CN109683289B

CN109683289B - Fish-eye lens

Info

Publication number: CN109683289B
Application number: CN201910119295.7A
Authority: CN
Inventors: 上官秋和
Original assignee: Xiamen Leading Optics Co Ltd
Current assignee: Xiamen Leading Optics Co Ltd
Priority date: 2019-02-18
Filing date: 2019-02-18
Publication date: 2024-01-19
Anticipated expiration: 2039-02-18
Also published as: CN109683289A

Abstract

The invention relates to the technical field of lenses, in particular to a fish-eye lens. The invention discloses a fisheye lens, which sequentially comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens and a ninth lens from an object side to an image side along an optical axis; the first lens has negative refractive index, the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface; the second lens has negative refractive power, the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface. The invention has the advantages of large image surface, wide angle, good day-night confocal, good optical performance and good imaging quality.

Description

Fish-eye lens

Technical Field

The invention belongs to the technical field of lenses, and particularly relates to a fisheye lens with good day-night confocal performance and a large image plane.

Background

A fisheye lens is a lens with a focal length of 16mm or less and an ultra-wide angle. The front lens of the lens is large in diameter and protrudes towards the front of the lens in a parabolic shape, and is quite similar to eyes of fish, so the front lens is commonly called as a 'fish-eye lens'. At present, the fisheye lens is widely applied to the fields of security monitoring, vehicle-mounted and the like, so that the requirements for the fisheye lens are higher and higher, but the conventional common fisheye lens has small image surface, low sensor utilization rate, poor day-night switching effect and even no day-night confocal function, is not suitable for all-weather use, and in addition, the optical performance and imaging quality are not ideal enough, so that the ever-increasing requirements of consumers cannot be met.

Disclosure of Invention

The invention aims to provide a fisheye lens which has good day-night confocal and large image plane and wide angle so as to solve the technical problems.

In order to achieve the above purpose, the invention adopts the following technical scheme: the fish-eye lens sequentially comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens and a ninth lens from an object side to an image side along an optical axis; the first lens element to the ninth lens element each comprise an object side surface facing the object side and passing the imaging light and an image side surface facing the image side and passing the imaging light;

the first lens has negative refractive index, the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface;

the second lens has negative refractive index, the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface;

the fish-eye lens has only nine lenses with refractive index.

Further, the third lens element has negative refractive power, wherein an object-side surface of the third lens element is a concave surface, and an image-side surface of the third lens element is a convex surface or a concave surface;

the fourth lens has positive refractive index, the object side surface of the fourth lens is a concave surface or a convex surface, and the image side surface of the fourth lens is a convex surface;

the fifth lens has positive refractive index, the object side surface of the fifth lens is a convex surface, and the image side surface of the fifth lens is a plane;

the sixth lens element has positive refractive index, wherein an object-side surface of the sixth lens element is concave or convex, and an image-side surface of the sixth lens element is convex;

the seventh lens has negative refractive power, the object side surface of the seventh lens is a concave surface, and the image side surface of the seventh lens is a convex surface;

the eighth lens element has positive refractive index, wherein the object-side surface of the eighth lens element is convex, and the image-side surface of the eighth lens element is convex;

the ninth lens element has a negative refractive power, wherein an object-side surface of the ninth lens element is concave, and an image-side surface of the ninth lens element is concave or convex.

Further, the fisheye lens further satisfies: nd1 > 1.95, wherein nd1 is the refractive index of the first lens at d-line.

Further, the image side surface of the third lens element and the object side surface of the fourth lens element are bonded together, and the following requirements are satisfied: 55< vd3<65, 22< vd4<30, where vd3 is the dispersion coefficient of the third lens at d-line and vd4 is the dispersion coefficient of the fourth lens at d-line.

Further, the image side surface of the sixth lens element and the object side surface of the seventh lens element are bonded together, and the following requirements are met: 45< vd6<55, 22< vd7<30, where vd6 is the dispersion coefficient of the sixth lens at d-line and vd7 is the dispersion coefficient of the seventh lens at d-line.

