Patent US5087990A successfully refreshed from Google Patents.
US5087990A
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US
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Collimator lens of erasable and re-recordable magneto-optical disk system
Assignee: Pentax Corp
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Filing: 1990-06-11
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Granted: 1992-02-11
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Expires: 2010-06-11
Abstract
Abstract A collimator lens for an erasable and re-recordable magneto-optical disk system comprising a first positive lens, a second positive lens and a third negative lens arranged from a light outgoing side in order. The second and third lenses are cemented together and the cemented lens has a positive power. A refractive index of the first lens n1 is lower than 1.686.
Inventors
- 👤 Koichi Maruyama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 20:34
CPC Classifications
G; G02; G02B; G02B13/00; G02B13/24
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
159 words
A collimator lens for an erasable and re-recordable magneto-optical disk system comprising: a positive first lens having a convex light emergent, surface and a light incident surface, wherein said light incident surface has a greater radius of curvature than the radius of curvature of said convex light emergent surface, a positive cemented lens having a positive second lens having a convex light emergent surface and a light incident surface, wherein said light incident surface has a greater radius of curvature than the radius of curvature of said convex light emergent surface, and a negative third lens having a light emergent surface and a concave light incident surface, wherein said light emergent surface has a greater radius of curvature than the radius of curvature of said concave light incident surface, wherein said lenses are arranged from a light emergent side in order, and said collimator lens satisfies a relation as follows: n1<1.686 where n1: refractive index of the first lens.
Claim 2
Dependent Claim
159 words
A collimator lens for an erasable and re-recordable magneto-optical disk system comprising: a positive first lens having a convex light emergent, surface and a light incident surface, wherein said light incident surface has a greater radius of curvature than the radius of curvature of said convex light emergent surface, a positive cemented lens having a positive second lens having a convex light emergent surface and a light incident surface, wherein said light incident surface has a greater radius of curvature than the radius of curvature of said convex light emergent surface, and a negative third lens having a light emergent surface and a concave light incident surface, wherein said light emergent surface has a greater radius of curvature than the radius of curvature of said concave light incident surface, wherein said lenses are arranged from a light emergent side in order, and said collimator lens satisfies a relation as follows: n1<1.686 where n1: refractive index of the first lens.
Claim 3
Dependent Claim
68 words
A collimator lens for an erasable and re-recordable magneto-optical disk system according to claim 1, wherein the following relations are satisfied: (n3-n2)>0.20 -0.55<f/r4<-0.15 (v3-v2)>28 where n2: refractive index of said second lens n3: refractive index of said third lens f: focal length of said collimator lens r4: radius of curvature of a cemented surface v2: Abbe number of said second lens v3: Abbe number of said third lens.
Claim 4
Dependent Claim
25 words
A collimator lens for an erasable and re-recordable magneto-optical disk system according to claim 1, wherein said first lens is formed as a plane-convex lens.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-02-10 | 1995-08-12 | 1996-02-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-02-10 | 1999-08-12 | 2000-02-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-02-10 | 2003-08-12 | 2004-02-11 | $7700.00 | Window Closed / Lapsed |