Method for examining a specimen by means of light sheet microscopy, in which - several illumination wavelengths are selected, of which illumination light for the specimen is composed, - for a middle wavelength the modulation depth of a phase-selective element is fixed at π, - wherein a predefined phase distribution is impressed on the phase-selective element and a predefined aperture structure is impressed on an aperture in an aperture plane, in that (i) a preferred wavelength is selected which comprises at least a wavelength corresponding to the longest illumination wavelength, (ii) in the focal plane of an illumination objective for a light sheet of predefined shape, its electric field is determined with light of the preferred wavelength, and therefrom the phase distribution to be predefined is calculated, wherein, in the aperture plane, a middle range is removed, with the result that (iii) the aperture structure removes the zero order of the structured light of the preferred wavelength, - the phase-selective element is illuminated with illumination light in or near to an intermediate image plane in an illumination beam path and the illumination light is structured by the phase-selective element, - the structured illumination light is imaged into an aperture plane, arranged downstream of the phase-selective element, in which a frequency spectrum of the illumination light is generated, - the aperture structure is adapted with the result that the zero orders of the structured illumination light are substantially removed in the aperture plane, whereby in a focal plane of the downstream illumination objective a structured, multicoloured light sheet is formed with a light sheet plane which is perpendicular to the focal plane of the illumination objective, - the specimen is illuminated with the structured light sheet in the light sheet plane and light emitted by the specimen is detected in a detection direction which forms an angle different from zero with the light sheet plane. - several illumination wavelengths are selected, of which illumination light for the specimen is composed, - for a middle wavelength the modulation depth of a phase-selective element is fixed at π, - wherein a predefined phase distribution is impressed on the phase-selective element and a predefined aperture structure is impressed on an aperture in an aperture plane, in that (i) a preferred wavelength is selected which comprises at least a wavelength corresponding to the longest illumination wavelength, (ii) in the focal plane of an illumination objective for a light sheet of predefined shape, its electric field is determined with light of the preferred wavelength, and therefrom the phase distribution to be predefined is calculated, wherein, in the aperture plane, a middle range is removed, with the result that (iii) the aperture structure removes the zero order of the structured light of the preferred wavelength, - the phase-selective element is illuminated with illumination light in or near to an intermediate image plane in an illumination beam path and the illumination light is structured by the phase-selective element, - the structured illumination light is imaged into an aperture plane, arranged downstream of the phase-selective element, in which a frequency spectrum of the illumination light is generated, - the aperture structure is adapted with the result that the zero orders of the structured illumination light are substantially removed in the aperture plane, whereby in a focal plane of the downstream illumination objective a structured, multicoloured light sheet is formed with a light sheet plane which is perpendicular to the focal plane of the illumination objective, - the specimen is illuminated with the structured light sheet in the light sheet plane and light emitted by the specimen is detected in a detection direction which forms an angle different from zero with the light sheet plane.