AN OPTICAL METHOD FOR CORRECTING THE EMISSIVITY OF BLACKBODY MODELS

Modern infrared thermometers are designed to measure the temperature of objects with an emissivity from 0.1 to 1.0. However, when approving the type, checking or calibrating infrared thermometers, metrological characteristics are determined only when the emissivity is close to one. It is impossible to perform objective control at other emissivity values due to the lack of necessary standards. The paper describes an optical method for correcting the emissivity of black body models. The method is based on the use of the properties of reflection and refraction of light at homogeneous flat interfaces of media. Viewing windows made of optical glass of the KI brand, calcium fluoride of the FC-I brand and potassium bromide are used as media separators. The possibility of reducing the emissivity of a black body to ≈ (0.5…0.6) is theoretically justified and experimentally confirmed. The additional temperature reproduction error, depending on the temperature and the material of the viewing windows, does not exceed 2.0…4.7 °C. The optical method of emissivity correction can be used to: improve reference models of a black body; calibrate infrared thermometers with an established emissivity of less than 0.99; verify algorithms for accounting for the emissivity of an object implemented in verifiable pyrometers.