| 摘要 |
PROBLEM TO BE SOLVED: To compensate unbalance between the channels caused in the output of an optical detector by the influence of stray light. SOLUTION: Output levels from light detectors 216, 217 are detected in a state in which focus control of a light spot on an optical disk 201 is defocused and in a state in which focus control is turned on. Also, differential balance of output of the optical detectors 216, 217 is adjusted so that change quantity of an output level of the optical detector at the time of defocus of focus control and an output level of the optical detector at the time of ON of focus control is made to be constant between channels. COPYRIGHT: (C)2004,JPO&NCIPI
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