Optical lens

Abstract

The invention provides an optical lens, which comprises six lenses in total, and sequentially comprises a first lens with negative focal power, a second lens with negative focal power, a third lens with negative focal power, a fourth lens with negative focal power, a fifth lens with negative focal power and a sixth lens with negative focal power from an object side to an imaging surface along an optical axis, the image side surface of the second lens 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 convex surface; the object side surface of the fifth lens is a concave surface, and the image side surface of the fifth lens is a concave surface; 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, through specific surface shape matching and reasonable focal power distribution, the lens has one or more advantages of a large field angle, a large aperture, miniaturization and the like while realizing a good infrared confocal effect.

Description

Technical Field

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

[0002] Due to differences in application environments, consumers have different performance requirements for lenses, but the overall requirements are getting higher and higher. In some application scenarios with complex environments, it is not only required that the lens does not defocus under conditions of large temperature differences between high and low temperatures, but also that it can meet the shooting requirements both during the day and at night. Therefore, today's lenses are constantly developing in the direction of lower cost, high-definition image quality, small size, and day-night confocal, and accordingly, a new architecture of day-night confocal lenses has become an object to be developed. Summary of the Invention

[0003] Aiming at the above problems, the purpose of the present invention is to provide an optical lens, which has the advantages of infrared confocal and excellent imaging quality.

[0004] The present invention provides an optical lens, which has a total of six lenses, and successively includes, along the optical axis from the object side to the imaging surface: A first lens with negative optical power, whose object side is convex and whose image side is concave; A second lens with positive optical power, whose image side is convex; 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 convex; A fifth lens with negative optical power, whose object side is concave and whose image side is concave; A sixth lens with positive optical power, whose object side is convex and whose image side is convex; The effective focal length f of the optical lens, the maximum field of view FOV of the optical lens, and the true image height IH corresponding to the maximum field of view of the optical lens satisfy: 60° < (f × FOV) / IH < 75°.

[0005] Further preferably, the effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -1.6 < f1 / f < -1.2.

[0006] Further preferably, the effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: -2 < f5 / f < -1.7.

[0007] Further preferably, the effective focal length f of the optical lens and the focal length f6 of the sixth lens satisfy: 1.7 < f6 / f < 1.9.

[0008] Further preferably, the sagittal height SAG51 of the clear aperture radius on the object side of the fifth lens and the central thickness CT5 of the fifth lens satisfy: -1.2 < SAG51 / CT5 < -0.8.

[0009] Further preferably, the back focal length BFL of the optical lens and the total optical length TTL of the optical lens satisfy: 0.25 < BFL / TTL < 0.35.

[0010] Further preferably, the maximum field of view FOV of the optical lens and the f-number Fno of the optical lens satisfy: 70° < FOV / Fno < 90°.

[0011] Further preferably, the radius of curvature R3 of the object side of the second lens and the radius of curvature R4 of the image side of the second lens satisfy: 0.7 < (R3 + R4) / (R3 - R4) < 1.4.

[0012] Further preferably, the Abbe number Vd1 of the first lens, the Abbe number Vd2 of the second lens, the Abbe number Vd3 of the third lens, the Abbe number Vd4 of the fourth lens, and the Abbe number Vd5 of the fifth lens satisfy: 50 < Vd1 < 55; 20 < Vd2 < 25; 52 < Vd3 < 58; 85 < Vd4 < 95; 20 < Vd5 < 25; the refractive index Nd1 of the first lens, the refractive index Nd2 of the second lens, the refractive index Nd3 of the third lens, the refractive index Nd4 of the fourth lens, and the refractive index Nd5 of the fifth lens satisfy: 1.7 < Nd1 < 1.8; 1.6 < Nd2 < 1.7; 1.5 < Nd3 < 1.6; 1.4 < Nd4 < 1.5; 1.6 < Nd5 < 1.7.

[0013] Further preferably, the Abbe number Vd6 and the refractive index Nd6 of the sixth lens satisfy: 52 < Vd6 < 58; 1.5 < Nd6 < 1.6.

[0014] The optical lens provided by the present invention uses six lenses with specific optical powers. Through specific surface shape combinations and reasonable optical power distributions, it can improve the imaging quality of the optical lens, reduce aberration, and improve the imaging quality of the optical lens, enabling the lens to have one or more advantages such as a large field of view, a large aperture, and miniaturization while achieving a good infrared confocal effect. 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, where: Figure 1 It is a schematic structural diagram of the optical lens in Embodiment 1 of the present invention.

