fisheye lens

Abstract

The application discloses a fisheye lens which is composed of five lenses and sequentially includes, along an optical axis from an object side to an imaging surface, a first lens with negative optical power, the object side of which is a convex surface and the image side of which is a concave surface; a second lens with positive optical power, the object side of which is a concave surface and the image side of which is a convex surface; a third lens with negative optical power, the object side of which is a convex surface and the image side of which is a concave surface; a diaphragm; a fourth lens with positive optical power, the object side and the image side of which are both convex surfaces; and a fifth lens with negative optical power, the object side of which is a concave surface and the image side of which is a convex surface at a near optical axis; wherein the maximum field of view FOV of the fisheye lens and the aperture value F# satisfy 100°<FOV / F#<120°. The fisheye lens provided by the application has the advantages of super large wide angle, miniaturization, large aperture, high pixel and good thermal stability by reasonably constraining the surface shape and optical power of each lens.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of imaging lens, in particular to a fisheye lens. BACKGROUND

[0002] With the development of optical technology, in addition to being configured on mobile devices, camera modules gradually begin to be applied in various smart home products, security monitoring, vehicle devices, virtual reality devices and other fields. In order to pursue superior imaging performance, the quality requirements for lenses are also increasingly high, and the specifications are increasingly stringent.

[0003] Among them, wide-angle and miniaturization have become the development trend of the current market; in order to obtain a wide imaging field of view, traditional wide-angle lenses often need to set more lenses, such as some seven-piece or eight-piece lens structures. Such lenses have high cost, large volume, increased weight, and cannot be well corrected for aberrations such as distortion and spherical aberration, and cannot meet the specifications and requirements of the future market. Therefore, how to design a compact, large-aperture, wide-angle optical lens is a problem that needs to be solved at present. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a fisheye lens having at least the advantages of ultra-wide angle, miniaturization, large aperture and high pixel.

[0005] The above-mentioned purposes are achieved by the following technical solutions.

[0006] The present application provides a fisheye lens composed of five lenses, which includes, along the optical axis from the object side to the imaging surface, a first lens with negative focal power, the object side surface of which is convex, and the image side surface of which is concave; a second lens with positive focal power, the object side surface of which is concave, and the image side surface of which is convex; a third lens with negative focal power, the object side surface of which is convex, and the image side surface of which is concave; a diaphragm; a fourth lens with positive focal power, both the object side surface and the image side surface of which are convex; and a fifth lens with negative focal power, the object side surface of which is concave, and the image side surface of which is convex near the optical axis; wherein the maximum field of view FOV and the aperture value F# of the fisheye lens satisfy: 100°<FOV / F#<120°.

[0007] Compared with the prior art, the fisheye lens provided by the present application adopts five glass-plastic hybrid lenses, and through specific surface shape matching and reasonable focal power distribution, the lens has the advantages of ultra-wide angle, miniaturization, large aperture, high pixel and good thermal stability. BRIEF DESCRIPTION OF DRAWINGS

[0008] The above and / or additional aspects and advantages of the present application will become apparent and be readily appreciated from the following description, including the accompanying drawings, in which:

[0009] Figure 1 A structural schematic diagram of the fisheye lens of the first embodiment of the present application;

[0010] Figure 2 A field curvature curve of the fisheye lens of the first embodiment of the present application;

[0011] Figure 3 A sagittal chromatic aberration curve of the fisheye lens of the first embodiment of the present application;

[0012] Figure 4 A structural schematic diagram of the fisheye lens of the second embodiment of the present application;

[0013] Figure 5 A field curvature curve of the fisheye lens of the second embodiment of the present application;

[0014] Figure 6 A sagittal chromatic aberration curve of the fisheye lens of the second embodiment of the present application;

[0015] Figure 7 A structural schematic diagram of the fisheye lens of the third embodiment of the present application;

[0016] Figure 8 A field curvature curve of the fisheye lens of the third embodiment of the present application;

[0017] Figure 9 A sagittal chromatic aberration curve of the fisheye lens of the third embodiment of the present application. DETAILED DESCRIPTION

[0018] In order to make the objects, features and advantages of the present application more clear and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. Several embodiments of the present application are given in the accompanying drawings. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terminology used in the description of the present application is only for the purpose of describing the specific embodiments and is not intended to limit the present application. Throughout the description and claims of this specification, the same reference numerals in different drawings represent the same elements.

