Fish-eye lens

Abstract

The utility model discloses a fisheye lens, and relates to the technical field of optical lenses, the fisheye lens is provided with an object side and an image side which are oppositely arranged along the direction of an optical axis, and the fisheye lens comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens which are sequentially arranged along the optical axis from the object side to the image side, the focal power of the first lens is negative, the focal power of the second lens is negative, the focal power of the third lens is negative, the focal power of the fourth lens is positive, the focal power of the fifth lens is positive, the focal power of the sixth lens is positive, the focal power of the seventh lens is negative, and the focal power of the eighth lens is positive. The diameter dimension D1 of the first lens meets the condition that D1 is smaller than or equal to 12mm; the light ray trend is well controlled through the cooperation of the lens, the structure is more compact while more light rays are introduced, the size and distortion of the lens are reduced, the definition of the lens is improved, the aperture of the lens is prevented from being too large, and the installation space requirement of a final product is met.

Description

Technical Field

[0001] The utility model relates to the technical field of optical lenses, in particular to a fisheye lens. Background Art

[0002] With the improvement of living standards and people's safety awareness, consumers have put forward higher and higher requirements for security monitoring lenses, expecting products to have advantages such as ultra-large field of view, high pixels, and taking into account both day and night scenarios. Due to the characteristics of ultra-large field of view, fisheye lenses introduce a lot of barrel distortion, and the image quality at the edge of the lens is greatly compressed, resulting in reduced edge angle resolution and blurred image quality. In addition, the large field of view angle is accompanied by the large diameter of the first lens, which leads to an oversized front end size of the lens.

[0003] Therefore, how to reduce the volume and distortion of the fisheye lens and improve the clarity is an urgent problem to be solved by those skilled in the art. Utility Model Content

[0004] The main purpose of the utility model is to provide a fisheye lens, aiming to reduce the volume and distortion of the lens and improve the clarity.

[0005] To achieve the above-mentioned purpose, the fisheye lens proposed in the utility model has an object side and an image side which are arranged opposite to each other along the optical axis direction. The fisheye lens comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens which are arranged in sequence from the object side to the image side along the optical axis. The optical focal power of the first lens is negative, the optical focal power of the second lens is negative, the optical focal power of the third lens is negative, the optical focal power of the fourth lens is positive, the optical focal power of the fifth lens is positive, the optical focal power of the sixth lens is positive, the optical focal power of the seventh lens is negative, and the optical focal power of the eighth lens is positive. The diameter size D1 of the first lens satisfies: D1≤12mm.

[0006] In one embodiment, a photosensitive chip opposite to the eighth lens is provided on the image plane side of the eighth lens, the photosensitive chip has an imaging surface close to the eighth lens, and a distance TTL between the object plane side vertex of the first lens and the imaging surface satisfies: TTL / EFL≤8.8; wherein EFL is the effective focal length of the fisheye lens.

[0007] In one embodiment, a distance TTL between the object-side vertex of the first lens and the imaging plane satisfies: TTL≤17.5 mm.

[0008] In one embodiment, a stop is disposed between the fourth lens and the fifth lens, and a diameter d of the stop satisfies: EFL / d≤2.0.

[0009] In one embodiment, the object side of the first lens is convex and the image side is concave. The focal length of the first lens is f1, and f1 satisfies: -10 mm < f1 < -5 mm; the object side of the second lens is convex and the image side is concave. The focal length of the second lens is f2, and f2 satisfies: -7 mm < f2 < -3 mm; the object side of the third lens is concave and the image side is convex. The focal length of the third lens is f3, and f3 satisfies: -14 mm < f3 < -8 mm; the object side of the fourth lens is convex and the image side is convex. The focal length of the fourth lens is f4, and f4 satisfies: 3 mm < f4 < 8 mm; the object side of the fifth lens is concave and the image side is convex. The focal length of the fifth lens is f5, and f5 satisfies: 5 mm < f5 < 8 mm; the object side of the sixth lens is concave and the image side is convex. The focal length of the sixth lens is f6, and f6 satisfies: 3 mm < f6 < 5 mm; the object side of the seventh lens is concave and the image side is concave. The focal length of the seventh lens is f7, and f7 satisfies: -4 mm < f7 < -2 mm; the object side of the eighth lens is convex and the image side is convex. The focal length of the eighth lens is f8, and f8 satisfies: 3 mm < f8 < 7 mm.

[0010] In one embodiment, the sixth lens and the seventh lens are adhesively connected.

