nm blue light has led to research on the effects of short-wavelength light in humans. Several studies have explored the efficacy of monochromatic blue or blue-enriched light in the treatment of SAD. In this study, a comparison has been made between the effects of broad-wavelength light without ultraviolet (UV) wavelengths compared to narrow-band blue light in the treatment of ...

  10. The effects of low-intensity narrow-band blue-light treatment compared to bright white-light treatment in sub-syndromal seasonal affective disorder

    OpenAIRE

    Meesters, Ybe; Winthorst, Wim H; Duijzer, Wianne; Bos, Elisabeth; V, Hommes,

    2016-01-01

    Background The discovery of a novel photoreceptor in the retinal ganglion cells with a highest sensitivity of 470-490 nm blue light has led to research on the effects of short-wavelength light in humans. Several studies have explored the efficacy of monochromatic blue or blue-enriched light in the treatment of SAD. In this study, a comparison has been made between the effects of broad-wavelength light without ultraviolet (UV) wavelengths compared to narrow-band blue light in the treatment of ...

  11. On the effects of size factor on albedo versus wavelength for light scattered by small particles under Mie and Rayleigh regimes

    CERN Document Server

    Brown, Adrian J

    2013-01-01

    Scattering by particles significantly smaller than the wavelength is an important physical process in the rocky bodies in our solar system and beyond. A number of observations of spectral bluing (referred to in those papers as "Rayleigh scattering") on planetary surfaces have been recently reported, however, the necessary mathematical modeling of this phenomenon has not yet achieved maturity. This paper is a first step to this effect, by examining the effect of grain size and optical index on the albedo of small conservative and absorbing particles as a function of wavelength. The basic conditions necessary for spectral bluing or reddening to be observed in real-world situations are identified. We find that any sufficiently monomodal size distribution of scattering particles will cause spectral bluing in some part of the EM spectrum regardless of its optical index.

  12. Nano-Optics for Enhancing Light-Matter Interactions on a Molecular Scale Plasmonics, Photonic Materials and Sub-Wavelength Resolution

    CERN Document Server

    Collins, John

    2013-01-01

    This volume presents a considerable number of interrelated contributions dealing with the new scientific ability to shape and control matter and electromagnetic fields on a sub-wavelength scale. The topics range from the fundamental ones, such as photonic metamateriials, plasmonics and sub-wavelength resolution to the more applicative, such as detection of single molecules, tomography on a micro-chip, fluorescence spectroscopy of biological systems, coherent control of biomolecules, biosensing of single proteins, terahertz spectroscopy of nanoparticles, rare earth ion-doped nanoparticles, random lasing, and nanocoax array architecture. The various subjects bridge over the disciplines of physics, biology and chemistry, making this volume of interest to people working in these fields. The emphasis is on the principles behind each technique and on examining the full potential of each technique. The contributions that appear in this volume were presented at a NATO Advanced Study Institute that was held in Erice, ...

  13. Effect of light wavelengths on lipid accumulation of Chlorella vulgaris in photoautotrophic culture%不同光质对小球藻光自养培养积累油脂的影响

    Institute of Scientific and Technical Information of China (English)

    尹继龙; 唐小红; 郑洪立; 尹丰伟; 高振; 黄和

    2014-01-01

    研究了5种光质对小球藻( Chlorella vulgaris) M209256生长和产油的影响。结果表明:蓝光为小球藻的最适生长和产油光质;与其他光质相比,蓝光培养的小球藻生物量和油脂含量均较高,为2�40×107个/mL和28%;红光培养的小球藻生长最慢且油脂含量最低,为1�32×107个/mL和15�13%,表现出明显的“红降”现象。在GC MS分析的基础上,对油脂甲酯化后的十六烷值进行评估,结果发现:蓝光的十六烷值最高;5种光质培养的小球藻所产油脂,甲酯十六烷值均在47以上。因此,小球藻油脂所制备的生物柴油具有较好的燃烧性能。%The effect of five kinds of light wavelengths on the growth and lipid production of Chlorella vulgaris M209256 was studied. The results showed that the optimal wavelength for growth and lipid production of Chlorella vulgaris was blue light. Compared with other light wavelengths,the higher biomass and lipid content of Chlorella vulgaris,2�40 × 107 mL-1 and 28%,respectively,were obtained under blue light�Both the biomass and lipid content,1�32 × 107 mL-1 and 15�13%,respectively,were the lowest when Chlorella vulgaris was exposed to red light�It was a phenomenon of "red drop"�Cetane number ( CN) was estimated in this work based on GC-MS analysis. It was found that Chlorella vulgaris under blue light had the highest CN and all CNs of fatty acid methyl esters ( FAMEs) from Chlorella vulgaris under the tested light wavelengths were above 47�

  14. Effects of a chronic reduction of short-wavelength light input on melatonin and sleep patterns in humans : Evidence for adaptation

    NARCIS (Netherlands)

    Gimenez, Marina C.; Beersma, Domien G. M.; Bollen, Pauline; van der Linden, Matthijs L.; Gordijn, Marijke C. M.

    2014-01-01

    Light is an important environmental stimulus for the entrainment of the circadian clock and for increasing alertness. The intrinsically photosensitive ganglion cells in the retina play an important role in transferring this light information to the circadian system and they are elicited in

  15. Effects of a chronic reduction of short-wavelength light input on melatonin and sleep patterns in humans : Evidence for adaptation

    NARCIS (Netherlands)

    Gimenez, Marina C.; Beersma, Domien G. M.; Bollen, Pauline; van der Linden, Matthijs L.; Gordijn, Marijke C. M.

    2014-01-01

    Light is an important environmental stimulus for the entrainment of the circadian clock and for increasing alertness. The intrinsically photosensitive ganglion cells in the retina play an important role in transferring this light information to the circadian system and they are elicited in particula

  16. Light

    DEFF Research Database (Denmark)

    Prescott, N.B.; Kristensen, Helle Halkjær; Wathes, C.M.

    2004-01-01

    This chapter presents the effect of artificial light environments (light levels, colour, photoperiod and flicker) on the welfare of broilers in terms of vision, behaviour, lameness and mortality......This chapter presents the effect of artificial light environments (light levels, colour, photoperiod and flicker) on the welfare of broilers in terms of vision, behaviour, lameness and mortality...

  17. Cumulative-Phase-Alteration of Galactic-Light Passing Through the Cosmic-Microwave-Background: A New Mechanism for Some Observed Spectral-Shifts

    Directory of Open Access Journals (Sweden)

    Tank H. K.

    2012-07-01

    Full Text Available Currently, whole of the measured “cosmological-red-shift ” is interpreted as due to the “metric-expansion-of-space”; so for the required “closer -density” of the universe, we need twenty times more mass-energy than the visible baryonic-matter contained in the universe. This paper proposes a new mechanism, which can account for good per- centage of the red-shift in the extra-galactic-light, greatly reducing the requirement of dark matter-energy. Also, this mechanism can cause a new kin d of blue-shift reported here, and their observational evidences. These spectral-s hifts are proposed to result due to cumulative phase-alteration of extra-galactic-light b ecause of vector-addition of: (i electric-field of extra-galactic-light and (ii that of the cosmic-microwave-background (CMB. Since the center-frequency of CMB is much lower than extra-galactic-light, the cumulative-phase-alteration results in red -shift, observed as an additional contribu- tor to the measured “cosmological red-shift”; and since the center-frequency of CMB is higher than the radio-frequency-signals used to measure velocity of space-probes like: Pioneer-10, Pioneer-11, Galileo and Ulysses, the cum ulative-phase-alteration re- sulted in blue-shift, leading to the interpretation of deceleration of these space-probes. While the galactic-light experiences the red-shift, and th e ranging-signals of the space- probes experience blue -shift, they are comparable in magnitude, providing a supportive- evidence for the new mechanism proposed here. More confirmative-experiments for this new mechanism are also proposed.

  18. Wavelength-domain RF photonic signal processing

    Science.gov (United States)

    Gao, Lu

    This thesis presents a novel approach to RF-photonic signal processing applications based on wavelength-domain optical signal processing techniques using broadband light sources as the information carriers, such as femtosecond lasers and white light sources. The wavelength dimension of the broadband light sources adds an additional degree of freedom to conventional optical signal processing systems. Two novel wavelength-domain optical signal processing systems are presented and demonstrated in this thesis. The first wavelength-domain RF photonic signal processing system is a wavelength-compensated squint-free photonic multiple beam-forming system for wideband RF phased-array antennas. Such a photonic beam-forming system employs a new modulation scheme developed in this thesis, which uses traveling-wave tunable filters to modulate wideband RF signals onto broadband optical light sources in a frequency-mapped manner. The wavelength dimension of the broadband light sources provides an additional dimension in the wavelength-compensated Fourier beam-forming system for mapping the received RF frequencies to the linearly proportional optical frequencies, enabling true-time-delay beam forming, as well as other novel RF-photonic signal processing functions such as tunable filtering and frequency down conversion. A new slow-light mechanism, the SLUGGISH light, has also been discovered with an effective slow-light velocity of 86 m/s and a record time-bandwidth product of 20. Experimental demonstration of true-time-delay beam forming based on the SLUGGISH light effect has also been presented in this thesis. In the second wavelength-domain RF photonic signal processing system, the wavelength dimension increases the information carrying capacity by spectrally multiplexing multiple wavelength channels in a wavelength-division-multiplexing fiber-optic communication system. A novel ultrafast all-optical 3R (Re-amplification, Retiming, Re-shaping) wavelength converter based on

  19. Extra-galactic background light measurements from the far-UV to the far-IR from deep ground and space-based galaxy counts

    CERN Document Server

    Driver, Simon P; Davies, Luke J; Robotham, Aaron S G; Wright, Angus H; Windhorst, Rogier A; Cohen, Seth; Emig, Kim; Jansen, Rolf A; Dunne, Loretta

    2016-01-01

    We combine wide and deep galaxy number-count data from GAMA, COSMOS/G10, HST ERS, HST UVUDF and various near-, mid- and far- IR datasets from ESO, Spitzer and Herschel. The combined data range from the far-UV (0.15microns) to far-IR (500microns), and in all cases the contribution to the integrated galaxy light (IGL) of successively fainter galaxies converges. Using a simple spline fit, we derive the IGL and the extrapolated-IGL in all bands. We argue undetected low surface brightness galaxies and intra-cluster/group light is modest, and that our extrapolated-IGL measurements are an accurate representation of the extra-galactic background light. Our data agree with most earlier IGL estimates and with direct measurements in the far-IR, but disagree strongly with direct estimates in the optical. Close agreement between our results and recent very high-energy experiments (H.E.S.S. and MAGIC), suggest that there may be an additional foreground affecting the direct estimates. The most likely culprit could be the ad...

  20. Recent Developments of Versatile Photoinitiating Systems for Cationic Ring Opening Polymerization Operating at Any Wavelengths and under Low Light Intensity Sources.

    Science.gov (United States)

    Lalevée, Jacques; Mokbel, Haifaa; Fouassier, Jean-Pierre

    2015-04-20

    Photoinitiators (PI) or photoinitiating systems (PIS) usable in light induced cationic polymerization (CP) and free radical promoted cationic polymerization (FRPCP) reactions (more specifically for cationic ring opening polymerization (ROP)) together with the involved mechanisms are briefly reviewed. The recent developments of novel two- and three-component PISs for CP and FRPCP upon exposure to low intensity blue to red lights is emphasized in details. Examples of such reactions under various experimental conditions are provided.

  1. Wavelength converter technology

    DEFF Research Database (Denmark)

    Kloch, Allan; Hansen, Peter Bukhave; Poulsen, Henrik Nørskov;

    1999-01-01

    Wavelength conversion is important since it ensures full flexibility of the WDM network layer. Progress in optical wavelength converter technology is reviewed with emphasis on all-optical wavelength converter types based on semiconductor optical amplifiers....

  2. Wavelength converter technology

    DEFF Research Database (Denmark)

    Kloch, Allan; Hansen, Peter Bukhave; Poulsen, Henrik Nørskov;

    1999-01-01

    Wavelength conversion is important since it ensures full flexibility of the WDM network layer. Progress in optical wavelength converter technology is reviewed with emphasis on air-optical wavelength converter types based on semiconductor optical amplifiers....

  3. Fine frequency tuning in sum-frequency generation of continuous-wave single-frequency coherent light at 252 nm with dual-wavelength enhancement.

    Science.gov (United States)

    Kumagai, Hiroshi

    2007-01-01

    Fine frequency tuning of the deep-ultraviolet single-mode coherent light at 252 nm was conducted through the PID feedback system automatically by changing the temperature of a beta-BaB(2)O(4) (BBO) crystal in a doubly resonant external cavity for the sum-frequency mixing of 373 and 780 nm light. The temperature-dependent frequency tuning rate is 19.3 MHzK(-1), which is sufficiently fine to realize the laser cooling of neutral silicon atoms because the natural width of the laser cooling transition is 28.8 MHz.

  4. Observations of 1ES 1101-232 with H.E.S.S. and at lower frequencies: A hard spectrum blazar and constraints on the extragalactic background light

    Science.gov (United States)

    Pühlhofer, Gerd; Benbow, Wystan; Costamante, Luigi; Sol, Helene; Boisson, Catherine; Emmanoulopoulos, Dimitrios; Wagner, Stefan; Horns, Dieter; Giebels, Berrie

    VHE observations of the distant (z=0.186) blazar 1ES 1101-232 with H.E.S.S. are used to constrain the extragalactic background light (EBL) in the optical to near infrared band. As the EBL traces the galaxy formation history of the universe, galaxy evolution models can therefore be tested with the data. In order to measure the EBL absorption effect on a blazar spectrum, we assume that usual constraints on the hardness of the intrinsic blazar spectrum are not violated. We present an update of the VHE spectrum obtained with H.E.S.S. and the multifrequency data that were taken simultaneously with the H.E.S.S. measurements. The data verify that the broadband characteristics of 1ES 1101-232 are similar to those of other, more nearby blazars, and strengthen the assumptions that were used to derive the EBL upper limit.

  5. A tunable wavelength-conversion laser

    Science.gov (United States)

    Kondo, Kentaro; Kuno, Masaaki; Yamakoshi, Shigenobu; Wakao, Kiyohide

    1992-05-01

    A novel wavelength-conversion laser was fabricated using monolithic integration of a bistable laser diode and a wavelength-tunable distributed Bragg reflector (DBR) laser. This device converts an input light signal with a certain wavelength to output light with a tunable wavelength over 3.5 nm. Input power required for switching is investigated, and its resonant dependence on input wavelength is revealed. Input polarization is also discussed, and suppression of crosstalk is demonstrated. This device's turn-off switching response is greatly influenced by the light power of the input signal as well as bias current, and the first 1 Gb/s operation is achieved in optimum conditions for fast turn-off and stable turn-on.

  6. ALMA Census of Faint 1.2 mm Sources Down to ~0.01 mJy: Extragalactic Background Light and Dust-Poor High-z Galaxies

    CERN Document Server

    Fujimoto, Seiji; Ono, Yoshiaki; Shibuya, Takatoshi; Ishigaki, Masafumi; Momose, Rieko

    2015-01-01

    We present statistics of 89 faint 1.2-mm continuum sources with a flux density of ~0.01-1 mJy detected by about 100 deep ALMA pointing data that include the complete deep datasets archived by 2015 March. These faint sources are identified in 50 blank fields and behind one cluster, Abell 1689, that magnifies the background sources by gravitational lensing. Evaluating various important effects including the false detection, detection completeness, and flux boosting as well as the lensing magnification by modeling and simulations, we derive number counts of 1.2 mm continuum sources. We find that the number counts are well represented by the Schechter function down to ~0.01 mJy, and that the total integrated 1.2 mm flux of the securely identified sources is 22.8^(+6.1)_(-6.4) Jy deg^(-2) that corresponds to 104^(+27)_(-30)% of the extragalactic background light (EBL) measured by COBE observations. These results suggest that the major 1.2 mm EBL contributors are sources with >~0.01 mJy, and that very faint 1.2 mm ...

  7. Integration of Background Large Screen and Lighting in Qingdao TV HD Studio%青岛电视台高清演播室背景大屏幕与灯光的融合

    Institute of Scientific and Technical Information of China (English)

    段孝讯; 殷茂森; 郭嘉

    2015-01-01

    介绍青岛电视台高清演播室背景大屏幕及灯光系统组成,分析如何实现背景大屏幕与灯光之间的融合。%This paper introduces the background large screen and the composition of lighting systems in Qingdao TV HD studio, and analysis how to achieve the integration between background large screen and lighting.

  8. Carrier dynamics in nitride-based light-emitting p-n junction diodes with two active regions emitting at different wavelengths

    Science.gov (United States)

    Li, Y.-L.; Gessmann, Th.; Schubert, E. F.; Sheu, J. K.

    2003-08-01

    The carrier transport and recombination dynamics of monolithic InGaN/GaN light-emitting p-n junction structures with two active regions are investigated. Room-temperature and low-temperature photoluminescence and room-temperature electroluminescence measurements show two emission bands originating from the two active regions. In electroluminescence, the intensity ratio of the two emission bands is independent of injection current. In contrast, the intensity ratio depends strongly on the excitation intensity in photoluminescence measurements. The dependency of the emission on excitation is discussed and attributed to carrier transport between the two active regions and to the different carrier injection dynamics in photoluminescence and electroluminescence. The luminous efficacy of a Gaussian dichromatic white-light source is calculated assuming a line broadening ranging from 2kT to 10kT. Luminous efficacies ranging from 380 to 440 lm/W are obtained for broadened dichromatic sources.

  9. 固定波长UV-VIS光对大豆油品质的影响%Effect of Fixed Wavelength UV-VIS Light on Quality of Soybean Oil

    Institute of Scientific and Technical Information of China (English)

    于殿宇; 刘鑫; 王玥; 邹小雨; 奚会松; 江连洲

    2013-01-01

    通过设定不同温度、光强度、光波长、时间对大豆油进行脱色试验,对大豆油的过氧化值、酸价及色泽进行了测定,研究分析了大豆油过氧化值、酸价及色泽随温度、光强度、光波长及照射时间变化的基本规律.通过单因素及正交试验,VIS-450光照脱色的最优工艺条件:光通量2400 lm,温度35℃,时间3h,脱色率为53.2%.UV-365光照脱色的最优工艺条件:光通量2 400 lm,温度35℃,时间2h,脱色率为42.4%.结果表明:UV-365比VIS-450对大豆油品质劣变影响较大;VIS-450比UV-365对大豆油脱色率影响较大.%By setting the different temperature,light intensity,light wavelength,time on decolorization of soybean oil,determine peroxide value,acid value and color of soybean,research and analysis of soybean oil peroxide value,acid value and color variation with relationship of temperature,light intensity,light wavelength and exposure time.Through single factor and orthogonal test,the optimum conditions of the VIS-450 light decolorization is:The luminous flux 2 400 lm,temperature of 35 ℃,time of 3 h,The decolorization rate 53.2%.The optimum conditions of the VIS-365 light decolorization is:The luminous flux 2 400 lm,temperature of 35 ℃,time of 2 h,the decolorization rate 42.4%.The results showed that:UV-365 more influential than VIS-450 t on the quality of soybean oil deterioration,VIS-450 more influential than UV-365 on soybean oil decolorization rate influence.

  10. The effects of low-intensity narrow-band blue-light treatment compared to bright white-light treatment in sub-syndromal seasonal affective disorder

    NARCIS (Netherlands)

    Meesters, Ybe; Winthorst, Wim H.; Duijzer, Wianne; Bos, Elisabeth; V, Hommes,

    2016-01-01

    Background The discovery of a novel photoreceptor in the retinal ganglion cells with a highest sensitivity of 470-490 nm blue light has led to research on the effects of short-wavelength light in humans. Several studies have explored the efficacy of monochromatic blue or blue-enriched light in the

  11. Passively synchronized dual-wavelength Q-switched lasers

    DEFF Research Database (Denmark)

    Janousek, Jiri; Tidemand-Lichtenberg, Peter; Mortensen, Jesper Liltorp

    We present a simple and efficient way of generating synchronized Q-switched pulses at wavelengths hundreds of nanometers apart. This principle can result in new pulsed all-solid-state light sources at new wavelengths based on SFG....

  12. Light

    CERN Document Server

    Robertson, William C

    2003-01-01

    Why is left right and right left in the mirror? Baffled by the basics of reflection and refraction? Wondering just how the eye works? If you have trouble teaching concepts about light that you don t fully grasp yourself, get help from a book that s both scientifically accurate and entertaining with Light. By combining clear explanations, clever drawings, and activities that use easy-to-find materials, this book covers what science teachers and parents need to know to teach about light with confidence. It uses ray, wave, and particle models of light to explain the basics of reflection and refraction, optical instruments, polarization of light, and interference and diffraction. There s also an entire chapter on how the eye works. Each chapter ends with a Summary and Applications section that reinforces concepts with everyday examples. Whether you need a deeper understanding of how light bends or a good explanation of why the sky is blue, you ll find Light more illuminating and accessible than a college textbook...

  13. Light-emitting Diodes

    Science.gov (United States)

    Opel, Daniel R.; Hagstrom, Erika; Pace, Aaron K.; Sisto, Krisanne; Hirano-Ali, Stefanie A.; Desai, Shraddha

    2015-01-01

    Background: In the early 1990s, the biological significance of light-emitting diodes was realized. Since this discovery, various light sources have been investigated for their cutaneous effects. Study design: A Medline search was performed on light-emitting diode lights and their therapeutic effects between 1996 and 2010. Additionally, an open-label, investigator-blinded study was performed using a yellow light-emitting diode device to treat acne, rosacea, photoaging, alopecia areata, and androgenetic alopecia. Results: The authors identified several case-based reports, small case series, and a few randomized controlled trials evaluating the use of four different wavelengths of light-emitting diodes. These devices were classified as red, blue, yellow, or infrared, and covered a wide range of clinical applications. The 21 patients the authors treated had mixed results regarding patient satisfaction and pre- and post-treatment evaluation of improvement in clinical appearance. Conclusion: Review of the literature revealed that differing wavelengths of light-emitting diode devices have many beneficial effects, including wound healing, acne treatment, sunburn prevention, phototherapy for facial rhytides, and skin rejuvenation. The authors’ clinical experience with a specific yellow light-emitting diode device was mixed, depending on the condition being treated, and was likely influenced by the device parameters. PMID:26155326

  14. Multi-wavelength Light Curve Model of the One-year Recurrence Period Nova M31N 2008-12a

    CERN Document Server

    Kato, Mariko; Hachisu, Izumi

    2015-01-01

    We present a theoretical light curve model of the recurrent nova M31N 2008-12a, the current record holder for the shortest recurrence period (1 yr). We combined interior structures calculated using a Henyey-type evolution code with optically thick wind solutions of hydrogen-rich envelopes, which give the proper mass-loss rates, photospheric temperatures, and luminosities. The light curve model is calculated for a 1.38 M_sun white dwarf (WD) with an accretion rate of 1.6 \\times 10^{-7} M_sun yr^{-1}. This model shows a very high effective temperature (log T_ph (K) \\geq 4.97) and a very small wind mass-loss rate (\\dot M_wind \\leq 9.3 \\times 10^{-6} M_sun yr^{-1}) even at the maximum expansion of the photosphere. These properties are consistent with the faint optical peak of M31N 2008-12a because the brightness of the free-free emission is proportional to the square of the mass-loss rate. The model well reproduces the short supersoft X-ray turn-on time of 6 days and turnoff time of 18 days after the outburst. Th...

  15. A Multi-wavelength study of 1WGA J1346.5-6255: a new $\\gamma$ Cas analog unrelated to the background supernova remnant G309.2-00.6

    CERN Document Server

    Safi-Harb, S; Butt, Y; Matheson, H; Negueruela, I; Lu, F; Chen, S J Y

    2006-01-01

    1WGA J1346.5-6255 is a ROSAT X-ray source found within the radio lobes of the supernova remnant (SNR) G309.2-00.6. This source also appears to coincide with the bright and early-type star HD 119682, which is in the middle of the galactic open cluster NGC 5281. The radio morphology of the remnant, consisting of two brightened and distorted arcs of emission on opposite sides of the 1WGA J1346.5-6255 source and of a jet-like feature and break in the shell, led to the suggestion that 1WGA J1346.5-6255/G309.2-00.6 is a young analog of the microquasar SS 433 powering the W50 nebula. This motivated us to study this source at X-ray and optical wavelengths. We here present new Chandra observations of 1WGA J1346.5-6255, archival XMM-Newton observations of G309.2-00.6, and optical spectroscopic observations of HD 119682, in order to search for X-ray jets from 1WGA J1346.5-6255, study its association with the SNR, and test for whether HD 119682 represents its optical counterpart. We do not find evidence for jets from 1WG...

  16. Extragalactic background light: a measurement at 400 nm using dark cloud shadow*†- I. Low surface brightness spectrophotometry in the area of Lynds 1642

    Science.gov (United States)

    Mattila, K.; Lehtinen, K.; Väisänen, P.; von Appen-Schnur, G.; Leinert, Ch.

    2017-09-01

    We present the method and observations for the measurement of the Extragalactic Background Light (EBL) utilizing the shadowing effect of a dark cloud. We measure the surface brightness difference between the opaque cloud core and its unobscured surroundings. In the difference the large atmospheric and Zodiacal light components are eliminated and the only remaining foreground component is the scattered starlight from the cloud itself. Although much smaller, its separation is the key problem in the method. For its separation we use spectroscopy. While the scattered starlight has the characteristic Fraunhofer lines and 400 nm discontinuity, the EBL spectrum is smooth and without these features. Medium resolution spectrophotometry at λ = 380-580 nm was performed with VLT/FORS at ESO of the surface brightness in and around the high-galactic-latitude dark cloud Lynds 1642. Besides the spectrum for the core with AV ≳ 15 mag, further spectra were obtained for intermediate-opacity cloud positions. They are used as proxy for the spectrum of the impinging starlight spectrum and to facilitate the separation of the scattered starlight (cf. Paper II; Mattila et al.). Our spectra reach a precision of ≲ 0.5 × 10-9 erg cm-2 s-1 sr-1 Å-1 as required to measure an EBL intensity in range of ∼1 to a few times 10-9 erg cm-2 s-1 sr-1 Å-1. Because all surface brightness components are measured using the same equipment, the method does not require unusually high absolute calibration accuracy, a condition that has been a problem for some previous EBL projects.

