| 摘要 |
An interference-type optical pickup, an optical information detection method, and an optical information recording and reproducing apparatus, which allow easy adjustment of a path difference between two lights, have a high signal amplification effect and are suitable for size reduction of an optical system, are provided. A signal light reflected from an optical disk and a reference light branched from the same light source and guided into detectors without being projected onto the optical disk are caused to interfere with each other on detectors. Detector outputs in four interference states in which phase relationships between the reference light and the signal light are different from each other by degrees are simultaneously obtained and calculated. Accordingly, a readout signal RF that is always stable and amplified with high quality is obtained even when an optical path changes due to disk undulations. The four detector outputs are simultaneously obtained by use of four quadrant photo detectors, and are calculated, to thereby also obtain a servo signal.
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