Pupil stop for an illumination optical unit of a metrology system

Abstract

A pupil stop serves for use in an illumination optical unit of a metrology system for determining, as a result of illumination and imaging under illumination and imaging conditions corresponding to those of an optical production system, an aerial image of an object to be measured. The pupil stop has two pole passage openings for specifying a respective pole of an illumination of the illumination optical unit specified by the pupil stop. In each case at least one stop web passes through the respective pole passage opening and consequently divides the pole passage opening into a plurality of partial pole openings. This yields a pupil stop with which an accuracy of a convergence of the illumination and imaging conditions of the optical production system to the illumination and imaging conditions of the optical measurement system can be improved.

Dependencies are inferred from the claim text.