Optical lens

Abstract

The invention provides an optical lens which comprises five lenses, and the five lenses sequentially comprise a first lens with positive focal power, a second lens with negative focal power, a third lens with positive focal power, a fourth lens with negative focal power, a fifth lens with positive focal power and a sixth lens with negative focal power from an object side to an imaging surface along an optical axis, the second lens has focal power; the third lens has positive focal power, and the image side surface of the third lens is a convex surface; the object side surface of the fourth lens is a concave surface, and the image side surface of the fourth lens is a concave surface; the object side surface of the fifth lens is a convex surface, and the image side surface of the fifth lens is a plane or a concave surface; wherein the maximum field angle FOV of the optical lens and the aperture value Fno of the optical lens meet the following conditions: 1.35 degree lt; an FOV / Fnot; 1.75 DEG C; the back focal length BFL of the optical lens and the total optical length TTL of the optical lens meet the following conditions: 0.4 lt; bFL / TTLlt; and 0.6. According to the optical lens provided by the invention, through specific surface shape matching and reasonable focal power distribution, the imaging quality of the optical lens can be improved, the aberration can be reduced, and the imaging quality of the optical lens can be improved.

Description

Technical Field

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

[0002] A gun sight is a special tool used for hunting or shooting sports competitions. The application environment is complex and it needs to have strong environmental adaptability. In a highly competitive situation, ordinary lenses can no longer meet the requirements, and it is often necessary to install a sighting lens on a firearm. The shooting environment also occurs at night or in areas with relatively dim light. At present, many gun sight lenses are blurred in an environment with poor light conditions. Moreover, most lenses can image the aimed object well at close range, but the imaging of distant targets is poor, and it is impossible to balance high-pixel long-distance imaging. When aiming at distant objects, the problem of not being able to highlight the main body will occur. Summary of the Invention

[0003] In view of 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 includes five lenses, which are sequentially arranged from the object side to the imaging surface along the optical axis:

[0006] A first lens with positive optical power, whose object side is convex and whose image side is flat;

[0007] A second lens with optical power;

[0008] A third lens with positive optical power, whose image side is convex;

[0009] A fourth lens with negative optical power, whose object side is concave and whose image side is concave;

[0010] A fifth lens with positive optical power, whose object side is convex and whose image side is flat or concave;

[0011] Wherein, the maximum field of view FOV of the optical lens and the aperture value Fno of the optical lens satisfy: 1.35° < FOV / Fno < 1.75°; the back focal length BFL of the optical lens and the total optical length TTL of the optical lens satisfy: 0.4 < BFL / TTL < 0.6; the image side curvature radius R8 of the fourth lens and the object side curvature radius R9 of the fifth lens satisfy: -0.4 < (R8 - R9) / (R8 + R9) ≤ 0.

[0012] More preferably, the effective focal length f of the optical lens satisfies: 80 mm < f < 100 mm; the chief ray angle of incidence CRA at the maximum image height of the optical lens satisfies: 2.7° < CRA < 5.5°.

[0013] More preferably, the total optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 1 < TTL / f < 1.35; 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: 7.1 < TTL / IH < 11.1.

[0014] More preferably, 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: 0.55 < IH / EPD < 0.7; the total optical length TTL of the optical lens, the true image height IH corresponding to the maximum field of view angle of the optical lens and the maximum field of view angle FOV of the optical lens satisfy: 3.7 / ° < TTL / IH / FOV < 6 / °.

[0015] More preferably, the effective focal length f of the optical lens and the focal length f4 of the fourth lens satisfy: -0.3 < f4 / f < -0.1; the object-side curvature radius R7 of the fourth lens and the image-side curvature radius R8 of the fourth lens satisfy: 0 < (R7 + R8) / (R7 - R8) < 0.8.

[0016] More preferably, the effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: 0.2 < f5 / f < 0.5; the effective focal length f of the optical lens and the object-side curvature radius R9 of the fifth lens satisfy: 0.15 < R9 / f < 0.35.

