Optical imaging system

Abstract

The utility model discloses an optical imaging system, which comprises a first lens with positive focal power, a second lens with positive focal power, a third lens with negative focal power, a fourth lens with negative focal power, a fifth lens with positive focal power, a sixth lens with positive focal power, a seventh lens with negative focal power and an eighth lens with positive focal power which are arranged from an object plane to an image plane along an optical axis, moreover, the second lens and the third lens are cemented to form a first cemented lens group, and the focal power of the first cemented lens group is phi 11. The fourth lens and the fifth lens are glued to form a second glued lens group, and the focal power of the second glued lens group is phi 12; the seventh lens and the eighth lens are glued to form a third glued lens group, and the focal power of the third glued lens group is phi 13; the focal power of the optical imaging system is phi; wherein phi 11 / phi is more than-0.75 and less than-0.50; phi 12 / phi is more than-0.83 and less than 0; and 0 < phi 13 / phi < 0.5. According to the scheme, the design of an optical imaging system with a large aperture and a large target surface can be realized through the balsaming lens group and the focal power distribution of each lens.

Description

Technical Field

[0001] The embodiments of the utility model relate to the technical field of optical devices, and in particular to an optical imaging system. Background Art

[0002] With the rapid development of the automotive industry, people's attention to and demand for driving safety are increasing. Consequently, various assisted driving functions have emerged, such as ADAS, DVR, AVP, AVM, FCW, LDW, and CMS. Most current automotive lenses have apertures above F2.0 and resolutions between 2MP and 5MP. This results in insufficient image clarity in dark environments, hindering further intelligent recognition. Consequently, the demand for advanced driver assistance systems is increasing, and special attention is being paid to the image quality of automotive cameras and the stability of their imaging performance in various temperature environments. Utility Model Content

[0003] The utility model provides an optical imaging system, which realizes the design of an optical imaging system with a larger aperture and a larger target surface by reasonably setting the composition mode, optical power distribution mode, gluing mode and optical power parameters of the lenses.

[0004] The embodiment of the utility model provides an optical imaging system, comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens arranged in sequence along an optical axis from an object plane to an image plane;

[0005] The first lens is a positive power lens, the second lens is a positive power lens, the third lens is a negative power lens, the fourth lens is a negative power lens, the fifth lens is a positive power lens, the sixth lens is a positive power lens, the seventh lens is a negative power lens, and the eighth lens is a positive power lens;

[0006] The second lens and the third lens are cemented together to form a first cemented lens group, and the optical power of the first cemented lens group is Φ11; the fourth lens and the fifth lens are cemented together to form a second cemented lens group, and the optical power of the second cemented lens group is Φ12; the seventh lens and the eighth lens are cemented together to form a third cemented lens group, and the optical power of the third cemented lens group is Φ13; the optical power of the optical imaging system is Φ;

[0007] Among them, -0.75<Φ11 / Φ<-0.50; -0.83<Φ12 / Φ<0; 0<Φ13 / Φ<0.5.

[0008] Optionally, the optical focal power of the first lens is Φ1, the optical focal power of the second lens is Φ2, the optical focal power of the third lens is Φ3, the optical focal power of the fourth lens is Φ4, the optical focal power of the fifth lens is Φ5, the optical focal power of the sixth lens is Φ6, the optical focal power of the seventh lens is Φ7, and the optical focal power of the eighth lens is Φ8;

[0009] Among them, 0.2<Φ1 / Φ<0.8; 0.45<Φ2 / Φ<1.48; -2.3<Φ3 / Φ<-1.3;

[0010] -3.2<Φ4 / Φ<-1.6; 1.3<Φ5 / Φ<2.2; 0.45<Φ6 / Φ<1.5;

[0011] -1.2<Φ7 / Φ<-0.23; 0.65<Φ8 / Φ<1.72.

[0012] Optionally, the distance between the object side surface of the first lens and the imaging plane on the optical axis is TTL, the effective focal length of the optical imaging system is f, and the maximum effective image plane of the optical imaging system is IM;

[0013] Among them, 1.85<TTL / f<2.3; 0.27<IM / f<0.32.

[0014] Optionally, the object-side central curvature radius of the second lens is R21, and the image-side central curvature radius is R22;

[0015] Among them, -2.7≤(R21-R22) / (R21+R22)≤0.

[0016] Optionally, the refractive index of the second lens is nd2, and the Abbe number is vd2; the refractive index of the third lens is nd3, and the Abbe number is vd3; the refractive index of the fourth lens is nd4, and the Abbe number is vd4; the refractive index of the fifth lens is nd5, and the Abbe number is vd5; the refractive index of the seventh lens is nd7, and the Abbe number is vd7; the refractive index of the eighth lens is nd8, and the Abbe number is vd8;

[0017] Among them, nd2 / nd3<1.0, vd2 / vd3<3.5; 0.8<nd4 / nd5, vd4 / vd5<0.85;

[0018] nd7 / nd8<1.5, vd7 / vd8<0.51.

[0019] Optionally, the distance between the object side surface of the first lens and the imaging surface on the optical axis is TTL, and the optical back focus of the optical imaging system is BFL;

[0020] Among them, BFL / TTL≥0.12.

[0021] Optionally, the refractive index of the first lens is nd1;

[0022] Among them, nd1>1.8.

[0023] Optionally, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens are all glass spherical lenses.

[0024] Optionally, the optical imaging system further includes an aperture and a filter;

[0025] The aperture is arranged in the optical path between the third lens and the fourth lens;

[0026] The filter is arranged in the optical path between the eighth lens and the image plane.

