| 摘要 |
PURPOSE:To prevent quantity-of-light reduction by luminous flux branching and to improve the carrier wave versus noise ratios (C/N) of a regenerative signal by selectively switching optical paths in accordance with the contents of a reflected light from an optical disk. CONSTITUTION:Laser light from a laser diode 1 passes through a collimator lens 2 and radiates an optical disk 6 through a beam splitter 4. Reflected light is reflected at the beam splitter 4 and is made incident on a polarized beam splitter 30 through an electro-optical element 20. At this time, when the data signal part of a recording track is scanned, a switch 21 is turned off, the light to transmit the element 20 is made to transmit the splitter 30 and light-received by a photodetector 8. On the other hand, when a servo signal part is scanned, the switch 21 is turned on and the plane of polarization of the laser light is turned to 90 deg.. Thus, the splitter 30 reflects the laser light in a right-angle direction and light-receiving is executed by a photodetector 12. Consequently, the luminous flux does not branch and the C/N is improved. |