[0016] Figure 2 It is the field curvature curve graph of the optical lens in Embodiment 1 of the present invention.

[0017] Figure 3 It is the axial aberration curve graph of the optical lens in Embodiment 1 of the present invention.

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

[0019] Figure 5 It is the MTF curve graph of the optical lens in Embodiment 1 of the present invention with wavelengths from 430nm to 650nm.

[0020] Figure 6 It is the MTF curve graph of the optical lens in Embodiment 1 of the present invention with a wavelength of 940nm.

[0021] Figure 7 It is the structural schematic diagram of the optical lens in Embodiment 2 of the present invention.

[0022] Figure 8 It is the field curvature curve graph of the optical lens in Embodiment 2 of the present invention.

[0023] Figure 9 It is the axial aberration curve graph of the optical lens in Embodiment 2 of the present invention.

[0024] Figure 10 It is the lateral chromatic aberration curve graph of the optical lens in Embodiment 2 of the present invention.

[0025] Figure 11 It is the MTF curve graph of the optical lens in Embodiment 2 of the present invention with wavelengths from 430nm to 650nm.

[0026] Figure 12 It is the MTF curve graph of the optical lens in Embodiment 2 of the present invention with a wavelength of 940nm.

[0027] Figure 13 It is the structural schematic diagram of the optical lens in Embodiment 3 of the present invention.

[0028] Figure 14 It is the field curvature curve graph of the optical lens in Embodiment 3 of the present invention.

[0029] Figure 15 It is the axial aberration curve graph of the optical lens in Embodiment 3 of the present invention.

[0030] Figure 16 It is the lateral chromatic aberration curve graph of the optical lens in Embodiment 3 of the present invention.

[0031] Figure 17 It is the MTF curve graph of the optical lens in Embodiment 3 of the present invention with wavelengths from 430nm to 650nm.

[0032] Figure 18 This is the MTF curve graph of the optical lens at a wavelength of 940 nm in Embodiment 3 of the present invention.

[0033] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. Specific Embodiments

[0034] To better understand the present application, more detailed descriptions of various aspects of the present application will be made 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 do not 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.

[0035] It should be noted that in this specification, the expressions such as 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 teachings of the present invention, the first lens discussed below may also be referred to as the second lens or the third lens.

[0036] In the drawings, for the sake of clarity, the thickness, dimensions and shape of the lenses have been slightly exaggerated. Specifically, the spherical or aspherical shapes shown in the drawings are shown by way of example. That is, the spherical or aspherical shapes are not limited to the spherical or aspherical shapes shown in the drawings. The drawings are only examples and are not drawn to an exact scale.

[0037] In this document, 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 to be photographed is called the object side surface of the lens, and the surface of each lens closest to the imaging surface is called the image side surface of the lens.

[0038] It should also be understood that the terms "comprises", "comprising", "has", "including" and / or "including having", when used in this specification, indicate the presence of the stated features, elements and / or components, but do not preclude the presence or addition of one or more other features, elements, components and / or combinations thereof. In addition, when an expression such as "at least one of..." appears after a list of listed features, it modifies the entire list of listed features rather than an individual element in the list. In addition, when describing the embodiments of the present application, the use of "may" means "one or more embodiments of the present application". And the term "exemplary" is intended to refer to an example or illustration.

[0039] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It should also be understood that terms (such as those defined in a common dictionary) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0040] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments may be combined with each other. The following will describe this application in detail with reference to the drawings and in combination with the embodiments.

[0041] The optical lens according to the embodiment of the present invention sequentially includes, along the optical axis from the object side to the imaging surface: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens.

[0042] In some embodiments, the first lens may have a negative optical power, its object side is convex, and its image side is concave. The second lens may have a positive optical power, its object side may be concave or convex, and its image side is convex. The third lens may have a negative optical power, its object side is concave, and its image side is convex. The fourth lens may have a positive optical power, its object side is convex, and its image side is convex. The fifth lens may have a negative optical power, its object side is concave, and its image side is concave. The sixth lens may have a positive optical power, its object side is convex, and its image side is convex.

