Science.gov

Sample records for reflected infrared light

  1. Origin of Infrared Light Modulation in Reflectance-Mode Photoplethysmography

    PubMed Central

    Sidorov, Igor S.; Romashko, Roman V.; Koval, Vasily T.; Giniatullin, Rashid

    2016-01-01

    We recently pointed out the important role of dermis deformation by pulsating arterial pressure in the formation of a photoplethysmographic signal at green light. The aim of this study was to explore the role of this novel finding in near-infrared (NIR) light. A light-emitting diode (LED)-based imaging photoplethysmography (IPPG) system was used to detect spatial distribution of blood pulsations under frame-to-frame switching green and NIR illumination in the palms of 34 healthy individuals. We observed a significant increase of light-intensity modulation at the heartbeat frequency for both illuminating wavelengths after a palm was contacted with a glass plate. Strong positive correlation between data measured at green and NIR light was found, suggesting that the same signal was read independently from the depth of penetration. Analysis of the data shows that an essential part of remitted NIR light is modulated in time as a result of elastic deformations of dermis caused by variable blood pressure in the arteries. Our observations suggest that in contrast with the classical model, photoplethysmographic waveform originates from the modulation of the density of capillaries caused by the variable pressure applied to the skin from large blood vessels. Particularly, beat-to-beat transmural pressure in arteries compresses/decompresses the dermis and deforms its connective-tissue components, thus affecting the distance between the capillaries, which results in the modulation of absorption and scattering coefficients of both green and NIR light. These findings are important for the correct interpretation of this widely used medical technique, which may have novel applications in diagnosis and treatment monitoring of aging and skin diseases. PMID:27768753

  2. Differences in visible and near-infrared light reflectance between orange fruit and leaves

    NASA Technical Reports Server (NTRS)

    Gausman, H. W.; Escobar, D. E.; Berumen, A.

    1975-01-01

    The objective was to find the best time during the season (April 26, 1972 to January 8, 1973) to distinguish orange fruit from leaves by spectrophotometrically determining at 10-day intervals when the difference in visible (550- and 650-nm wavelengths) and near-infrared (850-nm wavelength) light reflectance between fruit and nearby leaves was largest. December 5 to January 8 was the best time to distinguish fruit from leaves. During this period the fruit's color was rapidly changing from green to yellow, and the difference in visible light reflectance between fruit and leaves was largest. The difference in near-infrared reflectance between leaves and fruit remained essentially constant during ripening when the difference in visible light reflectance between leaves and fruit was largest.

  3. Electrically tunable selective reflection of light from ultraviolet to visible and infrared by heliconical cholesterics.

    PubMed

    Xiang, Jie; Li, Yannian; Li, Quan; Paterson, Daniel A; Storey, John M D; Imrie, Corrie T; Lavrentovich, Oleg D

    2015-05-20

    Electrical tuning of selective reflection of light is achieved in a very broad spectral range from ultraviolet to visible and infrared by an oblique helicoidal state of a cholesteric liquid crystal in a wide temperature range (including room temperature). The phenomenon offers potential applications in tunable smart windows, lasers, optical filters and limiters, as well as in displays. PMID:25821155

  4. Recognition of Banknote Fitness Based on a Fuzzy System Using Visible Light Reflection and Near-infrared Light Transmission Images.

    PubMed

    Kwon, Seung Yong; Pham, Tuyen Danh; Park, Kang Ryoung; Jeong, Dae Sik; Yoon, Sungsoo

    2016-01-01

    Fitness classification is a technique to assess the quality of banknotes in order to determine whether they are usable. Banknote classification techniques are useful in preventing problems that arise from the circulation of substandard banknotes (such as recognition failures, or bill jams in automated teller machines (ATMs) or bank counting machines). By and large, fitness classification continues to be carried out by humans, and this can cause the problem of varying fitness classifications for the same bill by different evaluators, and requires a lot of time. To address these problems, this study proposes a fuzzy system-based method that can reduce the processing time needed for fitness classification, and can determine the fitness of banknotes through an objective, systematic method rather than subjective judgment. Our algorithm was an implementation to actual banknote counting machine. Based on the results of tests on 3856 banknotes in United States currency (USD), 3956 in Korean currency (KRW), and 2300 banknotes in Indian currency (INR) using visible light reflection (VR) and near-infrared light transmission (NIRT) imaging, the proposed method was found to yield higher accuracy than prevalent banknote fitness classification methods. Moreover, it was confirmed that the proposed algorithm can operate in real time, not only in a normal PC environment, but also in an embedded system environment of a banknote counting machine. PMID:27294940

  5. Recognition of Banknote Fitness Based on a Fuzzy System Using Visible Light Reflection and Near-infrared Light Transmission Images.

    PubMed

    Kwon, Seung Yong; Pham, Tuyen Danh; Park, Kang Ryoung; Jeong, Dae Sik; Yoon, Sungsoo

    2016-06-11

    Fitness classification is a technique to assess the quality of banknotes in order to determine whether they are usable. Banknote classification techniques are useful in preventing problems that arise from the circulation of substandard banknotes (such as recognition failures, or bill jams in automated teller machines (ATMs) or bank counting machines). By and large, fitness classification continues to be carried out by humans, and this can cause the problem of varying fitness classifications for the same bill by different evaluators, and requires a lot of time. To address these problems, this study proposes a fuzzy system-based method that can reduce the processing time needed for fitness classification, and can determine the fitness of banknotes through an objective, systematic method rather than subjective judgment. Our algorithm was an implementation to actual banknote counting machine. Based on the results of tests on 3856 banknotes in United States currency (USD), 3956 in Korean currency (KRW), and 2300 banknotes in Indian currency (INR) using visible light reflection (VR) and near-infrared light transmission (NIRT) imaging, the proposed method was found to yield higher accuracy than prevalent banknote fitness classification methods. Moreover, it was confirmed that the proposed algorithm can operate in real time, not only in a normal PC environment, but also in an embedded system environment of a banknote counting machine.

  6. Recognition of Banknote Fitness Based on a Fuzzy System Using Visible Light Reflection and Near-infrared Light Transmission Images

    PubMed Central

    Kwon, Seung Yong; Pham, Tuyen Danh; Park, Kang Ryoung; Jeong, Dae Sik; Yoon, Sungsoo

    2016-01-01

    Fitness classification is a technique to assess the quality of banknotes in order to determine whether they are usable. Banknote classification techniques are useful in preventing problems that arise from the circulation of substandard banknotes (such as recognition failures, or bill jams in automated teller machines (ATMs) or bank counting machines). By and large, fitness classification continues to be carried out by humans, and this can cause the problem of varying fitness classifications for the same bill by different evaluators, and requires a lot of time. To address these problems, this study proposes a fuzzy system-based method that can reduce the processing time needed for fitness classification, and can determine the fitness of banknotes through an objective, systematic method rather than subjective judgment. Our algorithm was an implementation to actual banknote counting machine. Based on the results of tests on 3856 banknotes in United States currency (USD), 3956 in Korean currency (KRW), and 2300 banknotes in Indian currency (INR) using visible light reflection (VR) and near-infrared light transmission (NIRT) imaging, the proposed method was found to yield higher accuracy than prevalent banknote fitness classification methods. Moreover, it was confirmed that the proposed algorithm can operate in real time, not only in a normal PC environment, but also in an embedded system environment of a banknote counting machine. PMID:27294940

  7. Direct observation of surface plasmons in YBCO by attenuated total reflection of light in the infrared

    NASA Astrophysics Data System (ADS)

    Walmsley, D. G.; Smyth, C. C.; Sellai, A.; McCafferty, P. G.; Dawson, P.; Morrow, T.; Graham, W. G.

    1994-02-01

    Surface plasmons have been observed directly in YBCO films in an Otto-geometry attenuated total reflection measurement at a wavelength of 3.392 μm. The laser deposited films are c-axis oriented on an MgO substrate. This observation confirms theoretical deductions from complex dielectric function data. Measured data have been fitted to a theoretical model and are compared with the optical constants determined by Bozovic [1]. The investigations have been extended to films with other orientations to investigate whether material anisotropy is reflected in the results and non-metallic behaviour is found.

  8. Built-in hyperspectral camera for smartphone in visible, near-infrared and middle-infrared lights region (second report): sensitivity improvement of Fourier-spectroscopic imaging to detect diffuse reflection lights from internal human tissues for healthcare sensors

    NASA Astrophysics Data System (ADS)

    Kawashima, Natsumi; Hosono, Satsuki; Ishimaru, Ichiro

    2016-05-01

    We proposed the snapshot-type Fourier spectroscopic imaging for smartphone that was mentioned in 1st. report in this conference. For spectroscopic components analysis, such as non-invasive blood glucose sensors, the diffuse reflection lights from internal human skins are very weak for conventional hyperspectral cameras, such as AOTF (Acousto-Optic Tunable Filter) type. Furthermore, it is well known that the spectral absorption of mid-infrared lights or Raman spectroscopy especially in long wavelength region is effective to distinguish specific biomedical components quantitatively, such as glucose concentration. But the main issue was that photon energies of middle infrared lights and light intensities of Raman scattering are extremely weak. For improving sensitivity of our spectroscopic imager, the wide-field-stop & beam-expansion method was proposed. Our line spectroscopic imager introduced a single slit for field stop on the conjugate objective plane. Obviously to increase detected light intensities, the wider slit width of the field stop makes light intensities higher, regardless of deterioration of spatial resolutions. Because our method is based on wavefront-division interferometry, it becomes problems that the wider width of single slit makes the diffraction angle narrower. This means that the narrower diameter of collimated objective beams deteriorates visibilities of interferograms. By installing the relative inclined phaseshifter onto optical Fourier transform plane of infinity corrected optical systems, the collimated half flux of objective beams derived from single-bright points on objective surface penetrate through the wedge prism and the cuboid glass respectively. These two beams interfere each other and form the infererogram as spatial fringe patterns. Thus, we installed concave-cylindrical lens between the wider slit and objective lens as a beam expander. We successfully obtained the spectroscopic characters of hemoglobin from reflected lights from

  9. Strength of mineral absorption features in the transmitted component of near-infrared reflected light - First results from RELAB

    NASA Astrophysics Data System (ADS)

    Pieters, C. M.

    1983-11-01

    Bidirectional reflectance measurements are the only type of reflectance data available to the remote observer. For compositional interpretations, data are desired not only for identification of possible mineral components but also for modal abundance. The latter requires detailed information about the strength of absorption features. Using a new laboratory facility, the RELAB, laboratory data in the near infrared are presented that document effects of particle size, mineral mixtures, and viewing geometry for selected materials with well-developed absorption bands. The commonly observed increase in reflectance with decrease in particle size is also observed for absorption bands as well as a related decrease in absorption strength. For small particles in parts of the spectrum of maximum reflectance, however, a minor decrease in reflectance with a decrese in particle size is sometimes observed. Small particles dominate the observed characteristics of particulate surfaces, which contain a range of particle sizes. The mean optical path length (transmission through particles) of reflected radiation measured for a variety of particle sizes has an apparent upper limit of about 2 mm for particles of less than 250 microns. The typical number of particles involved in the optical path is less than 50.

  10. Effects of surface contamination on the infrared emissivity and visible-light scattering of highly reflective surfaces at cryogenic temperatures

    NASA Technical Reports Server (NTRS)

    Viehmann, W.; Eubanks, A. G.

    1972-01-01

    A technique is described for the simultaneous in situ measurement of film thickness, refractive index, total normal emissivity, visible-light scattering, and reflectance of contaminant films on a highly reflective liquid-nitrogen cooled, stainless steel substrate. Emissivities and scattering data are obtained for films of water, carbon dioxide, silicone oil, and a number of aromatic and aliphatic hydrocarbons as a function of film thickness between zero and 20 microns. Of the contaminants investigated, water has by far the greatest effect on emissivity, followed by silicone oil, aliphatic hydrocarbons, aromatic hydrocarbons, and carbon dioxide. The emissivity increases more rapidly with film thickness between zero and 2.5 microns than at thicknesses greater than 2.5 microns. Scattering of visible light changes very little below 2 microns thickness but increases rapidly with thickness beyond 2 to 3 microns. The effect of contaminant films on passive radiation coolers is discussed.

  11. A new experimental setup for in situ infrared reflection absorption spectroscopy studies of atmospheric corrosion on metal surfaces considering the influence of ultraviolet light.

    PubMed

    Wiesinger, R; Kleber, Ch; Frank, J; Schreiner, M

    2009-04-01

    The knowledge available regarding the influence of ultraviolet (UV) light on the atmospheric corrosion of materials is very rudimentary. Therefore, a new experimental setup consisting of a cell for studying in situ reactions occurring at the metal/atmosphere interface by simultaneously applying infrared reflection absorption spectroscopy (IRRAS) and quartz crystal microbalance (QCM) measurements was designed and built. The cell presented consists of an acrylic glass body with a UV-light-transparent window mounted in such a way that the sample can be irradiated and weathered under controlled atmospheric conditions under a grazing angle of incidence of the IR beam. This new setup was tested by using a specimen of polycrystalline silver, where the growth of Ag(2)CO(3) and AgOH as basic silver carbonate on the surface could be observed. The weathering tests were carried out in synthetic air containing 90% relative humidity (RH) and 250 ppm CO(2), with and without UV light. The results obtained from the IRRAS spectra could be perfectly correlated with the in situ QCM data.

  12. Graphene Plasmonic Metasurfaces to Steer Infrared Light.

    PubMed

    Li, Zubin; Yao, Kan; Xia, Fengnian; Shen, Sheng; Tian, Jianguo; Liu, Yongmin

    2015-07-23

    Metasurfaces utilizing engineered metallic nanostructures have recently emerged as an important means to manipulate the propagation of light waves in a prescribed manner. However, conventional metallic metasurfaces mainly efficiently work in the visible and near-infrared regime, and lack sufficient tunability. In this work, combining the pronounced plasmonic resonance of patterned graphene structures with a subwavelength-thick optical cavity, we propose and demonstrate novel graphene metasurfaces that manifest the potential to dynamically control the phase and amplitude of infrared light with very high efficiency. It is shown that the phase of the infrared light reflected from a simple graphene ribbon metasurface can span over almost the entire 2π range by changing the width of the graphene ribbons, while the amplitude of the reflection can be maintained at high values without significant variations. We successfully realize anomalous reflection, reflective focusing lenses, and non-diffracting Airy beams based on graphene metasurfaces. Our results open up a new paradigm of highly integrated photonic platforms for dynamic beam shaping and adaptive optics in the crucial infrared wavelength range.

  13. Lights, Camera, Reflection!

    ERIC Educational Resources Information Center

    Mourlam, Daniel

    2013-01-01

    There are many ways to critique teaching, but few are more effective than video. Personal reflection through the use of video allows one to see what really happens in the classrooms--good and bad--and provides a visual path forward for improvement, whether it be in one's teaching, work with a particular student, or learning environment. This…

  14. Estimating the absorption coefficient of the bottom layer in four-layered turbid mediums based on the time-domain depth sensitivity of near-infrared light reflectance.

    PubMed

    Sato, Chie; Shimada, Miho; Tanikawa, Yukari; Hoshi, Yoko

    2013-09-01

    Expanding our previously proposed "time segment analysis" for a two-layered turbid medium, this study attempted to selectively determine the absorption coefficient (μa) of the bottom layer in a four-layered human head model with time-domain near-infrared measurements. The difference curve in the temporal profiles of the light attenuation between an object and a reference medium, which are obtained from Monte Carlo simulations, is divided into segments along the time axis, and a slope for each segment is calculated to obtain the depth-dependent μa(μaseg). The reduced scattering coefficient (μs') of the reference is determined by curve fitting with the temporal point spread function derived from the analytical solution of the diffusion equation to the time-resolved reflectance of the object. The deviation of μaseg from the actual μa is expressed by a function of the ratio of μaseg in an earlier time segment to that in a later segment for mediums with different optical properties and thicknesses of the upper layers. Using this function, it is possible to determine the μa of the bottom layer in a four-layered epoxy resin-based phantom. These results suggest that the method reported here has potential for determining the μa of the cerebral tissue in humans.

  15. Improved Spatial Resolution For Reflection Mode Infrared Spectromicroscopy

    SciTech Connect

    Bechtel, Hans A; Martin, Michael C.; May, T. E.; Lerch, Philippe

    2009-08-13

    Standard commercial infrared microscopes operating in reflection mode use a mirror to direct the reflected light from the sample to the detector. This mirror blocks about half of the incident light, however, and thus degrades the spatial resolution by reducing the numerical aperture of the objective. Here, we replace the mirror with a 50% beamsplitter to allow full illumination of the objective and retain a way to direct the reflected light to the detector. The improved spatial resolution is demonstrated using a microscope coupled to a synchrotron source.

  16. Variable area light reflecting assembly

    DOEpatents

    Howard, Thomas C.

    1986-01-01

    Device for tracking daylight and projecting it into a building. The device tracks the sun and automatically adjusts both the orientation and area of the reflecting surface. The device may be mounted in either a wall or roof of a building. Additionally, multiple devices may be employed in a light shaft in a building, providing daylight to several different floors. The preferred embodiment employs a thin reflective film as the reflecting device. One edge of the reflective film is fixed, and the opposite end is attached to a spring-loaded take-up roller. As the sun moves across the sky, the take-up roller automatically adjusts the angle and surface area of the film. Additionally, louvers may be mounted at the light entrance to the device to reflect incoming daylight in an angle perpendicular to the device to provide maximum reflective capability when daylight enters the device at non-perpendicular angles.

  17. Variable area light reflecting assembly

    DOEpatents

    Howard, T.C.

    1986-12-23

    Device is described for tracking daylight and projecting it into a building. The device tracks the sun and automatically adjusts both the orientation and area of the reflecting surface. The device may be mounted in either a wall or roof of a building. Additionally, multiple devices may be employed in a light shaft in a building, providing daylight to several different floors. The preferred embodiment employs a thin reflective film as the reflecting device. One edge of the reflective film is fixed, and the opposite end is attached to a spring-loaded take-up roller. As the sun moves across the sky, the take-up roller automatically adjusts the angle and surface area of the film. Additionally, louvers may be mounted at the light entrance to the device to reflect incoming daylight in an angle perpendicular to the device to provide maximum reflective capability when daylight enters the device at non-perpendicular angles. 9 figs.

  18. Stray light in infrared detector

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Liu, Dafu; He, Xiangrong; Wang, Xiaokun; Zhang, Kefeng; Tang, Hengjing; Li, Tao

    2009-07-01

    Infrared optical system which has severe requirements on stray light levels often need cold shield around the detector. Some basic design principles and goals for baffles are presented. The location of vanes for cold shield are shown based on universal design criteria of baffle vane. Three different categories of vane designs for cold shield and their advantages for stray light control are discussed: one vane, two vanes and three vanes. The design of vane structure on cold shield surfaces is analyzed using the LIGHTTOOLS stray light software. The PST curves of cold shield without vane and with different vanes are given.

  19. Strength of mineral absorption features in the transmitted component of near-infrared reflected light - First results from RELAB. [spectrogoniometer for planetary and lunar surface composition experiments

    NASA Technical Reports Server (NTRS)

    Pieters, C. M.

    1983-01-01

    Bidirectional reflectance measurements are the only type of reflectance data available to the remote observer. For compositional interpretations, data are desired not only for identification of possible mineral components but also for modal abundance. The latter requires detailed information about the strength of absorption features. Using a new laboratory facility, the RELAB, laboratory data in the near infrared are presented that document effects of particle size, mineral mixtures, and viewing geometry for selected materials with well-developed absorption bands. The commonly observed increase in reflectance with decrease in particle size is also observed for absorption bands as well as a related decrease in absorption strength. For small particles in parts of the spectrum of maximum reflectance, however, a minor decrease in reflectance with a decrese in particle size is sometimes observed. Small particles dominate the observed characteristics of particulate surfaces, which contain a range of particle sizes. The mean optical path length (transmission through particles) of reflected radiation measured for a variety of particle sizes has an apparent upper limit of about 2 mm for particles of less than 250 microns. The typical number of particles involved in the optical path is less than 50.

  20. The near-infrared continuum emission of visual reflection nebulae

    NASA Technical Reports Server (NTRS)

    Sellgren, K.

    1984-01-01

    In the past, reflection nebulae have provided an astrophysical laboratory well suited for the study of the reflection properties of interstellar dust grains at visual and ultraviolet wavelengths. The present investigation is concerned with observations which were begun with the objective to extend to near-infrared wavelengths the study of grains in reflection. Observations of three classical visual reflection nebulae were conducted in the wavelength range from 1.25 to 2.2 microns, taking into account NGC 7023, 2023, and 2068. All three nebulae were found to have similar near-infrared colors, despite widely different colors of their illuminating stars. The brightness level shown by two of the nebulae at 2.2 microns was too high to be easily accounted for on the basis of reflected light. Attention is given to a wide variety of possible emission mechanisms.

  1. Infrared reflection nebulae in Orion Molecular Cloud 2

    NASA Technical Reports Server (NTRS)

    Pendleton, Yvonne; Werner, M. W.; Capps, R.; Lester, D.

    1986-01-01

    New observations of Orion Molecular Cloud 2 have been made from 1 to 100 microns using the NASA Infrared Telescope Facility and the Kuiper Airborne Observatory. An extensive program of polarimetry, photometry, and spectrophotometry has shown that the extended emission regions associated with two of the previously known near-infrared sources, IRS 1 and IRS 4, are infrared reflection nebulae, and that the compact sources IRS 1 and IRS 4 are the main luminosity sources in the cloud. The constraints from the far-infrared observations and an analysis of the scattered light from the IRS 1 nebula show that OMC-2/IRS 1 can be characterized by L of 500 solar luminosities or less and T of roughly 1000 K. The near-infrared albedo of the grains in the IRS 1 nebula is greater than 0.08.

  2. Infrared reflection nebulae in Orion molecular cloud 2

    NASA Technical Reports Server (NTRS)

    Pendleton, Y.; Werner, M. W.; Capps, R.; Lester, D.

    1986-01-01

    New obervations of Orion Molecular Cloud-2 have been made from 1-100 microns using the NASA Infrared Telescope Facility and the Kuiper Airborne Observatory. An extensive program of polarimetry, photometry and spectrophotometry has shown that the extended emission regions associated with two of the previously known near infrared sources, IRS1 and IRS4, are infrared reflection nebulae, and that the compact sources IRS1 and IRS4 are the main luminosity sources in the cloud. The constraints from the far infrared observations and an analysis of the scattered light from the IRS1 nebula show that OMC-2/IRS1 can be characterized by L less than or equal to 500 Solar luminosities and T approx. 1000 K. The near infrared (1-5) micron albedo of the grains in the IRS1 nebula is greater than 0.08.

  3. Studies of dust grain properties in infrared reflection nebulae.

    PubMed

    Pendleton, Y J; Tielens, A G; Werner, M W

    1990-01-20

    We have developed a model for reflection nebulae around luminous infrared sources embedded in dense dust clouds. The aim of this study is to determine the sizes of the scattering grains. In our analysis, we have adopted an MRN-like power-law size distribution (Mathis, Rumpl, and Nordsieck) of graphite and silicate grains, but other current dust models would give results which were substantially the same. In the optically thin limit, the intensity of the scattered light is proportional to the dust column density, while in the optically thick limit, it reflects the grain albedo. The results show that the shape of the infrared spectrum is the result of a combination of the scattering properties of the dust, the spectrum of the illuminating source, and foreground extinction, while geometry plays a minor role. Comparison of our model results with infrared observations of the reflection nebula surrounding OMC-2/IRS 1 shows that either a grain size distribution like that found in the diffuse interstellar medium, or one consisting of larger grains, can explain the observed shape of the spectrum. However, the absolute intensity level of the scattered light, as well as the observed polarization, requires large grains (approximately 5000 angstroms). By adding water ice mantles to the silicate and graphite cores, we have modeled the 3.08 micrometers ice band feature, which has been observed in the spectra of several infrared reflection nebulae. We show that this ice band arises naturally in optically thick reflection nebulae containing ice-coated grains. We show that the shape of the ice band is diagnostic of the presence of large grains, as previously suggested by Knacke and McCorkle. Comparison with observations of the BN/KL reflection nebula in the OMC-1 cloud shows that large ice grains (approximately 5000 angstroms) contribute substantially to the scattered light. PMID:11538693

  4. Studies of dust grain properties in infrared reflection nebulae.

    PubMed

    Pendleton, Y J; Tielens, A G; Werner, M W

    1990-01-20

    We have developed a model for reflection nebulae around luminous infrared sources embedded in dense dust clouds. The aim of this study is to determine the sizes of the scattering grains. In our analysis, we have adopted an MRN-like power-law size distribution (Mathis, Rumpl, and Nordsieck) of graphite and silicate grains, but other current dust models would give results which were substantially the same. In the optically thin limit, the intensity of the scattered light is proportional to the dust column density, while in the optically thick limit, it reflects the grain albedo. The results show that the shape of the infrared spectrum is the result of a combination of the scattering properties of the dust, the spectrum of the illuminating source, and foreground extinction, while geometry plays a minor role. Comparison of our model results with infrared observations of the reflection nebula surrounding OMC-2/IRS 1 shows that either a grain size distribution like that found in the diffuse interstellar medium, or one consisting of larger grains, can explain the observed shape of the spectrum. However, the absolute intensity level of the scattered light, as well as the observed polarization, requires large grains (approximately 5000 angstroms). By adding water ice mantles to the silicate and graphite cores, we have modeled the 3.08 micrometers ice band feature, which has been observed in the spectra of several infrared reflection nebulae. We show that this ice band arises naturally in optically thick reflection nebulae containing ice-coated grains. We show that the shape of the ice band is diagnostic of the presence of large grains, as previously suggested by Knacke and McCorkle. Comparison with observations of the BN/KL reflection nebula in the OMC-1 cloud shows that large ice grains (approximately 5000 angstroms) contribute substantially to the scattered light.

  5. Extended near-infrared emission from visual reflection nebulae

    NASA Technical Reports Server (NTRS)

    Sellgren, K.; Werner, M. W.; Dinerstein, H. L.

    1983-01-01

    Extended near infrared (2 to 5 microns) emission was observed from three visual reflection nebulae, NGC 7023, 2023, and 2068. The emission from each nebula consists of a smooth continuum, which can be described by a greybody with a color temperature of 1000 K, and emission features at 3.3 and 3.4 microns. The continuum emission cannot be explained by free-free emission, reflected light, or field stars, or by thermal emission from grains, with commonly accepted ratios of infrared to ultraviolet emissivities, which are in equilibrium with the stellar radiation field. A possible explanation is thermal emission from grains with extremely low ratios of infrared to ultraviolet emissivities, or from grains with a temperature determined by mechanisms other than equilibrium radiative heating. Another possibility is continuum fluorescence. Previously announced in STAR N83-25629

  6. Extended near infrared emission from visual reflection nebulae

    NASA Technical Reports Server (NTRS)

    Sellgren, K.; Werner, M. W.; Dinerstein, H. L.

    1982-01-01

    Extended near infrared (2 to 5 microns) emission was observed from three visual reflection nebulae, NGC 7023, 2023, and 2068. The emission from each nebula consists of a smooth continuum, which can be described by a greybody with a color temperature of 1000 K, and emission features at 3.3 and 3.4 microns. The continuum emission cannot be explained by free-free emission, reflected light, or field stars, or by thermal emission from grains, with commonly accepted ratios of infrared to ultraviolet emissivities, which are in equilibrium with the stellar radiation field. A possible explanation is thermal emission from grains with extremely low ratios of infrared to ultraviolet emissivities, or from grains with a temperature determined by mechanisms other than equilibrium radiative heating. Another possibility is continuum fluorescence.

  7. Improved Spatial Resolution for Reflection Mode Infrared Microscopy

    SciTech Connect

    Bechtel, Hans A.; Martin, Michael C.; May, T.E.; Lerch, Philippe

    2009-10-09

    Standard commercial infrared microscopes operating in reflection mode use a mirror to direct the reflected light from the sample to the detector. This mirror blocks about half of the incident light, however, and thus degrades the spatial resolution by reducing the umerical aperture of the objective. Here, we replace the mirror with a 50% beamsplitter to allow full illumination of the objective and retain a way to direct the reflected light to the detector. The improved spatial resolution is demonstrated using two different microscopes apable of diffraction-limited resolution: the first microscope is coupled to a synchrotron source and utilizes a single point detector, whereas the second microscope has a standard blackbody source and uses a focal planetarray (FPA) detector.

  8. Value of Reflected Light Microscopy in Teaching.

    ERIC Educational Resources Information Center

    Pasteris, Jill Dill

    1983-01-01

    Briefly reviews some optical and other physical properties of minerals that can be determined in reflected/incident light. Topics include optical properties of minerals, reflectance, internal reflections, color, bireflectance and reflection pleochroism, anisotropism, zonation, and reflected light microscopy as a teaching tool in undergraduate…

  9. Pigments which reflect infrared radiation from fire

    DOEpatents

    Berdahl, P.H.

    1998-09-22

    Conventional paints transmit or absorb most of the intense infrared (IR) radiation emitted by fire, causing them to contribute to the spread of fire. The present invention comprises a fire retardant paint additive that reflects the thermal IR radiation emitted by fire in the 1 to 20 micrometer ({micro}m) wavelength range. The important spectral ranges for fire control are typically about 1 to about 8 {micro}m or, for cool smoky fires, about 2 {micro}m to about 16 {micro}m. The improved inventive coatings reflect adverse electromagnetic energy and slow the spread of fire. Specific IR reflective pigments include titanium dioxide (rutile) and red iron oxide pigments with diameters of about 1 {micro}m to about 2 {micro}m and thin leafing aluminum flake pigments. 4 figs.

  10. Pigments which reflect infrared radiation from fire

    DOEpatents

    Berdahl, Paul H.

    1998-01-01

    Conventional paints transmit or absorb most of the intense infrared (IR) radiation emitted by fire, causing them to contribute to the spread of fire. The present invention comprises a fire retardant paint additive that reflects the thermal IR radiation emitted by fire in the 1 to 20 micrometer (.mu.m) wavelength range. The important spectral ranges for fire control are typically about 1 to about 8 .mu.m or, for cool smoky fires, about 2 .mu.m to about 16 .mu.m. The improved inventive coatings reflect adverse electromagnetic energy and slow the spread of fire. Specific IR reflective pigments include titanium dioxide (rutile) and red iron oxide pigments with diameters of about 1 .mu.m to about 2 .mu.m and thin leafing aluminum flake pigments.

  11. Infrared studies of dust grains in infrared reflection nebulae

    NASA Technical Reports Server (NTRS)

    Pendleton, Yvonne J.; Tielens, Alexander G. G. M.; Werner, Michael W.

    1989-01-01

    IR reflection nebulae, regions of dust which are illuminated by nearby embedded sources, were observed in several regions of ongoing star formation. Near IR observation and theoretical modelling of the scattered light form IR reflection nebulae can provide information about the dust grain properties in star forming regions. IR reflection nebulae were modelled as plane parallel slabs assuming isotropically scattering grains. For the grain scattering properties, graphite and silicate grains were used with a power law grain size distribution. Among the free parameters of the model are the stellar luminosity and effective temperature, the optical depth of the nebula, and the extinction by foreground material. The typical results from this model are presented and discussed.

  12. Infrared reflectance spectra: effects of particle size, provenance and preparation

    NASA Astrophysics Data System (ADS)

    Su, Yin-Fong; Myers, Tanya L.; Brauer, Carolyn S.; Blake, Thomas A.; Forland, Brenda M.; Szecsody, J. E.; Johnson, Timothy J.

    2014-10-01

    We have recently developed methods for making more accurate infrared total and diffuse directional - hemispherical reflectance measurements using an integrating sphere. We have found that reflectance spectra of solids, especially powders, are influenced by a number of factors including the sample preparation method, the particle size and morphology, as well as the sample origin. On a quantitative basis we have investigated some of these parameters and the effects they have on reflectance spectra, particularly in the longwave infrared. In the IR the spectral features may be observed as either maxima or minima: In general, upward-going peaks in the reflectance spectrum result from strong surface scattering, i.e. rays that are reflected from the surface without bulk penetration, whereas downward-going peaks are due to either absorption or volume scattering, i.e. rays that have penetrated or refracted into the sample interior and are not reflected. The light signals reflected from solids usually encompass all such effects, but with strong dependencies on particle size and preparation. This paper measures the reflectance spectra in the 1.3 - 16 micron range for various bulk materials that have a combination of strong and weak absorption bands in order to observe the effects on the spectral features: Bulk materials were ground with a mortar and pestle and sieved to separate the samples into various size fractions between 5 and 500 microns. The median particle size is demonstrated to have large effects on the reflectance spectra. For certain minerals we also observe significant spectral change depending on the geologic origin of the sample. All three such effects (particle size, preparation and provenance) result in substantial change in the reflectance spectra for solid materials; successful identification algorithms will require sufficient flexibility to account for these parameters.

  13. Infrared reflectance spectra: Effects of particle size, provenance and preparation

    SciTech Connect

    Su, Yin-Fong; Myers, Tanya L.; Brauer, Carolyn S.; Blake, Thomas A.; Forland, Brenda M.; Szecsody, James E.; Johnson, Timothy J.

    2014-09-22

    We have recently developed methods for making more accurate infrared total and diffuse directional - hemispherical reflectance measurements using an integrating sphere. We have found that reflectance spectra of solids, especially powders, are influenced by a number of factors including the sample preparation method, the particle size and morphology, as well as the sample origin. On a quantitative basis we have investigated some of these parameters and the effects they have on reflectance spectra, particularly in the longwave infrared. In the IR the spectral features may be observed as either maxima or minima: In general, upward-going peaks in the reflectance spectrum result from strong surface scattering, i.e. rays that are reflected from the surface without bulk penetration, whereas downward-going peaks are due to either absorption or volume scattering, i.e. rays that have penetrated or refracted into the sample interior and are not reflected. The light signals reflected from solids usually encompass all such effects, but with strong dependencies on particle size and preparation. This paper measures the reflectance spectra in the 1.3 – 16 micron range for various bulk materials that have a combination of strong and weak absorption bands in order to observe the effects on the spectral features: Bulk materials were ground with a mortar and pestle and sieved to separate the samples into various size fractions between 5 and 500 microns. The median particle size is demonstrated to have large effects on the reflectance spectra. For certain minerals we also observe significant spectral change depending on the geologic origin of the sample. All three such effects (particle size, preparation and provenance) result in substantial change in the reflectance spectra for solid materials; successful identification algorithms will require sufficient flexibility to account for these parameters.

  14. Monitoring hemodynamic and morphologic responses to closed head injury in a mouse model using orthogonal diffuse near-infrared light reflectance spectroscopy

    NASA Astrophysics Data System (ADS)

    Abookasis, David; Shochat, Ariel; Mathews, Marlon S.

    2013-04-01

    The authors' aim is to assess and quantitatively measure brain hemodynamic and morphological variations during closed-head injury (CHI) in mice using orthogonal diffuse near-infrared reflectance spectroscopy (o-DRS). CHI is a type of injury to the head that does not penetrate the skull. Usually, it is caused by mechanical blows to the head and frequently occurs in traffic accidents, falls, and assaults. Measurements of brain optical properties, namely absorption and reduced scattering coefficients in the wavelength range from 650 to 1000 nm were carried out by employing different source-detector distance and locations to provide depth sensitivity on an intact scalp over the duration of the whole experiment. Furthermore, alteration in both cortical hemodynamics and morphologic markers, i.e., scattering power and amplitude properties were derived. CHI was induced in anesthetized male mice by a weight-drop model using ˜50 g cylindrical metal falling from a height of 90 cm onto the intact scalp producing an impact of 4500 g cm. With respect to baseline, difference in brain physiological properties was observed following injury up to 1 h post-trauma. Additionally, the reduced scattering spectral shapes followed Mie scattering theory was quantified and clearly shows changes in both scattering amplitude and power from baseline indicating structural variations likely from evolving cerebral edema during CHI. We further demonstrate high correlation between scattering amplitude and scattering power, with more than 20% difference in slope in comparison to preinjury. This result indicates the possibility of using the slope also as a marker for detection of structural changes. Finally, experiments investigating brain function during the first 20 min postinjury were conducted and changes in chromophore concentrations and scattering were observed. Overall, our experiments demonstrate the potential of using the proposed technique as a valuable quantitative noninvasive tool for

  15. The Influence of Particle Size on Infrared Reflectance Spectra

    SciTech Connect

    Myers, Tanya L.; Brauer, Carolyn S.; Su, Yin-Fong; Blake, Thomas A.; Johnson, Timothy J.; Richardson, Robert L.

    2014-06-13

    Reflectance spectra of solids are influenced by the absorption coefficient as well as the particle size and morphology. In the infrared, spectral features may be observed as either maxima or minima: in general, the upward-going peaks in the reflectance spectrum result from surface scattering, which are rays that have reflected from the surface without penetration, whereas downward-going peaks result from either absorption or volume scattering, i.e. rays that have penetrated into the sample or refracted into the sample interior and are not reflected. The light signal reflected from solids usually encompasses all these effects which include dependencies on particle size, morphology and sample density. This paper measures the reflectance spectra in the 1.3 – 16 micron range for various bulk materials that have a combination of strong and weak absorption bands in order to understand the effects on the spectral features as a function of the mean grain size of the sample. The bulk materials were ground with a mortar and pestle and then sieved to separate the samples into various size fractions: 0-45, 45-90, 90-180, 180-250, 250-500, and >500 microns. The directional-hemispherical spectra were recorded using a Fourier transform infrared spectrometer equipped with an integrating sphere to measure the reflectance for all of the particle-size fractions. We have studied both organic and inorganic materials, but this paper focuses on inorganic salts, NaNO3 in particular. Our studies clearly show that particle size has an enormous influence on the measured reflectance spectra for bulk materials and that successful identification requires sufficient representative reflectance data so as to include the particle size(s) of interest. Origins of the effects are discussed.

  16. Transmitting and reflecting diffuser. [for ultraviolet light

    NASA Technical Reports Server (NTRS)

    Keafer, L. S., Jr.; Burcher, E. E.; Kopia, L. P. (Inventor)

    1973-01-01

    A near-Lambertian diffuser is described which transmits and reflects ultraviolet light. An ultraviolet grade fused silica substrate is coated with vaporized fuse silica. The coating thickness is controlled, one thickness causing ultraviolet light to diffuse and another thickness causing ultraviolet light to reflect a near Lambertian pattern.

  17. Photovoltaic module with light reflecting backskin

    DOEpatents

    Gonsiorawski, Ronald C.

    2007-07-03

    A photovoltaic module comprises electrically interconnected and mutually spaced photovoltaic cells that are encapsulated by a light-transmitting encapsulant between a light-transparent front cover and a back cover, with the back cover sheet being an ionomer/nylon alloy embossed with V-shaped grooves running in at least two directions and coated with a light reflecting medium so as to provide light-reflecting facets that are aligned with the spaces between adjacent cells and oriented so as to reflect light falling in those spaces back toward said transparent front cover for further internal reflection onto the solar cells, whereby substantially all of the reflected light will be internally reflected from said cover sheet back to the photovoltaic cells, thereby increasing the current output of the module. The internal reflector improves power output by as much as 67%.

  18. Dispersion effects on infrared spectra in attenuated total reflection

    NASA Astrophysics Data System (ADS)

    Belali, Rabah; Vigoureux, Jean-Marie; Morvan, Joseph

    1995-12-01

    A potential problem with the attenuated total reflection that is used to measure infrared spectra is described. The problem is the possibility that the anomalous dispersion associated with an infrared absorption band may cause the experimental configuration to move from the attenuated total reflection regime to the specular reflection regime, with consequent distortion of the apparent absorption bands and consequent error in the interpretation of the bands if the problem is not recognized. Key infrared spectra, attenuated total reflection, specular reflection, polyethylene terephtalate. Copyright (c) 1995 Optical Society of America

  19. Studies of the Reflection, Refraction and Internal Reflection of Light

    ERIC Educational Resources Information Center

    Lanchester, P. C.

    2014-01-01

    An inexpensive apparatus and associated experiments are described for studying the basic laws of reflection and refraction of light at an air-glass interface, and multiple internal reflections within a glass block. In order to motivate students and encourage their active participation, a novel technique is described for determining the refractive…

  20. Infrared light sources with semimetal electron injection

    DOEpatents

    Kurtz, Steven R.; Biefeld, Robert M.; Allerman, Andrew A.

    1999-01-01

    An infrared light source is disclosed that comprises a layered semiconductor active region having a semimetal region and at least one quantum-well layer. The semimetal region, formed at an interface between a GaAsSb or GalnSb layer and an InAsSb layer, provides electrons and holes to the quantum-well layer to generate infrared light at a predetermined wavelength in the range of 2-6 .mu.m. Embodiments of the invention can be formed as electrically-activated light-emitting diodes (LEDs) or lasers, and as optically-pumped lasers. Since the active region is unipolar, multiple active regions can be stacked to form a broadband or multiple-wavelength infrared light source.

  1. Infrared-Bolometer Arrays with Reflective Backshorts

    NASA Technical Reports Server (NTRS)

    Miller, Timothy M.; Abrahams, John; Allen, Christine A.

    2011-01-01

    Integrated circuits that incorporate square arrays of superconducting-transition- edge bolometers with optically reflective backshorts are being developed for use in image sensors in the spectral range from far infrared to millimeter wavelengths. To maximize the optical efficiency (and, thus, sensitivity) of such a sensor at a specific wavelength, resonant optical structures are created by placing the backshorts at a quarter wavelength behind the bolometer plane. The bolometer and backshort arrays are fabricated separately, then integrated to form a single unit denoted a backshort-under-grid (BUG) bolometer array. In a subsequent fabrication step, the BUG bolometer array is connected, by use of single-sided indium bump bonding, to a readout device that comprises mostly a superconducting quantum interference device (SQUID) multiplexer circuit. The resulting sensor unit comprising the BUG bolometer array and the readout device is operated at a temperature below 1 K. The concept of increasing optical efficiency by use of backshorts at a quarter wavelength behind the bolometers is not new. Instead, the novelty of the present development lies mainly in several features of the design of the BUG bolometer array and the fabrication sequence used to implement the design. Prior to joining with the backshort array, the bolometer array comprises, more specifically, a square grid of free-standing molybdenum/gold superconducting-transition-edge bolometer elements on a 1.4- m-thick top layer of silicon that is part of a silicon support frame made from a silicon-on-insulator wafer. The backshort array is fabricated separately as a frame structure that includes support beams and contains a correspond - ing grid of optically reflective patches on a single-crystal silicon substrate. The process used to fabricate the bolometer array includes standard patterning and etching steps that result in the formation of deep notches in the silicon support frame. These notches are designed to

  2. [Near infrared light irradiator using halogen lamp].

    PubMed

    Ide, Yasuo

    2012-07-01

    The practical electric light bulb was invented by Thomas Alva Edison in 1879. Halogen lamp is the toughest and brightest electric light bulb. With light filter, it is used as a source of near infrared light. Super Lizer and Alphabeam are made as near infrared light irradiator using halogen lamp. The light emmited by Super Lizer is linear polarized near infrared light. The wave length is from 600 to 1,600 nm and strongest at about 1,000 nm. Concerning Super Lizer, there is evidence of analgesic effects and normalization of the sympathetic nervous system. Super Lizer has four types of probes. SG type is used for stellate ganglion irradiation. B type is used for narrow area irradiation. C and D types are for broad area irradiation. The output of Alphabeam is not polarized. The wave length is from 700 to 1,600 nm and the strongest length is about 1,000nm. Standard attachment is used for spot irradiation. Small attachment is used for stellate ganglion irradiation. Wide attachment is used for broad area irradiation. The effects of Alphabeam are thought to be similar to that of Super Lizer.

  3. [Near infrared light irradiator using halogen lamp].

    PubMed

    Ide, Yasuo

    2012-07-01

    The practical electric light bulb was invented by Thomas Alva Edison in 1879. Halogen lamp is the toughest and brightest electric light bulb. With light filter, it is used as a source of near infrared light. Super Lizer and Alphabeam are made as near infrared light irradiator using halogen lamp. The light emmited by Super Lizer is linear polarized near infrared light. The wave length is from 600 to 1,600 nm and strongest at about 1,000 nm. Concerning Super Lizer, there is evidence of analgesic effects and normalization of the sympathetic nervous system. Super Lizer has four types of probes. SG type is used for stellate ganglion irradiation. B type is used for narrow area irradiation. C and D types are for broad area irradiation. The output of Alphabeam is not polarized. The wave length is from 700 to 1,600 nm and the strongest length is about 1,000nm. Standard attachment is used for spot irradiation. Small attachment is used for stellate ganglion irradiation. Wide attachment is used for broad area irradiation. The effects of Alphabeam are thought to be similar to that of Super Lizer. PMID:22860296

  4. Infrared light field imaging using single carbon nanotube detector

    NASA Astrophysics Data System (ADS)

    Xi, Ning; Chen, Liangliang; Zhou, Zhanxin; Yang, Ruiguo; Song, Bo; Sun, Zhiyong

    2014-06-01

    The conventional photographs only record the sum total of light rays of each point on image plane so that they tell little about the amount of light traveling along individual rays. The focus and lens aberration problems have challenged photographers since the very beginning therefore light field photography was proposed to solve these problems. Lens array and multiple camera systems are used to capture 4D light rays, by reordering the different views of scene from multiple directions. The coded aperture is another method to encode the angular information in frequency domain. However, infrared light field sensing is still widely opening to research. In the paper, we will propose micro plane mirror optics together with compressive sensing algorithm to record light field in infrared spectrum. The micro mirror reflects objects irradiation and forms a virtual image behind the plane in which the mirror lies. The Digital Micromirror (DMD) consists of millions microscale mirrors which work as CCD array in the camera and it is controlled separately so as to project linear combination of object image onto lens. Coded aperture could be utilized to control angular resolution of infrared light rays. The carbon nanotube based infrared detector, which has ultra high signal to noise ratio and ultra fast responsibility, will sum up all image information on it without image distortion. Based on a number of measurements, compressive sensing algorithm was used to recover images from distinct angles, which could compute different views of scene to reconstruct infrared light field scence. Two innovative applications of full image recovery using nano scale photodetector and DMD based synthetic aperture photography will also be discussed in this paper.

  5. Non-collinear upconversion of infrared light.

    PubMed

    Pedersen, Christian; Hu, Qi; Høgstedt, Lasse; Tidemand-Lichtenberg, Peter; Dam, Jeppe Seidelin

    2014-11-17

    Two dimensional mid-infrared upconversion imaging provides unique spectral and spatial information showing good potential for mid-infrared spectroscopy and hyperspectral imaging. However, to extract spectral or spatial information from the upconverted images an elaborate model is needed, which includes non-collinear interaction. We derive here a general theory providing the far field of the upconverted light when two arbitrary fields interact inside a nonlinear crystal. Theoretical predictions are experimentally verified for incoherent radiation and subsequently applied to previously published data with good agreement.

  6. Cosmic Infrared Background Fluctuations and Zodiacal Light

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

    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 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 ˜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 (≳100″) 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.

  7. Forensic applications of microscopical infrared internal reflection spectroscopy

    NASA Astrophysics Data System (ADS)

    Tungol, Mary W.; Bartick, Edward G.; Reffner, John A.

    1994-01-01

    Applications of microscopical infrared internal reflection spectroscopy in forensic science are discussed. Internal reflection spectra of single fibers, hairs, paint chips, vehicle rubber bumpers, photocopy toners, carbon copies, writing ink on paper, lipstick on tissue, black electrical tape, and other types of forensic evidence have been obtained. The technique is convenient, non-destructive, and may permit smeared materials to be analyzed in situ.

  8. Light distribution modulated diffuse reflectance spectroscopy.

    PubMed

    Huang, Pin-Yuan; Chien, Chun-Yu; Sheu, Chia-Rong; Chen, Yu-Wen; Tseng, Sheng-Hao

    2016-06-01

    Typically, a diffuse reflectance spectroscopy (DRS) system employing a continuous wave light source would need to acquire diffuse reflectances measured at multiple source-detector separations for determining the absorption and reduced scattering coefficients of turbid samples. This results in a multi-fiber probe structure and an indefinite probing depth. Here we present a novel DRS method that can utilize a few diffuse reflectances measured at one source-detector separation for recovering the optical properties of samples. The core of innovation is a liquid crystal (LC) cell whose scattering property can be modulated by the bias voltage. By placing the LC cell between the light source and the sample, the spatial distribution of light in the sample can be varied as the scattering property of the LC cell modulated by the bias voltage, and this would induce intensity variation of the collected diffuse reflectance. From a series of Monte Carlo simulations and phantom measurements, we found that this new light distribution modulated DRS (LDM DRS) system was capable of accurately recover the absorption and scattering coefficients of turbid samples and its probing depth only varied by less than 3% over the full bias voltage variation range. Our results suggest that this LDM DRS platform could be developed to various low-cost, efficient, and compact systems for in-vivo superficial tissue investigation. PMID:27375931

  9. Light distribution modulated diffuse reflectance spectroscopy

    PubMed Central

    Huang, Pin-Yuan; Chien, Chun-Yu; Sheu, Chia-Rong; Chen, Yu-Wen; Tseng, Sheng-Hao

    2016-01-01

    Typically, a diffuse reflectance spectroscopy (DRS) system employing a continuous wave light source would need to acquire diffuse reflectances measured at multiple source-detector separations for determining the absorption and reduced scattering coefficients of turbid samples. This results in a multi-fiber probe structure and an indefinite probing depth. Here we present a novel DRS method that can utilize a few diffuse reflectances measured at one source-detector separation for recovering the optical properties of samples. The core of innovation is a liquid crystal (LC) cell whose scattering property can be modulated by the bias voltage. By placing the LC cell between the light source and the sample, the spatial distribution of light in the sample can be varied as the scattering property of the LC cell modulated by the bias voltage, and this would induce intensity variation of the collected diffuse reflectance. From a series of Monte Carlo simulations and phantom measurements, we found that this new light distribution modulated DRS (LDM DRS) system was capable of accurately recover the absorption and scattering coefficients of turbid samples and its probing depth only varied by less than 3% over the full bias voltage variation range. Our results suggest that this LDM DRS platform could be developed to various low-cost, efficient, and compact systems for in-vivo superficial tissue investigation. PMID:27375931

  10. Red and near-infrared spectral reflectance of snow

    NASA Technical Reports Server (NTRS)

    Obrien, H. W.; Munis, R. H.

    1975-01-01

    The spectral reflectance of snow in the range of 0.60 to 2.50 microns wavelengths was studied in a cold laboratory using natural snow and simulated preparations of snow. A white barium sulfate powder was used as the standard for comparison. The high reflectance (usually nearly 100%) of fresh natural snow in visible wavelengths declines rapidly at wavelengths longer than the visible, as the spectral absorption coefficients of ice increase. Aging snow becomes only somewhat less reflective than fresh snow in the visible region and usually retains a reflectance greater than 80%. In the near infrared, aging snow tends to become considerably less reflective than fresh snow.

  11. Infrared reflectance of high altitude clouds.

    PubMed

    Hovis, W A; Blaine, L R; Forman, M L

    1970-03-01

    The spectral reflectance characteristics of cirrostratus, cirrus clouds, and a jet contrail, in the 0.68-2.4-micro spectral interval, are of interest for remote sensing of cloud types from orbiting satellites. Measurements made with a down-looking spectrometer from a high altitude aircraft show differences between the signatures of naturally formed ice clouds, a fresh jet contrail, and a snow covered surface.

  12. Capabilities and Limitations of Infrared Reflectance Microspectroscopy

    NASA Technical Reports Server (NTRS)

    Klima, R. L.; Pieters, C. M.

    2005-01-01

    Technological improvements in IR microspectroscopy have made it an increasingly appealing tool for planetary mineralogy. Microspectroscopy presents the prospect of examining small samples nondestructively and acquiring spectra that can be related to remote sensing observations. However, complications are introduced as a target beam size is reduced, and it is critical that limitations are understood. We present the results of a series of well constrained spectroscopic measurements, linking microspectroscopic data to traditionally collected reflectance spectra and petrologic information for the same rock.

  13. Near-infrared light photoacoustic ophthalmoscopy

    PubMed Central

    Liu, Tan; Wei, Qing; Song, Wei; Burke, Janice M.; Jiao, Shuliang; Zhang, Hao F.

    2012-01-01

    We achieved photoacoustic ophthalmoscopy (PAOM) imaging of the retina with near-infrared (NIR) light illumination. A PAOM imaging system with dual-wavelength illumination at 1064 nm and 532 nm was built. We compared in vivo imaging results of both albino and pigmented rat eyes at the two wavelengths. The results show that the bulk optical absorption of the retinal pigment epithelium (RPE) is only slightly higher than that of the retinal vessels at 532 nm while it becomes more than an order of magnitude higher than that of the retinal vessels at 1064 nm. These studies suggest that although visible light illumination is suitable for imaging both the retinal vessels and the RPE, NIR light illumination, being more comfortable to the eye, is better suited for RPE melanin related investigations and diagnoses. PMID:22574266

  14. Venus in Violet and Near Infrared Light

    NASA Technical Reports Server (NTRS)

    1990-01-01

    These images of the Venus clouds were taken by Galileo's Solid State Imaging System February 13,1990, at a range of about 1 million miles. The smallest detail visible is about 20 miles. The two right images show Venus in violet light, the top one at a time six hours later than the bottom one. They show the state of the clouds near the top of Venus's cloud deck. A right to left motion of the cloud features is evident and is consistent with westward winds of about 230 mph. The two left images show Venus in near infrared light, at the same times as the two right images. Sunlight penetrates through the clouds more deeply at the near infrared wavelengths, allowing a view near the bottom of the cloud deck. The westward motion of the clouds is slower (about 150 mph) at the lower altitude. The clouds are composed of sulfuric acid droplets and occupy a range of altitudes from 30 to 45 miles. The images have been spatially filtered to bring out small scale details and de-emphasize global shading. The filtering has introduced artifacts (wiggly lines running north/south) that are faintly visible in the infrared image. The Galileo Project is managed for NASA's Office of Space Science and Applications by the Jet Propulsion Laboratory; its mission is to study Jupiter and its satellites and magnetosphere after multiple gravity assist flybys at Venus and Earth.

  15. Measuring Light Reflectance of BGO Crystal Surfaces

    SciTech Connect

    Janecek, Martin; Moses, William

    2008-07-28

    A scintillating crystal's surface reflectance has to be well understood in order to accurately predict and optimize the crystal?s light collection through Monte Carlo simulations. In this paper, we measure the inner surface reflectance properties for BGO. The measurements include BGO crystals with a mechanically polished surface, rough-cut surface, and chemically etched surface, and with various reflectors attached, both air- coupled and with coupling compound. The measurements are performed with a laser aimed at the center of a hemispherical shaped BGO crystal. The hemispherical shape eliminates any non-perpendicular angles for light entering and exiting the crystal. The reflected light is collected with an array of photodiodes. The laser can be set at an arbitrary angle, and the photodiode array is rotated to fully cover 2? of solid angle. The current produced in the photodiodes is readout with a digital multimeter connected through a multiplexer. The two rows of photodiodes achieve 5-degree by 4-degree resolution, and the current measurement has a dynamic range of 10^5:1. The acquired data was not described by the commonly assumed linear combination of specular and diffuse (Lambertian) distributions, except for a very few surfaces. Surface roughness proved to be the most important parameter when choosing crystal setup. The reflector choice was of less importance and of almost no consequence for rough-cut surfaces. Pure specular reflection distribution for all incidence angles was measured for polished surfaces with VM2000 film, while the most Lambertian distribution for any surface finish was measured for titanium dioxide paint. The distributions acquired in this paper will be used to create more accurate Monte Carlo models for light reflection distribution within BGO crystals.

  16. Infrared reflectivity studies of quasi-two dimensional molybdenum oxides Mo 4O 11

    NASA Astrophysics Data System (ADS)

    Guyot, H.; Al Khoury, E.; Marcus, J.; Schlenker, C.; Banville, M.; Jandl, S.

    1991-07-01

    Infrared reflectivity of the quasi-two dimensional oxides η-Mo 4O 11, has been investigated on single crystals, using polarized light, in the range of 300 - 4000 cm -1, at room temperature and in the charge density wave (CDW) state. At 300 K, the anisotropy of the reflectivity emphasizes the anisotropy of the conduction electron gas, with a metallic behavior within the (100) plane and a semiconducting behavior in the [100] direction. In this direction, the IR reflectivity is fitted with the phonon oscillators. At low temperature, the decrease of the IR reflectivity is consistent with the loss of carriers, induced by the CDW gap opening.

  17. Infrared spectra of lunar soil analogs. [spectral reflectance of minerals

    NASA Technical Reports Server (NTRS)

    Aronson, J. R.

    1977-01-01

    The infrared spectra of analogs of lunar soils were investigated to further the development of methodology for interpretation of remotely measured infrared spectra of the lunar surface. The optical constants of dunite, bytownite, augite, ilmenite, and a mare glass analog were obtained. The infrared emittance spectra of powdered minerals were measured and compared with spectra calculated by the reflectance theory using a catalog of optical constants. The results indicate that the predictions of the theory closely simulate the experimental measurements if the optical constants are properly derived.

  18. Mid-Infrared Reflectance Imaging of Thermal-Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Edlridge, Jeffrey I.; Martin, Richard E.

    2009-01-01

    An apparatus for mid-infrared reflectance imaging has been developed as means of inspecting for subsurface damage in thermal-barrier coatings (TBCs). The apparatus is designed, more specifically, for imaging the progression of buried delamination cracks in plasma-sprayed yttria-stabilized zirconia coatings on turbine-engine components. Progression of TBC delamination occurs by the formation of buried cracks that grow and then link together to produce eventual TBC spallation. The mid-infrared reflectance imaging system described here makes it possible to see delamination progression that is invisible to the unaided eye, and therefore give sufficiently advanced warning before delamination progression adversely affects engine performance and safety. The apparatus (see figure) includes a commercial mid-infrared camera that contains a liquid-nitrogen-cooled focal plane indium antimonide photodetector array, and imaging is restricted by a narrow bandpass centered at wavelength of 4 microns. This narrow wavelength range centered at 4 microns was chosen because (1) it enables avoidance of interfering absorptions by atmospheric OH and CO2 at 3 and 4.25 microns, respectively; and (2) the coating material exhibits maximum transparency in this wavelength range. Delamination contrast is produced in the midinfrared reflectance images because the introduction of cracks into the TBC creates an internal TBC/air-gap interface with a high diffuse reflectivity of 0.81, resulting in substantially higher reflectance of mid-infrared radiation in regions that contain buried delamination cracks. The camera is positioned a short distance (.12 cm) from the specimen. The mid-infrared illumination is generated by a 50-watt silicon carbide source positioned to the side of the mid-infrared camera, and the illumination is collimated and reflected onto the specimen by a 6.35-cm-diameter off-axis paraboloidal mirror. Because the collected images are of a steady-state reflected intensity (in

  19. Light reflecting apparatus including a multi-aberration light reflecting surface

    DOEpatents

    Sawicki, Richard H.; Sweatt, William

    1987-01-01

    A light reflecting apparatus including a multi-aberration bendable light reflecting surface is disclosed herein. This apparatus includes a structural assembly comprised of a rectangular plate which is resiliently bendable, to a limited extent, and which has a front side defining the multi-aberration light reflecting surface and an opposite back side, and a plurality of straight leg members rigidly connected with the back side of the plate and extending rearwardly therefrom. The apparatus also includes a number of different adjustment mechanisms, each of which is connected with specific ones of the leg members. These mechanisms are adjustably movable in different ways for applying corresponding forces to the leg members in order to bend the rectangular plate and light reflecting surface into different predetermined curvatures and which specifically include quadratic and cubic curvatures corresponding to different optical aberrations.

  20. A light reflecting apparatus including a multi-aberration light reflecting surface

    DOEpatents

    Sawicki, R.H.; Sweatt, W.

    1985-11-21

    A light reflecting apparatus including a multi-aberration bendable light reflecting surface is disclosed herein. This apparatus includes a structural assembly comprised of a rectangular plate which is resiliently bendable, to a limited extent, and which has a front side defining the multi-aberration light reflecting surface and an opposite back side, and a plurality of straight leg members rigidly connected with the back side of the plate and extending rearwardly therefrom. The apparatus also includes a number of different adjustment mechanisms, each of which is connected with specific ones of the leg members. These mechanisms are adjustably movable in different ways for applying corresponding forces to the leg members in order to bend the rectangular plate and light reflecting surface into different predetermined curvatures and which specifically include quadratic and cubic curvatures corresponding to different optical aberrations.

  1. Sombrero Galaxy (M104) in Infrared Light

    NASA Technical Reports Server (NTRS)

    2003-01-01

    The razor sharp eye of the Hubble Space Telescope (HST) easily resolves the Sombrero galaxy, Messier 104 (M104). 50,000 light-years across, the galaxy is located 28 million light-years from Earth at the southern edge of the rich Virgo cluster of galaxies. Equivalent to 800 billion suns, Sombrero is one of the most massive objects in that group. The hallmark of Sombrero is a brilliant white, bulbous core encircled by the thick dust lanes comprising the spiral structure of the galaxy. As seen from Earth, the galaxy is tilted nearly edge-on. We view it from just six degrees north of its equatorial plane. This rich system of globular clusters is estimated to be nearly 2,000 in number which is 10 times as many as in our Milky Way galaxy. Similar to the clusters in the Milky Way, the ages range from 10-13 billion years old. Embedded in the bright core of M104 is a smaller disk, which is tilted relative to the large disk. The HST paired with the Spitzer infrared telescope, offers this striking composite capturing the magnificence of the Sombrero galaxy. In the Hubble view, the galaxy resembles a broad-rimmed Mexican hat, whereas in the Spitzer striking infrared view, the galaxy looks more like a bulls eye. The full view provided by Spitzer shows the disk is warped, which is often the result of a gravitational encounter with another galaxy, and clumpy areas spotted in the far edges of the ring indicate young star forming regions. Spitzer detected infrared emission not only from the ring, but from the center of the galaxy as well, where there is a huge black hole believed to be a billion times more massive than our Sun. The Marshall Space Flight Center (MSFC) had responsibility for design, development, and construction of the HST.

  2. [Identification of pearl powder using microscopic infrared reflectance spectroscopy].

    PubMed

    Zhang, Xuan; Hu, Chao; Yan, Yan; Yang, Hai-Feng; Li, Jun-Fang; Bai, Hua; Xi, Guang-Cheng; Liao, Jie

    2014-09-01

    Pearl is a precious ornament and traditional Chinese medicine, which application history in China is more than 2000 years. It is well known that the chemical ingredients of shell and pearl are very similar, which all of them including calcium carbonate and various amino acids. Generally, shell powders also can be used as medicine; however, its medicinal value is much lower than that of pearl powders. Due to the feature similarity between pearl powders and shell powders, the distinguishment of them by detecting chemical composition and morphology is very difficult. It should be noted that shell powders have been often posing as pearl powders in markets, which seriously infringes the interests of consumers. Identification of pearl powder was investigated by microscopic infrared reflectance spectroscopy, and pearl powder as well as shell powder was calcined at different temperatures for different time before infrared reflectance spectroscopy analysis. The experimental results indicated that when calcined at 400 °C for 30 minutes under atmospheric pressure, aragonite in pearl powder partly transformed into calcite, while aragonite in shell powder completely transformed into calcite. At the same time, the difference in phase transition between the pearl powders 'and shell powders can be easily detected by using the microscopic infrared reflectance spectroscopy. Therefore, based on the difference in their phase transition process, infrared reflectance spectroscopy can be used to identify phase transformation differences between pearl powder and shell powder. It's more meaningfully that the proposed infrared reflectance spec- troscopy method was also investigated for the applicability to other common counterfeits, such as oyster shell powders and abalone shell powders, and the results show that the method can be a simple, efficiently and accurately method for identification of pearl powder. PMID:25532338

  3. Catheter based mid-infrared reflectance and reflectance generated absorption spectroscopy

    SciTech Connect

    Holman, Hoi-Ying N

    2013-10-29

    A method of characterizing conditions in a tissue, by (a) providing a catheter that has a light source that emits light in selected wavenumbers within the range of mid-IR spectrum; (b) directing the light from the catheter to an area of tissue at a location inside a blood vessel of a subject; (c) collecting light reflected from the location and generating a reflectance spectra; and (d) comparing the reflectance spectra to a reference spectra of normal tissue, whereby a location having an increased number of absorbance peaks at said selected wavenumbers indicates a tissue inside the blood vessel containing a physiological marker for atherosclerosis.

  4. Spectral purification and infrared light recycling in extreme ultraviolet lithography sources.

    PubMed

    Bayraktar, Muharrem; van Goor, Fred A; Boller, Klaus J; Bijkerk, Fred

    2014-04-01

    We present the design of a novel collector mirror for laser produced plasma (LPP) light sources to be used in extreme ultraviolet (EUV) lithography. The design prevents undesired infrared (IR) drive laser light, reflected from the plasma, from reaching the exit of the light source. This results in a strong purification of the EUV light, while the reflected IR light becomes refocused into the plasma for enhancing the IR-to-EUV conversion. The dual advantage of EUV purification and conversion enhancement is achieved by incorporating an IR Fresnel zone plate pattern into the EUV reflective multilayer coating of the collector mirror. Calculations using Fresnel-Kirchhoff's diffraction theory for a typical collector design show that the IR light at the EUV exit is suppressed by four orders of magnitude. Simultaneously, 37% of the reflected IR light is refocused back the plasma. PMID:24718234

  5. Spectral infrared hemispherical reflectance measurements for LDEF tray clamps

    NASA Technical Reports Server (NTRS)

    Cromwell, B. K.; Shepherd, S. D.; Pender, C. W.; Wood, B. E.

    1993-01-01

    Infrared hemispherical reflectance measurements that were made on 58 chromic acid anodized tray clamps from LDEF are described. The measurements were made using a hemiellipsoidal mirror reflectometer with interferometer for wavelengths between 2-15 microns. The tray clamps investigated were from locations about the entire spacecraft and provided the opportunity for comparing the effects of atomic oxygen at each location. Results indicate there was essentially no dependence on atomic oxygen fluence for the surfaces studied, but there did appear to be a slight dependence on solar radiation exposure. The reflectances of the front sides of the tray clamps consistently were slightly higher than for the protected rear tray clamp surfaces.

  6. Reflection of light pulses from clouds.

    PubMed

    Plass, G N; Kattawar, G W

    1971-10-01

    The reflection of light pulses from clouds is calculated by a Monte Carlo technique for all orders of multiple scattering. The photons are emitted within a narrow cone, scattered by water droplets and ice crystals in clouds as well as by Rayleigh scattering centers and aerosols, and finally detected at the source position. The returned flux is determined as a function of the photon path length for: (1) three different size distributions for the cloud particles (haze C, nimbostratus, ice crystal); (2) two different variations of the number density with height of the scattering centers within the cloud; (3) six different zenith angles of the source. The influence of detector half-width and of the atmosphere on the returned flux is studied. The returned flux as a function of the photon path length depends on both the size distribution of the particles within the cloud and on the density of scattering centers as a function of height.

  7. Characterizing Cool Giant Planets in Reflected Light

    NASA Technical Reports Server (NTRS)

    Marley, Mark

    2016-01-01

    While the James Webb Space Telescope will detect and characterize extrasolar planets by transit and direct imaging, a new generation of telescopes will be required to detect and characterize extrasolar planets by reflected light imaging. NASA's WFIRST space telescope, now in development, will image dozens of cool giant planets at optical wavelengths and will obtain spectra for several of the best and brightest targets. This mission will pave the way for the detection and characterization of terrestrial planets by the planned LUVOIR or HabEx space telescopes. In my presentation I will discuss the challenges that arise in the interpretation of direct imaging data and present the results of our group's effort to develop methods for maximizing the science yield from these planned missions.

  8. [Drug release system controlled by near infrared light].

    PubMed

    Niidome, Takuro

    2013-01-01

    Gold nanorods have absorption bands in the near-infrared region; in this spectral range, light penetrates deeply into tissues. The absorbed light energy is converted into heat by gold nanorods. This is the so-called photothermal effect. Gold nanorods are therefore expected to act not only as thermal converters for photothermal therapy, but also as controllers for drug-release systems responding to irradiation with near-infrared light. To achieve a controlled-release system that could be triggered by light irradiation, the gold nanorods were modified with double-stranded DNA (dsDNA). When the dsDNA-modified gold nanorods were irradiated with near-infrared light, single-stranded DNA (ssDNA) was released from the gold nanorods because of the photothermal effect. The release of ssDNA was also observed in tumors grown on mice after near-infrared light irradiation. We also proposed a different controlled-release system responding to near-infrared light. Gold nanorods were modified with polyethylene glycol (PEG) through Diels-Alder cycloadducts. When the gold nanorods were irradiated with near-infrared light, the PEG chains were released from the gold nanorods because of the retro Diels-Alder reaction induced by the photothermal effect. Such controlled-release systems triggered by near-infrared light irradiation will be expanded for gold nanorod drug delivery system applications.

  9. Terahertz and mid-infrared reflectance of epitaxial graphene

    PubMed Central

    Santos, Cristiane N.; Joucken, Frédéric; De Sousa Meneses, Domingos; Echegut, Patrick; Campos-Delgado, Jessica; Louette, Pierre; Raskin, Jean-Pierre; Hackens, Benoit

    2016-01-01

    Graphene has emerged as a promising material for infrared (IR) photodetectors and plasmonics. In this context, wafer scale epitaxial graphene on SiC is of great interest in a variety of applications in optics and nanoelectronics. Here we present IR reflectance spectroscopy of graphene grown epitaxially on the C-face of 6H-SiC over a broad optical range, from terahertz (THz) to mid-infrared (MIR). Contrary to the transmittance, reflectance measurements are not hampered by the transmission window of the substrate, and in particular by the SiC Reststrahlen band in the MIR. This allows us to present IR reflectance data exhibiting a continuous evolution from the regime of intraband to interband charge carrier transitions. A consistent and simultaneous analysis of the contributions from both transitions to the optical response yields precise information on the carrier dynamics and the number of layers. The properties of the graphene layers derived from IR reflection spectroscopy are corroborated by other techniques (micro-Raman and X-ray photoelectron spectroscopies, transport measurements). Moreover, we also present MIR microscopy mapping, showing that spatially-resolved information can be gathered, giving indications on the sample homogeneity. Our work paves the way for a still scarcely explored field of epitaxial graphene-based THz and MIR optical devices. PMID:27102827

  10. Terahertz and mid-infrared reflectance of epitaxial graphene

    NASA Astrophysics Data System (ADS)

    Santos, Cristiane N.; Joucken, Frédéric; de Sousa Meneses, Domingos; Echegut, Patrick; Campos-Delgado, Jessica; Louette, Pierre; Raskin, Jean-Pierre; Hackens, Benoit

    2016-04-01

    Graphene has emerged as a promising material for infrared (IR) photodetectors and plasmonics. In this context, wafer scale epitaxial graphene on SiC is of great interest in a variety of applications in optics and nanoelectronics. Here we present IR reflectance spectroscopy of graphene grown epitaxially on the C-face of 6H-SiC over a broad optical range, from terahertz (THz) to mid-infrared (MIR). Contrary to the transmittance, reflectance measurements are not hampered by the transmission window of the substrate, and in particular by the SiC Reststrahlen band in the MIR. This allows us to present IR reflectance data exhibiting a continuous evolution from the regime of intraband to interband charge carrier transitions. A consistent and simultaneous analysis of the contributions from both transitions to the optical response yields precise information on the carrier dynamics and the number of layers. The properties of the graphene layers derived from IR reflection spectroscopy are corroborated by other techniques (micro-Raman and X-ray photoelectron spectroscopies, transport measurements). Moreover, we also present MIR microscopy mapping, showing that spatially-resolved information can be gathered, giving indications on the sample homogeneity. Our work paves the way for a still scarcely explored field of epitaxial graphene-based THz and MIR optical devices.

