| 摘要 |
PURPOSE:To record a synchronous mark which can surely be identified from a data mark and which can easily be detected at a short mark length. CONSTITUTION:The synchronous mark 26 is constituted by two synchronous pits 26a formed in the direction of a track width and the data mark is constituted by a single data pit 28. The two synchronous pits 26a are arranged so that the shortest distance of the outline of the pit is shorter than the distance in the direction of the track width of a beam spot 24 for setting the beam spot 24 to simultaneously irradiate the both synchronous pits 26a. The diameter of the synchronous pit 26a is formed to be equal to that of the data pit 28. |
