Optical lens

Abstract

The invention provides an optical lens, which comprises eight lenses in total, and sequentially comprises a first lens with negative focal power, a second lens with negative focal power, a third lens with positive focal power, a fourth lens with negative focal power, a fifth lens with negative focal power and a sixth lens with negative focal power from an object side to an image side along an optical axis, the object side surface and the image side surface of the second lens are convex surfaces; the object side surface of the third lens is a concave surface, and the image side surface of the third lens is a concave surface near the optical axis; the image side surface of the fourth lens is a convex surface; the fifth lens has positive focal power, and the object side surface and the image side surface of the fifth lens are convex surfaces; the sixth lens has negative focal power, and the object side surface and the image side surface of the sixth lens are concave surfaces; the object side surface and the image side surface of the seventh lens are convex surfaces; the object side surface of the eighth lens is a concave surface, and the image side surface of the eighth lens is a convex surface. According to the optical lens provided by the invention, the imaging quality of the optical lens can be improved, the aberration is reduced, and the imaging quality of the optical lens is improved.

Description

Technical Field

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

[0002] In the field of intelligent manufacturing, industrial lenses are widely used. They have many advantages such as high precision, high speed, and high efficiency. They can record key parameters and data in the production process at any time, thereby improving production efficiency and product quality. It can be foreseen that the market for industrial lenses will grow explosively in the future, and their application in intelligent manufacturing will become more extensive. With the continuous upgrading of industrial lenses, the requirements of intelligent manufacturing for industrial lenses will become higher and higher, and good imaging effects will become the main development trend of industrial lenses.

[0003] However, existing industrial lenses still have many shortcomings. For example, most lenses can well image the subject when shooting close-ups, but have poor imaging for distant targets and cannot provide clear imaging at long distances. The increased field of view of the lens makes it difficult to correct system aberrations and reduces imaging quality. It is difficult to meet market demand. Summary of the invention

[0004] In view of the above problems, an object of the present invention is to provide an optical lens having the advantage of excellent imaging quality.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] An optical lens, comprising eight lenses, which include:

[0007] The first lens has negative optical power, and both the object side surface and the image side surface are concave;

[0008] The second lens has positive refractive power, and its object side surface and image side surface are both convex;

[0009] The third lens has a negative optical power, the object side surface of which is concave, and the image side surface of which is concave near the optical axis;

[0010] a fourth lens element having positive refractive power and a convex image-side surface;

[0011] A fifth lens having positive refractive power, whose object-side surface and image-side surface are both convex;

[0012] The sixth lens has negative optical power, and both the object side surface and the image side surface are concave;

[0013] The seventh lens has positive refractive power, and both the object side surface and the image side surface are convex;

[0014] an eighth lens having positive refractive power, whose object side surface is concave and whose image side surface is convex;

[0015] Among them, the radius of curvature R1 of the object side surface of the first lens and the radius of curvature R2 of the image side surface of the first lens satisfy: 0.2 < (R1 + R2) / (R1 - R2) < 0.8.

[0016] Further preferably, the total optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 2 < TTL / f < 2.4.

[0017] Further preferably, the total 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 < TTL / IH < 2.4.

[0018] Further preferably, the effective focal length f of the optical lens and the focal length f8 of the eighth lens satisfy: 4.7 < f8 / f < 12.2.

[0019] Further preferably, the effective focal length f of the optical lens and the combined focal length f567 of the fifth lens, the sixth lens and the seventh lens satisfy: 1.2 < f567 / f < 1.9.

[0020] Further preferably, the effective focal length f of the optical lens and the radius of curvature R1 of the object side surface of the first lens satisfy: -2.65 < R1 / f < -0.7; the effective focal length f of the optical lens and the radius of curvature R2 of the image side surface of the first lens satisfy: 0.35 < R2 / f < 0.65.

[0021] Further preferably, the effective focal length f of the optical lens and the radius of curvature R15 of the object side surface of the eighth lens satisfy: -0.45 < R15 / f < -0.3.

[0022] Further preferably, the radius of curvature R15 of the object side surface of the eighth lens and the radius of curvature R16 of the image side surface of the eighth lens satisfy: 0.7 < R15 / R16 < 1.

[0023] Further preferably, the radius of curvature R15 of the object side surface of the eighth lens and the radius of curvature R16 of the image side surface of the eighth lens satisfy: -0.2 < (R15 - R16) / (R15 + R16) < 0.

[0024] Further preferably, the sagittal height Sag1 of the object side surface clear aperture of the first lens and the object side surface clear aperture d1 of the first lens satisfy: -0.2 < Sag1 / d1 < 0; the sagittal height Sag2 of the image side surface clear aperture of the first lens and the image side surface clear aperture d2 of the first lens satisfy: 0.1 < Sag2 / d2 < 0.35.

