An illumination apparatus for a microscope, for producing a de-excitation or switching light distribution, includes a light source configured to produce a primary illumination light beam and a beam splitter configured to divide the primary illumination light beam into two partial illumination light beams. An illumination objective is configured to focus the partial illumination light beams onto and/or into a sample such that the partial illumination light beams extend, spatially separated from one another, through an entry pupil of the illumination objective and are spatially superposed on and/or in the sample after passing through the illumination objective. A phase influencer is configured to cause a relative phase offset of the partial illumination light beams with respect to one another in such a way that the partial illumination light beams in the entry pupil of the illumination objective have a phase offset of π.