  17. The convergence fluctuation of light by clusters of galaxies - a cosmological test using the second acoustic peak of the microwave background

    CERN Document Server

    Lieu, R

    2004-01-01

    The weak lensing magnification of distant light by clusters of galaxies, assumed to be virialized systems with an NFW density profile, was calculated analytically as a statistical average over a random non-evolving distribution within $z=1$. The effect is exactly cancelled by the Dyer-Roeder beam in between clusters - this conclusion is valid also for an ensemble of spherical clumps of arbitrary density profile. An analytical expression for the variance in the mean magnification is provided, using the general formula from our previous work. The all sky fluctuation in the angular size of the microwave background second acoustic peak, due to the random placement of cluster lenses in the intervening space, is then derived to be $\\approx$ 33 %. Moreover, this standard deviation corresponds to that of a highly skewed magnification distribution, with a long tail extending towards the side of positive magnification, since any negative excursion from the mean cannot cross the hard limit imposed by the Dyer-Roeder emp...

  18. The extragalactic background light, the Hubble constant, and anomalies: conclusions from 20 years of TeV gamma-ray observations

    CERN Document Server

    Biteau, Jonathan

    2015-01-01

    Ground-based observatories have been collecting 0.2-20 TeV gamma rays from blazars for about twenty years. These gamma rays can experience absorption along the line of sight due to interactions with the extragalactic background light (EBL). In this paper, we investigate the most extensive set of TeV spectra from blazars collected so far, twice as large as any other studied. We first show that the gamma-ray optical depth can be reduced to the convolution product of an EBL kernel with the EBL intensity. We extract the EBL intensity from the gamma-ray spectra, show that it is preferred at 11 sigma to a null intensity, and unveil the broad-band spectrum of the EBL from mid-UV to far IR. Our measurement shows that the total radiative content of the universe between 0.1 and 1000 microns represents 6.5+/-1.2% of the brightness of the CMB. This is slightly above the accumulated emission of stars and galaxies and constrains the unresolved sources that could have reionized the universe. We also propose a data-driven me...

  19. Design of athermal phonon light detector for reducing alpha recoil background of next-gen CUORE 0 νββ experiment

    Science.gov (United States)

    Camilleri, Joseph; Pyle, Matt; Kolomensky, Yury; Cuore Collaboration; Cdms Collaboration

    2017-01-01

    The current generation of bolometric 0 νββ experiments, including CUORE, expect degraded alpha recoils to be the dominant background restricting experimental sensitivity. The CUPID project will aim to improve the sensitivity of CUORE by over an order of magnitude, and search for 0 νββ in the entire region of parameter space consistent with the inverted neutrino mass hierarchy. Surface contamination of Cu support structures for CUORE's 130Te crystal bolometers is primarily responsible for these unwanted alpha recoils. Electronic signals produced near Qββ (2.53 MeV) have been shown to produce Cherenkov radiation on the order of 100 eV in 130Te crystals. The heavier and slower alpha particles of comparable energy in the region of interest do not produce a Cherenkov signal, allowing for discrimination via a high-resolution cryogenic light detector. A photon detector with energy resolution <10 eV is necessary. We will discuss how athermal phonon collection calorimeter technology developed by the CDMS collaboration over the past decade can be scaled to produce such a sensitive detector, while also satisfying requirements for scintillating crystal alternatives. We will also present the current status of the detector development. NSF: NSF PHY-1314881.

  20. Structure-activity relationship study of anticancer thymidine-quinoxaline conjugates under the low radiance of long wavelength ultraviolet light for photodynamic therapy.

    Science.gov (United States)

    Zhang, Dejun; Liu, Huaming; Wei, Qiong; Zhou, Qibing

    2016-01-01

    Thymidine quinoxaline conjugate (dT-QX) is a thymidine analog with selective cytotoxicity against different cancer cells. In this study, the structure activity relationship study of dT-QX analogs was carried out under the low radiance of black fluorescent (UVA-1) light. Significantly enhanced cytotoxicity was observed under UVA-1 activation among analogs containing both thymidine and quinoxaline moieties with different length of the linker, stereochemical configuration and halogenated substituents. Among these analogs, the thymidine dichloroquinoxaline conjugate exhibited potent activity under UVA-1 activation as the best candidate with EC50 at 0.67 μM and 1.3 μM against liver and pancreatic cancer cells, respectively. In contrast, the replacement of thymidine moiety with a galactosyl residue or the replacement of quinoxaline moiety with a fluorescent pyrenyl residue or a simplified diketone structure resulted in the full loss of activity. Furthermore, it was revealed that the low radiance of UVA-1 at 3 mW/cm(2) for 20 min was sufficient enough to induce the full cytotoxicity of thymidine dichloroquinoxaline conjugate and that the cytotoxic mechanism was achieved through a rapid and steady production of reactive oxygen species.

  1. Device for wavelength-selective imaging

    Science.gov (United States)

    Frangioni, John V.

    2010-09-14

    An imaging device captures both a visible light image and a diagnostic image, the diagnostic image corresponding to emissions from an imaging medium within the object. The visible light image (which may be color or grayscale) and the diagnostic image may be superimposed to display regions of diagnostic significance within a visible light image. A number of imaging media may be used according to an intended application for the imaging device, and an imaging medium may have wavelengths above, below, or within the visible light spectrum. The devices described herein may be advantageously packaged within a single integrated device or other solid state device, and/or employed in an integrated, single-camera medical imaging system, as well as many non-medical imaging systems that would benefit from simultaneous capture of visible-light wavelength images along with images at other wavelengths.

  2. Light

    CERN Document Server

    Ditchburn, R W

    2011-01-01

    This classic study, available for the first time in paperback, clearly demonstrates how quantum theory is a natural development of wave theory, and how these two theories, once thought to be irreconcilable, together comprise a single valid theory of light. Aimed at students with an intermediate-level knowledge of physics, the book first offers a historical introduction to the subject, then covers topics such as wave theory, interference, diffraction, Huygens' Principle, Fermat's Principle, and the accuracy of optical measurements. Additional topics include the velocity of light, relativistic o

  3. Photodynamic therapy using systemic administration of 5-aminolevulinic acid and a 410-nm wavelength light-emitting diode for methicillin-resistant Staphylococcus aureus-infected ulcers in mice.

    Science.gov (United States)

    Morimoto, Kuniyuki; Ozawa, Toshiyuki; Awazu, Kunio; Ito, Nobuhisa; Honda, Norihiro; Matsumoto, Sohkichi; Tsuruta, Daisuke

    2014-01-01

    Bacterial resistance to antibiotics has become a worldwide problem. One potential alternative for bacterial control is photodynamic therapy. 5-aminolevulinic acid is a natural precursor of the photosensitizer protoporphyrin IX. Relatively little is known about the antibacterial efficacy of photodynamic therapy using the systemic administration of 5-aminolevulinic acid; a few reports have shown that 5-aminolevulinic acid exerts photodynamic effects on methicillin-resistant Staphylococcus aureus (MRSA) in vitro. In this study, we evaluated the effectiveness of photodynamic therapy using 5-aminolevulinic acid and a 410-nm wavelength light-emitting diode in vitro and in vivo for the treatment of MRSA. We found that 5-aminolevulinic acid photodynamic therapy with the light-emitting diode had an in-vitro bactericidal effect on MRSA. In vivo, protoporphyrin IX successfully accumulated in MRSA on ulcer surfaces after intraperitoneal administration of 5-aminolevulinic acid to mice. Furthermore, 5-aminolevulinic acid photodynamic therapy accelerated wound healing and decreased bacterial counts on ulcer surfaces; in contrast, vancomycin treatment did not accelerate wound healing. Our findings indicate that 5-aminolevulinic acid photodynamic therapy may be a new treatment option for MRSA-infected wounds.

  4. Extragalactic background light from hierarchical galaxy formation. Gamma-ray attenuation up to the epoch of cosmic reionization and the first stars

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Yoshiyuki [Stanford Univ., CA (United States). Kavli Inst. for Particle Astrophysics and Cosmology; Inoue, Susumu [Max Planck Inst. for Nuclear Physics, Heidelberg (Germany); Univ. of Tokyo (Japan). Inst. for Cosmic Ray Research; Kobayashi, Masakazu A. R. [Ehime Univ., Matsuyama (Japan). Research Center for Space and Cosmic Evolution; Makiya, Ryu [Kyoto Univ. (Japan). Dept. of Astronomy; Niino, Yuu [National Astronomical Observatory of Japan, Mitaka (Tokyo). Optical and Infrared Astronomy Division; Totani, Tomonori [Kyoto Univ. (Japan). Dept. of Astronomy

    2013-04-26

    Here, we present a new model of the extragalactic background light (EBL) and corresponding γγ opacity for intergalactic gamma-ray absorption from z = 0 up to z = 10, based on a semi-analytical model of hierarchical galaxy formation that reproduces key observed properties of galaxies at various redshifts. Including the potential contribution from Population III stars and following the cosmic reionization history in a simplified way, the model is also broadly consistent with available data concerning reionization, particularly the Thomson scattering optical depth constraints from Wilkinson Microwave Anisotropy Probe (WMAP). In comparison with previous EBL studies up to z ~ 3-5, our predicted γγ opacity is in general agreement for observed gamma-ray energy below 400/(1 + z) GeV, whereas it is a factor of ~2 lower above this energy because of a correspondingly lower cosmic star formation rate, even though the observed ultraviolet (UV) luminosity is well reproduced by virtue of our improved treatment of dust obscuration and direct estimation of star formation rate. Moreover, the horizon energy at which the gamma-ray opacity is unity does not evolve strongly beyond z ~ 4 and approaches ~20 GeV. The contribution of Population III stars is a minor fraction of the EBL at z = 0, and is also difficult to distinguish through gamma-ray absorption in high-z objects, even at the highest levels allowed by the WMAP constraints. Nevertheless, the attenuation due to Population II stars should be observable in high-z gamma-ray sources by telescopes such as Fermi or the Cherenkov Telescope Array and provide a valuable probe of the evolving EBL in the rest-frame UV. Our detailed results of our model are publicly available in numerical form at http://www.slac.stanford.edu/~yinoue/Download.html.

  5. The cosmic far-infrared background buildup since redshift 2 at 70 and 160 microns in the COSMOS and GOODS fields

    NARCIS (Netherlands)

    Jauzac, M.; Dole, H.; Le Floc'h, E.; Aussel, H.; Caputi, K.; Ilbert, O.; Salvato, M.; Bavouzet, N.; Beelen, A.; Bethermin, M.; Kneib, J. -P.; Lagache, G.; Puget, J. -L.

    2011-01-01

    Context. The cosmic far-infrared background (CIB) at wavelengths around 160 mu m corresponds to the peak intensity of the whole extragalactic background light, which is being measured with increasing accuracy. However, the build up of the CIB emission as a function of redshift is still not well know

  6. Pupillary behavior in relation to wavelength and age

    OpenAIRE

    Lobato-Rincón, Luis-Lucio; Cabanillas-Campos, Maria del Carmen; Bonnin-Arias, Cristina; Chamorro-Gutiérrez, Eva; Murciano-Cespedosa, Antonio; Sánchez-Ramos Roda, Celia

    2014-01-01

    Pupil light reflex can be used as a non-invasive ocular predictor of cephalic autonomic nervous system integrity. Spectral sensitivity of the pupil's response to light has, for some time, been an interesting issue. It has generally, however, only been investigated with the use of white light and studies with monochromatic wavelengths are scarce. This study investigates the effects of wavelength and age within three parameters of the pupil light reflex (amplitude of response, latency, and velo...

  7. Diagnostics of defects in AlGaN/GaN high electron mobility transitor (HEMT) epi-layers via spectroscopic photo current-voltage (IV) measurements with variable-wavelength ultraviolet (UV) and visible light excitation

    Science.gov (United States)

    Khanal, Min P.; Ozden, Burcu; Mirkhani, Vahid; Yapabandara, Kosala; Shehzad Sultan, Muhammad; Park, Minseo; Shen, Li

    The reliability and performance of the nitride high electron mobility transistors (HEMTs) have been plagued by deleterious phenomena such as current collapse which is believed to be produced by electrically-active deep-level defects (or traps) that reside at the surface/interfaces and in the bulk of the AlGaN/GaN HEMT layers. Therefore, identification of their physical/spectral locations and understanding the nature of defects is very important to improve the reliability of AlGaN/GaN HEMTs. In this work, deep-level defects and traps located in the AlGaN/GaN HEMT epi-layers were investigated by using spectroscopic photo IV measurements. An array of Schottky contacts was constructed on the HEMT layer produced by metal-organic chemical vapor deposition (MOCVD). The photo IV measurement was performed by collecting the photo current generated by the variable-wavelength UV/visible light illumination. It was successfully demonstrated that this technique can provide the information on the distribution of electrically-active defects along the in-depth direction and across the HEMT wafers. Therefore, it can be concluded that the spectroscopic measurements can be useful to assess the uniformity of defect distribution both along the in-depth direction and across the AlGaN/GaN wafers. Corresponding author.

  8. Wavelength conversion devices

    DEFF Research Database (Denmark)

    Mikkelsen, Benny; Durhuus, Terji; Jørgensen, Carsten

    1996-01-01

    system requirements. The ideal wavelength converter should be transparent to the bit rate and signal format and provide an unchirped output signal with both a high extinction ratio and a large signal-to-noise ratio. It should allow conversion to both shorter and longer wavelengths with equal performance...

  9. What is the $Wb\\bar{b}, Zb\\bar{b}$ or $t\\bar{t}b\\bar{b}$ irreducible background to the light Higgs boson searches at LHC?

    CERN Document Server

    Kersevan, Borut P; Kersevan, Borut Paul

    2002-01-01

    The W b anti-b, Z b anti-b and t anti-t b anti-b production at LHC are irreducible backgrounds for possible observability of the Standard Model (SM) and Minimal Supersymmetric Standard Model (MSSM) light Higgs boson respectively in the associated WH, ZH and t anti-t H production followed by the H -> b anti-b decay. We present a comparison of the background estimates as obtained with (a) complete massive matrix element implemented in AcerMC Monte Carlo generator and (b) PYTHIA implementation of the inclusive W, Z, and t anti-t production, followed by the parton showering mechanism. Both approaches lead to a production of the final state of interest, but differ in the approximations used. We concentrate on the comparison of these approaches for the background to the light Higgs boson searches at LHC.

  10. 不同波长的光照射对视网膜色素上皮细胞生长及其分泌生长因子的影响%Effects of different wave-length lights on proliferation and secretion of growth factors in human retinal pigment epithelium cells

    Institute of Scientific and Technical Information of China (English)

    郑晓汾; 康玉国; 褚仁远

    2011-01-01

    异均有统计学意义(P<0.05)。RT-PCR结果显示,不同波长光照射后RPE细胞中HGF mRNA的表达水平不同,蓝光下培养的RPE细胞HGF mRNA表达量最少,白光组、红光组和蓝光组HGF mRNA的表达量(A490)与对照组比较差异均有统计学意义( P<0.05)。透射电子显微镜下红光组、白光组人胚RPE细胞与对照组相比超微结构均无明显变化,但蓝光组RPE细胞核染色质稀疏变淡,细胞器减少,细胞界膜不清或消失。结论不同波长的光照射可影响人RPE细胞的增生及其分泌HGF、bFGF和TGF-β的功能,提示近视的形成可能与不同波长的光相互作用有关。%Background The study of myopia development is always the hotspot worldwide. Recently,scientist found that some growth factor secreted by retinal nerve epithelium cells and retinal pigment epithelium(RPE)cells are associated with the development of myopia. Whenever, the absorption of RPE cells to different wave-length lights is different. ObjectiveThis study was to investigate the effects of different wave-lengths lights on the proliferation of human RPE cells, and explore the influence of different wave-lengths lights on RPE cells secreting hepatocyte growth factor(HGF) ,basic fibroblast growth factor(bFGF) and transforming growth factor-β(TGF-β).Methods The fourth to fifth passages of human embryonic RPE cells were exposed to blue light( λ =480 nm),red light( λ =775 nm) and white light. The cells of control group were harvested in normal condition. The proliferation and growth of RPE cells were assayed by MTT,and the ultrastructure of cells was examined under the transmission electron microscopy at 48 hours after light exposure of RPE cells. Enzyme linked immunosorbent assay(ELISA) was adopted to determine the concentrations of HGF,bFGF and TGF-β in the culture medium in 12,24,48,72 hours. The expression of HGF mRNA in RPE cells was detected by RT-PCR. This study was approved by Ethic committee of Fudan University. Results

  11. A 12 GHz wavelength spacing multi-wavelength laser source for wireless communication systems

    Science.gov (United States)

    Peng, P. C.; Shiu, R. K.; Bitew, M. A.; Chang, T. L.; Lai, C. H.; Junior, J. I.

    2017-08-01

    This paper presents a multi-wavelength laser source with 12 GHz wavelength spacing based on a single distributed feedback laser. A light wave generated from the distributed feedback laser is fed into a frequency shifter loop consisting of 50:50 coupler, dual-parallel Mach-Zehnder modulator, optical amplifier, optical filter, and polarization controller. The frequency of the input wavelength is shifted and then re-injected into the frequency shifter loop. By re-injecting the shifted wavelengths multiple times, we have generated 84 optical carriers with 12 GHz wavelength spacing and stable output power. For each channel, two wavelengths are modulated by a wireless data using the phase modulator and transmitted through a 25 km single mode fiber. In contrast to previously developed schemes, the proposed laser source does not incur DC bias drift problem. Moreover, it is a good candidate for radio-over-fiber systems to support multiple users using a single distributed feedback laser.

  12. Wavelength conversion based spectral imaging

    DEFF Research Database (Denmark)

    Dam, Jeppe Seidelin

    There has been a strong, application driven development of Si-based cameras and spectrometers for imaging and spectral analysis of light in the visible and near infrared spectral range. This has resulted in very efficient devices, with high quantum efficiency, good signal to noise ratio and high...... resolution for this spectral region. Today, an increasing number of applications exists outside the spectral region covered by Si-based devices, e.g. within cleantech, medical or food imaging. We present a technology based on wavelength conversion which will extend the spectral coverage of state of the art...... visible or near infrared cameras and spectrometers to include other spectral regions of interest....

  13. 785nm dual-wavelength Y-branch DBR-RW diode laser with electrically adjustable wavelength distance between 0 nm and 2 nm

    Science.gov (United States)

    Sumpf, Bernd; Kabitzke, Julia; Fricke, Jörg; Ressel, Peter; Müller, André; Maiwald, Martin; Tränkle, Günther

    2017-02-01

    Shifted excitation Raman difference spectroscopy is a powerful tool to separate the weak Raman lines from disturbing background light like fluorescence, day light or artificial light. When exciting the sample alternatingly with two slightly shifted wavelengths, the Raman lines follow the change whereas the background remains unchanged. Therefore, background free Raman spectra can be obtained measuring the two Raman spectra, subtracting the two signals and applying a reconstruction algorithm. When the spectral distance between the two wavelengths is the width of the Raman lines under study best signal-to-noise ratios can be achieved. In this work, monolithic dual wavelength Y-branch DBR ridge waveguide diode lasers with resistor heaters over the DBR gratings will be presented. The devices have a total length of 3 mm and a RW stripe width of 2.2 μm. The wavelengths are defined and stabilized using 500 μm long 10th order gratings with a designed spectral distance of 0.62 nm. Using the resistor heaters, this distance can be adjusted. The monolithic devices reach optical output powers up to 180 mW. Over the full range, they operate in single mode. The emission width is smaller than 13 pm (FWHM). At an output power of 50 mW the conversion efficiency is 0.22, which only slightly decreases down to 0.18 at maximal power. At an output power of 100 mW and with heater currents smaller than 600 mA, the spectral distance can be tuned from 0 nm up to 2 nm. The spectra remain single mode.

  14. Background Material

    DEFF Research Database (Denmark)

    Zandersen, Marianne; Hyytiäinen, Kari; Saraiva, Sofia

    2016-01-01

    This document serves as a background material to the BONUS Pilot Scenario Workshop, which aims to develop harmonised regional storylines of socio-ecological futures in the Baltic Sea region in a collaborative effort together with other BONUS projects and stakeholders.......This document serves as a background material to the BONUS Pilot Scenario Workshop, which aims to develop harmonised regional storylines of socio-ecological futures in the Baltic Sea region in a collaborative effort together with other BONUS projects and stakeholders....

  15. COBE Observations of the Cosmic Infrared Background

    CERN Document Server

    Wright, E L

    2004-01-01

    The Diffuse InfraRed Background Experiment on COBE measured the total infrared signal seen from space at a distance of 1 astronomical unit from the Sun. Using time variations as the Earth orbits the Sun, it is possible to remove most of the foreground signal produced by the interplanetary dust cloud [zodiacal light]. By correlating the DIRBE signal with the column density of atomic hydrogen measured using the 21 cm line, it is possible to remove most of the foreground signal produced by interstellar dust, although one must still be concerned by dust associated with H_2 (molecular gas) and H II (the warm ionized medium). DIRBE was not able to determine the CIRB in the 5-60 micron wavelength range, but did detect both a far infrared background and a near infrared background. The far infrared background has an integrated intensity of about 34 nW/m^2/sr, while the near infrared and optical extragalactic background has about 59 nW/m^2/sr. The Far InfraRed Absolute Spectrophotometer (FIRAS) on COBE has been used to...

  16. Influence of blue light spectrum filter on short-wavelength and standard automated perimetries Influência de filtro para o espectro azul da luz na perimetria computadorizada branco-branco e azul-amarelo

    Directory of Open Access Journals (Sweden)

    Leonardo Cunha Castro

    2006-10-01

    Full Text Available PURPOSE: To evaluate the influence of a blue light spectrum filter (BLSF, similar in light spectrum transmittance to the intraocular lens Acrysof NaturalTM, on standard automated perimetry (SAP and short-wavelength automated perimetry (SWAP. METHODS: Twenty young individuals (OBJETIVO: Avaliar a influência de um filtro para o espectro azul da luz, semelhante à lente intra-ocular Acrysof Natural®, nos exames de perimetria automatizada padrão (branco-no-branco e de comprimento de onda curto (azul-no-amarelo. MÉTODOS: Vinte pacientes jovens sem alterações oculares (20 olhos realizaram seqüência de 4 exames de campo visual: perimetria automatizada padrão e azul-no-amarelo com e sem o filtro para o espectro azul da luz. Os índices de limiar foveal (FT, desvio médio (MD e desvio-padrão (PSD obtidos em todos os exames e a diferença causada pela excentricidade nos exames de perimetria automatizada azul-no-amarelo foram analisados. Variabilidade interindivíduos (desvio-padrão dos pontos testados foi calculada. RESULTADOS: Observou-se redução estatisticamente significante no desvio médio (p<0.001 e no limiar foveal (p<0.001 medidos pela perimetria automatizada azul-no-amarelo com o uso do filtro para o espectro azul da luz comparado quando realizado sem o filtro. Nenhum outro índice avaliado apresentou diferença estatisticamente significante nos exames de perimetria automatizada padrão ou azul-no-amarelo. Foi notado aumento da variabilidade interindivíduos com a excentricidade nos exames de perimetria automatizada azul-no-amarelo com e sem o uso do filtro para o espectro azul da luz, assim como a diferença de sensibilidade entre os hemisférios inferior e superior (hemisfério inferior menos superior, mas não houve diferença estatisticamente significante quando comparados os exames com e sem o uso do filtro. Quando foram comparados os 4 pontos mais inferiores e os 4 pontos mais superiores, a diferença inferior-superior aumentou

  17. Performance of Wavelength-Shifting Fibers for the Mu2e Cosmic Ray Veto Detector

    CERN Document Server

    DeZoort, G; Kessenich, H; Oksuzian, Y; Rase, T; Shooltz, D

    2015-01-01

    The Mu2e experiment will search for a neutrino-less muon-to-electron conversion process with almost four orders of magnitude of sensitivity improvement relative to the current best limit. One important background is caused by cosmic ray muons, and particles produced by their decay or interactions, mimicking the conversion electron signature. In order to reach the design sensitivity, Mu2e needs to obtain a cosmic ray veto (CRV) efficiency of 99.99\\%. The CRV system consists of four layers of plastic scintillating counters read out by silicon photo-multipliers (SiPM) through wavelength shifting fibers. The CRV counters must produce sufficient photo statistics in order to achieve the required veto efficiency. We study the light properties of several wavelength shifting fiber sizes in order to optimize the total light yield for the CRV system. The measurements are performed using a scanner designed to ensure fiber quality for the CRV.

  18. The extragalactic IR background

    CERN Document Server

    De Zotti, G; Mazzei, P; Toffolatti, L; Danese, L; De Zotti, G; Franceschini, A; Mazzei, P; Toffolatti, L; Danese, L

    1994-01-01

    Current limits on the intensity of the extragalactic infrared background are consistent with the expected contribution from evolving galaxies. Depending on the behaviour of the star formation rate and of the initial mass function, we can expect that dust extinction during early evolutionary phases ranges from moderate to strong. An example of the latter case may be the ultraluminous galaxy IRAS F10214 + 4724. The remarkable lack of high redshift galaxies in faint optically selected samples may be indirect evidence that strong extinction is common during early phases. Testable implications of different scenarios are discussed; ISO can play a key role in this context. Estimates of possible contributions of galaxies to the background under different assumptions are presented. The COBE/FIRAS limits on deviations from a blackbody spectrum at sub-mm wavelengths already set important constraints on the evolution of the far-IR emission of galaxies and on the density of obscured (``Type 2'') AGNs. A major progress in ...

  19. The determination of total cGMP levels in rod outer segments from intact toad photoreceptors in response to light superimposed on background and to consecutive flashes: a second light flash accelerates the dark recovery rate of cGMP levels in control media, but not in Na(+)-free, low Ca2+ medium.

    Science.gov (United States)

    Cohen, A I; Blazynski, C

    1993-01-01

    In previous experiments we established that a light flash reduced cGMP levels of toad rod outer segments within the transduction time interval, but that recovery of the dark level of cGMP occurred more slowly than reported electrophysiological recovery of membrane potential. We now report that a second light flash accelerates the recovery rate of total cGMP following an initial flash, but that this acceleration is blocked in a medium which is both sodium and calcium deficient. We also noted that calcium deficiency only elevated cGMP levels when sodium was present. For other experiments, we recorded ERG or aspartate isolated PIII responses from eyecups or retinas mounted on our quick-freeze apparatus, the light stimuli originating from the double light-bench of the latter. Whereas background illumination depressed cGMP, no detectable further cGMP loss accompanied the electrical response to a flash superimposed on the background.