[0027] Optionally, the aperture number of the optical imaging system is F#;

[0028] Among them, F#≤1.6.

[0029] An optical imaging system provided by an embodiment of the present utility model includes eight lenses, and the optical power combination of the eight lenses is positive-positive-negative-negative-positive-positive-negative-positive; at the same time, the second lens and the third lens are cemented to form a first cemented lens group, and the optical power Φ11 of the first cemented lens group satisfies the optical power Φ of the optical imaging system by -0.75<Φ11 / Φ<-0.50; the fourth lens and the fifth lens are cemented to form a second cemented lens group, and the optical power Φ12 of the second cemented lens group satisfies the optical power Φ of the optical imaging system by -0.83<Φ12 / Φ<0; the seventh lens and the eighth lens are cemented to form a third cemented lens group, and the optical power Φ13 of the third cemented lens group satisfies the optical power Φ of the optical imaging system by 0<Φ13 / Φ<0.5. By rationally setting up the eight lenses and the optical power combination of the eight lenses in the optical imaging system, as well as setting up the cemented lens group and the optical power combination, the image surface can be increased as much as possible while ensuring the imaging quality, achieving the goal of a large target surface; at the same time, the large aperture design of F#1.6 can be well realized.

[0030] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present invention, nor is it intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] 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.

[0032] Figure 1 This is a schematic structural diagram of an optical imaging system provided in Example 1 of the present utility model;

[0033] Figure 2 This is a schematic diagram of an axial aberration curve of an optical imaging system provided in Example 1 of the present utility model;

[0034] Figure 3 This is a schematic diagram of a field curvature distortion curve of an optical imaging system provided in the first embodiment of the present utility model;

[0035] Figure 4 This is a structural diagram of an optical imaging system provided by Example 2 of the present utility model;

[0036] Figure 5 This is a schematic diagram of an axial aberration curve of an optical imaging system provided in Example 2 of the present utility model;

[0037] Figure 6 This is a schematic diagram of a field curvature distortion curve of an optical imaging system provided in the second embodiment of the present utility model;

[0038] Figure 7 This is a structural diagram of an optical imaging system provided in Example 3 of the present utility model;

[0039] Figure 8 This is a schematic diagram of an axial aberration curve of an optical imaging system provided in Example 3 of the present utility model;

[0040] Figure 9 This is a schematic diagram of a field curvature distortion curve of an optical imaging system provided in Example 3 of the present utility model. DETAILED DESCRIPTION

[0041] In order to help those skilled in the art better understand the present invention, the following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0042] Example 1

[0043] Figure 1 This is a schematic diagram of the structure of an optical imaging system provided in the first embodiment of the present invention. Figure 1 As shown, the optical imaging system provided by the first embodiment of the present invention includes a first lens 101, a second lens 102, a third lens 103, a fourth lens 104, a fifth lens 105, a sixth lens 106, a seventh lens 107 and an eighth lens 108, which are arranged in sequence along the optical axis from the object plane to the image plane; the first lens 101 is a positive focal power lens, the second lens 102 is a positive focal power lens, the third lens 103 is a negative focal power lens, the fourth lens 104 is a negative focal power lens, the fifth lens 105 is a positive focal power lens, the sixth lens 106 is a positive focal power lens, the seventh lens 107 is a negative focal power lens, and the eighth lens 108 is a negative focal power lens. Lens 108 is a positive-power lens; the second lens 102 and the third lens 103 are cemented together to form a first cemented lens group, and the optical power of the first cemented lens group is Φ11; the fourth lens 104 and the fifth lens 105 are cemented together to form a second cemented lens group, and the optical power of the second cemented lens group is Φ12; the seventh lens 107 and the eighth lens 108 are cemented together to form a third cemented lens group, and the optical power of the third cemented lens group is Φ13; the optical power of the optical imaging system is Φ; wherein, -0.75<Φ11 / Φ<-0.50; -0.83<Φ12 / Φ<0; 0<Φ13 / Φ<0.5.

[0044] Specifically, the optical imaging system provided by the embodiment of the present invention includes eight lenses, namely a first lens 101, a second lens 102, a third lens 103, a fourth lens 104, a fifth lens 105, a sixth lens 106, a seventh lens 107 and an eighth lens 108. The arrangement of eight lenses ensures that the number of lenses in the optical imaging system is reasonably arranged, which is conducive to the miniaturization of the optical imaging system.

[0045] Furthermore, the focal length is equal to the difference between the convergence of the image plane light beam and the convergence of the object plane light beam, and it characterizes the ability of the optical system to deflect light. The larger the absolute value of the focal length, the stronger the ability to bend light, and the smaller the absolute value of the focal length, the weaker the ability to bend light. When the focal length is a positive number, the refraction of light is convergent; when the focal length is a negative number, the refraction of light is divergent. The focal length can be used to characterize a certain refractive surface of a lens (i.e., a surface of a lens), can be used to characterize a certain lens, and can also be used to characterize a system formed by multiple lenses (i.e., a lens group).

[0046] In the embodiment of the present invention, the first lens 101 and the second lens 102 are both positive power lenses, and the setting of their positive power can significantly correct the edge aberration of the optical imaging system, thereby improving the imaging resolution of the optical system. The third lens 103 and the fourth lens 104 are both negative power lenses, and the setting of their negative power can effectively deflect the incident light at a large angle, ensuring that more light enters the optical system. The fifth lens 105 and the sixth lens 106 are both positive power lenses, and the setting of their positive power can timely correct the larger aberrations generated by the third lens 103 and the fourth lens 104. The seventh lens 107 is a negative power lens, and the eighth lens 108 is a positive power lens. The negative-positive power combination of the seventh lens 107 and the eighth lens can further modulate the light incident thereon, thereby ensuring the imaging quality of the optical imaging system.

