Article presents the result of work on the development of the separately internal and external ceramics erosion measurement method. The tests results of the developed optical receiver are presented. Spectrum of SPT-70 with the wavelength range 240-850 nm is demonstrated. Qualitative analysis results are presented. A conclusion about spectrum element composition was made on the base on accepted spectrum data. In the result of optical sensitivity calibration before and after the experiment it was shown that optical receiver should be equipped with the protective elements.