CN216351494U

CN216351494U - Fisheye lens

Info

Publication number: CN216351494U
Application number: CN202123055140.3U
Authority: CN
Inventors: 曾繁胜; 何俊毅; 梁伟朝
Original assignee: Sunny Optics Zhongshan Co Ltd
Current assignee: Sunny Optics Zhongshan Co Ltd
Priority date: 2021-12-07
Filing date: 2021-12-07
Publication date: 2022-04-19
Anticipated expiration: 2031-12-07

Abstract

The present invention relates to a fisheye lens, including a first lens (L1) having negative power, a second lens (L2) having negative power, a third lens (L3) having negative power, a fourth lens (L4) having positive power, a Stop (STO), a fifth lens (L5) having positive power, a sixth lens (L6) having negative power, and a seventh lens (L7) having positive power, which are arranged in order from an object side to an image side along an optical axis, wherein a distance d56 from an image side optical axis center of the fifth lens (L5) to an object side optical axis center of the sixth lens (L6) and a distance BFL from the image side optical axis center of the seventh lens (L7) to an image side satisfy the following relationship: d56/BFL is more than or equal to 0.01 and less than or equal to 0.06. The fish-eye lens has the characteristics of large angle, high resolution, day and night confocal property and no virtual focus in the temperature range of-40-80 ℃.

Description

Fisheye lens

Technical Field

The utility model relates to the technical field of optical imaging, in particular to a fisheye lens.

Background

With the improvement of living standard and the enhancement of safety consciousness, people have higher requirements on home security, so that consumers generally require that a monitoring lens has a large angle and high resolution and can obtain a bright and clear image in a dark environment at night. In many optical lenses applied to the monitoring field, the fisheye lens has the advantage of a large field angle, but the imaging quality of most of the existing fisheye lenses is not ideal, and day-night confocal cannot be realized, so that the increasing demands of consumers cannot be met. Therefore, a fisheye lens with high imaging performance and day and night confocal function is needed to be designed.

SUMMERY OF THE UTILITY MODEL

The utility model aims to provide a fisheye lens.

In order to achieve the above object of the present invention, the present invention provides a fisheye lens, comprising a first lens having negative refractive power, a second lens having negative refractive power, a third lens having negative refractive power, a fourth lens having positive refractive power, a diaphragm, a fifth lens having positive refractive power, a sixth lens having negative refractive power, and a seventh lens having positive refractive power, arranged in this order from an object side to an image side along an optical axis, wherein a distance d56 between an image side optical axis center of the fifth lens and an object side optical axis center of the sixth lens and a distance BFL between the image side optical axis center of the seventh lens and an image plane satisfy the following relationship: d56/BFL is more than or equal to 0.01 and less than or equal to 0.06.

According to an aspect of the present invention, the first lens is a convex concave shape, the second lens is a convex concave shape, the third lens is a biconcave shape, the fourth lens is a convex concave shape or a biconvex shape, the fifth lens is a biconvex shape, the sixth lens is a biconcave shape, and the seventh lens is a biconvex shape.

According to an aspect of the present invention, the first lens is a spherical lens, the second lens is an aspherical lens, the third lens is an aspherical lens, the fourth lens is a spherical or aspherical lens, the fifth lens is a spherical or aspherical lens, the sixth lens is an aspherical lens, and the seventh lens is an aspherical lens.

According to one aspect of the utility model, the Abbe number of at least one of the fourth lens and the fifth lens is greater than or equal to 50.

According to an aspect of the present invention, the focal length f1 of the first lens, the focal length f3 of the third lens, and the focal length f6 of the sixth lens satisfy the following relationships, respectively, with the effective focal length f of the fisheye lens: f1/f is more than or equal to-8.1 and less than or equal to-4.2; f3/f is not less than-2 and is not less than-5.4; f6/f is more than or equal to-2.7 and less than or equal to-1.4.