  20. Dual-wavelength optical fluidic glucose sensor using time series analysis of d(+)-glucose measurement

    Science.gov (United States)

    Tang, Jing-Yau; Chen, Nan-Yueh; Chen, Ming-Kun; Wang, Min-Haw; Jang, Ling-Sheng

    2016-10-01

    This paper presents a rising-edge time-series analysis (TSA) method that can be applied to a dual-wavelength optical fluidic glucose sensor (DWOFGS). In the experiment, the concentration of glucose in phosphate buffered saline (PBS) was determined by measuring the absorbance of the solution as determined by variation in the rising edge of the photodiode (PD) voltage response waveform. The DWOFGS principle is based on near-infrared (NIR) absorption spectroscopy at selected dual wavelengths (1450 and 1650 nm) in the first overtone band. The DWOFGS comprises two light-emitting diodes (LEDs) and two PD detectors. No additional fibers or lenses are required in our device. The output light level of the LEDs is adjusted to a light intensity suitable to the glucose absorption rate in an electronic circuit. Four light absorbance paths enable detection of d(+)-glucose concentrations from 0 to 20 wt % in steps of 5 wt %. The glucose light absorbance process was calculated based on the rising edge of the PD waveform under a low-intensity light source using TSA. The TSA method can be used to obtain the glucose level in PBS and reduce measurement background noise. The application of the rising-edge TSA method improves sensor sensitivity, increases the accuracy of the data analysis, and lowers measurement equipment costs.

  1. Wavelength conversion technology

    DEFF Research Database (Denmark)

    Stubkjær, Kristian

    1998-01-01

    Optical wavelength conversion is currently attracting much interest. This is because it enables full flexibility and eases management of WDM fibre networks. The tutorial will review existing and potential application areas. Examples of node architectures and network demonstrators that use wavelen...

  2. Advanced Light Source (ALS)

    Data.gov (United States)

    Federal Laboratory Consortium — The Advanced Light Source (ALS), a world leader in soft x-ray science, generates light in the wavelengths needed for examining the atomic and electronic structure of...

  3. An economic Fabry-Perot wavelength reference

    Science.gov (United States)

    Fżrész, Gábor; Glenday, Alex; Latham, Christian

    2014-07-01

    Precision radial velocity (PRV) measurements are key in studying exoplanets, and so are wavelength calibrators in PRV instruments. ThAr lamps offer an affordable but somewhat limited solution for the visible passband. Laser frequency combs are ideal calibrators, except the (still) narrow wavelength coverage and large price tag. White light Fabry-Perot (FP) calibrators offer frequency-comb like properties in a more affordable and less complicated package1. Using a commercial solid FP etalon and off-the shelf components we have constructed an economic FP calibrator suitable for observatories on a smaller budget.

  4. Green light induces shade avoidance symptoms.

    Science.gov (United States)

    Zhang, Tingting; Maruhnich, Stefanie A; Folta, Kevin M

    2011-11-01

    Light quality and quantity affect plant adaptation to changing light conditions. Certain wavelengths in the visible and near-visible spectrum are known to have discrete effects on plant growth and development, and the effects of red, far-red, blue, and ultraviolet light have been well described. In this report, an effect of green light on Arabidopsis (Arabidopsis thaliana) rosette architecture is demonstrated using a narrow-bandwidth light-emitting diode-based lighting system. When green light was added to a background of constant red and blue light, plants exhibited elongation of petioles and upward leaf reorientation, symptoms consistent with those observed in a shaded light environment. The same green light-induced phenotypes were also observed in phytochrome (phy) and cryptochrome (cry) mutant backgrounds. To explore the molecular mechanism underlying the green light-induced response, the accumulation of shade-induced transcripts was measured in response to enriched green light environments. Transcripts that have been demonstrated to increase in abundance under far-red-induced shade avoidance conditions either decrease or exhibit no change when green light is added. However, normal far-red light-associated transcript accumulation patterns are observed in cryptochrome mutants grown with supplemental green light, indicating that the green-absorbing form of cryptochrome is the photoreceptor active in limiting the green light induction of shade-associated transcripts. These results indicate that shade symptoms can be induced by the addition of green light and that cryptochrome receptors and an unknown light sensor participate in acclimation to the enriched green environment.

  5. Planarian Phototactic Assay Reveals Differential Behavioral Responses Based on Wavelength.

    Directory of Open Access Journals (Sweden)

    Taylor R Paskin

    Full Text Available Planarians are free-living aquatic flatworms that possess a well-documented photophobic response to light. With a true central nervous system and simple cerebral eyes (ocelli, planarians are an emerging model for regenerative eye research. However, comparatively little is known about the physiology of their photoreception or how their behavior is affected by various wavelengths. Most phototactic studies have examined planarian behavior using white light. Here, we describe a novel planarian behavioral assay to test responses to small ranges of visible wavelengths (red, blue, green, as well as ultraviolet (UV and infrared (IR which have not previously been examined. Our data show that planarians display behavioral responses across a range of wavelengths. These responses occur in a hierarchy, with the shortest wavelengths (UV causing the most intense photophobic responses while longer wavelengths produce no effect (red or an apparent attraction (IR. In addition, our data reveals that planarian photophobia is comprised of both a general photophobic response (that drives planarians to escape the light source regardless of wavelength and wavelength-specific responses that encompass specific behavioral reactions to individual wavelengths. Our results serve to improve the understanding of planarian phototaxis and suggest that behavioral studies performed with white light mask a complex behavioral interaction with the environment.

  6. Metadevice for intensity modulation with sub-wavelength spatial resolution

    CERN Document Server

    Cencillo-Abad, Pablo; Plum, Eric

    2016-01-01

    Effectively continuous control over propagation of a beam of light requires light modulation with pixelation that is smaller than the optical wavelength. Here we propose a spatial intensity modulator with sub-wavelength resolution in one dimension. The metadevice combines recent advances in reconfigurable nanomembrane metamaterials and coherent all-optical control of metasurfaces. It uses nanomechanical actuation of metasurface absorber strips placed near a mirror in order to control their interaction with light from perfect absorption to negligible loss, promising a path towards dynamic beam diffraction, light focusing and holography without unwanted diffraction artefacts.

  7. What are the ideal wavelengths for full color holography?

    Science.gov (United States)

    Bazargan, Kaveh

    2013-02-01

    One of the holy grails in display holography is the production of natural color holographic images. Various sets of wavelengths for recording have been suggested, some favoring three wavelengths, some four, and even more. I will argue that the choice of recording wavelengths is completely independent of the holographic process; it was in fact was solved once and for all by scientists working in general lighting in the 1970s. I will suggest an ideal set of wavelengths which will produce color rendition equal to better than conventional photographic processes.

  8. Strictly Transparent Wavelength Conversion Using Multi-Wavelength Signal Generation

    Institute of Scientific and Technical Information of China (English)

    Eiichi; Yamada; Hiroaki; Sanjoh; Yuzo; Yoshikuni

    2003-01-01

    We succeeded in strictly transparent wavelength conversion by means of channel selection from multi-wavelength signals generated by sinusoidal modulation of input signal. Modulation-format-independent and bit-rate-independent wavelength conversion is achieved with small power penalty.

  9. Solar synthesis: prospects in visible light photocatalysis

    National Research Council Canada - National Science Library

    Schultz, Danielle M; Yoon, Tehshik P

    2014-01-01

    .... Nevertheless, the use of visible light in photochemical synthesis is fundamentally challenging because organic molecules tend not to interact with the wavelengths of visible light that are most...

  10. Wavelength-switchable photocurrent in a hybrid TiO2-Ag nanocluster photoelectrode.

    Science.gov (United States)

    Chen, Hongjun; Wang, Qiong; Lyu, Miaoqiang; Zhang, Zhi; Wang, Lianzhou

    2015-08-04

    A hybrid TiO2-Ag nanocluster (NC) photoelectrode demonstrates unique wavelength-switchable photocurrent. By simply tuning the light wavelength from ultraviolet (UV) to visible light, the photocurrent generated on a single electrode can be switched from anodic to cathodic current, in which the Ag NCs behave like a new type of visible light active photocatalyst.

  11. The influence of chromatic background on the photosensitivity of tilapia erythrophores

    Directory of Open Access Journals (Sweden)

    Shyh-Chi Chen

    2014-01-01

    Non-mammalian vertebrates and invertebrates use extraretinal photoreceptors to detect light and perform diverse non-image-forming functions. Compared to well-studied visual systems, the effect of ambient light conditions on photosensory systems of extraretinal photoreceptors is poorly understood. Chromatophores are photosensitive dermal pigment cells that play an important role in the formation of body color patterns to fit the surrounding environment. Here, we used tilapia erythrophores to investigate the relationship between environmental light and chromatophore photoresponses. All erythrophores from three spectral conditions aggregated their pigment granules in UV/short wavelengths and dispersed in middle/long wavelengths. Unlike retinal visual systems, environmental light did not change the usage of the primary opsins responsible for aggregation and dispersion. In addition, short wavelength-rich and red-shifted background conditions led to an inhibitory effect on erythrophore photoresponses. We suggest that, as extraretinal photoreceptors for non-image-forming functions, chromatophores directly adjust their photoresponse sensitivity via changes in opsin expression levels rather than opsin types when environmental light changes.

  12. The influence of chromatic background on the photosensitivity of tilapia erythrophores.

    Science.gov (United States)

    Chen, Shyh-Chi; Hornsby, Mark A W; Robertson, R Meldrum; Hawryshyn, Craig W

    2014-02-15

    Non-mammalian vertebrates and invertebrates use extraretinal photoreceptors to detect light and perform diverse non-image-forming functions. Compared to well-studied visual systems, the effect of ambient light conditions on photosensory systems of extraretinal photoreceptors is poorly understood. Chromatophores are photosensitive dermal pigment cells that play an important role in the formation of body color patterns to fit the surrounding environment. Here, we used tilapia erythrophores to investigate the relationship between environmental light and chromatophore photoresponses. All erythrophores from three spectral conditions aggregated their pigment granules in UV/short wavelengths and dispersed in middle/long wavelengths. Unlike retinal visual systems, environmental light did not change the usage of the primary opsins responsible for aggregation and dispersion. In addition, short wavelength-rich and red-shifted background conditions led to an inhibitory effect on erythrophore photoresponses. We suggest that, as extraretinal photoreceptors for non-image-forming functions, chromatophores directly adjust their photoresponse sensitivity via changes in opsin expression levels rather than opsin types when environmental light changes.

  13. Multi-wavelength Laser Photoacoustics

    Science.gov (United States)

    2012-09-01

    Multi-wavelength Laser Photoacoustics by Kristan P. Gurton, Melvin Felton, and Richard Tober ARL-TR-6147 September 2012...2012 Multi-wavelength Laser Photoacoustics Kristan P. Gurton and Melvin Felton Computational and Information Sciences Directorate, ARL...REPORT TYPE Final 3. DATES COVERED (From - To) June 1, 2012 4. TITLE AND SUBTITLE Multi-wavelength Laser Photoacoustics 5a. CONTRACT NUMBER

  14. Imaging the Spatial Fluctuations in Cosmic IR Background from Reionization with CIBER

    Science.gov (United States)

    Frazer, Chris; Bock, J.; Cooray, A.; Kawada, M.; Kim, M.; Lee, D.; Levenson, L.; Matsumoto, T.; Matsumuura, S.; Mitchell-Wynne, K.; Renbarger, T.; Smidt, J.; Sullivan, I.; Arai, T.; Tsumura, K.; Wada, T.; Zemcov, M.

    2011-01-01

    The Cosmic Infrared Background Experiment (CIBER) is a rocket-born absolute photometry imaging and spectroscopy experiment optimized to detect unresolved infrared signatures of first-light galaxies that were present during reionization. The signatures from reionization are theorized to be dominant at the wavelengths upon which CIBER surveys. CIBER consists of two wide field imagers to measure the extragalactic background fluctuations in the H and I-Bands (1.6 and 0.9 microns respectively) of the cosmic infrared background (CIB) as well as two spectrometers designed to take measurements of the foreground zodiacal light and the absolute Extragalactic Background Light (EBL) spectrum They imagers are capable of examining high-redshift (z 10-20) CIB fluctuations which will facilitate in the study of surface densities of sources associated with reionization. Studies of galaxies with similar redshift parameters (z > 6) are largely unaccounted for. The spectrometer configuration consists of one low resolution spectrometer and one narrow band spectrometer. They are respectively designed to take measurements of the absolute Extragalactic Background Light (EBL) spectrum, and foreground zodiacal light. In this poster we present the specifications for both CIBER imagers and detail how the fluctuations from galaxies during reionization will be measured.

  15. High-accuracy absolute distance measurement by two-wavelength double heterodyne interferometry with variable synthetic wavelengths

    CERN Document Server

    Kuramoto, Yoshiyuki

    2014-01-01

    We present an absolute distance measurement interferometer based on a two wavelength interferometer and a variable synthetic wavelength technique. The wavelength scanning range was 12 GHz, realized with a phase accuracy of 1.0 m{\\lambda} by heterodyne detection at each measurement wavelength. This small wavelength scanning range enabled the use of distributed feedback laser diodes as an interferometer light source and a fast 20 ms wavelength scanning time by injection current control. We demonstrated a measurement range of up to 1.5 m and an accuracy better than 1.2 nm in comparison with a displacement measurement interferometer, corresponding to a relative accuracy of 10-9. In addition, we also proposed expanding the range of maximum measurement and compensation of refractive index of air for linear colliders.

  16. Comets at radio wavelengths

    CERN Document Server

    Crovisier, Jacques; Colom, Pierre; Biver, Nicolas

    2016-01-01

    Comets are considered as the most primitive objects in the Solar System. Their composition provides information on the composition of the primitive solar nebula, 4.6 Gyr ago. The radio domain is a privileged tool to study the composition of cometary ices. Observations of the OH radical at 18 cm wavelength allow us to measure the water production rate. A wealth of molecules (and some of their isotopologues) coming from the sublimation of ices in the nucleus have been identified by observations in the millimetre and submillimetre domains. We present an historical review on radio observations of comets, focusing on the results from our group, and including recent observations with the Nan\\c{c}ay radio telescope, the IRAM antennas, the Odin satellite, the Herschel space observatory, ALMA, and the MIRO instrument aboard the Rosetta space probe.

  17. Optoelectronic Properties of Dual-wavelength InGaN/GaN Multi-quantum Well Light-emitting Diodes%双波长InGaN/GaN多量子阱发光二极管的光电特性

    Institute of Scientific and Technical Information of China (English)

    陈献文; 吴乾; 李述体; 郑树文; 何苗; 范广涵; 章勇

    2011-01-01

    In order to realize preferable white light-emitting diodes with high color rendering index and optimized luminous efficiency, white InGaN/GaN multi-quantum-well dual-wavelength light-emitting diodes (LEDs) were grown on (0001)-oriented sapphire substrates by metal-organic chemical vapor deposition (MOCVD). Photoluminescence and electroluminescence properties of dual-wavelength LEDs with different I(.n) content were also studied. The experimental results indicated that In component plays a critical role on stability for electroluminescence spectrum and luminous efficiency ofthe dual-wavelength LED structures. In addition, YAG: Ce phosphor-converted white light emission with high color rendering index was achieved using dual-blue emitting active regions.%为了实现高显色指数和流明效率的白光发光二极管,在(0001)蓝宝石衬底上利用金属有机化学气相沉积系统,生长了双波长发射的InGaN/GaN多量子阱发光二极管结构.通过对不同In组分含量的双波长发射发光二极管结构的光致发光和电致发光性能进行分析,结果表明In组分含量对双波长发射发光二极管的光致发光谱的稳定性及发光效率有重要影响.此外,用双蓝光发射的芯片来激发YAG:Ce荧光粉实现了高显色指数白光发射.

  18. Cyclic polling-based dynamic wavelength and bandwidth allocation in wavelength division multiplexing passive optical networks

    Institute of Scientific and Technical Information of China (English)

    Zhengcheng Xie; Hui Li; Yuefeng Ji

    2009-01-01

    Cyclic polling-based dynamic wavelength and bandwidth allocation algorithm supporting differentiated classes of services in wavelength division multiplexing (WDM) passive optical networks (PONs) is proposed. In this algorithm, the optical line terminal (OLT) polls for optical network unit (ONU) requests to transmit data in a cyclic manner. Services are categorized into three classes: expedited forward (EF) priority, assured forwarding (AF) priority, and best effort (BE) priority. The OLT assigns bandwidth for different priorities with different strategies. Simulation results show that the proposed algorithm saves a lot of downstream bandwidth under low load and does not show the light-load penalty compared with the simultaneous and interleaved polling schemes.

  19. Red emitting monolithic dual wavelength DBR diode lasers for shifted excitation Raman difference spectroscopy

    Science.gov (United States)

    Sumpf, B.; Maiwald, M.; Müller, A.; Bugge, F.; Fricke, J.; Ressel, P.; Pohl, J.; Erbert, G.; Tränkle, G.

    2014-02-01

    Raman lines are often obscured by background light or fluorescence especially when investigating biological samples or samples containing impurities. Shifted excitation Raman difference spectroscopy (SERDS) is a technique to overcome this. By exciting the sample with two slightly shifted wavelengths, it is possible to separate the Raman lines and distortions. In this paper, monolithic dual wavelength DBR diode lasers meeting the demands of Raman spectroscopy and SERDS will be presented. The wavelengths are stabilized and selected by using deeply-etched 10th order surface gratings with different periods manufactured using i-line wafer stepper lithography. Two possible resonator concepts, i.e. a mini-array of two parallel DBR RW-lasers and a Y-branch DBR laser, will be compared. Established excitation wavelengths for Raman spectroscopy at 671 nm and 785 nm are chosen. The total laser length is 3 mm; the ridge width is 2.2 μm for the 785 nm devices and 5 μm for the 671 nm lasers. The length of the DBR gratings is 500 μm. The devices at 671 nm reach output powers up to 100 mW having an emission width smaller than 12 pm (FWHM). The 785 nm lasers show output powers up to 200 mW and a narrow emission below 22 pm. For the dual wavelength lasers the spectral distance between the two excitation lines is about 0.5 nm as targeted. The power consumption at both wavelengths is below 1 W. These data proof that the devices are well suited for their application in portable Raman measurement systems such as handheld devices using SERDS.

  20. Peripheral detection and resolution with mid-/long-wavelength and short-wavelength sensitive cone systems.

    Science.gov (United States)

    Zhu, Hai-Feng; Zele, Andrew J; Suheimat, Marwan; Lambert, Andrew J; Atchison, David A

    2016-08-01

    This study compared neural resolution and detection limits of the human mid-/long-wavelength and short-wavelength cone systems with anatomical estimates of photoreceptor and retinal ganglion cell spacings and sizes. Detection and resolution limits were measured from central fixation out to 35° eccentricity across the horizontal visual field using a modified Lotmar interferometer. The mid-/long-wavelength cone system was studied using a green (550 nm) test stimulus to which S-cones have low sensitivity. To bias resolution and detection to the short-wavelength cone system, a blue (450 nm) test stimulus was presented against a bright yellow background that desensitized the M- and L-cones. Participants were three trichromatic males with normal visual functions. With green stimuli, resolution showed a steep central-peripheral gradient that was similar between participants, whereas the detection gradient was shallower and patterns were different between participants. Detection and resolution with blue stimuli were poorer than for green stimuli. The detection of blue stimuli was superior to resolution across the horizontal visual field and the patterns were different between participants. The mid-/long-wavelength cone system's resolution is limited by midget ganglion cell spacing and its detection is limited by the size of the M- and L-cone photoreceptors, consistent with previous observations. We found that no such simple relationships occur for the short-wavelength cone system between resolution and the bistratified ganglion cell spacing, nor between detection and the S-cone photoreceptor sizes.

  1. A low density of the extragalactic background light revealed by the H.E.S.S. spectra of the BL Lac objects 1ES 1101-232 and H 2356-309

    Science.gov (United States)

    Costamante, Luigi

    2007-06-01

    The study of the TeV emission from extragalactic sources is hindered by the uncertainties on the diffuse Extragalactic Background Light (EBL). The recent H.E.S.S. results on the blazars 1ES 1101-232 and H 2356-309 represent a breakthrough on this issue. Their unexpectedly hard spectra allow an upper limit to be derived on the EBL in the optical/near-infrared range, which is very close to the lower limit given by the resolved galaxy counts. This result seems to exclude a large contribution to the EBL from other sources (e.g. Population III stars) and indicates that the intergalactic space is more transparent to γ-rays than previously thought. A discussion of EBL absorption effects and further observational tests with Cherenkov telescopes are presented.

  2. A low density of the Extragalactic Background Light revealed by the H.E.S.S. spectra of the BLLac objects 1ES 1101-232 and H 2356-309

    CERN Document Server

    Costamante, L

    2006-01-01

    The unexpectedly hard spectra measured by HESS for the BLLacs 1ES 1101-232 and H 2356-309 has allowed an upper limit on the Extragalactic Background Light (EBL) to be derived in the optical/near-infrared range, which is very close to the lower limit given by the resolved galaxy counts. This result seems to exclude a large contribution to the EBL from other sources (e.g. Population III stars) and indicates that the intergalactic space is more transparent to gamma-rays than previously thought. A brief discussion of EBL absorption effects on blazar spectra and further observational tests to check this conclusion are presented, including the selection of new candidates for observations with Cherenkov telescopes.

  3. Wavelength-conserving grating router for intermediate wavelength density

    Science.gov (United States)

    Deri, Robert J.; Patel, Rajesh R.; Bond, Steven W.; Bennett, Cory V.

    2007-03-20

    A wavelength router to be used for fiber optical networking router is based on a diffraction grating which utilizes only N wavelengths to interconnect N inputs to N outputs. The basic approach is to augment the grating with additional couplers or wavelength selective elements so than N-1 of the 2N-1 outputs are combined with other N outputs (leaving only N outputs). One embodiment uses directional couplers as combiners. Another embodiment uses wavelength-selective couplers. Another embodiment uses a pair of diffraction gratings to maintain parallel propagation of all optical beams. Also, beam combining can be implemented either by using retroflection back through the grating pair or by using couplers.

  4. 不同波长光照对开产初期母鸡间脑c-fos基因表达的影响%Effect of light stimulation by different wavelength on expression of c-fos gene in hen diencephalon at early laying period

    Institute of Scientific and Technical Information of China (English)

    张毅; 胡满; 程金金; 郭洁; 兰晓宇

    2009-01-01

    To investigate the nervous mechanism in the effect of light on egg-laying, the response of hen diencephalon to light stimulation by different wavelength were investigated by u-sing c-Fos and GnRH method. Unilateral eyes of 150 days old hens were kept dark for seven days. Then they accepted different wavelength light stimulation of 20 lx for 1. 5 hours and dark adaptation 1. 5 hours. After perfusion with fixative, their brains were removed from the skulls and were made into continuous paraffin sections. The distribution of imunoreactive positive neurons of Fos protein and GnRH in mesencephalon were examined using immunohistochemical method. The results showed that expression of c-fos gene and the release of GnRH could be in-fluenceed by different wavelength light stimulation. The expression induced by green and blue light stimulation was more significant than that by red one.%为深入了解不同波长光照对母鸡生产性能的影响机理,用c-Fos法探讨了母鸡间脑对不同波长光照的反应,同时检测GnRH免疫反应神经元的动态变化.将150日龄母鸡右眼遮光7 d后接受20 lx 的不同波长光照刺激1.5 h, 暗适应1.5 h后灌流固定,取脑制作石蜡切片,采用免疫组化方法检测Fos 蛋白和 GnRH 样免疫反应阳性神经元在间脑的分布.结果显示,不同波长光照均影响c-fos基因表达和GnRH的释放,绿光组和蓝光组的表达均高于红光组.

  5. An algorithm and a Tool for Wavelength Allocation in OMS-SP Ring Architecture

    DEFF Research Database (Denmark)

    Riaz, Muhammad Tahir; Pedersen, Jens Myrup; Madsen, Ole Brun

    2006-01-01

    OMS-SP ring is one of the well known architectures in Wavelength Division Multiplexing based optical fiber networks. The architecture supports a restorable full mesh in an optical fiber ring using multiple light wavelengths. The paper presents an algorithm to allocate wavelengths in the OMS-SP ring...

  6. Laser system with wavelength converter

    DEFF Research Database (Denmark)

    2012-01-01

    The present invention relates to an apparatus comprising a diode laser (10) providing radiation in a first wavelength interval, a radiation conversion unit (12) having an input and an output, the radiation converter configured to receive the radiation in the first wavelength interval from the diode...... laser at the input, the radiation conversion unit configured to convert the radiation in the first wavelength interval to radiation in a second wavelength interval and the output configured to output the converted radiation, the second wavelength interval having one end point outside the first...... wavelength interval. Further, the invention relates to a method of optically pumping a target laser (14) in a laser system, the laser system comprising a laser source providing radiation at a first frequency, the laser source being optically connected to an input of a frequency converter, the frequency...

  7. Mechanism of wavelength conversion in polystyrene doped with benzoxanthene: emergence of a complex

    Science.gov (United States)

    Nakamura, Hidehito; Shirakawa, Yoshiyuki; Kitamura, Hisashi; Sato, Nobuhiro; Shinji, Osamu; Saito, Katashi; Takahashi, Sentaro

    2013-01-01

    Fluorescent guest molecules doped in polymers have been used to convert ultraviolet light into visible light for applications ranging from optical fibres to filters for the cultivation of plants. The wavelength conversion process involves the absorption of light at short wavelengths followed by fluorescence emission at a longer wavelength. However, a precise understanding of the light conversion remains unclear. Here we show light responses for a purified polystyrene base substrates doped with fluorescent benzoxanthene in concentrations varied over four orders of magnitude. The shape of the excitation spectrum for fluorescence emission changes significantly with the concentration of the benzoxanthene, indicating formation of a base substrate/fluorescent molecule complex. Furthermore, the wavelength conversion light yield increases in three stages depending on the nature of the complex. These findings identify a mechanism that will have many applications in wavelength conversion materials. PMID:23974205

  8. Wavelength conversion devices and techniques

    DEFF Research Database (Denmark)

    Stubkjær, Kristian; Jørgensen, Carsten; Danielsen, Søren Lykke;

    1996-01-01

    Wavelength division multiplexed (WDM) networks are currently subject to an immense interest because of the extra capacity and flexibility they provide together with the possibilities for graceful system upgrades. For full network flexibility it is very attractive to be able to translate the chann...... wavelengths in an easy way and preferably without opto-electronic conversion. Here, we will first briefly look at advantages of employing optical wavelength converters in WDM networks and next review the optical wavelength conversion devices with emphasis on recent developments....

