Optical lens

Abstract

The invention provides an optical lens, which sequentially comprises a first lens with negative focal power from an object side to an imaging surface along an optical axis, a second lens with negative focal power, a third lens with positive focal power and a fourth lens with negative focal power from the object side to the imaging surface, the object side surface of the second lens is a concave surface, and the image side surface of the second lens is a concave surface; the object side surface of the third lens is a convex surface, and the image side surface of the third lens is a concave surface; the object side surface of the fourth lens is a convex surface, and the image side surface of the fourth lens is a convex surface; the object side surface of the fifth lens is a convex surface, and the image side surface of the fifth lens is a convex surface; the object side surface of the sixth lens is a concave surface, and the image side surface of the sixth lens is a concave surface; the object side surface of the seventh lens is a convex surface, and the image side surface of the seventh lens is a convex surface; and the object side surface of the eighth lens is a convex surface, and the image side surface of the eighth lens is a concave surface. According to the optical lens, through specific surface shape matching and reasonable focal power distribution, the imaging quality of the optical lens can be improved, and the optical lens has the advantage of being good in imaging quality.

Description

Technical Field

[0001] The present invention relates to the technical field of imaging lenses, and particularly to an optical lens. Background Art

[0002] With the rapid development of fields such as drones, security, and automobiles, the pursuit of the imaging effect of the lenses carried by them has become more diversified. Currently, drones are developing rapidly and have won the favor of consumers with their unique high-altitude perspective and wide shooting range. Correspondingly, the demand for the optical lenses supporting them is also increasing. The optical lenses carried by them require both high-definition image quality and the ability to present large local details, so as to achieve that the local details can be vividly shown even in the high-altitude view and capture close-up pictures of the local area.

[0003] However, the field of view angle of the drone lenses on the market is too small to detect the changes in the surrounding environment comprehensively. How to better achieve a large field of view angle and high imaging quality of the lens is still an urgent problem to be solved. Summary of the Invention

[0004] Aiming at the above problems, the purpose of the present invention is to provide an optical lens with excellent imaging quality.

[0005] The present invention provides an optical lens, which has a total of eight lenses and sequentially includes, along the optical axis from the object side to the imaging surface: A first lens with a negative optical power, whose object side is convex and whose image side is concave; A second lens with a negative optical power, whose object side is concave and whose image side is concave; A third lens with a positive optical power, whose object side is convex and whose image side is concave; A fourth lens with a positive optical power, whose object side is convex and whose image side is convex; A fifth lens with a positive optical power, whose object side is convex and whose image side is convex; A sixth lens with a negative optical power, whose object side is concave and whose image side is concave; A seventh lens with a positive optical power, whose object side is convex and whose image side is convex; An eighth lens with an optical power, whose object side is convex and whose image side is concave; Wherein, the combined focal length fa of the first lens, the second lens, the third lens and the fourth lens and the effective focal length f of the optical lens satisfy: 15 < fa / f < 30; the combined focal length fb of the fifth lens, the sixth lens, the seventh lens and the eighth lens and the effective focal length f of the optical lens satisfy: 2.5 < fb / f < 3.

[0006] Further preferably, the effective focal length f of the optical lens and the true image height IH corresponding to the maximum field of view angle of the optical lens satisfy: 3.4 < IH / f < 3.55; the true image height IH corresponding to the maximum field of view angle of the optical lens and the effective aperture DM11 of the object side of the first lens satisfy: 1.8 < DM11 / IH < 2.2.

[0007] Further preferably, the effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -4 < f1 / f < -3.

[0008] Further preferably, the effective focal length f of the optical lens and the focal length f2 of the second lens satisfy: -2.5 < f2 / f < -2.15.

[0009] Further preferably, the effective focal length f of the optical lens and the focal length f3 of the third lens satisfy: 15 < f3 / f < 25.

[0010] Further preferably, the effective focal length f of the optical lens and the focal length f4 of the fourth lens satisfy: 2.8 < f4 / f < 3.2.

[0011] Further preferably, the effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: 1.5 < f5 / f < 1.7; the effective focal length f of the optical lens and the focal length f6 of the sixth lens satisfy: -1.5 < f6 / f < -1.

[0012] Further preferably, the effective focal length f of the optical lens and the focal length f7 of the seventh lens satisfy: 1.9 < f7 / f < 2.3.

