CN210442566U

CN210442566U - Small athermal prime lens

Info

Publication number: CN210442566U
Application number: CN201921837836.1U
Authority: CN
Inventors: 殷海明
Original assignee: Dongguan Changyi Photoelectric Co ltd
Current assignee: Dongguan Changyi photoelectric Co.,Ltd.
Priority date: 2019-10-30
Filing date: 2019-10-30
Publication date: 2020-05-01
Anticipated expiration: 2029-10-30

Abstract

The utility model discloses a small-size athermalization tight shot includes first lens, second lens, third lens, fourth lens, fifth lens, sixth lens and seventh lens from the object side to the image plane in proper order, wherein first lens and sixth lens are biconcave negative refractive power lens, and the third lens is meniscus positive refractive power lens, and the convex surface is towards the image plane side, and second lens, fourth lens, fifth lens and seventh lens are biconvex positive refractive power lens, and the convex surface of third lens is the grating face. The utility model discloses a focus of each lens of rational configuration realizes big wide angle, big light ring, does not have the thermalization, has advantages such as resistant ambient temperature stability.

Description

Small athermal prime lens

Technical Field

The utility model relates to a camera lens technical field, especially a small-size athermal confocal camera lens.

Background

With the development of security lenses, the requirements on imaging quality are higher and higher while the products are further miniaturized. The requirements for image quality in a night vision environment are becoming more and more strict, and therefore a lens capable of realizing full-color photographing under a low-light condition is required.

However, the existing products obviously cannot meet the technical requirements of large wide angle, large aperture, no heat and the like while achieving miniaturization, and therefore further technical research and development are needed.

SUMMERY OF THE UTILITY MODEL

The to-be-solved technical problem of the utility model is not enough to above-mentioned prior art, provide a small-size no thermalization confocal camera lens, realized the miniaturization of product, realized no thermalization when satisfying big wide angle, big light ring.

In order to solve the technical problem, the utility model discloses the technical scheme who takes is: a small athermal prime lens sequentially comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens from an object side to an imaging surface, wherein the first lens and the sixth lens are biconcave negative refractive power lenses, the third lens is a meniscus positive refractive power lens, a convex surface faces the imaging surface side, the second lens, the fourth lens, the fifth lens and the seventh lens are biconvex positive refractive power lenses, and a convex surface of the third lens is a grating surface.

In the above technical solution, an optical filter is further disposed between the seventh lens and the imaging side.

In the above technical solution, at least one or two surfaces of the first lens element, the second lens element, the fifth lens element, the sixth lens element and the seventh lens element are aspheric surfaces, and the third lens element is a spherical surface or an aspheric surface.

In the above technical solution, the focal length f1 of the first lens satisfies the following condition: -2.12< f1/f < -1.41; where f is the focal length of the lens.

In the above technical solution, the focal length f2 of the second lens satisfies the following condition: 5.36< f2/f < 8.04; where f is the focal length of the lens.

In the above technical solution, the focal length f3 of the third lens satisfies the following condition: 175< f3/f < 262; where f is the focal length of the lens.

In the above technical solution, the focal length f4 of the fourth lens satisfies the following condition: 2.51< f4/f < 3.76; where f is the focal length of the lens.

In the above technical solution, the focal length f5 of the fifth lens satisfies the following condition: 1.85< f5/f < 2.77; where f is the focal length of the lens.

In the above technical solution, the focal length f6 of the sixth lens meets the following condition: -1.93< f6/f < -1.28; where f is the focal length of the lens.

In the above technical solution, the focal length f7 of the seventh lens satisfies the following condition: 1.73< f7/f < 2.60; where f is the focal length of the lens.

The utility model has the advantages that: the small athermal prime lens sequentially comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens from an object side to an imaging surface, wherein the first lens and the sixth lens are biconcave negative refractive power lenses, the third lens is a meniscus positive refractive power lens, a convex surface faces the imaging surface side, the second lens, the fourth lens, the fifth lens and the seventh lens are biconvex positive refractive power lenses, and a convex surface of the third lens is a grating surface. And the large wide angle, the large aperture and the athermalization are realized by reasonably configuring the focal length of each lens, and the lens has the advantages of environmental temperature stability resistance and the like.