  11. Visible and near infrared reflectances measured from laboratory ice clouds.

    PubMed

    Barkey, Brian; Liou, K N

    2008-05-01

    We present laboratory results of the 0.68 microm visible (VIS) and 1.617 microm near infrared (NIR) reflectances typically used for inferring optical depth and ice crystal size from satellite radiometers, from ice clouds generated in a temperature controlled column cloud chamber. Two types of ice crystals were produced in this experiment: small columns and dendrites with mean maximum dimensions of about 17 and 35 microm. Within experimental uncertainty, the measured reflectances from ice clouds at both wavelengths agree reasonably well with the theoretical results computed from the plane-parallel adding-doubling method for radiative transfer using the measured ice particle morphology. We demonstrate that laboratory scattering and reflectance data for thin ice clouds with optical depths less than 0.4 can be used for validation of the thin cirrus optical depth and ice crystal size that have been routinely retrieved from the satellite VIS-NIR two channel pair.

  12. Visible and near infrared reflectances measured from laboratory ice clouds.

    PubMed

    Barkey, Brian; Liou, K N

    2008-05-01

    We present laboratory results of the 0.68 microm visible (VIS) and 1.617 microm near infrared (NIR) reflectances typically used for inferring optical depth and ice crystal size from satellite radiometers, from ice clouds generated in a temperature controlled column cloud chamber. Two types of ice crystals were produced in this experiment: small columns and dendrites with mean maximum dimensions of about 17 and 35 microm. Within experimental uncertainty, the measured reflectances from ice clouds at both wavelengths agree reasonably well with the theoretical results computed from the plane-parallel adding-doubling method for radiative transfer using the measured ice particle morphology. We demonstrate that laboratory scattering and reflectance data for thin ice clouds with optical depths less than 0.4 can be used for validation of the thin cirrus optical depth and ice crystal size that have been routinely retrieved from the satellite VIS-NIR two channel pair. PMID:18449323

  13. Reflected infrared spectrum of a massive protostar in Orion.

    PubMed

    Morino, J I; Yamashita, T; Hasegawa, T; Nakano, T

    1998-05-28

    The infrared source IRc2 in the star-forming region Orion-KL is generally believed to contain a massive and very young star. Its nature and evolutionary status, however, are difficult to determine because it is hidden from direct view by a dense disklike envelope of gas and dust. Here we report observations of infrared radiation (at a wavelength of about 2 microm) that has escaped the surrounding dust in the polar direction, perpendicular to the plane of the disk, and then been reflected towards us by dust farther away from the star. The reflected spectrum contains absorption lines of neutral metallic atoms and carbon monoxide, which we interpret as indicating a source temperature of about 4,500 K. But, given the luminosity of the source, its radius must be at least 300 solar radii-too large to be attained with the modest gas-accretion rates in existing theories of massive-star formation. Whether the infrared radiation is coming from the protostar itself or the self-luminous accretion disk around it, the accretion rate must be around (5-15) x 10(-3) solar masses per year, at least two orders of magnitude greater than is commonly assumed in models of star formation.

  14. Diffuse Reflection of Laser Light From Clouds

    NASA Technical Reports Server (NTRS)

    Cahalan, R. F.; Davis, A.; McGill, M.

    1999-01-01

    Laser light reflected from an aqueous suspension of particles or "cloud" with known thickness and particle size distribution defines the "cloud radiative Green's function", G. G is sensitive to cloud thickness, allowing retrieval of that important quantity. We describe a laboratory simulation of G, useful in design of an offbeam Lidar instrument for remote sensing of cloud thickness. Clouds of polystyrene microspheres suspended in water are analogous to real clouds of water droplets suspended in air. The size distribution extends from 0.5 microns to 25 microns, roughly lognormal, similar to real clouds. Density of suspended spheres is adjusted so photon mean-free-path is about 10 cm, 1000 times smaller than in real clouds. The light source is a Nd:YAG laser at 530 nm. Detectors are flux and photon-counting PMTs, with a glass probe for precise positioning. A Labview 5 VI controls position and data acquisition, via an NI Motion Control board connected to a stepper motor driving an Edmund linear slider,and a 16-channel 16-bit NI-DAQ board. The stepper motor is accurate to 10 microns. Step size is selectable. Far from the beam, the rate of exponential increase in the beam direction scales as expected from diffusion theory, linearly with cloud thickness, and inversely as the square root of the reduced optical thickness, independent of particle size. Nearer the beam the signal increases faster than exponential and depends on particle size. Results verify 3D Monte Carlo simulations that demonstrate detectability of remotely sensed offbeam returns, without filters at night, with narrow bandpass filter in day.

  15. Study of laser reflection of infrared cameras with germanium optics

    NASA Astrophysics Data System (ADS)

    Chiu, Patrio; Shih, Ishiang; Shi, S.; Laou, Philips

    2003-09-01

    Infrared cameras are widely used in today's battlefield for surveillance purpose. Because of retroreflection, an incident laser beam entering the camera optics results in a beam reflecting back to the direction of the laser source. An IR detector positioned close to the laser source can then detect the reflected beam. This effect can reveal the location of the cameras and thus increases the risk of covert operations. In the present work, the characteristics of the retroreflection is studied. It is found that the reflection intensity is high when the incident beam enters through the middle part of the lenses while it is low and the beam is diverged when entering through the outer part of the lenses. The reflection is symmetric when the incident beam is normal to the lenses while asymmetric when it is incident with an angle to the lenses. In order to study the potential effects on retroreflection of modified camera optics, IR low index slides (ZnSe and KCl with refractive indices of 2.49 and 1.54, respectively) with different thicknesses (2mm, 4mm and 6mm) are placed in the optical system. The result shows that the focal point of the lenses is changed by the addition of the slide but the optical paths of the reflection remain unchanged. The relationship between the different slides and beam intensity is also studied.

  16. Surface roughness and gloss study of prints: application of specular reflection at near infrared

    NASA Astrophysics Data System (ADS)

    Silfsten, P.; Dutta, R.; Pääkkönen, P.; Tåg, C.-M.; Gane, P. A. C.; Peiponen, K.-E.

    2012-12-01

    Absolute reflectance data were measured with a spectrophotometer in the visible and near infrared (NIR) spectral range. The specular reflectance data in the NIR were used for the assessment of the surface roughness of magenta, yellow, cyan and black prints on paper. In addition, surface roughness data obtained from the prints with a mechanical diamond stylus, an optical profiling system and the spectrophotometer are compared with each other. The surface roughness obtained with the aid of the spectrophotometer data suggests a smoother surface than when measured with the diamond stylus and the optical profiling system. The gloss of the prints can be obtained from the absolute specular reflectance spectra in the spectral region of visible light. It is shown that specular reflection data at a fixed wavelength in the NIR are useful also in the interpretation of gloss in the visible spectral range, but using an unconventional grazing angle of incidence.

  17. Photo-induced reflectivity in the mid and far infrared

    SciTech Connect

    Haar, P.; Harrington, K.J.; Schwettman, H.A.

    1995-12-31

    Interest in switching FEL beams has motivated studies of photo-induced reflectivity in the mid and far infrared. We are particularly interested in Ge{sup 4}, GaAs, and Si{sup 5}, materials that can be pumped with a visible or near-IR conventional laser and which together cover the wavelengths from 3-100{mu}m. We have made quantitative measurements to determine the induced reflectivity, carrier lifetime, and transient absorption of these materials at several wavelengths across this range using a variety of pump laser wavelengths and pulse lengths. These measurements allow us to determine the feasibility of single pulse selection and cavity dumping with our FELs at high repetition rates.

  18. Far-infrared emissivity measurements of reflective surfaces

    NASA Technical Reports Server (NTRS)

    Xu, J.; Lange, A. E.; Bock, J. J.

    1996-01-01

    An instrument developed to measure the emissivity of reflective surfaces by comparing the thermal emission of a test sample to that of a reference surface is reported. The instrument can accurately measure the emissivity of mirrors made from lightweight thermally insulating materials such as glass and metallized carbon fiber reinforced plastics. Far infrared measurements at a wavelength of 165 micrometers are reported. The instrument has an absolute accuracy of Delta epsilon = 9 x 10(exp -4) and can reproducibly measure an emissivity of as small as 2 x 10(exp -4) between flat reflective surfaces. The instrument was used to measure mirror samples for balloon-borne and spaceborne experiments. An emissivity of (6.05 +/- 1.24) x 10(exp -3) was measured for gold evaporated on glass, and (6.75 +/- 1.17) x 10(exp -3) for aluminum evaporated on glass.

  19. Apparatus for and method of correcting for astigmatism in a light beam reflected off of a light reflecting surface

    DOEpatents

    Sawicki, R.H.; Sweatt, W.

    1985-11-21

    A technique for adjustably correcting for astigmatism in a light beam is disclosed herein. This technique defines a flat, rectangular light reflecting surface having opposite reinforced side edges and which is resiliently bendable, to a limited extent, into different concave and/or convex cylindrical curvatures about a particular axis and provides for adjustably bending the light reflecting surface into one of different curvatures depending upon the astigmatism to be corrected and for fixedly maintaining the curvature selected. In the embodiment disclosed, the light reflecting surface is adjustably bendable into the selected cylindrical curvature by application of a particular bending moment to the reinforced side edges of the light reflecting surface.

  20. Gate-controlled mid-infrared light bending with aperiodic graphene nanoribbons array

    NASA Astrophysics Data System (ADS)

    Carrasco, Eduardo; Tamagnone, Michele; Mosig, Juan R.; Low, Tony; Perruisseau-Carrier, Julien

    2015-03-01

    Graphene plasmonic nanostructures enable subwavelength confinement of electromagnetic energy from the mid-infrared down to the terahertz frequencies. By exploiting the spectrally varying light scattering phase at the vicinity of the resonant frequency of the plasmonic nanostructure, it is possible to control the angle of reflection of an incoming light beam. We demonstrate, through full-wave electromagnetic simulations based on Maxwell equations, the electrical control of the angle of reflection of a mid-infrared light beam by using an aperiodic array of graphene nanoribbons, whose widths are engineered to produce a spatially varying reflection phase profile that allows for the construction of a far-field collimated beam towards a predefined direction.

  1. Combined use of visible, reflected infrared, and thermal infrared images for mapping Hawaiian lava flows

    NASA Technical Reports Server (NTRS)

    Abrams, Michael; Abbott, Elsa; Kahle, Anne

    1991-01-01

    The weathering of Hawaiian basalts is accompanied by chemical and physical changes of the surfaces. These changes have been mapped using remote sensing data from the visible and reflected infrared and thermal infrared wavelength regions. They are related to the physical breakdown of surface chill coats, the development and erosion of silica coatings, the oxidation of mafic minerals, and the development of vegetation cover. These effects show systematic behavior with age and can be mapped using the image data and related to relative ages of pahoehoe and aa flows. The thermal data are sensitive to silica rind development and fine structure of the scene; the reflectance data show the degree of oxidation and differentiate vegetation from aa and cinders. Together, data from the two wavelength regions show more than either separately. The combined data potentially provide a powerful tool for mapping basalt flows in arid to semiarid volcanic environments.

  2. Narrowband Mid-infrared reflectance filters using guided mode resonance

    PubMed Central

    Kodali, Anil K.; Schulmerich, Matthew; Ip, Jason; Yen, Gary; Cunningham, Brian T.; Bhargava, Rohit

    2010-01-01

    There is a need to develop mid-infrared (IR) spectrometers for applications in which the absorbance of only a few vibrational mode (optical) frequencies needs to be recorded; unfortunately, there are limited alternatives for the same. The key requirement is the development of a means to access discretely a small set of spectral positions from the wideband thermal sources commonly used for spectroscopy. We present here the theory, design and practical realization of a new class of filters in the mid-infrared (IR) spectral regions based on using guided mode resonances (GMR) for narrowband optical reflection. A simple, periodic surface-relief configuration is chosen to enable both a spectral response and facile fabrication. A theoretical model based on rigorous coupled wave analysis is developed, incorporating anomalous dispersion of filter materials in the mid-IR spectral region. As a proof-of-principle demonstration, a set of four filters for a spectral region around the C-H stretching mode (2600–3000 cm−1) are fabricated and responses compared to theory. The reflectance spectra were well-predicted by the developed theory and results were found to be sensitive to the angle of incidence and dispersion characteristics of the material. In summary, the work reported here forms the basis for a rational design of filters that can prove useful for IR absorption spectroscopy. PMID:20527738

  3. Spectral infrared hemispherical reflectance measurements for LDEF tray clamps

    NASA Technical Reports Server (NTRS)

    Wood, Bobby E.; Cromwell, Brian K.; Pender, Charles W.; Shepherd, Seth D.

    1992-01-01

    This paper describes infrared hemispherical reflectance measurements (2-15 microns) that were made on 58 chromic acid anodized tray clamps retrieved from the LDEF spacecraft. These clamps were used for maintaining the experiments in place and were located at various locations about the spacecraft. Changes in reflectance of the tray clamps at these locations were compared with atomic oxygen fluxes at the same locations. A decrease in absorption band depth was seen for the surfaces exposed to space indicating that there was some surface layer erosion. In all of the surfaces measured, little evidence of contamination was observed and none of the samples showed evidence of the brown nicotine stain that was so prominent in other experiments. Total emissivity values were calculated for both exposed and unexposed tray clamp surfaces. Only small differences, usually less than 1 percent, were observed. The spectral reflectances were measured using a hemi-ellipsoidal mirror reflectometer matched with an interferometer spectrometer. The rapid scanning capability of the interferometer allowed the reflectance measurements to be made in a timely fashion. The ellipsoidal mirror has its two foci separated by 2 inches and located on the major axis. A blackbody source was located at one focus while the tray clamp samples were located at the conjugate focus. The blackbody radiation was modulated and then focused by the ellipsoid onto the tray clamps. Radiation reflected from the tray clamp was sampled by the interferometer by viewing through a hole in the ellipsoid. A gold mirror (reflectance approximately 98 percent) was used as the reference surface.

  4. Long distance active hyperspectral sensing using high-power near-infrared supercontinuum light source.

    PubMed

    Manninen, Albert; Kääriäinen, Teemu; Parviainen, Tomi; Buchter, Scott; Heiliö, Miika; Laurila, Toni

    2014-03-24

    A hyperspectral remote sensing instrument employing a novel near-infrared supercontinuum light source has been developed for active illumination and identification of targets. The supercontinuum is generated in a standard normal dispersion multi-mode fiber and has 16 W total optical output power covering 1000 nm to 2300 nm spectral range. A commercial 256-channel infrared spectrometer was used for broadband infrared detection. The feasibility of the presented hyperspectral measurement approach was investigated both indoors and in the field. Reflection spectra from several diffusive targets were successfully measured and a measurement range of 1.5 km was demonstrated.

  5. NASA SOFIA International Year of Light (IYL) Event: Infrared Light: Hanging out in the Stratosphere

    NASA Astrophysics Data System (ADS)

    Clark, Coral; Backman, Dana E.; Harman, Pamela; Veronico, Nicholas

    2015-01-01

    As an International Year of Light committee endorsed event, Infrared Light: Hanging out in the Stratosphere will engage learners around the world, linking participants with scientists at work on board NASA SOFIA, the world's largest flying observatory. This major event will showcase science-in-action, interviews, live data, and observations performed both aboard the aircraft and at partner centers on land.SOFIA (Stratospheric Observatory For Infrared Astronomy) is an 80% - 20% partnership of NASA and the German Aerospace Center (DLR) consisting of an extensively modified Boeing 747SP aircraft carrying a reflecting telescope with an effective diameter of 2.5 meters. SOFIA is a program in NASA's Science Mission Directorate, Astrophysics Division. Science investigators leverage SOFIA's unique capabilities to study the universe at infrared wavelengths by making observations that are impossible for even the largest and highest ground-based telescopes. SOFIA received Full Operating Capacity status in May, 2014, and astrophysicists will continue to utilize the observatory and upgraded instruments to study astronomical objects and phenomena, including star birth and death; planetary system formation; identification of complex molecules in space; planets, comets, and asteroids in our solar system; and nebulae and dust in galaxies.This landmark event will reflect and build on the ProjectLink. In October 1995, SOFIA's predecessor, the Kuiper Airborne Observatory (KAO), performed the first satellite links from an airplane to the ground. The KAO downlinked to the Exploratorium museum (SF, CA), where over 200 students watched the webcast, conversed, and participated in simultaneous observations at the world-renowned science museum. SOFIA will now take this concept into the 21st century, utilizing internet technologies to engage and inspire 100,000+ learners of all ages through simultaneous presentations and appearances by over 70 SOFIA Educators at schools and informal learning

  6. Testing the spectrum of infrared emission reflected by several surfaces with a FTIR

    NASA Astrophysics Data System (ADS)

    Wang, Xuanyu; Hu, Rui; Pang, Minhui; Bai, Haitao; Dong, Wenjie

    2014-09-01

    A set of sectional FTIR is applied to study the reflecting characteristics of several surfaces to infrared emission. The standard infrared source is separated from the host of the FTIR and set in a right-angled triangle with the reflecting plate and the entrance to make the reflecting infrared emission can easily pass into the detector through the route. The reflecting infrared emission from the FTIR source is measured by the FTIR detector. The reflecting plate includes metal plate, mirror, wood block and so on. A high intensity standard infrared source cooled by air is accepted and the testing background is atmosphere. The infrared emission reflected by the plate from the standard source is tested one by one. By the experiment, mirror has a good performance to reflect infrared emission, which is much better than unpainted iron plate or painted wood block. Certainly, unpainted iron plate has stronger capacity to reflect infrared emission than painted wood block, etc. As a result, the smoother the surface is, the stronger the reflecting performance is. The reflecting performance of painted surface to infrared emission is poorer than unpainted one. The various painted surfaces have not a visible difference upon their reflecting performance to infrared emission although they are made from different materials.

  7. Analysis of silage composition by near-infrared reflectance spectroscopy

    NASA Astrophysics Data System (ADS)

    Reeves, James B., III; Blosser, Timothy H.; Colenbrander, V. F.

    1991-02-01

    Two studies were performed to investigate the feasibility of using near infrared reflectance spectroscopy (NIRS) with undried silages. In the first study silages were analyzed for major components (e. g. dry matter crude protein and other forms of nitrogen fiber and in vitro digestible dry matter) and short chain fatty acids (SCFA). NIRS was found to operate satisfactorily except for some forms of nitrogen and SCFA. In study two various methods of grinding spectral regions and sample presentation were examined. Undried Wiley ground samples in a rectangular cell gave the best overall results for non-dry ice undried grinds with wavelengths between 1100 and 2498 nm. Silages scanned after drying however produced the best results. Intact samples did not perform as well as ground samples and wavelengths below 1100 nm were of little use. 2 .

  8. Thermal infrared reflectance and emission spectroscopy of quartzofeldspathic glasses

    USGS Publications Warehouse

    Byrnes, J.M.; Ramsey, M.S.; King, P.L.; Lee, R.J.

    2007-01-01

    This investigation seeks to better understand the thermal infrared (TIR) spectral characteristics of naturally-occurring amorphous materials through laboratory synthesis and analysis of glasses. Because spectra of glass phases differ markedly from their mineral counterparts, examination of glasses is important to accurately determine the composition of amorphous surface materials using remote sensing datasets. Quantitatively characterizing TIR (5-25 ??m) spectral changes that accompany structural changes between glasses and mineral crystals provides the means to understand natural glasses on Earth and Mars. A suite of glasses with compositions analogous to common terrestrial volcanic glasses was created and analyzed using TIR reflectance and emission techniques. Documented spectral characteristics provide a basis for comparison with TIR spectra of other amorphous materials (glasses, clays, etc.). Our results provide the means to better detect and characterize glasses associated with terrestrial volcanoes, as well as contribute toward understanding the nature of amorphous silicates detected on Mars. Copyright 2007 by the American Geophysical Union.

  9. Aerosol collection and analysis using diffuse reflectance infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Samuels, Alan C.; Wong, Diane M.; Meyer, Gerald J.; Roelant, Geoffrey J.; Williams, Barry R.; Miles, Ronald W., Jr.; Manning, Christopher J.

    2004-08-01

    Infrared spectroscopy is routinely employed for the identification of organic molecules and, more recently, for the classification of biological materials. We have developed a sample collection method that facilitates infrared analysis of airborne particulates using a diffuse reflectance (DR) technique. Efforts are underway to extend the method to include simultaneous analysis of vapor phase organics by using adsorbent substrates compatible with the DR technique. This series of laboratory results provides proof-of-principle for both the sample collection and data collection processes. Signal processing of the DR spectra is shown to provide rapid qualitative identification of representative aerosol materials, including particulate matter commonly found in the environment. We compare the results for such materials as bacterial spores, pollens and molds, clays and dusts, smoke and soot. Background correction analysis is shown to be useful for differentiation and identification of these constituents. Issues relating to complex mixtures of environmental samples under highly variable conditions are considered. Instrumentation development and materials research are now underway with the aim of constructing a compact sampling system for near real-time monitoring of aerosol and organic pollutants. A miniature, tilt-compensated Fourier transform spectrometer will provide spectroscopic interrogation. A series of advanced digital signal processing methods are also under development to enhance the sensor package. The approach will be useful for industrial applications, chemical and biological agent detection, and environmental monitoring for chemical vapors, hazardous air pollutants, and allergens.

  10. Studies of dust grain properties in infrared reflection nebulae

    NASA Technical Reports Server (NTRS)

    Pendleton, Y. J.; Tielens, A. G. G. M.; Werner, M. W.

    1990-01-01

    A model has been developed for reflection nebulae around luminous IR sources embedded in dense dust clouds. The shape of the IR spectrum is shown to be the result of a combination of the scattering properties of the dust, the spectrum of the illuminating source, and foreground extinction, while geometry plays a minor role. Comparison of the model results with IR observations of the reflection nebula surrounding OMC-2/IRS 1 shows that either a grain size distribution like that found in the diffuse ISM, or consisting of larger grains, can explain the observed shape of the spectrum. However, the absolute intensity level of the scattered light, as well as the observed polarization, requires large grains. By adding water-ice mantles to the silicate and graphite cores, the 3.08 micron ice-band feature observed in the spectra of several IR reflection nebulae has been modeled. It is shown that this ice band arises naturally in optically thick reflection nebulae containing ice-coated grains.

  11. Infrared light emission from semiconductor devices

    SciTech Connect

    Barton, D.L.; Tangyunyong, P.; Soden, J.M.; Liang, A.Y.; Low, F.J.; Zaplatin, A.N.; Shivanandan, K.; Donohoe, G.

    1996-10-01

    We present results using near-infrared (NIR) cameras to study emission of common defect classes for integrated circuits. The cameras are based on a liquid nitrogen cooled HgCdTe imaging array with high quantum efficiency and very low read noise. The array was developed for infrared astronomy and has high quantum efficiency in the wavelength range from 0.8 to 2.5 {mu}m. For comparison, the same set of samples used to characterize the performance of the NIR camera were studied using a non-intensified, liquid-nitrogen-cooled, slow scan CCD camera (with a spectral range 400-1100 nm). Results show that the NIR camera images all of the defect classes studied here with much shorter integration times than the cooled CCD, suggesting that photon emission beyond 1 {mu}m is significantly stronger than at shorter wavelengths.

  12. Determination of in vivo skin moisture level by near-infrared reflectance spectroscopy

    NASA Astrophysics Data System (ADS)

    Saknite, Inga; Spigulis, Janis

    2015-03-01

    Near-infrared spectroscopy has a potential for noninvasive determination of skin moisture level due to high water absorption. In this study, diffuse reflectance spectra of in vivo skin were acquired in the spectral range of 900 nm to 1700 nm by using near-infrared spectrometer, optical fiber and halogen bulb light source. Absorption changes after applying skin moisturizers were analyzed over time at different body sites. Results show difference in absorption when comparing dry and normal skin. Comparison of absorption changes over time after applying moisturizer at different body sites is analyzed and discussed. Some patterns of how skin reacts to different skin moisturizers are shown, although no clear pattern can be seen due to signal noise.

  13. Untwisting the polarization properties of light reflected by scarab beetles

    NASA Astrophysics Data System (ADS)

    McDonald, Luke T.; Finlayson, Ewan D.; Vukusic, Peter

    2015-03-01

    The spectral and angle-dependent optical properties of two scarab beetle species belonging to the genus Chrysina are presented. The species display broadband reflectivity and selectively reflect left-circularly polarized light. We use electron microscopy to detail the left-handed, twisted lamellar structure present in these biological systems and imaging scatterometry to characterize their bidirectional reflectance distribution function. We show that the broadband nature of the beetles' reflectance originates due to the range of pitch dimensions found in the structure.

  14. Investigation of Latent Traces Using Infrared Reflectance Hyperspectral Imaging

    NASA Astrophysics Data System (ADS)

    Schubert, Till; Wenzel, Susanne; Roscher, Ribana; Stachniss, Cyrill

    2016-06-01

    The detection of traces is a main task of forensics. Hyperspectral imaging is a potential method from which we expect to capture more fluorescence effects than with common forensic light sources. This paper shows that the use of hyperspectral imaging is suited for the analysis of latent traces and extends the classical concept to the conservation of the crime scene for retrospective laboratory analysis. We examine specimen of blood, semen and saliva traces in several dilution steps, prepared on cardboard substrate. As our key result we successfully make latent traces visible up to dilution factor of 1:8000. We can attribute most of the detectability to interference of electromagnetic light with the water content of the traces in the shortwave infrared region of the spectrum. In a classification task we use several dimensionality reduction methods (PCA and LDA) in combination with a Maximum Likelihood classifier, assuming normally distributed data. Further, we use Random Forest as a competitive approach. The classifiers retrieve the exact positions of labelled trace preparation up to highest dilution and determine posterior probabilities. By modelling the classification task with a Markov Random Field we are able to integrate prior information about the spatial relation of neighboured pixel labels.

  15. Near-infrared branding efficiently correlates light and electron microscopy.

    PubMed

    Bishop, Derron; Nikić, Ivana; Brinkoetter, Mary; Knecht, Sharmon; Potz, Stephanie; Kerschensteiner, Martin; Misgeld, Thomas

    2011-06-05

    The correlation of light and electron microscopy of complex tissues remains a major challenge. Here we report near-infrared branding (NIRB), which facilitates such correlation by using a pulsed, near-infrared laser to create defined fiducial marks in three dimensions in fixed tissue. As these marks are fluorescent and can be photo-oxidized to generate electron contrast, they can guide re-identification of previously imaged structures as small as dendritic spines by electron microscopy.

  16. Red and infrared light distribution in blood

    NASA Astrophysics Data System (ADS)

    de Magalhães, Ana Carolina; Yoshimura, Elisabeth M.

    2013-02-01

    Low level laser therapy (LLLT) is used in several applications, including the reduction of inflammatory processes. It might be used to prevent the systemic inflammatory response syndrome (SIRS), which some patients develop after cardiopulmonary bypass (CPB) surgery. The objectives of this study were to investigate light distribution inside blood, in order to implement the LLLT during CPB, and, through this study, to determine the best wavelength and the best way to perform the treatment. The blood, diluted to the same conditions of CPB procedure was contained inside a cuvette and an optical fiber was used to collect the scattered light. Two wavelengths were used: 632.8 nm and 820 nm. Light distribution in blood inside CPB tubes was also evaluated. Compared to the 820 nm light, the 632.8 nm light is scattered further away from the laser beam, turning it possible that a bigger volume of blood be treated. The blood should be illuminated through the smallest diameter CPB tube, using at least four distinct points around it, in only one cross section, because the blood is kept passing through the tube all the time and the whole volume will be illuminated.

  17. Optical motion detector detecting visible and near infrared light

    NASA Astrophysics Data System (ADS)

    Everett, Hobart R., Jr.

    1990-02-01

    An optical motion detector detects changes in scene lighting indicative of motion and is also capable of detecting surveillance by active night vision devices using near-infrared light. The detector includes two photodetectors which each provide data to a signal processing network. One photodetector is sensitive to visible light; the other to near-infrared light. Both signal processing networks are identical and include a sample-and-hold, a comparator network, and a pulse stretcher. The output of a photodetector is provided to the sample-and-hold and comparator network. The comparator network compares a voltage corresponding to the instantaneously detected ambient lighting scene with a voltage corresponding to a reference lighting scene. The pulse stretcher receives the output of the comparator network and in turn provides an output to a logical processor. The logical processor compares the outputs of both signal processing networks and provides an output indicating surveillance with near-infrared light. The logical processor also indicates any perturbations in intensities of incandescent and fluorescent light.

  18. The infrared imaging spectrograph (IRIS) for TMT: reflective ruled diffraction grating performance testing and discussion

    NASA Astrophysics Data System (ADS)

    Meyer, Elliot; Chen, Shaojie; Wright, Shelley A.; Moore, Anna M.; Larkin, James E.; Simard, Luc; Marie, Jerome; Mieda, Etsuko; Gordon, Jacob

    2014-07-01

    We present the efficiency of near-infrared reflective ruled diffraction gratings designed for the InfraRed Imaging Spectrograph (IRIS). IRIS is a first light, integral field spectrograph and imager for the Thirty Meter Telescope (TMT) and narrow field infrared adaptive optics system (NFIRAOS). IRIS will operate across the near-infrared encompassing the ZYJHK bands (~0.84 - 2.4μm) with multiple spectral resolutions. We present our experimental setup and analysis of the efficiency of selected reflective diffraction gratings. These measurements are used as a comparison sample against selected candidate Volume Phase Holographic (VPH) gratings (see Chen et al., this conference). We investigate the efficiencies of five ruled gratings designed for IRIS from two separate vendors. Three of the gratings accept a bandpass of 1.19-1.37μm (J band) with ideal spectral resolutions of R=4000 and R=8000, groove densities of 249 and 516 lines/mm, and blaze angles of 9.86° and 20.54° respectively. The other two gratings accept a bandpass of 1.51-1.82μm (H Band) with an ideal spectral resolution of R=4000, groove density of 141 lines/mm, and blaze angle of 9.86°. The fraction of flux in each diffraction mode was compared to both a pure reflection mirror as well as the sum of the flux measured in all observable modes. We measure the efficiencies off blaze angle for all gratings and the efficiencies between the polarization transverse magnetic (TM) and transverse electric (TE) states. The peak reflective efficiencies are 98.90 +/- 3.36% (TM) and 84.99 +/- 2.74% (TM) for the H-band R=4000 and J-band R=4000 respectively. The peak reflective efficiency for the J-band R=8000 grating is 78.78 +/- 2.54% (TE). We find that these ruled gratings do not exhibit a wide dependency on incident angle within +/-3°. Our best-manufactured gratings were found to exhibit a dependency on the polarization state of the incident beam with a ~10-20% deviation, consistent with the theoretical efficiency

  19. Studying infrared light therapy for treating Alzheimer's disease

    NASA Astrophysics Data System (ADS)

    Han, Mengmeng; Wang, Qiyan; Zeng, Yuhui; Meng, Qingqiang; Zhang, Jun; Wei, Xunbin

    2016-03-01

    Alzheimer's disease (AD) is an extensive neurodegenerative disease. It is generally believed that there are some connections between AD and amyloid protein plaques in the brain. AD is a chronic disease that usually starts slowly and gets worse over time. The typical symptoms are memory loss, language disorders, mood swings and behavioral issues. Gradual losses of somatic functions eventually lead patients to death. Currently, the main therapeutic method is pharmacotherapy, which may temporarily reduce symptoms, but has many side effects. No current treatment can reverse AD's deterioration. Infrared (IR) light therapy has been studied in a range of single and multiple irradiation protocols in previous studies and was found beneficial for neuropathology. In our research, we have verified the effect of infrared light on AD through Alzheimer's disease mouse model. This transgenic mouse model is made by co-injecting two vectors encoding mutant amyloid precursor protein (APP) and mutant presenilin-1 (PSEN1). We designed an experimental apparatus for treating mice, which primarily includes a therapeutic box and a LED array, which emits infrared light. After the treatment, we assessed the effects of infrared light by testing cognitive performance of the mice in Morris water maze. Our results show that infra-red therapy is able to improve cognitive performance in the mouse model. It might provide a novel and safe way to treat Alzheimer's disease.

  20. Hemispherical reflectance and emittance properties of carbon nanotubes coatings at infrared wavelengths

    NASA Astrophysics Data System (ADS)

    Quijada, Manuel A.; Hagopian, John G.; Getty, Stephanie; Kinzer, Raymond E., Jr.; Wollack, Edward J.

    2011-10-01

    Recent visible wavelength observations of Multiwalled Carbon Nanotubes (MWCNT) coatings have revealed that they represent the blackest materials known in nature with a Total Hemispherical Reflectance (THR) of less than 0.25%. This makes them exceptionally good as absorbers, with the potential to provide order-ofmagnitude improvement in stray-light suppression over current black surface treatments when used in an optical system. Here we extend the characterization of this class of materials into the infrared spectral region to further evaluate their potential for use on instrument baffles for stray-light suppression and to manage spacecraft thermal properties through radiant heat transfer process. These characterizations will include the wavelength-dependent Total Hemispherical Reflectance (THR) properties in the mid- and far-infrared spectral regions (2-110 μm). Determination of the temperature-dependent emittance will be investigated in the temperature range of 40 to 300 K. These results will be compared with other more conventional black coatings such as Acktar Fractal Black or Z306 coatings among others.

  1. Apparatus for and method of correcting for astigmatism in a light beam reflected off of a light reflecting surface

    DOEpatents

    Sawicki, Richard H.; Sweatt, William

    1987-01-01

    A technique for adjustably correcting for astigmatism in a light beam is disclosed herein. This technique utilizes first means which defines a flat, rectangular light reflecting surface having opposite reinforced side edges and which is resiliently bendable, to a limited extent, into different concave and/or convex cylindrical curvatures about a particular axis and second means acting on the first means for adjustably bending the light reflecting surface into a particular selected one of the different curvatures depending upon the astigmatism to be corrected for and for fixedly maintaining the curvature selected. In the embodiment disclosed, the light reflecting surface is adjustably bendable into the selected cylindrical curvature by application of a particular bending moment to the reinforced side edges of the light reflecting surface.

  2. Fully reflective deep ultraviolet to near infrared spectrometer and entrance optics for resonance Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Schulz, B.; Bäckström, J.; Budelmann, D.; Maeser, R.; Rübhausen, M.; Klein, M. V.; Schoeffel, E.; Mihill, A.; Yoon, S.

    2005-07-01

    We present the design and performance of a new triple-grating deep ultraviolet to near-infrared spectrometer. The system is fully achromatic due to the use of reflective optics. The minimization of image aberrations by using on- and off- axis parabolic mirrors as well as elliptical mirrors yields a strong stray light rejection with high resolution over a wavelength range between 165 and 1000nm. The Raman signal is collected with a reflective entrance objective with a numerical aperture of 0.5, featuring a Cassegrain-type design. Resonance Raman studies on semiconductors and on correlated compounds, such as LaMnO3, highlight the performance of this instrument, and show diverse resonance effects between 1.96 and 5.4eV.

  3. Pluto-Charon: Infrared Reflectance from 3.6 to 8.0 Micrometers

    NASA Technical Reports Server (NTRS)

    Cruikshank, Dale P.; Emery, Joshua P.; Stansberry, John A.; VanCleve, Jeffrey E.

    2004-01-01

    We have measured the spectral reflectance of the Pluto-Charon pair at 3.6, 4.5, 5.8, and 8.0 micrometers with the Infrared Array Camera (IRAC) (G. G. Fazzio et al. Ap.J.Supp. 154, 10-17, 2004) on the Spitzer Space Telescope (STS), at eight different longitudes that cover a full rotation of the planet. STS does not have sufficient resolution to separate the light from the planet and the satellite. The image of the Pluto-Charon pair is clearly visible at each of the four wavelengths. We will discuss the spectral reflectance in terms of models that include the known components of Pluto and Charon s surfaces, and evidence for diurnal variations.

  4. Method of Detecting Coliform Bacteria from Reflected Light

    NASA Technical Reports Server (NTRS)

    Vincent, Robert K. (Inventor)

    2014-01-01

    The present invention relates to a method of detecting coliform bacteria in water from reflected light, and also includes devices for the measurement, calculation and transmission of data relating to that method.

  5. Angle-dependent infrared reflectance measurements in support of VIIRS

    NASA Astrophysics Data System (ADS)

    Kaplan, Simon G.; Iglesias, Enrique J.; Hanssen, Leonard M.

    2008-08-01

    We have developed a goniometric reflectometer using a Fourier-transform infrared (FTIR) spectrometer source for polarized reflectance measurements from 1 μm to 20 μm wavelength at angles of incidence from 10° to 80°, with an incident beam geometry of approximately f/25. Measurements are performed in either absolute mode, or relative to a reference mirror that has been calibrated at near-normal incidence using an integrating sphere-based reflectometer. Uncertainties in the 0.2 % to 0.5 % range are achieved using a photoconductive 77 K InSb detector from 1 μm to 5 μm and a 12 K Si:As BIB detector from 2 μm to 20 μm. The performance of the system has been tested using dielectric materials such as Si as well as high-quality Au mirrors. We describe measurements of SiOx-coated Ag mirrors to assess their performance for such applications as the half-angle mirror (HAM) in the VIIRS optical scanning system. Various coatings are analyzed to help assess the effect of p-polarized absorption bands at angles of incidence from 10° to 65° and wavelengths between 3 μm and 13 μm.

  6. Development of an ultra-compact mid-infrared attenuated total reflectance spectrophotometer

    NASA Astrophysics Data System (ADS)

    Kim, Dong Soo; Lee, Tae-Ro; Yoon, Gilwon

    2014-07-01

    Mid-infrared spectroscopy has been an important tool widely used for qualitative analysis in various fields. However, portable or personal use is size and cost prohibitive for either Fourier transform infrared or attenuated total reflectance (ATR) spectrophotometers. In this study, we developed an ultra-compact ATR spectrophotometer whose frequency band was 5.5-11.0 μm. We used miniature components, such as a light source fabricated by semiconductor technology, a linear variable filter, and a pyro-electric array detector. There were no moving parts. Optimal design based on two light sources, a zippered configuration of the array detector and ATR optics could produce absorption spectra that might be used for qualitative analysis. A microprocessor synchronized the pulsed light sources and detector, and all the signals were processed digitally. The size was 13.5×8.5×3.5 cm3 and the weight was 300 grams. Due to its low cost, our spectrophotometer can replace many online monitoring devices. Another application could be for a u-healthcare system installed in the bathroom or attached to a smartphone for monitoring substances in body fluids.

  7. Design and realization of a contact-less interaction system based on infrared reflection photoelectric detection array

    NASA Astrophysics Data System (ADS)

    Liu, Fei; Lei, Bing; Feng, Ying

    2015-10-01

    Due to the good performance of high sensitivity, quick response and low cost, infrared reflection detection technology is widely used in various fields. In this work, we present a novel contact-less interaction system which is based on infrared reflection detection technology. The system is mainly composed of a Micro Controller Unit (MCU), upper computer and photoelectric detection module. The MCU is utilized to control the photoelectric detection module and to make sure that the sensing unit is lighted one by one in a given order. When the interactive object appears upon the infrared reflection photoelectric detection array, its position information will be ensured and sent to the upper computer through MCU. In this system, every sensing unit is lighted for 1ms, and the detection array includes 8×8 units. It means that the photoelectric detection array will scan 15.6 times per-second. The experimental research results indicate that the factors affecting the detection range including the working current of transmitting diode, modulation frequency, and the reflectivity of the interactive object. When the working current is 10mA, and the modulation frequency is 80 KHz, the system has a detection range of 20 cm. Moreover, efficient modulation and demodulation of optical signal is quite necessary to remove the influence of surrounding light.

  8. Light Reflection from Water Surfaces Perturbed by Falling Rain Droplets

    ERIC Educational Resources Information Center

    Molesini, Giuseppe; Vannoni, Maurizio

    2009-01-01

    An account of peculiar light patterns produced by reflection in a pool under falling rain droplets was recently reported by Molesini and Vannoni (2008 Eur. J. Phys. 29 403-11). The mathematical approach, however, only covered the case of a symmetrical location of a light source and the observer's eyes with respect to the vertical of the falling…

  9. Self-assembled flower-like antimony trioxide microstructures with high infrared reflectance performance

    SciTech Connect

    Ge, Shengsong; Yang, Xiaokun; Shao, Qian; Liu, Qingyun; Wang, Tiejun; Wang, Lingyun; Wang, Xiaojie

    2013-04-15

    A simple hydrothermal process was adopted to self-assembly prepare high infrared reflective antimony trioxide with three-dimensional flower-like microstructures. The morphologies of antimony trioxide microstructures were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high resolution transmission electron microscopy (HRTEM) respectively. It is also found that experimental parameters, such as NaOH concentration, surfactant concentration and volume ratio of ethanol–water played crucial roles in controlling the morphologies of Sb{sub 2}O{sub 3} microstructures. A possible growth mechanism of flower-like Sb{sub 2}O{sub 3} microstructure was proposed based on the experimental data. UV–vis–NIR spectra verified that the near infrared reflectivity of the obtained flower-like microstructures could averagely achieve as 92% with maximum reflectivity of 98%, obviously higher than that of other different morphologies of antimony trioxide microstructures. It is expected that the flower-like Sb{sub 2}O{sub 3} nanostructures have some applications in optical materials and heat insulation coatings. - Graphical abstract: Flower-like Sb{sub 2}O{sub 3} microstructures that composed of nanosheets with thickness of ca. 100 nm exhibit high reflectivity under UV–vis–NIR spectra. Highlights: ► Uniform flower-like microstructures were synthesized via simple hydrothermal reaction. ► The flower-like Sb{sub 2}O{sub 3} microstructures exhibited higher reflectivity than other morphologies under the UV–vis–NIR light. ► Influencing parameters on the Sb{sub 2}O{sub 3} morphologies have been discussed in detail. ► Possible mechanism leading to flower-like microstructures was proposed.

  10. Measuring Snow Grain Size with the Near-Infrared Emitting Reflectance Dome (NERD)

    NASA Astrophysics Data System (ADS)

    Schneider, A. M.; Flanner, M.

    2014-12-01

    Because of its high visible albedo, snow plays a large role in Earth's surface energy balance. This role is a subject of intense study, but due to the wide range of snow albedo, variations in the characteristics of snow grains can introduce radiative feedbacks in a snow pack. Snow grain size, for example, is one property which directly affects a snow pack's absorption spectrum. Previous studies model and observe this spectrum, but potential feedbacks induced by these variations are largely unknown. Here, we implement a simple and inexpensive technique to measure snow grain size in an instrument we call the Near-infrared Emitting Reflectance Dome (NERD). A small black styrene dome (~17cm diameter), fitted with two narrowband light-emitting diodes (LEDs) centered around 1300nm and 1550nm and three near-infrared reverse-biased photodiodes, is placed over the snow surface enabling a multi-spectral measurement of the hemispheric directional reflectance factor (HDRF). We illuminate the snow at each wavelength, measure directional reflectance, and infer grain size from the difference in HDRFs measured on the same snow crystals at fixed viewing angles. We validate measurements from the NERD using two different reflectance standards, materials designed to be near perfect Lambertian reflectors, having known, constant reflectances (~99% and ~55%) across a wide range of wavelengths. Using a 3D Monte Carlo model simulating photon pathways through a pack of spherical snow grains, we calculate the difference in HDRFs at 1300nm and 1550nm to predict the calibration curve for a wide range of grain sizes. This theoretically derived curve gives a relationship between effective radius and the difference in HDRFs and allows us to approximate grain sizes using the NERD in just a few seconds. Further calibration requires knowledge of truth values attainable using a previously validated instrument or measurements from an inter-comparison workshop.

  11. Bio-inspired, subwavelength surface structures to control reflectivity, transmission, and scattering in the infrared

    NASA Astrophysics Data System (ADS)

    Lora Gonzalez, Federico

    Controlling the reflection of visible and infrared (IR) light at interfaces is extremely important to increase the power efficiency and performance of optics, electro-optical and (thermo)photovoltaic systems. The eye of the moth has evolved subwavelength protuberances that increase light transmission into the eye tissue and prevent reflection. The subwavelength protuberances effectively grade the refractive index from that of air (n=1) to that of the tissue (n=1.4), making the interface gradual, suppressing reflection. In theory, the moth-eye (ME) structures can be implemented with any material platform to achieve an antireflectance effect by scaling the pitch and size of protuberances for the wavelength range of interest. In this work, a bio-inspired, scalable and substrate-independent surface modification protocol was developed to realize broadband antireflective structures based on the moth-eye principle. Quasi-ordered ME arrays were fabricated in IR relevant materials using a colloidal lithography method to achieve highly efficient, omni-directional transmission of mid and far infrared (IR) radiation. The effect of structure height and aspect ratio on transmittance and scattering is explored, with discussion on experimental techniques and effective medium theory (EMT). The highest aspect ratio structures (AR = 9.4) achieved peak single-side transmittance of 98%, with >85% transmission for lambda = 7--30 microns. A detailed photon balance constructed by transmission, forward scattering, specular reflection and diffuse reflection measurements to quantify optical losses due to near-field effects will be discussed. In addition, angle-dependent transmission measurements showed that moth-eye structures provide superior antireflective properties compared to unstructured interfaces over a wide angular range (0--60° incidence). Finally, subwavelength ME structures are incorporated on a Si substrate to enhance the absorption of near infrared (NIR) light in PtSi films to

  12. A system for simultaneous near-infrared reflectance and transillumination imaging of occlusal carious lesions

    NASA Astrophysics Data System (ADS)

    Simon, Jacob C.; Darling, Cynthia L.; Fried, Daniel

    2016-02-01

    Clinicians need technologies to improve the diagnosis of questionable occlusal carious lesions (QOC's) and determine if decay has penetrated to the underlying dentin. Assessing lesion depth from near-infrared (NIR) images holds great potential due to the high transparency of enamel and stain to NIR light at λ=1300-1700-nm, which allows direct visualization and quantified measurements of enamel demineralization. Unfortunately, NIR reflectance measurements alone are limited in utility for approximating occlusal lesion depth >200-μm due to light attenuation from the lesion body. Previous studies sought to combine NIR reflectance and transillumination measurements taken at λ=1300-nm in order to estimate QOC depth and severity. The objective of this study was to quantify the change in lesion contrast and size measured from multispectral NIR reflectance and transillumination images of natural occlusal carious lesions with increasing lesion depth and severity in order to determine the optimal multimodal wavelength combinations for estimating QOC depth. Extracted teeth with varying amounts of natural occlusal decay were measured using a multispectral-multimodal NIR imaging system at prominent wavelengths within the λ=1300-1700-nm spectral region. Image analysis software was used to calculate lesion contrast and area values between sound and carious enamel regions.

  13. Long-Term Reduction in Infrared Autofluorescence Caused by Infrared Light Below the Maximum Permissible Exposure

    PubMed Central

    Masella, Benjamin D.; Williams, David R.; Fischer, William S.; Rossi, Ethan A.; Hunter, Jennifer J.

    2014-01-01

    Purpose. Many retinal imaging instruments use infrared wavelengths to reduce the risk of light damage. However, we have discovered that exposure to infrared illumination causes a long-lasting reduction in infrared autofluorescence (IRAF). We have characterized the dependence of this effect on radiant exposure and investigated its origin. Methods. A scanning laser ophthalmoscope was used to obtain IRAF images from two macaques before and after exposure to 790-nm light (15-450 J/cm2). Exposures were performed with either raster-scanning or uniform illumination. Infrared autofluorescence images also were obtained in two humans exposed to 790-nm light in a separate study. Humans were assessed with direct ophthalmoscopy, Goldmann visual fields, multifocal ERG, and photopic microperimetry to determine whether these measures revealed any effects in the exposed locations. Results. A significant decrease in IRAF after exposure to infrared light was seen in both monkeys and humans. In monkeys, the magnitude of this reduction increased with retinal radiant exposure. Partial recovery was seen at 1 month, with full recovery within 21 months. Consistent with a photochemical origin, IRAF decreases caused by either raster-scanning or uniform illumination were not significantly different. We were unable to detect any effect of the light exposure with any measure other than IRAF imaging. We cannot exclude the possibility that changes could be detected with more sensitive tests or longer follow-up. Conclusions. This long-lasting effect of infrared illumination in both humans and monkeys occurs at exposure levels four to five times below current safety limits. The photochemical basis for this phenomenon remains unknown. PMID:24845640

  14. Cholesteric liquid crystals with a broad light reflection band.

    PubMed

    Mitov, Michel

    2012-12-11

    The cholesteric-liquid-crystalline structure, which concerns the organization of chromatin, collagen, chitin, or cellulose, is omnipresent in living matter. In technology, it is found in temperature and pressure sensors, supertwisted nematic liquid crystal displays, optical filters, reflective devices, or cosmetics. A cholesteric liquid crystal reflects light because of its helical structure. The reflection is selective - the bandwidth is limited to a few tens of nanometers and the reflectance is equal to at most 50% for unpolarized incident light, which is a consequence of the polarization-selectivity rule. These limits must be exceeded for innovative applications like polarizer-free reflective displays, broadband polarizers, optical data storage media, polarization-independent devices, stealth technologies, or smart switchable reflective windows to control solar light and heat. Novel cholesteric-liquid-crystalline architectures with the related fabrication procedures must therefore be developed. This article reviews solutions found in living matter and laboratories to broaden the bandwidth around a central reflection wavelength, do without the polarization-selectivity rule and go beyond the reflectance limit. PMID:23090724

  15. Strong transmittance above the light line in mid-infrared two-dimensional photonic crystals

    NASA Astrophysics Data System (ADS)

    Kraeh, Christian; Martinez-Hurtado, J. L.; Zeitlmair, Martin; Popescu, Alexandru; Hedler, Harry; Finley, Jonathan J.

    2015-06-01

    The mid-infrared region of the electromagnetic spectrum between 3 and 8 μm hosts absorption lines of gases relevant for chemical and biological sensing. 2D photonic crystal structures capable of guiding light in this region of the spectrum have been widely studied, and their implementation into miniaturized sensors has been proposed. However, light guiding in conventional 2D photonic crystals is usually restricted to a frequency range below the light line, which is the dispersion relation of light in the media surrounding the structures. These structures rely on total internal reflection for confinement of the light in z-direction normal to the lattice plane. In this work, 2D mid-infrared photonic crystals consisting of microtube arrays that mitigate these limitations have been developed. Due to their high aspect ratios of ˜1:30, they are perceived as semi-infinite in the z-direction. Light transmission experiments in the 5-8 μm range reveal attenuations as low as 0.27 dB/100 μm, surpassing the limitations for light guiding above the light line in conventional 2D photonic crystals. Fair agreement is obtained between these experiments, 2D band structure and transmission simulations.

  16. Strong transmittance above the light line in mid-infrared two-dimensional photonic crystals

    SciTech Connect

    Kraeh, Christian; Martinez-Hurtado, J. L.; Zeitlmair, Martin; Finley, Jonathan J.; Popescu, Alexandru; Hedler, Harry

    2015-06-14

    The mid-infrared region of the electromagnetic spectrum between 3 and 8 μm hosts absorption lines of gases relevant for chemical and biological sensing. 2D photonic crystal structures capable of guiding light in this region of the spectrum have been widely studied, and their implementation into miniaturized sensors has been proposed. However, light guiding in conventional 2D photonic crystals is usually restricted to a frequency range below the light line, which is the dispersion relation of light in the media surrounding the structures. These structures rely on total internal reflection for confinement of the light in z-direction normal to the lattice plane. In this work, 2D mid-infrared photonic crystals consisting of microtube arrays that mitigate these limitations have been developed. Due to their high aspect ratios of ∼1:30, they are perceived as semi-infinite in the z-direction. Light transmission experiments in the 5–8 μm range reveal attenuations as low as 0.27 dB/100 μm, surpassing the limitations for light guiding above the light line in conventional 2D photonic crystals. Fair agreement is obtained between these experiments, 2D band structure and transmission simulations.

  17. Determination of plant silicon content with near infrared reflectance spectroscopy

    PubMed Central

    Smis, Adriaan; Ancin Murguzur, Francisco Javier; Struyf, Eric; Soininen, Eeva M.; Herranz Jusdado, Juan G.; Meire, Patrick; Bråthen, Kari Anne

    2014-01-01

    Silicon (Si) is one of the most common elements in the earth bedrock, and its continental cycle is strongly biologically controlled. Yet, research on the biogeochemical cycle of Si in ecosystems is hampered by the time and cost associated with the currently used chemical analysis methods. Here, we assessed the suitability of Near Infrared Reflectance Spectroscopy (NIRS) for measuring Si content in plant tissues. NIR spectra depend on the characteristics of the present bonds between H and N, C and O, which can be calibrated against concentrations of various compounds. Because Si in plants always occurs as hydrated condensates of orthosilicic acid (Si(OH)4), linked to organic biomolecules, we hypothesized that NIRS is suitable for measuring Si content in plants across a range of plant species. We based our testing on 442 samples of 29 plant species belonging to a range of growth forms. We calibrated the NIRS method against a well-established plant Si analysis method by using partial least-squares regression. Si concentrations ranged from detection limit (0.24 ppmSi) to 7.8% Si on dry weight and were well predicted by NIRS. The model fit with validation data was good across all plant species (n = 141, R2 = 0.90, RMSEP = 0.24), but improved when only graminoids were modeled (n = 66, R2 = 0.95, RMSEP = 0.10). A species specific model for the grass Deschampsia cespitosa showed even slightly better results than the model for all graminoids (n = 16, R2 = 0.93, RMSEP = 0.015). We show for the first time that NIRS is applicable for determining plant Si concentration across a range of plant species and growth forms, and represents a time- and cost-effective alternative to the chemical Si analysis methods. As NIRS can be applied concurrently to a range of plant organic constituents, it opens up unprecedented research possibilities for studying interrelations between Si and other plant compounds in vegetation, and for addressing the role of Si in ecosystems across a range of Si

  18. Far-Infrared Beamline at the Canadian Light Source

    NASA Astrophysics Data System (ADS)

    Billinghurst, Brant E.; May, Tim E.

    2014-06-01

    The far-infrared beamline at the Canadian Light Source is a state of the art user facility, which offers significantly more far-infrared brightness than conventional globar sources. The infrared radiation is collected from a bending magnet through a 55 X 37 mrad2 port to a Bruker IFS 125 HR spectrometer, which is equipped with a nine compartment scanning arm, allowing it to achieve spectral resolution better than 0.001 cm-1. Currently the beamline can achieve signal to noise ratios up to 8 times that which can be achieved using a traditional thermal source. This talk will provide an overview of the the beamline, and the capabilities available to users, recent and planned improvements including the addition of a Glow Discharge cell and advances in Coherent Synchrotron Radiation. Furthermore, the process of acquiring access to the facility will be covered.

  19. Properties of light reflected from road signs in active imaging.

    PubMed

    Halstuch, Aviran; Yitzhaky, Yitzhak

    2008-08-01

    Night vision systems in vehicles are a new emerging technology. A crucial problem in active (laser-based) systems is distortion of images by saturation and blooming due to strong retroreflections from road signs. We quantify this phenomenon. We measure the Mueller matrices and the polarization state of the reflected light from three different types of road sign commonly used. Measurements of the reflected intensity are also taken with respect to the angle of reflection. We find that different types of sign have different reflection properties. It is concluded that the optimal solution for attenuating the retroreflected intensity is using a linear polarized light source and a linear polarizer with perpendicular orientation (with regard to the source) at the detector. Unfortunately, while this solution performs well for two types of road sign, it is less efficient for the third sign type. PMID:18670559

  20. Automated variable wavelength interferometry in reflected light mode

    NASA Astrophysics Data System (ADS)

    Litwin, D.; Galas, J.; Blocki, N.

    2006-04-01

    The paper concentrates on the double-refracting systems - particularly variable wavelength techniques (VAWI) for reflected light... The family of techniques for (transmitted and reflected light) is especially recommended for studying objects, which produce optical path difference more than a few wavelengths. In such cases classical approach consisting in measuring deflection of interference fringes is not useful because of edge effects that break continuity of interference fringes. The VAWI methods have been invented in the time when image processing devices and computers were hardly available. Automated devices unfold a completely new approach to the classical measurement procedures. The paper discusses mainly construction aspects of the systems in context of the computerised instruments.

  1. All-Quantum-Dot Infrared Light-Emitting Diodes.

    PubMed

    Yang, Zhenyu; Voznyy, Oleksandr; Liu, Mengxia; Yuan, Mingjian; Ip, Alexander H; Ahmed, Osman S; Levina, Larissa; Kinge, Sachin; Hoogland, Sjoerd; Sargent, Edward H

    2015-12-22

    Colloidal quantum dots (CQDs) are promising candidates for infrared electroluminescent devices. To date, CQD-based light-emitting diodes (LEDs) have employed a CQD emission layer sandwiched between carrier transport layers built using organic materials and inorganic oxides. Herein, we report the infrared LEDs that use quantum-tuned materials for each of the hole-transporting, the electron-transporting, and the light-emitting layers. We successfully tailor the bandgap and band position of each CQD-based component to produce electroluminescent devices that exhibit emission that we tune from 1220 to 1622 nm. Devices emitting at 1350 nm achieve peak external quantum efficiency up to 1.6% with a low turn-on voltage of 1.2 V, surpassing previously reported all-inorganic CQD LEDs.

  2. Transient and selective suppression of neural activity with infrared light

    PubMed Central

    Duke, Austin R.; Jenkins, Michael W.; Lu, Hui; McManus, Jeffrey M.; Chiel, Hillel J.; Jansen, E. Duco

    2013-01-01

    Analysis and control of neural circuitry requires the ability to selectively activate or inhibit neurons. Previous work showed that infrared laser light selectively excited neural activity in endogenous unmyelinated and myelinated axons. However, inhibition of neuronal firing with infrared light was only observed in limited cases, is not well understood and was not precisely controlled. Using an experimentally tractable unmyelinated preparation for detailed investigation and a myelinated preparation for validation, we report that it is possible to selectively and transiently inhibit electrically-initiated axonal activation, as well as to both block or enhance the propagation of action potentials of specific motor neurons. Thus, in addition to previously shown excitation, we demonstrate an optical method of suppressing components of the nervous system with functional spatiotemporal precision. We believe this technique is well-suited for non-invasive investigations of diverse excitable tissues and may ultimately be applied for treating neurological disorders. PMID:24009039

  3. Near-infrared light activated azo-BF2 switches.

    PubMed

    Yang, Yin; Hughes, Russell P; Aprahamian, Ivan

    2014-09-24

    Increasing the electron density in BF2-coodinated azo compounds through para-substitution leads to a bathochromic shift in their activation wavelength. When the substituent is dimethyl amine, or the like, the trans/cis isomerization process can be efficiently modulated using near infrared light. The electron donating capability of the substituent also controls the hydrolysis half-life of the switch in aqueous solution, which is drastically longer for the cis isomer, while the BF2-coodination prevents reduction by glutathione.

  4. High Efficiency Near Infrared Spectrometer for Zodiacal Light Spectral Study

    NASA Technical Reports Server (NTRS)

    Kutyrea, A. S.

    2008-01-01

    We are developing a near infrared spectrometer for measuring solar absorption lines in the zodiacal light in the near infrared region. R. Reynolds at el. (2004, ApJ 61 2, 1206) demonstrated that observing single Fraunhofer line can be a powerful tool for extracting zodiacal light parameters based on their measurements of the profile of the Mg I lneat 5 184 A. We are extending this technique to the near infrared with the primary goal of measuring the absolute intensity of the zodiacal light. This measurement will provide the crucial information needed to accurately subtract zodiacal emission from the DIRBE measurements to get a much higher quality measurement of the extragalactic IR background. The instrument design is based on a dual Fabry-Perot interferometer with a narrow band filter. Its double etalon design allows to achieve high spectral contrast to reject the bright out of band telluric OH emission. High spectral contrast is absolutely necessary to achieve detection limits needed to accurately measure the intensity of the absorption line. We present the design, estimated performance of the instrument with the expected results of the observing program.

  5. Reflection of femtosecond laser light in multipulse ablation of metals

    SciTech Connect

    Vorobyev, A. Y.; Guo Chunlei

    2011-08-15

    The shot-to-shot reflectance of high-intensity laser light is studied as a function of both the number of laser shots and laser fluence in multipulse ablation of a metal when the irradiated surface undergoes structural changes from an initially smooth surface to a deep crater. Our study shows that the reflectance of the irradiated surface significantly decreases due to the high intensity of laser pulses and the laser-induced surface structures in ablation regimes typically used for femtosecond laser processing of materials. The high-intensity effect dominates in the reflection reduction at low numbers of laser shots when laser-induced surface structures do not cause the reflectance to decrease noticeably. With increasing the number of laser shots, the structural effect comes into play, and both high-intensity and structural effects quickly reduce the reflectance of the sample to a low value.

  6. Engineering adenylate cyclases regulated by near-infrared window light

    PubMed Central

    Ryu, Min-Hyung; Kang, In-Hye; Nelson, Mathew D.; Jensen, Tricia M.; Lyuksyutova, Anna I.; Siltberg-Liberles, Jessica; Raizen, David M.; Gomelsky, Mark

    2014-01-01

    Bacteriophytochromes sense light in the near-infrared window, the spectral region where absorption by mammalian tissues is minimal, and their chromophore, biliverdin IXα, is naturally present in animal cells. These properties make bacteriophytochromes particularly attractive for optogenetic applications. However, the lack of understanding of how light-induced conformational changes control output activities has hindered engineering of bacteriophytochrome-based optogenetic tools. Many bacteriophytochromes function as homodimeric enzymes, in which light-induced conformational changes are transferred via α-helical linkers to the rigid output domains. We hypothesized that heterologous output domains requiring homodimerization can be fused to the photosensory modules of bacteriophytochromes to generate light-activated fusions. Here, we tested this hypothesis by engineering adenylate cyclases regulated by light in the near-infrared spectral window using the photosensory module of the Rhodobacter sphaeroides bacteriophytochrome BphG1 and the adenylate cyclase domain from Nostoc sp. CyaB1. We engineered several light-activated fusion proteins that differed from each other by approximately one or two α-helical turns, suggesting that positioning of the output domains in the same phase of the helix is important for light-dependent activity. Extensive mutagenesis of one of these fusions resulted in an adenylate cyclase with a sixfold photodynamic range. Additional mutagenesis produced an enzyme with a more stable photoactivated state. When expressed in cholinergic neurons in Caenorhabditis elegans, the engineered adenylate cyclase affected worm behavior in a light-dependent manner. The insights derived from this study can be applied to the engineering of other homodimeric bacteriophytochromes, which will further expand the optogenetic toolset. PMID:24982160

  7. Near infrared reflection spectra of artificial cumulus clouds.

    PubMed

    Plummer, W T

    1969-10-01

    Reflection spectra are presented for artificial cumulus clouds with a progression of droplet sizes, including sizes common in natural clouds, over the wavelength range from 1.0 micro to 2.4 micro. A correction is made for gaseous absorption. The spectra show reflectivity minima at 1.16 micro, 1.41 micro, and 1.92micro which deepen as the droplets become larger and are in good agreement with reflection spectra of terrestrial clouds.

  8. Light Reflection in a Pool under Falling Rain Droplets

    ERIC Educational Resources Information Center

    Molesini, Giuseppe; Vannoni, Maurizio

    2008-01-01

    The observation of peculiar light patterns produced by reflection from a water surface perturbed by falling droplets is reported. The phenomenon is analysed in some detail, with a simplified model of a surface wave packet. A simple experiment reproducing the phenomenon in the laboratory is presented, also showing evidence of pattern distortions…

  9. Robust near-infrared light bullet in 800-nm femtosecond light filaments in air

    NASA Astrophysics Data System (ADS)

    Panov, Nikolay A.; Shipilo, Daniil E.; Andreeva, Vera A.; Uryupina, Daria S.; Savel'ev, Andrei B.; Kosareva, Olga G.; Chin, See Leang

    2015-09-01

    Systematic numerical study of near-infrared radiation formed during filamentation in air revealed the formation of robust light bullet first registered in the experiment (Chen et al. in Appl Phys B 91:219, 2008). The near-infrared light bullet propagates along the filament axis with the divergence <1 mrad and the quasi-constant duration of ~30 fs. The central wavelength of the bullet gradually increases from 860 to 900 nm during the propagation. The results of our numerical simulation are in agreement with the experiments (Chen et al. in Appl Phys B 91:219, 2008; Uryupina et al. in Appl Phys B 110:123, 2013).

  10. Non-invasive identification of metal-oxalate complexes on polychrome artwork surfaces by reflection mid-infrared spectroscopy.

    PubMed

    Monico, Letizia; Rosi, Francesca; Miliani, Costanza; Daveri, Alessia; Brunetti, Brunetto G

    2013-12-01

    In this work a reflection mid-infrared spectroscopy study of twelve metal-oxalate complexes, of interest in art conservation science as alteration compounds, was performed. Spectra of the reference materials highlighted the presence of derivative-like and/or inverted features for the fundamental vibrational modes as result of the main contribution from the surface component of the reflected light. In order to provide insights in the interpretation of theses spectral distortions, reflection spectra were compared with conventional transmission ones. The Kramers-Kronig (KK) algorithm, employed to correct for the surface reflection distortions, worked properly only for the derivative-like bands. Therefore, to pay attention to the use of this algorithm when interpreting the reflection spectra is recommended. The outcome of this investigation was exploited to discriminate among different oxalates on thirteen polychrome artworks analyzed in situ by reflection mid-infrared spectroscopy. The visualization of the νs(CO) modes (1400-1200 cm(-1)) and low wavenumber bands (below 900 cm(-1)) in the raw reflection profiles allowed Ca, Cu and Zn oxalates to be identified. Further information about the speciation of different hydration forms of calcium oxalates were obtained by using the KK transform. The work proves reflection mid-infrared spectroscopy to be a reliable and sensitive spectro-analytical method for identifying and mapping different metal-oxalate alteration compounds on the surface of artworks, thus providing conservation scientists with a non-invasive tool to obtain information on the state of conservation and causes of alteration of artworks.

  11. Characterization and Application of a Grazing Angle Objective for Quantitative Infrared Reflection Microspectroscopy

    NASA Technical Reports Server (NTRS)

    Pepper, Stephen V.

    1995-01-01

    A grazing angle objective on an infrared microspectrometer is studied for quantitative spectroscopy by considering the angular dependence of the incident intensity within the objective's angular aperture. The assumption that there is no angular dependence is tested by comparing the experimental reflectance of Si and KBr surfaces with the reflectance calculated by integrating the Fresnel reflection coefficient over the angular aperture under this assumption. Good agreement was found, indicating that the specular reflectance of surfaces can straight-forwardly be quantitatively integrated over the angular aperture without considering non-uniform incident intensity. This quantitative approach is applied to the thickness determination of dipcoated Krytox on gold. The infrared optical constants of both materials are known, allowing the integration to be carried out. The thickness obtained is in fair agreement with the value determined by ellipsometry in the visible. Therefore, this paper illustrates a method for more quantitative use of a grazing angle objective for infrared reflectance microspectroscopy.

  12. Tree Canopy Characterization for EO-1 Reflective and Thermal Infrared Validation Studies: Rochester, New York

    NASA Technical Reports Server (NTRS)

    Ballard, Jerrell R., Jr.; Smith, James A.

    2002-01-01

    The tree canopy characterization presented herein provided ground and tree canopy data for different types of tree canopies in support of EO-1 reflective and thermal infrared validation studies. These characterization efforts during August and September of 2001 included stem and trunk location surveys, tree structure geometry measurements, meteorology, and leaf area index (LAI) measurements. Measurements were also collected on thermal and reflective spectral properties of leaves, tree bark, leaf litter, soil, and grass. The data presented in this report were used to generate synthetic reflective and thermal infrared scenes and images that were used for the EO-1 Validation Program. The data also were used to evaluate whether the EO-1 ALI reflective channels can be combined with the Landsat-7 ETM+ thermal infrared channel to estimate canopy temperature, and also test the effects of separating the thermal and reflective measurements in time resulting from satellite formation flying.

  13. [Application of near infrared reflectance spectroscopy to predict meat chemical compositions: a review].

    PubMed

    Tao, Lin-Li; Yang, Xiu-Juan; Deng, Jun-Ming; Zhang, Xi

    2013-11-01

    In contrast to conventional methods for the determination of meat chemical composition, near infrared reflectance spectroscopy enables rapid, simple, secure and simultaneous assessment of numerous meat properties. The present review focuses on the use of near infrared reflectance spectroscopy to predict meat chemical compositions. The potential of near infrared reflectance spectroscopy to predict crude protein, intramuscular fat, fatty acid, moisture, ash, myoglobin and collagen of beef, pork, chicken and lamb is reviewed. This paper discusses existing questions and reasons in the current research. According to the published results, although published results vary considerably, they suggest that near-infrared reflectance spectroscopy shows a great potential to replace the expensive and time-consuming chemical analysis of meat composition. In particular, under commercial conditions where simultaneous measurements of different chemical components are required, near infrared reflectance spectroscopy is expected to be the method of choice. The majority of studies selected feature-related wavelengths using principal components regression, developed the calibration model using partial least squares and modified partial least squares, and estimated the prediction accuracy by means of cross-validation using the same sample set previously used for the calibration. Meat fatty acid composition predicted by near-infrared spectroscopy and non-destructive prediction and visualization of chemical composition in meat using near-infrared hyperspectral imaging and multivariate regression are the hot studying field now. On the other hand, near infrared reflectance spectroscopy shows great difference for predicting different attributes of meat quality which are closely related to the selection of calibration sample set, preprocessing of near-infrared spectroscopy and modeling approach. Sample preparation also has an important effect on the reliability of NIR prediction; in particular

  14. Infrared light gated MoS₂ field effect transistor.

    PubMed

    Fang, Huajing; Lin, Ziyuan; Wang, Xinsheng; Tang, Chun-Yin; Chen, Yan; Zhang, Fan; Chai, Yang; Li, Qiang; Yan, Qingfeng; Chan, H L W; Dai, Ji-Yan

    2015-12-14

    Molybdenum disulfide (MoS₂) as a promising 2D material has attracted extensive attentions due to its unique physical, optical and electrical properties. In this work, we demonstrate an infrared (IR) light gated MoS₂ transistor through a device composed of MoS₂ monolayer and a ferroelectric single crystal Pb(Mg(1/3)Nb(2/3))O₃-PbTiO₃ (PMN-PT). With a monolayer MoS₂ onto the top surface of (111) PMN-PT crystal, the drain current of MoS₂ channel can be modulated with infrared illumination and this modulation process is reversible. Thus, the transistor can work as a new kind of IR photodetector with a high IR responsivity of 114%/Wcm⁻². The IR response of MoS₂ transistor is attributed to the polarization change of PMN-PT single crystal induced by the pyroelectric effect which results in a field effect. Our result promises the application of MoS₂ 2D material in infrared optoelectronic devices. Combining with the intrinsic photocurrent feature of MoS₂ in the visible range, the MoS₂ on ferroelectric single crystal may be sensitive to a broadband wavelength of light.

