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 convex surface; the third lens has negative focal power, the object side surface of the third lens near the optical axis 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; 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. The optical lens provided by the invention has the advantage of excellent imaging quality through specific surface shape arrangement and reasonable focal power distribution.

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 recent years, with the rapid development of smart home and security monitoring, smart surveillance cameras have entered thousands of households and become products that help people communicate with their families and record their beautiful lives, providing convenience for people's daily lives. As the scope of use of smart surveillance cameras expands and the number of usage scenarios increases, people have higher requirements for their performance, pursuing high-definition imaging effects even in extreme cold or hot environments, and being able to see the surrounding scenes clearly in dimly lit environments. However, although the surveillance lenses currently on the market perform well in some aspects, there is still room for improvement in some specific technical indicators.

[0003] Therefore, how to make the surveillance camera meet high imaging quality is a problem that needs to be solved urgently. 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] The technical solution adopted by the present invention is: An optical lens, composed of eight lenses, including: The first lens has a negative optical power, the object side surface of which is convex, and the image side surface of which is concave; The second lens has a negative optical power, its object side surface is concave, and its image side surface is convex; The third lens has a negative optical power, the object side surface of which is convex at the near optical axis and the image side surface of which is concave; a fourth lens having positive refractive power, whose object-side surface is convex and whose image-side surface is convex; a fifth lens having positive refractive power, whose object-side surface is convex and whose image-side surface is convex; a sixth lens having negative optical power, whose object-side surface is concave and whose image-side surface is concave; a seventh lens having positive refractive power, whose object-side surface is convex and whose image-side surface is convex; an eighth lens having positive refractive power, whose object-side surface is convex and whose image-side surface is concave; Among them, the object side curvature radius R3 of the second lens and the image side curvature radius R4 of the second lens satisfy: -0.7<(R3-R4) / (R3+R4)<0; the object side curvature radius R5 of the third lens and the image side curvature radius R6 of the third lens satisfy: 0<(R5-R6) / (R5+R6)<0.9.

[0006] More preferably, the total optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 5.3 < TTL / f < 6.6; 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: 2.9 < TTL / IH < 3.6.

[0007] More preferably, the maximum field of view angle FOV of the optical lens and the aperture value Fno of the optical lens satisfy: 100° < FOV / Fno < 115°; the true image height IH corresponding to the maximum field of view angle of the optical lens and the entrance pupil diameter EPD of the optical lens satisfy: 1.7 < IH / EPD < 2.2.

[0008] More preferably, the true image height IH corresponding to the maximum field of view angle of the optical lens and the effective focal length f of the optical lens satisfy: 1.6 < IH / f < 2.1; the back focal length BFL of the optical lens and the effective focal length f of the optical lens satisfy: 0.8 < BFL / f < 1.2.

[0009] More preferably, the effective focal length f of the optical lens, the maximum field of view angle FOV of the optical lens and the true image height IH corresponding to the maximum field of view angle of the optical lens satisfy: 53° < (f × FOV) / IH < 65°; the true image height IH corresponding to the maximum field of view angle of the optical lens and the back focal length BFL of the optical lens satisfy: 1.5 < IH / BFL < 2.3.

[0010] More preferably, the effective focal length f of the optical lens and the focal length f2 of the second lens satisfy: -10.5 < f2 / f < -3.7; the effective focal length f of the optical lens and the object-side curvature radius R3 of the second lens satisfy: -0.9 < R3 / f < -0.6; the effective focal length f of the optical lens and the image-side curvature radius R4 of the second lens satisfy: -1.4 < R4 / f < -0.9.

[0011] More preferably, the effective focal length f of the optical lens and the focal length f3 of the third lens satisfy: -12.3 < f3 / f < -6; the effective focal length f of the optical lens and the object-side curvature radius R5 of the third lens satisfy: 5.3 < R5 / f < 11.2; the effective focal length f of the optical lens and the image-side curvature radius R6 of the third lens satisfy: 2.3 < R6 / f < 3.9.

[0012] Further preferably, the effective focal length f of the optical lens and the focal length f6 of the sixth lens satisfy: -1.6 < f6 / f < -1; the effective focal length f of the optical lens and the object-side curvature radius R11 of the sixth lens satisfy: -5.8 < R11 / f < -3; the effective focal length f of the optical lens and the image-side curvature radius R12 of the sixth lens satisfy: 1.1 < R12 / f < 1.9.

