Optical lens

Abstract

The invention provides an optical lens, which comprises eight lenses in total, and sequentially comprises a front group with positive focal power and a rear group with negative focal power from an object side to an imaging surface along an optical axis, the front group sequentially comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens from the object side to the imaging surface along the optical axis, the second lens has negative focal power; the third lens has positive focal power; the fourth lens has positive focal power; the rear group sequentially comprises a fifth lens with negative focal power, a sixth lens with negative focal power and a fifth lens with negative focal power from the object side to the imaging surface along the optical axis; the sixth lens has positive focal power; the seventh lens has negative focal power; and the eighth lens has negative focal power. According to the optical lens provided by the invention, through specific surface shape matching and reasonable focal power distribution, the imaging quality of the optical lens can be improved, and the optical lens has the advantage of excellent imaging quality.

Description

Technical Field

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

[0002] In modern video conferencing systems, high-quality image transmission is crucial. Most of the video conferencing lenses on the current market adopt fixed-focus or zoom designs to meet the requirements of different application scenarios. However, these traditional lenses often have the problems of relatively large volume and heavy weight, which not only limit the miniaturization design of the devices but also increase the manufacturing cost. Therefore, there is an urgent need to provide an optical lens that can meet the usage requirements of video conferencing, taking into account miniaturization and excellent imaging quality. Summary of the Invention

[0003] Aiming at the above problems, the purpose of the present invention is to provide an optical lens with the advantage of excellent imaging quality.

[0004] The present invention provides an optical lens, which has a total of eight lenses and successively includes, along the optical axis from the object side to the imaging surface: a front group with a positive focal power and a rear group with a negative focal power; The front group successively includes, along the optical axis from the object side to the imaging surface: A first lens with a negative focal power, whose object side is convex and whose image side is concave; A second lens with a negative focal power, whose object side is concave and whose image side is convex; A third lens with a positive focal power, whose object side is convex and whose image side is convex; A fourth lens with a positive focal power, whose object side is convex; The rear group successively includes, along the optical axis from the object side to the imaging surface: A fifth lens with a negative focal power, whose image side is concave; A sixth lens with a positive focal power, whose object side is convex and whose image side is convex; A seventh lens with a negative focal power, whose object side is concave and whose image side is convex; An eighth lens with a negative focal power, whose object side is convex near the optical axis and whose image side is concave near the optical axis; Wherein, the total optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 2.4 < TTL / f < 3; 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: 1.5 < TTL / IH < 1.7.

[0005] Further preferably, the combined focal length fa of the front group and the combined focal length fb of the rear group satisfy: -0.8 < fa / fb < -0.5.

[0006] More preferably, the true image height IH corresponding to the maximum field of view angle of the optical lens and the aperture value Fno of the optical lens satisfy: 5.6 mm < IH / Fno < 6.1 mm.

[0007] More preferably, the effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -25 < f1 / f < -2; the curvature radius R1 of the object side surface of the first lens, the curvature radius R2 of the image side surface of the first lens, and the central thickness CT1 of the first lens on the optical axis satisfy: 0.85 < R1 / (R2 + CT1) < 1.3.

[0008] More preferably, the effective focal length f of the optical lens and the focal length f2 of the second lens satisfy: -3.6 < f2 / f < -1.8; the curvature radius R4 of the image side surface of the second lens and the effective focal length f of the optical lens satisfy: -50 < R4 / f < -1.5.

[0009] More preferably, the effective focal length f of the optical lens and the focal length f3 of the third lens satisfy: 1.3 < f3 / f < 1.8; the effective focal length f of the optical lens and the focal length f4 of the fourth lens satisfy: 0.9 < f4 / f < 1.3.

[0010] More preferably, the effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: -1.85 < f5 / f < -1.4; the effective focal length f of the optical lens and the focal length f6 of the sixth lens satisfy: 1.2 < f6 / f < 1.7.

[0011] More preferably, the effective focal length f of the optical lens and the focal length f7 of the seventh lens satisfy: -10 < f7 / f < -6; the focal length f7 of the seventh lens and the focal length f8 of the eighth lens satisfy: 4 < f7 / f8 < 7.

