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 negative optical power, both the object side and the image side of which are concave surfaces; a third lens with positive optical power, the image side of which is a convex surface; a diaphragm; a fourth lens with positive optical power, both the object side and the image side of which are 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 near the optical axis; wherein the maximum field of view FOV of the fisheye lens and the aperture value F# satisfy 110°<FOV / F#<130°. 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 lenses, in particular to a fisheye lens. BACKGROUND

[0002] The fisheye lens is an imaging system with super large field of view and large aperture, which is often used for shooting a large range of scenes at a close distance. Due to the super large field of view, the fisheye lens is widely used in the fields of scene monitoring, satellite positioning, vehicle monitoring, unmanned aerial vehicle shooting and engineering measurement.

[0003] The fisheye lens in the prior art usually adopts a glass-plastic hybrid lens composed of glass lenses and plastic lenses. The glass-plastic hybrid lens can effectively correct the chromatic aberration of the system, improve the light intake and imaging clarity of the fisheye lens, has higher light transmittance and more stable chemical properties compared with a full-plastic lens, and can improve the imaging effect under different brightness, which is the development trend of future lenses. At present, the more common method is to use 6 plastic lenses and 2 glass lenses. Due to the large number of lenses, the fisheye lens has large volume, increased weight, and the aberrations such as distortion and spherical aberration cannot be well corrected. Therefore, how to design a compact fisheye lens with large aperture and large field of view is a problem to be solved at present. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a fisheye lens having the advantages of large field of view, large aperture, high pixel and small total length.

[0005] The present application achieves the above-mentioned purposes through the following technical solutions.

[0006] The present application provides a fisheye lens composed of five lenses, characterized in that, along the optical axis from the object side to the imaging surface, there are sequentially arranged: a first lens with negative focal power, the object side surface of the first lens being a convex surface, and the image side surface of the first lens being a concave surface; a second lens with negative focal power, the object side surface of the second lens being a concave surface, and the image side surface of the second lens being a concave surface; a third lens with positive focal power, the image side surface of the third lens being a convex surface; a diaphragm; a fourth lens with positive focal power, the object side surface of the fourth lens being a convex surface, and the image side surface of the fourth lens being a convex surface; and a fifth lens with negative focal power, the object side surface of the fifth lens being a concave surface, and the image side surface of the fifth lens being a convex surface near the optical axis; wherein the maximum field of view FOV and the aperture value F# of the fisheye lens satisfy: 110°<FOV / F#<130°.

[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 fisheye lens has the advantages of super wide angle, miniaturization, large aperture, high pixel and good thermal stability. Attached Figure Description

[0008] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0009] Figure 1 This is a schematic diagram of the structure of a fisheye lens according to the first embodiment of the present invention;

[0010] Figure 2 This is a field curvature curve diagram of the fisheye lens according to the first embodiment of the present invention;

[0011] Figure 3 This is a chromatic aberration curve of the fisheye lens according to the first embodiment of the present invention.

[0012] Figure 4 This is a schematic diagram of the structure of a fisheye lens according to the second embodiment of the present invention;

[0013] Figure 5 This is a field curvature curve diagram of the fisheye lens according to the second embodiment of the present invention;

[0014] Figure 6 This is a chromatic aberration curve of the fisheye lens according to the second embodiment of the present invention.

[0015] Figure 7 This is a schematic diagram of the structure of a fisheye lens according to the third embodiment of the present invention;

[0016] Figure 8 This is a field curvature curve diagram of a fisheye lens according to the third embodiment of the present invention;

[0017] Figure 9 This is a chromatic aberration curve of the fisheye lens according to the third embodiment of the present invention.

[0018] Figure 10 This is a field curvature curve diagram for lenses in the existing technology. Detailed Implementation

[0019] To make the objectives, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Several embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the present invention will be thorough and complete.

[0020] 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 this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application. Same reference numerals in different drawings denote the same elements.

[0021] In the present application, 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.

[0022] 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.