[0017] More preferably, the combined focal length f123 of the first lens, the second lens and the third lens and the combined focal length f45 of the fourth lens and the fifth lens satisfy: -1 < f123 / f45 < -0.6; the object-side clear aperture semi-diameter d1 of the first lens and the image-side clear aperture semi-diameter d10 of the fifth lens satisfy: 1.15 < d1 / d10 < 1.8.

[0018] More preferably, the focal length f3 of the third lens and the focal length f4 of the fourth lens satisfy: -10.6 < f3 / f4 < -1.5; the image-side curvature radius R6 of the third lens and the image-side curvature radius R8 of the fourth lens satisfy: -4.2 < R6 / R8 < -2.1.

[0019] More preferably, the focal length f4 of the fourth lens and the focal length f5 of the fifth lens satisfy: -0.75 < f4 / f5 < -0.4; the image-side curvature radius R8 of the fourth lens and the object-side curvature radius R9 of the fifth lens satisfy: 0.7 < R8 / R9 < 1.1.

[0020] More preferably, the focal length f2 of the second lens and the object-side curvature radius R3 of the second lens satisfy: 0.2 < f2 / R3 < 0.6; the focal length f2 of the second lens and the image-side curvature radius R4 of the second lens satisfy: -1.2 < f2 / R4 < -0.8.

[0021] More preferably, the object-side curvature radius R7 of the fourth lens and the image-side curvature radius R8 of the fourth lens satisfy: -4.5 < R7 / R8 < -1; the object-side curvature radius R7 of the fourth lens, the central thickness CT4 of the fourth lens and the image-side curvature radius R8 of the fourth lens satisfy: -4.8 < (R7 - CT4) / R8 < -1.35.

[0022] Compared with the prior art, the optical lens provided by the present invention has a high relative illumination through specific surface shape settings and reasonable optical power distribution. The object side of the first lens is convex, which helps to converge the incident light, reduces the aperture of the front lens, and is beneficial to the miniaturization of the front part. At the same time, the lens has a long focal length characteristic, which can better present larger local details, making the picture more concentrated and compact. It can improve the imaging quality of the optical lens, reduce aberration, and improve the imaging quality of the optical lens. Description of the Drawings

[0023] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the following description of the embodiments in conjunction with the accompanying drawings, where:

[0024] Figure 1 It is a schematic structural diagram of the optical lens in Embodiment 1 of the present invention.

[0025] Figure 2 It is a graph of F-Tan(Theta) distortion of the optical lens in Embodiment 1 of the present invention.

[0026] Figure 3 It is an axial aberration graph of the optical lens in Embodiment 1 of the present invention.

[0027] Figure 4 It is a graph of lateral chromatic aberration of the optical lens in Embodiment 1 of the present invention.

[0028] Figure 5 It is an MTF graph of the optical lens in Embodiment 1 of the present invention.

[0029] Figure 6 This is a relative illumination curve diagram of the optical lens in Example 1 of the present invention.

[0030] Figure 7 Schematic diagram of the structure of the optical lens in Example 2 of the present invention.

[0031] Figure 8 Graph showing the F-Tan (Theta) distortion of the optical lens in Example 2 of the present invention.

[0032] Fig. 9 Graph showing the axial aberration of the optical lens in Embodiment 2 of the present invention.

[0033] Fig.10 Graph showing the vertical axis chromatic aberration of the optical lens in Example 2 of the present invention.

[0034] Fig.11 This is an MTF curve diagram of the optical lens in Example 2 of the present invention.

[0035] Fig.12 This is a relative illumination curve diagram of the optical lens in Example 2 of the present invention.

[0036] Fig.13 Schematic diagram of the structure of the optical lens in Example 3 of the present invention.

[0037] Fig.14 Graph showing the F-Tan (Theta) distortion of the optical lens in Example 3 of the present invention.

[0038] Fig.15 Graph showing the axial aberration of the optical lens in Embodiment 3 of the present invention.

