fisheye lens

Abstract

The application discloses a fisheye lens, which 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 arranged in sequence along an optical axis from an object plane to an image plane, the sixth lens and the seventh lens form a first cemented lens group, the eighth lens and the ninth lens form a second cemented lens group, the optical power of each lens adopts a negative-negative-negative-positive-positive-positive-negative-positive-negative collocation mode, and the first cemented lens group and the second cemented lens group are both provided with positive optical power. The fisheye lens provided in the embodiment of the application is designed in the cemented state and the optical power of the nine lenses, so that the F.NO of the fisheye lens is less than or equal to 1.85, the F-Theta distortion is less than 1.5%, and excellent imaging quality can be maintained in the imaging range of 160-200 degrees, thereby realizing the fisheye lens with a large aperture, low chromatic aberration, low distortion and high image quality.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical technology, and in particular to a fisheye lens. BACKGROUND

[0002] With the continuous development of technology and the increasing expectations of society for technological innovation, the application scenarios of optical lenses and the requirements for their imaging performance are also changing. The demand for fisheye lenses with large imaging angle range and high imaging quality is increasing in the market.

[0003] However, mainstream fisheye lenses generally have low imaging quality, large chromatic aberration, and large distortion, which restricts the application potential of fisheye lenses in emerging technology fields. SUMMARY

[0004] The present application provides a fisheye lens to achieve a fisheye lens with large aperture, low chromatic aberration, high image quality, and low distortion.

[0005] The present application provides a fisheye lens, comprising 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 arranged in order along the optical axis from the object plane to the image plane;

[0006] 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, the eighth lens has a positive focal power, and the ninth lens has a negative focal power;

[0007] The sixth lens and the seventh lens form a first cemented lens group, and the eighth lens and the ninth lens form a second cemented lens group;

[0008] The focal power of the fisheye lens is The focal power of the first lens is The focal power of the second lens is The focal power of the third lens is The focal power of the fourth lens is The focal power of the fifth lens is The focal power of the sixth lens is The focal power of the seventh lens is The focal power of the eighth lens is The focal power of the ninth lens is The focal power of the first cemented lens group is The focal power of the second cemented lens group is

[0009] Optionally, the object side surface of the first lens is convex, and the image side surface is concave.

[0010] The object side surface of the second lens is convex, and the image side surface is concave.

[0011] The object side surface of the third lens is convex or concave, and the image side surface is concave.

[0012] The object side surface of the fourth lens is concave or flat, and the image side surface is convex.

[0013] The object side surface of the fifth lens is convex, and the image side surface is convex.

[0014] Optionally, the Abbe number of the sixth lens is v6, the Abbe number of the seventh lens is v7, the Abbe number of the eighth lens is v8, and the Abbe number of the ninth lens is v9, wherein 22≤|v7-v6|≤48 and 12≤|v9-v8|≤48.

[0015] Optionally, the focal length of the fisheye lens is F, the focal length of the first cemented lens group is F67, and the focal length of the second cemented lens group is F89.

[0016] 6≤F67 / F≤8 and 8≤F89 / F≤33.

[0017] Optionally, the refractive index of the ninth lens is n9, and the Abbe number is v9.

[0018] 1.8≤n9≤2.2 and 18≤v9≤24.

[0019] Optionally, the entrance pupil diameter of the fisheye lens is EPD, and the focal length is F.

[0020] F / EPD≤1.85.

[0021] Optionally, the back focal length of the fisheye lens is BFL, the total length of the fisheye lens is TTL, and the focal length is F.

[0022] TTL / F≤15 and BFL / F≥2.16.

[0023] Optionally, the fisheye lens further comprises a diaphragm.

[0024] The diaphragm is located in the optical path between the fifth lens and the first cemented lens group.

[0025] Optionally, the focal length of the fifth lens is F5, the focal length of the first cemented lens group is F67, and the focal length of the fisheye lens is F.

[0026] 9≤F5 / F+F67 / F≤12.

[0027] Optionally, the third lens, the sixth lens and the seventh lens are all aspherical lenses, and the first lens, the second lens, the fourth lens, the fifth lens, the eighth lens and the ninth lens are all spherical lenses.

[0028] The fisheye lens provided by the embodiment of the application uses nine lenses, and the imaging quality, chromatic aberration, distortion and aperture of the fisheye lens are all improved by designing the cementing state and optical power of the nine lenses.

[0029] It should be understood that the content described in this part is not intended to identify key or important features of the embodiments of the application, nor is it used to limit the scope of the application. Other features of the application will become apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.

[0031] Figure 1 A structural schematic diagram of a fisheye lens provided by the embodiment of the application;

[0032] Figure 2 A spherical aberration curve of the fisheye lens provided by the embodiment one of the application;

[0033] Figure 3 A ray fan diagram of the fisheye lens provided by the embodiment one of the application;

[0034] Figure 4 A field curvature distortion diagram of the fisheye lens provided by the embodiment one of the application;

[0035] Figure 5 A point spread diagram of the fisheye lens provided by the embodiment one of the application;

[0036] Figure 6 A structural schematic diagram of a fisheye lens provided by the embodiment two of the application;

[0037] Figure 7 A spherical aberration curve of the fisheye lens provided by the embodiment two of the application;

[0038] Figure 8 A ray fan diagram of the fisheye lens provided for the second embodiment of the present application;

[0039] Figure 9 A field curvature distortion diagram of the fisheye lens provided for the second embodiment of the present application;

[0040] Figure 10 A point spread diagram of the fisheye lens provided for the second embodiment of the present application;

[0041] Figure 11 A structural schematic diagram of the fisheye lens provided for the third embodiment of the present application;

[0042] Figure 12 A spherical aberration curve diagram of the fisheye lens provided for the third embodiment of the present application;

[0043] Figure 13 A ray fan diagram of the fisheye lens provided for the third embodiment of the present application;

[0044] Figure 14 A field curvature distortion diagram of the fisheye lens provided for the third embodiment of the present application;

[0045] Figure 15 A point spread diagram of the fisheye lens provided for the third embodiment of the present application;

[0046] Figure 16 A structural schematic diagram of the fisheye lens provided for the fourth embodiment of the present application;

[0047] Figure 17 A spherical aberration curve diagram of the fisheye lens provided for the fourth embodiment of the present application;

[0048] Figure 18 A ray fan diagram of the fisheye lens provided for the fourth embodiment of the present application;

[0049] Figure 19 A field curvature distortion diagram of the fisheye lens provided for the fourth embodiment of the present application;

[0050] Figure 20 A point spread diagram of the fisheye lens provided for the fourth embodiment of the present application;

[0051] Figure 21 A structural schematic diagram of the fisheye lens provided for the fifth embodiment of the present application;

[0052] Figure 22 A spherical aberration curve diagram of the fisheye lens provided for the fifth embodiment of the present application;

[0053] Figure 23 A ray fan diagram of the fisheye lens provided for the fifth embodiment of the present application;

[0054] Figure 24A field curvature distortion diagram of the fisheye lens provided for the fifth embodiment of the present application is shown in the following figure;

[0055] Figure 25 A point array diagram of the fisheye lens provided for the fifth embodiment of the present application is shown in the following figure. DETAILED DESCRIPTION

[0056] In order to make the personnel in the art better understand the present application scheme, the technical scheme in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the person of ordinary skill in the art without creative labor should belong to the protection scope of the present application.

[0057] It should be noted that the terms "first", "second" and the like in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or a chronological sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0058] Figure 1 A structural schematic diagram of a fisheye lens provided for the present application embodiment is shown in the following figure, Figure 1 The fisheye lens provided by the present application embodiment comprises, in order along the optical axis from the object plane to the 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, a seventh lens L7, an eighth lens L8 and a ninth lens L9.

