| 摘要 |
PURPOSE:To prevent the reduction in a signal level even when a spatial frequency is increased by providing a minute hole in the vicinity of a point in conjugation with a light collection point on a recording face of a recording medium on an optical path of a light made incident on a photodetection means. CONSTITUTION:A shield plate 9 having a minute through hole 8 is arranged in the vicinity of a point in conjugation with a point in which an information detection light spot is formed on a recording face of a disk 4 between a beam splitter 2 and a photodetector 5. Thus, even if a spatial frequency gets higher, the reduction in the signal level is prevented and the high density optical disk is attained. Moreover, the crosstalk between adjacent tracks is reduced. |
