Optical lens

Abstract

The invention provides an optical lens, which sequentially comprises a first lens with negative focal power from an object side to an imaging surface along an optical axis, a second lens with negative focal power, a third lens with negative focal power and a fourth lens with negative focal power from the object side to the imaging surface, the object side surface of the second lens is a concave surface, and the image side surface of the second lens near the optical axis is a convex surface; the object side surface of the third lens is a concave surface, and the image side surface of the third lens is a convex surface; the object side surface of the fourth lens is a convex surface, and the image side surface of the fourth lens is a 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 concave surface; and the object side surface of the sixth lens is a convex surface, and the image side surface of the sixth lens is a convex surface. According to the optical lens provided by the invention, the six lenses with specific focal power and specific surface types are adopted, so that the lens has one or more advantages of short total length, day and night common focal length, high imaging quality and the like.

Description

Technical Field

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

[0002] With the rapid development and wide application of security fixed-focus monitoring systems, the requirements for wide-angle monitoring lenses are constantly increasing. Today's wide-angle lenses are continuously evolving towards lower costs, high-definition image quality, small size, and day-night co-focus capabilities. Accordingly, a new architecture of day-night co-focus wide-angle lenses has become an object to be explored. Traditional all-glass lenses have high costs, low pixels, insufficient resolution, large volumes, and do not have day-night co-focus capabilities. 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: An optical lens is composed of six lenses with optical powers, and successively includes, along the optical axis from the object side to the imaging surface: A first lens with a negative optical power, whose object side is convex and whose image side is concave; A second lens with a negative optical power, whose object side is concave and whose image side is convex near the optical axis; A third lens with a negative optical power, whose object side is concave and whose image side is convex; A fourth lens with a positive optical power, whose object side is convex and whose image side is concave; A fifth lens with a negative optical power, whose object side is convex and whose image side is concave; A sixth lens with a positive optical power, whose object side is convex and whose image side is convex; Wherein, the total optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 5 < TTL / f < 7; the maximum field of view FOV of the optical lens and the aperture value Fno of the optical lens satisfy: 65° < FOV / Fno < 75°.

[0005] Further preferably, 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: 2.5 < TTL / IH < 3; 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: 3.2 < IH / EPD < 4.

[0006] More preferably, the back focal length BFL of the optical lens and the effective focal length f of the optical lens satisfy: 1.2 < BFL / f < 1.7; the sum ΣCT of the central thicknesses of the first lens to the sixth lens along the optical axis and the effective focal length f of the optical lens satisfy: 2.7 < ΣCT / f < 3.8.

[0007] More preferably, the focal length f1 of the first lens and the effective focal length f of the optical lens satisfy: -2.6 < f1 / f < -1.5; the image-side curvature radius R2 of the first lens and the effective focal length f of the optical lens satisfy: 0.8 < R2 / f < 1.1.

[0008] More preferably, the combined focal length f123 of the first lens, the second lens and the third lens and the combined focal length f456 of the fourth lens, the fifth lens and the sixth lens satisfy: -1.5 < f123 / f456 < -0.6.

[0009] More preferably, the object-side curvature radius R5 of the third lens and the effective focal length f of the optical lens satisfy: -1.7 < R5 / f < -0.7; the image-side curvature radius R6 of the third lens and the effective focal length f of the optical lens satisfy: -4 < R6 / f < -0.95.

[0010] More preferably, the object-side curvature radius R7 of the fourth lens and the effective focal length f of the optical lens satisfy: 1.2 < R7 / f < 1.9; the image-side curvature radius R8 of the fourth lens and the effective focal length f of the optical lens satisfy: 4 < R8 / f < 24.7.

[0011] More preferably, the object-side curvature radius R9 of the fifth lens and the effective focal length f of the optical lens satisfy: 1.1 < R9 / f < 2.4; the image-side curvature radius R10 of the fifth lens and the effective focal length f of the optical lens satisfy: 0.4 < R10 / f < 0.7.

