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US 8,264,939 B2Granted
Optical pickup apparatus
AssigneesSanyo Electric Co., Ltd., Sanyo Optec Design Co., Ltd.
InventorsTohru Hotta, Ryoichi Kawasaki
Life of this patent
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Abstract
An optical pickup apparatus includes: a laser diode configured to emit a laser beam; and an objective lens configured to condense the laser beam into a laser spot through which a signal recorded on a signal recording layer of an optical disc is read out by the laser beam, the objective lens having formed thereon a lens surface with a second numerical aperture for acting as a lens, which is larger than a first numerical aperture for forming the laser spot.
Claims4
An optical pickup apparatus comprising:
- a laser diode configured to emit a laser beam;
- and
- an objective lens configured to condense the laser beam into a laser spot through which a signal recorded on a signal recording layer of an optical disc is read out by the laser beam,
- the objective lens including a lens surface, a portion of the lens surface having a first numerical aperture used for forming the laser spot,
- the lens surface formed with a second numerical aperture for acting as a lens, the second numerical aperture larger than the first numerical aperture in consideration of manufacturing tolerance of the objective lens, and
- the lens surface having formed thereon an anti-reflection coating which determines a transmittance of the laser beam so that the transmittance of the laser beam becomes maximum at a position of the second numerical aperture, wherein the first numerical aperture used for forming the laser spot is 0.85, and the second numerical aperture is at least 0.87.
3 more elements
An optical pickup apparatus comprising:
- a laser diode configured to emit a laser beam;
- and
- an objective lens configured to condense the laser beam into a laser spot through which a signal recorded on a signal recording layer of an optical disc is read out by the laser beam,
- the objective lens including a lens surface, a portion of the lens surface used for forming the laser spot,
- the lens surface formed with a full numerical aperture for acting as a lens, the full numerical aperture larger than a highest numerical aperture used for forming the laser spot in consideration of manufacturing tolerance of the objective lens, and
- the lens surface having formed thereon an anti-reflection coating which determines a transmittance of the laser beam so that the transmittance of the laser beam becomes maximum at a position of the full numerical aperture, wherein the highest numerical aperture used for forming the laser spot is 0.85, and the full numerical aperture is at least 0.87.
3 more elements
Dependencies are inferred from the claim text.