| 摘要 |
PURPOSE:To stabilize the characteristic of tracking servo and to reproduce a signal with a high C/N, by performing the reproduction of the signal by using a dispersive optical device with a large extinction ratio such as a Wollaston prism, etc. CONSTITUTION:A laser beam emitted from a semiconductor laser 11 is dispersed to three beams, and they are projected on a disk D. Return light reflected on the disk D is introduced to a signal detecting system 20 on a backward path, and every beam is furthermore dispersed to three beams via the dispersive type optical device 23, and they are distributed to nine beams in matrix shape. By image-forming five beams out of the dispersed beams on a quarterly split photodetector 252 in the center of an octal split optical sensor 25 and a pair of photodetectors 253-256 at both sides, a servo error signal and a MO reproducing signal can be detected corresponding to the differential output. In such a way, magneto-optical head of three-beam system can be simplified and miniaturized, and also, the performance of the characteristic of signal reproduction can be improved more than ever. |