[0013] Further preferably, the effective focal length f of the optical lens and the focal length f8 of the eighth lens satisfy: |f8 / f| > 100; the effective focal length f of the optical lens and the curvature radius R15 of the object side of the eighth lens satisfy: 3 < R15 / f < 4.5.

[0014] Further preferably, the focal length f1 of the first lens and the focal length f8 of the eighth lens satisfy: -0.01 < f1 / f8 < 0.05.

[0015] Further preferably, the focal length f7 of the seventh lens and the focal length f8 of the eighth lens satisfy: -0.04 < f7 / f8 < 0.01.

[0016] Compared with the prior art, the optical lens provided by the present invention adopts eight lenses with specific optical powers. Through specific surface shape matching and reasonable optical power distribution, it can improve the imaging quality of the optical lens, reduce aberration, improve the imaging quality of the optical lens, and make the lens have one or more advantages such as ultra-wide angle, miniaturization, and high pixel. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which: Figure 1 Schematic diagram of the structure of the optical lens in Example 1 of the present invention.

[0018] Figure 2 Graph showing the F-Theta distortion of the optical lens in Example 1 of the present invention.

[0019] Figure 3 It is a field curvature curve diagram of the optical lens in Example 1 of the present invention.

[0020] Figure 4 Graph showing the axial aberration of the optical lens in Example 1 of the present invention.

[0021] Figure 5 Graph showing the vertical axis chromatic aberration of the optical lens in Example 1 of the present invention.

[0022] Figure 6 Schematic diagram of the structure of the optical lens in Example 2 of the present invention.

[0023] Figure 7 Graph showing the F-Theta distortion of the optical lens in Embodiment 2 of the present invention.

[0024] Figure 8 4 is a field curvature curve diagram of the optical lens in Example 2 of the present invention.

[0025] Fig. 9 Graph showing the axial aberration of the optical lens in Embodiment 2 of the present invention.

[0026] Fig.10 Graph showing the vertical axis chromatic aberration of the optical lens in Example 2 of the present invention.

[0027] Fig.11 Schematic diagram of the structure of the optical lens in Example 3 of the present invention.

[0028] Fig.12 Graph showing the F-Theta distortion of the optical lens in Embodiment 3 of the present invention.

[0029] Fig.13 4 is a field curvature curve diagram of the optical lens in Example 3 of the present invention.

[0030] Fig.14 Graph showing the axial aberration of the optical lens in Embodiment 3 of the present invention.

[0031] Fig.15 Graph showing the vertical axis chromatic aberration of the optical lens in Example 3 of the present invention.

[0032] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0033] In order to better understand the present application, a more detailed description will be made of various aspects of the present application with reference to the accompanying drawings. It should be understood that these detailed descriptions are only descriptions of the embodiments of the present application, and are not intended to limit the scope of the present application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0034] It should be noted that in this specification, the expressions of first, second, third, etc. are only used to distinguish one feature from another feature, and do not represent any limitation on the features. Therefore, without departing from the teaching of the present invention, the first lens discussed below may also be referred to as the second lens or the third lens.

[0035] In the drawings, the thickness, size and shape of the lenses have been slightly exaggerated for ease of explanation. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to the shapes of the spherical or aspherical surfaces shown in the drawings. The drawings are only examples and are not drawn strictly to scale.

[0036] In this article, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object is called the object side of the lens, and the surface of each lens closest to the imaging plane is called the image side of the lens.

[0037] It should also be understood that the terms "comprises", "including", "having", "includes" and / or "comprising", when used in this specification, indicate the presence of the stated features, elements and / or components, but do not exclude the presence or addition of one or more other features, elements, components and / or combinations thereof. In addition, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire listed features rather than modifying the individual elements in the list. In addition, when describing embodiments of the present application, "may" is used to mean "one or more embodiments of the present application". And, the term "exemplary" is intended to refer to an example or illustration.

[0038] Unless otherwise defined, all terms (including technical terms and scientific terms) used in this article have the same meaning as commonly understood by ordinary technicians in the field to which this application belongs. It should also be understood that terms (such as terms defined in commonly used dictionaries) should be interpreted as having the same meaning as their meaning in the context of the relevant technology, and will not be interpreted in an idealized or overly formal sense unless explicitly defined in this article.

[0039] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0040] The optical lens provided by the embodiment of the present invention comprises eight lenses in total, and the optical lens comprises, in order from the object side to the imaging surface along the optical axis: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens.

