An optical lens with large target surface and low distortion

Abstract

The present invention relates to the field of lens technology. The present invention discloses an optical lens with a large target surface and low distortion, comprising fifteen lenses, wherein the first lens is a convex-concave lens with a negative refractive power, the second, eighth, ninth, eleventh, twelfth, and fourteenth lenses are all convex-convex lenses with a positive refractive power, the third, tenth, and thirteenth lenses are all concave-concave lenses with a negative refractive power, the fourth, fifth, seventh, and fifteenth lenses are all concave-convex lenses with a negative refractive power, the sixth lens is a concave-convex lens with a positive refractive power, the second lens and the third lens are bonded together, the fourth lens and the fifth lens are bonded together, the sixth lens and the seventh lens are bonded together, the ninth lens and the tenth lens are bonded together, the twelfth lens and the thirteenth lens are bonded together, and the fourteenth lens and the fifteenth lens are bonded together; the optical lens having only the first to fifteenth lenses has the advantages of high resolution, good imaging effect, a large image surface, good pattern sharpness, and minimal image distortion.

Description

Technical Field

[0001] The present invention belongs to the technical field of lenses, and in particular relates to an optical lens with a large target surface and low distortion for machine vision. Background Art

[0002] With the continuous advancement of science and technology and the continuous development of society, optical lenses have also developed rapidly in recent years and are widely used in various fields such as smart phones, tablets, video conferencing, vehicle monitoring, security monitoring, machine vision, etc. Therefore, the requirements for optical lenses are getting higher and higher.

[0003] In machine vision systems, the performance of optical lenses is critical, impacting the feasibility and reliability of the entire system. However, the inspection lenses currently used in machine vision systems have low resolution and small target areas, failing to meet the requirements for large target areas and high-definition pixels. They also suffer from significant distortion, causing deformation of the imaged object, making it difficult to measure. They also suffer from low illumination, which can easily darken image edges and create uneven image brightness. They also have small apertures and low luminous flux, resulting in poor low-light performance. Furthermore, with the aperture positioned in front, chromatic aberration is significant, hindering chromatic aberration restoration. These lenses are no longer able to meet the increasing demands of machine vision systems and urgently require improvement. Summary of the Invention

[0004] The object of the present invention is to provide an optical lens with a large target surface and low distortion to solve at least one of the above-mentioned technical problems.

[0005] To achieve the above objectives, the present invention adopts a technical solution: an optical lens with a large target surface and low distortion, comprising, from the object side to the image side along an optical axis, first to fifteenth lenses; each of the first to fifteenth lenses includes an object-side surface facing the object side and through which imaging light passes, and an image-side surface facing the image side and through which imaging light passes;

[0006] The first lens has a negative refractive power, the object side surface of the first lens is convex, and the image side surface of the first lens is concave;

[0007] The second lens element has a positive refractive power, the object-side surface of the second lens element is convex, and the image-side surface of the second lens element is convex;

[0008] The third lens element has a negative refractive power, the object-side surface of the third lens element is concave, and the image-side surface of the third lens element is concave;

[0009] The fourth lens element has a positive refractive power, the object-side surface of the fourth lens element is concave, and the image-side surface of the fourth lens element is convex;

[0010] The fifth lens element has a negative refractive power, the object-side surface of the fifth lens element is concave, and the image-side surface of the fifth lens element is convex;

[0011] The sixth lens element has a positive refractive power, the object-side surface of the sixth lens element is concave, and the image-side surface of the sixth lens element is convex;

[0012] The seventh lens element has a negative refractive power, the object-side surface of the seventh lens element is concave, and the image-side surface of the seventh lens element is convex;

[0013] The eighth lens element has a positive refractive power, the object-side surface of the eighth lens element is convex, and the image-side surface of the eighth lens element is convex;

[0014] The ninth lens element has a positive refractive power, the object-side surface of the ninth lens element is convex, and the image-side surface of the ninth lens element is convex;

[0015] The tenth lens element has a negative refractive power, the object-side surface of the tenth lens element is concave, and the image-side surface of the tenth lens element is concave;

[0016] The eleventh lens has a positive refractive power, the object-side surface of the eleventh lens is convex, and the image-side surface of the eleventh lens is convex;

[0017] The twelfth lens has a positive refractive power, the object-side surface of the twelfth lens is convex, and the image-side surface of the twelfth lens is convex;