[0039] Fig.16 Graph showing the vertical axis chromatic aberration of the optical lens in Example 3 of the present invention.

[0040] Fig.17 This is the MTF curve diagram of the optical lens in Example 3 of the present invention.

[0041] Fig.18 This is a relative illumination curve diagram of the optical lens in Example 3 of the present invention.

[0042] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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.

[0049] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments 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.

[0050] The optical lens provided by the embodiment of the present invention includes five lenses, which are, 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, and a fifth lens.

[0051] In some embodiments, the first lens may have a positive optical power, its object side is a convex surface, and its image side is a flat surface. The second lens may have a positive optical power or a negative optical power, its object side may be a concave surface or a convex surface, and its image side may be a concave surface or a convex surface. The third lens may have a positive optical power, its object side may be a concave surface or a convex surface, and its image side is a convex surface. The fourth lens may have a negative optical power, its object side is a concave surface, and its image side is a concave surface. The fifth lens may have a positive optical power, its object side is a convex surface, and its image side is a flat surface or a concave surface.

[0052] In some embodiments, the optical lens may further include a diaphragm for restricting the light beam. The diaphragm may be located between the third lens and the fourth lens or between the object side and the first lens, which can reduce the generation of ghost images in the optical lens and effectively reduce the difficulty of distortion correction of the lens.

[0053] In some embodiments, the maximum field of view FOV of the optical lens and the aperture value Fno of the optical lens satisfy: 1.35° < FOV / Fno < 1.75°. Meeting the above range defines that the optical lens has a suitable field of view and aperture value. More specifically, 1.49° < FOV / Fno < 1.59°.

[0054] In some embodiments, the back focal length BFL of the optical lens and the total optical length TTL of the optical lens satisfy: 0.4 < BFL / TTL < 0.6. Meeting the above range enables the lens to have a larger back focus, which is beneficial to the assembly of the module, reduces interference, and improves the production yield. More specifically, 0.43 < BFL / TTL < 0.52.

[0055] In some embodiments, the radius of curvature R8 of the image side of the fourth lens and the radius of curvature R9 of the object side of the fifth lens satisfy: -0.4 < (R8 - R9) / (R8 + R9) ≤ 0. Meeting the above range can reduce the light deflection angle, make the light trend smoother; at the same time, it can correct coma and field curvature, improve the flatness of imaging, and enhance the imaging quality of the optical lens. More specifically, -0.12 < (R8 - R9) / (R8 + R9) ≤ 0.

[0056] In some embodiments, the effective focal length f of the optical lens satisfies: 80 mm < f < 100 mm; the chief ray angle of incidence CRA at the maximum image height of the optical lens satisfies: 2.7° < CRA < 5.5°. Meeting the above ranges enables the optical lens to have a telephoto characteristic and a small CRA, and can achieve the effect of bringing distant scenes closer and highlighting the main subject. More specifically, 87 mm < f < 93 mm; 2.9° < CRA < 5.1°.

[0057] In some embodiments, the overall optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 1 < TTL / f < 1.35. Meeting the above range is beneficial to restricting the overall length of the lens while better realizing the telephoto performance of the system. More specifically, 1.08 < TTL / f < 1.34.

[0058] 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 angle of the optical lens satisfy: 7.1 < TTL / IH < 11.1. Meeting the above range is beneficial to achieving the balance between the volume of the optical lens and the large image plane. More specifically, 7.96 < TTL / IH < 10.14.

[0059] In some embodiments, 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: 0.55 < IH / EPD < 0.7. Meeting the above range can increase the width of the light beam entering the optical lens, improve the brightness at the image plane of the optical lens, and avoid vignetting. More specifically, 0.64 < IH / EPD < 0.67.

[0060] In some embodiments, the overall optical length TTL of the optical lens, the true image height IH corresponding to the maximum field of view angle of the optical lens, and the maximum field of view angle FOV of the optical lens satisfy: 3.7 / ° < TTL / IH / FOV < 6 / °. Meeting the above range is beneficial to balancing the relationship among the overall length, image height, and field of view angle of the optical lens. More specifically, 4.12 / ° < TTL / IH / FOV < 5.41 / °.

