In order to determine the locations of individual fluorescent molecules in a sample, which keep a minimum distance with regard to each other, the individual molecules are excited for emission of fluorescence light by means of excitation light. The fluorescence light is registered for different positions of a zero point of an intensity distribution of the excitation light. The distance between these positions is at least half the minimum distance of the fluorescent molecules. The locations of the fluorescent molecules are derived from the course of the intensity of the fluorescence light over the positions of the zero point of the excitation light.