[0020] In this specification, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object is called the object side surface of the lens, and the surface of each lens closest to the imaging surface is called the image side surface of the lens.

[0021] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0022] The fish-eye lens comprises five lenses, and sequentially comprises, along an optical axis from an object side to an imaging surface, a first lens, a second lens, a third lens, a diaphragm, a fourth lens, a fifth lens and a filter.

[0023] The first lens has a negative focal power, the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface; the first lens adopts a negative meniscus lens, which is beneficial to obtain a larger field of view angle range and increase the large field of view light entering the optical system, thereby realizing super wide-angle imaging of the lens.

[0024] The second lens has a positive focal power, the object side surface of the second lens is a concave surface, and the image side surface of the second lens is a convex surface; the second lens adopts a concave-convex surface type with a positive focal power, which is beneficial to balance the off-axis aberration brought by the first lens, reduce the correction difficulty of the aberration, better converge the edge field of view light, make the light enter the subsequent system more smoothly, reduce the influence of the second lens on the field curvature of the lens, and improve the overall imaging quality.

[0025] The third lens has a negative focal power, the object side surface of the third lens is a convex surface, and the image side surface of the third lens is a concave surface; the third lens adopts a convex-concave surface type, which is beneficial to converge the edge field of view light and reduce the light deflection angle, and further make the light trend smooth transition.

[0026] The fourth lens has a positive focal power, and the object side surface and the image side surface of the fourth lens are both convex surfaces; the fourth lens adopts a double convex lens, which is beneficial to increase the imaging area of the lens, balance various aberrations of the lens, and improve the overall imaging quality.

[0027] The fifth lens has a negative focal power, the object side surface of the fifth lens is a concave surface, and the image side surface of the fifth lens is a convex surface near the optical axis; the fifth lens adopts a concave-convex surface type, which is beneficial to converge the edge field of view light and increase the imaging area of the lens.

[0028] The diaphragm arranged between the third lens and the fourth lens can reduce the distortion correction difficulty of the lens, and is beneficial to converge more light into the rear end of the lens, increase the light flux of the rear end of the lens, and improve the relative luminance of the lens.

[0029] The five lenses can be made of glass or plastic. In order to balance high-quality imaging and miniaturization, the glass lens and the plastic lens can be combined. Since the glass lens has better light transmittance, smaller dispersion and higher refractive index, the chromatic aberration can be effectively corrected and the total length of the system can be shortened. Therefore, the glass-plastic hybrid lens can improve the resolution of the lens, reduce the total length of the system, and improve the thermal stability of the lens. Compared with the all-plastic lens, the glass-plastic hybrid lens has higher light transmittance and more stable chemical properties, which can improve the imaging effect under different brightness and improve the overall imaging quality.

[0030] As an embodiment, in the embodiment of the present application, the first lens is a glass spherical lens, which effectively corrects the geometric chromatic aberration of the optical system by the low dispersion characteristic of the glass itself; the second lens, the third lens, the fourth lens and the fifth lens are plastic aspherical lenses, which can effectively reduce the cost, correct the aberration and provide an optical performance product with higher performance-price ratio. The present application reasonably restricts the surface shape and optical power of each lens, so that the structure is compact, and the characteristics of large field of view, miniaturization, large aperture and high pixel are realized.

[0031] In some embodiments, the maximum field of view FOV and the aperture value F# of the fisheye lens satisfy: 100°<FOV / F#<120°, which is beneficial to balance the large field of view and the large aperture of the lens, realize the characteristics of ultra-wide angle and large aperture, and obtain more scene information to meet the wide range of shooting requirements. The large aperture characteristic is beneficial to improve the problem of rapid decline of relative brightness of the edge field of view caused by the ultra-wide angle, so as to obtain more scene information and improve the imaging quality in the whole field of view.

