| 摘要 |
PROBLEM TO BE SOLVED: To provide a two-layer optical disk capable of performing recording/ reproducing in an existing optical disk device. SOLUTION: An optical disk 32 is made to have a thickness of about 1.8 mm as a whole by sticking the backsides of a CD layer 34 having a thickness of about 1.2 mm and a high-density layer 36 having a thickness of about 0.6 mm to each other. In the center of the CD layer 34, a center hole 44 having a diameter of 15 mm is formed. In the center of the high-density layer 36, a center hole 52 having a large diameter is formed. Disk clamping is performed in the part of the CD layer 34 having a thickness of about 1.2 mm in the center hole 52 of the high-density layer 36. |
