Patent ID: 6115175
Filing Date: 2000-09-05
Classification: G02B,G03F

Abstract:
A UV image forming optical system having au image projection mode during which a point on a reticle is imaged as a point on a photosensitive member, and an adjusting mode during which aberrations in said system are measured, said UV image forming optical system comprising:a collimating optical system through which a bundle of rays from a point on side reticle is collimated into a parallel bundle of rays;an imaging optical system that images said collimated bundle of rays, transmitted through said collimating optical system, onto said photosensitive member;a beam splitting system positioned along an optical path between said collimating optical system and said imaging optical system said beam splitting system comprising a beam splitter;said UV image forming optical system including, during said adjusting mode, an interferometer in which a collimated bundle of rays emitted from said collimating optical system, reflected by said beam splitter and further reflected by a reference mirror, interferes with a bundle of rays transmitted through said beam splitter, transmitted through said imaging optical system, reflected by a reflecting member, which replaces the photosensitive member, and transmitted back through said imaging optical system to form interference fringes, which includes the aberration information, said reflecting member being positioned at a location where said photosensitive member is positioned during said image projection mode;wherein, during said adjusting mode, said photosensitive member is removed and is replaced by said reflecting member, said reflecting member comprising one of a spherical reflecting member having a center of curvature located on a focal plane of said imaging optical system, and a reflecting surface located on said focal plane of said imaging optical system, for measuring different types of aberrations.