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

Description

Technical Field

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

[0002] With the rapid development of fields such as drones, security, and automobiles, the pursuit of the imaging effect of the lenses carried by them has become more diversified. At present, drones are developing rapidly and have won the favor of consumers with their unique high-altitude perspective and wide shooting range. Correspondingly, the demand for the optical lenses supporting them is also increasing. The optical lenses carried by them not only require high-definition image quality but also require the ability to present large local details, so as to achieve that the local details can be vividly displayed even in the high-altitude field of view and capture local close-up pictures.

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

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

[0005] The present invention provides an optical lens, which has a total of eight lenses and successively includes, along the optical axis from the object side to the imaging surface: 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 concave; 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 and whose image side is convex; A fifth lens with negative optical power, whose object side is concave and 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 positive optical power, whose object side is convex; Wherein, 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: 2.2 < TTL / IH < 2.8; the combined focal length fa of the first lens, the second lens, and the third lens and the combined focal length fb of the fourth lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens satisfy: 0.8 < fa / fb < 2.2.

[0006] More preferably, the effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -4 < f1 / f < -3; the curvature radius R1 of the object side surface of the first lens and the curvature radius R2 of the image side surface of the first lens satisfy: 3 < R1 / R2 < 4.

[0007] More preferably, the effective focal length f of the optical lens and the focal length f2 of the second lens satisfy: -2.5 < f2 / f < -2.

[0008] More preferably, the effective focal length f of the optical lens and the focal length f3 of the third lens satisfy: 2 < f3 / f < 2.8; the curvature radius R5 of the object side surface of the third lens and the curvature radius R6 of the image side surface of the third lens satisfy: -2 < R5 / R6 < -1.2.

[0009] More preferably, the effective focal length f of the optical lens and the focal length f4 of the fourth lens satisfy: 1.3 < f4 / f < 1.8; the effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: -1.5 < f5 / f < -1.

[0010] More preferably, the effective focal length f of the optical lens and the focal length f6 of the sixth lens satisfy: 2.1 < f6 / f < 2.8.

[0011] More preferably, the effective focal length f of the optical lens and the focal length f7 of the seventh lens satisfy: -13 < f7 / f < -8.5; the curvature radius R13 of the object side surface of the seventh lens, the curvature radius R14 of the image side surface of the seventh lens and the central thickness CT7 of the seventh lens satisfy: 0.85 < (R13 - CT7) / R14 < 1.

[0012] More preferably, the effective focal length f of the optical lens and the focal length f8 of the eighth lens satisfy: 4 < f8 / f < 6; the focal length f7 of the seventh lens and the focal length f8 of the eighth lens satisfy: -3 < f7 / f8 < -1.5.

[0013] More preferably, the curvature radius R3 of the object side surface of the second lens and the effective focal length f of the optical lens satisfy: -20 < R3 / f < -13; the curvature radius R4 of the image side surface of the second lens and the effective focal length f of the optical lens satisfy: 1 < R4 / f < 1.6.

[0014] More preferably, the overall length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 8.5 < TTL / f < 10; the effective focal length f of the optical lens and the true image height IH corresponding to the maximum field of view angle of the optical lens satisfy: 3.4 < IH / f < 3.6.

[0015] Further preferably, the effective focal length f of the optical lens and the combined focal length f45 of the fourth lens and the fifth lens satisfy: -25 <f45 / f<-15。

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

[0042] In some embodiments, the optical lens may further include an aperture, and the aperture may be located between the third lens and the fourth 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 third lens and the fourth lens, it is convenient to correct the aperture aberration.

[0043] In some embodiments, the optical lens may further include a filter disposed between the eighth lens and the imaging surface. The filter is used to filter out interfering light and 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 true image height IH corresponding to the maximum field of view angle of the optical lens satisfy: 2.2 < TTL / IH < 2.8. Meeting the above conditions can better achieve the miniaturization of the lens, and at the same time ensure that the lens has a larger image surface, capable of matching a larger-sized imaging chip to achieve high-definition imaging.

[0045] In some embodiments, the combined focal length fa of the first lens, the second lens, and the third lens and the combined focal length fb of the fourth lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens satisfy: 0.8 < fa / fb < 2.2. Meeting the above conditions, by reasonably setting the focal length relationship of the front and rear lens groups, it helps the smooth transition of light, expands the field of view angle of the optical lens, reduces the difficulty of correcting distortion and chromatic aberration of the rear lens, and improves the image quality of the optical lens.

[0046] In some embodiments, the effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -4 < f1 / f < -3. Meeting the above conditions, by reasonably setting the meniscus shape of the first lens, it is beneficial for the first lens to receive a larger angle of light and collect as much light as possible into the rear optical system, achieving a large field of view while increasing the light flux.