[0012] More preferably, the image-side curvature radius R4 of the second lens and the object-side curvature radius R5 of the third lens satisfy: 0.3 < (R4 - R5) / (R4 + R5) < 1; 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) / (R7 + R8) < -0.1.

[0013] Further preferably, the sagittal height Sag7 of the clear aperture of the object side surface of the fourth lens and the clear aperture diameter d7 of the object side surface of the fourth lens satisfy: 0.1 < Sag7 / d7 < 0.4; the sagittal height Sag8 of the clear aperture of the image side surface of the fourth lens and the clear aperture diameter d8 of the image side surface of the fourth lens satisfy: 0 < Sag8 / d8 < 0.2.

[0014] Compared with the prior art, the optical lens provided by the present invention has one or more advantages such as 4K high-definition imaging, short overall length, and day-night common focal length through specific surface shape settings and reasonable optical power distribution. In addition, by using a combination of glass and plastic lenses, the cost can be effectively reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the following description of the embodiments in conjunction with the accompanying drawings, wherein: Figure 1 is a schematic structural diagram of the optical lens in Embodiment 1 of the present invention.

[0016] Figure 2 is a graph of F-Tan(Theta) distortion of the optical lens in Embodiment 1 of the present invention.

[0017] Figure 3 is a graph of field curvature of the optical lens in Embodiment 1 of the present invention.

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

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

[0020] Figure 6 is a graph of F-Tan(Theta) distortion of the optical lens in Embodiment 2 of the present invention.

[0021] Figure 7 is a graph of field curvature of the optical lens in Embodiment 2 of the present invention.

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

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

[0024] Fig.10 is a graph of F-Tan(Theta) distortion of the optical lens in Embodiment 3 of the present invention.

[0025] Fig.114 is a field curvature curve diagram of the optical lens in Example 3 of the present invention.

[0026] Fig.12 Graph showing the vertical axis chromatic aberration of the optical lens in Example 3 of the present invention.

[0027] The following specific implementation manner will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0028] 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.

[0029] 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.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] The optical lens provided by the embodiment of the present invention is composed of six lenses with optical power, which include: a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens in sequence from the object side to the imaging surface along the optical axis.

[0036] In some embodiments, the first lens may have negative optical power, its object side surface may be convex, and its image side surface may be concave. The second lens may have negative optical power, its object side surface may be concave, and its image side surface may be convex at the near optical axis. The third lens may have negative optical power, its object side surface may be concave, and its image side surface may be convex. The fourth lens may have positive optical power, its object side surface may be convex, and its image side surface may be concave. The fifth lens may have negative optical power, its object side surface may be convex, and its image side surface may be concave. The sixth lens may have positive optical power, its object side surface may be convex, and its image side surface may be convex.

[0037] In some embodiments, the optical lens may further include an aperture, and the aperture may be located between the third lens and the fourth lens. It is understood that the aperture is used to limit the amount of light entering to change the brightness of the image. When the aperture is located between the third lens and the fourth lens, it is convenient to correct the aperture aberration.

[0038] In some embodiments, the optical lens may further include a filter and a protective glass, and the filter and the protective glass are sequentially arranged between the sixth 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. The protective glass plays a role in protecting the optical lens, preventing the photosensitive chip from being damaged, and can improve the impact resistance and scratch resistance of the optical lens, while having almost no effect on the imaging quality of the optical lens.

[0039] In some embodiments, the fifth lens and the sixth lens can be glued to form a glued lens, which can effectively correct the chromatic aberration of the optical lens, reduce the eccentricity sensitivity of the optical lens, balance the aberration of the optical lens, and improve the imaging quality of the optical lens; it can also reduce the assembly sensitivity of the optical lens, thereby reducing the difficulty of the processing technology of the optical lens and improving the assembly yield of the optical lens.

