Patent ID: 7940375

Claim:
An illumination system for a microlithography projection exposure machine for illuminating an illumination field with light from a primary light source, comprising: a pupil shaping unit configured to produce a prescribed light distribution in a pupil plane of the illumination system; a transmission filter apparatus configured for spatially dependent intensity filtering of an incident light distribution, the transmission filter apparatus being arranged at or in a vicinity of the pupil plane of the illumination system or at or in a vicinity of a further pupil plane conjugate to the pupil plane; wherein the transmission filter apparatus includes at least one retardation device configured to be operated in transmission to produce a spatially dependent retarding effect on the light of the incident light distribution, where the retardation device is configured to be driven to produce a temporally variable, spatially dependent retarding effect; and at least one polarization filter arrangement arranged in a light path downstream of the retardation device.