Illumination system for microlithographic projection exposure system, has astigmatic refractive optical element astigmatically changing intensity distribution in pupil surface by arrangement on different positions along optical axis

摘要

The system (12) has a field plane exhibiting an angular distribution of light produced by the system. Intensity distribution in a pupil surface is adjustable during an operation for influencing the angular distribution of the light in the field plane. An astigmatic refractive optical element has an optically effective surface consisting of two flat partial surfaces that are bent to each other. The astigmatic refractive optical element astigmatically changes the intensity distribution in the pupil surface by arrangement on different positions along an optical axis. An independent claim is also included for a method for imaging a mask with structures on a light-sensitive layer.