| 摘要 |
PROBLEM TO BE SOLVED: To prevent a protect code contained in a recorded signal from being read by conventionally reproducing the recorded signal recorded on a disk, and to provide an optical information recording medium permitting to record a protect code in any place without involvement of physical damage on the disk, and thereby prevent the disk from illegal copy. SOLUTION: This is an optical disk A formed by sequentially laminating a substrate 1 having rows of pits 5 or guide grooves arranged in a concentric circular form or a spiral form at a specified track pitch, a photo-chromic layer 2 made of a photo-chromic material formed on a part of or a whole surface of the substrate 1, and a reflecting layer 3 on the photo-chromic layer 23. Copy preventive information such as a bar code, characters, a pattern, etc., are recorded on the photo-chromic layer by varying an optical characteristics of the photo-chromic layer 2 by irradiating the layer with ultraviolet ray or laser light. |