[0011] In one embodiment, the refractive index n1 and the dispersion coefficient v1 of the first lens satisfy: 1.65 ≤ n1 ≤ 1.80; 50.0 ≤ v1 ≤ 70.0; the refractive index n2 and the dispersion coefficient v2 of the second lens satisfy: 1.50 ≤ n2 ≤ 1.60; 50.0 ≤ v2 ≤ 60.0; the refractive index n3 and the dispersion coefficient v3 of the third lens satisfy: 1.60 ≤ n3 ≤ 1.70; 18.0 ≤ v3 ≤ 28.0; the refractive index n4 and the dispersion coefficient v4 of the fourth lens satisfy: 1.80 ≤ n4 ≤ 2.05; 25.0 ≤ v4 ≤ 45.0; the refractive index n5 and the dispersion coefficient v5 of the fifth lens satisfy: 1.50 ≤ n5 ≤ 1.65; 60.0 ≤ v5 ≤ 75.0; the refractive index n6 and the dispersion coefficient v6 of the sixth lens satisfy: 1.50 ≤ n6 ≤ 1.65; 60.0 ≤ v6 ≤ 75.0; the refractive index n7 and the dispersion coefficient v7 of the seventh lens satisfy: 1.70 ≤ n7 ≤ 1.85; 30.0 ≤ v7 ≤ 30.0; the refractive index n8 and the dispersion coefficient v8 of the eighth lens satisfy: 1.50 ≤ n8 ≤ 1.60; 50.0 ≤ v8 ≤ 60.0.

[0012] In one embodiment, the first lens, the fourth lens, the sixth lens, and the seventh lens are spherical lenses, and the second lens, the third lens, the fifth lens, and the eighth lens are aspherical lenses.

[0013] In one embodiment, the diameter IC size of the imaging surface satisfies: IC ≤ 9.0 mm.

[0014] In one embodiment, a filter and a protective glass are disposed between the photosensitive chip and the eighth lens.

[0015] The technical solution of the present utility model is beneficial to the collection of light rays of the optical system and can effectively increase the field of view by providing the first lens L1 with a negative optical power; by providing the fourth lens L4 with a positive optical power, which undertakes a large optical power of the system and changes the propagation direction of the light beam, it is more conducive to the imaging of the light beam. Through the cooperation of each lens, the trend of light rays is well controlled, while introducing more light rays, the structure is made more compact, the volume and distortion of the lens are reduced, and the clarity of the lens is improved. And D1 ≤ 12 mm to avoid too large an aperture of the lens and meet the installation space requirements of the final product. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0017] Figure 1 It is a schematic structural diagram of an embodiment of the fish-eye lens provided by the present utility model;

[0018] Figure 2 It is Figure 1 a schematic diagram of the vertical chromatic aberration curve of

[0019] Figure 3 It is Figure 1 a schematic diagram of the ray aberration curve of

[0020] Figure 4 It is Figure 1 a schematic diagram of the field curvature and distortion of

[0021] Figure 5 It is Figure 1 the MTF diagram at 20 °C of

[0022] Figure 6 It is Figure 1 the 20 °C visible Through focus MTF diagram of

[0023] Figure 7 It is Figure 1 the 20 °C infrared Through focus MTF diagram of

[0024] Figure 8 It is Figure 1 the -20 °C visible Through focus MTF diagram of

[0025] Figure 9 For Figure 1 the 60°C visible Through focus MTF diagram.

[0026] Explanation of the reference numerals in the attached drawings:

[0027] 100, fisheye lens; L1, first lens; L2, second lens; L3, third lens; L4, fourth lens; STO, aperture; L5, fifth lens; L6, sixth lens; L7, seventh lens; L8, eighth lens; L9, filter; L10, protective glass; L11, photosensitive chip;

[0028] S1, object side of the first lens; S2, image side of the first lens; S3, object side of the second lens; S4, image side of the second lens; S5, object side of the third lens; S6, image side of the third lens; S7, object side of the fourth lens; S8, image side of the fourth lens; S10, object side of the fifth lens; S11, image side of the fifth lens; S12, object side of the sixth lens; S13, image side of the sixth lens; S14, object side of the seventh lens; S15, image side of the seventh lens; S16, object side of the eighth lens; S17, image side of the eighth lens; S18, object side of the filter; S19, image side of the filter; S20, object side of the protective glass; S21, image side of the protective glass; S22, imaging surface.

[0029] The realization, functional features, and advantages of the purpose of the present utility model will be further described in conjunction with the embodiments with reference to the attached drawings. Specific embodiments

[0030] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the attached drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts fall within the scope of protection of the present utility model.