[0012] More preferably, the effective focal length f of the optical lens and the focal length f8 of the eighth lens satisfy: -1.8 < f8 / f < -1.1; the central thickness CT1 of the first lens on the optical axis and the edge thickness ET1 of the first lens satisfy: 0.8 < CT1 / ET1 < 1.

[0013] More preferably, the light passing aperture DM11 of the object side surface of the first lens and the light passing aperture DM82 of the image side surface of the eighth lens satisfy: 1.2 < DM11 / DM82 < 1.5.

[0014] Compared with the prior art, the optical lens provided by the present invention adopts eight lenses with specific optical powers. Through specific surface shape matching and reasonable optical power distribution, it can improve the imaging quality of the optical lens, reduce aberrations, and enhance the imaging quality of the optical lens, enabling the lens to have one or more advantages such as miniaturization, large aperture, large image height, and high imaging quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] 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, where: Figure 1 FIG. 8 is a schematic structural diagram of the optical lens in Embodiment 1 of the present invention.

[0016] Figure 2 FIG. 12 is an astigmatism curve graph of the optical lens in Embodiment 1 of the present invention.

[0017] Figure 3 FIG. 16 is an axial aberration curve graph of the optical lens in Embodiment 1 of the present invention.

[0018] Figure 4 FIG. 20 is a lateral chromatic aberration curve graph of the optical lens in Embodiment 1 of the present invention.

[0019] Figure 5 FIG. 24 is a schematic structural diagram of the optical lens in Embodiment 2 of the present invention.

[0020] Figure 6 FIG. 28 is an astigmatism curve graph of the optical lens in Embodiment 2 of the present invention.

[0021] Figure 7 FIG. 32 is an axial aberration curve graph of the optical lens in Embodiment 2 of the present invention.

[0022] Figure 8 FIG. 36 is a lateral chromatic aberration curve graph of the optical lens in Embodiment 2 of the present invention.

[0023] Figure 9 FIG. 40 is a schematic structural diagram of the optical lens in Embodiment 3 of the present invention.

[0024] Figure 10 FIG. 44 is an astigmatism curve graph of the optical lens in Embodiment 3 of the present invention.

[0025] Figure 11 FIG. 48 is an axial aberration curve graph of the optical lens in Embodiment 3 of the present invention.

[0026] Figure 12 FIG. 52 is a lateral chromatic aberration curve graph of the optical lens in Embodiment 3 of the present invention.

[0027] Figure 13 FIG. 56 is a schematic structural diagram of the optical lens in Embodiment 4 of the present invention.

[0028] Figure 14 This is the astigmatism curve graph of the optical lens in Embodiment 4 of the present invention.

[0029] Figure 15 This is the axial aberration curve graph of the optical lens in Embodiment 4 of the present invention.

[0030] Figure 16 This is the lateral chromatic aberration curve graph of the optical lens in Embodiment 4 of the present invention.

[0031] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. Specific Embodiments

[0032] To better understand the present application, more detailed descriptions of various aspects of the present application will be made 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 do not 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.

[0033] It should be noted that in this specification, the expressions such as first, second, and third are only used to distinguish one feature from another feature and do not represent any limitation on the features. Therefore, without departing from the teachings of the present invention, the first lens discussed below may also be referred to as the second lens or the third lens.

[0034] In the drawings, for the sake of clarity, the thickness, dimensions, and shape of the lenses have been slightly exaggerated. Specifically, the spherical or aspherical shapes shown in the drawings are shown by way of example. That is, the spherical or aspherical shapes are not limited to the spherical or aspherical shapes shown in the drawings. The drawings are for illustrative purposes only and are not drawn to an exact scale.

[0035] In this document, 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 being photographed is called the object side surface of the lens, and the surface of each lens closest to the imaging surface is called the image side surface of the lens.

[0036] It should also be understood that the terms "comprising", "comprises", "having", "include", and / or "including", when used in this specification, denote the presence of the stated features, elements, and / or components, but do not preclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. Further, when an expression such as "at least one of..." appears after a list of listed features, it modifies the entire list of listed features rather than individual elements in the list. Additionally, when describing embodiments of the present application, the use of "may" means "one or more embodiments of the present application". Also, the term "exemplary" is intended to refer to an example or illustration.

