Optical lens

Abstract

The present invention provides an optical lens having a total of six lenses, which include, along the optical axis from the object side to the imaging surface, a first lens having negative optical power, whose object side surface is convex and whose image side surface is concave; a second lens having positive optical power, whose image side surface is convex; a third lens having negative optical power, whose object side surface is concave and whose image side surface is convex; a fourth lens having positive optical power, whose object side surface is convex and whose image side surface is convex; a fifth lens having negative optical power, whose object side surface is concave and whose image side surface is concave; and a sixth lens having positive optical power, whose object side surface is convex and whose image side surface is convex. The optical lens provided by the present invention, through a specific surface shape combination and a reasonable optical power distribution, enables the lens to achieve a good infrared confocal effect while also having one or more advantages such as a large field of view, a large aperture, and miniaturization.

Description

Technical Field

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

[0002] Due to varying application environments, consumers' requirements for lens performance vary, but overall, these requirements are becoming increasingly demanding. In some complex applications, lenses must not only maintain focus despite significant temperature swings, but also meet shooting requirements both day and night. To this end, today's lenses are continuously evolving toward lower costs, higher-definition image quality, smaller size, and day / night parfocality. Consequently, new day / night parfocal lens architectures are becoming a hot topic for development. Summary of the Invention

[0003] In view of the above problems, the object of the present invention is to provide an optical lens having the advantages of infrared confocal and excellent imaging quality.

[0004] The present invention provides an optical lens, comprising six lenses, which include the following lenses in order from the object side to the imaging surface along the optical axis:

[0005] The first lens has a negative optical power, its object-side surface is convex and its image-side surface is concave;

[0006] a second lens having positive refractive power and a convex image-side surface;

[0007] a third lens element having negative optical power, whose object-side surface is concave and whose image-side surface is convex;

[0008] a fourth lens element having positive refractive power, whose object-side surface is convex and whose image-side surface is convex;

[0009] a fifth lens element having negative optical power, whose object-side surface and image-side surface are concave;

[0010] a sixth lens element having positive refractive power, whose object-side surface is convex and whose image-side surface is convex;

[0011] The effective focal length f of the optical lens, the maximum field of view FOV of the optical lens and the real image height IH corresponding to the maximum field of view of the optical lens satisfy the following conditions: 60°<(f×FOV) / IH<75°.

[0012] 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。

[0013] Further preferably, the effective focal length f of the optical lens and the focal length f5 of the fifth lens satisfy: <f5 / f<-1.7。

[0014] 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.

[0015] Further preferably, the sagittal height SAG51 of the object side light passing semi-aperture of the fifth lens and the central thickness CT5 of the fifth lens satisfy: -1.2 < SAG51 / CT5 < -0.8.

[0016] 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.

[0017] Further preferably, the maximum field angle FOV of the optical lens and the f-number Fno of the optical lens satisfy: 70° < FOV / Fno < 90°.

[0018] 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.

[0019] 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.

[0020] Further preferably, 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.

[0021] 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 aberrations, improve the imaging quality of the optical lens, and enable the lens to have one or more advantages such as a large field angle, a large aperture, and miniaturization while achieving a good infrared confocal effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

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

[0024] Figure 2 Graph showing the field curvature of the optical lens in Example 1 of the present invention.

[0025] Figure 3 1 is an axial aberration curve diagram of the optical lens in Example 1 of the present invention.

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

[0027] Figure 5 This is an MTF curve diagram of the optical lens in Example 1 of the present invention at a wavelength of 430nm to 650nm.

[0028] Figure 6 This is the MTF curve of the optical lens at a wavelength of 940 nm in Example 1 of the present invention.

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

[0030] Figure 8 Graph showing the field curvature of the optical lens in Example 2 of the present invention.

[0031] Figure 9 2 is an axial aberration curve diagram of the optical lens in Example 2 of the present invention.

[0032] Figure 10 Graph showing vertical axis chromatic aberration of the optical lens in Example 2 of the present invention.

