Radiometric calibration of large dynamic range low light level camera

The low light level camera (LLLC) can acquire images of Visible/Near Infrared (VIS/NIR) targets in large dynamic range which are from daylight to starlight conditions. Accurate radiometric calibration for the LLLC was a key part of determining the performance of the camera, and it's very important to the quantitive application of images. The output radiance of the uniform light source which is used to calibrate the LLLC should be in the range from 110-9 W/(cm2sr) to 310-2 W/(cm2sr). For realizing high-precision radiometric calibration, a uniform light source which had constant spectrum in each output level was designed. A three-integrating-sphere transfer design was adopted and the difficulty of constant spectrum for each output level of the light source over multiple orders of magnitude was overcame. The design of the uniform low light level source for radiometric calibration was introduced. Furthermore, the accuracy of spectral radiance measurement for such a large dynamic range light source was also a challenge. The spectral radiance of each output level of the light source was obtained by transfer measuring method. The result of radiometric calibration for large dynamic range LLLC was given. The uncertainty of radiometric calibration for the LLLC achieved 18% (k=2).