| 摘要 |
In an optical information storage an retrieval system, the tracking and focus signals have, in the past, been generated by directing radiation beams from each section of a dual half aperture prism to spatially separated dual element sensors and processing the signals from the pair of dual element sensors. In order to reduce cross-talk between the focusing and tracking signals, a radiation beam which has interacted with the optical storage medium is divided into two portions. The first portion of the radiation beam is directed to a dual prism and the radiation beam from each portion of the prism is applied to a different dual sensor. However, the dual half aperture prism divides the radiation beam which has interacted with the storage medium along a plane perpendicular to the projection of the optical storage medium track being monitored. The focusing signal is derived from this pair of dual element sensors. The second portion of the radiation beam which has interacted with the optical storage medium is applied to a third dual element sensor, the third dual element sensor being divided to receive radiation defined by a plane parallel to the track on the optical storage medium being monitored. The third dual element sensor generates the tracking signal. This technique for generating the tracking and the focusing signals reduces the cross-talk between the two signals.
|
