Optical lens

Abstract

The present invention provides an optical lens, which has a total of four lenses. Along the optical axis from the object side to the imaging surface, it successively includes: a first lens with a negative optical power, the object side surface of which is concave near the optical axis and the image side surface of which is concave; a second lens with a positive optical power, the image side surface of which is convex; a third lens with a positive optical power, the object side surface of which is concave near the optical axis and the image side surface of which is convex; a fourth lens with an optical power, the object side surface of which is convex near the optical axis and the image side surface of which is concave near the optical axis; wherein, the maximum field of view FOV of the optical lens and the aperture value Fno satisfy: 130° < FOV / Fno < 150°; 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: 0.1 < (R5 - R6) / (R5 + R6) < 0.8. The optical lens provided by the present invention adopts four lenses with specific optical powers and specific surface types, so that the lens has one or more advantages such as large aperture, large field of view, small distortion, miniaturization, and high pixel.

Description

Technical Field

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

[0002] TOF, whose full name is "Time of Flight", is a technology for measuring the time of flight. TOF technology has a wide range of applications in multiple fields, including but not limited to 3D imaging, lidar, medical imaging, and wireless communication, etc. In 3D imaging, a TOF lens calculates the time difference between the emission and reflection of infrared light back to the camera, collects the data, and forms a set of distance-depth data to obtain a 3D model. TOF cameras can quickly capture the three-dimensional shape and depth information of objects and are widely used in fields such as gaming, virtual reality, augmented reality, and robot navigation. However, some TOF lenses on the market have too small an aperture, resulting in a dim recorded image; some have too small a field of view, making it difficult to record too many images; or they have a relatively large total length, increasing the volume of the lens. Summary of the Invention

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

[0004] The technical solution adopted by the present invention is as follows:

[0005] An optical lens, comprising a total of four lenses, which in sequence from the object side to the imaging surface along the optical axis include:

[0006] A first lens with a negative focal power, whose object side surface is concave near the optical axis and whose image side surface is concave;

[0007] A second lens with a positive focal power, whose image side surface is convex;

[0008] A third lens with a positive focal power, whose object side surface is concave near the optical axis and whose image side surface is convex;

[0009] A fourth lens with a focal power, whose object side surface is convex near the optical axis and whose image side surface is concave near the optical axis;

[0010] Wherein, the maximum field of view FOV of the optical lens and the aperture value Fno satisfy: 130° < FOV / Fno < 150°; 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: 0.1 < (R5 - R6) / (R5 + R6) < 0.8.

[0011] More preferably, the total optical length TTL of the optical lens and the true image height IH corresponding to the maximum field of view angle of the optical lens satisfy: 1.25 < TTL / IH < 1.7; 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: 3.1 < IH / EPD < 4.

[0012] 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: 2.6 < IH / f < 3.2; the sum ∑CT of the central thicknesses of the first lens to the fourth lens along the optical axis and the effective focal length f of the optical lens satisfy: 2 < ΣCT / f < 2.8.

[0013] More preferably, the focal length f4 of the fourth lens and the effective focal length f of the optical lens satisfy: |f4 / f| > 35; the curvature radius R7 of the object side of the fourth lens and the curvature radius R8 of the image side of the fourth lens satisfy: 1 < R7 / R8 < 1.3.

[0014] More preferably, the focal length f1 of the first lens and the combined focal length f234 of the second lens, the third lens and the fourth lens satisfy: -2 < f1 / f234 < -1.5.

[0015] More preferably, the focal length f1 of the first lens and the focal length f3 of the third lens satisfy: -1 < f1 / f3 < -0.7; the curvature radius R1 of the object side of the first lens and the curvature radius R5 of the object side of the third lens satisfy: 0.35 < R1 / R5 < 0.85.

[0016] More preferably, the curvature radius R1 of the object side of the first lens and the effective focal length f of the optical lens satisfy: -2 < R1 / f < -1.5; the curvature radius R5 of the object side of the third lens and the effective focal length f of the optical lens satisfy: -4.9 < R5 / f < -2.1.

[0017] More preferably, 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: -0.7 < (R1 + R2) / (R1 - R2) < -0.2.