[0031] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of the present utility model, then the directional indications are only used to explain the relative positional relationship and movement conditions between components in a specific posture. If the specific posture changes, then the directional indications will also change accordingly.

[0032] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the utility model, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the utility model.

[0033] With the improvement of living standards and people's safety awareness, consumers have put forward higher and higher requirements for security monitoring lenses, expecting products to have advantages such as ultra-large field of view, high pixels, and taking into account both day and night scenarios. Because fisheye lenses have the characteristics of ultra-large field of view, a large amount of barrel distortion is introduced, and the image quality at the edge of the lens is greatly compressed, resulting in reduced edge angle resolution and blurred image quality. In addition, the large field of view angle is accompanied by the large diameter of the first lens, which leads to an oversized front end size of the lens.

[0034] In view of this, the utility model proposes a fisheye lens, which aims to reduce the size and distortion of the lens and improve the clarity. Figures 1 to 9 , the accompanying drawings show a specific embodiment of the fisheye lens.

[0035] In one embodiment of the present invention, please refer to Figure 1 The fisheye lens has an object side and an image side which are arranged opposite to each other along the optical axis. The fisheye lens includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens which are arranged in sequence from the object side to the image side along the optical axis. The optical focal power of the first lens is negative, the optical focal power of the second lens is negative, the optical focal power of the third lens is negative, the optical focal power of the fourth lens is positive, the optical focal power of the fifth lens is positive, the optical focal power of the sixth lens is positive, the optical focal power of the seventh lens is negative, and the optical focal power of the eighth lens is positive. The diameter size D1 of the first lens satisfies: D1≤12mm.

[0036] The technical solution of the present utility model is to set the first lens L1 with negative optical power, which is beneficial to the collection of light rays in the optical system and can effectively increase the field of view. By setting the fourth lens L4 with positive optical power, it undertakes a large optical power of the system and changes the propagation direction of the light beam, which is more conducive to the imaging of the light beam. Through the cooperation of each lens, the trend of light rays is well controlled. While introducing more light rays, the structure is made more compact, reducing the volume and distortion of the lens and improving the lens clarity. And D1 ≤ 12 mm to avoid too large an aperture of the lens, meeting the installation space requirements of the final product.

[0037] In an embodiment of the present utility model, an imaging chip L11 opposite to the eighth lens L8 is provided on the image plane side of the eighth lens L8. The imaging chip L11 has an imaging plane close to the eighth lens L8. The distance between the vertex on the object plane side of the first lens L1 and the imaging plane is TTL. TTL and EFL satisfy: TTL / EFL ≤ 8.8; where EFL is the effective focal length of the fish-eye lens 100. With such a setting, the total length TTL of the fish-eye lens 100 can be shortened, making the lens group more lightweight and portable.

[0038] In an embodiment of the present utility model, the distance TTL between the vertex on the object plane side of the first lens L1 and the imaging plane satisfies: TTL ≤ 17.5 mm. With such a setting, the length of the fish-eye lens 100 is small, meeting the installation space requirements of the final product.

[0039] In an embodiment of the present utility model, a diaphragm STO is provided between the fourth lens L4 and the fifth lens L5. The diameter d of the diaphragm STO satisfies: EFL / d ≤ 2.0. With such a setting, the fish-eye lens can have a higher light transmittance, allowing more light rays to enter, enabling the fish-eye lens 100 to clearly image even in low light. While the field of view of the fish-eye lens 100 is wider, more data information can be obtained more fully.

[0040] In an embodiment of the present utility model, the object surface side of the first lens L1 is convex, and the image surface side is concave. The focal length of the first lens L1 is f1, and f1 satisfies: -10 mm < f1 < -5 mm; the object surface side of the second lens L2 is convex, and the image surface side is concave. The focal length of the second lens L2 is f2, and f2 satisfies: -7 mm < f2 < -3 mm; the object surface side of the third lens L3 is concave, and the image surface side is convex. The focal length of the third lens L3 is f3, and f3 satisfies: -14 mm < f3 < -8 mm; the object surface side of the fourth lens L4 is convex, and the image surface side is convex. The focal length of the fourth lens L4 is f4, and f4 satisfies: 3 mm < f4 < 8 mm; the object surface side of the fifth lens L5 is concave, and the image surface side is convex. The focal length of the fifth lens L5 is f5, and f5 satisfies: 5 mm < f5 < 8 mm; the object surface side of the sixth lens L6 is concave, and the image surface side is convex. The focal length of the sixth lens L6 is f6, and f6 satisfies: 3 mm < f6 < 5 mm; the object surface side of the seventh lens L7 is concave, and the image surface side is concave. The focal length of the seventh lens L7 is f7, and f7 satisfies: -4 mm < f7 < -2 mm; the object surface side of the eighth lens L8 is convex, and the image surface side is convex. The focal length of the eighth lens L8 is f8, and f8 satisfies: 3 mm < f8 < 7 mm. Through the mutual combination of different lenses, the matching relationship of the shapes between different lenses, and the reasonable distribution of the optical power, a compact athermalization is achieved, which has good performance such as a small volume, a large viewing angle, a small infrared defocus amount, and very good thermal aberration correction. The field of view is wider and the applicability is extensive.

