Cheng, Dewen Xu, Chen Wang, Yongtian Automatic_obscuration_elimination_eg2.mp4 Example 2 in paper "Automatic obscuration elimination for off-axis mirror systems". Optical design and fabrication;Imaging systems;Mirror system design 2017-11-06
    https://opticapublishing.figshare.com/articles/media/Automatic_obscuration_elimination_eg2_mp4/5372962
10.6084/m9.figshare.5372962.v1