[0059] The first lens L1 has a negative focal power, the second lens L2 has a negative focal power, the third lens L3 has a negative focal power, the fourth lens L4 has a positive focal power, the fifth lens L5 has a positive focal power, the sixth lens L6 has a positive focal power, the seventh lens L7 has a negative focal power, the eighth lens L8 has a positive focal power, and the ninth lens L9 has a negative focal power.

[0060] The sixth lens L6 and the seventh lens L7 constitute a first cemented lens group G1, and the eighth lens L8 and the ninth lens L9 constitute a second cemented lens group G2.

[0061] The focal power of the fisheye lens is The focal power of the first lens L1 is The focal power of the second lens L2 is The focal power of the third lens L3 is The focal power of the fourth lens L4 is The focal power of the fifth lens L5 is The focal power of the sixth lens L6 is The focal power of the seventh lens L7 is The focal power of the eighth lens L8 is The focal power of the ninth lens L9 is The focal power of the first cemented lens group G1 is The focal power of the second cemented lens group G2 is Wherein:

[0062]

[0063]

[0064] Specifically, the focal power is equal to the difference between the converging degree of the image side beam and the converging degree of the object side beam, which represents the ability of the optical system to deflect light. The greater the absolute value of the focal power, the stronger the bending ability of the light, and the smaller the absolute value of the focal power, the weaker the bending ability of the light. When the focal power is positive, the refraction of the light is convergent; when the focal power is negative, the refraction of the light is divergent. The focal power can be used to represent a certain refractive surface of a lens (i.e. a surface of the lens), a certain lens, or a system formed by multiple lenses (i.e. a lens group).

[0065] In the fisheye lens provided in the embodiment, each lens can be fixed in a lens barrel (not shown in the figure), but is not limited thereto. Figure 1

[0066] Wherein, the first lens L1, the second lens L2 and the third lens L3 all adopt negative focal power, jointly bear the negative focal power of the front group, play a role in converging the light entering the fisheye lens, help more light to enter the fisheye lens, improve the light throughput of the fisheye lens, realize a larger aperture, so that a clearer image can be obtained under dim conditions. At the same time, it can also reduce the aperture size of the light in the subsequent lenses to reduce the physical size required by the subsequent lenses, which is beneficial to make the structure of the fisheye lens more compact and portable.

[0067] In addition, the first lens L1, the second lens L2 and the third lens L3 adopt negative focal power, which can also help to offset the aberration introduced by the subsequent positive focal power lens, so that the aberration distribution is balanced, thereby achieving better aberration compensation effect in the entire fisheye lens, which is beneficial to realize lower distortion and higher imaging quality. ​

[0068] With reference to the above Figure 1 The sixth lens L6 and the seventh lens L7 are cemented to form a first cemented lens group G1, and the eighth lens L8 and the ninth lens L9 are cemented to form a second cemented lens group G2, so that chromatic aberration can be minimized or eliminated, and the chromatic aberration of the fisheye lens can be fully corrected.

[0069] Meanwhile, the air gap between the sixth lens L6 and the seventh lens L7 and the air gap between the eighth lens L8 and the ninth lens L9 can be effectively reduced, so that the total length of the lens can be further reduced.

[0070] In addition, the cementing of the sixth lens L6 and the seventh lens L7 and the cementing of the eighth lens L8 and the ninth lens L9 can also reduce the assembly components between the sixth lens L6 and the seventh lens L7 and between the eighth lens L8 and the ninth lens L9, simplify the assembly procedure in the lens manufacturing process, reduce the cost, and reduce the influence of the tilt / offset tolerance of the lens caused in the assembly process on the fisheye lens, and improve the stability of the fisheye lens.

[0071] Further, the continuous strong positive or strong negative power lens will cause the light to be sharply deflected at a certain point, which not only increases the aberration, but also can cause energy loss in the light path.

[0072] In the embodiment, the focal power of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8 and the ninth lens L9 adopts a negative-negative-negative-positive-positive-positive-negative-positive-negative collocation mode, the first cemented lens group G1 and the second cemented lens group G2 are both set to positive power, and the focal power of each lens and lens group is limited, so as to reasonably distribute the focal power of each lens and lens group, so that the propagation of light in the fisheye lens is more stable, and the light will not be sharply deflected on a certain surface, thereby avoiding introducing larger aberration, ensuring large aperture and low chromatic aberration, further correcting aberration and controlling distortion, and realizing higher imaging quality.

[0073] The fisheye lens provided by the embodiment of the application uses 9 lenses, and the cementing state and the focal power of the 9 lenses are designed, so that the aperture number F.NO of the fisheye lens is less than or equal to 1.85, the F-Theta distortion is less than |1.5%|, and excellent imaging quality can be maintained in the imaging range of 160°-200°, a fisheye lens with large aperture, low chromatic aberration, low distortion and high image quality is realized, and the problem that the imaging quality, chromatic aberration, distortion and aperture of the fisheye lens cannot be considered at the same time is solved.

[0074] As a feasible implementation manner, with reference to the above Figure 1The object side of the first lens L1 is convex, the image side is concave; the object side of the second lens L2 is convex, the image side is concave; the object side of the third lens L3 is convex or concave, the image side is concave; the object side of the fourth lens L4 is concave or flat, the image side is convex; the object side of the fifth lens L5 is convex, the image side is convex.

[0075] The surface type of the lens affects the propagation direction of the light, determines how the light is bent when passing through the lens, and further affects the maximum aperture and light throughput of the lens, as well as the imaging quality and characteristics.

[0076] In this embodiment, by reasonably matching the surface types of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4 and the fifth lens L5, while meeting the requirements of the refractive power of each lens, the light path is smoother when passing through the entire optical system, unnecessary reflection and absorption are reduced, and the light throughput and imaging quality are further improved while achieving large aperture, low chromatic aberration, low distortion and high image quality.

[0077] It should be noted that the image side of the third lens L3 is concave, and the object side of the fourth lens L4 is concave or flat, so that the third lens L3 and the fourth lens L4 as a whole present a more symmetrical structure, which helps to eliminate field curvature and enable the fisheye lens to obtain clearer imaging in the entire field of view, thereby optimizing the image quality.

[0078] Further, the inventors have found through research that in a fisheye lens, due to the very large incident angle, a cemented lens cannot provide a large refractive power, which is insufficient to effectively control these light rays and guide them in the correct direction. Therefore, as shown in Figure 1 In the fisheye lens provided in the embodiment of the present application, the third lens L3 and the fourth lens L4 are not cemented, which can better control the large-angle incident light at the front end of the fisheye lens, so that the light is well converged in the first half of the fisheye lens and enters the subsequent optical system in a more orderly manner, thereby facilitating the reduction of the aperture size of the light in the subsequent lenses, reducing the physical size required by the subsequent lenses, and making the structure of the fisheye lens more compact and lightweight.

[0079] As a feasible implementation manner, the Abbe number of the sixth lens L6 is v6, the Abbe number of the seventh lens L7 is v7, the Abbe number of the eighth lens L8 is v8, and the Abbe number of the ninth lens L9 is v9, wherein 22≤|v7-v6|≤48, 12≤|v9-v8|≤48.

[0080] The Abbe number is an index used to represent the dispersion ability of a transparent medium. The more serious the dispersion of the medium, the smaller the Abbe number; on the contrary, the lighter the dispersion of the medium, the larger the Abbe number.

[0081] In the embodiment, the Abbe numbers of the sixth lens L6, the seventh lens L7, the eighth lens L8 and the ninth lens L9 are defined, the lens with high Abbe number is used in pair with the lens with low Abbe number, the dispersion effect in the whole fisheye lens can be counteracted, the imaging chromatic aberration of the fisheye lens is further balanced, and the imaging performance of the fisheye lens is improved.

