Research on the Temperature Transfer Relationship between Miniature Fixed-Point and Blackbody for On-Orbit Infrared Remote Sensor Calibration

Miniature fixed-point blackbody (MFPB) can realize the on-orbit calibration of temperatures by tracing the miniature fixed-point. This ability can effectively improve the precision and life span of earth observation systems. Researchers have verified the feasibility of the MFPB in engineering through experiments. However, the temperature relationship between the miniature fixed-point and the blackbody is unclear at present, which means that the transfer relationship between radiation temperature of space infrared radiation standard source and international temperature scale cannot be established accurately. In this article, a temperature transfer relationship between miniature fixed-point and blackbody in MFPB is established, and the temperature transfer equation (TTE) is proposed to obtain the run-off point temperature of blackbody (RPTB). The effects of heating power and ambient temperature on the temperature transfer relationship between miniature fixed-point and blackbody are investigated numerically. Retrieval results show that a linear relationship exists between the RPTB and the heating power and ambient temperature in a single fixed-point temperature range. The TTE is obtained and explained theoretically. All experimental results of the gallium fixed-point are in good agreement with this equation. Furthermore, the RPTBs are accurately predicted at gallium-stannum and H2O fixed-points by TTE. The average and maximum errors are 0.0044 and 0.0063 K, respectively. The current study is of considerable importance to the development of MFPB technology and improvement of the on-orbit infrared remote sensor calibration.