| 摘要 |
PURPOSE:To prevent the disturbance and to properly discriminate the intensity of a laser beam by providing a face, which totally reflects a part of the luminous flux of the laser beam for monitor, and a photodetector and inclining the normal of the reflection face to the incidence direction. CONSTITUTION:The reflected light from the recording face of a magneto-optical disk 14 which is reflected by a separating face 12a passes a half-wave plate 15 and has the plane of polarization rotated at 45 deg.. The signal light which passes the plate 15 is made incident on a beam splitter 16 and is separated into the component transmitted through the separating face 16 and the component reflected by it. The reflected signal light passes a condenser lens 40 and is made incident on a photodetector 41, whose light reception face is divided in the tracking direction, to detect the tracking error. The p-polarized light component of the signal light transmitted through the face 16 has the focusing error detected by a photodetector 23. Only the part made incident on the element 40 is reflected to the detecting optical system side; and therefore, light is not made incident on the other photodetectors by inclining the normal of the reflection face to incident light, and the disturbance is eliminated to properly discriminate the intensity. |
