Patent ID: 8755031

Claim:
An illumination system having a pupil surface, the illumination system comprising: an optical raster element configured to produce a plurality of secondary light sources located in the pupil surface, the optical raster element comprising a plurality of light entrance facets, each light entrance face being associated with one of the secondary light sources; and a beam deflecting device comprising an array of reflective or transparent beam deflecting elements, each beam deflecting element being configured to illuminate a spot on one of the light entrance facets at a position that is variable by changing a deflection angle of the beam deflecting element, the spots illuminated by the beam deflecting elements having a total area that is at least 5 times smaller than a maximum total area of any of the light entrance facets, wherein: during use of the illumination system, points on the light entrance facets are imaged onto a mask plane; and the illumination system is configured to be used in a microlithographic projection exposure apparatus.