Optical lens

Abstract

The application provides an optical lens, which has four lenses with optical power, and sequentially comprises, along an optical axis from an object side to an imaging surface, a first lens with negative optical power, an object side surface of which is a convex surface and an image side surface of which is a concave surface; a second lens with positive optical power, an object side surface of which is a convex surface and an image side surface of which is a convex surface; a third lens with positive optical power, an object side surface of which is a convex surface and an image side surface of which is a convex surface; and a fourth lens with positive optical power, an object side surface of which is a concave surface and an image side surface of which is a convex surface; wherein an optical total length TTL of the optical lens and an effective focal length f of the optical lens satisfy 1.7 < TTL / f < 2.2; an object side surface of the first lens has a half aperture diameter d1, a real image height IH corresponding to a maximum field angle of the optical lens and a maximum field angle FOV of the optical lens satisfy 0.75 < d1 / IH / tan(FOV / 2) < 1.4. The optical lens provided by the application has one or more advantages such as a large aperture, a large image surface and small distortion.

Description

Technical Field

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

[0002] Traditional vehicle vision relies on visible light cameras, and its performance drops sharply in low visibility environments such as at night, in haze, and in sandstorms, unable to meet the requirements of driving safety. With the advancement of vehicle intelligence, the demand for all-weather environmental perception in autonomous driving and advanced driver assistance systems has become prominent. Therefore, infrared optical lenses that can still provide a clear view at night or in bad weather are increasingly favored by people. Although there are many types of current vehicle-mounted infrared lenses, most of them have the following problems: a large number of lenses, a small aperture, and a large distortion. 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, the number of lenses with optical power is four, and along the optical axis from the object side to the imaging surface, it successively includes: A first lens with negative optical power, its object side is convex, and its image side is concave; A second lens with positive optical power, its object side is convex, and its image side is convex; A third lens with positive optical power, its object side is convex, and its image side is convex; A fourth lens with positive optical power, its object side is concave, and its 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: 1.7 < TTL / f < 2.2; the clear aperture radius d1 of the object side of the first lens, the true image height IH corresponding to the maximum field angle of the optical lens, and the maximum field angle FOV of the optical lens satisfy: 0.75 < d1 / IH / tan(FOV / 2) < 1.4.

[0005] Further preferably, the total optical length TTL of the optical lens and the true image height IH corresponding to the maximum field angle of the optical lens satisfy: 1.6 < TTL / IH < 2.2.

[0006] Further preferably, the maximum field angle FOV of the optical lens and the aperture value Fno of the optical lens satisfy: 46° < FOV / Fno < 60°.

[0007] Further preferably, 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: 51° < f × FOV / IH < 62°.

[0008] Further preferably, the true image height IH corresponding to the maximum field angle of the optical lens and the aperture value Fno of the optical lens satisfy: 7.5mm < IH / Fno < 9.5mm.

[0009] Further preferably, the focal length f1 of the first lens and the effective focal length f of the optical lens satisfy: -7 < f1 / f < -3.8; the object-side curvature radius R1 of the first lens and the effective focal length f of the optical lens satisfy: 0.8 < R1 / f < 1; the image-side curvature radius R2 of the first lens and the effective focal length f of the optical lens satisfy: 0.53 < R2 / f < 0.65.

[0010] Further preferably, the focal length f2 of the second lens and the effective focal length f of the optical lens satisfy: 0.9 < f2 / f < 1.1; the object-side curvature radius R3 of the second lens and the effective focal length f of the optical lens satisfy: 1.8 < R3 / f < 2.3; the image-side curvature radius R4 of the second lens and the effective focal length f of the optical lens satisfy: -44 < R4 / f < -15.

[0011] Further preferably, the focal length f3 of the third lens and the effective focal length f of the optical lens satisfy: 1.1 < f3 / f < 1.4; the object-side curvature radius R5 of the third lens and the effective focal length f of the optical lens satisfy: 2.7 < R5 / f < 3.4; the image-side curvature radius R6 of the third lens and the effective focal length f of the optical lens satisfy: -25 < R6 / f < -17.

[0012] Further preferably, the clear aperture semi-diameter d1 of the object side of the first lens and the clear aperture semi-diameter d8 of the image side of the fourth lens satisfy: 1.2 < d1 / d8 < 1.5.

[0013] Further preferably, the sagittal height SAG8 of the clear aperture semi-diameter of the image side of the fourth lens, the sagittal height SAG7 of the clear aperture semi-diameter of the object side of the fourth lens, and the central thickness CT4 of the fourth lens satisfy: 0.01 < (SAG8 - SAG7) / CT4 < 0.05.