[0037] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It should also be understood that terms (such as those defined in a common dictionary) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0038] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0039] The optical lens provided by the embodiment of the present invention has a total of eight lenses, and sequentially includes, along the optical axis from the object side to the imaging surface: a front group with a positive focal power and a rear group with a negative focal power.

[0040] The front group sequentially includes, along the optical axis from the object side to the imaging surface: a first lens, a second lens, a third lens, and a fourth lens. The first lens may have a negative focal power, its object side surface is convex, and its image side surface is concave. The second lens may have a negative focal power, its object side surface is concave, and its image side surface is convex. The third lens may have a positive focal power, its object side surface is convex, and its image side surface is convex. The fourth lens may have a positive focal power, its object side surface is convex, and its image side surface may be concave or convex.

[0041] The rear group sequentially includes, along the optical axis from the object side to the imaging surface: a fifth lens, a sixth lens, a seventh lens, and an eighth lens. The fifth lens may have a negative focal power, its object side surface may be concave or convex, and its image side surface is concave. The sixth lens may have a positive focal power, its object side surface is convex, and its image side surface is convex. The seventh lens may have a negative focal power, its object side surface is concave, and its image side surface is convex. The eighth lens may have a negative focal power, its object side surface is convex near the optical axis, and its image side surface is concave near the optical axis.

[0042] In some embodiments, the optical lens may further include a diaphragm, which may be located between the fourth lens and the fifth lens, i.e., between the front lens group and the rear lens group. It can be understood that the diaphragm is used to limit the amount of incident light to change the brightness of the image. At the same time, a diaphragm for limiting the light beam is provided between the front lens group and the rear lens group, which can reduce the generation of ghost images of the optical lens, is beneficial to converging the light entering the optical system, reducing the aperture of the rear port of the optical lens, and the diaphragm arranged here also enables the optical lens to have a larger aperture, improving the light input of the lens and enabling the lens to achieve high-definition imaging even in a dim environment.

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

[0044] In some embodiments, the total optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 2.4 < TTL / f < 3. Meeting the above conditions can effectively limit the length of the lens, which is beneficial to the miniaturization of the optical lens.

[0045] 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: 1.5 < TTL / IH < 1.7. Meeting the above conditions can better achieve the miniaturization of the lens. At the same time, when ensuring the same total length of the lens, it has a larger image plane, can match a larger-size imaging chip to achieve high-definition imaging.

[0046] In some embodiments, the combined focal length fa of the front lens group and the combined focal length fb of the rear lens group satisfy: -0.8 < fa / fb < -0.5. Meeting the above conditions, by reasonably setting the proportion of the combined focal lengths of the front and rear lens groups, on the one hand, it is beneficial to the convergence of light, enabling the light entering the system from the front end to smoothly enter the rear optical system, making the overall light path more gentle, and on the other hand, it is beneficial to optimizing aberrations and improving the overall resolution of the lens.

[0047] In some embodiments, the true image height IH corresponding to the maximum field of view angle of the optical lens and the F-number Fno of the optical lens satisfy: 5.6 mm < IH / Fno < 6.1 mm. Meeting the above conditions can enable the lens to better achieve the balance of large target surface imaging and large aperture performance, make the pixel distribution sparser (i.e., the pixel size is larger), can reduce noise in a darker environment, the dynamic range will be wider, and more details can be retained in the dark part, thereby improving the image quality.

[0048] In some embodiments, the effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -25 < f1 / f < -2. Meeting the above conditions can endow the first lens with an appropriate negative optical power, which is conducive to receiving more light into the system and expanding the field of view angle of the optical lens.

[0049] In some embodiments, the curvature radius R1 of the object side surface of the first lens, the curvature radius R2 of the image side surface of the first lens, and the central thickness CT1 of the first lens on the optical axis satisfy: 0.85 < R1 / (R2 + CT1) < 1.3. Meeting the above conditions enables the first lens to adopt a design similar to concentric circles, which is conducive to the gentle entry of light into the rear lens, can reduce the field curvature, correct the off-axis point aberration, and is beneficial to the correction of the aberration of the entire optical lens, thereby improving the imaging quality of the optical lens.