[0047] Furthermore, in the optical imaging system provided by an embodiment of the present invention, the second lens 102 and the third lens 103 are cemented together to form a first cemented lens group, the fourth lens 104 and the fifth lens 105 are cemented together to form a second cemented lens group, and the seventh lens 107 and the eighth lens 108 are cemented together to form a third cemented lens group. Specifically, the cemented arrangement of the second lens 102 and the third lens 103 can be understood as the side surface of the second lens 102 near the image side being bonded to the side surface of the third lens 103 near the object plane, that is, the image-side surface of the second lens 102 is bonded to the object-side surface of the third lens 103. The cemented arrangement of the fourth lens 104 and the fifth lens 105 can be understood as the side surface of the fourth lens 104 near the image side being bonded to the side surface of the fifth lens 105 near the object plane, that is, the image-side surface of the fourth lens 1041 is bonded to the object-side surface of the fifth lens 105. The seventh lens element 107 and the eighth lens element 108 are cemented together, meaning that the image-side surface of the seventh lens element 107 is bonded to the object-side surface of the eighth lens element 108. That is, the image-side surface of the seventh lens element 107 is bonded to the object-side surface of the eighth lens element 108. By cementing the second lens element 102 and the third lens element 103, the fourth lens element 104 and the fifth lens element 105, and the seventh lens element 107 and the eighth lens element 108, the air gaps between the second lens element 102 and the third lens element 103, the air gaps between the fourth lens element 104 and the fifth lens element 105, and the air gaps between the seventh lens element 107 and the eighth lens element 108 can be reduced. This helps reduce the overall optical length of the lens element and mitigates tolerance sensitivity issues such as tilt and deflection that may arise during lens element assembly. This simplifies the assembly process during lens manufacturing and improves equipment efficiency. At the same time, the second lens 102 and the third lens 103 are glued together, the fourth lens 104 and the fifth lens 105 are glued together, and the seventh lens 107 and the eighth lens 108 are glued together, which can also reduce light loss caused by reflection between lenses, improve illumination, and reduce the risk of ghosting. Furthermore, the glued lenses can be used to minimize or eliminate chromatic aberration. Using glued lenses in an optical imaging system can improve image quality, reduce reflection loss of light energy, thereby improving image quality and enhancing the clarity of lens imaging. Furthermore, the second lens 102 and the third lens 103 can be supported by a gasket or glued together; the fourth lens 104 and the fifth lens 105 can be supported by a gasket or glued together; the seventh lens 107 and the eighth lens 108 can be supported by a gasket or glued together. The embodiments of the present invention do not limit the specific gluing method.Furthermore, by providing a cemented lens and reasonably setting its optical focal length, it is beneficial to balance the chromatic aberration of the lens system; it is also beneficial to correct the chromatic aberration and improve the imaging quality of the optical system; at the same time, it can also smoothly transmit light, reduce the tolerance sensitivity of the optical system, and improve the assembly yield of the optical system.

[0048] Furthermore, the focal power Φ11 of the first cemented lens formed by cementing the second lens 102 and the third lens 103 satisfies -0.75<Φ11 / Φ<-0.50 with the focal power Φ of the optical imaging system; the focal power Φ12 of the second cemented lens formed by cementing the fourth lens 104 and the fifth lens 105 satisfies -0.83<Φ12 / Φ<0 with the focal power Φ of the optical imaging system; and the focal power Φ13 of the third cemented lens formed by cementing the seventh lens 107 and the eighth lens 108 satisfies 0<Φ13 / Φ<0.5 with the focal power Φ of the optical imaging system. By limiting the focal power of the cemented lens group, chromatic aberration can be further corrected, imaging quality can be improved, and performance effects caused by ambient temperature changes can be compensated.

[0049] In summary, the optical imaging system provided by the embodiment of the present invention is configured to include eight lenses, and the optical power combination of the eight lenses satisfies positive-positive-negative-negative-positive-positive-negative-positive; at the same time, by setting the bonding method between different lenses and the optical power of the bonded lens group, while ensuring the imaging quality, the image surface can be increased as much as possible to achieve the goal of a large target surface; at the same time, the large aperture design of F#1.6 can be well realized.

[0050] Based on the above embodiment, the optical imaging lens provided by the embodiment of the present invention may further include an aperture (not shown in the figure) and a filter 109; the aperture is arranged in the optical path between the third lens 103 and the fourth lens 104; the filter 109 is arranged in the optical path between the eighth lens 108 and the image plane.

[0051] Specifically, the aperture is disposed in the optical imaging system, specifically in the optical path between the third lens 103 and the fourth lens 104. This can effectively reduce the aperture of the lens located before the aperture in the optical imaging system and reduce the weight of the lens. On the other hand, it is beneficial to reduce the value of the aperture number and achieve a large aperture. In this embodiment, the aperture number F# of the system can satisfy F#≤1.6, for example, the aperture number F# can be 1.60.

[0052] For further reference, Figure 1As shown, the optical imaging system provided by the embodiment of the present invention may further include a filter 109, which is arranged in the optical path between the eighth lens 108 and the image plane to filter out stray light and improve the imaging effect. Specifically, the filter 109 may be an infrared filter. Furthermore, the optical imaging system provided by the embodiment of the present invention may further include a protective glass and an image acquisition element (not shown in the figure). The protective glass may be arranged on the image side of the filter, and the image acquisition element may be arranged on the image side of the protective glass. The optical system is protected by the protective glass, and the image is acquired by the image acquisition element to realize the normal imaging function of the optical system.

