OPTICAL DISK

摘要

An optical disk comprising a substrate, a recording layer, and a protective layer. A laser beam is applied to the protective layer. The substrate has a diameter of more than 50 mm. The recording layer is formed on the substrate. The protective layer is formed on the recording layer and is thinner than the substrate. A recording or reproducing laser beam is applied to the protective layer. The total thickness of the optical disk is more than 0.7 mm.