  9. Temperature dependence of alpha-induced scintillation in the 1,1,4,4-tetraphenyl-1,3-butadiene wavelength shifter

    CERN Document Server

    Veloce, L M; Di Stefano, P C F; Noble, A J; Boulay, M G; Nadeau, P; Pollmann, T; Clark, M; Piquemal, M; Schreiner, K

    2015-01-01

    Liquid noble gas based particle detectors often use the organic wavelength shifter 1,1,4,4-tetraphenyl-1,3-butadiene (TPB) which shifts UV scintillation light to the visible regime, facilitating its detection, but which also can scintillate on its own. Dark matter searches based on this type of detector commonly rely on pulse-shape discrimination (PSD) for background mitigation. Alpha-induced scintillation therefore represents a possible background source in dark matter searches. The timing characteristics of this scintillation determine whether this background can be mitigated through PSD. We have therefore characterized the pulse shape and light yield of alpha induced TPB scintillation at temperatures ranging from 300 K down to 4 K, with special attention given to liquid noble temperatures. We find that the pulse shapes and light yield depend strongly on temperature. In addition, the significant contribution of long time constants above ~50 K provides an avenue for discrimination between alpha decay events ...

  10. Nitride quantum light sources

    Science.gov (United States)

    Zhu, T.; Oliver, R. A.

    2016-02-01

    Prototype nitride quantum light sources, particularly single-photon emitters, have been successfully demonstrated, despite the challenges inherent in this complex materials system. The large band offsets available between different nitride alloys have allowed device operation at easily accessible temperatures. A wide range of approaches has been explored: not only self-assembled quantum dot growth but also lithographic methods for site-controlled nanostructure formation. All these approaches face common challenges, particularly strong background signals which contaminate the single-photon stream and excessive spectral diffusion of the quantum dot emission wavelength. If these challenges can be successfully overcome, then ongoing rapid progress in the conventional III-V semiconductors provides a roadmap for future progress in the nitrides.

  11. Sub-wavelength bubble in photon coincidence detection

    CERN Document Server

    Liu, Ruifeng; Zhou, Yu; Gao, Hong; Li, Fuli

    2013-01-01

    Sub-wavelength interference has a potential application in lithography to beat the classical Rayleigh limit of resolution. We carefully study the second-order correlation theory and find there is a bubble of sub-wavelength interference in photon coincidence detection. A Young's double-slit experiment with thermal light is carried out to test the second-order correlation pattern. The result shows that when different scanning ways of two point detectors are chosen, we can get arbitrary-wavelength interference patterns. We then give a theoretical explanation to this surprising result, and find this explanation is also suitable for the result by using entangled light. Furthermore, the question of whether this kind of arbitrary-wavelength interference patterns can be used in quantum lithography is also analyzed.

  12. A wavelength selective bidirectional isolator for access optical networks

    Science.gov (United States)

    Hu, Xi-kui; Huang, Zhang-di; Li, Su-shan; Xu, Fei; Chen, Beckham; Lu, Yan-qing

    2011-05-01

    A wavelength selective bidirectional optical isolator is proposed. Being different from conventional isolators, a well-designed wave plate is employed and works together with the Faraday rotator. Different wavelengths thus experience different phase retardation so that wavelength-dependent polarization states are obtained for bidirectional beams. As an example, a (1.49 μm, 1.31 μm) wavelength selective isolator is proposed, which means only 1.49 μm light can propagate along one-direction while the opposite wave is just for 1.31 μm light. Over 60 dB optical isolation is obtained by selecting suitable wave plate thickness and orientation. This interesting isolator may have promising applications in access optical networks.

  13. Performance Evaluation of Wavelength Routed Optical Network with Wavelength Conversion

    CERN Document Server

    Gond, Vitthal J

    2010-01-01

    The rapid development of telecommunication networks is driven by user demands for new applications and advances in technologies. The explosive growth of the internet traffic is due to its use for collecting the information, communication, multimedia application, entertainment, etc. These applications are imposing a tremendous demand for bandwidth capacity on telecommunication network. The introduction of fiber optics had proved to meet the huge demand of bandwidth. These requirement can be meet by all optical network which is capable of transmitting enormous data at very high speed, around 50 Tera bits per seconds (Tbps) A wavelength conversion technique is addressed in this paper to reduced the blocking probability in wavelength routed networks. It is seen that the blocking probability of traffic requests decreases as the wavelength conversion factor increases. We explode the possibility for network with different size with variation in wavelength per link. In this work the evaluation of wavelength routed op...

  14. Probing Reionization through Near-Infrared Background Fluctuations with CIBER

    Science.gov (United States)

    Sullivan, Ian S.

    2010-01-01

    The Cosmic Infrared Background Experiment (CIBER) is a NASA sounding rocket payload that was first launched in February 2009. CIBER consists of four co-aligned instruments designed with foreground subtraction and control of systematics in mind. In addition, the platform of a sounding rocket enables observations of the NIRB outside of narrow atmospheric windows that are uncontaminated by airglow. We will present preliminary results from the first flight. CIBER seeks to measure the absolute brightness spectrum of the extragalactic NIRB, and has two spectrometers dedicated to that purpose. One, a high-resolution Fabry-Perot spectometer, is tuned to the 8545 nm Ca II line of the solar spectrum, and is designed to measure the absolute brightness of the Zodiacal Light directly, which is the source of greatest uncertainty in the NIRB spectrum. The second spectrometer measures the NIRB spectrum from 700nm to 1800nm, which spans the wavelength range where a Lyman cutoff feature from Reionization could appear. CIBER also houses two Infrared imaging telescopes, which have identical optics that give 2º x 2º field of views with 7 arcsec pixels, but have different band defining filters. The first imager has a wide band centered at 1600nm, and images the background at the expected peak of the spectrum. The imagers’ wide field of view allows them to measure the distinctive power spectrum peaking at 10 arcminutes. The second imager has a wide band centered at 1000nm that is intended to image at wavelengths shorter than the Lyman cutoff, and provides a powerful systematic test for any detection made at 1600 nm. First-light fluctuations should have a distinctive spatial power spectrum with very red 1600nm / 1000nm color, distinctly redder than the approximately solar color of any residual fluctuations arising from Zodiacal light, Galactic starlight, or low-redshift galaxies.

  15. Updated analysis of near-infrared background fluctuations

    CERN Document Server

    Yue, Bin; Salvaterra, Ruben

    2016-01-01

    The power spectrum of Near InfraRed Background (NIRB) fluctuations measured at 3.6 $\\mu$m by {\\tt Spitzer} shows a clustering excess over the known galaxies signal that has been interpreted in terms of early ($z\\simgt 13$), accreting (direct collapse) black holes (DCBH) or low-$z$ intrahalo light (IHL). In addition, these fluctuations correlate with the cosmic X-ray background (CXB) measured at (0.5-2) keV, supporting the black hole explanation. This scenario has been questioned by the recent detection of a correlation between the two {\\tt CIBER} 1.1/1.6 $\\mu$m bands with the 3.6 $\\mu$m {\\tt Spitzer} one. This correlation is hardly explained by early DCBHs that, due to intergalactic absorption, cannot contribute to the shortest wavelength bands. Here we show that the new correlation is caused instead by a Diffuse Galactic Light (DGL) component arising from Galactic stellar light scattered by dust. The black hole interpretation of the excess remains perfectly valid and, actually, the inclusion of DGL allows le...

  16. Synchronous two-wavelength temporal interferometry

    Science.gov (United States)

    Zhang, Xiaoqiong; Gao, Zhan; Qin, Jie; Li, Guangyu; Feng, Ziang; Wang, Shengjia

    2016-09-01

    Interferometry is an optical measuring method with the character of non-destructive, high sensitivity and high accuracy. However, its measurement range is limited by the phase ambiguity. Hence the method with two separate different wavelengths light source is introduced to enlarge the measurement range. As for the two-wavelength interferometry case, phase shifting is the traditional way to acquire the phase map, it needs to repeat the measurement twice, which means the measurement cannot be accomplished in real time. Hence to solve the problem, a temporal sequence interferometry has been used. This method can obtain the desired phase information in real time by using the Fourier transform methods of the interferogram recorded in a sequence while the object is being deformed. But, it is difficult to retrieve the phase information directly due to the multi extreme points in one period of the cosine function. In this paper, an algorithm based on the wavelet ridge analysis is adopted to retrieve the two wavelength phase fluctuation caused by the displacement simultaneously. The preliminary experiment is conducted and the results are compared with theoretical simulations to validate the proposed approach. The laser emits light with two wavelengths 532 nm and 473 nm, two separated interference patterns in time sequence are detected by the CCD camera in the same time. The overlapped interferograms of two colors are analyzed by this algorithm and the corresponding phase information are obtained. The maximum error value between the simulation and theory is 0.03 um and the relative error is 0.33%.

  17. Long-wavelength 256x256 QWIP handheld camera

    Science.gov (United States)

    Gunapala, Sarath D.; Liu, J. K.; Sundaram, Mani; Bandara, Sumith V.; Shott, C. A.; Hoelter, T.; Maker, Paul D.; Muller, Richard E.

    1996-06-01

    In this paper, we discuss the development of very sensitive long wavelength infrared GaAs/AlxGa1-xAs quantum well infrared photodetectors (QWIPs), fabrication of random reflectors for efficient light coupling, and the demonstration of first hand-held long-wavelength 256 X 256 QWIP focal plane array camera. Excellent imagery, with a noise equivalent differential temperature of 25 mK has been achieved.

  18. The cosmic infrared background experiment (CIBER): instrumentation and first results

    Science.gov (United States)

    Zemcov, M.; Battle, J.; Bock, J.; Cooray, A.; Hristov, V.; Keating, B.; Lee, D. H.; Levenson, L.; Mason, P.; Matsumoto, T.; Matsuura, S.; Nam, U. W.; Renbarger, T.; Sullivan, I.; Tsumura, K.; Wada, T.

    2010-07-01

    Ultraviolet emission from the first generation of stars in the Universe ionized the intergalactic medium in a process which was completed by z ~ 6; the wavelength of these photons has been redshifted by (1 + z) into the near infrared today and can be measured using instruments situated above the Earth's atmosphere. First flying in February 2009, the Cosmic Infrared Background ExpeRiment (CIBER) comprises four instruments housed in a single reusable sounding rocket borne payload. CIBER will measure spatial anisotropies in the extragalactic IR background caused by cosmological structure from the epoch of reionization using two broadband imaging instruments, make a detailed characterization of the spectral shape of the IR background using a low resolution spectrometer, and measure the absolute brightness of the Zodiacal light foreground with a high resolution spectrometer in each of our six science fields. The scientific motivation for CIBER and details of its first and second flight instrumentation will be discussed. First flight results on the color of the zodiacal light around 1 μm and plans for the future will also be presented.

  19. Dual-wavelength diode laser with electrically adjustable wavelength distance at 785  nm.

    Science.gov (United States)

    Sumpf, Bernd; Kabitzke, Julia; Fricke, Jörg; Ressel, Peter; Müller, André; Maiwald, Martin; Tränkle, Günther

    2016-08-15

    A spectrally adjustable monolithic dual-wavelength diode laser at 785 nm as an excitation light source for shifted excitation Raman difference spectroscopy (SERDS) is presented. The spectral distance between the two excitation wavelengths can be electrically adjusted between 0 and 2.0 nm using implemented heater elements above the distributed Bragg reflector (DBR) gratings. Output powers up to 180 mW at a temperature of 25°C were measured. The spectral width is smaller than 13 pm, limited by the spectrum analyzer. The device is well-suited for Raman spectroscopy, and the flexible spectral distance allows a target-specific adjustment of the excitation light source for shifted excitation Raman difference spectroscopy (SERDS).

  20. The Long Wavelength Array

    Science.gov (United States)

    Taylor, G. B.

    2006-08-01

    The Long Wavelength Array (LWA) will be a new, open, user-oriented astronomical instrument operating in the poorly explored window from 20-80 MHz at arcsecond level resolution and mJy level sensitivity. Key science drivers include (1) acceleration, propagation, and turbulence in the ISM, including the space-distribution and spectrum of Galactic cosmic rays, supernova remnants, and pulsars; (2) the high redshift universe, including the most distant radio galaxies and clusters - tools for understanding the earliest black holes and the cosmological evolution of Dark Matter and Dark Energy; (3) planetary, solar, and space science, including space weather prediction and extra-solar planet searches; and (4) the radio transient universe: including the known (e.g., SNe, GRBs) and the unknown. Because the LWA will explore one of the last and least investigated regions of the spectrum, the potential for new discoveries, including new classes of physical phenomena, is high, and there is a strong synergy with exciting new X-ray and Gamma-ray measurements, e.g. for cosmic ray acceleration, transients, and galaxy clusters. Operated by the University of New Mexico on behalf of the South West Consortium (SWC) the LWA will also provide a unique training ground for the next generation of radio astronomers. Students may also put skills learned on the LWA to work in computer science, electrical engineering, and the communications industry, among others. The development of the LWA will follow a phased build, which benefits from lessons learned at each phase. Four university-based Scientific Testing and Evaluation (ST&E) teams with different areas of concentration (1. High resolution imaging and particle acceleration; 2. Wide field imaging and large scale structures; 3. Ionosphere, and 4. RFI suppression and transient detection) will provide the feedback needed to assure that science objectives are met as the build develops. Currently in its first year of construction funding, the LWA

  1. UVIS G280 Wavelength Calibration

    Science.gov (United States)

    Bushouse, Howard

    2009-07-01

    Wavelength calibration of the UVIS G280 grism will be established using observations of the Wolf Rayet star WR14. Accompanying direct exposures will provide wavelength zeropoints for dispersed exposures. The calibrations will be obtained at the central position of each CCD chip and at the center of the UVIS field. No additional field-dependent variations will be obtained.

  2. Free-space wavelength-multiplexed optical scanner.

    Science.gov (United States)

    Yaqoob, Z; Rizvi, A A; Riza, N A

    2001-12-10

    A wavelength-multiplexed optical scanning scheme is proposed for deflecting a free-space optical beam by selection of the wavelength of the light incident on a wavelength-dispersive optical element. With fast tunable lasers or optical filters, this scanner features microsecond domain scan setting speeds and large- diameter apertures of several centimeters or more for subdegree angular scans. Analysis performed indicates an optimum scan range for a given diffraction order and grating period. Limitations include beam-spreading effects based on the varying scanner aperture sizes and the instantaneous information bandwidth of the data-carrying laser beam.

  3. The Cosmic Infrared Background Experiment (CIBER): The Wide-field Imagers

    Science.gov (United States)

    Bock, J.; Sullivan, I.; Arai, T.; Battle, J.; Cooray, A.; Hristov, V.; Keating, B.; Kim, M. G.; Lam, A. C.; Lee, D. H.; Levenson, L. R.; Mason, P.; Matsumoto, T.; Matsuura, S.; Mitchell-Wynne, K.; Nam, U. W.; Renbarger, T.; Smidt, J.; Suzuki, K.; Tsumura, K.; Wada, T.; Zemcov, M.

    2013-08-01

    We have developed and characterized an imaging instrument to measure the spatial properties of the diffuse near-infrared extragalactic background light (EBL) in a search for fluctuations from z > 6 galaxies during the epoch of reionization. The instrument is part of the Cosmic Infrared Background Experiment (CIBER), designed to observe the EBL above Earth's atmosphere during a suborbital sounding rocket flight. The imaging instrument incorporates a 2° × 2° field of view to measure fluctuations over the predicted peak of the spatial power spectrum at 10 arcmin, and 7'' × 7'' pixels, to remove lower redshift galaxies to a depth sufficient to reduce the low-redshift galaxy clustering foreground below instrumental sensitivity. The imaging instrument employs two cameras with Δλ/λ ~ 0.5 bandpasses centered at 1.1 μm and 1.6 μm to spectrally discriminate reionization extragalactic background fluctuations from local foreground fluctuations. CIBER operates at wavelengths where the electromagnetic spectrum of the reionization extragalactic background is thought to peak, and complements fluctuation measurements by AKARI and Spitzer at longer wavelengths. We have characterized the instrument in the laboratory, including measurements of the sensitivity, flat-field response, stray light performance, and noise properties. Several modifications were made to the instrument following a first flight in 2009 February. The instrument performed to specifications in three subsequent flights, and the scientific data are now being analyzed.

  4. DESCRIBING DISPERSION OF LIGHT THROUGH A GLASS PRISM AS IT IS BASED ON MAPPING RELATIONSHIP BETWEEN VISIBLE WAVELENGTH AND COLOR%基于可见光波长颜色映射关系的棱镜色散现象写真

    Institute of Scientific and Technical Information of China (English)

    徐代升; 甘亮勤; 杜旭日

    2013-01-01

      探讨了用计算机真实再现棱镜色散现象的技术。以Dan Bruton的工作为基础,依据MATLAB颜色显示法,建立了可见光波长与 RGB 的映射关系,实现了可见光波长颜色在显示屏上的再现。运用所建立映射关系,结合白光通过棱镜之光路追迹,真实再现了棱镜色散现象,实现了棱镜色散现象写真。进一步将上述方法运用于白光入射两个完全一样、相互倒置摆放棱镜实验现象仿真,得到了各色光从红到紫平行于入射白光依次从第二块棱镜出射的正确实验现象。%The technique of how to truly show dispersion of light through a glass prism on computer is discussed. Based on the work of Dan Bruton and the display method of color in MATLAB, the mapping relationship between visible wavelength and data in colormap matrix of MATLAB was erected Therefore the corresponding color of the visible wavelength can be displayed truly on computer screen. According to the mapping relationship, to describe prism dispersion as it is was realized by ray tracing. Furtherly used this method to show the experimental result of the incident white light through the pair of prisms which were made of same glass and placed inversely, the verity is that the refracted color rays from red to violet come out from the second prism parallel to the incident white light.

  5. Background and introduction

    DEFF Research Database (Denmark)

    2012-01-01

    by their particular theories and conceptual analyses, data, tools, and best practices, with a focus on respectively costs and benefits of facilities and services, alignment of corporate and public real estate to organizational objectives and organisational performance, and relationship management in market...... background information to understand the following chapters in this book. Research limitations: The chapter is mainly based on the experience and knowledge of the editors. It does not include original research but provides an introductory overview of the book. Originality/value: This chapter takes a look...... behind the scenes of the making of this book and connects contributions from three different fields - FM, CREM, and B2B marketing - to shed more light on the concept of added value of FM. It serves as an introduction to the research presented in the other chapters in this book....

  6. Super sub-wavelength patterns in photon coincidence detection

    Science.gov (United States)

    Liu, Ruifeng; Zhang, Pei; Zhou, Yu; Gao, Hong; Li, Fuli

    2014-02-01

    High-precision measurements implemented with light are desired in all fields of science. However, light acts as a wave, and the Rayleigh criterion in classical optics yields a diffraction limit that prevents obtaining a resolution smaller than the wavelength. Sub-wavelength interference has potential application in lithography because it beats the classical Rayleigh resolution limit. Here, we carefully study second-order correlation theory to establish the physics behind sub-wavelength interference in photon coincidence detection. A Young's double slit experiment with pseudo-thermal light is performed to test the second-order correlation pattern. The results show that when two point detectors are scanned in different ways, super sub-wavelength interference patterns can be obtained. We then provide a theoretical explanation for this surprising result, and demonstrate that this explanation is also suitable for the results found for entangled light. Furthermore, we discuss the limitations of these types of super sub-wavelength interference patterns in quantum lithography.

  7. The Cosmic Background Explorer Satellite

    Science.gov (United States)

    Mather, J.; Kelsall, T.

    1980-01-01

    The Cosmic Background Explorer (COBE) satellite, planned for launch in 1985, will measure the diffuse infrared and microwave radiation of the universe over the entire wavelength range from a few microns to 1.3 cm. It will include three instruments: a set of microwave isotropy radiometers at 23, 31, 53, and 90 GHz, an interferometer spectrometer from 1 to 100/cm, and a filter photometer from 1 to 300 microns. The COBE satellite is designed to reach the sensitivity limits set by foreground sources such as the interstellar and interplanetary dust, starlight, and galactic synchrotron radiation, so that a diffuse residual radiation may be interpreted unambiguously as extragalactic

  8. The COBE Diffuse Infrared Background Experiment search for thecosmic infrared background. I. Limits and detections

    Energy Technology Data Exchange (ETDEWEB)

    Hauser, M.G.; Arendt, R.G.; Kelsall, T.; Dwek, E.; Odegard, N.; Weiland, J.L.; Freudenreich, H.T.; Reach, W.T.; Silverberg, R.F.; Moseley, S.H.; Pei, Y.C.; Lubin, P.; Mather, J.C.; Shafer, R.A.; Smoot,G.F.; Weiss, R.; Wilkinson, D.T.; Wright, E.L.

    1998-01-06

    The Diffuse Infrared Background Experiment (DIRBE) on the Cosmic Background Explorer (COBE) spacecraft was designed primarily to conduct a systematic search for an isotropic cosmic infrared background (CIB) in 10 photometric bands from 1.25 to 240 mu m. The results of that search are presented here. Conservative limits on the CIB are obtained from the minimum observed brightness in all-sky maps at each wavelength, with the faintest limits in the DIRBE spectral range being at 3.5 mu m(nu l nu<64 nW m-2 sr-1, 95 percent confidence level) and at 240 mu m (nu l nu < 28 nW m-1 sr-1, 95 percent confidence level). The bright foregrounds from interplanetary dust scattering and emission, stars, and interstellar dust emission are the principal impediments to the DIRBE measurements of the CIB. These foregrounds have been modeled and removed from the sky maps. Assessment of the random and systematic uncertainties in the residuals and tests for isotropy show that only the 140 and 240 mum data provide candidate detections of the CIB. The residuals and their uncertainties provide CIB upper limits more restrictive than the dark sky limits at wavelengths from 1.25 to 100 mu m. No plausible solar system or Galactic source of the observed 140 and 240 mu m residuals can be identified, leading to the conclusion that the CIB has been detected at levels of nu l nu = 25 +- 7 and 14 +- 3 nW m-2 sr-1 at 140 and 240 mu m, respectively. The integrated energy from 140 to 240 mu m, 10.3 nW m-2sr-1, is about twice the integrated optical light from the galaxies in the Hubble Deep Field, suggesting that star formation might have been heavily enshrouded by dust at high redshift. The detections and upper limits reported here provide new constraints on models of the history of energy-releasing processes and dust production since the decoupling of the cosmic microwave background from matter.

  9. Light Emitting Diodes (LEDs)

    Science.gov (United States)

    1997-01-01

    A special lighting technology was developed for space-based commercial plant growth research on NASA's Space Shuttle. Surgeons have used this technology to treat brain cancer on Earth, in two successful operations. The treatment technique, called Photodynamic Therapy, requires the surgeon to use tiny, pinhead-size Light Emitting Diodes (LEDs) (a source that releases long wavelengths of light ) to activate light-sensitive, tumor-treating drugs. 'A young woman operated on in May 1999 has fully recovered with no complications and no evidence of the tumor coming back,' said Dr. Harry Whelan, a pediatric neurologist at the Medical Hospital of Wisconsin in Milwaukee. Laser light has been used for this type of surgery in the past, but the LED light illuminates through all nearby tissues, reaching parts of a tumor that shorter wavelengths of laser light carnot. The new probe is safer because the longer wavelengths of light are cooler than the shorter wavelengths of laser light, making the LED less likely to injure normal brain tissue near the tumor. It can be used for hours at a time while still remaining cool to the touch. The LED light source is compact, about the size of a briefcase, and can be purchased for a fraction of the cost of a laser. The LEDs, developed and managed by NASA's Marshall Space Flight Center, have been used on seven Space Shuttle flights inside the Microgravity Astroculture Facility. This technology has also been successfully used to further commercial research in crop growth.

  10. Change of Primary Cosmic Radiation Nuclear Conposition in the Energy Range $10^{15} - 10^{17}$ eV as a Result of the Interaction with the Interstellar Cold Background of Light Particles

    CERN Document Server

    Barnaveli, T T; Khaldeeva, I V

    2003-01-01

    In this paper the updated arguments in favor of a simple model, explaining from the united positions all peculiarities of the Extensive Air Shower (EAS) hadron E_h(E_0) (and muon E_mu(E_0)) component energy fluxes dependence on the primary particle energy E_0 in the primary energy region 10^{15} - 10^{17} eV are represented. These peculiarities have shapes of consequent distinct deeps of a widths dE_h/E_h of the order of 0.2 and of relative amplitudes dL/L of the order of {0.1 - 1.0}, and are difficult to be explained via known astrophysical mechanisms of particle generation and acceleration. In the basis of the model lies the destruction of the Primary Cosmic Radiation (PCR) nuclei on some monochromatic background of interstellar space, consisting of the light particles of the mass in the area of 36 eV (maybe the component of a dark matter). The destruction thresholds of PCR different nuclear components correspond to the peculiarities of E_h(E_0). In this work the results of the recent treatment of large sta...

  11. AWG Filter for Wavelength Interrogator

    Science.gov (United States)

    Black, Richard J. (Inventor); Costa, Joannes M. (Inventor); Faridian, Fereydoun (Inventor); Moslehi, Behzad (Inventor); Sotoudeh, Vahid (Inventor)

    2015-01-01

    A wavelength interrogator is coupled to a circulator which couples optical energy from a broadband source to an optical fiber having a plurality of sensors, each sensor reflecting optical energy at a unique wavelength and directing the reflected optical energy to an AWG. The AWG has a detector coupled to each output, and the reflected optical energy from each grating is coupled to the skirt edge response of the AWG such that the adjacent channel responses form a complementary pair response. The complementary pair response is used to convert an AWG skirt response to a wavelength.

  12. Topology optimised wavelength dependent splitters

    DEFF Research Database (Denmark)

    Hede, K. K.; Burgos Leon, J.; Frandsen, Lars Hagedorn

    A photonic crystal wavelength dependent splitter has been constructed by utilising topology optimisation1. The splitter has been fabricated in a silicon-on-insulator material (Fig. 1). The topology optimised wavelength dependent splitter demonstrates promising 3D FDTD simulation results....... This complex photonic crystal structure is very sensitive against small fabrication variations from the expected topology optimised design. A wavelength dependent splitter is an important basic building block for high-performance nanophotonic circuits. 1J. S. Jensen and O. Sigmund, App. Phys. Lett. 84, 2022...

  13. Topology optimised wavelength dependent splitters

    DEFF Research Database (Denmark)

    Hede, K. K.; Burgos Leon, J.; Frandsen, Lars Hagedorn;

    A photonic crystal wavelength dependent splitter has been constructed by utilising topology optimisation1. The splitter has been fabricated in a silicon-on-insulator material (Fig. 1). The topology optimised wavelength dependent splitter demonstrates promising 3D FDTD simulation results....... This complex photonic crystal structure is very sensitive against small fabrication variations from the expected topology optimised design. A wavelength dependent splitter is an important basic building block for high-performance nanophotonic circuits. 1J. S. Jensen and O. Sigmund, App. Phys. Lett. 84, 2022...