[0014] The optical lens provided by the present invention adopts four lenses with optical power. Through specific surface shape matching and reasonable optical power distribution, it can improve the imaging quality of the optical lens, reduce aberration, improve the imaging quality of the optical lens, and enable the lens to have one or more advantages such as a large aperture, a large image plane, and small distortion. Attached Figure Description

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

[0016] Figure 2 This is a field curvature curve diagram of the optical lens in Embodiment 1 of the present invention.

[0017] Figure 3 This is an F-Tan (Theta) distortion curve of the optical lens in Embodiment 1 of the present invention.

[0018] Figure 4 This is an axial aberration curve of the optical lens in Embodiment 1 of the present invention.

[0019] Figure 5 This is a chromatic aberration curve of the optical lens in Embodiment 1 of the present invention.

[0020] Figure 6 This is a relative illumination curve of the optical lens in Embodiment 1 of the present invention.

[0021] Figure 7 This is a defocus MTF curve of the optical lens in Embodiment 1 of the present invention.

[0022] Figure 8 This is a schematic diagram of the optical lens structure in Embodiment 2 of the present invention.

[0023] Figure 9 This is a field curvature curve diagram of the optical lens in Embodiment 2 of the present invention.

[0024] Figure 10 This is an F-Tan (Theta) distortion curve of the optical lens in Embodiment 2 of the present invention.

[0025] Figure 11 This is an axial aberration curve of the optical lens in Embodiment 2 of the present invention.

[0026] Figure 12 This is a chromatic aberration curve of the optical lens in Embodiment 2 of the present invention.

[0027] Figure 13 This is a relative illumination curve of the optical lens in Embodiment 2 of the present invention.

[0028] Figure 14 This is a defocus MTF curve of the optical lens in Embodiment 2 of the present invention.

[0029] Figure 15 This is a schematic diagram of the optical lens in Embodiment 3 of the present invention.

[0030] Figure 16 This is a field curvature curve diagram of the optical lens in Embodiment 3 of the present invention.

[0031] Figure 17 This is an F-Tan (Theta) distortion curve of the optical lens in Embodiment 3 of the present invention.

[0032] Figure 18 This is an axial aberration curve of the optical lens in Embodiment 3 of the present invention.

[0033] Figure 19 This is a chromatic aberration curve of the optical lens in Embodiment 3 of the present invention.

[0034] Figure 20 This is a relative illumination curve of the optical lens in Embodiment 3 of the present invention.

[0035] Figure 21 This is a defocus MTF curve of the optical lens in Embodiment 3 of the present invention.

[0036] Figure 22 This is a schematic diagram of the optical lens structure in Embodiment 4 of the present invention.

[0037] Figure 23 This is a field curvature curve diagram of the optical lens in Embodiment 4 of the present invention.

[0038] Figure 24 This is the F-Tan (Theta) distortion curve of the optical lens in Embodiment 4 of the present invention.

[0039] Figure 25 This is an axial aberration curve of the optical lens in Embodiment 4 of the present invention.

[0040] Figure 26 This is a chromatic aberration curve of the optical lens in Embodiment 4 of the present invention.

[0041] Figure 27 This is a relative illumination curve of the optical lens in Embodiment 4 of the present invention.

[0042] Figure 28 This is a defocus MTF curve of the optical lens in Embodiment 4 of the present invention.

[0043] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0044] To better understand this application, various aspects of this application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of embodiments of this application and are not intended to limit the scope of this 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.

[0045] It should be noted that in this specification, the terms "first," "second," "third," etc., are used only to distinguish one feature from another and do not imply any limitation on the features. Therefore, without departing from the teachings of the invention, the first lens discussed below may also be referred to as the second lens or the third lens.

[0046] In the accompanying drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are illustrated by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustrative purposes only and are not strictly to scale.

[0047] In this article, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the location of the convexity 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 location of the concaveness 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 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.

[0048] It should also be understood that the terms "comprising," "including," "having," "containing," 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. Furthermore, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features, not individual elements in the list. Additionally, when describing embodiments of this application, the word "may" is used to mean "one or more embodiments of this application." And the term "exemplary" is intended to refer to an example or illustration.

[0049] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms (e.g., those defined in common dictionaries) shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formal sense unless expressly so specified herein.

[0050] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The following will describe this application in detail with reference to the drawings and in combination with the embodiments.

[0051] An embodiment of the present invention provides an optical lens. The number of lenses with optical power is four. Along the optical axis, from the object side to the imaging surface, they are the first lens, the second lens, the third lens, and the fourth lens in sequence.