[0018] The thirteenth lens has a negative refractive power, the object-side surface of the thirteenth lens is concave, and the image-side surface of the thirteenth lens is concave;

[0019] The fourteenth lens has a positive refractive power, the object-side surface of the fourteenth lens is convex, and the image-side surface of the fourteenth lens is convex;

[0020] The fifteenth lens has a negative refractive power, the object side surface of the fifteenth lens is concave, and the image side surface of the fifteenth lens is convex;

[0021] The second lens and the third lens are cemented together, the fourth lens and the fifth lens are cemented together, the sixth lens and the seventh lens are cemented together, the ninth lens and the tenth lens are cemented together, the twelfth lens and the thirteenth lens are cemented together, and the fourteenth lens and the fifteenth lens are cemented together;

[0022] The optical lens has only the first to fifteenth lenses with refractive power.

[0023] Furthermore, it also includes an aperture, which is arranged on the object side of the first lens.

[0024] Furthermore, the optical lens also satisfies the following requirements: nd1>1.9, nd2>1.9, nd3≥1.9, nd5>1.9, nd6≥1.9, nd8≥1.9, and nd15>1.9, where nd1, nd2, nd3, nd5, nd6, nd8, nd9, and nd15 are the refractive indices of the first lens, the second lens, the third lens, the fifth lens, the sixth lens, the eighth lens, the ninth lens, and the fifteenth lens, respectively.

[0025] Furthermore, the optical lens also satisfies: yp1 / StopD>0.7, where yp1 is the lateral height of the intersection of light rays at the aperture stop over the entire field of view, and StopD is the half-aperture value of the aperture stop.

[0026] Furthermore, the optical lens also satisfies: f / Dstop<2.0, where Dstop is the outer diameter of the aperture, and f is the focal length of the optical lens.

[0027] Furthermore, the optical lens also satisfies: 10.0<|fg4 / f|<15.0, 0<|fg5 / f|<3.0, 1.0<|fg6 / f|<5.0, wherein fg4 is the combined focal length of the ninth lens and the tenth lens, fg5 is the combined focal length of the twelfth lens and the thirteenth lens, and fg4 is the combined focal length of the fourteenth lens and the fifteenth lens.

[0028] Furthermore, the optical lens also satisfies: Pg.F3>0.55, where Pg.F3 is the relative partial dispersion coefficient of the third lens.

[0029] Furthermore, the optical lens also satisfies: Pg.F6>0.53, where Pg.F6 is the relative partial dispersion coefficient of the sixth lens.

[0030] Furthermore, the optical lens also satisfies: Pg.F13>0.42, where Pg.F13 is the relative partial dispersion coefficient of the thirteenth lens.

[0031] Furthermore, the optical lens also satisfies: f / Diag<1.33, wherein f is the focal length of the optical lens, and Diag is the image diameter of the optical lens.

[0032] Beneficial technical effects of the present invention:

[0033] The present invention adopts fifteen lenses and designs each lens accordingly, so as to have the advantages of high resolution, large image surface, small distortion, high illumination, large aperture, good low-light effect, small chromatic aberration, and reduced separation of diffuse spot color light. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0035] Figure 1 This is a schematic structural diagram of Embodiment 1 of the present invention;

[0036] Figure 2 Graphs showing field curvature and distortion according to the first embodiment of the present invention;

[0037] Figure 3 This is an MTF curve diagram of visible light 0.435-0.656 μm according to Example 1 of the present invention;

[0038] Figure 4 1 is a graph showing the chromatic aberration of magnification according to the first embodiment of the present invention;

[0039] Figure 5 This is a structural diagram of embodiment 2 of the present invention;

[0040] Figure 6 Graphs showing field curvature and distortion according to the second embodiment of the present invention;

[0041] Figure 7 This is an MTF curve diagram of visible light 0.435-0.656 μm according to Example 2 of the present invention;

[0042] Figure 8 1 is a graph showing the chromatic aberration of magnification according to the second embodiment of the present invention;

[0043] Figure 9 This is a structural diagram of embodiment 3 of the present invention;

[0044] Figure 10 Graphs showing field curvature and distortion according to the third embodiment of the present invention;

[0045] Figure 11 This is an MTF curve diagram of visible light 0.435-0.656 μm according to Example 3 of the present invention;

[0046] Figure 12 1 is a graph showing the chromatic aberration of magnification according to the third embodiment of the present invention;

[0047] Figure 13 This is a structural diagram of a fourth embodiment of the present invention;

