STP689

    Lattice Absorption, Phonon Assignments, and Image Spoiling Properties of Cvd ZnS in the Infrared

    Published: Jan 1979


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    Abstract

    Chemical-vapor-deposited zinc sulfide (CVD ZnS) has been established as a highly promising material for advanced infrared imaging applications and is attracting attention as a potential window material at HF/DF laser wavelengths. The present contribution concerns work that has been carried out in the context of assessing the optical characteristics of CVD-ZnS blanks, particularly with regard to: (a) lattice absorption. Careful examination of transmission traces at wavelengths up to 25µm indicates that multiphonon processes dominate at frequencies below 1000 cm-1; peak-absorption assignments in terms of zone-boundary phonons have been made on the basis of best available inelastic neutron-scattering results for zincblende ZnS. (b) Temperature dependence. Absorption coefficients at temperatures up to 600K have been investigated in light of spectral transmittance and emittance measurements supplemented by calorimetric data at HF, DF, CO, and CO2-laser wavelengths. (c) Image spoiling. Line-spread functions in conjunction with index-inhomogeneity maps demonstrate that wavefront distortions resulting from the presence of a CVD-ZnS window do not inject any detectable degradation in contrast transmittance.

    Keywords:

    Characteristic phonons, chemical-vapor deposition, image spoiling, infrared imaging, lattice absorption, zinc sulfide


    Author Information:

    Klein, C
    Raytheon Company, Waltham, Massachusetts

    diBenedetto, B
    Raytheon Company, Waltham, Massachusetts

    Donadio, R
    Raytheon Company, Waltham, Massachusetts

    Kohane, T
    Raytheon Company, Waltham, Massachusetts

    Pappis, J
    Raytheon Company, Waltham, Massachusetts


    Paper ID: STP39109S

    Committee/Subcommittee: F01.02

    DOI: 10.1520/STP39109S


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