Sensitivity Investigation and Optimization for Solar Irradiance Absolute Radiometer

Abstract

Since the calibration accuracy decreases with the reduction of irradiance power, the nonlinearity of sensitivity is experimentally investigated and corrected in order to improve the precision of calibration for Solar Irradiance Absolute Radiometer (SIAR). The optimization method is proposed based on the interpolation approximation principle. The real-time correction sensitivities are repeatedly measured at each radiant power. The relative system error of sensitivity nonlinearity is 2.2%. The impact of sensitivity nonlinearity is analyzed. The radiant powers are measured by the optimization method and the traditional method. The comparison experiment results illustrate that the optimization method improves the measure accuracy to 0.1%. The sensitivity nonlinearity is compensated by the real-time correction. Thus, the optimization method significantly improves the calibration precision of ground-based comparison experiment. The investigation of sensitivity nonlinearity also provides the theoretical and experimental basis for optimizing the on-orbit calibration precision of Total Solar Irradiance Monitor (TSIM).