Design of hybrid refractive-diffractive objective with super wide angle and fast f-number

To design a hybrid refractive-diffractive objective with super wide angle and fast fnumber, the interrelationship of the objective parameters was analyzed and an initial conventional spherical system was achieved to fulfill the fundamental performance, then its distortion was corrected by the aspheric surface depositing far from the optical pupil and one of doublets was replaced by hybrid refractive-diffractive lens to reduce the size of the system. Using ZEMAX software, the final visible band objective with 100° FOV and f-number 2.5 was obtained by only 6 elements with a smaller size about φ35 mm×60 mm. Simulation shows that the MTF at 25 lp/mm is greater than 0.45 in the central field and 0.3 in the full field; the maximal distortion is less than 4%, much smaller than 35% of conventional system.