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US5986779A
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Multiple focus lens, an optical head apparatus and an optical information recording-reproducing apparatus
Assignee: Panasonic Holdings Corp
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Filing: 1996-08-12
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Granted: 1999-11-16
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Expires: 2016-08-12
Abstract
Abstract Coma of an objective lens occurs depending on the lens-forming condition when plural disks of different substrate thickness are recorded and reproduced. An objective lens according to this invention is not influenced by the coma even if the thickness of the substrates is changed. For this purpose, a diffraction grating whose aberration is corrected is formed on the first side of an aspheric objective lens. Due to this correction, light beams having different diffraction orders, e.g. 0th order diffracted light and +1st order diffracted light, are focused respectively on two kinds of substrates of different thickness. The whole objective lens is tilted to correct its axial coma, and the tilt angle is predetermined to be substantially identical with respect to plural substrates which are different in thickness.
Inventors
- 👤 Yasuhiro Tanaka
- 👤 Michihiro Yamagata
- 👤 Yoshiaki Komma
- 👤 Sadao Mizuno
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 06:40
CPC Classifications
G; G02; G02B; G02B5/00; G02B5/18; G02B5/1876; G02B5/189; G02B5/1895; G11; G11B; G11B7/00; G11B7/08; G02B27/00; G02B27/0025; G02B27/0037; G02B27/42; G02B27/4233; G02B27/4238; G11B7/12; G11B7/135; G11B7/1353; G11B7/1372; G11B7/1374; G11B7/1392; G11B7/13922; G11B2007/0003; G11B2007/0006
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
71 words
A multiple focus objective lens comprising at least one lens and a diffracting means for focusing light on a surface and whose aberration is corrected so that light beams having various diffracting orders focus respectively on plural substrates of different thickness, the lens being tilted to correct axial coma of the lens towards said plural substrates, the tilt angles of said lens with respect to said substrates being substantially the same.
Claim 2
Dependent Claim
71 words
A multiple focus objective lens comprising at least one lens and a diffracting means for focusing light on a surface and whose aberration is corrected so that light beams having various diffracting orders focus respectively on plural substrates of different thickness, the lens being tilted to correct axial coma of the lens towards said plural substrates, the tilt angles of said lens with respect to said substrates being substantially the same.
Claim 3
Dependent Claim
152 words
The multiple focus objective lens according to claim 1, which focuses 0th order diffracted light diffracted by said diffracting means on an information recording surface of a first substrate and focuses +1st order diffracted light diffracted by said diffracting means on an information recording surface of a second substrate which is different in thickness from said first substrate, and meets the requirement, L.sub.1 /(J.sub.1 +D.sub.1)≠L.sub.2 /(J.sub.2 +D.sub.2) where J 1 : off axis coma per unit angle toward the first substrate (mλ) J 2 : off axis coma per unit angle toward the second substrate (mλ) D 1 : coma per unit angle generated when the first substrate is tilted (mλ) D 2 : coma per unit angle generated when the second substrate is tilted (mλ) L 1 : axial coma of the lens toward the first substrate (mλ) L 2 : axial coma of the lens toward the second substrate (mλ).
Claim 4
Dependent Claim
154 words
The multiple focus objective lens according to claim 1, which focuses 0th order diffracted light diffracted by said diffracting means on the information recording surface of the first substrate and focuses +1st order diffracted light diffracted by said diffracting means on the information recording surface of the second substrate different from said first substrate in thickness, and a residual coma ZC meets the requirement, ZC=|L.sub.1 (J.sub.2 +D.sub.2)/(J.sub.1 +D.sub.1)-L.sub.2 |<20 where J 1 : off axis coma per unit angle toward the first substrate (mλ) J 2 : off axis coma per unit angle toward the second substrate (mλ) D 1 : coma per unit angle generated when the first substrate is tilted (mλ) D 2 : coma per unit angle generated when the second substrate is tilted (mλ) L 1 : axial coma of the lens toward the first substrate (mλ) L 2 : axial coma of the lens toward the second substrate (mλ).
Claim 5
Dependent Claim
21 words
The multiple focus objective lens according to claim 1, wherein said diffracting means is formed on one side of the lens.
Claim 6
Dependent Claim
21 words
The multiple focus objective lens according to claim 4, wherein said lens is a singlet having at least one aspheric surface.