[0043] In some embodiments, the optical lens may further include a diaphragm, and the diaphragm may be located between the third lens and the fourth lens. It can be understood that the diaphragm is used to limit the amount of incident light to change the brightness of the image. In addition, when the diaphragm is located between the third lens and the fourth lens, the diaphragm can reasonably distribute the functions of the first lens to the sixth lens. For example, the first lens, the second lens, and the third lens can be used to receive light to a greater extent, and the fourth lens to the sixth lens can be used to correct aberrations, which is beneficial to balancing the structure of the entire optical system. In addition, when the diaphragm is located between the third lens and the fourth lens, it is convenient to correct the diaphragm aberration.

[0044] In some embodiments, the optical lens may further include a filter, and the filter may be disposed between the sixth lens and the imaging surface. The filter is used to filter out interfering light to prevent the interfering light from reaching the imaging surface of the optical lens and affecting normal imaging.

[0045] In some embodiments, the effective focal length f of the optical lens, the maximum field of view FOV of the optical lens, and the true image height IH corresponding to the maximum field of view of the optical lens satisfy: 60° < (f × FOV) / IH < 75°. By satisfying the above range and reasonably restricting the relationship among the focal length, field of view, and image height of the optical lens, the optical lens has good optical performance and can well capture the details of the object to be photographed.

[0046] In some embodiments, the effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -1.6 < f1 / f < -1.2. By satisfying the above range, the first lens has an appropriate negative focal length, which is beneficial to expanding the field of view of the optical lens.

[0047] In some embodiments, the effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: -2 < f5 / f < -1.7. By satisfying the above range, the fifth lens has an appropriate negative focal length, which is beneficial to increasing the imaging area of the optical lens, balancing various aberrations generated by the fifth lens, and improving the imaging quality of the optical lens.

[0048] In some embodiments, the effective focal length f of the optical lens and the focal length f6 of the sixth lens satisfy: 1.7 < f6 / f < 1.9. By satisfying the above range, the sixth lens has a positive optical power, which can further focus light, optimize the imaging quality, and correct the remaining aberrations (such as distortion, chromatic aberration, etc.), thereby ensuring the imaging clarity and color reproduction.

[0049] In some embodiments, the sagittal height SAG51 of the clear aperture semi-diameter on the object side of the fifth lens and the central thickness CT5 of the fifth lens satisfy: -1.2 < SAG51 / CT5 < -0.8. By satisfying the above range and appropriately adjusting the ratio of the sagittal height to the thickness of the fifth lens, it is beneficial to lens manufacturing and molding, improving the manufacturing yield, and shortening the total length of the optical lens.

[0050] In some embodiments, the back focal length BFL of the optical lens and the total optical length TTL of the optical lens satisfy: 0.25 < BFL / TTL < 0.35. By satisfying the above range, it is beneficial to balance between obtaining good imaging quality and an optical back focal length that is easy to assemble, ensuring the imaging quality of the optical lens while avoiding interference with other components and reducing the assembly process difficulty of the camera module.

[0051] In some embodiments, the maximum field of view FOV of the optical lens and the f-number Fno of the optical lens satisfy: 70° < FOV / Fno < 90°. By satisfying the above range, the lens can increase the light flux through a large aperture and make the lens more compact.

[0052] In some embodiments, the radius of curvature R3 of the object side surface of the second lens and the radius of curvature R4 of the image side surface of the second lens satisfy: 0.7 < (R3 + R4) / (R3 - R4) < 1.4. Satisfying the above range can 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.

[0053] In some embodiments, the Abbe number Vd1 of the first lens, the Abbe number Vd2 of the second lens, the Abbe number Vd3 of the third lens, the Abbe number Vd4 of the fourth lens, and the Abbe number Vd5 of the fifth lens satisfy: 50 < Vd1 < 55; 20 < Vd2 < 25; 52 < Vd3 < 58; 85 < Vd4 < 95; 20 < Vd5 < 25; the refractive index Nd1 of the first lens, the refractive index Nd2 of the second lens, the refractive index Nd3 of the third lens, the refractive index Nd4 of the fourth lens, and the refractive index Nd5 of the fifth lens satisfy: 1.7 < Nd1 < 1.8; 1.6 < Nd2 < 1.7; 1.5 < Nd3 < 1.6; 1.4 < Nd4 < 1.5; 1.6 < Nd5 < 1.7. Satisfying the above range, by pairing low Abbe number lenses and high Abbe coefficient lenses, axial chromatic aberration can be offset, which is beneficial to achieving infrared confocal.