[0033] Figure 11 This is an MTF curve diagram of the optical lens in Example 2 of the present invention at a wavelength of 430nm to 650nm.

[0034] Figure 12 This is the MTF curve of the optical lens at a wavelength of 940 nm in Example 2 of the present invention.

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

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

[0037] Figure 15 4 is an axial aberration curve diagram of the optical lens in Example 3 of the present invention.

[0038] Figure 16 Graph showing vertical axis chromatic aberration of the optical lens in Example 3 of the present invention.

[0039] Figure 17 This is an MTF curve diagram of the optical lens in Example 3 of the present invention at a wavelength of 430nm to 650nm.

[0040] Figure 18 This is the MTF curve of the optical lens at a wavelength of 940 nm in Example 3 of the present invention.

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

[0042] For a better understanding of the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely descriptions of embodiments of the present application and are not intended to limit the scope of the present application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0043] It should be noted that in this specification, the terms "first," "second," "third," etc., are used solely to distinguish one feature from another and do not limit the features. Thus, the first lens discussed below could also be referred to as the second lens or the third lens without departing from the teachings of the present invention.

[0044] In the drawings, the thickness, size, and shape of the lenses are slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical and aspherical surfaces shown in the drawings are provided by way of example. That is, the shapes of the spherical and aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustration only and are not drawn strictly to scale.

[0045] In this article, the paraxial region refers to the area near the optical axis. If a lens surface is convex and the location of the convex surface is undefined, it means that the lens surface is convex at least in the paraxial region. If a lens surface is concave and the location of the concave surface is undefined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the subject is called the object-side surface of the lens, and the surface of each lens closest to the imaging plane is called the image-side surface of the lens.

[0046] It should also be understood that the terms "comprises," "including," "having," "includes," and / or "comprising," when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not preclude 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 list of features rather than modifying the individual elements in the list. In addition, when describing embodiments of the present application, "may" is used to mean "one or more embodiments of the present application." And, the term "exemplary" is intended to refer to an example or illustration.

[0047] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by those skilled in the art to which this application belongs. It should also be understood that terms (such as those defined in commonly used dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology and will not be interpreted in an idealized or overly formal sense unless expressly defined as such herein.

[0048] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0049] The optical lens of the embodiment of the present invention includes, 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, a fifth lens, and a sixth lens.

[0050] In some embodiments, the first lens may have negative optical power, with its object-side surface being convex and its image-side surface being concave. The second lens may have positive optical power, with its object-side surface being either concave or convex, and its image-side surface being convex. The third lens may have negative optical power, with its object-side surface being concave and its image-side surface being convex. The fourth lens may have positive optical power, with its object-side surface being convex and its image-side surface being convex. The fifth lens may have negative optical power, with its object-side surface being concave and its image-side surface being concave. The sixth lens may have positive optical power, with its object-side surface being convex and its image-side surface being convex.

[0051] In some embodiments, the optical lens may further include an aperture, which may be located between the third and fourth lenses. It is understood that the aperture is used to limit the amount of light entering, thereby changing the brightness of the image. Furthermore, when the aperture is located between the third and fourth lenses, it can effectively distribute the functions of the first through sixth lenses. For example, the first, second, and third lenses can be used to receive a greater amount of light, while the fourth through sixth lenses can be used to correct aberrations, thus balancing the structure of the entire optical system. Furthermore, when the aperture is located between the third and fourth lenses, it facilitates the correction of aperture aberrations.

[0052] In some embodiments, the optical lens may further include a filter, which may be disposed between the sixth lens and the imaging surface. The filter is used to filter out interfering light and prevent the interfering light from reaching the imaging surface of the optical lens and affecting normal imaging.

[0053] In some embodiments, the effective focal length f of the optical lens, the maximum field angle FOV of the optical lens, and the true image height IH corresponding to the maximum field angle of the optical lens satisfy: 60° < (f × FOV) / IH < 75°. Meeting the above range, by reasonably restricting the relationship between the focal length, field angle, and image height of the optical lens, the optical lens has good optical performance and can capture the details of the photographed object well.