Further, the image side surface of the eighth lens element and the object side surface of the ninth lens element are bonded to each other, and the following requirements are satisfied: 50< vd8<55, 22< vd9<30, where vd8 is the d-line dispersion coefficient of the eighth lens and vd9 is the d-line dispersion coefficient of the ninth lens.

Further, the fisheye lens further satisfies: nd5 > 1.75, wherein nd5 is the refractive index of the fifth lens at d-line.

Further, the fisheye lens further satisfies: 1.95< nd1<2.05, 22< vd1<27,1.75< nd2<1.85, 45< vd2<50,1.50< nd3<1.60, 55< vd3<65,1.75< nd4<1.85, 22< vd4<30,1.75< nd5<1.90, 40< vd5<50,1.70< nd6<1.80, 45< vd6<55,1.80< nd7<1.90, 22< vd7<30,1.75< nd8<1.85, 50< vd8<55,1.80< nd9<1.85, 22< vd9<30, respectively, wherein nd1-nd9 represents the refractive index of the first lens to the ninth lens at the d-line, respectively, and the first to ninth lenses at the d-th line represent the refractive index of the ninth lens at the d-th line, respectively.

Further, the fisheye lens further satisfies: 1.2< T1<1.6,0.65< T2<1.2, T3 > 0.65,2.0< T4<3.5,1.0< T5<2.5,1.2< T6<2.5,1.2< T7<3.5,1.2< T8<3.0, T9 > 0.65, wherein T1-T9 are the thicknesses of the first lens to the ninth lens on the optical axis, respectively.

Further, the fisheye lens further satisfies: 1.2< ALT/ALG <2.0, wherein ALG is the sum of air gaps of the first lens to the ninth lens on the optical axis, ALT is the sum of thicknesses of the nine lenses of the first lens to the ninth lens on the optical axis.

The beneficial technical effects of the invention are as follows:

nine lenses are adopted, and through the arrangement design of concave-convex curved surfaces of the corresponding lenses, the invention has the advantages of large image plane, wide angle, capability of being matched with a 1/2.3 '-2/3' sensor, almost complete confocal day and night, capability of simultaneously achieving high resolution effect in day and night switching, and in addition, the invention also has the advantages of small F-theta distortion due to the assistance of the limitation of related optics; the field of view from the center to the edge, the chromatic aberration is less than 4.5um, and the color reproducibility is high; high resolution and uniform distribution.

Drawings

FIG. 1 is a schematic diagram of a first embodiment of the present invention;

FIG. 2 is a graph of visible defocus of a first embodiment of the present invention;

FIG. 3 is a graph showing infrared (850 nm) defocus for a first embodiment of the present invention;

FIG. 4 is a graph showing MTF at 250lp/mm for visible light according to one embodiment of the present invention;

FIG. 5 is a graph of MTF at 250lp/mm for infrared 850nm for example one of the present invention;

FIG. 6 is a diagram of field curvature and distortion in accordance with a first embodiment of the present invention;

FIG. 7 is a graph showing a color difference curve according to a first embodiment of the present invention;

FIG. 8 is a schematic diagram of a second embodiment of the present invention;

FIG. 9 is a graph of visible defocus of a second embodiment of the present invention;

FIG. 10 is a graph showing infrared (850 nm) defocus for a second embodiment of the present invention;

FIG. 11 is a graph showing MTF of 250lp/mm for visible light in accordance with example II of the present invention;

FIG. 12 is a graph of MTF at 250lp/mm for infrared 850nm for example two of the present invention;

FIG. 13 is a diagram showing curvature of field and distortion in accordance with a second embodiment of the present invention;

FIG. 14 is a graph showing color difference in a second embodiment of the present invention;

FIG. 15 is a schematic view of a third embodiment of the present invention;

