US4564268A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical system for semiconductor laser
Assignee: Hitachi Ltd
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Filing: 1982-05-24
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Granted: 1986-01-14
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Expires: 2002-05-24
Abstract
Abstract An optical system for focusing a light beam emitted from a semiconductor laser is disclosed which comprises a lens of a numerical aperture NA satisfying a relation ##EQU1## (where λ and ΔZ indicate a laser wavelength of and an astigmatic focal distance in the semiconductor laser, respectively) to make the wave front aberration of a light beam emerging from the lens smaller than or equal to λ/4, thereby correcting astigmatism in the semiconductor laser.
Inventors
- 👤 Kimio Tatsuno
- 👤 Akira Arimoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 13:55
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/12; G11B7/135; G11B7/1398; B; B41; B41J; B41J2/00; B41J2/435; B41J2/44; B41J2/442; G02; G02B; G02B13/00; G02B27/00; G02B27/18; G11B7/1372; G11B7/1376
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
68 words
An optical system for focusing a laser beam emitted from a gain guide type semiconductor laser on a predetermined recording medium which comprises a non-cylindrical lens satisfying a relatiion ##EQU6## so as to correct astigmatism of said semiconductor laser, where NA, ΔZ and λ indicate a numerical aperture of said lens, an astigmatic focal distance in said semiconductor laser and a laser wavelength of said semiconductor laser, respectively.
Claim 2
Dependent Claim
68 words
An optical system for focusing a laser beam emitted from a gain guide type semiconductor laser on a predetermined recording medium which comprises a non-cylindrical lens satisfying a relatiion ##EQU6## so as to correct astigmatism of said semiconductor laser, where NA, ΔZ and λ indicate a numerical aperture of said lens, an astigmatic focal distance in said semiconductor laser and a laser wavelength of said semiconductor laser, respectively.
Claim 3
Dependent Claim
20 words
An optical system according to claim 1, wherein said laser beam is emitted from said semiconductor laser having large astigmatism.
Claim 4
Dependent Claim
16 words
An optical system according to claim 1, wherein said non-cylindrical lens is a rotational symmetry lens.
Claim 5
Dependent Claim
85 words
An optical system for recording information on or reproducing information from an optical disc, said system comprising a gain guide type semiconductor laser having an astigmatic focal distance of ΔZ and adapted to emit light having a wavelength of λ, a lens system for focusing said light emitted by said laser on a recording medium in said optical disc, said lens system comprising a non-cylindrical lens having a numerical aperture NA which satisfies the relation ##EQU7## so as to correct astigmatism in said semiconductor laser.
Claim 6
Dependent Claim
85 words
An optical system for recording information on or reproducing information from an optical disc, said system comprising a gain guide type semiconductor laser having an astigmatic focal distance of ΔZ and adapted to emit light having a wavelength of λ, a lens system for focusing said light emitted by said laser on a recording medium in said optical disc, said lens system comprising a non-cylindrical lens having a numerical aperture NA which satisfies the relation ##EQU7## so as to correct astigmatism in said semiconductor laser.
Claim 7
Dependent Claim
21 words
An optical system according to claim 4, wherein said gain guide type semiconductor laser is a narrow stripe type semiconductor laser.
Claim 8
Dependent Claim
15 words
An optical system according to claim 5, wherein the astigmatic focal distance is 20-40 μm.
Claim 9
Dependent Claim
39 words
An optical system according to claim 4, wherein said non-cylindrical lens enables a wave front aberration of the light emerging from said lens to be no greater than λ/4 so as to correct the astigmatism in said semiconductor laser.
Claim 10
Dependent Claim
16 words
An optical system according to claim 4, wherein said non-cylindrical lens is a rotational symmetry lens.
Claim 11
Dependent Claim
84 words
An optical system for focusing a laer beam emitted from gain guide type semiconductor laser to a diffraction limit on an optical disc, the semiconductor laser having as astigmatic focal distance of ΔZ and adapted to emit the laser beam having a wavelength of λ, said optical system comprising a non-cylindrical lens arranged to receive the laser beam emitted by the semiconductor laser, said lens having a numerical aperture NA which satisfies the relation ##EQU8## so as to correct astigmatism in the semiconductor laser.
