STP759: Wavelength and Temperature Dependence of the Absolute Reflectance of Metals at Visible and Infrared Wavelengths

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

    Hodgkin, VA
    Michelson Laboratory, Physics Division, Naval Weapons Center, China Lake, California

    Pages: 11    Published: Oct 1981


    Abstract

    This paper presents the wavelength dependence of Ag, Cu, and Al from 4000 Å to 10 μm wavelength. An intercomparison of data is made for surfaces prepared with a variety of techniques, including vacuum evaporation and diamond single-point machining. Briefly described, also, are experimental techniques and apparatus developed at the Naval Weapons Center for measuring temperature-dependent changes in the near-normal incidence reflectance of a sample to a precision of a few parts in 105. Reflectance results obtained from this instrument are presented for films and bulk material over the same wavelength range as above at temperatures from 270 to 450 K. The sample and reference surfaces were protected in ultrahigh vacuum for these measurements.

    A theoretical interpretation of results is presented, including both inter- and intraband electron transition effects, as well as extrinsic surface roughness effects. Of much practical interest for laser mirror applications, especially for pulsed mode operation, is the behavior of many metals upon temperature cycling, including hysteresis and time-dependent “annealing” behavior. Similar effects are also observed in both transport and thermal properties and are generally described under the name “premelting effects.”

    The data presented in this paper are of immediate engineering value in computing the performance of optical systems whose components necessarily operate at temperatures other than room temperature. It is also hoped that it will stimulate theoretical interest in examining some of the subtle and poorly understood dispersion effects such as those seen in the near-infrared in silver.

    Keywords:

    Aluminum, copper, Drude theory, infrared, reflectance, silver, surface roughness, temperature dependence


    Paper ID: STP37009S

    Committee/Subcommittee: F01.02

    DOI: 10.1520/STP37009S


    CrossRef ASTM International is a member of CrossRef.