| 摘要 |
PROBLEM TO BE SOLVED: To improve recording density and a reproducing degree of a signal by making a sheet of disk a double-layer, providing a recording layer in each layer and recording the signal. SOLUTION: The optical disk is constituted of an upper layer body 3 having an upper side recording layer 2, a lower layer body 5 having a lower side recording layer 4 and an intermediate layer 6 arranged between the upper layer body 3 and the lower layer body 5. An upper layer signal is recorded on the upper side recording layer 2, and a lower layer signal is recorded on the lower side recording layer 4. Then, light is emitted from the direction of the upper side recording layer 2, and the upper later signal and the lower layer signal are read out. The upper layer signal and the lower layer signal are recorded shifting in the radial direction of the disk. |