[0061] In some embodiments, the effective focal length f of the optical lens and the focal length f4 of the fourth lens satisfy: -0.3 < f4 / f < -0.1; 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 < (R7 + R8) / (R7 - R8) < 0.8. By satisfying the above ranges and reasonably setting the focal length and surface shape of the fourth lens, the positive spherical aberration generated by the fourth negative lens can be balanced with the negative spherical aberration generated by the front positive lenses, improving the overall imaging quality. At the same time, the trend of light can be reasonably controlled to avoid the problem of excessive lens sensitivity caused by excessive light deflection. More specifically, -0.22 < f4 / f < -0.17; 0.05 < (R7 + R8) / (R7 - R8) < 0.62.

[0062] In some embodiments, the effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: 0.2 < f5 / f < 0.5; the effective focal length f of the optical lens and the curvature radius R9 of the object side surface of the fifth lens satisfy: 0.15 < R9 / f < 0.35. By satisfying the above ranges and defining that the fifth lens has an appropriate positive optical power and the surface shape of the object side surface, it is beneficial to converge light and helps reduce the aberration of the optical lens. More specifically, 0.29 < f5 / f < 0.42; 0.21 < R9 / f < 0.29.

[0063] In some embodiments, the combined focal length f123 of the first lens, the second lens and the third lens and the combined focal length f45 of the fourth lens and the fifth lens satisfy: -1 < f123 / f45 < -0.6. By satisfying the above ranges and reasonably setting the focal length relationship between the front and rear lens groups, it helps the smooth transition of light, reduces the difficulty of correcting aberration of the rear-end lens, and improves the image quality of the optical imaging lens. More specifically, -0.91 < f123 / f45 < -0.69.

[0064] In some embodiments, the clear aperture radius d1 of the object side surface of the first lens and the clear aperture radius d10 of the image side surface of the fifth lens satisfy: 1.15 < d1 / d10 < 1.8. By satisfying the above ranges and controlling the aperture ratio of the front and rear lenses, the trend of light is restricted within a reasonable range, making the illuminance of the imaging surface uniform. More specifically, 1.3 < d1 / d10 < 1.67.

[0065] In some embodiments, the focal length f3 of the third lens and the focal length f4 of the fourth lens satisfy: -10.6 < f3 / f4 < -1.5; the image-side curvature radius R6 of the third lens and the image-side curvature radius R8 of the fourth lens satisfy: -4.2 < R6 / R8 < -2.1. Satisfying the above ranges can reduce the light deflection angle and make the light path more stable; at the same time, it can correct coma and field curvature, improve the flatness of imaging, and enhance the imaging quality of the optical lens. More specifically, -9.8 < f3 / f4 < -1.64; -3.83 < R6 / R8 < -2.31.

[0066] In some embodiments, the focal length f4 of the fourth lens and the focal length f5 of the fifth lens satisfy: -0.75 < f4 / f5 < -0.4; the image-side curvature radius R8 of the fourth lens and the object-side curvature radius R9 of the fifth lens satisfy: 0.7 < R8 / R9 < 1.1. Satisfying the above ranges can reduce the light deflection angle and make the light path more stable; at the same time, it can correct coma and field curvature, improve the flatness of imaging, and enhance the imaging quality of the optical lens. More specifically, -0.65 < f4 / f5 < -0.48; 0.79 < R8 / R9 < 1.01.

[0067] In some embodiments, the focal length f2 of the second lens and the object-side curvature radius R3 of the second lens satisfy: 0.2 < f2 / R3 < 0.6; the focal length f2 of the second lens and the image-side curvature radius R4 of the second lens satisfy: -1.2 < f2 / R4 < -0.8. Satisfying the above ranges is beneficial to slowing down the deflection degree of the incident light and avoiding excessive aberration caused by too strong refraction changes. More specifically, 0.25 < f2 / R3 < 0.52; -1.09 < f2 / R4 < -0.86.