[0013] Further preferably, the effective focal length f of the optical lens and the focal length f8 of the eighth lens satisfy: 19 < f8 / f < 36; the effective focal length f of the optical lens and the object-side curvature radius R15 of the eighth lens satisfy: 0.8 < R15 / f < 1.4; the effective focal length f of the optical lens and the image-side curvature radius R16 of the eighth lens satisfy: 0.8 < R16 / f < 1.4.

[0014] Further preferably, the combined focal length f1234 of the first lens, the second lens, the third lens and the fourth lens and the combined focal length f5678 of the fifth lens, the sixth lens, the seventh lens and the eighth lens satisfy: 1.8 < f1234 / f5678 < 3.2; the object-side clear aperture semi-diameter d1 of the first lens and the image-side clear aperture semi-diameter d16 of the eighth lens satisfy: 1.2 < d1 / d16 < 1.7.

[0015] Further preferably, the object-side clear aperture sagittal height Sag3 of the second lens and the object-side clear aperture semi-diameter d3 of the second lens satisfy: -0.5 < Sag3 / d3 < -0.1; the image-side clear aperture sagittal height Sag4 of the second lens and the image-side clear aperture semi-diameter d4 of the second lens satisfy: -0.4 < Sag4 / d4 < 0.

[0016] Compared with the prior art, the optical lens provided by the present invention, through specific surface shape settings and reasonable optical power distribution, not only effectively shortens the overall length of the optical lens but also has a large aperture, enabling the lens to achieve high-definition imaging even in a dim environment. At the same time, the lens also has a large field of view angle, capable of obtaining more scene information and meeting the requirements of large-range shooting. In addition, it can reasonably correct the overall aberration of the optical lens, achieve high-definition imaging, and improve the imaging quality of the optical lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which: Figure 1 It is a schematic structural diagram of the optical lens in Embodiment 1 of the present invention.

[0018] Figure 2It is a field curvature curve diagram of the optical lens in Example 1 of the present invention.

[0019] Figure 3 Graph showing the F-Theta distortion 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 This is the MTF curve diagram of the optical lens in Example 1 of the present invention.

[0023] Figure 7 This is a relative illumination curve diagram of the optical lens in Example 1 of the present invention.

[0024] Figure 8 Schematic diagram of the structure of the optical lens in Example 2 of the present invention.

[0025] Fig. 9 4 is a field curvature curve diagram of the optical lens in Example 2 of the present invention.

[0026] Fig.10 Graph showing the F-Theta distortion of the optical lens in Embodiment 2 of the present invention.

[0027] Fig.11 Graph showing the axial aberration of the optical lens in Embodiment 2 of the present invention.

[0028] Fig.12 Graph showing the vertical axis chromatic aberration of the optical lens in Example 2 of the present invention.

[0029] Fig.13 This is an MTF curve diagram of the optical lens in Example 2 of the present invention.

[0030] Fig.14 This is a relative illumination curve diagram of the optical lens in Example 2 of the present invention.

[0031] Fig.15 Schematic diagram of the structure of the optical lens in Example 3 of the present invention.

[0032] Fig.16 4 is a field curvature curve diagram of the optical lens in Example 3 of the present invention.

[0033] Fig.17 Graph showing the F-Theta distortion of the optical lens in Embodiment 3 of the present invention.

[0034] Fig.18 Graph showing the axial aberration of the optical lens in Embodiment 3 of the present invention.

[0035] Fig.19 Graph showing the vertical axis chromatic aberration of the optical lens in Example 3 of the present invention.

[0036] Fig. 20 This is the MTF curve diagram of the optical lens in Example 3 of the present invention.

[0037] Fig.21 This is a relative illumination curve diagram of the optical lens in Example 3 of the present invention.

[0038] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] The optical lens provided by the embodiment of the present invention is composed of eight lenses, which include: 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 sequence from the object side to the imaging surface along the optical axis.