  15. Infrared light gated MoS₂ field effect transistor.

    PubMed

    Fang, Huajing; Lin, Ziyuan; Wang, Xinsheng; Tang, Chun-Yin; Chen, Yan; Zhang, Fan; Chai, Yang; Li, Qiang; Yan, Qingfeng; Chan, H L W; Dai, Ji-Yan

    2015-12-14

    Molybdenum disulfide (MoS₂) as a promising 2D material has attracted extensive attentions due to its unique physical, optical and electrical properties. In this work, we demonstrate an infrared (IR) light gated MoS₂ transistor through a device composed of MoS₂ monolayer and a ferroelectric single crystal Pb(Mg(1/3)Nb(2/3))O₃-PbTiO₃ (PMN-PT). With a monolayer MoS₂ onto the top surface of (111) PMN-PT crystal, the drain current of MoS₂ channel can be modulated with infrared illumination and this modulation process is reversible. Thus, the transistor can work as a new kind of IR photodetector with a high IR responsivity of 114%/Wcm⁻². The IR response of MoS₂ transistor is attributed to the polarization change of PMN-PT single crystal induced by the pyroelectric effect which results in a field effect. Our result promises the application of MoS₂ 2D material in infrared optoelectronic devices. Combining with the intrinsic photocurrent feature of MoS₂ in the visible range, the MoS₂ on ferroelectric single crystal may be sensitive to a broadband wavelength of light. PMID:26698982

  16. Chemical Imaging of Biological Tissue with Synchrotron Infrared Light

    SciTech Connect

    Miller,L.; Dumas, P.

    2006-01-01

    Fourier transform infrared micro-spectroscopy (FTIRM) and imaging (FTIRI) have become valuable techniques for examining the chemical makeup of biological materials by probing their vibrational motions on a microscopic scale. Synchrotron infrared (S-IR) light is an ideal source for FTIRM and FTIRI due to the combination of its high brightness (i.e., flux density), also called brilliance, and broadband nature. Through a 10-{mu}m pinhole, the brightness of a synchrotron source is 100-1000 times higher than a conventional thermal (globar) source. Accordingly, the improvement in spatial resolution and in spectral quality to the diffraction limit has led to a plethora of applications that is just being realized. In this review, we describe the development of synchrotron-based FTIRM, illustrate its advantages in many applications to biological systems, and propose some potential future directions for the technique.

  17. Generation of infrared entangled light in asymmetric semiconductor quantum wells

    NASA Astrophysics Data System (ADS)

    Lü, Xin-You; Wu, Jing; Zheng, Li-Li; Huang, Pei

    2010-12-01

    We proposed a scheme to achieve two-mode CV entanglement with the frequencies of entangled modes in the infrared range in an asymmetric semiconductor double-quantum-wells (DQW), where the required quantum coherence is obtained by inducing the corresponding intersubband transitions (ISBTs) with a classical field. By numerically simulating the dynamics of system, we show that the entanglement period can be prolonged via enhancing the intensity of classical field, and the generation of entanglement doesn't depend intensively on the initial condition of system in our scheme. Moreover, we also show that a bipartite entanglement amplifier can be realized in our scheme. The present research provides an efficient approach to achieve infrared entangled light in the semiconductor nanostructure, which may have significant impact on the progress of solid-state quantum information theory.

  18. Stray-light suppression in a reflecting white-light coronagraph.

    PubMed

    Romoli, M; Weiser, H; Gardner, L D; Kohl, J L

    1993-07-01

    An analysis of stray-light suppression in the white-light channel of the Ultraviolet Coronagraph Spectrometer experiment for the Solar and Heliospheric Observatory is reported. The white-light channel consists of a reflecting telescope with external and internal occultation and a polarimeter section. Laboratory tests and analytical methods are used to perform the analysis. The various stray-light contributions are classified in two main categories: the contribution from sunlight that passes directly through the entrance aperture and the contribution of sunlight that is diffracted by the edges of the entrance aperture. Values of the stray-light contributions from various sources and the total stray-light level for observations at heliocentric heights from 1.4 to 5 solar radii are derived. Anticipated signal-to-stray-light ratios are presented together with the effective stray-light rejection by the polarimeter, demonstrating the efficacy of the stray-light suppression design.

  19. Stray-light suppression in a reflecting white-light coronagraph

    NASA Astrophysics Data System (ADS)

    Romoli, Marco; Weiser, Heinz; Gardner, Larry D.; Kohl, John L.

    1993-07-01

    An analysis of stray-light suppression in the white-light channel of the Ultraviolet Coronagraph Spectrometer experiment for the Solar and Heliospheric Observatory is reported. The white-light channel consists of a reflecting telescope with external and internal occultation and a polarimeter section. Laboratory tests and analytical methods are used to perform the analysis. The various stray-light contributions are classified in two main categories: the contribution from sunlight that passes directly through the entrance aperture and the contribution of sunlight that is diffracted by the edges of the entrance aperture. Values of the stray-light contributions from various sources and the total stray-light level for observations at heliocentric heights from 1.4 to 5 solar radii are derived. Anticipated signal-to-stray-light ratios are presented together with the effective stray-light rejection by the polarimeter, demonstrating the efficacy of the stray-light suppression design.

  20. Stray-light suppression in a reflecting white-light coronagraph

    NASA Technical Reports Server (NTRS)

    Romoli, Marco; Weiser, Heinz; Gardner, Larry D.; Kohl, John L.

    1993-01-01

    An analysis of stray-light suppression in the white-light channel of the Ultraviolet Coronagraph Spectrometer experiment for the Solar and Heliospheric Observatory is reported. The white-light channel consists of a reflecting telescope with external and internal occultation and a polarimeter section. Laboratory tests and analytical methods are used to perform the analysis. The various stray-light contributions are classified in two main categories: the contribution from sunlight that passes directly through the entrance aperture and the contribution of sunlight that is diffracted by the edges of the entrance aperture. Values of the stray-light contributions from various sources and the total stray-light level for observations at heliocentric heights from 1.4 to 5 solar radii are derived. Anticipated signal-to-stray-light ratios are presented together with the effective stray-light rejection by the polarimeter, demonstrating the efficacy of the stray-light suppression design.

  1. Do cephalopods communicate using polarized light reflections from their skin?

    PubMed

    Mäthger, Lydia M; Shashar, Nadav; Hanlon, Roger T

    2009-07-01

    Cephalopods (squid, cuttlefish and octopus) are probably best known for their ability to change color and pattern for camouflage and communication. This is made possible by their complex skin, which contains pigmented chromatophore organs and structural light reflectors (iridophores and leucophores). Iridophores create colorful and linearly polarized reflective patterns. Equally interesting, the photoreceptors of cephalopod eyes are arranged in a way to give these animals the ability to detect the linear polarization of incoming light. The capacity to detect polarized light may have a variety of functions, such as prey detection, navigation, orientation and contrast enhancement. Because the skin of cephalopods can produce polarized reflective patterns, it has been postulated that cephalopods could communicate intraspecifically through this visual system. The term 'hidden' or 'private' communication channel has been given to this concept because many cephalopod predators may not be able to see their polarized reflective patterns. We review the evidence for polarization vision as well as polarization signaling in some cephalopod species and provide examples that tend to support the notion--currently unproven--that some cephalopods communicate using polarized light signals.

  2. Using near infrared light for deep sea mining observation systems

    NASA Astrophysics Data System (ADS)

    Lu, Huimin; Li, Yujie; Li, Xin; Yang, Jianmin; Serikawa, Seiichi

    2015-10-01

    In this paper, we design a novel deep-sea near infrared light based imaging equipment for deep-sea mining observation systems. The spectral sensitivity peaks are in the red region of the invisible spectrum, ranging from 750nm to 900nm. In addition, we propose a novel underwater imaging model that compensates for the attenuation discrepancy along the propagation path. The proposed model fully considered the effects of absorption, scattering and refraction. We also develop a locally adaptive Laplacian filtering for enhancing underwater transmission map after underwater dark channel prior estimation. Furthermore, we propose a spectral characteristic-based color correction algorithm to recover the distorted color. In water tank experiments, we made a linear scale of eight turbidity steps ranging from clean to heavily scattered by adding deep sea soil to the seawater (from 500 to 2000 mg/L). We compared the results of different turbidity underwater scene, illuminated alternately with near infrared light vs. white light. Experiments demonstrate that the enhanced NIR images have a reasonable noise level after the illumination compensation in the dark regions and demonstrates an improved global contrast by which the finest details and edges are significantly enhanced. We also demonstrate that the effective distance of the designed imaging system is about 1.5 meters, which can meet the requirement of micro-terrain observation around the deep-sea mining systems. Remotely Operated Underwater Vehicle (ROV)-based experiments also certified the effectiveness of the proposed method.

  3. Spectral confocal reflection microscopy using a white light source

    NASA Astrophysics Data System (ADS)

    Booth, M.; Juškaitis, R.; Wilson, T.

    2008-08-01

    We present a reflection confocal microscope incorporating a white light supercontinuum source and spectral detection. The microscope provides images resolved spatially in three-dimensions, in addition to spectral resolution covering the wavelength range 450-650nm. Images and reflection spectra of artificial and natural specimens are presented, showing features that are not normally revealed in conventional microscopes or confocal microscopes using discrete line lasers. The specimens include thin film structures on semiconductor chips, iridescent structures in Papilio blumei butterfly scales, nacre from abalone shells and opal gemstones. Quantitative size and refractive index measurements of transparent beads are derived from spectral interference bands.

  4. Comments on a peak of AlxGa1-xN observed by infrared reflectance

    NASA Astrophysics Data System (ADS)

    Marx, G.; Engelbrecht, J. A. A.; Lee, M. E.; Wagener, M. C.; Henry, A.

    2016-05-01

    AlxGa1-xN epilayers, grown on c-plane oriented sapphire substrates by metal organic chemical vapour deposition (MOCVD), were evaluated using FTIR infrared reflectance spectroscopy. A peak at ∼850 cm-1 in the reflectance spectra, not reported before, was observed. Possible origins for this peak are considered and discussed.

  5. The Infrared Reflection Nebula Around the Protostellar System in S140

    NASA Technical Reports Server (NTRS)

    Harker, D.; Bregman, J.; Tielens, A. G. G. M.; Temi, P.; Rank, D.; Morrison, David (Technical Monitor)

    1994-01-01

    We have studied the protostellar system in S140 at 2.2, 3.1 and 3.45 microns using a 128x128 InSb array at the Lick Observatory 3m telescope. Besides the protostellar sources, the data reveal a bright infrared reflection nebula. We have developed a simple model of this region and derived the physical conditions. IRSI is surrounded by a dense dusty disk viewed almost edge-on. Photons leaking out through the poles illuminate almost directly north and south the inner edge of a surrounding shell of molecular gas, Analysis of the observed colors and intensities of the NIR light, using Mie scattering theory, reveal that the dust grains in the molecular cloud are somewhat larger than in the general diffuse interstellar medium. Moreover, the incident light has a "cool" color temperature, approximately equals 800K, and likely originates from a dust photosphere close to the protostar. Finally, we find little H2O ice associated with the dusty disk around IRSI. Most of the 3.1 micron ice extinction arises instead from cool intervening molecular cloud material. We have compared our infrared dust observations with millimeter and radio observations of molecular gas associated with this region. The large scale structure observable in the molecular gas is indicative of the interaction between the protostellar wind and the surrounding molecular cloud rather than the geometry of the protostellar disk. We conclude that S140 is a young blister formed by this outflow on the side of a molecular cloud and viewed edge-on.

  6. Application of representative layer theory to near-infrared reflectance spectra of powdered samples.

    PubMed

    Cairós, Carlos; Coello, Jordi; Maspoch, Santiago

    2008-12-01

    The diffuse reflectance near-infrared (NIR) spectrum of a powdered sample includes the contribution of specular and diffuse reflectance, which is a function of absorbance and scattering. The fraction of light scattered depends in a complex manner on the physical properties of the sample such as particle size, refraction index, etc. Several theories to study the dependence of NIR spectra on the particle size have been proposed. The best known is the Kubelka-Munk model, an approach based on continuous mathematics. Recently Dahm and Dahm put forward an alternative method, the representative layer theory (RLT), which uses discontinuous mathematics as a basis. This approach can be used to identify and disentangle the scattering and absorbance signals as well as their dependence on the particle size. The scattering and absorption coefficient of NaCl (a nonabsorbing material) and of potassium hydrogen phthalate, KHP (a strong absorber), have been estimated through the application of the representative layer theory, working on a particle size range from 63 to 450 microm. In both samples, the absorption coefficient of the sample (K) remains constant and practically independent of the particle size, while the scattering coefficient of the sample (S) decreases when the particle diameter increases, becoming stable around a diameter of 250 microm. PMID:19094396

  7. A search for the near-infrared extragalactic background light

    NASA Astrophysics Data System (ADS)

    Matsumoto, T.; Akiba, M.; Murakami, H.

    1988-09-01

    The diffuse celestial light at 1 - 5 μm was observed over a large portion of the sky including the Galactic pole with a rocket-borne infrared telescope cooled by solid nitrogen. After subtracting the foreground components, there still remains an appreciable amount of isotropic diffuse radiation with complex spectral feature. A part of this isotropic radiation may be contaminated by the environmental emission due to rocket engine exhaust; however, the 2.2 μm data is free from contamination and possibly attributed to an extragalactic origin.

  8. Optical diffuse reflectance accessory for measurements of skin tissue by near-infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Marbach, R.; Heise, H. M.

    1995-02-01

    An optimized accessory for measuring the diffuse reflectance spectra of human skin tissue in the near-infrared spectral range is presented. The device includes an on-axis ellipsoidal collecting mirror with efficient illumination optics for small sampling areas of bulky body specimens. The optical design is supported by the results of a Monte Carlo simulation study of the reflectance characteristics of skin tissue. Because the results evolved from efforts to measure blood glucose noninvasively, the main emphasis is placed on the long-wavelength near-infrared range where sufficient penetration depth for radiation into tissue is still available. The accessory is applied for in vivo diffuse reflectance measurements.

  9. The Effect of Incident Light Polarization on Vegetation Bidirectional Reflectance Factor

    NASA Technical Reports Server (NTRS)

    Georgiev, Georgi T.; Thome, Kurt; Ranson, Kurtis J.; King, Michael D.; Butler, James J.

    2010-01-01

    The Laboratory-based Bidirectional Reflectance Factor (BRF) polarization study of vegetation is presented in this paper. The BRF was measured using a short-arc Xenon lamp/monochromator assembly producing an incoherent, tunable light source with a well-defined spectral bandpass at visible and near-infrared wavelengths of interest at 470 nm and 870 nm and coherent light source at 1.656 microns. All vegetation samples were measured using P and S linearly polarized incident light over a range of incident and scatter angles. By comparing these results, we quantitatively examine how the BRF of the samples depends on the polarization of the incident light. The differences are significant, depend strongly on the incident and scatter angles, and can be as high as 120% at 67 deg incident and 470nm. The global nature of Earth's processes requires consistent long-term calibration of all instruments involved in data retrieval. The BRF defines the reflection characteristics of Earth surface. It provides the reflectance of a target in a specific direction as a function of illumination and viewing geometry. The BRF is a function of wavelength and reflects the structural and optical properties of the surface. Various space and airborne radiometric and imaging remote sensing instruments are used in the remote sensing characterization of vegetation canopies and soils, oceans, or especially large pollution sources. The satellite data is validated through comparison with airborne, ground-based and laboratory-based data in an effort to fully understand the vegetation canopy reflectance, The Sun's light is assumed to be unpolarized at the top of the atmosphere; however it becomes polarized to some degree due to atmospheric effects by the time it reaches the vegetation canopy. Although there are numerous atmospheric correction models, laboratory data is needed for model verification and improvement.

  10. Polarized infrared emissivity of one-dimensional Gaussian sea surfaces with surface reflections.

    PubMed

    Li, Hongkun; Pinel, Nicolas; Bourlier, Christophe

    2011-08-10

    Surface reflection is an important phenomenon that must be taken into account when studying sea surface infrared emissivity, especially at large observation angles. This paper models analytically the polarized infrared emissivity of one-dimensional sea surfaces with shadowing effect and one surface reflection, by assuming a Gaussian surface slope distribution. A Monte Carlo ray-tracing method is employed as a reference. It is shown that the present model agrees well with the reference method. The emissivity calculated by the present model is then compared with measurements. The comparisons show that agreements are greatly improved by taking one surface reflection into account. The Monte Carlo ray-tracing results of sea surface infrared emissivity with two and three reflections are also determined. Their contributions are shown to be negligible.

  11. The spatial distribution of infrared radiation from visible reflection nebulae

    NASA Technical Reports Server (NTRS)

    Luan, Ling; Werner, Michael W.; Dwek, Eli; Sellgren, Kris

    1989-01-01

    The emission at IRAS 12 and 25 micron bands of reflection nebulae is far in excess of that expected from the longer wavelength equilibrium thermal emission. The excess emission in the IRAS 12 micron band is a general phenomenon, seen in various components of interstellar medium such as IR cirrus clouds, H II regions, atomic and molecular clouds, and also normal spiral galaxies. This excess emission has been attributed to UV excited fluorescence in polycyclic aromatic hydrocarbon (PAH) molecules or to the effect of temperature fluctuations in very small grains. Results are presented of studies of IRAS data on reflection nebulae selected from the van den Bergh reflection nebulae sample. Detailed scans of flux ratio and color temperature across the nebulae were obtained in order to study the spatial distribution of IR emission. A model was used to predict the spatial distribution of IR emission from dust grains illuminated by a B type star. The model was also used to explore the excitation of the IRAS 12 micron band emission as a function of stellar temperature. The model predictions are in good agreement with the analysis of reflection nebulae, illuminated by stars with stellar temperature ranging from 21,000 down to 3,000 K.

  12. Qualitative flow visualization using colored lights and reflective flakes

    NASA Astrophysics Data System (ADS)

    Thoroddsen, S. T.; Bauer, J. M.

    1999-07-01

    We present a novel flow-visualization technique utilizing reflective flakes in combination with color illumination. Three differently colored columated light beams are used to illuminate the flow, each color being directed from a separate direction. In this way, the color of the light reflected from the flakes gives an indication of the local flake orientation. The flake orientation in complex three-dimensional (3-D) flow is in general a complicated function of the local velocity gradient tensor, but can be calculated if the underlying velocity field is known. This has recently been demonstrated by Gauthier et al. [Phys. Fluids. 10, 2147 (1998)] using monochome light. In complex flow fields the distribution of flakes may, however, be rearranged by the motion, thus making the local intensity of reflection depend on both orientation and flake concentration. The color is, however, immune to the local number density of flakes inside the flow, making quantitative information possible. This technique is demonstrated by visualizing the finer details of vortices in a Taylor-Couette device.

  13. Modeling of light absorption in tissue during infrared neural stimulation.

    PubMed

    Thompson, Alexander C; Wade, Scott A; Brown, William G A; Stoddart, Paul R

    2012-07-01

    A Monte Carlo model has been developed to simulate light transport and absorption in neural tissue during infrared neural stimulation (INS). A range of fiber core sizes and numerical apertures are compared illustrating the advantages of using simulations when designing a light delivery system. A range of wavelengths, commonly used for INS, are also compared for stimulation of nerves in the cochlea, in terms of both the energy absorbed and the change in temperature due to a laser pulse. Modeling suggests that a fiber with core diameter of 200 μm and NA=0.22 is optimal for optical stimulation in the geometry used and that temperature rises in the spiral ganglion neurons are as low as 0.1°C. The results show a need for more careful experimentation to allow different proposed mechanisms of INS to be distinguished.

  14. Infrared sensitive liquid crystal light valve with semiconductor substrate.

    PubMed

    Shcherbin, Konstantin; Gvozdovskyy, Igor; Evans, Dean R

    2016-02-10

    A liquid crystal light valve (LCLV) is an optically controlled spatial light modulator that allows recording of dynamic holograms. Almost all known LCLVs operate in the visible range of the spectrum. In the present work we demonstrate a LCLV operating in the infrared. The interaction of signal and pump waves is studied for different applied voltages, grating spacings, and intensities of the recording beams. A fourfold amplification of the weak signal beam is achieved. The amplitude of the refractive index modulation Δn=0.007 and nonlinear coupling constant n₂=-1  cm²/W are estimated from the experimental results. External phase modulation of one of the recording beams is used for a further transient increase of the signal beam gain. PMID:26906379

  15. Measurement of leaf relative water content by infrared reflectance

    NASA Technical Reports Server (NTRS)

    Hunt, E. Raymond, Jr.; Rock, Barrett N.; Nobel, Park S.

    1987-01-01

    From basic considerations and Beer's law, a leaf water content index incorporating reflectances of wavelengths from 0.76 to 0.90 microns and from 1.55 to 1.75 microns was developed that relates leaf reflectance to leaf relative water content. For the leaf succulent, Agave deserti, the leaf water content index was not significantly different from the relative water content for either individual leaves or an entire plant. Also, the relative water contents of intact plants of Encelia farinosa and Hilaria rigida in the field were estimated by the leaf water content index; variations in the proportion of living to dead leaf area could cause large errors in the estimate of relative water content. Thus, the leaf water content index may be able to estimate average relative water content of canopies when TM4 and TM5 are measured at a known relative water content and fraction of dead leaf material.

  16. Diffuse reflectance infrared Fourier-Transform spectra of selected organic compounds

    SciTech Connect

    Harmon, S.H.; Caton, J.E.

    1982-05-01

    Diffuse reflectance infrared spectra of a variety of different organic compounds have been determined. Profiles of the spectra along with the location and relative intensity of the principal bands have been included for each compound studied. In addition both diffuse reflectance and transmittance infrared spectra were obtained for the same samples, and the spectral results were compared. Although some minor variations are observed between a diffuse reflectance spectrum and the corresponding transmittance spectrum, the diffuse reflectance is quite useful and may be a superior technique for the study of many samples because it possesses an inherently higher signal-to-noise response, requires less sample preparation and allows a very wide range of samples (solids, liquids of low volatility, neat sample, or sample diluted in a reflecting medium) to be studied under very similar conditions.

  17. Simulating Scintillator Light Collection Using Measured Optical Reflectance

    SciTech Connect

    Janecek, Martin; Moses, William

    2010-01-28

    To accurately predict the light collection from a scintillating crystal through Monte Carlo simulations, it is crucial to know the angular distribution from the surface reflectance. Current Monte Carlo codes allow the user to set the optical reflectance to a linear combination of backscatter spike, specular spike, specular lobe, and Lambertian reflections. However, not all light distributions can be expressed in this way. In addition, the user seldom has the detailed knowledge about the surfaces that is required for accurate modeling. We have previously measured the angular distributions within BGO crystals and now incorporate these data as look-up-tables (LUTs) into modified Geant4 and GATE Monte Carlo codes. The modified codes allow the user to specify the surface treatment (ground, etched, or polished), the attached reflector (Lumirror(R), Teflon(R), ESR film, Tyvek(R), or TiO paint), and the bonding type (air-coupled or glued). Each LUT consists of measured angular distributions with 4o by 5o resolution in theta and phi, respectively, for incidence angles from 0? to 90? degrees, in 1o-steps. We compared the new codes to the original codes by running simulations with a 3 x 10 x 30 mm3 BGO crystal coupled to a PMT. The simulations were then compared to measurements. Light output was measured by counting the photons detected by the PMT with the 3 x 10, 3 x 30, or 10 x 30 mm2 side coupled to the PMT, respectively. Our new code shows better agreement with the measured data than the current Geant4 code. The new code can also simulate reflector materials that are not pure specular or Lambertian reflectors, as was previously required. Our code is also more user friendly, as no detailed knowledge about the surfaces or light distributions is required from the user.

  18. Light shift from ultraviolet to near infrared light: Cerenkov luminescence with gold nanocluster - near infrared (AuNc-NIR) conjugates

    NASA Astrophysics Data System (ADS)

    Yoo, Su Woong; Mun, Hyoyoung; Oh, Gyungseok; Ryu, Youngjae; Kim, Min-Gon; Chung, Euiheon

    2015-03-01

    Cerenkov luminescence (CL) is generated when a charged particle moves faster than the speed of light in dielectric media. Recently CL imaging becomes an emerging technique with the use of radioisotopes. However, due to relatively weak blue light production and massive tissue attenuation, CL has not been applied widely. Therefore, we attempted to shift the CL emission to more near infrared (NIR) spectrum for better tissue penetration by using Cerenkov Radiation Energy Transfer (CRET). Gold nanoclusters were conjugated with NIR dye molecules (AuNc-IR820 and AuNc-ICG) to be activated with ultraviolet light. We found optimal conjugate concentrations of AuNc-NIR conjugates by spectroscopy system to generate maximal photon emission. When exposed by ultraviolet light, the emission of NIR light from the conjugates were verified. In quantitative analysis, AuNc-NIR conjugates emit brighter light signal than pure AuNc. This result implies that NIR fluorescent dyes (both IR820 and ICG) can be excited by the emission from AuNc. Following the above baseline experiment, we mixed F-18 fluorodeoxyglucose (F-18 FDG) radioisotope to the AuNc- NIR conjugates, to confirm NIR emission induced from Cerenkov radiation. Long pass filter was used to block Cerenkov luminescence and to collect the emission from AuNc-NIR conjugates. Instead of one long exposure imaging with CCD, we used multiple frame scheme to eliminate gamma radiation strike in each frame prior to combination. In summary, we obtained NIR emission light from AuNc-NIR conjugated dyes that is induced from CL. We plan to perform in vivo small animal imaging with these conjugates to assess better tissue penetration.

  19. Three-dimensional light trap for reflective particles

    DOEpatents

    Neal, D.R.

    1999-08-17

    A system is disclosed for containing either a reflective particle or a particle having an index of refraction lower than that of the surrounding media in a three-dimensional light cage. A light beam from a single source illuminates an optics system and generates a set of at least three discrete focused beams that emanate from a single exit aperture and focus on to a focal plane located close to the particle. The set of focal spots defines a ring that surrounds the particle. The set of focused beams creates a ``light cage`` and circumscribes a zone of no light within which the particle lies. The surrounding beams apply constraining forces (created by radiation pressure) to the particle, thereby containing it in a three-dimensional force field trap. A diffractive element, such as an aperture multiplexed lens, or either a Dammann grating or phase element in combination with a focusing lens, may be used to generate the beams. A zoom lens may be used to adjust the size of the light cage, permitting particles of various sizes to be captured and contained. 10 figs.

  20. Three-dimensional light trap for reflective particles

    DOEpatents

    Neal, Daniel R.

    1999-01-01

    A system for containing either a reflective particle or a particle having an index of refraction lower than that of the surrounding media in a three-dimensional light cage. A light beam from a single source illuminates an optics system and generates a set of at least three discrete focussed beams that emanate from a single exit aperture and focus on to a focal plane located close to the particle. The set of focal spots defines a ring that surrounds the particle. The set of focussed beams creates a "light cage" and circumscribes a zone of no light within which the particle lies. The surrounding beams apply constraining forces (created by radiation pressure) to the particle, thereby containing it in a three-dimensional force field trap. A diffractive element, such as an aperture multiplexed lens, or either a Dammann grating or phase element in combination with a focusing lens, may be used to generate the beams. A zoom lens may be used to adjust the size of the light cage, permitting particles of various sizes to be captured and contained.

  1. Detecting Phycocynanin-Pigmented Microbes in Reflected Light

    NASA Technical Reports Server (NTRS)

    Vincent, Robert K.

    2008-01-01

    A recently invented method of measuring concentrations of phycocynanin-pigmented algae and bacteria in water is based on measurement of the spectrum of reflected sunlight. When present in sufficiently high concentrations, phycocynanin-pigmented microorganisms can be hazardous to the health of humans who use, and of animals that depend on, an affected body of water. The present method is intended to satisfy a need for a rapid, convenient means of detecting hazardous concentrations of phycocynanin-pigmented microorganisms. Rapid detection will speed up the issuance of public health warnings and performance of corrective actions. The method involves the measurement of light reflected from a body of water in at least two, but preferably five wavelength bands. In one version of the method, the five wavelength bands are bands 1, 3, 4, 5, and 7 of the Thematic Mapper (TM) multispectral imaging instrument aboard the Landsat-7 satellite (see table). In principle, other wavelength bands indicative of phycocynanin could be used alternatively or in addition to these five. Moreover, although the method was originally intended specifically for processing Landsat- 7 TM data, it is equally applicable to processing of data from other satellite-borne instruments or from airborne, hand-held, buoy-mounted, tower-mounted, or otherwise mounted instruments that measure radiances of light reflected from water in the wavelength bands of interest.

  2. Infrared reflection spectra in contactless nondestructive measurements of the electron density and mobility in indium phosphide

    SciTech Connect

    Il'in, M.A.; Karasev, P.Yu.; Denisova, N.A.; Rezvov, A.V.; Tyurina, S.V.

    1988-07-01

    On the basis of numerical calculations and experimental studies we analyze the possibilities of measuring the electrophysical parameters of indium phosphide by means of infrared reflection spectra at wavelengths ranging from 5 to 200 /mu/m. We demonstrate that contactless nondestructive measurements of the electron density in the range 10/sup 16/-10/sup 20/ cm/sup /minus/3/ can be made with a relative error not exceeding 15%, and of mobility with a relative error not exceeding 25%. A nomogram method is presented for rapid conversion of data form infrared reflection spectra into the parameters being measured.

  3. [Application of near-infrared diffuse reflectance spectroscopy to the detection and identification of transgenic corn].

    PubMed

    Rui, Yu-kui; Luo, Yun-bo; Huang, Kun-lun; Wang, Wei-min; Zhang, Lu-da

    2005-10-01

    With the rapid development of the GMO, more and more GMO food has been pouring into the market. Much attention has been paid to GMO labeling under the controversy of GMO safety. Transgenic corns and their parents were scanned by continuous wave of near infrared diffuse reflectance spectroscopy range of 12000-4000 cm(-1); the resolution was 4 cm(-1); scanning was carried out for 64 times; BP algorithm was applied for data processing. The GMO food was easily resolved. Near-infrared diffuse reflectance spectroscopy is unpolluted and inexpensive compared with PCR and ELISA, so it is a very promising detection method for GMO food.

  4. Exact simulation of polarized light reflectance by particle deposits

    NASA Astrophysics Data System (ADS)

    Ramezan Pour, B.; Mackowski, D. W.

    2015-12-01

    The use of polarimetric light reflection measurements as a means of identifying the physical and chemical characteristics of particulate materials obviously relies on an accurate model of predicting the effects of particle size, shape, concentration, and refractive index on polarized reflection. The research examines two methods for prediction of reflection from plane parallel layers of wavelength—sized particles. The first method is based on an exact superposition solution to Maxwell's time harmonic wave equations for a deposit of spherical particles that are exposed to a plane incident wave. We use a FORTRAN-90 implementation of this solution (the Multiple Sphere T Matrix (MSTM) code), coupled with parallel computational platforms, to directly simulate the reflection from particle layers. The second method examined is based upon the vector radiative transport equation (RTE). Mie theory is used in our RTE model to predict the extinction coefficient, albedo, and scattering phase function of the particles, and the solution of the RTE is obtained from adding—doubling method applied to a plane—parallel configuration. Our results show that the MSTM and RTE predictions of the Mueller matrix elements converge when particle volume fraction in the particle layer decreases below around five percent. At higher volume fractions the RTE can yield results that, depending on the particle size and refractive index, significantly depart from the exact predictions. The particle regimes which lead to dependent scattering effects, and the application of methods to correct the vector RTE for particle interaction, will be discussed.

  5. Reflectives: Phosphors and lasers - shedding light on rare earths

    SciTech Connect

    Tonneson, L.C.; Fox, G.J.

    1996-04-01

    The first powder electroluminescent phosphor was introduced in 1936. Today, phosphors, particularly those made of high-purity rare earths, have found their way into a variety of products: industrial, commercial, and consumer, alike. The fluorescent lamp industry which remains the leading market for the use of high-purity rare earths, lit the way for the future of rare earths in the optical, x-ray, and display screen applications. Light combined with rare earth materials is also a successful recipe for reflectivity needed in filtering applications such as optics, lasers, and conductors. This article discusses the applications and markets for phosphors and rare earths.

  6. POLARIZED LIGHT REFLECTED AND TRANSMITTED BY THICK RAYLEIGH SCATTERING ATMOSPHERES

    SciTech Connect

    Natraj, Vijay; Hovenier, J. W.

    2012-03-20

    Accurate values for the intensity and polarization of light reflected and transmitted by optically thick Rayleigh scattering atmospheres with a Lambert surface underneath are presented. A recently reported new method for solving integral equations describing Chandrasekhar's X- and Y-functions is used. The results have been validated using various tests and techniques, including the doubling-adding method, and are accurate to within one unit in the eighth decimal place. Tables are stored electronically and expected to be useful as benchmark results for the (exo)planetary science and astrophysics communities. Asymptotic expressions to obtain Stokes parameters for a thick layer from those of a semi-infinite atmosphere are also provided.

  7. In-field stray light due to surface scattering effects in infrared imaging systems

    NASA Astrophysics Data System (ADS)

    Sun, Ke; Jiang, Hou-man; Cheng, Xiang-ai

    2011-08-01

    In-field stray light caused by surface scattering is a serious problem in many infrared imaging systems. Light that scattered from lenses in infrared imaging system produces a halo of stray light within the field of view and often degrades the performance of an optical system especially irradiated by intensive light such as laser. The experiments are performed by using infrared thermal imaging system, irradiated by CW DF infrared laser. The relationship between the diameter of saturated area on the detector and the incident laser irradiance is obtained, which can be well explained by the point spread function (PSF) of the optics including both diffraction and scattering components.

  8. Plasmonic light harvesting for multicolor infrared thermal detection.

    PubMed

    Mao, Feilong; Xie, Jinjin; Xiao, Shiyi; Komiyama, Susumu; Lu, Wei; Zhou, Lei; An, Zhenghua

    2013-01-14

    Here we combined experiments and theory to study the optical properties of a plasmonic cavity consisting of a perforated metal film and a flat metal sheet separated by a semiconductor spacer. Three different types of optical modes are clearly identified-the propagating and localized surface plasmons on the perforated metal film and the Fabry-Perot modes inside the cavity. Interactions among them lead to a series of hybridized eigenmodes exhibiting excellent spectral tunability and spatially distinct field distributions, making the system particularly suitable for multicolor infrared light detections. As an example, we design a two-color detector protocol with calculated photon absorption efficiencies enhanced by more than 20 times at both colors, reaching ~42.8% at f1 = 20.0THz (15μm in wavelength) and ~46.2% at f2 = 29.5THz (~10.2μm) for a 1μm total thickness of sandwiched quantum wells.

  9. Non-invasive neuroimaging using near-infrared light

    NASA Technical Reports Server (NTRS)

    Strangman, Gary; Boas, David A.; Sutton, Jeffrey P.

    2002-01-01

    This article reviews diffuse optical brain imaging, a technique that employs near-infrared light to non-invasively probe the brain for changes in parameters relating to brain function. We describe the general methodology, including types of measurements and instrumentation (including the tradeoffs inherent in the various instrument components), and the basic theory required to interpret the recorded data. A brief review of diffuse optical applications is included, with an emphasis on research that has been done with psychiatric populations. Finally, we discuss some practical issues and limitations that are relevant when conducting diffuse optical experiments. We find that, while diffuse optics can provide substantial advantages to the psychiatric researcher relative to the alternative brain imaging methods, the method remains substantially underutilized in this field.

  10. Particle Shape Characterization of Lunar Regolith using Reflected Light Microscopy

    NASA Astrophysics Data System (ADS)

    McCarty, C. B.; Garcia, G. C.; Rickman, D.

    2014-12-01

    Automated identification of particles in lunar thin sections is necessary for practical measurement of particle shape, void characterization, and quantitative characterization of sediment fabric. This may be done using image analysis, but several aspects of the lunar regolith make such automations difficult. For example, many of the particles are shattered; others are aggregates of smaller particles. Sieve sizes of the particles span 5 orders of magnitude. The physical thickness of a thin section, at a nominal 30 microns, is large compared to the size of many of the particles. Image acquisition modes, such as SEM and reflected light, while superior to transmitted light, still have significant ambiguity as to the volume being sampled. It is also desirable to have a technique that is inexpensive, not resource intensive, and analytically robust. To this end, we have developed an image acquisition and processing protocol that identifies and delineates resolvable particles on the front surface of a lunar thin section using a petrographic microscope in reflected light. For a polished thin section, a grid is defined covering the entire thin section. The grid defines discrete images taken with 20% overlap, minimizing the number of particles that intersect image boundaries. In reflected light mode, two images are acquired at each grid location, with a closed aperture diaphragm. One image, A, is focused precisely on the front surface of the thin section. The second image, B, is made after the stage is brought toward the objective lens just slightly. A bright fringe line, analogous to a Becke line, appears inside all transparent particles at the front surface of the section in the second image. The added light in the bright line corresponds to a deficit around the particles. Particle identification is done using ImageJ and uses multiple steps. A hybrid 5x5 median filter is used to make images Af and Bf. This primarily removes very small particles just below the front surface

  11. Reflective liquid crystal light valve with hybrid field effect mode

    NASA Technical Reports Server (NTRS)

    Boswell, Donald D. (Inventor); Grinberg, Jan (Inventor); Jacobson, Alexander D. (Inventor); Myer, Gary D. (Inventor)

    1977-01-01

    There is disclosed a high performance reflective mode liquid crystal light valve suitable for general image processing and projection and particularly suited for application to real-time coherent optical data processing. A preferred example of the device uses a CdS photoconductor, a CdTe light absorbing layer, a dielectric mirror, and a liquid crystal layer sandwiched between indium-tin-oxide transparent electrodes deposited on optical quality glass flats. The non-coherent light image is directed onto the photoconductor; this reduces the impedance of the photoconductor, thereby switching the AC voltage that is impressed across the electrodes onto the liquid crystal to activate the device. The liquid crystal is operated in a hybrid field effect mode. It utilizes the twisted nematic effect to create a dark off-state (voltage off the liquid crystal) and the optical birefringence effect to create the bright on-state. The liquid crystal thus modulates the polarization of the coherent read-out or projection light responsively to the non-coherent image. An analyzer is used to create an intensity modulated output beam.

  12. Near Infrared 45°/0° Reflectance Factor of Pressed Polytetrafluoroethylene (PTFE) Powder

    PubMed Central

    Nadal, Maria E.; Barnes, P. Yvonne

    1999-01-01

    Pressed polytetrafluoroethylene (PTFE) powder is commonly used as a reflectance standard for bidirectional and hemispherical geometries. The wavelength dependence of the reflectance factor of PTFE is presented for the near-infrared spectral region (800 nm to 1600 nm) for the 45°/0° geometry, as well as in the visible spectral region (380 nm to 800 nm) for comparison with previously published results.

  13. Thermal Infrared Reflective Metal Oxide Sol-Gel Coatings for Carbon Fiber Reinforced Composite Structures

    NASA Astrophysics Data System (ADS)

    Richard, Brandon Demar

    Recent trends in composite research include the development of structural materials with multiple functionalities. In new studies, novel materials are being designed, developed, modified, and implemented into composite designs. Typically, an increase in functionality requires additional material phases within one system. The presence of excessive phases can result in deterioration of individual or overall properties. True multi-functional materials must maintain all properties at or above the minimum operating limit. In this project, samples of antimony and cobalt-doped tin oxide (ATO(Co2O 3)) sol-gel solutions are used to coat carbon fibers and are heat treated at a temperature range of 200 - 500 °C. Results from this research are used to model the implementation of sol-gel coatings into carbon fiber reinforced multifunctional composite systems. This research presents a novel thermo-responsive sol-gel/ (dopant) combination and evaluation of the actuating responses (reflectivity and surface heat dissipation) due to various heat treatment temperatures. While ATO is a well-known transparent conductive material, the implementation of ATO on carbon fibers for infrared thermal reflectivity has not been examined. These coatings serve as actuators capable of reflecting thermal infrared radiation in the near infrared wavelengths of 0.7-1.2 μm. By altering the level of Co2O3 and heat treatment temperatures, optimal optical properties are obtained. While scanning electron microscopy (SEM) is used for imaging, electron diffraction spectroscopy (EDS) is used to verify the compounds present in the coatings. Fourier transform infrared (FT-IR) spectroscopy was performed to analyze the chemical bonds and reflectivity in the infrared spectra after the heat treatments. Total reflection and angle-dependent reflectivity measurements were performed on the coatings in the wavelengths of 0.7-2 μm. Laser induced damage threshold testing was done to investigate the dielectric breakdown

  14. [DWT-iPLS applied in the infrared diffuse reflection spectrum of hydrocarbon source rocks].

    PubMed

    Song, Ning; Xu, Xiao-xuan; Wu, Zhong-chen; Zhang, Cun-zhou; Wang, Bin

    2008-08-01

    Infrared spectroscopy is useful to monitor the quality of products on-line, or to quality multivariate properties simultaneously. The IR spectrometer satisfies the requirements of users who want to have quantitative product information in real-time because the instrument provides the information promptly and easily. However, Samples that are measured using diffuse reflectance often exhibit significant differences in the spectra due to the non-homogeneous distribution of the particles. In fact, multiple spectral measurements of the same sample can look completely different. In many cases, the scattering can be an overpowering contributor to the spectrum, sometimes accounting for most of the variance in the data. Although the degree of scattering is dependent on the wavelength of the light that is used and the particle size and refractive index of the sample, the scattering is not uniform throughout the spectrum. Typically, this appears as a baseline shift, tilt and sometimes curvature, where the degree of influence is more pronounced at the longer-wavelength end of the spectrum. The diffuse reflection spectrum is unsatisfactory and the calibration may provide unsatisfactory prediction results. So we must use some methods to remove the effects of the scattering for multivariate calibration of IR spectral signals. Discrete wavelet transform (DWT) is a good method to remove the effects of the scattering for multivariate calibration of IR spectral signals. By using DWT on individual signals as a preprocessing method in regression modeling on IR spectra, good compression is achieved with almost no loss of information, the low-frequency varying background and the high-frequency noise be removed simultaneously. In this report, we use the iPLS method to establish the calibration models of hydrocarbon source rocks. iPLS is a new regression method and the authors can get better results by using DTW- iPLS.

  15. Comparison of visible and near infrared reflectance spectroscopy on fat to authenticate dietary history of lambs.

    PubMed

    Huang, Y; Andueza, D; de Oliveira, L; Zawadzki, F; Prache, S

    2015-11-01

    Since consumers are showing increased interest in the origin and method of production of their food, it is important to be able to authenticate dietary history of animals by rapid and robust methods used in the ruminant products. Promising breakthroughs have been made in the use of spectroscopic methods on fat to discriminate pasture-fed and concentrate-fed lambs. However, questions remained on their discriminatory ability in more complex feeding conditions, such as concentrate-finishing after pasture-feeding. We compared the ability of visible reflectance spectroscopy (Vis RS, wavelength range: 400 to 700 nm) with that of visible-near-infrared reflectance spectroscopy (Vis-NIR RS, wavelength range: 400 to 2500 nm) to differentiate between carcasses of lambs reared with three feeding regimes, using partial least square discriminant analysis (PLS-DA) as a classification method. The sample set comprised perirenal fat of Romane male lambs fattened at pasture (P, n = 69), stall-fattened indoors on commercial concentrate and straw (S, n = 55) and finished indoors with concentrate and straw for 28 days after pasture-feeding (PS, n = 65). The overall correct classification rate was better for Vis-NIR RS than for Vis RS (99.0% v. 95.1%, P < 0.05). Vis-NIR RS allowed a correct classification rate of 98.6%, 100.0% and 98.5% for P, S and PS lambs, respectively, whereas Vis RS allowed a correct classification rate of 98.6%, 94.5% and 92.3% for P, S and PS lambs, respectively. This study suggests the likely implication of molecules absorbing light in the non-visible part of the Vis-NIR spectra (possibly fatty acids), together with carotenoid and haem pigments, in the discrimination of the three feeding regimes.

  16. Infrared light management in high-efficiency silicon heterojunction and rear-passivated solar cells

    NASA Astrophysics Data System (ADS)

    Holman, Zachary C.; Filipič, Miha; Descoeudres, Antoine; De Wolf, Stefaan; Smole, Franc; Topič, Marko; Ballif, Christophe

    2013-01-01

    Silicon heterojunction solar cells have record-high open-circuit voltages but suffer from reduced short-circuit currents due in large part to parasitic absorption in the amorphous silicon, transparent conductive oxide (TCO), and metal layers. We previously identified and quantified visible and ultraviolet parasitic absorption in heterojunctions; here, we extend the analysis to infrared light in heterojunction solar cells with efficiencies exceeding 20%. An extensive experimental investigation of the TCO layers indicates that the rear layer serves as a crucial electrical contact between amorphous silicon and the metal reflector. If very transparent and at least 150 nm thick, the rear TCO layer also maximizes infrared response. An optical model that combines a ray-tracing algorithm and a thin-film simulator reveals why: parallel-polarized light arriving at the rear surface at oblique incidence excites surface plasmons in the metal reflector, and this parasitic absorption in the metal can exceed the absorption in the TCO layer itself. Thick TCO layers—or dielectric layers, in rear-passivated diffused-junction silicon solar cells—reduce the penetration of the evanescent waves to the metal, thereby increasing internal reflectance at the rear surface. With an optimized rear TCO layer, the front TCO dominates the infrared losses in heterojunction solar cells. As its thickness and carrier density are constrained by anti-reflection and lateral conduction requirements, the front TCO can be improved only by increasing its electron mobility. Cell results attest to the power of TCO optimization: With a high-mobility front TCO and a 150-nm-thick, highly transparent rear ITO layer, we recently reported a 4-cm2 silicon heterojunction solar cell with an active-area short-circuit current density of nearly 39 mA/cm2 and a certified efficiency of over 22%.

  17. Low-resolution mid-infrared reflection analysis for discernment of contaminants in seed cotton

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Contaminants often decrease cotton quality, which subsequently decrease cotton profitability. In this research, a low-resolution mid-infrared reflection instrument was designed and constructed by using only four different wavelengths to accomplish good separation of cotton samples from 14 contaminan...

  18. Near-infrared light-responsive nanomaterials in cancer therapeutics.

    PubMed

    Shanmugam, Vijayakumar; Selvakumar, S; Yeh, Chen-Sheng

    2014-09-01

    Noninvasive techniques, such as breath tests (urea breath test), blood pressure measurements using a sphygmomanometer and electrocardiography, were employed by a physician to perform classical diagnosis. The use of state-of-the-art noninvasive therapies at the organ level in modern medicine has gradually become possible. However, cancer treatment demands spatially and temporally controlled noninvasive therapy at the cell level because nonspecific toxicity often causes complicated side effects. To increase survival in cancer patients further, combination therapy and combination drugs are explored which demand high specificity to avoid combined-drug side effects. We believe that high specificity could be obtained by implementing near-infrared (NIR) light-assisted nanoparticles in photothermal therapy, chemotherapy, and photodynamic therapy. To refine this therapy and subsequently achieve high efficiency, novel nanomaterials have been designed and modified either to enhance the uptake and drug delivery to the cancer site, or control treatment to administer therapy efficiently. These modifications and developments have been demonstrated to achieve spatial and temporal control when conducting an in vivo xenograft, because the NIR light penetrated effectively the biological tissue. The nanoplatforms discussed in this review are grouped under the following subheadings: Au nanorods (NRs), Au nanoshells, other Au-related nanomaterials, graphene oxide, upconversion nanoparticles, and other related materials (including materials such as CuS, Fe3O4-related systems, and carbon nanotubes (CNTs)).

  19. Simulation and measurement of transcranial near infrared light penetration

    NASA Astrophysics Data System (ADS)

    Yue, Lan; Monge, Manuel; Ozgur, Mehmet H.; Murphy, Kevin; Louie, Stan; Miller, Carol A.; Emami, Azita; Humayun, Mark S.

    2015-03-01

    We are studying the transmission of LED array-emitted near-infrared (NIR) light through human tissues. Herein, we simulated and measured transcranial NIR penetration in highly scattering human head tissues. Using finite element analysis, we simulated photon diffusion in a multilayered 3D human head model that consists of scalp, skull, cerebral spinal fluid, gray matter and white matter. The optical properties of each layer, namely scattering and absorption coefficient, correspond to the 850 nm NIR light. The geometry of the model is minimally modified from the IEEE standard and the multiple LED emitters in an array were evenly distributed on the scalp. Our results show that photon distribution produced by the array exhibits little variation at similar brain depth, suggesting that due to strong scattering effects of the tissues, discrete spatial arrangements of LED emitters in an array has the potential to create a quasi-radially symmetrical illumination field. Measurements on cadaveric human head tissues excised from occipital, parietal, frontal and temporal regions show that illumination with an 850 nm LED emitter rendered a photon flux that closely follows simulation results. In addition, prolonged illumination of LED emitted NIR showed minimal thermal effects on the brain.

  20. Infrared

    NASA Astrophysics Data System (ADS)

    Vollmer, M.

    2013-11-01

    techniques such as attenuated total reflectance [6]. The two final papers deal with what seem to be wholly different scientific fields [7, 8]. One paper describes SOFIA, an aeroplane-based astronomical observatory covering the whole IR range [7], while the other represents a small review of the quite new topic of terahertz physics at the upper end of the IR spectral range, from around 30 µm to 3 mm wavelength, and its many applications in science and industry [8]. Although artificially separated, all these fields use similar kinds of detectors, similar kinds of IR sources and similar technologies, while the instruments use the same physical principles. We are convinced that the field of infrared physics will develop over the next decade in the same dynamic way as during the last, and this special issue may serve as starting point for regular submissions on the topic. At any rate, it shines a light on this fascinating and many-faceted subject, which started more than 200 years ago. References [1] Mangold K, Shaw J A and Vollmer M 2013 The physics of near-infrared photography Eur. J. Phys. 34 S51-71 [2] Vollmer M and Möllmann K-P 2013 Characterization of IR cameras in student labs Eur. J. Phys. 34 S73-90 [3] Ibarra-Castanedo C, Tarpani J R and Maldague X P V 2013 Nondestructive testing with thermography Eur. J. Phys. 34 S91-109 [4] Shaw J A and Nugent P W 2013 Physics principles in radiometric infrared imaging of clouds in the atmosphere Eur. J. Phys. 34 S111-21 [5] Möllmann K-P and Vollmer M 2013 Fourier transform infrared spectroscopy in physics laboratory courses Eur. J. Phys. 34 S123-37 [6] Heise H M, Fritzsche J, Tkatsch H, Waag F, Karch K, Henze K, Delbeck S and Budde J 2013 Recent advances in mid- and near-infrared spectroscopy with applications for research and teaching, focusing on petrochemistry and biotechnology relevant products Eur. J. Phys. 34 S139-59 [7] Krabbe A, Mehlert D, Röser H-P and Scorza C 2013 SOFIA, an airborne observatory for infrared astronomy

  1. Improving the light quantification of near infrared (NIR) diffused light optical tomography with ultrasound localization

    NASA Astrophysics Data System (ADS)

    Ardeshirpour, Yasaman

    According to the statistics published by the American Cancer Society, currently breast cancer is the second most common cancer after skin cancer and the second cause of cancer death after lung cancer in the female population. Diffuse optical tomography (DOT) using near-infrared (NIR) light, guided by ultrasound localization, has shown great promise in distinguishing benign from malignant breast tumors and in assessing the response of breast cancer to chemotherapy. Our ultrasound-guided DOT system is based on reflection geometry, with patients scanned in supine position using a hand-held probe. For patients with chest-wall located at a depth shallower than 1 to 2cm, as in about 10% of our clinical cases, the semi-infinite imaging medium is not a valid assumption and the chest-wall effect needs to be considered in the imaging reconstruction procedure. In this dissertation, co-registered ultrasound images were used to model the breast-tissue and chest-wall as a two-layer medium. The effect of the chest wall on breast lesion reconstruction was systematically investigated. The performance of the two-layer model-based reconstruction, using the Finite Element Method, was evaluated by simulation, phantom experiments and clinical studies. The results show that the two-layer model can improve the accuracy of estimated background optical properties, the reconstructed absorption map and the total hemoglobin concentration of the lesion. For patients' data affected by chest wall, the perturbation, which is the difference between measurements obtained at lesion and normal reference sites, may include the information of background mismatch between these two sites. Because the imaging reconstruction is based on the perturbation approach, the effect of this mismatch between the optical properties at the two sites on reconstructed optical absorption was studied and a guideline for imaging procedure was developed to reduce these effects during data capturing. To reduce the artifacts

  2. Durable silver mirror with ultra-violet thru far infra-red reflection

    DOEpatents

    Wolfe, Jesse D.

    2010-11-23

    A durable highly reflective silver mirror characterized by high reflectance in a broad spectral range of about 300 nm in the UV to the far infrared (.about.10000 nm), as well as exceptional environmental durability. A high absorptivity metal underlayer is used which prevents the formation of a galvanic cell with a silver layer while increasing the reflectance of the silver layer. Environmentally durable overcoat layers are provided to enhance mechanical and chemical durability and protect the silver layer from corrosion and tarnishing, for use in a wide variety of surroundings or climates, including harsh or extreme environments.

  3. Infrared reflection-absorption spectroscopy of hyperfine layers on surfaces of semiconductors and dielectrics

    NASA Astrophysics Data System (ADS)

    Gruzinov, S. N.; Tolstoy, V. P.

    1988-02-01

    Infrared reflection-absorption spectroscopy of film son surfaces of transparent or weakly absorbing semiconductor and dielectric substrates is analyzed theoretically, the purpose being to establish the conditions for maximum sensitivity of this method. The absorption factor, namely the relative change of the reflection coefficient upon formation of a film on the substrate surface, is selected as the sensitivity criterion. The analysis is based on exact relations, one for a homogeneous isotopic absorbing film between substrate and ambient medium with plane-parallel boundaries and one for a reflecting layer with the possibility of multiple reflections taken into account. Calculations have been programmed on a computer for up to 60 nm thick SiO2 films on various substrates and infrared radiation within the 8 to 11 gmm waveband. The results indicate that the dependence of the absorption factor on the radiation wavelength and on the film thickness is different with the radiation s-polarized than with the radiation p-polarized. Calculations have also yielded the dispersion of optical constants characterizing a SiO2 film. According to these results, infrared spectroscopy is most sensitive to films on substrates with a small refractive index and when done with p-polarized radiation incident at exactly or approximately the Brewster angle for a determination of their presence and their composition respectively, also when no multiple reflections occur.

  4. Modeling thermal infrared (2-14 micrometer) reflectance spectra of frost and snow

    NASA Technical Reports Server (NTRS)

    Wald, Andrew E.

    1994-01-01

    Existing theories of radiative transfer in close-packed media assume that each particle scatters independently of its neighbors. For opaque particles, such as are common in the thermal infrared, this assumption is not valid, and these radiative transfer theories will not be accurate. A new method is proposed, called 'diffraction subtraction', which modifies the scattering cross section of close-packed large, opaque spheres to account for the effect of close packing on the diffraction cross section of a scattering particle. This method predicts the thermal infrared reflectance of coarse (greater than 50 micrometers radius), disaggregated granular snow. However, such coarse snow is typically old and metamorphosed, with adjacent grains welded together. The reflectance of such a welded block can be described as partly Fresnel in nature and cannot be predicted using Mie inputs to radiative transfer theory. Owing to the high absorption coefficient of ice in the thermal infrared, a rough surface reflectance model can be used to calculate reflectance from such a block. For very small (less than 50 micrometers), disaggregated particles, it is incorrect in principle to treat diffraction independently of reflection and refraction, and the theory fails. However, for particles larger than 50 micrometers, independent scattering is a valid assumption, and standard radiative transfer theory works.

  5. Long-wave infrared surface reflectance spectra retrieved from Telops Hyper-Cam imagery

    NASA Astrophysics Data System (ADS)

    Adler-Golden, S. M.; Conforti, P.; Gagnon, M.; Tremblay, P.; Chamberland, Martin

    2014-06-01

    Processing long-wave infrared (LWIR) hyperspectral imagery to surface emissivity or reflectance units via atmospheric compensation and temperature-emissivity separation (TES) affords the opportunity to remotely classify and identify solid materials with minimal interference from atmospheric effects. This paper describes an automated atmospheric compensation and TES method, called FLAASH®-IR (Fast Line-of-sight Atmospheric Analysis of Spectral Hypecubes-- Infrared), and its application to ground-to-ground imagery taken with the Telops Inc. Hyper-Cam interferometric hyperspectral imager. The results demonstrate that clean, quantitative surface spectra can be obtained, even with highly reflective (low emissivity) objects such as bare metal and in the presence of some illumination from the surroundings. In particular, the atmospheric compensation process suppresses the spectral features due to atmospheric water vapor and ozone, which are especially prominent in reflected sky radiance.

  6. [The research progress in determining lignocellulosic content by near infrared reflectance spectroscopy technology].

    PubMed

    Du, Juan; An, Dong; Xia, Tian; Huang, Yan-Hua; Li, Hong-Chao; Zhang, Yun-Wei

    2013-12-01

    Near infrared reflectance spectroscopy technology, as a new analytic method, can be used to determine the content of lignin, cellulose and hemi-cellulose which is faster, effective, easier to operate, and more accurate than the traditional wet chemical methods. Nowadays it has been widely used in measuring the composition of lignocelluloses in woody plant and herbaceous plant. The domestic and foreign research progress in determining the lignin, cellulose and hemi-cellulose content in woody plant ( wood and bamboo used as papermaking raw materials and wood served as potential biomass energy) and herbaceous plant (forage grass and energy grass) by near infrared reflectance spectroscopy technology is comprehensively summarized and the advances in method studies of measuring the composition of lignocelluloses by near infrared reflectance spectroscopy technology are summed up in three aspects, sample preparation, spectral data pretreatment and wavelength selection methods, and chemometric analysis respectively. Four outlooks are proposed combining the development statues of wood, forage grass and energy grass industry. First of all, the authors need to establish more feasible and applicable models for a variety of uses which can be used for more species from different areas, periods and anatomical parts. Secondly, comprehensive near infrared reflectance spectroscopy data base of grass products quality index needs to be improved to realize on-line quality and process control in grassproducts industry, which can guarantee the quality of the grass product. Thirdly, the near infrared reflectance spectroscopy quality index model of energy plant need to be built which can not only contribute to breed screening, but also improve the development of biomass industry. Besides, modeling approaches are required to be explored and perfected any further. Finally, the authors need to try our best to boost the advancement in the determination method of lignin, cellulose and hemi

  7. Light scattering by a rough surface of human skin. 1. The luminance factor of reflected light

    SciTech Connect

    Barun, V V; Ivanov, A P

    2013-08-31

    Based on the analytical solution of Maxwell's equations, we have studied the angular structure of the luminance factor of light reflected by the rough skin surface with large-scale relief elements, illuminated by a directed radiation beam incident at an arbitrary angle inside or outside the medium. The parameters of the surface inhomogeneities are typical of human skin. The calculated angular dependences are interpreted from the point of view of the angular distribution function of micro areas. The results obtained can be used for solving direct and inverse problems in biomedical optics, in particular for determining the depth of light penetration into a biological tissue, for studying the light action spectra on tissue chromophores under the in vivo conditions, for developing diagnostic methods of structural and biophysical parameters of a medium, and for optimising the mechanisms of interaction of light with biological tissues under their noninvasive irradiation through skin. (biomedical optics)

  8. Unpolarized emissivity with shadow and multiple reflections from random rough surfaces with the geometric optics approximation: application to Gaussian sea surfaces in the infrared band.

    PubMed

    Bourlier, Christophe

    2006-08-20

    The emissivity from a stationary random rough surface is derived by taking into account the multiple reflections and the shadowing effect. The model is applied to the ocean surface. The geometric optics approximation is assumed to be valid, which means that the rough surface is modeled as a collection of facets reflecting locally the light in the specular direction. In particular, the emissivity with zero, single, and double reflections are analytically calculated, and each contribution is studied numerically by considering a 1D sea surface observed in the near infrared band. The model is also compared with results computed from a Monte Carlo ray-tracing method. PMID:16892130

  9. Evidence for Reflected Light from the Most Eccentric Known Exoplanet

    NASA Astrophysics Data System (ADS)

    Kane, Stephen

    2015-12-01

    Planets in highly eccentric orbits form a class of objects not seen within our Solar System. The most extreme case known amongst these objects is the planet orbiting HD 20782, with an orbital period of 597 days and an eccentricity of 0.96. Here we present new data and analysis for this system as part of the Transit Ephemeris Refinement and Monitoring Survey (TERMS). New radial velocities acquired during periastron provide incredible accuracy for the planetary orbit and astrometric results that show the companion is indeed planetary in nature. We obtained MOST photometry during a predicted periastron passage that shows evidence of phase variations due to reflected light from the planet. The extreme nature of this planet presents an ideal case from which to test theories regarding the formation of eccentric orbits and the response of atmospheres to extreme changes in flux.

  10. Evaluation of thermal stability of indinavir sulphate using diffuse reflectance infrared spectroscopy.

    PubMed

    Singh, Parul; Premkumar, L; Mehrotra, Ranjana; Kandpal, H C; Bakhshi, A K

    2008-06-01

    Indinavir sulphate is a potent and specific protease inhibitor of human immunodeficiency virus (HIV). It is used for the treatment of acquired immune deficiency syndrome (AIDS). At elevated temperature the drug which otherwise remains crystalline undergoes a phase transition to an amorphous phase to form degradation products. In the present study, thermal stability of indinavir sulphate is evaluated using diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. Infrared spectra of the drug before and after the exposure to thermal radiation at different temperatures were acquired in the diffuse reflectance mode using a Fourier transform infrared (FTIR) spectrophotometer. The differential scanning calorimetry (DSC) and the X-ray diffraction (XRD) studies were used as complimentary techniques to adequately implement and assist the interpretation of the infrared spectroscopy results. The DRIFT spectra reveal that the drug remains stable up to 100 degrees C, degrades slightly at 125 degrees C and undergoes complete degradation at about 150 degrees C to produce degradation products. The degradation products can easily be characterized using the infrared spectra.

  11. Potential of remote visible and near-infrared spectral reflectance measurements for mapping thermal maturity variations

    SciTech Connect

    Rowan, L.C.; Pawlewicz, M.J.; Jones, O.D. )

    1989-09-01

    The visible and near-infrared (VNIR) spectral reflectance of rocks containing organic matter is related to thermal maturity because thermal alteration liberates hydrogen and forms highly absorbing carbon-rich polycondensed structures. To evaluate the usefulness of remote spectral reflectance measurements for mapping thermal maturity differences, Landsat Thematic Mapper (TM) images of the Eureka, Nevada, area were processed to produce a digital classification image maps that shows maturity in well-exposed, sparsely vegetated areas consisting of Chainman Shale. The relationship between spectral reflectance in TM bands and band ratios and maturity was confirmed through analysis of laboratory VNIR spectral reflectance and mean vitrinite reflectance (R{sub m}) measurements of 20 samples.

  12. Effects of Sample Preparation on the Infrared Reflectance Spectra of Powders

    SciTech Connect

    Brauer, Carolyn S.; Johnson, Timothy J.; Myers, Tanya L.; Su, Yin-Fong; Blake, Thomas A.; Forland, Brenda M.

    2015-05-22

    While reflectance spectroscopy is a useful tool in identifying molecular compounds, laboratory measurement of solid (particularly powder) samples often is confounded by sample preparation methods. For example, both the packing density and surface roughness can have an effect on the quantitative reflectance spectra of powdered samples. Recent efforts in our group have focused on developing standard methods for measuring reflectance spectra that accounts for sample preparation, as well as other factors such as particle size and provenance. In this work, the effect of preparation method on sample reflectivity was investigated by measuring the directional-hemispherical spectra of samples that were hand-packed as well as pressed into pellets using an integrating sphere attached to a Fourier transform infrared spectrometer. The results show that the methods used to prepare the sample have a substantial effect on the measured reflectance spectra, as do other factors such as particle size.

  13. A cryogenic dichroic mirror for separating visible light from wideband infrared

    NASA Astrophysics Data System (ADS)

    Enya, K.; Fujishiro, N.; Haze, K.; Kotani, T.; Kaneda, H.; Oyabu, S.; Ishihara, D.; Oseki, S.

    2014-08-01

    We present the design, fabrication and test results for a dichroic mirror, which was primarily developed for the SPICA Coronagraph Instrument (SCI), but is potentially useful for various types of astronomical instrument. The dichroic mirror is designed to reflect near- and mid-infrared but to transmit visible light. Two designs, one with 3 layers and one with 5 layers on BK7 glass substrates, are presented. The 3-layer design, consisting of Ag and ZnS, is simpler, and the 5-layer design, consisting of Ag and TiO2 is expected to have better performance. Tape tests, evaluation of the surface figure, and measurements of the reflectivity and transmittance were carried out at ambient temperature in air. The reflectivity obtained from measurements made on mirrors with 5 layers were < 80 % for wavelengths, λ, from 1.2 to 22 μm and < 90 % for λ from 1.8 to 20 μm. The transmittance obtained from measurements made on mirrors with 5 layers were < 70 % for λ between 0.4 and 0.8 μm. Optical ghosting is estimated to be smaller than 10-4 at λ < 1.5 μm. A protective coating for preventing corrosion was applied and its influence on the reflectivity and transmittance evaluated. A study examining the trade-offs imposed by various configurations for obtaining a telescope pointing correction signal was also undertaken.

  14. Spectrum of reflected light by self-focusing of light in a laser plasma

    SciTech Connect

    Gorbunov, L.M.

    1983-05-01

    The spectrum of the radiation reflected by a laser-produced plasma is considered. In this situation, self-focusing occurs and a region of low density (caviton) is formed. It is shown that the process leads to a considerable broadening of the spectrum on the ''red'' side, and to the appearance of a line structure in the spectrum. The results can explain data for the reflected light spectrum (L. M. Gorbunov et al., FIAN Preprint No. 126 (1979)) as being due to the nonstationary self-focusing of light in a laser-produced plasma that has recently been observed (V. L. Artsimovich et al., FIAN Preprint No. 252 (1981); Sov. Phys. Doklady 27, 618 (1982)).

  15. Characterization of Material Degradation in Ceramic Matrix Composites Using Infrared Reflectance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Cooney, Adam T.; Flattum-Riemers, Richard Y.; Scott, Benjamin J.

    2011-06-01

    Ceramic matrix composite materials for thermal protection systems are required to maintain operational performance in extreme thermal and mechanical environments. In-service inspection of materials capable of assessing the degree and extent of damage and degradation will be required to ensure the safety and readiness of future air vehicles. Infrared reflectance spectroscopy is an established material characterization technique capable of extracting information regarding the chemical composition of substances. The viability of this technique as a potentially powerful nondestructive evaluation method capable of monitoring degradation in thermal protection system materials subjected to extreme mechanical and thermal environments is analyzed. Several oxide-based and non-oxide-based ceramic matrix composite materials were stressed to failure in a high temperature environment and subsequently measured using infrared reflectance spectroscopy. Spectral signatures at locations along the length of the samples were compared resulting in distinct and monotonic reflectance peak changes while approaching the fracture point. The chemical significance of the observed signatures and the feasibility of infrared reflectance nondestructive evaluation techniques are discussed.

  16. Near infrared light responsive hybrid nanoparticles for synergistic therapy.

    PubMed

    Liang, Yan; Gao, Wenxia; Peng, Xinyu; Deng, Xin; Sun, Changzhen; Wu, Huayue; He, Bin

    2016-09-01

    A near infrared (NIR) light responsive chromophore 7-(diethylamino)-4-(hydroxymethyl)-2H-chromen-2-one (DEACM) was synthesized and incorporated to β-cyclodextrins with cRGD functionalized poly(ethylene glycol), the amphiphiles were coordinated with Au nanorods or nanoparticles to load anticancer drug doxorubicin (DOX) for fabricating hybrid nanoparticles. The π-π stacking interaction between DEACM and DOX was formed in the hybrid nanoparticles, which contributed to the high drug loading content. The Au nanorods or nanoparticles enhanced the photosolvolysis of DEACM under the irradiation of NIR with 808 nm wavelength and triggered the accelerated drug release from the nanoparticles. The drug loaded hybrid nanoparticles with NIR irradiation exhibited efficient inhibition effect on the proliferation of 4T1 breast cancer cells in vitro. The in vivo anticancer activity study on breast cancer bearing mice revealed that the hybrid nanoparticles containing Au nanorods exhibited excellent anticancer activity under the irradiation of 808 nm wavelength NIR with 800 mW. PMID:27244691

  17. Infrared imaging of LED lighting tubes and fluorescent tubes

    NASA Astrophysics Data System (ADS)

    Siikanen, Sami; Kivi, Sini; Kauppinen, Timo; Juuti, Mikko

    2011-05-01

    The low energy efficiency of conventional light sources is mainly caused by generation of waste heat. We used infrared (IR) imaging in order to monitor the heating of both LED tube luminaires and ordinary T8 fluorescent tubes. The IR images showed clearly how the surface temperatures of the fluorescent tube ends quickly rose up to about +50...+70°C, whereas the highest surface temperatures seen on the LED tubes were only about +30...+40°C. The IR images demonstrated how the heat produced by the individual LED chips can be efficiently guided to the supporting structure in order to keep the LED emitters cool and hence maintain efficient operation. The consumed electrical power and produced illuminance were also recorded during 24 hour measurements. In order to assess the total luminous efficacy of the luminaires, separate luminous flux measurements were made in a large integrating sphere. The currently available LED tubes showed efficacies of up to 88 lm/W, whereas a standard "cool white" T8 fluorescent tube produced ca. 75 lm/W. Both lamp types gave ca. 110 - 130 lx right below the ceiling-mounted luminaire, but the LED tubes consume only 40 - 55% of the electric power compared to fluorescent tubes.

