A method for the optical detection of an illuminated specimen, wherein the illuminating light impinges in a spatially structured manner in at least one plane on the specimen and several images of the specimen are acquired by a detector in different positions of the structure on the specimen. An optical sectional image and/or an image with enhanced resolution is then calculated. The method includes generating a diffraction pattern in the direction of the specimen in or near the pupil of the objective lens or in a plane conjugate to the pupil. A phase plate with regions of varying phase delays is dedicated to the diffraction pattern in or near the pupil of the objective lens or in a plane conjugate to said pupil, and different phase angles of the illuminating light are set.