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, both its object side surface and image side surface being concave; a second lens with a positive optical power, its object side surface being concave and its image side surface being convex; a third lens with a positive optical power, both its object side surface and image side surface being convex; a fourth lens with a negative optical power, its object side surface being concave. Wherein, the maximum field of view FOV of the optical lens and the aperture value Fno satisfy: 60° < FOV / Fno < 80°; 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: 0.1 < (R1 + R2) / (R1 - R2) < 1. The optical lens provided by the present invention can improve the imaging quality of the optical lens, reduce aberration, improve the imaging quality of the optical lens, and enable the lens to have one or more advantages such as a large aperture, a large field of view angle, and high 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 the medical field, medical imaging is an important auxiliary diagnostic tool. When combined with artificial intelligence, it can judge the development of a patient's condition, provide accurate and comprehensive diagnostic basis for doctors, help doctors formulate more effective treatment plans, thus better solving medical problems and improving the medical level.

[0003] As a key component in various medical imaging devices, an optical lens can help doctors obtain high-definition images of the internal body, thereby improving the accuracy and safety of diagnosis and treatment. Currently, the optical lenses in medical imaging devices have the problem of low imaging quality and cannot meet the market demand. 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 technical solution adopted by the present invention is as follows:

[0006] An optical lens, comprising a total of four lenses, which sequentially include from the object side to the imaging surface along the optical axis:

[0007] A first lens with a negative optical power, both its object side surface and image side surface are concave surfaces;

[0008] A second lens with a positive optical power, its object side surface is a concave surface, and its image side surface is a convex surface;

[0009] A third lens with a positive optical power, both its object side surface and image side surface are convex surfaces;

[0010] A fourth lens with a negative optical power, its object side surface is a concave surface;

[0011] Wherein, the maximum field of view FOV of the optical lens and the aperture value Fno satisfy: 60° < FOV / Fno < 80°; 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: 0.1 < (R1 + R2) / (R1 - R2) < 1.

[0012] Further preferably, the total optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 14 < TTL / f < 17; the total 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: 4.5 < TTL / IH < 5.5.

[0013] Further 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: 2.9 < IH / f < 3.6; the back focal length BFL of the optical lens and the effective focal length f of the optical lens satisfy: 2.4 < BFL / f < 2.7.

[0014] Further preferably, the focal length f4 of the fourth lens and the effective focal length f of the optical lens satisfy: -3.7 < f4 / f < -2.7; the curvature radius R7 of the object side surface of the fourth lens and the curvature radius R8 of the image side surface of the fourth lens satisfy: 0.3 < |R7 / R8| < 0.45.

[0015] Further preferably, the combined focal length f34 of the third lens and the fourth lens and the effective focal length f of the optical lens satisfy: 2.7 < f34 / f < 3.3.

[0016] Further preferably, the focal length f2 of the second lens and the focal length f3 of the third lens satisfy: 6 < f2 / f3 < 10; the distance CT23 between the second lens and the third lens on the optical axis and the central thickness CT3 of the third lens satisfy: 2.1 < CT23 / CT3 < 3.8.

[0017] Further preferably, the curvature radius R1 of the object side surface of the first lens and the effective focal length f of the optical lens satisfy: -110 < R1 / f < -4; the curvature radius R2 of the image side surface of the first lens and the effective focal length f of the optical lens satisfy: 1.5 < R2 / f < 3.2.

[0018] Further preferably, 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: -65 < R1 / R2 < -1.2; the curvature radius R1 of the object side surface of the first lens and the focal length f1 of the first lens satisfy: 1.3 < R1 / f1 < 36.

[0019] Further preferably, the sagittal height Sag1 of the object side surface clear aperture of the first lens and the object side surface clear aperture d1 of the first lens satisfy: -0.03 < Sag1 / d1 < 0; the sagittal height Sag2 of the image side surface clear aperture of the first lens and the image side surface clear aperture d2 of the first lens satisfy: 0.5 < Sag2 / d2 < 0.8.