  18. [Long optical path gas detection based on MEMS infrared light source].

    PubMed

    Du, Bin-Bin; Zhang, Peng; Gao, Wen-Hong; Shi, Yun-Bo; Zhu, Lin-Quan

    2014-04-01

    According to the requirements of infrared gas sensor for the light source, a broad wavelength, high modulation frequency, low power consumption and small size MEMS infrared light source is chosen as the radiation source, whose performance meets the requirements of infrared sensing system for the light source greatly. However, the infrared light source with the lamberation radiation characteristics is a surface light source, which is still with a large numerical aperture after shaping. It is difficult to increase the detection sensitivity by using a traditional long optical gas cell in a MEMS infrared light source detection system. Based on the dual-wavelength single beam differential detection method, an integrating sphere as the gas cell for long optical path is designed, which is able to realize long optical path for high sensitivity gas detection. The physical dimension is deduced for the equivalent optical path according to the flux conservation principle in the process of light transmission, solving the calculation problem of equivalent optical path of the integrating sphere cell. Using FPGA control chip, the MEMS infrared light source is droved at high frequency modulation and the detector output signal is processed, which makes the external circuit design much simple and flexible. It turns out that 166.7 cm equivalent optical path and the minimum concentration of methane of 0.001 x 10(-6) are achieved by the use of a 5 cm diameter integrating sphere in the research, improving the sensitivity of infrared detection system greatly.

  19. [Long optical path gas detection based on MEMS infrared light source].

    PubMed

    Du, Bin-Bin; Zhang, Peng; Gao, Wen-Hong; Shi, Yun-Bo; Zhu, Lin-Quan

    2014-04-01

    According to the requirements of infrared gas sensor for the light source, a broad wavelength, high modulation frequency, low power consumption and small size MEMS infrared light source is chosen as the radiation source, whose performance meets the requirements of infrared sensing system for the light source greatly. However, the infrared light source with the lamberation radiation characteristics is a surface light source, which is still with a large numerical aperture after shaping. It is difficult to increase the detection sensitivity by using a traditional long optical gas cell in a MEMS infrared light source detection system. Based on the dual-wavelength single beam differential detection method, an integrating sphere as the gas cell for long optical path is designed, which is able to realize long optical path for high sensitivity gas detection. The physical dimension is deduced for the equivalent optical path according to the flux conservation principle in the process of light transmission, solving the calculation problem of equivalent optical path of the integrating sphere cell. Using FPGA control chip, the MEMS infrared light source is droved at high frequency modulation and the detector output signal is processed, which makes the external circuit design much simple and flexible. It turns out that 166.7 cm equivalent optical path and the minimum concentration of methane of 0.001 x 10(-6) are achieved by the use of a 5 cm diameter integrating sphere in the research, improving the sensitivity of infrared detection system greatly. PMID:25007612

  20. Cryo-Transmittance and -Reflectance of Filters and Beamsplitters for the SIRTF Infrared Array Camera

    NASA Technical Reports Server (NTRS)

    Stewart, Kenneth P.; Quijada, Manuel A.a

    2000-01-01

    The Space Infrared Telescope Facility (SIRTF) Infrared Array Camera (IRAC) uses two dichroic beamsplitters, four bandpass filters, and four detector arrays to acquire images in four channels at wavelengths between 3 and 10 micron. Accurate knowledge of the pass bands is necessary because, in order to meet the science objectives, IRAC is required to do 2% relative photometry in each band relative to the other bands. We report the in-band and out-of-band polarized transmittance and reflectance of these optical elements measured near the instrument operating temperature of 1.4 K. Details of the experimental apparatus, which include a continuous flow liquid helium optical cryostat and a Fourier transform infrared (FTIR) spectrometer are discussed.

  1. Improved calibration technique of the infrared imaging bolometer using ultraviolet light-emitting diodesa)

    NASA Astrophysics Data System (ADS)

    Drapiko, E.; Peterson, B.; Alekseev, A.; Seo, D. C.

    2010-10-01

    The technique used until recently utilizing the Ne-He laser for imaging bolometer foils calibration [B. J. Peterson et al., J. Plasma Fusion Res. 2, S1018 (2007)] has showed several issues. The method was based on irradiation of 1 cm spaced set of points on a foil by the laser beam moved by set of mirrors. Issues were the nonuniformity of laser power due to the vacuum window transmission nonuniformity and high reflection coefficient for the laser. Also, due to the limited infrared (IR) window size, it was very time consuming. The new methodology uses a compact ultraviolet (uv) light-emitting diodes installed inside the vacuum chamber in a fixed position and the foil itself will be moved in the XY directions by two vacuum feedthroughs. These will help to avoid the above mentioned issues due to lack of a vacuum window, fixed emitters, higher uv power absorption, and a fixed IR camera position.

  2. [Rapid determination of fatty acids in soybean oils by transmission reflection-near infrared spectroscopy].

    PubMed

    Song, Tao; Zhang, Feng-ping; Liu, Yao-min; Wu, Zong-wen; Suo, You-rui

    2012-08-01

    In the present research, a novel method was established for determination of five fatty acids in soybean oil by transmission reflection-near infrared spectroscopy. The optimum conditions of mathematics model of five components (C16:0, C18:0, C18:1, C18:2 and C18:3) were studied, including the sample set selection, chemical value analysis, the detection methods and condition. Chemical value was analyzed by gas chromatography. One hundred fifty eight samples were selected, 138 for modeling set, 10 for testing set and 10 for unknown sample set. All samples were placed in sample pools and scanned by transmission reflection-near infrared spectrum after sonicleaning for 10 minute. The 1100-2500 nm spectral region was analyzed. The acquisition interval was 2 nm. Modified partial least square method was chosen for calibration mode creating. Result demonstrated that the 1-VR of five fatty acids between the reference value of the modeling sample set and the near infrared spectrum predictive value were 0.8839, 0.5830, 0.9001, 0.9776 and 0.9596, respectively. And the SECV of five fatty acids between the reference value of the modeling sample set and the near infrared spectrum predictive value were 0.42, 0.29, 0.83, 0.46 and 0.21, respectively. The standard error of the calibration (SECV) of five fatty acids between the reference value of testing sample set and the near infrared spectrum predictive value were 0.891, 0.790, 0.900, 0.976 and 0.942, respectively. It was proved that the near infrared spectrum predictive value was linear with chemical value and the mathematical model established for fatty acids of soybean oil was feasible. For validation, 10 unknown samples were selected for analysis by near infrared spectrum. The result demonstrated that the relative standard deviation between predict value and chemical value was less than 5.50%. That was to say that transmission reflection-near infrared spectroscopy had a good veracity in analysis of fatty acids of soybean oil.

  3. [Tri-Level Infrared Spectroscopic Identification of Hot Melting Reflective Road Marking Paint].

    PubMed

    Li, Hao; Ma, Fang; Sun, Su-qin

    2015-12-01

    In order to detect the road marking paint from the trace evidence in traffic accident scene, and to differentiate their brands, we use Tri-level infrared spectroscopic identification, which employs the Fourier transform infrared spectroscopy (FTIR), the second derivative infrared spectroscopy(SD-IR), two-dimensional correlation infrared spectroscopy(2D-IR) to identify three different domestic brands of hot melting reflective road marking paints and their raw materials in formula we Selected. The experimental results show that three labels coatings in ATR and FTIR spectrograms are very similar in shape, only have different absorption peak wave numbers, they have wide and strong absorption peaks near 1435 cm⁻¹, and strong absorption peak near 879, 2955, 2919, 2870 cm⁻¹. After enlarging the partial areas of spectrograms and comparing them with each kind of raw material of formula spectrograms, we can distinguish them. In the region 700-970 and 1370-1 660 cm⁻¹ the spectrograms mainly reflect the different relative content of heavy calcium carbonate of three brands of the paints, and that of polyethylene wax (PE wax), ethylene vinyl acetate resin (EVA), dioctyl phthalate (DOP) in the region 2800-2960 cm⁻¹. The SD-IR not only verify the result of the FTIR analysis, but also further expand the microcosmic differences and reflect the different relative content of quartz sand in the 512-799 cm-1 region. Within the scope of the 1351 to 1525 cm⁻¹, 2D-IR have more significant differences in positions and numbers of automatically peaks. Therefore, the Tri-level infrared spectroscopic identification is a fast and effective method to distinguish the hot melting road marking paints with a gradually improvement in apparent resolution.

  4. [Tri-Level Infrared Spectroscopic Identification of Hot Melting Reflective Road Marking Paint].

    PubMed

    Li, Hao; Ma, Fang; Sun, Su-qin

    2015-12-01

    In order to detect the road marking paint from the trace evidence in traffic accident scene, and to differentiate their brands, we use Tri-level infrared spectroscopic identification, which employs the Fourier transform infrared spectroscopy (FTIR), the second derivative infrared spectroscopy(SD-IR), two-dimensional correlation infrared spectroscopy(2D-IR) to identify three different domestic brands of hot melting reflective road marking paints and their raw materials in formula we Selected. The experimental results show that three labels coatings in ATR and FTIR spectrograms are very similar in shape, only have different absorption peak wave numbers, they have wide and strong absorption peaks near 1435 cm⁻¹, and strong absorption peak near 879, 2955, 2919, 2870 cm⁻¹. After enlarging the partial areas of spectrograms and comparing them with each kind of raw material of formula spectrograms, we can distinguish them. In the region 700-970 and 1370-1 660 cm⁻¹ the spectrograms mainly reflect the different relative content of heavy calcium carbonate of three brands of the paints, and that of polyethylene wax (PE wax), ethylene vinyl acetate resin (EVA), dioctyl phthalate (DOP) in the region 2800-2960 cm⁻¹. The SD-IR not only verify the result of the FTIR analysis, but also further expand the microcosmic differences and reflect the different relative content of quartz sand in the 512-799 cm-1 region. Within the scope of the 1351 to 1525 cm⁻¹, 2D-IR have more significant differences in positions and numbers of automatically peaks. Therefore, the Tri-level infrared spectroscopic identification is a fast and effective method to distinguish the hot melting road marking paints with a gradually improvement in apparent resolution. PMID:26964206

  5. [Detection of erucic acid and glucosinolate in intact rapeseed by near-infrared diffuse reflectance spectroscopy].

    PubMed

    Riu, Yu-kui; Huang, Kun-lun; Wang, Wei-min; Guo, Jing; Jin, Yin-hua; Luo, Yun-bo

    2006-12-01

    With the rapid development of transgenic food, more and more transgenic food has been pouring into the market, raising great concern about transgenic food' s edible safety. To analyze the content of erucic acid and glucosinolate in transgenic rapeseed and its parents, all the seeds were scanned intact by continuous wave of near infrared diffuse reflectance spectrometry ranging from 12 000 to 4 000 cm(-1) with a resolution of 4 cm(-1) and 64 times of scanning. Bruker OPUS software package was applied for quantification, while the results were compared with the standard methods. The results showed that the method of NIRS was very precise, which proved that infrared diffuse reflectance spectroscopy can be applied to detect the toxins in transgenic food. On the other hand, the results also showed that the content of erucic acid in transgenic rapeseeds is 0. 5-1. 0 times

  6. Modeling the attenuated total reflectance infrared (ATR-FTIR) spectrum of apatite

    NASA Astrophysics Data System (ADS)

    Aufort, Julie; Ségalen, Loïc; Gervais, Christel; Brouder, Christian; Balan, Etienne

    2016-06-01

    Attenuated total reflectance (ATR) infrared spectra were measured on a synthetic and a natural fluorapatite sample. A modeling approach based on the computation of the Fresnel reflection coefficient between the ATR crystal and the powder sample was used to analyze the line shape of the spectra. The dielectric properties of the samples were related to those of pure fluorapatite using an effective medium approach, based on Maxwell-Garnett and Bruggeman models. The Bruggeman effective medium model leads to a very good agreement with the experimental data recorded on the synthetic fluorapatite sample. The poorer agreement observed on the natural sample suggests a more significant heterogeneity of the sample at a characteristic length scale larger than the mid-infrared characteristic wavelength, i.e., about 10 micrometers. The results demonstrate the prominent role of macroscopic electrostatic effects over fine details of the microscopic structure in determining the line shape of strong ATR bands.

  7. Modeling the attenuated total reflectance infrared (ATR-FTIR) spectrum of apatite

    NASA Astrophysics Data System (ADS)

    Aufort, Julie; Ségalen, Loïc; Gervais, Christel; Brouder, Christian; Balan, Etienne

    2016-10-01

    Attenuated total reflectance (ATR) infrared spectra were measured on a synthetic and a natural fluorapatite sample. A modeling approach based on the computation of the Fresnel reflection coefficient between the ATR crystal and the powder sample was used to analyze the line shape of the spectra. The dielectric properties of the samples were related to those of pure fluorapatite using an effective medium approach, based on Maxwell-Garnett and Bruggeman models. The Bruggeman effective medium model leads to a very good agreement with the experimental data recorded on the synthetic fluorapatite sample. The poorer agreement observed on the natural sample suggests a more significant heterogeneity of the sample at a characteristic length scale larger than the mid-infrared characteristic wavelength, i.e., about 10 micrometers. The results demonstrate the prominent role of macroscopic electrostatic effects over fine details of the microscopic structure in determining the line shape of strong ATR bands.

  8. Near-infrared reflectance spectra-applications to problems in asteroid-meteorite relationships

    NASA Technical Reports Server (NTRS)

    Mcfadden, Lucy A.; Chamberlin, Alan; Vilas, Faith

    1991-01-01

    Near-infrared spectral reflectance data were collected at the Infrared Telescope Facility (IRTF) at Mauna Kea Observatories in 1985 and 1986 for the purpose of searching the region near the 3:1 Kirkwood gap for asteroids with the spectral signatures of ordinary chondrite parent bodies. Twelve reflectance spectra are observed. The presence of ordinary chondrite parent bodies among this specific set of observed asteroids is not obvious, though the sample is biased towards the larger asteroids in the region due to limitations imposed by detector sensitivity. The data set, which was acquired with the same instrumentation used for the 52-color asteroid survey (Bell et al., 1987), also presents some additional findings. The range of spectral characteristics that exist among asteroids of the same taxonomic type is noted. Conclusions based on the findings are discussed.

  9. Prepreg cure monitoring using diffuse reflectance-FTIR. [Fourier Transform Infrared Technique

    NASA Technical Reports Server (NTRS)

    Young, P. R.; Chang, A. C.

    1984-01-01

    An in situ diffuse reflectance-Fourier transform infrared technique was developed to determine infrared spectra of graphite fiber prepregs as they were being cured. A bismaleimide, an epoxy, and addition polyimide matrix resin prepregs were studied. An experimental polyimide adhesive was also examined. Samples were positioned on a small heater at the focal point of diffuse reflectance optics and programmed at 15 F/min while FTIR spectra were being scanned, averaged, and stored. An analysis of the resulting spectra provided basic insights into changes in matrix resin molecular structure which accompanied reactions such as imidization and crosslinking. An endo-exothermal isomerization involving reactive end-caps was confirmed for the addition polyimide prepregs. The results of this study contribute to a fundamental understanding of the processing of composites and adhesives. Such understanding will promote the development of more efficient cure cycles.

  10. Measuring near infrared spectral reflectance changes from water stressed conifer stands with AIS-2

    NASA Technical Reports Server (NTRS)

    Riggs, George; Running, Steven W.

    1987-01-01

    Airborne Imaging Spectrometer-2 (AIS-2) data was acquired over two paired conifer stands for the purpose of detecting differences in spectral reflectance between stressed and natural canopies. Water stress was induced in a stand of Norway spruce and white pine by severing the sapwood near the ground. Water stress during the AIS flights was evaluated through shoot water potential and relative water content measurements. Preliminary analysis with raw AIS-2 data using SPAM indicates that there were small, inconsistent differences in absolute spectral reflectance in the near infrared 0.97 to 1.3 micron between the stressed and natural canopies.

  11. Influence of Si doping on the infrared reflectance characteristics of GaN grown on sapphire

    NASA Astrophysics Data System (ADS)

    Hou, Y. T.; Feng, Z. C.; Chua, S. J.; Li, M. F.; Akutsu, N.; Matsumoto, K.

    1999-11-01

    Si-doped GaN films grown on sapphire are investigated by infrared reflectance. A damping behavior of the interference fringes is observed, and interpreted to be due to the presence of an interface layer between the film and the substrate. A theoretical calculation using a two-layer model to take into account the interface layer resulted in this damping in agreement with the experiment. The damping behavior and an improvement of interface properties by Si incorporation are demonstrated.

  12. Label-free near-infrared reflectance microscopy as a complimentary tool for two-photon fluorescence brain imaging.

    PubMed

    Allegra Mascaro, Anna Letizia; Costantini, Irene; Margoni, Emilia; Iannello, Giulio; Bria, Alessandro; Sacconi, Leonardo; Pavone, Francesco S

    2015-11-01

    In vivo two-photon imaging combined with targeted fluorescent indicators is currently extensively used for attaining critical insights into brain functionality and structural plasticity. Additional information might be gained from back-scattered photons from the near-infrared (NIR) laser without introducing any exogenous labelling. Here, we describe a complimentary and versatile approach that, by collecting the reflected NIR light, provides structural details on axons and blood vessels in the brain, both in fixed samples and in live animals under a cranial window. Indeed, by combining NIR reflectance and two-photon imaging of a slice of hippocampus from a Thy1-GFPm mouse, we show the presence of randomly oriented axons intermingled with sparsely fluorescent neuronal processes. The back-scattered photons guide the contextualization of the fluorescence structure within brain atlas thanks to the recognition of characteristic hippocampal structures. Interestingly, NIR reflectance microscopy allowed the label-free detection of axonal elongations over the superficial layers of mouse cortex under a cranial window in vivo. Finally, blood flow can be measured in live preparations, thus validating label free NIR reflectance as a tool for monitoring hemodynamic fluctuations. The prospective versatility of this label-free technique complimentary to two-photon fluorescence microscopy is demonstrated in a mouse model of photothrombotic stroke in which the axonal degeneration and blood flow remodeling can be investigated.

  13. Label-free near-infrared reflectance microscopy as a complimentary tool for two-photon fluorescence brain imaging

    PubMed Central

    Mascaro, Anna Letizia Allegra; Costantini, Irene; Margoni, Emilia; Iannello, Giulio; Bria, Alessandro; Sacconi, Leonardo; Pavone, Francesco S.

    2015-01-01

    In vivo two-photon imaging combined with targeted fluorescent indicators is currently extensively used for attaining critical insights into brain functionality and structural plasticity. Additional information might be gained from back-scattered photons from the near-infrared (NIR) laser without introducing any exogenous labelling. Here, we describe a complimentary and versatile approach that, by collecting the reflected NIR light, provides structural details on axons and blood vessels in the brain, both in fixed samples and in live animals under a cranial window. Indeed, by combining NIR reflectance and two-photon imaging of a slice of hippocampus from a Thy1-GFPm mouse, we show the presence of randomly oriented axons intermingled with sparsely fluorescent neuronal processes. The back-scattered photons guide the contextualization of the fluorescence structure within brain atlas thanks to the recognition of characteristic hippocampal structures. Interestingly, NIR reflectance microscopy allowed the label-free detection of axonal elongations over the superficial layers of mouse cortex under a cranial window in vivo. Finally, blood flow can be measured in live preparations, thus validating label free NIR reflectance as a tool for monitoring hemodynamic fluctuations. The prospective versatility of this label-free technique complimentary to two-photon fluorescence microscopy is demonstrated in a mouse model of photothrombotic stroke in which the axonal degeneration and blood flow remodeling can be investigated. PMID:26601011

  14. High reflected cubic cavity as long path absorption cell for infrared gas sensing

    NASA Astrophysics Data System (ADS)

    Yu, Jia; Gao, Qiang; Zhang, Zhiguo

    2014-10-01

    One direct and efficient method to improve the sensitivity of infrared gas sensors is to increase the optical path length of gas cells according to Beer-Lambert Law. In this paper, cubic shaped cavities with high reflected inner coating as novel long path absorption cells for infrared gas sensing were developed. The effective optical path length (EOPL) for a single cubic cavity and tandem cubic cavities were investigated based on Tunable Diode Laser Absorption Spectroscopy (TDLAS) measuring oxygen P11 line at 763 nm. The law of EOPL of a diffuse cubic cavity in relation with the reflectivity of the coating, the port fraction and side length of the cavity was obtained. Experimental results manifested an increase of EOPL for tandem diffuse cubic cavities as the decrease of port fraction of the connecting aperture f', and the EOPL equaled to the sum of that of two single cubic cavities at f'<0.01. The EOPL spectra at infrared wavelength range for different inner coatings including high diffuse coatings and high reflected metallic thin film coatings were deduced.

  15. Polymer-cholesteric liquid-crystalline composites with a broad light reflection band

    NASA Astrophysics Data System (ADS)

    Mitov, Michel

    2016-05-01

    Cholesteric liquid crystals selectively reflect the light. The reflection bandgap is typically limited to 100 nm in the visible spectrum and, at the best, 50% of the unpolarized incident light is reflected. Solutions are found in biopolymers and polymer-liquid crystal composite materials to go beyond these limits.

  16. Reflective films and expression of light-regulated genes in field-grown apple

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Reflective films are used in orchard management to improve fruit coloration. Numerous physiological studies on the effects of application of these films have been conducted, including variation of angles of light incidence and reflection, spectral determination of reflected light and effects on pho...

  17. Multipitched Diffraction Gratings for Surface Plasmon Resonance-Enhanced Infrared Reflection Absorption Spectroscopy.

    PubMed

    Petefish, Joseph W; Hillier, Andrew C

    2015-11-01

    We demonstrate the application of metal-coated diffraction gratings possessing multiple simultaneous pitch values for surface enhanced infrared absorption (SEIRA) spectroscopy. SEIRA increases the magnitude of vibrational signals in infrared measurements by one of several mechanisms, most frequently involving the enhanced electric field associated with surface plasmon resonance (SPR). While the majority of SEIRA applications to date have employed nanoparticle-based plasmonic systems, recent advances have shown how various metals and structures lead to similar signal enhancement. Recently, diffraction grating couplers have been demonstrated as a highly tunable platform for SEIRA. Indeed, gratings are an experimentally advantageous platform due to the inherently tunable nature of surface plasmon excitation at these surfaces since both the grating pitch and incident angle can be used to modify the spectral location of the plasmon resonance. In this work, we use laser interference lithography (LIL) to fabricate gratings possessing multiple pitch values by subjecting photoresist-coated glass slides to repetitive exposures at varying orientations. After metal coating, these gratings produced multiple, simultaneous plasmon peaks associated with the multipitched surface, as identified by infrared reflectance measurements. These plasmon peaks could then be coupled to vibrational modes in thin films to provide localized enhancement of infrared signals. We demonstrate the flexibility and tunability of this platform for signal enhancement. It is anticipated that, with further refinement, this approach might be used as a general platform for broadband enhancement of infrared spectroscopy. PMID:26458177

  18. Multipitched Diffraction Gratings for Surface Plasmon Resonance-Enhanced Infrared Reflection Absorption Spectroscopy.

    PubMed

    Petefish, Joseph W; Hillier, Andrew C

    2015-11-01

    We demonstrate the application of metal-coated diffraction gratings possessing multiple simultaneous pitch values for surface enhanced infrared absorption (SEIRA) spectroscopy. SEIRA increases the magnitude of vibrational signals in infrared measurements by one of several mechanisms, most frequently involving the enhanced electric field associated with surface plasmon resonance (SPR). While the majority of SEIRA applications to date have employed nanoparticle-based plasmonic systems, recent advances have shown how various metals and structures lead to similar signal enhancement. Recently, diffraction grating couplers have been demonstrated as a highly tunable platform for SEIRA. Indeed, gratings are an experimentally advantageous platform due to the inherently tunable nature of surface plasmon excitation at these surfaces since both the grating pitch and incident angle can be used to modify the spectral location of the plasmon resonance. In this work, we use laser interference lithography (LIL) to fabricate gratings possessing multiple pitch values by subjecting photoresist-coated glass slides to repetitive exposures at varying orientations. After metal coating, these gratings produced multiple, simultaneous plasmon peaks associated with the multipitched surface, as identified by infrared reflectance measurements. These plasmon peaks could then be coupled to vibrational modes in thin films to provide localized enhancement of infrared signals. We demonstrate the flexibility and tunability of this platform for signal enhancement. It is anticipated that, with further refinement, this approach might be used as a general platform for broadband enhancement of infrared spectroscopy.

  19. Study on the activation of styrene-based shape memory polymer by medium-infrared laser light

    SciTech Connect

    Leng Jinsong; Yu Kai; Lan Xin; Zhang Dawei; Liu Yanju

    2010-03-15

    This paper demonstrates the feasibility of shape memory polymer (SMP) activation by medium-infrared laser light. Medium-infrared light is transmitted by an optical fiber embedded in the SMP matrix, and the shape recovery process and temperature distribution are recorded by an infrared camera. Light-induced SMP exhibits potential applications in biomedicines and flexible displays.

  20. Characterization of silver halide fiber optics and hollow silica waveguides for use in the construction of a mid-infrared attenuated total reflection fourier transform infrared (ATR FT-IR) spectroscopy probe.

    PubMed

    Damin, Craig A; Sommer, André J

    2013-11-01

    Advances in fiber optic materials have allowed for the construction of fibers and waveguides capable of transmitting infrared radiation. An investigation of the transmission characteristics associated with two commonly used types of infrared-transmitting fibers/waveguides for prospective use in a fiber/waveguide-coupled attenuated total internal reflection (ATR) probe was performed. Characterization of silver halide polycrystalline fiber optics and hollow silica waveguides was done on the basis of the transmission of infrared light using a conventional fiber optic coupling accessory and an infrared microscope. Using the fiber optic coupling accessory, the average percent transmission for three silver halide fibers was 18.1 ± 6.1% relative to a benchtop reflection accessory. The average transmission for two hollow waveguides (HWGs) using the coupling accessory was 8.0 ± 0.3%. (Uncertainties in the relative percent transmission represent the standard deviations.) Reduced transmission observed for the HWGs was attributed to the high numerical aperture of the coupling accessory. Characterization of the fibers/waveguides using a zinc selenide lens objective on an infrared microscope indicated 24.1 ± 7.2% of the initial light input into the silver halide fibers was transmitted. Percent transmission obtained for the HWGs was 98.7 ± 0.1%. Increased transmission using the HWGs resulted from the absence or minimization of insertion and scattering losses due to the hollow air core and a better-matched numerical aperture. The effect of bending on the transmission characteristics of the fibers/waveguides was also investigated. Significant deviations in the transmission of infrared light by the solid-core silver halide fibers were observed for various bending angles. Percent transmission greater than 98% was consistently observed for the HWGs at the bending angles. The combined benefits of high percent transmission, reproducible instrument responses, and increased bending

  1. Noninvasive blood glucose sensing on human body with near-infrared reflection spectroscopy

    NASA Astrophysics Data System (ADS)

    Huang, Zhen-hao; Hao, Chang-ning; Zhang, Lin-lin; Huang, Yan-chao; Shi, Yi-qin; Jiang, Geng-ru; Duan, Jun-li

    2011-08-01

    The non-invasive blood glucose sensing method has shown its high impact on the clinic application. This can make the measurement on the clinically relevant concentrations of glucose be free from the pain of patient. The transmission spectrum study indicates that the dependence of glucose concentration on the absorbance is in linear manner for the glucose concentration in the region of 30mg/dL to 4.5×104mg/dL. By the near infrared reflection spectroscopy of fiber spectrometer, the reflection band between 1.2μm and 1.35μm can be used to correlated with the glucose concentration in the range of 30 to 300 mg/dL. This reflection band is finally used to measure the glucose concentration effect in non-invasive manner, which gives the statistical significance of P value 0.02. Our experiment result shows that it is possible to get the glucose concentration by the near infrared reflection spectrum measurement on the human forefinger. This non-invasive blood glucose sensing method may useful in clinic after more experiment for different people.

  2. Detection of Cracks on Tomatoes Using a Hyperspectral Near-Infrared Reflectance Imaging System

    PubMed Central

    Lee, Hoonsoo; Kim, Moon S.; Jeong, Danhee; Delwiche, Stephen R.; Chao, Kuanglin; Cho, Byoung-Kwan

    2014-01-01

    The objective of this study was to evaluate the use of hyperspectral near-infrared (NIR) reflectance imaging techniques for detecting cuticle cracks on tomatoes. A hyperspectral NIR reflectance imaging system that analyzed the spectral region of 1000–1700 nm was used to obtain hyperspectral reflectance images of 224 tomatoes: 112 with and 112 without cracks along the stem-scar region. The hyperspectral images were subjected to partial least square discriminant analysis (PLS-DA) to classify and detect cracks on the tomatoes. Two morphological features, roundness (R) and minimum-maximum distance (D), were calculated from the PLS-DA images to quantify the shape of the stem scar. Linear discriminant analysis (LDA) and a support vector machine (SVM) were then used to classify R and D. The results revealed 94.6% and 96.4% accuracy for classifications made using LDA and SVM, respectively, for tomatoes with and without crack defects. These data suggest that the hyperspectral near-infrared reflectance imaging system, in addition to traditional NIR spectroscopy-based methods, could potentially be used to detect crack defects on tomatoes and perform quality assessments. PMID:25310472

  3. Graphical Approach to Fresnel's Equations for Reflection and Refraction of Light.

    ERIC Educational Resources Information Center

    Doyle, William T.

    1980-01-01

    Develops a coordinate-free approach to Fresnel's equations for the reflection and refraction of light at a plane interface. Describes a graphical construction for finding the vector amplitudes of the reflected and transmitted waves. (Author/CS)

  4. Infrared reflectance of AlN-GaN short period superlattice films

    NASA Astrophysics Data System (ADS)

    MacMillan, M. F.; Devaty, R. P.; Choyke, W. J.; Khan, M. Asif; Kuznia, J.

    1996-08-01

    The room-temperature infrared reflectance of AlN-GaN short period superlattice films has been measured. These superlattice films were deposited by switched atomic layer metalorganic chemical vapor deposition onto GaN or AlN buffer layers deposited on basal plane sapphire substrates. The measured reflectance spectra are compared to calculated spectra using an effective medium theory to model the dielectric function of the superlattice. The optical properties of the individual materials making up the samples are modeled with Lorentz oscillators using only bulk input parameters. The effects of film and substrate anisotropy and off-normal incidence are included in the calculation. Using this modeling technique, it is possible to obtain thickness estimates for the superlattice film and the buffer layer. The complicated structures seen in the reststrahl region reflectance of these films are also analyzed by comparison to the calculated spectra.

  5. Lights, Camera, Action: Facilitating PETE Students' Reflection through Film

    ERIC Educational Resources Information Center

    Lee, Okseon; Ravizza, Dean; Lee, Myung-Ah

    2009-01-01

    Preparing teacher candidates to be reflective professionals is a critical component of physical education teacher education programs. Although many specific strategies have been developed to facilitate post-lesson reflection, strategies for reflecting on future work and professional life have not been widely explored. As a way to facilitate…

  6. Quantum Well Infrared Photodetectors: Device Physics and Light Coupling

    NASA Technical Reports Server (NTRS)

    Bandara, S. V.; Gunapala, S. D.; Liu, J. K.; Mumolo, J.; Luong, E.; Hong, W.; Sengupta, D. K.

    1997-01-01

    It is customary to make infrared (IR) detectors in the long wavelength range by utilizing the interband transition which promotes an electron across the band gap (Eg) from the valence band to the conduction.

  7. Killing Cancer Cells with the Help of Infrared Light – Photoimmunotherapy

    Cancer.gov

    Near-infrared photoimmunotherapy uses an antibody–photoabsorber conjugate that binds to cancer cells. When near-infrared light is applied, the cells swell and then burst, causing the cancer cell to die. Photoimmunotherapy is in clinical trials in patients with inoperable tumors.

  8. [The evaluation of hydrocarbon potential generation for source rocks by near-infrared diffuse reflection spectra].

    PubMed

    Zhang, Yu-Jia; Xu, Xiao-Xuan; Song, Ning; Wu, Zhong-Chen; Zhou, Xiang; Chen, Jin; Cao, Xue-Wei; Wang, Bin

    2011-04-01

    Near-infrared (NIR) and mid-infrared (MIR) diffuse reflection spectra were compared and evaluated for hydrocarbon potential generation of source rocks. Near-infrared diffuse reflectance often exhibits significant differences in the spectra due to the non-homogeneous distribution of the particles, so the signal-to-noise ratio of NIR is much lower than MIR It is too difficult to get accurate results by NIR without using a strong spectral preprocessing method to remove systematic noise such as base-line variation and multiplicative scatter effects. In the present paper, orthogonal signal correction (OSC) and an improved algorithm of it, i.e. direct orthogonal signal correction (DOSC), are used as different methods to preprocess both the NIR and MIR spectra of the hydrocarbon source rocks. Another algorithm, wavelet multi-scale direct orthogonal signal correction (WMDOSC), which is a combination of discrete wavelet transform (DWT) and DOSC, is also used as a preprocessing method. Then, the calibration model of hydrocarbon source rocks before and after pretreatment was established by interval partial least square (iPLS). The experimental results show that WMDOSC is more successfully applied to preprocess the NIR spectra data of the hydrocarbon source rocks than other two algorithms, and NIR performed as good as MIR in the analysis of hydrocarbon potential generation of source rocks with WMDOSC-iPLS pretreatment calibration model.

  9. Assessment of diffuse transmission and reflection modes in near-infrared quantification, part 2: DIFFuse reflection information depth.

    PubMed

    Saeed, Muhanned; Probst, Leila; Betz, Gabriele

    2011-03-01

    Near-infrared spectroscopy offers tremendous advantages for pharmaceutical manufacturing as a fast and nondestructive method of quantitative and qualitative analysis. Content uniformity (end-product analytics) and process analytics are two important applications of the method. Diffuse reflection (DR) information depth (vertical sampling span) assessment is of equal importance in content prediction applications and to understand the effect of inhomogeneities in the sample. Three experiments were conducted: (a) 0.5 to 10.0 mm incremental thickness MCC tablets with constant porosity, (b) MCC/phenylbutazone (PBZ) double-layered (DL) tablets (PBZ layer 0%-100% in 0.5 mm steps), and (c) Comparison of placebo and 30% caffeine tablet cores with incremental film coating (film thickness of 0-0.35 mm). Incremental thickness and cluster analysis of DL tablets showed that DR information depth was <0.5 mm, whereas the data fitting from incremental coating showed that signal drop reached 50% at 0.05 to 0.07 mm, depending on the wavenumber and 90% signal drop (10% information content) can be seen between 0.20 and 0.25 mm without extrapolation. These results mean that DR mode for pharmaceutical tablets obtains spectral information from the very surface, and radiation is barely reflected back from beyond thin-film coatings, making it less useful than diffuse transmission mode for core content analysis, especially for thick-coated, multilayer, multicore, or highly inhomogeneous tablets.

  10. High temperature far-infrared dynamics of orthorhombic NdMnO3: emissivity and reflectivity.

    PubMed

    Massa, Néstor E; del Campo, Leire; Meneses, Domingos De Sousa; Echegut, Patrick; Martínez-Lope, María Jesús; Alonso, José Antonio

    2013-06-12

    We report on near normal far- and mid-infrared emission and reflectivity of NdMnO3 perovskite from room temperature to sample decomposition above 1800 K. At 300 K the number of infrared active phonons is in close agreement with the 25 calculated for the orthorhombic D(2h)(16)-Pbnm (Z = 4) space group. Their number gradually decreases as we approach the temperature of orbital disorder at ~1023 K where the orthorhombic O' lower temperature cooperative phase coexists with the cubic orthorhombic O. At above ~1200 K, the three infrared active phonons coincide with that expected for cubic Pm-3m (Z = 1) in the high temperature insulating regime. Heating samples in dry air triggers double exchange conductivity by Mn(3+) and Mn(4+) ions and a small polaron mid-infrared band. Fits to the optical conductivity single out the octahedral antisymmetric and symmetric vibrational modes as the main phonons in the electron-phonon interactions at 875 K. For 1745 K, it is enough to consider the symmetric stretching internal mode. An overdamped defect induced Drude component is clearly outlined at the highest temperatures. We conclude that rare earth manganite eg electrons are prone to spin, charge, orbital, and lattice couplings in an intrinsic orbital distorted perovskite lattice, favoring embryonic low energy collective excitations.

  11. Development of a realistic photonic modeling for the evaluation of infrared reflections in the metallic environment of ITER

    SciTech Connect

    Aumeunier, M.-H.; Travere, J.-M.

    2010-10-15

    In nuclear fusion experiments, the plasma facing components are exposed to high heat fluxes and infrared (IR) imaging diagnostics are routinely used for surveying their surface temperature for preventing damages. However the future use of metallic components in the ITER tokamak adds complications in temperature estimation. Indeed, low and variable emissivity of the observed surface and the multiple reflections of the light coming from hot regions will have to be understood and then taken into account. In this paper, a realistic photonic modeling based on Monte Carlo ray-tracing codes is used to predict the global response of the complete IR survey system. This also includes the complex vessel geometry and the thermal and optical surface properties using the bidirectional reflectivity distribution function that models the photon-material interactions. The first results of this simulation applied to a reference torus are presented and are used as a benchmark to investigate the validity of the global model. Finally the most critical key model parameters in the reflected signals are identified and their contribution is discussed.

  12. Development of a realistic photonic modeling for the evaluation of infrared reflections in the metallic environment of ITER.

    PubMed

    Aumeunier, M-H; Travere, J-M

    2010-10-01

    In nuclear fusion experiments, the plasma facing components are exposed to high heat fluxes and infrared (IR) imaging diagnostics are routinely used for surveying their surface temperature for preventing damages. However the future use of metallic components in the ITER tokamak adds complications in temperature estimation. Indeed, low and variable emissivity of the observed surface and the multiple reflections of the light coming from hot regions will have to be understood and then taken into account. In this paper, a realistic photonic modeling based on Monte Carlo ray-tracing codes is used to predict the global response of the complete IR survey system. This also includes the complex vessel geometry and the thermal and optical surface properties using the bidirectional reflectivity distribution function that models the photon-material interactions. The first results of this simulation applied to a reference torus are presented and are used as a benchmark to investigate the validity of the global model. Finally the most critical key model parameters in the reflected signals are identified and their contribution is discussed.

  13. Investigations of high-speed digital imaging of low-light-level events using pulsed near-infrared laser light sources

    NASA Astrophysics Data System (ADS)

    Jantzen, Connie; Slagle, Rick

    1997-05-01

    The distinction between exposure time and sample rate is often the first point raised in any discussion of high speed imaging. Many high speed events require exposure times considerably shorter than those that can be achieved solely by the sample rate of the camera, where exposure time equals 1/sample rate. Gating, a method of achieving short exposure times in digital cameras, is often difficult to achieve for exposure time requirements shorter than 100 microseconds. This paper discusses the advantages and limitations of using the short duration light pulse of a near infrared laser with high speed digital imaging systems. By closely matching the output wavelength of the pulsed laser to the peak near infrared response of current sensors, high speed image capture can be accomplished at very low (visible) light levels of illumination. By virtue of the short duration light pulse, adjustable to as short as two microseconds, image capture of very high speed events can be achieved at relatively low sample rates of less than 100 pictures per second, without image blur. For our initial investigations, we chose a ballistic subject. The results of early experimentation revealed the limitations of applying traditional ballistic imaging methods when using a pulsed infrared lightsource with a digital imaging system. These early disappointing results clarified the need to further identify the unique system characteristics of the digital imager and pulsed infrared combination. It was also necessary to investigate how the infrared reflectance and transmittance of common materials affects the imaging process. This experimental work yielded a surprising, successful methodology which will prove useful in imaging ballistic and weapons tests, as well as forensics, flow visualizations, spray pattern analyses, and nocturnal animal behavioral studies.

  14. Mars - Near-infrared spectral reflectance of surface regions and compositional implications

    NASA Astrophysics Data System (ADS)

    McCord, T. B.; Clark, R. N.; Singer, R. B.

    1982-04-01

    Both morphological and compositional information are needed to define and characterize surface geologic units on Mars. A description is presented of new, near-infrared spectra (0.65 to 2.50 micrometers) for 11 regions on the Martian surface observed in 1978. The high photometric quality of these data combined with increased near-infrared spectral coverage provide new information about the spectral behavior and, therefore, the composition and physical nature of Martian surface materials. The spectral reflectances were obtained with the aid of a 2.2-m telescope located on Mauna Kea, Hawaii. A cooled (to 77 K) circular variable filter spectrometer with an InSb detector was used to measure alternatively Mars and the standard star Beta Geminorum. Attention is given to general spectral characteristics, the dark region composition, spectral evidence for water, and the 2.3 micrometer absorption.

  15. Rheo-attenuated total reflectance infrared spectroscopy: a new tool to study biopolymers.

    PubMed

    Boulet-Audet, Maxime; Vollrath, Fritz; Holland, Chris

    2011-03-01

    Whilst rheology is the reference technique to study the mechanical properties of unspun silk, we know little of the structure and the dynamics that generate them. By coupling infrared spectroscopy and shearing forces to study silk fibroin conversion, we are introducing a novel tool to address this gap in our knowledge. Here the silk conversion process has been studied dynamically using polarized attenuated total reflectance Fourier transform infrared spectroscopy whilst applying shear, thus revealing silk protein conformation and molecular orientation in situ. Our results show that the silk conversion process starts with a pre-alignment of the proteins followed by a rapid growth of the β-sheet formation and then a subsequent deceleration of the growth. We propose that this tool will provide further insight into not only silk but any biopolymer solution, opening a new window into biological materials.

  16. [Applications of near infrared reflectance spectroscopy technique (NIRS) to soil attributes research].

    PubMed

    Liu, Yan-De; Xiong, Song-Sheng; Liu, De-Li

    2014-10-01

    Soil is a much complicated substance, because animals, plants and microbes live together, organic and inorganic exist together. So soil contains a large amount of information. The traditional method in laboratory is a time-consuming effort. But the technology of near infrared reflectance spectroscopy (NIRS) has been widely used in many areas, owing to its rapidness, high efficiency, no pollution and low cost, NIRS has become the most important method to detect the composition of soil. This paper mainly introduce some traditional methods in laboratory, the basic processes of soil detection by NIRS, some algorithms for data preprocessing and modeling. Besides, the present paper illustrates the latest research progress and the development of portable near infrared instruments of the soil. According to this paper, the authors also hope to promote the application conditions of NIRS in the grassland ecology research in China, and accelerate the modernization of research measures in this area.

  17. Infrared Attenuated Total Reflectance Spectroscopy: An Innovative Strategy for Analyzing Mineral Components in Energy Relevant Systems

    PubMed Central

    Müller, Christian Menno; Pejcic, Bobby; Esteban, Lionel; Piane, Claudio Delle; Raven, Mark; Mizaikoff, Boris

    2014-01-01

    The direct qualitative and quantitative determination of mineral components in shale rocks is a problem that has not been satisfactorily resolved to date. Infrared spectroscopy (IR) is a non-destructive method frequently used in mineral identification, yet challenging due to the similarity of spectral features resulting from quartz, clay, and feldspar minerals. This study reports on a significant improvement of this methodology by combining infrared attenuated total reflection spectroscopy (IR-ATR) with partial least squares (PLS) regression techniques for classifying and quantifying various mineral components present in a number of different shale rocks. The developed multivariate classification model was calibrated using pure component mixtures of the most common shale minerals (i.e., kaolinite, illite, montmorillonite, calcite, and quartz). Using this model, the IR spectra of 11 real-world shale samples were analyzed and evaluated. Finally, the performance of the developed IR-ATR method was compared with results obtained via X-ray diffraction (XRD) analysis. PMID:25358261

  18. Light reflection by the cuticle of C. aurigans scarabs: a biological broadband reflector of left handed circularly polarized light

    NASA Astrophysics Data System (ADS)

    Libby, E.; Azofeifa, D. E.; Hernández-Jiménez, M.; Barboza-Aguilar, C.; Solís, A.; García-Aguilar, I.; Arce-Marenco, L.; Hernández, A.; Vargas, W. E.

    2014-08-01

    Measured reflection spectra from elytra of Chrysina aurigans scarabs are reported. They show a broad reflection band for wavelengths from 0.525 to 1.0 μm with a sequence of maxima and minima reflection values superimposed on a mean value of around 40% for the high reflection band. Different mechanisms contributing to the reflection spectra have been considered, with the dominant effect, reflection of left handed circularly polarized light, being produced by a laminated left handed twisted structure whose pitch changes with depth through the procuticle in a more complex way than that characterizing broad band circular polarizers based on cholesteric liquid crystals.

  19. Near-infrared reflectance spectroscopy as a novel method to detect demyelination in rat sciatic nerve in vivo

    NASA Astrophysics Data System (ADS)

    Radhakrishnan, Harsha; Senapati, Arun; Peng, Yuan Bo; Kashyap, Dheerendra; Liu, Hanli

    2005-04-01

    This study was done to use near infrared (NIR) spectroscopy to bring out differences in the anatomical substructures in the rat spinal cord and further to differentiate scattering between demyelinated and normal sciatic nerves in rat models, thereby exploring a new methodology to localize MS (multiple Sclerosis) lesions in vivo for animal studies. The experimental setup consisted of a tungsten light source, CCD array spectrometer, and bifurcated optical fibers for light delivery and detection of back scattered light from tissue. The measurement system was calibrated with reflectance standard. The spinal cord of 14 rats was exposed by laminectomy, and the measurements were taken on 8 points at intervals of 1 mm on the right and left lumbar-sacral regions and the central blood vessel. For measurements on the sciatic nerve, the spinal nerves of 84 rats were ligated according to the Chung Model. Measurements were taken on five points on both the ligated and the control nerve side after 1, 4, 7 and 14 days. The reduced scattering coefficient, μs', was found to be higher in the lumbar-sacral regions (34.17 +/- 2.05 cm-1) than that near the central blood vessel (19.9 +/- 3.8 cm-1). Statistically, there was significant difference in scattering between the control side and the ligated side on postoperative days 4, 7, and 14. This study shows a promising diagnostic value in the future for monitoring of demyelinated CNS (central nervous system) diseases, like Multiple Sclerosis.

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

    NASA Technical Reports Server (NTRS)

    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.

  1. Infrared reflectance spectra (2. 2-15. mu. m) of plagioclase feldspars

    SciTech Connect

    Nash, D.B. ); Salisbury, J.W. )

    1991-06-01

    Laboratory results show that (1) the Christiansen frequency (CF) feature in mid-infrared reflectance spectra of powders can be used to accurately distinguish plagioclase composition, and (2) the wavelength position of the CF is not affected by vitrification of the plagioclase. Although the CF position does not distinguish glass from crystalline forms of plagioclase, other features (combination-tone, overtone, restrahlen bands) in the mid-IR spectra of plagioclase can be used for that purpose. These results have important implications for application of thermal emission spectroscopy to mapping the surface composition of regolith-covered planetary bodies like the Moon, Mars, and asteroids.

  2. Surface-enhanced infrared absorption of nucleic acids on gold substrate in FTIR reflectance mode

    NASA Astrophysics Data System (ADS)

    Dovbeshko, G. I.; Chegel, Vladimir I.; Gridina, Nina Y.; Repnytska, O. P.; Sekirin, I. V.; Shirshov, Yuri M.

    2001-06-01

    Data on surface enhanced infrared absorption (SEIRA) of nucleic acids deposited on the metal surface have been obtained in the experiment in FTIR reflectance mode. As metal surface, we used Au of 200 - 500 Angstrom thickness on quartz substrate. Roughness of Au was not greater than 50 Angstrom. In our experimental conditions, the enhancement factor of SEIRA was about 3 - 7. We obtained different enhancement factors for different vibrations of nuclei acids. Application of this method to the tumour brain nucleic acid gave a possibility to reveal some structural peculiarities of their sugar-phosphate backbone.

  3. [Sugar characterization of mini-watermelon and rapid sugar determination by near infrared diffuse reflectance spectroscopy].

    PubMed

    Wang, Shuo; Yuan, Hong-fu; Song, Chun-feng; Xie, Jin-chun; Li, Xiao-yu; Feng, Le-ping

    2012-08-01

    In the present paper, the distribution of sugar level within the mini-watermelon was studied, a new sugar characterization method of mini-watermelon using average sugar level, the highest sugar level and the lowest sugar level index is proposed. Feasibility of nondestructive determination of mini-watermenlon sugar level using diffuse reflectance spectroscopy information was investigated by an experiment. PLS models for measuring the 3 sugar levels were established. The results obtained by near infrared spectroscopy agreed with that of the new method established above.

  4. Atomic Scale Flatness of Chemically Cleaned Silicon Surfaces Studied by Infrared Attenuated-Total-Reflection Spectroscopy

    NASA Astrophysics Data System (ADS)

    Sawara, Kenichi; Yasaka, Tatsuhiro; Miyazaki, Seiichi; Hirose, Masataka

    1992-07-01

    Hydrogen-terminated Si(111) and Si(100) surfaces obtained by aqueous HF or pH-modified (pH{=}5.3) buffered-HF (BHF) treatments have been characterized by a Fourier transform infrared (FT-IR) attenuated-total-reflection (ATR) technique. The BHF treatment provides better surface flatness than the HF treatment. Pure water rinse is effective for improving the Si(111) surface flatness, while this is not the case for Si(100) because the pure water acts as an alkaline etchant and promotes the formation of (111) microfacets or microdefects on the (100) surface.

  5. Soil moisture estimation using reflected solar and emitted thermal infrared radiation

    NASA Technical Reports Server (NTRS)

    Jackson, R. D.; Cihlar, J.; Estes, J. E.; Heilman, J. L.; Kahle, A.; Kanemasu, E. T.; Millard, J.; Price, J. C.; Wiegand, C. L.

    1978-01-01

    Classical methods of measuring soil moisture such as gravimetric sampling and the use of neutron moisture probes are useful for cases where a point measurement is sufficient to approximate the water content of a small surrounding area. However, there is an increasing need for rapid and repetitive estimations of soil moisture over large areas. Remote sensing techniques potentially have the capability of meeting this need. The use of reflected-solar and emitted thermal-infrared radiation, measured remotely, to estimate soil moisture is examined.

  6. Preliminary Method for Direct Quantification of Colistin Methanesulfonate by Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy

    PubMed Central

    Niece, Krista L.

    2015-01-01

    Colistin use has increased in response to the advent of infections caused by multidrug-resistant organisms. It is administered parenterally as an inactive prodrug, colistin methanesulfonate (CMS). Various formulations of CMS and labeling conventions can lead to confusion about colistin dosing, and questions remain about the pharmacokinetics of CMS. Since CMS does not have strong UV absorbance, current methods employ a laborious process of chemical conversion to colistin followed by precolumn derivatization to detect formed colistin by high-performance liquid chromatography. Here, we report a method for direct quantification of colistin methanesulfonate by attenuated total reflectance Fourier transform infrared spectroscopy (ATR FTIR). PMID:26124160

  7. Infrared reflection and Raman scattering on Ba 1-xRb xBiO 3

    NASA Astrophysics Data System (ADS)

    Inoue, A.; Iyo, A.; Oiji, Y.; Tanaka, Y.; Tokumoto, M.; Uwe, H.; Sakudo, T.

    1991-12-01

    Measurements of infrared (IR) reflectivity and Raman scattering have been performed on Ba 1-xRb xBiO 3. The oscillator strength of the Bi-Bi stretching mode decreases with increasing Rb concentration, while the frequency change is small. The phonons detected by the Raman scattering experiment have the same frequencies as the LO phonons, although the system has the center of symmetry in the average structure. It is suggested that the coherence length of the charge density wave shorter than the incident laser wavelength 5145Å gets shorter with increasing the Rb concentration.

  8. Thickness Dependence of Infrared Reflection Absorption in Vacuum-Deposited Thin Film of Polyvinylidene Fluoride

    NASA Astrophysics Data System (ADS)

    Maki, Kunisuke; Terashima, Hidenobu; Kikuma, Kazuhiro

    1990-06-01

    Reflection absorption intensities for p-polarized infrared rays are shown as a function of thickness (d) of vacuum-deposited films of polyvinylidene fluoride (PVDF), which were deposited on Ag-covered mica substrates held at 25°C. Each absorption due to α-type polycrystalline film at 1412, 1215, 1185, 1150, 1070, 875 and 615 cm-1 increases linearly with increasing d. Some structural relaxation during the growth of PVDF film is discussed for interpretation of the result that absorption at 1215, 1185 and 875 cm-1 is not observed and the peak height at 882 cm-1 is seen clearly for films at d<15 nm.

  9. Preliminary method for direct quantification of colistin methanesulfonate by attenuated total reflectance Fourier transform infrared spectroscopy.

    PubMed

    Niece, Krista L; Akers, Kevin S

    2015-09-01

    Colistin use has increased in response to the advent of infections caused by multidrug-resistant organisms. It is administered parenterally as an inactive prodrug, colistin methanesulfonate (CMS). Various formulations of CMS and labeling conventions can lead to confusion about colistin dosing, and questions remain about the pharmacokinetics of CMS. Since CMS does not have strong UV absorbance, current methods employ a laborious process of chemical conversion to colistin followed by precolumn derivatization to detect formed colistin by high-performance liquid chromatography. Here, we report a method for direct quantification of colistin methanesulfonate by attenuated total reflectance Fourier transform infrared spectroscopy (ATR FTIR).

  10. Imaging the Material Properties of Bone Specimens Using Reflection-Based Infrared Microspectroscopy

    SciTech Connect

    Acerbo A. S.; Carr, G.L.; Judex, S.; Miller, L.M.

    2012-03-13

    Fourier transform infrared microspectroscopy (FTIRM) is a widely used method for mapping the material properties of bone and other mineralized tissues, including mineralization, crystallinity, carbonate substitution, and collagen cross-linking. This technique is traditionally performed in a transmission-based geometry, which requires the preparation of plastic-embedded thin sections, limiting its functionality. Here, we theoretically and empirically demonstrate the development of reflection-based FTIRM as an alternative to the widely adopted transmission-based FTIRM, which reduces specimen preparation time and broadens the range of specimens that can be imaged. In this study, mature mouse femurs were plastic-embedded and longitudinal sections were cut at a thickness of 4 {micro}m for transmission-based FTIRM measurements. The remaining bone blocks were polished for specular reflectance-based FTIRM measurements on regions immediately adjacent to the transmission sections. Kramers-Kronig analysis of the reflectance data yielded the dielectric response from which the absorption coefficients were directly determined. The reflectance-derived absorbance was validated empirically using the transmission spectra from the thin sections. The spectral assignments for mineralization, carbonate substitution, and collagen cross-linking were indistinguishable in transmission and reflection geometries, while the stoichiometric/nonstoichiometric apatite crystallinity parameter shifted from 1032/1021 cm{sup -1} in transmission-based to 1035/1025 cm{sup -1} in reflection-based data. This theoretical demonstration and empirical validation of reflection-based FTIRM eliminates the need for thin sections of bone and more readily facilitates direct correlations with other methods such as nanoindentation and quantitative backscatter electron imaging (qBSE) from the same specimen. It provides a unique framework for correlating bone's material and mechanical properties.

  11. Imaging the Material Properties of Bone Specimens using Reflection-Based Infrared Microspectroscopy

    PubMed Central

    Acerbo, Alvin S.; Carr, G. Lawrence; Judex, Stefan; Miller, Lisa M.

    2012-01-01

    Fourier Transform InfraRed Microspectroscopy (FTIRM) is a widely used method for mapping the material properties of bone and other mineralized tissues, including mineralization, crystallinity, carbonate substitution, and collagen cross-linking. This technique is traditionally performed in a transmission-based geometry, which requires the preparation of plastic-embedded thin sections, limiting its functionality. Here, we theoretically and empirically demonstrate the development of reflection-based FTIRM as an alternative to the widely adopted transmission-based FTIRM, which reduces specimen preparation time and broadens the range of specimens that can be imaged. In this study, mature mouse femurs were plastic-embedded and longitudinal sections were cut at a thickness of 4 μm for transmission-based FTIRM measurements. The remaining bone blocks were polished for specular reflectance-based FTIRM measurements on regions immediately adjacent to the transmission sections. Kramers-Kronig analysis of the reflectance data yielded the dielectric response from which the absorption coefficients were directly determined. The reflectance-derived absorbance was validated empirically using the transmission spectra from the thin sections. The spectral assignments for mineralization, carbonate substitution, and collagen cross-linking were indistinguishable in transmission and reflection geometries, while the stoichiometric/non-stoichiometric apatite crystallinity parameter shifted from 1032 / 1021 cm−1 in transmission-based to 1035 / 1025 cm−1 in reflection-based data. This theoretical demonstration and empirical validation of reflection-based FTIRM eliminates the need for thin sections of bone and more readily facilitates direct correlations with other methods such nanoindentation and quantitative backscatter electron imaging (qBSE) from the same specimen. It provides a unique framework for correlating bone’s material and mechanical properties. PMID:22455306

  12. Modelling of sensory and instrumental texture parameters in processed cheese by near infrared reflectance spectroscopy.

    PubMed

    Blazquez, Carmen; Downey, Gerard; O'Callaghan, Donal; Howard, Vincent; Delahunty, Conor; Sheehan, Elizabeth; Everard, Colm; O'Donnell, Colm P

    2006-02-01

    This study investigated the application of near infrared (NIR) reflectance spectroscopy to the measurement of texture (sensory and instrumental) in experimental processed cheese samples. Spectra (750 to 2498 nm) of cheeses were recorded after 2 and 4 weeks storage at 4 degrees C. Trained assessors evaluated 9 sensory properties, a texture profile analyser (TPA) was used to record 5 instrumental parameters and cheese 'meltability' was measured by computer vision. Predictive models for sensory and instrumental texture parameters were developed using partial least squares regression on raw or pre-treated spectral data. Sensory attributes and instrumental texture measurements were modelled with sufficient accuracy to recommend the use of NIR reflectance spectroscopy for routine quality assessment of processed cheese. PMID:16433962

  13. Sediment mineralogy based on visible and near-infrared reflectance spectroscopy

    USGS Publications Warehouse

    Jarrard, R.D.; Vanden Berg, M.D.; ,

    2006-01-01

    Visible and near-infrared spectroscopy (VNIS) can be used to measure reflectance spectra (wavelength 350-2500 nm) for sediment cores and samples. A local ground-truth calibration of spectral features to mineral percentages is calculated by measuring reflectance spectra for a suite of samples of known mineralogy. This approach has been tested on powders, core plugs and split cores, and we conclude that it works well on all three, unless pore water is present. Initial VNIS studies have concentrated on determination of relative proportions of carbonate, opal, smectite and illite in equatorial Pacific sediments. Shipboard VNIS-based determination of these four components was demonstrated on Ocean Drilling Program Leg 199. ?? The Geological Society of London 2006.

  14. Bidirectional reflectance distribution function of the Infrared Astronomical Satellite solar-shield material

    NASA Astrophysics Data System (ADS)

    Hubbs, J. E.; Nofziger, M. J.; Bartell, F. O.; Wolfe, W. L.; Brooks, L. D.

    1982-09-01

    The Infrared Astronomical Satellite (IRAS) telescope has an outer shield on it which is used to reduce the amount of thermal radiation that enters the telescope. The shield forms the first part of the baffle structure which reduces the photon incidence on the focal plane. It was, therefore, necessary to model this structure for scattering, and a required input for such modeling is the scattering characteristic of this surface. Attention is given to the measurement of the bidirectional reflectance distribution function (BRDF), the reflected radiance divided by the incident irradiance at 10.6 micrometers, 118 micrometers, and at several angles of incidence. Visual observation of the gold sample shows that there are striations which line up in a single direction. The data were, therefore, taken with the sample oriented in each of two directions.

  15. Method of Detecting Coliform Bacteria and Escherichia Coli Bacteria from Reflected Light

    NASA Technical Reports Server (NTRS)

    Vincent, Robert (Inventor)

    2013-01-01

    The present invention relates to a method of detecting coliform bacteria in water from reflected light and a method of detecting Eschericha Coli bacteria in water from reflected light, and also includes devices for the measurement, calculation and transmission of data relating to that method.

  16. Electro-optic study of PZT ferroelectric ceramics using modulation of reflected light

    NASA Astrophysics Data System (ADS)

    Kniazkov, A. V.

    2016-04-01

    Electro-optic coefficients of variations in the refractive index of PZT and PLZT ceramic materials induced by ac electric field are estimated using modulation of reflected light. The electro-optic coefficients of PLZT ceramics measured with the aid of conventional birefringence using the phase shift of transmitted radiation and the proposed method of birefringence using the modulation of reflected light are compared.

  17. An Overview of Ultraviolet Through Infrared Reflectance Spectroscopic Observations of Mercury During the First MESSENGER Flyby

    NASA Astrophysics Data System (ADS)

    Izenberg, N. R.; McClintock, W. E.; Holsclaw, G. M.; Robinson, M. S.; Blewett, D. T.; Domingue, D. L.; Head, J. W.; Jensen, E. A.; Kochte, M. C.; Lankton, M. R.; Murchie, S. L.; Sprague, A. L.; Vilas, F.; Solomon, S. C.

    2008-05-01

    During the first MESSENGER flyby of Mercury on January 14, 2008, the Mercury Atmospheric and Surface Composition Spectrometer (MASCS) measured reflectance spectra from Mercury's surface over the wavelength range 220-1450 nm. These are the first high-spatial-resolution (<10 km) spectra at any wavelength and the first reported ultraviolet (UV, wavelength < 360 nm) observations of the surface. MASCS observed the sunlit surface for approximately 14 minutes after closest approach, acquiring over 650 spectra with the Visible and Infrared Spectrograph (VIRS) detectors of MASCS sensitive to wavelengths of 350-1450 nm. MASCS also obtained just under four grating scans in the middle ultraviolet (220-320 nm) using MASCS's Ultraviolet and Visible Spectrometer (UVVS) component. Most of the near-equatorial ground track of the observation covered terrain in the previously unseen hemisphere of Mercury but also crossed into the hemisphere viewed by Mariner 10 south of Mozart crater and in Tir Planitia. Ground-based observations of Mercury reveal a surface with a red, nearly featureless spectrum in the visible and near-infrared (wavelengths greater than ~ 500 nm) that has been interpreted as evidence for a largely iron-poor feldspathic composition. Initial analyses of VIRS spectra also show strongly red-sloped, near featureless spectra, appearing to support contentions of low iron abundance in surface materials. However, interpretation of Mercury's spectral reflectance is complicated by our lack of knowledge about the effects on its surface materials of space weathering, which both suppresses the strength of spectral absorption features and reddens the spectrum. Brightness variations and absorption bands in ultraviolet reflectance may help determine both the nature and extent of processes that modify observed reflectance at longer wavelengths. MASCS surface observation data demonstrate spectral variations across the Mercury surface that can be related to previous telescopic

  18. Light-Harvesting Photosensitizers for Photodynamic Inactivation of Bacteria under Both Visible and Near-Infrared Excitations.

    PubMed

    Hu, Bo; Cao, Xian; Ahmadov, Ms Tevhide Ozkaya; Ding, Rui; Tang, Hong; Zhang, Peng

    2016-04-01

    We report a hybrid singlet oxygen production system, where strong resonance coupling between plasmonic nanoparticles and photosensitizing molecules results in exceptionally high singlet oxygen production under both visible light and near-infrared light excitation, even for the photosensitizing molecules without near-infrared absorption. The light-harvesting property of the plasmon-photosensitizer hybrids leads to an enhanced, broad-spectrum photodynamic inactivation of bacteria under a wide range of excitations, including that with near-infrared light.

  19. Superfast Near-Infrared Light-Driven Polymer Multilayer Rockets.

    PubMed

    Wu, Zhiguang; Si, Tieyan; Gao, Wei; Lin, Xiankun; Wang, Joseph; He, Qiang

    2016-02-01

    A gold nanoshell-functionalized polymer multilayer nanorocket performs self-propulsion upon the irradiation with NIR light in the absence of chemical fuel. Theoretical simulations reveal that the NIR light-triggered self-thermophoresis drives the propulsion of the nanorocket. The nanorocket also displays -efficient NIR light-triggered propulsion in -biofluids and thus holds considerable promise for various potential biomedical applications. PMID:26690728

  20. Engineering light-emitting diode surgical light for near-infrared fluorescence image-guided surgical systems

    PubMed Central

    Zhu, Nan; Mondal, Suman; Gao, Shengkui; Achilefu, Samuel; Gruev, Viktor; Liang, Rongguang

    2014-01-01

    Abstract. The near-infrared (NIR) fluorescence signal in the 700 to 900 nm from molecular probes used in fluorescence image-guided surgery (FIGS) is usually weak compared to the NIR component from white light-emitting diode surgical light, which is typically switched off during FIGS to enhance the molecular fluorescence contrast of the image. We propose a simple solution to this critical issue in FIGS by removing NIR light from surgical light with a low cost commercial 3M cool mirror film 330. PMID:25057962

  1. Engineering light-emitting diode surgical light for near-infrared fluorescence image-guided surgical systems.

    PubMed

    Zhu, Nan; Mondal, Suman; Gao, Shengkui; Achilefu, Samuel; Gruev, Viktor; Liang, Rongguang

    2014-01-01

    The near-infrared (NIR) fluorescence signal in the 700 to 900 nm from molecular probes used in fluorescence image-guided surgery (FIGS) is usually weak compared to the NIR component from white light-emitting diode surgical light, which is typically switched off during FIGS to enhance the molecular fluorescence contrast of the image. We propose a simple solution to this critical issue in FIGS by removing NIR light from surgical light with a low cost commercial 3M cool mirror film 330.

  2. Infrared phase-conjugate reflection by hot electron-induced optical nonlinearity in n-Ge

    NASA Astrophysics Data System (ADS)

    Poroshin, V. N.; Vasetskii, V. M.

    We have studied backward-degenerate four-wave mixing at CO2 laser wavelengths in n-type Ge having a free electron density of N=5×1016 cm-3. The phase conjugation due to the redistribution of free electrons between the equivalent valleys was observed. The effect occurs only when the electric field E of the light wave is aligned nonsymmetrically relative to the long axes of the valleys in the crystal, and is related to carrier heating by the infrared radiation.

  3. Infrared Studies of the Reflective Properties of Solar Cells and the HS376 Spacecraft

    NASA Technical Reports Server (NTRS)

    Frith, James; Reyes, Jacqueline; Cowardin, Heather; Anz-Meador, Phillip; Buckalew, Brent; Lederer, Susan

    2016-01-01

    In 2015, a selection of HS-376 buses were observed photometrically with the United Kingdom Infrared Telescope (UKIRT) to explore relationships between time-on-orbit and Near Infrared (NIR) color. These buses were chosen because of their relatively simple shape, for the abundance of similar observable targets, and their surface material being primarily covered by solar cells. While the HS-376 spacecraft were all very similar in design, differences in the specific solar cells used in the construction of each model proved to be an unconstrained variable that could affect the observed reflective properties. In 2016, samples of the solar cells used on various models of HS-376 spacecraft were obtained from Boeing and were analyzed in the Optical Measurements Center at the Johnson Space Center using a visible-near infrared field spectrometer. The laboratory-based spectra are convolved to match the photometric bands previously obtained using UKIRT and compared with the on-orbit photometry. The results and future work are discussed here.

  4. A transmitting and reflecting diffuser for ultraviolet light

    NASA Technical Reports Server (NTRS)

    Keafer, L. S., Jr.; Burcher, E. E.; Kopia, L. P.

    1972-01-01

    Fabrication of ultraviolet radiation diffusing layer in configuration that uses ultraviolet properties of fused silica condensate is discussed. Construction and operation of the device are described. Diagram of reflecting diffuser to show construction and method of operation is included.

  5. Combination of infrared thermography and reflectance spectroscopy for precise classification of hair follicle stage

    NASA Astrophysics Data System (ADS)

    Wang, Jianru; Guan, Yue; Liu, Caihua; Zhu, Dan

    2015-03-01

    Hair follicles enjoy continual cycle of anagen, catagen and telogen all life. They not only provide a unique opportunity to study the physiological mechanism of organ regeneration, but also benefit to guide the treatment of organ repair in regenerative medicine. Usually, the histological examination as a gold standard has been applied to determine the stage of hair follicle cycle, but noninvasive classification of hair cycle in vivo remains unsolved. In this study, the thermal infrared imager was applied to measure the temperature change of mouse dorsal skin with hair follicle cycle, and the change of diffuse reflectance was monitored by the optical fiber spectrometer. Histological examination was used to verify the hair follicle stages. The results indicated that the skin temperature increased at the beginning of anagen. After having stayed a high value for several days, the temperature began to decrease. At the same time, the skin diffuse reflectance decreased until the end of this period. Then the temperature increased gradually after slightly decreased when the hair follicle entered into catagen stage, and the diffuse reflectance increased at this time. In telogen, both the temperature and the diffuse reflectance went back to a steady state all the time. Sub-stages of hair follicle cycle could be distinguished based on the joint curves. This study provided a new method to noninvasively recognize the hair follicle stage, and should be valuable for the basic and therapeutic investigations on hair regeneration.

  6. Infrared reflectance spectroscopy as a characterization probe for polymer surfaces and interfaces

    NASA Astrophysics Data System (ADS)

    Riou, Sophie Annick

    1998-12-01

    Only recently has external reflectance infrared spectroscopy been used to acquire structural information at the molecular level at air-liquid interfaces, and particularly to characterize in situ molecular chains adsorbed at the air-water interface. This technique has been applied for the determination of chain orientation, chain conformation and packing density of small molecules such as phospholipids, fatty acids and fatty alcohols on the surface of water, and more recently of macromolecular systems. Vibrational spectroscopy, a nondestructive technique, is especially successful in the determination of the conformational order or disorder of alkyl chains (e.g. trans/gauche ratio) as well as in the evaluation of coil, helical or extended conformations in poly(amino acids). In this thesis work, the construction of a microcomputer controlled Langmuir trough optically coupled to a FT-IR instrument has allowed the direct investigation of molecular films spread at air-liquid interfaces. Order-disorder transitions and relaxation behaviors in vinyl comb-like polymeric Langmuir films have been examined using simultaneously external reflection infrared spectroscopy and surface tensiometry. The structures of several poly(amino acid) films have also been studied as a function of surface packing density at the air-water interface.

