| 摘要 |
PURPOSE:To increase recording density by making the magnitude of the track pitch of a recording pit on an optical disk coincide with the radius of the most inside dark ring of a beam spot and simultaneously lowering the reflectance in a land part than the same of a pit part. CONSTITUTION:The luminous intensity distribution 31 of the beam spot formed on the optical disk by an optical pickup device consists of a central part and a large number of a ring shape light distribution around the central part and dark rings with the luminous intensity 0 between the rings are present. The radius of the most inside dark ring is made to coincide with a tracking pitch and simultaneouly the reflectance of the land part 32 is reduced than that of the pit part. Thus, by narrowing a pit width by shifting the pit width where the modulation factor of a light beam by the diffraction of the pit becomes the maximum to a narrow side, cross-talk amount is reduced. Thus, the recording density is increased without changing the plural conditions of the pickup. |
