| 摘要 |
PURPOSE: To record/reproduce optical disks having different track pitches by a common optical head. CONSTITUTION: Tracking error signals for narrow track pitches and standard track pitches are obtained from two pairs of four auxiliary light beams 3', 3" and 103', 103" based on ± first-order and ± second-order diffracted light beams of a diffraction grid 24 installed immediately before a semiconductor laser 1. Thus, tracking is performed for an optical head corresponding to each of the narrow and standard track pitches. |
