Patent ID: 8253925

Claim:
A system, comprising: an illumination system configured to be used in a microlithography tool, the illumination system comprising a first component comprising a plurality of reflective elements, wherein, during operation of the system, the plurality of reflective elements of the first component direct radiation from a source along an optical path to an arc-shaped object field at an object plane of a projection objective of the microlithography tool, and at least one of the plurality of reflective elements of the first component has a curved shape that is different from the arc-shape of the object field, and wherein the at least one curve-shaped element of the first component is shaped as a segment of an annulus and has an inner edge with a constant radius of curvature, IR, and a height, h, and the arc-shaped object field is shaped as a segment of an annulus and has an inner edge with a constant radius of curvature, IR f , and a height, h f , and the ratio IR/h is different from the ratio IR f /h f .