零彗差自由点条件下的失调光学系统波像差特性分析

基于矢量像差理论,对反射式光学系统的一类特殊失调状态——满足零彗差自由点条件展开研究,分析了该特殊失调下三阶彗差和三阶像散的全视场波像差特性,建立了三阶像散双节点位置的解析计算公式,研究发现该类失调不会引入三阶彗差,并且会导致三阶像散的一个节点位于中心视场附近,揭示了当前传统装调方法中仅采用轴上彗差为零作为系统完善装调的弊端,并基于像差特性分析提出了一种仅根据轴上视场引入定量失调误差前后的像差变化来评估系统完善装调的方法。利用CODE V(Version 10.2)对两反式光学系统进行了仿真分析,结果表明文中建立的模型和方法可定量分析三阶像散双节点的位置及该类失调对系统波像差的影响规律,并验证了所提出系统完善装调方法的有效性。

Wave front aberration analysis for misaligned optical systems based on the coma-free pivot point

Based on the nodal aberration theory, a special case of misalignments for reflective optical systems, which satisfying the condition of the coma-free pivot point, was studied. Under the effect of the special misalignments, the full field display aberration characteristics of the 3rd order coma and the 3rd order astigmatism were analyzed, and the analytical calculation formula of the two nodes position of the 3rd order astigmatism was established. It was found that the 3rd order coma would not change, and one node of the 3rd order astigmatism would locate near the central FOV (field of view), which revealed the drawback of using only coma-zero in axial FOV as the criterion of perfect alignment during the traditional optical assembly. Based on the analysis of wavefront aberration, a method to judge whether the system was aligned well according to the variance of wavefront aberration in only one axial FOV after introducing quantitative misalignments was proposed. A type of two-mirror optical system was adopted by CODE V(Version 10.2) to simulate the effect of misalignments on wavefront aberration, results show that the model and the method established can quantitatively analyze the two nodes position of the 3rd order astigmatism and verified the validity of the proposed judgement method for system assembly.