Research on the New Technology of Calibrations of Spectroradiometer for Ultraviolet Space Borne Remote Sensing Based on Integrating Sphere

In the ultraviolet wavelength range,the high precision radiometric calibration of spectroradiometer is quite difficult.It is mainly caused by the relatively larger uncertainty(4%) in the irradiance calibration of FEL standard lamp and uncertainty(4%—6%) in the measurements of the diffuser bidirectional reflectance distribution function(BRDF).In this article,the calibration technique of sphere integrator is used to improve the precision of calibration,the large area uniform(~2%) source of radiance close to the ideal one is achieved to acquire the radiance responsivities of the spectroradiometer under development for ultraviolet remote sensing from space.The FEL standard lamp is assumed to be a uniform point source to get a correction for the illuminating factor.In the mean time,a comparison between the conventional FEL+diffuser method and the new sphere integrator method is performed.A conclusion is drawn that the radiance responsivities using these two techniques are consistent within 3%.A preliminary analysis of calibration data points out that the uncertainties in measurements of the diffuser BRDF and the calculation of the radiance in the FOV of spectroradiometer account for the discrepancy between the comparisons of these two techniques.