Claim 7
Dependent Claim
19 words
The multiple focus objective lens according to claim 4, wherein said diffracting means is a conic circular phase grating.
Claim 8
Dependent Claim
19 words
The multiple focus objective lens according to claim 1, wherein said diffracting means is formed on a plane substrate.
Claim 9
Dependent Claim
20 words
The multiple focus objective lens according to claim 7, whose plane substrate is formed by glass-molding method or resin-molding method.
Claim 10
Dependent Claim
17 words
The multiple focus objective lens according to claim 1, wherein said diffracting means is a phase grating.
Claim 11
Dependent Claim
35 words
The multiple focus objective lens according to claim 1, wherein focusing is conducted by using the 0th order diffracted light and the +1st order diffracted light respectively toward two kinds of substrates of different thickness.
Claim 12
Dependent Claim
20 words
The multiple focus objective lens according to claim 10, which focuses the 0th order diffracted light toward the thicker substrate.
Claim 13
Dependent Claim
20 words
The multiple focus objective lens according to claim 10. which focuses the 0th order diffracted light toward the thinner substrate.
Claim 14
Dependent Claim
47 words
The multiple focus objective lens according to claim 1, which is a singlet having at least one aspheric surface, and the coma the objective lens has on the axis is generated when the first surface and the second surface of the lens are relatively tilted at 0.05°.
Claim 15
Dependent Claim
118 words
The multiple focus objective lens according to claim 1, which meets the requirements: |fa.sup.2 (1/(fd·Vd)+1/(fs·Vs))|<0.0025 Vs=(nλ-1)/(nλ(-)-nλ(+)) Vd=λ/(λ(-)-λ(+)) where: λ: design wavelength λ(+): a wavelength 10 nm longer than the design wavelength λ(-): a wavelength 10 nm shorter than the design wavelength nλ: refractive index of lens for the design wavelength nλ(+): refractive index of lens at wavelength which is 10 nm longer than the design wavelength nλ(-): refractive index of lens at wavelength which is 10 nm shorter than the design wavelength fs: focal length of the lens defined by the 0th order diffracted light fd: focal length of the lens only by diffracting means fa: focal length of the lens defined by the +1st order diffracted light.
Claim 16
Dependent Claim
35 words
The multiple focus objective lens according to claim 1, in which at least one of the surfaces of the lens is integrated with the diffracting means and is formed by glass-molding method or resin-molding method.
Claim 17
Dependent Claim
104 words
An optical head apparatus which comprises a light source, means for focusing the light radiated from the light source on a surface of an information medium, means for separating beams modulated by said information medium, and means for receiving the light modulated by said information medium, wherein said focusing means is a multiple focus objective lens comprising a diffracting means whose aberration is corrected so that light beams having various diffracting orders focus respectively on plural substrates of different thickness, the lens is tilted to correct axial coma of the lens toward said substrates, the tilt angles to said substrates being substantially the same.
Claim 18
Dependent Claim
104 words
An optical head apparatus which comprises a light source, means for focusing the light radiated from the light source on a surface of an information medium, means for separating beams modulated by said information medium, and means for receiving the light modulated by said information medium, wherein said focusing means is a multiple focus objective lens comprising a diffracting means whose aberration is corrected so that light beams having various diffracting orders focus respectively on plural substrates of different thickness, the lens is tilted to correct axial coma of the lens toward said substrates, the tilt angles to said substrates being substantially the same.
Claim 19
Dependent Claim
154 words
The optical head apparatus according to claim 16, whose multiple focus objective lens focuses 0th order diffracted light diffracted by the diffracting means on an information recording surface of a first substrate and focuses +1st order diffracted light diffracted by said diffracting means on an information recording surface of a second substrate which is different in thickness from said first substrate, and meets the requirement, L.sub.1 /(J.sub.1 +D.sub.1)≠L.sub.2 /(J.sub.2 +D.sub.2) where J 1 : off axis coma per unit angle toward the first substrate (mλ) J 2 : off axis coma per unit angle toward the second substrate (mλ) D 1 coma per unit angle generated when the first substrate is tilted (mλ) D 2 : coma per unit angle generated when the second substrate is tilted (mλ) L 1 : axial coma of the lens toward the first substrate (mλ) L 2 : axial coma of the lens toward the second substrate (mλ).
