| 摘要 |
PURPOSE:To improve the C/N of a data signal of an information recording and reproducing device. CONSTITUTION:A laser beam outgoing from a semiconductor laser 8 in an optical head 7 is divided into plural diffracted light beams by a diffraction grating 10. A magneto-optical information recording medium 1 is irradiated with a main beam 5, sub beams 6a, 6b among these diffracted beams. These beams reflected from the magneto-optical information recording medium 1 are returned into the optical head 7 again and planes of polarization are rotated by 45 deg. by a 1/2 wavelength plate 13 and after astigmatism is imparted by a cylindrical lens 15, the beams are divided into a P polarization component 17 and a S polarization component 18. The P polarization component and the S polarization component of the main beam 5 are received by photodetectors 19a, 19b of a non-divided type respectively and used for the detection of the data signal. The P polarization components of the sub beams 6a, 6b are received by the photodetectors 20a, 20b of a quadripertite type and used for the detection of a focus error signal and a tracking error signal. |