[0068] In some embodiments, the object-side curvature radius R7 of the fourth lens and the image-side curvature radius R8 of the fourth lens satisfy: -4.5 < R7 / R8 < -1; the object-side curvature radius R7 of the fourth lens, the central thickness CT4 of the fourth lens and the image-side curvature radius R8 of the fourth lens satisfy: -4.8 < (R7 - CT4) / R8 < -1.35. Satisfying the above ranges can effectively reduce the optical path difference between the center and the periphery of the lens, which is beneficial to correcting the distortion of the optical lens. More specifically, -4.09 < R7 / R8 < -1.11; -4.39 < (R7 - CT4) / R8 < -1.51.

[0069] In some embodiments, the effective focal length f of the optical lens, the maximum field of view FOV and the true image height IH corresponding to the maximum field of view satisfy: 0.99 < (IH / 2) / (f × tan(FOV / 2)) < 1.02. Satisfying the above range can control the optical lens to have a small distortion and improve the imaging quality of the optical lens.

[0070] 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: 0.1 < IH / f < 0.2. Meeting the above range and controlling the image height and focal length of the optical lens within a reasonable range helps the optical lens to have long focal length characteristics and improve the imaging quality. More specifically, 0.12 < IH / f < 0.15.

[0071] In some embodiments, the effective focal length f of the optical lens and the back focal length BFL of the optical lens satisfy: 0.4 < BFL / f < 0.75. Meeting the above range and defining that the optical lens has an appropriate back focus facilitate the reasonable arrangement of the positions of each lens and reduce the processing and assembly difficulty at the same time. More specifically, 0.47 < BFL / f < 0.66.

[0072] In some embodiments, the effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: 0.4 < f1 / f < 0.8. Meeting the above range and setting the first lens to have a large positive refractive power can cause the incident light to converge to a large extent and allow more light to enter the system, which is beneficial to improving the light input of the lens and enabling the lens to achieve high-definition imaging in a darker environment. More specifically, 0.46 < f1 / f < 0.66.

[0073] In some embodiments, the effective focal length f of the optical lens and the focal length f2 of the second lens satisfy: -0.5 < f2 / f < 2. Meeting the above range is beneficial to the smooth transition of light and improves the imaging resolution. More specifically, -0.47 < f2 / f < 1.79.

[0074] In some embodiments, the effective focal length f of the optical lens and the focal length f3 of the third lens satisfy: 0.2 < f3 / f < 2.3. Meeting the above range can make the third lens have an appropriate positive optical power, which is beneficial to the smooth transition of the light trend and improves the imaging quality of the optical lens. More specifically, 0.29 < f3 / f < 2.1.

[0075] In some embodiments, the focal length f1 of the first lens and the focal length f5 of the fifth lens satisfy: 1.15 < f1 / f5 < 1.9; the central thickness CT1 of the first lens and the central thickness CT5 of the fifth lens satisfy: 0.7 < CT1 / CT5 < 1.1. Meeting the above range and controlling the focal length and thickness relationship of the front and rear lenses is beneficial to reducing the aberration of the optical lens and improving the imaging quality of the optical lens. More specifically, 1.3 < f1 / f5 < 1.73; 0.79 < CT1 / CT5 < 0.97.

[0076] 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: -4.6 < R3 / R4 < -1.7; 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: 1.4 < (R3 - R4) / (R3 + R4) < 4.2. By satisfying the above ranges, by controlling the surface shape of the second lens, the degree of deflection of light entering the second lens can be effectively reduced, which is beneficial to maintaining the miniaturization of the lens head. More specifically, -4.22 < R3 / R4 < -1.7; 1.61 < (R3 - R4) / (R3 + R4) < 3.81.