[0047] In some embodiments, the first lens may have a negative optical power, with its object side surface being convex and its image side surface being concave. The second lens may have a negative optical power, with its object side surface being concave and its image side surface being convex. The third lens may have a negative optical power, with its object side surface being convex at the near optical axis and its image side surface being concave. The fourth lens may have a positive optical power, with its object side surface being convex and its image side surface being convex. The fifth lens may have a positive optical power, with its object side surface being convex and its image side surface being convex. The sixth lens may have a negative optical power, with its object side surface being concave and its image side surface being concave. The seventh lens may have a positive optical power, with its object side surface being convex and its image side surface being convex. The eighth lens may have a positive optical power, with its object side surface being convex and its image side surface being concave.

[0048] 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.

[0049] In some embodiments, the optical lens may further include a filter and a protective glass. The filter and the protective glass may be sequentially disposed between the eighth lens and the imaging surface along the optical axis. 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 normal imaging. The protective glass plays a role in protecting the optical lens, preventing the photosensitive chip from being damaged, and can improve the anti-impact and scratch-resistant capabilities of the optical lens, while having little impact on the imaging quality of the optical lens.

[0050] In some embodiments, the sixth lens and the seventh lens may be glued together to form a glued 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.

[0051] In some embodiments, the radius of curvature R3 of the object side surface of the second lens and the radius of curvature R4 of the image side surface of the second lens satisfy: -0.7 < (R3 - R4) / (R3 + R4) < 0; the radius of curvature R5 of the object side surface of the third lens and the radius of curvature R6 of the image side surface of the third lens satisfy: 0 < (R5 - R6) / (R5 + R6) < 0.9. Satisfying the above ranges can effectively slow down the degree of deflection of light entering the second lens and the third lens, which is beneficial to maintaining the miniaturization of the lens head and increasing the light flux entering the lens. More specifically, -0.26 < (R3 - R4) / (R3 + R4) < -0.14; 0.28 < (R5 - R6) / (R5 + R6) < 0.49.

[0052] In some embodiments, the total optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 5.3 < TTL / f < 6.6. Satisfying the above range can effectively limit the length of the lens, which is beneficial to the miniaturization of the optical lens. More specifically, 5.9 < TTL / f < 6.12.

[0053] 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: 2.9 < TTL / IH < 3.6. Satisfying the above range, by reasonably restricting the ratio of the total length of the optical lens to the image height, it is ensured that the lens has a larger image surface under the same total length, achieving the balance of miniaturization and large image surface of the optical lens and improving the market competitiveness. More specifically, 3.24 < TTL / IH < 3.28.

[0054] In some embodiments, the maximum field of view (FOV) of the optical lens and the f-number (Fno) of the optical lens satisfy: 100° < FOV / Fno < 115°. Meeting the above range defines that the optical lens has an appropriate field of view and f-number, enabling it to collect light at large angles and obtain good imaging quality. More specifically, 101° < FOV / Fno < 106.7°.

[0055] In some embodiments, the true image height (IH) corresponding to the maximum field of view of the optical lens and the entrance pupil diameter (EPD) of the optical lens satisfy: 1.7 < IH / EPD < 2.2. Meeting the above range can increase the width of the light beam entering the optical lens, enhancing the brightness at the image plane of the optical lens and avoiding vignetting. More specifically, 1.89 < IH / EPD < 1.98.

[0056] In some embodiments, the true image height (IH) corresponding to the maximum field of view of the optical lens and the effective focal length (f) of the optical lens satisfy: 1.6 < IH / f < 2.1. Meeting the above range controls the image height and focal length of the optical lens within a reasonable range, which helps the optical lens to have a large image plane and improve the imaging quality. More specifically, 1.8 < IH / f < 1.89.

[0057] In some embodiments, the back focal length (BFL) of the optical lens and the effective focal length (f) of the optical lens satisfy: 0.8 < BFL / f < 1.2. Meeting the above range is beneficial for achieving a balance between obtaining good imaging quality and an optical back focal length that is easy to assemble, ensuring the imaging quality of the optical lens while reducing the assembly process difficulty of the camera module. More specifically, 0.89 < BFL / f < 1.12.

[0058] In some embodiments, the effective focal length (f) of the optical lens, the maximum field of view (FOV) of the optical lens, and the true image height (IH) corresponding to the maximum field of view of the optical lens satisfy: 53° < (f × FOV) / IH < 65°. Meeting the above range, by reasonably restricting the relationship between the focal length, field of view, and image height of the optical lens, it can ensure that the optical lens has the characteristics of a large field of view and a large image plane, thereby enabling the optical lens to have good optical performance and being able to capture details of the object being photographed well. More specifically, 58.2° < (f × FOV) / IH < 59.58°.

