Abstract: Solar irradiance is measured while the sun scans over the FOV(field-of-view) of the WFOV(wide-field-of-view)absolute radiometer. The result contributed by the stray light entered into the receiving cone has an effect on the measurement precision. There are three aspects

the model analysis

outfield measurement of FY-3 and correction for orbit data of SZ-3

were analyzed to make the distribution of stray light with the change of incident angle of sun light. 1) The effect of stray light increases with the incident angle in a liner way. 2) The slope angle of FY-3 is about 18.4 degree. The analyze result reaches 0.63% in an incident angle of 7 degree and the result of measurement from ground is about 0.79%. 3) The slope angle of SZ-3 is about 10.4 degree. It’s smaller than that of FY-3 and uses more baffles. So the effect of stray light is very little. The correction for the orbit data of SZ-3 with the result of SZ-3 analyze obviously reduces the system error.