STP689

    Measured Thin Film Absorption at the Air-Film Interface, the Film Bulk, and the Film-Substrate Interface

    Published: Jan 1979


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    Abstract

    A measurement technique is described where the absorption introduced by the addition of a single-layer thin film is separated into three parts: absorption (a) within the bulk of the film; (b) at the air-film interface; and (c) at the film-substrate interface. The technique employs a scanning adiabatic calorimeter to measure substrates which are partially coated on the entrance surface with films of continuously varying thickness. By measuring the absorption on the bare substrate and at various film thicknesses, we have unambiguously determined the film-bulk absorption coefficient. We have also measured the combined absorption due to the two film interfaces. It will be shown that, in some cases, it is possible to distinguish between air-film interface absorption and film-substrate interface absorption and determine the magnitude of each. Data will be presented for 2.9 and 2.7 µm for films made of NaF and As2Se3 on CaF2 These films show the presence of impurities in the film and/or at the film interfaces. The relative magnitude of absorption in the three regions will be discussed.

    Keywords:

    Absorption coefficient, adiabatic calorimetry, As, 2, Se, 3, interface absorption, laser calorimetry, NaF, thin film absorption, water absorption, wedged film


    Author Information:

    Temple, PA
    Michelson Laboratory, Physics Division Naval Weapons Center, China Lake, CA

    Decker, DL
    Michelson Laboratory, Physics Division Naval Weapons Center, China Lake, CA

    Donovan, TM
    Michelson Laboratory, Physics Division Naval Weapons Center, China Lake, CA

    Bethke, JW
    Michelson Laboratory, Physics Division Naval Weapons Center, China Lake, CA


    Paper ID: STP39101S

    Committee/Subcommittee: F01.02

    DOI: 10.1520/STP39101S


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