| 摘要 |
PURPOSE:To reproduce information of plural tracks simultaneously, by separating a light flux to diffracted light beams to form signals corresponding to plural tracks on the surface of a disc. CONSTITUTION:The light flux from a laser light source 1 is separated to, for example, 5 diffracted light beams of order 0, order + or -1, and order + or -2 after passing through a diffraction grating 2, and these light beams are condensed through a lens 3, a half mirror 4, and a galvanomirror 5 onto a disc 7 as 5 minute spots by a moving lens 6. Information tracks are preliminarily recorded on the disc at equal pitches and are so arranged that converged minute spots 8 correspond to tracks 9 respectively. The reflection light flux from each track is separated by the mirror 4 and is led to detectors 10-1-10-5 to detect signals from respective information tracks independently. |
