JP2005203004A5 - - Google Patents

Claims (2)

  Three laser light sources having different wavelengths, at least one collimating lens for converting the light emitted from the laser light source into a substantially parallel light beam, and one objective lens for condensing the light emitted from the laser light source on the optical disc; An optical head having an actuator for holding the objective lens and at least one photodetector for detecting reflected light from the optical disc, and having two wavelength-selective polarization holograms mounted on the actuator, One wavelength-selective polarization hologram diffracts a light beam emitted from a laser light source having the longest wavelength among the three laser light sources and made into a substantially parallel light beam by the collimator lens, and has a second wavelength selectivity. A polarization hologram is emitted from a laser light source having the second longest wavelength and is emitted from the collimating lens. An optical head, characterized in that diffracts a light beam substantially is a parallel light beam. The light beam emitted from the first long wavelength laser light source and diffracted from the first wavelength selective polarization hologram, and the second wavelength selective polarization hologram emitted from the second long wavelength laser light source. The more diffracted light beam is divergent light, and the divergent light beam emitted from the first wavelength selective polarization hologram is stronger divergent light than the divergent light beam emitted from the second wavelength selective polarization hologram. 2. The optical head according to claim 1, wherein