| 摘要 |
PURPOSE:To simplify the device by obtaining the tracking control signal indispensable for optical reproduction simultaneously with optical reproduction of the information from an information structural medium by scannable radiation detecting elements consisting of plural pieces. CONSTITUTION:The light beam 20 from a light source is derived to an objective lens system voice coil 22 by a tracking mirror 21, and is converged onto an information structural medium 23. The light transmitted through the medium 23 is conducted to a radiation detector 24, by the output whereof the information from the medium 23 and the tracking system control signal are obtained. In the figure viewing the detector 24 from an X direction, radiation detecting elements 25 and a track locus 26 are shown. The width B of the radiation detecting element 24 group is a minimum information signal width and is a maximum track pitch width and it is necessary to select a suitable width between these. The number of the elements 25 is determined by the size of each element, and the accuracy of the tracking control signal. |
