| 摘要 |
An optical pickup includes a light source, an objective lens, light detectors, an optical system, and an error-signal generator. The light-receiving surface of at least one of the light detectors has a width extending in a first direction corresponding to a radial direction of an optical disk, and is formed by first to sixth photoreceptors arrayed along the first direction. The first and second photoreceptors, the third and fourth photoreceptors, and the fifth and sixth photoreceptors are disposed axisymmetrically with respect to a center line extending perpendicularly to the first direction. The error-signal generator generates a focus-error signal using a sum signal of detection signals output from the first and second photoreceptors or a sum signal of detection signals output from the first to fourth photoreceptors in a light spot size method, and generates a tracking-error signal using the other sum signal in a differential compensate push-pull method.
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