Claim 12
Dependent Claim
84 words
An optical system for focusing a laer beam emitted from gain guide type semiconductor laser to a diffraction limit on an optical disc, the semiconductor laser having as astigmatic focal distance of ΔZ and adapted to emit the laser beam having a wavelength of λ, said optical system comprising a non-cylindrical lens arranged to receive the laser beam emitted by the semiconductor laser, said lens having a numerical aperture NA which satisfies the relation ##EQU8## so as to correct astigmatism in the semiconductor laser.
Claim 13
Dependent Claim
39 words
An optical system according to claim 9, further comprising a focusing lens for receiving the laser beam from said non-cylindrical lens and for focusing the laser beam from said non-cylindrical lens on a recording medium in the optical disc.
Claim 14
Dependent Claim
21 words
An optical system according to claim 9, wherein the gain guide type semiconductor laser is a narrow stripe type semiconductor laser.
Claim 15
Dependent Claim
39 words
An optical system according to claim 9, wherein said non-cylindrical lens enables a wave front aberration of the laser beam emerging from said lens to be no greater than λ/4, so as to correct astigmatism in the semiconductor laser.
Claim 16
Dependent Claim
16 words
An optical system according to claim 9, wherein said non-cylindrical lens is a rotational symmetry lens.
Claim 17
Dependent Claim
111 words
An optical disc apparatus for recording information on or reproducing information from an optical disc, said apparatus comprising a recording medium on and from which predetermined information is optically recorded or reproduced and which is provided in said optical disc, a gain guide type semiconductor laser having an astigmatic focal distance of ΔZ and adapted to emit a laser beam having a wavelength of λ, an optical system for focusing the laser beam emitted from said laser to a diffraction limit on said recording medium, said optical system comprising a non-cylindrical lens having a numerical aperture NA which satisfies the relation ##EQU9## so as to correct astigmatism in said semiconductor laser.
Claim 18
Dependent Claim
111 words
An optical disc apparatus for recording information on or reproducing information from an optical disc, said apparatus comprising a recording medium on and from which predetermined information is optically recorded or reproduced and which is provided in said optical disc, a gain guide type semiconductor laser having an astigmatic focal distance of ΔZ and adapted to emit a laser beam having a wavelength of λ, an optical system for focusing the laser beam emitted from said laser to a diffraction limit on said recording medium, said optical system comprising a non-cylindrical lens having a numerical aperture NA which satisfies the relation ##EQU9## so as to correct astigmatism in said semiconductor laser.
Claim 19
Dependent Claim
27 words
An optical disc apparatus according to claim 14, wherein said non-cylindrical lens is a spherical lens arranged to receive the laser beam emitted by said semiconductor laser.
Claim 20
Dependent Claim
30 words
An optical disc apparatus according to claim 15, wherein said optical system further comprises a focusing lens for focusing the laser beam from said spherical lens on said recording medium.
Claim 21
Dependent Claim
21 words
An optical disc apparatus according to claim 15, said gain guide type semiconductor laser is a narrow stripe type semiconductor laser.
Claim 22
Dependent Claim
16 words
An optical disc apparatus according to claim 17, wherein the astigmatic focal distance is 20-40 μm.
Claim 23
Dependent Claim
55 words
An optical disc apparatus according to claim 14, wherein said non-cylindrical lens is arranged to receive the laser beam emitted by said semiconductor laser and for enabling a wave front aberration of a laser beam emerging from said non-cylindrical lens to be no greater than λ/4, so as to correct astigmatism in said semiconductor laser.
Claim 24
Dependent Claim
16 words
An optical system according to claim 14, wherein said non-cylindrical lens is a rotational symmetry lens.
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US4318594A
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GB2006461A
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US4253735A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-01-13 | 1989-07-15 | 1990-01-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-01-13 | 1993-07-15 | 1994-01-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-01-13 | 1997-07-15 | 1998-01-14 | $7700.00 | Window Closed / Lapsed |