| 摘要 |
An optical pickup for reading information recorded on a recording surface of an optical information storage medium such as a compact disc or a laser video disc has a light beam source for emitting a linear light beam, and an optical system including an objective lens for converging the linear light beam as a linear image on the recording surface and collecting and emitting a light beam reflected from the recording surface. A focus control device includes a parallel flat glass plate for refracting the reflected light beam from the optical system, a photodetector having a plurality of photosensitive surfaces for photoelectrically converting the light beam applied thereto from the parallel flat glass plate into a plurality of respective detected signals, an error signal generator for processing the detected signals from the photodetector into a focus error signal indicative of whether the linear image is focused on the recording surface at the focal point of the objective lens, and an actuator responsive to the focus error signal for controlling the objective lens positionally with respect to the optical information storage medium to focus the linear image on the recording surface.
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