[0041] In some embodiments, the first lens may have a negative optical power, and its object side surface is convex, and its image side surface is concave. The second lens may have a negative optical power, and its object side surface is concave, and its image side surface is concave. The third lens may have a positive optical power, and its object side surface is convex, and its image side surface is concave. The fourth lens may have a positive optical power, and its object side surface is convex, and its image side surface is convex. The fifth lens may have a positive optical power, and its object side surface is convex, and its image side surface is convex. The sixth lens may have a negative optical power, and its object side surface is concave, and its image side surface is concave. The seventh lens may have a positive optical power, and its object side surface is convex, and its image side surface is convex. The eighth lens may have a positive optical power or a negative optical power, and its object side surface is convex, and its image side surface is concave.

[0042] In some embodiments, the optical lens may further include an aperture, and the aperture may be located between the fourth lens and the fifth lens. It is understood that the aperture is used to limit the amount of light entering to change the brightness of the image. When the aperture is located between the fourth lens and the fifth lens, it is convenient to correct the aperture aberration.

[0043] In some embodiments, the optical lens may further include a filter, which is disposed between the eighth lens and the imaging surface. The filter is used to filter out interference light to prevent the interference light from reaching the imaging surface of the optical lens and affecting normal imaging.

[0044] In some embodiments, the combined focal length fa of the first lens, the second lens, the third lens, and the fourth lens and the effective focal length f of the optical lens satisfy: 15 < fa / f < 30. Meeting the above conditions, by reasonably distributing the focal lengths of the front lens group composed of the first lens to the fourth lens, the object plane light with a wide field of view can be converged into the lens, better correcting the F-Theta distortion of the lens without generating large aberrations; at the same time, the front lens group can have an appropriate refractive power, which is beneficial to reducing the total length of the lens.

[0045] In some embodiments, the combined focal length fb of the fifth lens, the sixth lens, the seventh lens, and the eighth lens and the effective focal length f of the optical lens satisfy: 2.5 < fb / f < 3. Meeting the above conditions, by reasonably distributing the focal lengths of the rear lens group composed of the fifth lens to the eighth lens, it is beneficial to balance the distortion and astigmatism generated by the front lens of the optical lens and improve the imaging quality of the optical lens.

[0046] In some embodiments, the effective focal length f of the optical lens and the true image height IH corresponding to the maximum field of view angle of the optical lens satisfy: 3.4 < IH / f < 3.55. Meeting the above conditions is beneficial to realizing the large wide-angle characteristic of the lens, thus meeting the large-range shooting requirements, and can also realize the large image plane characteristic, thereby improving the imaging quality of the optical lens.

[0047] In some embodiments, the true image height IH corresponding to the maximum field of view angle of the optical lens and the effective aperture DM11 on the object side of the first lens satisfy: 1.8 < DM11 / IH < 2.2. Meeting the above conditions, the first lens is mainly used to receive incident light. Although a larger aperture of the first lens has a better light-receiving effect, it also increases the head size of the lens. Meeting the above conditions can ensure that the lens has a large field of view while ensuring that the overall size of the lens is appropriate.

[0048] In some embodiments, the effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -4 < f1 / f < -3. Meeting the above conditions, by reasonably setting the meniscus shape of the first lens, it is beneficial for the first lens to receive light at a larger angle and collect as much light as possible into the rear optical system, increasing the light flux while realizing a large field of view.

[0049] In some embodiments, the effective focal length f of the optical lens and the focal length f2 of the second lens satisfy: -2.5 < f2 / f < -2.15; the curvature radius R3 of the object side of the second lens and the curvature radius R4 of the image side of the second lens satisfy: -18 < R3 / R4 < -13. Meeting the above conditions, the second lens has a negative optical power and can share the negative optical power at the front end of the optical lens, which is beneficial to avoiding excessive light deflection caused by overly concentrated optical power of the first lens and reducing the difficulty of chromatic aberration correction of the optical lens.

[0050] In some embodiments, the effective focal length f of the optical lens and the focal length f3 of the third lens satisfy: 15 < f3 / f < 25. Meeting the above conditions is beneficial to improving the light converging ability, while balancing various aberrations brought by the previous two negative lenses and enhancing the imaging quality of the optical lens.

[0051] In some embodiments, the effective focal length f of the optical lens and the focal length f4 of the fourth lens satisfy: 2.8 < f4 / f < 3.2. Meeting the above conditions can further effectively converge the light, reduce the difficulty of correcting the marginal field distortion, ensure that the lens has a small distortion while achieving a large field of view angle, and improve the overall imaging quality.

