| 摘要 |
The present invention provides an optical disc which is constituted by a substrate, a recording layer, and a protection layer and is irradiated with a laser beam from the protection layer side. The optical disc has the substrate whose diameter is greater than 50 mm, the recording layer provided on the substrate, and the protection layer which is layered on the recording layer and thinner than the substrate and on which a recording or reproducing laser beam is incident. The total thickness of the optical disc is 0.7 mm or more.
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