[0025] 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, the imaging quality of the optical lens can be improved, the aberration can be reduced, and the imaging quality of the optical lens can be improved, so that the lens has one or more advantages such as long focus, large image surface, high imaging quality, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] 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:

[0027] Figure 1 Schematic diagram of the structure of the optical lens in Example 1 of the present invention.

[0028] Figure 2 It is a field curvature curve diagram of the optical lens in Example 1 of the present invention.

[0029] Figure 3 : is the F-Tan (Theta) distortion curve of the optical lens in Example 1 of the present invention.

[0030] Figure 4 Graph showing the axial aberration of the optical lens in Example 1 of the present invention.

[0031] Figure 5 Graph showing the vertical axis chromatic aberration of the optical lens in Example 1 of the present invention.

[0032] Figure 6 This is the MTF curve diagram of the optical lens in Example 1 of the present invention.

[0033] Figure 7 This is a relative illumination curve diagram of the optical lens in Example 1 of the present invention.

[0034] Figure 8 Schematic diagram of the structure of the optical lens in Example 2 of the present invention.

[0035] Fig. 9 It is a field curvature curve diagram of the optical lens in Example 2 of the present invention.

[0036] Fig.10 : is the F-Tan (Theta) distortion curve of the optical lens in Example 2 of the present invention.

[0037] Fig.11 Graph showing the axial aberration of the optical lens in Embodiment 2 of the present invention.

[0038] Fig.12 Graph showing the vertical axis chromatic aberration of the optical lens in Example 2 of the present invention.

[0039] Fig.13 This is an MTF curve diagram of the optical lens in Example 2 of the present invention.

[0040] Fig.14 This is a relative illumination curve diagram of the optical lens in Example 2 of the present invention.

[0041] Fig.15 Schematic diagram of the structure of the optical lens in Example 3 of the present invention.

[0042] Fig.16 4 is a field curvature curve diagram of the optical lens in Example 3 of the present invention.

[0043] Fig.17 : is the F-Tan (Theta) distortion curve of the optical lens in Example 3 of the present invention.

[0044] Fig.18 Graph showing the axial aberration of the optical lens in Embodiment 3 of the present invention.

[0045] Fig.19 Graph showing the vertical axis chromatic aberration of the optical lens in Example 3 of the present invention.

[0046] Fig. 20 This is the MTF curve diagram of the optical lens in Example 3 of the present invention.

[0047] Fig.21 This is a relative illumination curve diagram of the optical lens in Example 3 of the present invention.

[0048] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] The optical lens of the embodiment of the present invention has a total of eight lenses, which are: 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 in order from the object side to the imaging surface along the optical axis.

[0057] In some embodiments, the first lens may have a negative optical power, and its object side and image side are both concave. The second lens may have a positive optical power, and its object side and image side are both convex. The third lens may have a negative optical power, its object side is concave, and its image side is concave at the near optical axis. The fourth lens may have a positive optical power, its object side may be concave or convex, and its image side is convex. The fifth lens may have a positive optical power, and its object side and image side are both convex. The sixth lens may have a negative optical power, and its object side and image side are both concave. The seventh lens may have a positive optical power, and its object side and image side are both convex. The eighth lens may have a positive optical power, its object side is concave, and its image side is convex.

[0058] In some embodiments, the optical lens may further include a diaphragm, which may be located between the object side and the first lens. It can be understood that the diaphragm is used to limit the amount of incident light to change the brightness of the image formation.

[0059] In some embodiments, the optical lens may further include a filter, which may be disposed between the eighth lens and the imaging surface. The filter is used to filter out interfering light to prevent the interfering light from reaching the imaging surface of the optical lens and affecting the normal imaging.

[0060] In some embodiments, the first lens and the second lens may be glued together to form a cemented lens, which can effectively correct the chromatic aberration of the optical lens, 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 difficulty of the optical lens and improving the assembly yield of the optical lens.

[0061] In some embodiments, the fifth lens, the sixth lens and the seventh lens may be glued together to form a cemented lens, which can effectively correct the chromatic aberration of the optical lens, 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 difficulty of the optical lens and improving the assembly yield of the optical lens.

[0062] In some embodiments, the radius of curvature R1 of the object side surface of the first lens and the radius of curvature R2 of the image side surface of the first lens satisfy: 0.2 < (R1 + R2) / (R1 - R2) < 0.8. Meeting the above range is beneficial to alleviating the degree of deflection of light passing through the first lens, achieving the purpose of effectively reducing the working aperture of the first lens, and at the same time being able to reduce the difficulty of correcting aberration for subsequent lenses. More specifically, 0.28 < (R1 + R2) / (R1 - R2) < 0.67.

