| 摘要 |
The disclosure relates to an exposure system of a microlithographic projection exposure apparatus that includes a light source which produces substantially linearly polarised light which is propagated along a light propagation direction. The system also includes a light mixing system and an effectively depolarising system which is arranged upstream of the light mixing system in the light propagation direction. The effectively depolarising system causes a variation in the polarisation direction over the light beam cross-section such that the light mixing effected by the light mixing system substantially produces light without a polarisation preferred direction in an illumination plane, wherein the effectively depolarising system has at least one element of optically active crystal material with at least one portion extending substantially wedge-shaped in the light propagation direction, wherein the optical crystal axis is substantially parallel to the light propagation direction. The disclosure also provides a depolarizer which can be used in an illumination system.
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