针对目前光学口径不断增大的空间光学遥感器实验室辐射定标的需求, 基于近距离扩展源照明方法设计了400~900 nm谱段内最大积分辐射亮度为200 W/(m2·sr)的4 m直径均匀扩展定标光源。该定标光源内径为4 000 mm, 出光面直径为1 600 mm。对该定标光源光机结构进行了详细设计, 利用光纤光谱仪监视输出的相对光谱分布, CPLD结合单片机实现输出光谱辐亮度值无人值守智能化远程自动控制。使用PR 735光谱辐射计测量该光源400~900 nm谱段内最大积分辐射亮度为22262 W/(m2·sr), 通过对定标光源的稳定性、面均匀性及角度均匀性测试, 分析了定标光源的测量不确定度为357%。实验结果表明: 该定标光源可以满足口径1 600 mm以下可见/近红外空间光学载荷的实验室辐射定标需要, 并可实现智能程控化控制, 提高了定标测试精度。

In order to meet the requirements of laboratory radiometric calibration for continually rising optical aperture of optical remote sensors, 4 m extended uniform source for radiometric calibration is designed based on near extended source method. The maximum integrated radiance in the range of 400 nm to 900 nm is 200 W/(m2·sr). The diameter of the calibration source is 4 000 mm and the exit port diameter is 1 600 mm. The opto-mechanical parameters of the calibration source are designed in detail. Using fiberoptic spectrometer to monitor relative spectral distribution, the calibration source can realize intelligent programmable remote control through CPLD combined with SCM to export specific integrated radiance. The maximum integrated radiance in the range of 400 nm to 900 nm is measured 222.62 W/(m2·sr) using PR 735 spectrum radiometer. The measure uncertainty of the calibration source is analyzed by testing the radiation characteristics, including the stability, the uniformity,the lambertian, and the value is 357%. From the experimental results,the calibration source can satisfy the laboratory calibration needs for the visible/near-infrared optical remote sensors with the optical aperture under 1 600 mm. Meanwhile it can realize intelligent programmable control to improve the calibration accuracy.