Instrument for measuring the angular distribution of light produced by an illumination system of a microlithographic projection exposure apparatus

摘要

An instrument for measuring the angular distribution of light produced by an illumination system of a microlithographic projection exposure apparatus comprises pinhole (82) and a polarization conversion unit (92), for example a quarter-wave plate, that converts at least one state of polarization of the light into a circular state of polarization. An irradiance sensor (96) such as a CCD image sensor detects the spatial distribution of light having passed the pinhole (82) and being in a circular state of polarization. An aspheric collimating lens (90) may be arranged between the pinhole (82) and the polarization conversion unit (92).