[0082] As a feasible implementation, the focal length of the fisheye lens is F, the focal length of the first cemented lens group G1 is F67, and the focal length of the second cemented lens group G2 is F89, wherein 6≤F67 / F≤8 and 8≤F89 / F≤33.

[0083] In the embodiment, the focal length of the fisheye lens is F, the focal length of the first cemented lens group G1 is F67, and the focal length of the second cemented lens group G2 is F89, wherein 6≤F67 / F≤8 and 8≤F89 / F≤33.

[0084] As a feasible implementation, the refractive index of the ninth lens L9 is n9, and the Abbe number is v9, wherein 1.8≤n9≤2.2 and 18≤v9≤24.

[0085] The refractive index is the ratio of the propagation speed of light in vacuum to the propagation speed of light in the medium, which is mainly used to describe the refractive ability of the material to light, and the refractive index of different materials is different.

[0086] In the embodiment, the ninth lens L9 is located at the end of the fisheye lens, and the ninth lens L9 adopts a material with high refractive index, which can more effectively bend the light, thereby effectively controlling the incident angle of the light entering the imaging chip, avoiding the situation that the incident angle of the light entering the imaging chip is too large due to the too large divergence angle of the light after passing through the ninth lens L9, and ensuring that the light is more uniformly distributed on the imaging chip, thereby avoiding the situation that the light at the edge cannot be captured by the imaging chip due to the too large incident angle, thereby improving the brightness uniformity and clarity of the whole picture. Moreover, by using the material with high refractive index for the ninth lens L9 to reduce the incident angle of the light entering the imaging chip, the light can be more vertically irradiated to the surface of the imaging chip, the compatibility of the fisheye lens with various imaging chips can be improved, and the fisheye lens can be adapted to more imaging chips.

[0087] Meanwhile, the ninth lens L9 adopts a material with low Abbe number, and the ninth lens L9 and the eighth lens L8 are cemented to form the second cemented lens group G2, which is conducive to counteracting the dispersion effect, thereby effectively correcting the chromatic aberration and improving the color accuracy of the imaging. Further, by carefully matching the refractive index and Abbe number of the eighth lens L8 and the ninth lens L9, the correction of the aberration is also facilitated, and the imaging quality is improved.

[0088] As a feasible implementation, the entrance pupil diameter of the fisheye lens is EPD, and the focal length is F, wherein F / EPD≤1.85.

[0089] The aperture size of the fisheye lens is generally determined by the ratio of the entrance pupil diameter and the focal length, wherein the fisheye lens has a larger aperture when the entrance pupil diameter is larger under the condition of a certain focal length.

[0090] The fisheye lens provided by the embodiment of the present application has an entrance pupil diameter EPD and a focal length F satisfying F / EPD≤1.85, which indicates that the fisheye lens has a larger aperture, so that the fisheye lens can ensure a larger light quantity and realize clear imaging when working at night.

[0091] As a feasible implementation, the back focal length of the fisheye lens is BFL, the total length of the fisheye lens is TTL, and the focal length is F, wherein TTL / F≤15 and BFL / F≥2.16.

[0092] The back focal length BFL of the fisheye lens refers to the distance from the optical axis center of the image side of the ninth lens L9 to the image plane, and the total length TTL of the fisheye lens refers to the distance from the optical axis center of the object side of the first lens L1 to the image plane.

[0093] The fisheye lens provided by the embodiment of the present application has a low ratio of the total length TTL to the focal length F, so that the volume of the fisheye lens is further reduced, which is beneficial to the miniaturization of the fisheye lens.

[0094] Meanwhile, the fisheye lens has a large ratio of the back focal length BFL to the focal length F, which can provide sufficient space for the rear end structure of the fisheye lens, is beneficial to the assembly of the fisheye lens, improves the production brightness, and reduces the cost.

[0095] As a feasible implementation, with reference to Figure 1 , the fisheye lens further comprises a stop STO, and the stop STO is located in the optical path between the fifth lens L5 and the first cemented lens group G1.

[0096] The stop STO can determine the aperture size of the fisheye lens, and also affects the generation and control of aberration.

[0097] In the embodiment, the stop STO is arranged at a position close to the middle, i.e., between the fifth lens L5 and the first cemented lens group G1, so that the incident angle and distribution of light can be more effectively controlled, thereby greatly reducing the coma generated by the fisheye lens.

[0098] As a feasible implementation, the focal length of the fifth lens L5 is F5, the focal length of the first cemented lens group G1 is F67, and the focal length of the fisheye lens is F, wherein 9≤F5 / F+F67 / F≤12.

[0099] Wherein, by limiting and reasonably matching the relationship between the focal length of the fifth lens L5 and the first cemented lens group G1 near the light barrier STO and the focal length F of the entire fisheye lens, the path of the light passing through the light barrier STO is adjusted, which can balance the aberration generated when the light passes through the light barrier STO, and improve the imaging quality.

[0100] As a feasible implementation, the third lens L3, the sixth lens L6 and the seventh lens L7 are all aspherical lenses, and the first lens L1, the second lens L2, the fourth lens L4, the fifth lens L5, the eighth lens L8 and the ninth lens L9 are all spherical lenses.

[0101] Wherein, the aspherical lens can significantly reduce the spherical aberration and coma aberration and improve the imaging quality of the entire fisheye lens.

[0102] In the embodiment, the third lens L3, the sixth lens L6 and the seventh lens L7 are aspherical lenses, which are arranged at the key positions in the fisheye lens, which helps to more effectively control the light and reduce the aberration, thereby improving the imaging performance of the entire fisheye lens.

[0103] And, due to the good aberration correction ability of the above-mentioned aspherical lens, the total number of lenses required in the fisheye lens is reduced, thereby simplifying the lens design, reducing the weight and reducing the volume.

[0104] Further, the above-mentioned aspherical lens can be made of plastic material, which can realize lower cost compared with glass lens, and the plastic lens is easier to make into a complex aspherical shape.

[0105] At the same time, the first lens L1, the second lens L2, the fourth lens L4, the fifth lens L5, the eighth lens L8 and the ninth lens L9 are spherical lenses, which helps to reduce the cost and is easy to manufacture.

[0106] Further, the above-mentioned spherical lens can be a glass spherical lens, wherein the glass lens has higher transmittance, which can reduce the loss of light energy and make the light energy received by the imaging chip higher. In the embodiment, the first lens L1, the second lens L2, the fourth lens L4, the fifth lens L5, the eighth lens L8 and the ninth lens L9 are glass spherical lenses, which can make the fisheye lens have better imaging effect in dark environment.

[0107] At the same time, the glass lens has the advantages of high hardness, strong wear resistance, long service life and not easy to be deformed by temperature, thereby making the performance of the fisheye lens more stable.

[0108] It should be noted that in the embodiment, six glass spherical lenses and three plastic aspherical lenses are combined to realize a fisheye lens with large aperture, high image quality and low distortion. By reasonably distributing the positions of the aspherical lenses and the spherical lenses, the optical quality of the fisheye lens can be significantly improved, and the cost and weight can be controlled, so that the fisheye lens becomes a fisheye lens product with high performance and economic practicability.

[0109] As a feasible implementation manner, as shown in Figure 1 The fisheye lens further includes a filter P located on the image side of the ninth lens L9. The filter P can filter out unnecessary stray light, thereby further improving the image quality of the fisheye lens. Meanwhile, the filter P can also protect the imaging chip.

[0110] The specific embodiments of the fisheye lens applicable to the above-mentioned embodiments will be further described below with reference to the accompanying drawings.

