| 摘要 |
PURPOSE:To detect a magneto-optical disk information signal, an amplitude modulation disk information signal, a focus error signal, and a tracking error signal, by converting a light quantity received at six photoreceiving areas in an optical detector to electrical signals, and performing arithmetic operations on the six electrical signals. CONSTITUTION:A light spot A and a light spot B on an optical detector 8 are polarized light intersecting orthogonally with each other, and their light quantities are almost equal. When a disk 5 is a magneto-optical disk, a difference between the electrical signals generated by the light spot A and the light spot B is taken. In other words, by taking the difference between the sum of the electrical signals generated at a photoreceiving plane (a), a photoreceiving plane (b), and a photoreceiving plane (c), and the sum of those generated at a photoreceiving plane (d), a photoreceiving plane (e), and a photoreceiving plane (f), the magneto-optical disk information signal can be obtained. When the disk 5 is an amplitude modulation disk, the amplitude modulation disk information signal can be obtained by taking the sum of all of the light quantities received at the optical detector 8. |