  14. Wavelength dimensioning for wavelength-routed WDM satellite network

    Institute of Scientific and Technical Information of China (English)

    Liu Zhe; Guo Wei; Deng Changlin; Hu Weisheng

    2016-01-01

    Internet and broadband applications driven by data traffic demand have become key dri-vers for satellite constellations. The key technology to satisfy the high capacity requirements between satellites is optical satellite networks by means of wavelength division multiplexing inter-satellite links (ISLs) with wavelength routing (WDM-OSN). Due to the limited optical amplifier bandwidth onboard the satellite, it is important to minimize the wavelength requirements to provi-sion requests. However, ISLs should be dynamically established and deleted for each satellite according to its visible satellites. Furthermore, different link assignments will result in different topologies, hence yielding different routings and wavelength assignments. Thus, a perfect match model-based link assignment scheme (LAS-PMM) is proposed to design an appropriate topology such that shorter path could be routed and less wavelengths could be assigned for each ISL along the path. Finally, simulation results show that in comparison to the regular Manhattan street net-work (MSN) topology, wavelength requirements and average end-to-end delay based on the topol-ogy generated by LAS-PMM could be reduced by 24.8%and 12.4%, respectively.

  15. A Novel Approach for Improving Communication by Wavelength Utilization

    Directory of Open Access Journals (Sweden)

    Shrangesh Dahat

    2012-06-01

    Full Text Available Optical networks using wavelength division multiplexing (WDM technology modulate multiple channels over a single fiber. The most common architecture utilized for establishing communication in WDM optical networks is wavelength routing, where the communication between a source and a destination node is performed by setting up optical channels between them, called light-paths from the network perspective. In optical WDM networks, transmission of information along optical lines is advantageous since it has high transmission capacity, scalability, feasibility and also high reliability. But since large amount of information is being carried, any problem during transmission can lead to severe damage to the data being carried. In this paper, we propose to develop a routing and wavelength utilization algorithm which considers two constraints for selecting the best path. The two constraints are based on the available free load and the number of wavelength used in the link. Based on these constraints, two cost functions on load and wavelength are determined, which yields a combined cost function. For each pair of source and destination, the path with the minimum combined cost function is selected as the primary path for data transmission, allocating the sufficient wavelength. This study paper proposes a RWU algorithm for the problem of establishing the set of efficient light paths for a given set of connection requests. The effectiveness of the proposed RWU algorithm is demonstrated by simulation. This study divides the routing and wavelength allocation process in two step problem with a goal of minimizing Number of wavelength channel and number of wavelength conversion required. This algorithm thus provides a reliable path for the data transmission.

  16. Spin and wavelength multiplexed nonlinear metasurface holography

    Science.gov (United States)

    Ye, Weimin; Zeuner, Franziska; Li, Xin; Reineke, Bernhard; He, Shan; Qiu, Cheng-Wei; Liu, Juan; Wang, Yongtian; Zhang, Shuang; Zentgraf, Thomas

    2016-06-01

    Metasurfaces, as the ultrathin version of metamaterials, have caught growing attention due to their superior capability in controlling the phase, amplitude and polarization states of light. Among various types of metasurfaces, geometric metasurface that encodes a geometric or Pancharatnam-Berry phase into the orientation angle of the constituent meta-atoms has shown great potential in controlling light in both linear and nonlinear optical regimes. The robust and dispersionless nature of the geometric phase simplifies the wave manipulation tremendously. Benefitting from the continuous phase control, metasurface holography has exhibited advantages over conventional depth controlled holography with discretized phase levels. Here we report on spin and wavelength multiplexed nonlinear metasurface holography, which allows construction of multiple target holographic images carried independently by the fundamental and harmonic generation waves of different spins. The nonlinear holograms provide independent, nondispersive and crosstalk-free post-selective channels for holographic multiplexing and multidimensional optical data storages, anti-counterfeiting, and optical encryption.

  17. Coupling light to periodic nanostructures

    NARCIS (Netherlands)

    Driessen, Eduard Frans Clemens

    2009-01-01

    This thesis describes coupling of light to periodic structures. A material is patterned with a regular pattern on a length scale comparable to the wavelength of light. With these structures, light can be manipulated very precisely. The structures find applications in semiconductor lasers, light emit

  18. Infrared clutter measurements of marine backgrounds

    NARCIS (Netherlands)

    Schwering, Piet B.

    1991-01-01

    Observations in the infrared wavelength band between 8 and 12 μm of sea backgrounds have been recorded with a CCIR compatible imager for a large number of sea states (0 - 6). Recordings took place in coastal areas as well as on open seas. The behavior of clutter in the infrared data was analyzed in

  19. A new synchronization scheme based on time division multiplexing and wavelength division multiplexing technology for practical quantum key distribution system

    Institute of Scientific and Technical Information of China (English)

    Zhong Ping-Ping; Zhang Hua-Ni; Wang Jin-Dong; Qin Xiao-Juan; Wei zheng-Jun; Chen Shuai; Liu Song-Hao

    2011-01-01

    Three clock synchronization schemes for a quantum key distribution system are compared experimentally through the outdoor fibre and the interaction physical model of the the clock signal and the the quantum signal in the quantum key distribution system is analysed to propose a new synchronization scheme based on time division multiplexing and wavelength division multiplexing technology to reduce quantum bits error rates under some transmission rate conditions.The proposed synchronization scheme can not only completely eliminate noise photons from the bright background light of the the clock signal, but also suppress the fibre nonlinear crosstalk.

  20. Improvement of the dynamic range using background subtraction in single shot wide-field optical coherence tomography

    Science.gov (United States)

    Anna, Tulsi; Singh Mehta, Dalip; Sato, Manabu

    2015-12-01

    We investigated on the signal in single shot wide-field optical coherence tomographic (SS-WF-OCT) system to improve the dynamic range (DR). The SS-WF-OCT system is based on two-dimensional (2D) polarization Michelson interferometer and superluminescent diode (center wavelength of 842.5 nm) as light source. Two π-phase-shifted interferograms were acquired simultaneously using a single CCD camera and after subtraction, the en-face OCT image (area (x) 4.0 mm × (y) 4.3 mm) is obtained using 2D Hilbert transform. The OCT signal including incoherent background noises was analyzed. To improve the DR, background noise subtraction has been introduced and its measurement process is presented. This method is valuable during the background noise is stable. Using the scattering samples, such as, grind metal and polymer sponge with background subtraction algorithm, a significant reduction in background noise and improvement in the DR was demonstrated .

  1. Measurement of Cerenkov Radiation Induced by the Gamma-Rays of Co-60 Therapy Units Using Wavelength Shifting Fiber

    OpenAIRE

    Kyoung Won Jang; Sang Hun Shin; Seon Geun Kim; Jae Seok Kim; Wook Jae Yoo; Young Hoon Ji; Bongsoo Lee

    2014-01-01

    In this study, a wavelength shifting fiber that shifts ultra-violet and blue light to green light was employed as a sensor probe of a fiber-optic Cerenkov radiation sensor. In order to characterize Cerenkov radiation generated in the developed wavelength shifting fiber and a plastic optical fiber, spectra and intensities of Cerenkov radiation were measured with a spectrometer. The spectral peaks of light outputs from the wavelength shifting fiber and the plastic optical fiber were measured at...

  2. A stable and inexpensive wavelength reference for precise wavelength calibration of radial velocity spectrographs

    Science.gov (United States)

    Feger, Tobias; Ireland, Michael J.; Bento, Joao; Bacigalupo, Carlos

    2014-08-01

    We present a stable, inexpensive wavelength reference, based on a white-light interferometer for the use on current and future (arrays of) diffraction-limited radial velocity (RV) spectrographs. The primary aim of using an interferometer is to obtain a dense sinusoidal wavelength reference with spectral coverage between 450-650 nm. Its basic setup consists of an unbalanced fiber Mach-Zehnder interferometer (FMZI) that creates an interference pattern in the spectral domain due to superposition of phase delayed light, set by a fixed optical path-length difference (OPD). To achieve long-term stability, the interferometer is actively locked to a stable atomic line. The system operates in closed-loop using a thermo-optic modulator as the phase feedback component. We conducted stability measurements by superimposing the wavelength reference with thorium-argon (ThAr) emission lines and found the differential RMS shift to be ~5 m s-1 within 30 minute bins in an experiment lasting 5 hours.

  3. Random-phase metasurfaces at optical wavelengths

    Science.gov (United States)

    Pors, Anders; Ding, Fei; Chen, Yiting; Radko, Ilya P.; Bozhevolnyi, Sergey I.

    2016-06-01

    Random-phase metasurfaces, in which the constituents scatter light with random phases, have the property that an incident plane wave will diffusely scatter, hereby leading to a complex far-field response that is most suitably described by statistical means. In this work, we present and exemplify the statistical description of the far-field response, particularly highlighting how the response for polarised and unpolarised light might be alike or different depending on the correlation of scattering phases for two orthogonal polarisations. By utilizing gap plasmon-based metasurfaces, consisting of an optically thick gold film overlaid by a subwavelength thin glass spacer and an array of gold nanobricks, we design and realize random-phase metasurfaces at a wavelength of 800 nm. Optical characterisation of the fabricated samples convincingly demonstrates the diffuse scattering of reflected light, with statistics obeying the theoretical predictions. We foresee the use of random-phase metasurfaces for camouflage applications and as high-quality reference structures in dark-field microscopy, while the control of the statistics for polarised and unpolarised light might find usage in security applications. Finally, by incorporating a certain correlation between scattering by neighbouring metasurface constituents new types of functionalities can be realised, such as a Lambertian reflector.

  4. Build up and integration of the rocket-borne Cosmic Infrared Background ExpeRiment-2

    Science.gov (United States)

    Lanz, Alicia E.; Arai, Toshiaki; Battle, John; Bock, James; Cooray, Asantha R.; Hristov, Viktor; Kojima, Tomoya; Korngut, Phillip; Lee, Dae Hee; Mason, Peter; Matsumoto, Toshio; Matsuura, Shuji; Nguyen, Chi; Shirahata, Mai; Takahashi, Aoi; Tsumurai, Kohji; Wada, Takehiko; Wang, Shiang-Yu; Zemcov, Michael B.

    2017-01-01

    The Cosmic Infrared Background ExpeRiment, CIBER-2, is a near-infrared rocket-borne instrument designed to conduct comprehensive multi-band measurements of extragalactic background light anisotropy on arcsecond to degree angular scales. Recent measurements of the near-infrared Extragalactic Background Light (EBL) anisotropy find excess spatial power above the level predicted by known galaxy populations at large angular scales. CIBER-2 is designed to make measurements of the EBL anisotropy with the sensitivity, spectral range, and spectral resolution required to disentangle the contributions to the EBL from various sources throughout cosmic history.CIBER-2 consists of a 28.5 cm Cassegrain telescope assembly, imaging optics, and cryogenics mounted aboard a sounding rocket. Two dichroic beam-splitters spectrally subdivide the incident radiation into three optical paths, which are further subdivided in two wavelength bands per path, for a total of six observational wavelength bands that span the optical to the near-infrared and produce six 1.2 by 2.4 degree images recorded by three 2048 x 2048 HAWAII-2RG detector arrays. A small portion of each detector is also dedicated to absolute spectrophotometric imaging provided by a linear-variable filter. The instrument has several novel cryogenic mechanisms, a cryogenically-cooled pop-up baffle that extends during observations to provide radiative shielding and an electromagnetic cold shutter. We provide an overview of the instrument and current integration.

  5. Green Light for Nocturnally Migrating Birds

    Directory of Open Access Journals (Sweden)

    Hanneke Poot

    2008-12-01

    Laboratory experiments have shown the magnetic compass to be wavelength dependent: migratory birds require light from the blue-green part of the spectrum for magnetic compass orientation, whereas red light (visible long-wavelength disrupts magnetic orientation. We designed a field study to test if and how changing light color influenced migrating birds under field conditions. We found that nocturnally migrating birds were disoriented and attracted by red and white light (containing visible long-wavelength radiation, whereas they were clearly less disoriented by blue and green light (containing less or no visible long-wavelength radiation. This was especially the case on overcast nights. Our results clearly open perspective for the development of bird-friendly artificial lighting by manipulating wavelength characteristics. Preliminary results with an experimentally developed bird-friendly light source on an offshore platform are promising. What needs to be investigated is the impact of bird-friendly light on other organisms than birds.

  6. The Cosmic Infrared Background Experiment

    Science.gov (United States)

    Bock, James; Battle, J.; Cooray, A.; Hristov, V.; Kawada, M.; Keating, B.; Lee, D.; Matsumoto, T.; Matsuura, S.; Nam, U.; Renbarger, T.; Sullivan, I.; Tsumura, K.; Wada, T.; Zemcov, M.

    2009-01-01

    We are developing the Cosmic Infrared Background ExpeRiment (CIBER) to search for signatures of first-light galaxy emission in the extragalactic background. The first generation of stars produce characteristic signatures in the near-infrared extragalactic background, including a redshifted Ly-cutoff feature and a characteristic fluctuation power spectrum, that may be detectable with a specialized instrument. CIBER consists of two wide-field cameras to measure the fluctuation power spectrum, and a low-resolution and a narrow-band spectrometer to measure the absolute background. The cameras will search for fluctuations on angular scales from 7 arcseconds to 2 degrees, where the first-light galaxy spatial power spectrum peaks. The cameras have the necessary combination of sensitivity, wide field of view, spatial resolution, and multiple bands to make a definitive measurement. CIBER will determine if the fluctuations reported by Spitzer arise from first-light galaxies. The cameras observe in a single wide field of view, eliminating systematic errors associated with mosaicing. Two bands are chosen to maximize the first-light signal contrast, at 1.6 um near the expected spectral maximum, and at 1.0 um; the combination is a powerful discriminant against fluctuations arising from local sources. We will observe regions of the sky surveyed by Spitzer and Akari. The low-resolution spectrometer will search for the redshifted Lyman cutoff feature in the 0.7 - 1.8 um spectral region. The narrow-band spectrometer will measure the absolute Zodiacal brightness using the scattered 854.2 nm Ca II Fraunhofer line. The spectrometers will test if reports of a diffuse extragalactic background in the 1 - 2 um band continues into the optical, or is caused by an under estimation of the Zodiacal foreground. We report performance of the assembled and tested instrument as we prepare for a first sounding rocket flight in early 2009. CIBER is funded by the NASA/APRA sub-orbital program.

  7. Planarian Phototactic Assay Reveals Differential Behavioral Responses Based on Wavelength

    OpenAIRE

    Paskin, Taylor R.; John Jellies; Jessica Bacher; Wendy S Beane

    2014-01-01

    Planarians are free-living aquatic flatworms that possess a well-documented photophobic response to light. With a true central nervous system and simple cerebral eyes (ocelli), planarians are an emerging model for regenerative eye research. However, comparatively little is known about the physiology of their photoreception or how their behavior is affected by various wavelengths. Most phototactic studies have examined planarian behavior using white light. Here, we describe a novel planarian b...

  8. Transfer of orbital angular momentum through sub-wavelength waveguides.

    Science.gov (United States)

    Wang, Yanqin; Ma, Xiaoliang; Pu, Mingbo; Li, Xiong; Huang, Cheng; Pan, Wenbo; Zhao, Bo; Cui, Jianhua; Luo, Xiangang

    2015-02-01

    Data capacity of optical communication is achieving its limit owing to the non-linear effect of optical fiber. As an effective alternative, light carrying orbital angular momentum can greatly increase the capacity for its unprecedented degree of freedom. We demonstrate the propagation of orbital angular momentum with topological charge of 1 and 2 in plasmonic circular waveguide with sub-wavelength diameter with little propagation loss of 2.73 dB/μm, which has never been observed in optical fibers with sub-wavelength diameter. We also confirm that lights carrying orbital angular momentum can be maintained in sharp bended sub-wavelength waveguide. This plasmonic waveguide may serve as a key component in on-chip systems involving OAM.

  9. Ultraviolet Background Radiation

    Science.gov (United States)

    Henry, R. C.; Murthy, J.

    1993-12-01

    The UVX experiment was carried on the Space Shuttle Columbia between 1986 January 12 and 19 (STS-61C). Several ultraviolet spectrometers were used to obtain measurements of the diffuse ultraviolet background at 8 locations in the sky. We have reanalysed the UVX measurements of the surface brightness of the diffuse ultraviolet background above b = 40 using the dust-scattering model of Onaka & Kodaira (1991), which explicitly takes into account the variation of the source function with galactic longitude. The range of allowed values of interstellar grain albedoJa, and scattering asymmetry parameter g, is considerably expanded over those of a previous analysis. The new chi square probability contours come close to, but do not include, the values of a and g found for the interstellar grains by Witt et al. (1992) using the Ultraviolet Imaging Telescope (UIT) on the Astro mission. If we hypothesize in additon to the dust-scattered light an extragalactic component, of 300 1 100 photons cm-2 s-1 sr-1 A-1, attenuated by a cosecant b law, the new reduction of the UVX data gives complete consistency with the Witt et al. determination of the optical parameters of the grains in the ultraviolet. This work was supported by United States Air Force Contract F19628-93-K-0004, and by National Aeronautics and Space Administration grant NASA NAG5-619. We are grateful for the encouragement of Dr. Stephan Price, and we thank Dr. L. Danly for information. Onaka, T., & Kodaira, K. 1991, ApJ, 379, 532 Witt, A. N., Petersohn, J. K., Bohlin, R. C., O'Connell, R. W., Roberts, M. S., Smith, A. M., & Stecher, T. P. 1992, ApJ, 395, L5

  10. Wavelength and polarization affect phototaxis of the Asian citrus psyllid

    Science.gov (United States)

    The Asian citrus psyllid, D. citri, is a primary pest for citrus production due to its status as a vector of the citrus disease, huanglongbing. We investigated phototactic behavior of D. citri to evaluate effects of light of specific wavelength or polarization using a horizontal bioassay arena. Wave...

  11. Unveiling the cosmic history of light

    Science.gov (United States)

    Desai, Abhishek; Ajello, Marco; Hartmann, Dieter; Sharan Paliya, Vaidehi; Finke, Justin; Omodei, Nicola; Dominguez, Alberto; Helgason, Kári; Meyer, Manuel

    2017-08-01

    The extragalactic background light (EBL) is the collective emission of all the stars and galaxies over the history of the universe. The most efficient method to study the EBL is through the imprint it leaves via photon-photon annihilation in the spectra of distant gamma-ray sources. Here we present a combined analysis of gamma-ray data from GRBs and blazars detected by Fermi Large Area Telescope. This analysis allows us to probe the EBL up to much higher redshifts (z>4) and over a larger wavelength range. The details of this work and its implications will be discussed.

  12. Tuning of the excitation wavelength in Eu(3+)-aminophenyl based polyfluorinated β-diketonate complexes: a red-emitting Eu(3+)-complex encapsulated in a silica/polymer hybrid material excited by blue light.

    Science.gov (United States)

    Usha Gangan, T V; Reddy, M L P

    2015-09-28

    based Eu(3+)-β-diketonate complex is an interesting red-emitting material excited by blue light and therefore may find potential applications in the fields of biological and materials science.

  13. Planar Lenses at Visible Wavelengths

    CERN Document Server

    Khorasaninejad, Mohammadreza; Devlin, Robert C; Oh, Jaewon; Zhu, Alexander Y; Capasso, Federico

    2016-01-01

    Sub-wavelength resolution imaging requires high numerical aperture (NA) lenses, which are bulky and expensive. Metasurfaces allow the miniaturization of conventional refractive optics into planar structures. We show that high-aspect-ratio titanium dioxide metasurfaces can be fabricated and designed as meta-lenses with NA = 0.8. Diffraction-limited focusing is demonstrated at wavelengths of 405 nm, 532 nm, and 660 nm with corresponding efficiencies of 86%, 73%, and 66%. The meta-lenses can resolve nanoscale features separated by sub-wavelength distances and provide magnification as high as 170x with image qualities comparable to a state-of-the-art commercial objective. Our results firmly establish that meta-lenses can have widespread applications in laser-based microscopy, imaging, and spectroscopy.

  14. Wavelength Filters in Fibre Optics

    CERN Document Server

    Venghaus, Herbert

    2006-01-01

    Wavelength filters constitute an essential element of fibre-optic networks. This book gives a comprehensive account of the principles and applications of such filters, including their technological realisation. After an introductory chapter on wavelength division multiplexing in current and future fibre optic networks follows a detailed treatment of the phase characteristics of wavelength filters, a factor frequently neglected but of significant importance at high bit rates. Subsequent chapters cover three-dimensional reflection of gratings, arrayed waveguide gratings, fibre Bragg gratings, Fabry-Perot filters, dielectric multilayer filters, ring filters, and interleavers. The book explains the relevant performance parameters, the particular advantages and shortcomings of the various concepts and components, and the preferred applications. It also includes in-depth information on the characteristics of both commercially available devices and those still at the R&D stage. All chapters are authored by inter...

  15. Optical fiber read-out for liquid argon scintillation light

    CERN Document Server

    Csáthy, J Janicskó; Kratz, J; Schönert, S; Wiesinger, Ch

    2016-01-01

    In this paper we describe the performance of a light detector for Ar scintillation light made of wavelength-shifting (WLS) fibers connected to Silicon-Photomultipliers (SiPM). The setup was conceived to be used as anti-Compton veto for high purity germanium (HPGe) detectors operated directly in liquid Argon (LAr). Background suppression efficiencies for different radioactive sources were measured in a test cryostat with about 800 kg LAr. This work was part of the R\\&D effort for the GERDA experiment.

  16. Measuring the wavelength-dependent divergence of transmission through sub-wavelength hole-arrays by spectral imaging

    NARCIS (Netherlands)

    Docter, M.W.; Young, I.T.; Piciu, O.M.; Bossche, A.; Alkemade, P.F.A.; Van den Berg, P.M.; Garini, Y.

    2006-01-01

    We present a study on the far-field patterns of light transmitted through sub-wavelength metallic hole-arrays. Spectral imaging measurements are used here on hole arrays for the first time. It provides both spatial and spectral information of the transmission in far-field. The visibility of the imag

  17. Wavelength standards in the infrared

    CERN Document Server

    Rao, KN

    2012-01-01

    Wavelength Standards in the Infrared is a compilation of wavelength standards suitable for use with high-resolution infrared spectrographs, including both emission and absorption standards. The book presents atomic line emission standards of argon, krypton, neon, and xenon. These atomic line emission standards are from the deliberations of Commission 14 of the International Astronomical Union, which is the recognized authority for such standards. The text also explains the techniques employed in determining spectral positions in the infrared. One of the techniques used includes the grating con

  18. Harnessing spectral property of dual wavelength white LED to improve vertical scanning interferometry.

    Science.gov (United States)

    Chong, Wee Keat; Li, Xiang; Soh, Yeng Chai

    2013-07-01

    Unlike a conventional white light source that emits a continuous and broad spectrum of light, the dual wavelength white light emitting diode (LED) generates white light by mixing blue and yellow lights, so there are two distinct peaks in its intensity spectrum. Prior works had shown that the spectral property of the dual wavelength white LED can affect the vertical scanning interferometry negatively if the spectral effects are not compensated. In this paper, we shall examine this issue by modeling the spectral property and variation of the dual wavelength white LED, followed by investigating its effects on the interference signal of vertical scanning interferometry. Instead of compensating the spectral effects of the dual wavelength white LED, we harness its spectral property to improve the performance of a phase-based height reconstruction algorithm in vertical scanning interferometry.

  19. Multi-wavelength characterization of carbonaceous aerosol

    Science.gov (United States)

    Massabò, Dario; Caponi, Lorenzo; Chiara Bove, Maria; Piazzalunga, Andrea; Valli, Gianluigi; Vecchi, Roberta; Prati, Paolo

    2014-05-01

    Carbonaceous aerosol is a major component of the urban PM. It mainly consists of organic carbon (OC) and elemental carbon (EC) although a minor fraction of carbonate carbon could be also present. Elemental carbon is mainly found in the finer PM fractions (PM2.5 and PM1) and it is strongly light absorbing. When determined by optical methods, it is usually called black carbon (BC). The two quantities, EC and BC, even if both related to the refractory components of carbonaceous aerosols, do not exactly define the same PM component (Bond and Bergstrom, 2006; and references therein). Moreover, another fraction of light-absorbing carbon exists which is not black and it is generally called brown carbon (Andreae and Gelencsér, 2006). We introduce a simple, fully automatic, multi-wavelength and non-destructive optical system, actually a Multi-Wavelength Absorbance Analyzer, MWAA, to measure off-line the light absorption in Particulate Matter (PM) collected on filters and hence to derive the black and brown carbon content in the PM This gives the opportunity to measure in the same sample the concentration of total PM by gravimetric analysis, black and brown carbon, metals by, for instance, X Ray Fluorescence, and finally ions by Ion Chromatography. Up to 16 samples can be analyzed in sequence and in an automatic and controlled way within a few hours. The filter absorbance measured by MWAA was successfully validated both against a MAAP, Multi Angle Absorption Photometer (Petzold and Schönlinner, 2004), and the polar photometer of the University of Milan. The measurement of sample absorbance at three wavelengths gives the possibility to apportion different sources of carbonaceous PM, for instance fossil fuels and wood combustion. This can be done following the so called "aethalometer method" (Sandradewi et al., 2008;) but with some significant upgrades that will be discussed together the results of field campaigns in rural and urban sites. Andreae, M.O, and Gelencsér, A

  20. Determination of the Average Native Background and the Light-Induced EPR Signals and their Variation in the Teeth Enamel Based on Large-Scale Survey of the Population.

