Determination of true temperature of opaque matter based on its thermal radiation spectrum: Using relative emissivity and the Wien displacement law

Abstract

Two methods for determining of the true (thermodynamic) temperature via thermal radiation spectrum of an opaque heated object are presented. The first method is based on the relative emissivity. It is shown that in many cases, the range of the true temperature values may be narrowed down using the “convex-concave” criterion. As shown, that any relative spectral emissivity dependence can be approximated by the same parametric model. The second method is based on the use of the Wien displacement law for real materials. This method is effective when the radiation of the object close to the gray-body radiation in the region of the spectral emission maximum. It is shown that these two methods complement each other.