[0111] Embodiment one

[0112] Continuing to refer to Figure 1 The fisheye lens provided by the embodiment one of the present application includes, in order along the optical axis from the object plane to the 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, a seventh lens L7, an eighth lens L8 and a ninth lens L9.

[0113] The first lens L1 is a meniscus negative lens, the second lens L2 is a meniscus negative lens, the third lens L3 is a double-concave negative lens, the fourth lens L4 is a meniscus positive lens, the fifth lens L5 is a double-convex positive lens, the sixth lens L6 is a meniscus positive lens, the seventh lens L7 is a meniscus negative lens, the eighth lens L8 is a double-convex positive lens, and the ninth lens L9 is a meniscus negative lens.

[0114] The sixth lens L6 and the seventh lens L7 form a first cemented lens group G1, and the eighth lens L8 and the ninth lens L9 form a second cemented lens group G2.

[0115] The diaphragm STO is located in the optical path between the fifth lens L5 and the first cemented lens group G1, and the filter P is located on the image side of the ninth lens L9.

[0116] Table 1 details the specific optical and physical parameters of each lens in the fisheye lens provided by the embodiment one of the present application in a feasible implementation manner. The fisheye lens in Table 1 corresponds to the fisheye lens shown in Figure 1 .

[0117] Table 1 Design values of optical and physical parameters of the fisheye lens

[0118]

[0119]

[0120] In the table 1, the surface serial number is numbered according to the surface sequence of each lens, for example, the surface serial number "SI" represents the object side surface of the first lens, the surface serial number "S2" represents the image side surface of the first lens, and so on; "STO" represents the diaphragm of the lens; the radius of curvature represents the bending degree of the lens surface, the positive value represents that the surface bends to the object side, the center is close to the image, the negative value represents that the surface bends to the image side, the center is close to the object, and "INF" represents that the surface is a plane, the radius of curvature is infinite; the thickness represents the center axial distance from the current surface to the next surface, wherein, due to the different number of parameter values, there is an error in focusing, so the thickness of the 19th surface (i.e. S19) has a certain range, and the value can be adjusted to achieve the purpose of clear focusing; the material (nd) represents the refractive index, i.e. the deflection ability of the material between the current surface and the next surface to the light, and the space represents that the current position is air, and the refractive index is 1; the material (vd) represents the Abbe number, i.e. the dispersion characteristic of the material between the current surface and the next surface to the light, and the space represents that the current position is air. The half diameter represents the half aperture of the lens.

[0121] Further, the third lens L3, the sixth lens L6 and the seventh lens L7 are aspherical lenses.

[0122] In the embodiment, the surface type of the aspherical lens in the fisheye lens can meet the following formula:

[0123]

[0124] Wherein, Z is the sag of the aspherical surface, c is the basic curvature at the vertex, k is the conic constant, r is the radial coordinate perpendicular to the optical axis, a i is the high order coefficient, a i r 2i is the high order term of the aspherical surface.

[0125] For example, the table 2 details the aspherical coefficients of each lens in embodiment I in a possible implementation manner.

[0126] Table 2: Design values of aspherical coefficients of each lens in fisheye lens

[0127]

[0128] The fisheye lens provided by embodiment I meets the following technical indexes:

[0129] Focal length: F = 1.95 mm;

[0130] F-number: F.NO = 1.85;

[0131] Field of view: 190°;

[0132] Optical total length: 29mm;

[0133] Image surface size: φ6.4mm.

[0134] Figure 2 A ball aberration curve of the fisheye lens provided in the first embodiment of the present application, wherein the vertical direction represents a normalized pupil coordinate, 0 represents a pupil center, the vertical direction top represents a pupil vertex, and the horizontal direction is the spherical aberration of different wavelengths, in units of millimeters (mm); different linear curves in the figure represent different wavelengths of the fisheye lens imaging. As shown in the figure, the pupil radius is 0.5267mm, and the spherical aberration under different wavelengths (0.436μm, 0.470μm, 0.486μm, 0.546μm, 0.587μm and 0.656μm) is within ±0.01mm, and the different wavelength curves are relatively concentrated, which indicates that the axial aberration of the fisheye lens is very small, so it can be known that the fisheye lens can better correct aberration. Figure 2

[0135] Figure 3 A ray fan diagram of the fisheye lens provided in the first embodiment of the present application, wherein the horizontal axis represents the distance of the light ray deviating from the center of the entrance pupil when passing through the entrance pupil, and the vertical axis represents the distance of the corresponding light ray deviating from the chief ray on the image surface, and it should be noted that the chief ray is the light ray passing through the center of the entrance pupil. The most ideal curve is a straight line coinciding with the horizontal coordinate, at this time it is indicated that all light rays converge to the same point on the image surface. As shown in the figure, Figure 3 It can be seen that the curves under each field of view are gentle, which represents that the aberration of the fisheye lens is well corrected.

[0136] Figure 4 A field curvature distortion diagram of the fisheye lens provided in the first embodiment of the present application, in the left coordinate system, the horizontal coordinate represents the size of the field curvature, in units of millimeters (mm); the vertical coordinate represents the normalized image height, without unit; from Figure 4 It can be seen that the fisheye lens provided in the present embodiment effectively controls the light with a wavelength of 0.436μm to 0.656μm on the field curvature, and ensures that the center image quality and the peripheral image quality are relatively small when imaging. In the right coordinate system, the horizontal coordinate represents the size of the F-Theta distortion, in units of %; the vertical coordinate represents the normalized image height, without unit; from Figure 4 It can be seen that the fisheye lens provided in the present embodiment is effectively controlled.

[0137] Figure 5 ​The point spread diagram of the fisheye lens provided by the embodiment one of the present application is shown in FIG. 1. The point spread diagram refers to a dispersion diagram of a plurality of light rays emitted by a point light source after passing through an optical system, and the intersection points of the light rays with an image plane are no longer concentrated at the same point due to aberration, thereby forming a dispersion diagram scattered in a certain range. The distribution of points in the point spread diagram can approximately represent the concentration degree of the light rays, and reflect the imaging quality of the system. As shown in FIG. 1, the dispersion diagram of the light rays (0.436 μm-0.656 μm) under each field of view is relatively concentrated, and the root mean square radius (RMS radius) of the light rays at each field of view is 0.512 μm, 0.504 μm, 0.529 μm, 0.639 μm, 0.734 μm, 0.724 μm, 0.682 μm, 0.776 μm, 0.833 μm, 0.713 μm and 0.924 μm, respectively. The RMS radius of each field of view is less than 1 μm, indicating that the fisheye lens has low chromatic aberration and aberration under the full field of view, and can realize high-resolution imaging. Figure 5

[0138] Embodiment two

[0139] Figure 6 The structural schematic diagram of the fisheye lens provided by the embodiment two of the present application is shown in FIG. 2. The fisheye lens provided by the embodiment two of the present application comprises, in sequence along the optical axis from the object plane to the 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, a seventh lens L7, an eighth lens L8 and a ninth lens L9. Figure 6

[0140] The first lens L1 is a meniscus negative lens, the second lens L2 is a meniscus negative lens, the third lens L3 is a double-concave negative lens, the fourth lens L4 is a meniscus positive lens, the fifth lens L5 is a double-convex positive lens, the sixth lens L6 is a meniscus positive lens, the seventh lens L7 is a meniscus negative lens, the eighth lens L8 is a double-convex positive lens, and the ninth lens L9 is a meniscus negative lens.

[0141] The sixth lens L6 and the seventh lens L7 constitute a first cemented lens group G1, and the eighth lens L8 and the ninth lens L9 constitute a second cemented lens group G2.

[0142] The diaphragm STO is located in the optical path between the fifth lens L5 and the first cemented lens group G1, and the filter P is located on the image side of the ninth lens L9.

