Patent ID: 7626770
Filing Date: 2009-12-01
Classification: G02B,G03F

Abstract:
1. A catoptric illumination system with a light source which during operation of the catoptric illumination system emits a radiation, wherein the radiation illuminates a field in a field plane and at the same time provides an illumination in a pupil plane, wherein the illuminated area in the pupil plane has a size which can be continuously varied, the illumination system comprising: a number of optical elements arranged in such a way that the radiation is directed from the light source to the field plane and to the pupil plane, wherein a distance between at least two optical elements of the number of optical elements is variable, the two optical elements include at least one facetted optical element, and the illuminated area in the pupil plane has a shape, and said shape of the illuminated area in the pupil plane remains unchanged when the distance between the at least two optical elements is varied.