Radiometric calibration system for IR cameras

This paper describes an automated calibration system that we developed to calibrate JR flight cameras for a series of sub-orbital experiments. Short schedules as well as concern over cryo-cooler lifetimes dictated a totally automated calibration system that obtained as much data as possible over a short period of time. The data must be as complete as possible since the cameras are not recovered. For this reason the system calibrates each pixel individually. The output of the calibration is a set of calibration coefficients which convert the gray level output of the camera into physical units of radiance (Watts/cm2-str-.tm). We have calibrated Hughes 256x256 pixels PtSi cameras and 128x128 pixels HgCd cameras and Amber 128x128 pixels JnSb cameras. These cameras put out 8 bit digital data and sync signal at a given camera setting. This paper describes the calibration acquisition system and shows the results for the Hughes 256x256 PtSi camera.