[0052] In some embodiments, the effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: 1.5 < f5 / f < 1.7. Meeting the above conditions enables the fifth lens to have a large positive refractive power, which is beneficial to improving the light converging ability of the optical lens, while being able to balance the aberrations of the optical lens and enhance the imaging quality of the optical lens.

[0053] In some embodiments, the effective focal length f of the optical lens and the focal length f6 of the sixth lens satisfy: -1.5 < f6 / f < -1. Meeting the above conditions can diverge the light to a large extent, increase the area of the light entering the imaging surface, which is beneficial to the large target surface imaging of the lens and enhance the overall imaging quality of the lens.

[0054] In some embodiments, the effective focal length f of the optical lens and the focal length f7 of the seventh lens satisfy: 1.9 < f7 / f < 2.3; the curvature radius R13 of the object side surface of the seventh lens and the curvature radius R14 of the image side surface of the seventh lens satisfy: -2.2 < R13 / R14 < -1.8. Meeting the above conditions can enable the seventh lens to have a large positive optical power, effectively transmit more light beams to the imaging surface, while being able to balance the aberrations of the optical lens and enhance the imaging quality of the optical lens.

[0055] In some embodiments, the effective focal length f of the optical lens and the focal length f8 of the eighth lens satisfy: |f8 / f| > 100; the effective focal length f of the optical lens and the curvature radius R15 of the object side surface of the eighth lens satisfy: 3 < R15 / f < 4.5; the curvature radius R15 of the object side surface of the eighth lens and the curvature radius R16 of the image side surface of the eighth lens satisfy: 0.8 < R15 / R16 < 1.3. Meeting the above conditions can enable the eighth lens to have an appropriate refractive power and meniscus shape, facilitate controlling the smooth trend of light, reduce the angle between the chief ray of the marginal field and the optical axis, so as to reduce the spot diameter and improve the aberration, and enhance the overall imaging quality.

[0056] In some embodiments, the focal length f1 of the first lens and the focal length f8 of the eighth lens satisfy: -0.01 < f1 / f8 < 0.05. Meeting the above conditions is conducive to increasing the area of light entering the imaging surface, achieving large target surface imaging of the lens, and improving the imaging quality of the optical lens.

[0057] In some embodiments, the focal length f7 of the seventh lens and the focal length f8 of the eighth lens satisfy: -0.04 < f7 / f8 < 0.01. Meeting the above conditions, by reasonably setting the focal length relationship between the seventh and eighth lenses, the light can be diverged to a certain extent and the aberration can be effectively corrected, which is beneficial to achieving large target surface imaging of the lens.

[0058] In some embodiments, the overall optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 8.5 < TTL / f < 10. Meeting the above conditions can effectively limit the length of the lens and is beneficial to the miniaturization of the optical lens.

[0059] In some embodiments, the overall optical length TTL of the optical lens and the true image height IH corresponding to the maximum field of view angle of the optical lens satisfy: 2.5 < TTL / IH < 2.8. Meeting the above conditions can better achieve the miniaturization of the lens, while ensuring that the lens has a larger image surface and can match a larger-sized imaging chip to achieve high-definition imaging.

[0060] In some embodiments, the refractive index Nd1 of the first lens satisfies: Nd1 > 1.7. Meeting the above conditions, the first lens uses a glass lens with a high refractive index, which is beneficial to the back focus compensation of the system at high and low temperatures, improves the imaging quality of the system at high and low temperatures, and achieves good thermal stability.

[0061] In some embodiments, the curvature radius R1 of the object side of the first lens and the curvature radius R2 of the image side of the first lens satisfy: 3.8 < R1 / R2 < 4.5. Meeting the above conditions, the first lens adopts a convex-concave meniscus shape, which helps to converge the incident light, reduces the aperture of the front lens, is beneficial to the miniaturization of the front part, and at the same time, the first lens uses a glass material, which has an anti-scratch effect.

[0062] In some embodiments, the curvature radius R7 of the object side of the fourth lens and the curvature radius R8 of the image side of the fourth lens satisfy: -4.5 < R7 / R8 < -3.8. Meeting the above conditions is beneficial to better achieve the convergence of light, shorten the distance for light to reach the next lens, and is beneficial to reducing the overall optical length of the optical lens.