[0053] Based on the above embodiment, the focal power of the first lens 101 is Φ1, the focal power of the second lens 102 is Φ2, the focal power of the third lens 103 is Φ3, the focal power of the fourth lens 104 is Φ4, the focal power of the fifth lens 105 is Φ5, the focal power of the sixth lens 106 is Φ6, the focal power of the seventh lens 107 is Φ7, and the focal power of the eighth lens 108 is Φ8; wherein, 0.2<Φ1 / Φ<0.8; 0.45<Φ2 / Φ<1.48; -2.3<Φ3 / Φ<-1.3; -3.2<Φ4 / Φ<-1.6; 1.3<Φ5 / Φ<2.2; 0.45<Φ6 / Φ<1.5; -1.2<Φ7 / Φ<-0.23; and 0.65<Φ8 / Φ<1.72. Reasonable optical power distribution enables the system to have smaller aberrations while meeting the design indicators. At the same time, the system tolerance sensitivity is low, which can reduce the assembly process requirements and make the system more cost-effective.

[0054] Based on the above embodiment, the distance from the object side surface of the first lens 101 to the imaging surface on the optical axis is TTL, the effective focal length of the optical imaging system is f, and the maximum effective image surface of the optical imaging system is IM; wherein, 1.85<TTL / f<2.3; 0.27<IM / f<0.32. By limiting the relationship between the total optical length and the effective focal length of the optical imaging system, the total optical length of the optical imaging system is controlled while satisfying the field angle range of the optical imaging system, thereby meeting the miniaturization characteristics of the optical imaging system. If the lower limit of the above conditional expression is exceeded, the effective focal length of the system is too long, and the field angle range of the system cannot be satisfied; if the upper limit of the conditional expression is exceeded, the total optical length of the system is too long, and the miniaturization characteristics of the system cannot be satisfied. By limiting the relationship between the maximum effective image surface and the effective focal length, the characteristics of the optical imaging system with a large target surface are achieved while satisfying the miniaturization characteristics of the optical imaging system.

[0055] Based on the above embodiment, the object-side central radius of curvature of the second lens 102 is R21, and the image-side central radius of curvature is R22; where -2.7 ≤ (R21 - R22) / (R21 + R22) ≤ 0. These limitations facilitate correction of system aberrations, resulting in better imaging quality for the optical imaging system and reducing system light energy loss.

[0056] Based on the above embodiment, the refractive index of the second lens 102 is nd2, and the Abbe number is vd2; the refractive index of the third lens 103 is nd3, and the Abbe number is vd3; the refractive index of the fourth lens 104 is nd4, and the Abbe number is vd4; the refractive index of the fifth lens 105 is nd5, and the Abbe number is vd5; the refractive index of the seventh lens 107 is nd7, and the Abbe number is vd7; and the refractive index of the eighth lens 108 is nd8, and the Abbe number is vd8. Here, nd2 / nd3 < 1.0, vd2 / vd3 < 3.5; 0.8 < nd4 / nd5, vd4 / vd5 < 0.85; nd7 / nd8 < 1.5, and vd7 / vd8 < 0.51. By limiting the ratio of the refractive indices and the ratio of the Abbe numbers of the two lenses in the cemented lens group, it is advantageous to correct the chromatic aberration and aberration of the system, thereby improving the imaging quality of the optical imaging system.

[0057] Based on the above embodiment, the distance between the object-side surface of the first lens 101 and the imaging plane on the optical axis is TTL, and the optical back focus of the optical imaging system is BFL; where BFL / TTL ≥ 0.12. With the above definition, the back focus is shortened while miniaturization is achieved, facilitating assembly of the optical imaging system.

[0058] Based on the above embodiment, the refractive index of the first lens 101 is nd1, wherein nd1>1.8. By limiting the refractive index of the first lens 101, it is beneficial to reduce the front port diameter and improve the imaging quality.

[0059] Based on the above embodiment, the first lens 101 , the second lens 102 , the third lens 103 , the fourth lens 104 , the fifth lens 105 , the sixth lens 106 , the seventh lens 107 and the eighth lens 108 are all glass spherical lenses.

[0060] Specifically, spherical lenses are characterized by a constant curvature from the center to the periphery, ensuring a simple lens configuration. Furthermore, because glass lenses have a low coefficient of thermal expansion and excellent stability, the first lens 101, the second lens 102, the third lens 103, the fourth lens 104, the fifth lens 105, the sixth lens 106, the seventh lens 107, and the eighth lens 108 can all be glass spherical lenses. Glass spherical lenses have more stable thermal properties, ensuring good resolution over a wide temperature range when carrying a high optical power. Furthermore, compared to plastic aspherical lenses, glass materials offer a wider range of options, with relatively free choices of refractive index and Abbe number. This allows for control of higher-order aberrations and chromatic aberrations in the lens to a certain extent, meeting the requirements of use under complex conditions.

[0061] As a feasible implementation method, the specific parameters in the optical imaging system are described below.