[0048] Figure 14 Graphs showing field curvature and distortion according to the fourth embodiment of the present invention;

[0049] Figure 15 This is an MTF curve diagram of visible light 0.435-0.656 μm according to Example 4 of the present invention;

[0050] Figure 16 This is a graph showing the chromatic aberration of magnification according to the fourth embodiment of the present invention. DETAILED DESCRIPTION

[0051] To further illustrate various embodiments, the present invention is provided with accompanying drawings. These drawings form part of the present disclosure and are primarily used to illustrate the embodiments and, in conjunction with the relevant description in the specification, to explain the operating principles of the embodiments. By referring to these drawings, one of ordinary skill in the art will understand other possible embodiments and the advantages of the present invention. The components in the figures are not drawn to scale, and similar reference numerals are generally used to represent similar components.

[0052] The present invention will now be further described with reference to the accompanying drawings and specific embodiments.

[0053] Here, "a lens having a positive (or negative) refractive power" means that the lens's paraxial refractive power, calculated using Gaussian optics theory, is positive (or negative). The "object-side (or image-side) of a lens" is defined as the specific area of ​​the lens surface through which the imaging light passes. The concavity or convexity of a lens's surface can be determined using the same method commonly used by those skilled in the art: the sign of the radius of curvature (abbreviated as R value). R values ​​are commonly used in optical design software such as Zemax or CodeV. R values ​​are also commonly found in lens data sheets within optical design software. For the object-side surface, a positive R value indicates a convex surface; a negative R value indicates a concave surface. Conversely, for the image-side surface, a positive R value indicates a concave surface; a negative R value indicates a convex surface.

[0054] The present invention discloses an optical lens with a large target surface and low distortion, which includes a first lens to a fifteenth lens in sequence from the object side to the image side along an optical axis; the first lens to the fifteenth lens each include an object-side surface facing the object side and allowing imaging light to pass through, and an image-side surface facing the image side and allowing imaging light to pass through.

[0055] The first lens has a negative refractive power, the object-side surface of the first lens is convex, and the image-side surface of the first lens is concave.

[0056] The second lens element has a positive refractive power, an object-side surface of the second lens element is a convex surface, and an image-side surface of the second lens element is a convex surface.

[0057] The third lens element has a negative refractive power, with both its object-side and image-side surfaces being concave. The concave surfaces on both the image-side and image-side surfaces of the first and third lenses primarily produce positive distortion, offsetting the significant negative distortion produced by the other lens surfaces. The resulting optical system exhibits minimal negative distortion.

[0058] The fourth lens element has a positive refractive power, an object-side surface of the fourth lens element is concave, and an image-side surface of the fourth lens element is convex.

[0059] The fifth lens element has a negative refractive power, the object-side surface of the fifth lens element is concave, and the image-side surface of the fifth lens element is convex.

[0060] The sixth lens element has a positive refractive power, an object-side surface of the sixth lens element is concave, and an image-side surface of the sixth lens element is convex.

[0061] The seventh lens element has a negative refractive power, the object-side surface of the seventh lens element is concave, and the image-side surface of the seventh lens element is convex.

[0062] The eighth lens element has a positive refractive power, and the object-side surface and image-side surface of the eighth lens element are convex.

[0063] The ninth lens element has a positive refractive power, the object-side surface of the ninth lens element is convex, and the image-side surface of the ninth lens element is convex.

[0064] The tenth lens element has a negative refractive power, the object-side surface of the tenth lens element is concave, and the image-side surface of the tenth lens element is concave.

[0065] The eleventh lens has a positive refractive power, the object-side surface of the eleventh lens is convex, and the image-side surface of the eleventh lens is convex.

[0066] The twelfth lens has positive refractive power, the object-side surface of the twelfth lens is convex, and the image-side surface of the twelfth lens is convex.

[0067] The thirteenth lens has a negative refractive power, the object-side surface of the thirteenth lens is concave, and the image-side surface of the thirteenth lens is concave.

[0068] The fourteenth lens has a positive refractive power, the object-side surface of the fourteenth lens is convex, and the image-side surface of the fourteenth lens is convex.

[0069] The fifteenth lens has a negative refractive power, the object-side surface of the fifteenth lens is concave, and the image-side surface of the fifteenth lens is convex.