[0063] In some embodiments, the total optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 2 < TTL / f < 2.4. Meeting the above range is beneficial to restricting the total length of the lens while better realizing the telephoto performance of the system. More specifically, 2.29 < TTL / f < 2.4.

[0064] In some embodiments, the total 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 < TTL / IH < 2.4. Meeting the above range is beneficial to achieving the balance between the volume of the optical lens and the large image plane. More specifically, 2.21 < TTL / IH < 2.34.

[0065] In some embodiments, the effective focal length f of the optical lens and the focal length f8 of the eighth lens satisfy: 4.7 < f8 / f < 12.2. Meeting the above range can make the eighth lens have a positive optical power, control the light path smoothly, transfer more light to the imaging surface, and improve the imaging quality of the optical lens. More specifically, 5.18 < f8 / f < 11.08.

[0066] In some embodiments, the effective focal length f of the optical lens and the combined focal length f567 of the fifth, sixth, and seventh lenses satisfy: 1.2 < f567 / f < 1.9. Meeting the above range, the fifth, sixth, and seventh lenses form a cemented lens group with a positive optical power. By reasonably setting the focal length of the cemented lens group, the chromatic aberration of the optical lens can be effectively corrected, the eccentricity sensitivity of the optical lens can be reduced, and the aberration of the optical lens can be balanced, improving the imaging quality of the optical lens. More specifically, 1.32 < f567 / f < 1.76.

[0067] In some embodiments, the effective focal length f of the optical lens and the curvature radius R1 of the object side surface of the first lens satisfy: -2.65 < R1 / f < -0.7; the effective focal length f of the optical lens and the curvature radius R2 of the image side surface of the first lens satisfy: 0.35 < R2 / f < 0.65. Meeting the above range, by reasonably setting the surface shape of the first lens, the light entering the system can be effectively increased, and the imaging quality in bright and dark environments can be improved. More specifically, -2.41 < R1 / f < -0.78; 0.43 < R2 / f < 0.57.

[0068] In some embodiments, the effective focal length f of the optical lens and the curvature radius R15 of the object side surface of the eighth lens satisfy: -0.45 < R15 / f < -0.3. Meeting the above range, controlling the surface shape of the object side surface of the eighth lens is beneficial to increasing the imaging area and the field of view angle. More specifically, -0.4 < R15 / f < -0.36.

[0069] In some embodiments, 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: 0.7 < R15 / R16 < 1. Meeting the above range, controlling the surface shape of the eighth lens can effectively correct the aberration and improve the imaging quality of the optical lens. More specifically, 0.77 < R15 / R16 < 0.86.

[0070] In some embodiments, the radius of curvature R15 of the object side surface of the eighth lens and the radius of curvature R16 of the image side surface of the eighth lens satisfy: -0.2 < (R15 - R16) / (R15 + R16) < 0. Meeting the above range controls the reasonable shapes of the object side surface and the image side surface of the eighth lens and improves the imaging quality. More specifically, -0.13 < (R15 - R16) / (R15 + R16) < -0.07.

[0071] In some embodiments, the sagittal height Sag1 of the clear aperture of the object side surface of the first lens and the clear aperture diameter d1 of the object side surface of the first lens satisfy: -0.2 < Sag1 / d1 < 0; the sagittal height Sag2 of the clear aperture of the image side surface of the first lens and the clear aperture diameter d2 of the image side surface of the first lens satisfy: 0.1 < Sag2 / d2 < 0.35. Meeting the above range helps to control the trend of light rays in the marginal field of view and highlights the detailed information of the central field of view of the optical lens. More specifically, -0.12 < Sag1 / d1 < -0.03; 0.18 < Sag2 / d2 < 0.27.

[0072] In some embodiments, the effective focal length f of the optical lens, the maximum field of view angle FOV, and the true image height IH corresponding to the maximum field of view angle satisfy: 0.85 < (IH / 2) / (f × tan(FOV / 2)) < 0.95. Meeting the above range can control the size of distortion and improve the imaging quality of the optical lens. More specifically, 0.87 < (IH / 2) / (f × tan(FOV / 2)) < 0.91.

[0073] 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 satisfy: 1 < IH / f < 1.1. Meeting the above range can not only achieve the long focal length characteristic of the lens to meet the local shooting requirements, but also achieve the large image plane characteristic of the lens to realize high-definition imaging of the lens. More specifically, 1 < IH / f < 1.05.

[0074] In some embodiments, the effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -1.4 < f1 / f < -0.5. Meeting the above range can make the first lens have a negative optical power, which is beneficial to reducing the inclination angle of the incident light rays and is beneficial to collecting as much marginal field of view light rays as possible into the rear optical lenses to achieve large-angle light collection. More specifically, -1.28 < f1 / f < -0.6.

