| 摘要 |
An apparatus for focusing a light beam onto a recording medium comprising: a light source (201) generating a light beam which is modulated by a thin-film PLZT modulator array (204); a beamsplitter (203) used to direct the modulated light beam to an objective lens (206) which focuses the modulated light beam onto the recording medium (207); a focus detector (208) for receiving a light reflected back from the recording medium (207) and for generating an electrical signal corresponding to a degree of focus of the modulated light beam in reference to the recording medium (207); and a focus actuator (210) placed in close proximity to the modulator. By moving the focus actuator (210) in an optical axis according to the electrical signal generated by the focus detector (208), a high bandwidth servo loop can be closed about the focal position.
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