[0047] In some embodiments, the curvature radius R1 of the object side surface of the first lens and the curvature radius R2 of the image side surface of the first lens satisfy: 3 < R1 / R2 < 4. Meeting the above conditions, the first lens adopts a convex-concave meniscus shape, which helps the incident light to converge, reduces the aperture of the front lens, is beneficial for the miniaturization of the front part, and at the same time the first lens is made of glass material, having an anti-scratch effect.

[0048] In some embodiments, the effective focal length f of the optical lens and the focal length f2 of the second lens satisfy: -2.5 < f2 / f < -2. Meeting the above conditions, the second lens has a negative optical power, which can share the negative optical power at the front end of the optical lens, thus helping to avoid excessive light deflection caused by the overly concentrated optical power of the first lens and reducing the difficulty of chromatic aberration correction of the optical lens.

[0049] In some embodiments, the effective focal length f of the optical lens and the focal length f3 of the third lens satisfy: 2 < f3 / f < 2.8. Meeting the above conditions, the third lens can have an appropriate positive optical power, which is beneficial for the smooth transition of the light trend and improves the imaging quality of the optical lens.

[0050] In some embodiments, 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: -2 < R5 / R6 < -1.2. Meeting the above conditions is beneficial to better achieve the convergence of light, shorten the distance for light to reach the next lens, and is conducive to reducing the total length of the optical lens.

[0051] In some embodiments, the effective focal length f of the optical lens and the focal length f4 of the fourth lens satisfy: 1.3 < f4 / f < 1.8. Meeting the above conditions can further effectively converge light, reduce the difficulty of correcting the distortion of the edge 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.

[0052] In some embodiments, the effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: -1.5 < f5 / f < -1. Meeting the above conditions can make the fifth lens have an appropriate negative optical power, which is beneficial to balancing the astigmatism and field curvature 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: 2.1 < f6 / f < 2.8. Meeting the above conditions 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.

[0054] In some embodiments, the effective focal length f of the optical lens and the focal length f7 of the seventh lens satisfy: -13 < f7 / f < -8.5. Meeting the above conditions is beneficial to diverging the light in the central field of view to a certain extent, and at the same time, combining the curvature of the edge field of view to reduce the exit angle of the light in the edge field of view and improve the relative illumination of the edge field of view.

[0055] In some embodiments, the radius of curvature R13 of the object side surface of the seventh lens, the radius of curvature R14 of the image side surface of the seventh lens and the central thickness CT7 of the seventh lens satisfy: 0.85 < (R13 - CT7) / R14 < 1. Meeting the above conditions, the seventh 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.

[0056] In some embodiments, the effective focal length f of the optical lens and the focal length f8 of the eighth lens satisfy: 4 < f8 / f < 6. Meeting the above conditions is beneficial to increasing the area of light entering the imaging surface, realizing large target surface imaging of the lens, and improving the imaging quality of the optical lens.

[0057] In some embodiments, the focal length f7 of the seventh lens and the focal length f8 of the eighth lens satisfy: -3 < f7 / f8 < -1.5. By satisfying the above conditions and reasonably setting the focal length relationship between the seventh and eighth lenses, the light can be diverged to a certain extent and the aberration can be effectively corrected, which is beneficial to achieving large target surface imaging of the lens.

[0058] In some embodiments, the radius of curvature R3 of the object side surface of the second lens and the effective focal length f of the optical lens satisfy: -20 < R3 / f < -13; the radius of curvature R4 of the image side surface of the second lens and the effective focal length f of the optical lens satisfy: 1 < R4 / f < 1.6. By satisfying the above conditions, the second lens adopts a double concave surface type, which is beneficial to collecting the light rays incident after passing through the first lens, enabling the light ray trend to transition smoothly, and improving the imaging quality of the optical lens.

[0059] In some embodiments, the overall optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 8.5 < TTL / f < 10. By satisfying the above conditions, the length of the lens can be effectively limited, which is beneficial to achieving miniaturization of the optical lens.

[0060] In some embodiments, the effective focal length f of the optical lens and the true image height IH corresponding to the maximum field of view angle of the optical lens satisfy: 3.4 < IH / f < 3.6. By satisfying the above conditions, it is beneficial to achieve the large wide-angle characteristic of the lens, thereby meeting the large-range shooting requirements, and it can also achieve the large image surface characteristic, thereby improving the imaging quality of the optical lens.