[0040] In some embodiments, the total optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 5 < TTL / f < 7; the maximum field of view FOV of the optical lens and the f-number Fno of the optical lens satisfy: 65° < FOV / Fno < 75°. Satisfying the above ranges can effectively limit the length of the lens, thereby realizing a lens with a short total length. Moreover, by defining that the optical lens has a suitable field of view and f-number, it is possible to collect light at large angles and obtain good imaging quality. More specifically: 5.33 < TTL / f < 6.54; 71.02° < FOV / Fno < 72.74°.

[0041] In some embodiments, the total optical length TTL of the optical lens and the true image height IH corresponding to the maximum field of view of the optical lens satisfy: 2.5 < TTL / IH < 3; 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: 3.2 < IH / EPD < 4. Satisfying 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 entering the optical lens, improve the image plane brightness, and at the same time can better achieve a reasonable balance between the total length of the lens and the large image plane. More specifically: 2.71 < TTL / IH < 2.9; 3.23 < IH / EPD < 3.74.

[0042] In some embodiments, the back focal length BFL of the optical lens and the effective focal length f of the optical lens satisfy: 1.2 < BFL / f < 1.7; the sum ΣCT of the central thicknesses of the first lens to the sixth lens along the optical axis respectively and the effective focal length f of the optical lens satisfy: 2.7 < ΣCT / f < 3.8. Satisfying the above ranges, by controlling the back focal length and the effective focal length of the optical lens within appropriate ranges, it is beneficial to reduce the interference between the lens and the imaging chip and improve the assembly yield. 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: 1.35 < BFL / f < 1.53; 2.99 < ΣCT / f < 3.44.

[0043] In some embodiments, the focal length f1 of the first lens and the effective focal length f of the optical lens satisfy: -2.6 < f1 / f < -1.5; 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: 0.8 < R2 / f < 1.1. Satisfying the above ranges can make the first lens have an appropriate negative optical power and define the surface shape of the image side surface of the first lens, which can effectively balance the lens aberration and improve the imaging quality. More specifically: -2.34 < f1 / f < -1.7; 0.88 < R2 / f < 0.99.

[0044] In some embodiments, the combined focal length f123 of the first lens, the second lens, and the third lens and the combined focal length f456 of the fourth lens, the fifth lens, and the sixth lens satisfy: -1.5 < f123 / f456 < -0.6. Meeting the above range and defining the focal length ratio of the lens groups before and after the aperture of the optical lens can effectively correct the aberration generated by the lens groups before and after the aperture and improve the imaging quality of the optical lens. More specifically: -1.36 < f123 / f456 < -0.68.

[0045] In some embodiments, the object-side curvature radius R5 of the third lens and the effective focal length f of the optical lens satisfy: -1.7 < R5 / f < -0.7; the image-side curvature radius R6 of the third lens and the effective focal length f of the optical lens satisfy: -4 < R6 / f < -0.95. Meeting the above range and reasonably setting the surface shape of the third lens enables the light passing through the third lens to diverge better, which is beneficial to improving the imaging clarity. More specifically: -1.58 < R5 / f < -0.81; -3.69 < R6 / f < -1.06.

[0046] In some embodiments, the object-side curvature radius R7 of the fourth lens and the effective focal length f of the optical lens satisfy: 1.2 < R7 / f < 1.9; the image-side curvature radius R8 of the fourth lens and the effective focal length f of the optical lens satisfy: 4 < R8 / f < 24.7. Meeting the above range and reasonably setting the surface shape of the fourth lens can further optimize the spherical aberration and improve the imaging quality. More specifically: 1.37 < R7 / f < 1.74; 4.47 < R8 / f < 22.48.

[0047] In some embodiments, the object-side curvature radius R9 of the fifth lens and the effective focal length f of the optical lens satisfy: 1.1 < R9 / f < 2.4; the image-side curvature radius R10 of the fifth lens and the effective focal length f of the optical lens satisfy: 0.4 < R10 / f < 0.7. Meeting the above range and reasonably setting the surface shape of the fifth lens helps to further balance the aberration of the lens and improve the imaging quality. More specifically: 1.19 < R9 / f < 2.24; 0.5 < R10 / f < 0.64.

