Optical disk having a high-density recording layer and a low density recording layer

摘要

The present invention relates to an optical disk having a high density information recording layer for recording information at high density and an information recording layer which stores information at a density lower than the high density information recording layer. The optical disk also has a light incidence surface which is formed on the opposite side from the second information recording layer, where, the thickness of the disk from the light incidence surface to the second information recording layer is made the same as the thickness of the disk.