Due to the inherent advantages of free-form surfaces, the design and development of infrared optical free-form surfaces has become the development trend of cutting-edge infrared imaging optical systems. It is to solve the contradiction between large field of view, long focal length and system miniaturization in infrared imaging systems, and to achieve high One of the key technologies and effective means of infrared optical system with high performance, miniaturization and light weight. The performance and image quality of thermal imagers based on free-form optical design are significantly improved compared to traditional thermal imagers.