[0070] The second lens and the third lens are cemented together, the fourth lens and the fifth lens are cemented together, the sixth lens and the seventh lens are cemented together, the ninth lens and the tenth lens are cemented together, the twelfth lens and the thirteenth lens are cemented together, and the fourteenth lens and the fifteenth lens are cemented together. Multiple groups of double-cemented lenses are used to correct chromatic aberration and reduce the separation of diffuse spot color light.

[0071] The optical lens comprises only the first through fifteenth lenses described above. The present invention utilizes the fifteen lenses described above and, through appropriate design of each lens, achieves high resolution, supports 12MP resolution, a large image plane, minimal distortion, high illumination, a large aperture, excellent low-light performance, minimal chromatic aberration, and reduced separation of diffuse speckled light.

[0072] Preferably, an aperture is further included, which is arranged on the object side of the first lens, so that the actual image height of the off-axis field of view is smaller than the ideal image height, the distortion of the optical lens system becomes a negative value, and the aperture of the optical lens is reduced, thereby reducing the difficulty of the optical system at the front end of the optical lens.

[0073] More preferably, the optical lens further satisfies the following conditions: nd1>1.9, nd2>1.9, nd3≥1.9, nd5>1.9, nd6≥1.9, nd8≥1.9, and nd15>1.9, wherein nd1, nd2, nd3, nd5, nd6, nd8, nd9, and nd15 are the refractive indices of the first lens, the second lens, the third lens, the fifth lens, the sixth lens, the eighth lens, the ninth lens, and the fifteenth lens, respectively. This is beneficial for reducing the curvature radius of the lens surface while keeping the optical power unchanged, thereby reducing the system sensitivity and indirectly improving the resolution of the system.

[0074] Preferably, the optical lens further satisfies: yp1 / StopD>0.7, wherein yp1 is the lateral height of the intersection of light rays at the aperture stop over the entire field of view, and StopD is the half-aperture value of the aperture stop.

[0075] Preferably, the optical lens further satisfies: f / Dstop<2.0, wherein Dstop is the outer diameter of the aperture, and f is the focal length of the optical lens, which reduces the F value of the system and has a good low-light effect.

[0076] Preferably, the optical lens further satisfies: 10.0<|fg4 / f|<15.0, 0<|fg5 / f|<3.0, 1.0<|fg6 / f|<5.0, wherein fg4 is the combined focal length of the ninth lens and the tenth lens, fg5 is the combined focal length of the twelfth lens and the thirteenth lens, and fg4 is the combined focal length of the fourteenth lens and the fifteenth lens, thereby further correcting the chromatic aberration of the optical system and reducing the degree of chromatic aberration diffusion.

[0077] Preferably, the optical lens also satisfies: Pg.F3>0.55, where Pg.F3 is the relative partial dispersion coefficient of the third lens. Using materials that deviate from the normal dispersion curve can better correct the chromatic aberration of the optical system. For the aperture pre-system, it can significantly compensate for the defects of the system itself, thereby improving the chromatic aberration performance of the optical system.

[0078] Preferably, the optical lens further satisfies the following requirement: Pg.F6>0.53, where Pg.F6 is the relative partial dispersion coefficient of the sixth lens element. Using materials that deviate from the normal dispersion curve can better correct the chromatic aberration of the optical system. For the pre-aperture system, it can significantly compensate for the defects of the system itself, thereby improving the chromatic aberration performance of the optical system.

[0079] Preferably, the optical lens further satisfies the following requirements: Pg.F13>0.42, where Pg.F13 is the relative partial dispersion coefficient of the thirteenth lens. Using materials that deviate from the normal dispersion curve can better correct the chromatic aberration of the optical system. For the pre-aperture system, it can significantly compensate for the defects of the system itself, thereby improving the chromatic aberration performance of the optical system.

[0080] Preferably, the optical lens also satisfies: f / Diag<1.33, wherein f is the focal length of the optical lens, and Diag is the image diameter of the optical lens, which ensures a larger image surface while avoiding an excessively large target surface that increases design difficulty.

[0081] The optical lens with large target surface and low distortion of the present invention will be described in detail with reference to specific embodiments below.

[0082] Example 1

[0083] like Figure 1 As shown, an optical lens with a large target surface and low distortion includes, from object side A1 to image side A2, an aperture 160, a first lens 10, a second lens 20, a third lens 30, a fourth lens 40, a fifth lens 50, a sixth lens 60, a seventh lens 70, an eighth lens 80, a ninth lens 90, a tenth lens 100, an eleventh lens 110, a twelfth lens 120, a thirteenth lens 130, a fourteenth lens 140, a fifteenth lens 150, a protective glass 170, and an imaging surface 180. The first to fifteenth lenses 10 to 150 each include an object-side surface facing the object side A1 and through which imaging light passes, and an image-side surface facing the image side A2 and through which imaging light passes.