[0020] Further preferably, the object side surface clear aperture d1 of the first lens and the image side surface clear aperture d4 of the second lens satisfy: 2 < d1 / d4 < 2.6; the object side surface clear aperture d5 of the third lens and the image side surface clear aperture d8 of the fourth lens satisfy: 0.7 < d5 / d8 < 1.2.

[0021] The optical lens provided by the present invention adopts four lenses with specific optical powers. Through specific surface shape matching and reasonable optical power distribution, the imaging quality of the optical lens can be improved, the aberration can be reduced, and the imaging quality of the optical lens can be improved, so that the lens has one or more advantages such as large aperture, large field of view, high imaging quality, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] 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:

[0023] Figure 1 Schematic diagram of the structure of the optical lens in Example 1 of the present invention.

[0024] Figure 2 It is a field curvature curve diagram of the optical lens in Example 1 of the present invention.

[0025] Figure 3 4 is a F-Tanθ distortion curve diagram of the optical lens in Example 1 of the present invention.

[0026] Figure 4 Graph showing the axial aberration of the optical lens in Example 1 of the present invention.

[0027] Figure 5 Graph showing the vertical axis chromatic aberration of the optical lens in Example 1 of the present invention.

[0028] Figure 6 This is the MTF curve diagram of the optical lens in Example 1 of the present invention.

[0029] Figure 7 Schematic diagram of the structure of the optical lens in Example 2 of the present invention.

[0030] Figure 8 4 is a field curvature curve diagram of the optical lens in Example 2 of the present invention.

[0031] Fig. 9 4 is a F-Tanθ distortion curve diagram of the optical lens in Example 2 of the present invention.

[0032] Fig.10 Graph showing the axial aberration of the optical lens in Embodiment 2 of the present invention.

[0033] Fig.11 Graph showing the vertical axis chromatic aberration of the optical lens in Example 2 of the present invention.

[0034] Fig.12 This is an MTF curve diagram of the optical lens in Example 2 of the present invention.

[0035] Fig.13 Schematic diagram of the structure of the optical lens in Example 3 of the present invention.

[0036] Fig.14 4 is a field curvature curve diagram of the optical lens in Example 3 of the present invention.

[0037] Fig.15 4 is a F-Tanθ distortion curve diagram of the optical lens in Example 3 of the present invention.

[0038] Fig.16 Graph showing the axial aberration of the optical lens in Embodiment 3 of the present invention.

[0039] Fig.17 Graph showing the vertical axis chromatic aberration of the optical lens in Example 3 of the present invention.

[0040] Fig.18 This is the MTF curve diagram of the optical lens in Example 3 of the present invention.

[0041] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] In some embodiments, the first lens may have negative power, and its object side surface and image side surface may both be concave. The second lens may have positive power, its object side surface may be concave, and its image side surface may be convex. The third lens may have positive power, and its object side surface and image side surface may both be convex. The fourth lens may have negative power, its object side surface may be concave, and its image side surface may be concave or convex.

[0051] In some embodiments, the optical lens may further include an aperture, which may be located between the second lens and the third lens. It is understandable that the aperture is used to limit the amount of light entering to change the brightness of the image. In addition, when the aperture is located between the second lens and the third lens, the aperture can reasonably distribute the functions of the first lens to the fourth lens. For example, the first lens and the second lens can be used to receive light to a greater extent, and the third lens and the fourth lens can be used to correct the aberration, which is conducive to balancing the structure of the entire optical system. In addition, when the aperture is located between the second lens and the third lens, it is convenient to correct the aperture aberration.

[0052] 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 interfering light and prevent the interfering light from reaching the imaging surface of the optical lens and affecting normal imaging.

[0053] In some embodiments, the maximum field of view angle FOV of the optical lens and the aperture value Fno satisfy: 60° < FOV / Fno < 80°. Meeting the above range defines that the optical lens has an appropriate field of view angle and aperture value, can collect light at large angles and obtain good imaging quality. More specifically: 64° < FOV / Fno < 78°.