FIG. 16 is a graph of visible defocus for a third embodiment of the present invention;

FIG. 17 is an infrared (850 nm) defocus plot of a third embodiment of the present invention;

FIG. 18 is a graph of MTF at 250lp/mm for visible light for example III of the present invention;

FIG. 19 is a graph of MTF at 250lp/mm for infrared 850nm for example three of the present invention;

FIG. 20 is a diagram showing curvature of field and distortion in accordance with a third embodiment of the present invention;

FIG. 21 is a graph showing the color difference of the third embodiment of the present invention;

fig. 22 is a numerical table of the respective expressions of the three embodiments of the present invention.

Detailed Description

The invention will now be further described with reference to the drawings and detailed description.

The term "a lens having a positive refractive index (or negative refractive index)" means that the paraxial refractive index of the lens calculated by Gaussian optics theory is positive (or negative). The term "object side (or image side) of a lens" is defined as the specific range of imaging light rays passing through the lens surface. The surface roughness determination of the lens can be performed by a determination method by a person of ordinary skill in the art, that is, by a sign of a radius of curvature (abbreviated as R value). The R value may be commonly used in optical design software, such as Zemax or CodeV. The R value is also commonly found in the lens data sheet (lens data sheet) of optical design software. When the R value is positive, the object side surface is judged to be convex; when the R value is negative, the object side surface is judged to be a concave surface. On the contrary, when the R value is positive, the image side surface is judged to be concave; when the R value is negative, the image side surface is determined to be convex.

The invention discloses a fisheye lens, which sequentially comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens and a ninth lens from an object side to an image side along an optical axis; the first lens element to the ninth lens element each comprise an object side surface facing the object side and passing the imaging light and an image side surface facing the image side and passing the imaging light;

the fish-eye lens has only nine lenses with refractive index. Nine lenses are adopted, and the first lens and the second lens are provided with the same concave-convex surface structure through the arrangement design of concave-convex surfaces of the first lens and the second lens, namely, the first lens and the second lens are both meniscus-shaped lenses, have large image surfaces and wide angles, can be matched with 1/2.3 '-2/3' sensors, are almost completely confocal day and night, and can simultaneously achieve the advantage of high resolution effect in day and night switching.

Preferably, the third lens element has negative refractive power, wherein the object-side surface of the third lens element is concave, and the image-side surface of the third lens element is convex or concave;

the ninth lens element has a negative refractive power, wherein an object-side surface of the ninth lens element is concave, and an image-side surface of the ninth lens element is concave or convex. Further optimizing day-night confocal performance, optical performance and imaging quality; the image side surface of the fifth lens adopts a plane, so that the structural design is facilitated, and the structural stability is improved.

Preferably, the fisheye lens further satisfies: nd1 > 1.95, wherein nd1 is the refractive index of the first lens at d-line. The first lens is made of high-refractive-index materials, so that smaller optical outer diameter can be realized, and distortion is optimized; and the first lens has good chemical stability and low cost.

Preferably, the image side surface of the third lens element and the object side surface of the fourth lens element are bonded to each other, and the following requirements are satisfied: 55< vd3<65, 22< vd4<30, wherein vd3 is the d-line dispersion coefficient of the third lens, vd4 is the d-line dispersion coefficient of the fourth lens, more preferably, 40< |R34| < 60, R34 is the radius of curvature of the bonding surface between the third lens and the fourth lens, and the chromatic aberration is compensated and corrected; day and night confocal was optimized.

Preferably, the image side surface of the sixth lens element and the object side surface of the seventh lens element are bonded to each other, and the following requirements are satisfied: 45< vd6<55, 22< vd7<30, wherein vd6 is the dispersion coefficient of the sixth lens at d-line, vd7 is the dispersion coefficient of the seventh lens at d-line, more preferably 2< |R67| <5, R67 is the radius of curvature of the bonding surface of the sixth lens and the seventh lens, which reduces chromatic aberration and optimizes day-night confocal.

