| 摘要 |
PURPOSE: To diminish laser light returned as noise to an optical pickup and to enhance signal-to-noise ratio. CONSTITUTION: This joined optical disk consists of an information recording disk 12 with an optical information recording layer and a dummy disk 13 laminated on the rear side of the disk 12 and not subjected to optical information recording. The thickness t1 of the disk 12 is practically about 0.6mm and that t2 of the disk 13 is practically about 0.6mm. The dummy disk 13 is formed from a light absorbing resin material contg. a light absorbing substance such as carbon black. Since laser light passing through the optical information recording layer of the information recording disk 12 is absorbed in the dummy disk 13, the return of the laser light as noise to an optical pickup is prevented and S-N ratio is enhanced. |
