Disclosed is a projection optical system having relatively large image-side
numerical aperture and projection field and being excellent in mechanical stability
in respect of vibrations, and the like. The projection optical system includes
a first image-forming optical system for forming a first intermediate image of
a first surface (R), a second image-forming optical system having a concave reflective
mirror and for forming a second intermediate image based on a radiation beam from
the first intermediate image, and a third image-forming optical system for forming
a final image on a second surface based on a radiation beam from the second intermediate
image. Then, predetermined conditional expressions are satisfied with regard to
a clear aperture diameter of the concave reflective mirror, a distance (L) between
the first surface and the second surface, and a distance (H) between the concave
reflective mirror and a reference optical axis.
