| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical disk having 'watermarks' which are visible from the reproducing surface side of the disk and disappear at the time of disk forgery and a process for producing the same. SOLUTION: The optical disk A of a bonding type obtd. by successively laminating a reflection layer 2, an adhesive layer 3 and a dummy transparent substrate 4 on an information signal recording surface 1a of a transparent substrate 1 is produced. In such a case, the adhesive layer 3 consists of an adhesive of which the curing rate changes according to the irradiation quantity of electromagnetic radiations. The dummy transparent substrate 4 is arranged on the information signal recording surface 1a of the transparent substrate 1 respectively via the reflection layer 2 and the adhesive layer 3. Next, a mask 11 for masking the 'watermarks' 11a is arranged on the one surface side of the dummy transparent substrate 4 not facing the adhesive layer 3 and thereafter, the irradiation quantity of the electromagnetic radiations is changed according to the specific shape and the inside of the adhesive layer 3 is irradiated with such electromagnetic radiations via the mask 11, by which recording is executed so as to change the position of the reflection layer 2 corresponding to the position of the specific shape from the position of the reflection layer 2 not corresponding to the position of the specific shape. |