[0041] In an embodiment of the present utility model, the sixth lens L6 and the seventh lens L7 are adhesively connected. An adhesive lens group is formed through the adhesive connection to minimize or eliminate chromatic aberration to the greatest extent, improve the image quality, and reduce the reflection loss of light energy, thereby enhancing the clarity of imaging.

[0042] In an embodiment of the present utility model, the refractive index n1 and the dispersion coefficient v1 of the first lens L1 satisfy: 1.65 ≤ n1 ≤ 1.80; 50.0 ≤ v1 ≤ 70.0; the refractive index n2 and the dispersion coefficient v2 of the second lens L2 satisfy: 1.50 ≤ n2 ≤ 1.60; 50.0 ≤ v2 ≤ 60.0; the refractive index n3 and the dispersion coefficient v3 of the third lens L3 satisfy: 1.60 ≤ n3 ≤ 1.70; 18.0 ≤ v3 ≤ 28.0; the refractive index n4 and the dispersion coefficient v4 of the fourth lens L4 satisfy: 1.80 ≤ n4 ≤ 2.05; 25.0 ≤ v4 ≤ 45.0; the refractive index n5 and the dispersion coefficient v5 of the fifth lens L5 satisfy: 1.50 ≤ n5 ≤ 1.65; 60.0 ≤ v5 ≤ 75.0; the refractive index n6 and the dispersion coefficient v6 of the sixth lens L6 satisfy: 1.50 ≤ n6 ≤ 1.65; 60.0 ≤ v6 ≤ 75.0; the refractive index n7 and the dispersion coefficient v7 of the seventh lens L7 satisfy: 1.70 ≤ n7 ≤ 1.85; 30.0 ≤ v7 ≤ 30.0; the refractive index n8 and the dispersion coefficient v8 of the eighth lens L8 satisfy: 1.50 ≤ n8 ≤ 1.60; 50.0 ≤ v8 ≤ 60.0. By optimizing the combination of the refractive index and the dispersion coefficient of each lens, chromatic aberration is eliminated to achieve the effect of infrared confocal, which is also beneficial to the athermalization of the fish-eye lens 100.

[0043] In an embodiment of the present utility model, the first lens L1, the fourth lens L4, the sixth lens L6, and the seventh lens L7 are spherical lenses, and the second lens L2, the third lens L3, the fifth lens L5, and the eighth lens L8 are aspherical lenses. Such a reasonable arrangement of aspherical lenses corrects various aberrations, improves the edge image quality, and has a high imaging quality.

[0044] Specifically, the second lens L1, the third lens L3, and the eighth lens L8 are plastic lenses; the first lens L1, the fourth lens L4, and the fifth lens L5 are glass lenses. The fifth lens L5 close to the aperture STO is set as a glass aspherical lens. The lens made of glass material has a smaller thermal expansion coefficient, so that the imaging is less affected by temperature changes. At the same time, the glass aspherical lens can more directly affect the light rays with large incident angles and can more effectively correct the aberrations generated therefrom. By setting the first lens L1 as a glass spherical lens, it has strong anti-corrosion and anti-scratch capabilities and can obtain a smaller head size, reducing the volume of the fish-eye lens 100. Further, in the cemented lens group, the sixth lens L6 and the seventh lens L7 are both spherical lenses and are cemented by at least two different types of optical glass through an optical adhesive, such as crown glass, flint glass, crown glass, or other special materials. In this embodiment, various aberrations are corrected by reasonably arranging the aspherical lenses, improving the edge image quality, and having a high imaging quality.

[0045] In an embodiment of the present utility model, the diameter IC of the imaging surface satisfies: IC ≤ 9.0 mm. With such a setting, the smaller diameter of the imaging surface makes the lens group design more compact, which helps to reduce the volume and weight of the lens group.