[0143] Table 3 details the specific optical physical parameters of each lens in the fisheye lens provided by the embodiment two of the present application in a feasible implementation manner.

[0144] Table 3 Design values of optical physical parameters of fisheye lens

[0145] ​​

[0146]

[0147] In Table 3, the surface serial number is numbered according to the surface sequence of each lens, for example, the surface serial number "S1" represents the object side surface of the first lens, the surface serial number "S2" represents the image side surface of the first lens, and so on; "STO" represents the diaphragm of the lens; the radius of curvature represents the bending degree of the lens surface, a positive value represents that the surface bends to the object side, the center is close to the image side, a negative value represents that the surface bends to the image side, the center is close to the object side, and "INF" represents that the surface is a plane, the radius of curvature is infinite; the thickness represents the center axial distance from the current surface to the next surface; because the number of digits of each parameter is different, there is an error in focusing, so the thickness of the 19th surface (S19) has a certain range, which can be adjusted according to the situation to achieve the purpose of clear focusing; the material (nd) represents the refractive index, that is, the deflection ability of the material between the current surface and the next surface to the light; the space represents that the current position is air, and the refractive index is 1; the material (vd) represents the Abbe number, that is, the dispersion characteristic of the material between the current surface and the next surface to the light; the space represents that the current position is air. The half diameter represents the half aperture of the lens.

[0148] Further, the third lens L3, the sixth lens L6 and the seventh lens L7 are aspherical lenses.

[0149] In the embodiment, the surface type of the aspherical lens in the fisheye lens can satisfy the following formula:

[0150]

[0151] Wherein, Z is the sag of the aspherical surface, c is the basic curvature at the vertex, k is the conic constant, r is the radial coordinate perpendicular to the optical axis, a i is the high-order coefficient of the aspherical surface, a i r 2i is the high-order term of the aspherical surface.

[0152] For example, Table 4 details the aspherical coefficients of each lens in the second embodiment in a possible implementation manner.

[0153] Table 4: Design values of aspherical coefficients of each lens in the fisheye lens

[0154]

[0155]

[0156] The fisheye lens provided in the second embodiment achieves the following technical indicators:

[0157] Focal length: 1.95mm;

[0158] Aperture: F1.85;

[0159] Field of view: 190°;

[0160] Overall optical length: 29mm;

[0161] Image size: φ6.4mm.

[0162] Figure 7 This is a spherical aberration curve diagram of a fisheye lens provided in Embodiment 2 of the present invention. In the diagram, the vertical direction represents the normalized pupil coordinates, 0 represents the pupil center, the vertical vertex represents the pupil vertex, and the horizontal direction represents the spherical aberration of different wavelengths, in millimeters (mm). Different linear curves in the diagram represent different wavelengths of image formation by the fisheye lens. Figure 7 As shown, the pupil radius is 0.5266 mm, and the spherical aberration at different wavelengths (0.436 μm, 0.470 μm, 0.486 μm, 0.546 μm, 0.587 μm and 0.656 μm) is within ±0.01 mm. The curves for different wavelengths are relatively concentrated, indicating that the axial aberration of this fisheye lens is very small. Therefore, it can be concluded that this fisheye lens can correct aberrations well.

[0163] Figure 8 This is a ray fan diagram of a fisheye lens provided in Embodiment 2 of the present invention. In the diagram, the horizontal axis represents the distance a ray deviates from the center of the entrance pupil when it passes through the pupil, and the vertical axis represents the distance the corresponding ray deviates from the principal ray on the image plane. It should be noted that the principal ray is the ray that passes through the center of the entrance pupil. Ideally, each curve is a straight line coinciding with the horizontal axis, indicating that all rays converge at the same point on the image plane. For example... Figure 8 It can be seen that the curves are flat in each field of view, which means that the aberrations of the fisheye lens have been well corrected.

[0164] Figure 9 This is a field curvature distortion diagram of a fisheye lens provided in Embodiment 2 of the present invention. In the coordinate system on the left side of the diagram, the horizontal coordinate represents the magnitude of the field curvature, in millimeters (mm); the vertical coordinate represents the normalized image height, which has no unit. Figure 9 It can be seen that the fisheye lens provided in this embodiment effectively controls the field curvature for light with wavelengths from 0.436 μm to 0.656 μm, ensuring a small difference in image quality between the center and the periphery during imaging. In the coordinate system on the right, the horizontal axis represents the magnitude of F-Theta distortion, expressed as a percentage; the vertical axis represents the normalized image height, which has no unit. Figure 9 It can be seen that the distortion of the fisheye lens provided in this embodiment has been effectively controlled.

[0165] Figure 10This is a dot plot of a fisheye lens provided in Embodiment 2 of the present invention. A dot plot refers to the pattern formed by the dispersion of light rays emitted from a single light source across a certain range. Due to aberrations, the intersection points of these rays with the image plane are no longer concentrated at a single point, but rather form a diffuse pattern. The distribution of points in the dot plot can approximately represent the degree of light concentration and reflect the imaging quality of the system. For example... Figure 10 As shown, the dispersion pattern of the light rays (0.436μm to 0.656μm) is relatively concentrated in each field of view. Meanwhile, the root mean square radius (RMS radius) of the light rays at each field of view is 0.466μm, 0.414μm, 0.448μm, 0.690μm, 0.941μm, 0.894μm, 0.681μm, 0.567μm, 0.577μm, 0.665μm and 1.076μm, respectively. The RMS radius of each field of view is less than 1.1μm, indicating that the fisheye lens has low chromatic aberration and aberrations in the entire field of view and can achieve high-resolution imaging.

[0166] Example 3

[0167] Figure 11 This is a schematic diagram of the structure of the fisheye lens provided in Embodiment 3 of the present invention, as shown below. Figure 11 As shown, the fisheye lens provided in Embodiment 3 of the present invention includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, and a ninth lens L9 arranged sequentially along the optical axis from the object plane to the image plane.

[0168] The first lens L1 is a meniscus negative lens, the second lens L2 is a meniscus negative lens, the third lens L3 is a meniscus negative lens, the fourth lens L4 is a plano-convex positive lens, the fifth lens L5 is a biconvex positive lens, the sixth lens L6 is a meniscus positive lens, the seventh lens L7 is a meniscus negative lens, the eighth lens L8 is a biconvex positive lens, and the ninth lens L9 is a meniscus negative lens.

[0169] The sixth lens L6 and the seventh lens L7 form the first cemented lens group G1, and the eighth lens L8 and the ninth lens L9 form the second cemented lens group G2.

[0170] The aperture stop STO is located in the optical path between the fifth lens L5 and the first cemented lens group G1, and the filter P is located on the image side of the ninth lens L9.

[0171] Table 5 details the specific optical physical parameters of each lens in the fisheye lens provided in Embodiment 3 of the present invention, according to a feasible implementation method.