[0062] Table 1 Optical design values ​​of the optical imaging system in Example 1

[0063] Example 1 Upper limit Lower limit Φ1 / Φ 0.51 0.8 0.2 Φ2 / Φ 1.09 1.48 0.45 Φ3 / Φ -1.97 -1.3 -2.3 Φ4 / Φ -2.02 -1.6 -3.2 Φ5 / Φ 1.65 2.2 1.3 Φ6 / Φ 0.83 1.5 0.45 Φ7 / Φ -0.69 -0.23 -1.2 Φ8 / Φ 1.04 1.72 0.65 Φ11 / Φ -0.63 -0.5 -0.75 Φ12 / Φ -0.02 0 -0.83 Φ13 / Φ 0.11 0.5 0 TTL / F 2.13 2.3 1.85 IM / F 0.29 0.32 0.27 nd2 / nd3 0.91 1.0 vd2 / vd3 2.18 3.5 nd4 / nd5 0.95 0.8 vd4 / vd5 0.70 0.85 nd7 / nd8 1.32 1.5 vd7 / vd8 0.22 0.51 (R21-R22) / (R21+R22) -2.35 0 -2.7 BFL / TTL 0.15 0.12

[0064] Table 2 Design values ​​of optical physical parameters of an optical imaging system

[0065] Surface number Surface type Curvature radius (mm) Thickness (mm) Nd Vd OBJ spherical surface Infinity Infinity S1 spherical surface 15.76 2.47 1.94 32.1 S2 spherical surface 33.58 1.74 S3 spherical surface 9.42 2.74 1.50 70.0 S4 spherical surface -23.38 0.85 1.65 32.1 S5 spherical surface 6.41 1.89 STO spherical surface Infinity 1.54 S7 spherical surface -8.59 1.54 1.64 37.1 S8 spherical surface 11.55 3.72 1.73 52.7 S9 spherical surface -13.48 0.05 S10 spherical surface 30.95 1.82 1.90 40.0 S11 spherical surface -33.32 1.64 S12 spherical surface 10.49 4.43 1.98 20.0 S13 spherical surface 5.57 2.67 1.50 90.0 S14 spherical surface 21.71 1.80 S15 spherical surface Infinity 0.70 1.52 64.2 S16 spherical surface Infinity 2.14

[0066] The surface numbers in Table 2 are numbered according to the order of the surfaces of each lens, where "OBJ" represents the object plane, "S1" represents the front surface of the first lens, "S2" represents the back surface of the first lens, "STO" represents the aperture, and so on. The radius of curvature represents the degree of curvature of the lens surface. A positive value indicates that the surface is curved toward the image plane, and a negative value indicates that the surface is curved toward the object plane. "Infinity" indicates that the surface is flat and the radius of curvature is infinite. The thickness represents the central axial distance from the current surface to the next surface. The refractive index represents the ability of the material between the current surface and the next surface to deflect light. A blank space represents that the current position is air with a refractive index of 1. The Abbe number represents the dispersion characteristics of the material between the current surface and the next surface. A blank space represents that the current position is air.

[0067] Further, Figure 2This is a schematic diagram of the axial aberration curve of an optical imaging system provided by the first embodiment of the present invention, specifically a schematic diagram of the axial aberration curve when the pupil radius is 4.6046mm. The vertical direction represents the normalized aperture, 0 represents the optical axis, and the vertical vertex represents the maximum pupil radius; the horizontal direction represents the offset relative to the ideal focus, in millimeters (mm). The different linear curves in the figure represent different wavelengths of imaging of the system (436nm, 486nm, 546nm, 588nm and 656nm respectively), which are represented by Figure 2 It can be seen that the axial aberrations at different wavelengths are all controlled within the range of (-0.03mm, +0.03mm), indicating that the axial aberrations of the optical imaging system at each wavelength are well controlled and can meet the requirements of wide spectrum applications.

[0068] Figure 3 This is a schematic diagram of a field curvature distortion curve of an optical imaging system provided by the first embodiment of the present invention. In the coordinate system on the left side of the figure, the horizontal coordinate represents the magnitude of the field curvature, in millimeters (mm); the vertical coordinate represents the normalized image height, without units; Figure 3 As can be seen from the left figure, the lens provided by this embodiment has a maximum field of view of 17.2°, and both the tangential and sagittal curvature of field are effectively controlled at various wavelengths (436nm, 486nm, 546nm, 587nm, and 656nm). This means that when imaging, the difference in image quality between the center and the periphery is small. In the coordinate system on the right, the horizontal coordinate represents the degree of distortion in %, and the vertical coordinate represents the normalized image height, which has no unit. Figure 3 It can be seen from the figure on the right that the distortion of the lens provided in this embodiment is controlled within the range of -5%, and the distortion is relatively small.

[0069] In summary, the optical imaging system provided in Example 1 of the present invention uses eight glass spherical lenses. The number of lenses is reasonable, the structure is simple and compact, the optical power and position of each lens are reasonable, and it can achieve confocality during the day and night, has strong environmental adaptability, and high resolution. At the same time, by reasonably setting the lens bonding method and the optical power of the bonded lens, it can well achieve a large aperture of F#1.6 and a large target surface (supporting 1 / 1.7" SENSOR), maintain good high pixels, and achieve stable imaging quality under temperature changes.

[0070] Example 2

[0071] Figure 4 This is a schematic diagram of the structure of an optical imaging system provided by the second embodiment of the present invention. Figure 4As shown, the optical imaging system provided by the second embodiment of the present invention includes a first lens 101, a second lens 102, a third lens 103, a fourth lens 104, a fifth lens 105, a sixth lens 106, a seventh lens 107 and an eighth lens 108, which are arranged in sequence along the optical axis from the object plane to the image plane; the first lens 101 is a positive focal power lens, the second lens 102 is a positive focal power lens, the third lens 103 is a negative focal power lens, the fourth lens 104 is a negative focal power lens, the fifth lens 105 is a positive focal power lens, the sixth lens 106 is a positive focal power lens, the seventh lens 107 is a negative focal power lens, and the eighth lens 108 is a negative focal power lens. Lens 108 is a positive-power lens; the second lens 102 and the third lens 103 are cemented together to form a first cemented lens group, and the optical power of the first cemented lens group is Φ11; the fourth lens 104 and the fifth lens 105 are cemented together to form a second cemented lens group, and the optical power of the second cemented lens group is Φ12; the seventh lens 107 and the eighth lens 108 are cemented together to form a third cemented lens group, and the optical power of the third cemented lens group is Φ13; the optical power of the optical imaging system is Φ; wherein, -0.75<Φ11 / Φ<-0.50; -0.83<Φ12 / Φ<0; 0<Φ13 / Φ<0.5.

