| 摘要 |
A focus error signal generator device including first and second optical lenses disposed in the respective paths of first and second light beams derived from the return read beam wherein the first and second optical lens have corresponding points of focus, and first and second detectors disposed in the corresponding paths of the first and second light beams located after the points of focus. First and second pinholes are disposed in the corresponding paths of the first and second light beams after the corresponding optical lens and before the corresponding detector, and an electrical differencing circuit having inputs to the first and second detectors and an output to an optical head servo system. A method for focus error signal includes the steps of focussing first and second light beams derived from a return read beam at corresponding first and second points of focus; providing for first and second detectors disposed in the path of corresponding first and second light beams after corresponding first and second points of focus; providing for first and second pinholes in the path of corresponding first and second light beams; and generating a focus error signal related to the difference between the output of the first detector and an output of the second detector. An optical data delivery and detection system comprises a laser source emitting a light beam, an optical head that receives the light beam, optical lenses within the optical head that focus the light beam on an optical storage media, a data detector that receives the light beam on the beam's return path and provides data signals and the focus error generator device described above.
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