[0059] In some embodiments, the true image height (IH) corresponding to the maximum field of view of the optical lens and the back focal length (BFL) of the optical lens satisfy: 1.5 < IH / BFL < 2.3. Meeting the above range defines that the optical lens has an appropriate back focus, facilitating the reasonable arrangement of the positions of each lens and reducing the processing and assembly difficulty at the same time. More specifically, 1.65 < IH / BFL < 2.05.

[0060] In some embodiments, the effective focal length f of the optical lens and the focal length f2 of the second lens satisfy: -10.5 < f2 / f < -3.7; the effective focal length f of the optical lens and the curvature radius R3 of the object side surface of the second lens satisfy: -0.9 < R3 / f < -0.6; the effective focal length f of the optical lens and the curvature radius R4 of the image side surface of the second lens satisfy: -1.4 < R4 / f < -0.9. Meeting the above ranges, controlling the second lens to have a suitable negative optical power and surface shape 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. More specifically, -9.58 < f2 / f < -4.1; -0.76 < R3 / f < -0.69; -1.23 < R4 / f < -1.01.

[0061] In some embodiments, the effective focal length f of the optical lens and the focal length f3 of the third lens satisfy: -12.3 < f3 / f < -6; the effective focal length f of the optical lens and the curvature radius R5 of the object side surface of the third lens satisfy: 5.3 < R5 / f < 11.2; the effective focal length f of the optical lens and the curvature radius R6 of the image side surface of the third lens satisfy: 2.3 < R6 / f < 3.9. Meeting the above ranges, controlling the third lens to have a suitable negative optical power and surface shape has the effect of diverging light. At the same field of view angle, it further diverges the light rays emitted from the first lens and the second lens, can disperse the central light rays and marginal light rays of each field of view, and enables the rear optical system to have a larger light receiving surface to receive the light rays emitted from the image side surface of the third lens, achieving a larger light input amount and being beneficial to increasing the relative illuminance. More specifically, -11.17 < f3 / f < -6.74; 5.87 < R5 / f < 10.16; 2.58 < R6 / f < 3.53.

[0062] In some embodiments, the effective focal length f of the optical lens and the focal length f6 of the sixth lens satisfy: -1.6 < f6 / f < -1; the effective focal length f of the optical lens and the curvature radius R11 of the object side surface of the sixth lens satisfy: -5.8 < R11 / f < -3; the effective focal length f of the optical lens and the curvature radius R12 of the image side surface of the sixth lens satisfy: 1.1 < R12 / f < 1.9. Meeting the above ranges can make the sixth lens have an appropriate negative optical power and surface shape, which is beneficial to balancing the astigmatism and field curvature of the optical lens and improving the imaging quality of the optical lens. More specifically, -1.47 < f6 / f < -1.16; -5.28 < R11 / f < -3.28; 1.3 < R12 / f < 1.76.

[0063] In some embodiments, the effective focal length f of the optical lens and the focal length f8 of the eighth lens satisfy: 19 < f8 / f < 36; the effective focal length f of the optical lens and the object-side curvature radius R15 of the eighth lens satisfy: 0.8 < R15 / f < 1.4; the effective focal length f of the optical lens and the image-side curvature radius R16 of the eighth lens satisfy: 0.8 < R16 / f < 1.4. Meeting the above ranges can make the eighth lens have an appropriate positive optical power and surface shape, which is beneficial to balancing the astigmatism of the optical lens and improving the imaging quality of the optical lens. More specifically, 21.26 < f8 / f < 33.16; 0.92 < R15 / f < 1.21; 0.91 < R16 / f < 1.22.

[0064] In some embodiments, the combined focal length f1234 of the first lens, the second lens, the third lens, and the fourth lens and the combined focal length f5678 of the fifth lens, the sixth lens, the seventh lens, and the eighth lens satisfy: 1.8 < f1234 / f5678 < 3.2. Meeting the above range is beneficial to balancing various aberrations of the system and improving the overall imaging quality by reasonably setting the relationship between the lens groups before and after the aperture stop. More specifically, 2 < f1234 / f5678 < 2.97.