[0054] In some embodiments, the Abbe number Vd6 and the refractive index Nd6 of the sixth lens satisfy: 52 < Vd6 < 58; 1.5 < Nd6 < 1.6. Satisfying the above range, using a high Abbe coefficient and low infrared dispersion material in the last lens can reduce the focus shift at 940 nm and correct infrared resolution.

[0055] In some embodiments, the overall optical length TTL of the optical lens and the central thickness CT3 of the third lens satisfy: 6.5 < TTL / CT3 < 8.5. Satisfying the above range, by controlling the ratio relationship between the central thickness and the overall length of the third lens, the third lens can be prevented from being too thick, and high-order spherical aberration or dispersion caused by excessive refraction can be avoided.

[0056] In some embodiments, the sagittal height SAG21 of the object side clear aperture semi-diameter of the second lens and the sagittal height SAG22 of the image side clear aperture semi-diameter of the second lens satisfy: 0.5 < SAG21 - SAG22 < 0.68. Satisfying the above range, by controlling the relationship between the vector height of the image side and the sagittal height of the object side of the second lens, it is beneficial to constrain the shape of the second lens and reasonably control the lens opening angle of the second lens, which is further beneficial to improving the processability of the lens. In addition, by reasonably constraining the lens shape of the second lens, the risk of ghosting generated by the second lens can be effectively reduced.

[0057] 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: 10 < R1 / R2 < 18. Satisfying the above range and reasonably setting the radii of curvature of the object side surface and the image side surface of the first lens helps to achieve a larger field of view angle.

[0058] In some embodiments, the radius of curvature R11 of the object side surface of the sixth lens and the radius of curvature R12 of the image side surface of the sixth lens satisfy: -1 < R11 / R12 < -0.8. Satisfying the above range and reasonably setting the radius of curvature of the sixth lens can correct the aberration of the optical lens and reduce the tolerance sensitivity of the optical lens.

[0059] In some embodiments, the radius of curvature R9 of the object side surface of the fifth lens and the radius of curvature R10 of the image side surface of the fifth lens satisfy: 0.24 < (R9 + R10) / (R9 - R10) < 0.42. Satisfying the above range and reasonably controlling the radii of curvature of the object side surface and the image side surface of the fifth lens near the optical axis is beneficial to controlling the shape of the fifth lens, correcting the aberration generated by itself, and improving the imaging quality.

[0060] In some embodiments, the radius of curvature R11 of the object side surface of the sixth lens and the radius of curvature R12 of the image side surface of the sixth lens satisfy: -0.1 < (R11 + R12) / (R11 - R12) < 0. Satisfying the above range can control the light direction, reduce spherical aberration, correct coma, increase light utilization rate, and improve stability.

[0061] In some embodiments, the focal length f1 of the first lens, the focal length f2 of the second lens, the focal length f3 of the third lens, the focal length f4 of the fourth lens, the focal length f5 of the fifth lens, and the focal length f6 of the sixth lens satisfy: -0.45 < f1 / f2 < -0.35; -0.52 < f2 / f3 < -0.05; -19 < f3 / f4 < -3; -1.5 < f4 / f5 < -0.9; -1.15 < f5 / f6 < -0.9; -0.9 < f1 / f6 < -0.65. Satisfying the above range and forming a positive-negative optical power combination can improve the temperature drift stability performance of the lens, help reduce the influence of environmental temperature on the lens group, and also meet the compactness requirements of the lens.

[0062] In some embodiments, the central thickness CT3 of the third lens and the central thickness CT4 of the fourth lens satisfy: 0.95 < CT3 / CT4 < 1. Satisfying the above range enables a reasonable configuration of the ratio of the thickness of the third lens on the optical axis to the thickness of the fourth lens on the optical axis. The third lens and the fourth lens can regulate each other to maintain the characteristics of miniaturization of the optical system.

[0063] In some embodiments, the central thickness CT1 of the first lens and the central thickness CT6 of the sixth lens satisfy: 0.25 < CT1 / CT6 < 0.35. Meeting the above range controls the thickness ratio of the first and last lenses, balancing the structural strength, light path convergence efficiency, and aberration correction ability.

[0064] In some embodiments, the sum ∑CT of the central thicknesses of the first lens to the sixth lens along the optical axis and the total optical length TTL of the optical lens satisfy: 0.5 < ∑CT / TTL < 0.6. Meeting the above range can effectively compress the total length of the optical lens and is beneficial to the structural design and production process of the optical lens.

