| 摘要 |
PURPOSE:To enlarge the allowance for tilting in the direction of the tracking or tangential direction and to reduce the amount of cross-talk as output characteristics by tilting the direction of a far-field pattern to the pit string of a disk. CONSTITUTION:The direction of the longer axis of a far-field pattern of a beam irradiated from a semiconductor laser is made to tilt to the bit string 1 on the disk, most desirably, made to be irradiated at an tilting angle of less than 45 deg.. Accordingly, the position at which the smallest beam diameter Wo is obtained for the pit string 1 on the disk is also in a face tilting by theta to the pit string 1. In this face, the beam diameter becomes small. However, the level of strength H2 in the outside zone becomes large. However, as the far-field pattern is tilted to the pit string 1, the distance to adjoining tracks 2, 3 can be made large. The distance becomes maximum when the angle of tilting is 45 deg. and interference with adjoining tracks 2, 3 can be made small. |
