General construction method for a rotationally symmetric ultrashort distance catadioptric projector

In this work, the off-axis imaging of a fan of rays with a rotationally symmetric mirror is studied, based on which a general construction method is proposed for the design of a rotationally symmetric ultrashort distance catadioptric projector. With the proposed method, the intermediate images at arbitrary planes of incidence can be obtained, and thus the designer has the freedom to choose suitable intermediate images to simplify the aberration correction of the catadioptric starting point. To prove the effectiveness of the proposed method, the construction process of a convex-type ultrashort distance catadioptric projector is presented. The intermediate image at the meridional plane is discontinuous, and the image distances for some fields are infinite. In contrast, the intermediate image at the sagittal plane is continuous, smooth, and finite-and thus is selected to correct the skew aberrations in the catadioptric starting point. An initial configuration, which has small aberrations, is obtained without increasing the system complexity. Further automatic optimization is applied to the initial configuration to get the optimal solution. The simulated performance of the optimal solution is excellent.