[0084] The first lens element 10 has a negative refractive power. The object-side surface 11 of the first lens element 10 is a convex surface, and the image-side surface 12 of the first lens element 10 is a concave surface.

[0085] The second lens element 20 has a positive refractive power. The object-side surface 21 of the second lens element 20 is a convex surface, and the image-side surface 22 of the second lens element 20 is a convex surface.

[0086] The third lens element 30 has a negative refractive power. The object-side surface 31 of the third lens element 30 is concave, and the image-side surface 32 of the third lens element 30 is concave.

[0087] The fourth lens element 40 has a positive refractive power. The object-side surface 41 of the fourth lens element 40 is concave, and the image-side surface 42 of the fourth lens element 40 is convex.

[0088] The fifth lens element 50 has a negative refractive power. The object-side surface 51 of the fifth lens element 50 is concave, and the image-side surface 52 of the fifth lens element 50 is convex.

[0089] The sixth lens element 60 has a positive refractive power. The object-side surface 61 of the sixth lens element 60 is concave, and the image-side surface 62 of the sixth lens element 60 is convex.

[0090] The seventh lens element 70 has a negative refractive power. The object-side surface 71 of the seventh lens element 70 is concave, and the image-side surface 72 of the seventh lens element 70 is convex.

[0091] The eighth lens element 80 has a positive refractive power. The object-side surface 81 of the eighth lens element 80 is a convex surface, and the image-side surface 82 of the eighth lens element 80 is a convex surface.

[0092] The ninth lens element 90 has a positive refractive power. The object-side surface 91 of the ninth lens element 90 is a convex surface, and the image-side surface 92 of the ninth lens element 90 is a convex surface.

[0093] The tenth lens element 100 has a negative refractive power. The object-side surface 101 of the tenth lens element 100 is concave, and the image-side surface 102 of the tenth lens element 100 is concave.

[0094] The eleventh lens element 110 has a positive refractive power. The object-side surface 111 of the eleventh lens element 110 is a convex surface. The image-side surface 112 of the eleventh lens element 110 is a convex surface.

[0095] The twelfth lens 120 has a positive refractive power. The object-side surface 121 of the twelfth lens 120 is a convex surface, and the image-side surface 122 of the twelfth lens 120 is a convex surface.

[0096] The thirteenth lens element 130 has a negative refractive power. The object-side surface 131 of the thirteenth lens element 130 is a concave surface, and the image-side surface 132 of the thirteenth lens element 130 is a concave surface.

[0097] The fourteenth lens 140 has a positive refractive power. The object-side surface 141 of the fourteenth lens 140 is a convex surface, and the image-side surface 142 of the fourteenth lens 140 is a convex surface.

[0098] The fifteenth lens element 150 has a negative refractive power. The object-side surface 151 of the fifteenth lens element 150 is concave, and the image-side surface 152 of the fifteenth lens element 150 is convex.

[0099] The second lens 20 and the third lens 30 are cemented together, the fourth lens 40 and the fifth lens 50 are cemented together, the sixth lens 60 and the seventh lens 70 are cemented together, the ninth lens 90 and the tenth lens 100 are cemented together, the twelfth lens 120 and the thirteenth lens 130 are cemented together, and the fourteenth lens 140 and the fifteenth lens 150 are cemented together.

[0100] In this specific embodiment, the relative partial dispersion coefficient Pg.F3 of the third lens element is greater than 0.55, the relative partial dispersion coefficient Pg.F6 of the sixth lens element is greater than 0.53, and the relative partial dispersion coefficient Pg.F13 of the thirteenth lens element is greater than 0.42.

[0101] In other embodiments, the aperture 160 may also be set at other positions.

[0102] The detailed optical data of this specific embodiment are shown in Table 1-1.

[0103] Table 1-1 Detailed optical data of Example 1

[0104]

[0105]

[0106] Please refer to Table 5 for the values ​​of the relevant conditional expressions of this specific embodiment.

