Patent ID: 11441970

Abstract:
A measurement apparatus (10) for measuring a wavefront aberration of an imaging optical system (12) includes (i) a measurement wave generating module (24) which generates a measurement wave (26) radiated onto the optical system and which includes an illumination system (30) illuminating a mask plane (14) with an illumination radiation (32), as well as coherence structures (36) arranged in the mask plane, and (ii) a wavefront measurement module (28) which measures the measurement wave after passing through the optical system and determines from the measurement result, with an evaluation device (46), a deviation of the wavefront of the measurement wave from a desired wavefront. The evaluation device (46) determines an influence of an intensity distribution (70) of the illumination radiation in the region of the mask plane on the measurement result and, when determining the deviation of the wavefront, utilizes the influence of the intensity distribution.