    Science.gov (United States)

    Ivannikov, Alexander I; Khailov, Artem M; Orlenko, Sergey P; Skvortsov, Valeri G; Stepanenko, Valeri F; Zhumadilov, Kassym Sh; Williams, Benjamin B; Flood, Ann B; Swartz, Harold M

    2016-12-01

    The aim of the study is to determine the average intensity and variation of the native background signal amplitude (NSA) and of the solar light-induced signal amplitude (LSA) in electron paramagnetic resonance (EPR) spectra of tooth enamel for different kinds of teeth and different groups of people. These values are necessary for determination of the intensity of the radiation-induced signal amplitude (RSA) by subtraction of the expected NSA and LSA from the total signal amplitude measured in L-band for in vivo EPR dosimetry. Variation of these signals should be taken into account when estimating the uncertainty of the estimated RSA. A new analysis of several hundred EPR spectra that were measured earlier at X-band in a large-scale examination of the population of the Central Russia was performed. Based on this analysis, the average values and the variation (standard deviation, SD) of the amplitude of the NSA for the teeth from different positions, as well as LSA in outer enamel of the front teeth for different population groups, were determined. To convert data acquired at X-band to values corresponding to the conditions of measurement at L-band, the experimental dependencies of the intensities of the RSA, LSA and NSA on the m.w. power, measured at both X and L-band, were analysed. For the two central upper incisors, which are mainly used in in vivo dosimetry, the mean LSA annual rate induced only in the outer side enamel and its variation were obtained as 10 ± 2 (SD = 8) mGy y(-1), the same for X- and L-bands (results are presented as the mean ± error of mean). Mean NSA in enamel and its variation for the upper incisors was calculated at 2.0 ± 0.2 (SD = 0.5) Gy, relative to the calibrated RSA dose-response to gamma radiation measured under non-power saturation conditions at X-band. Assuming the same value for L-band under non-power saturating conditions, then for in vivo measurements at L-band at 25 mW (power saturation conditions), a mean NSA and its

  1. Optical effects of exposing intact human lenses to ultraviolet radiation and visible light

    DEFF Research Database (Denmark)

    Kessel, Line; Eskildsen, Lars; Lundeman, Jesper Holm

    2011-01-01

    BACKGROUND: The human lens is continuously exposed to high levels of light. Ultraviolet radiation is believed to play a causative role in the development of cataract. In vivo, however, the lens is mainly exposed to visible light and the ageing lens absorbs a great part of the short wavelength...... region of incoming visible light. The aim of the present study was to examine the optical effects on human lenses of short wavelength visible light and ultraviolet radiation. METHODS: Naturally aged human donor lenses were irradiated with UVA (355 nm), violet (400 and 405 nm) and green (532 nm) lasers....... The effect of irradiation was evaluated qualitatively by photography and quantitatively by measuring the direct transmission before and after irradiation. Furthermore, the effect of pulsed and continuous laser systems was compared as was the effect of short, intermediate and prolonged exposures. RESULTS...

  2. Optical effects of exposing intact human lenses to ultraviolet radiation and visible light

    DEFF Research Database (Denmark)

    Kessel, Line; Eskildsen, Lars Baunsgaard; Lundeman, Jesper Holm

    2011-01-01

    ABSTRACT: BACKGROUND: The human lens is continuously exposed to high levels of light. Ultraviolet radiation is believed to play a causative role in the development of cataract. In vivo, however, the lens is mainly exposed to visible light and the ageing lens absorbs a great part of the short...... wavelength region of incoming visible light. The aim of the present study was to examine the optical effects on human lenses of short wavelength visible light and ultraviolet radiation. METHODS: Naturally aged human donor lenses were irradiated with UVA (355 nm), violet (400 and 405 nm) and green (532 nm......) lasers. The effect of irradiation was evaluated qualitatively by photography and quantitatively by measuring the direct transmission before and after irradiation. Furthermore, the effect of pulsed and continuous laser systems was compared as was the effect of short, intermediate and prolonged exposures...

  3. Observations of the Near-Infrared Spectrum of the Zodiacal Light with CIBER

    CERN Document Server

    Tsumura, K; Bock, J; Cooray, A; Hristov, V; Keating, B; Lee, D H; Levenson, L R; Mason, P; Matsumoto, T; Matsuura, S; Nam, U W; Renbarger, T; Sullivan, I; Suzuki, K; Wada, T; Zemcov, M

    2010-01-01

    Interplanetary dust (IPD) scatters solar radiation which results in the zodiacal light that dominates the celestial diffuse brightness at optical and near-infrared wavelengths. Both asteroid collisions and cometary ejections produce the IPD, but the relative contribution from these two sources is still unknown. The Low Resolution Spectrometer (LRS) onboard the Cosmic Infrared Background Experiment (CIBER) observed the astrophysical sky spectrum between 750 and 2100 nm over a wide range of ecliptic latitude. The resulting zodiacal light spectrum is redder than the solar spectrum, and shows a broad absorption feature, previously unreported, at approximately 900 nm, suggesting the existence of silicates in the IPD material. The spectral shape of the zodiacal light is isotropic at all ecliptic latitudes within the measurement error. The zodiacal light spectrum, including the extended wavelength range to 2500 nm using IRTS data, is qualitatively similar to the reflectance of S-type asteroids. This result can be ex...

  4. Wavelength-shifted Cherenkov radiators

    Science.gov (United States)

    Krider, E. P.; Jacobson, V. L.; Pifer, A. E.; Polakos, P. A.; Kurz, R. J.

    1976-01-01

    The scintillation and Cherenkov responses of plastic Cherenkov radiators containing different wavelength-shifting fluors in varying concentrations have been studied in beams of low energy protons and pions. For cosmic ray applications, where large Cherenkov to scintillation ratios are desired, the optimum fluor concentrations are 0.000025 by weight or less.

  5. Light scattering reviews 8 radiative transfer and light scattering

    CERN Document Server

    Kokhanovsky, Alexander A

    2013-01-01

    Light scattering review (vol 8) is aimed at the presentation of recent advances in radiative transfer and light scattering optics. The topics to be covered include: scattering of light by irregularly shaped particles suspended in atmosphere (dust, ice crystals), light scattering by particles much larger as compared the wavelength of incident radiation, atmospheric radiative forcing, astrophysical radiative transfer, radiative transfer and optical imaging in biological media, radiative transfer of polarized light, numerical aspects of radiative transfer.

  6. Resolving The Moth at Millimeter Wavelengths

    CERN Document Server

    Ricarte, Angelo; Hughes, A Meredith; Duchêne, Gaspard; Williams, Jonathan P; Andrews, Sean M; Wilner, David J

    2013-01-01

    HD 61005, also known as "The Moth," is one of only a handful of debris disks that exhibit swept-back "wings" thought to be caused by interaction with the ambient interstellar medium (ISM). We present 1.3 mm Submillimeter Array (SMA) observations of the debris disk around HD 61005 at a spatial resolution of 1.9 arcsec that resolve the emission from large grains for the first time. The disk exhibits a double-peaked morphology at millimeter wavelengths, consistent with an optically thin ring viewed close to edge-on. To investigate the disk structure and the properties of the dust grains we simultaneously model the spatially resolved 1.3 mm visibilities and the unresolved spectral energy distribution. The temperatures indicated by the SED are consistent with expected temperatures for grains close to the blowout size located at radii commensurate with the millimeter and scattered light data. We also perform a visibility-domain analysis of the spatial distribution of millimeter-wavelength flux, incorporating constr...

  7. Sinusoidal wavelength-scanning interferometer with a superluminescent diode for step-profile measurement.

    Science.gov (United States)

    Sasaki, O; Murata, N; Suzuki, T

    2000-09-01

    In sinusoidal phase-modulating interferometry an optical path length (OPD) larger than a wavelength is measured by detection of sinusoidal phase-modulation amplitude Z(b) of the interference signal that is produced by sinusoidal scanning of the wavelength of a light source. A light source with a large scanning width of wavelength is created by use of a superluminescent laser diode for the error in the measured value obtained by Z(b) to be smaller than half of the central wavelength. In this situation the measured value can be combined with a fractional value of the OPD obtained from the conventional phase of the interference signal. A sinusoidal wavelength-scanning interferometer with the light source measures an OPD over a few tens of micrometers with a high accuracy of a few nanometers.

  8. Continuous-wave optical parametric oscillation tunable up to 8 μm wavelength

    Science.gov (United States)

    Breunig, Ingo; Fürst, Josef Urban; Hanka, Kevin; Buse, Karsten

    2017-06-01

    We demonstrate the first cw OPO emitting mid-infrared light at wavelengths up to 8 μm. This device is based on a 3.5-mm-diameter whispering gallery resonator made of silver gallium selenide (AgGaSe2) pumped by a compact distributed feedback laser diode emitting light at 1.57 μm wavelength. Phase-matching is achieved for a c-cut resonator disk pumped with extraordinarily polarized light at this wavelength. The oscillation thresholds are in the mW region, while the output power ranges from 10 to 800 μW. Wavelength tuning is achieved via changing the radial mode number of the pump wave and by changing the resonator temperature. Simulations predict that whispering gallery OPOs based on AgGaSe2 with diameters around 2 mm can generate idler waves exceeding 10 μm wavelength.

  9. Underdense radiation sources: Moving towards longer wavelengths

    Energy Technology Data Exchange (ETDEWEB)

    Back, C.A.; Kilkenny, J.D. [General Atomics, San Diego, California (United States); Seely, J.F.; Weaver, J.L. [Naval Research Laboratory, Washington, DC (United States); Feldman, U. [Artep Inc., Ellicott City, MD (United States); Tommasini, R.; Glendinning, S.G.; Chung, H.K.; Rosen, M.; Lee, R.W.; Scott, H.A. [Lawrence Livermore National Laboratory, California (United States); Tillack, M. [U. C. San Diego, La Jolla, CA (United States)

    2006-06-15

    Underdense radiation sources have been developed to provide efficient laboratory multi-keV radiation sources for radiography and radiation hardening studies. In these plasmas laser absorption by inverse Bremsstrahlung leads to high x-ray conversion efficiency because of efficient ionization of the low density aerogel or gas targets. Now we performing experiments in the soft x-ray energy regime where the atomic physics models are much more complicated. In recent experiments at the NIKE laser, we have irradiated a Ti-doped SiO{sub 2} aerogel with up to 1650 J of 248 nm wavelength light. The absolute Ti L-shell emission in the 200-800 eV range is measured with a diagnostic that uses a transmission grating coupled to Si photodiodes. We will give an overview of the temporally-resolved absolutely calibrated spectra obtained over a range of conditions. (authors)

  10. Development of in situ, at-wavelength metrology for soft x-ray nano-focusing

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Sheng Sam; Yashchuk, Valeriy V.; Goldberg, Kenneth A.; Celestre, Richard; McKinney, Wayne R.; Morrison, Gregory Y.; Warwick, Tony; Padmore, Howard A.

    2010-09-19

    At the Advanced Light Source (ALS), we are developing broadly applicable, high-accuracy, in situ, at-wavelength wavefront slope measurement techniques for Kirkpatrick-Baez (KB) mirror nano-focusing. We describe here details of the metrology beamline endstation, the at-wavelength tests, and an original alignment method that have already allowed us to precisely set a bendable KB mirror to achieve a FWHM focused spot size of ~;;120 nm, at 1-nm soft x-ray wavelength.

  11. Monolithic Michelson Interferometer as ultra stable wavelength reference

    Science.gov (United States)

    Wan, Xiaoke; Ge, Jian

    2010-07-01

    Ultra-stable Monolithic Michelson interferometer can be an ideal reference for highprecision applications such as RV measurement in planet searching and orbit study. The advantages include wide wavelength range, simple sinusoidal spectral format, and high optical efficiency. In this paper, we report that a monolithic Michelson interferometers has been in-house developed with minimized thermal sensitivity with compensation tuning. With a scanning white light interferometer, the thermal sensitivity is measured ~ 6x10-7/°C at 550 nm and it decreases to zero near 1000 nm. We expect the wideband wavelength reference source to be stabilized better than 0.3 m/s for RV experiments

  12. Three Dimensional Imaging with Multiple Wavelength Speckle Interferometry

    Energy Technology Data Exchange (ETDEWEB)

    Bernacki, Bruce E.; Cannon, Bret D.; Schiffern, John T.; Mendoza, Albert

    2014-05-28

    We present the design, modeling, construction, and results of a three-dimensional imager based upon multiple-wavelength speckle interferometry. A surface under test is illuminated with tunable laser light in a Michelson interferometer configuration while a speckled image is acquired at each laser frequency step. The resulting hypercube is Fourier transformed in the frequency dimension and the beat frequencies that result map the relative offsets of surface features. Synthetic wavelengths resulting from the laser tuning can probe features ranging from 18 microns to hundreds of millimeters. Three dimensional images will be presented along with modeling results.

  13. Wavelength dependence in photosynthesis of porous silicon dot

    Science.gov (United States)

    Cheah, K. W.; Choy, C. H.

    1994-09-01

    Porous silicon dot was fabricated by laser induced etching of single crystal silicon wafer immersed in hydrofluoric solution. The result shows that there is strong photo-chemical reaction on the laser irradiated silicon surface. Various incident wavelengths have been used to fabricate the porous silicon dots. It is found that there is a significant shift in photoluminescence peak when using infra-red light as etching wavelength. We proposed that there are two possible mechanisms responsible for the shift; one is electronic and the other is photo-chemical.

  14. The Wavelength-Dispersive Spectrometer and Its Proposed Use in the Analytical Electron Microscope

    Science.gov (United States)

    Goldstein, Joseph I.; Lyman, Charles E.; Williams, David B.

    1989-01-01

    The Analytical Electron Microscope (AEM) equipped with a wavelength-dispersive spectrometer (WDS) should have the ability to resolve peaks which normally overlap in the spectra from an energy-dispersive spectrometer (EDS). With a WDS it should also be possible to measure lower concentrations of elements in thin foils due to the increased peak-to-background ratio compared with EDS. The WDS will measure X-ray from the light elements (4 less than Z less than 1O) more effectively. This paper addresses the possibility of interfacing a compact WDS with a focussing circle of approximately 4 cm to a modem AEM with a high-brightness (field emission) source of electrons.

  15. Lethal photosensitization of wound-associated microbes using indocyanine green and near-infrared light

    DEFF Research Database (Denmark)

    Omar, Ghada Said Mohammed; Wilson, Michael; Nair, Sean P.

    2008-01-01

    Background: The increase in resistance to antibiotics among disease-causing bacteria necessitates the development of alternative antimicrobial approaches such as the use of light-activated antimicrobial agents (LAAAs). Light of an appropriate wavelength activates the LAAA to produce cytotoxic...... species which can then cause bacterial cell death via loss of membrane integrity, lipid peroxidation, the inactivation of essential enzymes, and/or exertion of mutagenic effects due to DNA modification. In this study, the effect of the LAAA indocyanine green excited with high or low intensity light (808...

  16. Light in man's environment.

    Science.gov (United States)

    Marshall, J

    2016-02-01

    Light in the form of solar radiation influenced early civilisations and resulted in the independent development of a number of sun-worshipping dieties. These were of particular importance as hunter gatherers transformed into settled agricultural societies. All artificial light sources were synonymous with fire, and early civilisations began to expand their visual day by burning brands, oil, and candles. Fire-based light sources extended for thousands of years and were still present in the era of gas lighting. Light meant fire risk. The advent of incandescent bulbs and the era of electric lighting really only expanded in the early part of the twentieth century. Fluorescent lighting became available in the 1940s, and today the drive for low energy has resulted in a plethora of novel light sources-in particular, light-emitting diodes (LEDs). Evolution governed the development of the eye in relation to roughly 12 h of light gradually changing to 12 h of darkness. Today almost daylight levels can be achieved abruptly at the flick of a switch. Many studies have demonstrated the spectral dependence of eye health, with the retinal hazard zone associated with wavelengths in the blue, peaking at 441 nm- many of today's low-energy sources peak in this region. Given the increased longevity and artificial light sources emitting at biologically unfriendly wavelengths, attention has to be directed towards light in man's environment as a risk factor in age-related ocular diseases.

  17. Mode-selective wavelength conversion based on four-wave mixing in a multimode silicon waveguide

    DEFF Research Database (Denmark)

    Ding, Yunhong; Xu, Jing; Ou, Haiyan;

    2014-01-01

    We propose and demonstrate all-optical mode-selective wavelength conversion in a silicon waveguide. The mode-selective wavelength conversion relies on strong four-wave mixing when pump and signal light are on the same spatial mode, while weak four-wave mixing is obtained between different modes due...

  18. The Cosmic Infrared Background Experiment: Flight Characterization Of The Ciber Narrow Band Spectrometer.

    Science.gov (United States)

    Levenson, Louis R.; Battle, J.; Bock, J. J.; Cooray, A.; Hristov, V.; Keating, B.; Lee, D.; Mason, P.; Matsumoto, T.; Matsuura, S.; Nam, U. W.; Renbarger, T.; Sullivan, I.; Suzuki, K.; Wada, T.; Zemcov, M.

    2011-01-01

    Subtraction of the Zodiacal light foreground is the dominant source of uncertainty in absolute photometric measurements of the extra-galactic background at near-infrared to optical wavelengths. The second flight of the Cosmic Infrared Background ExpeRiment (CIBER) occurred on July 10th, 2010. CIBER is a NASA sounding rocket experiment carrying four co-aligned instruments including two imaging telescopes with wide passbands centered at 1 and 1.6 microns, respectively, as well as a low resolution spectrometer and a narrow-band spectrometer. THE CIBER spectrometers are absolutely calibrated in collaboration with NIST. The narrow-band spectrometer filter is centered on the Ca II solar Fraunhofer line at 854.2 nm and is designed to measure the equivalent width of the solar line reflected by the interplanetary dust in order to obtain an absolute measurement of the Zodiacal contribution to the infrared sky at that wavelength. In conjunction with measured low resolution spectrum from 700 to 1900 nm, this will provide an accurate independent check of the DIRBE Zodiacal light models. Here we describe the NBS instrument, calibration and in-flight characterization.

  19. Characterization of Neutron Backgrounds for Direct Dark Matter Searches

    Science.gov (United States)

    Sweany, Melinda Dominique

    Direct dark matter experiments generally cannot distinguish between nuclear recoils caused by Weakly Interacting Massive Particles (WIMPs) and those caused by neutron backgrounds. It is therefore crucial that all sources of neutron background are well understood and accounted for when claiming a discovery or reporting limits on the WIMP-nucleon cross section. One source of neutrons that is not well understood results from cosmogenic muon interactions in the material surrounding a detector. The Neutron Multiplicity Meter in the Soudan cavern is a gadolinium-doped water Cherenkov detector capable of detecting high multiplicity neutron showers resulting from fast neutrons incident on a lead target. This measurement is the first such measurement obtained without a liquid scintillator detector medium; muon and neutron spallation is media-dependent, and because neutron shield technology for dark matter detectors is moving towards water, this is an important measurement. The integrated fast neutron flux in the Soudan cavern is reported as a linear function of the power, alpha, of the neutron angular distribution with the zenith angle: F = 4.8x10-9 +/- 3.5x10-10 + (5.4x10-10 +/- 1.5x10-10)alpha. Technological studies of neutron detection with gadolinium-doped water are also reported here. The neutron detection efficiency of a cylindrical 3.5 kL detector is measured at 70% for neutrons in the center of the detector. In addition, other improvements to water Cherenkov technology are explored, namely the addition of water-soluble wavelength-shifting chemicals. The wavelength-shifting chemical 4-Methylumbelliferone has been shown here to increase the measured light output of Cherenkov radiation resulting from neutron capture showers by a factor of 1.7.

  20. Background sources at PEP

    Energy Technology Data Exchange (ETDEWEB)

    Lynch, H.; Schwitters, R.F.; Toner, W.T.

    1988-01-01

    Important sources of background for PEP experiments are studied. Background particles originate from high-energy electrons and positrons which have been lost from stable orbits, ..gamma..-rays emitted by the primary beams through bremsstrahlung in the residual gas, and synchrotron radiation x-rays. The effect of these processes on the beam lifetime are calculated and estimates of background rates at the interaction region are given. Recommendations for the PEP design, aimed at minimizing background are presented. 7 figs., 4 tabs.

  1. Review of short wavelength lasers

    Energy Technology Data Exchange (ETDEWEB)

    Hagelstein, P.L.

    1985-03-18

    There has recently been a substantial amount of research devoted to the development of short wavelength amplifiers and lasers. A number of experimental results have been published wherein the observation of significant gain has been claimed on transitions in the EUV and soft x-ray regimes. The present review is intended to discuss the main approaches to the creation of population inversions and laser media in the short wavelength regime, and hopefully aid workers in the field by helping to provide access to a growing literature. The approaches to pumping EUV and soft x-ray lasers are discussed according to inversion mechanism. The approaches may be divided into roughly seven categories, including collisional excitation pumping, recombination pumping, direct photoionization and photoexcitation pumping, metastable state storage plus optical pumping, charge exchange pumping, and finally, the extension of free electron laser techniques into the EUV and soft x-ray regimes. 250 references.

  2. Wavelength-multiplexed entanglement distribution

    Science.gov (United States)

    Lim, Han Chuen; Yoshizawa, Akio; Tsuchida, Hidemi; Kikuchi, Kazuro

    2010-08-01

    The realization of an entanglement distribution optical fiber network connecting multiple parties would permit implementation of many information security applications such as entanglement-based quantum key distribution and quantum secret sharing. However, due to material absorption and scattering in optical fiber, photons that are the carriers of quantum entanglement experience loss during propagation and the overall photon arrival rate can be very low in such a network. One way to increase photon arrival rate is to make full use of the available transmission bandwidth of optical fiber and this is achievable via wavelength-multiplexing. We review our recent work on wavelength-multiplexed entanglement distribution and discuss system design considerations from a telecommunication engineering perspective.

  3. Damaging effects of visible light. Comprehensive progress report

    Energy Technology Data Exchange (ETDEWEB)

    None

    1981-01-01

    Research progress is reported on studies of retinal light damage. A myriad of variables effect the production of light damage. These include age, prior light history, body temperature, vitamin A status, intensity, wavelength and duration of light. The intensity-duration function and the age function have been studied in detail in rats. Studies have been begun on the wavelength variable. (ACR)

  4. A New Wavelength Selective Photoreceiver

    Institute of Scientific and Technical Information of China (English)

    LIU Kai; HUANG Yongqing; REN Xiaomin; LI Jianxin; GUO Wei

    2000-01-01

    A new kind of wavelength selective photoreceiver is proposed. It was constructed by a Fabry-Perot (F-P) etalon filter and a resonant cavity enhanced (RCE) photodetector. The photoreceiver′s spectral response is determined by the F-P etalon filter with a FWHM of less than 4 nm. Moreover, with such a photoreceiver, the transmission loss of the F-P etalon filter can be compensated to some extent. And this will benefit its applications.

  5. Building Background Knowledge

    Science.gov (United States)

    Neuman, Susan B.; Kaefer, Tanya; Pinkham, Ashley

    2014-01-01

    This article make a case for the importance of background knowledge in children's comprehension. It suggests that differences in background knowledge may account for differences in understanding text for low- and middle-income children. It then describes strategies for building background knowledge in the age of common core standards.

  6. How to distinguish elastically scattered light from Stokes shifted light for solid-state lighting?

    NARCIS (Netherlands)

    Meretska, M. L.; Lagendijk, A.; Thyrrestrup, H.; Mosk, A. P.; IJzerman, W. L.; Vos, W.L.

    2016-01-01

    We have studied the transport of light through phosphor diff user plates that are used in commercial solid-state lighting modules (Fortimo). These polymer plates contain YAG:Ce+3 phosphor particles that both elastically scatter and Stokes shift light in the visible wavelength range (400-700 nm). We

  7. Towards the Long Wavelength Array

    Science.gov (United States)

    Kassim, N. E.; Erickson, W. C.

    2008-08-01

    Nearly three decades ago, the Very Large Array (VLA) opened the cm-wavelength radio sky to high-dynamic range imaging. By developing and exploiting new techniques to mitigate ionospheric phase fluctuations, the VLA 74 MHz system is providing the first sub-arcminute resolution view of the meter-wavelength radio universe. This technical innovation has inspired an emerging suite of much more powerful low-frequency instruments, including the Long Wavelength Array (LWA). The LWA, with its great collecting area (approaching one square kilometer at 20 MHz) and long baselines (up to 400 km), will surpass, by up to 2--3 orders of magnitude, the imaging power of any previous low-frequency interferometer. LWA science goals include Cosmic Evolution, the Acceleration of Relativistic Particles, Plasma Astrophysics, and Ionospheric & Space Weather Science. Because it will explore one of the last and most poorly investigated regions of the spectrum, the potential for unexpected new discoveries is high. For more on the LWA, see http://lwa.unm.edu. The LWA project is led by the University of New Mexico, and includes the Naval Research Laboratory, Applied Research Laboratories of U. Texas, Los Alamos National Laboratory, Virginia Tech, and U. Iowa, with cooperation from the National Radio Astronomy Observatory.

  8. The Cosmic Infrared Background Experiment

    CERN Document Server

    Bock, J; Cooray, A R; Kawada, M; Keating, B; Lange, A; Lee, D H; Matsumoto, T; Matsuura, S; Pak, S; Renbarger, T; Sullivan, I; Tsumura, K; Wada, T; Watabe, T; Bock, James; Battle, John; Cooray, Asantha; Kawada, Mitsunobu; Keating, Brian; Lange, Andrew; Lee, Dae-Hea; Matsumoto, Toshio; Matsuura, Shuji; Pak, Soojong; Renbarger, Tom; Sullivan, Ian; Tsumura, Kohji; Wada, Takehiko; Watabe, Toyoki

    2006-01-01

    We are developing a rocket-borne instrument (the Cosmic Infrared Background ExpeRiment, or CIBER) to search for signatures of primordial galaxy formation in the cosmic near-infrared extra-galactic background. CIBER consists of a wide-field two-color camera, a low-resolution absolute spectrometer, and a high-resolution narrow-band imaging spectrometer. The cameras will search for spatial fluctuations in the background on angular scales from 7 arcseconds to 2 degrees over a range of angular scales poorly covered by previous experiments. CIBER will determine if the fluctuations reported by the IRTS arise from first-light galaxies or have a local origin. In a short rocket flight CIBER has sensitivity to probe fluctuations 100 times fainter than IRTS/DIRBE. By jointly observing regions of the sky studied by Spitzer and ASTRO-F, CIBER will build a multi-color view of the near-infrared background, accurately assessing the contribution of local (z = 1-3) galaxies to the observed background fluctuations, allowing a de...

  9. Wavelength Phase-shift Dual-diffraction Interferometer

    Directory of Open Access Journals (Sweden)

    Geng-An Jiang

    2014-08-01

    Full Text Available This paper presents a wavelength phase-shift dual-diffraction interferometer for the displacement measurement. The measurement system is divided into two parts. On the part of the optical configuration, the grating displacement is converted into the phase of the light based on Doppler effect. By means of the dual-diffraction design, the phase sensitivity corresponding to the grating shift is enhanced. The second part is the phase analysis system. Because of the unbalance optical path design and the modulated wavelength, the wavelength phase-shift technique is developed for analyzing the phase variation resulted from the grating displacement. The experimental results demonstrate that this system has good stability and repeatability.