  7. Reflective and photoacoustic infrared spectroscopic techniques in assessment of binding media in paintings

    NASA Astrophysics Data System (ADS)

    Łojewski, Tomasz; Bagniuk, Jacek; Kołodziej, Andrzej; Łojewska, Joanna

    2011-11-01

    This study proposes a method to estimate the lipid content in binding media in paintings that can be used at any laboratory equipped with an infrared spectrometer. The lipid content estimator, termed greasiness index (GI), is defined as a ratio of lipid ν(C=O) and protein amide I bands at 1743 and 1635 cm-1, respectively. Three Fourier transform infrared (FTIR) sampling techniques were evaluated for GI determination: reflective attenuated total reflection—ATR, specular reflection microscopy— μSR and photoacoustic—PAS. A set of model painting samples containing three tempera binding media (casein, egg, egg + oil), seven pigments and one varnish type were used in the study. Multivariate analysis was used to evaluate the resulting data. A good reproducibility of GI was obtained by ATR and PAS but not with μSR. The discriminative power of the technique is higher for unvarnished samples, but, generally, the GI estimator can be used for the categorisation of binding media in large populations of painting samples analysed with the same FTIR technique (sampling technique, detection, etc.).

  8. Classification of the waxy condition of durum wheat by near infrared reflectance spectroscopy using wavelets and a genetic algorithm

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Near infrared (NIR) reflectance spectroscopy has been applied to the problem of differentiating four genotypes of durum wheat: ‘waxy’, wx-A1 null, wx-B1 null and wild type. The test data consisted of 95 NIR reflectance spectra of wheat samples obtained from a USDA-ARS wheat breeding program. A two...

  9. Hygrothermal degradation of 3-glycidoxypropyltrimethoxysilane films studied by neutron and X-ray reflectivity and attenuated total reflection infrared spectroscopy.

    SciTech Connect

    Tallant, David Robert; Garcia, Manuel Joseph; Majewski, Jaroslaw; Kent, Michael Stuart; Yim, Hyun

    2005-05-01

    Thin films of organosilanes have great technological importance in the areas of adhesion promotion, durability, and corrosion resistance. However, it is well-known that water can degrade organosilane films, particularly at elevated temperatures. In this work, X-ray and neutron reflectivity (XR and NR) were combined with attenuated total reflection infrared (ATR-IR) spectroscopy to study the chemical and structural changes within thin films of (3-glycidoxypropyl)trimethoxysilane (GPS) after exposure for various periods of time to air saturated with either D{sub 2}O or H{sub 2}O at 80 C. For NR and XR, ultrathin ({approx}100 {angstrom}) films were prepared by spin-coating. Both D{sub 2}O and H{sub 2}O provide neutron scattering contrast with GPS. Variations in the neutron scattering length density (SLD) profiles (a function of mass density and atomic composition) with conditioning time were measured after drying the samples out and also swelled with H{sub 2}O or D{sub 2}O vapor at room temperature. For samples that were dried out prior to measurement, little or no change was observed for H{sub 2}O conditioning up to 3.5 days, but large changes were observed after 30 days of conditioning. The range of conditioning time for this structural change was narrowed to between 4 and 10 days with XR. The SLD profiles indicated that the top portion of the GPS film was transformed into a thick low-density layer after conditioning, but the bottom portion showed little structural change. A previous NR study of as-prepared GPS films involving swelling with deuterated nitrobenzene showed that the central portion of the film has much lower cross-link density than the region nearest the substrate. The present data show that the central portion also swells to a much greater extent with water and hydrolyzes more rapidly. The chemical degradation mechanism was identified by IR as hydrolysis of siloxane bonds. For ATR-IR, GPS films were prepared by dip-coating, which resulted in a greater

  10. Improved near-infrared ocean reflectance correction algorithm for satellite ocean color data processing.

    PubMed

    Jiang, Lide; Wang, Menghua

    2014-09-01

    A new approach for the near-infrared (NIR) ocean reflectance correction in atmospheric correction for satellite ocean color data processing in coastal and inland waters is proposed, which combines the advantages of the three existing NIR ocean reflectance correction algorithms, i.e., Bailey et al. (2010) [Opt. Express18, 7521 (2010)Appl. Opt.39, 897 (2000)Opt. Express20, 741 (2012)], and is named BMW. The normalized water-leaving radiance spectra nLw(λ) obtained from this new NIR-based atmospheric correction approach are evaluated against those obtained from the shortwave infrared (SWIR)-based atmospheric correction algorithm, as well as those from some existing NIR atmospheric correction algorithms based on several case studies. The scenes selected for case studies are obtained from two different satellite ocean color sensors, i.e., the Moderate Resolution Imaging Spectroradiometer (MODIS) on the satellite Aqua and the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi National Polar-orbiting Partnership (SNPP), with an emphasis on several turbid water regions in the world. The new approach has shown to produce nLw(λ) spectra most consistent with the SWIR results among all NIR algorithms. Furthermore, validations against the in situ measurements also show that in less turbid water regions the new approach produces reasonable and similar results comparable to the current operational algorithm. In addition, by combining the new NIR atmospheric correction with the SWIR-based approach, the new NIR-SWIR atmospheric correction can produce further improved ocean color products. The new NIR atmospheric correction can be implemented in a global operational satellite ocean color data processing system.

  11. Improved near-infrared ocean reflectance correction algorithm for satellite ocean color data processing.

    PubMed

    Jiang, Lide; Wang, Menghua

    2014-09-01

    A new approach for the near-infrared (NIR) ocean reflectance correction in atmospheric correction for satellite ocean color data processing in coastal and inland waters is proposed, which combines the advantages of the three existing NIR ocean reflectance correction algorithms, i.e., Bailey et al. (2010) [Opt. Express18, 7521 (2010)Appl. Opt.39, 897 (2000)Opt. Express20, 741 (2012)], and is named BMW. The normalized water-leaving radiance spectra nLw(λ) obtained from this new NIR-based atmospheric correction approach are evaluated against those obtained from the shortwave infrared (SWIR)-based atmospheric correction algorithm, as well as those from some existing NIR atmospheric correction algorithms based on several case studies. The scenes selected for case studies are obtained from two different satellite ocean color sensors, i.e., the Moderate Resolution Imaging Spectroradiometer (MODIS) on the satellite Aqua and the Visible Infrared Imaging Radiometer Suite (VIIRS) on the Suomi National Polar-orbiting Partnership (SNPP), with an emphasis on several turbid water regions in the world. The new approach has shown to produce nLw(λ) spectra most consistent with the SWIR results among all NIR algorithms. Furthermore, validations against the in situ measurements also show that in less turbid water regions the new approach produces reasonable and similar results comparable to the current operational algorithm. In addition, by combining the new NIR atmospheric correction with the SWIR-based approach, the new NIR-SWIR atmospheric correction can produce further improved ocean color products. The new NIR atmospheric correction can be implemented in a global operational satellite ocean color data processing system. PMID:25321543

  12. Diagnosis of the phase function of random media from light reflectance

    NASA Astrophysics Data System (ADS)

    Xu, Min

    2016-03-01

    Light reflectance has been widely used to diagnose random media in both in situ and in vivo applications. The quantification of the phase function of the medium from reflectance measurements, however, remains elusive due to the lack of an explicit connection between the light reflectance profile and the phase function. Here we first present an analytical model for reflectance of scattered light at an arbitrary source-detector separation by forward-peaked scattering media such as biological tissue and cells. The model incorporates the improved small-angle scattering approximation (SAA) to radiative transfer for sub-diffusive light reflectance and expresses the dependence of the light reflectance on the phase function of the scattering medium in a closed form. A spreading length scale, lΘ, is found to characterise subdiffusive light reflectance at the high spatial frequency (close separation) limit. After validation by Monte Carlo simulations, we then demonstrate the application of the model in accurate determination of the complete set of optical properties and the phase function of a turbid medium from the profile of subdiffusive and diffusive light reflectance.

  13. Diagnosis of the phase function of random media from light reflectance

    PubMed Central

    Xu, Min

    2016-01-01

    Light reflectance has been widely used to diagnose random media in both in situ and in vivo applications. The quantification of the phase function of the medium from reflectance measurements, however, remains elusive due to the lack of an explicit connection between the light reflectance profile and the phase function. Here we first present an analytical model for reflectance of scattered light at an arbitrary source-detector separation by forward-peaked scattering media such as biological tissue and cells. The model incorporates the improved small-angle scattering approximation (SAA) to radiative transfer for sub-diffusive light reflectance and expresses the dependence of the light reflectance on the phase function of the scattering medium in a closed form. A spreading length scale, lΘ, is found to characterise subdiffusive light reflectance at the high spatial frequency (close separation) limit. After validation by Monte Carlo simulations, we then demonstrate the application of the model in accurate determination of the complete set of optical properties and the phase function of a turbid medium from the profile of subdiffusive and diffusive light reflectance. PMID:26935167

  14. A Near-Infrared Spectrometer to Measure Zodiacal Light Absorption Spectrum

    NASA Technical Reports Server (NTRS)

    Kutyrev, A. S.; Arendt, R.; Dwek, E.; Kimble, R.; Moseley, S. H.; Rapchun, D.; Silverberg, R. F.

    2010-01-01

    We have developed a high throughput infrared spectrometer for zodiacal light fraunhofer lines measurements. The instrument is based on a cryogenic dual silicon Fabry-Perot etalon which is designed to achieve high signal to noise Fraunhofer line profile measurements. Very large aperture silicon Fabry-Perot etalons and fast camera optics make these measurements possible. The results of the absorption line profile measurements will provide a model free measure of the zodiacal Light intensity in the near infrared. The knowledge of the zodiacal light brightness is crucial for accurate subtraction of zodiacal light foreground for accurate measure of the extragalactic background light after the subtraction of zodiacal light foreground. We present the final design of the instrument and the first results of its performance.

  15. Assessment of Drowsiness Based on Ocular Parameters Detected by Infrared Reflectance Oculography

    PubMed Central

    Anderson, Clare; Chang, Anne-Marie; Sullivan, Jason P.; Ronda, Joseph M.; Czeisler, Charles A.

    2013-01-01

    Study Objectives: Numerous ocular parameters have been proposed as reliable physiological markers of drowsiness. A device that measures many of these parameters and then combines them into a single metric (the Johns Drowsiness Scale [JDS]) is being used commercially to assess drowsiness in professional drivers. Here, we examine how these parameters reflect changes in drowsiness, and how they relate to objective and subjective indices of the drowsy state in a controlled laboratory setting. Design: A within subject prospective study. Participants: 29 healthy adults (18 males; mean age 23.3 ± 4.6 years; range 18-34 years) Interventions: N/A. Measurements and Results: Over the course of a 30-h extended wake vigil under constant routine (CR) conditions, participants were monitored using infrared reflectance oculography (Optalert) and completed bi-hourly neurobehavioral tests, including the Karolinska Sleepiness Scale (KSS) and Psychomotor Vigilance Task (PVT). Ocular-defined increases in drowsiness were evident with extended time awake and during the biological night for all ocular parameters; JDS being the most sensitive marker of drowsiness induced by sleep regulatory processes (p < 0.0001). In addition, the associations between JDS in the preceding 10-min period and subsequent PVT lapses and KSS were stronger (AUC 0.74/0.80, respectively) than any other ocular metric, such that PVT lapses, mean response time (RT), and KSS increased in a dose-response manner as a function of prior JDS score (p < 0.0001). Conclusions: Ocular parameters captured by infrared reflectance oculography detected fluctuations in drowsiness due to time awake and during the biological night. The JDS outcome was the strongest predictor of drowsiness among those tested, and showed a clear association to objective and subjective measures of drowsiness. Our findings indicate this real-time objective drowsiness monitoring system is an effective tool for monitoring changes in alertness and

  16. Mineralogical and spectroscopic investigation of enstatite chondrites by X-ray diffraction and infrared reflectance spectroscopy

    NASA Astrophysics Data System (ADS)

    Izawa, M. R.; King, P. L.; Flemming, R. L.; Peterson, R. C.; McCausland, P. J.

    2009-05-01

    Reflectance spectroscopy of well-characterized meteorites provides an important means of linking meteorites to potential parent objects; an important objective in meteoritics research. There is a lack of such sample- correlated spectroscopic and mineralogical data sets in the literature to date. In an effort to improve this situation, the bulk mineralogy and infrared reflectance spectra of 13 enstatite chondrite meteorite finds, spanning the full range of textural alteration grades in both EL and EH classes have been investigated, including eleven recovered from the Antarctic and one from Northwest Africa. Rietveld refinement of high- resolution powder X-ray diffraction (XRD) data was used to identify the major mineral phases and quantify their modal abundances. The mineralogy and modes agree well with those of well-documented enstatite chondrites. Terrestrial weathering products such as Fe-oxyhydroxides, gypsum, and carbonates also occur in most of the meteorites from Antarctica. The mineral abundances determined via Rietveld refinement have been used to calculate model grain densities for each meteorite (i.e. density of the solid phases). Bulk magnetic susceptibility measurements combined with modal mineralogy reveal that as terrestrial weathering increases, both grain density and bulk susceptibility decrease. Sample-correlated thermal infrared (400-4500 cm-1, 2-25 μm) biconical (Diffuse) Reflectance Infrared Fourier Transform Spectroscopy data were collected for each meteorite to facilitate comparison with remote sensing data. The meteorite spectra are dominated by features corresponding to enstatite. Terrestrial weathering manifests itself as a broad, asymmetric H2O band centered near ~3400 cm-1, analogous to the "3 μm water of hydration feature" recognized in asteroid spectra, particularly from the enigmatic W-type asteroids. Additional sharp features superimposed on this band, as well as the sharpness of an asymmetric feature related to bound molecular

  17. Infrared microscope inspection apparatus

    DOEpatents

    Forman, Steven E.; Caunt, James W.

    1985-02-26

    Apparatus and system for inspecting infrared transparents, such as an array of photovoltaic modules containing silicon solar cells, includes an infrared microscope, at least three sources of infrared light placed around and having their axes intersect the center of the object field and means for sending the reflected light through the microscope. The apparatus is adapted to be mounted on an X-Y translator positioned adjacent the object surface.

  18. Infrared microscope inspection apparatus

    DOEpatents

    Forman, S.E.; Caunt, J.W.

    1985-02-26

    Apparatus and system for inspecting infrared transparents, such as an array of photovoltaic modules containing silicon solar cells, includes an infrared microscope, at least three sources of infrared light placed around and having their axes intersect the center of the object field and means for sending the reflected light through the microscope. The apparatus is adapted to be mounted on an X-Y translator positioned adjacent the object surface. 4 figs.

  19. Deep tissue targeted near-infrared optogenetic stimulation using fully implantable upconverting light bulbs.

    PubMed

    Chamanzar, Maysamreza; Garfield, David J; Iafrati, Jillian; Sohal, Vikaas; Chan, Emory; Cohen, Bruce; Schuck, P James; Maharbiz, Michel M

    2015-08-01

    We demonstrate for the first time, the possibility of targeted optogenetic stimulation of neurons deep into brain tissue (>2 mm) in a minimally-invasive way by sending near-infrared light through tissue to excite passive lanthanide-doped blue-emitting upconverting nanocrystals (UCNPs) encapsulated in Parylene C microstructure light bulbs that emit visible (blue) light and locally excite opsins with high spatial resolution. PMID:26736388

  20. Nondestructive inspection of organic films on sandblasted metals using diffuse reflectance infrared spectroscopy

    SciTech Connect

    Powell, G.L.; Cox, R.L.; Barber, T.E.; Neu, J.T.

    1996-07-08

    Diffuse reflectance infrared spectroscopy is a very useful tool for the determination of surface contamination and characterization of films in manufacturing applications. Spectral data from the surfaces of a host of practical materials may be obtained with sufficient insensitivity to characterize relatively thick films, such as paint, and the potential exists to detect very thin films, such as trace oil contamination on metals. The SOC 400 Surface Inspection Machine/InfraRed (SIMIR) has been developed as a nondestructive inspection tool to exploit this potential in practical situations. This SIMIR is a complete and ruggidized Fourier transform infrared spectrometer with a very efficient and robust barrel ellipse diffuse reflectance optical collection system and operating software system. The SIMIR weighs less than 8 Kg, occupies less than 14 L volume, and may be manipulated into any orientation during operation. The surface to be inspected is placed at the focal point of the SIMIR by manipulating the SIMIR or the surface. The SIMIR may or may not contact the surface being inspected. For flat or convex items, there are no size limits to items being inspected. For concave surfaces, the SIMIR geometry limits the surface to those having a radius of curvature greater than 0.2 m. For highly reflective metal surfaces, the SIMIR has a noise level approaching 1 {times} 10{sup {minus}4} absorbance units, which is sufficient for detecting nanometer thick organic film residues on metals. The use of this nondestructive inspection tool is demonstrated by the spatial mapping of organic stains on sand blasted metals in which organic stains such as silicone oils, mineral oils, and triglycerides are identified both qualitatively and quantitatively over the surface of the metal specimen.

  1. Temperature dependence of far-infrared difference reflectivity of YBa2Cu3O7-y

    NASA Astrophysics Data System (ADS)

    Krenn, H.; Bauer, G.; Vogl, G.; Strasser, G.; Gornik, E.

    1989-04-01

    Far-infrared difference reflectivity spectra (50-450 cm-1) below, across and above the transition temperature on polycrystalline single-phase YBa2Cu3O7-y samples were measured. The data are compared with model fits using the explicit temperature dependence of the Mattis-Bardeen conductivity, an effective-medium approach and temperature-dependent phonon oscillator parameters and alternatively a plasma model. For the plasma model we alternatively use a generalized Drude-like expression with a frequency-dependent damping after Thomas et al. [Phys. Rev. B 36, 846 (1987)] or the original model with Orenstein et al. [Phys. Rev. B 36, 729 (1987)] and Sherwin, Richards, and Zettl [Phys. Rev. B 37, 1587 (1988)] with a Drude contribution plus a mid-infrared oscillator, but with constant carrier relaxation rates. The models explain the difference reflectivity data (precision <0.2%) with a fitting accuracy of 1-2 % (Mattis-Bardeen model) or 2-3 % (plasma model) over the full temperature range. In order to investigate their applicability, reflectivity, and conductivity data of a highly oriented YBa2Cu3O7-y sample, as recently published by Bonn et al. [Phys. Rev. Lett. 58, 2249 (1987)], were also fitted with both models. Because of the frequency dependence of the free-carrier damping rates, it was important to fulfill the Kramers-Kronig relations between the real and the imaginary part of the dynamic conductivity in the calculations. For both models the characteristic dependences of the conductivity on frequency and temperature are given. Whereas, naturally, the Mattis-Bardeen model yields a gaplike depression of the conductivity for frequencies below an assumed gap, the plasma model results in somewhat smoother dependences of Re(σ(ω)) and Im(σ(ω)) in the frequency region of interest.

  2. Identification of cattle, llama and horse meat by near infrared reflectance or transflectance spectroscopy.

    PubMed

    Mamani-Linares, L W; Gallo, C; Alomar, D

    2012-02-01

    Visible and near infrared reflectance spectroscopy (VIS-NIRS) was used to discriminate meat and meat juices from three livestock species. In a first trial, samples of Longissimus lumborum muscle, corresponding to beef (31) llamas (21) and horses (27), were homogenised and their spectra collected in reflectance (NIRSystems 6500 scanning monochromator, in the range of 400-2500 nm). In the second trial, samples of meat juice (same muscle) from the same species (20 beef, 19 llama and 19 horse) were scanned in folded transmission (transflectance). Discriminating models (PLS regression) were developed against "dummy" variables, testing different mathematical treatments of the spectra. Best models indentified the species of almost all samples by their meat (reflectance) or meat juice (transflectance) spectra. A few (three of beef and one of llama, for meat samples; one of beef and one of horse, for juice samples) were classified as uncertain. It is concluded that NIRS is an effective tool to recognise meat and meat juice from beef, llama and horses.

  3. Low-temperature and low atmospheric pressure infrared reflectance spectroscopy of Mars soil analog materials

    NASA Technical Reports Server (NTRS)

    Bishop, Janice L.; Pieters, Carle M.

    1995-01-01

    Infrared reflectance spectra of carefully selected Mars soil analog materials have been measured under low atmospheric pressures and temperatures. Chemically altered montmorillonites containing ferrihydrite and hydrated ferric sulfate complexes are examined, as well as synthetic ferrihydrite and a palagonitic soil from Haleakala, Maui. Reflectance spectra of these analog materials exhibit subtle visible to near-infrared features, which are indicative of nanophase ferric oxides or oxyhydroxides and are similar to features observed in the spectra of the bright regions of Mars. Infrared reflectance spectra of these analogs include hydration features due to structural OH, bound H2O, and adsorbed H2O. The spectral character of these hydration features is highly dependent on the sample environment and on the nature of the H2O/OH in the analogs. The behavior of the hydration features near 1.9 micron, 2.2 micron, 2.7 micron, 3 micron, and 6 microns are reported here in spectra measured under a Marslike atmospheric environment. In spectra of these analogs measured under dry Earth atmospheric conditions the 1.9-micron band depth is 8-17%; this band is much stronger under moist conditions. Under Marslike atmospheric conditions the 1.9-micron feature is broad and barely discernible (1-3% band depth) in spectra of the ferrihydrite and palagonitic soil samples. In comparable spectra of the ferric sulfate-bearing montmorillonite the 1.9-micron feature is also broad, but stronger (6% band depth). In the low atmospheric pressure and temperature spectra of the ferrihydrite-bearing montmorillonite this feature is sharper than the other analogs and relatively stronger (6% band depth). Although the intensity of the 3-micron band is weaker in spectra of each of the analogs when measured under Marslike conditions, the 3-micron band remains a dominant feature and is especially broad in spectra of the ferrihydrite and palagonitic soil. The structural OH features observed in these materials

  4. Low-temperature and low atmospheric pressure infrared reflectance spectroscopy of Mars soil analog materials

    NASA Technical Reports Server (NTRS)

    Bishop, Janice L.; Pieters, Carle M.

    1995-01-01

    Infrared reflectance spectra of carefully selected Mars soil analog materials have been measured under low atmospheric pressures and temperatures. Chemically altered montmorillonites containing ferrihydrite and hydrated ferric sulfate complexes are examined, as well as synthetic ferrihydrate and a palagonitic soil from Haleakala, Maui. Reflectance spectra of these analog materials exhibit subtle visible to near-infrared features, which are indicative of nanophase ferric oxides or oxyhydroxides and are similar to features observed in the spectra of the bright regions of Mars. Infrared reflectance spectra of these analogs include hydration features due to structural OH, bound H2O and adsorbed H2O. The spectal character of these hydration features is highly dependent on the sample environment and on the nature of the H2O/OH in the analogs. The behavior of the hydration features near 1.9 micrometers, 2.2 micrometers, 2.7 micrometers, 3 micrometers, and 6 micrometers are reported here in spetra measured under Marslike atmospheric environment. In spectra of these analogs measured under dry Earth atmospheric conditions the 1.9-micrometer band depth is 8-17%; this band is much stonger under moist conditions. Under Marslike atmospheric conditions the 1.9-micrometer feature is broad and barely discernible (1-3% band depth) in spectra of the ferrihydrite and palagonitic soil samples. In comparable spectra of the ferric sulfate-bearing montmorillonite the 1.9-micrometer feature is also broad, but stronger (6% band depth). In the low atmospheric pressure and temperature spectra of the ferrihydrite-bearing montmorillonite this feature is sharper than the other analogs and relatively stronger (6% band depth). Although the intensity of the 3- micrometer band is weaker in spectra of each of the analogs when measured under Marslike conditions, the 3-micromter band remains a dominant feature and is especially broad in spectra of the ferrihydrite and palagonitic soil. The structural

  5. [Fast determination of induction period of motor gasoline using Fourier transform attenuated total reflection infrared spectroscopy].

    PubMed

    Liu, Ya-Fei; Yuan, Hong-Fu; Song, Chun-Feng; Xie, Jin-Chun; Li, Xiao-Yu; Yan, De-Lin

    2014-11-01

    A new method is proposed for the fast determination of the induction period of gasoline using Fourier transform attenuated total reflection infrared spectroscopy (ATR-FTIR). A dedicated analysis system with the function of spectral measurement, data processing, display and storage was designed and integrated using a Fourier transform infrared spectrometer module and chemometric software. The sample presentation accessory designed which has advantages of constant optical path, convenient sample injection and cleaning is composed of a nine times reflection attenuated total reflectance (ATR) crystal of zinc selenide (ZnSe) coated with a diamond film and a stainless steel lid with sealing device. The influence of spectral scanning number and repeated sample loading times on the spectral signal-to-noise ratio was studied. The optimum spectral scanning number is 15 times and the optimum sample loading number is 4 times. Sixty four different gasoline samples were collected from the Beijing-Tianjin area and the induction period values were determined as reference data by standard method GB/T 8018-87. The infrared spectra of these samples were collected in the operating condition mentioned above using the dedicated fast analysis system. Spectra were pretreated using mean centering and 1st derivative to reduce the influence of spectral noise and baseline shift A PLS calibration model for the induction period was established by correlating the known induction period values of the samples with their spectra. The correlation coefficient (R2), standard error of calibration (SEC) and standard error of prediction (SEP) of the model are 0.897, 68.3 and 91.9 minutes, respectively. The relative deviation of the model for gasoline induction period prediction is less than 5%, which meets the requirements of repeatability tolerance in GB method. The new method is simple and fast. It takes no more than 3 minutes to detect one sample. Therefore, the method is feasible for implementing

  6. Using low-energy near infrared light and upconverting nanoparticles to trigger photoreactions within supramolecular assemblies.

    PubMed

    Wu, Tuoqi; Branda, Neil R

    2016-07-01

    This overview highlights how the high-energy ultraviolet or visible light required to drive photochemical reactions can be overcome by integrating the chromophores into supramolecular structures containing upconverting nanoparticles with trivalent lanthanide dopants (such as Tm(3+) and Er(3+)). These nanoparticles are particularly interesting systems because they absorb multiple photons of near infrared light and convert them into higher-energy light which is emitted in the ultraviolet and visible regions of the electromagnetic spectrum. The upconverting nanoparticles effectively act as nanoscopic 'light bulbs', and in this way, less damaging near infrared light can be used to trigger photochemical reactions for use in imaging and small molecule release. Several examples of how this phenomenon is being used in photochemistry will be presented with the focus being on self-assembled supramolecular systems, some of which are being used in cells and small animals. PMID:27270956

  7. Optimum conditions of the distributed bragg reflector in 850-nm GaAs infrared light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Ahn, Su-Chang; Lee, Byung-Teak; An, Won-Chan; Kim, Dae-Kwang; Jang, In-Kyu; So, Jin-Su; Lee, Hyung-Joo

    2016-07-01

    In this paper, a distributed Bragg reflector (DBR) for a bottom reflector in 850-nm GaAs infrared light-emitting diodes (Ir-LEDs) was developed and optimized. At an 850-nm wavelength, markedly improved reflection spectra were observed from DBRs consisting of Al1-xGaxAs/AlxGa1-xAs materials. In addition, the reflection spectra of Al1-xGaxAs/AlxGa1-xAs-based DBRs was found to increase with increasing difference between the high and the low refractive indices. At multiple layers of 10 pairs, maximal reflection spectra having about a 92% reflectivity were obtained from DBRs consisting of GaAs/AlAs. At 20 pairs, however, outstanding reflection spectra having a higher reflectivity and broader width were clearly observed from DBRs consisting of Al0.1Ga0.9As/Al0.9Ga0.1As. Some incident light appears to have been absorbed and confined by the narrow bandgap of the GaAs material used in DBRs consisting of GaAs/AlAs. This fact could be supported by the decrease in the reflectivity of the shorter wavelength region in DBRs consisting of GaAs/AlAs. For this reason, a remarkable output power could be obtained from the 850-nm GaAs Ir-LED chip having a DBR consisting of Al0.1Ga0.9As/Al0.9Ga0.1As.

  8. Propagation of structured light beams after multiple reflections in a spiral phase plate

    NASA Astrophysics Data System (ADS)

    Rumala, Yisa S.

    2015-11-01

    This work presents propagation dynamics of structured light (complex light) containing optical vortices after it has undergone multiple reflections in a spiral phase plate (SPP) device having a nonzero surface reflection. In the calculations, the thick-plate approximation is assumed as it is expected to give a more accurate representation of the standard geometry of an SPP device from a low-surface reflection to a high-surface reflection. Calculations showing the propagation of counter-rotating optical vortices are presented, and the effect of the statistical nature of photons on the observation of the angular intensity modulation of the beam is discussed.

  9. Enhancing the sensitivity of mesoscopic light reflection statistics in weakly disordered media by interface reflections

    NASA Astrophysics Data System (ADS)

    Park, Daniel J.; Pradhan, Prabhakar; Backman, Vadim

    2016-07-01

    Reflection statistics have not been well studied for optical random media whose mean refractive indices do not match with the refractive indices of their surrounding media. Here, we theoretically study how this refractive index mismatch between a one-dimensional (1D) optical sample and its surrounding medium affects the reflection statistics in the weak disorder limit, when the fluctuation part of the refractive index (Δn) is much smaller than the mismatch as well as the mean refractive index of the sample (Δn ≪). In the theoretical derivation, we perform a detailed calculation that results in the analytical forms of the mean and standard deviation (STD) of the reflection coefficient in terms of disorder parameters (<(Δn)2>1 2 and its correlation length lc) in an index mismatched backscattering system. Particularly, the orders of disorder parameters in STD of the reflection coefficient for index mismatched systems are shown to be lower (˜(<Δn2>l c)1/2) than that of the matched systems (˜<Δn2>l c). By comparing STDs of the reflection coefficient values of index matched and mismatched systems, we show that reflection coefficient at the sample boundaries in index mismatched systems can enhance the signal of the STD to the “disorder parameters” of the reflection coefficient. In terms of biophotonics applications, this result can lead to potential techniques that effectively extract the sample disorder parameters by manipulating the index mismatched conditions. Potential applications of the technique for enhancement in sensitivity of cancer detection at the single cell level are also discussed.

  10. Stray light in the Infrared Astronomical Satellite (IRAS)

    NASA Technical Reports Server (NTRS)

    Lange, S. R.; Breault, R. P.

    1980-01-01

    Changes made to the telescope and critical objects considered in modeling these changes into the APART program are described. The optical system was analyzed for scattered light, diffracted then scattered radiation, and thermally emitted radiation. The damaged area of the primary to mirror was also examined. Results are presented in tables and graphs.

  11. Multiple perturbation two-dimensional correlation analysis of cellulose by attenuated total reflection infrared spectroscopy.

    PubMed

    Shinzawa, Hideyuki; Morita, Shin-Ich; Awa, Kimie; Okada, Mariko; Noda, Isao; Ozaki, Yukihiro; Sato, Hidetoshi

    2009-05-01

    An extension of the two-dimensional (2D) correlation analysis scheme for multi-dimensional perturbation is described. A simple computational form is provided to construct synchronous correlation and disrelation maps for the analysis of microscopic imaging data based on two independent perturbation variables. Sets of time-dependent attenuated total reflection infrared (ATR-IR) spectra of water and cellulose mixtures were collected during the evaporation of water from finely ground cellulose. The system exhibits complex behaviors in response to two independent perturbations, i.e., evaporation time and grinding time. Multiple perturbation 2D analysis reveals a specific difference in the rate of evaporation of water molecules when accompanied by crystallinity changes of cellulose. It identifies subtle differences in the volatility of water, which is related to the crystalline structure of cellulose. PMID:19470205

  12. Infrared reflection-absorption spectroscopy: principles and applications to lipid-protein interaction in Langmuir films.

    PubMed

    Mendelsohn, Richard; Mao, Guangru; Flach, Carol R

    2010-04-01

    Infrared reflection-absorption spectroscopy (IRRAS) of lipid/protein monolayer films in situ at the air/water interface provides unique molecular structure and orientation information from the film constituents. The technique is thus well suited for studies of lipid/protein interaction in a physiologically relevant environment. Initially, the nature of the IRRAS experiment is described and the molecular structure information that may be obtained is recapitulated. Subsequently, several types of applications, including the determination of lipid chain conformation and tilt as well as elucidation of protein secondary structure are reviewed. The current article attempts to provide the reader with an understanding of the current capabilities of IRRAS instrumentation and the type of results that have been achieved to date from IRRAS studies of lipids, proteins, and lipid/protein films of progressively increasing complexity. Finally, possible extensions of the technology are briefly considered. PMID:20004639

  13. Detection of whitening agents in illegal cosmetics using attenuated total reflectance-infrared spectroscopy.

    PubMed

    Deconinck, E; Bothy, J L; Desmedt, B; Courselle, P; De Beer, J O

    2014-09-01

    Cosmetic products containing illegal whitening agents are still found on the European market. They represent a considerable risk to public health, since they are often characterised by severe side effects when used chronically. The detection of such products at customs is not always simple, due to misleading packaging and the existence of products containing only legal components. Therefore there is a need for easy to use equipment and techniques to perform an initial screening of samples. The use of attenuated total reflectance-infrared (ATR-IR) spectroscopy, combined with chemometrics, was evaluated for that purpose. It was found that the combination of ATR-IR with the simple chemometric technique k-nearest neighbours gave good results. A model was obtained in which a minimum of illegal samples was categorised as legal. The correctly classified illegal samples could be attributed to the illegal components present.

  14. Detection of whitening agents in illegal cosmetics using attenuated total reflectance-infrared spectroscopy.

    PubMed

    Deconinck, E; Bothy, J L; Desmedt, B; Courselle, P; De Beer, J O

    2014-09-01

    Cosmetic products containing illegal whitening agents are still found on the European market. They represent a considerable risk to public health, since they are often characterised by severe side effects when used chronically. The detection of such products at customs is not always simple, due to misleading packaging and the existence of products containing only legal components. Therefore there is a need for easy to use equipment and techniques to perform an initial screening of samples. The use of attenuated total reflectance-infrared (ATR-IR) spectroscopy, combined with chemometrics, was evaluated for that purpose. It was found that the combination of ATR-IR with the simple chemometric technique k-nearest neighbours gave good results. A model was obtained in which a minimum of illegal samples was categorised as legal. The correctly classified illegal samples could be attributed to the illegal components present. PMID:24927403

  15. Estimation of blood alcohol concentration by horizontal attenuated total reflectance-Fourier transform infrared spectroscopy.

    PubMed

    Sharma, Kakali; Sharma, Shiba P; Lahiri, Sujit C

    2010-06-01

    Numerous methods like distillation followed by iodometric titrations, gas chromatograph (GC)-flame ionization detector, gas chromatograph-mass spectrophotometer, GC-Headspace, Breath analyzer, and biosensors including alcohol dehydrogenase (enzymatic) have been used to determine blood alcohol concentration (BAC). In the present study, horizontal attenuated total reflectance-Fourier transform infrared spectroscopy had been used to determine BAC in whole blood. The asymmetric stretching frequency of C-C-O group of ethanol in water (1,045 cm(-1)) had been used to calculate BAC using Beer's Law. A seven-point calibration curve of ethanol was drawn in the concentration range 24-790 mg dL(-1). The curve showed good linearity over the concentration range used (r(2)=0.999, standard deviation=0.0023). The method is accurate, reproducible, rapid, simple, and nondestructive in nature. PMID:20541351

  16. Fast determination of total ginsenosides content in ginseng powder by near infrared reflectance spectroscopy

    NASA Astrophysics Data System (ADS)

    Chen, Hua-cai; Chen, Xing-dan; Lu, Yong-jun; Cao, Zhi-qiang

    2006-01-01

    Near infrared (NIR) reflectance spectroscopy was used to develop a fast determination method for total ginsenosides in Ginseng (Panax Ginseng) powder. The spectra were analyzed with multiplicative signal correction (MSC) correlation method. The best correlative spectra region with the total ginsenosides content was 1660 nm~1880 nm and 2230nm~2380 nm. The NIR calibration models of ginsenosides were built with multiple linear regression (MLR), principle component regression (PCR) and partial least squares (PLS) regression respectively. The results showed that the calibration model built with PLS combined with MSC and the optimal spectrum region was the best one. The correlation coefficient and the root mean square error of correction validation (RMSEC) of the best calibration model were 0.98 and 0.15% respectively. The optimal spectrum region for calibration was 1204nm~2014nm. The result suggested that using NIR to rapidly determinate the total ginsenosides content in ginseng powder were feasible.

  17. Pectin functionalised by fatty acids: Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopic characterisation

    NASA Astrophysics Data System (ADS)

    Kamnev, Alexander A.; Calce, Enrica; Tarantilis, Petros A.; Tugarova, Anna V.; De Luca, Stefania

    2015-01-01

    Chemically modified pectin derivatives obtained by partial esterification of its hydroxyl moieties with fatty acids (FA; oleic, linoleic and palmitic acids), as well as the initial apple peel pectin were comparatively characterised using diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. Characteristic changes observed in DRIFT spectra in going from pectin to its FA esters are related to the corresponding chemical modifications. Comparing the DRIFT spectra with some reported data on FTIR spectra of the same materials measured in KBr or NaCl matrices has revealed noticeable shifts of several polar functional groups both in pectin and in its FA-esterified products induced by the halide salts. The results obtained have implications for careful structural analyses of biopolymers with hydrophilic functional groups by means of different FTIR spectroscopic methodologies.

  18. Reflection-Absorption Infrared Spectroscopy of Thin Films Using an External Cavity Quantum Cascade Laser

    SciTech Connect

    Phillips, Mark C.; Craig, Ian M.; Blake, Thomas A.

    2013-02-04

    We present experimental demonstrations using a broadly tunable external cavity quantum cascade laser (ECQCL) to perform Reflection-Absorption InfraRed Spectroscopy (RAIRS) of thin layers and residues on surfaces. The ECQCL compliance voltage was used to measure fluctuations in the ECQCL output power and improve the performance of the RAIRS measurements. Absorption spectra from self-assembled monolayers of a fluorinated alkane thiol and a thiol carboxylic acid were measured and compared with FTIR measurements. RAIRS spectra of the explosive compounds PETN, RDX, and tetryl deposited on gold substrates were also measured. Rapid measurement times and low noise were demonstrated, with < 1E-3 absorbance noise for a 10 second measurement time.

  19. Discrimination of nylon polymers using attenuated total reflection mid-infrared spectra and multivariate statistical techniques.

    PubMed

    Enlow, Elizabeth M; Kennedy, Jennifer L; Nieuwland, Alexander A; Hendrix, James E; Morgan, Stephen L

    2005-08-01

    Nylons are an important class of synthetic polymers, from an industrial, as well as forensic, perspective. A spectroscopic method, such as Fourier transform infrared (FT-IR) spectroscopy, is necessary to determine the nylon subclasses (e. g., nylon 6 or nylon 6,6). Library searching using absolute difference and absolute derivative difference algorithms gives inconsistent results for identifying nylon subclasses. The objective of this study was to evaluate the usefulness of peak ratio analysis and multivariate statistics for the identification of nylon subclasses using attenuated total reflection (ATR) spectral data. Many nylon subclasses could not be distinguished by the peak ratio of the N-H vibrational stretch to the sp(3) C-H(2) vibrational stretch intensities. Linear discriminant analysis, however, provided a graphical visualization of differences between nylon subclasses and was able to correctly classify a set of 270 spectra from eight different subclasses with 98.5% cross-validated accuracy.

  20. Depth profile characterization technique for electron density in GaN films by infrared reflectance spectroscopy

    NASA Astrophysics Data System (ADS)

    Kamijoh, Takaaki; Ma, Bei; Morita, Ken; Ishitani, Yoshihiro

    2016-05-01

    Infrared reflectance spectroscopy is a noncontact measurement method for carrier density and mobility. In this article, the model determination procedure of layer-type nonuniform electron distribution is investigated, since the spectrum fitting hitherto has been conducted on the basis of a multilayer model defined in advance. A simplified case of a high-electron-density GaN layer embedded in a GaN matrix is mainly studied. The following procedure is found to be applicable. The first step is the determination of the high-density layer position in the vicinity of the surface, in the middle region, or in the vicinity of the interface. This is followed by the specification of the sheet electron density and the layer thickness of the high-density region. It is found that this procedure is also applicable to the characterization of two-dimensional electron gases in the vicinity of AlGaN/GaN heterointerfaces.

  1. Titanium-silicon oxide film structures for polarization-modulated infrared reflection absorption spectroscopy

    PubMed Central

    Dunlop, Iain E.; Zorn, Stefan; Richter, Gunther; Srot, Vesna; Kelsch, Marion; van Aken, Peter A.; Skoda, Maximilian; Gerlach, Alexander; Spatz, Joachim P.; Schreiber, Frank

    2010-01-01

    We present a titanium-silicon oxide film structure that permits polarization modulated infrared reflection absorption spectroscopy on silicon oxide surfaces. The structure consists of a ~6 nm sputtered silicon oxide film on a ~200 nm sputtered titanium film. Characterization using conventional and scanning transmission electron microscopy, electron energy loss spectroscopy, X-ray photoelectron spectroscopy and X-ray reflectometry is presented. We demonstrate the use of this structure to investigate a selectively protein-resistant self-assembled monolayer (SAM) consisting of silane-anchored, biotin-terminated poly(ethylene glycol) (PEG). PEG-associated IR bands were observed. Measurements of protein-characteristic band intensities showed that this SAM adsorbed streptavidin whereas it repelled bovine serum albumin, as had been expected from its structure. PMID:20418963

  2. Fan-shaped gold nanoantennas above reflective substrates for surface-enhanced infrared absorption (SEIRA).

    PubMed

    Brown, Lisa V; Yang, Xiao; Zhao, Ke; Zheng, Bob Y; Nordlander, Peter; Halas, Naomi J

    2015-02-11

    Here, we report a new nanoantenna for surface-enhanced infrared absorption (SEIRA) detection, consisting of a fan-shaped Au structure positioned at a well-specified distance above a reflective plane with an intervening silica spacer layer. We examine how to optimize both the antenna dimensions and the spacer layer for optimal SEIRA enhancement of the C-H stretching mode. This tunable 3D geometry yields a theoretical SEIRA enhancement factor of 10(5), corresponding to the experimental detection of 20-200 zeptomoles of octadecanethiol, using a standard commercial FTIR spectrometer. Experimental studies illustrate the sensitivity of the observed SEIRA signal to the gap dimensions. The optimized antenna structure exhibits an order of magnitude greater SEIRA sensitivity than previous record-setting designs.

  3. Understanding the collapse mechanism in Langmuir monolayers through polarization modulation-infrared reflection absorption spectroscopy.

    PubMed

    Goto, Thiago Eichi; Caseli, Luciano

    2013-07-23

    The collapse of films at the air-water interface is related to a type of 2D-to-3D transition that occurs when a Langmuir monolayer is compressed beyond its stability limit. Studies on this issue are extremely important because defects in ultrathin solid films can be better understood if the molecular mechanisms related to collapse processes are elucidated. This paper explores how the changes of vibration of specific groups of lipid molecules, as revealed by polarization modulation-infrared reflection absorption spectroscopy (PM-IRRAS), are affected by the monolayer collapse. Different mechanisms of collapse were studied, for those lipids that undergo constant-area collapse (such as stearic acid) and for those that undergo constant-pressure collapse (such as DPPC, DPPG, and DODAB). Lipid charges also affect the mechanism of collapse, as demonstrated for two oppositely charged lipids.

  4. [Testing of germination rate of hybrid rice seeds based on near-infrared reflectance spectroscopy].

    PubMed

    Li, Yi-nian; Jiang, Dan; Liu, Ying-ying; Ding, Wei-min; Ding, Qi-shuo; Zha, Liang-yu

    2014-06-01

    Germination rate of rice seeds was measured according to technical stipulation of germination testing for agricultural crop seeds at present. There existed many faults for this technical stipulation such as long experimental period, more costing and higher professional requirement. A rapid and non-invasive method was put forward to measure the germination rate of hybrid rice seeds based on near-infrared reflectance spectroscopy. Two varieties of hybrid rice seeds were aged artificially at temperature 45 degrees C and humidity 100% condition for 0, 24, 48, 72, 96, 120 and 144 h. Spectral data of 280 samples for 2 varieties of hybrid rice seeds with different aging time were acquired individually by near-infrared spectra analyzer. Spectral data of 280 samples for 2 varieties of hybrid rice seeds were randomly divided into calibration set (168 samples) and prediction set (112 samples). Gormination rate of rice seed with different aging time was tested. Regression model was established by using partial least squares (PLS). The effect of the different spectral bands on the accuracy of models was analyzed and the effect of the different spectral preprocessing methods on the accuracy of models was also compared. Optimal model was achieved under the whole bands and by using standardization and orthogonal signal correction (OSC) preprocessing algorithms with CM2000 software for spectral data of 2 varieties of hybrid rice seeds, the coefficient of determination of the calibration set (Rc) and that of the prediction set (Rp) were 0.965 and 0.931 individually, standard error of calibration set (SEC) and that of prediction set (SEP) were 1.929 and 2.899 respectively. Relative error between tested value and predicted value for prediction set of rice seeds is below 4.2%. The experimental results show that it is feasible that rice germination rate is detected rapidly and nondestructively by using the near-infrared spectroscopy analysis technology. PMID:25358159

  5. Diffuse reflectance near infrared-chemometric methods development and validation of amoxicillin capsule formulations

    PubMed Central

    Khan, Ahmed Nawaz; Khar, Roop Krishen; Ajayakumar, P. V.

    2016-01-01

    Objective: The aim of present study was to establish near infrared-chemometric methods that could be effectively used for quality profiling through identification and quantification of amoxicillin (AMOX) in formulated capsule which were similar to commercial products. In order to evaluate a large number of market products easily and quickly, these methods were modeled. Materials and Methods: Thermo Scientific Antaris II near infrared analyzer with TQ Analyst Chemometric Software were used for the development and validation of the identification and quantification models. Several AMOX formulations were composed with four excipients microcrystalline cellulose, magnesium stearate, croscarmellose sodium and colloidal silicon dioxide. Development includes quadratic mixture formulation design, near infrared spectrum acquisition, spectral pretreatment and outlier detection. According to prescribed guidelines by International Conference on Harmonization (ICH) and European Medicine Agency (EMA) developed methods were validated in terms of specificity, accuracy, precision, linearity, and robustness. Results: On diffuse reflectance mode, an identification model based on discriminant analysis was successfully processed with 76 formulations; and same samples were also used for quantitative analysis using partial least square algorithm with four latent variables and 0.9937 correlation of coefficient followed by 2.17% root mean square error of calibration (RMSEC), 2.38% root mean square error of prediction (RMSEP), 2.43% root mean square error of cross-validation (RMSECV). Conclusion: Proposed model established a good relationship between the spectral information and AMOX identity as well as content. Resulted values show the performance of the proposed models which offers alternate choice for AMOX capsule evaluation, relative to that of well-established high-performance liquid chromatography method. Ultimately three commercial products were successfully evaluated using developed

  6. [Testing of germination rate of hybrid rice seeds based on near-infrared reflectance spectroscopy].

    PubMed

    Li, Yi-nian; Jiang, Dan; Liu, Ying-ying; Ding, Wei-min; Ding, Qi-shuo; Zha, Liang-yu

    2014-06-01

    Germination rate of rice seeds was measured according to technical stipulation of germination testing for agricultural crop seeds at present. There existed many faults for this technical stipulation such as long experimental period, more costing and higher professional requirement. A rapid and non-invasive method was put forward to measure the germination rate of hybrid rice seeds based on near-infrared reflectance spectroscopy. Two varieties of hybrid rice seeds were aged artificially at temperature 45 degrees C and humidity 100% condition for 0, 24, 48, 72, 96, 120 and 144 h. Spectral data of 280 samples for 2 varieties of hybrid rice seeds with different aging time were acquired individually by near-infrared spectra analyzer. Spectral data of 280 samples for 2 varieties of hybrid rice seeds were randomly divided into calibration set (168 samples) and prediction set (112 samples). Gormination rate of rice seed with different aging time was tested. Regression model was established by using partial least squares (PLS). The effect of the different spectral bands on the accuracy of models was analyzed and the effect of the different spectral preprocessing methods on the accuracy of models was also compared. Optimal model was achieved under the whole bands and by using standardization and orthogonal signal correction (OSC) preprocessing algorithms with CM2000 software for spectral data of 2 varieties of hybrid rice seeds, the coefficient of determination of the calibration set (Rc) and that of the prediction set (Rp) were 0.965 and 0.931 individually, standard error of calibration set (SEC) and that of prediction set (SEP) were 1.929 and 2.899 respectively. Relative error between tested value and predicted value for prediction set of rice seeds is below 4.2%. The experimental results show that it is feasible that rice germination rate is detected rapidly and nondestructively by using the near-infrared spectroscopy analysis technology.

  7. Development of blood vessel searching system using near-infrared light stereo method for clinical blood sampling

    NASA Astrophysics Data System (ADS)

    Cheng, Kai; Morita, Yusuke; Nakamachi, Eiji; Honda, Norihiro; Awazu, Kunio

    2014-10-01

    We developed an accurate three-dimensional blood vessel search (3D BVS) system using NIR light for the clinical blood sampling. In the previous study, the 3D BVS system, which used near-infrared (NIR) light imaging and the stereo method to locate blood vessel accurately in three dimensions has been developed(1). However, as NIR lights could not transmit the human arm, this system could not be used for the subcutaneous blood vessel detection. In this study, we developed a BVS by using the reflecting NIR light for blood sampling assist. The light scattering in human tissue will cause blur of blood vessel edge in image, that makes the diameter of blood vessel became uncertain. In this study, a light propagation simulation and a multilayer phantom were adopted to estimate the measurement error of blood vessel diameter in our BSV system. In the simulation, the optical properties of scattering coefficient, absorption coefficient, and refractive index were set similar with human skin. Next, we fabricated a multilayer phantom, which has the similar structure and optical properties with the human skin to confirm availability of the simulation. Also, the optical properties of our phantom are adjustable in our phantom to imitate the different color of skin. We established the estimation algorithm to detect the blood vessel accurately. Finally, we confirm the availability of our BVS for the blood sampling assist system.

  8. Ranging system which compares an object reflected component of a light beam to a reference component of the light beam

    NASA Technical Reports Server (NTRS)

    Mclauchlan, J. M.; Auyeung, J.; Tubbs, E. F.; Goss, W. C.; Psaltis, D. (Inventor)

    1985-01-01

    A system is described for measuring the distance to an object by comparing a first component of a light pulse that is reflected off the object with a second component of the light pulse that passes along a reference path of known length, which provides great accuracy with a relatively simple and rugged design. The reference path can be changed in precise steps so that it has an equivalent length approximately equal to the path length of the light pulse component that is reflected from the object. The resulting small difference in path lengths can be precisely determined by directing the light pulse components into opposite ends of a detector formed of a material that emits a second harmonic light output at the locations where the opposite going pulses past simultaneously across one another.

  9. Attenuated total reflectance Fourier-transform infrared spectroscopy of carboxylic acids adsorbed onto mineral surfaces

    NASA Astrophysics Data System (ADS)

    Kubicki, J. D.; Schroeter, L. M.; Itoh, M. J.; Nguyen, B. N.; Apitz, S. E.

    1999-09-01

    A suite of naturally-occurring carboxylic acids (acetic, oxalic, citric, benzoic, salicylic and phthalic) and their corresponding sodium salts were adsorbed onto a set of common mineral substrates (quartz, albite, illite, kaolinite and montmorillonite) in batch slurry experiments. Solution pH's of approximately 3 and 6 were used to examine the effects of pH on sorption mechanisms. Attenuated total reflectance Fourier-transform infrared (ATR FTIR) spectroscopy was employed to obtain vibrational frequencies of the organic ligands on the mineral surfaces and in solution. UV/visible spectroscopy on supernatant solutions was also employed to confirm that adsorption from solution had taken place for benzoic, salicylic and phthalic acids. Molecular orbital calculations were used to model possible surface complexes and interpret the experimental spectra. In general, the tectosilicates, quartz and albite feldspar, did not chemisorb (i.e., strong, inner-sphere adsorption) the carboxylate anions in sufficient amounts to produce infrared spectra of the organics after rinsing in distilled water. The clays (illite, kaolinite and montmorillonite) each exhibited similar ATR FTIR spectra. However, the illite sample used in this study reacted to form strong surface and aqueous complexes with salicylic acid before being treated to remove free Fe-hydroxides. Chemisorption of carboxylic acids onto clays is shown to be limited without the presence of Fe-hydroxides within the clay matrix.

  10. Quantitative diffuse reflectance infrared fourier transform spectrometric studies of cementitious blends

    SciTech Connect

    Rebagay, T.V.; Dodd, D.A.

    1989-07-01

    The effective immobilization of low-level radioactive liquid wastes in the form of grout depends on the quality of the dry cementitious blends used in the grout formulation. Variation in the mix ratios of the components of the blend can cause detrimental effects on the processing behavior of the grout slurry and the final properties of the cured grout. Thus the blends require thorough chemical characterization and monitoring by strict quality control protocols. In an earlier work at our laboratories, Fourier transform infrared- transmission method has been successfully applied in the analysis of blends of cement, fly ash, and clays. However, this method involved time-consuming sample preparation resulting in slow turnaround for repetitive sampling. A practical approach to quality control required a fast and simple method for the analysis of the blends. This paper describes a diffuse reflectance infrared Fourier transform (DRIFT) spectrometric procedure for the routine examination of neat blends consisting of cement, fly ash, clays and/or blast furnace slags. (1 ref., 10 figs., 4 tabs.)

  11. Germanium-on-silicon mid-infrared grating couplers with low-reflectivity inverse taper excitation.

    PubMed

    Alonso-Ramos, Carlos; Nedeljkovic, Milos; Benedikovic, Daniel; Penadés, Jordi Soler; Littlejohns, Callum G; Khokhar, Ali Z; Pérez-Galacho, Diego; Vivien, Laurent; Cheben, Pavel; Mashanovich, Goran Z

    2016-09-15

    A broad transparency range of its constituent materials and compatibility with standard fabrication processes make germanium-on-silicon (Ge-on-Si) an excellent platform for the realization of mid-infrared photonic circuits. However, the comparatively large Ge waveguide thickness and its moderate refractive index contrast with the Si substrate hinder the implementation of efficient fiber-chip grating couplers. We report for the first time, to the best of our knowledge, a single-etch Ge-on-Si grating coupler with an inversely tapered access stage, operating at a 3.8 μm wavelength. Optimized grating excitation yields a coupling efficiency of -11  dB (7.9%), the highest value reported for a mid-infrared Ge-on-Si grating coupler, with reflectivity below -15  dB (3.2%). The large periodicity of our higher-order grating design substantially relaxes the fabrication constraints. We also demonstrate that a focusing geometry allows a 10-fold reduction in inverse taper length, from 500 to 50 μm. PMID:27628388

  12. Recent progress in noninvasive diabetes screening by diffuse reflectance near-infrared skin spectroscopy

    NASA Astrophysics Data System (ADS)

    Heise, H. M.; Haiber, S.; Licht, M.; Ihrig, D. F.; Moll, C.; Stuecker, M.

    2006-02-01

    Near infrared spectroscopy exhibits a tremendous potential for clinical chemistry and tissue pathology. Owing to its penetration depth into human skin, near infrared radiation can probe chemical and structural information non-invasively. Metabolic diseases such as diabetes mellitus increase nonenzymatic glycation with the effect of glucose molecules bonding chemically to proteins. In addition, glycation accumulates on tissue proteins with the clearest evidence found in extracellular skin collagen, affecting also covalent crosslinking between adjacent protein strands, which reduces their flexibility, elasticity, and functionality. Non-enzymatically glycated proteins in human skin and following chemical and structural skin changes were our spectroscopic target. We carried out measurements on 109 subjects using two different NIR-spectrometers equipped with diffuse reflection accessories. Spectra of different skin regions (finger and hand/forearm skin) were recorded for comparison with clinical blood analysis data and further patient information allowing classification into diabetics and non-diabetics. Multivariate analysis techniques for supervised classification such as linear discriminant analysis (LDA) were applied using broad spectral interval data or a number of optimally selected wavelengths. Based on fingertip skin spectra recorded by fiber-optics, it was possible to classify diabetics and non-diabetics with a maximum accuracy of 87.8 % using leave-5-out cross-validation (sensitivity of 87.5. %, specificity of 88.2 %). With the results of this study, it can be concluded that ageing and glycation at elevated levels cannot always be separated from each other.

  13. Analysis of visible and near infrared spectral reflectance for assessing metals in soil.

    PubMed

    Rathod, Paresh H; Müller, Ingo; Van der Meer, Freek D; de Smeth, Boudewijn

    2015-10-01

    Visible and near infrared reflectance (VNIR; 350-2500 nm) spectroscopy has greatly been used in soils, especially for studying variability in spectrally active soil components (e.g., organic carbon, clays, and Fe/Al oxides) based on their diagnostic spectral features. In recent years, this technique has also been applied to assess soil metallic ions. In this research, the feasibility of VNIR spectroscopy for determination of soil metals was investigated with two soil data sets: (i) artificially metal-spiked and (ii) in situ metal-contaminated soils. Results showed that reflectance spectra of neither metal-spiked soils with Cd, As, and Pb even at their higher concentrations of 20, 900, and 1200 mg kg(-1), respectively, nor in situ metal-contaminated soils (with concentrations of 30 mg Cd, 3019 mg As, and 5725 mg Pb kg(-1) soil) showed any recognized absorption peaks that correspond to soil metal concentrations. We observed variations in reflectance intensity for in situ metal-contaminated soils only, showing higher reflectance across the entire spectrum for strongly and lower for less metal-contaminated soils. A significant correlation was found between surface soil metals' concentrations and continuum removed spectra, while soil metals were also found significantly associated with soil organic matter and total Fe. A partial least square regression with cross-validation approach produced an acceptable prediction of metals (R (2) = 0.58-0.94) for both soil data sets, metal-spiked and in situ metal-contaminated soils. However, high values of root mean square error ruled out practical application of the achieved prediction models. PMID:27614958

  14. Penetration Depth Measurement of Near-Infrared Hyperspectral Imaging Light for Milk Powder.

    PubMed

    Huang, Min; Kim, Moon S; Chao, Kuanglin; Qin, Jianwei; Mo, Changyeun; Esquerre, Carlos; Delwiche, Stephen; Zhu, Qibing

    2016-01-01

    The increasingly common application of the near-infrared (NIR) hyperspectral imaging technique to the analysis of food powders has led to the need for optical characterization of samples. This study was aimed at exploring the feasibility of quantifying penetration depth of NIR hyperspectral imaging light for milk powder. Hyperspectral NIR reflectance images were collected for eight different milk powder products that included five brands of non-fat milk powder and three brands of whole milk powder. For each milk powder, five different powder depths ranging from 1 mm-5 mm were prepared on the top of a base layer of melamine, to test spectral-based detection of the melamine through the milk. A relationship was established between the NIR reflectance spectra (937.5-1653.7 nm) and the penetration depth was investigated by means of the partial least squares-discriminant analysis (PLS-DA) technique to classify pixels as being milk-only or a mixture of milk and melamine. With increasing milk depth, classification model accuracy was gradually decreased. The results from the 1-mm, 2-mm and 3-mm models showed that the average classification accuracy of the validation set for milk-melamine samples was reduced from 99.86% down to 94.93% as the milk depth increased from 1 mm-3 mm. As the milk depth increased to 4 mm and 5 mm, model performance deteriorated further to accuracies as low as 81.83% and 58.26%, respectively. The results suggest that a 2-mm sample depth is recommended for the screening/evaluation of milk powders using an online NIR hyperspectral imaging system similar to that used in this study. PMID:27023555

  15. Penetration Depth Measurement of Near-Infrared Hyperspectral Imaging Light for Milk Powder

    PubMed Central

    Huang, Min; Kim, Moon S.; Chao, Kuanglin; Qin, Jianwei; Mo, Changyeun; Esquerre, Carlos; Delwiche, Stephen; Zhu, Qibing

    2016-01-01

    The increasingly common application of the near-infrared (NIR) hyperspectral imaging technique to the analysis of food powders has led to the need for optical characterization of samples. This study was aimed at exploring the feasibility of quantifying penetration depth of NIR hyperspectral imaging light for milk powder. Hyperspectral NIR reflectance images were collected for eight different milk powder products that included five brands of non-fat milk powder and three brands of whole milk powder. For each milk powder, five different powder depths ranging from 1 mm–5 mm were prepared on the top of a base layer of melamine, to test spectral-based detection of the melamine through the milk. A relationship was established between the NIR reflectance spectra (937.5–1653.7 nm) and the penetration depth was investigated by means of the partial least squares-discriminant analysis (PLS-DA) technique to classify pixels as being milk-only or a mixture of milk and melamine. With increasing milk depth, classification model accuracy was gradually decreased. The results from the 1-mm, 2-mm and 3-mm models showed that the average classification accuracy of the validation set for milk-melamine samples was reduced from 99.86% down to 94.93% as the milk depth increased from 1 mm–3 mm. As the milk depth increased to 4 mm and 5 mm, model performance deteriorated further to accuracies as low as 81.83% and 58.26%, respectively. The results suggest that a 2-mm sample depth is recommended for the screening/evaluation of milk powders using an online NIR hyperspectral imaging system similar to that used in this study. PMID:27023555

  16. Penetration Depth Measurement of Near-Infrared Hyperspectral Imaging Light for Milk Powder.

    PubMed

    Huang, Min; Kim, Moon S; Chao, Kuanglin; Qin, Jianwei; Mo, Changyeun; Esquerre, Carlos; Delwiche, Stephen; Zhu, Qibing

    2016-03-25

    The increasingly common application of the near-infrared (NIR) hyperspectral imaging technique to the analysis of food powders has led to the need for optical characterization of samples. This study was aimed at exploring the feasibility of quantifying penetration depth of NIR hyperspectral imaging light for milk powder. Hyperspectral NIR reflectance images were collected for eight different milk powder products that included five brands of non-fat milk powder and three brands of whole milk powder. For each milk powder, five different powder depths ranging from 1 mm-5 mm were prepared on the top of a base layer of melamine, to test spectral-based detection of the melamine through the milk. A relationship was established between the NIR reflectance spectra (937.5-1653.7 nm) and the penetration depth was investigated by means of the partial least squares-discriminant analysis (PLS-DA) technique to classify pixels as being milk-only or a mixture of milk and melamine. With increasing milk depth, classification model accuracy was gradually decreased. The results from the 1-mm, 2-mm and 3-mm models showed that the average classification accuracy of the validation set for milk-melamine samples was reduced from 99.86% down to 94.93% as the milk depth increased from 1 mm-3 mm. As the milk depth increased to 4 mm and 5 mm, model performance deteriorated further to accuracies as low as 81.83% and 58.26%, respectively. The results suggest that a 2-mm sample depth is recommended for the screening/evaluation of milk powders using an online NIR hyperspectral imaging system similar to that used in this study.

  17. Diffuse Reflectance Mid-Infrared Spectroscopy as a Tool for the Identification of Surface Contamination on Sandblasted Metals

    NASA Technical Reports Server (NTRS)

    Powell, Louis G.; Barber, Tye E.; Neu, John T.; Nerren, Billy H.

    1997-01-01

    The SOC 400 Surface Inspection Machine/Infrared (SIMIR) is a small, ruggedized Fourier transform infrared spectrometer having dedicated diffuse reflectance optics. The SOC 400 was designed for the purpose of detecting (qualitatively and quantitatively) oil stains on the inside surface of solid rocket motor casings in the as-sandblasted and cleaned condition at levels approaching 1 mg. sq ft. The performance of this instrument is described using spectral mapping techniques.

  18. Diffuse reflectance mid-infrared spectroscopy as a tool for the identification of surface contamination on sandblasted metals

    SciTech Connect

    Powell, G.L.; Barber, T.E.; Neu, J.T.; Nerren, B.H.

    1996-07-30

    The SOC 400 Surface Inspection Machine/Infrared (SIMIR) is a small, ruggedized Fourier transform infrared spectrometer having dedicated diffuse reflectance optics. The SOC 400 was designed for the purpose of detecting (qualitatively and quantitatively) oil stains on the inside surface of solid rocket motor casings in the as-sandblasted and cleaned condition at levels approaching 1 mg ft{sup {minus}2}. The performance of this instrument is described using spectral mapping techniques.

  19. Innovative light collimator with afocal lens and total internal reflection lens for daylighting system.

    PubMed

    Chen, Bo-Jian; Chen, Yin-Ti; Ullah, Irfan; Chou, Chun-Han; Chan, Kai-Cyuan; Lai, Yi-Lung; Lin, Chia-Ming; Chang, Cheng-Ming; Whang, Allen Jong-Woei

    2015-10-01

    This research presents a novel design of the collimator, which uses total internal reflection (TIR), convex, and concave lenses for the natural light illumination system (NLIS). The concept of the NLIS is to illuminate building interiors with natural light, which saves energy consumption. The TIR lens is used to collimate the light, and convex and concave lenses are used to converge the light to the required area. The results have shown that the efficiency in terms of achieving collimated light using the proposed collimator at the output of the light collector is better than that of a previous system without a collimator. PMID:26479648

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

    NASA Astrophysics Data System (ADS)

    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 (z<2) galaxies, those were tidally stripped by the interaction of satellite dwarf galaxies. Thus, in order to understand the origin of the EBL, both the spatial fluctuation observations with multiple wavelength bands and the absolute spectroscopic observations for the EBL are highly required. After the successful initial CIBER- 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

  1. Chemical morphology of Areca nut characterized directly by Fourier transform near-infrared and mid-infrared microspectroscopic imaging in reflection modes.

    PubMed

    Chen, Jian-Bo; Sun, Su-Qin; Zhou, Qun

    2016-12-01

    Fourier transform near-infrared (NIR) and mid-infrared (MIR) imaging techniques are essential tools to characterize the chemical morphology of plant. The transmission imaging mode is mostly used to obtain easy-to-interpret spectra with high signal-to-noise ratio. However, the native chemical compositions and physical structures of plant samples may be altered when they are microtomed for the transmission tests. For the direct characterization of thick plant samples, the combination of the reflection NIR imaging and the attenuated total reflection (ATR) MIR imaging is proposed in this research. First, the reflection NIR imaging method can explore the whole sample quickly to find out typical regions in small sizes. Next, each small typical region can be measured by the ATR-MIR imaging method to reveal the molecular structures and spatial distributions of compounds of interest. As an example, the chemical morphology of Areca nut section is characterized directly by the above approach.

  2. Effects on biological systems of reflected light from a satellite power system

    NASA Technical Reports Server (NTRS)

    White, M.

    1981-01-01

    Light reflection produced by the satellite power system and the possible effects of that light on the human eye, plants, and animals were studied. For the human eye, two cases of reflected light, might cause eye damage if viewed for too long. These cases are: (1) if, while in low Earth orbit, the orbital transfer vehicle is misaligned to reflect the Sun to Earth there exists a maximum safe fixation time for the naked eye of 42.4 secs; (2) reflection from the aluminum paint on the back of the orbital transfer vehicle, while in or near low Earth orbit, can be safely viewed by the naked eye for 129 sec. For plants and animals the intensity and timing of light are not a major problem. Ways for reducing and/or eliminating the irradiances are proposed.

  3. Method and apparatus for detecting phycocyanin-pigmented algae and bacteria from reflected light

    NASA Technical Reports Server (NTRS)

    Vincent, Robert (Inventor)

    2006-01-01

    The present invention relates to a method of detecting phycocyanin algae or bacteria in water from reflected light, and also includes devices for the measurement, calculation and transmission of data relating to that method.

  4. Method and apparatus for detecting phycocyanin-pigmented algae and bacteria from reflected light

    NASA Technical Reports Server (NTRS)

    Vincent, Robert (Inventor)

    2013-01-01

    The present invention relates to a method of detecting phycocyanin algae or bacteria in water from reflected light, and also includes devices for the measurement, calculation and transmission of data relating to that method.

  5. Experiment in the Bragg Reflection of Light for the Undergraduate Using Cholesteric Liquid Crystals

    ERIC Educational Resources Information Center

    Olah, A.; Doane, J. W.

    1977-01-01

    Describes a simple experimental setup in which the student can detect and record light spectra, study and test the concept of Bragg reflection, and measure the anisotropy of the index of refraction in a cholesteric liquid crystal. (MLH)

  6. Scattered and reflected light intensities above the atmosphere.

    PubMed

    Thompson, B C; Wells, M B

    1971-07-01

    A calculational method is described that was developed for use in predicting the angular distribution of the upwelling flux of sunlight scattered by the atmosphere and reflected by the ground. Monte Carlo calculations of the radiation escaping the top of a plane-parallel model atmosphere were used as input in a computer procedure that integrates the reflected intensities over the sunlit portion of the top of the earth's atmosphere, which is visible by a receiver located on a spacecraft. Calculations were performed for a model maritime atmosphere, with and without low-altitude cloud layer, and a model continental atmosphere, which includes treatment of the effects of aerosol, Rayleigh scattering, and ozone absorption. The ground surface was assumed to be a Lambert reflector. The results of the Monte Carlo calculation for five wavelengths between 370 nm and 780 nm were compared with measured data from the Ames Research Center earth albedo experiment on the OSO-3 satellite. Agreement between calculated and measured values was sufficiently good to warrant the conclusion that reasonable estimates of the angular distribution of the radiation reaching a near-earth spacecraft from different atmospheric conditions could be calculated.

  7. "Lights, Camera, Reflection": Using Peer Video to Promote Reflective Dialogue among Student Teachers

    ERIC Educational Resources Information Center

    Harford, Judith; MacRuairc, Gerry; McCartan, Dermot

    2010-01-01

    This paper examines the use of peer-videoing in the classroom as a means of promoting reflection among student teachers. Ten pre-service teachers participating in a teacher education programme in a university in the Republic of Ireland and ten pre-service teachers participating in a teacher education programme in a university in the North of…

  8. Face Recognition in Low-Light Environments Using Fusion of Thermal Infrared and Intensified Imagery

    NASA Astrophysics Data System (ADS)

    Socolinsky, Diego A.; Wolff, Lawrence B.

    This chapter presents a study of face recognition performance as a function of light level using intensified near infrared imagery in conjunction with thermal infrared imagery. Intensification technology is the most prevalent in both civilian and military night vision equipment and provides enough enhancement for human operators to perform standard tasks under extremely low light conditions. We describe a comprehensive data collection effort undertaken to image subjects under carefully controlled illumination and quantify the performance of standard face recognition algorithms on visible, intensified, and thermal imagery as a function of light level. Performance comparisons for automatic face recognition are reported using the standardized implementations from the Colorado State University Face Identification Evaluation System, as well as Equinox's algorithms. The results contained in this chapter should constitute the initial step for analysis and deployment of face recognition systems designed to work in low-light conditions.

  9. Face recognition in low-light environments using fusion of thermal infrared and intensified imagery

    NASA Astrophysics Data System (ADS)

    Socolinsky, Diego A.; Wolff, Lawrence B.; Lundberg, Andrew J.

