Research on the methodology and instrument of traceable measurement of surface temperature based on an “ideal plane” model

Abstract

Because the emissivity of a measured sample is difficult to determine in an in situ measurement and the emissivity of a pyrometer is different in the in situ measurement and calibration, the measurement results of the pyrometer are not traceable to a standard—The International Temperature Scale of 1990. To solve this problem, an ideal plane is proposed in this paper. The measured sample and the thermocouple are in a vacuum blackbody, and a gold-plated reflector is in contact with the measured sample. The surface can emit blackbody radiation during the measurement. The emissivity of the measured surface is always the same as that during calibration, so the uncertainty of emissivity is eliminated. In addition, the temperature of the measured sample is the same as that of the thermocouple in the vacuum blackbody; in doing so, the temperature differences between them are eliminated, and the uncertainty of the traceable measurement of the measured surface is greatly reduced. The instrument has been developed and tested. The results show that the average difference of traceable measurements in the range of 600–900 °C is 2.29 °C, while the uncertainty is 0.52 °C.