[0063] In some embodiments, the radius of curvature R9 of the object side surface of the fifth lens and the radius of curvature R10 of the image side surface of the fifth lens satisfy: -1.7 < R9 / R10 < -1.2. Meeting the above conditions, the fifth lens is a biconvex lens, which is beneficial to converging light while correcting the field curvature and distortion of the optical lens, and improving the imaging quality of the optical lens.

[0064] In some embodiments, the radius of curvature R11 of the object side surface of the sixth lens and the radius of curvature R12 of the image side surface of the sixth lens satisfy: -0.65 < R11 / R12 < -0.5. Meeting the above conditions, the sixth lens is a biconcave lens, which can be paired with the fifth positive lens to better correct the chromatic aberration of the system.

[0065] In some embodiments, the radius of curvature R5 of the object side surface of the third lens, the radius of curvature R6 of the image side surface of the third lens, and the central thickness CT3 of the third lens satisfy: 0.75 < (R5 + CT3) / R6 < 0.95. Meeting the above conditions, the third lens adopts a lens shape close to a concentric circle, which can effectively reduce the optical path difference between the center and the periphery of the lens, and is beneficial to correcting the distortion of the optical lens.

[0066] In some embodiments, the radius of curvature R5 of the object side surface of the third lens and the effective focal length f of the optical lens satisfy: 4 < R5 / f < 5; the radius of curvature R6 of the image side surface of the third lens and the effective focal length f of the optical lens satisfy: 5.5 < R6 / f < 7. Meeting the above conditions, the convergence of light can be better achieved, the distance for light to enter the next lens can be shortened, and it is beneficial to the miniaturization of the optical lens.

[0067] In some embodiments, the focal length f1 of the first lens and the focal length f2 of the second lens satisfy: 1.4 < f1 / f2 < 1.5. Meeting the above conditions, light in a large range can be collected as much as possible, and at the same time, it is beneficial for the rear-end optical system to correct large-angle aberrations, so as to achieve the balance of large wide-angle and high pixel of the optical lens.

[0068] In some embodiments, the focal length f3 of the third lens and the focal length f4 of the fourth lens satisfy: 5.5 < f3 / f4 < 8. Meeting the above conditions, by reasonably setting the focal lengths of the third and fourth lenses, the convergence of light can be better achieved, the distance for light to enter the next lens can be shortened, and it is beneficial to the miniaturization of the optical lens.

[0069] In some embodiments, the fifth lens and the sixth lens form a cemented lens, and the focal length f5 of the fifth lens and the focal length f6 of the sixth lens satisfy: -1.5 < f5 / f6 < -1.1. Meeting the above conditions, the fifth and sixth lenses form a cemented lens with a negative optical power. By reasonably setting the focal length relationship of this cemented lens, it is beneficial to eliminate the chromatic aberration of the system, and at the same time make the light trend transition smoothly, and improve the relative illuminance of the edge field of view.

[0070] In some embodiments, the sum ∑CT of the central thicknesses of the first lens to the eighth lens along the optical axis and the total optical length TTL of the optical lens satisfy: 0.55 < ∑CT / TTL < 0.63. Meeting the above conditions can effectively compress the total length of the optical system, making the structure of the system more compact.

[0071] In some embodiments, the sagittal height SAG81 of the clear aperture semi-diameter on the object side of the eighth lens and the sagittal height SAG82 of the clear aperture semi-diameter on the image side of the eighth lens satisfy: 0.45 < SAG81 / SAG82 < 0.55. Meeting the above conditions, by reasonably setting the surface sagittal height of the eighth lens, the excessive sagittal height at the edge of the eighth lens can be avoided, improving the processability, avoiding strict tolerance limits and process levels, and increasing the production yield of the product.

[0072] In some embodiments, the maximum field of view FOV of the optical lens and the f-number Fno of the optical lens satisfy: FOV / Fno > 80°. Meeting the above conditions can better achieve the balance of the ultra-wide viewing angle and large aperture of the lens.

[0073] In some embodiments, the combined focal length fa of the first lens, the second lens, the third lens, and the fourth lens and the combined focal length fb of the fifth lens, the sixth lens, the seventh lens, and the eighth lens satisfy: 6 < fa / fb < 12. Meeting the above conditions, by reasonably setting the focal length relationship of the front and rear lens groups, it helps the smooth transition of light, expands the field of view of the optical lens, reduces the difficulty of correcting distortion and chromatic aberration of the rear-end lens, and improves the image quality of the optical lens.

