Design Of Off-axis Catadioptic Long Wave Infrared Zoom Optical System

With the development of science and technology, the target number of being searched and tracked is increasing. The farther distance and the more quick speed greatly increase the difficulty of searching and tracking towards the target. Therefore, the system of detection and tracking system is challenged by higher requirements.In this paper, the development trends of zoom optical system at home and abroad are summarized, the advantages and disadvantages of infrared zoom optical system are compared, and the theory of the zoom optical system is also explored. For the existed problem of infrared zoom optical system, the limitations of infrared materials are taken into account. An off-axis catadioptric design method is proposed and a long wave infrared zoom optical system with the band in the range of 8 ~ 12?m, the focal length range from 200 to 2000 mm, F number 4 is designed. In order to ensure the feasibility of processing and alignment, the tolerance analysis is conducted. The design results show that this system has a good image quality within the range of focal lengths; and the diffraction limitation is reached at 201 p / mm of cut-off frequency; and the cam curve is smooth without inflection. The system has the features like being unobstructed when it zooms, a large zoom ratio, and long focal length, which meets the needs of infrared detection tracking system preferably.