A microscope device which has a diffraction-limited resolution volume, with multiple dye molecules that can be switched between different states, at least one of which is fluorescent. The fluorescence is focused using an objective lens and is imaged onto a spatially resolving detector. In at least one portion of the sample, the dye molecules have a distribution density that is greater than the inverse of the diffraction-limited resolution volume. One or more light sources are provided for emitting a switching radiation in order to switch a first subset of the dye molecules in the sample, and for emitting an excitation radiation in order to excite the first subset of dye molecules. A phase mask which generates a light distribution having an at least partially limited local minimum radiation on the detector plane is provided in the beam path, preferably in the detection beam path.