| 摘要 |
An optical-pickup apparatus includes: a laser-light-source unit to emit a laser beam having a first or second wavelength selectively; an objective lens; a photodetector; a light-splitting unit to split first and second laser beams respectively emitted from the laser-light-source unit and an optical-recording medium according to a wavelength and polarization direction, and guide the first and second laser beams to the lens and photodetector, respectively; and a quarter-wave plate arranged between the light-splitting unit and lens to convert the laser beams having the first and second wavelengths incident thereon through the light-splitting unit, from linearly-polarized light to circularly-polarized light and from linearly-polarized light to elliptically-polarized light, respectively, the laser beam having the second wavelength being incident, as first linearly-polarized light, on the light-splitting unit, and the light-splitting unit performing phase shift for the laser beam having the second wavelength incident thereon through the quarter-wave plate to reduce a first-linearly-polarized-light component.
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