[0052] In some embodiments, the first lens may have a negative optical power. Its object side surface may be convex, and its image side surface may be concave. The second lens may have a positive optical power. Its object side surface may be convex, and its image side surface may be convex. The third lens may have a positive optical power. Its object side surface may be convex, and its image side surface may be convex. The fourth lens may have a positive optical power. Its object side surface may be concave, and its image side surface may be convex.

[0053] In some embodiments, the optical lens may further include an aperture. The aperture may be located between the second lens and the third lens. It can be understood that the aperture is used to limit the amount of incident light to change the brightness of the image.

[0054] In some embodiments, the total optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 1.7 < TTL / f < 2.2; the clear aperture radius d1 of the object side surface of the first lens, the true image height IH corresponding to the maximum field angle of view of the optical lens, and the maximum field angle of view FOV of the optical lens satisfy: 0.75 < d1 / IH / tan(FOV / 2) < 1.4. Satisfying the above range can effectively limit the length of the lens, which is beneficial to the miniaturization of the optical lens. At the same time, it can ensure the balance between the size of the optical lens, the field angle of view, and the image plane.

[0055] In some embodiments, the total optical length TTL of the optical lens and the true image height IH corresponding to the maximum field angle of view of the optical lens satisfy: 1.6 < TTL / IH < 2.2. Satisfying the above range can better achieve the miniaturization of the lens, and ensure that, with the same total length of the lens, it has a larger image plane and can match a larger-sized imaging chip to achieve high-definition imaging.

[0056] In some embodiments, the maximum field angle of view FOV of the optical lens and the aperture value Fno of the optical lens satisfy: 46° < FOV / Fno < 60°. Satisfying the above range can achieve a large aperture, which is beneficial to increasing the amount of light entering the lens and enabling the lens to achieve high-definition imaging in a dim environment.

[0057] 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: 51° < f × FOV / IH < 62°. Meeting the above range and reasonably restricting the relationship among the focal length, field angle, and image height of the optical lens is beneficial to achieving the balance between the field angle of the optical lens and large-target-plane imaging, and better meeting the usage requirements of high-image-quality shooting of the optical lens.

[0058] In some embodiments, the true image height IH corresponding to the maximum field angle of the optical lens and the aperture value Fno of the optical lens satisfy: 7.5 mm < IH / Fno < 9.5 mm. Meeting the above range, while maintaining a large image plane for the optical lens, ensures that the optical lens has a large aperture, achieving the balance between a large image plane and a large aperture.

[0059] In some embodiments, the focal length f1 of the first lens and the effective focal length f of the optical lens satisfy: -7 < f1 / f < -3.8; the curvature radius R1 of the object side surface of the first lens and the effective focal length f of the optical lens satisfy: 0.8 < R1 / f < 1; the curvature radius R2 of the image side surface of the first lens and the effective focal length f of the optical lens satisfy: 0.53 < R2 / f < 0.65. 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. At the same time, reasonably defining the shape of the first lens can correct coma, spherical aberration, and astigmatism, improve the flatness of imaging, and enhance the imaging quality of the optical lens.

[0060] In some embodiments, the focal length f2 of the second lens and the effective focal length f of the optical lens satisfy: 0.9 < f2 / f < 1.1; the curvature radius R3 of the object side surface of the second lens and the effective focal length f of the optical lens satisfy: 1.8 < R3 / f < 2.3; the curvature radius R4 of the image side surface of the second lens and the effective focal length f of the optical lens satisfy: -44 < R4 / f < -15. Meeting the above range, the second lens converges the incident light at the front end, which is beneficial to correcting the aberration and distortion of the edge field brought by the front-end lens, making the lens have less distortion and capable of providing a high-definition imaging effect. At the same time, it is beneficial to reducing the difficulty of lens forming and processing.

[0061] In some embodiments, the focal length f3 of the third lens and the effective focal length f of the optical lens satisfy:1.1 < f3 / f < 1.4; the radius of curvature R5 of the object side surface of the third lens and the effective focal length f of the optical lens satisfy: 2.7 < R5 / f < 3.4; the radius of curvature R6 of the image side surface of the third lens and the effective focal length f of the optical lens satisfy: -25 < R6 / f < -17. Satisfying the above ranges, the third lens is a positive lens, which transmits the light beam to the final imaging lens group, compensates for aberrations with the front and rear optical systems, thereby achieving high imaging quality of the optical lens. At the same time, reasonably limiting the proportion of the optical power of the third lens and its surface shape can effectively correct the aberrations of the optical lens and improve the imaging quality.

[0062] In some embodiments, the clear aperture semi-diameter d1 of the object side surface of the first lens and the clear aperture semi-diameter d8 of the image side surface of the fourth lens satisfy: 1.2 < d1 / d8 < 1.5. Satisfying the above ranges, 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, and can better meet the balance of miniaturization and high pixels.

