Rearch Of Infrared Catadioptric Optical System With Large Field For The Panoramic Early Warning System

With the development of modern technology, especially the development ofinformation technology at high speed，the infrared early warning systemplays an increasingly important role. Infrared optical system is in theforefront of the infrared early warning system, so it is equivalent tothe eye of the entire system. Its main task is to collect the infraredradiation from the target and background to the detector. With thedevelopment of science and technology, a variety of detectors have arisen.And the requirements of infrared detection system are raised. So thedemand for the infrared optical system has been raised. The project ofinfrared optical system includes the design of overall dimensions and thestructure of suppressing stray light. Stray light analysis is one of thekey to complete the task for the infrared early warning systemThe paper designs a infrared optical system with large field for theinfrared early warning system. And it analyzes the stray light of thesystem. In the first part of this paper, the initial structure is chosenaccording to the indicator of the system. The design of the system is stillbased on a two-mirror system which has small field of view. In order toovercome this difficulty, primary and secondary mirrors use Mangin mirrorstructure. This approach avoids using the high non-spherical surface, andreduces the difficulty of processing. The initial structure of the systemis inputted to the ZEMAX, and a certain constraint functions are set, andthen the system automatically optimizes.The method saves a lot of time.In the second part of the paper, the design of structure which used toeliminating stray light is finished. The paper introduced the principlesof infrared system stray light analysis. A detail discuss about straylight sources and analysis steps of stray light have also been given, which make function for subsequent stray light analysis. According to thedefinition of the infrared optical system, stray light source of infraredoptical systems with big field is pointed. And the structure usingeliminating stray light is built. In order to reduce the internalradiation, reflective vanes are used in the baffle interior. The modelof infrared optical system is built. Tracepro software is used to buildthe system model and simulate analysis of the system. The results indicatethat stray light is well suppressed, and the PST can achieve a level of10^(-4)～10^(-10).At the same time, the internal radiation energy thatgets to imager can achieve a level of10^(-8) watt. Consequently the systemcan achieve a clear image.