Automated first-order design for slim catadioptric zoom lens system by using freeform surface

The development of electronic industry demands miniaturization for zoom lens. Freeform surfaces and catadioptric lens system play important roles in the compactness of optical design. However, the initial structure of the catadioptric system is relatively rare and repeated optimizing in first-order lens design requires advanced knowledge and experiences. That brings challenges for establishing an initial structure for the freeform catadioptric zoom system, which is essential for optical designers. In this work, an automatic design method for the initial structure of a catadioptric system with freeform surface and zoom lens is proposed. As long as the focal length range and total length are determined, the initial structure of the catadioptric zoom lens with arbitrary zoom ratio in a certain range can be obtained for further analysis and optimization. The rapid design method reduces the dependence on experience for catadioptric system design, saves considerable time and can help to ease the difficulty in finding the initial structure of slim zoom lens.