| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical disk which is free of deterioration in recording and reproducing quality and is capable of suppressing a cross erase. SOLUTION: At least a first dielectric layer 22, a recording layer 23 of a phase transition type and a second dielectric layer 24 are laminated on a transparent substrate 21 in such a manner that the respective ratios Ds/Df, ts/tf and ds/df of the average film thicknesses Df, tf and df of the first dielectric layer, recording layer and second dielectric layer formed in the groove parts and the flat parts of land parts and the average film thicknesses Ds, ts and ds of the first dielectric layer, recording layer and second dielectric layer formed in the side wall position between the groove parts and the flat parts the land parts and satisfy at least one relation of ts/tf>Ds/Df and ts/tf>ds/df. |
