Wei Lei, Yang Lin, Fan Yuan-Peng, Cong Shan-Shan, Wang Yan-Song
Institute of Frontier and Interdisciplinary Science, Shandong University, Qingdao 266237, China.
Chang Guang Satellite Technology Co., Ltd., Changchun 130000, China.
Sensors (Basel). 2022 Jun 24;22(13):4772. doi: 10.3390/s22134772.
The stray-light suppression of a large off-axis three-mirror anastigmatic space camera has been a hot topic, and this study proposes a composite stray-light suppression strategy that effectively suppresses stray light using the combination of a baffle, retaining ring, and internal antistray light measures. Additionally, the light barrier of the third mirror with a three-layered structure was designed to further optimize the composite stray-light suppression system. At the stray-light simulation analysis stage, in view of the limitations of the Torrance-Sparrow scattering analysis model, an analysis model with wide adaptability is proposed, which can be applied to the stray-light simulation analysis of large-size mirrors with rough surfaces. The simulation results indicate that the point source transmittance of the composite stray-light suppression strategy proposed in this paper is of the order of 10 before installing the light barrier of the third mirror, and the veiling glare index of the full field of view is less than 5.8%. After installing the light barrier of the third mirror, the point source transmittance reached the order of 10, and the veiling glare index of the full field of view was less than 1.31%. Moreover, the influence of the light barrier of the third mirror on the modulation transfer function of the system was less than 2.3%. The modulation transfer function test of the large-width off-axis three-mirror anastigmatic space camera in a simulated vacuum on-orbit environment was completed, and the test results indicated that the negative impact of the light barrier of the third mirror on the modulation transfer function was less than 3.6%. Moreover, an out-of-field imaging test of the space camera was conducted and the results showed that the image was clear, and the SNR reached 80 dB. The simulation and experimental results prove that the solution in this study can effectively solve the problem of stray-light suppression for large off-axis three-mirror anastigmatic space cameras.
大口径离轴三镜消像散空间相机的杂散光抑制一直是研究热点，本研究提出一种复合杂散光抑制策略，通过遮光罩、固定环和内部抗杂光措施相结合有效抑制杂散光。此外，设计了具有三层结构的第三镜光阑，以进一步优化复合杂散光抑制系统。在杂散光仿真分析阶段，针对托伦斯 - 斯帕罗散射分析模型的局限性，提出了一种适应性广的分析模型，可应用于粗糙表面大尺寸镜面的杂散光仿真分析。仿真结果表明，本文提出的复合杂散光抑制策略在安装第三镜光阑前点源透过率为10的量级，全视场杂光系数小于5.8%。安装第三镜光阑后，点源透过率达到10的量级，全视场杂光系数小于1.31%。而且，第三镜光阑对系统调制传递函数的影响小于2.3%。完成了大口径离轴三镜消像散空间相机在模拟真空在轨环境下的调制传递函数测试，测试结果表明第三镜光阑对调制传递函数的负面影响小于3.6%。此外，对该空间相机进行了视场外成像测试，结果显示图像清晰，信噪比达到80dB。仿真和实验结果证明，本研究中的解决方案能够有效解决大口径离轴三镜消像散空间相机的杂散光抑制问题。
