The present application relates to an apparatus for determining a position of at least one element on a photolithographic mask, said apparatus comprising: (a) at least one scanning particle microscope comprising a first reference object, wherein the first reference object is disposed on the scanning particle microscope in such a way that the scanning particle microscope can be used to determine a relative position of the at least one element on the photolithographic mask relative to the first reference object; and (b) at least one distance measuring device, which is embodied to determine a distance between the first reference object and a second reference object, wherein there is a relationship between the second reference object and the photolithographic mask.