[0075] In some embodiments, the focal length f2 of the second lens and the effective focal length f of the optical lens satisfy: 0.4 < f2 / f < 0.7. Meeting the above range, defining that the second lens has an appropriate positive optical power, is conducive to the convergence of light, enables the divergent light entering the system from the front to smoothly enter the rear optical system, makes the light trend smoother, optimizes aberrations, and improves resolution. More specifically, 0.44 < f2 / f < 0.67.

[0076] In some embodiments, the effective focal length f of the optical lens and the focal length f3 of the third lens satisfy: -0.9 < f3 / f < -0.5. Meeting the above range is conducive to slowing down the deflection degree of the incident light, avoiding excessive aberration caused by overly strong refraction changes, and at the same time is conducive to balancing various aberrations generated by the front lens group, improving the overall imaging quality. More specifically, -0.75 < f3 / f < -0.53.

[0077] In some embodiments, the effective focal length f of the optical lens and the focal length f4 of the fourth lens satisfy: 0.6 < f4 / f < 1.1. Meeting the above range can effectively converge light, correct the aberrations generated by the front lens, and improve the overall imaging quality. More specifically, 0.7 < f4 / f < 1.01.

[0078] In some embodiments, the effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: 0.6 < f5 / f < 1.4. Meeting the above range can make the fifth lens have a positive optical power, which is conducive to improving the light-gathering ability of the optical lens, and at the same time can balance the aberrations of the optical lens, improving the imaging quality of the optical lens. More specifically, 0.69 < f5 / f < 1.28.

[0079] In some embodiments, the effective focal length f of the optical lens and the focal length f6 of the sixth lens satisfy: -1.3 < f6 / f < -0.5. Meeting the above range can make the sixth lens have a negative optical power, which is conducive to increasing the imaging area and field of view angle of the optical lens, and improving the imaging quality of the optical lens. More specifically, -1.14 < f6 / f < -0.54.

[0080] In some embodiments, the effective focal length f of the optical lens and the focal length f7 of the seventh lens satisfy: 1 < f7 / f < 1.4. Meeting the above range can make the seventh lens have a positive optical power, improve the light-gathering ability of the optical lens, balance the aberrations of the optical lens, and improve the imaging quality of the optical lens. More specifically, 1.14 < f7 / f < 1.2.

[0081] In some embodiments, the combined focal length f12 of the first lens and the second lens and the effective focal length f of the optical lens satisfy: 1.1 < f12 / f < 1.6. Meeting the above range, the first lens and the second lens form a cemented lens group with positive optical power. By reasonably setting the focal length of the cemented lens group, the chromatic aberration of the optical lens can be effectively corrected, the eccentricity sensitivity of the optical lens can be reduced, and the aberration of the optical lens can also be balanced, improving the imaging quality of the optical lens. More specifically, 1.24 < f12 / f < 1.48.

[0082] In some embodiments, the effective focal length f of the optical lens and the curvature radius R3 of the object side surface of the second lens satisfy: 0.35 < R3 / f < 0.65. Meeting the above range, by reasonably setting the shape of the object side surface of the second lens, it is beneficial to converge light, balance the aberration brought by the first lens, reduce the difficulty of distortion correction, make the image in the edge field of view of the lens undistorted, and improve the imaging quality of the optical system. More specifically, 0.43 < R3 / f < 0.57.

[0083] In some embodiments, the effective focal length f of the optical lens and the curvature radius R9 of the object side surface of the fifth lens satisfy: 1.2 < R9 / f < 2. Meeting the above range, defining the shape of the object side surface of the fifth lens helps to reasonably control the light path, reduce aberration, and improve the imaging quality of the optical lens. More specifically, 1.37 < R9 / f < 1.8.

[0084] In some embodiments, the effective focal length f of the optical lens and the curvature radius R13 of the object side surface of the seventh lens satisfy: 1.1 < R13 / f < 1.5. Meeting the above range, defining the shape of the object side surface of the seventh lens helps to reasonably control the light path, reduce aberration, and improve the imaging quality of the optical lens. More specifically, 1.25 < R13 / f < 1.36.

[0085] In some embodiments, the effective focal length f of the optical lens and the curvature radius R16 of the image side surface of the eighth lens satisfy: -0.55 < R16 / f < -0.4. Meeting the above range, it is beneficial to converge light, transmit more light to the imaging surface, and improve the imaging quality of the optical lens. More specifically, -0.49 < R16 / f < -0.43.

[0086] In some embodiments, the curvature radius R3 of the object side surface of the second lens and the curvature radius R4 of the image side surface of the second lens satisfy: -0.75 < (R3 + R4) / (R3 - R4) < -0.3. Meeting the above range, it is beneficial to keep the light path stable and reduce the aberration correction pressure of the rear-end lens of the optical lens. More specifically, -0.68 < (R3 + R4) / (R3 - R4) < -0.39.

