| 摘要 |
PROBLEM TO BE SOLVED: To secure high reliability by suppressing the occurrence of secular change to prevent a reproduction defect in an optical recording medium where a optical recording layer and a light transmissive protection layer are laminated on a support baseboard. SOLUTION: A reflection layer 3, a first dielectric layer 4, a recording layer 5 and a second dielectric layer 6 are successively laminated on a non-magnetic disk baseboard 2 so as to obtain the optical recording layer 7. The light transmissive protection layer 9 is arranged through an adhesive layer 8 on one main surface of the disk baseboard 2 where the optical recording layer 7 is formed so that an optical disk 1 is constituted. In the optical disk 1, the material of the disk baseboard 2 and the material of the light transmissive protection layer 9 are decided so that a difference between the water absorption of the disk baseboard 2 and that of the protection layer 9 becomes <=0.1%. Favorably, the material of the protection layer 9 and that of the baseboard 2 are made to be the same kind of material. |
