| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical disk capable of always excellently reproducing information with sufficiently low reproducing jitters similarly to the reproducing of information at a standard linear velocity even when information recorded at about twice linear velocity as the standard linear velocity is reproduced. SOLUTION: This optical disk D is obtained by laminating a protective layer 20, a recording layer 30 containing a AgInSbTe compound, a protective layer 40 and a reflection layer 50 on a substrate 10, and when recording and reproducing is performed by switching the linear velocity, the highest linear velocity is about twice as the lowest linear velocity. The composition range of the AgInSbTe compound and the film thickness of the protective layer 20, recording layer 30 and protective layer 40 are determined in such a manner that the change ratio (c) defined by c=(a-b)/a, wherein (a) is the reflectance of the reflected light from the recording layer 30 at the lowest line velocity and (b) is the reflectance of the reflected light form the recording layer 30 at the highest line velocity, ranges -0.03<=c<=0.03 when the information initially recorded in the recording layer 30 is reproduced and that the change rate c after recording is repeated by 1000 times ranges -0.05<=c<=0.05. |