[0063] In some embodiments, the sagittal height SAG8 of the clear aperture semi-diameter of the image side surface of the fourth lens, the sagittal height SAG7 of the clear aperture semi-diameter of the object side surface of the fourth lens, and the central thickness CT4 of the fourth lens satisfy: 0.01 < (SAG8 - SAG7) / CT4 < 0.05. Satisfying the above ranges, by controlling the relationship between the difference in the sagittal heights of the image side and object side surfaces of the fourth lens and the central thickness of the fourth lens, it is beneficial to correct the coma of the off-axis field and improve the imaging quality of the off-axis field of the optical lens.

[0064] In some embodiments, the combined focal length f12 of the first lens and the second lens and the combined focal length f34 of the third lens and the fourth lens satisfy: 1.2 < f12 / f34 < 1.8. Satisfying the above ranges, it is possible to reasonably distribute the proportion of the optical power of the lens groups before and after the aperture stop, which is beneficial to increasing the relative illumination of the lens and improving the imaging quality of the lens.

[0065] In some embodiments, the combined focal length f12 of the first lens and the second lens and the effective focal length f of the optical lens satisfy: 1.7 < f12 / f < 2.2. Satisfying the above ranges, by reasonably distributing the proportion of the optical power from the first lens to the second lens, it is beneficial to reduce the light deflection angle at the front end of the lens and reduce the generation of various off-axis aberrations.

[0066] In some embodiments, the combined focal length f34 of the third lens and the fourth lens and the effective focal length f of the optical lens satisfy: 1.1 < f34 / f < 1.4. Satisfying the above ranges, by reasonably distributing the proportion of the optical power from the third lens to the fourth lens, it is possible to balance the focal length of the optical lens, improve the correction ability of various aberrations at the rear end of the lens, and enhance the imaging quality of the optical lens.

[0067] In some embodiments, the clear aperture semi-diameter d1 of the object side surface of the first lens and the true image height IH corresponding to the maximum field angle of the optical lens satisfy: 0.47 < d1 / IH < 0.7. Meeting the above range can ensure that the lens has a large field angle and the overall size of the lens is appropriate.

[0068] In some embodiments, the distance CT23 between the second lens and the third lens on the optical axis and the total optical length TTL of the optical lens satisfy: 0.04 < CT23 / TTL < 0.07. Meeting the above range helps to improve the structural compactness of the optical lens by controlling the distance between the front and rear lenses of the aperture stop on the optical axis.

[0069] In some embodiments, the sagittal height SAG2 of the clear aperture of the image side surface of the first lens, the sagittal height SAG1 of the clear aperture of the object side surface of the first lens, and the central thickness CT1 of the first lens satisfy: 0.04 < (SAG2 - SAG1) / CT1 < 0.06. Meeting the above range can limit the central depression degree of the first lens and reduce the difficulty of aberration correction in the marginal field by controlling the relationship between the sagittal height difference between the image side and the object side of the first lens and the central thickness of the first lens.

[0070] In some embodiments, the true image height IH corresponding to the maximum field angle of the optical lens, the effective focal length f of the optical lens, and the maximum field angle FOV of the optical lens satisfy: 0.8 < (IH / 2) / (f × tan(FOV / 2)) < 1. Meeting the above range indicates that the optical distortion of the optical lens is well controlled, the resolution of the optical lens is improved, and at the same time, the special distortion specification is achieved, ensuring that the marginal field occupies a larger proportion in the entire imaging picture and making the imaging of the marginal field clearer.

[0071] In some embodiments, the true image height IH corresponding to the maximum field angle of the optical lens and the entrance pupil diameter EPD of the optical lens satisfy: 0.85 < IH / EPD < 1.4. Meeting the above range, while the optical lens meets the large image plane, it can also ensure sufficient image plane brightness in the marginal field, prevent the occurrence of vignetting, and thus improve the imaging quality.

[0072] In some embodiments, the true image height IH corresponding to the maximum field angle of the optical lens and the effective focal length f of the optical lens satisfy: 0.85 < IH / f < 1.2. Meeting the above range can achieve a larger field angle and imaging range, and can achieve the characteristics of a large image plane while ensuring the depth of field of the optical lens, thereby improving the imaging quality of the optical system.

[0073] In some embodiments, the distance BL from the image side of the fourth lens of the optical lens to the imaging surface on the optical axis and the effective focal length f of the optical lens satisfy: 0.28 < BL / f < 0.34. Meeting the above range is conducive to achieving a balance between good imaging quality and easy assembly, ensuring the imaging quality of the optical lens while avoiding interference between the lens and other components and reducing the assembly process difficulty of the camera module.