[0072] The configuration of the lens is the same as that in the first embodiment, and will not be described again here.

[0073] As another feasible implementation, specific parameters in the optical imaging system are described below.

[0074] Table 3 Optical design values ​​of the optical imaging system in Example 2

[0075] Example 2 Upper limit Lower limit Φ1 / Φ 0.65 0.8 0.2 Φ2 / Φ 0.71 1.48 0.45 Φ3 / Φ -1.61 -1.3 -2.3 Φ4 / Φ -2.74 -1.6 -3.2 Φ5 / Φ 1.87 2.2 1.3 Φ6 / Φ 1.13 1.5 0.45 Φ7 / Φ -0.85 -0.23 -1.2 Φ8 / Φ 1.38 1.72 0.65 Φ11 / Φ -0.69 -0.5 -0.75 Φ12 / Φ -0.52 0 -0.83 Φ13 / Φ 0.20 0.5 0 TTL / F 2.05 2.3 1.85 IM / F 0.31 0.32 0.27 nd2 / nd3 0.88 1.0 vd2 / vd3 3.13 3.5 nd4 / nd5 0.99 0.8 vd4 / vd5 0.56 0.85 nd7 / nd8 1.27 1.5 vd7 / vd8 0.42 0.51 (R21-R22) / (R21+R22) -0.62 0 -2.7 BFL / TTL 0.12 0.12

[0076] Table 4 Design values ​​of optical physical parameters of an optical imaging system

[0077] Surface number Surface type Curvature radius (mm) Thickness (mm) Nd Vd OBJ spherical surface Infinity Infinity S1 spherical surface 12.88 2.55 1.86 27.93 S2 spherical surface 30.23 0.56 S3 spherical surface 8.53 2.59 1.49 87.73 S4 spherical surface 35.93 0.81 1.69 28.00 S5 spherical surface 5.64 1.04 STO spherical surface Infinity 3.98 S7 spherical surface -6.87 0.66 1.73 26.44 S8 spherical surface 11.37 2.76 1.74 47.60 S9 spherical surface -12.14 0.05 S10 spherical surface 63.57 2.45 1.96 27.87 S11 spherical surface -16.74 0.10 S12 spherical surface 13.54 6.14 2.00 37.29 S13 spherical surface 6.04 4.46 1.57 90.00 S14 spherical surface 69.71 0.80 S15 spherical surface Infinity 0.80 1.52 64.20 S16 spherical surface Infinity 2.26

[0078] The surface numbers in Table 4 are numbered according to the order of the surfaces of each lens, where "OBJ" represents the object plane, "S1" represents the front surface of the first lens, "S2" represents the back surface of the first lens, "STO" represents the aperture, and so on. The radius of curvature represents the degree of curvature of the lens surface. A positive value indicates that the surface is curved toward the image plane, and a negative value indicates that the surface is curved toward the object plane. "Infinity" indicates that the surface is flat and the radius of curvature is infinite. The thickness represents the central axial distance from the current surface to the next surface. The refractive index represents the ability of the material between the current surface and the next surface to deflect light. A blank space represents that the current position is air with a refractive index of 1. The Abbe number represents the dispersion characteristics of the material between the current surface and the next surface. A blank space represents that the current position is air.

[0079] Figure 5 This is a schematic diagram of the axial aberration curve of an optical imaging system provided by Example 2 of the present invention, specifically a schematic diagram of the axial aberration curve when the pupil radius is 4.7322mm. The vertical direction represents the normalized aperture, 0 represents the optical axis, and the vertical vertex represents the maximum pupil radius; the horizontal direction represents the offset relative to the ideal focus, in millimeters (mm). The different linear curves in the figure represent different wavelengths of imaging of the system (436nm, 486nm, 546nm, 588nm and 656nm respectively), which are represented by Figure 5 It can be seen that the axial aberrations at different wavelengths are all controlled within the range of (-0.03mm, +0.03mm), indicating that the axial aberrations of the optical imaging system at each wavelength are well controlled and can meet the requirements of wide spectrum applications.

[0080] Figure 6 This is a schematic diagram of a field curvature distortion curve of an optical imaging system provided by the second embodiment of the present invention. In the coordinate system on the left side of the figure, the horizontal coordinate represents the magnitude of the field curvature, in millimeters (mm); the vertical coordinate represents the normalized image height, without units; Figure 6 As can be seen from the left figure, the lens provided by this embodiment has a maximum field of view of 17.2°, and both the tangential and sagittal curvature of field are effectively controlled at various wavelengths (436nm, 486nm, 546nm, 587nm, and 656nm). This means that when imaging, the difference in image quality between the center and the periphery is small. In the coordinate system on the right, the horizontal coordinate represents the degree of distortion in %, and the vertical coordinate represents the normalized image height, which has no unit. Figure 6 It can be seen from the figure on the right that the distortion of the lens provided in this embodiment is controlled within the range of -5%, and the distortion is relatively small.