[0054] 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. Meeting the above range, the first lens has an appropriate negative focal length, which is beneficial to expanding the field angle of the optical lens.

[0055] 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. Meeting 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.

[0056] 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. Meeting 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 degree.

[0057] In some embodiments, 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. Meeting the above range, by 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.

[0058] 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. Meeting 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.

[0059] In some embodiments, the maximum field of view FOV of the optical lens and the aperture value Fno of the optical lens satisfy: 70° < FOV / Fno < 90°. Meeting the above range, the lens can increase the light flux through a large aperture and make the lens more compact.

[0060] In some embodiments, 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. Meeting 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.

[0061] 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. Meeting the above range, pairing low Abbe number lenses and high Abbe coefficient lenses can cancel axial chromatic aberration and is beneficial to achieving infrared confocal.

[0062] 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. Meeting 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.

[0063] In some embodiments, the total optical length TTL of the optical lens and the central thickness CT3 of the third lens satisfy: 6.5 < TTL / CT3 < 8.5. Meeting the above range, by controlling the ratio relationship between the central thickness of the third lens and the total length, it is possible to prevent the third lens from being too thick and avoid high-order spherical aberration or dispersion caused by excessive refraction.

[0064] In some embodiments, the sagittal height SAG21 of the clear aperture on the object side of the second lens and the sagittal height SAG22 of the clear aperture on the image side of the second lens satisfy: 0.5 < SAG21 - SAG22 < 0.68. Meeting the above range, by controlling the relationship between the vector height of the image side of the second lens and the sagittal height of the object side, it is beneficial to constrain the shape of the second lens and reasonably control the lens opening angle of the second lens, thereby being beneficial to improving the manufacturability of the lens. In addition, by reasonably constraining the lens shape of the second lens, the risk of ghost images generated by the second lens can be effectively reduced.

[0065] In some embodiments, the radius of curvature R1 of the object side of the first lens and the radius of curvature R2 of the image side of the first lens satisfy: 10 < R1 / R2 < 18. Meeting the above range, reasonably setting the radii of curvature of the object side and the image side of the first lens helps to achieve a larger field angle.

[0066] In some embodiments, the radius of curvature R11 of the object side of the sixth lens and the radius of curvature R12 of the image side of the sixth lens satisfy: -1 < R11 / R12 < -0.8. Meeting the above range, reasonably setting the radii of curvature of the sixth lens can correct the aberration of the optical lens and reduce the tolerance sensitivity of the optical lens.

[0067] In some embodiments, the radius of curvature R9 of the object side of the fifth lens and the radius of curvature R10 of the image side of the fifth lens satisfy: 0.24 < (R9 + R10) / (R9 - R10) < 0.42. Meeting the above range, reasonably controlling the radii of curvature of the object side and the image side 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.

[0068] In some embodiments, the radius of curvature R11 of the object side of the sixth lens and the radius of curvature R12 of the image side of the sixth lens satisfy: -0.1 < (R11 + R12) / (R11 - R12) < 0. Meeting the above range can control the light direction, reduce spherical aberration, correct coma, increase light utilization rate, and improve stability.

[0069] 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. Meeting the above range to form a positive-negative focal 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.

[0070] 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. Meeting 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, maintaining the characteristic of miniaturization of the optical system.

[0071] 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.

[0072] In some embodiments, the sum ∑CT 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 < ∑CT / TTL < 0.6. Meeting the above range can effectively compress the total length of the optical lens, while being beneficial to the structural design and production process of the optical lens. <e

[0073] In some embodiments, the clear aperture semi-diameter DM11 of the object side surface of the first lens and the clear aperture semi-diameter DM62 of the image side surface of the sixth lens satisfy: 1.2 < DM11 / DM62 < 1.5. Meeting the above range, by reasonably setting the ratio of the apertures 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.