[0172] Table 5 Design values ​​of optical physical parameters for fisheye lenses

[0173] Surface type Radius of curvature Thickness Material (nd) Material (vd) Half-diameter S1 Sphere 27.6742 2.8733 1.51 80.5 14.022 S2 Sphere 9.4530 1.9844 7.579 S3 Sphere 13.9810 1.0315 1.75 68.7 6.983 S4 Sphere 4.4422 3.0315 4.266 S5 Asphere 18.1310 0.7310 1.53 70 3.909 S6 Asphere 2.6172 1.9345 2.900 S7 Sphere INF 1.9705 1.86 26.9 2.869 S8 Sphere -10.2141 1.9966 2.782 S9 Sphere 24.1468 2.0227 1.68 54.9 2.001 S10 Sphere -6.0958 0.4189 1.995 STO Sphere INF 0.7095 1.693 S12 Asphere -9.5032 1.3004 1.53 60.4 1.874 S13 Asphere -2.7786 1.1399 1.63 21.5 1.992 S14 Asphere -4.4369 0.0817 2.230 S15 Sphere 24.4624 2.0005 1.59 57 2.374 S16 Sphere -3.0272 1.5502 1.92 22.4 2.456 S17 Sphere -6.8115 1.2920 2.967 S18 Sphere INF 0.7100 1.52 64.2 3.127 S19 Sphere INF 2.2211 IMA Sphere INF

[0174] In Table 5, the surface serial number is numbered according to the surface sequence of each lens, for example, the surface serial number "SI" represents the object side surface of the first lens, the surface serial number "S2" represents the image side surface of the first lens, and so on; "STO" represents the diaphragm of the lens; the radius of curvature represents the bending degree of the lens surface, a positive value represents that the surface bends to the object side, the center is close to the image, and a negative value represents that the surface bends to the image side, the center is close to the object; "INF" represents that the surface is a plane, and the radius of curvature is infinite; the thickness represents the center axial distance from the current surface to the next surface; because the number of digits of each parameter is different, there is an error in focusing, so the thickness of the 19th surface (S19) has a certain range, and the value can be adjusted as needed to achieve the purpose of clear focusing; the material (nd) represents the refractive index, i.e. the deflection ability of the material between the current surface and the next surface to the light; the space represents that the current position is air, and the refractive index is 1; the material (vd) represents the Abbe number, i.e. the dispersion characteristic of the material between the current surface and the next surface to the light; the half diameter represents the half aperture of the lens.

[0175] Further, the third lens L3, the sixth lens L6 and the seventh lens L7 are aspherical lenses.

[0176] In this embodiment, the surface type of the aspherical lens in the fisheye lens can satisfy the following formula:

[0177]

[0178] Wherein, Z is the sag of the aspherical surface, c is the basic curvature at the vertex, k is the conic constant, r is the radial coordinate perpendicular to the optical axis, a i is the high-order coefficient, a i r 2i is the high-order term of the aspherical surface.

[0179] For example, Table 6 details the aspherical coefficients of each lens in this embodiment three in a possible implementation manner.

[0180] Table 6: Design values of aspherical coefficients of each lens in the fisheye lens

[0181]

[0182] The fisheye lens provided in embodiment three achieves the following technical indicators:

[0183] Focal length: 1.95mm;

[0184] Aperture: F1.85;

[0185] Field of view: 190°;

[0186] Optical total length: 29mm;

[0187] Image surface size: φ6.4mm.

[0188] Figure 12 A ball aberration curve of the fisheye lens provided in the third embodiment of the present application is shown in the figure, wherein the vertical direction represents a normalized pupil coordinate, 0 represents a pupil center, the vertical direction top represents a pupil vertex, and the horizontal direction is the spherical aberration of different wavelengths, in millimeters (mm); different linear curves in the figure represent different wavelengths of the fisheye lens imaging. As shown in the figure, the pupil radius is 0.5261mm, the spherical aberration under different wavelengths (0.436μm, 0.470μm, 0.486μm, 0.546μm, 0.587μm and 0.656μm) is within ±0.02mm, and the different wavelength curves are relatively concentrated, which indicates that the axial aberration of the fisheye lens is very small, and thus it can be known that the fisheye lens can correct aberration well. Figure 12

[0189] Figure 13 A ray fan diagram of the fisheye lens provided in the third embodiment of the present application is shown in the figure, wherein the horizontal axis represents the distance of the light ray deviating from the center of the entrance pupil when passing through the entrance pupil, and the vertical axis represents the distance of the corresponding light ray deviating from the chief ray on the image surface. It should be noted that the chief ray is the light ray passing through the center of the entrance pupil. The most ideal curve is a straight line coinciding with the horizontal coordinate, at this time it indicates that all light rays converge to the same point on the image surface. As shown in the figure,It can be known that the curves under each field of view are gentle, which represents that the aberration of the fisheye lens is well corrected. Figure 13

[0190] Figure 14 A field curvature distortion diagram of the fisheye lens provided in the third embodiment of the present application is shown in the figure, in the left coordinate system, the horizontal coordinate represents the size of the field curvature, in millimeters (mm); the vertical coordinate represents the normalized image height, without unit; as shown in the figure,It can be seen that the fisheye lens provided in the embodiment effectively controls the light with a wavelength of 0.436μm to 0.656μm on the field curvature, and ensures that the central image quality and the peripheral image quality are small when imaging. In the right coordinate system, the horizontal coordinate represents the size of the F-Theta distortion, in %; the vertical coordinate represents the normalized image height, without unit; as shown in the figure,It can be seen that the fisheye lens provided in the embodiment effectively controls the distortion. Figure 14 Figure 14

[0191] Figure 15 A point spread diagram of the fisheye lens provided in the third embodiment of the present application is shown in the figure, the point spread diagram refers to a diffused pattern formed by a point light source emitting many light rays after passing through the optical system, and the intersection points of the light rays on the image surface are no longer concentrated on the same point due to aberration. The distribution of points in the point spread diagram can approximately represent the concentration degree of the light rays, and reflect the imaging quality of the system. As shown in the figure,​Figure 15 As shown in the figure, the dispersion pattern of the light rays (0.436 μm-0.656 μm) under each field of view is relatively concentrated, and the root mean square radius (RMS radius) of the light rays at each field of view is 1.149 μm, 1.223 μm, 1.516 μm, 2.209 μm, 3.286 μm, 2.692 μm, 2.120 μm, 2.181 μm, 2.574 μm, 2.807 μm and 2.519 μm, respectively, and the RMS radius of each field of view is less than 3.5 μm, indicating that the fisheye lens has low chromatic aberration and aberration under the full field of view, and can realize high-resolution imaging.

[0192] Example Four

[0193] Figure 16 The structural schematic diagram of the fisheye lens provided by Example Four of the present application is shown in the figure, Figure 16 As shown in the figure, the fisheye lens provided by Example Four of the present application includes first lens L1, second lens L2, third lens L3, fourth lens L4, fifth lens L5, sixth lens L6, seventh lens L7, eighth lens L8 and ninth lens L9 arranged in order along the optical axis from the object plane to the image plane.

[0194] The first lens L1 is a meniscus negative lens, the second lens L2 is a meniscus negative lens, the third lens L3 is a double-concave negative lens, the fourth lens L4 is a meniscus positive lens, the fifth lens L5 is a double-convex positive lens, the sixth lens L6 is a meniscus positive lens, the seventh lens L7 is a meniscus negative lens, the eighth lens L8 is a double-convex positive lens, and the ninth lens L9 is a meniscus negative lens.

[0195] The sixth lens L6 and the seventh lens L7 form a first cemented lens group G1, and the eighth lens L8 and the ninth lens L9 form a second cemented lens group G2.

[0196] The diaphragm STO is located in the optical path between the fifth lens L5 and the first cemented lens group G1, and the filter P is located on the image side of the ninth lens L9.

[0197] Table 7 details the specific optical and physical parameters of each lens in the fisheye lens provided by Example Four of the present application in a feasible implementation manner.

[0198] Table 7 Design values of optical and physical parameters of fisheye lens

[0199]

[0200]

[0201] In the table 7, the surface serial number is numbered according to the surface sequence of each lens, for example, the surface serial number "S1" represents the object side surface of the first lens, the surface serial number "S2" represents the image side surface of the first lens, and so on; "STO" represents the diaphragm of the lens; the radius of curvature represents the bending degree of the lens surface, the positive value represents that the surface bends to the object side, the center is close to the image, the negative value represents that the surface bends to the image side, the center is close to the object, and "INF" represents that the surface is a plane, the radius of curvature is infinite; the thickness represents the center axial distance from the current surface to the next surface, wherein, because the parameter value has different number of digits, there is an error in focusing, so the thickness of the 19th surface (S19) has a certain range, and the value can be adjusted to achieve the purpose of clear focusing; the material (nd) represents the refractive index, that is, the deflection ability of the material between the current surface and the next surface to the light; the space represents that the current position is air, and the refractive index is 1; the material (vd) represents the Abbe number, that is, the dispersion characteristic of the material between the current surface and the next surface to the light, and the space represents that the current position is air. The half diameter represents the half aperture of the lens.

