百叶遮光罩对卡塞格林系统能量集中度的影响

Effect of shutter-type baffle on energy concentration of Cassegrain system

以机载星敏感器为代表的高精度卡塞格林光学系统对能量集中度具有很高的要求。百叶遮光罩以其低遮拦比、高杂散光抑制能力、结构稳固等优势应用于卡塞格林光学系统中,然而仅以遮拦效应来评估百叶遮光罩对系统能量集中度的影响存在较大误差。从圆孔的夫琅和费衍射出发,推导具有百叶遮光罩的卡塞格林光学系统的衍射强度分布,证明了百叶遮光罩的衍射效应会对卡塞格林光学系统能量集中度产生较大影响。通过在Zemax中建立的光学系统模型分析表明,百叶遮光罩的衍射效应引起卡塞格林光学系统能量集中度的降低值是遮拦效应的3倍以上,并且叶片数量或厚度的增减都会引起能量集中度的显著下降。为百叶遮光罩的设计提供了理论依据和精确模型。

High-precision Cassegrain optical system, represented by airborne star sensors, has high demand for energy concentration. The shutter-type baffles are used in the Cassegrain optical system with its advantages of low masking ratio, high stray light suppression ability, stable structure, etc. However, there is a large error in the method of using masking effect to assess the impact of shutter-type baffle on energy concentration of the system. Based on the Fraunhofer diffraction formula of the round hole, the diffraction intensity distribution of the Cassegrain optical system with shutter-type baffles is deduced. It is proved that the diffraction effect of the shutter-type baffles will have great effect on energy concentration of the Cassegrain optical system. The analysis on the optical system model established in Zemax shows that the reduction in energy concentration of the Cassegrain optical system caused by diffraction effect of the shutter-type baffle is more than 3 times that of the masking effect. And the increase in the number or thickness of the vanes will significantly decrease the energy concentration. This work provides a theoretical basis and an accurate model for the design of the shutter-type baffles.