[0061] In some embodiments, the effective focal length f of the optical lens and the combined focal length f45 of the fourth lens and the fifth lens satisfy: -25 < f45 / f < -15. By satisfying the above conditions, the fourth and fifth lenses form a cemented lens with negative optical power. By reasonably setting the focal length relationship of the fourth and fifth cemented lenses, it is beneficial to eliminate the chromatic aberration of the system, and at the same time make the light ray trend transition smoothly, and improve the relative illumination of the edge field of view.

[0062] In some embodiments, the back focal length BFL of the optical lens and the effective focal length f of the optical lens satisfy: 0.9 < BFL / f < 1.2. Within the above range, it is defined that the optical lens has an appropriate back focus, which is convenient for reasonably arranging the positions of each lens, and at the same time reduces the processing and assembly difficulty.

[0063] In some embodiments, the refractive index Nd1 of the first lens satisfies: Nd1 > 1.75. By satisfying the above conditions, the first lens adopts a glass lens with a high refractive index, which is beneficial to the back focus compensation of the system at high and low temperatures, improves the imaging quality of the system at high and low temperatures, and achieves good thermal stability.

[0064] In some embodiments, the focal length f1 of the first lens and the focal length f2 of the second lens satisfy: 1.5 < f1 / f2 < 1.65. Meeting the above conditions can effectively converge a wide range of light entering the system, and at the same time is beneficial for the rear-end optical system to correct large-angle aberrations, thereby achieving the balance of miniaturization and high pixels of the optical lens.

[0065] In some embodiments, the focal length f4 of the fourth lens and the focal length f5 of the fifth lens satisfy: -1.35 < f4 / f5 < -1.2. Meeting the above conditions, by reasonably setting the focal length relationship between the fourth and fifth lenses, chromatic aberration of the system can be better eliminated and the overall imaging quality can be improved.

[0066] In some embodiments, the combined focal length fa of the first lens, the second lens, and the third lens and the effective focal length f of the optical lens satisfy: 4.5 < fa / f < 6. Meeting the above conditions, by reasonably distributing the combined focal length of the first lens to the third lens, it is beneficial to reduce the astigmatism and field curvature generated by the front-end lens of the optical lens and improve the imaging quality of the optical lens.

[0067] In some embodiments, the combined focal length fb of the fourth lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens and the effective focal length f of the optical lens satisfy: 2 < fb / f < 6. Meeting the above conditions, by reasonably distributing the combined focal length of the fifth lens to the eighth lens, 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.

[0068] In some embodiments, the optical lens satisfies the conditional formula: 0.9mm < f < 1.1mm, 8mm < TTL < 10mm, FOV > 180°, CRA < 23°; where f represents the effective focal length of the optical lens, TTL represents the overall optical length of the optical lens, FOV represents the maximum field of view angle of the optical lens, and CRA represents the principal ray incident angle at the maximum image height of the optical lens. Meeting the above conditions indicates that the optical lens provided by the embodiments of the present invention has at least a large field of view angle, can realize shooting of images in an ultra-wide range; has a small CRA, can well match the chip, and ensure good resolution quality; has the characteristics of miniaturization.

[0069] In some embodiments, the eight lenses in the optical lens can all adopt 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. Specifically, the first lens can adopt a glass lens, and the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens are all plastic lenses; adopting a glass-plastic hybrid structure can improve the thermal stability performance, effectively reduce costs, correct aberrations, reduce the volume, and provide an optical lens product with higher cost performance.

[0070] 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 the size of lenses, and better realizing miniaturization of lenses. More specifically, in the optical lens provided by the present invention, the first lens may be a spherical lens, and the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens may be aspherical lenses.

[0071] 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, G, and H are the fourth-order, sixth-order, eighth-order, tenth-order, twelfth-order, fourteenth-order, and sixteenth-order surface coefficients respectively.

[0072] 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.

[0073] Example 1 See also Figure 1 , shown is a schematic diagram of the structure of the optical lens 100 provided in Example 1 of the present invention, and the optical lens 100 includes, from the object side to the imaging surface S18 along the optical axis, a first lens L1, a second lens L2, a third lens L3, an aperture ST, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8 and a filter G1.

[0074] The first lens L1 has negative refractive power, its object side surface S1 is convex, and its image side surface S2 is concave; The second lens L2 has negative refractive power, its object-side surface S3 is concave, and its image-side surface S4 is concave; The third lens L3 has positive refractive power, its object-side surface S5 is convex, and its image-side surface S6 is convex; The fourth lens L4 has positive refractive power, its object-side surface S7 is convex, and its image-side surface is convex; The fifth lens L5 has negative refractive power, its object side surface is concave, and its image side surface S9 is concave; The fourth lens L4 and the fifth lens L5 form a cemented lens group with negative power, that is, the cemented surface between the image side surface of the fourth lens L4 and the object side surface of the fifth lens L5 is S8; The sixth lens L6 has positive refractive power, an object-side surface S10 thereof is convex, and an image-side surface S11 thereof is convex; The seventh lens L7 has negative refractive power, its object-side surface S12 is concave, and its image-side surface S13 is convex; The eighth lens L8 has positive refractive power, its object-side surface S14 is convex, and its image-side surface S15 is convex; The object side surface S16 and the image side surface S17 of the filter G1 are both planes; The imaging surface S18 is a plane.

