Patent ID: 8675178
Filing Date: 2014-03-18
Classification: G03F

Abstract:
1. An apparatus, comprising: a light source configured to generate pulsed light; an illumination device; a projection objective having an object plane and an image plane; a polarization-influencing optical element comprising first, second, third and fourth polarizer elements offset by 90° relative to one another in a circumferential direction about an optical axis of the illumination device, and wherein the first and second polarizer elements lie opposite one another and are transmissive to light of a first polarization direction, and wherein the third and fourth polarizer elements are transmissive to light of a second polarization direction perpendicular to the first polarization direction; and a photoelastic modulator between the light source and the illumination device, wherein the illumination device is configured to illuminate the object plane of the projection objective during use, the projection objective is designed to project an image in the object plane of the projection objective to the image plane of the projection objective during use, and the apparatus is a microlithographic projection exposure apparatus; wherein the apparatus is configured so that during use of the apparatus: