基于双太阳漫射板星上定标系统,建立了定标漫射板双向反射分布函数(BRDF)衰 减监测模型,介绍了用于衰减入射太阳光通量的太阳衰减屏的结构设计。衰减屏透过率是影响 星上定标精度的关键参数之一,需要在发射前精确测量。在实验室利用衰减屏透过率测量系统对 其进行多次重复测量,结果表明衰减屏在测试角度范围内透过率为13.8%,测试不确定度优 于0.54%(K为2),满足星上定标需求。测试结果可用于建立地面数据库,为后期星上定标 提供数据支撑,对保证长期星上定标精度有重要意义。

Based on double solar diffusers on-board calibration system, a bidirectional reflectance distribution function (BRDF) attenuation monitoring model of calibration diffuser is established, and the structure design of solar attenuation screen for attenuating the incident sunlight flux is introduced. The attenuation screen transmittance is one of the key parameters that affect on-board calibration accuracy, and it need to be measured accurately before launch. It is measured repeatedly with the attenuation screen transmittance measurement system. Results show that the attenuation screen transmittance is 13.8% within the test angle range, and the test uncertainty is better than 0.54% (K is 2), which satisfies the requirements of on-board calibration. Test results can be used to establish the ground database, and it can provide data support for the later satellite calibration, which is of great significance to ensure the long-term on-board calibration accuracy.