[0018] More preferably, the curvature radius R7 of the object side of the fourth lens and the curvature radius R8 of the image side of the fourth lens satisfy: 10 < (R7 + R8) / (R7 - R8) < 19.3.

[0019] Further preferably, the sagittal height Sag1 of the light-passing semi-aperture of the object side surface of the first lens and the light-passing semi-aperture d1 of the object side surface of the first lens satisfy: 0 < Sag1 / d1 < 0.25; the light-passing semi-aperture d1 of the object side surface of the first lens and the light-passing semi-aperture d8 of the image side surface of the fourth lens satisfy: 0.95 < d1 / d8 < 1.2.

[0020] The optical lens provided by the present invention adopts four lenses with specific optical powers and specific surface shapes, so that the lens has one or more advantages such as large aperture, large field of view, small distortion, miniaturization, and high pixel. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, wherein:

[0022] Figure 1 is a schematic structural diagram of the optical lens in Embodiment 1 of the present invention.

[0023] Figure 2 is a field curvature curve graph of the optical lens in Embodiment 1 of the present invention.

[0024] Figure 3 is an F-Theta distortion curve graph of the optical lens in Embodiment 1 of the present invention.

[0025] Figure 4 is an axial aberration curve graph of the optical lens in Embodiment 1 of the present invention.

[0026] Figure 5 is a lateral chromatic aberration curve graph of the optical lens in Embodiment 1 of the present invention.

[0027] Figure 6 is a schematic structural diagram of the optical lens in Embodiment 2 of the present invention.

[0028] Figure 7 is a field curvature curve graph of the optical lens in Embodiment 2 of the present invention.

[0029] Figure 8 is an F-Theta distortion curve graph of the optical lens in Embodiment 2 of the present invention.

[0030] Fig. 9 is an axial aberration curve graph of the optical lens in Embodiment 2 of the present invention.

[0031] Fig.10 is a lateral chromatic aberration curve graph of the optical lens in Embodiment 2 of the present invention.

[0032] Fig.11 is a schematic structural diagram of the optical lens in Embodiment 3 of the present invention.

[0033] Fig.12 4 is a field curvature curve diagram of the optical lens in Example 3 of the present invention.

[0034] Fig.13 Graph showing the F-Theta distortion of the optical lens in Embodiment 3 of the present invention.

[0035] Fig.14 Graph showing the axial aberration of the optical lens in Embodiment 3 of the present invention.

[0036] Fig.15 Graph showing the vertical axis chromatic aberration of the optical lens in Example 3 of the present invention.

[0037] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] The optical lens provided by the embodiment of the present invention comprises four lenses, which are a first lens, a second lens, a third lens and a fourth lens in sequence from the object side to the imaging surface along the optical axis.

[0046] In some embodiments, the first lens may have negative power, its object side surface may be concave at the near optical axis, and its image side surface may be concave. The second lens may have positive power, its object side surface may be concave or convex at the near optical axis, and its image side surface may be convex. The third lens may have positive power, its object side surface may be concave at the near optical axis, and its image side surface may be convex. The fourth lens may have positive power or negative power, its object side surface may be convex at the near optical axis, and its image side surface may be concave at the near optical axis.

[0047] In some embodiments, the optical lens may further include an aperture, and the aperture may be located between the first lens and the second lens. It is understood that the aperture is used to limit the amount of incoming light to change the brightness of the image.

[0048] In some embodiments, the optical lens may further include a filter, which is disposed between the fourth lens and the imaging surface along the optical axis. The filter is used to filter out interference light to prevent the interference light from reaching the imaging surface of the optical lens and affecting normal imaging.

[0049] In some embodiments, the maximum field of view FOV of the optical lens and the aperture value Fno satisfy: 130° < FOV / Fno < 150°; 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: 0.1 < (R5 - R6) / (R5 + R6) < 0.8. Meeting the above ranges defines that the optical lens has a suitable field of view and aperture value, can collect light at large angles and obtain good imaging quality. Moreover, by reasonably defining the shapes of the object side surface and the image side surface of the third lens, it is possible to control the third lens to have an appropriate surface shape and effectively correct the aberration of the optical lens. More specifically: 133° < FOV / Fno < 138°; 0.35 < (R5 - R6) / (R5 + R6) < 0.58.