[0048] In some embodiments, the radius of curvature R4 of the image side surface of the second lens and the radius of curvature R5 of the object side surface of the third lens satisfy: 0.3 < (R4 - R5) / (R4 + R5) < 1; 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) / (R7 + R8) < -0.1. Meeting the above ranges and reasonably controlling the mutual relationship between the radius of curvature of the image side surface of the second lens and the object side surface of the third lens can correct the aberration of the optical lens and is conducive to high-definition imaging of the lens. Moreover, by controlling the shapes of the object side surface and the image side surface of the fourth lens, the fourth lens has an appropriate surface shape, which can effectively improve the field curvature and aberration. More specifically: 0.59 < (R4 - R5) / (R4 + R5) < 0.82; -0.89 < (R7 - R8) / (R7 + R8) < -0.43.

[0049] In some embodiments, the sagittal height Sag7 of the clear aperture of the object side surface of the fourth lens and the clear aperture d7 of the object side surface of the fourth lens satisfy: 0.1 < Sag7 / d7 < 0.4; the sagittal height Sag8 of the clear aperture of the image side surface of the fourth lens and the clear aperture d8 of the image side surface of the fourth lens satisfy: 0 < Sag8 / d8 < 0.2. Meeting the above ranges helps to control the light ray trend and highlight the detailed information of the central field of view of the optical lens. More specifically: 0.22 < Sag7 / d7 < 0.27; 0 < Sag8 / d8 < 0.09.

[0050] In some embodiments, the sum ΣCT of the central thicknesses of the first lens to the sixth lens along the optical axis respectively and the total optical length TTL of the optical lens satisfy: 0.5 < ΣCT / TTL < 0.6. Meeting the above ranges 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: 0.52 < ΣCT / TTL < 0.57.

[0051] In some embodiments, the focal length f2 of the second lens and the effective focal length f of the optical lens satisfy: -19.2 < f2 / f < -5.5. Meeting the above ranges and controlling the second lens to have an appropriate negative optical power helps to control the distortion and reduce the field curvature, thereby improving the geometric accuracy of the imaging surface. More specifically: -17.58 < f2 / f < -6.05.

[0052] In some embodiments, the focal length f3 of the third lens and the effective focal length f of the optical lens satisfy: -43 < f3 / f < -4.5. Meeting the above ranges and controlling the third lens to have an appropriate negative optical power helps to increase the imaging area and improve the imaging quality. More specifically: -39.87 < f3 / f < -5.05.

[0053] In some embodiments, the focal length f4 of the fourth lens and the effective focal length f of the optical lens satisfy: 2.1 < f4 / f < 4.7. Meeting the above range, controlling the fourth lens to have an appropriate positive optical power can converge light, reduce the light deflection angle, and improve the imaging quality. More specifically: 2.33 < f4 / f < 4.3.

[0054] In some embodiments, the focal length f5 of the fifth lens and the effective focal length f of the optical lens satisfy: -4.5 < f5 / f < -1.3. Meeting the above range, controlling the fifth lens to have an appropriate negative optical power is beneficial to diverge the light converged by the fourth lens, thereby increasing the light entering the sixth lens. More specifically: -4.11 < f5 / f < -1.51.

[0055] In some embodiments, the focal length f6 of the sixth lens and the effective focal length f of the optical lens satisfy: 0.8 < f6 / f < 1.1. Meeting the above range, controlling the sixth lens to have an appropriate positive optical power is beneficial to improving the light converging ability of the optical lens, and at the same time can balance the aberration of the optical lens and improve the imaging quality of the optical lens. More specifically: 0.85 < f6 / f < 1.