[0074] 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 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 angle of the optical lens, Fno represents the aperture value of the optical lens, and CRA represents the chief 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.

[0075] In some embodiments, the six lenses in the optical lens can all be plastic lenses or a glass-plastic hybrid structure. Preferably, the optical lens of the present invention employs a six-lens glass-plastic hybrid structure to improve thermal stability. Specifically, the first and fourth lenses can be glass lenses, while the second, third, fifth, and sixth lenses can all be plastic lenses. The glass-plastic hybrid structure effectively reduces costs, corrects aberrations, and reduces size, providing a more cost-effective optical lens product.

[0076] In some embodiments, the first, second, third, fourth, fifth, and sixth lenses may be spherical or aspherical lenses. Compared to spherical lenses, aspherical structures can effectively reduce the aberrations of the optical system, thereby reducing the number and size of lenses and achieving better miniaturization. More specifically, in the optical lens provided by the present invention, the first and fourth lenses are spherical lenses, while the second, third, fifth, and sixth lenses are all aspherical lenses.

[0077] In various embodiments of the present invention, when the lens is an aspheric lens, the shapes of the aspheric surfaces of the optical lens satisfy the following equations:

[0078] ;

[0079] Where z is the distance between the surface and the vertex 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, and B, C, D, E, and F are the fourth-order, sixth-order, eighth-order, tenth-order, and twelfth-order surface coefficients, respectively.

[0080] The present invention is further illustrated below with reference to several embodiments. In each embodiment, the thickness, radius of curvature, and material selection of each lens in the optical lens vary; for details, please refer to the parameter tables of each embodiment. The following embodiments are merely preferred embodiments of the present invention, but the present invention is not limited thereto. Any other changes, substitutions, combinations, or simplifications that do not deviate from the novelties of the present invention shall be considered equivalent replacements and are included within the scope of protection of the present invention.

[0081] Example 1

[0082] See also Figure 1 , shown is a schematic structural diagram of the optical lens provided in Example 1 of the present invention, which 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, an aperture ST, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a filter G1.

[0083] The first lens L1 has negative refractive power, its object-side surface S1 is convex, and its image-side surface S2 is concave;

[0084] The second lens L2 has positive refractive power, its object-side surface S3 is convex near the optical axis, and its image-side surface S4 is convex;

[0085] The third lens L3 has negative refractive power, its object-side surface S5 is concave, and its image-side surface S6 is convex;

[0086] The fourth lens L4 has positive refractive power, its object-side surface S7 is convex, and its image-side surface S8 is convex;

[0087] The fifth lens L5 has negative refractive power, its object-side surface S9 is concave, and its image-side surface S10 is concave;

[0088] The sixth lens L6 has positive refractive power, its object-side surface S11 is convex, and its image-side surface S12 is convex;

[0089] The object-side surface S13 and the image-side surface S14 of the filter G1 are both flat surfaces;

[0090] The imaging surface S15 is a plane.

[0091] The first lens L1 and the fourth lens L4 are glass spherical lenses; the second lens L2, the third lens L3, the fifth lens L5, and the sixth lens L6 are plastic aspherical lenses.

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

[0093] Table 1-1

[0094]

[0095] The surface parameters of the aspheric lens of the optical lens in Example 1 are shown in Table 1-2.

[0096] Table 1-2

[0097]

[0098] In this embodiment, the field curvature curve, axial aberration curve, vertical chromatic aberration curve, MTF curve at a wavelength of 430nm to 650nm, and MTF curve at a wavelength of 940nm of the optical lens are shown as follows: Figure 2 、 Figure 3 、 Figure 4 、 Figure 5 、 Figure 6 shown.

[0099] Figure 2The field curvature curve for Example 1 shows the degree of light curvature in the meridional and sagittal image planes. The horizontal axis represents the offset (unit: mm), and the vertical axis represents the half field angle (unit: degrees). As can be seen from the figure, the field curvature in the meridional and sagittal image planes is controlled within a range of -0.04mm to 0.02mm, demonstrating that the optical lens is able to effectively correct field curvature.