[0032] In some embodiments, the fisheye lens satisfies the following condition formula:

[0033] -1.5<f1 / f2<-0.1;

[0034] Wherein, f1 represents the focal length of the first lens, and f2 represents the focal length of the second lens. Satisfying the above range can make the first and second lenses together realize the converging effect of the large-angle light, expand the field of view of the lens, on the other hand, can make the second lens better converge the edge field of view light, make the light more smoothly enter the subsequent system, reduce the influence of the first and second lenses on the field curvature of the lens, and improve the overall imaging quality.

[0035] In some embodiments, the fisheye lens satisfies the following condition formula:

[0036] 4<f2 / f<25;

[0037] Wherein, f2 represents the focal length of the second lens, and f represents the effective focal length of the fisheye lens. The above range is met, so that the second lens has appropriate positive refractive power, which is beneficial to balance the positive spherical aberration generated by the first lens and the third lens, and improve the imaging quality.

[0038] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0039] -60 < f3 / f < -3;

[0040] Wherein, f3 represents the focal length of the third lens, and f represents the effective focal length of the fisheye lens. The above range is met, so that the third lens has appropriate negative refractive power, which is beneficial to balance the spherical aberration caused by the second lens and improve the imaging quality of the lens.

[0041] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0042] -0.8 < f4 / f5 < -0.1;

[0043] Wherein, f4 represents the focal length of the fourth lens, and f5 represents the focal length of the fifth lens. The above range is met, so that the refractive power ratio of the fourth and fifth lenses is reasonably set, which is beneficial to the convergence of light, makes the divergent light entering the front of the system smoothly into the rear optical system, makes the overall light path more gentle, and is beneficial to optimizing aberration and improving overall resolution.

[0044] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0045] -5 < R51 / f < -0.5;

[0046] Wherein, R51 represents the radius of curvature of the object side of the fifth lens, and f represents the effective focal length of the fisheye lens. The above range is met, which is beneficial to converge the edge field of view light, balance various aberrations, and improve the resolution of the lens.

[0047] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0048] 0 < R51 / R52 < 1;

[0049] Wherein, R51 represents the radius of curvature of the object side of the fifth lens, and R52 represents the radius of curvature of the image side of the fifth lens. The above range is met, which is beneficial to converge the edge field of view light, increase the imaging area of the lens, and improve the overall imaging quality.

[0050] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0051] 1.5 < BFL / f < 2.0;

[0052] BFL / f> 1.5, and BFL / f< 2.5, wherein BFL represents an optical back focal length of the fisheye lens, and f represents an effective focal length of the fisheye lens. The above range is beneficial to reasonably control the back focal length of the lens, improve the matching degree of the fisheye lens and the imaging chip, reduce the interference between the lens and the module, and improve the assembly yield.

[0053] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0054] 1.5 < DM2 / DM5 < 2.5;

[0055] wherein DM2 represents an effective diameter of the second lens, and DM5 represents an effective diameter of the fifth lens. The above range is beneficial to realize the miniaturization of the lens volume by reasonably setting the aperture ratio of the second lens and the fifth lens.

[0056] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0057] 60° < (FOV x f) / H < 75°;

[0058] wherein FOV represents a maximum field of view angle of the fisheye lens, f represents an effective focal length of the fisheye lens, and H represents a full image height corresponding to the maximum field of view angle of the fisheye lens. The above range is beneficial to realize the balance between the large wide angle and the large image surface of the lens, so as to obtain more scene information and meet the demand of shooting a large range of pictures.

[0059] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0060] 0.04 < Nd1 / Vd1 < 0.06;

[0061] wherein Nd1 represents the refractive index of the first lens, and Vd1 represents the Abbe number of the first lens. The above range is beneficial to reasonably set the material selection range of the first lens, correct the chromatic aberration of the system, improve the imaging quality, and improve the thermal stability of the lens, so that the lens has stable imaging performance in high and low temperature environments.

