| 摘要 |
PURPOSE:To improve S/N and to stabilize focus servo, by providing a polarizing means which has larger reflectance of the direction S than that of the direction P to the optical path of the reflected light for reading of a photomagnetic recorder/reproducer. CONSTITUTION:The laser beam given from a laser light souce 1 is reflected by a vertical magnetized film 7a of a disk 7 via a diffraction grating 2, lens 3, polarizing prism 17, mirror 5 and lens 6. The reflected light includes the revolution of a polarized wave surface corresponding to the digital signals already recorded and passes through the lens 6, the mirror 5 and polarizing prisms 17 and 18. A part of the reflected light is made incident to an optical detector 13 via a cylindrical lens 11 and then turned into a focus signal; while the other part of the light is made incident to an optical detector 14 via a photodetector 10 and delivers reading signals. For the prisms 17 and 18, the reflectance of the direction P is set larger than that of the direction S. Thus the revolution is amplified for the polarized wave surface including the returning beams. Thus the focus servo is stabilized and at the same time the S/N is improved. |