According to an aspect of the present invention, the focal length f2 of the second lens, the focal length f4 of the fourth lens, the focal length f5 of the fifth lens, and the focal length f7 of the seventh lens satisfy the following relationships, respectively, with the effective focal length f of the fisheye lens: f2/f is not less than-3.8 and not more than-2.1; f4/f is more than or equal to 2 and less than or equal to 4.1; f5/f is more than or equal to 2.1 and less than or equal to 3; f7/f is more than or equal to 1.7 and less than or equal to 2.8.

According to an aspect of the present invention, a distance BFL from an image-side surface optical axis center of the seventh lens element to an image surface and a total length TTL of the fisheye lens satisfy the following relationship: BFL/TTL is more than or equal to 0.19 and less than or equal to 0.32.

According to an aspect of the present invention, the total length TTL and the effective focal length f of the fisheye lens satisfy the following relationship: TTL/f is more than or equal to 9.7 and less than or equal to 13.6.

According to an aspect of the present invention, a radius of curvature R11 of the image-side surface of the fifth lens and a radius of curvature R12 of the object-side surface of the sixth lens satisfy the following relationship: the absolute value of R12/R11 is more than or equal to 0.5 and less than or equal to 3.

According to an aspect of the present invention, a radius of curvature R5 of the object-side surface of the third lens and a radius of curvature R15 of the image-side surface of the seventh lens satisfy the following relationship: the absolute value of R5/R15 is more than or equal to 2.5 and less than or equal to 4.5.

According to the concept of the utility model, the glass-plastic mixed fisheye lens can realize large-angle high-resolution confocal day and night without virtual focus in the temperature range of-40-80 ℃.

According to one aspect of the utility model, the maximum aperture of the fisheye lens reaches FNO2.0, and the imaging target surface reaches 1/3 ". And moreover, the glass lens and the plastic lens are used in a mixed mode, so that the confocal effect of visible light and infrared light is realized, and the cost of the lens is effectively reduced. And CRA of the lens is less than or equal to 22 degrees, so that the lens can be adapted to a plurality of sensors, and has wide application prospect and high market competitiveness. The lens can also realize the image capture of the object space field angle of 214 degrees and the F-theta distortion of less than or equal to 38 percent.

Drawings

Fig. 1 is a schematic diagram showing a configuration of a fisheye lens according to a first embodiment of the utility model;

FIG. 2 is a diagram schematically showing an FFT-MTF at a frequency of 200lp/mm for a fisheye lens according to a first embodiment of the utility model;

FIG. 3 is a Through-Focus-MTF graph schematically showing a fisheye lens frequency of 120lp/mm according to a first embodiment of the utility model;

FIG. 4 is a Through-Focus-MTF graph schematically showing the frequency of 120lp/mm at-40 ℃ in a fisheye lens according to a first embodiment of the utility model;

FIG. 5 is a Through-Focus-MTF graph schematically showing a high temperature 80 ℃ frequency of 120lp/mm for a fisheye lens according to a first embodiment of the utility model;

fig. 6 schematically shows a F-Theta distortion plot of a fisheye lens according to a first embodiment of the utility model;

fig. 7 is a schematic view showing a configuration of a fisheye lens according to a second embodiment of the utility model;

FIG. 8 is a graph schematically showing FFT-MTF at a frequency of 200lp/mm for a fisheye lens according to a second embodiment of the present invention;

FIG. 9 is a Through-Focus-MTF graph schematically showing a fisheye lens frequency of 120lp/mm according to a second embodiment of the utility model;

FIG. 10 is a Through-Focus-MTF graph schematically showing the frequency of 120lp/mm at-40 ℃ in a fisheye lens according to a second embodiment of the utility model;

FIG. 11 is a Through-Focus-MTF graph schematically showing a high temperature 80 ℃ frequency of 120lp/mm for a fisheye lens according to a second embodiment of the utility model;

fig. 12 schematically shows a F-Theta distortion graph of a fisheye lens according to a second embodiment of the utility model;

fig. 13 is a schematic view showing a configuration of a fisheye lens according to a third embodiment of the utility model;

