Patent ID: 7973908

Claim:
A projection system for guiding light from an object plane to an image plane, the projection system comprising: at least a first mirror, a second mirror, a third mirror, a fourth mirror, a fifth mirror and a sixth mirror centered around an optical axis and arranged along the optical axis, so that during use the light travels from the object plane to the first mirror, then from the first mirror to the second mirror, then from the second mirror to the third mirror, then from the third mirror to the fourth mirror, then from the fourth mirror to the fifth mirror and then from the fifth mirror to the sixth mirror, wherein the third mirror, the fourth mirror and the sixth mirror are arranged along the optical axis geometrically between the first mirror and the second mirror, the projection system has an image side numerical aperture greater than 0.2, and the projection system is configured to be used with wavelengths less than 193 nm.