[0050] In some embodiments, the overall optical length TTL of the optical lens and the true image height IH corresponding to the maximum field of view of the optical lens satisfy: 1.25 < TTL / IH < 1.7; 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: 3.1 < IH / EPD < 4. Meeting the above ranges, by controlling the image height and the entrance pupil diameter within appropriate ranges, it helps to increase the width of the light beam incident on the optical lens, improve the image plane brightness, and at the same time can better achieve a reasonable balance between the overall length of the lens and the large image plane. More specifically: 1.41 < TTL / IH < 1.55; 3.51 < IH / EPD < 3.63.

[0051] 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: 2.6 < IH / f < 3.2; the sum ∑CT of the central thicknesses of the first lens to the fourth lens along the optical axis and the effective focal length f of the optical lens satisfy: 2 < ΣCT / f < 2.8. Meeting the above ranges, by reasonably controlling the ratio of the image height and the focal length of the optical lens, both the ultra-wide-angle characteristic can be achieved to meet the shooting requirements of a large wide angle, and the large image plane characteristic can be achieved to improve the imaging quality of the optical lens. Moreover, by controlling the effective focal length of the optical lens and the sum of the central thicknesses of each lens within a reasonable range, it is possible to facilitate the structural design and processing and further improve the imaging quality. More specifically: 2.86 < IH / f < 2.94; 2.3 < ΣCT / f < 2.58.

[0052] In some embodiments, the focal length f4 of the fourth lens and the effective focal length f of the optical lens satisfy: |f4 / f| > 35; the radius of curvature R7 of the object side surface of the fourth lens and the radius of curvature R8 of the image side surface of the fourth lens satisfy: 1 < R7 / R8 < 1.3. Satisfying the above ranges, by reasonably defining the focal length ratio of the fourth lens and the shapes of the object side surface and the image side surface of the fourth lens, it is beneficial for more light beams to be effectively transmitted to the imaging surface, thereby improving the imaging quality. More specifically: 35 < |f4 / f| < 75; 1.11 < R7 / R8 < 1.21.

[0053] In some embodiments, the focal length f1 of the first lens and the combined focal length f234 of the second, third, and fourth lenses satisfy: -2 < f1 / f234 < -1.5. Satisfying the above range, by defining the focal length ratio of the lens groups before and after the aperture of the optical lens, the aberration generated by the lens groups before and after the aperture can be effectively corrected, and the imaging quality of the optical lens can be improved. More specifically: -1.85 < f1 / f234 < -1.65.

[0054] In some embodiments, the focal length f1 of the first lens and the focal length f3 of the third lens satisfy: -1 < f1 / f3 < -0.7; the radius of curvature R1 of the object side surface of the first lens and the radius of curvature R5 of the object side surface of the third lens satisfy: 0.35 < R1 / R5 < 0.85. Satisfying the above ranges, by reasonably defining the focal length ratio of the first lens and the third lens and the shapes of the object side surfaces of the first lens and the third lens, it is beneficial for light convergence and improves the imaging brightness. More specifically: -0.89 < f1 / f3 < -0.79; 0.37 < R1 / R5 < 0.78.

[0055] In some embodiments, the radius of curvature R1 of the object side surface of the first lens and the effective focal length f of the optical lens satisfy: -2 < R1 / f < -1.5; the radius of curvature R5 of the object side surface of the third lens and the effective focal length f of the optical lens satisfy: -4.9 < R5 / f < -2.1. Satisfying the above ranges, by reasonably defining the shapes of the object side surfaces of the first lens and the third lens, it is beneficial for correcting the spherical aberration of the optical lens. More specifically: -1.79 < R1 / f < -1.7; -4.45 < R5 / f < -2.3.

[0056] In some embodiments, the radius of curvature R1 of the object side surface of the first lens and the radius of curvature R2 of the image side surface of the first lens satisfy: -0.7 < (R1 + R2) / (R1 - R2) < -0.2. Satisfying the above conditions, by reasonably defining the shapes of the object side surface and the image side surface of the first lens, the first lens can have an appropriate surface shape, which helps the incident light to converge, reduces the aperture of the front lens, and thus realizes the miniaturization of the head. More specifically: -0.51 < (R1 + R2) / (R1 - R2) < -0.42.

