This approach of the spectral emissivity determination is the development at the new method on radiation thermometry without black body [1]. In this paper we consider an application of directional relative reflectometry, which in this method completely excludes the influence of the radiation surface character. That means that this reflectometry method does not subordinate to Lambert's law. With measuring the coefficients of the directional relative reflection in discussed method the simultaneous measurements the intensity of two spectral components of the own radiation are measuring. By measuring of the ratio of reflection coefficients on each wavelength (λ_(1),λ_(2)) for each pair of the unknown temperatures (T_(1),T_(2)), (T_(2),T_(3)) and involution with (λ_(1),λ_(2)) the ratio of the spectral emissivities of the own radiation with the same wavelengths and the same temperatures we come to six equations with six unknown meanings of the emissivities. The solution of the equations gives the estimations of spectral emissivities. The lack of current information on the emissivity of various materials is a crucial problem for radiation thermometry based on the Planck law. This law holds for a black body and is used for calibrating any pyrometer (i.e., for determining its spread function). However, it turns out that the effect of emissivity and the spread function can be eliminated by the use of redundant information on temperatures and the number of spectral components of thermal radiation, which are used for measuring the radiation intensities. Thus, pyrometer calibration against a black body also becomes unnecessary.
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