[0062] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0063] 0.5 < R21 / R22 < 1.8;

[0064] wherein R21 represents the curvature radius of the object side surface of the second lens, and R22 represents the curvature radius of the image side surface of the second lens. The above range is beneficial to converge the edge field of view light, make the converged light smoothly enter the rear optical system, and further make the light trend smoothly transition.

[0065] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0066] 1 < R31 / R32 < 2.5;

[0067] wherein R31 represents a curvature radius of an object side surface of the third lens, and R32 represents a curvature radius of an image side surface of the third lens. Satisfying the above range is conducive to slowing down the turning trend of light rays entering the third lens, and can effectively correct the aberration and distortion of the off-axis field of view, and improve the high-quality imaging of the lens.

[0068] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0069] f / EPD < 2.1;

[0070] wherein f represents an effective focal length of the fisheye lens, and EPD represents an entrance pupil diameter of the fisheye lens. Satisfying the above range is conducive to realizing the large aperture characteristics of the lens, increasing the light flux, and improving the imaging effect of the lens in a dim environment.

[0071] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0072] 7 < R11 / f < 10;

[0073] wherein R11 represents a curvature radius of an object side surface of the first lens, and f represents an effective focal length of the fisheye lens. Satisfying the above range can effectively expand the field of view angle of the lens and collect large field of view light rays.

[0074] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0075] 5 < TTL / CT3 < 18;

[0076] wherein TTL represents an optical total length of the fisheye lens, and CT3 represents a center thickness of the third lens on the optical axis. Satisfying the above range is conducive to shortening the optical total length of the lens.

[0077] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0078] 0.2 < CT3 / DM3 < 0.6;

[0079] wherein CT3 represents a center thickness of the third lens on the optical axis, and DM3 represents an effective diameter of the third lens. Satisfying the above range can effectively control the bending shape of the third lens, can effectively slow down the turning trend of light rays, is conducive to correcting the aberration and distortion of the off-axis field of view, and improves the high-quality imaging of the lens.

[0080] The application will be further described in the following embodiments. In each embodiment, the thickness, radius of curvature, and material selection of each lens in the fisheye lens are different, and the specific differences can be seen from the parameter table of each embodiment. The following embodiments are only preferred embodiments of the application, but the embodiments of the application are not limited to the following embodiments only, and any changes, substitutions, combinations or simplifications made without departing from the innovative points of the application should be regarded as equivalent replacement modes, and are included in the protection scope of the application.

[0081] In each embodiment of the application, when the lens in the fisheye lens is an aspheric lens, the aspheric surface of the lens satisfies an aspheric equation, where z is the distance sag of the aspheric surface at a height h along the optical axis, c is the paraxial curvature of the surface, k is the quadratic surface coefficient, A 2i is the aspheric surface coefficient of the 2i-th order.

[0082] First embodiment

[0083] Please refer to Figure 1 , which is a structural schematic diagram of a fisheye lens 100 provided in the first embodiment of the application. The fisheye lens 100 includes, in order from the object side to the imaging surface along the optical axis, a first lens L1, a second lens L2, a third lens L3, a stop ST, a fourth lens L4, a fifth lens L5, and a filter G1.

[0084] The first lens L1 has a negative focal power, the object side surface S1 of the first lens is a convex surface, and the image side surface S2 of the first lens is a concave surface.

[0085] The second lens L2 has a positive focal power, the object side surface S3 of the second lens is a concave surface, and the image side surface S4 of the second lens is a convex surface.

[0086] The third lens L3 has a negative focal power, the object side surface S5 of the third lens is a convex surface, and the image side surface S6 of the third lens is a concave surface.

[0087] The fourth lens L4 has a positive focal power, the object side surface S7 of the fourth lens is a convex surface, and the image side surface S8 of the fourth lens is a convex surface.

