| 摘要 |
PURPOSE:To attain stable servo by cancelling an offset component which is generated in each error signal due to reflection of optical parts or the like on an optical disc. CONSTITUTION:The offset component of each detected error signal generated by stray light or the like in an optical device is not concerned with signal recording and reproducing and is proportional to the quantity of light emitted from a light source 1. A part of incident light 2 from the light source 1 is separated directly by a beam splitter 4 provided in the optical path and is detected by the second photodetector 13, and the output is synthesized with a focus error signal 10 and a tracking error signal 11 respectively. Thus, offset is cancelled and thus the system can cope with the influence of change of the reflection factor on the surface of the disc or the like.
|
