Patent ID: 8174677

Claim:
An illumination system configured to guide light from a light source toward an object field along a light path, the illumination system comprising: a first mirror in the light path, the first mirror comprising a first plurality of facets arranged in a plane across a direction of incidence of the light, the facets being offset relative to one another within the plane; a second mirror in the light path, the second mirror comprising a second plurality of facets; and an optical system following the second mirror along the light path, the optical system configured to have an influence on intensities of bundle portions of the light, wherein: the first mirror is configured to compensate for the influence of the optical system on the intensities of the bundle portions of the light, each of the first plurality of facets is assigned to a corresponding facet of the second plurality of facets, an optical element of the optical system has a first section and a second section which is spaced apart from the first section in a direction perpendicular to the light path, the first section of the optical element has a first reflectivity for the light, the second section of the optical element has a second reflectivity for the light, the first reflectivity is greater than the second reflectivity, for each corresponding facet of the second plurality of facets, the facet is assigned to the first section of the optical element or to the second section of the optical element, during use, the light impinging on a first facet of the second mirror that is assigned to the first section of the optical element has an integral power intensity that is lower than an integral power intensity of light impinging on a second facet of the second mirror that is assigned to the second section of the optical element, and the illumination system is configured to be used in microlithography projection exposure apparatus.