| 摘要 |
PURPOSE:To select data signal light intensity and tracking signal light intensity independently by providing only a lens and the tip of an optical fiber to a part which moves for data tracking, and arranging a photodetecting element at a desired position. CONSTITUTION:When the projection light spot B from a data signal optical fiber 132 shifts in position from the center of a track 17a, optical fibers 131 and 132 have a difference in the quantity of incident reflected light. Consequently, there is a difference in the quantity of light generated between beam spots A' and C' supplied to photodetecting elements 191 and 193 through demultiplexing optical fibers 181 and 183 branched from the optical fibers 131 and 133 to generate a difference in electric output between the photodetecting elements 191 and 193. For the purpose, the signal of the electric output difference between the photodetecting elements 191 and 193 is inputted to a tracking device 15. The correct data tracking of an optical fiber 132 for data signal transmission is performed by controlling the positions of the optical fibers 131-133 so that the electric output difference between the photodetecting elements 191 and 193 is eliminated. |