Preferably, the image side surface of the eighth lens element and the object side surface of the ninth lens element are bonded to each other, and the following requirements are satisfied: 50< vd8<55, 22< vd9<30, wherein vd8 is the d-line dispersion coefficient of the eighth lens, vd9 is the d-line dispersion coefficient of the ninth lens, more preferably, 5< |R89| < 15, R89 is the curvature radius of the bonding surface of the eighth lens and the ninth lens, and the bonding of the sixth lens and the fourth lens and the seventh lens can control chromatic aberration to the optimal state, and the day-night confocal is optimized to reach almost complete confocal.

Preferably, the fisheye lens further satisfies: nd5 > 1.75, wherein nd5 is the refractive index of the fifth lens at d-line. The fifth lens adopts high refractive index material, and can realize high resolution and high image quality by matching with the first lens.

Preferably, the fisheye lens further satisfies: 1.95< nd1<2.05, 22< vd1<27,1.75< nd2<1.85, 45< vd2<50,1.50< nd3<1.60,1.75< nd4<1.85,1.75< nd5<1.90, 40< vd5<50,1.70< nd6<1.80,1.80< nd7<1.90,1.75< nd8<1.85,1.80< nd9<1.85, where nd1-nd9 represent refractive indices of the first to ninth lenses at d-line, and vd1, vd2, vd5 represent dispersion coefficients of the first, second and fifth lenses at d-line, respectively. The combination of the series of materials can realize better chromatic aberration performance, visible and infrared confocal performance, MTF performance and distortion performance.

Preferably, the fisheye lens further satisfies: 1.2< T1<1.6,0.65< T2<1.2, T3 > 0.65,2.0< T4<3.5,1.0< T5<2.5,1.2< T6<2.5,1.2< T7<3.5,1.2< T8<3.0, T9 > 0.65, wherein T1-T9 are the thicknesses of the first lens to the ninth lens on the optical axis, respectively. Can balance chromatic aberration, visible and infrared confocal performance and resolution power and control the overall length of the lens.

Preferably, the fisheye lens further satisfies: 1.2< ALT/ALG <2.0, wherein ALG is the sum of air gaps of the first lens to the ninth lens on the optical axis, ALT is the sum of eight lens thicknesses of the first lens to the ninth lens on the optical axis. The system length of the fish-eye lens is favorable to optimization, and chromatic aberration is further optimized.

Preferably, the first to ninth lenses are made of glass materials to improve optical performance, but not limited thereto, and in some embodiments, may be made of other materials such as plastics.

Preferably, the lens assembly further comprises a diaphragm, and the diaphragm is arranged between the fifth lens and the sixth lens.

Implement one

As shown in fig. 1, a fisheye lens includes, in order from an object side A1 to an image side A2 along an optical axis I, a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a stop 110, a sixth lens 6, a seventh lens 7, an eighth lens 8, a ninth lens 9, and an imaging plane 100; the first lens element 1 to the ninth lens element 9 each comprise an object side surface facing the object side and allowing the imaging light to pass therethrough, and an image side surface facing the image side and allowing the imaging light to pass therethrough.

The first lens element 1 has a negative refractive power, wherein an object-side surface 11 of the first lens element 1 is convex, and an image-side surface 12 of the first lens element 1 is concave;

the second lens element 2 has a negative refractive power, wherein an object-side surface 21 of the second lens element 2 is convex, and an image-side surface 22 of the second lens element 2 is concave;

the third lens element 3 has a negative refractive power, wherein an object-side surface 31 of the third lens element 3 is concave, and an image-side surface 32 of the third lens element 3 is convex;

the fourth lens element 4 has a positive refractive power, wherein an object-side surface 41 of the fourth lens element 4 is concave, and an image-side surface 42 of the fourth lens element 4 is convex;

the fifth lens element 5 has positive refractive power, wherein an object-side surface 51 of the fifth lens element 5 is convex, and an image-side surface 52 of the fifth lens element 5 is planar;

