An apparatus for producing flat thin sections of a specimen (3) comprises a blade edge (7), a specimen carrier (4), a drive device (14) for producing a relative motion between the blade edge (7) and the specimen carrier (4) in a sectioning plane (5), and a light light-ribbon micrometer (8) arranged between the blade edge (7) and the specimen (3), wherein the light-ribbon micrometer (8) is arranged at a fixed distance (d) relative to the blade edge (7) and generates a light-ribbon in a plane perpendicular to the sectioning plane. A coding device (13) may be associated with the drive device (14) for controlling an alternating drive as a function of the distance (d) and of signals generated by the light-ribbon micrometer (8).