| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical disk having a difference in Ag alloy (AgAlBi) compositions between a semi-transmissive film of a surface layer and other layers and to provide an optical disk device using the optical disk. <P>SOLUTION: The multilayer optical disk having three or more recording layers is constituted so as to reduce the ratio of silver and increase the ratio of aluminum in the compositions of reflection film materials which constitute respective layers, respectively, toward the depth when viewed from a light incident surface side. Thereby, durability and reproduced signal characteristics are improved by enhancement in adhesion of films and overall reflectance of the disk is increased (a high SN ratio) by enhancement in transmittance of the surface layer. <P>COPYRIGHT: (C)2009,JPO&INPIT |
