| 摘要 |
PURPOSE:To detect a shift in track-directional position, a shift in focus- directional position, etc., at the same time and to reduce the size of a waveguide type optical head by providing parallel waveguides on both side of a waveguide for an optical pickup in parallel and providing slanting waveguides which cross the tips of the waveguides in a V shape to the projection end sides of the parallel waveguides. CONSTITUTION:A laser light source LD and a photodetector 13 are connected to the pickup waveguide 17 in the center, and photodetectors 18 and 19, and 20 and 21 are connected to the other-end sides of the parallel waveguides A1 and A2, and slanting waveguides B1 and B2. The photodetectors 18 and 19 are connected to an arithmetic circuit 22 and the output values of both photodetectors 18 and 19 are compared to detect the track-directional position shift of an optical head. Further, the photodetectors 18 and 19, and 20 and 21 are connected to another arithmetic circuit 23 and the output values of the photodetectors 18 and 19 are compared with the output values of the photodetectors 20 and 21 to detect a shift in focus position. |