  10. In-vacuum long-wavelength macromolecular crystallography.

    Science.gov (United States)

    Wagner, Armin; Duman, Ramona; Henderson, Keith; Mykhaylyk, Vitaliy

    2016-03-01

    Structure solution based on the weak anomalous signal from native (protein and DNA) crystals is increasingly being attempted as part of synchrotron experiments. Maximizing the measurable anomalous signal by collecting diffraction data at longer wavelengths presents a series of technical challenges caused by the increased absorption of X-rays and larger diffraction angles. A new beamline at Diamond Light Source has been built specifically for collecting data at wavelengths beyond the capability of other synchrotron macromolecular crystallography beamlines. Here, the theoretical considerations in support of the long-wavelength beamline are outlined and the in-vacuum design of the endstation is discussed, as well as other hardware features aimed at enhancing the accuracy of the diffraction data. The first commissioning results, representing the first in-vacuum protein structure solution, demonstrate the promising potential of the beamline.

  11. Photonic digital-to-analog conversion based on wavelength multiplexing

    Science.gov (United States)

    Yang, Shuna; Hu, Miao; Chi, Hao; Li, Qiliang

    2017-10-01

    A novel photonic digital-to-analog conversion (PDAC) scheme, which is based on optical intensity weighting and multiplexing/summing of different wavelengths, is proposed. The employment of wavelength multiplexing in the system, which conducts the function of modulated light intensity summation, greatly simplifies the system complexity and improves the conversion speed/accuracy limited by large-area photo-detectors and associated electronics. A 4-bit PDAC with a conversion speed of 10 GS/s demonstrates the feasibility of the proposed scheme. In addition, the performance degradation induced by the limited extinction ratios of the applied electro-optic modulators, the synchronization errors among different wavelength channels, and the bit resolutions of the built system is also discussed.

  12. Fabrication of broadband antireflective sub-wavelength structures on fluorescent SiC

    DEFF Research Database (Denmark)

    Ou, Yiyu; Jokubavicus, V.; Kaiser, M.

    2013-01-01

    Surface nanocones on 6H-SiC have been developed and demonstrated as an effective method of enhancing the light extraction efficiency from fluorescent SiC layers. The surface reflectance, measured from the opposite direction of light emission, over a broad bandwidth range is significantly suppress...... from 20.5% to 1.0 % after introducing the sub-wavelength structures. An omnidirectional light harvesting enhancement (>91%), is also achieved which promotes fluorescent SiC as a good candidate of wavelength converter for white light-emitting diodes....

  13. Determination of the optimal amount of scattering in a wavelength conversion plate for white LEDs.

    Science.gov (United States)

    Ryckaert, Jana; Leyre, Sven; Hanselaer, Peter; Meuret, Youri

    2015-11-30

    Luminescent materials are widely used in white LEDs to convert part of the blue LED light into light with a longer wavelength, resulting in white light when both colors are well mixed. One way to integrate the luminescent material in the LED package is to deposit a thin luminescent layer on a planar carrier or disperse luminescent particles in the carrier material and then position the resulting wavelength conversion plate above one or more LEDs. It is very important that these wavelength conversion plates have the right properties to ensure homogeneous white light with a high efficiency and desired correlated color temperature (CCT). Key properties are the absorption and emission spectrum and the scattering and absorption coefficients. These properties strongly influence the color of the resulting light, but also the efficiency and the angular uniformity. This work describes an extensive study of the effect of the scattering and absorption coefficients in terms of the desired CCT. A computationally efficient extended Adding-Doubling method is used for the simulation of the light distribution and conversion in the planar wavelength conversion element. Ultimately an optimal combination with a high efficiency and low angular color deviation is desired. Different systems are investigated and optimal coefficients are found. With these findings a more targeted approach can be used in the manufacturing of wavelength conversion plates for white LEDs. The addition of scatterers or non-scattering luminescent particles can be used to obtain optimal scattering properties of the wavelength conversion plate.

  14. Do shorter wavelengths improve contrast in optical mammography?

    Science.gov (United States)

    Taroni, P.; Pifferi, A.; Torricelli, A.; Spinelli, L.; Danesini, G. M.; Cubeddu, R.

    2004-04-01

    The detection of tumours with time-resolved transmittance imaging relies essentially on blood absorption. Previous theoretical and phantom studies have shown that both contrast and spatial resolution of optical images are affected by the optical properties of the background medium, and high absorption and scattering are generally beneficial. Based on these observations, wavelengths shorter than presently used (680-780 nm) could be profitable for optical mammography. A study was thus performed analysing time-resolved transmittance images at 637, 656, 683 and 785 nm obtained from 26 patients bearing 16 tumours and 15 cysts. The optical contrast proved to increase upon decreasing wavelengths for the detection of cancers in late-gated intensity images, with higher gain in contrast for lesions of smaller size (decrease in contrast with wavelength was observed in scattering images.

  15. Enhanced Plasmonic Wavelength Selective Infrared Emission Combined with Microheater

    Directory of Open Access Journals (Sweden)

    Hiroki Ishihara

    2017-09-01

    Full Text Available The indirect wavelength selective thermal emitter that we have proposed is constructed using a new microheater, demonstrating the enhancement of the emission peak generated by the surface plasmon polariton. The thermal isolation is improved using a 2 μm-thick Si membrane having 3.6 and 5.4 mm outer diameter. The emission at around the wavelength of the absorption band of CO2 gas is enhanced. The absorption signal increases, confirming the suitability for gas sensing. Against input power, the intensity at the peak wavelength shows a steeper increasing ratio than the background intensity. The microheater with higher thermal isolation gives larger peak intensity and its increasing ratio against the input power.

  16. Magic wavelengths for the $5s-18s$ transition in rubidium

    CERN Document Server

    Goldschmidt, E A; Koller, S B; Wyllie, R; Brown, R C; Porto, J V; Safronova, U I; Safronova, M S

    2015-01-01

    Magic wavelengths, for which there is no differential ac Stark shift for the ground and excited state of the atom, allow trapping of excited Rydberg atoms without broadening the optical transition. This is an important tool for implementing quantum gates and other quantum information protocols with Rydberg atoms, and reliable theoretical methods to find such magic wavelengths are thus extremely useful. We use a high-precision all-order method to calculate magic wavelengths for the $5s-18s$ transition of rubidium, and compare the calculation to experiment by measuring the light shift for atoms held in an optical dipole trap at a range of wavelengths near a calculated magic value.

  17. Green Light Induces Shade Avoidance Symptoms1[C][W][OA

    Science.gov (United States)

    Zhang, Tingting; Maruhnich, Stefanie A.; Folta, Kevin M.

    2011-01-01

    Light quality and quantity affect plant adaptation to changing light conditions. Certain wavelengths in the visible and near-visible spectrum are known to have discrete effects on plant growth and development, and the effects of red, far-red, blue, and ultraviolet light have been well described. In this report, an effect of green light on Arabidopsis (Arabidopsis thaliana) rosette architecture is demonstrated using a narrow-bandwidth light-emitting diode-based lighting system. When green light was added to a background of constant red and blue light, plants exhibited elongation of petioles and upward leaf reorientation, symptoms consistent with those observed in a shaded light environment. The same green light-induced phenotypes were also observed in phytochrome (phy) and cryptochrome (cry) mutant backgrounds. To explore the molecular mechanism underlying the green light-induced response, the accumulation of shade-induced transcripts was measured in response to enriched green light environments. Transcripts that have been demonstrated to increase in abundance under far-red-induced shade avoidance conditions either decrease or exhibit no change when green light is added. However, normal far-red light-associated transcript accumulation patterns are observed in cryptochrome mutants grown with supplemental green light, indicating that the green-absorbing form of cryptochrome is the photoreceptor active in limiting the green light induction of shade-associated transcripts. These results indicate that shade symptoms can be induced by the addition of green light and that cryptochrome receptors and an unknown light sensor participate in acclimation to the enriched green environment. PMID:21852417

  18. Selection of Quantum Dot Wavelengths for Biomedical Assays and Imaging

    Directory of Open Access Journals (Sweden)

    Yong Taik Lim

    2003-01-01

    Full Text Available Fluorescent semiconductor nanocrystals (quantum dots [QDs] are hypothesized to be excellent contrast agents for biomedical assays and imaging. A unique property of QDs is that their absorbance increases with increasing separation between excitation and emission wavelengths. Much of the enthusiasm for using QDs in vivo stems from this property, since photon yield should be proportional to the integral of the broadband absorption. In this study, we demonstrate that tissue scatter and absorbance can sometimes offset increasing QD absorption at bluer wavelengths, and counteract this potential advantage. By using a previously validated mathematical model, we explored the effects of tissue absorbance, tissue scatter, wavelength dependence of the scatter, water-to- hemoglobin ratio, and tissue thickness on QD performance. We conclude that when embedded in biological fluids and tissues, QD excitation wavelengths will often be quite constrained, and that excitation and emission wavelengths should be selected carefully based on the particular application. Based on our results, we produced near-infrared QDs optimized for imaging surface vasculature with white light excitation and a silicon CCD camera, and used them to image the coronary vasculature in vivo. Taken together, our data should prove useful in designing fluorescent QD contrast agents optimized for specific biomedical applications.

  19. THE COSMIC INFRARED BACKGROUND EXPERIMENT (CIBER): THE WIDE-FIELD IMAGERS

    Energy Technology Data Exchange (ETDEWEB)

    Bock, J.; Battle, J. [Jet Propulsion Laboratory (JPL), National Aeronautics and Space Administration (NASA), Pasadena, CA 91109 (United States); Sullivan, I. [Department of Physics, University of Washington, Seattle, WA 98195 (United States); Arai, T.; Matsumoto, T.; Matsuura, S.; Tsumura, K. [Department of Space Astronomy and Astrophysics, Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara, Kanagawa 252-5210 (Japan); Cooray, A.; Mitchell-Wynne, K.; Smidt, J. [Center for Cosmology, University of California, Irvine, CA 92697 (United States); Hristov, V.; Lam, A. C.; Levenson, L. R.; Mason, P. [Department of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Keating, B.; Renbarger, T. [Department of Physics, University of California, San Diego, San Diego, CA 92093 (United States); Kim, M. G. [Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Lee, D. H. [Institute of Astronomy and Astrophysics, Academia Sinica, National Taiwan University, Taipei 10617, Taiwan (China); Nam, U. W. [Korea Astronomy and Space Science Institute (KASI), Daejeon 305-348 (Korea, Republic of); Suzuki, K. [Instrument Development Group of Technical Center, Nagoya University, Nagoya, Aichi 464-8602 (Japan); and others

    2013-08-15

    We have developed and characterized an imaging instrument to measure the spatial properties of the diffuse near-infrared extragalactic background light (EBL) in a search for fluctuations from z > 6 galaxies during the epoch of reionization. The instrument is part of the Cosmic Infrared Background Experiment (CIBER), designed to observe the EBL above Earth's atmosphere during a suborbital sounding rocket flight. The imaging instrument incorporates a 2 Degree-Sign Multiplication-Sign 2 Degree-Sign field of view to measure fluctuations over the predicted peak of the spatial power spectrum at 10 arcmin, and 7'' Multiplication-Sign 7'' pixels, to remove lower redshift galaxies to a depth sufficient to reduce the low-redshift galaxy clustering foreground below instrumental sensitivity. The imaging instrument employs two cameras with {Delta}{lambda}/{lambda} {approx} 0.5 bandpasses centered at 1.1 {mu}m and 1.6 {mu}m to spectrally discriminate reionization extragalactic background fluctuations from local foreground fluctuations. CIBER operates at wavelengths where the electromagnetic spectrum of the reionization extragalactic background is thought to peak, and complements fluctuation measurements by AKARI and Spitzer at longer wavelengths. We have characterized the instrument in the laboratory, including measurements of the sensitivity, flat-field response, stray light performance, and noise properties. Several modifications were made to the instrument following a first flight in 2009 February. The instrument performed to specifications in three subsequent flights, and the scientific data are now being analyzed.

  20. 选择性P型量子阱垒层掺杂在双波长发光二极管光谱调控中的作用%Investigation of spectral regulation in dual wavelength light-emitting diodes by using the selective p-doped barrier*

    Institute of Scientific and Technical Information of China (English)

    陈峻; 范广涵; 张运炎

    2012-01-01

    The electrical and the optical characteristics of dual-wavelength light-emitting diode (LED) with the newly designed selective p-doped barriers are investigated numerically. The simulation results show that the selective p-doped barriers can improve the distribution equilibria of electron and hole concentrations in each quantum well (QW). The radiative recombination rate of QW is enhanced remarkably when specific number of p-doped barriers is adopted, and the electron leakage current is suppressed obviously with this new design. Therefore, the internal quantum efficiency is improved and the trend of efficiency drooping with the increase of current injection is also alleviated. Moreover, the curve peaks of the spectrum become quite uniform when the specific number of vertically-stacked QWs is adopted, and the spectral regulation of the dual-wavelength LED is more effective%采用软件理论分析的方法对选择性P型掺杂量子阱垒层在InGaN双波长发光二极管(LED)中的光谱调控作用进行模拟分析.分析结果表明,选择性P型掺杂对量子阱中电子和空穴浓度分布的均衡性起到一定的调控作用,在适当选择P型掺杂量子阱垒层层数的条件下,能够改善量子阱中载流子的辐射复合速率,降低溢出电子浓度,从而有效提高芯片内量子效率,并减缓内量子效率随驱动电流增大而快速下降的趋势.随着活性层量子阱增加到特定数量,选择性P型掺杂的调控效果更加明显,LED芯片的双波长发光峰强度达到基本均衡.

  1. Wavelength-selective plasmonics for enhanced cultivation of microalgae

    Science.gov (United States)

    Ooms, Matthew D.; Jeyaram, Yogesh; Sinton, David

    2015-02-01

    Optimal photon management is a key challenge for photobioreactor design, since light gradients and varying spectral sensitivities between organisms result in uneven illumination and unused photons. This paper demonstrates wavelength specific scattering from plasmonic nano-patterned surfaces as a means of addressing the challenge of photon management in photobioreactors. Modular photobioreactors were constructed with different reflective substrates including arrays of plasmonic nanodisks, broadband reflectors, and untreated glass. It was found that the growth rate of cyanobacterium S. elongatus in photobioreactors equipped with a plasmonic substrate (R623 nm ˜ 35%) was enhanced by 6.5% compared to photobioreactors equipped with untreated glass. Furthermore, plasmonic reflectors showed a normalized power efficiency improvement of 52% over broadband reflectors. Wavelength-specific reflection from plasmonic reflectors increases the flux of useful light to cultures without sacrificing the full spectrum.

  2. Wavelength-selective plasmonics for enhanced cultivation of microalgae

    Energy Technology Data Exchange (ETDEWEB)

    Ooms, Matthew D.; Jeyaram, Yogesh; Sinton, David, E-mail: sinton@mie.utoronto.ca [Department of Mechanical and Industrial Engineering, and Institute for Sustainable Energy, University of Toronto, Toronto M5S 3G8 (Canada)

    2015-02-09

    Optimal photon management is a key challenge for photobioreactor design, since light gradients and varying spectral sensitivities between organisms result in uneven illumination and unused photons. This paper demonstrates wavelength specific scattering from plasmonic nano-patterned surfaces as a means of addressing the challenge of photon management in photobioreactors. Modular photobioreactors were constructed with different reflective substrates including arrays of plasmonic nanodisks, broadband reflectors, and untreated glass. It was found that the growth rate of cyanobacterium S. elongatus in photobioreactors equipped with a plasmonic substrate (R{sub 623 nm} ∼ 35%) was enhanced by 6.5% compared to photobioreactors equipped with untreated glass. Furthermore, plasmonic reflectors showed a normalized power efficiency improvement of 52% over broadband reflectors. Wavelength-specific reflection from plasmonic reflectors increases the flux of useful light to cultures without sacrificing the full spectrum.

  3. Spatial Symmetry Breaking in the Belousov-Zhabotinsky Reaction with Light-Induced Remote Communication

    Energy Technology Data Exchange (ETDEWEB)

    Hildebrand, M.; Skodt, H.; Showalter, K.

    2001-08-20

    Domains containing spiral waves form on a stationary background in a photosensitive Belousov-Zhabotinsky reaction with light-induced alternating nonlocal feedback. Complex behavior of colliding and splitting wave fragments is found with feedback radii comparable to the spiral wavelength. A linear stability analysis of the uniform stationary states in an Oregonator model reveals a spatial symmetry breaking instability. Numerical simulations show behavior in agreement with that found experimentally and also predict a variety of other new patterns.

  4. Energy Efficient Task Light

    DEFF Research Database (Denmark)

    Logadottir, Asta; Ardkapan, Siamak Rahimi; Johnsen, Kjeld

    2014-01-01

    The objectives of this work is to develop a task light for office lighting that fulfils the minimum requirements of the European standard EN12464 - 1 : Light and lightingLighting of work places, Part 1: Indoor workplaces and the Danish standard DS 700 : Lys og belysning I arbejdsrum , or more...... specifically the requirements that apply to the work area and the immediate surrounding area. By providing a task light that fulfils the requirements for task lighting and the immediate surrounding area, the general lighting only needs to provide the illuminance levels required for background lighting...... and thereby a reduction in installed power for general lighting of about 40 % compared to the way illuminance levels are designed in an office environment in Denmark today. This lighting strategy is useful when the placement of the task area is not defined in the space before the lighting is design ed...

  5. Lighting Design

    DEFF Research Database (Denmark)

    Hansen, Ellen Kathrine; Mullins, Michael

    2014-01-01

    Light as a multi-dimensional design element has fundamental importance for a sustainable environment. The paper discusses the need for an integration of scientific, technical and creative approaches to light and presents theory, methods and applications toward fulfilling this need. A theory...... of design developed from three experiments show how distinct qualitative and quantitative criteria in different disciplinary traditions can be integrated successfully, despite disparate technical/scientific, social scientific and art/humanities backgrounds. The model is applied to a pedagogical curriculum...

  6. Lighting Design

    DEFF Research Database (Denmark)

    Hansen, Ellen Kathrine; Mullins, Michael

    2014-01-01

    of design developed from three experiments show how distinct qualitative and quantitative criteria in different disciplinary traditions can be integrated successfully, despite disparate technical/scientific, social scientific and art/humanities backgrounds. The model is applied to a pedagogical curriculum......Light as a multi-dimensional design element has fundamental importance for a sustainable environment. The paper discusses the need for an integration of scientific, technical and creative approaches to light and presents theory, methods and applications toward fulfilling this need. A theory...

  7. Calculus light

    CERN Document Server

    Friedman, Menahem

    2011-01-01

    Another Calculus book? As long as students find calculus scary, the failure rate in mathematics is higher than in all other subjects, and as long as most people mistakenly believe that only geniuses can learn and understand mathematics, there will always be room for a new book of Calculus. We call it Calculus Light. This book is designed for a one semester course in ""light"" calculus -- mostly single variable, meant to be used by undergraduate students without a wide mathematical background and who do not major in mathematics but study subjects such as engineering, biology or management infor

  8. Sub-wavelength diffractive optics

    Energy Technology Data Exchange (ETDEWEB)

    Warren, M.E.; Wendt, J.R.; Vawter, G.A.

    1998-03-01

    This report represents the completion of a three-year Laboratory-Directed Research and Development (LDRD) program to investigate sub-wavelength surface relief structures fabricated by direct-write e-beam technology as unique and very high-efficiency optical elements. A semiconductor layer with sub-wavelength sized etched openings or features can be considered as a layer with an effective index of refraction determined by the fraction of the surface filled with semiconductor relative to the fraction filled with air or other material. Such as a layer can be used to implement planar gradient-index lenses on a surface. Additionally, the nanometer-scale surface structures have diffractive properties that allow the direct manipulation of polarization and altering of the reflective properties of surfaces. With this technology a single direct-write mask and etch can be used to integrate a wide variety of optical functions into a device surface with high efficiencies; allowing for example, direct integration of polarizing optics into the surface with high efficiencies; allowing for example, direct integration of polarizing optics into the surfaces of devices, forming anti-reflection surfaces or fabricating high-efficiency, high-numerical aperture lenses, including integration inside vertical semiconductor laser cavities.

  9. Astronomical Studies at Infrared Wavelengths

    Science.gov (United States)

    Rinehart, Stephen A.

    2009-01-01

    Astronomical studies at infrared wavelengths have dramatically improved our understanding of the universe, and observations with Spitzer, Herschel, and SOFIA will continue to provide exciting new discoveries. The relatively low angular resolution of these missions, however, is insufficient to resolve the physical scale on which mid-to far-infrared emission arises, resulting in source and structure ambiguities that limit our ability to answer key science questions. Interferometry enables high angular resolution at these wavelengths - a powerful tool for scientific discovery. We will build the Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII), an eight-meter baseline Michelson stellar interferometer to fly on a high-altitude balloon. BETTII's spectral-spatial capability, provided by an instrument using double-Fourier techniques, will address key questions about the nature of disks in young star clusters and active galactic nuclei and the envelopes of evolved stars. BETTII will also lay the technological groundwork for future balloon programs, paving the way for interferometric observations of exoplanets.

  10. Long-wavelength silicon photonic integrated circuits

    OpenAIRE

    2014-01-01

    In this paper we elaborate on our development of silicon photonic integrated circuits operating at wavelengths beyond the telecommunication wavelength window. Silicon-on-insulator waveguide circuits up to 3.8 mu m wavelength are demonstrated as well as germanium-on-silicon waveguide circuits operating in the 5-5 mu m wavelength range. The heterogeneous integration of III-V semiconductors and IV-VI semiconductors on this platform is described for the integration of lasers and photodetectors op...

  11. The Cosmic Microwave Background

    OpenAIRE

    Silk, Joseph

    2002-01-01

    This set of lectures provides an overview of the basic theory and phenomenology of the cosmic microwave background. Topics include a brief historical review; the physics of temperature and polarization fluctuations; acoustic oscillations of the primordial plasma; the space of inflationary cosmological models; current and potential constraints on these models from the microwave background; and constraints on inflation.

  12. Supersymmetric heterotic string backgrounds

    NARCIS (Netherlands)

    Gran, U.; Papadopoulos, G.; Roest, D.; Cvetič, M.

    2007-01-01

    We present the main features of the solution of the gravitino and dilatino Killing spinor equations derived in hep-th/0510176 and hep-th/0703143 which have led to the classification of geometric types of all type I backgrounds. We then apply these results to the supersymmetric backgrounds of the het

  13. All-optical wavelength-shifting technologies

    DEFF Research Database (Denmark)

    Jørgensen, Carsten; Mikkelsen, Benny; Danielsen, Søren Lykke

    1995-01-01

    State-of-the-art results for interferometric wavelength converters for WDM fiber networks have been presented. The interferometric converters are capable of high speed (10 Gbit/s), polarisation and wavelength independent (within 30 nn) wavelength conversion. In addition they offer unique features...

  14. Nearly wavelength-independent systems for broadband security applications

    Science.gov (United States)

    Andrés, P.; Tajahuerce, E.; Mínguez-Vega, G.

    2005-09-01

    We describe the application of nearly wavelength-independent optical processors to develop several broadband security techniques. Our achromatic optical configurations, based in the appropriate combination of a small number of diffractive and refractive lenses, are designed to work under temporally incoherent illumination. In this way, we are able to develop a method to reconstruct color Fourier holograms, an optical system to perform color pattern recognition and a technique to encrypt and decrypt color input objects, in all cases under white-light illumination. Moreover, we extend these ideas to work under both spatially and temporally incoherent illumination. This allows us to perform color pattern recognition and optical encryption techniques under natural light.

  15. The {ital COBE} Diffuse Infrared Background Experiment Search for the Cosmic Infrared Background. I. Limits and Detections

    Energy Technology Data Exchange (ETDEWEB)

    Hauser, M.G. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Arendt, R.G. [Raytheon STX, Code 685, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Kelsall, T.; Dwek, E. [Code 685, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Odegard, N.; Weiland, J.L.; Freudenreich, H.T. [Raytheon STX, Code 685, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Reach, W.T. [California Institute of Technology, IPAC/JPL, MS 100-22, Pasadena, CA 91125 (United States); Silverberg, R.F.; Moseley, S.H. [Code 685, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Pei, Y.C. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Lubin, P. [Physics Department, University of California at Santa Barbara, Santa Barbara, CA 93106 (United States); Mather, J.C.; Shafer, R.A. [Code 685, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Smoot, G.F. [Lawrence Berkeley Laboratory, Space Sciences Laboratory, Department of Physics, UC Berkeley, CA 94720 (United States); Weiss, R. [Massachusetts Institute of Technology, Room 20F-001, Department of Physics, Cambridge, MA 02139 (United States); Wilkinson, D.T. [Princeton University, Department of Physics, Jadwin Hall, Box 708, Princeton, NJ 08544 (United States); Wright, E.L. [UCLA, Astronomy Department, Los Angeles, CA 90024-1562 (United States)

    1998-11-01

    The Diffuse Infrared Background Experiment (DIRBE) on the Cosmic Background Explorer ({ital COBE}) spacecraft was designed primarily to conduct a systematic search for an isotropic cosmic infrared background (CIB) in 10 photometric bands from 1.25 to 240 {mu}m. The results of that search are presented here. Conservative limits on the CIB are obtained from the minimum observed brightness in all-sky maps at each wavelength, with the faintest limits in the DIRBE spectral range being at 3.5 {mu}m ({nu}{ital I}{sub {nu}} {lt} 64 nW m{sup {minus}2} sr{sup {minus}1}, 95{percent} confidence level) and at 240 {mu}m ({nu}{ital I}{sub {nu}} {lt} 28 nW m{sup {minus}2} sr{sup {minus}1}, 95{percent} confidence level). The bright foregrounds from interplanetary dust scattering and emission, stars, and interstellar dust emission are the principal impediments to the DIRBE measurements of the CIB. These foregrounds have been modeled and removed from the sky maps. Assessment of the random and systematic uncertainties in the residuals and tests for isotropy show that only the 140 and 240 {mu}m data provide candidate detections of the CIB. The residuals and their uncertainties provide CIB upper limits more restrictive than the dark sky limits at wavelengths from 1.25 to 100 {mu}m. No plausible solar system or Galactic source of the observed 140 and 240 {mu}m residuals can be identified, leading to the conclusion that the CIB has been detected at levels of {nu}{ital I}{sub {nu}} = 25 {plus_minus} 7 and 14 {plus_minus} 3 nW m{sup {minus}2} sr{sup {minus}1} at 140 and 240 {mu}m, respectively. The integrated energy from 140 to 240 {mu}m, 10.3 nW m{sup {minus}2} sr{sup {minus}1}, is about twice the integrated optical light from the galaxies in the Hubble Deep Field, suggesting that star formation might have been heavily enshrouded by dust at high redshift. The detections and upper limits reported here provide new constraints on models of the history of energy-releasing processes and dust

  16. The Athena Background

    Science.gov (United States)

    Piro, Luigi; Lotti, Simone; Macculi, Claudio; Molendi, Silvano; Eraerds, Tanja; Laurent, Philippe

    2015-09-01

    Estimating, reducing and controlling the residual particle background is fundamental for achieving the objectives of several science topics of Athena, in particular those connected with background dominated observations of faint and/or diffuse sources. This requires assessing the particle environment in L2, propagating the various particle components throughout the mirror, spacecraft, and instruments via proper modelling and simulations of various physical processes, implementing design and h/w measures at instrument and mission level to reduce the un-rejected background and identifying proper calibration methods to control the background variations. Likewise, an adequate knowledge of the XRB, made of components that may vary spatially or temporally, is required as well. Here we will review the present status of the background knowledge, and summarize the activities on-going within Athena at various levels.

