Blackbody simulator calibration method: determining temperature corrections based on thermal imaging measurements and calculated flow conversion rates

The issues of calibration and performance verification of the planned scientific equipment for the “Sun-Terahertz” space experiment are considered. A blackbody simulator has been developed for ground tests of this scientific equipment. The method of calibration in ground conditions of a blackbody simulator is given. The results of calibrations of the blackbody simulator in ground conditions are necessary to assess the signal level of scientific equipment receivers when measuring radiation fluxes from the Sun during an experiment in low-Earth orbit aboard the International Space Station. Ground tests and testing of the proposed methodology were carried out using a single-channel mock-up of scientific equipment. The blackbody simulator allows you to direct the radiation stream into the telescopes of scientific equipment at various set temperatures of the radiator. A thermal imager based on the MLX90640 infrared camera was used to control the brightness temperature of the blackbody simulator. The proposed technique makes it possible to evaluate factors affecting the operation of scientific equipment, such as the temperature gradient between the surface of the parabolic mirror of the blackbody simulator emitter and the installation point of the thermocouple, the temperature gradient from the center to the edge of the emitting surface of the blackbody simulator and the divergence of the blackbody simulator radiation beam. The spectral transmission coefficient of the air environment in the optical path is also calculated, from the radiator of the blackbody simulator to the entrance window of the receiver of scientific equipment. Based on the results of the experimental verification, conclusions were drawn about the actual radiation fluxes entering the receivers of scientific equipment from a blackbody simulator during calibrations, depending on the temperature set on the meter controller. The results obtained can be used by experimenters involved in thermophysical measurements, spectrometric scientific instruments based on optoacoustic transducers (Golay cell) and other sensitive elements.