[0065] In some embodiments, the clear aperture radius DM11 of the object side of the first lens and the clear aperture radius DM62 of the image side of the sixth lens satisfy: 1.2 < DM11 / DM62 < 1.5. Meeting the above range, by reasonably setting the aperture ratio of the first and last lenses, the lens can have a smaller head size while having a larger imaging surface, better meeting the balance of miniaturization and high pixels.

[0066] In some embodiments, the optical lens satisfies the following conditional expressions: 3mm < f < 3.5mm; 130° < FOV < 145°; 19mm < TTL < 26mm; 6.3mm < IH < 6.6mm; 1.6 ≤ Fno ≤ 1.8; 13° < CRA < 15°. 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, TTL represents the total optical length of the optical lens, IH represents the true image height corresponding to the maximum field of view angle of the optical lens, Fno represents the aperture value of the optical lens, and CRA represents the principal ray incident angle at the maximum image height. Meeting the above range, the optical lens has at least one or more advantages such as a large aperture, ultra-wide angle, and miniaturization.

[0067] In some embodiments, the six lenses in the optical lens can all be made of plastic lenses or adopt a glass-plastic hybrid material structure. Preferably, the optical lens of the present invention adopts a six-piece glass-plastic hybrid lens structure, which can improve the thermal stability performance. 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 a glass-plastic hybrid structure can effectively reduce costs, correct aberrations, reduce volume, and provide an optical lens product with higher cost performance.

[0068] In some embodiments, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens may be 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, in the optical lens provided by the present invention, the first lens and the fourth lens are spherical lenses; the second lens, the third lens, the fifth lens, and the sixth lens are all aspherical lenses.

[0069] In various embodiments of the present invention, when the lens is an aspherical lens, the shapes of the aspherical surfaces of the optical lens satisfy the following equation: ; where z is the distance between the curved surface and the vertex of the curved surface in the optical axis direction, h is the distance from the optical axis to the curved surface, c is the curvature of the vertex of the curved surface, K is the conic coefficient, and B, C, D, E, and F are the coefficients of the fourth-order, sixth-order, eighth-order, tenth-order, and twelfth-order curved surfaces respectively.

[0070] The present invention will be further described in multiple embodiments below. In each embodiment, the thickness, radius of curvature, and material selection of each lens in the optical lens are slightly different. For specific differences, please refer to the parameter tables of each embodiment. The following embodiments are only the preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the following embodiments only. Any 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.

[0071] Embodiment 1 Please refer to Figure 1 , which shows a schematic structural diagram of the optical lens 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, a fifth lens L5, a sixth lens L6, and a filter G1.

[0072] Among them, the first lens L1 has a negative optical power. Its object side surface S1 is a convex surface, and its image side surface S2 is a concave surface; The second lens L2 has a positive optical power. Its object side surface S3 is a convex surface near the optical axis, and its image side surface S4 is a convex surface; The third lens L3 has a negative optical power. Its object side surface S5 is a concave surface, and its image side surface S6 is a convex surface; The fourth lens L4 has a positive optical power. Its object side surface S7 is a convex surface, and its image side surface S8 is a convex surface; The fifth lens L5 has a negative optical power. Its object side surface S9 is a concave surface, and its image side surface S10 is a concave surface; The sixth lens L6 has a positive optical power, its object side S11 is convex, and its image side S12 is convex; Both the object side S13 and the image side S14 of the filter G1 are flat; The imaging surface S15 is flat.

[0073] The first lens L1 and the fourth lens L4 are made of glass spherical lenses; the second lens L2, the third lens L3, the fifth lens L5, and the sixth lens L6 are all made of plastic aspherical lenses.

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

[0075] Table 1-1 The surface shape parameters of the aspherical lenses of the optical lens in Embodiment 1 are shown in Table 1-2.

[0076] Table 1-2 In this embodiment, the field curvature curve graph, the axial aberration curve graph, the lateral chromatic aberration curve graph, the MTF curve graph with wavelengths from 430nm to 650nm, and the MTF curve graph with a wavelength of 940nm of the optical lens are respectively as Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 shown.

[0077] Figure 2 shows the field curvature curve of Embodiment 1, which represents the bending degree of light rays in the meridional image plane and the sagittal image plane. The horizontal axis represents the offset (unit: mm), and the vertical axis represents the semi-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 to 0.02mm, indicating that the optical lens can correct the field curvature well.