[0077] In some embodiments, the optical lens satisfies the conditional expressions: 17.5 mm < EPD < 19.5 mm, 90 mm < TTL < 125 mm, 4.5 < Fno < 5.5, 40 mm < BFL < 65 mm, 7° < FOV < 8°, 11 mm < IH < 13 mm; where, 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, BFL represents the back focal length of the optical lens, FOV represents the maximum field of view angle of the optical lens, and IH represents the image height corresponding to the maximum field of view angle of the optical lens. By satisfying the above conditions, it shows that the optical lens provided by the embodiments of the present invention has at least the characteristics of long focal length, large image plane, small CRA, etc. More specifically, 18.2 mm < EPD < 18.5 mm, 95.5 mm < TTL < 121.6 mm, 4.8 < Fno < 5.1, 42.1 mm < BFL < 59.7 mm, 7.4° < FOV < 7.8°, 11.9 mm < IH < 12.1 mm.

[0078] The present invention will be further described below with multiple embodiments. In each embodiment, the thickness, radius of curvature, and material selection of each lens in the optical lens are partially different. For specific differences, please refer to the parameter tables of each embodiment. The following embodiments are only preferred embodiments of the present invention, but the embodiments of the present invention are not limited only by the following embodiments. Any other changes, substitutions, combinations, or simplifications made without departing from the innovative points of the present invention should be regarded as equivalent replacement methods and are included in the protection scope of the present invention.

[0079] Embodiment 1

[0080] Please refer to Figure 1 , which shows a schematic structural diagram of the optical lens 100 provided in Embodiment 1 of the present invention. The optical lens sequentially includes, along the optical axis from the object side to the imaging surface: a first lens L1, a second lens L2, a third lens L3, a diaphragm ST, a fourth lens L4, and a fifth lens L5.

[0081] The first lens L1 has positive refractive power, its object side surface S1 is convex, and its image side surface S2 is flat;

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

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

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

[0085] The fifth lens L5 has positive refractive power, an object-side surface S9 thereof is a convex surface, and an image-side surface S10 thereof is a flat surface.

[0086] The first lens L1, the second lens L2, the third lens L3, the fourth lens L4 and the fifth lens L5 are glass spherical lenses.

[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] In this embodiment, the F-Tan (Theta) distortion curve, the axial aberration curve, the vertical chromatic aberration curve, the MTF curve, and the relative illumination curve of the optical lens 100 are respectively as follows: Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 shown.

[0091] Figure 2 The F-Tan (Theta) distortion curve of the optical lens 100 in this embodiment is shown, which represents the distortion of different field angles on the imaging plane, with the horizontal axis representing the distortion value (unit: %) and the vertical axis representing the half field angle (unit: °). It can be seen from the figure that the distortion value is controlled within ±0.08%, indicating that the optical lens 100 can correct the distortion well.

[0092] Figure 3 The axial aberration curve of the optical lens 100 in this embodiment is shown, which represents the aberration of each wavelength on the optical axis at the imaging 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, indicating that the optical lens 100 can correct the axial aberration well.

[0093] Figure 4The vertical axis chromatic aberration curve of the optical lens 100 in this embodiment is shown, which represents the chromatic aberration of each wavelength relative to the central wavelength (0.59 μm) at different image heights on the imaging surface, the horizontal axis represents the vertical axis chromatic aberration value of each wavelength relative to the central wavelength (unit: μm), and the vertical axis represents the normalized field angle. It can be seen from the figure that the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±0.6 μm, indicating that the optical lens 100 can correct chromatic aberration very well.

[0094] Figure 5 The modulation transfer function (MTF) curve of the optical lens 100 in this embodiment is shown, which represents the imaging modulation degree of the lens at different spatial frequencies 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 whole field of view, and in the range of 0 to 100 lp / mm, the MTF curve decreases evenly and smoothly from the center to the edge of the field of view, and has good imaging quality and good detail resolution ability in both low-frequency and high-frequency conditions.

[0095] Figure 6 The relative illumination curve of the optical lens 100 in this embodiment is shown, which represents the relative illumination values ​​at different viewing angles on the imaging surface, the horizontal axis represents the half viewing angle (unit: °), and the vertical axis represents the relative illumination. It can be seen from the figure that the relative illumination value of the optical lens 100 is still greater than 98% at the edge of the viewing field, indicating that the optical lens 100 has an excellent relative illumination.