[0107] For details of the field curvature and distortion curves of this specific embodiment, see Figure 2 (A) and (B) show that the field curvature is within 0.05mm, the distance between the meridional ray and the sagittal ray is very small, the astigmatism is well corrected, and the astigmatism has a maximum value near the 0.7 field of view, about 0.03mm. The relative optical distortion is within -1.2%, which can meet the distortion requirements of the machine vision field. For details of the MTF curve, see Figure 3 , it can be seen that at 145lp / mm, the resolution is higher than 0.3; see the magnification chromatic aberration curve for details. Figure 4 It can be seen that the chromatic aberration is small, the chromatic aberration of the entire field of view is ≤2.5μm, there is no purple fringing phenomenon, and the color reproduction is high.

[0108] The illumination of this specific embodiment is greater than 70%.

[0109] In this specific embodiment, the focal length of the optical imaging lens is f=23.3 mm; the field of view angle FOV=42.0°; the image plane diameter Diag=17.6 mm; the aperture value FNO=1.9; and the distance TTL from the aperture 160 to the imaging plane 180 on the optical axis I is 83.4 mm.

[0110] Example 2

[0111] like Figure 5 As shown, the surface profile and refractive index of each lens in this embodiment are the same as those in the first embodiment, and only the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0112] The detailed optical data of this specific embodiment are shown in Table 2-1.

[0113] Table 2-1 Detailed optical data of Example 2

[0114]

[0115]

[0116] Please refer to Table 5 for the values ​​of the relevant conditional expressions of this specific embodiment.

[0117] For details of the field curvature and distortion curves of this specific embodiment, see Figure 6 (A) and (B) show that the field curvature is within 0.05mm, the distance between the meridional ray and the sagittal ray is very small, the astigmatism is well corrected, and the astigmatism has a maximum value near the 0.7 field of view, about 0.03mm. The relative optical distortion is within -1.2%, which can meet the distortion requirements of the machine vision field. For details of the MTF curve, see Figure 7 , it can be seen that at 145lp / mm, the resolution is higher than 0.3; see the magnification chromatic aberration curve for details. Figure 8 It can be seen that the chromatic aberration is small, the chromatic aberration of the entire field of view is ≤2.7μm, there is no purple fringing phenomenon, and the color reproduction is high.

[0118] The illumination of this specific embodiment is greater than 70%.

[0119] In this specific embodiment, the focal length of the optical imaging lens is f=23.3 mm; the field of view angle FOV=42.0°; the image plane diameter Diag=17.6 mm; the aperture value FNO=1.9; and the distance TTL from the aperture 160 to the imaging plane 180 on the optical axis I is 83.1 mm.

[0120] Example 3

[0121] like Figure 9 As shown, the surface profile and refractive index of each lens in this embodiment are the same as those in the first embodiment, and only the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0122] The detailed optical data of this specific embodiment are shown in Table 3-1.

[0123] Table 3-1 Detailed optical data of Example 3

[0124] surface Curvature radius / mm Thickness / interval / mm Material Refractive index Dispersion coefficient Focal length / mm 160 aperture Infinity 0.5 11 First lens 39.2 1.1 H-ZLAF90 2.0 25.4 -30.8 12 17.0 0.8 21 Second lens 39.0 8.2 H-ZLAF90 2.0 25.4 8.4 22 -9.6 0 31 The third lens -9.6 1.1 H-ZF88 1.9 17.9 -9.0 32 77.8 3.4 41 Fourth lens -12.1 4.6 H-LAF10LA 1.8 47.5 35.2 42 -9.8 0 51 Fifth lens -9.8 1.2 H-ZLAF92 2.0 28.3 -26.7 52 -16.4 0.1 61 Sixth lens -50.1 5.1 H-ZF88 1.9 17.9 34.4 62 -20.7 0 71 Seventh lens -20.7 1.2 H-ZF11 1.7 30.1 -51.8 72 -49.5 0.1 81 Eighth lens 174.7 5.8 H-ZF88 1.9 17.9 40.9 82 -49.0 0.5 91 Ninth lens 57.0 14.0 H-ZPK5 1.6 68.3 26.9 92 -20.2 0 101 Tenth lens -20.2 1.8 H-ZF4A 1.7 28.3 -26.8 102 677.5 0.1 111 Eleventh lens 81.3 7.0 H-ZLAF68N 1.9 39.2 32.5 112 -42.5 0.2 121 Twelfth lens 61.2 6.1 H-ZPK5 1.6 68.3 30.7 122 -25.0 0 131 Thirteenth lens -25.0 1.2 H-ZF71 1.8 22.7 -12.1 132 16.5 1.5 141 Fourteenth lens 28.9 8.1 H-ZPK5 1.6 68.3 16.1 142 -12.8 0 151 Fifteenth lens -12.8 1.2 H-ZLAF90 2.0 25.4 -18.0 152 -46.6 5.5 170 Protective glass Infinity 0.8 H-K9L 1.5 64.2 Infinity - Infinity 2.2 180 Imaging surface Infinity

[0125] Please refer to Table 5 for the values ​​of the relevant conditional expressions of this specific embodiment.