[0074] In some embodiments, the total optical length TTL of the optical lens, the true image height IH corresponding to the maximum field angle of the optical lens, and the maximum field angle FOV of the optical lens satisfy: 0.02 / ° < TTL / IH / FOV < 0.05 / °. Meeting the above range can achieve a balance among large image height, large field angle, and miniaturization, and improve the imaging quality of the optical lens.

[0075] In some embodiments, the sum ΣCT of the central thicknesses of the four lenses and the total optical length TTL of the optical lens satisfy: 0.55 < ΣCT / TTL < 0.7. Meeting the above range can effectively compress the total length of the optical lens and is conducive to the structural design and production process of the optical lens.

[0076] In some embodiments, the distance BL from the image side of the fourth lens of the optical lens to the imaging surface on the optical axis and the total optical length TTL of the optical lens satisfy: 0.15 < BL / TTL < 0.19. Meeting the above range is conducive to achieving a short back focus of the optical lens, and is conducive to the miniaturization of the optical lens while ensuring sufficient space for the installation and focusing of optical components.

[0077] In some embodiments, the focal length f2 of the second lens and the focal length f3 of the third lens satisfy: 0.75 < f2 / f3 < 0.95. Meeting the above range and reasonably setting the focal length ratio of the second lens and the third lens can shorten the system length, reduce aberration and distortion of the marginal field of view, make the lens have less distortion, and be able to provide a high-definition imaging effect.

[0078] In some embodiments, the central thickness CT1 of the first lens and the central thickness CT2 of the second lens satisfy: 1 < CT1 / CT2 < 1.9. Meeting the above range and their mutual matching help to eliminate axial chromatic aberration.

[0079] In some embodiments, the curvature radius R7 of the object side of the fourth lens and the effective focal length f of the optical lens satisfy: -8.2 < R7 / f < -6.2; the curvature radius R8 of the image side of the fourth lens and the effective focal length f of the optical lens satisfy: -8.3 < R8 / f < -6.4. Meeting the above range and reasonably defining the surface type of the fourth lens can smoothly transition light, reduce aberration, and is conducive to improving the relative illumination of the optical lens.

[0080] In some embodiments, the radius of curvature R1 of the object side surface of the first lens and the radius of curvature R2 of the image side surface of the first lens satisfy: 0.2 < (R1 - R2) / (R1 + R2) < 0.24. Meeting the above range and reasonably defining the surface shape of the first lens is beneficial for light divergence, obtaining a larger picture, can effectively eliminate aberration, and improve the resolution ability of the optical lens.

[0081] 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: -1.4 < (R3 - R4) / (R3 + R4) < -1. Meeting the above range and reasonably defining the shape of the second lens can optimize the aberration balance of the lens group and improve the imaging quality.

[0082] In some embodiments, the radius of curvature R5 of the object side surface of the third lens and the radius of curvature R6 of the image side surface of the third lens satisfy: -1.55 < (R5 - R6) / (R5 + R6) < -1.2. Meeting the above range and reasonably defining the shape of the third lens can comprehensively balance the spherical aberration, chromatic aberration and field curvature of the optical system, reduce the risk of ghosting, improve the resolution ability of the optical system. At the same time, it is also beneficial to reduce the processing difficulty of the second lens.

[0083] In some embodiments, the radius of curvature R7 of the object side surface of the fourth lens and the radius of curvature R8 of the image side surface of the fourth lens satisfy: -0.02 < (R7 - R8) / (R7 + R8) < 0. Meeting the above range and reasonably defining the surface shape of the fourth lens helps to control the light trend of the edge field of view and improve the imaging quality of the edge field of view.

[0084] In some embodiments, the optical lens satisfies the following conditional expressions: 9mm < f < 9.2mm; 51.9° < FOV < 65.1°; 7.8mm < EPD < 9.1mm; 16.2mm < TTL < 18.2mm; 1 < Fno < 1.2; 8.2mm < IH < 10.4mm; 35.2° < CRA < 39.2°; 2.7mm < BL < 2.9mm. In the above conditional expressions, f represents the effective focal length of the optical lens, FOV represents the maximum field of view angle of the optical lens, EPD represents the entrance pupil diameter of the optical lens, TTL represents the total optical length of the optical lens, Fno represents the 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 BL represents the distance from the image side surface of the fourth lens of the optical lens to the imaging surface on the optical axis. Meeting the above range, the optical lens has at least one or more advantages such as a large aperture, a large image plane, and small distortion.

