| 摘要 |
PURPOSE:To decrease the pitch of pits and to increase the information recording density by making the edge at both ends in the pit arranging direction orthogonal to the arranging direction. CONSTITUTION:A pre-group 2 is formed on a base 1 in concentrical or spiral shape and pre-pits 6 are arranged intermittently along the pre-group 2. Edges 6A, 6B at both ends of the arranging direction of the pre-pits 6 are formed to be made orthogonal in the arranging direction X and the pre-pits 6 are formed in a rectangular shape. Thus, the pitch P2 is decreased regardless of the width W of the pre-pits 6 and the information recording density is increased. |
