Method to remove the effect of ambient temperature on radiometric calibration.

High precision radiometric calibration is essential for infrared imaging systems, especially in scientific applications where an accurate quantitative analysis is required. Nevertheless, calibration and radiometry are usually not simultaneously performed. Hence the discrepancy of ambient temperature between calibration and actual measurement can generate significant measurement errors unless the calibration results have been properly corrected. To overcome the restriction, we studied the effect of ambient temperature on radiometric calibration, then derived the relationship between calibration results and ambient temperature considering the integration time. A novel method compensating for the impact of ambient temperature on the calibration of a cooled infrared system is proposed. Several experiments are performed, and the results indicate that the proposed method can not only ensure the accuracy of calibration but achieve calibration results under any ambient temperature and arbitrary integration time.