[0065] In some embodiments, the object-side clear aperture semi-diameter d1 of the first lens and the image-side clear aperture semi-diameter d16 of the eighth lens satisfy: 1.2 < d1 / d16 < 1.7. Meeting the above range can limit the light ray trend within a reasonable range by controlling the aperture ratio of the front and rear lenses, making the illuminance on the imaging surface uniform. More specifically, 2 < d1 / d16 < 2.97.

[0066] In some embodiments, the object-side clear aperture sagittal height Sag3 of the second lens and the object-side clear aperture semi-diameter d3 of the second lens satisfy: -0.5 < Sag3 / d3 < -0.1; the image-side clear aperture sagittal height Sag4 of the second lens and the image-side clear aperture semi-diameter d4 of the second lens satisfy: -0.4 < Sag4 / d4 < 0. Meeting the above ranges helps to control the trend of light rays in the edge field of view and highlight the detailed information of the central field of view of the optical lens. More specifically, -0.37 < Sag3 / d3 < -0.28; -0.3 < Sag4 / d4 < -0.12.

[0067] In some embodiments, the effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -2.9 < f1 / f < -2.2. Meeting the above range is beneficial to the first lens accommodating a larger angle of light rays and collecting as much light as possible to enter the rear optical system by setting the first lens to have a negative refractive power, increasing the light flux while achieving a large field of view. More specifically, -2.67 < f1 / f < -2.45.

[0068] In some embodiments, the effective focal length f of the optical lens and the focal length f4 of the fourth lens satisfy: 1.7 < f4 / f < 2.2. Meeting the above range can effectively converge light, reduce the difficulty of correcting the distortion of the peripheral field of view, ensure that the lens has a small distortion while achieving a large field of view angle, and improve the overall imaging quality. More specifically, 1.93 < f4 / f < 2.02.

[0069] In some embodiments, the effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: 2.4 < f5 / f < 3.3. Meeting the above conditions and setting the fifth lens to have a positive refractive power 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. More specifically, 2.68 < f5 / f < 2.96.

[0070] In some embodiments, the effective focal length f of the optical lens and the focal length f7 of the seventh lens satisfy: 1.1 < f7 / f < 1.5. Meeting the above range can make the seventh lens have an appropriate positive optical power, which is beneficial to balancing the astigmatism of the optical lens and improving the imaging quality of the optical lens. More specifically, 1.23 < f7 / f < 1.4.

[0071] In some embodiments, the combined focal length f67 of the sixth lens and the seventh lens and the effective focal length f of the optical lens satisfy: 7 < f67 / f < 14.8. Meeting the above range, the sixth and seventh lenses form a cemented lens with a positive optical power, which can further converge the incident light, reduce the loss of light energy, and at the same time enable the diverging light to converge smoothly and enter the rear, further making the light trend transition smoothly and improving the relative illumination of the peripheral field of view. More specifically, 7.7 < f67 / f < 13.54.

[0072] 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 < (R11 + R12) / (R11 - R12) < 0.9. Meeting the above range and controlling the surface shape of the sixth lens is beneficial to increasing the imaging area and field of view angle of the optical lens, balancing the aberration of the optical lens, and improving the imaging quality of the optical lens. More specifically, 0.29 < (R11 + R12) / (R11 - R12) < 0.59.

[0073] In some embodiments, the focal length f6 of the sixth lens and the central thickness CT6 of the sixth lens satisfy: -11.5 < f6 / CT6 < -7.3. Meeting the above range and reasonably controlling the thickness of the sixth lens is beneficial to balancing the aberration of the optical lens and improving the imaging quality of the optical lens. More specifically, -10.54 < f6 / CT6 < -8.12.

[0074] In some embodiments, the radius of curvature R3 of the object side surface of the second lens, the central thickness CT2 of the second lens, and the radius of curvature R4 of the image side surface of the second lens satisfy: 0.3 < (R3 + CT2) / R4 < 0.5. When the above range is satisfied, the second 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. More specifically, 0.37 < (R3 + CT2) / R4 < 0.41.