[0056] In some embodiments, the combined focal length f56 of the fifth lens and the sixth lens and the effective focal length f of the optical lens satisfy: 1.7 < f56 / f < 3.3. Meeting the above range, the fifth and sixth lenses form a cemented lens with a positive optical power. By reasonably setting the focal lengths of the fifth and sixth cemented lenses, the incident light can be further converged, the light energy loss can be reduced, and the light can smoothly enter the rear after convergence, further making the light trend stable and improving the relative illumination of the edge field of view. More specifically: 1.88 < f56 / f < 3.03.

[0057] 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) < 0. Meeting the above range, by reasonably limiting 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, which can effectively correct the aberration of the optical lens. More specifically: -0.46 < (R3 - R4) / (R3 + R4) < -0.19.

[0058] In some embodiments, the focal length f4 of the fourth lens and the distance CT45 between the fourth lens and the fifth lens on the optical axis satisfy: 16 < f4 / CT45 < 45. Meeting the above range is beneficial to meeting the processability of the lens and can reduce the assembly difficulty. More specifically: 18 < f4 / CT45 < 40.87.

[0059] In some embodiments, the optical lens satisfies the following conditional expressions: 2.7 mm < f < 3.8 mm; 1.7 mm < EPD < 2.4 mm; 18 mm < TTL < 21 mm; 1.5 < Fno < 1.8; 20° < CRA < 25°; 4 mm < BFL < 5 mm; 110° < FOV < 130°; 6.5 mm < IH < 7.5 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 overall optical length of the optical lens, Fno represents the aperture value of the optical lens, IH represents the true image height corresponding to the maximum field of view angle of the optical lens, 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 short overall length, day-night common focal length, and high imaging quality. More specifically: 3.03 mm < f < 3.57 mm; 1.83 mm < EPD < 2.17 mm; 19.01 mm < TTL < 19.83 mm; 1.64 < Fno < 1.66; 22.32° < CRA < 22.81°; 4.46 mm < BFL < 4.85 mm; 117.1° < FOV < 120.1°; 6.85 mm < IH < 7.11 mm.

[0060] 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. On the other hand, 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 adopts a combination structure of six lenses with a glass-plastic mixture, which can better achieve high-definition imaging. Specifically, the first lens and the fourth lens can be made of glass lenses, and the second lens, the third lens, the fifth lens, and the sixth lens are all plastic lenses. Adopting the glass-plastic hybrid structure can effectively reduce costs, correct aberrations, reduce the volume, and provide an optical lens product with higher cost performance.

[0061] In some embodiments, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens can adopt spherical lenses or aspherical lenses. Compared with the spherical structure, the aspherical structure can effectively reduce the aberration of the optical system, thereby reducing the number of lenses and the size of the lenses, and better realizing the miniaturization of the lens. More specifically, the first lens and the fourth lens of the present invention can both adopt spherical lenses, and the second lens, the third lens, the fifth lens, and the sixth lens can all adopt aspherical lenses.

[0062] 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: ; 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, and E are the fourth-order, sixth-order, eighth-order, and tenth-order surface coefficients respectively.

[0063] 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.

[0064] Example 1 See also Figure 1 , which is a schematic diagram of the structure of the optical lens 100 provided in Embodiment 1 of the present invention, wherein the optical lens 100 includes, in sequence from the object side to the imaging surface along the optical axis: a first lens L1, a second lens L2, a third lens L3, an aperture ST, a fourth lens L4, a fifth lens L5, a sixth lens L6, a filter G1 and a protective glass G2.

[0065] The first lens L1 has negative refractive power, its object side surface S1 is convex, and its image side surface S2 is concave; The second lens L2 has negative refractive power, its object side surface S3 is concave, and its image side surface S4 is convex near the optical axis; The third lens L3 has negative refractive power, its object-side surface S5 is concave, and its image-side surface S6 is convex; The fourth lens L4 has positive refractive power, its object-side surface S7 is convex, and its image-side surface S8 is concave; The fifth lens L5 has negative refractive power, its object-side surface S9 is convex, and its image-side surface S10 is concave; The sixth lens L6 has positive refractive power, an object-side surface S10 thereof is convex, and an image-side surface S11 thereof is convex; The fifth lens L5 and the sixth lens L6 form a cemented lens group with positive refractive power, that is, the cemented surface between the image side surface of the fifth lens L5 and the object side surface of the sixth lens L6 is S10; The object side surface S12 and the image side surface S13 of the filter G1 are both planes; The object side surface S14 and the image side surface S15 of the protective glass G2 are both planes; The imaging surface S16 is a plane.