[0088] The fifth lens L5 has a negative focal power, the object side surface S9 of the fifth lens is a concave surface, and the image side surface S10 of the fifth lens is a convex surface near the optical axis.

[0089] The first lens L1 is a glass spherical lens, and the second lens L2, the third lens L3, the fourth lens L4, and the fifth lens L5 are plastic aspheric lenses.

[0090] Specifically, the design parameters of each lens of the fisheye lens 100 provided in the embodiment are shown in Table 1.

[0091] Table 1

[0092]

[0093]

[0094] In this embodiment, the aspherical parameters of each lens in the fisheye lens 100 are shown in Table 2.

[0095] Table 2

[0096] Surface Number k [A4] [A6] [A8] A 10 ]]> A 12 ]] A 14 ]] A 16 ]] A 18 ]] A 20 ]] S3 1.52E-01 -7.24E-02 -8.23E-02 3.90E-01 1.73E-01 -2.05E-01 -1.96E-01 4.53E-02 1.63E-01 -2.11E-02 S4 0.00E+00 -1.09E-01 3.05E-01 5.89E-02 -5.70E-01 5.82E-01 2.87E-01 -4.82E-01 -2.03E-01 2.96E-01 S5 0.00E+00 -1.35E-01 2.34E-01 -2.16E-01 5.23E-01 -8.17E-02 -1.01E+00 9.17E-01 3.90E-01 -2.48E-01 S6 0.00E+00 -9.77E-01 6.08E-02 1.45E+01 -6.88E+01 1.10E+02 4.96E+02 -2.55E+03 4.20E+03 4.37E+03 S7 -5.14E-01 -1.18E+00 2.20E+00 -7.43E+00 1.13E+01 -1.29E+01 -1.65E+01 3.13E+02 1.97E+02 -1.80E+03 S8 2.02E-01 -2.26E-01 9.29E-01 4.17E+00 -1.94E+01 1.73E+00 1.64E+02 1.46E+02 -7.33E+02 9.29E+01 S9 0.00E+00 -8.63E-03 3.93E+00 -9.43E+00 4.97E+00 5.47E+00 1.53E+02 3.18E+02 -2.44E+03 1.12E+03 S10 0.00E+00 9.01E-01 1.10E+00 1.06E+01 -7.29E+01 1.20E+02 3.58E+02 -8.21E+02 -3.50E+03 8.06E+03

[0097] Please refer to Figure 2 and Figure 3 , which respectively show the field curvature curve and the axial chromatic aberration curve of the fisheye lens 100.

[0098] Figure 2 The field curvature curve of the fisheye lens 100 represents the bending degree of the sagittal image surface and the tangential image surface, Figure 2 In the fisheye lens 100, the horizontal axis represents the offset (unit: millimeter), and the vertical axis represents the field angle (unit: degree). From Figure 2 It can be seen that the field curvature of the sagittal and tangential image surfaces is controlled within ±0.02 millimeter, which indicates that the fisheye lens 100 has good field curvature correction.

[0099] Figure 3 The axial chromatic aberration curve of the fisheye lens 100 represents the chromatic aberration of each wavelength relative to the central wavelength (0.555 microns) at different image heights on the imaging surface, Figure 3 In the fisheye lens 100, the horizontal axis represents the axial chromatic aberration value of each wavelength relative to the central wavelength (unit: microns), and the vertical axis represents the normalized field angle. From Figure 3 It can be seen that the axial chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±2 microns, which indicates that the fisheye lens 100 can effectively correct the aberration of the edge field and the second spectrum of the entire image surface.

[0100] Second Embodiment

[0101] Please refer to Figure 5 , which shows the structural schematic diagram of the fisheye lens 200 provided by the second embodiment of the present application. The fisheye lens 200 of the second embodiment is substantially the same as the fisheye lens 100 of the first embodiment, and the difference mainly lies in the difference in the curvature radius, lens thickness, spacing, etc. of each lens surface.

[0102] Specifically, the design parameters of the fisheye lens 200 provided by the second embodiment are shown in Table 3.