[0046] In an embodiment of the present utility model, a filter L9 and a protective glass L10 are arranged between the photosensitive chip L11 and the eighth lens L8.

[0047] Furthermore, in this embodiment, the aspherical surface shape of the aspherical lens satisfies the following conditions:

[0048]

[0049] Where Z represents the distance of the curved surface from the vertex of the curved surface in the optical axis direction, c is the curvature of the vertex of the curved surface; y is the distance from the optical axis to the curved surface; k is the conic coefficient (when the k coefficient is less than -1, the surface shape curve is a hyperbola, when the k coefficient is equal to -1, it is a parabola, when the k coefficient is between -1 and 0, it is an ellipse, when the k coefficient is equal to 0, it is a circle, and when the k coefficient is greater than 0, it is an oblate circle). A, B, C, D, E, F, G respectively represent the fourth-order, sixth-order, eighth-order, tenth-order, twelfth-order, fourteenth-order, and sixteenth-order aspherical coefficients. The shape and size of the aspherical surfaces on the object side and image side of the lens can be set through the above parameters.

[0050] Specifically, in this embodiment, the parameters of the fish-eye lens are as follows:

[0051] Focal length EFL = 1.95 mm, aperture value F = 2.0, image plane diameter 5.8 mm, diagonal field of view angle 180°.

[0052] Specifically, in an embodiment, the parameters such as the refractive index, curvature radius, and thickness interval of each lens are shown in the following table:

[0053] Table 1 Parameters of each lens in the embodiment

[0054]

[0055]

[0056] In an embodiment of the present utility model, the even-order coefficients of each aspherical surface are shown in Table 2 below:

[0057] Table 2 Conic coefficients and aspherical coefficients corresponding to the aspherical lenses in the embodiment

[0058]

[0059]

[0060] In this embodiment, the lateral chromatic aberration, ray aberration, field curvature, and distortion of the fish-eye lens are respectively as shown in Figure 2 , Figure 3 , Figure 4 . The MTF graphs at 20°C, the visible Through focus MTF graphs at 20°C, the infrared Through focus MTF graphs at 20°C, the visible Through focus MTF graphs at -20°C, and the visible Through focus MTF graphs at 60°C are respectively as shown in Figures 5 - 9 .

[0061] Figure 2 is a schematic diagram of the lateral chromatic aberration curve of the embodiment. It can be seen from Figure 2 that the lateral offset at the focal position does not exceed ±4μm, and the embodiment can effectively correct chromatic aberration and reduce the appearance of colored edges.

[0062] Figure 3 is a schematic diagram of the ray aberration curve of the embodiment. Among them, the abscissa is the normalized pupil coordinate, the ordinate is the ray aberration value, and the unit scale is 4μm. It can be seen from Figure 3 that for light rays with wavelengths of 436nm, 486nm, 546nm, 588nm, and 656nm incident within the designed pupil range, the spherical aberration of the embodiment does not exceed ±20μm. The embodiment can well correct aberration in the light ray environment with wavelengths of 436nm - 656nm and improve the image quality.

[0063] Figure 4 is a schematic diagram of the field curvature and distortion of the embodiment. It can be seen from Figure 4 that the field curvature values of the embodiment are all within the range of ±0.08mm, and both the field curvature and astigmatism are well corrected; the distortion is within 7%, and the distortion is well corrected.

[0064] Figure 5 is the MTF graph at 20°C of the embodiment. When the spatial frequency of the embodiment is 0 - 80 lp / mm, its MTF is greater than 0.5, which can well maintain the contrast of details and has very excellent imaging performance.

[0065] Figures 6 - 9 are respectively the visible Through focus MTF graph at 20°C, the infrared Through focus MTF graph at 20°C, the visible Through focus MTF graph at -20°C, and the visible Through focus MTF graph at 60°C. The embodiment has a high concentration and a low defocus amount within the temperature range of -20°C to 60°C, does not defocus within a large temperature difference range, and has a high concentration and a low defocus amount.

[0066] In summary, compared with the prior art, the present embodiment adopts a glass-plastic hybrid structure, fully utilizes the aspherical surface to reduce the volume of the optical system, and corrects chromatic aberration by bonding lenses. At the same time, by reasonably matching the lens materials, it can work stably at high and low temperatures, has a large angle, a diagonal field of view of more than 180°, high imaging quality, and CRA ≤ 12°, which can match multiple SENSORS, and has broad application prospects.

