Approach to increase the image performance of the uncoaxial three-mirror reflective system

The method on how to design the uncoaxial three reflective system is introduced.It is based on the design of the coaxial three reflective system. By designing the coaxial three reflective system, the original structure parameters of the uncoaxial three reflective system are obtained. The aperture is placed on the first surface and decentered to a suitable position to avoid the obstruction of the light. The system is optimized. It is pointed out that the use of uncoaxial,tilted , polynomial aspheric reflective surfaces can improve the image quality effectively. Two examples are given, one is F =10 and small field angle, another is F =1.67 and wide field angle. The evaluation shows that the optimization of the decenter amount, tilt degree, aspheric coefficients can not only increase the image quality, sometimes also help to shorten the whole length of the system.