[0202] Further, the third lens L3, the sixth lens L6 and the seventh lens L7 are aspherical lenses.

[0203] In the embodiment, the surface type of the aspherical lens in the fisheye lens can meet the following formula:

[0204]

[0205] Wherein, Z is the sag of the aspherical surface, c is the basic curvature at the vertex, k is the conic constant, r is the radial coordinate perpendicular to the optical axis, a i is the high order coefficient, a i r 2i is the high order term of the aspherical surface.

[0206] For example, the table 8 details the aspherical coefficients of each lens in the fourth embodiment in a feasible implementation manner.

[0207] Table 8: Design values of aspherical coefficients of each lens in the fisheye lens

[0208]

[0209] The fisheye lens provided in the fourth embodiment achieves the following technical indexes:

[0210] Focal length: 1.95mm;

[0211] Aperture: F1.85;

[0212] Field of view: 190°;

[0213] Total optical length: 28.9mm;

[0214] Image surface size: φ6.4mm.

[0215] Figure 17 A ball aberration curve of the fisheye lens provided in the fourth embodiment of the present application is shown in the figure, wherein the vertical direction represents a normalized pupil coordinate, 0 represents a pupil center, the vertical direction vertex represents a pupil vertex, and the horizontal direction represents the spherical aberration of different wavelengths in millimeters (mm); different linear curves in the figure represent different wavelengths of the fisheye lens imaging. As shown in the figure, the pupil radius is 0.5269mm, the spherical aberration under different wavelengths (0.436μm, 0.470μm, 0.486μm, 0.546μm, 0.587μm and 0.656μm) is within the range of ±0.01mm, and the different wavelength curves are relatively concentrated, which indicates that the axial aberration of the fisheye lens is very small, and thus it can be known that the fisheye lens can better correct the aberration. Figure 17

[0216] Figure 18 A ray fan diagram of the fisheye lens provided in the fourth embodiment of the present application is shown in the figure, wherein the horizontal axis represents the distance of the light ray deviating from the center of the entrance pupil when passing through the entrance pupil, and the vertical axis represents the distance of the corresponding light ray deviating from the chief ray on the image surface. It should be noted that the chief ray is the light ray passing through the center of the entrance pupil. The most ideal curve is a straight line coinciding with the horizontal coordinate, at this time it indicates that all light rays converge to the same point on the image surface. As shown in the figure,It can be known that the curves under each field of view are gentle, which represents that the aberration of the fisheye lens is better corrected. Figure 18

[0217] Figure 19 A field curvature distortion diagram of the fisheye lens provided in the fourth embodiment of the present application is shown in the figure, in the left coordinate system, the horizontal coordinate represents the size of the field curvature in millimeters (mm); the vertical coordinate represents the normalized image height without unit; as shown in the figure,It can be seen that the fisheye lens provided in the embodiment effectively controls the light with a wavelength of 0.436μm to 0.656μm on the field curvature, and ensures that the central image quality and the peripheral image quality are relatively small when imaging. In the right coordinate system, the horizontal coordinate represents the size of the F-Theta distortion in %; the vertical coordinate represents the normalized image height without unit; as shown in the figure,It can be seen that the fisheye lens provided in the embodiment effectively controls the distortion. Figure 19 Figure 19

[0218] Figure 20 A point spread diagram of the fisheye lens provided in the fourth embodiment of the present application is shown in the figure, the point spread diagram refers to a diffuse pattern formed by a point light source emitting many light rays after passing through the optical system, and the intersection points of the light rays on the image surface are no longer concentrated on the same point due to aberration. The distribution of points in the point spread diagram can approximately represent the concentration degree of light rays, and reflect the imaging quality of the system. As shown in the figure, Figure 20 ​As shown, the dispersion patterns of light rays (0.436 μm-0.656 μm) under each field of view are relatively concentrated, and the root mean square radius (RMS radius) of the light rays at each field of view is 0.806 μm, 0.834 μm, 0.978 μm, 1.193 μm, 1.273 μm, 1.248 μm, 1.011 μm, 0.928 μm, 1.094 μm, 1.165 μm and 1.265 μm, respectively. The RMS radius of each field of view is less than 1.5 μm, indicating that the fisheye lens has low chromatic aberration and aberration under the full field of view, and can realize high-resolution imaging.

[0219] Example Five

[0220] Figure 21 The structural schematic diagram of the fisheye lens provided by Example Five of the present application is shown in Figure 21 As shown, the fisheye lens provided by Example Five of the present application comprises, in order along the optical axis from the object plane to the 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, a seventh lens L7, an eighth lens L8 and a ninth lens L9.

[0221] The first lens L1 is a meniscus negative lens, the second lens L2 is a meniscus negative lens, the third lens L3 is a double-concave negative lens, the fourth lens L4 is a meniscus positive lens, the fifth lens L5 is a double-convex positive lens, the sixth lens L6 is a meniscus positive lens, the seventh lens L7 is a meniscus negative lens, the eighth lens L8 is a double-convex positive lens, and the ninth lens L9 is a meniscus negative lens.

[0222] The sixth lens L6 and the seventh lens L7 form a first cemented lens group G1, and the eighth lens L8 and the ninth lens L9 form a second cemented lens group G2.

[0223] The diaphragm STO is located in the optical path between the fifth lens L5 and the first cemented lens group G1, and the filter P is located on the image side of the ninth lens L9.

[0224] Table 9 details the specific optical and physical parameters of each lens in the fisheye lens provided by Example Five of the present application in one possible implementation.

[0225] Table 9 Design values of optical and physical parameters of the fisheye lens

[0226]

[0227]

[0228] In the table 9, the surface serial number is numbered according to the surface sequence of each lens, for example, the surface serial number "S1" represents the object side surface of the first lens, the surface serial number "S2" represents the image side surface of the first lens, and so on; "STO" represents the diaphragm of the lens; the radius of curvature represents the bending degree of the lens surface, the positive value represents that the surface bends to the object side, the center is close to the image, the negative value represents that the surface bends to the image side, the center is close to the object, and "INF" represents that the surface is a plane, the radius of curvature is infinite; the thickness represents the center axial distance from the current surface to the next surface, wherein, because the parameter values are different, there is an error in focusing, so the thickness of the 19th surface (S19) has a certain range, and the value can be adjusted to achieve the purpose of clear focusing; the material (nd) represents the refractive index, that is, the deflection ability of the material between the current surface and the next surface to the light; the space represents that the current position is air, and the refractive index is 1; the material (vd) represents the Abbe number, that is, the dispersion characteristic of the material between the current surface and the next surface to the light, and the space represents that the current position is air. The half diameter represents the half aperture of the lens.

[0229] Further, the third lens L3, the sixth lens L6 and the seventh lens L7 are aspherical lenses.

[0230] In the embodiment, the surface type of the aspherical lens in the fisheye lens can meet the following formula:

[0231]

[0232] Wherein, Z is the sag of the aspherical surface, c is the basic curvature at the vertex, k is the conic constant, r is the radial coordinate perpendicular to the optical axis, a i is the high-order coefficient, a i r 2i is the high-order term of the aspherical surface.

