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US4668055A
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Lens for an optical recording/reproducing apparatus and optical recording/reproducing apparatus using same
Assignee: Nippon Sheet Glass Co Ltd
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Filing: 1985-11-22
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Granted: 1987-05-26
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Expires: 2005-11-22
Abstract
Abstract In a lens for an optical recording/reproducing apparatus of the invention, a refractive index n(r) at a position of a distance r from an optical axis along a radial direction is given by: n.sup.2 (r)=n.sub.O.sup.2 {1-(g·r).sup.2 +h.sub.4 (g·r) 4 +h 6 (g·r) 6 +h 8 (g·r) 8 + . . . } and the following conditions are satisfied: R.sub.2 =∞ 3.0≧R.sub.1 /(1+0.75S)≧0.8 1.40≦n.sub.O ≦1.87-0.6g·S 0.75≧g·f≧0.45 where n O : refractive index on the optical axis g, h 4 , h 6 , h 8 : coefficients R 1 : radius of curvature of a first surface R 2 : radius of curvature of a second surface S: working distance f: focal distance of an overall optical system at an image side. An optical recording/reproducing apparatus of the invention has a lens as described above as an objective lens.
Inventors
- 👤 Hisami Nishi
- 👤 Minoru Toyama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 18:45
CPC Classifications
G; G02; G02B; G02B9/00; G02B9/02; G02B3/00; G02B3/0087; G11; G11B; G11B7/00; G11B7/12; G11B7/135; G11B7/1372; G11B7/1374; G11B7/1392; G11B7/13922
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
113 words
A lens for an optical recording/reproducing apparatus wherein a refractive index n(r) at a position of a distance r from an optical axis along a radial direction is given by: n.sup.2 (r)=n.sub.0.sup.2 {1-(g·r).sup.2 +h.sub.4 (g·r).sup.4 +h.sub.6 (g·r).sup.6 +h.sub.8 + . . . } and the following conditions are satisfied: R.sub.2 =∞ 3.0≧R.sub.1 /(1+0.75S)≧0.8 1.40≦n.sub.0 ≦1.87-0.6g·S 0.75 ≧g·f≧0.45 where n 0 : refractive index on the optical axis g, h 4 , h 6 , h 8 : coefficients R 1 : radius of curvature of a first surface R 2 : radius of curvature of a second surface S: working distance f: focal distance of an overall optical system at an image side.
Claim 2
Dependent Claim
113 words
A lens for an optical recording/reproducing apparatus wherein a refractive index n(r) at a position of a distance r from an optical axis along a radial direction is given by: n.sup.2 (r)=n.sub.0.sup.2 {1-(g·r).sup.2 +h.sub.4 (g·r).sup.4 +h.sub.6 (g·r).sup.6 +h.sub.8 + . . . } and the following conditions are satisfied: R.sub.2 =∞ 3.0≧R.sub.1 /(1+0.75S)≧0.8 1.40≦n.sub.0 ≦1.87-0.6g·S 0.75 ≧g·f≧0.45 where n 0 : refractive index on the optical axis g, h 4 , h 6 , h 8 : coefficients R 1 : radius of curvature of a first surface R 2 : radius of curvature of a second surface S: working distance f: focal distance of an overall optical system at an image side.
Claim 3
Dependent Claim
28 words
A lens according to claim 1, wherein values of n 0 , g, R 1 , S and f satisfy the following conditions: 2.0≧R.sub.1 /(1+0.75S)≧0.9 1.40≦n.sub.0 ≦1.83-0.6g·S 0.61≧g·f≧0.51.
Claim 4
Dependent Claim
16 words
A lens according to claim 1 or 2, wherein a central thickness d satisfies: 0.5≦d≦7 (mm).
Claim 5
Dependent Claim
117 words
An optical recording/reproducing apparatus using a lens as an objective lens wherein a refractive index n(r) at a position of a distance r from an optical axis along a radial direction is given by: n.sup.2 (r)=n.sub.0.sup.2 {1-(g·r).sup.2 +h.sub.4 (g·r).sup.4 +h.sub.6 (g·r).sup.6 +h.sub.8 (g·r).sup.8 + . . . } and the following conditions are satisfied: R.sub.2 =∞ 3.0≧R.sub.1 /(1+0.75S)≧0.8 1.40≦n.sub.0 ≦1.87-0.6g·S 0.75≧g·f≧0.45 where n 0 : refractive index on the optical axis g, h 4 , h 6 , h 8 : coefficients R 1 : radius of curvature of a first surface R 2 : radius of curvature of a second surface S: working distance f: focal distance of an overall optical system at an image side.
Claim 6
Dependent Claim
117 words
An optical recording/reproducing apparatus using a lens as an objective lens wherein a refractive index n(r) at a position of a distance r from an optical axis along a radial direction is given by: n.sup.2 (r)=n.sub.0.sup.2 {1-(g·r).sup.2 +h.sub.4 (g·r).sup.4 +h.sub.6 (g·r).sup.6 +h.sub.8 (g·r).sup.8 + . . . } and the following conditions are satisfied: R.sub.2 =∞ 3.0≧R.sub.1 /(1+0.75S)≧0.8 1.40≦n.sub.0 ≦1.87-0.6g·S 0.75≧g·f≧0.45 where n 0 : refractive index on the optical axis g, h 4 , h 6 , h 8 : coefficients R 1 : radius of curvature of a first surface R 2 : radius of curvature of a second surface S: working distance f: focal distance of an overall optical system at an image side.
Claim 7
Dependent Claim
28 words
An apparatus according to claim 4, wherein values of n 0 , g, R 1 , S and f satisfy the following conditions: 2.0≧R.sub.1 /(1+0.75S)≧0.9 1.40≦n.sub.0 ≦1.83-0.6g·S 0.61≧g·f≧0.51.
Claim 8
Dependent Claim
16 words
An apparatus according to claim 4 or 5, wherein a central thickness d satisfies: 0.5≦d≦7 (mm).
References Cited (Backward Citations)
US934579A
Cited
US4613212A
Cited
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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