Correction about rear of aperture serves as sphere wall in effective area method

To eliminate the non-uniformity response of integrating sphere detector, which is brought by the back surface of the measured main aperture of the solar irradiance absolute radiometer serving as a part of the integrating sphere wall in effective area method, a correction optical model is designed to tackle the issue in TracePro program. By simulations, the radiant flux responded by the integrating sphere detector is given. Then the curve of the relative change about the radiant flux is deduced and the experiment measurement data are corrected on the basis of relative change curve. Eventually, the uncorrected and the corrected main aperture areas are calculated. Within a series of repeated measurements, the relative uncertainties of the uncorrected results and the corrected results are both 7 × 10−5 (n = 7). The relative uncertainty of the differences between the raw results and corrected results is 9.65 × 10−5 which proves that the optical model can evaluate the deviation, efficiently.