[0066] The first lens L1 and the fourth lens L4 are glass spherical lenses, and the second lens L2, the third lens L3, the fifth lens L5, and the sixth lens L6 are plastic aspherical lenses.

[0067] The relevant parameters of each lens in the optical lens 100 in Example 1 are shown in Table 1-1.

[0068] Table 1-1 The surface parameters of the aspheric lens of the optical lens 100 in Example 1 are shown in Table 1-2.

[0069] Table 1-2 In this embodiment, the F-Tan (Theta) distortion curve, the field curvature curve, and the vertical axis chromatic aberration curve of the optical lens 100 are respectively as follows: Figure 2 , Figure 3 , Figure 4 shown.

[0070] Figure 2 The F-Tan (Theta) distortion curve of Example 1 is shown, which represents the F-Tan (Theta) distortion at different image heights on the imaging plane, the horizontal axis represents the F-Tan (Theta) distortion value (unit: %), and the vertical axis represents the half field angle (unit: °). It can be seen from the figure that the F-Tan (Theta) distortion of the optical lens 100 is controlled within -40%~0%, indicating that the distortion of the optical lens 100 is well corrected.

[0071] Figure 3 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.

[0072] Figure 4 The vertical chromatic aberration curve of Example 1 is shown, which represents the chromatic aberration of each wavelength relative to the central wavelength (0.555 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~4 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.

[0073] Example 2 See also Figure 5, 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 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.

[0074] The relevant parameters of each lens in the optical lens 200 in Example 2 are shown in Table 2-1.

[0075] Table 2-1 The surface parameters of the aspheric lens of the optical lens 200 in Example 2 are shown in Table 2-2.

[0076] Table 2-2 In this embodiment, the F-Tan (Theta) distortion curve, the field curvature curve, and the vertical axis chromatic aberration curve of the optical lens 200 are respectively as follows: Figure 6 , Figure 7 , Figure 8 shown.

[0077] from Figure 6 It can be seen that the F-Tan (Theta) distortion of the optical lens 200 is controlled within -45%~0%, indicating that the distortion of the optical lens 200 is well corrected.

[0078] from Figure 7 It can be seen that the field curvature of the meridian image plane and the sagittal image plane is controlled within ±0.1 mm, indicating that the optical lens 200 can correct the field curvature well.

[0079] from Figure 8 It can be seen that the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±4μm, indicating that the optical lens 200 can extremely well correct the chromatic aberration of the edge field of view and the secondary spectrum of the entire image plane.

[0080] Example 3 See also Fig. 9 , 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.

[0081] The relevant parameters of each lens in the optical lens 300 in Example 3 are shown in Table 3-1.

[0082] Table 3-1 The surface parameters of the aspheric lens of the optical lens 300 in Example 3 are shown in Table 3-2.

[0083] Table 3-2 In this embodiment, the F-Tan (Theta) distortion curve, the field curvature curve, and the vertical axis chromatic aberration curve of the optical lens 300 are respectively as follows: Fig.10 , Fig.11 , Fig.12 shown.

[0084] from Fig.10 It can be seen that the F-Tan (Theta) distortion of the optical lens 300 is controlled within -40%~0%, indicating that the distortion of the optical lens 300 is well corrected.

[0085] from Fig.11 It can be seen that the field curvature of the meridian image plane and the sagittal image plane is controlled within ±0.1 mm, indicating that the optical lens 300 can correct the field curvature well.

