US Patent 7268952 Catadioptric projection system, and exposure apparatus having the same

A catadioptric projection system for forming an intermediate image of a first object plural times, and images the intermediate image onto a second object includes at least two deflective reflectors, a lens unit arranged in an optical path between the two deflective reflectors, the lens unit having a negative refractive power, and not forming a reciprocating optical system that passes incident light and reflected light.