[0087] 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: 0.25 < (R9 + R10) / (R9 - R10) < 0.6. Meeting the above range can reduce spherical aberration and at the same time increase the relative illumination of the marginal field of view. More specifically, 0.31 < (R9 + R10) / (R9 - R10) < 0.46.

[0088] In some embodiments, the radius of curvature R13 of the object side surface of the seventh lens and the radius of curvature R14 of the image side surface of the seventh lens satisfy: -0.85 < (R13 - R14) / (R13 + R14) < -0.1. Meeting the above range can reasonably define the shapes of the object side surface and the image side surface of the seventh lens, enable the seventh lens to have an appropriate surface shape, effectively improve field curvature and aberration, and enhance the imaging quality. More specifically, -0.68 < (R13 - R14) / (R13 + R14) < -0.15.

[0089] In some embodiments, the total optical length TTL of the optical lens and the sum ∑CT of the central thicknesses of the first lens to the eighth lens along the optical axis satisfy: 0.6 < ∑CT / TTL < 0.85. Meeting the above range can effectively compress the total length of the optical lens and is conducive to the structural design and production process of the optical lens. More specifically, 0.69 < ∑CT / TTL < 0.75.

[0090] In some embodiments, the clear aperture radius d1 of the object side surface of the first lens and the clear aperture radius d16 of the image side surface of the eighth lens satisfy: 0.25 < d1 / d16 < 0.35. Meeting the above range can, by controlling the aperture ratio of the front and rear lenses, limit the light ray trend within a reasonable range and make the illumination on the imaging surface uniform. More specifically, 0.29 < d1 / d16 < 0.32.

[0091] In some embodiments, the clear aperture radius d1 of the object side surface of the first lens, the true image height IH corresponding to the maximum field of view angle of the optical lens, and the maximum field of view angle FOV of the optical lens satisfy: 0.5 < d1 / (IH / 2) / tan(FOV / 2) < 0.65. Meeting the above range can balance the relationship among the front aperture diameter, the field of view angle, and the image surface size of the optical lens, which is conducive to miniaturization. More specifically, 0.55 < d1 / (IH / 2) / tan(FOV / 2) < 0.58.

[0092] In some embodiments, the optical lens satisfies the conditional formula: 12.2 mm < f < 15.2 mm, 55° < FOV < 65°, 3.6 mm < EPD < 4.4 mm, 30 mm < TTL < 34 mm, 3 < Fno < 3.7, 12.6 mm < IH < 15.5 mm, 1.7° < CRA < 3.6°, 4 mm < BFL < 4.5 mm, where f represents the effective focal length of the optical lens, FOV represents the maximum field of view angle of the optical lens, EPD represents the entrance pupil diameter of the optical lens, TTL represents the overall optical length of the optical lens, Fno represents the aperture value of the optical lens, IH represents the image height corresponding to the maximum field of view angle of the optical lens, CRA represents the chief ray angle of incidence at the maximum image height of the optical lens, and BFL represents the back focal length of the optical lens. Meeting the above conditions indicates that the optical lens provided by the embodiments of the present invention has at least the characteristics of long focal length, large image plane, small CRA, etc. More specifically, 13.4 mm < f < 13.9 mm, 59.9° < FOV < 60.1°, 3.9 mm < EPD < 4.1 mm, 31.1 mm < TTL < 32.9 mm, 3.3 < Fno < 3.4, 14 mm < IH < 14.1 mm, 1.8° < CRA < 3.4°, 4.1 mm < BFL < 4.3 mm.

[0093] In some embodiments, the lens material in the optical lens provided by the present invention can be glass or plastic. When the lens material is plastic, the production cost can be effectively reduced. Additionally, when the lens material is glass, due to the low dispersion characteristic of glass itself, the geometric chromatic aberration of the optical system can be effectively corrected. The optical lens provided by the present invention can adopt an all-glass lens structure, which can reduce dispersion, effectively correct the chromatic aberration of the optical lens, and improve the imaging quality.

[0094] In some embodiments, 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 realizing the miniaturization of the lens. More specifically, the first lens, the second lens, the fifth lens, the sixth lens, and the seventh lens of the present invention adopt spherical lenses, and the third lens, the fourth lens, and the eighth lens adopt aspherical lenses.

[0095] In various embodiments of the present invention, when the lens adopts an aspherical lens, the shapes of the aspherical surfaces of the optical lens satisfy the following equations:

[0096]

[0097] Among them, z is the distance between the surface and the vertex of the surface in the direction of the optical axis, h is the distance from the optical axis to the surface, c is the curvature of the surface vertex, K is the quadratic surface coefficient, B, C, D, E, F, G, and H are the fourth-order, sixth-order, eighth-order, tenth-order, twelfth-order, fourteenth-order, and sixteenth-order surface coefficients respectively.

