Experimental apparatus for radiometric emissivity measurements of metals

An apparatus of the radiometric emissivity measurement of a metal has been developed. The apparatus possesses some features that it can keep a metallic sample under specific conditions such as vacuum, oxidizing, and deoxidizing atmosphere. Using the apparatus, spectral (from visible to 10 μm infrared wavelengths), directional (normal and 80°), and polarized emissivities (p and s polarized) of metals can be measured and can be utilized to investigate the behavior of the emissivity of the specimen. In this article, the concrete design of the apparatus is described and some examples of measurements of emissivities under some specific conditions are introduced. The peculiar behaviors of the emissivity of a metal in the early stage when the oxide film is grown on its surface are discussed.