[0075] In some embodiments, the optical lens satisfies the conditional formula: 4.4 mm < f < 5.6 mm, 4.2 mm < EPD < 5.3 mm, 27 mm < TTL < 33 mm, 0.9 < Fno < 1.2, 10° < CRA < 16°, 4 mm < BFL < 6 mm, 95° < FOV < 125°, 8.5 mm < IH < 10 mm; where f represents the effective focal length of the optical lens, EPD represents the entrance pupil diameter of the optical lens, TTL represents the total optical length of the optical lens, Fno represents the aperture value of the optical lens, CRA represents the principal ray incident angle at the maximum image height of the optical lens, BFL represents the back focal length of the optical lens, FOV represents the maximum field of view angle of the optical lens, and IH represents the image height corresponding to the maximum field of view angle of the optical lens. When the above conditions are satisfied, it indicates that the optical lens provided by the embodiments of the present invention has at least the characteristics of a large aperture, a large image plane, a small CRA, etc. More specifically, 4.88 mm < f < 5.1 mm, 4.65 mm < EPD < 4.86 mm, 29.8 mm < TTL < 30.2 mm, 1.04 < Fno < 1.06, 10.86° < CRA < 15.37°, 4.49 mm < BFL < 5.55 mm, 106.12° < FOV < 112.03°, 9.1 mm < IH < 9.3 mm.

[0076] 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. On the other hand, when the lens material is glass, the geometric chromatic aberration of the optical system can be effectively corrected by the low dispersion characteristic of the glass itself. The first lens, the fourth lens, the sixth lens, and the seventh lens in the optical lens provided by the present invention adopt glass lenses, and the second lens, the third lens, the fifth lens, and the eighth lens adopt plastic lenses. The optical lens of the present invention adopts a glass-plastic hybrid structure to improve the thermal stability.

[0077] 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 may be spherical lenses or aspherical lenses. Compared with spherical structures, aspherical structures can effectively reduce the aberration of the optical system, thereby reducing the number of lenses and reducing the size of lenses, and better realizing miniaturization of lenses. More specifically, the first lens, the fourth lens, the sixth lens, and the seventh lens of the present invention are spherical lenses, and the second lens, the third lens, the fifth lens, and the eighth lens can all be aspherical lenses, which can effectively reduce the aberration of the optical lens, thereby reducing the number of lenses and reducing the size of lenses, and better realizing miniaturization of lenses.

[0078] In various embodiments of the present invention, when the lens is an aspherical lens, the shapes of the aspherical surfaces of the optical lens satisfy the following equations: ; 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, and G are the fourth-order, sixth-order, eighth-order, tenth-order, twelfth-order, and fourteenth-order surface coefficients 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 , 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 100 includes, in order from the object side to the imaging surface along the optical axis: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, an aperture ST, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, a filter G1 and a protective glass G2.

[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 convex; The third lens L3 has negative refractive power, its object side surface S5 is convex at the near optical axis, 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 S10 is convex; The sixth lens L6 has negative refractive power, its object-side surface S11 is concave, and its image-side surface S12 is concave; The seventh lens L7 has positive refractive power, its object-side surface S13 is convex, and its image-side surface S14 is convex; The sixth lens L6 and the seventh lens L7 form a cemented lens group with positive refractive power, that is, the image-side surface S12 of the sixth lens L6 and the object-side surface S13 of the seventh lens L7 are cemented surfaces; The eighth lens L8 has positive refractive power, its object-side surface S15 is convex, and its image-side surface S16 is concave; The object side surface S17 and the image side surface S18 of the filter G1 are both planes; The object side surface S19 and the image side surface S20 of the protective glass G2 are both planes; The imaging surface S21 is a plane.

[0082] The first lens L1, the fourth lens L4, the sixth lens L6 and the seventh lens L7 are glass spherical lenses, and the second lens L2, the third lens L3, the fifth lens L5 and the eighth lens L8 are 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 field curvature curve, F-Theta distortion curve, axial aberration curve, vertical axis 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.

[0086] Figure 2The field curvature curve of the optical lens 100 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 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 ±0.03mm, indicating that the optical lens 100 can well correct the field curvature.

[0087] Figure 3 The F-Theta distortion curve of the optical lens 100 in 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 half field angle (unit: °). It can be seen from the figure that the distortion value is controlled within ±2%, indicating that the optical lens 100 can correct the distortion well.