[0023] The present application provides a fisheye lens composed of five lenses, which comprises, along the optical axis from the object side to the imaging surface, a first lens, a second lens, a third lens, a diaphragm, a fourth lens, a fifth lens and a filter.

[0024] The first lens has a negative focal power, its object side surface is convex, and its image side surface is concave; the first lens adopts a negative meniscus lens, which is conducive to obtaining a larger field of view angle range and increasing the large field of view light entering the optical system to realize large wide-angle imaging of the lens.

[0025] The second lens has a negative focal power, and both its object side surface and image side surface are concave; the first and second lenses as front groups both adopt negative focal power lenses, which is conducive to compressing the super large field of view on the object side to the field of view range required by a conventional lens.

[0026] The third lens has a positive focal power, its object side surface can be concave or convex, and its image side surface is convex; the third lens adopts a positive focal power lens, which is conducive to balancing the off-axis aberration brought by the first and second lenses, reducing the correction difficulty of the aberration, and better converging the edge field of view light to make the light enter the subsequent system more smoothly.

[0027] The fourth lens has a positive focal power, and both its object side surface and image side surface are convex; the fourth lens adopts a biconvex lens, which is conducive to increasing the imaging area of the lens, balancing various aberrations of the lens, and improving the overall imaging quality.

[0028] The fifth lens has a negative focal power, its object side surface is concave, and its image side surface is convex near the optical axis; the fifth lens adopts a concave-convex surface type, which is conducive to converging the edge field of view light and increasing the imaging area of the lens.

[0029] The light barrier arranged between the third lens and the fourth lens can reduce the difficulty of distortion correction of the fisheye lens, and is beneficial to converge more light into the rear end of the fisheye lens, increase the light quantity of the rear end of the lens, and improve the relative luminance of the lens.

[0030] The five lenses can be all glass lenses or plastic lenses; in order to pursue the balance between high-quality imaging and miniaturization, the glass lenses and the plastic lenses can be combined, since the glass lenses have 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 combining the glass lenses and the plastic lenses can better improve the resolving power of the lens, reduce the total length of the system, and improve the thermal stability of the lens.

[0031] As an implementation form, in the embodiment of the present application, the first lens is a glass lens, the low dispersion of the glass lens can effectively correct the geometric chromatic aberration of the optical system; the second lens, the third lens, the fourth lens and the fifth lens are plastic lenses, which can effectively reduce the cost and correct the aberration, and provide an optical performance product with higher performance-price ratio. The present application reasonably restricts the surface shape and the focal length 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.

[0032] In some embodiments, the maximum field of view FOV and the aperture value F# of the fisheye lens satisfy: 110°<FOV / F#<130°. Satisfying the above range is beneficial to realize the balance between the large field of view and the large aperture of the lens, and realize the characteristics of super wide angle and large aperture; the super wide angle characteristic can make the lens obtain more scene information, meet the shooting demand in a large range; 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 super wide angle, so as to also be beneficial to obtain more scene information and improve the imaging quality in the whole field of view.

[0033] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0034] 0.6<f1 / f2<1.3;

[0035] 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, and at the same time reduce the deflection angle borne by the rear lens, which is beneficial to realize the effect of large aperture and super wide angle of the lens.

[0036] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0037] -7<f2 / f<-3;

[0038] wherein f2 represents a focal length of the second lens, and f represents an effective focal length of the fisheye lens. Satisfying the above range, by reasonably configuring the power of the second lens, it is helpful to strengthen the correction of the coma of the off-axis field of view, while making the lens obtain a longer back focus in the case of ultra-wide angle and short focal length.

[0039] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0040] -3 < f5 / f < -1;

[0041] wherein f5 represents a focal length of the fifth lens, and f represents an effective focal length of the fisheye lens. Satisfying the above range, the fifth lens can have an appropriate negative power, which is beneficial to balance various aberrations in the front-end lens, while ensuring that the chief ray incidence angle of the lens is smaller than that of the image sensor, thereby improving the imaging quality of the fisheye lens.

