Single focus lens
First Claim
Patent Images
1. A single focus lens comprising:
- in order from an object side of the single focus lens,a first lens having positive power and having a convex surface on the object side;
a second lens of a negative meniscus lens and having a concave surface of the object side on its paraxial axis; and
a third lens of an aspherical lens having a convex surface on the object side on its paraxial axis,wherein the single focus lens satisfies conditions (1) to (7);
0.6<
f1/f<
1.5
(1)
69<
ν
dA
(2)
24<
ν
dB<
32
(3)
NdA<
1.55
(4)
1.48<
NdB<
1.65
(5)
L/D<
1.8
(6)
0.30<
RA/f<
0.40
(7)whereinf represents a focal length of the single focus lens;
f1 represents a focal length of the first lens;
ν
dA represents Abbe number of the first lens;
ν
dB represents Abbe number of the second lens;
NdA represents a refractive index at the d-line of the first lens;
NdB represents a refractive index at the d-line of the second lens;
RA represents a paraxial radius of curvature of an object-side surface of the first lens;
L represents a distance along an optical axis between the object-side surface of the first lens and an image-forming position; and
D represents a maximum image height.
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Abstract
A single focus lens is provided and includes: in order from an object side of the single focus lens, a first lens having positive power and having a convex surface on the object side; a second lens of a negative meniscus lens and having a concave surface of the object side on its paraxial axis; and a third lens of an aspherical lens having a convex surface on the object side on its paraxial axis. The single focus lens satisfies conditions specified in the specification.
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Citations
26 Claims
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1. A single focus lens comprising:
- in order from an object side of the single focus lens,
a first lens having positive power and having a convex surface on the object side; a second lens of a negative meniscus lens and having a concave surface of the object side on its paraxial axis; and a third lens of an aspherical lens having a convex surface on the object side on its paraxial axis, wherein the single focus lens satisfies conditions (1) to (7);
0.6<
f1/f<
1.5
(1)
69<
ν
dA
(2)
24<
ν
dB<
32
(3)
NdA<
1.55
(4)
1.48<
NdB<
1.65
(5)
L/D<
1.8
(6)
0.30<
RA/f<
0.40
(7)wherein f represents a focal length of the single focus lens; f1 represents a focal length of the first lens; ν
dA represents Abbe number of the first lens;ν
dB represents Abbe number of the second lens;NdA represents a refractive index at the d-line of the first lens; NdB represents a refractive index at the d-line of the second lens; RA represents a paraxial radius of curvature of an object-side surface of the first lens; L represents a distance along an optical axis between the object-side surface of the first lens and an image-forming position; and D represents a maximum image height. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 18)
wherein ν
dA represents Abbe number of the first lens, and NdA represents a refractive index at the d-line of the first lens.
- in order from an object side of the single focus lens,
-
15. A single focus lens comprising:
- in order from an object side of the single focus lens,
a first lens having positive power and having a convex surface on the object side; a second lens of a negative meniscus lens and having a concave surface of the object aide on its paraxial axis; and a third lens of an aspherical lens having a convex surface on the object side on its paraxial axis, wherein the single focus lens satisfies conditions (1), (6) and (7) for compactness;
0.6<
f1/f<
1.5
(1)
L/D<
1.8
(6)
0.30<
RA/f<
0.40
(7)wherein f represents a focal length of the single focus lens; f1 represents a focal length of the first lens; RA represents a paraxial radius of curvature of an object-side surface of the first lens; L represents a distance along an optical axis between the object-side surface of the first lens and an image-forming position; and D represents a maximum image height. - View Dependent Claims (16, 17, 19, 20, 21, 22)
wherein ν
dB represents Abbe number of the second lens, and NdB represents a refractive index at the d-line of the second lens.
- in order from an object side of the single focus lens,
-
20. The single focus lens according to claim 15, wherein the first and second lenses are aspherical lenses.
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21. The single focus lens according to claim 15, wherein
an object-side surface of the third lens is shaped such that its positive power decreases outward from the optical axis, and the image-side surface of the third lens is a concave surface on its paraxial axis, its negative power decreasing away from the center so that the power turns positive at a position further away from the center. -
22. The single focus lens according to claim 15, wherein the power in the single focus lens is increased by decreasing the radius of curvature of the front surface of the first lens, and the total length of the single focus lens is shortened.
-
23. A single focus lens comprising:
- in order from an object side of the single focus lens,
a first lens having positive power and having a convex surface on the object side; a second lens of a negative meniscus lens and having a concave surface of the object side on its paraxial axis; and a third lens of an aspherical lens having a convex surface on the object side on its paraxial axis, wherein the single focus lens satisfies conditions (2)-(6);
69<
ν
dA
(2)
24<
ν
dB<
32
(3)
NdA<
1.55
(4)
1.48<
NdB<
1.65
(5)
L/D<
1.8
(6)wherein f represents a focal length of the single focus lens; ν
dA represents Abbe number of the first lensν
dB represents Abbe number of the second lens;NdA represents a refractive index at the d-line of the first lens; NdB represents a refractive index at the d-line of the second lens; L represents a distance along an optical axis between the object-side surface of the first lens and an image-forming position; and D represents a maximum image height. - View Dependent Claims (24, 25, 26)
- in order from an object side of the single focus lens,
Specification