[0126] For details of the field curvature and distortion curves of this specific embodiment, see Figure 10 (A) and (B) show that the field curvature is within 0.05mm, the distance between the meridional ray and the sagittal ray is very small, the astigmatism is well corrected, and the astigmatism has a maximum value near the 0.7 field of view, about 0.03mm. The relative optical distortion is within -1.2%, which can meet the distortion requirements of the machine vision field. For details of the MTF curve, see Figure 11 , it can be seen that at 145lp / mm, the resolution is higher than 0.3; see the magnification chromatic aberration curve for details. Figure 12 It can be seen that the chromatic aberration is small, the chromatic aberration of the entire field of view is ≤2.5μm, there is no purple fringing phenomenon, and the color reproduction is high.

[0127] The illumination of this specific embodiment is greater than 70%.

[0128] In this specific embodiment, the focal length of the optical imaging lens is f=23.3 mm; the field of view angle FOV=42.0°; the image plane diameter Diag=17.72 mm; the aperture value FNO=1.9; and the distance TTL from the aperture 160 to the imaging plane 180 on the optical axis I is 83.4 mm.

[0129] Example 4

[0130] like Figure 13 As shown, the surface profile and refractive index of each lens in this embodiment are the same as those in the first embodiment, and only the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0131] The detailed optical data of this specific embodiment are shown in Table 4-1.

[0132] Table 4-1 Detailed optical data of Example 4

[0133]

[0134]

[0135] Please refer to Table 5 for the values ​​of the relevant conditional expressions of this specific embodiment.

[0136] For details of the field curvature and distortion curves of this specific embodiment, see Figure 14 (A) and (B) show that the field curvature is within 0.05mm, the distance between the meridional ray and the sagittal ray is very small, the astigmatism is well corrected, and the astigmatism has a maximum value near the 0.7 field of view, about 0.03mm. The relative optical distortion is within -1.2%, which can meet the distortion requirements of the machine vision field. For details of the MTF curve, see Figure 15 , it can be seen that at 145lp / mm, the resolution is higher than 0.3; see the magnification chromatic aberration curve for details. Figure 16 It can be seen that the chromatic aberration is small, the chromatic aberration of the entire field of view is ≤2.7μm, there is no purple fringing phenomenon, and the color reproduction is high.

[0137] The illumination of this specific embodiment is greater than 70%.

[0138] In this specific embodiment, the focal length of the optical imaging lens is f=23.3 mm; the field of view angle FOV=42.0°; the image plane diameter Diag=17.7 mm; the aperture value FNO=1.9; and the distance TTL from the aperture 160 to the imaging plane 180 on the optical axis I is 83.0 mm.

[0139] Table 5 Numerical values ​​of relevant important parameters of four embodiments of the present invention

[0140] Example 1 Example 2 Example 3 Example 4 yp1 / StopD 0.78 0.80 0.79 0.80 f / Dstop 1.94 1.94 1.90 1.93 |fg4 / f| 12.94 12.7 12.9 12.69 |fg5 / f| 1.00 0.93 0.94 0.94 |fg6 / f| 3.80 3.74 3.76 3.71 f / Diag 1.32 1.32 1.31 1.32

[0141] Although the present invention has been particularly shown and described in conjunction with preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made to the present invention without departing from the spirit and scope of the invention as defined in the appended claims, and all such changes are within the scope of protection of the present invention.

