Determining the position of structures on a mask for microlithography

A method for determining the position of structures on a mask for microlithography, wherein structures of the mask (102) with illumination light of a lighting device (103, 104) to be illuminated, wherein by this mask (102), light coming from an optical imaging system (105) (on a detector unit is mapped 107) and detected, and wherein (from the detector unit 107) image data received are evaluated in an evaluation unit (108) for determining the position of the structures, characterized, in that of the detector unit (107) captured image data are subjected to the evaluation of a post, said post-processing is performed such that at least one effect, which in imaging of a mask (102) through a projection lens (20) of a microlithographic projection exposure apparatus (to a wafer 40) causes a distortion of the image of the structures of the mask (102) in the wafer plane, emulated, wherein starting from the post-processing of the image data subjected to a position determination of the structures on a mask is carried out; wherein the at least one effect includes the deflection of a wafer held in a wafer plane of the microlithographic projection exposure apparatus (40).