公开(公告)号：DE69219163T2

公开(公告)日：1997-08-28

申请号：DE69219163

申请日：1992-01-08

Applicant: SONY CORP

Inventor： HIGASHIHARA TERUAKI ,  ISHII YOJI ,  OHSATO KIYOSHI

IPC: G02B27/28 ,  G11B7/00 ,  G11B7/0045 ,  G11B7/135 ,  G11B7/1362 ,  G11B7/1365 ,  G11B11/10 ,  G11B11/105

Abstract: Laser light beams for first and second laser light sources (11, 12) having different wavelengths are synthesized by a dichroic mirror (16) and irradiated on a magneto-optical disc (20) forming a recordable disc, and the reflected light is separated into the laser light of the first and second wavelengths. In respect of the laser light of the first wavelength, the phase difference between the P and S-polarization components produced by the dichroic mirror 16 is compensated by a phase compensation plate (32), and the P and S-polarization components are separated from each other by a polarization beam splitter (36) so as to be received by photodetector elements (37, 38). The dichroic mirror (16) used in such the difference between the minimum transmittance in a working range of the laser light of the first wavelength and the maximum transmittance in a working range of the laser light of the second wavelength is 90% or higher for reducing changes in the phase difference between the P and S-polarization components.

公开(公告)号：DE69219163D1

公开(公告)日：1997-05-28

申请号：DE69219163

申请日：1992-01-08

Applicant: SONY CORP

Inventor： HIGASHIHARA TERUAKI ,  ISHII YOJI ,  OHSATO KIYOSHI

IPC: G02B27/28 ,  G11B7/00 ,  G11B7/0045 ,  G11B7/135 ,  G11B7/1362 ,  G11B7/1365 ,  G11B11/10 ,  G11B11/105

Abstract: Laser light beams for first and second laser light sources (11, 12) having different wavelengths are synthesized by a dichroic mirror (16) and irradiated on a magneto-optical disc (20) forming a recordable disc, and the reflected light is separated into the laser light of the first and second wavelengths. In respect of the laser light of the first wavelength, the phase difference between the P and S-polarization components produced by the dichroic mirror 16 is compensated by a phase compensation plate (32), and the P and S-polarization components are separated from each other by a polarization beam splitter (36) so as to be received by photodetector elements (37, 38). The dichroic mirror (16) used in such the difference between the minimum transmittance in a working range of the laser light of the first wavelength and the maximum transmittance in a working range of the laser light of the second wavelength is 90% or higher for reducing changes in the phase difference between the P and S-polarization components.