[0057] In some embodiments, the radius of curvature R7 of the object side surface of the fourth lens and the radius of curvature R8 of the image side surface of the fourth lens satisfy: 10 < (R7 + R8) / (R7 - R8) < 19.3. By satisfying the above range and controlling the shapes of the object side surface and the image side surface of the fourth lens, the fourth lens can have an appropriate surface shape, effectively improving the field curvature and aberration and enhancing the imaging quality. More specifically: 11.17 < (R7 + R8) / (R7 - R8) < 17.58.

[0058] In some embodiments, the sagittal height Sag1 of the clear aperture of the object side surface of the first lens and the clear aperture d1 of the object side surface of the first lens satisfy: 0 < Sag1 / d1 < 0.25; the clear aperture d1 of the object side surface of the first lens and the clear aperture d8 of the image side surface of the fourth lens satisfy: 0.95 < d1 / d8 < 1.2. By satisfying the above range, it helps to control the light ray trend, highlight the detailed information of the central field of view of the optical lens, and at the same time achieve a good light flux balance between different lenses, thereby improving the quality and stability of imaging. More specifically: 0.08 < Sag1 / d1 < 0.16; 1.04 < d1 / d8 < 1.11.

[0059] In some embodiments, the overall optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 3.6 < TTL / f < 5. By satisfying the above range, the length of the lens can be effectively limited, which is beneficial to reducing the volume of the optical lens. More specifically: 4.06 < TTL / f < 4.54.

[0060] In some embodiments, the back focal length BFL of the optical lens and the effective focal length f of the optical lens satisfy: 0.95 < BFL / f < 1.25. By satisfying the above range, it is beneficial to reducing the volume of the optical lens and reducing the interference between the lens and the imaging chip, and improving the assembly yield. More specifically: 1.06 < BFL / f < 1.12.

[0061] In some embodiments, the focal length f1 of the first lens and the effective focal length f of the optical lens satisfy: -2.3 < f1 / f < -1.8; the radius of curvature R1 of the object side surface of the first lens and the radius of curvature R2 of the image side surface of the first lens satisfy: -0.45 < R1 / R2 < -0.3. By satisfying the above range, by reasonably defining the proportion of the focal length of the first lens and the shapes of the object side surface and the image side surface of the first lens, it is beneficial to collect light rays with a large field of view angle and increase the field of view angle of the optical lens. More specifically: -2.12 < f1 / f < -2.01; -0.4 < R1 / R2 < -0.33.

[0062] In some embodiments, the focal length f2 of the second lens and the effective focal length f of the optical lens satisfy: 1.5 < f2 / f < 2.1; 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: R3 / R4 > -30. Meeting the above ranges, by reasonably defining the proportion of the focal length of the second lens and the shapes of the object side surface and the image side surface of the second lens, the difficulty of correcting aberrations by subsequent lenses can be effectively reduced. More specifically: 1.63 < f2 / f < 1.9; -30 < R3 / R4 < -14.64.

[0063] In some embodiments, the focal length f3 of the third lens and the effective focal length f of the optical lens satisfy: 2.2 < f3 / f < 2.8; 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: 1.9 < R5 / R6 < 4. Meeting the above ranges, by reasonably defining the proportion of the focal length of the third lens and the shapes of the object side surface and the image side surface of the third lens, it helps with the distribution of the optical power and improves the imaging quality of the optical lens. More specifically: 2.39 < f3 / f < 2.54; 2.12 < R5 / R6 < 3.64.

[0064] 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: R3 / f < 33. Meeting the above range, by reasonably defining the shape of the object side surface of the second lens, the field curvature of the lens can be improved and the difficulty of optimizing lens aberrations can be reduced. More specifically: 18.02 < R3 / f < 30.7.

[0065] In some embodiments, the radius of curvature R7 of the object side surface of the fourth lens and the effective focal length f of the optical lens satisfy: 0.95 < R7 / f < 1.25; the radius of curvature R8 of the image side surface of the fourth lens and the effective focal length f of the optical lens satisfy: 0.8 < R8 / f < 1.1. Meeting the above ranges, by reasonably defining the shapes of the object side surface and the image side surface of the fourth lens, it helps to control distortion and improve the resolution of the optical lens. More specifically: 1.04 < R7 / f < 1.15; 0.87 < R8 / f < 0.99.

