Arrangement for and method of characterising the polarization properties of an optical system

An arrangement for and a method of characterizing the polarization properties of an optical system, in particular an optical system of a microlithographic projection exposure apparatus. The arrangement includes at least one polarization state generator (130, 230, 330) which sets a defined polarization state of radiation incident on the optical system, and a polarization state detector (140, 240, 340) adapted to measure the exit polarization state of radiation issuing from the optical system, wherein the optical system is designed for a working wavelength of less than 15 nm, and wherein the polarization state generator and/or the polarization state detector are so designed that their polarization-optical action on an incident light beam is substantially constant over an angle spectrum of the light beam of at least 10°.