Claims

1. An optical lens with a large target surface and low distortion, characterized by: The lens system includes, in order from the object side to the image side along an optical axis, first to fifteenth lenses; each of the first to fifteenth lenses includes an object-side surface facing the object side and allowing imaging light to pass therethrough, and an image-side surface facing the image side and allowing imaging light to pass therethrough; The first lens has a negative refractive power, the object side surface of the first lens is convex, and the image side surface of the first lens is concave; The second lens element has a positive refractive power, the object-side surface of the second lens element is convex, and the image-side surface of the second lens element is convex; The third lens element has a negative refractive power, the object-side surface of the third lens element is concave, and the image-side surface of the third lens element is concave; The fourth lens element has a positive refractive power, the object-side surface of the fourth lens element is concave, and the image-side surface of the fourth lens element is convex; The fifth lens element has a negative refractive power, the object-side surface of the fifth lens element is concave, and the image-side surface of the fifth lens element is convex; The sixth lens element has a positive refractive power, the object-side surface of the sixth lens element is concave, and the image-side surface of the sixth lens element is convex; The seventh lens element has a negative refractive power, the object-side surface of the seventh lens element is concave, and the image-side surface of the seventh lens element is convex; The eighth lens element has a positive refractive power, the object-side surface of the eighth lens element is convex, and the image-side surface of the eighth lens element is convex; The ninth lens element has a positive refractive power, the object-side surface of the ninth lens element is convex, and the image-side surface of the ninth lens element is convex; The tenth lens element has a negative refractive power, the object-side surface of the tenth lens element is concave, and the image-side surface of the tenth lens element is concave; The eleventh lens has a positive refractive power, the object-side surface of the eleventh lens is convex, and the image-side surface of the eleventh lens is convex; The twelfth lens has a positive refractive power, the object-side surface of the twelfth lens is convex, and the image-side surface of the twelfth lens is convex; The thirteenth lens has a negative refractive power, the object-side surface of the thirteenth lens is concave, and the image-side surface of the thirteenth lens is concave; The fourteenth lens has a positive refractive power, the object-side surface of the fourteenth lens is convex, and the image-side surface of the fourteenth lens is convex; The fifteenth lens has a negative refractive power, the object side surface of the fifteenth lens is concave, and the image side surface of the fifteenth lens is convex; The second lens and the third lens are cemented together, the fourth lens and the fifth lens are cemented together, the sixth lens and the seventh lens are cemented together, the ninth lens and the tenth lens are cemented together, the twelfth lens and the thirteenth lens are cemented together, and the fourteenth lens and the fifteenth lens are cemented together; The optical lens has only the first to fifteenth lenses with refractive power.

2. The optical lens with large target area and low distortion according to claim 1, characterized in that: The optical system further includes an aperture stop, which is arranged on the object side of the first lens.

3. The optical lens with large target area and low distortion according to claim 2, characterized in that: The optical lens also satisfies the following requirements: nd1>1.9, nd2>1.9, nd3≥1.9, nd5>1.9, nd6≥1.9, nd8≥1.9, and nd15>1.9, wherein nd1, nd2, nd3, nd5, nd6, nd8, nd9, and nd15 are the refractive indices of the first lens, the second lens, the third lens, the fifth lens, the sixth lens, the eighth lens, the ninth lens, and the fifteenth lens, respectively.

4. The optical lens with large target area and low distortion according to claim 2, characterized in that: The optical lens also satisfies: yp1 / StopD>0.7, where yp1 is the lateral height of the intersection of light rays at the aperture over the full field of view, and StopD is the half-aperture value of the aperture.

5. The optical lens with large target area and low distortion according to claim 2, characterized in that: The optical lens also satisfies: f / Dstop<2.0, where Dstop is the outer diameter of the aperture and f is the focal length of the optical lens.

6. The optical lens with large target area and low distortion according to claim 2, characterized in that: The optical lens also satisfies the following requirements: 10.0<|fg4 / f|<15.0, 0<|fg5 / f|<3.0, 1.0<|fg6 / f|<5.0, wherein fg4 is the combined focal length of the ninth lens and the tenth lens, fg5 is the combined focal length of the twelfth lens and the thirteenth lens, and fg4 is the combined focal length of the fourteenth lens and the fifteenth lens.

7. The optical lens with large target area and low distortion according to claim 2, characterized in that: The optical lens also satisfies: Pg.F3>0.55, where Pg.F3 is the relative partial dispersion coefficient of the third lens.

8. The optical lens with large target area and low distortion according to claim 2, characterized in that: The optical lens further satisfies: Pg.F6>0.53, where Pg.F6 is the relative partial dispersion coefficient of the sixth lens.

9. The optical lens with large target area and low distortion according to claim 2, characterized in that: The optical lens further satisfies: Pg.F13>0.42, where Pg.F13 is the relative partial dispersion coefficient of the thirteenth lens.

10. The optical lens with large target area and low distortion according to claim 2, characterized in that: The optical lens also satisfies: f / Diag<1.33, where f is the focal length of the optical lens and Diag is the image diameter of the optical lens.

Images