    2006-05-01

    This paper presents a study of face recognition performance as a function of light level using intensified near infrared imagery in conjunction with thermal infrared imagery. Intensification technology is the most prevalent in both civilian and military night vision equipment, and provides enough enhancement for human operators to perform standard tasks under extremely low-light conditions. We describe a comprehensive data collection effort undertaken by the authors to image subjects under carefully controlled illumination and quantify the performance of standard face recognition algorithms on visible, intensified and thermal imagery as a function of light level. Performance comparisons for automatic face recognition are reported using the standardized implementations from the CSU Face Identification Evaluation System, as well as Equinox own algorithms. The results contained in this paper should constitute the initial step for analysis and deployment of face recognition systems designed to work in low-light level conditions.

  10. In vivo measurement of mid-infrared light scattering from human skin

    PubMed Central

    Michel, Anna P. M.; Liakat, Sabbir; Bors, Kevin; Gmachl, Claire F.

    2013-01-01

    Two mid-infrared light sources, a broadband source from a Fourier Transform Infrared Spectrometer (FTIR) and a pulsed Quantum Cascade (QC) Laser, are used to measure angle-resolved backscattering in vivo from human skin across a broad spectral range. Scattering profiles measured using the FTIR suggest limited penetration of the light into the skin, with most of the light interacting with the stratum corneum layer of the epidermis. Scattering profiles from the QC laser show modulation patterns with angle suggesting interaction with scattering centers in the skin. The scattering is attributed to interaction of the laser light with components such as collagen fibers and capillaries in the dermis layer of the skin. PMID:23577287

  11. Does infrared or ultraviolet light damage the lens?

    PubMed

    Söderberg, P G; Talebizadeh, N; Yu, Z; Galichanin, K

    2016-02-01

    In daylight, the human eye is exposed to long wavelength ultraviolet radiation (UVR), visible radiation and short wavelength infrared radiation (IRR). Almost all the UVR and a fraction of the IRR waveband, respectively, left over after attenuation in the cornea, is absorbed in the lens. The time delay between exposure and onset of biological response in the lens varies from immediate-to-short-to-late. After exposure to sunlight or artificial sources, generating irradiances of the same order of magnitude or slightly higher, biological damage may occur photochemically or thermally. Epidemiological studies suggest a dose-dependent association between short wavelength UVR and cortical cataract. Experimental data infer that repeated daily in vivo exposures to short wavelength UVR generate photochemically induced damage in the lens, and that short delay onset cataract after UVR exposure is photochemically induced. Epidemiology suggests that daily high-intensity short wavelength IRR exposure of workers, is associated with a higher prevalence of age-related cataract. It cannot be excluded that this effect is owing to a thermally induced higher denaturation rate. Recent experimental data rule out a photochemical effect of 1090 nm in the lens but other wavelengths in the near IRR should be investigated.

  12. Analysis of the DNA Fourier transform-infrared microspectroscopic signature using an all-reflecting objective.

    PubMed

    Mello, Maria Luiza S; Vidal, Benedicto C

    2014-06-01

    The Fourier transform-infrared (FT-IR) signature of dry samples of DNA and DNA-polypeptide complexes, as studied by IR microspectroscopy using a diamond attenuated total reflection (ATR) objective, has revealed important discriminatory characteristics relative to the PO2(-) vibrational stretchings. However, DNA IR marks that provide information on the sample's richness in hydrogen bonds have not been resolved in the spectral profiles obtained with this objective. Here we investigated the performance of an "all reflecting objective" (ARO) for analysis of the FT-IR signal of hydrogen bonds in DNA samples differing in base richness types (salmon testis vs calf thymus). The results obtained using the ARO indicate prominent band peaks at the spectral region representative of the vibration of nitrogenous base hydrogen bonds and of NH and NH2 groups. The band areas at this spectral region differ in agreement with the DNA base richness type when using the ARO. A peak assigned to adenine was more evident in the AT-rich salmon DNA using either the ARO or the ATR objective. It is concluded that, for the discrimination of DNA IR hydrogen bond vibrations associated with varying base type proportions, the use of an ARO is recommended.

  13. Rapid estimation of nutritional elements on citrus leaves by near infrared reflectance spectroscopy

    PubMed Central

    Galvez-Sola, Luis; García-Sánchez, Francisco; Pérez-Pérez, Juan G.; Gimeno, Vicente; Navarro, Josefa M.; Moral, Raul; Martínez-Nicolás, Juan J.; Nieves, Manuel

    2015-01-01

    Sufficient nutrient application is one of the most important factors in producing quality citrus fruits. One of the main guides in planning citrus fertilizer programs is by directly monitoring the plant nutrient content. However, this requires analysis of a large number of leaf samples using expensive and time-consuming chemical techniques. Over the last 5 years, it has been demonstrated that it is possible to quantitatively estimate certain nutritional elements in citrus leaves by using the spectral reflectance values, obtained by using near infrared reflectance spectroscopy (NIRS). This technique is rapid, non-destructive, cost-effective and environmentally friendly. Therefore, the estimation of macro and micronutrients in citrus leaves by this method would be beneficial in identifying the mineral status of the trees. However, to be used effectively NIRS must be evaluated against the standard techniques across different cultivars. In this study, NIRS spectral analysis, and subsequent nutrient estimations for N, K, Ca, Mg, B, Fe, Cu, Mn, and Zn concentration, were performed using 217 leaf samples from different citrus trees species. Partial least square regression and different pre-processing signal treatments were used to generate the best estimation against the current best practice techniques. It was verified a high proficiency in the estimation of N (Rv = 0.99) and Ca (Rv = 0.98) as well as achieving acceptable estimation for K, Mg, Fe, and Zn. However, no successful calibrations were obtained for the estimation of B, Cu, and Mn. PMID:26257767

  14. Characterization of historic silk by polarized attenuated total reflectance Fourier transform infrared spectroscopy for informed conservation.

    PubMed

    Garside, Paul; Lahlil, Sophia; Wyeth, Paul

    2005-10-01

    When assessing historic textiles and considering appropriate conservation, display, and storage strategies, characterizing the physical condition of the textiles is essential. Our work has concentrated on developing nondestructive or micro-destructive methodologies that will permit this. Previously, we have demonstrated a correlation between the physical deterioration of unweighted and "pink" tin (IV) chloride weighted silk and certain measurable spectroscopic and chromatographic signatures, derived from polarized Fourier transform infrared attenuated total reflectance (FTIR-ATR) spectroscopy (Pol-ATR) and high-performance liquid chromatography (HPLC) microsampling analyses. The application of the Pol-ATR technique to aged silk characterization has now been extended to include a more comprehensive range of weighting methods and aging regimes. This was intended to replicate the full spectrum of states of deterioration observed in silk textiles, from pristine to heavily degraded. Breaking strength was employed as a measure of the physical integrity of the fibers, and, as expected, decreased with aging. An orientational crystallinity parameter, reflecting the microstructural ordering of the fibroin polymer within the fibers, was derived from the Pol-ATR spectra. A good correlation was observed between the breaking strength of the variety of fibers and this parameter. This suggests that the physical state of historic silk fabrics might be adequately characterized for conservation purposes by such indirect micromethodology.

  15. Improved depth resolution in near-infrared diffuse reflectance spectroscopy using obliquely oriented fibers

    NASA Astrophysics Data System (ADS)

    Thilwind, Rachel Estelle; 't Hooft, Gert; Uzunbajakava, Natallia E.

    2009-03-01

    We demonstrate a significant improvement of depth selectivity when using obliquely oriented fibers for near-infrared (NIR) diffuse reflectance spectroscopy. This is confirmed by diffuse reflectance measurements of a two-layer tissue-mimicking phantom across the spectral range from 1000 to 1940 nm. The experimental proof is supported by Monte Carlo simulations. The results reveal up to fourfold reduction in the mean optical penetration depth, twofold reduction in its variation, and a decrease in the number of scattering events when a single fiber is oriented at an angle of 60 deg. The effect of reducing the mean optical penetration depth is enhanced by orienting both fibers inwardly. Using outwardly oriented fibers enables more selective probing of deeper layers, while reducing the contribution from surface layers. We further demonstrate that the effect of an inward oblique arrangement can be approximated to a decrease in fiber-to-fiber separation in the case of a perpendicular fiber arrangement. This approximation is valid in the weak- or absorption-free regime. Our results assert the advantages of using obliquely oriented fibers when attempting to specifically address superficial tissue layers, for example, for skin cancer detection, or in noninvasive glucose monitoring. Such flexibility could be further advantageous in a range of minimally invasive applications, including catheter-based interventions.

  16. Synchrotron Infrared Reflectance Microspectroscopy Study of Film Formation and Breakdown on Copper

    SciTech Connect

    Hahn, F.; Melendres, C

    2010-01-01

    This work demonstrates the utility of synchrotron infrared reflectance microspectroscopy in the far- and mid-IR for the determination of the composition of electrogenerated surface films formed during the general and localized corrosion of copper in alkaline and bicarbonate solutions. Back-reflection geometry has been employed to identify the anodic film formed on copper in 0.1 M NaOH solution at 0.3 V (versus a Ag/AgCl reference) to be mainly CuO. In 0.01 M NaHCO{sub 3} solution general corrosion occurs with passive film formation below 0.2 V. The surface film at 0.2 V consisted mainly of bicarbonate, copper carbonate dihydroxide or malachite [CuCO{sub 3} {center_dot} Cu(OH){sub 2}], Cu(OH){sub 2} and possibly some CuO. At higher potentials the passive film breaks down and localized corrosion occurs leading to the formation of pits. The composition of the surface films inside the pits formed at 0.6 V was found to be essentially the same as that outside but the relative amount of Cu(OH){sub 2} appears to be higher.

  17. Radiance and polarization of light reflected from optically thick clouds.

    PubMed

    Kattawar, G W; Plass, G N

    1971-01-01

    The reflected radiance and polarization are calculated for clouds with optical thicknesses from 10 to 100. The results are presented for both the haze C and nimbostratus model. The peak in the single scattered polarization at 140 degrees for the nimbostratus model persists even with all the multiple scattering events that occur for the largest optical thicknesses considered here. The calculations are made by a Monte Carlo technique, which includes the effect of multiple scattering through all orders and a realistic anisotropic phase function for single scattering appropriate for the distribution of particle sizes in the cloud. The effect of the surface albedo is included in the calculations for the optical thickness of 10. The variation of the radiance and polarization with both the nadir and azimuthal angle is given for several solar zenith angles.

  18. Photosynthesis-related infrared light transmission changes in spinach leaf segments

    SciTech Connect

    Akimoto, T.

    1985-10-01

    The time courses of infrared light transmission changes and fluorescence induced by light in spinach leaf segments were measured. The illumination by red light exhibited a complex wave pattern. The transmission approached the baseline after repeating decreases and increases. Illumination by far-red light decreased the transmission. One of the differences between the two responses was the difference between the two amplitudes of the first increasing component. The component in the red light response was larger than the component in the far-red light response. The transmission decrease by far-red light is supposed to correspond to ''red drop.'' The transmission decrease by far-red light was suppressed by red light. This is due to an activation of a transmission-increasing component. This probably corresponds to ''enhancement.'' A proportional correlation existed between the intensity of far-red light and the minimum intensity of red light that suppressed the transmission decrease induced by far-red light. The component which made Peak D in the time course of fluorescence yield and the first increasing component in the transmission changes were suppressed by intense light.

  19. Turning On Lights to Stop Neurodegeneration: The Potential of Near Infrared Light Therapy in Alzheimer's and Parkinson's Disease

    PubMed Central

    Johnstone, Daniel M.; Moro, Cécile; Stone, Jonathan; Benabid, Alim-Louis; Mitrofanis, John

    2016-01-01

    Alzheimer's and Parkinson's disease are the two most common neurodegenerative disorders. They develop after a progressive death of many neurons in the brain. Although therapies are available to treat the signs and symptoms of both diseases, the progression of neuronal death remains relentless, and it has proved difficult to slow or stop. Hence, there is a need to develop neuroprotective or disease-modifying treatments that stabilize this degeneration. Red to infrared light therapy (λ = 600–1070 nm), and in particular light in the near infrared (NIr) range, is emerging as a safe and effective therapy that is capable of arresting neuronal death. Previous studies have used NIr to treat tissue stressed by hypoxia, toxic insult, genetic mutation and mitochondrial dysfunction with much success. Here we propose NIr therapy as a neuroprotective or disease-modifying treatment for Alzheimer's and Parkinson's patients. PMID:26793049

  20. Baseline Correction of Diffuse Reflection Near-Infrared Spectra Using Searching Region Standard Normal Variate (SRSNV).

    PubMed

    Genkawa, Takuma; Shinzawa, Hideyuki; Kato, Hideaki; Ishikawa, Daitaro; Murayama, Kodai; Komiyama, Makoto; Ozaki, Yukihiro

    2015-12-01

    An alternative baseline correction method for diffuse reflection near-infrared (NIR) spectra, searching region standard normal variate (SRSNV), was proposed. Standard normal variate (SNV) is an effective pretreatment method for baseline correction of diffuse reflection NIR spectra of powder and granular samples; however, its baseline correction performance depends on the NIR region used for SNV calculation. To search for an optimal NIR region for baseline correction using SNV, SRSNV employs moving window partial least squares regression (MWPLSR), and an optimal NIR region is identified based on the root mean square error (RMSE) of cross-validation of the partial least squares regression (PLSR) models with the first latent variable (LV). The performance of SRSNV was evaluated using diffuse reflection NIR spectra of mixture samples consisting of wheat flour and granular glucose (0-100% glucose at 5% intervals). From the obtained NIR spectra of the mixture in the 10 000-4000 cm(-1) region at 4 cm intervals (1501 spectral channels), a series of spectral windows consisting of 80 spectral channels was constructed, and then SNV spectra were calculated for each spectral window. Using these SNV spectra, a series of PLSR models with the first LV for glucose concentration was built. A plot of RMSE versus the spectral window position obtained using the PLSR models revealed that the 8680–8364 cm(-1) region was optimal for baseline correction using SNV. In the SNV spectra calculated using the 8680–8364 cm(-1) region (SRSNV spectra), a remarkable relative intensity change between a band due to wheat flour at 8500 cm(-1) and that due to glucose at 8364 cm(-1) was observed owing to successful baseline correction using SNV. A PLSR model with the first LV based on the SRSNV spectra yielded a determination coefficient (R2) of 0.999 and an RMSE of 0.70%, while a PLSR model with three LVs based on SNV spectra calculated in the full spectral region gave an R2 of 0.995 and an RMSE of

  1. Noninvasive observation of skeletal muscle contraction using near-infrared time-resolved reflectance and diffusing-wave spectroscopy.

    PubMed

    Belau, Markus; Ninck, Markus; Hering, Gernot; Spinelli, Lorenzo; Contini, Davide; Torricelli, Alessandro; Gisler, Thomas

    2010-01-01

    We introduce a method for noninvasively measuring muscle contraction in vivo, based on near-infrared diffusing-wave spectroscopy (DWS). The method exploits the information about time-dependent shear motions within the contracting muscle that are contained in the temporal autocorrelation function g(1)(τ,t) of the multiply scattered light field measured as a function of lag time, τ, and time after stimulus, t. The analysis of g(1)(τ,t) measured on the human M. biceps brachii during repetitive electrical stimulation, using optical properties measured with time-resolved reflectance spectroscopy, shows that the tissue dynamics giving rise to the speckle fluctuations can be described by a combination of diffusion and shearing. The evolution of the tissue Cauchy strain e(t) shows a strong correlation with the force, indicating that a significant part of the shear observed with DWS is due to muscle contraction. The evolution of the DWS decay time shows quantitative differences between the M. biceps brachii and the M. gastrocnemius, suggesting that DWS allows to discriminate contraction of fast- and slow-twitch muscle fibers. PMID:21054123

  2. Noninvasive observation of skeletal muscle contraction using near-infrared time-resolved reflectance and diffusing-wave spectroscopy

    NASA Astrophysics Data System (ADS)

    Belau, Markus; Ninck, Markus; Hering, Gernot; Spinelli, Lorenzo; Contini, Davide; Torricelli, Alessandro; Gisler, Thomas

    2010-09-01

    We introduce a method for noninvasively measuring muscle contraction in vivo, based on near-infrared diffusing-wave spectroscopy (DWS). The method exploits the information about time-dependent shear motions within the contracting muscle that are contained in the temporal autocorrelation function g(1)(τ,t) of the multiply scattered light field measured as a function of lag time, τ, and time after stimulus, t. The analysis of g(1)(τ,t) measured on the human M. biceps brachii during repetitive electrical stimulation, using optical properties measured with time-resolved reflectance spectroscopy, shows that the tissue dynamics giving rise to the speckle fluctuations can be described by a combination of diffusion and shearing. The evolution of the tissue Cauchy strain e(t) shows a strong correlation with the force, indicating that a significant part of the shear observed with DWS is due to muscle contraction. The evolution of the DWS decay time shows quantitative differences between the M. biceps brachii and the M. gastrocnemius, suggesting that DWS allows to discriminate contraction of fast- and slow-twitch muscle fibers.

  3. Near infrared light-responsive and injectable supramolecular hydrogels for on-demand drug delivery.

    PubMed

    Wang, Xinyu; Wang, Changping; Zhang, Qiang; Cheng, Yiyun

    2016-01-18

    A near infrared (NIR) light-responsive supramolecular hydrogel consisting of α-cyclodextrin and poly(ethylene glycol)-modified dendrimer-encapsulated platinum nanoparticles was developed. Upon NIR irradiation, this hydrogel underwent a photothermo-sensitive degradation to release the entrapped therapeutic agents in an on-demand and dose-tunable fashion. PMID:26588349

  4. The influence of the thermal environment on the stray light performances of infrared telescope systems

    NASA Astrophysics Data System (ADS)

    Xiao, Jing; Yao, Xiuwen; Zhang, Bin; Zeng, Shuguang; He, Pan

    2010-05-01

    Infrared telescopes are often required to work in a complex thermal environment. A long time of daytime heating will cause the temperature of the telescope dome and the surrounding facilities different from the ambient air during the night. Different levels of temperature controlling and the accuracy of forecasting will lead to the temperature departures between the components in the system. Furthermore, the contaminated particles settled on the optical elements will change the optical characteristics of the optical elements. All of these factors will degrade the stray light performances of infrared telescopes. In this paper, taking Cassegrain as a typical example and using the optical analysis software, i.e., ASAP, the three-dimensional simulation models of the infrared telescope and the dome has been built up. On this basis, the stray light performances and the variation of the systems have been simulated and analyzed for the different cases of the different coating for the dome, the change of the temperature of primary and ambient, as well as the existence of the mirror contamination. The effective emissivity has been introduced and the stray light performance of the systems has been evaluated. The results indicate that the contaminated particles settled on the optical elements will degrade the system performances significantly, whereas the influences of other factors are relatively small. Therefore, it is of great importance to focus on the contaminated particles settled on the optical elements to adopt proper methods to improve the stray light performances of infrared telescope systems.

  5. Effects of ultraviolet radiation, visible light, and infrared radiation on erythema and pigmentation: a review.

    PubMed

    Sklar, Lindsay R; Almutawa, Fahad; Lim, Henry W; Hamzavi, Iltefat

    2013-01-01

    The effects of ultraviolet radiation, visible light, and infrared radiation on cutaneous erythema, immediate pigment darkening, persistent pigment darkening, and delayed tanning are affected by a variety of factors. Some of these factors include the depth of cutaneous penetration of the specific wavelength, the individual skin type, and the absorption spectra of the different chromophores in the skin. UVB is an effective spectrum to induce erythema, which is followed by delayed tanning. UVA induces immediate pigment darkening, persistent pigment darkening, and delayed tanning. At high doses, UVA (primarily UVA2) can also induce erythema in individuals with skin types I-II. Visible light has been shown to induce erythema and a tanning response in dark skin, but not in fair skinned individuals. Infrared radiation produces erythema, which is probably a thermal effect. In this article we reviewed the available literature on the effects of ultraviolet radiation, visible light, and infrared radiation on the skin in regards to erythema and pigmentation. Much remains to be learned on the cutaneous effects of visible light and infrared radiation.

  6. Micro-light guides: a new method for measuring tissue fluorescence and reflectance.

    PubMed

    Ji, S; Chance, B; Nishiki, K; Smith, T; Rich, T

    1979-03-01

    Three-way light guides containing one or more strands of 25-micron or 80-micron diameter optical fibers in each channel have been constructed and used to measure the NADH fluorescence and UV reflectance from mitochondrial suspensions, the perfused, hemoglobin-free rat liver, and the perfused beating interventricular septum of the rabbit. The optical changes measured with these so-called micro-light guides, which have channels containing one or several strands of optical fibers less than 100 micron, are comparable in magnitude with those measured using much larger conventional light guides. The effect of light scattering on the fluorescence channel has been determined and an empirical equation for correcting the fluorescence channel for light scattering has been obtained for mitochondrial suspensions. A mathematical equation characterizing the optical behavior of a two-way micro-light guide has been derived and has been shown to account satisfactorily for reflectance and fluorescence measurements of a mat surface in air.

  7. Autofluorescence Imaging With Near-Infrared Excitation:Normalization by Reflectance to Reduce Signal From Choroidal Fluorophores

    PubMed Central

    Cideciyan, Artur V.; Swider, Malgorzata; Jacobson, Samuel G.

    2015-01-01

    Purpose. We previously developed reduced-illuminance autofluorescence imaging (RAFI) methods involving near-infrared (NIR) excitation to image melanin-based fluorophores and short-wavelength (SW) excitation to image lipofuscin-based flurophores. Here, we propose to normalize NIR-RAFI in order to increase the relative contribution of retinal pigment epithelium (RPE) fluorophores. Methods. Retinal imaging was performed with a standard protocol holding system parameters invariant in healthy subjects and in patients. Normalized NIR-RAFI was derived by dividing NIR-RAFI signal by NIR reflectance point-by-point after image registration. Results. Regions of RPE atrophy in Stargardt disease, AMD, retinitis pigmentosa, choroideremia, and Leber congenital amaurosis as defined by low signal on SW-RAFI could correspond to a wide range of signal on NIR-RAFI depending on the contribution from the choroidal component. Retinal pigment epithelium atrophy tended to always correspond to high signal on NIR reflectance. Normalizing NIR-RAFI reduced the choroidal component of the signal in regions of atrophy. Quantitative evaluation of RPE atrophy area showed no significant differences between SW-RAFI and normalized NIR-RAFI. Conclusions. Imaging of RPE atrophy using lipofuscin-based AF imaging has become the gold standard. However, this technique involves bright SW lights that are uncomfortable and may accelerate the rate of disease progression in vulnerable retinas. The NIR-RAFI method developed here is a melanin-based alternative that is not absorbed by opsins and bisretinoid moieties, and is comfortable to view. Further development of this method may result in a nonmydriatic and comfortable imaging method to quantify RPE atrophy extent and its expansion rate. PMID:26024124

  8. The effect of lunarlike satellites on the orbital infrared light curves of Earth-analog planets.

    PubMed

    Moskovitz, Nicholas A; Gaidos, Eric; Williams, Darren M

    2009-04-01

    We have investigated the influence of lunarlike satellites on the infrared orbital light curves of Earth-analog extrasolar planets. Such light curves will be obtained by NASA's Terrestrial Planet Finder (TPF) and ESA's Darwin missions as a consequence of repeat observations to confirm the companion status of a putative planet and determine its orbit. We used an energy balance model to calculate disk-averaged infrared (bolometric) fluxes from planet-satellite systems over a full orbital period (one year). The satellites are assumed to lack an atmosphere, have a low thermal inertia like that of the Moon, and span a range of plausible radii. The planets are assumed to have thermal and orbital properties that mimic those of Earth, while their obliquities and orbital longitudes of inferior conjunction remain free parameters. Even if the gross thermal properties of the planet can be independently constrained (e.g., via spectroscopy or visible-wavelength detection of specular glint from a surface ocean), only the largest (approximately Mars-sized) lunarlike satellites can be detected by light curve data from a TPF-like instrument (i.e., one that achieves a photometric signal-to-noise ratio of 10 to 20 at infrared wavelengths). Nondetection of a lunarlike satellite can obfuscate the interpretation of a given system's infrared light curve so that it may resemble a single planet with high obliquity, different orbital longitude of vernal equinox relative to inferior conjunction, and in some cases drastically different thermal characteristics. If the thermal properties of the planet are not independently established, then the presence of a lunarlike satellite cannot be inferred from infrared data, which would thus demonstrate that photometric light curves alone can only be used for preliminary study, and the addition of spectroscopic data will be necessary. PMID:19400731

  9. The effect of lunarlike satellites on the orbital infrared light curves of Earth-analog planets.

    PubMed

    Moskovitz, Nicholas A; Gaidos, Eric; Williams, Darren M

    2009-04-01

    We have investigated the influence of lunarlike satellites on the infrared orbital light curves of Earth-analog extrasolar planets. Such light curves will be obtained by NASA's Terrestrial Planet Finder (TPF) and ESA's Darwin missions as a consequence of repeat observations to confirm the companion status of a putative planet and determine its orbit. We used an energy balance model to calculate disk-averaged infrared (bolometric) fluxes from planet-satellite systems over a full orbital period (one year). The satellites are assumed to lack an atmosphere, have a low thermal inertia like that of the Moon, and span a range of plausible radii. The planets are assumed to have thermal and orbital properties that mimic those of Earth, while their obliquities and orbital longitudes of inferior conjunction remain free parameters. Even if the gross thermal properties of the planet can be independently constrained (e.g., via spectroscopy or visible-wavelength detection of specular glint from a surface ocean), only the largest (approximately Mars-sized) lunarlike satellites can be detected by light curve data from a TPF-like instrument (i.e., one that achieves a photometric signal-to-noise ratio of 10 to 20 at infrared wavelengths). Nondetection of a lunarlike satellite can obfuscate the interpretation of a given system's infrared light curve so that it may resemble a single planet with high obliquity, different orbital longitude of vernal equinox relative to inferior conjunction, and in some cases drastically different thermal characteristics. If the thermal properties of the planet are not independently established, then the presence of a lunarlike satellite cannot be inferred from infrared data, which would thus demonstrate that photometric light curves alone can only be used for preliminary study, and the addition of spectroscopic data will be necessary.

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

    SciTech Connect

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

    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.

  11. Surgical lighting with contrast enhancement based on spectral reflectance comparison and entropy analysis.

    PubMed

    Shen, Junfei; Wang, Huihui; Wu, Yisi; Li, An; Chen, Chi; Zheng, Zhenrong

    2015-10-01

    Surgical light is important for helping the surgeon easily identify specific tissues during an operation. We propose a spectral reflectance comparison model to optimize the light-emitting diode light spectrum in the operating room. An entropy evaluation method, meant specifically for surgical situations, was developed to evaluate images of biological samples. White light was mixed to achieve an optimal spectrum, and images of different tissues under the light were captured and analyzed. Results showed that images obtained with light with an optimal spectrum had a higher contrast than those obtained with a commercial white light of different color temperatures. Optimized surgical light obtained using this simple and effective method could replace the traditional surgical illumination systems.

  12. Surgical lighting with contrast enhancement based on spectral reflectance comparison and entropy analysis

    NASA Astrophysics Data System (ADS)

    Shen, Junfei; Wang, Huihui; Wu, Yisi; Li, An; Chen, Chi; Zheng, Zhenrong

    2015-10-01

    Surgical light is important for helping the surgeon easily identify specific tissues during an operation. We propose a spectral reflectance comparison model to optimize the light-emitting diode light spectrum in the operating room. An entropy evaluation method, meant specifically for surgical situations, was developed to evaluate images of biological samples. White light was mixed to achieve an optimal spectrum, and images of different tissues under the light were captured and analyzed. Results showed that images obtained with light with an optimal spectrum had a higher contrast than those obtained with a commercial white light of different color temperatures. Optimized surgical light obtained using this simple and effective method could replace the traditional surgical illumination systems.

  13. Mid-infrared bi-directional reflectance spectroscopy of impact melt glasses and tektites

    NASA Astrophysics Data System (ADS)

    Morlok, Andreas; Stojic, Aleksandra; Weber, Iris; Hiesinger, Harald; Zanetti, Michael; Helbert, Joern

    2016-11-01

    We have analyzed 14 impact melt glass samples, covering the compositional range from highly felsic to mafic/basaltic, as part of our effort to provide mid-infrared spectra (7-14 μm) for MERTIS (Mercury Radiometer and Thermal Infrared Spectrometer), an instrument onboard of the ESA/JAXA BepiColombo mission. Since Mercury was exposed to many impacts in its history, and impact glasses are also common on other bodies, powders of tektites (Irghizite, Libyan Desert Glass, Moldavite, Muong Nong, Thailandite) and impact glasses (from the Dellen, El'gygytgyn, Lonar, Mien, Mistastin, and Popigai impact structures) were analyzed in four size fractions of (0-25, 25-63, 93-125 and 125-250 μm) from 2.5 to 19 μm in bi-directional reflectance. The characteristic Christiansen Feature (CF) is identified between 7.3 μm (Libyan Desert Glass) and 8.2 μm (Dellen). Most samples show mid-infrared spectra typical of highly amorphous material, dominated by a strong Reststrahlen Band (RB) between 8.9 μm (Libyan Desert Glass) and 10.3 μm (Dellen). Even substantial amounts of mineral fragments hardly affect this general band shape. Comparisons of the SiO2 content representing the felsic/mafic composition of the samples with the CF shows felsic/intermediate glass and tektites forming a big group, and comparatively mafic samples a second one. An additional sign of a highly amorphous state is the lack of features at wavelengths longer than ∼15 μm. The tektites and two impact glasses, Irghizite and El'gygytgyn respectively, have much weaker water features than most of the other impact glasses. For the application in remote sensing, spectral features have to be correlated with compositional characteristics of the materials. The dominating RB in the 7-14 μm range correlates well with the SiO2 content, the Christiansen Feature shows similar dependencies. To distinguish between glass and crystalline phases of the same chemical composition, a comparison between CF the SCFM index (SiO2/(SiO2

  14. Interactions of light with rough dielectric surfaces - Spectral reflectance and polarimetric properties

    NASA Technical Reports Server (NTRS)

    Yon, S. A.; Pieters, C. M.

    1988-01-01

    The nature of the interactions of visible and NIR radiation with the surfaces of rock and mineral samples was investigated by measuring the reflectance and the polarization properties of scattered and reflected light for slab samples of obsidian and fine-grained basalt, prepared to controlled surface roughness. It is shown that the degree to which radiation can penetrate a surface and then scatter back out, an essential criterion for mineralogic determinations based on reflectance spectra, depends not only upon the composition of the material, but also on its physical condition such as sample grain size and surface roughness. Comparison of the experimentally measured reflectance and polarization from smooth and rough slab materials with the predicted models indicates that single Fresnel reflections are responsible for the largest part of the reflected intensity resulting from interactions with the surfaces of dielectric materials; multiple Fresnel reflections are much less important for such surfaces.

  15. Infrared

    NASA Astrophysics Data System (ADS)

    Vollmer, M.

    2013-11-01

    'Infrared' is a very wide field in physics and the natural sciences which has evolved enormously in recent decades. It all started in 1800 with Friedrich Wilhelm Herschel's discovery of infrared (IR) radiation within the spectrum of the Sun. Thereafter a few important milestones towards widespread use of IR were the quantitative description of the laws of blackbody radiation by Max Planck in 1900; the application of quantum mechanics to understand the rotational-vibrational spectra of molecules starting in the first half of the 20th century; and the revolution in source and detector technologies due to micro-technological breakthroughs towards the end of the 20th century. This has led to much high-quality and sophisticated equipment in terms of detectors, sources and instruments in the IR spectral range, with a multitude of different applications in science and technology. This special issue tries to focus on a few aspects of the astonishing variety of different disciplines, techniques and applications concerning the general topic of infrared radiation. Part of the content is based upon an interdisciplinary international conference on the topic held in 2012 in Bad Honnef, Germany. It is hoped that the information provided here may be useful for teaching the general topic of electromagnetic radiation in the IR spectral range in advanced university courses for postgraduate students. In the most general terms, the infrared spectral range is defined to extend from wavelengths of 780 nm (upper range of the VIS spectral range) up to wavelengths of 1 mm (lower end of the microwave range). Various definitions of near, middle and far infrared or thermal infrared, and lately terahertz frequencies, are used, which all fall in this range. These special definitions often depend on the scientific field of research. Unfortunately, many of these fields seem to have developed independently from neighbouring disciplines, although they deal with very similar topics in respect of the

  16. Enhanced single seed trait predictions in soybean (Glycine max) and robust calibration model transfer with near infrared reflectance spectroscopy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Single seed near infrared reflectance (NIR) spectroscopy predicts soybean (Glycine max) seed quality traits of moisture, oil, and protein. We tested the accuracy of transferring calibrations between different single seed NIR analyzers of the same design by collecting NIR spectra and analytical trait...

  17. Secondary cell wall development in cotton fibers as examined with attenuated total reflection Fourier transform infrared spectroscopy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cotton fibers harvested at 18, 20, 24, 28, 32, 36 and 40 days after flowering were examined using attenuated total reflection Fourier transform-infrared (ATR FT-IR) spectroscopy. The selected harvesting points coincide with secondary cell wall (SCW) development in the fibers. Progressive but moderat...

  18. Strong visible light emission from well-aligned multiwalled carbon nanotube films under infrared laser irradiation

    SciTech Connect

    Zhang Yong; Gong Tao; Liu Wenjin; Zhang Xianfeng; Chang Jianguo; Wang Kunlin; Wu Dehai

    2005-10-24

    We report strong and brilliant visible light emission from well-aligned multiwalled carbon nanotube (AMWNT) films under infrared (IR) laser irradiation with wavelength at 1.06 and 10.6 {mu}m, respectively. The AMWNT film shows a high durability against laser irradiation and achieved a conversion from IR laser to visible light. It is a good candidate for optical converter. Light emission spectra versus different wavelengths and various powers were found to have similar line shapes. It could be explained as combination of laser-induced photoluminescence and resistive heating.

  19. Visible and Infra-red Light Emission in Boron-Doped Wurtzite Silicon Nanowires

    PubMed Central

    Fabbri, Filippo; Rotunno, Enzo; Lazzarini, Laura; Fukata, Naoki; Salviati, Giancarlo

    2014-01-01

    Silicon, the mainstay semiconductor in microelectronic circuitry, is considered unsuitable for optoelectronic applications owing to its indirect electronic band gap, which limits its efficiency as a light emitter. Here we show the light emission properties of boron-doped wurtzite silicon nanowires measured by cathodoluminescence spectroscopy at room temperature. A visible emission, peaked above 1.5 eV, and a near infra-red emission at 0.8 eV correlate respectively to the direct transition at the Γ point and to the indirect band-gap of wurtzite silicon. We find additional intense emissions due to boron intra-gap states in the short wavelength infra-red range. We present the evolution of the light emission properties as function of the boron doping concentration and the growth temperature. PMID:24398782

  20. Visible and infra-red light emission in boron-doped wurtzite silicon nanowires.

    PubMed

    Fabbri, Filippo; Rotunno, Enzo; Lazzarini, Laura; Fukata, Naoki; Salviati, Giancarlo

    2014-01-08

    Silicon, the mainstay semiconductor in microelectronic circuitry, is considered unsuitable for optoelectronic applications owing to its indirect electronic band gap, which limits its efficiency as a light emitter. Here we show the light emission properties of boron-doped wurtzite silicon nanowires measured by cathodoluminescence spectroscopy at room temperature. A visible emission, peaked above 1.5 eV, and a near infra-red emission at 0.8 eV correlate respectively to the direct transition at the Γ point and to the indirect band-gap of wurtzite silicon. We find additional intense emissions due to boron intra-gap states in the short wavelength infra-red range. We present the evolution of the light emission properties as function of the boron doping concentration and the growth temperature.

  1. Joint FDTD-Optical/FEM-Electrical Numerical Simulation of Reflection-Type Subwavelength-Microstructure InSb Infrared Focal-Plane Arrays

    NASA Astrophysics Data System (ADS)

    He, J. L.; Hu, W. D.; Ye, Z. H.; Lv, Y. Q.; Chen, X. S.; Lu, W.

    2016-09-01

    The design of a reflection-type subwavelength microstructure has been numerically investigated to concentrate incident light onto pixels for improved photoresponse of InSb infrared focal-plane arrays. Compared with traditional microlenses placed on top of the detector substrate, this reflection-type microstructure is better suited for extremely small pixel pitches. The structure is simulated using a joint numerical method combining the finite-difference time-domain method based on Maxwell's curl equations and the finite-element method based on the Poisson and continuity equations. The results show that this advanced design could effectively improve device response without sacrificing crosstalk. The optimal structure parameters are obtained theoretically, with response increase of approximately 100%.

  2. Diffuse reflectance infrared spectroscopic identification of dispersant/particle bonding mechanisms in functional inks.

    PubMed

    Deiner, L Jay; Farjami, Elaheh

    2015-05-08

    In additive manufacturing, or 3D printing, material is deposited drop by drop, to create micron to macroscale layers. A typical inkjet ink is a colloidal dispersion containing approximately ten components including solvent, the nano to micron scale particles which will comprise the printed layer, polymeric dispersants to stabilize the particles, and polymers to tune layer strength, surface tension and viscosity. To rationally and efficiently formulate such an ink, it is crucial to know how the components interact. Specifically, which polymers bond to the particle surfaces and how are they attached? Answering this question requires an experimental procedure that discriminates between polymer adsorbed on the particles and free polymer. Further, the method must provide details about how the functional groups of the polymer interact with the particle. In this protocol, we show how to employ centrifugation to separate particles with adsorbed polymer from the rest of the ink, prepare the separated samples for spectroscopic measurement, and use Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFTS) for accurate determination of dispersant/particle bonding mechanisms. A significant advantage of this methodology is that it provides high level mechanistic detail using only simple, commonly available laboratory equipment. This makes crucial data available to almost any formulation laboratory. The method is most useful for inks composed of metal, ceramic, and metal oxide particles in the range of 100 nm or greater. Because of the density and particle size of these inks, they are readily separable with centrifugation. Further, the spectroscopic signatures of such particles are easy to distinguish from absorbed polymer. The primary limitation of this technique is that the spectroscopy is performed ex-situ on the separated and dried particles as opposed to the particles in dispersion. However, results from attenuated total reflectance spectra of the wet separated

  3. Diffuse reflectance infrared spectroscopic identification of dispersant/particle bonding mechanisms in functional inks.

    PubMed

    Deiner, L Jay; Farjami, Elaheh

    2015-01-01

    In additive manufacturing, or 3D printing, material is deposited drop by drop, to create micron to macroscale layers. A typical inkjet ink is a colloidal dispersion containing approximately ten components including solvent, the nano to micron scale particles which will comprise the printed layer, polymeric dispersants to stabilize the particles, and polymers to tune layer strength, surface tension and viscosity. To rationally and efficiently formulate such an ink, it is crucial to know how the components interact. Specifically, which polymers bond to the particle surfaces and how are they attached? Answering this question requires an experimental procedure that discriminates between polymer adsorbed on the particles and free polymer. Further, the method must provide details about how the functional groups of the polymer interact with the particle. In this protocol, we show how to employ centrifugation to separate particles with adsorbed polymer from the rest of the ink, prepare the separated samples for spectroscopic measurement, and use Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFTS) for accurate determination of dispersant/particle bonding mechanisms. A significant advantage of this methodology is that it provides high level mechanistic detail using only simple, commonly available laboratory equipment. This makes crucial data available to almost any formulation laboratory. The method is most useful for inks composed of metal, ceramic, and metal oxide particles in the range of 100 nm or greater. Because of the density and particle size of these inks, they are readily separable with centrifugation. Further, the spectroscopic signatures of such particles are easy to distinguish from absorbed polymer. The primary limitation of this technique is that the spectroscopy is performed ex-situ on the separated and dried particles as opposed to the particles in dispersion. However, results from attenuated total reflectance spectra of the wet separated

  4. Total reflection infrared spectroscopy of water-ice and frozen aqueous NaCl solutions

    SciTech Connect

    Walker, Rachel L.; Searles, Keith; Willard, Jesse A.; Michelsen, Rebecca R. H.

    2013-12-28

    Liquid-like and liquid water at and near the surface of water-ice and frozen aqueous sodium chloride films were observed using attenuated total reflection infrared spectroscopy (ATR-IR). The concentration of NaCl ranged from 0.0001 to 0.01 M and the temperature varied from the melting point of water down to 256 K. The amount of liquid brine at the interface of the frozen films with the germanium ATR crystal increased with salt concentration and temperature. Experimental spectra are compared to reflection spectra calculated for a simplified morphology of a uniform liquid layer between the germanium crystal and the frozen film. This morphology allows for the amount of liquid observed in an experimental spectrum to be converted to the thickness of a homogenous layer with an equivalent amount of liquid. These equivalent thickness ranges from a nanometer for water-ice at 260 K to 170 nm for 0.01 M NaCl close to the melting point. The amounts of brine observed are over an order of magnitude less than the total liquid predicted by equilibrium thermodynamic models, implying that the vast majority of the liquid fraction of frozen solutions may be found in internal inclusions, grain boundaries, and the like. Thus, the amount of liquid and the solutes dissolved in them that are available to react with atmospheric gases on the surfaces of snow and ice are not well described by thermodynamic equilibrium models which assume the liquid phase is located entirely at the surface.

  5. Analysis of total oil and fatty acids composition by near infrared reflectance spectroscopy in edible nuts

    NASA Astrophysics Data System (ADS)

    Kandala, Chari V.; Sundaram, Jaya

    2014-10-01

    Near Infrared (NIR) Reflectance spectroscopy has established itself as an important tool in quantifying water and oil present in various food materials. It is rapid and nondestructive, easier to use, and does not require processing the samples with corrosive chemicals that would render them non-edible. Earlier, the samples had to be ground into powder form before making any measurements. With the development of new soft ware packages, NIR techniques could now be used in the analysis of intact grain and nuts. While most of the commercial instruments presently available work well with small grain size materials such as wheat and corn, the method present here is suitable for large kernel size products such as shelled or in-shell peanuts. Absorbance spectra were collected from 400 nm to 2500 nm using a NIR instrument. Average values of total oil contents (TOC) of peanut samples were determined by standard extraction methods, and fatty acids were determined using gas chromatography. Partial least square (PLS) analysis was performed on the calibration set of absorption spectra, and models were developed for prediction of total oil and fatty acids. The best model was selected based on the coefficient of determination (R2), Standard error of prediction (SEP) and residual percent deviation (RPD) values. Peanut samples analyzed showed RPD values greater than 5.0 for both absorbance and reflectance models and thus could be used for quality control and analysis. Ability to rapidly and nondestructively measure the TOC, and analyze the fatty acid composition, will be immensely useful in peanut varietal improvement as well as in the grading process of grain and nuts.

  6. Influence of the linear magneto-electric effect on the lateral shift of light reflected from a magneto-electric film

    NASA Astrophysics Data System (ADS)

    Dadoenkova, Yu S.; Bentivegna, F. F. L.; Dadoenkova, N. N.; Petrov, R. V.; Lyubchanskii, I. L.; Bichurin, M. I.

    2016-08-01

    We present a theoretical investigation of the lateral shift of an infrared light beam reflected from a magnetic film deposited on a non-magnetic dielectric substrate, taking into account the linear magneto-electric interaction in the magnetic film. We use the stationary phase method to evaluate the lateral shift. It is shown that the magneto-electric coupling leads to a six-fold enhancement of the lateral shift amplitude of a p-(s-) polarized incident beam reflected into a s-(p-) polarized beam. A reversal of the magnetization in the film leads to a nonreciprocal sign change of the lateral shift.

  7. Absorption and electrochromic modulation of near-infrared light: realized by tungsten suboxide

    NASA Astrophysics Data System (ADS)

    Li, Guilian; Zhang, Shouhao; Guo, Chongshen; Liu, Shaoqin

    2016-05-01

    In the present study, needle-like tungsten suboxide W18O49 nanocrystals were fabricated as the optical active substance to realize the aim of optical control of near-infrared light. The W18O49 nanocrystals were selected in this regard due to their unique optical performance. As revealed by the powder absorption result, the needle-like W18O49 nanocrystals show strong and wide photoabsorption in the entire near infrared region of 780-2500 nm, from which thin films with the W18O49 nanocrystal coating thus benefits and can strongly shield off almost all near infrared irradiation, whereas transmitting the majority of visible light. To make it more tunable, the W18O49 nanocrystals were finally assembled onto an ITO glass via the layer-by-layer strategy for later electrochromic investigation. The nanostructured architectures of the W18O49 nanocrystal electrochromic films exhibit high contrast, faster switching response, higher coloration efficiencies (150 cm2 C-1 at 650 nm and 255 cm2 C-1 at 1300 nm), better long-term redox switching stability (reversibility of 98% after 500 cycles) and wide electrochromic spectrum coverage of both the visible and infrared regions.In the present study, needle-like tungsten suboxide W18O49 nanocrystals were fabricated as the optical active substance to realize the aim of optical control of near-infrared light. The W18O49 nanocrystals were selected in this regard due to their unique optical performance. As revealed by the powder absorption result, the needle-like W18O49 nanocrystals show strong and wide photoabsorption in the entire near infrared region of 780-2500 nm, from which thin films with the W18O49 nanocrystal coating thus benefits and can strongly shield off almost all near infrared irradiation, whereas transmitting the majority of visible light. To make it more tunable, the W18O49 nanocrystals were finally assembled onto an ITO glass via the layer-by-layer strategy for later electrochromic investigation. The nanostructured

  8. [Attenuated Total Reflection Infrared Spectroscopy for Degradation Profile of High Density Polyethylene after Weathering Aging].

    PubMed

    Guo, Jun-jun; Yan, Hua; Bao, He-bin; Wang, Xue-mei; Hu, Zhi-de; Yang, Jian-jian

    2015-06-01

    High density polyethylene (HDPE) was widely used as rotational packaging case in the material reserve field. The chemical changes of HDPE, exposed to particular climatic conditions of tropic marine atmosphere for one year-long in Wanning Hainan, were elucidated by the attenuated total reflection infrared spectroscopy (ATR-FTIR). The structural changes were studied qualitatively, mainly from the polymeric chain breaking, branching and oxidation to distinguish the degradation profile. The variations of crystallinity & carbonyl index were also studied quantitatively according to the characteristic peaks intensity & area ratio. Finally, the relationships between structural changes and mechanical properties were investigated. The results showed that the polymeric chain breaking & branching play a leading role before 3 months in the aging progress. Then oxidation phenomena gradually takes place during 3-6 months. The chain branching & oxidation were predominant factors after 6 months. Nine months later, the oxidation was saturated gradually. Furthermore, the aging process is positively correlated to the temperature and irradiation. After 12 months aging, the carbonyl index increased by 112 times and crystallinity was 10% higher than before. The tensile/bending modulus deceased faster than tensile/bending strength of HDPE. The linear degree of tensile modulus and carbonyl index was 0.97. The degree of linearity of tensile strength and crystallinity calculated by feature bands (720-730 cm(-1)) was 0.96. It showed that the mechanical properties of HDPE can be speculated from the structural changes by ATR-FTIR. PMID:26601359

  9. Characterization of early stage cartilage degradation using diffuse reflectance near infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Brown, C. P.; Jayadev, C.; Glyn-Jones, S.; Carr, A. J.; Murray, D. W.; Price, A. J.; Gill, H. S.

    2011-04-01

    Interest in localized and early stage treatment technologies for joint conditions such as osteoarthritis is growing rapidly. It has therefore become important to develop objective measures capable of characterizing the earliest (non-visible) changes associated with degeneration to aid treatment procedures. In addition to assessing tissue before treatment, it is further important to develop an effective, non-destructive means of monitoring post-treatment tissue healing, and of providing the high-quality data needed for trials of developing treatment methods. To investigate its ability to detect the early stages of degeneration in cartilage-on-bone, diffuse reflectance near infrared spectroscopy was applied to normal and osteoarthritic joints. A discriminating function was developed to relate absorbance peaks of interest and track degradation around focal osteoarthritic defects. The function could distinguish between normal and degraded tissue (100% separation of normal tissue from that within 25 mm of a defect) and between different stages of osteoarthritic progression (p < 0.05). This technique allows simple, practical and non-destructive assessment of component-level properties over the full depth of the tissue. It has the potential to increase our understanding of the underlying etiologic and pathogenic processes in early stage degeneration, to assist classification and the development of new treatment methods.

  10. Attenuated total reflectance Fourier transform infrared spectroscopy method to differentiate between normal and cancerous breast cells.

    PubMed

    Lane, Randy; See, Seong S

    2012-09-01

    Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) is used to find the structural differences between cancerous breast cells (MCF-7 line) and normal breast cells (MCF-12F line). Gold nanoparticles were prepared and the hydrodynamic diameter of the gold nanoparticles found to be 38.45 nm. The Gold nanoparticles were exposed to both MCF-7 and MCF-12F cells from lower to higher concentrations. Spectroscopic studies founds nanoparticles were within the cells, and increasing the nanoparticles concentration inside the cells also resulted in sharper IR peaks as a result of localized surface Plasmon resonance. Asymmetric and symmetric stretching and bending vibrations between phosphate, COO-, CH2 groups were found to give negative shifts in wavenumbers and a decrease in peak intensities when going from noncancerous to cancerous cells. Cellular proteins produced peak assignments at the 1542 and 1644 cm(-1) wavenumbers which were attributed to the amide I and amide II bands of the polypeptide bond of proteins. Significant changes were found in the peak intensities between the cell lines in the spectrum range from 2854-2956 cm(-1). Results show that the concentration range of gold nanoparticles used in this research showed no significant changes in cell viability in either cell line. Therefore, we believe ATR-FTIR and gold nanotechnology can be at the forefront of cancer diagnosis for some time to come.

  11. Detection of sibutramine in adulterated dietary supplements using attenuated total reflectance-infrared spectroscopy.

    PubMed

    Deconinck, E; Cauwenbergh, T; Bothy, J L; Custers, D; Courselle, P; De Beer, J O

    2014-11-01

    Sibutramine is one of the most occurring adulterants encountered in dietary supplements with slimming as indication. These adulterated dietary supplements often contain a herbal matrix. When customs intercept these kind of supplements it is almost impossible to discriminate between the legal products and the adulterated ones, due to misleading packaging. Therefore in most cases these products are confiscated and send to laboratories for analysis. This results inherently in the confiscation of legal, non-adulterated products. Therefore there is a need for easy to use equipment and techniques to perform an initial screening of samples. Attenuated total reflectance-infrared (ATR-IR) spectroscopy was evaluated for the detection of sibutramine in adulterated dietary supplements. Data interpretation was performed using different basic chemometric techniques. It was found that the use of ATR-IR combined with the k-Nearest Neighbours (k-NN) was able to detect all adulterated dietary supplements in an external test set and this with a minimum of false positive results. This means that a small amount of legal products will still be confiscated and analyzed in a laboratory to be found negative, but no adulterated samples will pass the initial ATR-IR screening.

  12. Application of near infrared reflectance spectroscopy to predict meat and meat products quality: A review.

    PubMed

    Prieto, N; Roehe, R; Lavín, P; Batten, G; Andrés, S

    2009-10-01

    Over the past three decades, near infrared reflectance (NIR) spectroscopy has been proved to be one of the most efficient and advanced tools for the estimation of quality attributes in meat and meat products. This review focuses on the use of NIR spectroscopy to predict different meat properties, considering the literature published mainly in the last decade. Firstly, the potential of NIR to predict chemical composition (crude protein, intramuscular fat, moisture/dry matter, ash, gross energy, myoglobin and collagen), technological parameters (pH value; L*, a*, b* colour values; water holding capacity; Warner-Bratzler and slice shear force) and sensory attributes (colour, shape, marbling, odour, flavour, juiciness, tenderness or firmness) are reviewed. Secondly, the usefulness of NIR for classification into meat quality grades is presented and thirdly its potential application in the industry is shown. The review indicates that NIR showed high potential to predict chemical meat properties and to categorize meat into quality classes. In contrast, NIR showed limited ability for estimating technological and sensory attributes, which may be mainly due to the heterogeneity of the meat samples and their preparation, the low precision of the reference methods and the subjectivity of assessors in taste panels. Hence, future work to standardize sample preparation and increase the accuracy of reference methods is recommended to improve NIR ability to predict those technological and sensory characteristics. In conclusion, the review shows that NIR has a considerable potential to predict simultaneously numerous meat quality criteria. PMID:20416766

  13. Phase transitions of amorphous solid acetone in confined geometry investigated by reflection absorption infrared spectroscopy.

    PubMed

    Shin, Sunghwan; Kang, Hani; Kim, Jun Soo; Kang, Heon

    2014-11-26

    We investigated the phase transformations of amorphous solid acetone under confined geometry by preparing acetone films trapped in amorphous solid water (ASW) or CCl4. Reflection absorption infrared spectroscopy (RAIRS) and temperature-programmed desorption (TPD) were used to monitor the phase changes of the acetone sample with increasing temperature. An acetone film trapped in ASW shows an abrupt change in the RAIRS features of the acetone vibrational bands during heating from 80 to 100 K, which indicates the transformation of amorphous solid acetone to a molecularly aligned crystalline phase. Further heating of the sample to 140 K produces an isotropic solid phase, and eventually a fluid phase near 157 K, at which the acetone sample is probably trapped in a pressurized, superheated condition inside the ASW matrix. Inside a CCl4 matrix, amorphous solid acetone crystallizes into a different, isotropic structure at ca. 90 K. We propose that the molecularly aligned crystalline phase formed in ASW is created by heterogeneous nucleation at the acetone-water interface, with resultant crystal growth, whereas the isotropic crystalline phase in CCl4 is formed by homogeneous crystal growth starting from the bulk region of the acetone sample.

  14. Attenuated total reflectance fourier transform infrared analysis of fly ash geopolymer gel aging.

    PubMed

    Rees, Catherine A; Provis, John L; Lukey, Grant C; van Deventer, Jannie S J

    2007-07-17

    Structural changes in fly ash geopolymers activated with different sodium hydroxide and silicate concentrations are investigated using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy over a period of 200 days. A strong correlation is found between the concentration of silicate monomer in the activating solution and the position of the main Si-O-T stretching band in the FTIR spectrum, which gives an indication of the relative changes in the gel Si/Al ratio. The FTIR spectra of geopolymer samples with activating solution concentrations of up to 1.2 M SiO2 indicate that an Al-rich gel forms before the final gel composition is reached. The time required for the system to reach a steady gel composition depends on the silicate activating solution concentration and speciation. Geopolymers activated with solutions containing predominantly high-order silicate species rapidly reach a steady gel composition without first forming an Al-rich gel. A minimum silicate monomer concentration of approximately 0.6 M is required to shift the geopolymer synthesis mechanism from hydroxide activation to silicate activation. Silicate speciation in the activating solutions also affects zeolite formation and geopolymer microstructures, with a more homogeneous microstructure and less zeolite formation observed at a higher SiO2 content.

  15. [Discriminant Analysis of Lavender Essential Oil by Attenuated Total Reflectance Infrared Spectroscopy].

    PubMed

    Tang, Jun; Wang, Qing; Tong, Hong; Liao, Xiang; Zhang, Zheng-fang

    2016-03-01

    This work aimed to use attenuated total reflectance Fourier transform infrared spectroscopy to identify the lavender essential oil by establishing a Lavender variety and quality analysis model. So, 96 samples were tested. For all samples, the raw spectra were pretreated as second derivative, and to determine the 1 750-900 cm(-1) wavelengths for pattern recognition analysis on the basis of the variance calculation. The results showed that principal component analysis (PCA) can basically discriminate lavender oil cultivar and the first three principal components mainly represent the ester, alcohol and terpenoid substances. When the orthogonal partial least-squares discriminant analysis (OPLS-DA) model was established, the 68 samples were used for the calibration set. Determination coefficients of OPLS-DA regression curve were 0.959 2, 0.976 4, and 0.958 8 respectively for three varieties of lavender essential oil. Three varieties of essential oil's the root mean square error of prediction (RMSEP) in validation set were 0.142 9, 0.127 3, and 0.124 9, respectively. The discriminant rate of calibration set and the prediction rate of validation set had reached 100%. The model has the very good recognition capability to detect the variety and quality of lavender essential oil. The result indicated that a model which provides a quick, intuitive and feasible method had been built to discriminate lavender oils. PMID:27400512

  16. [Near-infrared reflectance spectroscopy analytic model established for the IVDMD of Cichorium intybus L].

    PubMed

    Hu, Chao; Bai, Shi-qie; Zhang, Yu; Yan, Jia-jun; You, Ming-hong; Li, Da-xu; Bai, Ling; Zhang Jin

    2014-08-01

    Chicory (Cichorium intybus L.) is a new type of forage grasses of high yield and quality with a great value of popularization and utilization. In vitro dry matter digestibility (IVDMD) is one of the important indicators of the nutritional value of forage evaluation. For the study of establishment of Chicory IVDMD NIRS quantitative analysis model, seventy-two species with different genotypes, different growth stages of 204 chicory samples of aboveground material were collected, and by Fourier transform near-infrared diffuse reflectance spectroscopy, through the use of different regression algorithms, can comparing different spectral ranges and spectral pretreatment methods, eight chicory IVDMD NIRS calibration models were established, and the best calibration model parameters were chosen. Its calibration coefficient of determination (Ri) and external validation coefficient of determination (Rval2) were 0.95317 and 0.90455, calibration standard deviation (RMSEC) and predictive standard deviation (RMSEP) was 1.977 99% and 2.008 82%, and the correlation coefficient (r) between predicted values and chemical values was 0.95108. The results show that using NIRS to determine chicory IVDMD is feasible, and provided a rapid analysis method for the determination IVDMD of chicory. PMID:25508718

  17. Rapid analysis of diesel fuel properties by near infrared reflectance spectra

    NASA Astrophysics Data System (ADS)

    Feng, Fei; Wu, Qiongshui; Zeng, Libo

    2015-10-01

    In this study, based on near infrared reflectance spectra (NIRS) of 441 samples from four diesel groups (-10# diesel, -20# diesel, -35# diesel, and inferior diesel), three spectral analysis models were established by using partial least square (PLS) regression for the six diesel properties (i.e., boiling point, cetane number, density, freezing temperature, total aromatics, and viscosity) respectively. In model 1, all the samples were processed as a whole; in model 2 and model 3, samples were firstly classified into four groups by least square support vector machine (LS-SVM), and then partial least square regression models were applied to each group and each property. The main difference between model 2 and model 3 was that the latter used the direct orthogonal signal correction (DOSC), which helped to get rid of the non-relevant variation in the spectra. Comparing these three models, two results could be concluded: (1) models for grouped samples had higher precision and smaller prediction error; (2) models with DOSC after LS-SVM classification yielded a considerable error reduction compared to models without DOSC.

  18. Quantifying amyloid fibrils in protein mixtures via infrared attenuated-total-reflection spectroscopy.

    PubMed

    Wang, Pei; Bohr, Wilhelm; Otto, Markus; Danzer, Karin M; Mizaikoff, Boris

    2015-05-01

    Amyloid aggregation of proteins is usually associated with amyloid diseases. A distinct feature of protein aggregation is the increase of crossed β-sheet structures. Infrared attenuated-total-reflectance (IR-ATR) spectroscopy is a sensitive optical technique that has the potential to provide secondary structure characteristics of proteins even in complex biological samples. In this study we report the analysis of secondary structures of proteins, using the amide I band for the detection and quantification of amyloid fibrils in protein mixtures by use of IR-ATR techniques, at comparatively low sample concentrations. From the experimental results, an analytical model of the relationship between the IR spectra of protein mixtures and the individual mixture components was established using spectral-deconvolution procedures and curve-fitting methods. On the basis of this model, four ratios were shown to provide direct information on amyloid aggregated fibrils via the increase of crossed β-sheet structures in protein-mixture samples. In conclusion, this study confirms the utility of IR spectroscopy for analyzing protein mixtures and for identifying amyloid fibril information within such complex multi-component samples.

  19. [Attenuated Total Reflection Infrared Spectroscopy for Degradation Profile of High Density Polyethylene after Weathering Aging].

    PubMed

    Guo, Jun-jun; Yan, Hua; Bao, He-bin; Wang, Xue-mei; Hu, Zhi-de; Yang, Jian-jian

    2015-06-01

    High density polyethylene (HDPE) was widely used as rotational packaging case in the material reserve field. The chemical changes of HDPE, exposed to particular climatic conditions of tropic marine atmosphere for one year-long in Wanning Hainan, were elucidated by the attenuated total reflection infrared spectroscopy (ATR-FTIR). The structural changes were studied qualitatively, mainly from the polymeric chain breaking, branching and oxidation to distinguish the degradation profile. The variations of crystallinity & carbonyl index were also studied quantitatively according to the characteristic peaks intensity & area ratio. Finally, the relationships between structural changes and mechanical properties were investigated. The results showed that the polymeric chain breaking & branching play a leading role before 3 months in the aging progress. Then oxidation phenomena gradually takes place during 3-6 months. The chain branching & oxidation were predominant factors after 6 months. Nine months later, the oxidation was saturated gradually. Furthermore, the aging process is positively correlated to the temperature and irradiation. After 12 months aging, the carbonyl index increased by 112 times and crystallinity was 10% higher than before. The tensile/bending modulus deceased faster than tensile/bending strength of HDPE. The linear degree of tensile modulus and carbonyl index was 0.97. The degree of linearity of tensile strength and crystallinity calculated by feature bands (720-730 cm(-1)) was 0.96. It showed that the mechanical properties of HDPE can be speculated from the structural changes by ATR-FTIR.

  20. Detection of sibutramine in adulterated dietary supplements using attenuated total reflectance-infrared spectroscopy.

    PubMed

    Deconinck, E; Cauwenbergh, T; Bothy, J L; Custers, D; Courselle, P; De Beer, J O

    2014-11-01

    Sibutramine is one of the most occurring adulterants encountered in dietary supplements with slimming as indication. These adulterated dietary supplements often contain a herbal matrix. When customs intercept these kind of supplements it is almost impossible to discriminate between the legal products and the adulterated ones, due to misleading packaging. Therefore in most cases these products are confiscated and send to laboratories for analysis. This results inherently in the confiscation of legal, non-adulterated products. Therefore there is a need for easy to use equipment and techniques to perform an initial screening of samples. Attenuated total reflectance-infrared (ATR-IR) spectroscopy was evaluated for the detection of sibutramine in adulterated dietary supplements. Data interpretation was performed using different basic chemometric techniques. It was found that the use of ATR-IR combined with the k-Nearest Neighbours (k-NN) was able to detect all adulterated dietary supplements in an external test set and this with a minimum of false positive results. This means that a small amount of legal products will still be confiscated and analyzed in a laboratory to be found negative, but no adulterated samples will pass the initial ATR-IR screening. PMID:25173110

  1. Attenuated total reflection (ATR) Fourier transform infrared spectroscopy of dimyristoyl phosphatidylserine-cholesterol mixtures.

    PubMed

    Bach, D; Miller, I R

    2001-10-01

    Mixtures of cholesterol with dimyristoyl phosphatidylserine or deuterated dimyristoyl phosphatidylserine were investigated by polarized and non polarized attenuated total reflection (ATR) Fourier transform infrared (FTIR) Spectroscopy. From polarized spectra the dichroic ratios of various vibrations as a function of cholesterol were calculated. Dichroic ratios of methylene vibration (CH(2)) 2934 cm(-1) of cholesterol decreases with increase of cholesterol concentration leveling off in the region where cholesterol phase separation takes place. The orientation of deuterated methylene (CD(2)) symmetric and asymmetric bands of the deuterated dimyristoyl phosphatidylserine is influenced little by cholesterol. In the polar region of dimyristoyl phosphatidylserine no effect of cholesterol on the dichroic ratios of carbonyl (C==O) and asymmetric phosphate (PO(2)(-)) vibrations were detected. For nonpolarized spectra the broad bands in the polar region of the phospholipid were deconvoluted. The carbonyl band (C==O) in pure dimyristoyl phosphatidylserine is composed of five bands; in the presence of increasing concentrations of cholesterol conformational change of these vibrations takes place evolving into one predominant band. Similar conformational change takes place in the presence of 75 molecules water/molecule DMPS. For the asymmetric phosphate band very small shifts due to interaction with cholesterol were detected.

  2. Measurement of evapotranspiration with combined reflective and thermal infrared radiance observations

    NASA Technical Reports Server (NTRS)

    Hope, Allen S.

    1993-01-01

    The broad goal of the research summarized in this report was 'To facilitate the evaluation of regional evapotranspiration (ET) through the combined use of solar reflective and thermal infrared radiance observations.' The specific objectives stated by Goward and Hope (1986) were to: (1) investigate the nature of the relationship between surface temperature (T(sub S)) and the normalized difference vegetation index (NDVI) and develop an understanding of this relationship in terms of energy exchange processes, particularly latent flux heat (LE); (2) develop procedures to estimate large area LE using combined T(sub S) and NDVI observations obtained from AVHRR data; and (3) determine whether measurements derived from satellite observations relate directly to measurements made at the surface or from aircraft platforms. Both empirical and modeling studies were used to develop an understanding of the T(sub S)-NDVI relationship. Most of the modeling was based on the Tergra model as originally proposed by Goward. This model, and modified versions developed in this project, simulates the flows of water and energy in the soil-plant-atmosphere system using meteorological, soil and vegetation inputs. Model outputs are the diurnal course of soil moisture, T(sub S), LE and the other individual components of the surface energy balance.

  3. Rapid Assessment of Mineral Concentration in Meadow Grasses by Near Infrared Reflectance Spectroscopy

    PubMed Central

    Ward, Alastair; Nielsen, Anne Lisbeth; Møller, Henrik

    2011-01-01

    A near infrared reflectance spectroscopy (NIRS) method for rapid determination of nitrogen, phosphorous and potassium in diverse meadow grasses was developed with a view towards utilizing this material for biogas production and organic fertilizer. NIRS spectra between 12,000 cm−1 and 4,000 cm−1 were used. When validated on samples from different years to those used for the calibration set, the NIRS prediction of nitrogen was considered moderately useful with R2 = 0.77, ratio of standard error of prediction to reference data range (RER) of 9.32 and ratio of standard error of prediction to standard deviation of reference data (RPD) of 2.33. Prediction of potassium was less accurate, with R2 = 0.77, RER of 6.56 and RPD of 1.45, whilst prediction of phosphorous was not considered accurate enough to be of any practical use. This work is of interest from the point of view of both the removal of excess nutrients from formerly intensively farmed areas and also for assessing the plant biomass suitability for conversion into carbon neutral energy through biogas production. PMID:22163878

  4. Forensic Hair Differentiation Using Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Spectroscopy.

    PubMed

    Manheim, Jeremy; Doty, Kyle C; McLaughlin, Gregory; Lednev, Igor K

    2016-07-01

    Hair and fibers are common forms of trace evidence found at crime scenes. The current methodology of microscopic examination of potential hair evidence is absent of statistical measures of performance, and examiner results for identification can be subjective. Here, attenuated total reflection (ATR) Fourier transform-infrared (FT-IR) spectroscopy was used to analyze synthetic fibers and natural hairs of human, cat, and dog origin. Chemometric analysis was used to differentiate hair spectra from the three different species, and to predict unknown hairs to their proper species class, with a high degree of certainty. A species-specific partial least squares discriminant analysis (PLSDA) model was constructed to discriminate human hair from cat and dog hairs. This model was successful in distinguishing between the three classes and, more importantly, all human samples were correctly predicted as human. An external validation resulted in zero false positive and false negative assignments for the human class. From a forensic perspective, this technique would be complementary to microscopic hair examination, and in no way replace it. As such, this methodology is able to provide a statistical measure of confidence to the identification of a sample of human, cat, and dog hair, which was called for in the 2009 National Academy of Sciences report. More importantly, this approach is non-destructive, rapid, can provide reliable results, and requires no sample preparation, making it of ample importance to the field of forensic science. PMID:27412186

  5. Quantitative orientation measurements in thin lipid films by attenuated total reflection infrared spectroscopy.

    PubMed Central

    Picard, F; Buffeteau, T; Desbat, B; Auger, M; Pézolet, M

    1999-01-01

    Quantitative orientation measurements by attenuated total reflectance (ATR) infrared spectroscopy require the accurate knowledge of the dichroic ratio and of the mean-square electric fields along the three axes of the ATR crystal. In this paper, polarized ATR spectra of single supported bilayers of the phospholipid dimyristoylphosphatidic acid covered by either air or water have been recorded and the dichroic ratio of the bands due to the methylene stretching vibrations has been calculated. The mean-square electric field amplitudes were calculated using three formalisms, namely the Harrick thin film approximation, the two-phase approximation, and the thickness- and absorption-dependent one. The results show that for dry bilayers, the acyl chain tilt angle varies with the formalism used, while no significant variations are observed for the hydrated bilayers. To test the validity of the different formalisms, s- and p-polarized ATR spectra of a 40-A lipid layer were simulated for different acyl chain tilt angles. The results show that the thickness- and absorption-dependent formalism using the mean values of the electric fields over the film thickness gives the most accurate values of acyl chain tilt angle in dry lipid films. However, for lipid monolayers or bilayers, the tilt angle can be determined with an acceptable accuracy using the Harrick thin film approximation. Finally, this study shows clearly that the uncertainty on the determination of the tilt angle comes mostly from the experimental error on the dichroic ratio and from the knowledge of the refractive index. PMID:9876167

  6. Detection of canine skin and subcutaneous tumors by visible and near-infrared diffuse reflectance spectroscopy

    NASA Astrophysics Data System (ADS)

    Cugmas, Blaž; Plavec, Tanja; Bregar, Maksimilijan; Naglič, Peter; Pernuš, Franjo; Likar, Boštjan; Bürmen, Miran

    2015-03-01

    Cancer is the main cause of canine morbidity and mortality. The existing evaluation of tumors requires an experienced veterinarian and usually includes invasive procedures (e.g., fine-needle aspiration) that can be unpleasant for the dog and the owner. We investigate visible and near-infrared diffuse reflectance spectroscopy (DRS) as a noninvasive optical technique for evaluation and detection of canine skin and subcutaneous tumors ex vivo and in vivo. The optical properties of tumors and skin were calculated in a spectrally constrained manner, using a lookup table-based inverse model. The obtained optical properties were analyzed and compared among different tumor groups. The calculated parameters of the absorption and reduced scattering coefficients were subsequently used for detection of malignant skin and subcutaneous tumors. The detection sensitivity and specificity of malignant tumors ex vivo were 90.0% and 73.5%, respectively, while corresponding detection sensitivity and specificity of malignant tumors in vivo were 88.4% and 54.6%, respectively. The obtained results show that the DRS is a promising noninvasive optical technique for detection and classification of malignant and benign canine skin and subcutaneous tumors. The method should be further investigated on tumors with common origin.

