LAUSR

Abstract A new directional polarized spectral emissivity measurement apparatus with the wavelength range of 4-20 μm was established to promote the development of thermal radiation transfer and polarization engineering. The measurement accuracy was improved by eliminating the background radiation with a high emissive thermostatic shutter and precisely determining the sample surface temperature. An accurate expression for directional polarized spectral emissivity was obtained taking into account the multiple reflection between the sample and the chamber. The linearity of spectral response was calibrated respectively in parallel and perpendicular polarized directions. The directional polarized spectral emissivity of a high-purity SiC sample was measured in a controlled environment to validate the capability of the apparatus. The excellent agreement between the measurement result and the literature data proved the reliability of the experiment apparatus and the measurement method. The measurement uncertainty was evaluated for each experiment, and the relative uncertainty was estimated to be less than 4.1%.