[0233] For example, table 10 details the aspherical coefficients of each lens in the fifth embodiment in a feasible implementation manner.

[0234] Table 10: Design values of aspherical coefficients of each lens in the fisheye lens

[0235]

[0236]

[0237] The fisheye lens provided in the fifth embodiment achieves the following technical indicators:

[0238] Focal length: 1.95mm;

[0239] Aperture: F1.85;

[0240] Field of view: 190°;

[0241] Optical total length: 28.1mm;

[0242] Image surface size: φ6.4mm.

[0243] Figure 22 A ball aberration curve of the fisheye lens provided in the fifth embodiment of the present application, wherein the vertical direction represents a normalized pupil coordinate, 0 represents a pupil center, the vertical direction top represents a pupil vertex, and the horizontal direction represents the spherical aberration of different wavelengths in millimeters (mm); different linear curves in the figure represent different wavelengths of the fisheye lens imaging. As shown in the figure, the pupil radius is 0.5280mm, the spherical aberration under different wavelengths (0.436μm, 0.470μm, 0.486μm, 0.546μm, 0.587μm and 0.656μm) is within ±0.01mm, and the different wavelength curves are relatively concentrated, which indicates that the axial aberration of the fisheye lens is very small, so it can be known that the fisheye lens can better correct the aberration. Figure 22

[0244] Figure 23 A ray fan diagram of the fisheye lens provided in the fifth embodiment of the present application, wherein the horizontal axis represents the distance of the light ray deviating from the center of the entrance pupil when passing through the entrance pupil, and the vertical axis represents the distance of the corresponding light ray deviating from the chief ray on the image surface. It should be noted that the chief ray is the light ray passing through the center of the entrance pupil. The most ideal curve is a straight line coinciding with the horizontal coordinate, at this time it indicates that all light rays converge to the same point on the image surface. As shown in the figure, Figure 23 It can be seen that the curves under each field of view are gentle, which represents that the aberration of the fisheye lens is well corrected.

[0245] Figure 24 A field curvature distortion diagram of the fisheye lens provided in the fifth embodiment of the present application, in the left coordinate system, the horizontal coordinate represents the size of the field curvature, in millimeters (mm); the vertical coordinate represents the normalized image height, without unit; from Figure 24 It can be seen that the fisheye lens provided in the present embodiment effectively controls the light with a wavelength of 0.436μm to 0.656μm on the field curvature, and ensures that the central image quality and the peripheral image quality are relatively small when imaging. In the right coordinate system, the horizontal coordinate represents the size of the F-Theta distortion, in %; the vertical coordinate represents the normalized image height, without unit; from Figure 24 It can be seen that the fisheye lens provided in the present embodiment is effectively controlled.

[0246] Figure 25 ​The point spread function (PSF) of the fisheye lens provided in the fifth embodiment of the present application is shown in FIG. 8. The PSF refers to a diffused pattern of light rays emitted from a point source after passing through an optical system, and the diffused pattern is caused by aberration, which makes the intersection of the light rays with the image plane no longer concentrated at the same point. The distribution of points in the PSF can approximately represent the concentration of light rays, and reflects the imaging quality of the system. As shown in FIG. 8, the diffused pattern of the light rays (0.436 μm-0.656 μm) is relatively concentrated at each field of view, and the root mean square radius (RMS radius) of the light rays at each field of view is 0.234 μm, 0.243 μm, 0.326 μm, 0.426 μm, 0.530 μm, 0.597 μm, 0.590 μm, 0.669 μm, 0.948 μm, 1.187 μm and 1.847 μm, respectively. The RMS radius of each field of view is less than 2 μm, which indicates that the fisheye lens has low chromatic aberration and aberration at the full field of view, and can achieve high-resolution imaging. Figure 25

[0247] In order to more clearly illustrate the above embodiments, Table 11 details the specific optical and physical parameters of each lens in the fisheye lens provided in the first to fifth embodiments of the present application.

[0248] Table 11 Design values of optical and physical parameters of the fisheye lens

[0249]

[0250]

[0251] The above detailed description does not constitute a limitation on the scope of protection of the present application. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.​

Claims

1. A fisheye lens characterized by comprising: The fisheye lens comprises, in sequence from the object plane to the image plane along the optical axis, 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; the fisheye lens has nine lenses with optical power; The first lens has negative optical power, the second lens has negative optical power, the third lens has negative optical power, the fourth lens has positive optical power, the fifth lens has positive optical power, the sixth lens has positive optical power, the seventh lens has negative optical power, the eighth lens has positive optical power, and the ninth lens has negative optical power; The sixth lens and the seventh lens form a first cemented lens group, and the eighth lens and the ninth lens form a second cemented lens group; The fisheye lens has optical power φ, the first lens has optical power φ1, the second lens has optical power φ2, the third lens has optical power φ3, the fourth lens has optical power φ4, the fifth lens has optical power φ5, the sixth lens has optical power φ6, the seventh lens has optical power φ7, the eighth lens has optical power φ8, the ninth lens has optical power φ9, the first cemented lens group has optical power φ67, and the second cemented lens group has optical power φ89; -0.15<φ1 / φ<-0.06; -0.23<φ2 / φ<-0.09; -0.38<φ3 / φ<-0.32; 0.06<φ4 / φ<0.18; 0.24<φ5 / φ<0.34; 0.25<φ6 / φ<0.35; -0.14<φ7 / φ<-0.09; 0.36<φ8 / φ<0.43; -0.35<φ9 / φ<-0.25; 0.11<φ67 / φ<0.18, 0.027<φ89 / φ<0.

12.

2. The fisheye lens according to claim 1, wherein the object side surface of the first lens is a convex surface, and the image side surface is a concave surface; the object side surface of the second lens is a convex surface, and the image side surface is a concave surface; the object side surface of the third lens is a convex surface or a concave surface, and the image side surface is a concave surface; the object side surface of the fourth lens is a concave surface or a plane, and the image side surface is a convex surface; the object side surface of the fifth lens is a convex surface, and the image side surface is a convex surface.

3. The fisheye lens according to claim 1, wherein the Abbe number of the sixth lens is v6, the Abbe number of the seventh lens is v7, the Abbe number of the eighth lens is v8, and the Abbe number of the ninth lens is v9, wherein 22≤|v7-v6|≤48 and 12≤|v9-v8|≤48.

4. The fisheye lens according to claim 1, wherein the focal length of the fisheye lens is F, and the focal length of the first cemented lens group is F67; 6≤F67 / F≤8.

5. The fisheye lens according to claim 1, wherein the refractive index of the ninth lens is n9, and the Abbe number of the ninth lens is v9; 1.8≤n9≤2.2 and 18≤v9≤24.

6. The fisheye lens according to claim 1, wherein An entrance pupil diameter of the fisheye lens is EPD, and a focal length of the fisheye lens is F; F / EPD = 1.

85.

7. The fisheye lens according to claim 1, wherein A back focal length of the fisheye lens is BFL, a total track length of the fisheye lens is TTL, and a focal length of the fisheye lens is F; 14. 41≤TTL / F≤15, 2.28≥BFL / F≥2.

16.

8. The fisheye lens according to claim 1, wherein The fisheye lens further comprises a diaphragm; The diaphragm is located in an optical path between the fifth lens and the first cemented lens group.

9. The fisheye lens according to claim 1, wherein A focal length of the fifth lens is F5, a focal length of the first cemented lens group is F67, and a focal length of the fisheye lens is F; 9≤F5 / F+F67 / F≤12.

10. The fisheye lens according to claim 1, wherein The third lens, the sixth lens and the seventh lens are all aspherical lenses, and the first lens, the second lens, the fourth lens, the fifth lens, the eighth lens and the ninth lens are all spherical lenses.

Images