Design of Ultrashort-Throw Projection Imaging System Based on Catadioptric Coupling

The complex structure, small projection ratio, and large field-of-view of the catadioptric ultrashort-throw optical projection imaging system are result in slow convergence speed of optimized aberration. Hence, we proposed a design for an ultrashort-throw optical projection imaging system based on catadioptric coupling point herein. The deviation between the ideal and observed coupling points determined by calculating the position of the light coupling point at an aperture as well as the each field-of-view between the refracting lens set and the concave mirror in the proposed optical system is used as an evaluation function to optimize the aberration. Moreover, the forward and reverse designs are combined to effectively increase the optimization efficiency of the proposed optical system. Using this technique, we designed an ultrashort-throw projection lens that can project a 100 inch (2540 mm) size picture at 486 mm, with TV distortion of less 0. 2% and modulation transfer function (MTF) of each field-of-view of more 0. 5 at 117-lp/mm cutoff frequency.