摘要 |
An illumination system of a microlithographic projection exposure apparatus comprises an optical integrator having a plurality of light entrance facets and a beam deflection array of reflective or transparent beam deflecting elements. Each beam deflecting element is configured to illuminate a spot on the optical integrator at a position that is variable by changing a deflection angle produced by the beam deflecting element. The illumination system further comprises a control unit which is configured to control the beam deflection elements in such a manner that a light pattern assembled from the spots on at least one of the light entrance facets is varied in response to an input command that a field dependency of the angular irradiance distribution in a mask plane shall be modified. |