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US 6,660,985 B2Granted
Optical pick-up device and objective lens therefor
AssigneeKonica Corporation
InventorKoji Honda
Life of this patent
Estimating the term…
Abstract
In an optical pickup apparatus provided with a first light source; a second light source; a converging optical system having an objective lens provided with a diffractive section, and an optical detector, the optical detector comprises a central light receiving section to detect a focusing condition and a peripheral light receiving section to detect a tracking error, and when information is reproduced from or recorded in the second optical information recording medium, a reflected light flux of the second light flux reflected from or a transmitted light flux of the second light flux transmitted through the second optical information recording medium is irradiated so as to cover the entire surface of the peripheral light receiving section.
Claims20
An optical pickup apparatus for reproducing information from or recording information in at least two kinds of optical information recording medium, comprising:
- a first light source to emit a first light flux having a first wavelength λ1
- a second light source to emit a second light flux having a second wavelength λ2 (λ2>λ1);
- a converging optical system having an objective lens provided with a diffractive section, to converge the first light flux emitted from the first light source through a transparent base board of a first optical information recording medium onto a recording surface and to converge the second light flux emitted from the second light source through a transparent base board of a second optical information recording medium onto a recording surface;
- an optical detector to receive a reflected light flux and/or a transmitted light flux from the first and second optical information recording medium;
- wherein the first light flux is irradiated to reproduce information from or to record information in the first optical information recording medium including a transparent base board having a thickness of t1 and the second light flux is irradiated to reproduce information from or to record information in the second optical information recording medium including a transparent base board having a thickness of t2 (t2>t1);
- wherein when a numerical aperture NA1 is a numerical aperture at an image side of the objective lens and necessary to reproduce information from or record in the first optical information recording medium, the converging optical system converges the first light flux on the information recording surface of the first optical information recording medium within the numerical aperture NA1 on a condition that wavefront aberration is 0.07λ1 rms or less, and when a numerical aperture NA2 (NA2<NA1) is a numerical aperture at an image side of the objective lens and necessary to reproduce information from or record in the second optical information recording medium, the converging optical system converges the second light flux on the information recording surface of the second optical information recording medium within the numerical aperture NA2 on a condition that wavefront aberration is 0.07λ2 rms or less,
- wherein the optical detector comprises a central light receiving section to detect a focusing condition and a peripheral light receiving section to detect a tracking error, and when information is reproduced from or recorded in the second optical information recording medium, a reflected light flux of the second light flux reflected from or a transmitted light flux of the second light flux transmitted through the second optical information recording medium is irradiated so as to cover the entire surface of the peripheral light receiving section.
4 more elements
An objective lens for use in an optical pickup apparatus for reproducing information from or recording information in at least two kinds of optical information recording medium, the optical pickup apparatus comprising:
- a first light source to emit a first light flux having a first wavelength λ1;
- a second light source to emit a second light flux having a second wavelength λ2 (λ2>λ1);
- a converging optical system having the objective lens provided with a diffractive section, to converge the first light flux emitted from the first light source through a transparent base board of a first optical information recording medium onto a recording surface and to converge the second light flux emitted from the second light source through a transparent base board of a second optical information recording medium onto a recording surface;
- an optical detector to receive a reflected light flux and/or a transmitted light flux from the first and second optical information recording medium;
- wherein the first light flux is irradiated to reproduce information from or to record information in the first optical information recording medium including a transparent base board having a thickness of t1 and the second light flux is irradiated to reproduce information from or to record information in the second optical information recording medium including a transparent base board having a thickness of t2 (t2>t1);
- wherein when a numerical aperture NA1 is a numerical aperture at an image side of the objective lens and necessary to reproduce information from or record in the first optical information recording medium, the converging optical system converges the first light flux on the information recording surface of the first optical information recording medium within the numerical aperture NA1 on a condition that wavefront aberration is 0.07λ1 rms or less, and when a numerical aperture NA2 (NA2<NA1) is a numerical aperture at an image side of the objective lens and necessary to reproduce information from or record in the second optical information recording medium, the converging optical system converges the second light flux on the information recording surface of the second optical information recording medium within the numerical aperture NA2 on a condition that wavefront aberration is 0.07λ2 rms or less,
- wherein the optical detector comprises a central light receiving section to detect a focusing condition and a peripheral light receiving section to detect a tracking error, and when information is reproduced from or recorded in the second optical information recording medium, a reflected light flux of the second light flux reflected from or a transmitted light flux of the second light flux transmitted through the second optical information recording medium is irradiated so as to cover the entire surface of the peripheral light receiving section.
4 more elements
Dependencies are inferred from the claim text.