the sixth lens element 6 with positive refractive power has a concave object-side surface 61 and a convex image-side surface 62;

the seventh lens element 7 with negative refractive power has a concave object-side surface 71 and a convex image-side surface 72;

the eighth lens element 8 has a positive refractive power, wherein an object-side surface 81 of the eighth lens element 8 is convex, and an image-side surface 82 of the eighth lens element 8 is convex;

the ninth lens element 9 has a negative refractive power, wherein an object-side surface 91 of the ninth lens element 9 is concave, and an image-side surface 92 of the ninth lens element 9 is concave.

In this embodiment, the third lens 3 and the fourth lens 4 are cemented lenses, the sixth lens 6 and the seventh lens 7 are cemented lenses, and the eighth lens 8 and the ninth lens 9 are cemented lenses.

The detailed optical data of this particular example are shown in Table 1-1.

Table 1-1 detailed optical data for example one

Surface of the body		Radius of curvature	Thickness of (L)	Material of material	Refractive index	Coefficient of dispersion	Focal length
								OBJ	Object plane	Plane surface	Infinity
11	First lens	18.00	1.52	Glass	2.00	25.4	-10.1
								12		6.24	2.47
21	Second lens	12.50	0.78	Glass	1.79	47.5	-9.5
								22		4.57	3.68
31	Third lens	-7.84	2.01	Glass	1.54	59.7	-17.1
								32		-55.77	0
41	Fourth lens	-55.77	2.67	Glass	1.81	25.5	17.2
								42		-11.40	0.1
51	Fifth lens	7.82	2.17	Glass	1.80	44.3	9.7
								52		INF	2.83
110	Diaphragm	INF	0.52
								61	Sixth lens	-67.43	1.80	Glass	1.74	52.7	3.6
62		-2.57	0
								71	Seventh lens	-2.57	2.96	Glass	1.85	23.8	-4.9
72		-10.21	0.1
								81	Eighth lens	7.91	2.67	Glass	1.76	52.3	4.7
82		-5.58	0
								91	Ninth lens	-5.58	0.73	Glass	1.81	25.5	-6.2
92		61.78	3.42
								100	Imaging surface	INF	-

Referring to fig. 22 for the values of other related conditional expressions in this embodiment, G12 is the air gap between the first lens element 1 and the second lens element 2 on the optical axis I, G23 is the air gap between the second lens element 2 and the third lens element 3 on the optical axis I, G45 is the air gap between the fourth lens element 4 and the fifth lens element 5 on the optical axis I, G78 is the air gap between the seventh lens element 7 and the eighth lens element 8 on the optical axis I, gsto is the sum of the front and rear air gaps of the diaphragm 110, and TTL is the distance between the first lens element 1 and the imaging plane 100 on the optical axis I.

Referring to fig. 2 and 3, the visible light and infrared 850nm confocal performance of the present embodiment can be seen that the visible light and infrared confocal performance is good, and the 850nm infrared offset IR shift=1um; with reference to fig. 4 and 5, it can be seen from the figure that the resolution is good, the resolution is high, and both reach 250lp/mm, the field curvature and distortion diagram are shown in fig. 6 (a) and (B), and the distortion is small, and the linear change of the F-theta distortion is less than 5.8%; referring to FIG. 7 for the color difference curve, it can be seen that the field of view has small color difference, and the lateral color difference between 435nm and 656nm is less than 4.5um.

In this embodiment, the diameter of the image surface of the fisheye lens is greater than 7.4mm, and the field angle fov=180°.

Example two

As shown in fig. 8, in this embodiment, the surface roughness and refractive index of each lens are the same as those of the first embodiment, and only the optical parameters such as the radius of curvature and the lens thickness of each lens surface are different.

The detailed optical data of this particular example are shown in Table 2-1.