[0042] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0043] 1 < f2 / f5 < 4;

[0044] wherein f2 represents a focal length of the second lens, and f5 represents a focal length of the fifth lens. Satisfying the above range, by reasonably setting the focal length ratio of the second and fifth lenses, the edge field of view light can be better converged, the correction difficulty of the distortion and aberration of the off-axis field of view is reduced, and the overall imaging quality is improved.

[0045] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0046] -5 < R21 / R22 < -0.5;

[0047] wherein R21 represents a curvature radius of the object side surface of the second lens, and R22 represents a curvature radius of the image side surface of the second lens. Satisfying the above range is beneficial to slow down the turning trend of the light, and can effectively correct the aberration and distortion of the off-axis field of view, thereby improving the high-quality imaging of the lens.

[0048] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0049] 0.3 < R21 / R32 < 5;

[0050] wherein R21 represents a curvature radius of the object side surface of the second lens, and R32 represents a curvature radius of the image side surface of the third lens. Satisfying 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 transition smoothly, thereby improving the high-quality imaging of the lens.

[0051] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0052] 0.15 < CT3 / TTL < 0.35;

[0053] wherein CT3 represents a center thickness of the third lens, and TTL represents an optical total length of the fisheye lens. Satisfying the above range can effectively shorten the total length of the lens and effectively correct the field curvature generated by the front end lens of the aperture, thereby improving the imaging quality of the lens.

[0054] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0055] 1.7 < BFL / f < 2.2;

[0056] wherein BFL represents an optical back focal length of the fisheye lens, and f represents an effective focal length of the fisheye lens. Satisfying the above range is conducive to reasonably controlling the back focal length of the lens, improving the matching degree of the lens and the imaging chip, reducing the interference between the lens and the module, and improving the assembly yield.

[0057] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0058] 60° < (FOV x f) / IH < 75°;

[0059] wherein FOV represents a maximum field of view angle of the fisheye lens, f represents an effective focal length of the fisheye lens, and IH represents an image height corresponding to the maximum field of view angle of the fisheye lens. Satisfying the above range is conducive to achieving a balance between a large wide angle and a large image surface of the lens, thereby being able to obtain more scene information and meet the shooting demand of a large range of imaging.

[0060] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0061] 0.4 < (SAG52-SAG51) / DM52 < 0.5;

[0062] wherein SAG51 represents a sag of an object side surface of the fifth lens at an effective aperture, SAG52 represents a sag of an image side surface of the fifth lens at the effective aperture, and DM52 represents an effective aperture of the image side surface of the fifth lens. Satisfying the above range can effectively control the distribution of light incidence angles by reasonably setting the sag and aperture relationship of the fifth lens, and is conducive to correcting high-order aberrations of the fisheye lens.

[0063] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0064] 0.05 < Nd1 / Vd1 < 0.06;

[0065] Wherein, Nd1 represents the refractive index of the first lens, and Vd1 represents the Abbe number of the first lens. Satisfying the above range, the material selection range of the first lens can be reasonably set, which is conducive to correcting the chromatic aberration of the system and improving the imaging quality. Meanwhile, through reasonable material selection, the thermal stability of the lens can be improved, so that the lens has stable imaging performance in high and low temperature environments.

[0066] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0067] 0.4 < (R11-R12) / (R11+R12) < 0.7;

[0068] Wherein, R11 represents the curvature radius of the object side of the first lens, and R12 represents the curvature radius of the image side of the first lens. Satisfying the above range, the surface shape of the first lens is reasonably limited to correct the off-axis aberration and allow the light rays to have appropriate incidence and emission angles in the first lens, which helps to increase the field of view angle and the area of the imaging surface and ensures high-quality imaging.

[0069] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0070] -15 < (f1+f2) / f < -5;

[0071] Wherein, f1 represents the focal length of the first lens, f2 represents the focal length of the second lens, and f represents the effective focal length of the fisheye lens. Satisfying the above range, the optical power of each lens is reasonably configured, which helps to strengthen the coma correction of the off-axis field of view and obtain a longer back focus under the condition of ultra-wide angle and short focal length.

