| 摘要 |
PURPOSE:To supply an optical disk superior in safety by preventing the danger that an operator's eye is damaged, by preventing laser beam light from leaking out by fitting a protective disk to the opposite surface of the metal coating layer of a circularly formed substrate. CONSTITUTION:On the surface of substrate 22 of optical disk 21, metal coating layer 26 of bismuth, for example, is formed by vapor deposition and this metal coating layer 26 is irradiated with laser beam light to record information in a track shape according to the rotation of disk 21. The reverse surface of substrate 22, on the other hand, is fitted with protective disk 27 of the same outer diameter with said glass disk 22. This disk 27, which is enough excellent in absorbance as to a laser beam to prevent its penetration, is formed of a synthetic resin material so that even if substrate 22 is broken down, the shape of the disk can be maintained. Here, even if a flaw is made in metal coating layer 26 and laser beam light l is supplied from below, it never penetrates upward by being absorbed by protective disk 27. |
