| 摘要 |
PURPOSE:To reproduce desired information in good order while tracking said information even if a rotary disk is vibrated due to disturbance by polarizing a laser beam condensed to a disk in the direction crossing a track, and polarizing the laser beam by a detecting signal relating to a tracking state containing in an output of a detecting signal of reflected light from the disk. CONSTITUTION:An optical deflector 10 deflects a microspot 9 toward the outside of a disk 1, namely, + side, and two signals 31, 32 appear in a photodetector 14. A pulse counter 13 gives a command of the optical deflector 10 so that the very small spot 9 is deflected toward the inside of the disk 1. Five signals 33-37 appear in the photodetector 14, and the third signal from the beginning among them, namely, 35 is sampled and inputted to a demodulator 15. When the counter 13 receives five pulses, it gives a command to the optical deflector 10 so that the microspot 9 is deflected to the outside of the disk 1. By repeating in this way, signals 30, 35, 40, 45 and 50 can be fetched from a specified track, for instance, 4. |