[0050] In some embodiments, the effective focal length f of the optical lens and the focal length f2 of the second lens satisfy: -3.6 < f2 / f < -1.8. The curvature radius R4 of the image side surface of the second lens and the effective focal length f of the optical lens satisfy: -50 < R4 / f < -1.5. Meeting the above conditions can endow the second lens with a large negative optical power, further diverge the incident light, avoid excessive light deflection caused by the over-concentration of the optical power of the first lens, and reduce the difficulty of chromatic aberration correction of the optical lens.

[0051] In some embodiments, the effective focal length f of the optical lens and the focal length f3 of the third lens satisfy: 1.3 < f3 / f < 1.8; the effective focal length f of the optical lens and the focal length f4 of the fourth lens satisfy: 0.9 < f4 / f < 1.3. Meeting the above conditions, by setting the third and fourth lenses to have a large positive optical power, the incident light at the front end can be effectively converged, which is beneficial to correcting the aberration and distortion of the edge field of view brought by the front-end lens, making the lens have less distortion and capable of providing a high-definition imaging effect.

[0052] In some embodiments, the effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: -1.85 < f5 / f < -1.4. Meeting the above conditions can endow the fifth lens with an appropriate negative optical power, which is conducive to increasing the imaging area of the optical lens and improving the imaging quality of the optical lens.

[0053] In some embodiments, the effective focal length f of the optical lens and the focal length f6 of the sixth lens satisfy: 1.2 < f6 / f < 1.7. Meeting the above conditions can endow the sixth lens with an appropriate positive optical power, which is conducive to the smooth transition of light, and at the same time balances the spherical aberration and field curvature of the fifth lens, improving the imaging quality of the optical lens.

[0054] In some embodiments, the effective focal length f of the optical lens and the focal length f7 of the seventh lens satisfy: -10 < f7 / f < -6; the focal length f7 of the seventh lens and the focal length f8 of the eighth lens satisfy: 4 < f7 / f8 < 7. Meeting the above conditions, by reasonably setting the refractive power relationship between the seventh and eighth lenses, the light rays in the marginal field of view can be effectively diverged. At the same time, combined with the curvature of the marginal region of the eighth lens, the exit angle of the light rays in the marginal field of view can be reduced, and the relative illuminance of the marginal field of view can be improved.

[0055] In some embodiments, the effective focal length f of the optical lens and the focal length f8 of the eighth lens satisfy: -1.8 < f8 / f < -1.1. Meeting the above conditions, by setting the eighth lens to have a relatively large negative refractive power, the incident light rays can be diverged to a greater extent, causing the peripheral light rays and the central light rays to turn upwards and reach a higher imaging position, better realizing the large target surface imaging of the lens and improving the imaging quality.

[0056] In some embodiments, the central thickness CT1 of the first lens on the optical axis and the edge thickness ET1 of the first lens satisfy: 0.8 < CT1 / ET1 < 1. Meeting the above conditions, on the one hand, the first lens can have a relatively moderate thickness ratio, reducing the processing difficulty; on the other hand, the refractive degree of the light rays in the marginal field of view can be appropriately increased, facilitating more incident light rays to enter the system and realizing the wide viewing angle of the lens.

[0057] In some embodiments, the clear aperture DM11 of the object side of the first lens and the clear aperture DM82 of the image side of the eighth lens satisfy: 1.2 < DM11 / DM82 < 1.5. Meeting the above conditions, the lens can have a relatively large incident aperture. While ensuring that as many light rays as possible enter the system, the area of the light rays entering the imaging surface is increased, which is beneficial to realizing the balance of the large image surface and the large aperture of the lens.

[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: 65° < (f × FOV) / IH < 80°. Meeting the above range can balance the requirements of large-range detection and high-quality imaging and improve the adaptability of the optical lens.