[0098] 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.

[0099] Example 1

[0100] See also Figure 1 , which is a schematic diagram of the structure of the optical lens 100 provided in Embodiment 1 of the present invention, wherein the optical lens includes, in sequence from the object side to the imaging surface along the optical axis: an aperture ST, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, and a filter G1.

[0101] The first lens L1 has negative refractive power, and its object side surface S1 and image side surface S2 are both concave;

[0102] The second lens L2 has positive refractive power, and its object-side surface S2 and image-side surface S3 are both convex;

[0103] The first lens L1 and the second lens L2 form a cemented lens group with positive refractive power, that is, the cemented surface of the image side surface of the first lens L1 and the object side surface of the second lens L2 is S2;

[0104] The third lens L3 has negative refractive power, its object side surface S4 is concave, and its image side surface S5 is concave near the optical axis;

[0105] The fourth lens L4 has positive refractive power, and its object-side surface S6 and image-side surface S7 are both convex surfaces;

[0106] The fifth lens L5 has positive refractive power, and its object-side surface S8 and image-side surface S9 are both convex surfaces;

[0107] The sixth lens L6 has negative refractive power, and its object-side surface S9 and image-side surface S10 are both concave surfaces;

[0108] The seventh lens L7 has positive refractive power, and its object-side surface S10 and image-side surface S11 are both convex surfaces;

[0109] The fifth lens L5, the sixth lens L6 and the seventh lens L7 form a cemented lens group with positive refractive power, wherein the cemented surface between the image side surface of the fifth lens L5 and the object side surface of the sixth lens L6 is S9; the cemented surface between the image side surface of the sixth lens L6 and the object side surface of the seventh lens L7 is S10;

[0110] The eighth lens L8 has positive refractive power, its object-side surface S12 is concave, and its image-side surface S13 is convex;

[0111] The object side surface S14 and the image side surface S15 of the filter G1 are both planes;

[0112] The imaging surface S16 is a plane.

[0113] The first lens, the second lens, the fifth lens, the sixth lens and the seventh lens are glass spherical lenses, and the third lens, the fourth lens and the eighth lens are glass aspherical lenses.

[0114] The relevant parameters of each lens in the optical lens 100 in Example 1 are shown in Table 1-1.

[0115] Table 1-1

[0116]

[0117]

[0118] The surface parameters of the aspheric lens of the optical lens 100 in Example 1 are shown in Table 1-2.

[0119] Table 1-2

[0120] Face number K B C D E F G H S4 1.33E+00 -5.69E-05 8.20E-05 -7.97E-06 1.74E-06 -1.47E-07 7.22E-09 -8.89E-11 S5 -7.12E+01 -1.36E-03 6.75E-05 -1.66E-06 3.31E-09 4.52E-10 4.56E-11 -2.49E-12 S6 3.61E+01 -1.39E-03 6.24E-05 -6.59E-07 1.24E-09 -8.69E-11 -9.88E-12 2.72E-13 S7 -5.44E-01 2.09E-04 -3.72E-06 5.87E-07 -1.84E-08 4.89E-10 1.09E-11 -1.63E-13 S12 -5.37E+00 9.00E-04 -2.55E-05 5.33E-07 -5.91E-09 2.31E-11 1.75E-13 -1.51E-15 S13 -4.84E+00 1.07E-03 -3.33E-05 6.05E-07 -4.64E-09 -7.16E-12 3.57E-13 -1.04E-15

[0121] In this embodiment, the field curvature curve, F-Tan (Theta) distortion curve, axial aberration curve, vertical chromatic aberration curve, MTF curve, and relative illumination curve of the optical lens 100 are shown in FIG. Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 shown.

[0122] Figure 2 The field curvature curve of Example 1 is shown, which indicates the degree of curvature of light of different wavelengths on the meridional image plane and the sagittal image plane, with the horizontal axis indicating the offset (unit: mm) and the vertical axis indicating the half 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 ±0.06mm, indicating that the optical lens can correct the field curvature well.

[0123] Figure 3The F-Tan (Theta) distortion curve of Example 1 is shown, which represents the distortion of light of different wavelengths at different image heights on the imaging surface, with the horizontal axis representing the distortion value (unit: %) and the vertical axis representing the half field angle (unit: °). It can be seen from the figure that the distortion of the optical lens is controlled within ±10%, indicating that the optical lens can correct the distortion well.