[0074] In some embodiments, the combined focal length f56 of the fifth lens and the sixth lens and the effective focal length f of the optical lens satisfy: -28 < f56 / f < -18. Meeting the above conditions, the fifth and sixth lenses form a cemented lens with a negative optical power, which can effectively eliminate the chromatic aberration of the system, reduce the eccentricity sensitivity of the optical lens, balance the aberration of the optical lens, and improve the imaging quality of the optical lens; it can also reduce the assembly sensitivity of the optical lens, thereby reducing the processing technology difficulty of the optical lens and increasing the assembly yield of the optical lens.

[0075] In some embodiments, the optical lens satisfies the conditional formula: 0.9 mm < f < 1.1 mm, 8.5 mm < TTL < 10 mm, FOV > 180°, 25° < CRA < 30°; where f represents the effective focal length of the optical lens, TTL represents the overall optical length of the optical lens, FOV represents the maximum field of view angle of the optical lens, and CRA represents the principal ray incident angle at the maximum image height of the optical lens. Meeting the above conditions indicates that the optical lens provided by the embodiments of the present invention has at least an extremely large field of view angle, can achieve picture shooting within an extremely wide range; has a relatively small overall optical length, and is better able to achieve miniaturization of the lens; has a relatively small CRA, can well match the chip, and ensure good resolution quality.

[0076] In some embodiments, all eight lenses in the optical lens can be made of plastic lenses or adopt a structure with a combination of glass and plastic materials. Preferably, the optical lens of the present invention adopts a lens structure with a combination of eight glass and plastic lenses. Specifically, the first lens can be made of a glass lens, and the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens are all plastic lenses; adopting a glass-plastic hybrid structure can improve the thermal stability performance, effectively reduce costs, correct aberrations, reduce the volume, and provide an optical lens product with higher cost performance.

[0077] In some embodiment manners, 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 can adopt spherical lenses or aspherical lenses. Compared with the spherical structure, the aspherical structure can effectively reduce the aberration of the optical system, thereby reducing the number of lenses and the size of the lenses, and better achieving miniaturization of the lens. More specifically, the first lens in the optical lens provided by the present invention can adopt a spherical lens, and the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens can adopt aspherical lenses.

[0078] In various embodiments of the present invention, when the lens adopts an aspherical lens, the surface shapes of the aspherical surfaces of the optical lens satisfy the following equation: ; where z is the distance between the surface and the vertex of the surface in the optical axis direction, h is the distance from the optical axis to the surface, c is the curvature of the vertex of the surface, K is the conic coefficient, and B, C, D, E, F, G, H are the surface coefficients of the fourth order, sixth order, eighth order, tenth order, twelfth order, fourteenth order, and sixteenth order respectively.

[0079] The present invention is further described below in multiple embodiments. In each embodiment, the thickness, radius of curvature, and material selection of each lens in the optical lens are different. For specific differences, please refer to the parameter table of each embodiment. The following embodiments are only preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the following embodiments. Any other changes, substitutions, combinations or simplifications that do not deviate from the innovative points of the present invention should be regarded as equivalent replacement methods and are included in the protection scope of the present invention.

[0080] Example 1 See also Figure 1 , shown is a schematic diagram of the structure of the optical lens 100 provided in Example 1 of the present invention, and the optical lens 100 includes, along the optical axis from the object side to the imaging surface S18, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, an aperture ST, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8 and a filter G1.

[0081] The first lens L1 has negative refractive power, its object side surface S1 is convex, and its image side surface S2 is concave; The second lens L2 has negative refractive power, its object-side surface S3 is concave, and its image-side surface S4 is concave; The third lens L3 has positive refractive power, its object-side surface S5 is convex, and its image-side surface S6 is concave; The fourth lens L4 has positive refractive power, its object-side surface S7 is convex, and its image-side surface S8 is convex; The fifth lens L5 has positive refractive power, its object-side surface S9 is convex, and its image-side surface is convex; The sixth lens L6 has negative refractive power, its object-side surface is concave, and its image-side surface S11 is concave; The fifth lens L5 and the sixth lens L6 form a cemented lens group with negative power, that is, the cemented surface between the image side surface of the fifth lens L5 and the object side surface of the sixth lens L6 is S10; The seventh lens L7 has positive refractive power, its object-side surface S12 is convex, and its image-side surface S13 is convex; The eighth lens L8 has negative refractive power, its object-side surface S14 is convex, and its image-side surface S15 is concave; The object side surface S16 and the image side surface S17 of the filter G1 are both planes; The imaging surface S18 is a plane.

