Abstract: The thermal control system is one of the most important components of a large ground-based solar telescope, which can minimize the astronomical seeing effect of the primary mirror and the internal astronomical seeing effect. In a thermal control system, temperature sensors are the "eyes" that monitor the real temperatures of the primary mirror surface, heat-stop and the ambient air. Therefore, the accuracy of the temperature sensors have great effect on the performance of the thermal control system and even the whole telescope. In view of the low accuracy defect of most of the available temperature sensors, whose zero points and response curves vary with time, it is necessary to calibrate these sensors before being assembled into the telescope. In this paper, a precise calibration method of univariate linear regression for the temperature sensors of a large ground-based solar telescope has been adopted. The method can improve the accuracy of the sensor by correcting the response curve of the sensor. To validate the feasibility and effectiveness of the adopted method, an experimental setup has been built. The experimental results show that the measurement error of the tested temperature sensor is reduced from more than 1.5 oC to lower than 0.05 oC, which meets the requirement of the thermal control system of a large ground-based solar telescope.

Key words: adaptive optics, temperature sensor, calibration method, measurement accuracy, solar telescope, thermal control system