| 摘要 |
Provided is a dioptric projection optical system favorably applicable to projection exposure apparatus used in the lithography step in fabrication of microdevices such as semiconductor devices. This projection optical system includes a positive, front lens unit (GF), an aperture stop (AS), and a positive, rear lens unit (GR) and is a bitelecentric optical system. The optical system satisfies the following condition:where f2 is a focal length of the rear lens unit (GR) and L is a distance between an object and an image.The projection optical system includes at least one aspheric surface (ASP 1 to ASP 6).
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