[0078] Figure 3 shows the axial aberration curve graph of Embodiment 1, which represents the aberration of each wavelength on the optical axis at the imaging surface. 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 -0.02mm to 0.04mm, indicating that the optical lens can correct the axial aberration well.

[0079] Figure 4The vertical chromatic aberration curve diagram of Embodiment 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 of view 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 - 4 μm, indicating that this optical lens can correct chromatic aberration well.

[0080] Figure 5 The MTF (Modulation Transfer Function) curve diagram of wavelengths from 430 nm to 650 nm of Embodiment 1 is shown, which represents the modulation of lens imaging at different spatial frequencies under each field of view for wavelengths from 430 nm to 650 nm. 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 0.35 within the entire field of view. In the range of 0 - 120 lp / mm, the MTF curve decreases uniformly and smoothly from the central field of view to the edge field of view, and has good imaging quality and good detail resolution ability in both low-frequency and high-frequency cases.

[0081] Figure 6 The MTF curve diagram of wavelength 940 nm of Embodiment 1 is shown, which represents the modulation of lens imaging at different spatial frequencies under each field of view for wavelength 940 nm. 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 the optical lens of this embodiment is above 0.58 within the entire field of view in the infrared band. In the range of 0 - 120 lp / mm, the MTF curve decreases uniformly and smoothly from the central field of view to the edge field of view, and has good imaging quality and good detail resolution ability in both low-frequency and high-frequency cases.

[0082] Embodiment 2 Please refer to Figure 7 , which shows the structural schematic diagram of the optical lens provided in Embodiment 2 of the present invention. Compared with Embodiment 1, the main difference is that: the object side surface S3 of the second lens L2 is a concave surface, and the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0083] The relevant parameters of each lens in the optical lens of Embodiment 2 are shown in Table 2 - 1.

[0084] Table 2 - 1 The surface type parameters of the aspherical lens in the optical lens of Embodiment 2 are shown in Table 2 - 2.

[0085] Table 2 - 2 In this embodiment, the field curvature curve graph, axial aberration curve graph, lateral chromatic aberration curve graph, MTF curve graph with wavelengths from 430 nm to 650 nm, and MTF curve graph with a wavelength of 940 nm of the optical lens are respectively as follows Figure 8 , Figure 9 , Figure 10 , Figure 11 , Figure 12 .

[0086] It can be seen from Figure 8 that the field curvature of the meridional image plane and the sagittal image plane is controlled within -0.04 mm to 0.02 mm, indicating that the optical lens can correct the field curvature well.

[0087] It can be seen from Figure 9 that the offset of the axial aberration is controlled within -0.02 mm to 0.04 mm, indicating that the optical lens can correct the axial aberration better.

[0088] It can be seen from Figure 10 that the lateral chromatic aberration between the longest wavelength and the shortest wavelength is controlled within 0 to 4 μm, indicating that the optical lens can correct the chromatic aberration better.

[0089] It can be seen from Figure 11 that the MTF value of this embodiment is above 0.38 within the entire field of view. In the range of 0 to 120 lp / mm, the MTF curve smoothly decreases uniformly 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 cases.

[0090] It can be seen from Figure 12 that the MTF value of the optical lens in this embodiment is above 0.5 within the entire field of view in the infrared band. In the range of 0 to 120 lp / mm, the MTF curve smoothly decreases uniformly 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 cases.

[0091] Embodiment 3 Please refer to Figure 13 , which shows the structural schematic diagram of the optical lens provided in Embodiment 3 of the present invention. Compared with Embodiment 1, the main difference is that the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

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

[0093] Table 3-1 The surface type parameters of the aspherical lens of the optical lens in Embodiment 3 are shown in Table 3-2.

[0094] Table 3-2 In this embodiment, the field curvature curve graph, axial aberration curve graph, lateral chromatic aberration curve graph, MTF curve graph with wavelengths from 430 nm to 650 nm, and MTF curve graph with wavelength 940 nm of the optical lens are respectively as Figure 14 , Figure 15 , Figure 16 , Figure 17 , Figure 18 shown.

[0095] From Figure 14 , it can be seen that the field curvature of the meridional image plane and the sagittal image plane is controlled within -0.04 mm to 0.02 mm, indicating that the optical lens can correct the field curvature well.

[0096] From Figure 15 , it can be seen that the offset of the axial aberration is controlled within -0.02 mm to 0.03 mm, indicating that the optical lens can correct the axial aberration better.

