| 摘要 |
PURPOSE:To prevent that the conjunction track point from floating from the zero level of the differential output of a light detecting device which detects two primary beams even to the inclination of a recording medium and the inclination of a light source, and to detect correctly the track dislocation quantity by providing a light flux processing part at the front surface of a buffer layer to hold the light source. CONSTITUTION:In addition to the conventional construction, on a front surface 200 of a buffer layer 3, a reflecting preventing layer 400 is newly added as the light flux processing part, and thereby, the light reflected from an LD side to a point C again comes to be essentially the light only to pass through the AGBGAGC channel. Thus, by making low the reflecting ratio of the front surface of the buffer layer, the light to make incident on the primary light on the disk again can come to be only one, and the interference effect conventionally caused by the phase dislocation due to the inclination of the disk and the inclination of the edge surface of the LD side between plural reincident light beams can be prevented. Consequently, by the differentiation of the light detecting device element, when the track dislocation is detected, the floating from the zero level of the conjunction track point can be eliminated. |