Drawings

Fig. 1 is a schematic view of the overall structure of the present invention;

FIG. 2 is a schematic diagram of the optical path of the present invention;

fig. 3 is a graph of field curvature/distortion characteristics of an embodiment of the present invention;

fig. 4 is a graph of axial tolerance of an embodiment of the present invention.

In the figure, the first to seventh lenses L1 to L7, the filter IRCF, the lens surfaces s1 to s15, the grating surface STO and the imaging surface IMA.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings.

As shown in fig. 1, a small-sized athermalized prime lens includes, in order from an object side to an image plane, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a seventh lens L7, wherein the first lens L1 and the sixth lens L6 are biconcave negative refractive power lenses, the third lens L3 is a meniscus positive refractive power lens with a convex surface facing the image plane side, the second lens L2, the fourth lens L4, the fifth lens L5, and the seventh lens L7 are biconvex positive refractive power lenses, and the convex surface of the third lens L3 is a grating surface. An optical filter IRCF is further disposed between the seventh lens L7 and the imaging surface IMA. At least one or two surfaces of the first lens L1, the second lens L2, the fifth lens L5, the sixth lens L6 and the seventh lens L7 are aspheric, and the third lens L3 is spherical or aspheric.

Specifically, the focal length f1 of the first lens L1 satisfies the following condition: -2.12< f1/f < -1.41; where f is the focal length of the lens. The focal length f2 of the second lens L2 satisfies the following condition: 5.36< f2/f < 8.04; where f is the focal length of the lens. A focal length f3 of the third lens L3 satisfies the following condition: 175< f3/f < 262; where f is the focal length of the lens. A focal length f4 of the fourth lens L4 satisfies the following condition: 2.51< f4/f < 3.76; where f is the focal length of the lens. A focal length f5 of the fifth lens L5 satisfies the following condition: 1.85< f5/f < 2.77; where f is the focal length of the lens. A focal length f6 of the sixth lens L6 satisfies the following condition: -1.93< f6/f < -1.28; where f is the focal length of the lens. A focal length f7 of the seventh lens L7 satisfies the following condition: 1.73< f7/f < 2.60; where f is the focal length of the lens. Further description will be made below by way of specific examples.

The following is a specific embodiment of the optical system, the aspheric coefficients in the embodiment being defined as follows:

when the optical axis is located in the Z direction, Z (r) is the sag value calculated from the vertex of the surface, C is the reciprocal of the paraxial radius of curvature, r is the height from the optical axis, K is a conic constant, and A2i is an aspheric coefficient.

Parameters of the examples

Focal length of entire system: f =3.85mm

F-number=1.0

FOV=104°

f1=-6.800mm,f2=25.788mm,f3=841.849mm,f4=12.064mm,f5=8.875mm,

f6=-6.172mm, f7=8.334mm

f1/f=-1.767

f2/f=6.702

f3/f=218.782

f4/f=3.135

f5/f=2.306

f6/f=-1.604

f7/f=2.166。

The lens in the embodiment has the following conditions (table 1) that the radius of curvature R of each lens, the thickness d of each lens, the distance between lenses, the refractive index nd of each lens, and the abbe number vd of each lens satisfy the following conditions:

table 1: physical parameters of each lens

	Flour mark	Radius of curvature R	Thickness d	Effective diameter	Refractive index nd	Abbe number vd
								Article surface	Infinite number of elements	Infinite number of elements	---	---	---
L1	s1	-18.221	1.000	9.25	1.54	55.99
								s2	4.737	1.651	5.95
L2	s3	38.744	1.812	6.14	1.66	20.37
								s4	-29.906	0.743	5.60
L3	s5	-4.762	3.510	5.60	1.79	47.52
								s6	-6.264	-1.129	8.20
STO	s7	Infinite number of elements	1.229	7.90
							L4	s8	13.783	2.700	10.00	1.59	68.62
	s9	-13.783	0.100	10.00
							L5	s10	5.915	2.704	8.05	1.51	57.12
	s11	-16.533	0.091	7.50
							L6	s12	-9.545	0.730	7.01	1.66	20.37
	s13	7.352	1.094	6.40
							L7	s14	5.960	2.116	6.80	1.54	55.99
	s15	-16.644	1.000	7.15
							IRCF	s16	Infinite number of elements	0.700	6.72	1.52	64.21
	s17	Infinite number of elements	2.382	6.70

As can be seen from table 1, the focal powers of the first lens element to the seventh lens element L1 to L7 are distributed reasonably, so that the focal power of each lens element is in a reasonable interval, the tolerance sensitivity is reduced to the greatest extent, and the best performance is exhibited.

