Miniature design of high resolution optical system for infrared seeker

A mid-wave infrared imaging guiding system with high resolution is designed. First imaging refractive system and telephoto lens groupe are used for the initialized structure. The system with three optical elements, the all field of view of 10, a focal length of 70mm, and the total length of 49mm is designed. Within -40℃~60℃, the system possesses better athermal performance. The image quality of the system almost approaches the diffraction limit. The biggest defocused spot's diameter is less than 15m. It is applicable to the infrared focal plane arrays（IR FPA）detector with the format of 640512, the pixel size of 15m and the Fnumber of 2. This system can suffice the requirements design of infrared seeker, which has the advantages of high resolution, wide field and small volume.