[0072] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0073] -1.5 < SAG21 / CT2 < -0.3;

[0074] Wherein, SAG21 represents the sagittal height of the object side of the second lens, and CT2 represents the center thickness of the second lens. Appropriately adjusting the sagittal height to thickness ratio of the second lens helps lens manufacturing and forming, improves the manufacturing yield, and satisfies the above range, which helps to shorten the total length of the fisheye lens.

[0075] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0076]

[0077] Wherein, represents the optical power of the second lens, represents the optical power of the third lens, The focal length of the fisheye lens is represented. The above range is met, the decentration sensitivity of the third lens is shared to the second lens, the positive and negative focal length of the second and third lenses are matched, the spherical aberration of the system is better corrected, the imaging quality of the lens is improved, and the total length of the lens is effectively shortened.

[0078] In some embodiments, the fisheye lens meets the following conditional expression:

[0079] 1.2 < CT3 / DM3 < 2.5;

[0080] 1.2 < DM2 / DM3 < 1.5;

[0081] Wherein, CT3 represents the center thickness of the third lens, DM2 represents the effective aperture of the second lens, and DM3 represents the effective aperture of the third lens. The above range is met, the effective aperture ratio of the second and third lenses is reasonably controlled, and the bending shape of the third lens is controlled by controlling the ratio of the center thickness of the third lens to the effective aperture thereof, so that the turning trend of the light is effectively slowed down, the aberration and distortion of the off-axis field are effectively corrected, and high-quality imaging of the lens is ensured.

[0082] In some embodiments, the fisheye lens meets the following conditional expression:

[0083] 1.3 < f4 / f < 1.5;

[0084] Wherein, f4 represents the focal length of the fourth lens, and f represents the effective focal length of the fisheye lens. The above range is met, the focal length ratio of the fourth lens is adjusted, the corresponding positive focal length is borne in the optical system, the focusing efficiency of the light on the imaging surface is slowed down, the correction of the spherical aberration and chromatic aberration in the optical system is facilitated, and the overall imaging quality is improved.

[0085] In some embodiments, the fisheye lens meets the following conditional expression:

[0086] -0.4 < (R41+R42) / f4 < 0.3;

[0087] Wherein, R41 represents the curvature radius of the object side of the fourth lens, R42 represents the curvature radius of the image side of the fourth lens, and f4 represents the focal length of the fourth lens. The above range is met, the surface shape of the fourth lens is reasonably controlled, the system sensitivity is reduced, the manufacturing yield is improved by reducing the molding difficulty, the stray light generated by the lens is also reduced, and the imaging quality of the lens is improved.

[0088] In some embodiments, the fisheye lens meets the following conditional expression:

[0089] 0.1 < (CT4+CT5) / TTL < 0.2;

[0090] 1.3 < CT4 / CT5 < 2.8;

[0091] CT4 represents the center thickness of the fourth lens, CT5 represents the center thickness of the fifth lens, and TTL represents the total optical length of the fisheye lens. By setting the center thickness of the fourth and fifth lenses within the above range, the fourth lens is prevented from being too thin to cause uneven filling of the plastic material during molding, or the fifth lens is prevented from being too thick to cause interference between the lens and the lens barrel during assembly, thereby affecting the imaging effect.

[0092] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0093] f / EPD < 1.95;

[0094] f represents the effective focal length of the fisheye lens, and EPD represents the entrance pupil diameter of the fisheye lens. By satisfying the above range, the fisheye lens can achieve a large aperture characteristic, increase the light flux, and reduce the noise caused by weak light in a dark environment, thereby improving the imaging quality and meeting the imaging requirements in different light flux conditions.

[0095] In some embodiments, the fisheye lens satisfies the following conditional expression:

[0096] 10 < TTL / f < 14;

[0097] f represents the effective focal length of the fisheye lens, and TTL represents the total optical length of the fisheye lens. By satisfying the above range, the fisheye lens can achieve a balance between a large field of view and miniaturization, and have a large depth of field to capture a perspective image.