The aspheric coefficients of the object planes s1, s2, s3, s4, s10, s11, s12, s13, s14 and s15 are as follows (table 2):

table 2:

K

A4

A6

A8

A10

A12

A14

A16

s1

-72.06

2.52E-03

-1.10E-04

3.12E-06

-4.66E-08

0.00E+00

s2

1.03

9.93E-04

2.61E-05

-1.91E-06

-7.43E-08

0.00E+00

s3

114.72

-6.41E-03

1.60E-04

1.29E-05

-7.50E-07

2.62E-08

0.00E+00

s4

-38.04

-4.41E-03

2.53E-04

2.66E-06

-3.09E-08

7.60E-09

0.00E+00

s10

-0.48

-5.82E-04

-2.37E-05

1.21E-06

5.25E-08

0.00E+00

s11

9.70

-1.14E-03

8.28E-05

-7.80E-07

1.84E-08

0.00E+00

s12

-11.15

3.04E-03

-2.96E-04

9.90E-06

-8.83E-08

0.00E+00

S13

3.03

1.57E-03

1.34E-05

-2.86E-05

1.13E-06

0.00E+00

S14

-3.11

-2.04E-03

2.35E-04

-1.41E-05

2.26E-07

-2.37E-08

0.00E+00

S15

-94.48

-2.13E-03

1.71E-04

-1.09E-05

-2.31E-08

-1.22E-08

0.00E+00

as can be seen from table 2, the first lens L1, the second lens L2, the fifth lens L5, the sixth lens L6 and the seventh lens L7 have advantages due to their aspheric coefficients.

The field curvature/distortion characteristic graph of the present embodiment can be seen from fig. 3, and the axial convergence graph of the present embodiment can be seen from fig. 4. Fig. 3 and 4 can reflect the main parameter level that the lens of the embodiment can reach in the optical design, which is superior to the existing lens products of the same type.

The above embodiments are merely illustrative and not restrictive, and all equivalent changes and modifications made by the methods described in the claims are intended to be included within the scope of the present invention.

Claims

1. A small athermal prime lens, comprising: the optical lens assembly sequentially comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens from an object side to an image plane, wherein the first lens and the sixth lens are biconcave negative refractive power lenses, the third lens is a meniscus positive refractive power lens, a convex surface faces the image plane side, the second lens, the fourth lens, the fifth lens and the seventh lens are biconvex positive refractive power lenses, and a convex surface of the third lens is a grating surface.

2. The small athermal prime lens of claim 1, wherein: and an optical filter is arranged between the seventh lens and the imaging side.

3. The small athermal prime lens of claim 1, wherein: at least one surface or two surfaces of the first lens, the second lens, the fifth lens, the sixth lens and the seventh lens are aspheric surfaces, and the third lens is a spherical surface or an aspheric surface.

4. The small athermal prime lens of claim 1, wherein: the focal length f1 of the first lens satisfies the following condition: -2.12< f1/f < -1.41; where f is the focal length of the lens.

5. The small athermal prime lens of claim 1, wherein: the focal length f2 of the second lens satisfies the following condition: 5.36< f2/f < 8.04; where f is the focal length of the lens.

6. The small athermal prime lens of claim 1, wherein: the focal length f3 of the third lens satisfies the following condition: 175< f3/f < 262; where f is the focal length of the lens.

7. The small athermal prime lens of claim 1, wherein: the focal length f4 of the fourth lens satisfies the following condition: 2.51< f4/f < 3.76; where f is the focal length of the lens.

8. The small athermal prime lens of claim 1, wherein: the focal length f5 of the fifth lens satisfies the following condition: 1.85< f5/f < 2.77; where f is the focal length of the lens.

9. The small athermal prime lens of claim 1, wherein: the focal length f6 of the sixth lens satisfies the following condition: -1.93< f6/f < -1.28; where f is the focal length of the lens.

10. The small athermal prime lens of claim 1, wherein: a focal length f7 of the seventh lens satisfies the following condition: 1.73< f7/f < 2.60; where f is the focal length of the lens.