| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an optical disk suitable for high density recording by regulating the thickness of an effective light transmission layer and the range of the refractive index of the light transmission layer in a next generation optical disk etc. and to provide its recording and playing-back device. <P>SOLUTION: In the optical disk 51 consisting of a substrate 52, an information recording layer 53, an intermediate layer 54, an information recording layer 55 and a cover layer 56, the thickness t of the cover layer 56 is set to be f(n)-t1 or more by using a function f(n) which is related to the refractive index n of the cover layer 56 and is no constant and constants t1 and t2 determined based on the maximum permissible value of aberration in the light transmission layer consisting of the cover layer 56, the information recording layers 53 and 55 and the intermediate layer 54 which can be corrected by a spherical aberration correcting mechanism 24 that an optical disk device has and the total thickness of the cover layer 56, the intermediate layer 54 and the information recording layer 55 except the information recording layer 53 the nearest to the substrate 52 is set to be f(n)+t2 or less. <P>COPYRIGHT: (C)2004,JPO&NCIPI |
