Patent EP0807928A2 successfully refreshed from Google Patents.
EP0807928A2
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Optical pickup apparatus and objective lens for optical pickup apparatus
Assignee: Konica Minolta Inc
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Filing: 1997-05-07
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Granted: —
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Expires: 2017-05-07
Abstract
Abstract In an objective lens for use in an optical pickup apparatus for converging a light beam from a laser source onto an information recording surface through a transparent substrate of an optical information recording medium, the objective lens includes: a lens surface so that a spherical aberration is discontinuous in a third numerical aperture (NA3) on a side of the optical information recording medium, and the third numerical aperture (NA3) is satisfied the following condition, NA1 > NA3 wherein a first numerical aperture (NA1) is a numerical aperture of the objective lens on a side of a first optical information recording medium having a first thickness (t1), required for obtaining an information from the information recording surface of the first optical information recording medium.
Inventors
- 👤 Katsuya Yagi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 18:38
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/12; G11B7/135; G11B7/1372; G11B7/1374; G11B7/13; G11B7/131; G11B7/1392; G11B7/13922; G11B2007/0003; G11B2007/0006; G11B7/08; G11B7/09; G11B7/0908
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
123 words
An objective lens for use in an optical pickup apparatus for converging a light beam from a laser source onto an information recording surface through a transparent substrate of an optical information recording medium, the objective lens comprising: a lens surface so that a spherical aberration is discontinuous in a third numerical aperture (NA3) on a side of the optical information recording medium, and the third numerical aperture (NA3) is satisfied the following condition, NA1 > NA3 wherein a first numerical aperture (NA1) is a numerical aperture of the objective lens on a side of a first optical information recording medium having a first thickness (t1), required for obtaining an information from the information recording surface of the first optical information recording medium.
Claim 2
Dependent Claim
78 words
The objective lens of claim 1, wherein the third numerical aperture (NA3) is further satisfied the following condition, NA3 ≥ NA2 and wherein the second numerical aperture (NA2) is a numerical aperture of the objective lens on a side of a second optical information recording medium having a second thickness (t2), which is thicker than the first thickness (t1), of transparent substrate, required for obtaining information from the information recording surface of the second optical information recording medium.
Claim 3
Dependent Claim
66 words
The objective lens of either of claim 1 or 2, wherein a best fit wavefront aberration of the objective lens through the first thickness (t1) of transparent substrate of the optical information recording medium is not more than 0.05 λrms, where λ represents an emitting wavelength of the laser source when information is obtained from the information recording surface of the first optical information recording medium.
Claim 4
Dependent Claim
72 words
The objective lens of either of claims 1 through 3, wherein a best fit wavefront aberration of the objective lens through the second thickness (t2) of transparent substrate of the optical information recording medium within the third numerical aperture (NA3) is not more than 0.07 λrms, where λ represents an emitting wavelength of the laser source when information is obtained from the information recording surface of the second optical information recording medium.
Claim 5
Dependent Claim
52 words
The objective lens of either of claims 1 through 4, wherein on the lens surface having the discontinuous spherical aberration, a spherical aberration corresponding to half the third numerical aperture (NA3) is over-corrected more than that corresponding to the third numerical aperture when the first thickness (t1) of transparent substrate is used.
Claim 6
Dependent Claim
53 words
The objective lens of either of claims 1 through 5, wherein the first thickness (t1) is 0.6 mm, and the first numerical aperture (NA1) is λ/1.14 µm where λ represents an emitting wavelength of the laser source when information is obtained from the information recording surface of the first optical information recording medium.
Claim 7
Dependent Claim
53 words
The objective lens of either of claims 1 through 6, wherein the second thickness (t2) is 1.2 mm, and the second numerical aperture (NA2) is λ/1.75 µm, where λ represents an emitting wavelength of the laser source when information is obtained from the information recording surface of the second optical information recording medium.
Claim 8
Dependent Claim
53 words
The objective lens of either of claims 1 through 7, wherein the second thickness (t2) is 1.2 mm, and the second numerical aperture (NA2) is λ/2.46 µm, where λ represents an emitting wavelength of the laser source when information is obtained from the information recording surface of the second optical information recording medium.
Claim 9
Dependent Claim
15 words
An optical pickup apparatus having the objective lens of either of claims 1 through 8.
References Cited (Backward Citations)
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