太阳漫反射板反射率衰减监测仪(后简称比辐射计,SDRDM)被用来监测漫反射板反射率的变化。其太阳观测端口的透过率和太阳漫射板的相对双向反射分布函数(BRDF)是随角度变化的变量,因此比辐射计观测信号会受到入射光线角度的影响,该影响因子被叫作比辐射计角度因子(简称角度因子)。提出一种使用星上数据计算角度因子的方法,该方法被使用的前提是太阳漫射板在轨前期不发生衰退。采用相同太阳角度比值计算,在不使用比辐射计角度因子的前提下验证了太阳漫反射板在轨前期的稳定性。随后计算SDRDM的角度因子,并与实验室测量结果进行比对。结果显示星上计算值与实验室测量值偏差小于0.5%,发射前测量的角度因子可以用于计算太阳漫反射板的退化因子。

Solar diffuser reflectance degradation monitor (SDRDM) is used to gain the reflectance of a solar diffuser (SD). The transmittance of the sun view port and the relative bidirectional reflectance distribution function (BRDF) of the solar diffuser vary with the angle. Therefore, the SDRDM observation signals are affected by the angle of the incident light. The effect factor is called the SDRDM angle factor (abbreviated as the angle factor). This study proposes a method for calculating the SDRDM angle factor using on-board data employed on the premise that the solar diffuser plate does not decay in the early orbit stage. The same solar angle ratio calculation is used, thereby verifying the stability of the solar diffuser reflector without discussing the angle factor. The angle factor is calculated and compared with laboratory measurements. Results show that the deviation between the calculated values and the measured values of the laboratory is less than 0.5%. The angle factor measured prior to the launch can be used to calculate the BRDF degradation factor of the SD.