[0075] The first lens L1 is a glass spherical lens; the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7 and the eighth lens L8 are all plastic aspherical lenses.

[0076] The relevant parameters of each lens in the optical lens 100 in Example 1 are shown in Table 1-1.

[0077] Table 1-1 The surface parameters of the aspheric lens of the optical lens 100 in Example 1 are shown in Table 1-2.

[0078] Table 1-2 In this embodiment, the F-Theta distortion curve, field curvature curve, axial aberration curve, and vertical chromatic aberration curve of the optical lens 100 are respectively as follows: Figure 2 , Figure 3 , Figure 4 and Figure 5 shown.

[0079] Figure 2 The F-Theta distortion curve of this embodiment is shown, which represents the distortion of different field angles on the imaging plane, with the horizontal axis representing the distortion value (unit: %) and the vertical axis representing the field angle (unit: °). It can be seen from the figure that the distortion value is controlled within ±4%, indicating that the optical lens 100 can correct the distortion well.

[0080] Figure 3The field curvature curve in this embodiment is shown, which represents the field curvature of light on the meridional image plane and the sagittal image plane, the horizontal axis represents the offset (unit: mm), and the vertical axis represents the field angle (unit: °). It can be seen from the figure that the field curvature of the meridional image plane and the sagittal image plane is controlled within ±0.05mm, indicating that the optical lens 100 can well correct the field curvature.

[0081] Figure 4 The axial aberration curve in this embodiment is shown, which represents the aberration of each wavelength on the optical axis at the imaging plane, the horizontal axis represents the axial aberration value (unit: mm), and the vertical axis represents the normalized pupil radius. As can be seen from the figure, the offset of the axial aberration is controlled within ±0.01mm, indicating that the optical lens 100 can better correct the axial aberration.

[0082] Figure 5 The vertical chromatic aberration curve in this embodiment is shown, which represents the chromatic aberration of each wavelength relative to the central wavelength (0.55 μm) at different image heights on the imaging surface, the horizontal axis represents the vertical 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 chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±3 μm, indicating that the optical lens 100 can well correct the vertical chromatic aberration.

[0083] Example 2 See also Figure 6 , which is a schematic diagram of the structure of the optical lens 200 provided in Example 2 of the present invention. Compared with Example 1, the main differences between this embodiment and Example 1 are: the image side surface S15 of the eighth lens L8 is a concave surface; the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0084] The relevant parameters of each lens in the optical lens 200 in Example 2 are shown in Table 2-1.

[0085] Table 2-1 The surface parameters of the aspheric lens of the optical lens 200 in Example 2 are shown in Table 2-2.

[0086] Table 2-2 In this embodiment, the F-Theta distortion curve, field curvature curve, axial aberration curve, and vertical axis chromatic aberration curve of the optical lens 200 are respectively as follows: Figure 7 , Figure 8 , Fig. 9 and Fig.10 shown.

[0087] from Figure 7It can be seen that the distortion value is controlled within ±5%, indicating that the optical lens 200 can correct the distortion well.

[0088] from Figure 8 It can be seen that the field curvature of the meridian image plane and the sagittal image plane is controlled within ±0.05mm, indicating that the optical lens 200 can correct the field curvature well.

[0089] from Fig. 9 It can be seen that the offset of the axial aberration is controlled within ±0.01 mm, indicating that the optical lens 200 can correct the axial aberration well.

[0090] from Fig.10 It can be seen that the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±4μm, indicating that the optical lens 200 can correct the vertical axis chromatic aberration well.

[0091] Example 3 See also Fig.11 , which 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 differences of this embodiment are: the image side surface S15 of the eighth lens L8 is a concave surface; the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0092] The relevant parameters of each lens in the optical lens 300 in Example 3 are shown in Table 3-1.

[0093] Table 3-1 The surface parameters of the aspheric lens of the optical lens 300 in Example 3 are shown in Table 3-2.

[0094] Table 3-2 In this embodiment, the F-Theta distortion curve, field curvature curve, axial aberration curve, and vertical axis chromatic aberration curve of the optical lens 300 are respectively as follows: Fig.12 , Fig.13 , Fig.14 and Figure 5 shown.

