An optical imaging system for inspection microscopes with which lithography masks can be checked for defects particularly through emulation of high-aperture scanner systems. The microscope imaging system for emulating high-aperture imaging systems comprises imaging optics, a detector and an evaluating unit, wherein polarizing optical elements are selectively arranged in the illumination beam path for generating different polarization states of the illumination beam and/or in the imaging beam path for selecting different polarization components of the imaging beam, an optical element with a polarization-dependent intensity attenuation function can be introduced into the imaging beam path, images of the mask and/or sample are received by the detector for differently polarized beam components and are conveyed to the evaluating unit for further processing.