[0054] 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: 0.1 < (R1 + R2) / (R1 - R2) < 1. Meeting the above range reasonably defines the shapes of the object side surface and the image side surface of the first lens, can control the first lens to have an appropriate surface type, and can effectively correct the aberration of the optical lens. More specifically: 0.14 < (R1 + R2) / (R1 - R2) < 0.98.

[0055] In some embodiments, the total optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 14 < TTL / f < 17; 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: 4.5 < TTL / IH < 5.5. Meeting the above conditions can achieve the large target surface imaging effect of the optical lens, improve the pixel point size under the same pixel, can improve the energy reception efficiency of the chip for the light collected by the lens, thereby achieving high-pixel imaging; at the same time, it can better achieve a reasonable balance between the total length of the lens and the large image surface. More specifically: 15.23 < TTL / f < 16.77; 4.76 < TTL / IH < 5.07.

[0056] In some embodiments, 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: 2.9 < IH / f < 3.6; the back focal length BFL of the optical lens and the effective focal length f of the optical lens satisfy: 2.4 < BFL / f < 2.7. Meeting the above conditions, by reasonably controlling the ratio of the image height and the focal length of the optical lens, both the wide-angle characteristic can be achieved to meet the large wide-angle shooting requirements, and the large image surface characteristic can be achieved to improve the imaging quality of the optical lens. And by setting the optical lens to have a relatively large optical back focal length, it is beneficial to reduce the interference between the lens and the imaging chip and improve the assembly yield. More specifically: 3.18 < IH / f < 3.33; 2.47 < BFL / f < 2.50.

[0057] In some embodiments, the focal length f4 of the fourth lens and the effective focal length f of the optical lens satisfy: -3.7 < f4 / f < -2.7; 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: 0.3 < |R7 / R8| < 0.45. Satisfying the above ranges defines an appropriate negative optical power for the fourth lens and the surface shape of the fourth lens, which is conducive to diverging light and improving the imaging quality of the optical lens. More specifically: -3.65 < f4 / f < -3; 0.34 < |R7 / R8| < 0.44.

[0058] In some embodiments, the combined focal length f34 of the third lens and the fourth lens and the effective focal length f of the optical lens satisfy: 2.7 < f34 / f < 3.3. Satisfying the above conditions enables the combination of the third lens and the fourth lens to act as an optical lens group with a reasonable positive optical power, balancing the aberration generated by the front-end optical lens group, and thus obtaining good imaging quality. More specifically: 2.96 < f34 / f < 3.1.

[0059] In some embodiments, the focal length f2 of the second lens and the focal length f3 of the third lens satisfy: 6 < f2 / f3 < 10; the distance CT23 between the second lens and the third lens on the optical axis and the central thickness CT3 of the third lens satisfy: 2.1 < CT23 / CT3 < 3.8. Satisfying the above conditions, by reasonably setting the relationship between the central thickness of the third lens and the air gap, the degree of light deflection can be effectively alleviated, the field curvature and distortion of the system can be effectively reduced, and the imaging quality can be improved. More specifically: 6.48 < f2 / f3 < 9.78; 2.35 < CT23 / CT3 < 3.38.

[0060] 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: -110 < R1 / f < -4; the radius of curvature R2 of the image side surface of the first lens and the effective focal length f of the optical lens satisfy: 1.5 < R2 / f < 3.2. Satisfying the above ranges, by reasonably setting the surface shape of the first lens, the incident and exit angles of the light entering the first lens can be made appropriate. More specifically: -104.18 < R1 / f < -4.06; 1.71 < R2 / f < 3.04.

[0061] 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: -65 < R1 / R2 < -1.2; the radius of curvature R1 of the object side surface of the first lens and the focal length f1 of the first lens satisfy: 1.3 < R1 / f1 < 36. Satisfying the above ranges, by reasonably setting the surface shape of the first lens, the spherical aberration and coma can be effectively reduced, and the clarity and sharpness of the imaging can be improved. More specifically: -60.02 < R1 / R2 < -1.33; 1.33 < R1 / f1 < 33.04.