[0085] 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, production costs can be effectively reduced. Alternatively, when the lens material is glass, the low dispersion characteristic of glass itself can effectively correct the geometric chromatic aberration of the optical system. More specifically, the optical lens provided by the present invention can adopt an all-glass lens structure, which can reduce dispersion, effectively correct chromatic aberration of the optical lens, and improve image quality.

[0086] In some embodiments, the first lens, second lens, third lens, and fourth lens can be spherical lenses or aspherical lenses. Compared to spherical structures, aspherical structures can effectively reduce the aberrations of the optical system, thereby reducing the number of lenses and the size of the lenses, and better achieving lens miniaturization. More specifically, the first lens, second lens, third lens, and fourth lens of the present invention can all be aspherical lenses.

[0087] In various embodiments of the present invention, when an aspherical lens is used, the shapes of each aspherical surface of the optical lens satisfy the following equations: ; Where 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 vertex of the surface, K is the quadratic surface coefficient, and B, C, D, E, and F are the fourth, sixth, eighth, tenth, and twelfth order surface coefficients, respectively.

[0088] The present invention will be further described below with reference to several 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 tables of each embodiment. The following embodiments are merely preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the following embodiments. Any changes, substitutions, combinations, or simplifications made without departing from the innovative points of the present invention should be considered equivalent substitutions and are included within the protection scope of the present invention. Example 1

[0089] Please see Figure 1 The diagram shows a schematic of the structure of the optical lens 100 provided in Embodiment 1 of the present invention. The optical lens 100 includes, along the optical axis from the object side to the imaging plane, the following components in sequence: a first lens L1, a second lens L2, an aperture ST, a third lens L3, and a fourth lens L4.

[0090] Among them, the first lens L1 has negative optical power, its object side S1 is convex, and its image side S2 is concave. The second lens L2 has positive optical power, its object side S3 is convex, and its image side S4 is convex. The third lens L3 has positive optical power, its object side S5 is convex, and its image side S6 is convex. The fourth lens L4 has positive optical power, its object side S7 is concave, and its image side S8 is convex. The imaging plane S9 is a plane.

[0091] The first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 are all glass aspherical lenses.

[0092] The relevant parameters of each lens in the optical lens 100 in Example 1 are shown in Table 1-1.

[0093] Table 1-1 The surface profile parameters of the aspherical lens of the optical lens 100 in Example 1 are shown in Table 1-2.

[0094] Table 1-2 In this embodiment, the field curvature curve, F-Tan (Theta) distortion curve, axial aberration curve, transverse chromatic aberration curve, relative illumination curve, and defocus MTF curve of the optical lens 100 are respectively as follows: Figures 2 to 7 As shown.

[0095] Figure 2 The field curvature curve of Embodiment 1 is shown, which represents the degree of curvature of light of different wavelengths in the meridional and sagittal image planes. The horizontal axis represents the offset (unit: mm), and the vertical axis represents the half field of view (unit: °). As can be seen from the figure, the field curvature of the meridional and sagittal image planes is controlled within -0.1 mm to 0.05 mm, indicating that the optical lens 100 can effectively correct the field curvature.

[0096] Figure 3 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 distortion value (unit: %), and the vertical axis represents the half field of view (unit: °). As can be seen from the figure, the distortion of the optical lens is controlled within -10% to 0%, indicating that the optical lens 100 can effectively correct distortion in the infrared band.

[0097] Figure 4 The axial aberration curve of Embodiment 1 is shown, which represents the aberration of each wavelength on the optical axis at the imaging plane. The horizontal axis represents the axial aberration value (unit: mm), and the vertical axis represents the normalized pupil radius. As can be seen from the figure, the axial aberration offset is controlled within ±0.05 mm, indicating that the optical lens 100 can effectively correct axial aberration.

[0098] Figure 5 The diagram shows the transverse chromatic aberration curves for Example 1, representing the chromatic aberration of each wavelength relative to the center wavelength (10.6 μm) at different image heights on the imaging plane. The horizontal axis represents the transverse chromatic aberration value of each wavelength relative to the center wavelength (unit: μm), and the vertical axis represents the normalized field of view. As can be seen from the diagram, the transverse chromatic aberration of the longest and shortest wavelengths is controlled within ±1 μm, indicating that the optical lens 100 can effectively correct transverse chromatic aberration.

[0099] Figure 6 The relative illumination curve of Example 1 is shown, which represents the relative illumination value at different field-of-view angles on the imaging plane. The horizontal axis represents the half-field-of-view angle (unit: °), and the vertical axis represents the relative illumination (unit: %). As can be seen from the figure, the relative illumination value of the optical lens is still greater than 50% at the maximum half-field-of-view angle, indicating that the optical lens 100 has good relative illumination in the infrared band.

