Patent ID: 7271876

Claim:
A projection objective for microlithography for imaging a pattern arranged in an object plane of the projection objective into an image plane of the projection objective, comprising: between the object plane and the image plane, a catadioptric first objective part comprising a concave mirror and a beam deflection device and, behind the beam deflection device, a dioptic second objective part; wherein the beam deflection device of the catadioptric first objective part comprises a first mirror surface for deflecting the radiation coming from the object plane to the concave mirror and a second mirror surface for deflecting the radiation reflected from the concave mirror in the direction of the second objective part, wherein at least one of the first mirror surface and the second mirror surface is a polarization splitter device which is operated only once in reflection between the object plane and the image plane; and wherein the polarization splitter device is designed to discard a direction of polarization of light impinging on the polarization splitter device such that substantially only one direction of polarization contributes to the formation of an image in the image plane.