[0081] In summary, the optical imaging system provided in Example 2 of the present invention uses eight glass spherical lenses. The number of lenses is reasonable, the structure is simple and compact, the optical power and position of each lens are reasonable, and it can achieve confocality day and night, strong environmental adaptability, and high resolution. At the same time, by reasonably setting the lens bonding method and the optical power of the bonded lens, it can well achieve a large aperture of F#1.6 and a large target area (supporting 1 / 1.7" sensor), maintain good high pixels, and achieve stable imaging quality under temperature changes.

[0082] Example 3

[0083] Figure 7 This is a schematic diagram of the structure of an optical imaging system provided by the third embodiment of the present invention. Figure 7As shown, the optical imaging system provided by the third embodiment of the present invention includes a first lens 101, a second lens 102, a third lens 103, a fourth lens 104, a fifth lens 105, a sixth lens 106, a seventh lens 107 and an eighth lens 108, which are arranged in sequence along the optical axis from the object plane to the image plane; the first lens 101 is a positive focal power lens, the second lens 102 is a positive focal power lens, the third lens 103 is a negative focal power lens, the fourth lens 104 is a negative focal power lens, the fifth lens 105 is a positive focal power lens, the sixth lens 106 is a positive focal power lens, the seventh lens 107 is a negative focal power lens, and the eighth lens 108 is a negative focal power lens. Lens 108 is a positive-power lens; the second lens 102 and the third lens 103 are cemented together to form a first cemented lens group, and the optical power of the first cemented lens group is Φ11; the fourth lens 104 and the fifth lens 105 are cemented together to form a second cemented lens group, and the optical power of the second cemented lens group is Φ12; the seventh lens 107 and the eighth lens 108 are cemented together to form a third cemented lens group, and the optical power of the third cemented lens group is Φ13; the optical power of the optical imaging system is Φ; wherein, -0.75<Φ11 / Φ<-0.50; -0.83<Φ12 / Φ<0; 0<Φ13 / Φ<0.5.

[0084] The configuration of the lens is the same as that in the first embodiment, and will not be described again here.

[0085] As another feasible implementation, specific parameters in the optical imaging system are described below.

[0086] Table 5 Optical design values ​​of the optical imaging system in Example 3

[0087] Example 3 Upper limit Lower limit Φ1 / Φ 0.58 0.8 0.2 Φ2 / Φ 0.97 1.48 0.45 Φ3 / Φ -1.95 -1.3 -2.3 Φ4 / Φ -2.50 -1.6 -3.2 Φ5 / Φ 1.82 2.2 1.3 Φ6 / Φ 1.11 1.5 0.45 Φ7 / Φ -0.79 -0.23 -1.2 Φ8 / Φ 1.32 1.72 0.65 Φ11 / Φ -0.69 -0.5 -0.75 Φ12 / Φ -0.39 0 -0.83 Φ13 / Φ 0.23 0.5 0 TTL / F 2.02 2.3 1.85 IM / F 0.30 0.32 0.27 nd2 / nd3 0.89 1.0 vd2 / vd3 3.07 3.5 nd4 / nd5 0.98 0.8 vd4 / vd5 0.41 0.85 nd7 / nd8 1.24 1.5 vd7 / vd8 0.41 0.51 (R21-R22) / (R21+R22) -1.46 0 -2.7 BFL / TTL 0.15 0.12

[0088] Table 6 Design values ​​of optical physical parameters of an optical imaging system

[0089] Surface number Surface type Curvature radius (mm) Thickness (mm) Nd Vd OBJ spherical surface Infinity Infinity S1 spherical surface 15.35 2.47 1.87 24.91 S2 spherical surface 44.61 1.54 S3 spherical surface 9.15 3.27 1.50 82.53 S4 spherical surface -48.62 0.84 1.68 26.92 S5 spherical surface 6.03 1.24 STO spherical surface Infinity 2.74 S7 spherical surface -6.98 0.48 1.71 25.98 S8 spherical surface 11.82 2.57 1.75 62.64 S9 spherical surface -11.82 0.10 S10 spherical surface 51.09 2.68 1.96 21.60 S11 spherical surface -17.42 0.10 S12 spherical surface 12.09 5.00 2.00 20.27 S13 spherical surface 5.89 2.90 1.61 49.13 S14 spherical surface 30.49 0.80 S15 spherical surface Infinity 0.60 1.52 64.20 S16 spherical surface Infinity 3.05

[0090] The surface numbers in Table 6 are numbered according to the order of the surfaces of each lens, where "OBJ" represents the object plane, "S1" represents the front surface of the first lens, "S2" represents the back surface of the first lens, "STO" represents the aperture, and so on. The radius of curvature represents the degree of curvature of the lens surface. A positive value indicates that the surface is curved toward the image plane, and a negative value indicates that the surface is curved toward the object plane. "Infinity" indicates that the surface is flat and the radius of curvature is infinite. The thickness represents the central axial distance from the current surface to the next surface. The refractive index represents the ability of the material between the current surface and the next surface to deflect light. A blank space represents that the current position is air with a refractive index of 1. The Abbe number represents the dispersion characteristics of the material between the current surface and the next surface. A blank space represents that the current position is air.

[0091] Further, Figure 8 This is a schematic diagram of the axial aberration curve of an optical imaging system provided by Example 3 of the present invention, specifically a schematic diagram of the axial aberration curve when the pupil radius is 4.5634mm. The vertical direction represents the normalized aperture, 0 represents the optical axis, and the vertical vertex represents the maximum pupil radius; the horizontal direction represents the offset relative to the ideal focus, in millimeters (mm). The different linear curves in the figure represent different wavelengths of imaging of the system (436nm, 486nm, 546nm, 588nm and 656nm respectively), which are represented by Figure 8 It can be seen that the axial aberrations at different wavelengths are all controlled within the range of (-0.03mm, +0.03mm), indicating that the axial aberrations of the optical imaging system at each wavelength are well controlled and can meet the requirements of wide spectrum applications.