[0100] Figure 7 The defocus MTF (modulation transfer function) curve of Example 1 is shown, which represents the lens imaging modulation at different focal shifts in various fields of view. The horizontal axis represents the focal shift (unit: mm), and the vertical axis represents the MTF value. It can be seen from the figure that, with the same focal shift, the MTF values ​​differ little across fields of view. Furthermore, for the same focal shift, the meridional and sagittal curves for the same field of view are close, indicating that the optical lens 100 has low astigmatism. Example 2

[0101] Please see Figure 8 The figure shown is a schematic diagram of the structure of the optical lens 200 provided in Embodiment 2 of the present invention. The main difference between this embodiment and Embodiment 1 is that the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0102] The relevant parameters of each lens in the optical lens 200 in Example 2 are shown in Table 2-1.

[0103] Table 2-1 The surface profile parameters of the aspherical lens of the optical lens 200 in Example 2 are shown in Table 2-2.

[0104] Table 2-2 In this embodiment, the field curvature curve, F-Tan (Theta) distortion curve, axial aberration curve, transverse chromatic aberration curve, relative illumination curve, and defocus MTF curve of the optical lens 200 are respectively as follows: Figures 9 to 14 As shown.

[0105] from Figure 9As can be seen, the field curvature of the meridional and sagittal image planes is controlled within -0.1mm to 0.05mm, indicating that the optical lens 200 can effectively correct the field curvature.

[0106] from Figure 10 As can be seen, the distortion of the optical lens is controlled within -10% to 0%, indicating that the optical lens 200 can effectively correct distortion in the infrared band.

[0107] from Figure 11 As can be seen, the axial aberration offset is controlled within -0.05mm to 0.1mm, indicating that the optical lens 200 can correct axial aberration well.

[0108] from Figure 12 As can be seen, the transverse chromatic aberration of the longest and shortest wavelengths is controlled within ±1μm, indicating that the optical lens 200 can effectively correct transverse chromatic aberration.

[0109] from Figure 13 As can be seen, the relative illumination value of the optical lens is still greater than 50% at the maximum half field of view, indicating that the optical lens 200 has good relative illumination in the infrared band.

[0110] from Figure 14 As can be seen, under the same focal shift, the MTF values ​​of each field of view are relatively similar. Furthermore, for the same focal shift, the meridional and sagittal curves of the same field of view are close, indicating that the optical lens 200 has low astigmatism. Example 3

[0111] Please see Figure 15 The figure shown is a schematic diagram of the structure of the optical lens 300 provided in Embodiment 3 of the present invention. The main difference between this embodiment and Embodiment 1 is that the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0112] The relevant parameters of each lens in the optical lens 300 in Example 3 are shown in Table 3-1.

[0113] Table 3-1 The surface profile parameters of the aspherical lens of the optical lens 300 in Example 3 are shown in Table 3-2.

[0114] Table 3-2 In this embodiment, the field curvature curve, F-Tan (Theta) distortion curve, axial aberration curve, transverse chromatic aberration curve, relative illumination curve, and defocus MTF curve of the optical lens 300 are respectively as follows: Figures 16 to 21 As shown.

[0115] from Figure 16 As can be seen, the field curvature of the meridional and sagittal image planes is controlled within -0.1mm to 0.05mm, indicating that the optical lens 300 can effectively correct field curvature.

[0116] from Figure 17 As can be seen, the distortion of the optical lens is controlled within -10% to 0%, indicating that the optical lens 300 can effectively correct distortion in the infrared band.

[0117] from Figure 18 As can be seen, the axial aberration offset is controlled within ±0.05mm, indicating that the optical lens 300 can correct axial aberration well.

[0118] from Figure 19 As can be seen, the transverse chromatic aberration of the longest and shortest wavelengths is controlled within ±1μm, indicating that the optical lens 300 can effectively correct transverse chromatic aberration.

[0119] from Figure 20 As can be seen, the relative illumination value of the optical lens is still greater than 50% at the maximum half field of view, indicating that the optical lens 300 has good relative illumination in the infrared band.

[0120] from Figure 21 As can be seen, under the same focal shift, the MTF values ​​of each field of view are relatively similar. Furthermore, for the same focal shift, the meridional and sagittal curves of the same field of view are close, indicating that the optical lens 300 has low astigmatism. Example 4

[0121] Please see Figure 22 The figure shown is a schematic diagram of the structure of the optical lens 400 provided in Embodiment 4 of the present invention. The main difference between this embodiment and Embodiment 1 is that the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0122] The relevant parameters of each lens in the optical lens 400 in Example 4 are shown in Table 4-1.

[0123] Table 4-1 The surface profile parameters of the aspherical lens of the optical lens 400 in Example 4 are shown in Table 4-2.

