Patent ID: 8730572

Claim:
A catadioptric projection objective for imaging a pattern provided in an object plane of the projection objective onto an image plane of the projection objective comprising: a first purely refractive objective part to image the pattern provided in the object plane into a first intermediate image; a second objective part that comprises at least one concave mirror to image the first intermediate image into a second intermediate image; and a third objective part that includes one or more refractive optical elements to image the second intermediate image onto the image plane; wherein an aperture stop is positioned in the third objective part between a region of maximum beam diameter and the image surface in a region of a converging beam, wherein there are four or fewer lenses between the aperture stop and the image plane, and wherein the catadioptric projection objective has an image-side numerical aperture NA greater than 1.2 when an immersion fluid comprising water is positioned between the third objective part and the image plane.