  17. Environmental Effects on TPB Wavelength-Shifting Coatings

    CERN Document Server

    Chiu, C S; Bugel, L; Chen, H; Conrad, J M; Jones, B J P; Katori, T; Moult, I

    2012-01-01

    The scintillation detection systems of liquid argon time projection chambers (LArTPCs) require wavelength shifters to detect the 128 nm scintillation light produced in liquid argon. Tetraphenyl butadiene (TPB) is a fluorescent material that can shift this light to a wavelength of 425 nm, lending itself well to use in these detectors. We can coat the glass of photomultiplier tubes (PMTs) with TPB or place TPB-coated plates in front of the PMTs. In this paper, we investigate the degradation of a chemical TPB coating in a laboratory or factory environment to assess the viability of long-term TPB film storage prior to its initial installation in an LArTPC. We present evidence for severe degradation due to common fluorescent lights and ambient sunlight in laboratories, with potential losses at the 40% level in the first day and eventual losses at the 80% level after a month of exposure. We determine the degradation is due to wavelengths in the UV spectrum, and we demonstrate mitigating methods for retrofitting lab...

  18. Non-visual effects of light on melatonin, alertness and cognitive performance: can blue-enriched light keep us alert?

    Directory of Open Access Journals (Sweden)

    Sarah Laxhmi Chellappa

    Full Text Available BACKGROUND: Light exposure can cascade numerous effects on the human circadian process via the non-imaging forming system, whose spectral relevance is highest in the short-wavelength range. Here we investigated if commercially available compact fluorescent lamps with different colour temperatures can impact on alertness and cognitive performance. METHODS: Sixteen healthy young men were studied in a balanced cross-over design with light exposure of 3 different light settings (compact fluorescent lamps with light of 40 lux at 6500K and at 2500K and incandescent lamps of 40 lux at 3000K during 2 h in the evening. RESULTS: Exposure to light at 6500K induced greater melatonin suppression, together with enhanced subjective alertness, well-being and visual comfort. With respect to cognitive performance, light at 6500K led to significantly faster reaction times in tasks associated with sustained attention (Psychomotor Vigilance and GO/NOGO Task, but not in tasks associated with executive function (Paced Visual Serial Addition Task. This cognitive improvement was strongly related with attenuated salivary melatonin levels, particularly for the light condition at 6500K. CONCLUSIONS: Our findings suggest that the sensitivity of the human alerting and cognitive response to polychromatic light at levels as low as 40 lux, is blue-shifted relative to the three-cone visual photopic system. Thus, the selection of commercially available compact fluorescent lights with different colour temperatures significantly impacts on circadian physiology and cognitive performance at home and in the workplace.

  19. Measurement of Optical Attenuation in Acrylic Light Guides for a Dark Matter Detector

    CERN Document Server

    Bodmer, M; Gold, M; Loomba, D; Matthews, J A J; Rielage, K

    2013-01-01

    Acrylic is a common material used in dark matter and neutrino detectors for light guides, transparent vessels, and neutron shielding, creating an intermediate medium between the target volume and photodetectors. Acrylic has low absorption within the visible spectrum and has a high capture cross section for neutrons. The natural radioactivity in photodetectors is a major source of background neutrons for low background detectors making the use of acrylic attractive for shielding and background reduction. To test the optical properties of acrylic we measured the transmittance and attenuation length of fourteen samples of acrylic from four different manufacturers. Samples were evaluated at five different wavelengths between 375 nm and 632 nm. We found that all samples had excellent transmittance at wavelengths greater than 550 nm. Transmittance was found to decrease below 550 nm. As expected, UV-absorbing samples showed a sharp decrease in transmittance below 425 nm compared to UV-transmitting samples. We report...

  20. Bolometric Arrays for Millimeter Wavelengths

    Science.gov (United States)

    Castillo, E.; Serrano, A.; Torres-Jácome, A.

    2009-11-01

    During last years, semiconductor bolometers using thin films have been developed at INAOE, specifically boron-doped hydrogenated amorphous silicon films. The characteristics shown by these devices made them attractive to be used in astronomical instrumentation, mainly in two-dimentional arrays. These detector arrays used at the Large Millimeter Telescope will make possible to obtain astronomical images in millimeter and sub-millimeter wavelengths. With this in mind, we are developing a method to produce, with enough reliability, bolometer arrays at INAOE. Until now, silicon nitride diaphragm arrays, useful as radiation absorbers, have succesfully been obtained. Sizes going from one to four millimeter by element in a consistent way; however we have not tested thermometers and metallic contact deposition yet. At the same time, we are working on two possible configurations for the readout electronics; one of them using commercial components while the other will be an integrated circuit specifically designed for this application. Both versions will work below 77K.

  1. Wavelength modulation spectroscopy of semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Kohn, S.E.

    1977-10-01

    The use of modulation spectroscopy to study the electronic properties of solids has been very productive. The construction of a wide range Wavelength Modulation Spectrometer to study the optical properties of solids is described in detail. Extensions of the working range of the spectrometer into the vacuum ultraviolet are discussed. Measurements of the reflectivity and derivative reflectivity spectra of the lead chalcogenides, the chalcopyrite ZnGeP/sub 2/, the layer compounds GaSe and GaS and their alloys, the ferroelectric SbSI, layer compounds SnS/sub 2/ and SnSe/sub 2/, and HfS/sub 2/ were made. The results of these measurements are presented along with their interpretation in terms of band structure calculations.

  2. Cosmogenic Backgrounds to 0{\

    CERN Document Server

    :,; Auty, D J; Barbeau, P S; Beck, D; Belov, V; Breidenbach, M; Brunner, T; Burenkov, A; Cao, G F; Chambers, C; Cleveland, B; Coon, M; Craycraft, A; Daniels, T; Danilov, M; Daugherty, S J; Davis, J; Delaquis, S; Der Mesrobian-Kabakian, A; DeVoe, R; Didberidze, T; Dilling, J; Dolgolenko, A; Dolinski, M J; Dunford, M; Fairbank, W; Farine, J; Feldmeier, W; Feyzbakhsh, S; Fierlinger, P; Fudenberg, D; Gornea, R; Graham, K; Gratta, G; Hall, C; Herrin, S; Hughes, M; Jewell, M J; Johnson, A; Johnson, T N; Johnston, S; Karelin, A; Kaufman, L J; Killick, R; Koffas, T; Kravitz, S; Krücken, R; Kuchenkov, A; Kumar, K S; Leonard, D S; Licciardi, C; Lin, Y H; Ling, J; MacLellan, R; Marino, M G; Mong, B; Moore, D; Njoya, O; Nelson, R; Odian, A; Ostrovskiy, I; Piepke, A; Pocar, A; Prescott, C Y; Retière, F; Rowson, P C; Russell, J J; Schubert, A; Sinclair, D; Smith, E; Stekhanov, V; Tarka, M; Tolba, T; Tsang, R; Twelker, K; Vuilleumier, J -L; Waite, A; Walton, J; Walton, T; Weber, M; Wen, L J; Wichoski, U; Wood, J; Yang, L; Yen, Y -R; Zeldovich, O Ya

    2015-01-01

    As neutrinoless double-beta decay experiments become more sensitive and intrinsic radioactivity in detector materials is reduced, previously minor contributions to the background must be understood and eliminated. With this in mind, cosmogenic backgrounds have been studied with the EXO-200 experiment. Using the EXO-200 TPC, the muon flux (through a flat horizontal surface) underground at the Waste Isolation Pilot Plant (WIPP) has been measured to be {\\Phi} = 4.07 $\\pm$ 0.14 (sys) $\\pm$ 0.03 (stat) $\\times$ $10^{-7}$cm$^{-2}$ s$^{-1}$, with a vertical intensity of $I_{v}$ = 2.97$^{+0.14}_{-0.13}$ (sys) $\\pm$ 0.02 (stat) $\\times$ $10^{-7}$cm$^{-2}$ s$^{-1}$ sr$^{-1}$. Simulations of muon-induced backgrounds identified several potential cosmogenic radionuclides, though only 137Xe is a significant background for the 136Xe 0{\

  3. On Background Independence

    CERN Document Server

    Anderson, Edward

    2013-01-01

    This paper concerns what Background Independence itself is (as opposed to some particular physical theory that is background independent). The notions presented mostly arose from a layer-by-layer analysis of the facets of the Problem of Time in Quantum Gravity. Part of this coincides with two relational postulates which are thus identified as classical precursors of two of the facets of the Problem of Time. These are furthemore tied to the forms of each of the GR Hamiltonian and momentum constraints. Other aspects of Background Independence include the algebraic closure of these constraints, expressing physics in terms of beables, foliation independence as implemented by refoliation invariance, the reconstruction of spacetime from space. The final picture is that Background Independence - a philosophically desirable and physically implementable feature for a theory to have - has the facets of the Problem of Time among its consequences. Thus these arise naturally and are problems to be resolved, as opposed to ...

  4. Zambia Country Background Report

    DEFF Research Database (Denmark)

    Hampwaye, Godfrey; Jeppesen, Søren; Kragelund, Peter

    This paper provides background data and general information for the Zambia studies focusing on local food processing sub­‐sector; and the local suppliers to the mines as part of the SAFIC project (Successful African Firms and Institutional Change).......This paper provides background data and general information for the Zambia studies focusing on local food processing sub­‐sector; and the local suppliers to the mines as part of the SAFIC project (Successful African Firms and Institutional Change)....

  5. [Design and implementation of a long wavelength near infrared spectrometer based on MEMS scanning mirror].

    Science.gov (United States)

    Ye, Kun-Tao; Dong, Tai-Yuan; He, Wen-Xi; Li, Yu-Xiao; Cheng, Xian-Ming; Li, Guang-Yong; Li, Hao-Yu; Xu, Hao-Yu

    2014-10-01

    Long Wavelength Near InfraRed (LW-NIR) spectrometer has wide applications. Miniaturization and low-cost are two major goals of the development of LW-NIR spectrometer in the industrial or research community. Under the background that having a trend of spectrometer miniaturization and integration, method and main problems involved in miniaturization of LW-NIR spectrometer through MEMS scanning mirror, such as the design strategy of the light-splitting optical system, selection considerations of the MEMS scanning mirror, design method of the preamplifier circuit, etc, have been presented in detail. A prototype of miniaturized LW-NIR spectrometer, with the spectrum range of detection of 900-2,055 nm, is designed and implemented using MEMS scanning mirror, InGaAs single detector unit with high sensitivity. Littrow optical layout is used for its light-splitting optical system, and the spectral resolution is between 9.4-16 nm at 1,000-1,965 nm detection wavelength range. The prototype is successfully applied in LW-NIR spectrum measurement on pure water and ethanol aqueous solution, and a forecast analysis on ethanol aqueous solution concentration is also demonstrated. Through adopting MEMS scanning mirror into the spectrometer system, the complexity of the mechanical scanning fixtures and its controlling mechanism is greatly reduced therefore the size of the spectrometer is reduced. Furthermore, due to MEMS scanning mirror technology, LW-NIR spectrometer with single InGaAs detector is achieved, thus the cost reduction of the NIR spectrometer system is also realized because the expensive InGaAs arrays are avoided.

  6. GPC light shaping a supercontinuum source

    DEFF Research Database (Denmark)

    Kopylov, Oleksii; Bañas, Andrew Rafael; Villangca, Mark Jayson;

    2015-01-01

    incorporating various multi-wavelength approaches into spatially shaped excitations that can enable new broadband light applications. We verify this new approach using a supercontinuum light source, interfaced with a compact GPC light shaper. Our experiments give ~70% efficiency, ~3x intensity gain, and ~85......Generalized Phase Contrast (GPC) is a versatile tool for efficiently rerouting and managing photon energy into speckle-free contiguous spatial light distributions. We have previously shown theoretically and numerically that a GPC Light Shaper shows robustness to shift in wavelength and can maintain...... both projection length scale and high efficiency over a range [0.75λ0; 1.5λ0] with λ0 as the characteristic design wavelength. With this performance across multiple wavelengths and the recent availability of tabletop supercontinuum lasers, GPC light shaping opens the possibility for creatively...

  7. The influence of femtosecond laser pulse wavelength on embryonic stem cell differentiation

    CSIR Research Space (South Africa)

    Mthunzi, P

    2012-08-01

    Full Text Available play an active role in absorbing ultra-violet (UV) and visible light sources. Light-matter interactions in biomaterials are a complex situation and subsequent damage may not always amount only from wavelength dependent effects but may also be driven...

  8. 5,000 h reliable operation of 785nm dual-wavelength DBR-RW diode lasers suitable for Raman spectroscopy and SERDS

    Science.gov (United States)

    Sumpf, Bernd; Müller, André; Maiwald, Martin

    2016-03-01

    Monolithic wavelength stabilized diode lasers, e.g. distributed Bragg reflector (DBR) ridge waveguide (RW) lasers, are well-suited light sources for compact and portable Raman spectroscopic systems. In the case of in situ and outdoor investigations, the weak Raman lines are often superimposed by daylight, artificial light sources or fluorescence signals from the samples under study. Among others, shifted excitation Raman difference spectroscopy (SERDS) has been demonstrated as a powerful and easy-to-use technique to separate the Raman lines from disturbing background signals. SERDS is based on subsequential excitation of the sample with two slightly shifted wavelengths. The Raman lines follow the change in the excitation wavelength whereas the non-Raman signals remain unchanged. For SERDS dual-wavelength light sources, e.g., mini-arrays containing two DBR-RW lasers, are requested. Moreover, for portable Raman instruments such as handheld devices robust and reliable excitation light sources with lifetimes > 1,000 h are preferred. In this work, reliability investigations of dual-wavelength DBR-RW mini-arrays over a total test time of 5,000 h are presented. Wavelength stabilization and narrowing of the spectral emission is realized by 10th-order DBR surface gratings defined by i-line wafer stepper technology. The DBR-section has a length of 500 μm, the devices a total length of 3 mm. The ridge waveguide has a stripe width of 2.2 μm. Maximum output powers up to 215 mW per emitter were measured. Over the whole power range, 95 % of the emitted power is within a spectral width of 0.15 nm (2.5 cm-1), which is smaller than the spectral width needed to resolve most Raman lines of solid and liquid samples. In a step-stress test, the devices were tested at 50 mW, followed by 75 mW and finally at 100 mW per emitter. Electro-optical and spectral measurements were performed before, during and after the test. All emitters under study did not show any deterioration of their

  9. A background free double beta decay experiment

    OpenAIRE

    Giomataris, Ioannis

    2010-01-01

    We present a new detection scheme for rejecting backgrounds in neutrino less double beta decay experiments. It relies on the detection of Cherenkov light emitted by electrons in the MeV region. The momentum threshold is tuned to reach a good discrimination between background and good events. We consider many detector concepts and a range of target materials. The most promising is a high-pressure 136Xe emitter for which the required energy threshold is easily adjusted. Combination of this conc...

  10. Efficiency Studies and Simulations of a Neutron Background Veto for Dark Matter Detectors

    Science.gov (United States)

    Westerdale, Shawn; Shields, Emily; Xu, Jingke; Calaprice, Frank

    2013-04-01

    In direct WIMP dark matter detection experiments, neutrons from cosmogenic sources and nuclear reactions in detector materials can provide backgrounds indistinguishable from WIMP signals. To reduce this background, an active neutron veto filled with a boron-loaded scintillator is being developed. The scintillator used will be pseudocumene, mixed with trimethyl borate as a boron source, and a PPO wavelength shifter. Such a veto would detect neutrons in the volume surrounding the detector, allowing coincident background events in the detector to be rejected. Neutrons are captured by the ^10B with a high cross section, resulting in an α and ^7Li. The scintillation from the nuclear products is heavily quenched to an equivalent electron energy as low as 50 keV. To detect this, it is necessary to have high light collection efficiency. To model the neutron veto concept, light yield measurements were taken for a small prototype filled with the scintillator mixture and lined with a Lumirror reflector. These results were reproduced in GEANT4 and in an independent simulation. We then applied the simulations to the DarkSide-50 neutron veto to predict its neutron rejection power. Results from measurements taken with the prototype and from the simulation will be presented.

  11. Light-sensitive brain pathways and aging

    OpenAIRE

    Daneault, Véronique; Dumont, Marie; Massé, Eric; Vandewalle, Gilles; Carrier, Julie

    2016-01-01

    Notwithstanding its effects on the classical visual system allowing image formation, light acts upon several non-image-forming (NIF) functions including body temperature, hormonal secretions, sleep-wake cycle, alertness, and cognitive performance. Studies have shown that NIF functions are maximally sensitive to blue wavelengths (460–480 nm), in comparison to longer light wavelengths. Higher blue light sensitivity has been reported for melatonin suppression, pupillary constriction, vigilance, ...

  12. Characterization, 1064 nm photon signals and background events of a tungsten TES detector for the ALPS experiment

    Energy Technology Data Exchange (ETDEWEB)

    Dreyling-Eschweiler, J.; Doebrich, B.; Januschek, F.; Lindner, A. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Bastidon, N.; Horns, D. [Hamburg Univ. (Germany). Inst. fuer Experimentalphysik

    2015-02-15

    The high efficiency, low-background, and single-photon detection with transition-edge sensors (TES) is making this type of detector attractive in widely different types of application. In this paper, we present first characterizations of a TES to be used in the Any Light Particle Search (ALPS) experiment searching for new fundamental ultra-light particles. Firstly, we describe the setup and the main components of the ALPS TES detector (TES, millikelvin-cryostat and SQUID read-out) and their performances. Secondly, we explain a dedicated analysis method for single-photon spectroscopy and rejection of non-photon background. Finally, we report on results from extensive background measurements. Considering an event-selection, optimized for a wavelength of 1064 nm, we achieved a background suppression of ∝10{sup -3} with a ∝ 50 % efficiency for photons passing the selection. The resulting overall efficiency was 23 % with a dark count rate of 8.6.10{sup -3} s{sup -1}. We observed that pile-up events of thermal photons are the main background component.

  13. Wavelength calibration for OSIRIS/GTC* tunable filters

    CERN Document Server

    Mendez-Abreu, J; Munoz-Tunon, C; Rodriguez-Espinosa, J M; Aguerri, J A L; Gonzalez, D Rosa; Mayya, Y D; Vega, O; Terlevich, R; Terlevich, E; Bertone, E; Rodriguez-Merino, L H

    2011-01-01

    OSIRIS (Optical System for Imaging and low Resolution Integrated Spectroscopy) is the first light instrument of the Gran Telescopio Canarias (GTC). It provides a flexible and competitive tunable filter (TF). Since it is based on a Fabry-Perot interferometer working in collimated beam, the TF transmission wavelength depends on the position of the target with respect to the optical axis. This effect is non-negligible and must be accounted for in the data reduction. Our paper establishes a wavelength calibration for OSIRIS TF with the accuracy required for spectrophotometric measurements using the full field of view (FOV) of the instrument. The variation of the transmission wavelength $\\lambda(R)$ across the FOV is well described by $\\lambda(R)=\\lambda(0)/\\sqrt{1+(R/f_2)^2}$, where $\\lambda(0)$ is the central wavelength, $R$ represents the physical distance from the optical axis, and $f_2=185.70\\pm0.17\\,$mm is the effective focal length of the camera lens. This new empirical calibration yields an accuracy better...

  14. Magic and tune-out wavelengths for atomic francium

    CERN Document Server

    Dammalapati, U; Sakemi, Y

    2016-01-01

    The frequency dependent polarizabilities of the francium atom are calculated from the available data of energy levels and transition rates. Magic wavelengths for the state insensitive optical dipole trapping are identified from the calculated light shifts of the $7s~^2S_{1/2}$, $7p~^2P_{1/2, 3/2}$ and $8s~^{2}S_{1/2}$ levels of the $7s~^{2}S_{1/2}-7p~^{2}P_{1/2,3/2}$ and $7s~^{2}S_{1/2}-8s~^{2}S_{1/2}$ transitions, respectively. Wavelengths in the ultraviolet, visible and near infrared region is identified that are suitable for cooling and trapping. Magic wavelengths between 600-700~nm and 700-1000~nm region, which are blue and red detuned with the $7s-7p$ and $7s-8s$ transitions are feasible to implement as lasers with sufficient power are available. In addition, we calculated the tune-out wavelengths where the ac polarizability of the ground $7s~^{2}S_{1/2}$ state in francium is zero. These results are beneficial as laser cooled and trapped francium has been in use for fundamental symmetry investigations li...

  15. Exploring String Theory Backgrounds

    CERN Document Server

    Williams, B P

    2004-01-01

    This thesis examines phenomenological and theoretical questions by exploring string theoretic backgrounds. Part I focuses on cosmology. First we propose that the induced metric along a brane moving through a curved bulk may be interpreted as the cosmology of the brane universe, providing a resolution to the apparent cosmological singularity on the brane. We then look at various decay channels of the certain meta-stable de Sitter vacua and show that there exist NS5-brane meditated decays which are much faster than decays to decompactification. Part II discusses a new class of nongeometric vacua in string theory. These backgrounds may be described locally as T2 fibrations. By enlarging the monodromy group of the fiber to include perturbative stringy duality symmetries we are able to explicitly construct nongeometric backgrounds.

  16. BOLOMETRIC ARRAYS FOR MILLIMETER WAVELENGTHS

    Directory of Open Access Journals (Sweden)

    E. Castillo

    2009-01-01

    Full Text Available During last years, semiconductor bolometers using thin lms have been developed at INAOE, speci cally boron-doped hydrogenated amorphous silicon lms. The characteristics shown by these devices made them attractive to be used in astronomical instrumentation, mainly in two-dimentional arrays. These detector arrays used at the Large Millimeter Telescope will make possible to obtain astronomical images in millimeter and submillimeter wavelengths. With this in mind, we are developing a method to produce, with enough reliability, bolometer arrays at INAOE. Until now, silicon nitride diaphragm arrays, useful as radiation absorbers, have succesfully been obtained. Sizes going from one to four millimeter by element in a consistent way; however we have not tested thermometers and metallic contact deposition yet. At the same time, we are working on two possible con gurations for the readout electronics; one of them using commercial components while the other will be an integrated circuit speci cally designed for this application. Both versions will work below 77K.

  17. Cosmic Tachyon Background Radiation

    CERN Document Server

    Tomaschitz, R

    1999-01-01

    The equilibrium statistical mechanics of a background radiation of superluminal particles is investigated, based on a vectorial wave equation for tachyons of the Proca type. The partition function, the spectral energy density, and the various thermodynamic variables of an ideal Bose gas of tachyons in an open Robertson-Walker cosmology are derived. The negative mass square in the wave equation changes the frequency scaling in the Rayleigh-Jeans law, and there are also significant changes in the low temperature regime as compared to the microwave background, in particular in the caloric and thermal equations of state.

  18. Remote-sensing vibrometry at 1550 nm wavelength

    Science.gov (United States)

    Dräbenstedt, A.; Sauer, J.; Rembe, C.

    2012-06-01

    Laser-Doppler vibrometry (LDV) is a proven technique for vibration analysis of mechanical structures. A wavelength of 633 nm is usually employed because of the availability of the relatively inexpensive Helium-Neon laser source which has a good coherence behavior. However, coherence break-down through the beat of multiple longitudinal modes and the limited detector carrier-to-noise-ratio (CNR) at a measurement laser power of 1 mW have prevented a wide use of LDV in remote sensing applications. Such applications in civil engineering are bridges, towers or wind turbines. The lower photon energy of IR light at 1550 nm wavelength increases the CNR by a factor 2.4. This helps especially in the condition where the carrier power decreases below the FM threshold. We have designed a heterodyne interferometer which allows the shot noise limited detection at 1550 nm wavelength close to the theoretical possible CNR. We present calculations of the fundamental noise contributions in interferometric light detection for a comparison of the achievable CNR between common HeNe vibrometers and IR vibrometers. The calculations are backed by measurements that show the devices working close to the theoretical limits. The achievable noise level of the demodulated velocity signal is shown in dependence from the standoff distance. Our novel heterodyne interferometer has been transferred to the Polytec product RSV-150. An application example of this new sensor will be demonstrated.

  19. Positron Production in Multiphoton Light-by-Light Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Koffas, Thomas

    2003-07-28

    We present the results of an experimental study on e{sup +}e{sup -} pair production during the collision of a low emittance 46.6 GeV electron beam with terawatt laser pulses from a Nd:glass laser at 527 nm wavelength and with linear polarization. The experiment was conducted at the Final Focus Test Beam facility in the Stanford Linear Accelerator Center. Results with a 49.1 GeV electron beam are also included. A signal of 106 {+-} 14 positrons for the 46.6 GeV electron beam case and of 22 {+-} 10 positrons for the 49.1 GcV case above background, has been detected. We interpret the positrons as the products of a two-step process during which laser photons are backscattered to high energy gamma photons that absorb in their turn several laser photons in order to produce a e{sup +}e{sup -} pair. The data compare well with the existing theoretical models. This is the first observation in the laboratory of inelastic Light-by-Light scattering with only real photons. Alternatively, the data are interpreted as a manifestation of the spontaneous breakdown of the vacuum under the influence of an intense external alternating electric field.

  20. Light sheet microscopy reveals more gradual light attenuation in light green versus dark green soybean leaves

    Science.gov (United States)

    Light wavelengths preferentially absorbed by chlorophyll (chl) often display steep absorption gradients. This oversaturates photosynthesis in upper chloroplasts and deprives lower chloroplasts of blue and red light, causing a steep gradient in carbon fixation. Reducing chl content could create a mor...