[0098] The present application is 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 found in the parameter table of each embodiment. The following embodiments are preferred embodiments of the present application, but the embodiments of the present application are not limited to the following embodiments. Any changes, substitutions, combinations, or simplifications that do not deviate from the innovative points of the present application are equivalent replacement methods and are included in the protection scope of the present application.

[0099] In each embodiment of the present application, when the lens in the fisheye lens is an aspherical lens, the aspherical surface of the lens satisfies the following equation:

[0100] where z is the distance from the vertex of the aspherical surface when the aspherical surface is at a height h along the optical axis, c is the paraxial curvature of the surface, k is the quadratic surface coefficient, A 2iAspherical surface type coefficients of the 2i-th order.

[0101] First embodiment

[0102] Referring to Figure 1 , a structure diagram of a fisheye lens 100 provided in the first embodiment of the present application is shown, 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.

[0103] The first lens L1 has a negative refractive 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.

[0104] The second lens L2 has a negative refractive 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 concave surface.

[0105] The third lens L3 has a positive refractive power, the object side surface S5 of the third lens is a concave surface, and the image side surface S6 of the third lens is a convex surface.

[0106] The fourth lens L4 has a positive refractive 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.

[0107] The fifth lens L5 has a negative refractive 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.

[0108] 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 aspherical lenses.

[0109] Specifically, the design parameters of each lens of the fisheye lens 100 provided in the embodiment are shown in Table 1.

[0110] Table 1

[0111]

[0112] In the embodiment, the aspherical surface parameters of each lens in the fisheye lens 100 are shown in Table 2.

[0113] Table 2

[0114] Surface Number k [A4] [A6] [A8] A 10 ]]> A 12 ]] A 14 ]]> A 16 ]] A 18 ]]> A 20 ]] S3 1.30E+01 8.30E-03 -6.75E-02 5.82E-02 -7.03E-05 -1.60E-02 7.88E-03 1.25E-03 -2.93E-03 8.26E-04 S4 -8.69E+00 1.93E-02 6.52E-02 -1.46E-01 -2.05E-01 5.36E-01 -3.39E-01 8.93E-02 0.00E+00 0.00E+00 S5 0.00E+00 -4.57E-02 -4.17E-02 6.05E-02 -2.36E-01 2.77E-02 5.00E-01 -3.40E-01 0.00E+00 0.00E+00 S6 0.00E+00 4.97E-02 -6.63E-02 1.16E-02 -7.71E-01 7.45E+00 -1.80E+01 1.43E+01 0.00E+00 0.00E+00 S7 5.33E-01 -7.99E-02 -1.41E-01 -1.56E-01 1.23E-01 -1.94E+00 2.96E+00 -2.47E+00 0.00E+00 0.00E+00 S8 -2.86E+00 7.41E-02 2.44E-02 -6.52E-01 1.05E-01 1.08E+00 8.25E-01 -2.26E+00 0.00E+00 0.00E+00 S9 0.00E+00 9.15E-01 -1.10E-01 -1.15E+00 1.51E+00 3.38E+00 -7.21E-01 -6.06E+00 3.84E+00 2.62E+00 S10 0.00E+00 5.19E-01 1.53E-01 1.47E+00 -5.60E+00 -3.03E+00 5.83E+01 -6.09E+01 -5.47E+01 5.05E+01

[0115] Referring to Figure 2 and Figure 3 , field curvature curves and axial chromatic aberration curves of the fisheye lens 100 are shown.

[0116] Figure 2 The field curvature curves represent the bending degrees of the meridional image surface and the sagittal image surface,Figure 2 The horizontal axis represents the offset (unit: mm), and the vertical axis represents the field angle (unit: degree). From Figure 2 It can be seen that the field curvature of the meridional and sagittal image surfaces is controlled within ±0.05 mm, which indicates that the fish-eye lens 100 has good field curvature correction.

[0117] Figure 3 The vertical axis chromatic aberration curve represents the chromatic aberration of each wavelength at different image heights on the imaging surface relative to the central wavelength (0.555 microns), Figure 3 The horizontal axis represents the vertical axis 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 vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±2.5 microns, which indicates that the fish-eye lens 100 can effectively correct the aberration of the edge field and the secondary spectrum of the entire image surface.

