| 摘要 |
PURPOSE:To improve the weather proof by providing a reflecting layer only to an intermediate part between an outer circumferential part and an inner circumferential part of a torus base and providing a protection layer so as to cover the entire face. CONSTITUTION:An Al alloy including Ta with excellent corrosion proof is used for a reflecting layer and provided only to the intermediate part of both the circumferential part and a protection layer whose thickness (after curing) is 1 - 20mu is provided to the entire face. Thus, a long period storage optical disk with excellent weather proof and withstanding the use of tight condition is obtained. |
