Design Of Catadioptric Infrared Optical System With Wide Field

Many infrared optical systems usually adopt catoptric systems. Because that the system does not have chromatism and restriction of the working wave. But the coma and astigmatism of off-axis point is large, so the field of view that we can use is restricted. In the needs of infrared early warning system for sea-based, a large field of catadioptric infrared optical system is designed. The optical system breaks the limitation of traditional reflective optical system with small field of view. The system adopts two methods to expand the field of view. One is adding the calibration group before the reflecting system .The other one is that the primary and secondary reflective mirror system are used of Mangin mirror. So the optical system avoids any high-order aspheric surface .In order to match the cold aperture exactly, lens group is inserted after the first image plane. The system's field can reach 8 degree, and the ratio of obscuration is less than 0.4, and also optical transfer function achieves diffraction limit.