Optical pickup device
AssigneeSharp Kabushiki Kaisha
InventorsMasaru Ogawa, Tetsuo Saeki
Life of this patent
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Abstract
There can be obtained a miniaturized, 3-beam optical pickup device using a polarization separating prism of an inexpensive material and capable of reliably detecting light of a signal. The present pickup device includes an optical element having the first, second and third members, and having a first boundary surface receiving light from a semiconductor laser and reflecting and directing it toward a collimator lens, and also transmitting light reflected by an MO disc and directing it toward a photodetector, and a second boundary surface separating polarized light of light transmitted through the first boundary surface.
Claims17
An optical pickup device comprising:
- a light source;
- a lens arranged on an optical path extending from said light source to a magneto-optical recording medium;
- an optical element arranged on an optical path extending from said light source to said lens, and separating polarized light of light reflected by said magneto-optical recording medium;
- and
- a photodetector detecting light separated by said optical element, said optical element including
- a first member formed of an isotropic optical medium, receiving light from said light source and reflecting the received light to direct the reflected light to said magneto-optical recording medium,
- a second member formed of an isotropic optical medium and arranged adjacent to said first member, further passing the light reflected by said magneto-optical recording medium and having passed through said first member, and
- a third member formed of an anisotropic optical medium and arranged adjacent to said second member, separating via a boundary surface of said second and third members the light having passed through said second member, and directing the separated light to said photodetector.
An optical pickup device comprising:
- a light source emanating a beam of light;
- light collecting means receiving the beam of light emanating from said light source, and collecting the received beam of light on a magneto-optical recording medium;
- an optical element formed of an isotropic optical member formed of an isotropic optical medium and an anisotropic optical member formed of an anisotropic optical medium, arranged between said light source and said light collecting means, said isotropic and anisotropic optical members having a boundary surface therebetween serving as a polarization separating surface;
- a photodetector receiving light reflected by said magneto-optical recording medium and directed thereto;
- and
- a first diffraction element arranged between said optical element and said photodetector to receive and direct light from said optical element to said photodetector, said first diffraction element having a hologram pattern compensating for a wave aberration introduced when said boundary surface refracts light.
Dependencies are inferred from the claim text.