Patent ID: 7203008

Claim:
A projection objective for projecting a pattern arranged in the object plane of the projection objective into an image plane of the projection objective with the aid of ultraviolet light of a prescribed operating wavelength, the projection objective comprising: a plurality of optical elements which are arranged along an optical axis; and a diaphragm located at a system diaphragm within the projection objective, the system diaphragm being the location in which a main beam of the projection objective intersects the optical axis for the last time prior to reaching the image plane, the diaphragm having a diaphragm diameter; the optical group with refractive power next to the image plane being a planoconvex group having a substantially spherical entrance surface and a substantially flat exit surface; and the planoconvex group having a diameter that is at least 50% of the diaphragm diameter; wherein the projection objective has an image-side numerical aperture NA>0.85.