[0059] 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 of the optical lens satisfy: 1.4 < IH / f < 1.85. Meeting the above conditions, the lens can have a relatively large image surface and long focal length performance, and can match a relatively large-sized chip to achieve high-definition imaging.

[0060] 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: 0.01 < R3 / R4 < 0.5. Meeting the above conditions, by reasonably setting the meniscus shape of the second lens, it is beneficial to receive large-angle incident light and control the incident light to enter the optical system relatively gently, thereby reducing the tolerance sensitivity of the optical system.

[0061] 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: -1.5 < R11 / R12 < -0.15. Meeting the above conditions, by reasonably setting the biconvex shape of the sixth lens, it is beneficial to better converge light, shorten the distance for light to reach the next lens, and is beneficial to reducing the total length of the optical lens.

[0062] In some embodiments, the spacing CT78 of the seventh lens and the eighth lens on the optical axis and the central thickness CT8 of the eighth lens on the optical axis satisfy: 1.2 < CT78 / CT8 < 2; the spacing CT78 of the seventh lens and the eighth lens on the optical axis and the central thickness CT7 of the seventh lens on the optical axis satisfy: 1.5 < CT78 / CT7 < 4. Meeting the above conditions is beneficial to the spatial arrangement of the seventh lens and the eighth lens, reduces the processing difficulty, and improves the production yield.

[0063] In some embodiments, the clear aperture DM1 of the first lens, the clear aperture DM2 of the second lens, the clear aperture DM3 of the third lens, and the clear aperture DM4 of the fourth lens satisfy: DM1 > DM2 > DM3 > DM4; the clear aperture DM5 of the fifth lens, the clear aperture DM6 of the sixth lens, the clear aperture DM7 of the seventh lens, and the clear aperture DM8 of the eighth lens satisfy: DM8 > DM7 > DM6 > DM5. Meeting the above conditions can, on the one hand, make the assembly of the lens more convenient, and on the other hand, while ensuring that the lens has a large light flux, it also has a small rear-end volume, better realizing the miniaturization of the lens volume.

[0064] In some embodiments, the combined focal length fa of the front lens group and the effective focal length f of the optical lens satisfy: 0.75 < fa / f < 1; meeting the above conditions, by reasonably distributing the combined focal length of the front-end lens group, it is beneficial to reduce the spherical aberration and field curvature generated by the front-end lens of the optical lens and improve the imaging quality of the optical lens.

[0065] In some embodiments, the combined focal length fb of the rear lens group and the effective focal length f of the optical lens satisfy: -1.8 < fb / f < -1. Meeting the above conditions can diverge the light entering the system to a certain extent, which is beneficial to increasing the height of the light entering the image plane. At the same time, it is beneficial to balance the distortion and astigmatism generated by the front-end lens of the optical lens and improve the imaging quality of the optical lens.

[0066] In some embodiments, the optical lens satisfies the conditional formula: 6.5 mm < f < 8 mm, 18 mm < TTL < 20 mm, 1.9 < Fno < 2.1, 11 mm < IH < 12 mm, 110° < FOV < 120°, where f represents the effective focal length 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 true image height corresponding to the maximum field of view angle of the optical lens, and FOV represents the maximum field of view angle of the optical lens. Meeting the above conditions indicates that the optical lens provided by the embodiments of the present invention has at least: a relatively large aperture value, enabling the lens to achieve high-definition imaging even in a relatively dark environment; a relatively large imaging surface, which can be matched with a larger-sized chip to achieve high-definition imaging.

[0067] In some embodiments, all eight lenses in the optical lens can be made of plastic lenses or adopt a structure with a combination of glass and plastic materials. Preferably, the optical lens of the present invention adopts a lens structure with a combination of eight glass and plastic materials, which can improve the thermal stability performance. Specifically, the second lens and the third lens can be made of glass lenses, and the first lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens are all plastic lenses; adopting a glass-plastic hybrid structure can effectively reduce costs, correct aberrations, reduce the volume, and provide an optical lens product with higher cost performance.

[0068] 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, in the optical lens provided by the present invention, the second lens and the third lens adopt spherical lenses, and the first lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens can adopt aspherical lenses.