Claim 20
Dependent Claim
156 words
The optical head apparatus according to claim 16, whose multiple focus objective lens focuses 0th order diffracted light diffracted by said diffracting means on the information recording surface of the first substrate and focuses +1st order diffracted light diffracted by said diffracting means on the information recording surface of the second substrate different from said first substrate in thickness, and residual coma ZC meets the requirement, ZC=|L.sub.1 (J.sub.2 +D.sub.2)/(J.sub.1 +D.sub.1)-L.sub.2 |<20 where J 1 : off axis coma per unit angle toward the first substrate (mλ) J 2 : off axis coma per unit angle toward the second substrate (mλ) D 1 : coma per unit angle generated when the first substrate is tilted (mλ) D 2 : coma per unit angle generated when the second substrate is tilted (mλ) L 1 : axial coma of the lens toward the first substrate (mλ) L 2 : axial coma of the lens toward the second substrate (mλ).
Claim 21
Dependent Claim
130 words
An optical information recording-reproducing apparatus which records and reproduces information on plural kinds of recording media of different thickness, by using an optical head apparatus which comprises a light source, means for focusing the light radiated from the light source on a surface of an information medium, means for separating beams modulated by said information medium, and means for receiving the light modulated by said information medium, wherein said focusing means is a multiple focus objective lens comprising a lens and a diffracting means whose aberration is corrected so that light beams having various diffracting orders focus respectively on plural substrates of different thickness, the lens is tilted to correct axial coma of the lens toward said substrates, the tilt angles with respect to said substrates being substantially the same.
Claim 22
Dependent Claim
130 words
An optical information recording-reproducing apparatus which records and reproduces information on plural kinds of recording media of different thickness, by using an optical head apparatus which comprises a light source, means for focusing the light radiated from the light source on a surface of an information medium, means for separating beams modulated by said information medium, and means for receiving the light modulated by said information medium, wherein said focusing means is a multiple focus objective lens comprising a lens and a diffracting means whose aberration is corrected so that light beams having various diffracting orders focus respectively on plural substrates of different thickness, the lens is tilted to correct axial coma of the lens toward said substrates, the tilt angles with respect to said substrates being substantially the same.
Claim 23
Dependent Claim
154 words
The optical information recording-reproducing apparatus according to claim 19, whose multiple focus objective lens focuses 0th order diffracted light diffracted by said diffracting means on an information recording surface of a first substrate while focuses +1st order diffracted light diffracted by said diffracting means on an information recording surface of a second substrate different in thickness from said first substrate, and meets the requirement, L.sub.1 /(J.sub.1 +D.sub.1)≠L.sub.2 /(J.sub.2 +D.sub.2) where J 1 : off axis coma per unit angle toward the first substrate (mλ) J 2 : off axis coma per unit angle toward the second substrate (mλ) D 1 : coma per unit angle generated when the first substrate is tilted (mλ) D 2 : coma per unit angle generated when the second substrate is tilted (mλ) L 1 : axial coma of the lens toward the first substrate (mλ) L 2 : axial coma of the lens toward the second substrate (mλ).
Claim 24
Dependent Claim
157 words
The optical information recording-reproducing apparatus according to claim 19, whose multiple focus objective lens focuses 0th order diffracted light diffracted by said diffracting means on the information recording surface of the first substrate and focuses +1st order diffracted light diffracted by said diffracting means on the information recording surface of the second substrate of different thickness from said first substrate, and residual coma ZC meets the requirement, ZC=|L.sub.1 (J.sub.2 +D.sub.2)/(J.sub.1 +D.sub.1)-L.sub.2 |<20 where J 1 : off axis coma per unit angle toward the first substrate (mλ) J 2 : off axis coma per unit angle toward the second substrate (mλ) D 1 : coma per unit angle generated when the first substrate is tilted (mλ) D 2 : coma per unit angle generated when the second substrate is tilted (mλ) L 1 : axial coma of the lens toward the first substrate (mλ) L 2 : axial coma of the lens toward the second substrate (mλ).
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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) | 2002-11-15 | 2003-05-17 | 2003-11-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-11-15 | 2007-05-17 | 2007-11-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-11-15 | 2011-05-17 | 2011-11-16 | $7700.00 | Window Closed / Lapsed |