Effect of multilayer anti-reflective coating on spectral emissivity of area blackbody

Abstract

An area blackbody is used as a standard radiant source for calibrating equipment of non-contact infrared temperature measurement. Tailoring the spectral emissivity of area blackbody is important for improving the accuracy of a temperature measurement system. In this work, a new antireflective coating (ARC) has been proposed and the first association it with area blackbody has been made to improve the emission in the 3–14 μm wavelength range. We have compared the single, dual and triple-layer of different ARC materials with a different combination. In each category, we have optimized the SiO2, Al2O3 and Si3N4 thin films layer stack as ARC coating and then compared radiation property of area blackbody covered by ARC. Numerical simulations of the spectral emissivity of the combination reveals that double-layer ARC is taken as the most excellent stack structure, which can realize spectral emissivity exceeding 0.9 with least material in the wavelength range from 3 to 13 μm. Physical mechanisms responsible for the increasing emissivity are elucidated as due to producing the gradual variation of the refractive index and the selection of each layer material directly affects emission performance. Considering excellent radiation property of area blackbody combined with ARC, this study can help pave the way for designing ideal area blackbody.