[0069] In each embodiment of the present invention, when the lens adopts an aspherical lens, the surface shapes of the aspherical surfaces of the optical lens satisfy the following equations: ; where z is the distance between the curved surface and the vertex of the curved surface in the optical axis direction, h is the distance from the optical axis to the curved surface, c is the curvature of the vertex of the curved surface, K is the conic coefficient, and B, C, D, E, F, G, H are the surface coefficients of the fourth order, sixth order, eighth order, tenth order, twelfth order, fourteenth order, and sixteenth order respectively.

[0070] The present invention will be further described below with reference to multiple embodiments. In each embodiment, the thickness, radius of curvature, and material selection of each lens in the optical lens are somewhat different. For specific differences, please refer to the parameter tables of each embodiment. The following embodiments are only preferred embodiments of the present invention, but the embodiments of the present invention are not limited only by the following embodiments. Any other changes, substitutions, combinations, or simplifications made without departing 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.

[0071] Embodiment 1 Please refer to Figure 1 , which shows a schematic structural diagram of an optical lens 100 provided in Embodiment 1 of the present invention. The optical lens 100 sequentially includes, along the optical axis from the object side to the imaging surface S19: a front group with positive optical power, a stop ST, a rear group with negative optical power, and a filter G1; The front group sequentially includes, along the optical axis from the object side to the imaging surface: a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4.

[0072] Among them, the first lens L1 has negative optical power, its object side surface S1 is convex, and its image side surface S2 is concave; The second lens L2 has negative optical power, its object side surface S3 is concave, and its image side surface S4 is convex; The third lens L3 has positive optical power, its object side surface S5 is convex, and its image side surface S6 is convex; The fourth lens L4 has positive optical power, its object side surface S7 is convex, and its image side surface S8 is concave near the optical axis; The rear group sequentially includes, along the optical axis from the object side to the imaging surface: a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8.

[0073] Among them, the fifth lens L5 has negative optical power, its object side surface S9 is convex, and its image side surface S10 is concave; The sixth lens L6 has positive optical power, its object side surface S11 is convex, and its image side surface S12 is convex; The seventh lens L7 has negative optical power, its object side surface S13 is concave, and its image side surface S14 is convex; The eighth lens L8 has negative optical power, its object side surface S15 is convex near the optical axis, and its image side surface S16 is concave near the optical axis; Both the object side surface S17 and the image side surface S18 of the filter G1 are flat; The imaging surface S19 is flat.

[0074] The second lens L2 and the third lens L3 are made of glass spherical lenses; the first lens L1, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the eighth lens L8 are all made of plastic aspherical lenses.

[0075] The relevant parameters of each lens in the optical lens 100 in Embodiment 1 are shown in Table 1-1.

[0076] Table 1-1 The surface shape parameters of the aspherical lenses of the optical lens 100 in Embodiment 1 are shown in Table 1-2.

[0077] Table 1-2 In this embodiment, the astigmatism curve graph, the axial aberration curve graph, and the lateral chromatic aberration curve graph of the optical lens 100 are respectively as Figure 2 , Figure 3 , Figure 4 shown.

[0078] Figure 2 shows the astigmatism curve graph of the optical lens 100 in this embodiment, which represents the astigmatism of light rays in the meridional image plane and the sagittal image plane. The horizontal axis represents the offset (unit: mm), and the vertical axis represents the semi-field angle (unit: °). It can be seen from the figure that the astigmatism of the meridional image plane and the sagittal image plane is controlled within ±0.1 mm, indicating that the optical lens 100 can correct astigmatism well.

[0079] Figure 3 shows the axial aberration curve graph of the optical lens 100 in this embodiment, which represents the aberration of each wavelength on the optical axis at the imaging plane. The horizontal axis represents the axial aberration value (unit: mm), and the vertical axis represents the normalized pupil radius. It can be seen from the figure that the offset of the axial aberration is controlled within ±0.03 mm, indicating that the optical lens 100 can correct axial aberration well.