[0103] Table 3

[0104]

[0105] In the embodiment, the aspheric parameters of each lens in the fisheye lens 200 are shown in Table 4.

[0106] Table 4

[0107]

[0108]

[0109] In the embodiment, the curve graphs of the field curvature and the sagittal chromatic aberration of the fisheye lens 200 are shown in Figure 5 and Figure 6 respectively. It can be seen from Figure 5 that the field curvature of the meridional image surface and the sagittal image surface is controlled within ±0.05 millimeter, which indicates that the field curvature of the fisheye lens 200 is well corrected. It can be seen from Figure 6 that the sagittal chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±4 micrometers, which indicates that the fisheye lens 200 can effectively correct the aberration of the edge field of view and the secondary spectrum of the entire image surface.

[0110] Third Embodiment

[0111] Please refer to Fig. 3, which is a structural schematic diagram of a fisheye lens 300 provided by the third embodiment of the present application. The fisheye lens 300 of the embodiment is substantially the same as the fisheye lens 100 of the first embodiment described above, and the difference mainly lies in that the curvature radius, the lens thickness, the interval and the like of each lens surface type are different. Figure 9 Specifically, the design parameters of the fisheye lens 300 provided by the embodiment are shown in Table 5.

[0112] Table 5

[0113]

[0114] In the embodiment, the aspheric parameters of each lens in the fisheye lens 300 are shown in Table 6.

[0115] Table 6

[0116]

[0117] Surface Number k [A4] [A6] [A8] A 10 ]] A 12 ]]> A 14 ]] A 16 ]]> A 18 ]] A 20 ]]> S3 1.42E-01 8.58E-03 -1.61E-01 2.89E-01 2.15E-01 -7.12E-02 -1.92E-01 -2.23E-02 1.56E-02 9.46E-02 S4 0.00E+00 -1.32E-02 2.42E-01 1.08E-02 -4.93E-01 6.02E-01 2.88E-01 -4.75E-01 -3.02E-01 3.20E-01 S5 0.00E+00 -1.54E-01 5.71E-01 9.76E-02 -7.33E-01 7.29E-01 7.60E-01 2.72E+00 5.89E-01 -9.01E+00 S6 0.00E+00 -1.94E-01 -2.09E-02 1.43E+01 -7.89E+01 1.13E+02 5.62E+02 -2.44E+03 4.32E+03 -3.99E+03 S7 -1.42E-01 -2.99E-01 2.13E+00 -1.11E+01 7.95E+00 -8.25E+00 -1.47E+01 2.39E+02 -2.44E+02 -1.22E+03 S8 2.32E-01 -1.76E-01 5.36E-01 3.90E+00 -1.98E+01 -2.56E+00 1.52E+02 1.15E+02 -9.50E+02 2.47E+02 S9 0.00E+00 5.08E-01 2.85E+00 -1.31E+01 5.33E+00 3.56E+01 2.57E+02 3.96E+02 -2.29E+03 -1.86E+03 S10 0.00E+00 1.13E+00 3.22E-02 1.17E+01 -6.98E+01 7.69E+01 5.73E+02 -5.25E+02 -3.92E+03 5.87E+03

[0118] In the embodiment, the curve graphs of the field curvature and the sagittal chromatic aberration of the fisheye lens 300 are shown in Figure 8 and Figure 9 respectively. It can be seen from Figure 8 that the field curvature of the meridional image surface and the sagittal image surface is controlled within ±0.07 millimeter, which indicates that the field curvature of the fisheye lens 300 is well corrected. It can be seen from Figure 9 that the sagittal chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±3 micrometers, which indicates that the fisheye lens 300 can effectively correct the aberration of the edge field of view and the secondary spectrum of the entire image surface. ​

[0119] Referring to Table 7, optical properties of the fisheye lens corresponding to each of the three embodiments are shown, including the maximum field of view FOV, the total optical length TTL, the image height IH corresponding to the maximum half field of view, the effective focal length f, and the related numerical values corresponding to each of the aforementioned conditional expressions.