Table 2-1 detailed optical data for example two

Surface of the body		Radius of curvature	Thickness of (L)	Material of material	Refractive index	Coefficient of dispersion	Focal length
								OBJ	Object plane	Plane surface	Infinity
11	First lens	16.20	1.44	Glass	2.00	25.4	-11.2
								12		6.34	2.46
21	Second lens	13.92	0.73	Glass	1.79	47.5	-8.6
								22		4.46	3.76
31	Third lens	-7.73	1.90	Glass	1.54	59.7	-16.7
								32		-56.8	0
41	Fourth lens	-56.8	2.56	Glass	1.81	25.5	17.1
								42		-11.38	0.32
51	Fifth lens	7.98	2.15	Glass	1.80	44.3	9.9
								52		INF	2.98
110	Diaphragm	INF	0.3
								61	Sixth lens	-68.6	2.2	Glass	1.74	52.7	3.47
62		-2.52	0
								71	Seventh lens	-2.52	2.37	Glass	1.85	23.8	-4.6
72		-10.07	0.62
								81	Eighth lens	7.59	2.52	Glass	1.76	52.3	5.39
82		-7.59	0
								91	Ninth lens	-7.59	0.77	Glass	1.81	25.5	-8.16
92		54.97	3.45
								100	Imaging surface	INF	-

The values of other related conditional expressions of this embodiment are shown in fig. 22.

Referring to fig. 9 and 10, the visible light and infrared 850nm confocal performance of the present embodiment can be seen that the visible light and infrared confocal performance is good, and the 850nm infrared offset IR shift=0um; with reference to fig. 11 and 12, it can be seen from the figure that the resolution is good, the resolution is high, and both reach 250lp/mm, the field curvature and distortion diagram are shown in fig. 13 (a) and (B), and the distortion is small, and the linear change of the F-theta distortion is < -8%; referring to FIG. 14 for the color difference curve, it can be seen that the field of view has small color difference, and the lateral color difference between 435nm and 656nm is less than 4.5um.

Example III

As shown in fig. 15, the surface roughness and refractive index of each lens element in this embodiment are substantially the same as those of the first embodiment, and only the image side surface 32 of the third lens element 3 in this embodiment is concave, the object side surface 41 of the fourth lens element 4 is convex, the object side surface 61 of the sixth lens element 6 is convex, and the image side surface 92 of the ninth lens element 9 is convex, and the optical parameters such as the radius of curvature and the lens thickness of each lens element surface are different.

The detailed optical data of this particular example are shown in Table 3-1.

Table 3-1 detailed optical data for example three

Surface of the body		Radius of curvature	Thickness of (L)	Material of material	Refractive index	Coefficient of dispersion	Focal length
								OBJ	Object plane	Plane surface	Infinity
11	First lens	15.2	1.44	Glass	2.00	25.4	-12.1
								12		6.46	3.07
21	Second lens	27.7	0.95	Glass	1.79	47.5	-6.6
								22		4.34	3.48
31	Third lens	-7.54	0.78	Glass	1.54	59.7	-11.7
								32		40.80	0
41	Fourth lens	40.80	2.73	Glass	1.81	25.5	11.8
								42		-12.24	0.1
51	Fifth lens	7.55	2.22	Glass	1.80	44.3	9.4
								52		INF	3.21
110	Diaphragm	INF	0.38
								61	Sixth lens	78.92	1.63	Glass	1.74	52.7	3.3
62		-2.52	0
								71	Seventh lens	-2.52	2.9	Glass	1.85	23.8	-4.3
72		-12.51	0.4
								81	Eighth lens	8.84	1.97	Glass	1.76	52.3	6.7
82		-10.80	0
								91	Ninth lens	-10.80	0.65	Glass	1.81	25.5	-14.9
92		-101.72	4.34
								100	Imaging surface	INF	-

Referring to fig. 16 and 17, the visible light and infrared 850nm confocal performance of the present embodiment can be seen that the visible light and infrared confocal performance is good, and the 850nm infrared offset IR shift=2um; with reference to fig. 18 and 19, it can be seen from the figure that the resolution is good, the resolution is high, and both reach 250lp/mm, the field curvature and distortion diagram are shown as (a) and (B) of fig. 20, and the distortion is small, and the linear change of the F-theta distortion is < -6%; referring to FIG. 21 for the color difference curve, it can be seen that the field of view has small color difference, and the lateral color difference between 435nm and 656nm is less than 4.5um.

