Patent US4676607A successfully refreshed from Google Patents.
US4676607A
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US
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Behind stop lens
Assignee: Nikon Corp
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Filing: 1985-02-14
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Granted: 1987-06-30
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Expires: 2005-02-14
Abstract
Abstract A behind stop lens comprises, in succession from the object side, a first lens which is a positive meniscus lens having its convex surface facing the object side, a second lens which is a biconcave lens, a third lens which is a biconvex lens, and a fourth lens which is a negative meniscus lens having its convex surface facing the image side. The third lens and the fourth lens are joined together to form a positive cemented lens. The behind stop lens has a stop at a position most adjacent to the image side.
Inventors
- 👤 Koichi Wakamiya
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 17:53
CPC Classifications
G; G02; G02B; G02B9/00; G02B9/12; G02B9/14; G02B9/18; G02B9/20
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
235 words
A behind stop lens having a compact configuration in which various aberrations, especially coma and chromatic coma, are well corrected, comprising, in succession from the object side, a first lens which is a positive meniscus lens having its convex surface facing the object side, a second lens which is a biconcave lens, a third lens which is a biconvex lens, and a fourth lens which is a negative meniscus lens having its convex surface facing the image side, said third lens and said fourth lens being joined together to form a positive cemented lens, said behind stop lens having a stop at a position most adjacent to the image side and satisfying the following conditions: 0.30f<Σd<0.36f (1) 1.58<n2<1.745 (2) n1>n2 (3) 0.26<n3-n4<0.33 (4) 0.6f<f1<1.0f (5) 0.37f<-r6<0.40f (6) 1.7f<-r7<10f (7) 10<ν4-ν3<25 (8) 2<(d5+d6)/d3<9.9 (9) where Σd: full length of the lens system f: composite focal length of the lens r6: curvature radius of the object side surface of the fourth lens r7: curvature radius of the image side surface of the fourth lens d5: center thickness of the third lens d6: center thickness of the fourth lens n1: refractive index of the first lens n2: refractive index of the second lens n3: refractive index of the third lens n4: refractive index of the fourth lens ν3: Abbe number of the third lens ν4: Abbe number of the fourth lens f1: focal length of said first lens.
Claim 2
Dependent Claim
235 words
A behind stop lens having a compact configuration in which various aberrations, especially coma and chromatic coma, are well corrected, comprising, in succession from the object side, a first lens which is a positive meniscus lens having its convex surface facing the object side, a second lens which is a biconcave lens, a third lens which is a biconvex lens, and a fourth lens which is a negative meniscus lens having its convex surface facing the image side, said third lens and said fourth lens being joined together to form a positive cemented lens, said behind stop lens having a stop at a position most adjacent to the image side and satisfying the following conditions: 0.30f<Σd<0.36f (1) 1.58<n2<1.745 (2) n1>n2 (3) 0.26<n3-n4<0.33 (4) 0.6f<f1<1.0f (5) 0.37f<-r6<0.40f (6) 1.7f<-r7<10f (7) 10<ν4-ν3<25 (8) 2<(d5+d6)/d3<9.9 (9) where Σd: full length of the lens system f: composite focal length of the lens r6: curvature radius of the object side surface of the fourth lens r7: curvature radius of the image side surface of the fourth lens d5: center thickness of the third lens d6: center thickness of the fourth lens n1: refractive index of the first lens n2: refractive index of the second lens n3: refractive index of the third lens n4: refractive index of the fourth lens ν3: Abbe number of the third lens ν4: Abbe number of the fourth lens f1: focal length of said first lens.
Claim 3
Dependent Claim
138 words
A behind stop lens according to claim 1, wherein numerical data are as follows: ______________________________________
f = 100 f 2.8 2ω = 62.6°
Radius of Center Refractive
Abbe
curvature thickness and
index number
No. r spacing d n ν
______________________________________
1 32.469 10.568 1.77279 49.4 L1
2 71.207 3.542
3 -160.959 3.999 1.71736 29.5 L2
4 30.706 2.571
5 60.931 10.568 1.79668 45.5 L3
6 -38.016 2.571 1.51680 64.1 L4
7 -347.523
Bf = 76.712 Σd =
33.819
f1 = 69.0
f2 = -35.6
f3 = 47.2
______________________________________ where the left-hand numbers represent the order from the object side, Bf represents the back focal length, f1 represents the focal length of said first lens, f2 represents the focal length of said second lens, and f3 represents the composite focal length of said third lens and said fourth lens.