[0100] Figure 3 The following graph shows the axial aberration curve for Example 1, which represents the aberration on the optical axis at the imaging plane for each wavelength. The horizontal axis represents the axial aberration value (unit: mm), and the vertical axis represents the normalized pupil radius. As can be seen from the graph, the offset of the axial aberration is controlled within a range of -0.02mm to 0.04mm, indicating that the optical lens can effectively correct axial aberration.

[0101] Figure 4 The vertical chromatic aberration curve for Example 1 shows the chromatic aberration of each wavelength relative to the central wavelength (0.555 μm) at different image heights on the imaging plane. 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. As can be seen from the graph, the vertical chromatic aberration for both the longest and shortest wavelengths is controlled within 0 to 4 μm, demonstrating that this optical lens is capable of effectively correcting chromatic aberration.

[0102] Figure 5 The MTF (Modulation Transfer Function) curves for Example 1 at wavelengths from 430 nm to 650 nm are shown. These curves represent the degree of lens imaging modulation at different spatial frequencies across the field of view from wavelengths from 430 nm to 650 nm. The horizontal axis represents spatial frequency (lp / mm), and the vertical axis represents MTF. As can be seen from the graph, the MTF values ​​for this example are consistently above 0.35 across the entire field of view. Within the range of 0 to 120 lp / mm, the MTF curve decreases evenly and smoothly from the center to the edge of the field of view, demonstrating excellent imaging quality and detail resolution at both low and high frequencies.

[0103] Figure 6 The MTF curve for Example 1 at a wavelength of 940 nm is shown. It represents the imaging modulation of the lens at different spatial frequencies across the 940 nm wavelength field of view. The horizontal axis represents spatial frequency (unit: lp / mm), and the vertical axis represents the MTF value. As can be seen from the graph, the optical lens of this embodiment maintains an MTF value of 0.58 or higher across the entire field of view in the infrared band. Within the range of 0 to 120 lp / mm, the MTF curve decreases evenly and smoothly from the center to the edge of the field of view, demonstrating excellent imaging quality and detail resolution at both low and high frequencies.

[0104] Example 2

[0105] See also Figure 7, shown is a schematic structural diagram of the optical lens provided in Example 2 of the present invention. Compared with Example 1, this embodiment mainly differs in that the object-side surface S3 of the second lens L2 is concave, and the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0106] The relevant parameters of each lens in the optical lens in Example 2 are shown in Table 2-1.

[0107] Table 2-1

[0108]

[0109] The surface parameters of the aspheric lens of the optical lens in Example 2 are shown in Table 2-2.

[0110] Table 2-2

[0111]

[0112] In this embodiment, the field curvature curve, axial aberration curve, vertical chromatic aberration curve, MTF curve at a wavelength of 430nm to 650nm, and MTF curve at a wavelength of 940nm of the optical lens are shown as follows: Figure 8 、 Figure 9 、 Figure 10 、 Figure 11 、 Figure 12 shown.

[0113] from Figure 8 It can be seen that the field curvature of the meridional image plane and the sagittal image plane is controlled within -0.04mm~0.02mm, indicating that the optical lens can correct the field curvature well.

[0114] from Figure 9 It can be seen that the offset of axial aberration is controlled within -0.02mm~0.04mm, which shows that the optical lens can correct axial aberration well.

[0115] from Figure 10 It can be seen that the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within 0~4μm, indicating that the optical lens can correct chromatic aberration well.

[0116] from Figure 11 As can be seen, the MTF value of this embodiment is above 0.38 throughout the entire field of view. In the range of 0 to 120 lp / mm, the MTF curve decreases evenly and smoothly from the center to the edge of the field of view, demonstrating good imaging quality and detail resolution at both low and high frequencies.