While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Claims

1. The utility model provides a fish-eye lens which characterized in that: the optical lens system comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens and a ninth lens in sequence from an object side to an image side along an optical axis; the first lens element to the ninth lens element each comprise an object side surface facing the object side and passing the imaging light and an image side surface facing the image side and passing the imaging light;

the third lens has negative refractive index, the object side surface of the third lens is a concave surface, and the image side surface of the third lens is a convex surface or a concave surface;

the ninth lens has negative refractive power, the object side surface of the ninth lens is a concave surface, and the image side surface of the ninth lens is a concave surface or a convex surface;

the lens with the refractive index of the fish-eye lens is only nine, and the fish-eye lens further meets the following conditions: 1.2< T1<1.6,0.65< T2<1.2, T3 > 0.65,2.0< T4<3.5,1.0< T5<2.5,1.2< T6<2.5,1.2< T7<3.5,1.2< T8<3.0, T9 > 0.65, wherein T1-T9 are the thicknesses of the first lens to the ninth lens on the optical axis, respectively.

2. The fisheye lens of claim 1 wherein the fisheye lens further satisfies: nd1 > 1.95, wherein nd1 is the refractive index of the first lens at d-line.

3. The fish-eye lens of claim 1, wherein: the image side surface of the third lens element and the object side surface of the fourth lens element are bonded together, and the following requirements are met: 55< vd3<65, 22< vd4<30, where vd3 is the dispersion coefficient of the third lens at d-line and vd4 is the dispersion coefficient of the fourth lens at d-line.

4. A fish-eye lens according to claim 3, wherein: the image side surface of the sixth lens element and the object side surface of the seventh lens element are bonded together, and the following requirements are met: 45< vd6<55, 22< vd7<30, where vd6 is the dispersion coefficient of the sixth lens at d-line and vd7 is the dispersion coefficient of the seventh lens at d-line.

5. The fish-eye lens of claim 4, wherein: the image side surface of the eighth lens element and the object side surface of the ninth lens element are bonded together, and the following requirements are met: 50< vd8<55, 22< vd9<30, where vd8 is the d-line dispersion coefficient of the eighth lens and vd9 is the d-line dispersion coefficient of the ninth lens.

6. The fish-eye lens of claim 1, wherein: the fish-eye lens also satisfies the following conditions: nd5 > 1.75, wherein nd5 is the refractive index of the fifth lens at d-line.

7. The fisheye lens of claim 1 wherein the fisheye lens further satisfies: 1.95< nd1<2.05, 22< vd1<27,1.75< nd2<1.85, 45< vd2<50,1.50< nd3<1.60, 55< vd3<65,1.75< nd4<1.85, 22< vd4<30,1.75< nd5<1.90, 40< vd5<50,1.70< nd6<1.80, 45< vd6<55,1.80< nd7<1.90, 22< vd7<30,1.75< nd8<1.85, 50< vd8<55,1.80< nd9<1.85, 22< vd9<30, respectively, wherein nd1-nd9 represents the refractive index of the first lens to the ninth lens at the d-line, respectively, and the first to ninth lenses at the d-th line represent the refractive index of the ninth lens at the d-th line, respectively.

8. The fisheye lens of claim 1 wherein the fisheye lens further satisfies: 1.2< ALT/ALG <2.0, wherein ALG is the sum of air gaps of the first lens to the ninth lens on the optical axis, ALT is the sum of thicknesses of the nine lenses of the first lens to the ninth lens on the optical axis.