| 摘要 |
<P>PROBLEM TO BE SOLVED: To properly set a signal value for deciding control constant of focus servo even when the focus servo is performed by an optical disk that has irregular amount of wobble. Ž<P>SOLUTION: An optical device is provided with: an actuator 31 moving the focal point of a beam emitted to an optical disk 1 by driving an objective lens 32; a photodetector 4 detecting the beam reflected from the optical disk 1 and outputting it as a detection signal; and a servo control part 8 controlling the focal point of the beam from the detection signal of the photodetector 4 by driving the actuator 31. The servo control part 8 has a focus servo part 80 for inputting the detection signal of the photodetector 4 and driving the actuator 31 so that the beam is in focus on the basis of the predetermined control constant, and an initializing part 90 for deciding the control constant from the detection signal when the objective lens 32 is located within a predetermined range when the detection signal of the photodetector 4 is in focus. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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