Abstract
In the wide band radiation thermometry, variation of spectral emissivity in an observation band causes systematic error in measured temperature. Usually, we measure reflectance, derive emissivity from the reflectance and estimate object temperature by solving radiation equation. In these procedures, we assume that the reflectance and the emissivity do not depend on object temperature and that sum of them is unity. However, the variation of spectral emissivity yields temperature dependency of emissivity and reflectance.
In this paper, we propose a method for obtaining object temperature without the error. In this method, we use a variable temperature radiator. Reflectances (we call them differential refrectance) measured at various temperatures using the radiator are transformed to (interval) emissivities at the same temperature, respectively. By solving radiation equation with interpolation of the neighboring emissivities, we get object temperature with high accuracy. Here, we describe the principle and the procedures of the proposed method. The validity of the method is confirmed by a numerical simulation.