[0124] Figure 4 The axial aberration curve of the optical lens 100 in this embodiment is shown, which represents the aberration of each wavelength on the optical axis at the imaging surface, the horizontal axis represents the axial aberration value (unit: mm), and the vertical axis represents the normalized pupil radius. It can be seen from the figure that the offset of the axial aberration is controlled within ±0.03mm, indicating that the optical lens 100 can correct the axial aberration well.

[0125] Figure 5 The vertical axis chromatic aberration curve of the optical lens 100 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 ±3.5 μm, indicating that the optical lens 100 can correct chromatic aberration well.

[0126] Figure 6 The MTF (Modulation Transfer Function) curve of Example 1 is shown, which represents the imaging modulation degree of the lens at different spatial frequencies under each field of view, the horizontal axis represents the spatial frequency (unit: lp / mm), and the vertical axis represents the MTF value. It can be seen from the figure that the MTF value of this embodiment is above 0.3 in the whole field of view, and in the range of 0 to 200 lp / mm, the MTF curve decreases evenly and smoothly from the center to the edge of the field of view, and has good imaging quality and good detail resolution ability in both low-frequency and high-frequency conditions.

[0127] Figure 7 The relative illumination curve of Example 1 is shown, which represents the relative illumination values ​​at different viewing angles on the imaging surface, the horizontal axis represents the half viewing angle (unit: °), and the vertical axis represents the relative illumination (unit: %). It can be seen from the figure that the relative illumination value of the optical lens is still greater than 80% at the maximum half viewing angle, indicating that the optical lens has good relative illumination.

[0128] Example 2

[0129] See also Figure 8, shown is a schematic diagram of the structure of the optical lens 200 provided in Example 2 of the present invention. The optical lens of this embodiment is substantially the same as that of Example 1, except that the object side surface S6 of the fourth lens L4 is a concave surface; and the optical parameters such as the curvature radius, aspheric coefficient, and thickness of each lens surface are different.

[0130] The relevant parameters of each lens in the optical lens 200 in Example 2 are shown in Table 2-1.

[0131] Table 2-1

[0132]

[0133]

[0134] The surface parameters of the aspheric lens of the optical lens 200 in Example 2 are shown in Table 2-2.

[0135] Table 2-2

[0136] Face number K B C D E F G H S4 5.18E+00 -4.72E-03 1.65E-04 -1.69E-05 1.73E-06 -1.37E-07 7.13E-09 -9.86E-11 S5 -2.00E+02 -2.59E-03 8.00E-05 -1.26E-06 1.71E-09 5.43E-11 4.01E-11 -1.15E-12 S6 -3.09E+01 -8.55E-04 5.42E-05 -8.64E-07 2.86E-09 2.69E-10 -1.09E-11 1.19E-13 S7 -5.95E-01 4.23E-04 -1.50E-05 9.68E-07 -2.14E-08 2.74E-10 5.41E-12 -1.09E-13 S12 -6.33E+01 1.02E-03 -3.26E-05 5.63E-07 -5.46E-09 2.28E-11 1.28E-13 -1.32E-15 S13 -2.00E+02 1.86E-03 -6.39E-05 9.85E-07 -5.31E-09 -3.27E-11 3.51E-13 2.27E-15

[0137] In this embodiment, the field curvature curve, F-Tan (Theta) distortion curve, axial aberration curve, vertical chromatic aberration curve, MTF curve, and relative illumination curve of the optical lens 200 are shown in FIG. Fig. 9 , Fig.10 , Fig.11 , Fig.12 , Fig.13 , Fig.14 shown.

[0138] from Fig. 9 It can be seen that the field curvature of the meridian image plane and the sagittal image plane is controlled within ±0.06mm, indicating that the optical lens can correct the field curvature well.

[0139] from Fig.10 It can be seen that the distortion of the optical lens is controlled within ±10%, indicating that the optical lens can correct the distortion well.

[0140] from Fig.11 It can be seen that the offset of axial aberration is controlled within ±0.03mm, which means that the optical lens can correct axial aberration well.

[0141] from Fig.12 It can be seen that the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±5μm, indicating that the optical lens can correct chromatic aberration well.

[0142] from Fig.13It can be seen that the MTF value of this embodiment is above 0.3 in the whole field of view. In the range of 0 to 200 lp / mm, the MTF curve decreases evenly and smoothly from the center to the edge of the field of view, and has good imaging quality and good detail resolution capability in both low-frequency and high-frequency conditions.

[0143] from Fig.14 It can be seen that at the maximum half field of view angle, the relative illumination value of the optical lens is still greater than 80%, indicating that the optical lens has good relative illumination.

[0144] Example 3

[0145] See also Fig.15 , shown is a schematic diagram of the structure of the optical lens 300 provided in Example 3 of the present invention. The optical lens of this embodiment is substantially the same as that of Example 1, and the main difference lies in that the optical parameters such as the curvature radius, aspheric coefficient, thickness, etc. of each lens surface are different.

