分析和研究了测量绝对反射比因子的原理,设计、制作了一套可以测量光源入射照度和反射辐亮度的比辐射计和一套45°/0°漫反射板绝对反射比因子测量装置。首先，使用比辐射计测量光源的入射照度和反射辐亮度，给出漫反射板绝对反射比因子的计算公式；然后，根据推导公式中辐射亮度由测量比辐射计的光阑面积决定，提出一种新的光学方法来精确测量光阑面积，从而提高测量精度。最后，介绍了测量装置的设计和其它部件的制作过程。采用该装置实验测量了安徽光学精密机械研究所研制的标准漫反射板在633~960 nm的绝对反射比因子，得到的装置的测量不确定度为0.19％。实验结果表明，该测量装置测量方法简单、精度高，可以满足反射比因子的测量要求。

The measuring principle of absolute reflectance factors was discussed, and a specific radiometer to measure both the incident irradiance and reflected radiance and a reflectometer to measure the absolute reflectance factor were designed. On the basis of the measurements of the incident irradiance and the reflected radiance, the formula for calculating the absolute reflectance of a diffuse panel was deduced, then in consideration of the measuring accuracy depended on the aperture area, a new method was proposed to measure the aperture area to achieve an exact solid angle. Finally, the design of reflectometer and the fabrication of related devices were introduced. The reflectometer was used to measure the absolute reflectance factors of a standard diffuse panel at visible and near-infrared wavelengths(633-960 nm) and results show that the uncertainty obtained by this system is 0.19％. These results demonstrate that the measuring method is simple, and can satisfy the requirements of reflecting factor measurement for the accuracy.