基于太阳漫射板+稳定性监视辐射计的星上定标方式能有效地提高遥感数据定量化水平，其中漫射板的双向反射分布函数(BRDF)定标精度是高精度星上定标的关键，BRDF绝对测量可实现漫射板的高精度定标。为解决高精度BRDF绝对测量的关键技术，设计了高亮度、高稳定度、高均匀性积分球光源；使用单色仪和单片探测器对大动态范围入射和反射辐亮度信号进行高精度探测，并利用锁相放大器对信号进行放大和采集；采用样品漫射板三维转动和三维平移及光源一维转动的组合运动形式，以高精密六轴串联机械手和中空分度盘分别作为样品漫射板和光源的定位机构，可高精度、无遮挡、快速地构建BRDF测量所需的几何关系。研制的装置可实现包括“平面外”在内的全角度BRDF绝对测量，可测量的入射、反射光束角度范围：天顶角为0°~75°、方位角为0°~360°，目前可测量的光谱范围为250~1700 nm，装置的BRDF绝对测量不确定度优于1%。

The method of on-board calibration based on sun-diffuse panel panel plus radiometer for stability monitoring can improve the level of quantification of remote sensing data, and the BRDF calibration accuracy of diffuse panel is the key of high-precision on-board calibration, and the BRDF absolute measurement can realize high-precision calibration of the diffuse panel. In order to solve the key technology of high-precision BRDF absolute measurement, we design a high-brightness, high-stability and high-uniformity integrating sphere as the lamp source; using a monochromator and a single detector to detect the incident and reflected radiance signals with large dynamic range accurately, moreover using a lock-in amplifier to amplify and acquire the signals; using high-precision six-axis robot and hollow rotary indexing table orientate sample diffuse panel with three-dimensional rotation and translation and lamp source with one-dimensional rotation separately to construct BRDF absolute measuring geometry with high-precision, non-blocking and speediness. The device can realize omnidirectional BRDF measurements except for that out of plane, and measurable angle range is: azimuthal angle is 0°~360°, and zenith angle is 0°~75°. Currently measurable spectral range is 250~1700 nm. The uncertainty degree of this device can be less than 1%.