| 摘要 |
<p>PURPOSE: To substantially decrease access time by correcting focusing and tracking direction errors due to an eccentricity of an optical disk by driving only a corrective optical system. CONSTITUTION: A laser beam emitted from a laser diode 1 passes through a focusing correction part, a corrective optical system 5, 6, 7, in order, and reaches a prism 8. This prism 8 makes a scan by the beam which has a different diameter ratio of the scanning direction to the rotational direction of the disk, and the beam is deflected by a mirror 9 and a rotary mirror 10, an optical scanning device, being reflected by a thick mirror 12, and the focus in the scanning direction is converged on a expected track on the optical disk 11, while the focus orthogonal to the scanning direction is converged on the optical disk 11 through cylindrical objective lens 13. In this case, the focusing correction is performed by driving cylindrical lenses 6 and 7. Thus, since the whole optical head does not move but the optical scanning device operates scanning to seek a track by the beam, the accessing is accelerated.</p> |