  7. Adsorption on carbon nanotubes studied using polarization-modulated infrared reflection-absorption spectroscopy.

    PubMed

    Bermudez, V M

    2005-05-26

    Single-wall carbon nanotubes (SWNTs), deposited onto an Al substrate from a liquid suspension, have been cleaned by annealing in ultrahigh vacuum. The effects of exposing the sample in situ to atomic H (or D) and/or to dimethyl methylphosphonate [DMMP, (CH(3)O)(2)(CH(3))P=O] were then studied using polarization-modulated infrared reflection-absorption spectroscopy. Atomic H reacts preferentially near strained or defective regions in the nanotube wall to produce a spectrum consistent with alkane-like species (>CH(2) and -CH(3)). Only a small fraction of the >C=C< sites in the nanotube wall react with H, and there is no clear evidence for monohydride >C(H)-C(H)< species. For DMMP, data were obtained under steady-state conditions in reagent pressures in excess of half the room-temperature vapor pressure. Adsorption occurs via the P=O group with a coverage that depends on the ambient pressure. Varying the DMMP coverage by changing the pressure causes changes in the spectrum that can be related to the strength of the DMMP/SWNT interaction. Preadsorbed H is seen to have little or no effect on the subsequent adsorption of DMMP. For DMMP, the molecular features are superimposed on a broad, smoothly varying background that can be related to adsorption-induced changes in the Drude parameters characterizing the SWNT free-carrier density and scattering lifetime.

  8. Crop/weed discrimination using near-infrared reflectance spectroscopy (NIRS)

    NASA Astrophysics Data System (ADS)

    Zhang, Yun; He, Yong

    2006-09-01

    The traditional uniform herbicide application often results in an over chemical residues on soil, crop plants and agriculture produce, which have imperiled the environment and food security. Near-infrared reflectance spectroscopy (NIRS) offers a promising means for weed detection and site-specific herbicide application. In laboratory, a total of 90 samples (30 for each species) of the detached leaves of two weeds, i.e., threeseeded mercury (Acalypha australis L.) and fourleafed duckweed (Marsilea quadrfolia L.), and one crop soybean (Glycine max) was investigated for NIRS on 325- 1075 nm using a field spectroradiometer. 20 absorbance samples of each species after pretreatment were exported and the lacked Y variables were assigned independent values for partial least squares (PLS) analysis. During the combined principle component analysis (PCA) on 400-1000 nm, the PC1 and PC2 could together explain over 91% of the total variance and detect the three plant species with 98.3% accuracy. The full-cross validation results of PLS, i.e., standard error of prediction (SEP) 0.247, correlation coefficient (r) 0.954 and root mean square error of prediction (RMSEP) 0.245, indicated an optimum model for weed identification. By predicting the remaining 10 samples of each species in the PLS model, the results with deviation presented a 100% crop/weed detection rate. Thus, it could be concluded that PLS was an available alternative of for qualitative weed discrimination on NTRS.

  9. Application of near infrared reflectance spectroscopy to predict meat and meat products quality: A review.

    PubMed

    Prieto, N; Roehe, R; Lavín, P; Batten, G; Andrés, S

    2009-10-01

    Over the past three decades, near infrared reflectance (NIR) spectroscopy has been proved to be one of the most efficient and advanced tools for the estimation of quality attributes in meat and meat products. This review focuses on the use of NIR spectroscopy to predict different meat properties, considering the literature published mainly in the last decade. Firstly, the potential of NIR to predict chemical composition (crude protein, intramuscular fat, moisture/dry matter, ash, gross energy, myoglobin and collagen), technological parameters (pH value; L*, a*, b* colour values; water holding capacity; Warner-Bratzler and slice shear force) and sensory attributes (colour, shape, marbling, odour, flavour, juiciness, tenderness or firmness) are reviewed. Secondly, the usefulness of NIR for classification into meat quality grades is presented and thirdly its potential application in the industry is shown. The review indicates that NIR showed high potential to predict chemical meat properties and to categorize meat into quality classes. In contrast, NIR showed limited ability for estimating technological and sensory attributes, which may be mainly due to the heterogeneity of the meat samples and their preparation, the low precision of the reference methods and the subjectivity of assessors in taste panels. Hence, future work to standardize sample preparation and increase the accuracy of reference methods is recommended to improve NIR ability to predict those technological and sensory characteristics. In conclusion, the review shows that NIR has a considerable potential to predict simultaneously numerous meat quality criteria.

  10. Simultaneous diffuse reflectance infrared determination of clavulanic acid and amoxicillin using multivariate calibration techniques.

    PubMed

    Müller, Aline Lima Hermes; Picoloto, Rochele Sogari; Ferrão, Marco Flores; da Silva, Fabiana Ernestina Barcellos; Müller, Edson Irineu; Flores, Erico Marlon de Moraes

    2012-06-01

    A method for simultaneous determination of clavulanic acid (CA) and amoxicillin (AMO) in commercial tablets was developed using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and multivariate calibration. Twenty-five samples (10 commercial and 15 synthetic) were used as a calibration set and 15 samples (10 commercial and 5 synthetic) were used for a prediction set. Calibration models were developed using partial least squares (PLS), interval PLS (iPLS), and synergy interval PLS (siPLS) algorithms. The best algorithm for CA determination was siPLS model with spectra divided in 30 intervals and combinations of 2 intervals. This model showed a root mean square error of prediction (RMSEP) of 5.1 mg g(-1). For AMO determination, the best siPLS model was obtained with spectra divided in 10 intervals and combinations of 4 intervals. This model showed a RMSEP of 22.3 mg g(-1). The proposed method was considered as a suitable for the simultaneous determination of CA and AMO in commercial pharmaceuticals products.

  11. Far infrared reflectance of sintered nickel manganite samples for negative temperature coefficient thermistors

    SciTech Connect

    Nikolic, M.V. . E-mail: maria@mi.sanu.ac.yu; Paraskevopoulos, K.M.; Aleksic, O.S.; Zorba, T.T.; Savic, S.M.; Lukovic, D.T.

    2007-08-07

    Single phase complex spinel (Mn, Ni, Co, Fe){sub 3}O{sub 4} samples were sintered at 1050, 1200 and 1300 deg. C for 30 min and at 1200 deg. C for 120 min. Morphological changes of the obtained samples with the sintering temperature and time were analyzed by X-ray diffraction and scanning electron microscope (SEM). Room temperature far infrared reflectivity spectra for all samples were measured in the frequency range between 50 and 1200 cm{sup -1}. The obtained spectra for all samples showed the presence of the same oscillators, but their intensities increased with the sintering temperature and time in correlation with the increase in sample density and microstructure changes during sintering. The measured spectra were numerically analyzed using the Kramers-Kroenig method and the four-parameter model of coupled oscillators. Optical modes were calculated for six observed ionic oscillators belonging to the spinel structure of (Mn, Ni, Co, Fe){sub 3}O{sub 4} of which four were strong and two were weak.

  12. Characterization of NPP Visible/Infrared Imager Radiometer Suite (VIIRS) Reflective Solar Bands Dual Gain Anomaly

    NASA Technical Reports Server (NTRS)

    Lee, Shihyan; McIntire, Jeff; Oudari, Hassan

    2012-01-01

    The Visible/Infrared Imager Radiometer Suite (VIIRS) contains six dual gain bands in the reflective solar spectrum. The dual gain bands are designed to switch gain mode at pre-defined thresholds to achieve high resolution at low radiances while maintaining the required dynamic range for science. During pre-launch testing, an anomaly in the electronic response before transitioning from high to low gain was discovered and characterized. On-orbit, the anomaly was confirmed using MODIS data collected during Simultaneous Nadir Overpasses (SNOs). The analysis of the Earth scene data shows that dual gain anomaly can be determined at the orbital basis. To characterize the dual gain anomaly, the anomaly region and electronic offsets were tracked per week during the first 8 month of VIIRS operation. The temporal analysis shows the anomaly region can drift 20 DN and is impacted by detectors DC Restore. The estimated anomaly flagging regions cover 2.5 % of the high gain dynamic range and are consistent with prelaunch and on-orbit LUT. The prelaunch results had a smaller anomaly range (30-50 DN) and are likely the results of more stable electronics from the shorter data collection time. Finally, this study suggests future calibration efforts to focus on the anomaly's impact on science products and possible correction method to reduce uncertainties.

  13. Electrically tunable selective reflection of light by heliconical cholesteric structures (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Lavrentovich, Oleg D.; Xiang, Jie; Shiyanovskii, Sergij V.; Li, Quan

    2015-10-01

    Cholesteric liquid crystals with helicoidal molecular architecture are known for their ability to selectively reflect light with the wavelength that is determined by the periodicity of molecular orientations. Resulting interference colors are highly saturated, they add like colored lights and produce a color gamut greater than that obtained with inks, dyes, and pigments. The periodicity of the helical structure and thus the wavelength of the reflected light can be controlled by chemical composition and sometimes by temperature, but tuning with the electric field has been so far elusive. Here we demonstrate that by using a cholesteric with oblique helicoidal (heliconical) structure, as opposed to the classic "right-angle" helicoid, one can vary the wavelength of selectively reflected light in a broad spectral range, by simply adjusting the electric field applied parallel to the helicoidal axis. The effect can enable many applications that require dynamically controlled transmission and reflection of light, from energy-saving smart windows to tunable organic lasers, and transparent "see-through" displays. Since the material is non-absorbing and transparent everywhere except the electrically preselected reflection band, the effect can be used in creating multilayered structures with a dynamic additive mixture of colors.

  14. Effects of polychromatic visible and infrared light on biological liquid media.

    PubMed

    Zilov, V G; Khadartsev, A A; Bitsoev, V D

    2014-08-01

    Experimental study of the effects of polychromatic visible and infrared light on biological fluids was carried out in order to validate the new approaches to phototherapy. Polychromatic light generated by Bioptron device at different modes and frequencies was released through the fiberoptic cable, including the exposure paralleled by CO2 saturation of water and exposure from a device placed 10 cm above the water surface, which ensured maximum light absorption. The effects of irradiation were recorded in 26 and 15 min, while the increase of light absorption by blood plasma in vivo was recorded 1 h after a bath with water pre-exposed to polarized light. Absorption bands corresponding to those for immunomodulatory, anti-inflammatory, and antiviral drugs, were detected. Changes in the spectra of valency oscillations, depending on the oscillation anharmonism values, were detected.

  15. A novel sensor system for 3D face scanning based on infrared coded light

    NASA Astrophysics Data System (ADS)

    Modrow, Daniel; Laloni, Claudio; Doemens, Guenter; Rigoll, Gerhard

    2008-02-01

    In this paper we present a novel sensor system for three-dimensional face scanning applications. Its operating principle is based on active triangulation with a color coded light approach. As it is implemented in the near infrared band, the used light is invisible for human perception. Though the proposed sensor is primarily designed for face scanning and biometric applications, its performance characteristics are beneficial for technical applications as well. The acquisition of 3d data is real-time capable, provides accurate and high resolution depthmaps and shows high robustness against ambient light. Hence most of the limiting factors of other sensors for 3d and face scanning applications are eliminated, such as blinding and annoying light patterns, motion constraints and highly restricted scenarios due to ambient light constraints.

  16. Suppressing light reflection from polycrystalline silicon thin films through surface texturing and silver nanostructures

    SciTech Connect

    Akhter, Perveen; Huang, Mengbing Kadakia, Nirag; Spratt, William; Malladi, Girish; Bakhru, Hassarum

    2014-09-21

    This work demonstrates a novel method combining ion implantation and silver nanostructures for suppressing light reflection from polycrystalline silicon thin films. Samples were implanted with 20-keV hydrogen ions to a dose of 10¹⁷/cm², and some of them received an additional argon ion implant to a dose of 5×10¹⁵ /cm² at an energy between 30 and 300 keV. Compared to the case with a single H implant, the processing involved both H and Ar implants and post-implantation annealing has created a much higher degree of surface texturing, leading to a more dramatic reduction of light reflection from polycrystalline Si films over a broadband range between 300 and 1200 nm, e.g., optical reflection from the air/Si interface in the AM1.5 sunlight condition decreasing from ~30% with an untextured surface to below 5% for a highly textured surface after post-implantation annealing at 1000°C. Formation of Ag nanostructures on these ion beam processed surfaces further reduces light reflection, and surface texturing is expected to have the benefit of diminishing light absorption losses within large-size (>100 nm) Ag nanoparticles, yielding an increased light trapping efficiency within Si as opposed to the case with Ag nanostructures on a smooth surface. A discussion of the effects of surface textures and Ag nanoparticles on light trapping within Si thin films is also presented with the aid of computer simulations.

  17. Separation of surface and bulk reflectance by absorption of bulk scattered light.

    PubMed

    Johansson, Niklas; Neuman, Magnus; Andersson, Mattias; Edström, Per

    2013-07-01

    A method is proposed for separating light reflected from turbid media with a rough surface into a bulk and a surface component. Dye is added to the sample, thereby increasing absorption and canceling bulk scattering. The remaining reflected light is surface reflectance, which can be subtracted from the total reflectance of an undyed sample to obtain the bulk component. The method is applied to paper where the addition of dye is accomplished by inkjet printing. The results show that the bulk scattered light is efficiently canceled, and that both the spectrally neutral surface reflectance and the surface topography of the undyed paper is maintained. The proposed method is particularly suitable for characterization of dielectric, highly randomized materials with significant bulk reflectance and rough surfaces, which are difficult to analyze with existing methods. A reliable separation method opens up for new ways of analyzing, e.g., biological tissues and optical coatings, and is also a valuable tool in the development of more comprehensive reflectance models.

  18. Geometric conditions for reflection measurement II: effects of light trap size of integrating sphere

    NASA Astrophysics Data System (ADS)

    Baba, Gorow; Suzuki, Kenichi

    2002-06-01

    Many samples with various color and gloss grades were measured by the spectrophotometer with integrating sphere, of which light trap size was variable. Samples include white plaques, ceramic tiles, paint panels, ink-jet printings, textiles and metal surfaces. For these samples, lightness and chromaticness change with light trap size, which is relate to the elimination of surface reflection, was examined. In case of color measurement, using integrating sphere, colorimetric values are affected by the light trap size, when gloss grade of sample is different.

  19. Progress in the Field of Constructing Near-Infrared Light-Responsive Drug Delivery Platforms.

    PubMed

    Zhou, Fang; Wang, Hanjie; Chang, Jin

    2016-03-01

    Stimuli-responsive materials have taken replace of traditional drug carriers due to their ability to achieve controlled release of their encapsulated contents. A variety of sensitive materials, such as polymers that respond to pH, light, and magnetic fields, are widely used to construct drug carriers, and achieved good results. Specifically, near-infrared light (NIR) responsive materials are of particular interest in drug delivery, as NIR can penetrate body tissue and is minimally absorbed by the body's water and hemoglobin and is less harmful to healthy cells than UV or visible light. Thus, the near-infrared excitation drug delivery systems (NIRDDSs) have some essential advantages just like being efficient to kill tumor cells, accurate to achieve the tumor sites and less damage to human body. Also, in the process of building the carriers, we may achieve a combination of controlled release chemotherapy, photothermal therapy (PTT) or photodynamic therapy (PDT). In addition, besides utilizing as drug delivery platforms, some carriers can achieve multifunctional tumor diagnosis and treatment, such as magnetic resonance imaging, optical imaging, drug carriers and PTT. In this review, based on the mechanism of NIR, we highlight diverse near-infrared light-responsive drug delivery platforms and recent advances in the development of NIRDDSs for cancer therapy primarily. PMID:27455610

  20. Variable Stars in the 3.6 Year DIRBE Near-Infrared Light Curve Archive

    NASA Astrophysics Data System (ADS)

    Kraemer, Kathleen E.; Price, S. D.; Smith, B. J.; Kuchar, T. A.; Mizuno, D. R.; Webb, J.

    2011-05-01

    The 3.6 year light curve archive created by Price et al. (2010) from the cryo+post-cryo Diffuse Infrared Background Experiment (DIRBE) mission contains a wealth of variable star information at 1.25, 2.2, 3.5, and 4.9 microns. Of the 2700 objects in the archive, over 500 show strong variability and another 75 show potential variability. We have combined visible observations obtained during the DIRBE extended mission with the infrared archive to investigate wavelength-dependent phase lags between the visible and the near-IR maxima, extending the study of Smith et al. (2006) to those stars with periods longer than the 300 day cryo mission. Of those 518 stars exhibiting strong near-infrared variability, 200 have visible light curves in the American Association of Variable Star Observers database during the DIRBE mission. Because viewing geometry for both the visible observers and DIRBE mission limited the opportunities for observing the stars, the light curves were inspected to determine if the peaks were defined well enough to determine phase lags among the five wavebands. For those objects that have sufficient data, we investigate a number of methods to best estimate the peaks and thus find the phase lags, if any. We have also examined the differences in phase dependence on variable type, e.g. Miras, SRa's, SRb's, and carbon stars. The DIRBE light curve data are available to the community through the Vizier service at the Centre de Donnees Astronomique de Strasbourg.

  1. THE 1.6 {mu}m NEAR-INFRARED NUCLEI OF 3C RADIO GALAXIES: JETS, THERMAL EMISSION, OR SCATTERED LIGHT?

    SciTech Connect

    Baldi, Ranieri D.; Chiaberge, Marco; Sparks, William; Macchetto, F. Duccio; Capetti, Alessandro; O'Dea, Christopher P.; Axon, David J.; Baum, Stefi A.; Quillen, Alice C.

    2010-12-20

    Using HST NICMOS 2 observations we have measured 1.6 {mu}m near-infrared nuclear luminosities of 100 3CR radio galaxies with z < 0.3, by modeling and subtracting the extended emission from the host galaxy. We performed a multiwavelength statistical analysis (including optical and radio data) of the properties of the nuclei following classification of the objects into FR I and FR II, and low-ionization galaxies (LIGs), high-ionization galaxies (HIGs), and broad-line objects (BLOs) using the radio morphology and optical spectra, respectively. The correlations among near-infrared, optical, and radio nuclear luminosity support the idea that the near-infrared nuclear emission of FR Is has a non-thermal origin. Despite the difference in radio morphology, the multiwavelength properties of FR II LIG nuclei are statistically indistinguishable from those of FR Is, an indication of a common structure of the central engine. All BLOs show an unresolved near-infrared nucleus and a large near-infrared excess with respect to FR II LIGs and FR Is of equal radio core luminosity. This requires the presence of an additional (and dominant) component other than the non-thermal light. Considering the shape of their spectral energy distribution, we ascribe the origin of their near-infrared light to hot circumnuclear dust. A near-infrared excess is also found in HIGs, but their nuclei are substantially fainter than those of BLO. This result indicates that substantial obscuration along the line of sight to the nuclei is still present at 1.6 {mu}m. Nonetheless, HIG nuclei cannot simply be explained in terms of dust obscuration: a significant contribution from light reflected in a circumnuclear scattering region is needed to account for their multiwavelength properties.

  2. The Origin of the Excess Near-Infrared Diffuse Sky Brightness: Population III Stars or Zodiacal Light?

    NASA Technical Reports Server (NTRS)

    Dwek, Eli

    2006-01-01

    The intensity of the diffuse 1 to 5 micron sky emission from which solar system and Galactic foregrounds have been subtracted is in excess of that expected from energy released by galaxies and stars that formed during the z < 5 redshift interval. The spectral signature of this excess near-infrared background light (NIRBL) component is almost identical to that of reflected sunlight from the interplanetary dust cloud, and could therefore be the result of the incomplete subtraction of this foreground emission component from the diffuse sky maps. Alternatively, this emission component could be extragalactic. Its spectral signature is consistent with that of redshifted continuum and recombination line emission from H-II regions formed by the first generation of very massive stars. In this talk I will present the implications of this excess emission for our understanding of the zodiacal dust cloud, the formation rate of Pop III stars, and the TeV gamma-ray opacity to nearby blazars.

  3. Real time infrared aerosol analyzer

    DOEpatents

    Johnson, Stanley A.; Reedy, Gerald T.; Kumar, Romesh

    1990-01-01

    Apparatus for analyzing aerosols in essentially real time includes a virtual impactor which separates coarse particles from fine and ultrafine particles in an aerosol sample. The coarse and ultrafine particles are captured in PTFE filters, and the fine particles impact onto an internal light reflection element. The composition and quantity of the particles on the PTFE filter and on the internal reflection element are measured by alternately passing infrared light through the filter and the internal light reflection element, and analyzing the light through infrared spectrophotometry to identify the particles in the sample.

  4. De-polarization of a CdZnTe radiation detector by pulsed infrared light

    SciTech Connect

    Dědič, V. Franc, J.; Rejhon, M.; Grill, R.; Zázvorka, J.; Sellin, P. J.

    2015-07-20

    This work is focused on a detailed study of pulsed mode infrared light induced depolarization of CdZnTe detectors operating at high photon fluxes. This depolarizing effect is a result of the decrease of positive space charge that is caused by the trapping of photogenerated holes at a deep level. The reduction in positive space charge is due to the optical transition of electrons from a valence band to the deep level due to additional infrared illumination. In this paper, we present the results of pulse mode infrared depolarization, by which it is possible to keep the detector in the depolarized state during its operation. The demonstrated mechanism represents a promising way to increase the charge collection efficiency of CdZnTe X-ray detectors operating at high photon fluxes.

  5. Multi-spectral imaging with infrared sensitive organic light emitting diode.

    PubMed

    Kim, Do Young; Lai, Tzung-Han; Lee, Jae Woong; Manders, Jesse R; So, Franky

    2014-01-01

    Commercially available near-infrared (IR) imagers are fabricated by integrating expensive epitaxial grown III-V compound semiconductor sensors with Si-based readout integrated circuits (ROIC) by indium bump bonding which significantly increases the fabrication costs of these image sensors. Furthermore, these typical III-V compound semiconductors are not sensitive to the visible region and thus cannot be used for multi-spectral (visible to near-IR) sensing. Here, a low cost infrared (IR) imaging camera is demonstrated with a commercially available digital single-lens reflex (DSLR) camera and an IR sensitive organic light emitting diode (IR-OLED). With an IR-OLED, IR images at a wavelength of 1.2 µm are directly converted to visible images which are then recorded in a Si-CMOS DSLR camera. This multi-spectral imaging system is capable of capturing images at wavelengths in the near-infrared as well as visible regions. PMID:25091589

  6. Multi-spectral imaging with infrared sensitive organic light emitting diode

    NASA Astrophysics Data System (ADS)

    Kim, Do Young; Lai, Tzung-Han; Lee, Jae Woong; Manders, Jesse R.; So, Franky

    2014-08-01

    Commercially available near-infrared (IR) imagers are fabricated by integrating expensive epitaxial grown III-V compound semiconductor sensors with Si-based readout integrated circuits (ROIC) by indium bump bonding which significantly increases the fabrication costs of these image sensors. Furthermore, these typical III-V compound semiconductors are not sensitive to the visible region and thus cannot be used for multi-spectral (visible to near-IR) sensing. Here, a low cost infrared (IR) imaging camera is demonstrated with a commercially available digital single-lens reflex (DSLR) camera and an IR sensitive organic light emitting diode (IR-OLED). With an IR-OLED, IR images at a wavelength of 1.2 µm are directly converted to visible images which are then recorded in a Si-CMOS DSLR camera. This multi-spectral imaging system is capable of capturing images at wavelengths in the near-infrared as well as visible regions.

  7. Optical designs of compact multichannel and all-reflective system for infrared imaging

    NASA Astrophysics Data System (ADS)

    Wang, Min; Châteauneuf, François; Proulx, Christian

    2011-06-01

    In space infrared (IR) optics, to achieve better observation of ground target, a common aperture all-reflective telescope, working at fast focal-ratio with multi-channel to cover different waveband and wide field-of-view (FOV), is a most wanted optical system. The remarkable imaging properties of the fast focal-ratio, flat-field, anastigmatic, rotationally symmetric Schwarzschild telescope have been well recognized historically, but suffer strong central obscuration and limited FOV in the conventional axis-symmetric design. Our solution is to use an eccentric system evolved from the Schwarzschild axially symmetric system, adding a tertiary off-axis mirror, to optimize the off-axis performance with the appropriate system parameters and specs, as required by most space IR optical systems. The optical design system consists of three powered mirrors, in which the primary (M1) is convex and secondary (M2) is either convex or concave, with a tertiary (M3) always in concave shape respectively. Both secondary and tertiary mirrors have their size larger than that of the primary. The entrance pupil of the system is projected behind M1. Dichroic filters can be used after the tertiary mirror to achieve separation of multi-spectral channels. In the designs the mirrors with optimized aspherical shapes, which are all in even-asphere warped up to 10th asphericities, are used for achieving the final image quality. The final corrected wavefront in the system can result in the good optical performance with an encircled energy of better than 80% per pixel for all channels, working at F/1.66 to correct a wide FOV up to 27.70 (H) x 48.70 (V). The design is scalable for different image scales, as usually required for different optical systems targeting different applications. The broad spectral range from mid-wave infrared (MWIR) up to Far IR can be fully covered by this design. Multiple focalplane- arrays (FPAs) can be used with respect to different spectral channels in the optical

  8. An experimental set-up to apply polarization modulation to infrared reflection absorption spectroscopy for improved in situ studies of atmospheric corrosion processes

    SciTech Connect

    Wiesinger, R.; Schade, U.; Kleber, Ch.; Schreiner, M.

    2014-06-15

    A new set-up for improved monitoring of atmospheric corrosion processes in situ and in real-time is presented. To characterize chemical structures of thin films on metal surfaces surface sensitive analytical techniques are required. One possible technique is Infrared Reflection Absorption Spectroscopy (IRRAS) which has become an established method to investigate surface corrosion films of thicknesses less than 200 nm. However, there are limitations related to the sensitivity of these measurements, in case of investigating ultrathin films or absorption bands of interest, surface species are superimposed by atmospheric background absorption, which changes during in situ measurements in ambient atmospheres. These difficulties of in situ surface reflection measurements can be eliminated by availing the polarization selectivity of adsorbed surface species. At grazing angles of incidence the absorption of p-polarized infrared radiation by thin surface films on metals is enhanced, while the absorption of s-polarized light by this film is nearly zero. This different behavior of the polarization properties leads to strong selection rules at the surface and can therefore be used to identify molecules adsorbed on metal surfaces. Polarization Modulation (PM) of the infrared (IR) light takes advantage of this disparity of polarization on sample surfaces and in combination with IRRAS yielding a very sensitive and surface-selective method for obtaining IR spectra of ultra-thin films on metal surfaces. An already existing in situ IRRAS/Quartz Crystal Microbalance weathering cell was combined with PM and evaluated according to its applicability to study in situ atmospheric corrosion processes. First real-time measurements on silver samples exposed to different atmospheres were performed showing the advantage of PM-IRRAS compared to conventional IRRAS for such investigations.

  9. An experimental set-up to apply polarization modulation to infrared reflection absorption spectroscopy for improved in situ studies of atmospheric corrosion processes.

    PubMed

    Wiesinger, R; Schade, U; Kleber, Ch; Schreiner, M

    2014-06-01

    A new set-up for improved monitoring of atmospheric corrosion processes in situ and in real-time is presented. To characterize chemical structures of thin films on metal surfaces surface sensitive analytical techniques are required. One possible technique is Infrared Reflection Absorption Spectroscopy (IRRAS) which has become an established method to investigate surface corrosion films of thicknesses less than 200 nm. However, there are limitations related to the sensitivity of these measurements, in case of investigating ultrathin films or absorption bands of interest, surface species are superimposed by atmospheric background absorption, which changes during in situ measurements in ambient atmospheres. These difficulties of in situ surface reflection measurements can be eliminated by availing the polarization selectivity of adsorbed surface species. At grazing angles of incidence the absorption of p-polarized infrared radiation by thin surface films on metals is enhanced, while the absorption of s-polarized light by this film is nearly zero. This different behavior of the polarization properties leads to strong selection rules at the surface and can therefore be used to identify molecules adsorbed on metal surfaces. Polarization Modulation (PM) of the infrared (IR) light takes advantage of this disparity of polarization on sample surfaces and in combination with IRRAS yielding a very sensitive and surface-selective method for obtaining IR spectra of ultra-thin films on metal surfaces. An already existing in situ IRRAS/Quartz Crystal Microbalance weathering cell was combined with PM and evaluated according to its applicability to study in situ atmospheric corrosion processes. First real-time measurements on silver samples exposed to different atmospheres were performed showing the advantage of PM-IRRAS compared to conventional IRRAS for such investigations.

  10. An experimental set-up to apply polarization modulation to infrared reflection absorption spectroscopy for improved in situ studies of atmospheric corrosion processes

    NASA Astrophysics Data System (ADS)

    Wiesinger, R.; Schade, U.; Kleber, Ch.; Schreiner, M.

    2014-06-01

    A new set-up for improved monitoring of atmospheric corrosion processes in situ and in real-time is presented. To characterize chemical structures of thin films on metal surfaces surface sensitive analytical techniques are required. One possible technique is Infrared Reflection Absorption Spectroscopy (IRRAS) which has become an established method to investigate surface corrosion films of thicknesses less than 200 nm. However, there are limitations related to the sensitivity of these measurements, in case of investigating ultrathin films or absorption bands of interest, surface species are superimposed by atmospheric background absorption, which changes during in situ measurements in ambient atmospheres. These difficulties of in situ surface reflection measurements can be eliminated by availing the polarization selectivity of adsorbed surface species. At grazing angles of incidence the absorption of p-polarized infrared radiation by thin surface films on metals is enhanced, while the absorption of s-polarized light by this film is nearly zero. This different behavior of the polarization properties leads to strong selection rules at the surface and can therefore be used to identify molecules adsorbed on metal surfaces. Polarization Modulation (PM) of the infrared (IR) light takes advantage of this disparity of polarization on sample surfaces and in combination with IRRAS yielding a very sensitive and surface-selective method for obtaining IR spectra of ultra-thin films on metal surfaces. An already existing in situ IRRAS/Quartz Crystal Microbalance weathering cell was combined with PM and evaluated according to its applicability to study in situ atmospheric corrosion processes. First real-time measurements on silver samples exposed to different atmospheres were performed showing the advantage of PM-IRRAS compared to conventional IRRAS for such investigations.

  11. Berry Phase of Light under Bragg Reflection by Chiral Liquid-Crystal Media.

    PubMed

    Barboza, Raouf; Bortolozzo, Umberto; Clerc, Marcel G; Residori, Stefania

    2016-07-29

    A Berry phase is revealed for circularly polarized light when it is Bragg reflected by a chiral liquid-crystal medium of the same handedness. By using a chiral nematic layer we demonstrate that if the input plane of the layer is rotated with respect to a fixed reference frame, a geometric phase effect occurs for the circularly polarized light reflected by the periodic helical structure of the medium. Theory and numerical simulations are supported by an experimental observation, disclosing novel applications in the field of optical manipulation and fundamental optical phenomena. PMID:27517773

  12. Diffraction-dependent spin splitting in spin Hall effect of light on reflection.

    PubMed

    Qiu, Xiaodong; Xie, Linguo; Qiu, Jiangdong; Zhang, Zhiyou; Du, Jinglei; Gao, Fuhua

    2015-07-27

    We report on a diffraction-dependent spin splitting of the paraxial Gaussian light beams on reflection theoretically and experimentally. In the case of horizontal incident polarization, the spin splitting is proportional to the diffraction length of light beams near the Brewster angle. However, the spin splitting is nearly independent with the diffraction length for the vertical incident polarization. By means of the angular spectrum theory, we find that the diffraction-dependent spin splitting is attributed to the first order expansion term of the reflection coefficients with respect to the transverse wave-vector which is closely related to the diffraction length.

  13. Berry Phase of Light under Bragg Reflection by Chiral Liquid-Crystal Media

    NASA Astrophysics Data System (ADS)

    Barboza, Raouf; Bortolozzo, Umberto; Clerc, Marcel G.; Residori, Stefania

    2016-07-01

    A Berry phase is revealed for circularly polarized light when it is Bragg reflected by a chiral liquid-crystal medium of the same handedness. By using a chiral nematic layer we demonstrate that if the input plane of the layer is rotated with respect to a fixed reference frame, a geometric phase effect occurs for the circularly polarized light reflected by the periodic helical structure of the medium. Theory and numerical simulations are supported by an experimental observation, disclosing novel applications in the field of optical manipulation and fundamental optical phenomena.

  14. Absorption and electrochromic modulation of near-infrared light: realized by tungsten suboxide.

    PubMed

    Li, Guilian; Zhang, Shouhao; Guo, Chongshen; Liu, Shaoqin

    2016-05-01

    In the present study, needle-like tungsten suboxide W18O49 nanocrystals were fabricated as the optical active substance to realize the aim of optical control of near-infrared light. The W18O49 nanocrystals were selected in this regard due to their unique optical performance. As revealed by the powder absorption result, the needle-like W18O49 nanocrystals show strong and wide photoabsorption in the entire near infrared region of 780-2500 nm, from which thin films with the W18O49 nanocrystal coating thus benefits and can strongly shield off almost all near infrared irradiation, whereas transmitting the majority of visible light. To make it more tunable, the W18O49 nanocrystals were finally assembled onto an ITO glass via the layer-by-layer strategy for later electrochromic investigation. The nanostructured architectures of the W18O49 nanocrystal electrochromic films exhibit high contrast, faster switching response, higher coloration efficiencies (150 cm(2) C(-1) at 650 nm and 255 cm(2) C(-1) at 1300 nm), better long-term redox switching stability (reversibility of 98% after 500 cycles) and wide electrochromic spectrum coverage of both the visible and infrared regions. PMID:27119556

  15. Absorption and electrochromic modulation of near-infrared light: realized by tungsten suboxide.

    PubMed

    Li, Guilian; Zhang, Shouhao; Guo, Chongshen; Liu, Shaoqin

    2016-05-01

    In the present study, needle-like tungsten suboxide W18O49 nanocrystals were fabricated as the optical active substance to realize the aim of optical control of near-infrared light. The W18O49 nanocrystals were selected in this regard due to their unique optical performance. As revealed by the powder absorption result, the needle-like W18O49 nanocrystals show strong and wide photoabsorption in the entire near infrared region of 780-2500 nm, from which thin films with the W18O49 nanocrystal coating thus benefits and can strongly shield off almost all near infrared irradiation, whereas transmitting the majority of visible light. To make it more tunable, the W18O49 nanocrystals were finally assembled onto an ITO glass via the layer-by-layer strategy for later electrochromic investigation. The nanostructured architectures of the W18O49 nanocrystal electrochromic films exhibit high contrast, faster switching response, higher coloration efficiencies (150 cm(2) C(-1) at 650 nm and 255 cm(2) C(-1) at 1300 nm), better long-term redox switching stability (reversibility of 98% after 500 cycles) and wide electrochromic spectrum coverage of both the visible and infrared regions.

  16. Photodynamic inactivation of microorganisms which cause pulmonary diseases with infrared light: an in vitro study

    NASA Astrophysics Data System (ADS)

    Leite, Ilaiáli S.; Geralde, Mariana C.; Salina, Ana C.; Medeiros, Alexandra I.; Kurachi, Cristina; Bagnato, Vanderlei S.; Inada, Natalia M.

    2014-03-01

    Lower respiratory infections are among the leading causes of death worldwide. In this study, it was evaluated the interaction of indocyanine green, a photosensitizer activated by infrared light, with alveolar macrophages and the effectiveness of the photodynamic therapy using this compound against Streptococcus pneumoniae . Initial experiments analyzed indocyanine green toxicity to alveolar macrophages in the dark with different drug concentrations and incubation times, and macrophage viability was obtained with the MTT method. The average of the results showed viability values below 90% for the two highest concentrations. Experiments with Streptococcus pneumoniae showed photodynamic inactivation with 10 μM indocyanine green solution. Further experiments with the bacteria in co-culture with AM will be conducted verifying the photodynamic inactivation effectiveness of the tested drug concentrations and incubation periods using infrared light.

  17. Solvothermal fabrication of rubidium tungsten bronze for the absorption of near infrared light.

    PubMed

    Guo, Chongshen; Yin, Shu; Dong, Qiang; Kimura, Takeshi; Tanaka, Miyuki; Hang, Le Thi; Wu, Xiaoyong; Sato, Tsugio

    2013-05-01

    For fabricating the crystal of Rb(x)WO3, the solvothermal process was performed using a mixed medium of water and ethanol as solvent. It has been found that the morphological evolutions of samples were greatly changed as disordered nanoparticles, bundle of nanorods and microfibers with increasing content of water in the starting solution. Among them, sample synthesized with assistance of 3 ml water consisted of the nanorods with a diameter in the range of 80-150 nm, showing suitable size and morphology as near-infrared shielding material. On the merits of this nanostructure, the thin film of the Rb(x)WO3 nanorods realized excellent shielding of near-infrared light, meanwhile, it selectively transmitted the major part of visible light.

  18. Optimal front light design for reflective displays under different ambient illumination

    NASA Astrophysics Data System (ADS)

    Wang, Sheng-Po; Chang, Ting-Ting; Li, Chien-Ju; Bai, Yi-Ho; Hu, Kuo-Jui

    2011-01-01

    The goal of this study is to find out the optimal luminance and color temperature of front light for reflective displays in different ambient illumination by conducting series of psychophysical experiments. A color and brightness tunable front light device with ten LED units was built and been calibrated to present 256 luminance levels and 13 different color temperature at fixed luminance of 200 cd/m2. The experiment results revealed the best luminance and color temperature settings for human observers under different ambient illuminant, which could also assist the e-paper manufacturers to design front light device, and present the best image quality on reflective displays. Furthermore, a similar experiment procedure was conducted by utilizing new flexible e-signage display developed by ITRI and an optimal front light device for the new display panel has been designed and utilized.

  19. Light source design for double reflection transmission-type visibility meter

    NASA Astrophysics Data System (ADS)

    Zhen, Xiaoqiong; Yang, Ling; Niu, Zhiqiang; Zeng, Qiangyu

    2015-07-01

    In this paper, a novel transmission-type visibility meter which is also named double reflection transmission-type visibility meter is introduced and developed. The novel visibility meter uses a charge coupled device (CCD) as an image acquiring unit, the CCD acquires light spot images which generated by a light source, an air extinction coefficient is calculated, and then the meteorology visibility is obtained. The light source is an important unit in this novel visibility meter, and influences the meteorology visibility calculation results. In this paper, several light source design schemes are proposed and researched. Each light source scheme is tested and the experimental results are analyzed. Finally the novel visibility meter which employs a determined light source design scheme finished a measurement result comparison experiment and the reliability and accuracy of the visibility meter are proved.

  20. Light diffuse reflectance for detection and differentiation of teeth caries lesions

    NASA Astrophysics Data System (ADS)

    Borisova, E.; Uzunov, Tz.; Valkanov, S.; Avramov, L.

    2007-05-01

    One of the goals of the contemporary dentistry is differentiation between carious stages that must be fast, non-invasive procedure, which will allow to the dentists to make reliable judgments. One suitable candidate for such method is reflectance spectroscopy. The objectives of current study are to determine the feasibility of applying the light reflectance spectroscopy technique for detection of different carious stages; therefore reflectance spectra of teeth illuminated at 450- 900 nm light were recorded. There are obtained reflectance signals from the healthy enamel, dentine and different lesion stages of the investigated teeth. These spectra are compared to that, obtained by non-carious tooth lesions - fluorosa and odontolithiasis, resembling on initial carious stages. There is observed a significant decrease of the intensity of the reflected light in blue region in the case of caries. Reflectance signals, obtained from non-carious lesions also have significantly different character and could be used for differentiation between them and initial carious stages. An algorithm for differentiation between carious stages is proposed with diagnostic accuracy achieved up to 86,1% between precarious stage and sound tooth and 100% for determination of deep cavitation. Some comments about role of teeth enamel structure and anisotropy factor of dental layers on the results obtained are also made.

  1. Ultra low emittance electron beams from multi-alkali antimonide photocathode operated with infrared light

    NASA Astrophysics Data System (ADS)

    Cultrera, L.; Gulliford, C.; Bartnik, A.; Lee, H.; Bazarov, I.

    2016-03-01

    The intrinsic emittance of electron beams generated from a multi-alkali photocathode operated in a high voltage DC gun is reported. The photocathode showed sensitivity extending to the infrared part of the spectrum up to 830 nm. The measured intrinsic emittances of electron beams generated with light having wavelength longer than 800 nm are approaching the limit imposed by the thermal energy of electrons at room temperature with quantum efficiencies comparable to metallic photocathodes used in operation of modern photoinjectors.

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

    NASA Astrophysics Data System (ADS)

    Dillner, A. M.; Takahama, S.

    2014-11-01

    Organic carbon (OC) can constitute 50% or more of the mass of atmospheric particulate matter. Typically, the organic carbon concentration is measured using thermal methods such as Thermal-Optical Reflectance (TOR) from quartz fiber filters. Here, methods are presented whereby Fourier Transform Infrared (FT-IR) absorbance spectra from polytetrafluoroethylene (PTFE or Teflon) filters are used to accurately predict TOR OC. Transmittance FT-IR analysis is rapid, inexpensive, and non-destructive to the PTFE filters. To develop and test the method, FT-IR absorbance spectra are obtained from 794 samples from seven Interagency Monitoring of PROtected Visual Environment (IMPROVE) sites sampled during 2011. Partial least squares regression is used to calibrate sample FT-IR absorbance spectra to artifact-corrected TOR OC. The FTIR spectra are divided into calibration and test sets by sampling site and date which leads to precise and accurate OC predictions by FT-IR as indicated by high coefficient of determination (R2; 0.96), low bias (0.02 μg m-3, all μg m-3 values based on the nominal IMPROVE sample volume of 32.8 m-3), low error (0.08 μg m-3) and low normalized error (11%). These performance metrics can be achieved with various degrees of spectral pretreatment (e.g., including or excluding substrate contributions to the absorbances) and are comparable in precision and accuracy to collocated TOR measurements. FT-IR spectra are also divided into calibration and test sets by OC mass and by OM / OC which reflects the organic composition of the particulate matter and is obtained from organic functional group composition; this division also leads to precise and accurate OC predictions. Low OC concentrations have higher bias and normalized error due to TOR analytical errors and artifact correction errors, not due to the range of OC mass of the samples in the calibration set. However, samples with low OC mass can be used to predict samples with high OC mass indicating that the

  3. Prediction of Soil Salinity Using Near-Infrared Reflectance Spectroscopy with Nonnegative Matrix Factorization.

    PubMed

    Chen, Hongyan; Zhao, Gengxing; Sun, Li; Wang, Ruiyan; Liu, Yaqiu

    2016-09-01

    As a key, yet difficult, issue currently in the quantitative remote sensing analysis of soil, the accurate and stable monitoring of soil salinity content (SSC) in situ should be studied and improved. The purpose of this study is to explore the method of fusing spectra outdoors with spectra indoors and improve the estimation precision of SSC based on near-infrared (NIR) reflectance hyper-spectra. First, samples of saline soil from the Yellow River delta of China were collected and analyzed. We measured three groups of sample spectra using a spectrometer: (1) situ-spectra, measured at sampling points in situ; (2) out-spectra, measured outdoors on air-dried samples; and, (3) lab-spectra, measured in a dark laboratory with the above air-dried samples. Second, four algorithms (multiplicative update, alternating least-squares, sparse affine non-negative matrix factorization (NMF), and gradient projection algorithms) of NMF were used to fuse the situ-spectra or out-spectra with the lab-spectra for the calibration of SSC. Finally, estimation models of SSC were built using the multiple linear regression method based on the first derivatives of the un-fused and fused spectra. The results indicate that using the NMF method to fuse the situ-spectra or out-spectra with the lab-spectra can heighten the correlation between SSC and the outdoor spectra in most wavelength ranges and improve the accuracy of the prediction model. The gradient projection algorithm shows the best performance with fewer variables and highest accuracy of the SSC model based on the NIR spectra. PMID:27566255

  4. [Attenuated total reflection-fourier transform infrared spectroscopic study of dried shark fin products].

    PubMed

    Han, Wan-qing; Luo, Hai-ying; Xian, Yan-ping; Luo, Dong-hui; Mu, Torng-na; Guo, Xin-dong

    2015-02-01

    Sixty-four pieces of shark fin dried products (including real, fake and artificial shark fin products) and real products coated with gelatin were rapidly and nondestructively analyzed by attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR). The characteristic of IR spectrograms among the above four kinds of samples were systematically studied and comparied, the results showed that the spectrograms of the same kind of samples were repeatable, and different kinds of shark fin products presented significant differences in the spectrograms, which mainly manifested as the specific absorption peaks of amido bonds in protein (1650, 1544 cm(-1)) and skeletal vibration in polysaccharide (1050 cm(-1)). The spectrograms of real shark fins were characterized by the strong absorption peaks of protein characteristic amide I and II absorbent (1650, 1544 cm(-1)) and relatively weak C--O--C vibration absorbent (1050 cm(-1)) owing to the high content of protein and relatively low level of polysaccharide. For fake shark fin products that were molded form by mixing together with the offcut of shark, collagen and other substances, the introduction of non-protein materials leaded to the weaker amido bonds absorbent than real products along with a 30 cm(-1) blue shift of amide I absorbent. Opposite to the real sample, the relatively strong absorption peak of polysaccharide (approximately 1047 cm(-1)) and barely existed amide absorbent were the key features of the spectrogram of artificial samples, which was synthersized by polysaccharide like sodium alginate. Real samples coated with gelatin, the peak strength of protein and polysaccharide were decreased simultaneously when the data collection was taken at the surface of sample, while the spectrogram presented no significant difference to real samples when the data was collected in the section. The results above indicated that by analyzing the characteristic of IR spectrograms and the value range of Apro

  5. Near infrared reflectance spectroscopy for the fast identification of PVC-based films.

    PubMed

    Laasonen, M; Rantanen, J; Harmia-Pulkkinen, T; Michiels, E; Hiltunen, R; Räsänen, M; Vuorela, H

    2001-07-01

    Near infrared (NIR) reflectance spectroscopy was used to develop a non-destructive and rapid qualitative method for the analysis of plastic films used by the pharmaceutical industry for blistering. Three types of films were investigated: 250 microm PVC [poly(vinyl chloride)] films, 250 microm PVC films coated with 40 g m(-2) of PVDC [poly(vinylidene dichloride)] and 250 microm PVC films coated with 5 g m(-2) of TE (Thermoelast) and 90 g m(-2) of PVDC. Three analyses were carried out using different pre-treatment options and a PLS (partial least squares) algorithm. Each analysis was aimed at identifying one type of film and rejecting all types of false sample (different thickness, colour or layer). True and false samples from four plastics manufacturers were included in the calibration sets in order to obtain robust methods that were suitable regardless of the supplier. Specificity was demonstrated by testing validation sets against the methods. The tests showed 0% of type I (false negative identification) and 1% of type II errors (false positive identification) for the PVC method, 13 and 3%, respectively, for the PVC-PVDC method and no error for the PVC-TE-PVDC method. Type II errors, mostly due to the slight sensitivity of the methods to film thickness, are easily corrected by simple thickness measurements. This study demonstrates that NIR spectroscopy is an excellent tool for the identification of PVC-based films. The three methods can be used by the pharmaceutical industry or plastics manufacturers for the quality control of films used in blister packaging.

  6. Tethered bilayer lipid membranes studied by simultaneous attenuated total reflectance infrared spectroscopy and electrochemical impedance spectroscopy

    PubMed Central

    Erbe, Andreas; Bushby, Richard J.; Evans, Stephen D.; Jeuken, Lars J. C.

    2013-01-01

    The formation of tethered lipid bilayer membranes (tBLMs) from unilamelar vesicles of egg yolk phosphatidylcholine (EggPC) on mixed self–assembled monolayers (SAMs) from varying ratios of 6-mercaptohexanol and EO3Cholesteryl on gold has been monitored by simultaneous attenuated total reflectance fourier transform infrared (ATR–FTIR) spectroscopy and electrochemical impedance spectroscopy (EIS). The influence of the lipid orientation (and hence the anisotropy) of lipids on a gold film on the dichroic ratio was studied by simulations of spectra with a matrix method for anisotropic layers. It is shown that for certain tilt angles of the dielectric tensor of the adsorbed anisotropic layer dispersive and negative absorption bands are possible. The experimental data indicates that the structure of the assemblies obtained varies with varying SAM composition. On SAMs with a high content of EO3Cholesteryl, tBLMs with reduced fluidity are formed. For SAMs with high content of 6-mercaptohexanol, the results are consistent with the adsorption of flattened vesicles, while spherical vesicles have been found in a small range of surface compositions. The kinetics of the adsorption process is consistent with the assumption of spherical vesicles as long–living intermediates for surfaces of high 6-mercaptohexanol content. No long–living spherical vesicles have been detected for surfaces with large fraction of EO3Cholesteryl tethers. The observed differences between the surfaces suggest that for the formation of tBLMs (unlike supported BLMs) no critical surface coverage of vesicles is needed prior to lipid bilayer formation. PMID:17388505

  7. Prediction of Soil Salinity Using Near-Infrared Reflectance Spectroscopy with Nonnegative Matrix Factorization.

    PubMed

    Chen, Hongyan; Zhao, Gengxing; Sun, Li; Wang, Ruiyan; Liu, Yaqiu

    2016-09-01

    As a key, yet difficult, issue currently in the quantitative remote sensing analysis of soil, the accurate and stable monitoring of soil salinity content (SSC) in situ should be studied and improved. The purpose of this study is to explore the method of fusing spectra outdoors with spectra indoors and improve the estimation precision of SSC based on near-infrared (NIR) reflectance hyper-spectra. First, samples of saline soil from the Yellow River delta of China were collected and analyzed. We measured three groups of sample spectra using a spectrometer: (1) situ-spectra, measured at sampling points in situ; (2) out-spectra, measured outdoors on air-dried samples; and, (3) lab-spectra, measured in a dark laboratory with the above air-dried samples. Second, four algorithms (multiplicative update, alternating least-squares, sparse affine non-negative matrix factorization (NMF), and gradient projection algorithms) of NMF were used to fuse the situ-spectra or out-spectra with the lab-spectra for the calibration of SSC. Finally, estimation models of SSC were built using the multiple linear regression method based on the first derivatives of the un-fused and fused spectra. The results indicate that using the NMF method to fuse the situ-spectra or out-spectra with the lab-spectra can heighten the correlation between SSC and the outdoor spectra in most wavelength ranges and improve the accuracy of the prediction model. The gradient projection algorithm shows the best performance with fewer variables and highest accuracy of the SSC model based on the NIR spectra.

  8. The potential of near infrared reflectance spectroscopy (NIRS) for the estimation of agroindustrial compost quality.

    PubMed

    Galvez-Sola, L; Moral, R; Perez-Murcia, M D; Perez-Espinosa, A; Bustamante, M A; Martinez-Sabater, E; Paredes, C

    2010-02-15

    Composting is an environmentally friendly alternative for the recycling of organic wastes and its use is increasing in recent years. An exhaustive monitoring of the composting process and of the final compost characteristics is necessary to certify that the values of compost characteristics are within the limits established by the legislation in order to obtain a safe and marketable product. The analysis of these parameters on each composting batch in the commercial composting plant is time-consuming and expensive. So, their estimation in the composting facilities based on the use of near infrared reflectance spectroscopy (NIRS) could be an interesting approach in order to monitor compost quality. In this study, more than 300 samples from 20 different composting procedures were used to calibrate and validate the NIRS estimation of compost properties (pH, electrical conductivity (EC), total organic matter (TOM), total organic carbon (TOC), total nitrogen (TN) and C/N ratio, macronutrient contents (N, P, K) and potentially pollutant element concentrations (Fe, Cu, Mn and Zn)). The composts used were elaborated using different organic wastes from agroindustrial activities (GS: grape stalk; EGM: exhausted grape marc; GM: grape marc; V: vinasse; CJW: citrus juice waste; Alpeorujo: olive-oil waste; AS: almond skin; EP: exhausted peat; TSW: tomato soup waste; SMS: spent mushroom substrate) co-composted with manures (CM: cattle manure; PM: poultry manure) or urban wastes (SS: sewage sludge) The estimation results showed that the NIRS technique needs to be fitted to each element and property, using specific spectrum transformations, in order to achieve an acceptable accuracy in the prediction. However, excellent prediction results were obtained for TOM and TOC, successful calibrations for pH, EC, Fe and Mn, and moderately successful estimations for TN, C/N ratio, P, K, Cu and Zn. PMID:20061002

  9. Evaluation of various polyethylene as potential dosimeters by attenuated total reflectance-Fourier-transform infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Halperin, Fred; Collins, Greta; DiCicco, Michael; Logar, John

    2014-12-01

    Various types of polyethylene (PE) have been evaluated in the past for use as a potential dosimeter, chiefly via the formation of an unsaturated transvinylene (TV) double-bond resulting from exposure to ionizing radiation. The utilization of attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy in characterizing TV formation in irradiated PE for a potential dosimeter has yet to be fully developed. In this initial investigation, various PE films/sheets were exposed to ionizing radiation in a high-energy 5 megaelectron volt (MeV) electron beam accelerator in the 10-500 kilogray (kGy) dose range, followed by ATR-FTIR analysis of TV peak formation at the 965 cm-1 wavenumber. There was an upward trend in TV formation for low-density polyethylene (LDPE) films and high-density polyethylene (HDPE) sheets as a function of absorbed dose in the 10-50 kGy dose range, however, the TV response could not be equated to a specific absorbed dose. LDPE film displayed a downward trend from 50 kGy to 250 kGy and then scattering up to 500 kGy; HDPE sheets demonstrated an upward trend in TV formation up to 500 kGy. For ultra-high molecular weight polyethylene (UHMWPE) sheets irradiated up to 150 kGy, TV response was equivalent to non-irradiated UHMWPE, and a minimal upward trend was observed for 200 kGy to 500 kGy. The scatter of the data for the irradiated PE films/sheets is such that the TV response could not be equated to a specific absorbed dose. A better correlation of the post-irradiation TV response to absorbed dose may be attained through a better understanding of variables.

  10. Reflectivity, transmission, and photoinduced infrared spectra of NdNiO{sub 3}

    SciTech Connect

    Massa, N.E.; Alonso, J.A.; Martinez-Lope, M.J.; Rasines, I.

    1997-07-01

    We report temperature-dependent infrared spectra of NdNiO{sub 3} prepared by synthesis under high oxygen pressure. Its room-temperature reflectivity is characteristic of a metal oxide with a Drude tail asymptotically extending to higher frequencies. The sharp metal-insulator transition is detected at about 200 K as phonons become unscreened. While their activity is in the frequency range for a distorted perovskite, the strength of involving the Nd ion against the NiO{sub 6} octahedra at 183cm{sup {minus}1} is remarkable. This and all phonon groups show strong antiresonances near the longitudinal optical frequencies and these are unusually close to absorptions seen in transmission measurements. We interpret this as evidence of strong electron-phonon interactions with carrier localization in a temperature-dependent regime. Low-temperature photoinduced spectra, excited with argon laser lines, support this picture by showing weak absorptions at about those frequencies as well as a relatively very strong photoinduced band at 810cm{sup {minus}1} and one very broad and weak peak at {approximately}2300cm{sup {minus}1} and tail up to 4000cm{sup {minus}1}. They are assigned to electronic transitions involving localized defects. Our measurements suggest that the metal-insulator phase transition in NdNiO{sub 3} is triggered by electron localization in a polaronic environment. We conclude that a suitable order parameter for perovskites with a metal-insulator phase transition may be identified in the coupling between those electrons and local spins {copyright} {ital 1997} {ital The American Physical Society}

  11. Modeling near-infrared reflectance spectra of clay and sulfate mixtures and implications for Mars

    NASA Astrophysics Data System (ADS)

    Stack, K. M.; Milliken, R. E.

    2015-04-01

    High-resolution mapping by visible and near-infrared orbital spectrometers has revealed a diversity of hydrated mineral deposits on the surface of Mars. Quantitative analysis of mineral abundances within these deposits has the potential to distinguish depositional and diagenetic processes. Such analysis can also provide important constraints on the nature of putative global and local-scale mineralogical transitions on Mars. However, the ability of models to extract quantitative mineral abundances from spectra of mixtures relevant to sedimentary rocks remains largely untested. This is particularly true for clay and sulfate minerals, which often occur as fine-grained components of terrestrial sedimentary rocks and are known to occur in a number of sedimentary deposits on Mars. This study examines the spectral properties of a suite of mixtures containing the Mg-sulfate epsomite mixed with varying proportions of smectitic clay (saponite, nontronite, and montmorrilonite). The goal of this work is to test the ability of checkerboard (linear) and intimate (non-linear) mixing models to obtain accurate estimates of mineral abundances under ideal and controlled laboratory conditions. The results of this work suggest that: (1) spectra of clay-sulfate mixtures can be reproduced by checkerboard and intimate mixing models to within 2% absolute reflectance or single scattering albedo, (2) clay and epsomite abundance can be modeled to within 5 wt.% when particle diameter is optimized, and (3) the lower threshold for modeling clay in spectra of clay-epsomite mixtures is approximately 10 wt.%, below which the models often fail to recognize the presence of clay.

  12. Quantification of bovine immunoglobulin G using transmission and attenuated total reflectance infrared spectroscopy.

    PubMed

    Elsohaby, Ibrahim; McClure, J Trenton; Riley, Christopher B; Shaw, R Anthony; Keefe, Gregory P

    2016-01-01

    In this study, we evaluated and compared the performance of transmission and attenuated total reflectance (ATR) infrared (IR) spectroscopic methods (in combination with quantification algorithms previously developed using partial least squares regression) for the rapid measurement of bovine serum immunoglobulin G (IgG) concentration, and detection of failure of transfer of passive immunity (FTPI) in dairy calves. Serum samples (n = 200) were collected from Holstein calves 1-11 days of age. Serum IgG concentrations were measured by the reference method of radial immunodiffusion (RID) assay, transmission IR (TIR) and ATR-IR spectroscopy-based assays. The mean IgG concentration measured by RID was 17.22 g/L (SD ±9.60). The mean IgG concentrations predicted by TIR and ATR-IR spectroscopy methods were 15.60 g/L (SD ±8.15) and 15.94 g/L (SD ±8.66), respectively. RID IgG concentrations were positively correlated with IgG levels predicted by TIR (r = 0.94) and ATR-IR (r = 0.92). The correlation between 2 IR spectroscopic methods was 0.94. Using an IgG concentration <10 g/L as the cut-point for FTPI cases, the overall agreement between TIR and ATR-IR methods was 94%, with a corresponding kappa value of 0.84. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for identifying FTPI by TIR were 0.87, 0.97, 0.91, 0.95, and 0.94, respectively. Corresponding values for ATR-IR were 0.87, 0.95, 0.86, 0.95, and 0.93, respectively. Both TIR and ATR-IR spectroscopic approaches can be used for rapid quantification of IgG level in neonatal bovine serum and for diagnosis of FTPI in dairy calves.

  13. Reanalysis of the Near-infrared Extragalactic Background Light Based on the IRTS Observations

    NASA Astrophysics Data System (ADS)

    Matsumoto, T.; Kim, M. G.; Pyo, J.; Tsumura, K.

    2015-07-01

    We reanalyze data of the near-infrared background taken by IRTS using up-to-date observational results of zodiacal light (ZL), integrated star light, and diffuse Galactic light. We confirm the existence of residual isotropic emission, which is slightly lower but almost the same as previously reported. At wavelengths longer than 2 μm, the result is fairly consistent with the recent observation with AKARI. We also perform the same analysis using a different ZL model by Wright and detect residual isotropic emission that is slightly lower than that based on the original Kelsall model. Both models show residual isotropic emission that is significantly brighter than the integrated light of galaxies.

  14. REANALYSIS OF THE NEAR-INFRARED EXTRAGALACTIC BACKGROUND LIGHT BASED ON THE IRTS OBSERVATIONS

    SciTech Connect

    Matsumoto, T.; Kim, M. G.; Pyo, J.; Tsumura, K.

    2015-07-01

    We reanalyze data of the near-infrared background taken by IRTS using up-to-date observational results of zodiacal light (ZL), integrated star light, and diffuse Galactic light. We confirm the existence of residual isotropic emission, which is slightly lower but almost the same as previously reported. At wavelengths longer than 2 μm, the result is fairly consistent with the recent observation with AKARI. We also perform the same analysis using a different ZL model by Wright and detect residual isotropic emission that is slightly lower than that based on the original Kelsall model. Both models show residual isotropic emission that is significantly brighter than the integrated light of galaxies.

  15. The Use of NASA Light-Emitting Diode Near-Infrared Technology for Biostimulation

    NASA Technical Reports Server (NTRS)

    Whelan, Harry T.

    2002-01-01

    Studies on cells exposed to microgravity and hypergravity indicate that human cells need gravity to stimulate growth. As the gravitational force increases or decreases, the cell function responds in a linear fashion. This poses significant health risks for astronauts in long-term spaceflight. The application of light therapy with the use of NASA LEDs will significantly improve the medical care that is available to astronauts on long-term space missions. NASA LEDs stimulate the basic energy processes in the mitochondria (energy compartments) of each cell, particularly when near-infrared light is used to activate the color sensitive chemicals (chromophores, cytochrome systems) inside. Optimal LED wavelengths include 680, 730 and 880 nm and our laboratory has improved the healing of wounds in laboratory animals by using both NASA LED light and hyperbaric oxygen. Furthermore, DNA synthesis in fibroblasts and muscle cells has been quintupled using NASA LED light alone, in a single application combining 680, 730 and 880 nm each at 4 Joules per centimeter squared. Muscle and bone atrophy are well documented in astronauts, and various minor injuries occurring in space have been reported not to heal until landing on Earth. An LED blanket device may be used for the prevention of bone and muscle atrophy in astronauts. The depth of near-infrared light penetration into human tissue has been measured spectroscopically.

  16. [Research on error reduction of path change of liquid samples based on near infrared trans-reflective spectra measurement].

    PubMed

    Wang, Ya-Hong; Dong, Da-Ming; Zhou, Ping; Zheng, Wen-Gang; Ye, Song; Wang, Wen-Zhong

    2014-10-01

    Based on sucrose solution as the research object, this paper measured the trans-reflective spectrum of sucrose solution of different concentration by the technique of near infrared spectrum in three optical path (4, 5, 6 mm). Five kinds of pretreatment method (vector normalization, baseline offset correction, multiplicative scatter correction, standard normal variate transformation, a derivative) were used to eliminate the influence of the optical path difference, and to establish model of the calibration set in combination with the PLS (Partial Least Squares)method. Five kinds of pretreatment method could restrain the inter ference of light path in varying degrees. Compared with the PLS model of original spectra, the model of multiple scattering correction combined with PLS method is the optimal model. The results of quantitative analysis of original spectra: the number of principal component PC= 6, the determination coefficient R2 = 0.891 278, the determination coefficient of cross validation R2CV = 0.888 374, root mean square error of calibration RMSEC = 1.704%, root mean square error of cross validation RMSECV = 1.827%; The results of quantitative analysis of spectra after MSC pretreatment: the number of principal component PC = 3, the determination coefficient R2 = 0.987 535, the determination coefficient of cross validation R2CV = 0.983 343, root mean square er- ror of calibration RMSEC = 0.89%, root mean square error of cross validation RMSECV = 1.05%. The correlation coefficient of the prediction set is as much as 0.976 22. root mean square error of prediction is 0.01, lesser than 0.014 36. The results show that the MSC can eliminate the influence of optical path difference, improve the prediction precision and improve the stability.

  17. Non-destructively reading out information embedded inside real objects by using far-infrared light

    NASA Astrophysics Data System (ADS)

    Okada, Ayumi; Silapasuphakornwong, Piyarat; Suzuki, Masahiro; Torii, Hideyuki; Takashima, Youichi; Uehira, Kazutake

    2015-09-01

    This paper presents a technique that can non-destructively read out information embedded inside real objects by using far-infrared-light. We propose a technique that can protect the copyrights of digital content for homemade products using digital fabrication technologies such as those used in 3D printers. It embeds information on copyrights inside real objects produced by 3D printers by forming fine structures inside the objects as a watermark that cannot be observed from the outside. Fine structures are formed near the surface inside real objects when they are being fabricated. Information embedded inside real objects needs to be read out non-destructively. We used a technique that could non-destructively read out information from inside real objects by using far-infrared light. We conducted experiments where we structured fine cavities inside objects. The disposition of the fine domain contained valuable information. We used the flat and curved surfaces of the objects to identify them. The results obtained from the experiments demonstrated that the disposition patterns of the fine structures appeared on the surface of objects as a temperature profile when far-infrared light was irradiated on their surface. Embedded information could be read out successfully by analyzing the temperature profile images of the surface of the objects that were captured with thermography and these results demonstrated the feasibility of the technique we propose.

  18. High Resolution Near Infrared Spectrometer to Study the Zodiacal Light Spectrum

    NASA Technical Reports Server (NTRS)

    Kutyrev, Alexander; Arendt, Richard G.; Dwek, Eli; Moseley, Samuel H.; Silverberg, Robert F.; Rapchun, David

    2008-01-01

    We are developing a near infrared spectrometer for measuring solar absorption lines in the zodiacal light in the near infrared region. R. Reynolds at el. (2004, ApJ 612, 1206) demonstrated that observing single Fraunhofer line can be a powerful tool for extracting zodiacal light parameters based on their measurements of the profile of the Mg I line at 5184 A. We are extending this technique to the near infrared with the primary goal of measuring the absolute intensity of the zodiacal light. This measurement will provide the crucial information needed to accurately subtract zodiacal emission from the DIRBE measurements to get a much higher quality measurement of the extragalactic IR background. The instrument design is based on a dual Fabry-Perot interferometer with a narrow band filter. Its double etalon design allows to achieve high spectral contrast to reject the bright out of band telluric OH emission. High spectral contrast is absolutely necessary to achieve detection limits needed to accurately measure the intensity of the absorption line. We present the design, estimated performance of the instrument with the expected results of the observing program.

  19. A color fusion method of infrared and low-light-level images based on visual perception

    NASA Astrophysics Data System (ADS)

    Han, Jing; Yan, Minmin; Zhang, Yi; Bai, Lianfa

    2014-11-01

    The color fusion images can be obtained through the fusion of infrared and low-light-level images, which will contain both the information of the two. The fusion images can help observers to understand the multichannel images comprehensively. However, simple fusion may lose the target information due to inconspicuous targets in long-distance infrared and low-light-level images; and if targets extraction is adopted blindly, the perception of the scene information will be affected seriously. To solve this problem, a new fusion method based on visual perception is proposed in this paper. The extraction of the visual targets ("what" information) and parallel processing mechanism are applied in traditional color fusion methods. The infrared and low-light-level color fusion images are achieved based on efficient typical targets learning. Experimental results show the effectiveness of the proposed method. The fusion images achieved by our algorithm can not only improve the detection rate of targets, but also get rich natural information of the scenes.

  20. Characterization of process-induced damage in Cu/low-k interconnect structure by microscopic infrared spectroscopy with polarized infrared light

    NASA Astrophysics Data System (ADS)

    Seki, Hirofumi; Hashimoto, Hideki; Ozaki, Yukihiro

    2016-09-01

    Microscopic Fourier-transform infrared (FT-IR) spectra are measured for a Cu/low-k interconnect structure using polarized IR light for different widths of low-k spaces and Cu lines, and for different heights of Cu lines, on Si substrates. Although the widths of the Cu line and the low-k space are 70 nm each, considerably smaller than the wavelength of the IR light, the FT-IR spectra of the low-k film were obtained for the Cu/low-k interconnect structure. A suitable method was established for measuring the process-induced damage in a low-k film that was not detected by the TEM-EELS (Transmission Electron Microscope-Electron Energy-Loss Spectroscopy) using microscopic IR polarized light. Based on the IR results, it was presumed that the FT-IR spectra mainly reflect the structural changes in the sidewalls of the low-k films for Cu/low-k interconnect structures, and the mechanism of generating process-induced damage involves the generation of Si-OH groups in the low-k film when the Si-CH3 bonds break during the fabrication processes. The Si-OH groups attract moisture and the OH peak intensity increases. It was concluded that the increase in the OH groups in the low-k film is a sensitive indicator of low-k damage. We achieved the characterization of the process-induced damage that was not detected by the TEM-EELS and speculated that the proposed method is applicable to interconnects with line and space widths of 70 nm/70 nm and on shorter scales of leading edge devices. The location of process-induced damage and its mechanism for the Cu/low-k interconnect structure were revealed via the measurement method.

  1. Spin and orbital angular momenta of light reflected from a cone

    SciTech Connect

    Mansuripur, Masud; Wright, Ewan M.; Zakharian, Armis R.

    2011-09-15

    We examine several retro-reflecting optical elements, each involving two reflections. In the case of a hollow metallic cone having an apex angle of 90 deg., a circularly polarized incident beam acquires, upon reflection, the opposite spin angular momentum. However, no angular momentum is transferred to the cone, because the reflected beam picks up an orbital angular momentum that is twice as large but opposite in direction to that of its spin. A 90 deg. cone made of a transparent material in which the incident light suffers two total internal reflections before returning may be designed to endow the retro-reflected beam with different mixtures of orbital and spin angular momenta. Under no circumstances, however, is it possible to transfer angular momentum from the light beam to the cone without either allowing absorption or breaking the axial symmetry of the cone. A simple example of broken symmetry is provided by a wedge-shaped metallic reflector having an apex angle of 90 deg., which picks up angular momentum upon reflecting a circularly polarized incident beam.

  2. [Multiple scattering of visible and infrared light by sea fog over wind driving rough sea surface].

    PubMed

    Sun, Xian-Ming; Wang, Hai-Hua; Lei, Cheng-Xin; Shen, Jin

    2013-08-01

    The present paper is concerned with computing the multiple scattering characteristics of a sea fog-sea surface couple system within this context. The single scattering characteristics of sea fog were studied by Mie theory, and the multiple scattering of sunlight by single sea fog layer was studied by radiative transfer theory. The reflection function of a statistically rough ocean surface was obtained using the standard Kirchhoff formulation, with shadowing effects taken into account. The reflection properties of the combined sea fog and ocean surface were obtained employing the adding method, and the results indicated that the reflected light intensity of sea fog increased with the sea background.

