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Junji Nishii - One of the best experts on this subject based on the ideXlab platform.

  • Design and fabrication of an achromatic Infrared Wave plate with Sb–Ge–Sn–S system chalcogenide glass
    Applied optics, 2013
    Co-Authors: Itsunari Yamada, Naoto Yamashita, Toshihiko Einishi, Mitsunori Saito, K. Fukumi, Junji Nishii
    Abstract:

    We designed and fabricated an achromatic Infrared Wave plate. To examine its phase retardation characteristics, the birefringence was calculated using the effective medium theory. A Wave plate with a subWavelength grating was fabricated by direct imprint lithography on a low toxic chalcogenide glass (Sb–Ge–Sn–S system) based on calculated results. As a result of imprinting onto chalcogenide glass by a glassy carbon mold, a grating with 1.63 μm depth, a fill factor of 0.7, and a 3 μm period was obtained. The phase retardation of the elements reached around 30° in the 8.5–10.5 μm Wavelength range. The fabrication of the Infrared Wave plate is less costly compared with conventional crystalline Wave plates.

  • Fabrication of Achromatic Infrared Wave Plate by Direct Imprinting Process on Chalcogenide Glass
    Applied Physics Express, 2012
    Co-Authors: Itsunari Yamada, Naoto Yamashita, Kunihiko Tani, Toshihiko Einishi, Mitsunori Saito, K. Fukumi, Junji Nishii
    Abstract:

    An achromatic Infrared Wave plate was fabricated by forming a subWavelength grating on the chalcogenide glass using direct imprint lithography. A low toxic chalcogenide glass (Sb?Ge?Sn?S system) substrate was imprinted with a grating of 1.63-?m depth, a fill factor of 0.7, and 3-?m period using glassy carbon as a mold at 253 ?C and 3.8 MPa. Phase retardation of the element reached around 30? at 8.5?10.5 ?m Wavelengths, and the transmittance exceeded that of a flat substrate over 8 ?m Wavelength. Fabrication of the mid-Infrared Wave plate is thereby less expensive than that of conventional crystalline Wave plates.

Masaaki Ashida - One of the best experts on this subject based on the ideXlab platform.

Yuan Zhang - One of the best experts on this subject based on the ideXlab platform.

  • Study on reflection of human skin with liquid paraffin as the penetration enhancer by spectroscopy.
    Journal of biomedical optics, 2013
    Co-Authors: Kun Chen, Yanmei Liang, Yuan Zhang
    Abstract:

    Optical clearing agents can improve tissue optical transmittance by reducing the diffuse reflection. The reflection on in vivo human skin before and after applying anhydrous glycerol and 30 to 50% liquid paraffin glycerol mixed solution are investigated in this paper. From their visible and near-Infrared reflection spectroscopy, all of their diffuse reflections are reduced after applying the agents. It is found that the three mixed solutions show stronger effect than that of anhydrous glycerol. These results further prove liquid paraffin can enhance the percutaneous penetration of glycerol and take synergistically optical clearing effect with glycerol over visible and near-Infrared Wave bands.

Masaaki Nagatsu - One of the best experts on this subject based on the ideXlab platform.

  • broadband Infrared quarter Wave plate realized through perpendicular to helical axis Wave propagation in a helix array
    Optics Letters, 2013
    Co-Authors: A Balmakou, I V Semchenko, Masaaki Nagatsu
    Abstract:

    The ability of helix arrays to filter circularly polarized light efficiently when the light propagates parallel to the helical axis has been demonstrated recently. In this Letter, we present a broadband linear-to-circular polarization transformer composed of metal microhelices. The device provides significant transformation performance combined with high transmittance over a broad Infrared Wave band. High performance is achieved through fine adjustment of a finite-element electromagnetic model. The array design assumes Wave propagation perpendicular to the helical axis, which distinguishes it from well-studied analogous designs that filter light propagating parallel to the helical axis. To the best of our knowledge, this is the first time this scheme has been realized in the Infrared range.

Odile Hembise - One of the best experts on this subject based on the ideXlab platform.

  • Estimation of light penetration, and horizontal and vertical visibility in oceanic and coastal waters from surface reflectance
    Journal of Geophysical Research: Oceans, 2007
    Co-Authors: Maeva Doron, Mathieu Babin, Antoine Mangin, Odile Hembise
    Abstract:

    1 We present algorithms for the estimation of the vertical diffuse attenuation coefficient, K-d (m(-1)), and the beam attenuation coefficient, c (m(-1)), at 490 nm from irradiance reflectance. Our aim is to retrieve as analytically as possible K-d(490) + c(490)(-1), a proxy for vertical visibility. The two algorithms are based on the semianalytical retrieval of the absorption coefficient a (m(-1)) and the backscattering coefficient b(b) (m(-1)) from reflectance at two Wavelengths, 490 and 709 nm. The use of a near-Infrared Wave band allows a small number of simple assumptions to be made, (1) light absorption at 709 nm is only due to pure seawater, and (2) there exists a constant ratio between the particulate backscattering coefficients at 490 and 709 nm. To estimate c(490), we developed an empirical relationship between b and b(b) for particles. Algorithm development, testing, and validation are achieved using data from the literature, a synthetic data set, and a large in situ data set of inherent and apparent optical properties measured in various environments. The algorithms are found to be valid both in coastal and oceanic waters, and largely insensitive to regional peculiarities in the inherent optical properties. The values of K-d( 490) and c( 490) are retrieved within a factor of 2.21 and 2.91 (95% confidence interval), respectively, using independent in situ data sets. This performance for K-d( 490) is better or comparable to that of recently published algorithms. This study opens the way to the development of simple semianalytical ocean color algorithms that make the best use of spectral information.