Patent ID: 7154676

Claim:
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 system diaphragm arranged at a distance in front of the image plane; the projection objective being designed as a purely refractive single-waist system with a belly near the object, a belly near the image and a waist therebetween, and there being arranged in a region of divergent radiation between the waist and the system diaphragm a negative group which has an effective curvature with a concave side directed towards the image, where the effective curvature has a radius of curvature of r c whose ratio r c /DB to the aperture diameter DB of the system diaphragm is in a range between approximately 0.8 and approximately 2.2.