[0092] Figure 9 This is a schematic diagram of a field curvature distortion curve of an optical imaging system provided by the third embodiment of the present invention. In the coordinate system on the left side of the figure, the horizontal coordinate represents the magnitude of the field curvature, in millimeters (mm); the vertical coordinate represents the normalized image height, without units; Figure 9 As can be seen from the left figure, the lens provided by this embodiment has a maximum field of view of 17.2°, and both the tangential and sagittal curvature of field are effectively controlled at various wavelengths (436nm, 486nm, 546nm, 587nm, and 656nm). This means that when imaging, the difference in image quality between the center and the periphery is small. In the coordinate system on the right, the horizontal coordinate represents the degree of distortion in %, and the vertical coordinate represents the normalized image height, which has no unit. Figure 9 It can be seen from the figure on the right that the distortion of the lens provided in this embodiment is controlled within the range of -5%, and the distortion is relatively small.

[0093] In summary, the optical imaging system provided in Example 3 of the present invention uses eight glass spherical lenses. The number of lenses is reasonable, the structure is simple and compact, the optical focal length and position of each lens are reasonable, and it can achieve confocality during the day and night, has strong environmental adaptability, and high resolution. At the same time, by reasonably setting the lens bonding method and the optical focal length of the bonded lens, it can well achieve a large aperture of F#1.6 and a large target surface (supporting 1 / 1.7" SENSOR), maintain good high pixels, and achieve stable imaging quality under temperature changes.

[0094] The above specific embodiments do not limit the scope of protection of this utility model. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model shall be included within the scope of protection of this utility model.

Claims

1. An optical imaging system, characterized in that: comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens arranged in sequence along the optical axis from the object plane to the image plane; The first lens is a positive power lens, the second lens is a positive power lens, the third lens is a negative power lens, the fourth lens is a negative power lens, the fifth lens is a positive power lens, the sixth lens is a positive power lens, the seventh lens is a negative power lens, and the eighth lens is a positive power lens; The second lens and the third lens are cemented together to form a first cemented lens group, and the optical power of the first cemented lens group is Φ11; the fourth lens and the fifth lens are cemented together to form a second cemented lens group, and the optical power of the second cemented lens group is Φ12; The seventh lens and the eighth lens are cemented together to form a third cemented lens group, and the optical power of the third cemented lens group is Φ13; the optical power of the optical imaging system is Φ; Among them, -0.75<Φ11 / Φ<-0.50; -0.83<Φ12 / Φ<0; 0<Φ13 / Φ<0.

5.

2. The optical imaging system according to claim 1, wherein: The optical power of the first lens is Φ1, the optical power of the second lens is Φ2, the optical power of the third lens is Φ3, the optical power of the fourth lens is Φ4, the optical power of the fifth lens is Φ5, the optical power of the sixth lens is Φ6, the optical power of the seventh lens is Φ7, and the optical power of the eighth lens is Φ8; Among them, 0.2<Φ1 / Φ<0.8; 0.45<Φ2 / Φ<1.48; -2.3<Φ3 / Φ<-1.3; -3.2<Φ4 / Φ<-1.6; 1.3<Φ5 / Φ<2.2; 0.45<Φ6 / Φ<1.5; -1.2<Φ7 / Φ<-0.23; 0.65<Φ8 / Φ<1.

72.

3. The optical imaging system according to claim 1, wherein: The distance between the object side surface of the first lens and the imaging surface on the optical axis is TTL, the effective focal length of the optical imaging system is f, and the maximum effective image surface of the optical imaging system is IM; Among them, 1.85<TTL / f<2.3; 0.27<IM / f<0.

32.

4. The optical imaging system according to claim 1, wherein: The object side center curvature radius of the second lens is R21, and the image side center curvature radius is R22; Among them, -2.7≤(R21-R22) / (R21+R22)≤0.

5. The optical imaging system according to claim 1, wherein: The refractive index of the second lens is nd2, and the Abbe number is vd2; the refractive index of the third lens is nd3, and the Abbe number is vd3; the refractive index of the fourth lens is nd4, and the Abbe number is vd4; the refractive index of the fifth lens is nd5, and the Abbe number is vd5; the refractive index of the seventh lens is nd7, and the Abbe number is vd7; the refractive index of the eighth lens is nd8, and the Abbe number is vd8; Among them, nd2 / nd3<1.0, vd2 / vd3<3.5; 0.8<nd4 / nd5, vd4 / vd5<0.85; nd7 / nd8<1.5, vd7 / vd8<0.

51.

6. The optical imaging system according to claim 1, wherein: The distance between the object side surface of the first lens and the imaging surface on the optical axis is TTL, and the optical back focus of the optical imaging system is BFL; Among them, BFL / TTL≥0.

12.

7. The optical imaging system according to claim 1, wherein: The refractive index of the first lens is nd1; Among them, nd1>1.

8.

8. The optical imaging system according to claim 1, wherein: The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens are all glass spherical lenses.

9. The optical imaging system according to claim 1, wherein: The optical imaging system further includes an aperture and a filter; The aperture is arranged in the optical path between the third lens and the fourth lens; The filter is arranged in the optical path between the eighth lens and the image plane.

10. The optical imaging system according to claim 1, wherein: The aperture number of the optical imaging system is F#; Among them, F#≤1.6.

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