ACCOMMODATING ADDITIONAL DATA ON AN OPTICAL DATA CARRIER DISK

摘要

An optical data carrier disk reader is adapted for detecting a slope of a wall in a data track of an optical disk. An optical disk has pits (811, 812), having walls with at least two different steepnesses, in its data track. The steepness represents information written on the optical disk. A method for making an optical disk stamper (8) comprising exposing portions of a photo-sensitive layer to electro-magnetic radiation is also described. By controlling the variation of the focal point during exposure, the inclination of the walls between the bump (811, 812) or pit forming portions and the "land" forming portions of the surface of the optical disk stamper (8) can be controlled.