[0080] Figure 4 shows the lateral chromatic aberration curve graph of the optical lens 100 in this embodiment, which represents the chromatic aberration of each wavelength relative to the central wavelength (0.555 μm) at different image heights on the imaging plane. The horizontal axis represents the lateral 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 lateral chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±1 μm, indicating that the optical lens 100 can correct chromatic aberration well.

[0081] Embodiment 2 Please refer to Figure 5, which shows the structural schematic diagram of the optical lens 200 provided in Embodiment 2 of the present invention. Compared with Embodiment 1, the main differences are as follows: the image side S8 of the fourth lens L4 is a convex surface; the object side S9 of the fifth lens L5 is a concave surface; the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0082] The relevant parameters of each lens in the optical lens 200 in Embodiment 2 are shown in Table 2-1.

[0083] Table 2-1 The aspherical lens surface parameters of the optical lens 200 in Embodiment 2 are shown in Table 2-2.

[0084] Table 2-2 In this embodiment, the astigmatism curve graph, axial aberration curve graph, and lateral chromatic aberration curve graph of the optical lens 200 are respectively as Figure 6 , Figure 7 , Figure 8 shown.

[0085] From Figure 6 it can be seen that the astigmatism between the meridional image plane and the sagittal image plane is controlled within ±0.1 mm, indicating that the optical lens 200 can correct astigmatism well.

[0086] From Figure 7 it can be seen that the offset of the axial aberration is controlled within ±0.03 mm, indicating that the optical lens 200 can correct the axial aberration well.

[0087] From Figure 8 it can be seen that the lateral chromatic aberration between the longest wavelength and the shortest wavelength is controlled within ±1.5 μm, indicating that the optical lens 200 can correct chromatic aberration well.

[0088] Embodiment 3 Please refer to Figure 9 , which shows the structural schematic diagram of the optical lens 300 provided in Embodiment 3 of the present invention. Compared with Embodiment 1, the main differences are as follows: the image side S8 of the fourth lens L4 is a convex surface; the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0089] The relevant parameters of each lens in the optical lens 300 in Embodiment 3 are shown in Table 3-1.

[0090] Table 3-1 The aspherical lens surface parameters of the optical lens 300 in Embodiment 3 are shown in Table 3-2.

[0091] Table 3-2 In this embodiment, the astigmatism curve graph, axial aberration curve graph, and lateral chromatic aberration curve graph of the optical lens 300 are respectively as shown in Figure 10 , Figure 11 , Figure 12 .

[0092] From Figure 10 , it can be seen that the astigmatism between the meridional image plane and the sagittal image plane is controlled within ±0.1 mm, indicating that the optical lens 300 can correct astigmatism well.

[0093] From Figure 11 , 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 axial aberration well.

[0094] From Figure 12 , it can be seen that the lateral chromatic aberration between the longest wavelength and the shortest wavelength is controlled within ±2 μm, indicating that the optical lens 300 can correct chromatic aberration well.

[0095] Embodiment 4 Please refer to Figure 13 . The following is a schematic structural diagram of the optical lens 400 provided in Embodiment 4 of the present invention. Compared with Embodiment 1, the main differences are as follows: The image side surface S8 of the fourth lens L4 is a convex surface; the object side surface S9 of the fifth lens L5 is a concave surface; the optical parameters such as the curvature radius and lens thickness of each lens surface are different.

[0096] The relevant parameters of each lens in the optical lens 400 in Embodiment 4 are shown in Table 4-1.

[0097] Table 4-1 The aspheric lens surface type parameters of the optical lens 400 in Embodiment 4 are shown in Table 4-2.

[0098] Table 4-2 In this embodiment, the astigmatism curve graph, axial aberration curve graph, and lateral chromatic aberration curve graph of the optical lens 400 are respectively as shown in Figure 14 , Figure 15 , Figure 16 .

[0099] From Figure 14 , it can be seen that the astigmatism between the meridional image plane and the sagittal image plane is controlled within ±0.1 mm, indicating that the optical lens 400 can correct astigmatism well.

[0100] FromFigure 15 It can be seen that the offset of the axial aberration is controlled within ±0.03 mm, indicating that the optical lens 400 can correct the axial aberration well.

