| 摘要 |
PURPOSE:To provide a diffraction grating adjustment position detector which can detect a fact that a subspot is set on the same track as a main spot even if a subspot signal does not contain a wide band component. CONSTITUTION:When the diffraction grating of an optical pickup of a 3-spot system is adjusted, a main spot signal is delayed by a fixed time and a detection pulse of the prescribed detection window width is produced by a detection window circuit 34. Then the maximum value generating time of a subspot signal is detected in the detection window and a fact that the subspot is set on the same track as a main spot is detected. |