[0117] from Figure 12As can be seen from the figure, the optical lens of this embodiment has an MTF value of above 0.5 throughout the entire field of view in the infrared band. In the range of 0 to 120 lp / mm, the MTF curve decreases evenly and smoothly from the center to the edge of the field of view, demonstrating good imaging quality and detail resolution in both low-frequency and high-frequency conditions.

[0118] Example 3

[0119] See also Figure 13 , shown is a schematic structural diagram of the optical lens provided in Example 3 of the present invention. Compared with Example 1, the main difference between this embodiment is that the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0120] The relevant parameters of each lens in the optical lens in Example 3 are shown in Table 3-1.

[0121] Table 3-1

[0122]

[0123] The surface parameters of the aspheric lens of the optical lens in Example 3 are shown in Table 3-2.

[0124] Table 3-2

[0125]

[0126] In this embodiment, the field curvature curve, axial aberration curve, vertical chromatic aberration curve, MTF curve at a wavelength of 430nm to 650nm, and MTF curve at a wavelength of 940nm of the optical lens are shown as follows: Figure 14 、 Figure 15 、 Figure 16 、 Figure 17 、 Figure 18 shown.

[0127] from Figure 14 It can be seen that the field curvature of the meridional image plane and the sagittal image plane is controlled within -0.04mm~0.02mm, indicating that the optical lens can correct the field curvature well.

[0128] from Figure 15 It can be seen that the offset of axial aberration is controlled within -0.02mm~0.03mm, which shows that the optical lens can correct axial aberration well.

[0129] from Figure 16 It can be seen that the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within 0~3μm, indicating that the optical lens can correct chromatic aberration well.

[0130] from Figure 17As can be seen, the MTF value of this embodiment is above 0.4 throughout the entire field of view. In the range of 0 to 120 lp / mm, the MTF curve decreases evenly and smoothly from the center to the edge of the field of view, achieving good imaging quality and detail resolution in both low-frequency and high-frequency conditions.

[0131] from Figure 18 As can be seen from the figure, the optical lens of this embodiment has an MTF value of over 0.55 in the entire field of view in the infrared band. In the range of 0 to 120 lp / mm, the MTF curve decreases evenly and smoothly from the center to the edge of the field of view, demonstrating good imaging quality and detail resolution in both low-frequency and high-frequency conditions.

[0132] Please refer to Table 4, which shows the optical characteristics corresponding to the above embodiments, including the effective focal length f, total optical length TTL, aperture value Fno, real image height IH corresponding to the maximum field of view angle, maximum field of view angle FOV, chief ray incidence angle CRA at the maximum image height, and the numerical value corresponding to each conditional expression in each embodiment.

[0133] Table 4

[0134]

[0135] In summary of the above embodiments, the optical lens provided by the present invention uses six lenses with specific optical powers. Through the combination of specific surface shapes and reasonable optical power distribution, it is possible to improve the imaging quality of the optical lens, reduce aberrations, and improve the imaging quality of the optical lens. While achieving a good infrared confocal effect, the lens also has one or more advantages such as a large field of view, a large aperture, and miniaturization.

[0136] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0137] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. An optical lens, comprising six lenses, characterized in that: It sequentially includes from the object side to the imaging surface along the optical axis: 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 angle FOV of the optical lens, and the true image height IH corresponding to the maximum field angle of the optical lens satisfy: 60° < (f × FOV) / IH < 75°; The sagittal height SAG51 of the clear aperture semi-diameter of the object side of the fifth lens and the central thickness CT5 of the fifth lens satisfy: -1.2 < SAG51 / CT5 < -0.

8.

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, wherein: 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, wherein: 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 total optical length TTL of the optical lens and the central thickness CT3 of the third lens satisfy: 6.5 < TTL / CT3 < 8.

5.

6. The optical lens according to claim 1, wherein: 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, wherein: The maximum field 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, wherein: 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, wherein: The Abbe number Vd6 of the sixth lens and the refractive index Nd6 of the sixth lens satisfy: 52 < Vd6 <

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