[0095] from Fig.12 It can be seen that the distortion value is controlled within ±4%, indicating that the optical lens 300 can correct the distortion well.

[0096] from Fig.13 It can be seen that the field curvature of the meridian image plane and the sagittal image plane is controlled within ±0.15 mm, indicating that the optical lens 300 can correct the field curvature well.

[0097] from Fig.14It can be seen that the offset of the axial aberration is controlled within ±0.01 mm, indicating that the optical lens 300 can correct the axial aberration well.

[0098] from Fig.15 It can be seen that the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±5μm, indicating that the optical lens 300 can correct the vertical axis chromatic aberration well.

[0099] Please refer to Table 4, which shows the optical characteristics corresponding to the above embodiments, including the effective focal length f of the optical lens, the total optical length TTL, the aperture value Fno, the real image height IH corresponding to the maximum field of view angle, the chief ray incident angle CRA at the maximum image height, the maximum field of view angle FOV, and the numerical value corresponding to each conditional expression in each embodiment.

[0100] Table 4 Compared with the prior art, the optical lens provided by the present invention has at least the following advantages: (1) The optical lens provided by the present invention adopts an eight-piece glass-plastic hybrid structure. Through a specific surface shape setting and a reasonable optical focal length distribution, the structure of the optical lens is relatively compact, and a large field of view of the lens can be achieved, thereby being able to obtain more scene information and meet the needs of large-scale detection of the optical lens.

[0101] (2) The optical lens provided by the present invention has a smaller CRA, which can be well matched with the chip to ensure good resolution quality; at the same time, it can also reasonably correct the overall aberration of the optical lens, so that the optical lens has high pixels while effectively shortening the overall length of the optical lens.

[0102] (3) The optical lens provided by the present invention adopts a glass-plastic hybrid structure, which not only makes the lens have good thermal stability, but also greatly reduces the production cost of the lens, reduces the size of the lens, and better realizes the miniaturization of the lens.

[0103] 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.

[0104] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. An optical lens, comprising eight lenses, characterized in that: It successively includes from the object side to the imaging surface along the optical axis: A first lens with a negative optical power, whose object side is convex and whose image side is concave; A second lens with a negative optical power, whose object side is concave and whose image side is concave; A third lens with a positive optical power, whose object side is convex and whose image side is convex; A fourth lens with a positive optical power, whose object side is convex and whose image side is convex; A fifth lens with a negative optical power, whose object side is concave and whose image side is concave; A sixth lens with a positive optical power, whose object side is convex and whose image side is convex; A seventh lens with a negative optical power, whose object side is concave and whose image side is convex; An eighth lens with a positive optical power, whose object side is convex; Wherein, 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: 2.2 < TTL / IH < 2.8; The combined focal length fa of the first lens, the second lens and the third lens and the combined focal length fb of the fourth lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens satisfy: 0.8 < fa / fb < 2.

2.

2. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -4 < f1 / f < -3; The curvature radius R1 of the object side of the first lens and the curvature radius R2 of the image side of the first lens satisfy: 3 < R1 / R2 < 4.

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

4. 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: 2 < f3 / f < 2.8; 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: -2 < R5 / R6 < -1.

2.

5. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens and the focal length f4 of the fourth lens satisfy: 1.3 < f4 / f < 1.8; The effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: -1.5 < f5 / f < -1.

6. 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: 2.1 < f6 / f < 2.

8.

7. 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: -13 < f7 / f < -8.5; The curvature radius R13 of the object side of the seventh lens, the curvature radius R14 of the image side of the seventh lens and the central thickness CT7 of the seventh lens satisfy: 0.85 < (R13 - CT7) / R14 < 1.

8. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens and the focal length f8 of the eighth lens satisfy: 4 < f8 / f < 6; The focal length f7 of the seventh lens and the focal length f8 of the eighth lens satisfy: -3 < f7 / f8 < -1.

5.

9. The optical lens according to claim 1, characterized in that: The curvature radius R3 of the object side of the second lens and the effective focal length f of the optical lens satisfy: -20 < R3 / f < -13; The curvature radius R4 of the image side of the second lens and the effective focal length f of the optical lens satisfy: 1 < R4 / f < 1.

6.

10. 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: 8.5 < TTL / f < 10; the effective focal length f of the optical lens and the true image height IH corresponding to the maximum field of view angle of the optical lens satisfy: 3.4 < IH / f < 3.

6.

11. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens and the combined focal length f45 of the fourth lens and the fifth lens satisfy: -25 < f45 / f < -15.

Images