[0062] In some embodiments, the sagittal height Sag1 of the light-passing semi-aperture of the object side of the first lens and the light-passing semi-aperture d1 of the object side of the first lens satisfy: -0.03 < Sag1 / d1 < 0; the sagittal height Sag2 of the light-passing semi-aperture of the image side of the first lens and the light-passing semi-aperture d2 of the image side of the first lens satisfy: 0.5 < Sag2 / d2 < 0.8. Meeting the above ranges helps to control the light path and highlight the detailed information of the central field of view of the optical lens. More specifically: 0.63 < Sag2 / d2 < 0.71.

[0063] In some embodiments, the light-passing semi-aperture d1 of the object side of the first lens and the light-passing semi-aperture d4 of the image side of the second lens satisfy: 2 < d1 / d4 < 2.6; the light-passing semi-aperture d5 of the object side of the third lens and the light-passing semi-aperture d8 of the image side of the fourth lens satisfy: 0.7 < d5 / d8 < 1.2. Meeting the above ranges helps to achieve a good light flux balance between different lenses, thereby improving the quality and stability of imaging. More specifically: 2.25 < d1 / d4 < 2.49; 0.76 < d5 / d8 < 1.08.

[0064] In some embodiments, the curvature radius R3 of the object side of the second lens and the effective focal length f of the optical lens satisfy: -8.3 < R3 / f < -5; the curvature radius R4 of the image side of the second lens and the effective focal length f of the optical lens satisfy: -4.9 < R4 / f < -3.9. Meeting the above ranges, by reasonably setting the surface shape of the second lens, the light passing through the second lens can be better focused, reducing aberration and distortion. More specifically: -7.54 < R3 / f < -5.11; -4.53 < R4 / f < -3.97.

[0065] In some embodiments, the curvature radius R5 of the object side of the third lens and the effective focal length f of the optical lens satisfy: 1.8 < R5 / f < 3.2; the curvature radius R6 of the image side of the third lens and the effective focal length f of the optical lens satisfy: -2 < R6 / f < -0.7. Meeting the above ranges, by reasonably setting the surface shape of the third lens, the imaging quality of the optical system can be improved, making the image more real and natural. More specifically: 1.87 < R5 / f < 3; -1.99 < R6 / f < -0.85.

[0066] In some embodiments, the curvature radius R7 of the object side of the fourth lens and the effective focal length f of the optical lens satisfy: -3.6 < R7 / f < -0.6. Meeting the above ranges, controlling the lens focal length and the object side of the fourth lens within a certain reasonable range helps to further balance the lens aberration and improve the imaging quality. More specifically: -3.38 < R7 / f < -0.76.

[0067] In some embodiments, the total optical length TTL of the optical lens and the sum ∑CT of the central thicknesses of the first lens to the fourth lens along the optical axis satisfy: 0.35 < ∑CT / TTL < 0.55. Satisfying the above range and controlling the total optical length of the optical lens and the sum of the central thicknesses of each lens within a reasonable range can facilitate the structural design and processing, and further improve the imaging quality. More specifically: 0.4 < ∑CT / TTL < 0.48.

[0068] In some embodiments, the distance CT23 between the second lens and the third lens on the optical axis and the distance CT12 between the first lens and the second lens on the optical axis satisfy: 1 < CT23 / CT12 < 1.8. Satisfying the above range can make the distance between each lens smaller, ensure the assembly yield, and minimize the thickness size of the lens to the greatest extent. More specifically: 1.03 < CT23 / CT12 < 1.62.

[0069] In some embodiments, the Abbe number V1 of the first lens and the Abbe number V2 of the second lens satisfy: 30 < V1 - V2 < 38. Satisfying the above range and controlling the Abbe number of the first lens and the Abbe number of the second lens within a reasonable range helps to balance the chromatic aberration of the optical system and improve the imaging clarity and color authenticity. More specifically: 31.77 < V1 - V2 < 35.33.