[0096] Example 2

[0097] 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 of this embodiment are: the second lens L2 has positive focal power; the object-side surface S3 of the second lens L2 is a convex surface; the image-side surface S4 of the second lens L2 is a convex surface; the object-side surface S5 of the third lens L3 is a concave surface; the image-side surface S10 of the fifth lens L5 is a concave surface; the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0098] The relevant parameters of each lens in the optical lens 200 in Example 2 are shown in Table 2-1.

[0099] Table 2-1

[0100]

[0101] In this embodiment, the F-Tan (Theta) distortion curve, the axial aberration curve, the vertical chromatic aberration curve, the MTF curve, and the relative illumination curve of the optical lens 200 are respectively as follows: Figure 8 , Fig. 9 , Fig.10 , Fig.11 , Fig.12 shown.

[0102] from Figure 8 It can be seen that the distortion value is controlled within ±0.03%, indicating that the optical lens 200 can correct the distortion well.

[0103] from Fig. 9 It can be seen that the offset of the axial aberration is controlled within ±0.06 mm, indicating that the optical lens 200 can correct the axial aberration well.

[0104] from Fig.10 It can be seen that the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±0.4 μm, indicating that the optical lens 200 can correct chromatic aberration very well.

[0105] from Fig.11 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 100 lp / mm, the MTF curve decreases evenly and smoothly from the center to the edge of the field of view, and has good imaging quality and good detail resolution capability in both low-frequency and high-frequency conditions.

[0106] from Fig.12 It can be seen that the relative illumination value of the optical lens 200 is still greater than 98% at the edge of the field of view, indicating that the optical lens 200 has excellent relative illumination.

[0107] Example 3

[0108] 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.

[0109] The relevant parameters of each lens in the optical lens 300 in Example 3 are shown in Table 3-1.

[0110] Table 3-1

[0111]

[0112] In this embodiment, the F-Tan (Theta) distortion curve, the axial aberration curve, the vertical axis chromatic aberration curve, the MTF curve, and the relative illumination curve of the optical lens 300 are respectively as follows: Fig.14 , Fig.15 , Fig.16 , Fig.17 , Fig.18 shown.

[0113] from Fig.14 It can be seen that the distortion value is controlled within ±0.15%, indicating that the optical lens 300 can correct the distortion well.

[0114] from Fig.15 It can be seen that the offset of the axial aberration is controlled within ±0.05 mm, indicating that the optical lens 300 can correct the axial aberration well.

[0115] from Fig.16 It can be seen that the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±0.2μm, indicating that the optical lens 300 can correct chromatic aberration very well.

[0116] from Fig.17 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 100 lp / mm, the MTF curve decreases evenly and smoothly from the center to the edge of the field of view, and has good imaging quality and good detail resolution capability in both low-frequency and high-frequency conditions.

[0117] from Fig.18 It can be seen that the relative illumination value of the optical lens 300 is still greater than 90% at the edge of the field of view, indicating that the optical lens 300 has excellent relative illumination.

[0118] 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 maximum field of view angle FOV, the chief ray incident angle CRA at the maximum image height, and the numerical value corresponding to each conditional expression in each embodiment.

[0119] Table 4

[0120]

[0121]

[0122] In summary, the optical lens provided by the present invention has at least the following advantages:

[0123] (1) The object side of the first lens is convex, which helps to converge the incident light, reduce the diameter of the head lens, and facilitate miniaturization of the head. The lens has a telephoto characteristic, which can better present larger local details and make the picture more focused and compact; it can also realize the large image surface characteristic of the lens and achieve high-definition imaging of the lens.

[0124] (2) Through the specific surface shape setting and reasonable optical power distribution, the lens has the characteristics of high relative illumination, which can well capture real images, and the brightness of the captured images is uniform. It can improve the imaging quality of the optical lens, have less distortion, reduce aberrations, and improve the imaging quality of the optical lens.