[0066] 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) < 1.1. Meeting the above range, by reasonably defining the shapes of the object side surface and the image side surface of the second lens, the second lens can be controlled to have an appropriate surface shape, and the aberrations of the optical lens can be effectively corrected. More specifically: 0.86 < (R3 + R4) / (R3 - R4) < 1.01.

[0067] In some embodiments, the optical lens satisfies the following conditional expressions: 0.8 mm < f < 1.1 mm; 150° < FOV < 180°; 0.7 mm < EPD < 0.9 mm; 3.6 mm < TTL < 4.8 mm; 1.05 < Fno < 1.35; 2.6 mm < IH < 3.1 mm; 15.5° < CRA < 22.8°; 0.9 mm < BFL < 1.2 mm. In the above conditional expressions, f represents the effective focal length of the optical lens, FOV represents the maximum field of view angle of the optical lens, EPD represents the entrance pupil diameter of the optical lens, TTL represents the total 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, CRA represents the principal ray incident angle at the maximum image height of the optical lens, and BFL represents the back focal length of the optical lens. Meeting the above ranges, the optical lens has at least one or more advantages such as ultra-wide angle, large aperture, and short total length. More specifically: 0.96 mm < f < 1 mm; 164° < FOV < 167°; 0.78 mm < EPD < 0.82 mm; 4.02 mm < TTL < 4.41 mm; 1.19 < Fno < 1.25; 2.8 mm < IH < 2.9 mm; 17.06° < CRA < 20.84°; 1.03 mm < BFL < 1.1 mm.

[0068] In some embodiments, the lens material in the optical lens provided by the present invention can be glass or plastic. When the lens material is plastic, the production cost can be effectively reduced. Additionally, when the lens material is glass, the geometric chromatic aberration of the optical system can be effectively corrected by the low dispersion characteristic of the glass itself. The optical lens provided by the present invention can adopt an all-plastic lens structure, which can make the structure of the lens relatively compact, can better achieve the balance of high image quality of the lens, and reduce costs.

[0069] In some embodiments, the first lens, the second lens, the third lens, and the fourth 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. More specifically, the first lens, the second lens, the third lens, and the fourth lens of the present invention all adopt aspherical lenses.

[0070] In each embodiment of the present invention, when the lens adopts an aspherical lens, the shapes of the aspherical surfaces of the optical lens satisfy the following equations:

[0071] ;

[0072] 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.

[0073] 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.

[0074] Example 1

[0075] See also Figure 1 , shown is a schematic diagram of the structure of the optical lens 100 provided in Example 1 of the present invention, and the optical lens 100 includes, along the optical axis from the object side to the imaging surface, a first lens L1, an aperture ST, a second lens L2, a third lens L3, a fourth lens L4 and a filter G1.

[0076] The first lens L1 has negative refractive power, its object side surface S1 is concave at the near optical axis, and its image side surface S2 is concave;

[0077] The second lens L2 has positive refractive power, its object side surface S3 is convex at the near optical axis, and its image side surface S4 is convex;

[0078] The third lens L3 has positive refractive power, its object side surface S5 is concave at the near optical axis, and its image side surface S6 is convex;

[0079] The fourth lens L4 has positive refractive power, an object-side surface S7 thereof is convex at the near optical axis, and an image-side surface S8 thereof is concave at the near optical axis;

[0080] The object side surface S9 and the image side surface S10 of the filter G1 are both planes;

[0081] The imaging surface S11 is a plane.

[0082] The relevant parameters of each lens in the optical lens 100 in Example 1 are shown in Table 1-1.

[0083] Table 1-1

[0084]

[0085] The surface parameters of the aspheric lens of the optical lens 100 in Example 1 are shown in Table 1-2.

[0086] Table 1-2

[0087]

[0088] In this embodiment, the field curvature curve, F-Theta distortion curve, axial aberration curve, and vertical axis chromatic aberration curve of the optical lens 100 are respectively as follows: Figure 2 , Figure 3 , Figure 4 , Figure 5 shown.