[0120] Table 7

[0121]

[0122]

[0123] In summary, the fisheye lens provided by the present application has at least the following advantages:

[0124] (1) The fisheye lens provided by the present application adopts five lenses, and through specific surface shape matching and reasonable refractive power distribution, the demand for a large field of view of the lens is met, and the lens has the advantages of small total length, large aperture, low sensitivity, good resolution, etc.

[0125] (2) Since the glass has better light transmittance and higher refractive index, the fisheye lens provided by the present application can basically be consistent with the optical quality of the current mainstream 6-7 plastic lenses by adopting one glass lens + four plastic lenses, and has better light transmittance and optical performance, has good thermal stability, and realizes high-pixel imaging quality of the lens.

[0126] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0127] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as a limitation on the scope of the present patent. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of protection of the present application. Therefore, the protection scope of the present patent should be subject to the appended claims.

Claims

1. A fisheye lens consisting of five pieces of lenses, characterized by, In order from the object side to the imaging surface along the optical axis, comprising: a first lens with negative refractive power, the object side surface of the first lens being convex, and the image side surface of the first lens being concave; a second lens with positive refractive power, the object side surface of the second lens being concave, and the image side surface of the second lens being convex; a third lens with negative refractive power, the object side surface of the third lens being convex, and the image side surface of the third lens being concave; a diaphragm; a fourth lens with positive refractive power, both the object side surface and the image side surface of the fourth lens being convex; a fifth lens with negative refractive power, the object side surface of the fifth lens being concave, and the image side surface of the fifth lens being convex at the near optical axis; wherein the maximum field of view FOV of the fisheye lens and the aperture value F# satisfy: 100°<FOV / F#<120°.

2. The fisheye lens according to claim 1, characterized by The fisheye lens satisfies the following conditional expression: -1.5<f1 / f2<-0.1; wherein f1 represents the focal length of the first lens, and f2 represents the focal length of the second lens.

3. The fisheye lens according to claim 1, characterized by The fisheye lens satisfies the following conditional expression: 4<f2 / f<25; wherein f2 represents the focal length of the second lens, and f represents the effective focal length of the fisheye lens.

4. The fisheye lens according to claim 1, characterized by The fisheye lens satisfies the following conditional expression: -60<f3 / f<-3; wherein f3 represents the focal length of the third lens, and f represents the effective focal length of the fisheye lens.

5. The fisheye lens according to claim 1, wherein The fisheye lens satisfies the following conditional expression: -0.8<f4 / f5<-0.1; wherein f4 represents the focal length of the fourth lens, and f5 represents the focal length of the fifth lens.

6. The fisheye lens according to claim 1, characterized by The fisheye lens satisfies the following conditional expression: -5<R51 / f<-0.5; wherein R51 represents the curvature radius of the object side surface of the fifth lens, and f represents the effective focal length of the fisheye lens.

7. The fisheye lens according to claim 1, wherein The fisheye lens satisfies the following conditional expression: 0<R51 / R52<1; wherein R51 represents the curvature radius of the object side surface of the fifth lens, and R52 represents the curvature radius of the image side surface of the fifth lens.

8. The fisheye lens of claim 1, wherein, The fisheye lens satisfies the following conditional expression: 1.5<BFL / f<2.0; wherein BFL represents the optical back focal length of the fisheye lens, and f represents the effective focal length of the fisheye lens.

9. The fisheye lens of claim 1, wherein, The fisheye lens satisfies the following conditional expression: 1.5<DM2 / DM5<2.5; wherein DM2 represents the effective diameter of the second lens, and DM5 represents the effective diameter of the fifth lens.

10. The fisheye lens of claim 1, wherein, The fisheye lens satisfies the following conditional expression: 60°<(FOV×f) / H<75°; wherein FOV represents the maximum field of view of the fisheye lens, f represents the effective focal length of the fisheye lens, and H represents the full image height corresponding to the maximum field of view of the fisheye lens.

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