[0118] Second embodiment

[0119] Please refer to Figure 5 , which is a structural schematic diagram of the fish-eye lens 200 provided by the second embodiment of the present application. The fish-eye lens 200 of the present embodiment is substantially the same as the first embodiment described above, and the main difference is that the object side S5 of the third lens is a convex surface near the optical axis, and the curvature radius, lens thickness, spacing, etc. of each lens surface profile are different.

[0120] Specifically, the design parameters of the fish-eye lens 200 provided by the present embodiment are shown in Table 3.

[0121] Table 3

[0122]

[0123] In the present embodiment, the aspheric parameters of each lens in the fish-eye lens 200 are shown in Table 4.

[0124] Table 4

[0125]

[0126] In the present embodiment, the field curvature and the vertical axis chromatic aberration curves of the fish-eye lens 200 are shown in Figure 5 and Figure 6 respectively. From Figure 5 It can be seen that the field curvature of the meridional and sagittal image surfaces is controlled within ±0.06 mm, which indicates that the fish-eye lens 200 has good field curvature correction. From Figure 6 It can be seen that the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±2.5 microns, which indicates that the fish-eye lens 200 can effectively correct the aberration of the edge field and the secondary spectrum of the entire image surface.

[0127] Third embodiment

[0128] Please refer to Figure 9 , the structure schematic diagram of the fisheye lens 300 provided by the third embodiment of the present application is shown, the fisheye lens 300 of the embodiment is substantially the same as the first embodiment, the difference is mainly that the object side S5 of the third lens is a convex surface, and the curvature radius, lens thickness, spacing and the like of each lens surface type are different.

[0129] Specifically, the design parameters of the fisheye lens 300 provided by the embodiment are shown in Table 5.

[0130] Table 5

[0131]

[0132]

[0133] In the embodiment, the aspheric surface parameters of each lens in the fisheye lens 300 are shown in Table 6.

[0134] Table 6

[0135] Surface Number k [A4] [A6] [A8] A 10 ]] A 12 ]] A 14 ]] A 16 ]]> A 18 ]]> A 20 ]]> S3 4.80E+00 -1.35E-01 4.46E-02 6.14E-02 -2.34E-02 -1.67E-02 1.09E-02 1.56E-03 -2.47E-03 4.79E-04 S4 0.00E+00 -4.31E-01 -1.50E-01 4.66E-01 -2.22E-01 1.38E-01 -2.29E-01 1.28E-01 0.00E+00 0.00E+00 S5 0.00E+00 -1.83E-01 -4.32E-01 5.55E-01 5.51E-04 -2.87E-01 1.24E-01 4.40E-03 0.00E+00 0.00E+00 S6 0.00E+00 -4.98E-01 9.84E-01 -6.89E-01 -2.88E+00 9.75E+00 -1.21E+01 5.61E+00 0.00E+00 0.00E+00 S7 -2.64E-01 -6.58E-01 1.17E+00 -2.68E+00 2.83E+00 -1.45E+00 -9.41E-01 3.96E-04 0.00E+00 0.00E+00 S8 -6.72E-01 7.60E-02 1.22E+00 -2.94E+00 6.80E-01 3.86E+00 -2.53E+00 -6.42E-01 0.00E+00 0.00E+00 S9 0.00E+00 1.05E+00 8.09E-01 -5.06E+00 8.07E+00 -4.66E-01 -3.77E+00 3.68E+00 -2.41E+01 3.94E+01 S10 0.00E+00 1.19E+00 -2.28E+00 1.07E+01 -2.90E+01 2.97E+01 1.19E+01 2.80E+01 -9.90E+01 -3.24E+01

[0136] In the embodiment, the field curvature and the curve of the sagittal color difference 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 ±0.12 mm, which indicates that the field curvature of the fisheye lens 300 is well corrected. It can be seen from Figure 9 that the sagittal color difference of the longest wavelength and the shortest wavelength is controlled within ±2.5 microns, which indicates that the fisheye lens 300 can effectively correct the aberration of the edge field of view and the second spectrum of the entire image surface.

