| 摘要 |
<p>An optical feedback to a laser light source when using a 1/4 wavelength board of narrow band is reduced. An optical pickup device is provided with a laser light source unit for selectively emitting laser light with a first and a second wavelengths, an objective lens for focusing on an optical recording medium the laser light emitted from the laser light source unit, a light detector for detecting the laser light reflected from the optical recording medium, a light separating unit for guiding to the objective lens the laser light emitted from the laser light source unit while guiding to the light detector the laser light reflected from the optical recording medium, and a 1/4 wavelength board for converting the first wavelength laser light incident via the light separating unit from linearly-polarized light to circularly-polarized light while converting the second wavelength laser light incident via the light separating unit from linearly-polarized light to elliptically-polarized light, wherein the second wavelength laser light emitted from the laser light source unit is incident to the light separating unit as a first linearly-polarized light, and the light separating unit shifts the phase of the second wavelength laser light which is incident via the 1/4 wavelength board such that the component of the first linearly-polarized light is reduced.</p> |