[0089] Figure 2 The field curvature curve of Example 1 is shown, which indicates the degree of curvature of light of different wavelengths on the meridional image plane and the sagittal image plane, with the horizontal axis indicating the offset (unit: mm) and the vertical axis indicating the half field angle (unit: °). It can be seen from the figure that the field curvature of the meridional image plane and the sagittal image plane is controlled within ±0.1 mm, indicating that the optical lens can correct the field curvature well.

[0090] Figure 3 The F-Theta distortion curve of Example 1 is shown, which represents the F-Theta distortion at different image heights on the imaging plane, the horizontal axis represents the F-Theta distortion value (unit: %), and the vertical axis represents the half field angle (unit: °). It can be seen from the figure that the F-Theta distortion of the optical lens 100 is controlled within 0% to 6%, indicating that the distortion of the optical lens 100 is well corrected.

[0091] Figure 4 The axial aberration curve of Example 1 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. It can be seen from the figure that the offset of the axial aberration is controlled within -0.06mm~0.02mm, indicating that the optical lens can correct the axial aberration well.

[0092] Figure 5 The vertical chromatic aberration curve of Example 1 is shown, which represents the chromatic aberration of each wavelength relative to the central wavelength (0.94 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 ±2 μm, indicating that the optical lens can perfectly correct the chromatic aberration of the edge field of view and the secondary spectrum of the entire image surface.

[0093] Example 2

[0094] See also Figure 6, 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 differences between this embodiment and Example 1 are that the optical focal length of the fourth lens is negative and the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0095] The relevant parameters of each lens in the optical lens 200 in Example 2 are shown in Table 2-1.

[0096] Table 2-1

[0097]

[0098] The surface parameters of the aspheric lens of the optical lens 200 in Example 2 are shown in Table 2-2.

[0099] Table 2-2

[0100]

[0101] In this embodiment, the field curvature curve, F-Theta distortion 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 , Fig.10 shown.

[0102] from Figure 7 It can be seen that the field curvature of the meridian image plane and the sagittal image plane is controlled within -0.1mm~0.15mm, indicating that the optical lens 200 can correct the field curvature well.

[0103] from Figure 8 It can be seen that the F-Theta distortion of the optical lens 200 is controlled within 0%~6%, indicating that the distortion of the optical lens 200 is well corrected.

[0104] from Fig. 9 It can be seen that the offset of the axial aberration is controlled within -0.02mm~0.03mm, which means that the optical lens 200 can correct the axial aberration well.

[0105] from Fig.10 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 extremely well correct the chromatic aberration of the edge field of view and the secondary spectrum of the entire image plane.

[0106] Example 3

[0107] See also Fig.11, shown is a schematic diagram of the structure of the optical lens 300 provided in Example 3 of the present invention. Compared with Example 1, the main differences of this embodiment are: the object side surface of the second lens is concave at the near optical axis, the optical power of the fourth lens is negative, and the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0108] The relevant parameters of each lens in the optical lens 300 in Example 3 are shown in Table 3-1.

[0109] Table 3-1

[0110]

[0111] The surface parameters of the aspheric lens of the optical lens 300 in Example 3 are shown in Table 3-2.

[0112] Table 3-2

[0113]

[0114] In this embodiment, the field curvature curve, F-Theta distortion curve, axial aberration curve, and vertical chromatic aberration curve of the optical lens 300 are respectively as follows: Fig.12 , Fig.13 , Fig.14 , Fig.15 shown.

[0115] from Fig.12 It can be seen that the field curvature of the meridian image plane and the sagittal image plane is controlled within -0.05mm~0.2mm, indicating that the optical lens 300 can correct the field curvature well.

[0116] from Fig.13 It can be seen that the F-Theta distortion of the optical lens 300 is controlled within 0%~4%, indicating that the distortion of the optical lens 300 is well corrected.

[0117] from Fig.14 It can be seen that the offset of the axial aberration is controlled within -0.04mm~0.03mm, which means that the optical lens 300 can correct the axial aberration well.

[0118] from Fig.15 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 extremely well correct the chromatic aberration of the edge field of view and the secondary spectrum of the entire image plane.

[0119] 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 maximum field of view FOV, the entrance pupil diameter EPD, the total optical length TTL, the aperture value Fno, the real image height IH corresponding to the maximum field of view angle, the main light incident angle CRA, the back focal length BFL and the numerical value corresponding to each conditional expression in each embodiment.

