| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain a satisfactory push-pull signal capable of accurately performing tracking control and the like by optimizing a shape (groove depth, groove width) of a groove used for tracking. <P>SOLUTION: In the optical disk having a substrate 14 having pre-grooves 12 formed in one principal surface thereof, optically functional layers including at least one recording layer formed on the principal surface of the substrate 14 and a light transmission layer disposed and formed so as to cover the optically functional layers, a half value width (the width of the pre-groove at a position of 1/2 of depth h of the pre-groove 12) of the pre-groove of the substrate 14 is 120 to 200 nm and the depth h of the pre-groove 12 is 30 to 60 nm. <P>COPYRIGHT: (C)2007,JPO&INPIT |
