Patent ID: 6860610
Filing Date: 2005-03-01
Classification: G02B,G03F

Abstract:
1. A reflection type projection optical system for projecting a pattern on an object surface onto an image surface and for serving as an imaging system that forms an intermediate image between the object surface and image surface, said reflection type projection optical system comprising four or more mirrors arranged substantially as a coaxial system to reflect light from an object side to an image side, and reflection surfaces on the four or more mirrors forming the same direction for forming a reflection angle, wherein said reflection type projection optical system is a twice-imagine system, and the four or more mirrors include, in order along an optical path from the intermediate image to the image surface, a convex mirror whose convex surface faces the object side, and a concave mirror whose concave surface faces the image side, and wherein said reflection type projection optical system images only off axis light incident upon the object surface onto the image surface.