Correcting for focal-plane-array temperature dependence in microbolometer infrared cameras lacking thermal stabilization

Abstract

Advances in microbolometer detectors have led to the development of infrared cameras that operate without active temperature stabilization. The response of these cameras varies with the temperature of the camera's focal plane array (FPA). This paper describes a method for stabilizing the camera's response through software processing. This stabilization is based on the difference between the camera's response at a measured temperature and at a reference temperature. This paper presents the mathematical basis for such a correction and demonstrates the resulting accuracy when applied to a commercially available longwave infrared camera. The stabilized camera was then radiometrically calibrated so that the digital response from the camera could be related to the radiance or temperature of objects in the scene. For FPA temperature deviations within AE7.2C changing by 0.5C min, this method produced a camera calibration with spatial-temporal rms variability of 0.21C, yielding a total calibration uncertainty of 0.38C limited primarily by the 0.32C uncertainty in the blackbody source emissivity and temperature.