[0101] From Figure 16 It can be seen that the lateral chromatic aberration between the longest wavelength and the shortest wavelength is controlled within ±1.5 μm, indicating that the optical lens 400 can correct the chromatic aberration well.

[0102] Please refer to Table 5 for the optical characteristics corresponding to the above embodiments, including the effective focal length f of the optical lens, the total optical length TTL, the f-number Fno, the true image height IH corresponding to the maximum field of view angle, the chief ray angle of incidence CRA at the maximum image height, the maximum field of view angle FOV, and the values corresponding to each conditional expression in each embodiment.

[0103] Table 5 In summary of the above embodiments, the optical lens provided by the present invention adopts an eight-piece glass-plastic hybrid structure. Through specific surface shape settings and reasonable optical power distribution, the structure of the optical lens is relatively compact, effectively shortening the overall length of the optical lens, which is beneficial to miniaturization; it has a large f-number, enabling the lens to achieve high-definition imaging even in a relatively dark environment; at the same time, it has a large imaging surface and can match a larger-sized chip to achieve high-definition imaging. In addition, it can reasonably correct the overall aberration of the optical lens, has the characteristics of high pixels, and improves the imaging quality of the optical lens.

[0104] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "example", "specific example", "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0105] The above-described embodiments merely represent several implementation manners of the present invention, and their descriptions are relatively specific and detailed, but should not be construed as limiting the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims

1. An optical lens, comprising eight lenses, characterized in that: It sequentially includes, from the object side to the imaging surface along the optical axis: a front group with positive optical power and a rear group with negative optical power; The front group sequentially includes, from the object side to the imaging surface along the optical axis: A first lens with negative optical power, whose object side is convex and whose image side is concave; A second lens with negative optical power, whose object side is concave and whose image side is convex; A third lens with positive optical power, whose object side is convex and whose image side is convex; A fourth lens with positive optical power, whose object side is convex; The rear group sequentially includes, from the object side to the imaging surface along the optical axis: A fifth lens with negative optical power, whose image side is concave; A sixth lens with positive optical power, whose object side is convex and whose image side is convex; A seventh lens with negative optical power, whose object side is concave and whose image side is convex; An eighth lens with negative optical power, whose object side is convex near the optical axis and whose image side is concave near the optical axis; Wherein, the total optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 2.4 < TTL / f < 3; 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: 1.5 < TTL / IH < 1.

7.

2. The optical lens according to claim 1, characterized in that: The combined focal length fa of the front group and the combined focal length fb of the rear group satisfy: -0.8 < fa / fb < -0.

5.

3. 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 aperture value Fno of the optical lens satisfy: 5.6mm < IH / Fno < 6.1mm.

4. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -25 < f1 / f < -2; the object side curvature radius R1 of the first lens, the image side curvature radius R2 of the first lens and the central thickness CT1 of the first lens on the optical axis satisfy: 0.85 < R1 / (R2 + CT1) < 1.

3.

5. 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: -3.6 < f2 / f < -1.8; the image side curvature radius R4 of the second lens and the effective focal length f of the optical lens satisfy: -50 < R4 / f < -1.

5.

6. 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: 1.3 < f3 / f < 1.8; the effective focal length f of the optical lens and the focal length f4 of the fourth lens satisfy: 0.9 < f4 / f < 1.

3.

7. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: -1.85 < f5 / f < -1.4; the effective focal length f of the optical lens and the focal length f6 of the sixth lens satisfy: 1.2 < f6 / f < 1.

7.

8. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens and the focal length f7 of the seventh lens satisfy: -10 < f7 / f < -6; the focal length f7 of the seventh lens and the focal length f8 of the eighth lens satisfy: 4 < f7 / f8 < 7.

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: -1.8 < f8 / f < -1.1; the central thickness CT1 of the first lens on the optical axis and the edge thickness ET1 of the first lens satisfy: 0.8 < CT1 / ET1 < 1.

10. The optical lens according to claim 1, characterized in that: The clear aperture DM11 of the object side of the first lens and the clear aperture DM82 of the image side of the eighth lens satisfy: 1.2 < DM11 / DM82 < 1.5.

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