[0086] from Fig.12 It can be seen that the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±4μm, indicating that the optical lens 300 can extremely well correct the chromatic aberration of the edge field of view and the secondary spectrum of the entire image plane.

[0087] 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.

[0088] Table 4-1 Table 4-2 In summary of the above embodiments, the optical lens provided by the present invention uses six lenses with specific optical focal lengths and specific surface shapes, so that the lens has one or more advantages such as 4K high-definition imaging, short total length, day and night cofocal distance, etc.

[0089] 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.

[0090] 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 is composed of six lenses with optical power, and successively includes from the object side to the imaging surface along the optical axis: A first lens with negative optical power, whose object side is convex and whose image side is concave; A second lens with negative optical power, whose object side is concave and whose image side is convex near the optical axis; A third lens with negative optical power, whose object side is concave and whose image side is convex; A fourth lens with positive optical power, whose object side is convex and whose image side is concave; A fifth lens with negative optical power, whose object side is convex and whose image side is concave; A sixth lens with positive optical power, whose object side is convex and whose image side is convex; Wherein, the total optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 5 < TTL / f < 7; the maximum field of view FOV of the optical lens and the f-number Fno of the optical lens satisfy: 65° < FOV / Fno < 75°.

2. The optical lens according to claim 1, characterized in that: 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: 2.5 < TTL / IH < 3; 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: 3.2 < IH / EPD < 4.

3. The optical lens according to claim 1, characterized in that: The back focal length BFL of the optical lens and the effective focal length f of the optical lens satisfy: 1.2 < BFL / f < 1.7; the sum ΣCT of the central thicknesses of the first lens to the sixth lens along the optical axis respectively and the effective focal length f of the optical lens satisfy: 2.7 < ΣCT / f < 3.

8.

4. The optical lens according to claim 1, characterized in that: The focal length f1 of the first lens and the effective focal length f of the optical lens satisfy: -2.6 < f1 / f < -1.5; the curvature radius R2 of the image side of the first lens and the effective focal length f of the optical lens satisfy: 0.8 < R2 / f < 1.

1.

5. 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 f456 of the fourth lens, the fifth lens and the sixth lens satisfy: -1.5 < f123 / f456 < -0.

6.

6. The optical lens according to claim 1, characterized in that: The curvature radius R5 of the object side of the third lens and the effective focal length f of the optical lens satisfy: -1.7 < R5 / f < -0.7; the curvature radius R6 of the image side of the third lens and the effective focal length f of the optical lens satisfy: -4 < R6 / f < -0.

95.

7. The optical lens according to claim 1, characterized in that: The curvature radius R7 of the object side of the fourth lens and the effective focal length f of the optical lens satisfy: 1.2 < R7 / f < 1.9; the curvature radius R8 of the image side of the fourth lens and the effective focal length f of the optical lens satisfy: 4 < R8 / f < 24.

7.

8. The optical lens according to claim 1, characterized in that: The curvature radius R9 of the object side of the fifth lens and the effective focal length f of the optical lens satisfy: 1.1 < R9 / f < 2.4; the curvature radius R10 of the image side of the fifth lens and the effective focal length f of the optical lens satisfy: 0.4 < R10 / f < 0.

7.

9. The optical lens according to claim 1, characterized in that: The radius of curvature R4 of the image side surface of the second lens and the radius of curvature R5 of the object side surface of the third lens satisfy: 0.3 < (R4 - R5) / (R4 + R5) < 1; 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) / (R7 + R8) < -0.

1.

10. The optical lens according to claim 1, characterized in that: The sagittal height Sag7 of the object side surface clear aperture of the fourth lens and the clear aperture diameter d7 of the object side surface of the fourth lens satisfy: 0.1 < Sag7 / d7 < 0.4; the sagittal height Sag8 of the image side surface clear aperture of the fourth lens and the clear aperture diameter d8 of the image side surface of the fourth lens satisfy: 0 < Sag8 / d8 < 0.2.

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