External field calibration method for low temperature section of infrared radiation measuring equipment

In the process of using infrared radiation measuring equipment, it is generally required to calibrate the linear response of the linear response range of the infrared focal plane detector. The calibration process generally calculates the grayscale output value of the device by measuring the standard blackbody radiation source with different known temperatures, and calculates the linear response of the device by the fitting method. In the actual calibration process of the external field, since the calibration temperature of the blackbody radiation source cannot be set lower than the ambient temperature, the equipment cannot perform measurement calibration on the black body below the ambient temperature, resulting in the lower limit of the linear response interval of the device cannot be confirmed, lower than the environment. The extrapolation calibration of the temperature may have a large error and the error cannot be evaluated. In this paper, a calibration method for low temperature section of external field equipment is proposed. The experiment proves that the method has high calibration accuracy.