Mask inspection microscope with variable lighting setting

In the mask inspection defects are visible, which also occur during wafer exposure. Therefore, the aerial images generated in the resist and on the detector must be identical as possible. In order to achieve an equivalent imaging, lighting and object-side numerical aperture to be adjusted scanner used in mask inspection. The invention relates to a mask inspection microscope for variably adjusting the lighting. It is used for forming an image of the structure (150) of which is arranged in an object plane of the reticle (145) in a field plane of the mask inspection microscope. It has a projection light emitting light source (5), at least one illumination beam path (3, 87, 88) and a diaphragm to produce a resultant intensity distribution of the projection light in an optically conjugate to the object plane pupil plane (135) of the illumination beam path (3, 87, 88) on , According to the invention the diaphragm is configured such that the resulting intensity distribution of the projection light between a minimum and a maximum intensity value, at least one further intensity value.