ILLUMINATION SYSTEM OF A MICROLITHOGRAPHIC PROJECTION EXPOSURE APPARATUS

摘要

The invention relates to an illumination system of a microlithographic projection exposure apparatus comprising a depolariser (10, 500-900) which in conjunction with a light mixing system disposed downstream in the light propagation direction at least partially causes effective depolarisation of polarised light impinging on the depolariser (10, 500-900) and a microlens array (20) which is arranged upstream of the light mixing system in the light propagation direction and in which a plurality of microlenses (20a, 20b,... ) are arranged with a periodicity, wherein the depolariser (10, 500-900) is such that a contribution afforded by interaction of the depolariser (10, 500-900) on the one hand with the periodicity of the microlens array (20) on the other hand, to a residual polarisation distribution occurring in a pupil plane (PP) arranged downstream of the microlens array (20) in the light propagation direction has a maximum degree of polarisation of not more than 5%.