Patent ID: 7911584

Claim:
An illumination system configured to illuminate a field in a field plane, the illumination system comprising: at least one optical integrator which splits a light bundle emitted by a light source into a plurality of light channels each having a light intensity; and a filter in the light path from the light source to the field plane, with the filter comprising filter elements which are configured in such a way that the light intensity of at least one light channel is reduced in the light path after the filter elements, wherein: the optical integrator comprises a first optical element with a plurality of first raster elements; the optical integrator comprises a second optical element with a plurality of second raster elements; the plurality of first raster elements is configured to be projected directly into the field plane, or to be projected via an intermediate image into the field plane; the filter elements comprise diaphragms located in front of the plurality of first elements along the light path; the filter elements are configured to vary an expansion of the light channels in a scanning direction; and the illumination system is configured to be used in EUV microlithography with light of a wavelength in the region between about 11 nm and about 14 nm.