  3. Potential of near-infrared hyperspectral reflectance imaging for screening of farm feed contamination

    NASA Astrophysics Data System (ADS)

    Wang, Wenbo; Paliwal, Jitendra

    2005-09-01

    With the outbreak of Bovine Spongiform Encephalopathy (BSE) (commonly known as mad cow disease) in 1987 in the United Kingdom and a recent case discovered in Alberta, more and more emphasis is placed on food and farm feed quality and safety issues internationally. The disease is believed to be spread through farm feed contamination by animal byproducts in the form of meat-and-bone-meal (MBM). The paper reviewed the available techniques necessary to the enforcement of legislation concerning the feed safety issues. The standard microscopy method, although highly sensitive, is laborious and costly. A method to routinely screen farm feed contamination certainly helps to reduce the complexity of safety inspection. A hyperspectral imaging system working in the near-infrared wavelength region of 1100-1600 nm was used to study the possibility of detection of ground broiler feed contamination by ground pork. Hyperspectral images of raw broiler feed, ground broiler feed, ground pork, and contaminated feed samples were acquired. Raw broiler feed samples were found to possess comparatively large spectral variations due to light scattering effect. Ground feed adulterated with 1%, 3%, 5%, and 10% of ground pork was tested to identify feed contamination. Discriminant analysis using Mahalanobis distance showed that the model trained using pure ground feed samples and pure ground pork samples resulted in 100% false negative errors for all test replicates of contaminated samples. A discriminant model trained with pure ground feed samples and 10% contamination level samples resulted in 12.5% false positive error and 0% false negative error.

  4. Transparent conductive and near-infrared reflective Ga-doped ZnO/Cu bilayer films grown at room temperature

    SciTech Connect

    Lu, J. G.; Bie, X.; Wang, Y. P.; Gong, L.; Ye, Z. Z.

    2011-05-15

    Bilayer films consisting of Ga-doped ZnO (GZO) and Cu layers were grown at room temperature by magnetron sputtering. The structural, electrical, and optical properties of GZO/Cu bilayer films were investigated in detail. The crystallinity and transparent-conductive properties of the films were correlated with the Cu layer thickness. The GZO/Cu bilayer film with the Cu layer thickness of 7.8 nm exhibited a low resistivity of 7.6x10{sup -5} {Omega} cm and an average visible transmittance of 74%. The reflectance was up to 65% in the near-infrared region for this film. The transparent conductive and near-infrared reflective GZO/Cu bilayer films could be readily deposited at room temperature. The GZO/Cu bilayer films were thermally stable when annealed at temperatures as high as 500 deg. C.

  5. [Study on determining the content of all kinds of composition in the natural rock by near infrared reflectance spectroscopy].

    PubMed

    Li, Jun-Hua; Wu, Wei; He, Yan; Yao, Jin-Zhu; Wu, Xiao-Hong; Deng, Bo

    2013-01-01

    The infrared reflectance spectroscopy from the sample simulating natural-rock prepared by kaolin, muscovite and montmorillonite mixed-powders was obtained by a spectrometer. Spectral data preprocessing was done using SNV. Random forest mathematical modeling was used for predicting the components of rock samples. The smallest root mean square error of the predicted three types of rock composition were 0.088 0, 0.095 6 and 0.121 2 respectively. The predictive studies showed that the application of near infrared diffuse reflectance spectroscopy to determining the content of the natural rocks and minerals of various rock composition is feasible. The study provides a theoretical basis for the rapid detection of the rock composition in the future.

  6. Mitochondrial signal transduction in accelerated wound and retinal healing by near-infrared light therapy.

    PubMed

    Eells, Janis T; Wong-Riley, Margaret T T; VerHoeve, James; Henry, Michele; Buchman, Ellen V; Kane, Mary P; Gould, Lisa J; Das, Rina; Jett, Marti; Hodgson, Brian D; Margolis, David; Whelan, Harry T

    2004-09-01

    Photobiomodulation by light in the red to near infrared range (630-1000 nm) using low energy lasers or light-emitting diode (LED) arrays has been shown to accelerate wound healing, improve recovery from ischemic injury in the heart and attenuate degeneration in the injured optic nerve. Recent evidence indicates that the therapeutic effects of red to near infrared light result, in part, from intracellular signaling mechanisms triggered by the interaction of NIR light with the mitochondrial photoacceptor molecule cytochrome c oxidase. We have demonstrated that NIR-LED photo-irradiation increases the production of cytochrome oxidase in cultured primary neurons and reverses the reduction of cytochrome oxidase activity produced by metabolic inhibitors. We have also shown that NIR-LED treatment prevents the development of oral mucositis in pediatric bone marrow transplant patients. Photobiomodulation improves wound healing in genetically diabetic mice by upregulating genes important in the promotion of wound healing. More recent studies have provided evidence for the therapeutic benefit of NIR-LED treatment in the survival and functional recovery of the retina and optic nerve in vivo after acute injury by the mitochondrial toxin, formic acid generated in the course of methanol intoxication. Gene discovery studies conducted using microarray technology documented a significant upregulation of gene expression in pathways involved in mitochondrial energy production and antioxidant cellular protection. These findings provide a link between the actions of red to near infrared light on mitochondrial oxidative metabolism in vitro and cell injury in vivo. Based on these findings and the strong evidence that mitochondrial dysfunction is involved in the pathogenesis of numerous diseases processes, we propose that NIR-LED photobiomodulation represents an innovative and non-invasive therapeutic approach for the treatment of tissue injury and disease processes in which mitochondrial

  7. Applicability of a Diffuse Reflectance Infrared Fourier Transform handheld spectrometer to perform in situ analyses on Cultural Heritage materials.

    PubMed

    Arrizabalaga, Iker; Gómez-Laserna, Olivia; Aramendia, Julene; Arana, Gorka; Madariaga, Juan Manuel

    2014-08-14

    This work studies the applicability of a Diffuse Reflectance Infrared Fourier Transform handheld device to perform in situ analyses on Cultural Heritage assets. This portable diffuse reflectance spectrometer has been used to characterise and diagnose the conservation state of (a) building materials of the Guevara Palace (15th century, Segura, Basque Country, Spain) and (b) different 19th century wallpapers manufactured by the Santa Isabel factory (Vitoria-Gasteiz, Basque Country, Spain) and by the well known Dufour and Leroy manufacturers (Paris, France), all of them belonging to the Torre de los Varona Castle (Villanañe, Basque Country, Spain). In all cases, in situ measurements were carried out and also a few samples were collected and measured in the laboratory by diffuse reflectance spectroscopy (DRIFT) in order to validate the information obtained by the handheld instrument. In the analyses performed in situ, distortions in the diffuse reflectance spectra can be observed due to the presence of specular reflection, showing the inverted bands caused by the Reststrahlen effect, in particular on those IR bands with the highest absorption coefficients. This paper concludes that the results obtained in situ by a diffuse reflectance handheld device are comparable to those obtained with laboratory diffuse reflectance spectroscopy equipment and proposes a few guidelines to acquire good spectra in the field, minimising the influence caused by the specular reflection.

  8. Diffuse near-infrared reflectance spectroscopy during heatstroke in a mouse model: pilot study

    NASA Astrophysics Data System (ADS)

    Abookasis, David; Zafrir, Elad; Nesher, Elimelech; Pinhasov, Albert; Sternklar, Shmuel; Mathews, Marlon S.

    2012-10-01

    Heatstroke, a form of hyperthermia, is a life-threatening condition characterized by an elevated core body temperature that rises above 40°C (104°F) and central nervous system dysfunction that results in delirium, convulsions, or coma. Without emergency treatment, the victim lapses into a coma and death soon follows. The study presented was conducted with a diffuse reflectance spectroscopy (DRS) setup to assess the effects of brain dysfunction that occurred during heatstroke in mice model (n=6). It was hypothesized that DRS can be utilized in small animal studies to monitor change in internal brain tissue temperature during heatstroke injury since it induces a sequence of pathologic changes that change the tissue composition and structure. Heatstroke was induced by exposure of the mice body under general anesthesia, to a high ambient temperature. A type of DRS in which the brain tissue was illuminated through the intact scalp with a broadband light source and diffuse reflected spectra was employed, taking in the spectral region between 650 and 1000 nm and acquired at an angle of 90 deg at a position on the scalp ˜12 mm from the illumination site. The temperature at the onset of the experiment was ˜34°C (rectal temperature) with increasing intervals of 1°C until mouse death. The increase in temperature caused optical scattering signal changes consistent with a structural alteration of brain tissue, ultimately resulting in death. We have found that the peak absorbance intensity and its second derivative at specific wavelengths correlate well with temperature with an exponential dependence. Based on these findings, in order to estimate the influence of temperature on the internal brain tissue a reflectance-temperature index was established and was seen to correlate as well with measured temperature. Overall, results indicate variations in neural tissue properties during heatstroke and the feasibility to monitor and assess internal temperature variations using

  9. Near-infrared reflectance spectra of mixtures of kaolin-group minerals: use in clay mineral studies

    USGS Publications Warehouse

    Crowley, J.K.; Vergo, N.

    1988-01-01

    Near-infrared (NIR) reflectance spectra for mixtures of ordered kaolinite and ordered dickite have been found to simulate the spectral response of disordered kaolinite. The amount of octahedral vacancy disorder in nine disordered kaolinite samples was estimated by comparing the same spectra to the spectra of reference mixtures. The resulting estimates are consistent with previously published estimates of vacancy disorder for similar kaolin minerals that were modeled from calculated X-ray diffraction patterns. -from Authors

  10. Geographical differentiation of dried lentil seed (Lens culinaris) samples using diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) and discriminant analysis.

    PubMed

    Kouvoutsakis, G; Mitsi, C; Tarantilis, P A; Polissiou, M G; Pappas, C S

    2014-02-15

    Diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) and discriminant analysis were used for the geographical differentiation of dried lentil seed (Lens culinaris) samples. Specifically, 18 Greek samples and nine samples imported from other countries were distinguished using the 2250-1720 and 1275-955 cm⁻¹ spectral regions. The differentiation is complete. The combination of DRIFTS and discriminant analysis enables simple, rapid, cheap and accurate differentiation of commercial lentil seeds in terms of geographical origin.

  11. VUV light reflectivity measurements from PTFE in Liquid Xenon for the LZ Dark Matter experiment

    NASA Astrophysics Data System (ADS)

    Pushkin, Kirill; LZ Collaboration

    2016-03-01

    The LUX-Zeplin (LZ) collaboration is the next generation of the experiment to search for Dark Matter in the Universe with a dual-phase detector based on liquid xenon (LXe) with a target mass of 7 ton. LXe dual phase detectors are very sensitive probes to search for WIMP dark matter interactions. The LZ collaboration is conducting R&D to study VUV light reflectivity from PTFE (Teflon) in LXe. Teflon is used in dual phase detectors both as an electrical insulator and as reflector of VUV scintillation light (~175 nm) to improve photon detection with photomultiplier tubes (PMTs). However, experimental data for the reflectance of VUV light from PTFE in LXe is not sufficiently conclusive. We present a new technique of measuring the light reflectivity from PTFE by varying the fractional area of the PMT in the detector. PTFE reflectivity measurements were performed as a function of Teflon wall thickness in the range of 2 mm to 9.5 mm. The method, apparatus and experimental results will be presented.

  12. The high frequency characteristics of laser reflection and visible light during solid state disk laser welding

    NASA Astrophysics Data System (ADS)

    Gao, Xiangdong; You, Deyong; Katayama, Seiji

    2015-07-01

    Optical properties are related to weld quality during laser welding. Visible light radiation generated from optical-induced plasma and laser reflection is considered a key element reflecting weld quality. An in-depth analysis of the high-frequency component of optical signals is conducted. A combination of a photoelectric sensor and an optical filter helped to obtain visible light reflection and laser reflection in the welding process. Two groups of optical signals were sampled at a high sampling rate (250 kHz) using an oscilloscope. Frequencies in the ranges 1-10 kHz and 10-125 kHz were investigated respectively. Experimental results showed that there was an obvious correlation between the high-frequency signal and the laser power, while the high-frequency signal was not sensitive to changes in welding speed. In particular, when the defocus position was changed, only a high frequency of the visible light signal was observed, while the high frequency of the laser reflection signal remained unchanged. The basic correlation between optical features and welding status during the laser welding process is specified, which helps to provide a new research focus for investigating the stability of welding status.

  13. LightLeaves: computer controlled kinetic reflection hologram installation and a brief discussion of earlier work

    NASA Astrophysics Data System (ADS)

    Connors Chen, Betsy

    2013-02-01

    LightLeaves is an installation combining leaf shaped, white light reflection holograms of landscape images with a special kinetic lighting device that houses a lamp and moving leaf shaped masks. The masks are controlled by an Arduino microcontroller and servomotors that position the masks in front of the illumination source of the holograms. The work is the most recent in a long series of landscapes that combine multi-hologram installations with computer controlled devices that play with the motion of the holograms, the light, sound or other elements in the work. LightLeaves was first exhibited at the Peabody Essex Museum in Salem, Massachusetts in a show titled "Eye Spy: Playing with Perception".

  14. Polarized white light from LEDs using remote-phosphor layer sandwiched between reflective polarizer and light-recycling dichroic filter.

    PubMed

    Oh, Ji Hye; Yang, Su Ji; Do, Young Rag

    2013-09-01

    This study introduces an efficient polarized, white phosphor-converted, light-emitting diode (pc-LED) using a remote phosphor film sandwiched between a reflective polarizer film (RPF) and a short-wavelength pass dichroic filter (SPDF). The on-axis brightness of polarized white light emission of a RPF/SPDF-sandwiched phosphor film over a blue LED, showed greater recovery than that of a conventional unpolarized remote phosphor film over blue LED, due to the recycling effect of yellow light from an SPDF. The relative luminous efficacy of an RPF/SPDF-sandwiched phosphor film was made 1.40 times better by adding an SPDF on the backside of an RPF-capped phosphor film. A polarization ratio of 0.84 was demonstrated for a white LED with an RPF/SPDF-sandwiched phosphor film, in good agreement with the measured results from the RPF-only sample.

  15. Light scattering by a rough surface of human skin. 2. Diffuse reflectance

    SciTech Connect

    Barun, V V; Ivanov, A P

    2013-10-31

    Based on the previously calculated luminance factors, we have investigated the integral characteristics of light reflection from a rough surface of the skin with large-scale inhomogeneities under various conditions of the skin illumination. Shadowing of incident and scattered beams by relief elements is taken into account. Diffuse reflectances by the Gaussian and the quasi-periodic surfaces are compared and, in general, both these roughness models are shown to give similar results. We have studied the effect of the angular structure of radiation multiply scattered deep in the tissue and the refraction of rays as they propagate from the dermis to the surface of the stratum corneum on the reflection characteristics of the skin surface. The importance of these factors is demonstrated. The algorithms constructed can be included in the schemes of calculation of the light fields inside and outside the medium in solving various direct and inverse problems of optics of biological tissues. (biophotonics)

  16. Seeing people in different light--joint shape, motion, and reflectance capture.

    PubMed

    Theobalt, Christian; Ahmed, Naveed; Lensch, Hendrik; Magnor, Marcus; Seidel, Hans-Peter

    2007-01-01

    By means of passive optical motion capture, real people can be authentically animated and photo-realistically textured. To import real-world characters into virtual environments, however, surface reflectance properties must also be known. We describe a video-based modeling approach that captures human shape and motion as well as reflectance characteristics from a handful of synchronized video recordings. The presented method is able to recover spatially varying surface reflectance properties of clothes from multiview video footage. The resulting model description enables us to realistically reproduce the appearance of animated virtual actors under different lighting conditions, as well as to interchange surface attributes among different people, e.g., for virtual dressing. Our contribution can be used to create 3D renditions of real-world people under arbitrary novel lighting conditions on standard graphics hardware.

  17. Action potential propagation imaged with high temporal resolution near-infrared video microscopy and polarized light

    PubMed Central

    Schei, Jennifer L.; McCluskey, Matthew D.; Foust, Amanda J.; Yao, Xin-Cheng; Rector, David M.

    2008-01-01

    To identify the neural constituents responsible for generating polarized light changes, we created spatially resolved movies of propagating action potentials from stimulated lobster leg nerves using both reflection and transmission imaging modalities. Changes in light polarization are associated with membrane depolarization and provide sub-millisecond temporal resolution. Typically, signals are detected using light transmitted through tissue; however, because we eventually would like to apply polarization techniques in-vivo, reflected light is required. In transmission mode, the optical signal was largest throughout the center of the nerve, suggesting that most of the optical signal arose from the inner nerve bundle. In reflection mode, polarization changes were largest near the edges, suggesting that most of the optical signal arose from the outer sheath. In support of these observations, an optical model of the tissue showed that the outer sheath is more reflective while the inner nerve bundle is more transmissive. In order to apply these techniques in-vivo, we must consider that brain tissue does not have a regular orientation of processes as in the lobster nerve. We tested the effect of randomizing cell orientation by tying the nerve in an overhand knot prior to imaging, producing polarization changes that can be imaged even without regular cell orientations. PMID:18272402

  18. Simulation of reflected light intensity changes during navigation and radio-frequency lesioning in the brain.

    PubMed

    Johansson, Johannes D; Fredriksson, Ingemar; Wårdell, Karin; Eriksson, Ola

    2009-01-01

    An electrode with adjacent optical fibers for measurements during navigation and radio frequency lesioning in the brain is modeled for Monte Carlo simulations of light transport in brain tissue. Relative reflected light intensity at 780 nm, I780, from this electrode and probes with identical fiber configuration are simulated using the intensity from native white matter as reference. Models are made of homogeneous native and coagulated gray, thalamus, and white matter as well as blood. Dual layer models, including models with a layer of cerebrospinal fluid between the fibers and the brain tissue, are also made. Simulated I780 was 0.16 for gray matter, 0.67 for coagulate gray matter, 0.36 for thalamus, 0.39 for coagulated thalamus, unity for white matter, 0.70 for coagulated white matter, and 0.24 for blood. Thalamic matter is also found to reflect more light than gray matter and less than white matter in clinical studies. In conclusion, the reflected light intensity can be used to differentiate between gray and white matter during navigation. Furthermore, coagulation of light gray tissue, such as the thalamus, might be difficult to detect using I780, but coagulation in darker gray tissue should result in a rapid increase of I780.

  19. Simulation of reflected light intensity changes during navigation and radio-frequency lesioning in the brain

    NASA Astrophysics Data System (ADS)

    Johansson, Johannes D.; Fredriksson, Ingemar; Wa˚Rdell, Karin; Eriksson, Ola

    2009-07-01

    An electrode with adjacent optical fibers for measurements during navigation and radio frequency lesioning in the brain is modeled for Monte Carlo simulations of light transport in brain tissue. Relative reflected light intensity at 780 nm, I780, from this electrode and probes with identical fiber configuration are simulated using the intensity from native white matter as reference. Models are made of homogeneous native and coagulated gray, thalamus, and white matter as well as blood. Dual layer models, including models with a layer of cerebrospinal fluid between the fibers and the brain tissue, are also made. Simulated I780 was 0.16 for gray matter, 0.67 for coagulate gray matter, 0.36 for thalamus, 0.39 for coagulated thalamus, unity for white matter, 0.70 for coagulated white matter, and 0.24 for blood. Thalamic matter is also found to reflect more light than gray matter and less than white matter in clinical studies. In conclusion, the reflected light intensity can be used to differentiate between gray and white matter during navigation. Furthermore, coagulation of light gray tissue, such as the thalamus, might be difficult to detect using I780, but coagulation in darker gray tissue should result in a rapid increase of I780.

  20. Visible light and near-infrared-responsive chromophores for drug delivery-on-demand applications.

    PubMed

    Linsley, Chase S; Quach, Viola Y; Agrawal, Gaurav; Hartnett, Elyse; Wu, Benjamin M

    2015-12-01

    The need for temporal-spatial control over the release of biologically active molecules has motivated efforts to engineer novel drug delivery-on-demand strategies actuated via light irradiation. Many systems, however, have been limited to in vitro proof-of-concept due to biocompatibility issues with the photo-responsive moieties or the light wavelength, intensity, and duration. To overcome these limitations, this paper describes a light actuated drug delivery-on-demand strategy that uses visible and near-infrared (NIR) light and biocompatible chromophores: cardiogreen, methylene blue, and riboflavin. All three chromophores are capable of significant photothermal reaction upon exposure to NIR and visible light, and the amount of temperature change is dependent upon light intensity, wavelength as well as chromophore concentration. Pulsatile release of bovine serum albumin (BSA) from thermally responsive hydrogels was achieved over 4 days. These findings have the potential to translate light-actuated drug delivery-on-demand systems from the bench to clinical applications that require explicit control over the presentation of biologically active molecules.

  1. Visible light and near infrared-responsive chromophores for drug delivery-on-demand applications

    PubMed Central

    Linsley, Chase S.; Quach, Viola Y.; Agrawal, Gaurav; Hartnett, Elyse; Wu, Benjamin M.

    2016-01-01

    The need for temporal-spatial control over the release of biologically active molecules has motivated efforts to engineer novel drug delivery-on-demand strategies actuated via light irradiation. Many systems, however, have been limited to in vitro proof-of-concept due to biocompatibility issues with the photo-responsive moieties or the light wavelength, intensity and duration. To overcome these limitations, this paper describes a light actuated drug delivery-on-demand strategy that uses visible and near infrared (NIR) light and biocompatible chromophores: cardiogreen, methylene blue and riboflavin. All 3 chromophores are capable of significant photothermal reaction upon exposure to NIR and visible light, and the amount of temperature change is dependent upon light intensity, wavelength as well as chromophore concentration. Pulsatile release of bovine serum albumin (BSA) from thermally-responsive hydrogels was achieved over 4 days. These findings have the potential to translate light actuated drug delivery-on-demand systems from the bench to clinical applications that require explicit control over the presentation of biologically active molecules. PMID:26423655

  2. Plasmonic caged gold nanorods for near-infrared light controlled drug delivery

    NASA Astrophysics Data System (ADS)

    Xiong, Wei; Mazid, Romiza; Yap, Lim Wei; Li, Xinyong; Cheng, Wenlong

    2014-11-01

    A new near-infrared light-controlled drug delivery system based on caged gold nanorods (CGNRs) is demonstrated. The loading and release process of drug payloads into/from CGNR nanocarriers were systematically investigated. The drug-loaded CGNR constructs could enable combined chemotherapy and photo-thermal effects in killing tumor cells upon light irradiation, therefore, enhance the killing efficiency. In conjunction with visibility under quenching-free dark-field imaging, CGNRs may serve as multifunctional theranostic reagents towards cancer diagnostics and therapeutics.A new near-infrared light-controlled drug delivery system based on caged gold nanorods (CGNRs) is demonstrated. The loading and release process of drug payloads into/from CGNR nanocarriers were systematically investigated. The drug-loaded CGNR constructs could enable combined chemotherapy and photo-thermal effects in killing tumor cells upon light irradiation, therefore, enhance the killing efficiency. In conjunction with visibility under quenching-free dark-field imaging, CGNRs may serve as multifunctional theranostic reagents towards cancer diagnostics and therapeutics. Electronic supplementary information (ESI) available: Calculation of the SERS enhancement factor of CGNRs, tunable UV-vis absorbance for CGNRs, TEM images for CGNRs loaded with nile red, dark field images of HeLaGFP cells uptaken with CGNRs loaded with Dox. See DOI: 10.1039/c4nr04400b

  3. Carbon nanotube-assisted optical activation of TGF-β signalling by near-infrared light

    NASA Astrophysics Data System (ADS)

    Lin, Liang; Liu, Ling; Zhao, Bing; Xie, Ran; Lin, Wei; Li, He; Li, Yaya; Shi, Minlong; Chen, Ye-Guang; Springer, Timothy A.; Chen, Xing

    2015-05-01

    Receptor-mediated signal transduction modulates complex cellular behaviours such as cell growth, migration and differentiation. Although photoactivatable proteins have emerged as a powerful tool for controlling molecular interactions and signalling cascades at precise times and spaces using light, many of these light-sensitive proteins are activated by ultraviolent or visible light, which has limited tissue penetration. Here, we report a single-walled carbon nanotube (SWCNT)-assisted approach that enables near-infrared light-triggered activation of transforming growth factor β (TGF-β) signal transduction, an important signalling pathway in embryonic development and cancer progression. The protein complex of TGF-β and its latency-associated peptide is conjugated onto SWCNTs, where TGF-β is inactive. Upon near-infrared irradiation, TGF-β is released through the photothermal effect of SWCNTs and becomes active. The released TGF-β activates downstream signal transduction in live cells and modulates cellular behaviours. Furthermore, preliminary studies show that the method can be used to mediate TGF-β signalling in living mice.

  4. Gallium antimonide texturing for enhanced light extraction from infrared optoelectronics devices

    NASA Astrophysics Data System (ADS)

    Wassweiler, Ella; Toor, Fatima

    2016-06-01

    The use of gallium antimonide (GaSb) is increasing, especially for optoelectronic devices in the infrared wavelengths. It has been demonstrated in gallium nitride (GaN) devices operating at ultraviolet (UV) wavelengths, that surface textures increase the overall device efficiency. In this work, we fabricated eight different surface textures in GaSb to be used in enhancing efficiency in infrared wavelength devices. Through chemical etching with hydrofluoric acid, hydrogen peroxide, and tartaric acid we characterize the types of surface textures formed and the removal rate of entire layers of GaSb. Through optimization of the etching recipes we lower the reflectivity from 35.7% to 1% at 4 μm wavelength for bare and textured GaSb, respectively. In addition, we simulate surface textures using ray optics in finite element method solver software to provide explanation of our experimental findings.

  5. Variability of light absorption by aquatic particles in the near-infrared spectral region

    NASA Astrophysics Data System (ADS)

    Tassan, Stelvio; Ferrari, Giovanni M.

    2003-08-01

    We have measured the light absorption of a set of particle suspensions of varying nature (pure minerals, particulate standards, aquatic particles) using a double-beam spectrophotometer with a 15-cm-diameter integrating sphere. The sample was located inside the sphere so as to minimize the effect of light scattering by the particles. The results obtained showed highly variable absorption in the near-IR region of the wavelength spectrum. The same particle samples were deposited on glass-fiber filters, and their absorption was measured by the transmittance-reflectance method, based on a theoretical model that corrects for the effect of light scattering. The good agreement found between the results of the measurements carried out inside the sphere and by the transmittance-reflectance method confirms the validity of the scattering correction included in the above method.

  6. Infrared external reflection spectroscopic studies of phase transitions in Langmuir monolayers of stearyl alcohol

    NASA Astrophysics Data System (ADS)

    Buontempo, Joseph T.; Rice, Stuart A.

    1993-11-01

    There is a steadily growing body of evidence that much of the information available concerning the properties of Langmuir monolayers concerns systems which are not in a state of equilibrium. What are now known to be unrelaxed monolayers of stearyl alcohol exhibit a high surface pressure phase transition whose signature in the isotherm changes from a ``kink'' (0-8 °C), to a small nearly flat region (8-15 °C), and finally to another kink (at higher temperatures). We have carried out external reflection infrared spectroscopic studies of relaxed monolayers of stearyl alcohol along a representative isotherm from each of the mentioned temperature regions. The results of our studies indicate that in each region the surfactant hydrocarbon chain becomes more ordered (i.e., has fewer gauche conformations) as the surface pressure is increased. We find that (i) at 5 °C, throughout the surface pressure range where the change in intramolecular chain order occurs, the collective tilt of the hydrocarbon chains remains nearly constant. For this isotherm the kink signals the point at which the hydrocarbon chains have achieved a very high degree of intramolecular order, perhaps the all-trans limit. (ii) In the 11 °C monolayer, in the phase often referred to as ``superfluid'', the intramolecular disorder in the hydrocarbon chains is measurably greater than in the equivalent phases in the higher and lower temperature regions. We also show that in the relaxed monolayer the nearly flat portion of the isotherm observed in the unrelaxed monolayer is almost totally absent, leaving only a kink very similar to those observed at higher and lower temperatures. (iii) At 25 °C, although the hydrocarbon chains in the relaxed monolayer attain a relatively high degree of intramolecular order, the high surface pressure phase transition is not observed. Instead, the surface pressure levels off at a value below that at which the transition is expected, and below the equilibrium spreading pressure

  7. Analysis of reflection, transmission and absorption of frequency selective surfaces in the infrared

    NASA Astrophysics Data System (ADS)

    Puscasu, Irina

    Frequency-selective surfaces (FSSs) are commonly used as dichroic filters in the microwave portion of the spectrum. These filters are typically configured as periodic arrays of metallic patches supported by a dielectric substrate, or as an array of apertures on a metallic sheet. To first order, the current-wave resonance of the individual patches or apertures determines the spectral behavior of the structure. The resonant dimension of the structures is on the order of a wavelength of the incident radiation. Using the high- resolution capabilities of direct-write electron-beam lithography (DEBL), the functionality of an FSS can be extended toward shorter wavelengths-into the infrared (IR), and even to visible wavelengths. Design of FSSs at these short wavelengths presents new problems-the usual assumption of perfect metal conductivity is not valid in the IR. In our method-of- moments model, we use a frequency-dependent complex conductivity to characterize the metallic structure, which allows prediction of the location, magnitude, and spectral width of the resonance. We compare the measured behavior of our IR FSSs to the theoretical predictions and find good agreement over a wide range of structure sizes and materials. Treating the loss mechanism in this way allows us to predict resonant effects not only for reflection and transmission, but for absorption as well. Kirchoff's Law, which states that absorption and emissivity are equal on a spectral basis, provides a means to develop IR FSSs for which the spectral emissivity can be enhanced over a desired range of wavelengths. This characteristic has potential application in development of new sources for IR spectroscopy, and in IR-signature management. Fabrication of IR FSSs by DEBL allows fine control over the dimensions of the metallic elements, but the direct write process is slow and hence too expensive for practical development of large-area IR FSSs. We investigated precision imprint embossing as a candidate

  8. First Light from the Far-Infrared Spectroscopy of the Troposphere (FIRST) Instrument

    NASA Technical Reports Server (NTRS)

    Mlynczak, Martin G.; Johnson, David G.; Latvakoski, Harri; Jucks, Kenneth; Watson, Mike; Bingham, Gail; Kratz, David P.; Traub, Wesley A.; Wellard, Stanley J.; Hyde, Charles R.; Liu, Xu

    2005-01-01

    We present first light spectra from the new Far-Infrared Spectroscopy of the Troposphere (FIRST) instrument. FIRST is a Fourier Transform Spectrometer developed to measure accurately the far-infrared (15 to 100 micrometers; 650 to 100 wavenumbers) emission spectrum of the Earth and its atmosphere. The observations presented here were obtained during a high altitude balloon flight from Ft. Sumner, New Mexico on 7 June 2005. The flight data demonstrate the instrument's ability to observe the entire energetically significant infrared emission spectrum (50 to 2000 wavenumbers) at high spectral and spatial resolution on a single focal plane in an instrument with one broad spectral bandpass beamsplitter. Comparisons with radiative transfer calculations demonstrate that FIRST accurately observes the very fine spectral structure in the far-infrared. Comparisons of the atmospheric window radiances measured by FIRST and by instruments on the NASA Aqua satellite that overflew FIRST are in excellent agreement. FIRST opens a new window on the spectrum that can be used for studying atmospheric radiation and climate, cirrus clouds, and water vapor in the upper troposphere.

  9. Illuminating Cell Signaling with Near-Infrared Light-Responsive Nanomaterials

    PubMed Central

    Li, Zhanjun; Ma, Guolin; Zhou, Yubin; Han, Gang

    2016-01-01

    The regulation of cellular signaling in vivo has been a challenging task owing to the lack of effective methods for tunable control of the amplitude, location, and duration of cell-signaling events at a deep-tissue level. In this issue of ACS Nano, an intriguing paper by Ambrosone et al. demonstrates that deep-tissue-penetrating near-infrared (NIR) light can be used to control the Wnt/β-catenin-signaling pathway in a single-cell organism (Hydra) by utilizing microcapsules that contain plasmonic gold nanoparticles. In parallel, in recent work, we proposed upconversion nanoparticles (UCNPs) as NIR-light-activatable “wireless” optogenetic tools, and we showed their ability to modulate cell signaling pathways in both mammalian cells and mice. We believe that these interesting NIR-light-responsive nanotechnologies will open new avenues for both basic research and clinical applications. PMID:27077481

  10. Monolayer graphene/germanium Schottky junction as high-performance self-driven infrared light photodetector.

    PubMed

    Zeng, Long-Hui; Wang, Ming-Zheng; Hu, Han; Nie, Biao; Yu, Yong-Qiang; Wu, Chun-Yan; Wang, Li; Hu, Ji-Gang; Xie, Chao; Liang, Feng-Xia; Luo, Lin-Bao

    2013-10-01

    We report on the simple fabrication of monolayer graphene (MLG)/germanium (Ge) heterojunction for infrared (IR) light sensing. It is found that the as-fabricated Schottky junction detector exhibits obvious photovoltaic characteristics, and is sensitive to IR light with high Ilight/Idark ratio of 2 × 10(4) at zero bias voltage. The responsivity and detectivity are as high as 51.8 mA W(-1) and 1.38 × 10(10) cm Hz(1/2) W(-1), respectively. Further photoresponse study reveals that the photovoltaic IR detector displays excellent spectral selectivity with peak sensitivity at 1400 nm, and a fast light response speed of microsecond rise/fall time with good reproducibility and long-term stability. The generality of the above results suggests that the present MLG/Ge IR photodetector would have great potential for future optoelectronic device applications.

  11. Gold nanocages covered by smart polymers for controlled release with near-infrared light

    NASA Astrophysics Data System (ADS)

    Yavuz, Mustafa S.; Cheng, Yiyun; Chen, Jingyi; Cobley, Claire M.; Zhang, Qiang; Rycenga, Matthew; Xie, Jingwei; Kim, Chulhong; Song, Kwang H.; Schwartz, Andrea G.; Wang, Lihong V.; Xia, Younan

    2009-12-01

    Photosensitive caged compounds have enhanced our ability to address the complexity of biological systems by generating effectors with remarkable spatial/temporal resolutions. The caging effect is typically removed by photolysis with ultraviolet light to liberate the bioactive species. Although this technique has been successfully applied to many biological problems, it suffers from a number of intrinsic drawbacks. For example, it requires dedicated efforts to design and synthesize a precursor compound for each effector. The ultraviolet light may cause damage to biological samples and is suitable only for in vitro studies because of its quick attenuation in tissue. Here we address these issues by developing a platform based on the photothermal effect of gold nanocages. Gold nanocages represent a class of nanostructures with hollow interiors and porous walls. They can have strong absorption (for the photothermal effect) in the near-infrared while maintaining a compact size. When the surface of a gold nanocage is covered with a smart polymer, the pre-loaded effector can be released in a controllable fashion using a near-infrared laser. This system works well with various effectors without involving sophisticated syntheses, and is well suited for in vivo studies owing to the high transparency of soft tissue in the near-infrared region.

  12. Near-infrared roll-off-free electroluminescence from highly stable diketopyrrolopyrrole light emitting diodes

    PubMed Central

    Sassi, Mauro; Buccheri, Nunzio; Rooney, Myles; Botta, Chiara; Bruni, Francesco; Giovanella, Umberto; Brovelli, Sergio; Beverina, Luca

    2016-01-01

    Organic light emitting diodes (OLEDs) operating in the near-infrared spectral region are gaining growing relevance for emerging photonic technologies, such as lab-on-chip platforms for medical diagnostics, flexible self-medicated pads for photodynamic therapy, night vision and plastic-based telecommunications. The achievement of efficient near-infrared electroluminescence from solution-processed OLEDs is, however, an open challenge due to the low photoluminescence efficiency of most narrow-energy-gap organic emitters. Diketopyrrolopyrrole-boron complexes are promising candidates to overcome this limitation as they feature extremely high photoluminescence quantum yield in the near-infrared region and high chemical stability. Here, by incorporating suitably functionalized diketopyrrolopyrrole derivatives emitting at ~760 nm in an active matrix of poly(9,9-dioctylfluorene-alt-benzothiadiazole) and without using complex light out-coupling or encapsulation strategies, we obtain all-solution-processed NIR-OLEDs with external quantum efficiency as high as 0.5%. Importantly, our test-bed devices show no efficiency roll-off even for high current densities and high operational stability, retaining over 50% of the initial radiant emittance for over 50 hours of continuous operation at 10 mA/cm2, which emphasizes the great applicative potential of the proposed strategy. PMID:27677240

  13. Detecting and distinguishing metamorphic gradients of Unequilibrated (Type 3) Ordinary Chondrites using Infrared Reflectance Spectra.

    NASA Astrophysics Data System (ADS)

    Trivedi, M.; Smith, H. D.; Sears, D. W. G.

    2014-09-01

    We measure the IR reflectance spectra of fallen UOC to determine if Type 3 meteorites can be identified and classified using IR reflectance spectra and clinopyroxene abundance. Spectra was obtained from RELAB and taken on samples from SI and NHM.

  14. A Mid-Infrared Emission and Reflectance Library of Meteorites and Fine Particulate Phases

    NASA Astrophysics Data System (ADS)

    Osterloo, M. M.; Hamilton, V. E.

    2011-12-01

    We have acquired middle infrared (MIR) emission and reflectance spectra of fine particulate minerals and solid and fine particulate meteorite samples under ambient conditions. This dataset is intended to help expand our ability to interpret the MIR spectra of asteroids, possible extinct comets, and other rocky bodies, which contain a record of processes that are key to understanding the formation of our solar system 4.6 G.y. ago. Non-destructive MIR spectra of all samples in this study were collected in the spectroscopy laboratory at Southwest Research Institute [Hamilton and Lucey, 2005, LPSC XXXVI]. We measured the MIR spectra of fine particulate meteorite samples with the objective of providing the planetary community a dataset that can be used for qualitative comparison to asteroid spectra. The current library [Salisbury et al., 1991, Icarus] that is used for comparison to asteroid emissivity spectra represents particle size fractions of < 75 μm. However, several studies have demonstrated that this may be too large a size fraction to be analogous to low inertia asteroid regoliths [e.g., Barucci et al. 2002, Icarus; Emery et al. 2006, Icarus]. Therefore, our MIR spectral library includes a series of meteorite powders having smaller size fractions that may be more analogous to the regoliths of large, low inertia asteroids and will be beneficial for qualitative comparisons. The Smithsonian Institute's analyzed Meteorite Powered Collections (USNM 7073) provided particulate meteorite samples. At this time we have focused on chondritic and a few achondrite samples with particle size fractions < 25 μm. The samples chosen represent many of the samples that were originally measured by Salisbury et al. [1991, Icarus], providing continuity with the existing larger particle size spectral dataset. Furthermore, this work is the first to obtain spectral data of meteorites at wavelengths greater than 13.5 μm, which contain diagnostic features in silicates, carbonates, and

  15. Predicting ambient aerosol thermal-optical reflectance (TOR) measurements from infrared spectra: organic carbon

    NASA Astrophysics Data System (ADS)

    Dillner, A. M.; Takahama, S.

    2015-03-01

    Organic carbon (OC) can constitute 50% or more of the mass of atmospheric particulate matter. Typically, organic carbon is measured from a quartz fiber filter that has been exposed to a volume of ambient air and analyzed using thermal methods such as thermal-optical reflectance (TOR). Here, methods are presented that show the feasibility of using Fourier transform infrared (FT-IR) absorbance spectra from polytetrafluoroethylene (PTFE or Teflon) filters to accurately predict TOR OC. This work marks an initial step in proposing a method that can reduce the operating costs of large air quality monitoring networks with an inexpensive, non-destructive analysis technique using routinely collected PTFE filter samples which, in addition to OC concentrations, can concurrently provide information regarding the composition of organic aerosol. This feasibility study suggests that the minimum detection limit and errors (or uncertainty) of FT-IR predictions are on par with TOR OC such that evaluation of long-term trends and epidemiological studies would not be significantly impacted. To develop and test the method, FT-IR absorbance spectra are obtained from 794 samples from seven Interagency Monitoring of PROtected Visual Environment (IMPROVE) sites collected during 2011. Partial least-squares regression is used to calibrate sample FT-IR absorbance spectra to TOR OC. The FTIR spectra are divided into calibration and test sets by sampling site and date. The calibration produces precise and accurate TOR OC predictions of the test set samples by FT-IR as indicated by high coefficient of variation (R2; 0.96), low bias (0.02 μg m-3, the nominal IMPROVE sample volume is 32.8 m3), low error (0.08 μg m-3) and low normalized error (11%). These performance metrics can be achieved with various degrees of spectral pretreatment (e.g., including or excluding substrate contributions to the absorbances) and are comparable in precision to collocated TOR measurements. FT-IR spectra are also

  16. ELiXIR—Solid-State Luminaire With Enhanced Light Extraction by Internal Reflection

    NASA Astrophysics Data System (ADS)

    Allen, Steven C.; Steckl, Andrew J.

    2007-06-01

    A phosphor-converted light-emitting diode (pcLED) luminaire featuring enhanced light extraction by internal reflection (ELiXIR) with efficacy of 60 lm/W producing 18 lumens of yellowish green light at 100 mA is presented. The luminaire consists of a commercial blue high power LED, a polymer hemispherical shell lens with interior phosphor coating, and planar aluminized reflector. High extraction efficiency of the phosphor-converted light is achieved by separating the phosphor from the LED and using internal reflection to steer the light away from lossy reflectors and the LED package and out of the device. At 10 and 500 mA, the luminaire produces 2.1 and 66 lumens with efficacies of 80 and 37 lm/W, respectively. Technological improvements over existing commercial LEDs, such as more efficient pcLED packages or, alternatively, higher efficiency green or yellow for color mixing, will be essential to achieving 150 200 lm/W solid-state lighting. Advances in both areas are demonstrated.

  17. Electromagnetic radiation energy arrangement. [coatings for solar energy absorption and infrared reflection

    NASA Technical Reports Server (NTRS)

    Lipkis, R. R.; Vehrencamp, J. E. (Inventor)

    1965-01-01

    A solar energy collector and infrared energy reflector is described which comprises a vacuum deposited layer of aluminum of approximately 200 to 400 Angstroms thick on one side of a substrate. An adherent layer of titanium with a thickness of between 800 and 1000 Angstroms is vacuum deposited on the aluminum substrate and is substantially opaque to solar energy and substantially transparent to infrared energy.

  18. Visible and near-infrared (0.4-2.5 μm) reflectance spectra of playa evaporite minerals

    USGS Publications Warehouse

    Crowley, James K.

    1991-01-01

    Visible and near-infrared (VNIR; 0.4–2.4 μm) reflectance spectra were recorded for 35 saline minerals that represent the wide range of mineral and brine chemical compositions found in playa evaporite settings. The spectra show that many of the saline minerals exhibit diagnostic near-infrared absorption bands, chiefly attributable to vibrations of hydrogen-bonded structural water molecules. VNIR reflectance spectra can be used to detect minor hydrate phases present in mixtures dominated by anhydrous halite or thenardite, and therefore will be useful in combination with X ray diffraction data for characterizing natural saline mineral assemblages. In addition, VNIR reflectance spectra are sensitive to differences in sample hydration state and should facilitate in situ studies of minerals that occur as fragile, transitory dehydration products in natural salt crusts. The use of spectral reflectance measurements in playa studies should aid in mapping evaporite mineral distributions and may provide insight into the geochemical and hydrological controls on playa mineral and brine development.

  19. Effect of leaf variables on visible, near-infrared and mid-infrared reflectance of excised leaves

    NASA Technical Reports Server (NTRS)

    Bell, R.; Labovitz, M. L.; Ludwig, R. W.

    1983-01-01

    Effects of an imposed (excised) leaf orientation, differing species and differing venation patterns on reflectance measurements in the LANDSAT-4 thematic mapper (TM) channels TM3 (0.63 to 0.69 microns), TM4 (0.76 to 0.90 microns), and TM5 (1.55 to 1.75 microns) were investigated. Orientation of leaves (random vs. systematic placement) was found to affect measurements in the TM4 channel, but not the TM3 and TM5 measurements. Venation caused no significant changes for any band. Azimuth of incident radiation was not a significant main effect, but in conjunction with changes in orientation, angle did have a significant effect on reflectance values in TM3, TM4 and TM5. Specific differences were highly significant (P f or = 0.006) in all but one borderline (P F or = 0.0222) case for TM5. For spectral examination of excised leaves, the sampling arrangement of the leaves should as closely approximate in situ positioning as possible (with respect to remote sensing instrumentation). This dictates a random rather than aligned arrangement.

  20. Near-infrared light-responsive composite microneedles for on-demand transdermal drug delivery.

    PubMed

    Chen, Mei-Chin; Ling, Ming-Hung; Wang, Kuan-Wen; Lin, Zhi-Wei; Lai, Bo-Hung; Chen, Dong-Hwang

    2015-05-11

    This study presents near-infrared (NIR) light-responsive polymer-nanostructure composite microneedles used for on-demand transdermal drug delivery. Silica-coated lanthanum hexaboride (LaB6@SiO2) nanostructures were incorporated into polycaprolactone microneedles, serving as an NIR absorber. When the microneedles were irradiated with NIR light, light-to-heat transduction mediated by the LaB6@SiO2 nanostructures caused the microneedle melting at 50 °C. This increased the mobility of the polymer chains, enabling drug release from the matrix. Drug release from the microneedles was evaluated for four laser on/off cycles. In each cycle, the samples were irradiated until the temperature reached 50 °C for 3 min (laser on); the laser was then turned off for 30 min (laser off). The results showed that light-induced phase transition in the polymer triggered drug release from the melted microneedles. A stepwise drug-release behavior was observed after multiple cycles of NIR light exposure. No notable drug leakage was found in the off state. This NIR-light-triggerable device exhibits excellent reproducibility, low off-state leakage, and noninvasive triggerability and, thus, represents an advance in transdermal delivery technology.

  1. THE FIRST MAXIMUM-LIGHT ULTRAVIOLET THROUGH NEAR-INFRARED SPECTRUM OF A TYPE Ia SUPERNOVA

    SciTech Connect

    Foley, Ryan J.; Marion, G. Howie; Challis, Peter; Kirshner, Robert P.; Berta, Zachory K.; Kromer, Markus; Taubenberger, Stefan; Hillebrandt, Wolfgang; Roepke, Friedrich K.; Ciaraldi-Schoolmann, Franco; Seitenzahl, Ivo R.; Pignata, Giuliano; Stritzinger, Maximilian D.; Filippenko, Alexei V.; Li Weidong; Silverman, Jeffrey M.; Folatelli, Gaston; Hsiao, Eric Y.; Morrell, Nidia I.; Simcoe, Robert A.; and others

    2012-07-01

    We present the first maximum-light ultraviolet (UV) through near-infrared (NIR) Type Ia supernova (SN Ia) spectrum. This spectrum of SN 2011iv was obtained nearly simultaneously by the Hubble Space Telescope at UV/optical wavelengths and the Magellan Baade telescope at NIR wavelengths. These data provide the opportunity to examine the entire maximum-light SN Ia spectral energy distribution. Since the UV region of an SN Ia spectrum is extremely sensitive to the composition of the outer layers of the explosion, which are transparent at longer wavelengths, this unprecedented spectrum can provide strong constraints on the composition of the SN ejecta, and similarly the SN explosion and progenitor system. SN 2011iv is spectroscopically normal, but has a relatively fast decline ({Delta}m{sub 15}(B) = 1.69 {+-} 0.05 mag). We compare SN 2011iv to other SNe Ia with UV spectra near maximum light and examine trends between UV spectral properties, light-curve shape, and ejecta velocity. We tentatively find that SNe with similar light-curve shapes but different ejecta velocities have similar UV spectra, while those with similar ejecta velocities but different light-curve shapes have very different UV spectra. Through a comparison with explosion models, we find that both a solar-metallicity W7 and a zero-metallicity delayed-detonation model provide a reasonable fit to the spectrum of SN 2011iv from the UV to the NIR.

  2. Grating-coupled mid-infrared light emission from tensilely strained germanium nanomembranes

    SciTech Connect

    Boztug, Cicek; Yin, Jian; Paiella, Roberto; Sánchez-Pérez, José R.; Lagally, Max G.

    2013-11-11

    Mechanically stressed nanomembranes are used to demonstrate mid-infrared interband light emission from Ge within the 2.1–2.5 μm atmospheric transmission window. Large biaxial tensile strain is introduced in these samples to convert Ge into a (near-) direct-bandgap semiconductor and to red-shift its luminescence. A diffractive array of Ge pillars is used to outcouple the long-wavelength interband radiation, which is otherwise primarily emitted in the sample plane. An order-of-magnitude strain-induced enhancement in radiative efficiency is also reported, together with the observation of luminescence signatures associated with photonic-crystal cavity modes. These results are promising for the development of silicon-compatible lasers for mid-infrared optoelectronics applications.

  3. Spectral response of localized surface plasmon in resonance with mid-infrared light

    SciTech Connect

    Kusa, Fumiya; Ashihara, Satoshi

    2014-10-21

    We study spectral responses of localized surface plasmons (LSPs) in gold nanorods, which resonate at mid-infrared frequencies, by transmission spectroscopy and electromagnetic field analyses. The resonance linewidth is found to be linearly proportional to the resonance frequency, indicating that the dephasing due to Drude relaxation is suppressed and that the overall dephasing is dominated by radiative damping. Owing to the reduced radiative/non-radiative damping and large geometrical length of the nanorod, near-field intensity enhancement exceeds several hundred times. Nonetheless the resonance linewidth is comparable with or larger than the bandwidth of a 100-fs pulse, and therefore the enhanced near-field as short as 100-fs can be created upon pulsed excitation. The large enhancements with appropriate bandwidths make LSPs promising for enhanced nonlinear spectroscopies, coherent controls, and strong-field light-matter interactions in the mid-infrared range.

  4. Spectral reflectance of carbonate minerals and rocks in the visible and near infrared (0.35 - 2.55 microns) and its applications in carbonate petrology

    NASA Technical Reports Server (NTRS)

    Gaffey, S. J.

    1984-01-01

    Reflection spectroscopy in the visible and near infrared (0.35 to 2.55 micron) offers a rapid, inexpensive, nondestructive tool for determining the mineralogy and investigating the minor element chemistry of the hard-to-discriminate carbonate minerals, and can, in one step, provide information previously obtainable only by the combined application of two or more analytical techniques. When light interacts with a mineral certain wavelengths are preferentially absorbed. The number, positions, widths and relative intensities of these absorptions are diagnostic of the mineralogy and chemical composition of the sample. At least seven bands due to vibrations of the carbonate radical occur between 1.60 and 2.55 micron. Positions of these bands vary from one carbonae mineral to another and can be used for mineral identification. Cation mass is the primary factor controlling band position; cation radius plays a secondary role.

  5. Visible and near-infrared reflectance spectroscopy of planetary analog materials. Experimental facility at Laboratoire de Planetologie de Grenoble.

    NASA Astrophysics Data System (ADS)

    Pommerol, A.; Brissaud, O.; Schmitt, B.; Quirico, E.; Doute, S.

    2007-08-01

    We have developed an original experimental facility designed to measure the bidirectional reflectance spectra of planetary analog materials. These measurements are helpful to interpret the observations of the spectrometers on board space probes in orbit around various Solar System bodies. The central part of the facility is the LPG spectrogonio- radiometer (Brissaud et al., 2004). This instrument provides measurements of samples BRDF (Bidirectional Reflectance Distribution Function) with high photometric and spectrometric accuracy in the spectral range of visible and near-infrared (0.3 - 4.8 microns). Measurements can be made at any value of incidence and emergence angle up to 80°. Azimuth angle is allowed to vary between 0 and 180°. The instrument was recently installed in a cold room allowing ambient temperatures as low as -20°C. This makes possible the measurements on different kinds of water ice samples (slab ice, frost, snow...) and mixtures of minerals and water ice with unprecedented accuracy. We also have designed and built a simulation chamber to measure spectra of samples (water ice and/or minerals) under an atmosphere with perfectly controlled temperature, pressure and composition. The main objective of this last improvement is the study of water exchange between planetary regolith analogs and atmosphere (adsorption/ desorption, condensation/sublimation). Experimental results will mainly apply to Martian water cycle and hydrated mineralogy. This simulation chamber also provides an efficient way to obtain bidirectional reflectance spectra of dry materials (removal of adsorbed water) with implications for planetary bodies without atmospheric or surface water (Titan, asteroids...). The reflectance spectroscopy facility is part of a large panel of instruments and techniques available at Laboratoire de Planetologie de Grenoble that provide complementary measurements on the same samples: infrared transmission spectroscopy of thin ice films, thick liquid and

  6. Macroscopic Fourier transform infrared scanning in reflection mode (MA-rFTIR), a new tool for chemical imaging of cultural heritage artefacts in the mid-infrared range.

    PubMed

    Legrand, Stijn; Alfeld, Matthias; Vanmeert, Frederik; De Nolf, Wout; Janssens, Koen

    2014-05-21

    In this paper we demonstrate that by means of scanning reflection FTIR spectroscopy, it is possible to record highly specific distribution maps of organic and inorganic compounds from flat, macroscopic objects with cultural heritage value in a non-invasive manner. Our previous work involved the recording of macroscopic distributions of chemical elements or crystal phases from painted works of art based on respectively macroscopic X-ray fluorescence or X-ray powder diffraction analysis. The use of infrared radiation instead of X-rays has the advantage that more specific information about the nature and distribution of the chemical compounds present can be gathered. This higher imaging specificity represents a clear advantage for the characterization of painting and artist materials. It allows the distribution of metallo-organic compounds to be visualized and permits distinguishing between pigmented materials containing the same key metal. The prototype instrument allows the recording of hyperspectral datacubes by scanning the surface of the artefact in a contactless and sequential single-point measuring mode, while recording the spectrum of reflected infrared radiation. After the acquisition, spectral line intensities of individual bands and chemical distribution maps can be extracted from the datacube to identify the compounds present and/or to highlight their spatial distribution. Not only is information gained on the surface of the investigated artefacts, but also images of overpainted paint layers and, if present, the underdrawing may be revealed in this manner. A current major limitation is the long scanning times required to record these maps.

  7. Monitoring of environmental arsenic by cultures of the photosynthetic bacterial sensor illuminated with a near-infrared light emitting diode array.

    PubMed

    Maeda, Isamu; Sakurai, Hirokazu; Yoshida, Kazuyuki; Siddiki, Mohammad; Shimizu, Tokuo; Fukami, Motohiro; Ueda, Shunsaku

    2011-12-01

    Recombinant Rhodopseudomonas palustris, harboring the carotenoid-metabolizing gene crtI (CrtIBS), and whose color changes from greenish yellow to red in response to inorganic As(III), was cultured in transparent microplate wells illuminated with a light emitting diode (LED) array. The cells were seen to grow better under near-infrared light, when compared with cells illuminated with blue or green LEDs. The absorbance ratio of 525 to 425 nm after cultivation for 24 h, which reflects red carotenoid accumulation, increased with an increase in As(III) concentrations. The detection limit of cultures illuminated with near-infrared LED was 5 microgram/l, which was equivalent to that of cultures in test tubes illuminated with an incandescent lamp. A near-infrared LED array, in combination with a microplate, enabled the simultaneous handling of multiple cultures, including CrtIBS and a control strain, for normalization by the illumination of those with equal photon flux densities. Thus, the introduction of a near-infrared LED array to the assay is advantageous for the monitoring of arsenic in natural water samples that may contain a number of unknown factors and, therefore, need normalization of the reporter event.

  8. Metallic attenuated total reflection infrared hollow fibers for robust optical transmission systems

    SciTech Connect

    Jing, Chengbin; Guo, Hong; Hu, Zhigao; Yang, Pingxiong; Chu, Junhao; Liu, Aiyun; Shi, Yiwei

    2014-07-07

    A durable metallic attenuated total reflection (ATR) hollow fiber (bore size: 1.45 mm, wall thickness: 50 μm) was designed and fabricated based on a nickel capillary tube and hexagonal germanium dioxide (GeO{sub 2}). The anomalous dispersion of the hexagonal GeO{sub 2} layer grown inside a nickel tube achieves low-loss light transmission at two peak-power wavelengths for CO{sub 2} laser devices (10.2 and 10.6 μm). An 11–28 W, 10.2 or 10.6 μm CO{sub 2} laser power was steadily delivered via a fiber elastically bent from 0° to 90° (radius: 45 cm) for over 40 min (transmission loss: 0.22 to 4.2 dB/m). Theoretically fitting the measured temperatures showed that front-end clipping caused greater thermal loading than the distributed mode absorption. The maximum external temperature of a nickel ATR fiber is much lower than that of a silica glass ATR fiber owing to their different heat dissipation abilities. The HE{sub 11} mode purity of the output beam profiles decreased from 90.3% to 44.7% as the bending angle increased from 0° to 90°. Large core sizes and wall roughnesses (scattering loss 0.04 dB/m) contributed to mode mixing and excess losses that were above the value predicted by the classical Marcatili and Schmeltzer equation (0.024–0.037 dB/m).

  9. Hollow optical-fiber based infrared spectroscopy for measurement of blood glucose level by using multi-reflection prism.

    PubMed

    Kino, Saiko; Omori, Suguru; Katagiri, Takashi; Matsuura, Yuji

    2016-02-01

    A mid-infrared attenuated total reflection (ATR) spectroscopy system employing hollow optical fibers and a trapezoidal multi-reflection ATR prism has been developed to measure blood glucose levels. Using a multi-reflection prism brought about higher sensitivity, and the flat and wide contact surface of the prism resulted in higher measurement reproducibility. An analysis of in vivo measurements of human inner lip mucosa revealed clear signatures of glucose in the difference spectra between ones taken during the fasting state and ones taken after ingestion of glucose solutions. A calibration plot based on the absorption peak at 1155 cm(-1) that originates from the pyranose ring structure of glucose gave measurement errors less than 20%.

  10. Hollow optical-fiber based infrared spectroscopy for measurement of blood glucose level by using multi-reflection prism

    PubMed Central

    Kino, Saiko; Omori, Suguru; Katagiri, Takashi; Matsuura, Yuji

    2016-01-01

    A mid-infrared attenuated total reflection (ATR) spectroscopy system employing hollow optical fibers and a trapezoidal multi-reflection ATR prism has been developed to measure blood glucose levels. Using a multi-reflection prism brought about higher sensitivity, and the flat and wide contact surface of the prism resulted in higher measurement reproducibility. An analysis of in vivo measurements of human inner lip mucosa revealed clear signatures of glucose in the difference spectra between ones taken during the fasting state and ones taken after ingestion of glucose solutions. A calibration plot based on the absorption peak at 1155 cm−1 that originates from the pyranose ring structure of glucose gave measurement errors less than 20%. PMID:26977373

  11. Blood glucose measurement in vivo using hollow-fiber based, mid-infrared ATR probe with multi-reflection prism

    NASA Astrophysics Data System (ADS)

    Kino, Saiko; Omori, Suguru; Matsuura, Yuji

    2016-03-01

    An attenuated-total-reflection (ATR), mid-infrared spectroscopy system that consists of hollow optical fibers, a trapezoidal multi-reflection ATR prism, and a conventional FT-IR spectrometer has been developed to measure blood glucose levels. Owing to the low transmission loss and high flexibility of the hollow-optical fiber, the system can measure any sites of the human body where blood capillaries are close to the surface of mucosa, such as inner lips. Using a multi-reflection prism brought about higher sensitivity, and the flat and wide contact surface of the prism resulted in higher measurement reproducibility. The results of in-vivo measurement of human inner lips showed the feasibility of the proposed system, and the measurement errors were within 20%.

  12. Hollow optical-fiber based infrared spectroscopy for measurement of blood glucose level by using multi-reflection prism.

    PubMed

    Kino, Saiko; Omori, Suguru; Katagiri, Takashi; Matsuura, Yuji

    2016-02-01

    A mid-infrared attenuated total reflection (ATR) spectroscopy system employing hollow optical fibers and a trapezoidal multi-reflection ATR prism has been developed to measure blood glucose levels. Using a multi-reflection prism brought about higher sensitivity, and the flat and wide contact surface of the prism resulted in higher measurement reproducibility. An analysis of in vivo measurements of human inner lip mucosa revealed clear signatures of glucose in the difference spectra between ones taken during the fasting state and ones taken after ingestion of glucose solutions. A calibration plot based on the absorption peak at 1155 cm(-1) that originates from the pyranose ring structure of glucose gave measurement errors less than 20%. PMID:26977373

  13. Spectral and Imaging Observations of a White-light Solar Flare in the Mid-infrared

    NASA Astrophysics Data System (ADS)

    Penn, Matt; Krucker, Säm; Hudson, Hugh; Jhabvala, Murzy; Jennings, Don; Lunsford, Allen; Kaufmann, Pierre

    2016-03-01

    We report high-resolution observations at mid-infrared wavelengths of a minor solar flare, SOL2014-09-24T17:50 (C7.0), using Quantum Well Infrared Photodetector cameras at an auxiliary of the McMath-Pierce telescope. The flare emissions, the first simultaneous observations in two mid-infrared bands at 5.2 and 8.2 μ {{m}} with white-light and hard X-ray coverage, revealed impulsive time variability with increases on timescales of ˜4 s followed by exponential decay at ˜10 s in two bright regions separated by about 13\\prime\\prime . The brightest source is compact, unresolved spatially at the diffraction limit (1\\_\\_AMP\\_\\_farcs;72 at 5.2 μ {{m}}). We identify the IR sources as flare ribbons also seen in white-light emission at 6173 Å observed by SDO/HMI, with twin hard X-ray sources observed by Reuven Ramaty High Energy Solar Spectroscopic Imager, and with EUV sources (e.g., 94 Å) observed by SDO/AIA. The two infrared points have nearly the same flux density (fν, W m-2 Hz) and extrapolate to a level of about an order of magnitude below that observed in the visible band by HMI, but with a flux of more than two orders of magnitude above the free-free continuum from the hot (˜15 MK) coronal flare loop observed in the X-ray range. The observations suggest that the IR emission is optically thin; this constraint and others suggest major contributions from a density less than about 4× {10}13 cm-3. We tentatively interpret this emission mechanism as predominantly free-free emission in a highly ionized but cool and rather dense chromospheric region.

  14. Monte Carlo simulation of reflection spectra of random multilayer media strongly scattering and absorbing light

    SciTech Connect

    Meglinskii, I V

    2001-12-31

    The reflection spectra of a multilayer random medium - the human skin - strongly scattering and absorbing light are numerically simulated. The propagation of light in the medium and the absorption spectra are simulated by the stochastic Monte Carlo method, which combines schemes for calculations of real photon trajectories and the statistical weight method. The model takes into account the inhomogeneous spatial distribution of blood vessels, water, and melanin, the degree of blood oxygenation, and the hematocrit index. The attenuation of the incident radiation caused by reflection and refraction at Fresnel boundaries of layers inside the medium is also considered. The simulated reflection spectra are compared with the experimental reflection spectra of the human skin. It is shown that a set of parameters that was used to describe the optical properties of skin layers and their possible variations, despite being far from complete, is nevertheless sufficient for the simulation of the reflection spectra of the human skin and their quantitative analysis. (laser applications and other topics in quantum electronics)

  15. Tunable natural nano-arrays: controlling surface properties and light reflectance

    NASA Astrophysics Data System (ADS)

    Watson, Jolanta A.; Myhra, Sverre; Watson, Gregory S.

    2006-01-01

    The general principles of optical design based on the theories of reflection, refraction and diffraction have been rigorously developed and optimized over the last three centuries. Of increasing importance has been the ability to predict and devise new optical technologies designed for specific functions. A key design feature of many of today's optical materials is the control of reflection and light transmittance through the medium. A sudden transition or impedance mismatch from one optical medium to another can result in unwanted reflections from the surface plane. Modification of a surface by creation of a gradual change in refractive index over a significant portion of a wavelength range will result in a reduction in reflection. An alternative surface modification to the multi layered stack coating (gradient index coating) is to produce a surface with structures having a period and height shorter than the light wavelength. These structures act like a pseudo-gradient index coating and can be described by the effective medium theory. Bernhard and Miller some forty years ago were the first to observe such structures found on the surface of insects. These were found in the form of hexagonally close packed nanometre sized protrusions on the corneal surface of certain moths. In this study we report on similar structures which we have found on certain species of cicada wings demonstrating that the reflective/transmission properties of these natural nano-structures can be tuned by controlled removal of the structure height using Atomic Force Microscopy (AFM).

  16. Light propagation with phase discontinuities: generalized laws of reflection and refraction.

    PubMed

    Yu, Nanfang; Genevet, Patrice; Kats, Mikhail A; Aieta, Francesco; Tetienne, Jean-Philippe; Capasso, Federico; Gaburro, Zeno

    2011-10-21

    Conventional optical components rely on gradual phase shifts accumulated during light propagation to shape light beams. New degrees of freedom are attained by introducing abrupt phase changes over the scale of the wavelength. A two-dimensional array of optical resonators with spatially varying phase response and subwavelength separation can imprint such phase discontinuities on propagating light as it traverses the interface between two media. Anomalous reflection and refraction phenomena are observed in this regime in optically thin arrays of metallic antennas on silicon with a linear phase variation along the interface, which are in excellent agreement with generalized laws derived from Fermat's principle. Phase discontinuities provide great flexibility in the design of light beams, as illustrated by the generation of optical vortices through use of planar designer metallic interfaces. PMID:21885733

  17. Light Propagation with Phase Discontinuities: Generalized Laws of Reflection and Refraction

    NASA Astrophysics Data System (ADS)

    Yu, Nanfang; Genevet, Patrice; Kats, Mikhail A.; Aieta, Francesco; Tetienne, Jean-Philippe; Capasso, Federico; Gaburro, Zeno

    2011-10-01

    Conventional optical components rely on gradual phase shifts accumulated during light propagation to shape light beams. New degrees of freedom are attained by introducing abrupt phase changes over the scale of the wavelength. A two-dimensional array of optical resonators with spatially varying phase response and subwavelength separation can imprint such phase discontinuities on propagating light as it traverses the interface between two media. Anomalous reflection and refraction phenomena are observed in this regime in optically thin arrays of metallic antennas on silicon with a linear phase variation along the interface, which are in excellent agreement with generalized laws derived from Fermat’s principle. Phase discontinuities provide great flexibility in the design of light beams, as illustrated by the generation of optical vortices through use of planar designer metallic interfaces.

  18. Cloud shortwave radiative effect and cloud properties estimated from airborne measurements of transmitted and reflected light

    NASA Astrophysics Data System (ADS)

    LeBlanc, Samuel E.; Redemann, Jens; Segal-Rosenheimer, Michal; Kacenelenbogen, Meloë; Shinozuka, Yohei; Flynn, Connor; Russell, Philip; Schmid, Beat; Schmidt, K. Sebastian; Pilewskie, Peter; Song, Shi

    2015-04-01

    Surface cloud radiative effect, or the perturbation of sunlight by clouds, is often estimated by cloud properties retrieved from reflected sunlight, however transmission-based retrievals may lead to a more representative surface radiative effect than reflection-based counterparts. Transmitted light interacts with cloud particles throughout the vertical extent of the cloud, while reflected light, commonly used for satellite remote sensing of clouds, is more influenced by the top-most cloud particles. We showcase the difference in measurement-based estimates of cloud radiative effect at the surface when using transmitted light instead of reflected light for particular cases during recent field missions. Along with cloud radiative effect, we present the retrieved cloud properties based on light transmitted and reflected by clouds in the Gulf of Mexico, sampled during the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS), and in the Gulf of Maine, sampled during the Two-Column Aerosol Project (TCAP). To quantify cloud properties from transmitted shortwave radiation, a new retrieval utilizing spectrally resolved measurements is employed. Spectral features in shortwave radiation transmitted through clouds are sensitive to changes in cloud properties including cloud optical thickness, effective radius, and thermodynamic phase. The absorption and scattering of light by liquid water and ice clouds result in shifts in spectral slopes, curvatures, maxima, and minima of cloud-transmitted radiance. A new framework is introduced to quantify these spectral features that are observed in measured and modeled transmittance. This new framework consists of 15 parameters that are independent of spectrally neutral variations in radiometric calibration quantifying spectral slopes, derivatives, spectral curvature calculations, and ratios. These parameters are used to retrieve cloud properties from measurements of zenith radiance

  19. Reflectance and preparation of front-surface mirrors for use at various angles of incidence from the ultraviolet to the far infrared

    NASA Astrophysics Data System (ADS)

    Hass, G.

    1982-01-01

    Methods for measuring the reflectance of front-surface mirrors at various wavelengths and angles of incidence are discussed, and techniques for preparing reflecting films with maximum reflectance and durability are described. Data are presented on the UV, visible, and infrared reflectance of the most frequently used mirror coatings: Al, Ag, Au, and Rh. Single-layer and multilayer dielectric overcoatings are applied to increase durability and normal-incidence reflectance; the effect of these coatings on reflectance at higher angles of incidence is discussed. It is shown that, in the infrared from 8 to 12 microns, Al and Ag, overcoated with thin layers of silicon oxides or Al2O3, have almost the same high reflectance as the unprotected metal at close to normal incidence, but greatly decreased reflectance at angles larger than 40 deg. Since only the parallel component is responsible for the infrared reflectance decrease, such film combinations are suitable for producing highly efficient reflection polarizers for the infrared radiation. The determination of water absorption in dielectric overcoatings and its effect on the mirror reflectance at 3 microns (where water has the highest extinction coefficient) is discussed.

  20. Reflected Light Curves, Spherical and Bond Albedos of Jupiter- and Saturn-like Exoplanets

    NASA Astrophysics Data System (ADS)

    Dyudina, Ulyana; Zhang, Xi; Li, Liming; Kopparla, Pushkar; Ingersoll, Andrew P.; Dones, Luke; Verbiscer, Anne; Yung, Yuk L.

    2016-05-01

    Reflected light curves observed for exoplanets indicate that a few of them host bright clouds. We estimate how the light curve and total stellar heating of a planet depends on forward and backward scattering in the clouds based on Pioneer and Cassini spacecraft images of Jupiter and Saturn. We fit analytical functions to the local reflected brightnesses of Jupiter and Saturn depending on the planet’s phase. These observations cover broadbands at 0.59-0.72 and 0.39-0.5 μm, and narrowbands at 0.938 (atmospheric window), 0.889 (CH4 absorption band), and 0.24-0.28 μm. We simulate the images of the planets with a ray-tracing model, and disk-integrate them to produce the full-orbit light curves. For Jupiter, we also fit the modeled light curves to the observed full-disk brightness. We derive spherical albedos for Jupiter and Saturn, and for planets with Lambertian and Rayleigh-scattering atmospheres. Jupiter-like atmospheres can produce light curves that are a factor of two fainter at half-phase than the Lambertian planet, given the same geometric albedo at transit. The spherical albedo is typically lower than for a Lambertian planet by up to a factor of ˜1.5. The Lambertian assumption will underestimate the absorption of the stellar light and the equilibrium temperature of the planetary atmosphere. We also compare our light curves with the light curves of solid bodies: the moons Enceladus and Callisto. Their strong backscattering peak within a few degrees of opposition (secondary eclipse) can lead to an even stronger underestimate of the stellar heating. Division of Geological and Planetary Sciences, 150-21 California Institute of Technology, Pasadena, CA 91125 USA.