Radiometric calibration of low light imager based on specialized light sources

Abstract

Due to the advances in the low light imagers and high quality of the related night time data products, some related applications such as fishery activities, fog detection, gravity wave and internal solitary wave parameters retrieval, armed conflicts and disasters have been greatly promoted. However, the indirect radiometric calibration at night brings some uncertainties. Thus, the directly radiometric calibration of low light imagers is urgent and important to produce high quality data products. As the relatively stable light emissions may also be obtained by the low-level light imager at night, the calibration method of low-level light imager based on self-design light source are provided. a low-light calibration light source based on the integrating sphere which has good radiance uniformity and stable emission radiation was designed and developed to further improve the calibration accuracy. Based on the test and analysis of its radiative characteristics in the laboratory, the low-light calibration experiment based on the integrated sphere light source is performed in the Dunhuang site. The results show that the observations are consistence with the simulations, which means that the self-design light source is a good way to calibrate the low light imager. As the new generation of space borne low light sensors own higher spatial resolution and multispectral camera covering the range from blue to NIR, some calibration problems of the further low light sensors are also discussed.