Patent ID: 9274440
Filing Date: 2016-03-01
CPC Classification: G03F

Claim Text:
1. An arrangement for characterising the polarisation properties of an optical system, comprising: at least one polarisation state generator which sets a defined polarisation state of radiation incident on the optical system; and a polarisation state detector adapted to measure the exit polarisation state of radiation issuing from the optical system; wherein the optical system is designed for a working wavelength of less than 15 nm; wherein at least one of the polarisation state generator and/or the polarisation state detector is so designed that its polarisation-optical action on an incident light beam is substantially constant over an angle spectrum of the light beam of at least 10°, wherein the angle spectrum comprises a spectrum of angles between diverging beam portions of the incident beam; wherein the at least one of the polarisation state generator and/or the polarisation state detector has at least one of a rotatable polariser and/or a rotatable retarder; wherein the at least one of the rotatable polariser and/or the rotatable retarder has at least one multi-layer system having a plurality of individual layers; and wherein the multi-layer system has a light entrance surface which is curved at least in regions along the surface such that an angle of incidence of the light beam on the surface is substantially constant for the angle spectrum of the light beam of at least 10°.