Patent ID: 6909492

Claim:
A projection optical system for forming an image of a first surface onto a second surface, comprising: a first image-forming optical system for forming a first intermediate image of the first surface, the first image-forming optical system being arranged in an optical path between the first surface and the second surface; a second image-forming optical system including at least one concave reflective mirror and for forming a second intermediate image based on a radiation beam from the first intermediate image, the second image-forming optical system being arranged in an optical path between the first image-forming optical system and the second surface; and a third image-forming optical system for forming a final image onto the second surface based on a radiation beam from the second intermediate image, the third image-forming optical system being arranged in an optical path between the second image-forming optical system and the second surface, wherein a condition of: Ec/(Na×Ic)<10 is satisfied where a clear aperture diameter of the concave reflective mirror is Ec, an effective diameter of a projection field on the second surface is Ic, and an image-side numerical aperture of the projection optical system is Na.