On surface temperature measurement of low emittance artefact coating by active infrared laser radiation thermometry

Accurate measurement of the material surface temperature plays a vital role in many scientific and technological advances. With the application of the active infrared laser radiation thermometry, the surface temperature can be obtained independently of the target emissivity. This method has been developed gradually, but there is still lacking of the experimental result about low emissivity surfaces, and the determination of the system core parameter has not been sufficiently discussed. Therefore, a new active infrared laser radiation thermometry system is reported in this paper. The temperature change radiance signals emitted from the target surface at the same frequency as the heating laser are accurately screened and collected by using a lock-in amplifier, and the calibration method of the instrument constant is discussed. The experimental results show that, for high emissivity sample, in the range of 873-1173 K, the relative deviation between the temperature measurement results of the experimental device and the reference value is within 0.5%. For the low emissivity sample, also in the range of 873-1173 K the relative deviation between the measurement results of the experimental device and the reference temperature is within 0.8%, and the average absolute deviation is 3.3 K. The measurement accuracy is improved and compared with previous literature.