[0146] The relevant parameters of each lens in the optical lens 300 in Example 3 are shown in Table 3-1.

[0147] Table 3-1

[0148]

[0149] The surface parameters of the aspheric lens of the optical lens 300 in Example 3 are shown in Table 3-2.

[0150] Table 3-2

[0151]

[0152]

[0153] In this embodiment, the field curvature curve, F-Tan (Theta) distortion curve, axial aberration curve, vertical axis chromatic aberration curve, MTF curve, and relative illumination curve of the optical lens 300 are shown in FIG. Fig.16 , Fig.17 , Fig.18 , Fig.19 , Fig. 20 , Fig.21 shown.

[0154] from Fig.16 It can be seen that the field curvature of the meridian image plane and the sagittal image plane is controlled within ±0.06mm, indicating that the optical lens can correct the field curvature well.

[0155] from Fig.17 It can be seen that the distortion of the optical lens is controlled within ±10%, indicating that the optical lens can correct the distortion well.

[0156] from Fig.18 It can be seen that the offset of axial aberration is controlled within ±0.03mm, which means that the optical lens can correct axial aberration well.

[0157] from Fig.19 It can be seen that the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±3μm, indicating that the optical lens can correct chromatic aberration well.

[0158] from Fig. 20 It can be seen that the MTF value of this embodiment is above 0.45 in the whole field of view. In the range of 0 to 200 lp / mm, the MTF curve decreases evenly and smoothly from the center to the edge of the field of view, and has good imaging quality and good detail resolution capability in both low-frequency and high-frequency conditions.

[0159] from Fig.21 It can be seen that at the maximum half field of view angle, the relative illumination value of the optical lens is still greater than 80%, indicating that the optical lens has good relative illumination.

[0160] Please refer to Table 4, which shows 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 chief 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.

[0161] Table 4

[0162]

[0163]

[0164] In summary of the above embodiments, 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 is possible to improve the imaging quality of the optical lens, reduce aberrations, and improve the imaging quality of the optical lens, so that the lens has one or more advantages such as telephoto, large image surface, and high imaging quality.

[0165] 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.

[0166] 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 successively includes from the object side to the imaging surface along the optical axis: A first lens with a negative optical power, whose object side and image side are both concave surfaces; A second lens with a positive optical power, whose object side and image side are both convex surfaces; A third lens with a negative optical power, whose object side is a concave surface and whose image side is a concave surface near the optical axis; A fourth lens with a positive optical power, whose image side is a convex surface; A fifth lens with a positive optical power, whose object side and image side are both convex surfaces; A sixth lens with a negative optical power, whose object side and image side are both concave surfaces; A seventh lens with a positive optical power, whose object side and image side are both convex surfaces; An eighth lens with a positive optical power, whose object side is a concave surface and whose image side is a convex surface; Wherein, the radius of curvature R1 of the object side of the first lens and the radius of curvature R2 of the image side of the first lens satisfy: 0.2 < (R1 + R2) / (R1 - R2) < 0.

8.

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

4.

3. The optical lens according to claim 1, characterized in that: The total 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 < TTL / IH < 2.

4.

4. 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: 4.7 < f8 / f < 12.

2.

5. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens and the combined focal length f567 of the fifth lens, the sixth lens and the seventh lens satisfy: 1.2 < f567 / f < 1.

9.

6. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens and the radius of curvature R1 of the object side of the first lens satisfy: -2.65 < R1 / f < -0.7; the effective focal length f of the optical lens and the radius of curvature R2 of the image side of the first lens satisfy: 0.35 < R2 / f < 0.

65.

7. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens and the radius of curvature R15 of the object side of the eighth lens satisfy: -0.45 < R15 / f < -0.

3.

8. The optical lens according to claim 1, characterized in that: The radius of curvature R15 of the object side of the eighth lens and the radius of curvature R16 of the image side of the eighth lens satisfy: 0.7 < R15 / R16 < 1.

9. The optical lens according to claim 1, characterized in that: The radius of curvature R15 of the object side of the eighth lens and the radius of curvature R16 of the image side of the eighth lens satisfy: -0.2 < (R15 - R16) / (R15 + R16) < 0.

10. The optical lens according to claim 1, characterized in that: The sagittal height Sag1 of the clear aperture semi-diameter of the object side of the first lens and the clear aperture semi-diameter d1 of the object side of the first lens satisfy: -0.2 < Sag1 / d1 < 0; the sagittal height Sag2 of the clear aperture semi-diameter of the image side of the first lens and the clear aperture semi-diameter d2 of the image side of the first lens satisfy: 0.1 < Sag2 / d2 < 0.35.

Images