FIG. 14 is a graph schematically showing FFT-MTF at a frequency of 200lp/mm for a fisheye lens according to a third embodiment of the utility model;

FIG. 15 is a Through-Focus-MTF graph schematically showing a fisheye lens frequency of 120lp/mm according to a third embodiment of the utility model;

FIG. 16 is a Through-Focus-MTF graph schematically showing the frequency of 120lp/mm at-40 ℃ in a fisheye lens according to a third embodiment of the utility model;

FIG. 17 is a Through-Focus-MTF graph schematically showing a high temperature 80 ℃ frequency of 120lp/mm for a fisheye lens according to a third embodiment of the utility model;

fig. 18 schematically shows a F-Theta distortion graph of a fisheye lens according to a third embodiment of the utility model.

Detailed Description

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments will be briefly described below. It is obvious that the drawings in the following description are only some embodiments of the utility model, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.

In describing embodiments of the present invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in an orientation or positional relationship that is based on the orientation or positional relationship shown in the associated drawings, which is for convenience and simplicity of description only, and does not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus, the above-described terms should not be construed as limiting the present invention.

The present invention is described in detail below with reference to the drawings and the specific embodiments, which are not repeated herein, but the embodiments of the present invention are not limited to the following embodiments.

Referring to fig. 1, the fish-eye lens of the present invention includes a first lens L1 having negative power, a second lens L2 having negative power, a third lens L3 having negative power, a fourth lens L4 having positive power, a stop STO, a fifth lens L5 having positive power, a sixth lens L6 having negative power, and a seventh lens L7 having positive power, which are arranged in order from the object side to the image side along the optical axis. In the present invention, a distance d56 from the image-side optical axis center of the fifth lens L5 to the object-side optical axis center of the sixth lens L6 and a distance BFL from the image-side optical axis center of the seventh lens L7 to the image plane satisfy the following relationship: d56/BFL is more than or equal to 0.01 and less than or equal to 0.06. Thus, under the condition that the back focal length is limited, the tolerance sensitivity of the optical system is favorably reduced.

In the present invention, the first lens L1 is a concave-convex shape, the second lens L2 is a concave-convex shape, the third lens L3 is a biconcave shape, the fourth lens L4 is a concave-convex shape or a biconvex shape, the fifth lens L5 is a biconvex shape, the sixth lens L6 is a biconcave shape, and the seventh lens L7 is a biconvex shape. So, through the roughness of rationally setting up every piece of lens, be favorable to carrying out rational distribution to optical system's focal power to make light transmit better, in order to guarantee imaging quality.

In the present invention, the first lens L1 is a spherical lens, the second lens L2 is an aspherical lens, the third lens L3 is an aspherical lens, the fourth lens L4 is a spherical or aspherical lens, the fifth lens L5 is a spherical or aspherical lens, the sixth lens L6 is an aspherical lens, and the seventh lens L7 is an aspherical lens. Therefore, various aberrations in the optical system can be corrected through reasonable matching of the spherical lens and the aspheric lens, and the resolution of the lens is improved.