[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, comprising five lenses, characterized in that: It sequentially includes from the object side to the imaging surface along the optical axis: A first lens with positive optical power, whose object side is convex and whose image side is flat; A second lens with optical power; A third lens with positive optical power, whose image side is convex; A fourth lens with negative optical power, whose object side is concave and whose image side is concave; A fifth lens with positive optical power, whose object side is convex and whose image side is flat or concave; Wherein, the maximum field of view angle FOV of the optical lens and the aperture value Fno of the optical lens satisfy: 1.35° < FOV / Fno < 1.75°; the back focal length BFL of the optical lens and the total optical length TTL of the optical lens satisfy: 0.4 < BFL / TTL < 0.6; the image side curvature radius R8 of the fourth lens and the object side curvature radius R9 of the fifth lens satisfy: -0.4 < (R8 - R9) / (R8 + R9) ≤ 0.

2. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens satisfies: 80mm < f < 100mm; the chief ray angle of incidence CRA at the maximum image height of the optical lens satisfies: 2.7° < CRA < 5.5°.

3. 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: 1 < TTL / f < 1.35; 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: 7.1 < TTL / IH < 11.

1.

4. The optical lens according to claim 1, characterized in that: The true image height IH corresponding to the maximum field of view angle of the optical lens and the entrance pupil diameter EPD of the optical lens satisfy: 0.55 < IH / EPD < 0.7; the total optical length TTL of the optical lens, the true image height IH corresponding to the maximum field of view angle of the optical lens and the maximum field of view angle FOV of the optical lens satisfy: 3.7 / ° < TTL / IH / FOV < 6 / °.

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: -0.3 < f4 / f < -0.1; the object side curvature radius R7 of the fourth lens and the image side curvature radius R8 of the fourth lens satisfy: 0 < (R7 + R8) / (R7 - R8) < 0.

8.

6. The optical lens according to claim 1, characterized in that: The effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: 0.2 < f5 / f < 0.5; the effective focal length f of the optical lens and the object side curvature radius R9 of the fifth lens satisfy: 0.15 < R9 / f < 0.

35.

7. The optical lens according to claim 1, characterized in that: The combined focal length f123 of the first lens, the second lens and the third lens and the combined focal length f45 of the fourth lens and the fifth lens satisfy: -1 < f123 / f45 < -0.6; the clear aperture semi-diameter d1 of the object side of the first lens and the clear aperture semi-diameter d10 of the image side of the fifth lens satisfy: 1.15 < d1 / d10 < 1.

8.

8. The optical lens according to claim 1, characterized in that: The focal length f3 of the third lens and the focal length f4 of the fourth lens satisfy: -10.6 < f3 / f4 < -1.5; the image-side curvature radius R6 of the third lens and the image-side curvature radius R8 of the fourth lens satisfy: -4.2 < R6 / R8 < -2.

1.

9. The optical lens according to claim 1, characterized in that: The focal length f4 of the fourth lens and the focal length f5 of the fifth lens satisfy: -0.75 < f4 / f5 < -0.4; the image-side curvature radius R8 of the fourth lens and the object-side curvature radius R9 of the fifth lens satisfy: 0.7 < R8 / R9 < 1.

1.

10. The optical lens according to claim 1, characterized in that: The focal length f2 of the second lens and the object-side curvature radius R3 of the second lens satisfy: 0.2 < f2 / R3 < 0.6; the focal length f2 of the second lens and the image-side curvature radius R4 of the second lens satisfy: -1.2 < f2 / R4 < -0.

8.

11. The optical lens according to claim 1, characterized in that: The object-side curvature radius R7 of the fourth lens and the image-side curvature radius R8 of the fourth lens satisfy: -4.5 < R7 / R8 < -1; the object-side curvature radius R7 of the fourth lens, the central thickness CT4 of the fourth lens and the image-side curvature radius R8 of the fourth lens satisfy: -4.8 < (R7 - CT4) / R8 < -1.35.

Images