Laboratory radiometric calibration of the channeled interference imaging spectropolarimeter

The radiometric calibration is the prerequisite and guarantee for realizing quantitative detection of the spectral characteristics for the channeled interference imaging spectropolarimeter (CIISP). A complete set of experimental scheme and processing algorithm of the lab radiometric calibration for CIISP were detailed presented. In relative radiometric calibration, the dark current noise of the CIISP was eliminated firstly, and then the uniformity correction was implemented according to the characteristics of the output interferogram formed by CIISP. The response uniformity of pixels in CCD detector was efficiently improved, as well as the vignetting effects of the instrument. By the absolute radiometric calibration, the spectral responsivity was corrected at each wavelength, and the functional relation between the standard spectral radiance and the dimensionless reconstructed spectral data was established. As a result, the maximum root-mean-square error of the calibrated spectrum was approximate 1.88% within the wavebands which have a normal signal-to-noise ratio. The study provides us a quite efficient and high-precision calibration method that is well applicable to other detection modes of the CIISP.