[0088] 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 ±0.02mm, indicating that the optical lens 100 can better correct the axial aberration.

[0089] 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 (0.587 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 ±2 μm, indicating that the optical lens 100 can correct chromatic aberration very well.

[0090] Figure 6 The modulation transfer function (MTF) curve of the optical lens 100 in this embodiment is shown, which represents the imaging modulation degree of the lens at different spatial frequencies in 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 0.48 in the whole field of view, and in the range of 0 to 100 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.

[0091] Figure 7The relative illumination curve of the optical lens 100 in this embodiment is shown, which represents the relative illumination values ​​at different viewing angles on the imaging plane, with the horizontal axis representing the half viewing angle (unit: °) and the vertical axis representing the relative illumination. It can be seen from the figure that the relative illumination value of the optical lens 100 is still greater than 50% at the edge of the viewing field, indicating that the optical lens 100 has an excellent relative illumination.

[0092] Example 2 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. 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.

[0093] The relevant parameters of each lens in the optical lens 200 in Example 2 are shown in Table 2-1.

[0094] Table 2-1 The surface parameters of the aspheric lens of the optical lens 200 in Example 2 are shown in Table 2-2.

[0095] Table 2-2 In this embodiment, the field curvature curve, F-Theta distortion curve, axial aberration curve, vertical axis 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.

[0096] from Fig. 9 It can be seen that the field curvature of the meridian image plane and the sagittal image plane is controlled within ±0.02mm, indicating that the optical lens 200 can correct the field curvature well.

[0097] from Fig.10 It can be seen that the distortion value is controlled within ±4%, indicating that the optical lens 200 can correct the distortion well.

[0098] from Fig.11 It can be seen that the offset of the axial aberration is controlled within ±0.02 mm, indicating that the optical lens 200 can correct the axial aberration well.

[0099] from Fig.12 It can be seen that the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±2μm, indicating that the optical lens 200 can correct chromatic aberration very well.

[0100] from Fig.13 It can be seen that the MTF value of this embodiment is above 0.4 in the whole field of view. In the range of 0 to 100 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.

[0101] from Fig.14 It can be seen that the relative illumination value of the optical lens 200 is still greater than 50% at the edge of the field of view, indicating that the optical lens 200 has excellent relative illumination.

[0102] Example 3 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. 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.

[0103] The relevant parameters of each lens in the optical lens 300 in Example 3 are shown in Table 3-1.

[0104] Table 3-1 The surface parameters of the aspheric lens of the optical lens 300 in Example 3 are shown in Table 3-2.

[0105] Table 3-2 In this embodiment, the field curvature curve, F-Theta distortion curve, axial aberration curve, vertical 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.

[0106] from Fig.16 It can be seen that the field curvature of the meridian image plane and the sagittal image plane is controlled within ±0.02mm, indicating that the optical lens 300 can correct the field curvature well.

[0107] from Fig.17 It can be seen that the distortion value is controlled within ±3%, indicating that the optical lens 300 can correct the distortion well.

[0108] from Fig.18 It can be seen that the offset of the axial aberration is controlled within ±0.02 mm, indicating that the optical lens 300 can correct the axial aberration well.

[0109] from Fig.19 It can be seen that the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±2μm, indicating that the optical lens 300 can correct chromatic aberration very well.

[0110] from Fig. 20 It can be seen that the MTF value of this embodiment is above 0.6 in the whole field of view. In the range of 0 to 100 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.

[0111] from Fig.21 It can be seen that the relative illumination value of the optical lens 300 is still greater than 50% at the edge of the field of view, indicating that the optical lens 300 has excellent relative illumination.

[0112] Please refer to Table 4-1 and Table 4-2, which are the optical characteristics corresponding to the above-mentioned 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.

[0113] Table 4-1 Table 4-2 In summary, the optical lens provided by the present invention has at least the following advantages: (1) Through the specific surface shape setting and reasonable optical focal length distribution, the lens has a large aperture, which can achieve high-definition imaging even in dim environments; at the same time, it has a large field of view, so that more scene information can be obtained to meet the needs of large-scale shooting. The lens has a small head size, which is conducive to miniaturization and conforms to the current development of increasingly lightweight and high-performance security lenses.

