Illumination system for illuminating a mask in a microlithographic exposure apparatus

摘要

A diffractive optical element (156) is configured to be inserted into a light beam path of an illumination system (112) of a microlithographic projection exposure apparatus (10) such that it produces a desired intensity distribution in a system pupil surface (154) of the illumination system, wherein a Fourier transform of an angular distribution produced by the diffractive optical element (156) differs from the desired intensity distribution.