[0097] From Figure 16 , it can be seen that the lateral chromatic aberration between the longest wavelength and the shortest wavelength is controlled within 0 to 3 μm, indicating that the optical lens can correct the chromatic aberration better.

[0098] From Figure 17 , it can be seen that the MTF value of this embodiment is above 0.4 in the entire field of view. In the range of 0 to 120 lp / mm, the MTF curve smoothly decreases uniformly 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 cases.

[0099] From Figure 18 , it can be seen that the MTF value of the optical lens in this embodiment is above 0.55 in the entire field of view in the infrared band. In the range of 0 to 120 lp / mm, the MTF curve smoothly decreases uniformly 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 cases.

[0100] Please refer to Table 4 for the optical characteristics corresponding to the above embodiments, including the effective focal length f, total optical length TTL, aperture value Fno, true image height IH corresponding to the maximum field of view angle, maximum field of view angle FOV, chief ray angle of incidence CRA at the maximum image height, and the values corresponding to each conditional formula in each embodiment.

[0101] Table 4 In summary of the above embodiments, the optical lens provided by the present invention uses six lenses with specific optical powers. Through specific surface shape matching and reasonable optical power distribution, it can improve the imaging quality of the optical lens, reduce aberration, and enhance the imaging quality of the optical lens, enabling the lens to have one or more advantages such as a large field of view, a large aperture, and miniaturization while achieving a good infrared confocal effect.

[0102] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0103] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent of the present invention shall be subject to the appended claims.

Claims

1. An optical lens, consisting of six lenses in total, characterized in that, From the object side to the imaging plane along the optical axis, it successively includes: A first lens with a negative optical power, whose object side is convex and whose image side is concave; A second lens with a positive optical power, whose image side is convex; 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 convex; A fifth lens with a negative optical power, whose object side is concave and whose image side is concave; A sixth lens with a positive optical power, whose object side is convex and whose image side is convex; Wherein, the effective focal length f of the optical lens, the maximum field of view angle FOV of the optical lens, and the true image height IH corresponding to the maximum field of view angle of the optical lens satisfy: 60° < (f × FOV) / IH < 75°.

2. The optical lens according to claim 1, wherein The effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -1.6 < f1 / f < -1.

2.

3. 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: -2 < f5 / f < -1.

7.

4. The optical lens according to claim 1, characterized in that, The effective focal length f of the optical lens and the focal length f6 of the sixth lens satisfy: 1.7 < f6 / f < 1.

9.

5. The optical lens according to claim 1, wherein The sagittal height SAG51 of the clear aperture semi-diameter on the object side of the fifth lens and the central thickness CT5 of the fifth lens satisfy: -1.2 < SAG51 / CT5 < -0.

8.

6. The optical lens according to claim 1, characterized in that, The back focal length BFL of the optical lens and the total optical length TTL of the optical lens satisfy: 0.25 < BFL / TTL < 0.

35.

7. The optical lens according to claim 1, characterized in that The maximum field of view angle FOV of the optical lens and the f-number Fno of the optical lens satisfy: 70° < FOV / Fno < 90°.

8. The optical lens according to claim 1, wherein The radius of curvature R3 of the object side of the second lens and the radius of curvature R4 of the image side of the second lens satisfy: 0.7 < (R3 + R4) / (R3 - R4) < 1.

4.

9. The optical lens according to claim 1, characterized in that, The Abbe number Vd1 of the first lens, the Abbe number Vd2 of the second lens, the Abbe number Vd3 of the third lens, the Abbe number Vd4 of the fourth lens, and the Abbe number Vd5 of the fifth lens satisfy: 50 < Vd1 < 55; 20 < Vd2 < 25; 52 < Vd3 < 58; 85 < Vd4 < 95; 20 < Vd5 < 25; the refractive index Nd1 of the first lens, the refractive index Nd2 of the second lens, the refractive index Nd3 of the third lens, the refractive index Nd4 of the fourth lens, and the refractive index Nd5 of the fifth lens satisfy: 1.7 < Nd1 < 1.8; 1.6 < Nd2 < 1.7; 1.5 < Nd3 < 1.6; 1.4 < Nd4 < 1.5; 1.6 < Nd5 < 1.

7.

10. The optical lens according to claim 1, characterized in that, The Abbe number Vd6 of the sixth lens and the refractive index Nd6 of the sixth lens satisfy: 52 < Vd6 < 58; 1.5 < Nd6 < 1.6.

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