Obscuration elimination in three-dimensional nonsymmetrical optical systems

Abstract

In order to avoid central obscuration in reflective optical systems, off-axis designs with mirrors tilting and decentering about optical axis are popular. With the help of freeform surfaces, the field of view and resolution of the off-axis mirror systems have been greatly improved. However, it is important to take care of mechanical vignetting during the design process and recalculate the unobscured transmitted field after the design is completed. In this paper, one method to compute obscuration-free fields in a fixed off-axis plane symmetrical system is developed. Then, one algorithm that automatically eliminates obscuration in optical systems which have no symmetry in three-dimensional space is put forward. In the end, two examples are shown to prove the feasibility of this idea.