| 摘要 |
PURPOSE:To obtain an optical disk which enables the lowering of variations in reflection factor per disk while reducing the unevenness of the reflection factor within the disk regardless of any unevenness in the thickness of each thin film composing the optical disk and changes in the thickness for each disk. CONSTITUTION:In an optical disk which has a first protective layer, a recording layer, a second protective layer and a reflection layer formed sequentially on a substrate, changes in the reflection factor of the optical disk with respect to changes in the thickness of thin film layers are shown in a graph with an amplitude and a cycle fixed. At least one of the thin film layers is made less (A1) in thickness or is set (A2-A5) to a thickness value or a value therenear so that the reflection factor in the above graph reaches the maximum value Ttop or the minimum value Rbot. The enables the reflection factor difference to be suppressed to + or -1%, for example, as given when the thickness changes by 5%. |