In the present invention, the Abbe number of at least one of the fourth lens L4 and the fifth lens L5 is not less than 50. The condition is satisfied, and purple fringing and near infrared aberration can be effectively balanced. The focal length f1 of the first lens L1, the focal length f3 of the third lens L3, and the focal length f6 of the sixth lens L6 satisfy the following relationships, respectively, with the effective focal length f of the fisheye lens: f1/f is more than or equal to-8.1 and less than or equal to-4.2; f3/f is not less than-2 and is not less than-5.4; f6/f is more than or equal to-2.7 and less than or equal to-1.4. Through the combination of the focal length sections, the effective correction of aberration can be realized, so that the optical system meets the characteristic of high resolution, and simultaneously meets day and night confocal and high and low temperature non-virtual focus. The focal length f2 of the second lens L2, the focal length f4 of the fourth lens L4, the focal length f5 of the fifth lens L5 and the focal length f7 of the seventh lens L7 satisfy the following relationships, respectively, with the effective focal length f of the fisheye lens: f2/f is not less than-3.8 and not more than-2.1; f4/f is more than or equal to 2 and less than or equal to 4.1; f5/f is more than or equal to 2.1 and less than or equal to 3; f7/f is more than or equal to 1.7 and less than or equal to 2.8. The distribution of the optical power enables light to smoothly pass through the optical system, thereby reducing tolerance sensitivity of the whole optical system. The distance BFL from the center of the optical axis of the image side surface of the seventh lens L7 to the image surface and the total length TTL of the fisheye lens satisfy the following relation: BFL/TTL is more than or equal to 0.19 and less than or equal to 0.32. Satisfying this relationship enables the lens to meet the size requirements and miniaturization characteristics of mainstream cameras. The total length TTL and the effective focal length f of the fisheye lens satisfy the following relation: TTL/f is more than or equal to 9.7 and less than or equal to 13.6. Thus, the method is beneficial to realizing higher resolution and simultaneously ensuring small volume. The radius of curvature R11 of the image-side surface of the fifth lens L5 and the radius of curvature R12 of the object-side surface of the sixth lens L6 satisfy the following relationship: the absolute value of R12/R11 is more than or equal to 0.5 and less than or equal to 3. By the distribution mode of the curvature radius, the adjustment of the incident angle of the principal ray can be realized, the ray is further converged, and the clear imaging of the optical system is ensured. The radius of curvature R5 of the object-side surface of the third lens L3 and the radius of curvature R15 of the image-side surface of the seventh lens L7 satisfy the following relationship: the absolute value of R5/R15 is more than or equal to 2.5 and less than or equal to 4.5. Thus, it is advantageous to effectively correct distortion of the optical system.

In conclusion, the maximum aperture of the lens can reach FNO2.0, and the imaging target surface can reach 1/3 ". The utility model adopts the scheme of mixing the glass lens and the plastic lens, can realize the confocal of visible light and infrared light, and thus effectively reduces the cost of the lens. And the lens CRA is less than or equal to 22 degrees, so that the lens CRA can be adapted to a plurality of sensors, and the lens CRA has a wide application prospect and high market competitiveness. The lens can realize no virtual focus within the temperature range of minus 40 ℃ to 80 ℃, thereby being suitable for different environments. In addition, the lens can also realize the image capture of the object-side view angle of 214 degrees and the F-theta distortion of less than or equal to 38 percent.

In the following, the fisheye lens of the present invention will be described in detail in three embodiments, where the surfaces of the optical elements are denoted by S0, S1, …, and SN, the stop may be denoted by STO, the object plane may be denoted by OBJ, and the image plane may be denoted by IMA.

The parameters of each embodiment specifically satisfying the above conditional expressions are shown in table 1 below:

table 1 the aspherical lens of the fish-eye lens of the present invention satisfies the following formula:

wherein z is the axial distance from the curved surface to the vertex at the position with the height h perpendicular to the optical axis along the direction of the optical axis; c represents the curvature at the apex of the aspherical surface; k is a conic coefficient; a. the₄、A₆、A₈、A₁₀、A₁₂、A₁₄、A₁₆The aspherical coefficients of the fourth, sixth, eighth, tenth, twelfth, fourteenth and sixteenth orders are expressed respectively.

First embodiment

Referring to fig. 1 to 6, in the present embodiment, each parameter of the fisheye lens is F #: 2.1; total lens length: 11.889 mm; the field angle: 214 deg.