Claim 4
Dependent Claim
138 words
A behind stop lens according to claim 1, wherein numerical data are as follows: ______________________________________
f = 100 F 2.8 2ω = 62.4°
Radius of Center Refractive
Abbe
curvature thickness and
index number
No. r spacing d n ν
______________________________________
1 32.481 10.858 1.77261 49.4 L1
2 72.782 2.857
3 -176.257 4.857 1.71728 29.5 L2
4 30.292 2.572
5 60.131 10.572 1.79654 45.5 L3
6 -38.204 2.572 1.51709 64.2 L4
7 -494.155
Bf = 76.183 Σd =
34.288
f1 = 67.9
f2 = -35.7
f3 = 47.8
______________________________________ where the left-hand numbers represent the order from the object side, Bf represents the back focal length, f1 represents the focal length of said first lens, f2 represents the focal length of said second lens, and f3 represents the composite focal length of said third lens and said fourth lens.
Claim 5
Dependent Claim
138 words
A behind stop lens according to claim 1, wherein numerical data are as follows: ______________________________________
f = 100 F 2.8 2ω = 57.2°
Radius of Center Refractive
Abbe
curvature thickness and
index number
No. r spacing d n ν
______________________________________
1 32.468 10.567 1.77279 49.4 L1
2 71.206 3.541
3 -160.956 3.999 1.71736 29.5 L2
4 30.705 2.570
5 60.929 10.568 1.79668 45.5 L3
6 -38.015 2.570 1.51680 64.1 L4
7 -347.516
Bf = 76.713 Σd =
33.815
f1 = 69.0
f2 = -35.6
f3 = 47.2
______________________________________ where the left-hand numbers represent the order from the object side, Bf represents the back focal length, f1 represents the focal length of said first lens, f2 represents the focal length of said second lens, and f3 represents the composite focal lnegth of said third lens and said fourth lens.
Claim 6
Dependent Claim
138 words
A behind stop lens according to claim 1, wherein numerical data are as follows: ______________________________________
f = 100 f 2.8 2ω = 62.8°
Radius of Center Refractive
Abbe
curvature thickness and
index number
No. r spacing d n ν
______________________________________
1 32.943 10.286 1.77279 49.4 L1
2 71.697 3.429
3 -159.028 4.857 1.71736 29.5 L2
4 31.252 2.571
5 60.757 10.571 1.79668 45.5 L3
6 -38.424 2.571 1.51680 64.1 L4
7 -313.984
Bf = 77.285 Σd =
34.285
f1 = 70.7
f2 = -36.0
f3 = 47.0
______________________________________ where the left-hand numbers represent the order from the object side, Bf represents the back focal length, f1 represents the focal length of said first lens, f2 represents the focal length of said second lens, and f3 represents the composite focal length of said third lens and said fourth lens.
Claim 7
Dependent Claim
39 words
A behind stop lens according to claim 1, further satisfy the following condition: 1.6<f1/f3<2.1 where f1 is the focal length of said first lens and f3 is the composite focal length of said third lens and said fourth lens.
Claim 8
Dependent Claim
138 words
A behind stop lens according to claim 6, wherein numerical data are as follows: ______________________________________
f = 100 f 3.5 2ω = 58°
Radius of Center Refractive
Abbe
curvature thickness and
index number
No. r spacing d n ν
______________________________________
1 31.222 10.000 1.76684 46.8 L1
2 55.310 3.333
3 -122.575 3.590 1.69895 30.1 L2
4 30.515 2.051
5 53.162 10.770 1.78797 47.5 L3
6 -37.168 2.821 1.51680 64.1 L4
7 -180.745
Bf = 79.834 Σd =
32.565
f1 = 79.2
f2 = -34.6
f3 = 41.7
______________________________________ where the left-hand numbers represent the order from the object side, Bf represents the back focal length, f1 represents the focal length of said first lens, f2 represents the focal length of said second lens, and f3 represents the composite focal length of said third lens and said fourth lens.
References Cited (Backward Citations)
US4192579A
Cited
US4606615A
Cited
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1990-06-29 | 1990-12-29 | 1991-06-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-06-29 | 1994-12-29 | 1995-06-30 | $3760.00 | Window Closed / Lapsed |
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