Projection optical system and projection exposure apparatus

摘要

A projection optical system that projects an image of an object in an object surface onto an image surface with a fixed reduction magnification comprises, in light path order from the object surface: a first group of lenses with positive refractive power; a second group of lenses forming an approximately afocal system; and a third group of lenses with positive refractive power. The projection optical system has a focal length F, the projection optical system has a projection magnification B, the object surface and the image surface are separated by a distance L, and a lens surface in the first group of lenses that is closest to the object surface is separated from the object surface by a distance d0. A paraxial marginal ray from an axial object point on the object surface enters the second group of lenses G2 at an entrance height h1 from an optical axis, and the paraxial marginal ray from the axial object point on the object surface emerges from the second group of lenses G2 at an emergence height h2 from the optical axis. The optical system is characterized by the following: 1.8