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.
Because there is no practical method to validate the precision of atmospheric transmittance for earth based infrared optical system measuring flying aircraft, this paper applies multiple linear regression to analyze the measured meteorological parameters and atmospheric transmittance, and points out that: 1) the effects of air pressure and visibility on atmospheric transmittance are contrary with physical laws; 2) among all the meteorological parameters, the angle of elevation has the greatest impact on atmospheric transmittance. By comparing with practical result of the experiment, it is found there is big difference. At last, conclusion is drawn that the accuracy of atmospheric transmittance provided by one infrared optical system is not high.