A response function expansion method for cooled IRFPA with multiple neutral density filters under a variable integration time

Infrared focal plane array (IRFPA) radiometric calibration is necessary to achieve infrared temperature measurements; however, the traditional method requires separate calibrations of the response functions for different integration times. In this study, based on the response model of a cooled IRFPA, the relationship between the response function (CRF), integration time, and transmittance was presented. The results demonstrated that the mean absolute percentage error (MAPE) of the expansion method with different neutral density filters under a variable integration time was 1.95 %. The MAPE of the expansion method with only changing the integration time was 1.27 %, and that with only changing the neutral density filters was 1.39 %. In addition, the CRF expansion method was applied to infrared temperature measurements, demonstrating that the relative error was less than ±1.5 % in the ambient temperature range and less than ±1 % in the higher temperature range.