[0070] In some embodiments, the refractive index N1 of the first lens and the refractive index N2 of the second lens satisfy: 0.9 < N1 / N2 < 0.95. Satisfying the above range and controlling the refractive index of the first lens and the refractive index of the second lens within a reasonable range helps to reduce the difference in the degree of light deflection and control the propagation path of light.

[0071] In some embodiments, the focal length f1 of the first lens and the effective focal length f of the optical lens satisfy: -3.5 < f1 / f < -2.9; the focal length f2 of the second lens and the effective focal length f of the optical lens satisfy: 8.5 < f2 / f < 20.5; the focal length f3 of the third lens and the effective focal length f of the optical lens satisfy: 1.3 < f3 / f < 2.2. Satisfying the above range and reasonably controlling the proportion of the focal lengths of the first lens, the second lens, and the third lens helps the light power distribution of each lens and improves the imaging quality of the optical lens. More specifically: -3.16 < f1 / f < -3.03, 9.05 < f2 / f < 19.57, 1.39 < f3 / f < 2.01.

[0072] In some embodiments, the optical lens satisfies the following conditional expressions: 0.40 mm < f < 0.60 mm; 120° < FOV < 160°; 0.2 mm < EPD < 0.3 mm; 7.0 mm < TTL < 8.2 mm; 1.8 < Fno < 2.2; 1.30 mm < IH < 1.90 mm; 18° < CRA < 28°; 1.0 mm < BFL < 1.5 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 f-number 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 a large aperture, a large field of view angle, and high imaging quality. More specifically: 0.43 mm < f < 0.54 mm; 128° < FOV < 156°; 0.21 mm < EPD < 0.27 mm; 7.37 mm < TTL < 8.01 mm; 1.9 < Fno < 2.1; 1.44 mm < IH < 1.70 mm; 20.99° < CRA < 25.91°; 1.09 mm < BFL < 1.31 mm.

[0073] 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.

[0074] 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.

[0075] In various embodiments of the present invention, when the lens adopts an aspherical lens, the shapes of the aspherical surfaces of the optical lens satisfy the following equations:

[0076] ;

[0077] 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.

[0078] 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.

[0079] Example 1

[0080] 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, a second lens L2, an aperture ST, a third lens L3, a fourth lens L4 and a filter G1.

[0081] The first lens L1 has negative refractive power, and its object side surface S1 and image side surface S2 are both concave surfaces;

[0082] The second lens L2 has positive refractive power, its object-side surface S3 is concave, and its image-side surface S4 is convex;

[0083] The third lens L3 has positive refractive power, and its object-side surface S5 and image-side surface S6 are both convex;

[0084] The fourth lens L4 has negative refractive power, its object-side surface S7 is concave, and its image-side surface S8 is convex;

[0085] The object side surface S9 and the image side surface S10 of the filter G1 are both planes;

[0086] The imaging surface S11 is a plane.

[0087] The relevant parameters of each lens in the optical lens 100 in Example 1 are shown in Table 1-1.

[0088] Table 1-1

[0089]

[0090] The surface parameters of the aspheric lens of the optical lens 100 in Example 1 are shown in Table 1-2.

[0091] Table 1-2

[0092]

[0093] In this embodiment, the field curvature curve, F-Tanθ distortion curve, axial aberration curve, vertical axis chromatic aberration curve, and MTF curve of the optical lens 100 are respectively as follows: Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 shown.

[0094] 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 -0.04mm~0.10mm, indicating that the optical lens can correct the field curvature well.

[0095] Figure 3 The F-Tanθ distortion curve of Example 1 is shown, which represents the F-Tanθ distortion at different image heights on the imaging surface, the horizontal axis represents the F-Tanθ distortion value (unit: %), and the vertical axis represents the half field angle (unit: °). It can be seen from the figure that the F-Tanθ distortion of the optical lens 100 is controlled within -25% to 15%, indicating that the distortion of the optical lens 100 is well corrected.

[0096] 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 -0.03mm~0.01mm, indicating that the optical lens can correct the axial aberration well.

[0097] 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 (0.55 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 -0.5 μm~1 μm, indicating that the optical lens can extremely well correct the chromatic aberration of the edge field of view and the secondary spectrum of the entire image surface.

