Method and device for spatially periodic modification of a substrate surface

Method for modifying in a spatially periodic manner at least in some regions a surface of a substrate (24), said surface being disposed on a sample plane (P) by acting upon different regions (211, 221, 231, 232) of the substrate surface successively with a spatially periodic illumination pattern of an energy density above a processing threshold of the substrate surface, where the illumination pattern is generated by diffraction of an input beam (10) and superimposition of resulting, diffracted sub-beams (12, 14) by means of a grid interferometer (100), and where, in order to select the respective substrate surface region to be illuminated (211, 221, 231, 232), the input beam (10) is deviated by means of a beam-deviating unit (16) arranged upstream of the grid interferometer (100), wherein the input beam (10) passes through an F-Theta lens (22) between the beam-deviating unit (16) and the grid interferometer (100).