The parameters related to each lens of the fisheye lens of the present embodiment, including the surface type, the radius of curvature, the thickness, the refractive index of the material, and the abbe number, are as shown in table 2 below:

TABLE 2

The aspherical surface coefficients of the aspherical lenses in this embodiment are shown in table 3 below:

TABLE 3

Where K is the conic constant of the surface, A₄、A₆、A₈、A₁₀、A₁₂The aspheric coefficients of fourth order, sixth order, eighth order, tenth order and twelfth order.

Second embodiment

Referring to fig. 7 to 12, in the present embodiment, each parameter of the fisheye lens is F #: 2.0; total lens length: 12.130 mm; the field angle: 174 deg.

The parameters related to each lens of the fisheye lens of the present embodiment, including the surface type, the radius of curvature, the thickness, the refractive index of the material, and the abbe number, are shown in table 4 below:

number of noodles	Surface type	R value	Thickness of	Refractive index	Abbe number
						S0(OBJ)	Spherical surface	Infinity	Infinity
S1	Spherical surface	8.452	0.700	1.78	51.3
						S2	Spherical surface	3.233	1.173
S3	Aspherical surface	3.898	0.612	1.54	56.5
						S4	Aspherical surface	1.135	1.662
S5	Aspherical surface	-5.295	0.502	1.54	55.7
						S6	Aspherical surface	1.782	0.072
S7	Aspherical surface	1.801	1.481	1.64	21.2
						S8	Aspherical surface	198.236	0.226
S9(STO)	Spherical surface	Infinity	-0.051
						S10	Spherical surface	2.864	1.070	1.50	79.5
S11	Spherical surface	-2.002	0.065
						S12	Aspherical surface	-1.495	0.401	1.64	21.2
S13	Aspherical surface	65.354	0.070
						S14	Aspherical surface	2.026	1.256	1.53	56.1
S15	Aspherical surface	-1.786	1.003
						S16	Spherical surface	Infinity	0.610	1.52	64.2
S17	Spherical surface	Infinity	1.278
						S18(IMA)	Spherical surface	Infinity	-	-	-

TABLE 4

The aspherical surface coefficients of the aspherical lenses in this embodiment are shown in table 5 below:

TABLE 5

Third embodiment

Referring to fig. 13 to 18, in the present embodiment, each parameter of the fisheye lens is F #: 2.0; total lens length: 12.067 mm; the field angle: 180 deg.

The parameters related to each lens of the fisheye lens of the present embodiment, including the surface type, the radius of curvature, the thickness, the refractive index of the material, and the abbe number, are as shown in table 6 below:

number of noodles	Surface type	R value	Thickness of	Refractive index	Abbe number
						S0(OBJ)	Spherical surface	Infinity	Infinity
S1	Spherical surface	8.716	0.578	1.79	48.2
						S2	Spherical surface	3.260	1.474
S3	Aspherical surface	27.375	0.565	1.56	53.1
						S4	Aspherical surface	1.520	1.585
S5	Aspherical surface	-6.454	0.481	1.54	55.7
						S6	Aspherical surface	2.026	0.070
S7	Spherical surface	2.082	1.814	1.78	25.7
						S8	Spherical surface	-5.561	0.364
S9(STO)	Spherical surface	Infinity	0.016
						S10	Aspherical surface	7.713	0.703	1.54	57.0
S11	Aspherical surface	-1.446	0.065
						S12	Aspherical surface	-1.179	0.401	1.66	20.4
S13	Aspherical surface	9.568	0.063
						S14	Aspherical surface	2.208	1.185	1.53	56.1
S15	Aspherical surface	-1.574	1.003
						S16	Spherical surface	Infinity	0.610	1.52	64.2
S17	Spherical surface	Infinity	1.090
						S18(IMA)	Spherical surface	Infinity	-	-	-

TABLE 6

The aspherical surface coefficients of the aspherical lenses in this embodiment are shown in table 7 below:

TABLE 7

The above description is only one embodiment of the present invention, and is not intended to limit the present invention, and it is apparent to those skilled in the art that various modifications and variations can be made in the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A fisheye lens comprising, in order from an object side to an image side along an optical axis, a first lens (L1) having negative power, a second lens (L2) having negative power, a third lens (L3) having negative power, a fourth lens (L4) having positive power, a Stop (STO), a fifth lens (L5) having positive power, a sixth lens (L6) having negative power, and a seventh lens (L7) having positive power, characterized in that a distance d56 from an image-side optical axis center of the fifth lens (L5) to an object-side optical axis center of the sixth lens (L6) and a distance BFL from the image-side optical axis center of the seventh lens (L7) to an image plane satisfy the following relationship: d56/BFL is more than or equal to 0.01 and less than or equal to 0.06.

2. The fish-eye lens according to claim 1, wherein the first lens (L1) is convexly concave, the third lens (L3) is biconcave, and the sixth lens (L6) is biconcave;

the sixth lens (L6) is an aspherical lens.

3. The fish-eye lens of claim 1, wherein the second lens (L2) is convex-concave, the fourth lens (L4) is convex-concave or biconvex, the fifth lens (L5) is biconvex, and the seventh lens (L7) is biconvex.

4. The fish-eye lens according to claim 1, wherein the first lens (L1) is a spherical lens, the second lens (L2) is an aspherical lens, the third lens (L3) is an aspherical lens, the fourth lens (L4) is a spherical or aspherical lens, the fifth lens (L5) is a spherical or aspherical lens, and the seventh lens (L7) is an aspherical lens.

5. Fish-eye lens according to any of claims 1 to 4, wherein at least one of the fourth lens (L4) and the fifth lens (L5) has an Abbe number ≥ 50.

6. Fish-eye lens according to any of claims 1 to 4, characterized in that the focal length f1 of the first lens (L1), the focal length f3 of the third lens (L3) and the focal length f6 of the sixth lens (L6) satisfy the following relation with the effective focal length f of the fish-eye lens, respectively: f1/f is more than or equal to-8.1 and less than or equal to-4.2; f3/f is not less than-2 and is not less than-5.4; f6/f is more than or equal to-2.7 and less than or equal to-1.4.

7. Fish-eye lens according to any of claims 1 to 4, wherein the focal length f2 of the second lens (L2), the focal length f4 of the fourth lens (L4), the focal length f5 of the fifth lens (L5) and the focal length f7 of the seventh lens (L7), respectively, satisfy the following relation with the effective focal length f of the fish-eye lens: f2/f is not less than-3.8 and not more than-2.1; f4/f is more than or equal to 2 and less than or equal to 4.1; f5/f is more than or equal to 2.1 and less than or equal to 3; f7/f is more than or equal to 1.7 and less than or equal to 2.8.

8. The fisheye lens according to any of claims 1-4, characterised in that the distance BFL from the centre of the image-side optical axis of the seventh lens (L7) to the image plane and the total length TTL of the fisheye lens satisfy the following relation: BFL/TTL is more than or equal to 0.19 and less than or equal to 0.32.

9. The fisheye lens of any of claims 1-4, wherein the total length TTL and the effective focal length f of the fisheye lens satisfy the following relation: TTL/f is more than or equal to 9.7 and less than or equal to 13.6.

10. Fish-eye lens according to one of the claims 1 to 4, characterised in that the radius of curvature R11 of the image side of the fifth lens (L5) and the radius of curvature R12 of the object side of the sixth lens (L6) satisfy the following relation: the absolute value of R12/R11 is more than or equal to 0.5 and less than or equal to 3.

11. Fish-eye lens according to one of the claims 1 to 4, characterized in that the radius of curvature R5 of the object-side surface of the third lens (L3) and the radius of curvature R15 of the image-side surface of the seventh lens (L7) satisfy the following relation: the absolute value of R5/R15 is more than or equal to 2.5 and less than or equal to 4.5.