| 摘要 |
PURPOSE:To extract a magneto-optical signal without deterioration and to improve the CNR (carrier.noise ratio) by providing an adjustment means in the direction of rotation to a 1/2 wavelength plate. CONSTITUTION:The 1/2 wavelength plate 7 is adhered to a holder 14 provided with an adjustment hole and turned by an adjustment jig, and the reflected light whose direction of polarization is tilted by 45 deg. by the 1/2 wavelength plate 7 and whose phase of the P and S polarized light is shifted by 180 deg. is made incident in the polarized beam splitter 8 having a function of analyzer, where the light is separated into the P and S polarized components. Then a P polarized light beam is formed on a 4-split photodetector 11, a focus error signal is detected and a S polarization beam is formed by a 1/2 split photodetector 13 to detect a tracking error signal. Then the information signal is extracted by the differential detection method. Thus, the phase deviation is reduced and the reduction in the CNR is prevented. |