[0114] (2) The optical lens of the present invention can reasonably correct the overall aberration of the optical lens, reduce the aberration, improve the resolution of the optical lens, achieve high-definition imaging, and improve the imaging quality of the optical lens.

[0115] (3) The glass-plastic hybrid structure improves the stability of the lens under high and low temperature conditions while also improving the imaging quality. At the same time, the lens has a smaller CRA, which can match the chip well and ensure good resolution quality.

[0116] 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.

[0117] 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, consisting of 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 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 convex; A third lens with a negative optical power, whose object side is convex near the optical axis 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 a positive optical power, whose object side is convex and whose image side is concave; Wherein, 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: -0.7 < (R3 - R4) / (R3 + R4) < 0; the curvature radius R5 of the object side of the third lens and the curvature radius R6 of the image side of the third lens satisfy: 0 < (R5 - R6) / (R5 + R6) < 0.

9.

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: 5.3 < TTL / f < 6.6; 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: 2.9 < TTL / IH < 3.

6.

3. The optical lens according to claim 1, characterized in that: The maximum field of view angle FOV of the optical lens and the f-number Fno of the optical lens satisfy: 100° < FOV / Fno < 115°; the true image height IH corresponding to the maximum field of view angle of the optical lens and the entrance pupil diameter EPD of the optical lens satisfy: 1.7 < IH / EPD < 2.

2.

4. The optical lens according to claim 1, characterized in that: The true image height IH corresponding to the maximum field of view angle of the optical lens and the effective focal length f of the optical lens satisfy: 1.6 < IH / f < 2.1; the back focal length BFL of the optical lens and the effective focal length f of the optical lens satisfy: 0.8 < BFL / f < 1.

2.

5. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens, the maximum field of view angle FOV of the optical lens and the true image height IH corresponding to the maximum field of view angle of the optical lens satisfy: 53° < (f × FOV) / IH < 65°; the true image height IH corresponding to the maximum field of view angle of the optical lens and the back focal length BFL of the optical lens satisfy: 1.5 < IH / BFL < 2.

3.

6. 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: -10.5 < f2 / f < -3.7; the effective focal length f of the optical lens and the curvature radius R3 of the object side of the second lens satisfy: -0.9 < R3 / f < -0.6; the effective focal length f of the optical lens and the curvature radius R4 of the image side of the second lens satisfy: -1.4 < R4 / f < -0.

9.

7. 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: -12.3 < f3 / f < -6; the effective focal length f of the optical lens and the object-side curvature radius R5 of the third lens satisfy: 5.3 < R5 / f < 11.2; the effective focal length f of the optical lens and the image-side curvature radius R6 of the third lens satisfy: 2.3 < R6 / f < 3.

9.

8. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens and the focal length f6 of the sixth lens satisfy: -1.6 < f6 / f < -1; the effective focal length f of the optical lens and the object-side curvature radius R11 of the sixth lens satisfy: -5.8 < R11 / f < -3; the effective focal length f of the optical lens and the image-side curvature radius R12 of the sixth lens satisfy: 1.1 < R12 / f < 1.

9.

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: 19 < f8 / f < 36; the effective focal length f of the optical lens and the object-side curvature radius R15 of the eighth lens satisfy: 0.8 < R15 / f < 1.4; the effective focal length f of the optical lens and the image-side curvature radius R16 of the eighth lens satisfy: 0.8 < R16 / f < 1.

4.

10. The optical lens according to claim 1, characterized in that: The combined focal length f1234 of the first lens, the second lens, the third lens and the fourth lens and the combined focal length f5678 of the fifth lens, the sixth lens, the seventh lens and the eighth lens satisfy: 1.8 < f1234 / f5678 < 3.2; the object-side clear aperture semi-diameter d1 of the first lens and the image-side clear aperture semi-diameter d16 of the eighth lens satisfy: 1.2 < d1 / d16 < 1.

7.

11. The optical lens according to claim 1, characterized in that: The object-side clear aperture sagittal height Sag3 of the second lens and the object-side clear aperture semi-diameter d3 of the second lens satisfy: -0.5 < Sag3 / d3 < -0.1; the image-side clear aperture sagittal height Sag4 of the second lens and the image-side clear aperture semi-diameter d4 of the second lens satisfy: -0.4 < Sag4 / d4 < 0.

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