[0082] The first lens L1 is a glass spherical lens; the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7 and the eighth lens L8 are all plastic aspherical lenses.

[0083] The relevant parameters of each lens in the optical lens 100 in Example 1 are shown in Table 1-1.

[0084] Table 1-1 The surface parameters of the aspheric lens of the optical lens 100 in Example 1 are shown in Table 1-2.

[0085] Table 1-2 In this embodiment, the F-Theta distortion curve, field curvature curve, axial aberration curve, and vertical chromatic aberration curve of the optical lens 100 are respectively as follows: Figure 2 , Figure 3 , Figure 4 and Figure 5 shown.

[0086] Figure 2 The F-Theta distortion curve of this embodiment is shown, which represents the distortion of different field angles on the imaging plane, with the horizontal axis representing the distortion value (unit: %) and the vertical axis representing the field angle (unit: °). It can be seen from the figure that the distortion value is controlled within ±1%, indicating that the optical lens 100 can correct the distortion well.

[0087] Figure 3 The field curvature curve in this embodiment is shown, which represents the field curvature of light on the meridional image plane and the sagittal image plane, the horizontal axis represents the offset (unit: mm), and the vertical axis represents the field angle (unit: °). It can be seen from the figure that the field curvature of the meridional image plane and the sagittal image plane is controlled within ±0.1mm, indicating that the optical lens 100 can well correct the field curvature.

[0088] Figure 4 The axial aberration curve in this embodiment is shown, which represents the aberration of each wavelength on the optical axis at the imaging plane, the horizontal axis represents the axial aberration value (unit: mm), and the vertical axis represents the normalized pupil radius. As can be seen from the figure, the offset of the axial aberration is controlled within ±0.02mm, indicating that the optical lens 100 can better correct the axial aberration.

[0089] Figure 5 The vertical axis chromatic aberration curve in this embodiment is shown, which represents the chromatic aberration of each wavelength relative to the central wavelength (0.55 μm) at different image heights on the imaging surface, the horizontal axis represents the vertical axis chromatic aberration value of each wavelength relative to the central wavelength (unit: μm), and the vertical axis represents the normalized field angle. It can be seen from the figure that the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±4 μm, indicating that the optical lens 100 can better correct the vertical axis chromatic aberration.

[0090] Example 2 See also Figure 6, which is a schematic diagram of the structure of the optical lens 200 provided in Example 2 of the present invention. Compared with Example 1, the main differences of this embodiment are: the eighth lens L8 has positive focal power; and the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0091] The relevant parameters of each lens in the optical lens 200 in Example 2 are shown in Table 2-1.

[0092] Table 2-1 The surface parameters of the aspheric lens of the optical lens 200 in Example 2 are shown in Table 2-2.

[0093] Table 2-2 In this embodiment, the F-Theta distortion curve, field curvature curve, axial aberration curve, and vertical axis chromatic aberration curve of the optical lens 200 are respectively as follows: Figure 7 , Figure 8 , Fig. 9 and Fig.10 shown.

[0094] from Figure 7 It can be seen that the distortion value is controlled within ±1%, indicating that the optical lens 200 can correct the distortion well.

[0095] from Figure 8 It can be seen that the field curvature of the meridian image plane and the sagittal image plane is controlled within ±0.1 mm, indicating that the optical lens 200 can correct the field curvature well.

[0096] from Fig. 9 It can be seen that the offset of the axial aberration is controlled within ±0.01 mm, indicating that the optical lens 200 can correct the axial aberration well.

[0097] from Fig.10 It can be seen that the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±4 μm, indicating that the optical lens 200 can correct the vertical axis chromatic aberration well.

[0098] Example 3 See also Fig.11 , shown is a schematic diagram of the structure of the optical lens 300 provided in Example 3 of the present invention. Compared with Example 1, the main difference between this embodiment and Example 1 is that the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0099] The relevant parameters of each lens in the optical lens 300 in Example 3 are shown in Table 3-1.

[0100] Table 3-1 The surface parameters of the aspheric lens of the optical lens 300 in Example 3 are shown in Table 3-2.

[0101] Table 3-2 In this embodiment, the F-Theta distortion curve, field curvature curve, axial aberration curve, and vertical axis chromatic aberration curve of the optical lens 300 are respectively as follows: Fig.12 , Fig.13 , Fig.14 and Figure 5 shown.

[0102] from Fig.12 It can be seen that the distortion value is controlled within ±1%, indicating that the optical lens 300 can correct the distortion well.

