Projection lens for a microlithographic projection exposure apparatus

Abstract

A projection lens (10) for a microlithographic projection exposure apparatus has a first optical element, for example a birefringent lens (L2), that has polarization dependent properties causing intensity fluctuations in an image plane of the projection lens. These fluctuation may be produced by a second optical element (24), for example a polarization selective beam splitting layer (28), that is arranged downstream of the first optical element. A gray filter (32; 132; 232) disposed in the beam path reduces the intensity fluctuations.

Dependencies are inferred from the claim text.