| 摘要 |
PURPOSE:To narrow the pitch of a track and to reproduce the recorded signal between tracks except the influence of crosstalk by dividing reflected light beams from a disk into approximately two, dislocating the phases of the peripheral parts of both divided reflected light beams, and obtaining a reproduced signal from a synthesized light beam. CONSTITUTION:A light beam 1 emitted from a semiconductor laser 1 of a light source is made into parallel beams by a collimator lens 2, reflected on a polarizing beam splitter 3, transmitted through a lambda/4 plate 4, and after that formed into a light spot on a disk 6 by a diaphragm lens 5. A reflected light beam J from the disk 6 is transmitted through the diaphragm lens 5, the lambda/4 plate 4, and the polarizing beam splitter 3, passed through a half mirror 8, and image-formed on a phase plate 9 by a convex lens 7, a reflected light beam K from the phase plate 9 is reflected on the half mirror 8 and image-formed on a light detector 11 by a detecting lens 10, and the reproduced signal is taken out. While the energy of the peripheral part of the reflected light beam K synthesized in this manner is weaken by optical interference, the energy of the center part of the reflected light beam K is emphasized to the contrary. Thus, the track pitch can be narrowed, and the signal recorded between the tracks can be also reproduced except the influence of the crosstalk. |