[0137] Please refer to Table 7, the optical properties corresponding to the fisheye lens provided in the above three embodiments are shown, including the maximum field of view angle FOV of the fisheye lens, the total optical length TTL, the image height IH corresponding to the maximum field of view, the effective focal length f and the related numerical value corresponding to each of the foregoing conditional expressions.

[0138] Table 7

[0139]

[0140]

[0141] In summary, the fisheye lens provided by the present application has at least the following advantages:

[0142] (1) The fish-eye lens provided by the application adopts five lenses, and meets the requirement of large field angle of view by specific surface shape matching and reasonable refractive power distribution, and has the advantages of small total length, large aperture, low sensitivity, good resolving power and the like.

[0143] (2) Since the glass has better light transmittance and higher refractive index, the fish-eye lens provided by the application can basically be consistent with the optical quality of the mainstream 6-7 plastic lenses by adopting one glass lens and four plastic lenses, and has better light transmittance and optical performance, better thermal stability, and realizes high-pixel imaging quality of the lens.

[0144] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection 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.

[0145] The above-described embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent of the present application. 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 all within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A fisheye lens, composed of five lenses, characterized in that, Along the optical axis from the object side to the imaging plane, the following are included in sequence: A first lens with negative optical power, wherein the object side of the first lens is convex and the image side of the first lens is concave. A second lens with negative optical power, wherein both the object-side and image-side surfaces of the second lens are concave. A third lens with positive optical power, wherein the image-side surface of the third lens is convex; Aperture; A fourth lens with positive optical power, wherein both the object-side surface and the image-side surface of the fourth lens are convex. A fifth lens with negative optical power, wherein the object-side surface of the fifth lens is concave and the image-side surface of the fifth lens is convex near the optical axis; The maximum field of view (FOV) of the fisheye lens and the aperture value (F#) satisfy: 110° <FOV / F#<130°。 2. The fisheye lens according to claim 1, characterized in that, The fisheye lens satisfies the following condition: 0.6 <f1 / f2<1.3; Where 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 in that, The fisheye lens satisfies the following condition: -7 <f2 / f<-3; Where 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 in that, The fisheye lens satisfies the following condition: -3 <f5 / f<-1; Where f5 represents the focal length of the fifth lens, and f represents the effective focal length of the fisheye lens.

5. The fisheye lens according to claim 1, characterized in that, The fisheye lens satisfies the following condition: 1 <f2 / f5<4; Where f2 represents the focal length of the second lens and f5 represents the focal length of the fifth lens.

6. The fisheye lens according to claim 1, characterized in that, The fisheye lens satisfies the following condition: -5 <R21 / R22<-0.5; 0.3 <R21 / R32<5; Wherein, R21 represents the radius of curvature of the object side of the second lens, R22 represents the radius of curvature of the image side of the second lens, and R32 represents the radius of curvature of the image side of the third lens.

7. The fisheye lens according to claim 1, characterized in that, The fisheye lens satisfies the following condition: 0.15 <CT3 / TTL<0.35; Wherein, CT3 represents the center thickness of the third lens, and TTL represents the total optical length of the fisheye lens.

8. The fisheye lens according to claim 1, characterized in that, The fisheye lens satisfies the following condition: 1.7 <BFL / f<2.2; 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 according to claim 1, characterized in that, The fisheye lens satisfies the following condition: 60° < (FOV×f) / IH < 75°; Wherein, FOV represents the maximum field of view of the fisheye lens, f represents the effective focal length of the fisheye lens, and IH represents the image height corresponding to the maximum field of view of the fisheye lens.

10. The fisheye lens according to claim 1, characterized in that, The fisheye lens satisfies the following condition: 0.4 < (SAG52 - SAG51) / DM52 < 0.5; Wherein, SAG51 represents the sagitta of the object side of the fifth lens at the effective aperture, SAG52 represents the sagitta of the image side of the fifth lens at the effective aperture, and DM52 represents the effective aperture of the image side of the fifth lens.

Images