Patent ID: 8035803

Claim:
A system, comprising: a first polarization-influencing optical element which during operation converts a first polarization distribution produced by a light source unit into a second polarization distribution which is different from the first polarization distribution; and a second polarization-influencing optical element which during operation converts the second polarization distribution into a third polarization distribution corresponding to a desired polarization distribution, the second polarization-influencing optical element causing an effective rotation of the second polarization distribution through 90° over its optically effective surface, wherein: the second polarization distribution is an at least approximately radial polarization distribution and the desired polarization distribution is an at least approximately tangential polarization distribution; the system is a sub-system of an illumination system of a microlithographic projection exposure apparatus which during operation illuminates a reticle plane of the microlithographic projection exposure apparatus with light having the desired polarization distribution; and the first polarization-influencing optical element is upstream of any pupil plane of the illumination system along a path of light through the illumination system from the light source to the reticle plane.