[0120] Table 4-1

[0121]

[0122] Table 4-2

[0123]

[0124] In summary of the above embodiments, the optical lens provided by the present invention uses four lenses with specific optical power and specific surface shape, so that the lens has one or more advantages such as large aperture, large field of view, small distortion, miniaturization, high pixel, etc.

[0125] 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.

[0126] 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, characterized in that: It sequentially includes from the object side to the imaging plane along the optical axis: A first lens with a negative optical power, whose object side is concave near the optical axis and whose image side is concave; A second lens with a positive optical power, whose image side is convex; A third lens with a positive optical power, whose object side is concave near the optical axis and whose image side is convex; A fourth lens with an optical power, whose object side is convex near the optical axis and whose image side is concave near the optical axis; Among them, in the optical lens, the number of lenses with optical power is four; the maximum field of view angle FOV of the optical lens and the aperture value Fno satisfy: 130° < FOV / Fno < 150°; the object side curvature radius R5 of the third lens and the image side curvature radius R6 of the third lens satisfy: 0.1 < (R5 - R6) / (R5 + R6) < 0.8; the focal length f1 of the first lens and the combined focal length f234 of the second lens, the third lens and the fourth lens satisfy: -2 < f1 / f234 < -1.

5.

2. The optical lens according to claim 1, characterized in that: The overall optical length TTL of the optical lens and the true image height IH corresponding to the maximum field of view angle of the optical lens satisfy: 1.25 < TTL / IH < 1.7; 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: 3.1 < IH / EPD < 4.

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 effective focal length f of the optical lens satisfy: 2.6 < IH / f < 3.2; the sum ∑CT of the central thicknesses of the first lens to the fourth lens along the optical axis respectively and the effective focal length f of the optical lens satisfy: 2 < ΣCT / f < 2.

8.

4. The optical lens according to claim 1, characterized in that: The focal length f4 of the fourth lens and the effective focal length f of the optical lens satisfy: |f4 / f| > 35; the object side curvature radius R7 of the fourth lens and the image side curvature radius R8 of the fourth lens satisfy: 1 < R7 / R8 < 1.

3.

5. The optical lens according to claim 1, characterized in that: The maximum field of view angle FOV of the optical lens and the aperture value Fno satisfy: 133° < FOV / Fno < 138°; the object side curvature radius R5 of the third lens and the image side curvature radius R6 of the third lens satisfy: 0.35 < (R5 - R6) / (R5 + R6) < 0.58; the focal length f1 of the first lens and the combined focal length f234 of the second lens, the third lens and the fourth lens satisfy: -1.85 < f1 / f234 < -1.

65.

6. The optical lens according to claim 1, characterized in that: The focal length f1 of the first lens and the focal length f3 of the third lens satisfy: -1 < f1 / f3 < -0.7; the object side curvature radius R1 of the first lens and the object side curvature radius R5 of the third lens satisfy: 0.35 < R1 / R5 < 0.

85.

7. The optical lens according to claim 1, characterized in that: The object side curvature radius R1 of the first lens and the effective focal length f of the optical lens satisfy: -2 < R1 / f < -1.5; the object side curvature radius R5 of the third lens and the effective focal length f of the optical lens satisfy: -4.9 < R5 / f < -2.

1.

8. The optical lens according to claim 1, characterized in that: The radius of curvature R1 of the object side surface of the first lens and the radius of curvature R2 of the image side surface of the first lens satisfy: -0.7 < (R1 + R2) / (R1 - R2) < -0.

2.

9. The optical lens according to claim 1, characterized in that: The radius of curvature R7 of the object side surface of the fourth lens and the radius of curvature R8 of the image side surface of the fourth lens satisfy: 10 < (R7 + R8) / (R7 - R8) < 19.

3.

10. The optical lens according to claim 1, characterized in that: The sagittal height Sag1 of the clear aperture semi-diameter of the object side surface of the first lens and the clear aperture semi-diameter d1 of the object side surface of the first lens satisfy: 0 < Sag1 / d1 < 0.25; the clear aperture semi-diameter d1 of the object side surface of the first lens and the clear aperture semi-diameter d8 of the image side surface of the fourth lens satisfy: 0.95 < d1 / d8 < 1.2.

Images