[0067] The above description is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structural transformation made under the technical concept of the present invention by using the content of the specification and drawings of the present invention, or directly / indirectly applied to other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A fisheye lens, characterized in that: The fisheye lens has an object side and an image side which are arranged opposite to each other along the optical axis direction, and comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens which are arranged in sequence from the object side to the image side along the optical axis, wherein the first lens has a negative focal power, the second lens has a negative focal power, the third lens has a negative focal power, the fourth lens has a positive focal power, the fifth lens has a positive focal power, the sixth lens has a positive focal power, the seventh lens has a negative focal power, and the eighth lens has a positive focal power; The diameter size D1 of the first lens satisfies: D1≤12 mm.

2. The fisheye lens according to claim 1, wherein: A photosensitive chip opposite to the eighth lens is disposed on the image plane side of the eighth lens, the photosensitive chip has an imaging surface close to the eighth lens, and a distance TTL between the vertex on the object plane side of the first lens and the imaging surface satisfies: TTL / EFL≤8.8; Wherein, EFL is the effective focal length of the fisheye lens.

3. The fisheye lens according to claim 2, characterized in that: A distance TTL between the object-side vertex of the first lens and the imaging plane satisfies: TTL≤17.5 mm.

4. The fisheye lens according to claim 2, wherein: An aperture is disposed between the fourth lens and the fifth lens, and a diameter d of the aperture satisfies: EFL / d≤2.

0.

5. The fisheye lens according to claim 1, wherein: The object side of the first lens is convex, the image side is concave, the focal length of the first lens is f1, and f1 satisfies: -10mm <f1<-5mm; The object side of the second lens is convex, the image side is concave, the focal length of the second lens is f2, and f2 satisfies: -7mm <f2<-3mm; The object side of the third lens is concave, the image side is convex, the focal length of the third lens is f3, and f3 satisfies: -14mm <f3<-8mm; The object side of the fourth lens is convex, the image side is convex, the focal length of the fourth lens is f4, and f4 satisfies: 3mm <f4<8mm; The object side of the fifth lens is concave, the image side is convex, the focal length of the fifth lens is f5, and f5 satisfies: 5mm <f5<8mm; The object side of the sixth lens is concave, the image side is convex, the focal length of the sixth lens is f6, and f6 satisfies: 3mm <f6<5mm; The object side of the seventh lens is concave, the image side is concave, the focal length of the seventh lens is f7, and f7 satisfies: -4mm <f7<-2mm; The object side of the eighth lens is convex, the image side is convex, the focal length of the eighth lens is f8, and f8 satisfies: 3mm <f8<7mm。 6. The fisheye lens according to claim 5, characterized in that: The sixth lens is cemented and connected to the seventh lens.

7. The fisheye lens according to claim 1, wherein: The refractive index n1 and the dispersion coefficient v1 of the first lens satisfy: 1.65≤n1≤1.80; 50.0≤v1≤70.0; The refractive index n2 and the dispersion coefficient v2 of the second lens satisfy: 1.50≤n2≤1.60; 50.0≤v2≤60.0; The refractive index n3 and the dispersion coefficient v3 of the third lens satisfy: 1.60≤n3≤1.70; 18.0≤v3≤28.0; The refractive index n4 and the dispersion coefficient v4 of the fourth lens satisfy: 1.80≤n4≤2.05; 25.0≤v4≤45.0; The refractive index n5 and the dispersion coefficient v5 of the fifth lens satisfy: 1.50≤n5≤1.65; 60.0≤v5≤75.0; The refractive index n6 and the dispersion coefficient v6 of the sixth lens satisfy: 1.50≤n6≤1.65; 60.0≤v6≤75.0; The refractive index n7 and the dispersion coefficient v7 of the seventh lens satisfy: 1.70≤n7≤1.85; 30.0≤v7≤30.0; The refractive index n8 and the dispersion coefficient v8 of the eighth lens satisfy: 1.50≤n8≤1.60; 50.0≤v8≤60.

0.

8. The fisheye lens according to any one of claims 1 to 7, characterized in that: The first lens, the fourth lens, the sixth lens, and the seventh lens are spherical lenses, and the second lens, the third lens, the fifth lens, and the eighth lens are aspherical lenses.

9. The fisheye lens according to claim 2, wherein: The diameter IC of the imaging surface satisfies: IC≤9.0 mm.

10. The fisheye lens according to claim 2, wherein: A filter and a protective glass are arranged between the photosensitive chip and the eighth lens.

Images