[0103] from Fig.13 It can be seen that the field curvature of the meridian image plane and the sagittal image plane is controlled within ±0.05mm, indicating that the optical lens 300 can correct the field curvature well.

[0104] from Fig.14 It can be seen that the offset of the axial aberration is controlled within ±0.01 mm, indicating that the optical lens 300 can correct the axial aberration well.

[0105] from Fig.15 It can be seen that the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±4μm, indicating that the optical lens 300 can correct the vertical axis chromatic aberration well.

[0106] Please refer to Table 4-1 and Table 4-2, which are the optical characteristics corresponding to the above embodiments, including the effective focal length f of the optical lens, the total optical length TTL, the aperture value Fno, the real image height IH corresponding to the maximum field of view angle, the main ray incident angle CRA at the maximum image height, the maximum field of view angle FOV and the numerical value corresponding to each conditional expression in each embodiment.

[0107] Table 4-1 Table 4-2 Compared with the prior art, the optical lens provided by the present invention has at least the following advantages: (1) The optical lens provided by the present invention adopts an eight-piece glass-plastic hybrid structure. Through a specific surface shape setting and a reasonable optical focal length distribution, the structure of the optical lens is relatively compact, and a large field of view of the lens can be achieved, thereby being able to obtain more scene information and meet the needs of large-scale detection of the optical lens.

[0108] (2) The optical lens provided by the present invention has a smaller CRA, which can be well matched with the chip to ensure good resolution quality; at the same time, it can also reasonably correct the overall aberration of the optical lens, so that the optical lens has high pixels while effectively shortening the overall length of the optical lens.

[0109] (3) The optical lens provided by the present invention adopts a glass-plastic hybrid structure, which not only makes the lens have good thermal stability, but also greatly reduces the production cost of the lens, reduces the size of the lens, and better realizes the miniaturization of the lens.

[0110] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0111] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An optical lens, comprising eight lenses, characterized in that: It sequentially includes, from the object side to the imaging surface along the optical axis: A first lens with a negative focal power, whose object side is convex and whose image side is concave; A second lens with a negative focal power, whose object side is concave and whose image side is concave; A third lens with a positive focal power, whose object side is convex and whose image side is concave; A fourth lens with a positive focal power, whose object side is convex and whose image side is convex; A fifth lens with a positive focal power, whose object side is convex and whose image side is convex; A sixth lens with a negative focal power, whose object side is concave and whose image side is concave; A seventh lens with a positive focal power, whose object side is convex and whose image side is convex; An eighth lens with a focal power, whose object side is convex and whose image side is concave; Wherein, the combined focal length fa of the first lens, the second lens, the third lens and the fourth lens and the effective focal length f of the optical lens satisfy: 15 < fa / f < 30; the combined focal length fb of the fifth lens, the sixth lens, the seventh lens and the eighth lens and the effective focal length f of the optical lens satisfy: 2.5 < fb / f < 3.

2. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens and the true image height IH corresponding to the maximum field of view angle of the optical lens satisfy: 3.4 < IH / f < 3.55; the true image height IH corresponding to the maximum field of view angle of the optical lens and the effective aperture DM11 of the object side of the first lens satisfy: 1.8 < DM11 / IH < 2.

2.

3. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -4 < f1 / f < -3.

4. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens and the focal length f2 of the second lens satisfy: -2.5 < f2 / f < -2.

15.

5. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens and the focal length f3 of the third lens satisfy: 15 < f3 / f < 25.

6. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens and the focal length f4 of the fourth lens satisfy: 2.8 < f4 / f < 3.

2.

7. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: 1.5 < f5 / f < 1.7; the effective focal length f of the optical lens and the focal length f6 of the sixth lens satisfy: -1.5 < f6 / f < -1.

8. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens and the focal length f7 of the seventh lens satisfy: 1.9 < f7 / f < 2.

3.

9. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens and the focal length f8 of the eighth lens satisfy: |f8 / f| > 100; the effective focal length f of the optical lens and the curvature radius R15 of the object side of the eighth lens satisfy: 3 < R15 / f < 4.

5.

10. The optical lens according to claim 1, characterized in that: The focal length f1 of the first lens and the focal length f8 of the eighth lens satisfy: -0.01 < f1 / f8 < 0.

05.

11. The optical lens according to claim 1, characterized in that: The focal length f7 of the seventh lens and the focal length f8 of the eighth lens satisfy: -0.04 < f7 / f8 < 0.01.

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