[0098] Figure 6The MTF (Modulation Transfer Function) curve of Example 1 is shown, which represents the imaging modulation degree of the lens at different spatial frequencies under each field of view, the horizontal axis represents the spatial frequency (unit: lp / mm), and the vertical axis represents the MTF value. It can be seen from the figure that the MTF value of this embodiment is above 0.5 in the entire field of view, and in the range of 0 to 160 lp / mm, the MTF curve decreases evenly and smoothly from the center to the edge of the field of view, and has good imaging quality and good detail resolution ability in both low-frequency and high-frequency conditions.

[0099] Example 2

[0100] See also Figure 7 , 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 image side surface of the fourth lens is a concave surface and the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0101] The relevant parameters of each lens in the optical lens 200 in Example 2 are shown in Table 2-1.

[0102] Table 2-1

[0103]

[0104] The surface parameters of the aspheric lens of the optical lens 200 in Example 2 are shown in Table 2-2.

[0105] Table 2-2

[0106]

[0107] In this embodiment, the field curvature curve, F-Tanθ distortion curve, axial aberration curve, vertical axis chromatic aberration curve, and MTF curve of the optical lens 200 are shown as follows: Figure 8 , Fig. 9 , Fig.10 , Fig.11 , Fig.12 shown.

[0108] from Figure 8 It can be seen that the field curvature of the meridian image plane and the sagittal image plane is controlled within -0.02mm~0.06mm, indicating that the optical lens 200 can correct the field curvature well.

[0109] from Fig. 9 It can be seen that the F-Tanθ distortion of the optical lens 200 is controlled within -70%~5%, indicating that the distortion of the optical lens 200 is well corrected.

[0110] from Fig.10It can be seen that the offset of the axial aberration is controlled within -0.01mm~0.03mm, which means that the optical lens 200 can correct the axial aberration well.

[0111] from Fig.11 It can be seen that the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within -1μm~1.5μm, which means that the optical lens 200 can perfectly correct the chromatic aberration of the edge field of view and the secondary spectrum of the entire image plane.

[0112] from Fig.12 It can be seen that the MTF value of this embodiment is above 0.5 in the whole field of view. In the range of 0 to 160 lp / mm, the MTF curve decreases evenly and smoothly from the center to the edge of the field of view, and has good imaging quality and good detail resolution capability in both low-frequency and high-frequency conditions.

[0113] Example 3

[0114] See also Fig.13 , shown is a schematic diagram of the structure of the optical lens 300 provided in Example 3 of the present invention. Compared with Example 1, the main difference between this embodiment and Example 1 is that the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0115] The relevant parameters of each lens in the optical lens 300 in Example 3 are shown in Table 3-1.

[0116] Table 3-1

[0117]

[0118] The surface parameters of the aspheric lens of the optical lens 300 in Example 3 are shown in Table 3-2.

[0119] Table 3-2

[0120]

[0121] In this embodiment, the field curvature curve, F-Tanθ distortion curve, axial aberration curve, vertical axis chromatic aberration curve, and MTF curve of the optical lens 300 are shown as follows: Fig.14 , Fig.15 , Fig.16 , Fig.17 , Fig.18 shown.

[0122] from Fig.14 It can be seen that the field curvature of the meridian image plane and the sagittal image plane is controlled within -0.02mm~0.04mm, indicating that the optical lens 300 can correct the field curvature well.

[0123] from Fig.15It can be seen that the F-Tanθ distortion of the optical lens 300 is controlled within -25%~10%, indicating that the distortion of the optical lens 300 is well corrected.

[0124] from Fig.16 It can be seen that the offset of the axial aberration is controlled within -0.02mm~0.01mm, which means that the optical lens 300 can correct the axial aberration well.

[0125] from Fig.17 It can be seen that the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within -0.25μm~1.75μm, which means that the optical lens 300 can perfectly correct the chromatic aberration of the edge field of view and the secondary spectrum of the entire image plane.

