| 摘要 |
An optical apparatus for focusing a light beam onto an object having a first track and a second track for guiding the light beam, includes an optical element for directing the light beam onto the object, a detector for detecting the light beam from the object and for generating a tracking-error signal representing a location of the light beam with respect to the first track of the object, and an actuator for moving the optical element from the first track toward the second track. The optical apparatus further includes a generator for generating a track compensating signal corresponding to the distance between the first track and the second track, and an adder for adding the tracking-error signal generated by the detector and the track compensating signal generated by the generator. An adjuster is provided for adjusting the location of the optical element with respect to the second track of the object in response to the signal added by the adder.
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