Patent ID: 7910900

Claim:
A collector, comprising: at least two mirror shells arranged inside each other around a collector axis, wherein: the collector is configured to be used in an illumination system of a microlithography projection exposure apparatus; the collector is configured so that, during use, a light source side of the collector can collect light from a light source; a maximum thickness of at least one of the least two mirror shells is greater than 0.5 mm; a ratio of an effective solid angle of the collector on the light source side to the subtended solid angle of the collector on the light source side is greater than 0.8; the ratio of the effective solid angle of the collector on the light source side to the subtended solid angle of the collector on the light source side is greater than R, where R=0.96−0.04/mm*D, and D is a maximum thickness of the at least two mirror shells measured in mm.