[0126] from Fig.18 It can be seen that the MTF value of this embodiment is above 0.55 in the whole field of view. In the range of 0 to 160 lp / mm, the MTF curve decreases evenly and smoothly from the center to the edge of the field of view, and has good imaging quality and good detail resolution capability in both low-frequency and high-frequency conditions.

[0127] 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.

[0128] Table 4-1

[0129]

[0130] Table 4-2

[0131]

[0132] In summary of the above embodiments, the optical lens provided by the present invention adopts four lenses with specific optical powers. Through specific surface shape matching and reasonable optical power distribution, it is possible to improve the imaging quality of the optical lens, reduce aberrations, and improve the imaging quality of the optical lens, so that the lens has one or more advantages such as large aperture, large field of view, and high imaging quality.

[0133] 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.

[0134] 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 four lenses, characterized in that: It sequentially includes from the object side to the imaging surface along the optical axis: A first lens with negative optical power, whose object side and image side are both concave surfaces; A second lens with positive optical power, whose object side is a concave surface and whose image side is a convex surface; A third lens with positive optical power, whose object side and image side are both convex surfaces; A fourth lens with negative optical power, whose object side is a concave surface; In the optical lens, the number of lenses with optical power is four; Among them, the maximum field of view angle FOV of the optical lens and the aperture value Fno satisfy: 60° < FOV / Fno < 80°; 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: 0.1 < (R1 + R2) / (R1 - R2) < 1; the total optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 14 < TTL / f < 17; 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: 4.5 < TTL / IH < 5.

5.

2. The optical lens according to claim 1, characterized in that: The total optical length TTL of the optical lens and the sum ∑CT of the central thicknesses of the first lens to the fourth lens along the optical axis respectively satisfy: 0.35 < ∑CT / TTL < 0.

55.

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: 2.9 < IH / f < 3.6; the back focal length BFL of the optical lens and the effective focal length f of the optical lens satisfy: 2.4 < BFL / f < 2.

7.

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: -3.7 < f4 / f < -2.7; 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: 0.3 < |R7 / R8| < 0.

45.

5. The optical lens according to claim 1, characterized in that: The combined focal length f34 of the third lens and the fourth lens and the effective focal length f of the optical lens satisfy: 2.7 < f34 / f < 3.

3.

6. The optical lens according to claim 1, characterized in that: The focal length f2 of the second lens and the focal length f3 of the third lens satisfy: 6 < f2 / f3 < 10; the distance CT23 between the second lens and the third lens on the optical axis and the central thickness CT3 of the third lens satisfy: 2.1 < CT23 / CT3 < 3.

8.

7. The optical lens according to claim 1, characterized in that: The curvature radius R1 of the object side of the first lens and the effective focal length f of the optical lens satisfy: -110 < R1 / f < -4; the curvature radius R2 of the image side of the first lens and the effective focal length f of the optical lens satisfy: 1.5 < R2 / f < 3.

2.

8. The optical lens according to claim 1, characterized in that: 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: -65 < R1 / R2 < -1.2; the curvature radius R1 of the object side of the first lens and the focal length f1 of the first lens satisfy: 1.3 < R1 / f1 < 36.

9. The optical lens according to claim 1, characterized in that: The sagittal height Sag1 of the light-passing semi-aperture on the object side of the first lens and the light-passing semi-aperture d1 on the object side of the first lens satisfy: -0.03 < Sag1 / d1 < 0; the sagittal height Sag2 of the light-passing semi-aperture on the image side of the first lens and the light-passing semi-aperture d2 on the image side of the first lens satisfy: 0.5 < Sag2 / d2 < 0.

8.

10. The optical lens according to claim 1, characterized in that: The light-passing semi-aperture d1 on the object side of the first lens and the light-passing semi-aperture d4 on the image side of the second lens satisfy: 2 < d1 / d4 < 2.6; the light-passing semi-aperture d5 on the object side of the third lens and the light-passing semi-aperture d8 on the image side of the fourth lens satisfy: 0.7 < d5 / d8 < 1.2.

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