[0124] Table 4-2 In this embodiment, the field curvature curve, F-Tan (Theta) distortion curve, axial aberration curve, transverse chromatic aberration curve, relative illumination curve, and defocus MTF curve of the optical lens 400 are respectively as follows: Figures 23 to 28 As shown.

[0125] from Figure 23 As can be seen, the field curvature of the meridional and sagittal image planes is controlled within -0.1mm to 0.05mm, indicating that the optical lens 400 can effectively correct field curvature.

[0126] from Figure 24 As can be seen, the distortion of the optical lens is controlled within -15% to 0%, indicating that the optical lens 400 can effectively correct distortion in the infrared band.

[0127] from Figure 25 As can be seen, the axial aberration offset is controlled within ±0.05mm, indicating that the optical lens 400 can effectively correct axial aberration.

[0128] from Figure 26 As can be seen, the transverse chromatic aberration of the longest and shortest wavelengths is controlled within ±1μm, indicating that the optical lens 400 can effectively correct transverse chromatic aberration.

[0129] from Figure 27 As can be seen, the relative illumination value of the optical lens is still greater than 40% at the maximum half field of view, indicating that the optical lens 400 has good relative illumination in the infrared band.

[0130] from Figure 28 As can be seen, under the same focal shift, the MTF values ​​of each field of view are relatively similar. Furthermore, for the same focal shift, the meridional and sagittal curves of the same field of view are close, indicating that the optical lens 400 has low astigmatism.

[0131] Please refer to Table 5 for the optical characteristics corresponding to each of the above embodiments, including the effective focal length f, total optical length TTL, aperture value Fno, principal ray incident angle CRA at the maximum image height, true image height IH corresponding to the maximum field of view, maximum field of view FOV, entrance pupil diameter EPD, distance BL from the image side of the fourth lens to the imaging plane on the optical axis, and the numerical values ​​corresponding to each conditional expression in each embodiment.

[0132] Table 5 In summary, the optical lens provided by the present invention employs four lenses with optical power. Through specific surface shape matching and reasonable optical power distribution, it can improve the imaging quality of the optical lens, reduce aberrations, and enhance the imaging quality of the optical lens, giving the lens one or more advantages such as large aperture, large image plane, and small distortion.

[0133] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions 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 one or more embodiments or examples.

[0134] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. An optical lens having four lenses with optical power, characterized in that, It successively 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 object side is convex and whose image side is convex; A third lens with a positive optical power, whose object side is convex and whose image side is convex; A fourth lens with a positive optical power, whose object side is concave 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: 1.7 < TTL / f < 2.2; the clear aperture semi-diameter d1 of the object side of the first lens, the true image height IH corresponding to the maximum field angle of the optical lens and the maximum field angle FOV of the optical lens satisfy: 0.75 < d1 / IH / tan(FOV / 2) < 1.

4.

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 angle of the optical lens satisfy: 1.6 < TTL / IH < 2.

2.

3. The optical lens according to claim 1, characterized in that, The maximum field angle FOV of the optical lens and the f-number Fno of the optical lens satisfy: 46° < FOV / Fno < 60°.

4. The optical lens according to claim 1, characterized in that, 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: 51° < f×FOV / IH < 62°.

5. The optical lens according to claim 1, characterized in that, The true image height IH corresponding to the maximum field angle of the optical lens and the f-number Fno of the optical lens satisfy: 7.5mm < IH / Fno < 9.5mm.

6. 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: -7 < f1 / f < -3.8; the curvature radius R1 of the object side of the first lens and the effective focal length f of the optical lens satisfy: 0.8 < R1 / f < 1; the curvature radius R2 of the image side of the first lens and the effective focal length f of the optical lens satisfy: 0.53 < R2 / f < 0.

65.

7. The optical lens according to claim 1, characterized in that, The focal length f2 of the second lens and the effective focal length f of the optical lens satisfy: 0.9 < f2 / f < 1.1; the curvature radius R3 of the object side of the second lens and the effective focal length f of the optical lens satisfy: 1.8 < R3 / f < 2.3; the curvature radius R4 of the image side of the second lens and the effective focal length f of the optical lens satisfy: -44 < R4 / f < -15.

8. The optical lens according to claim 1, characterized in that, The focal length f3 of the third lens and the effective focal length f of the optical lens satisfy: 1.1 < f3 / f < 1.4; the curvature radius R5 of the object side of the third lens and the effective focal length f of the optical lens satisfy: 2.7 < R5 / f < 3.4; the curvature radius R6 of the image side of the third lens and the effective focal length f of the optical lens satisfy: -25 < R6 / f < -17.

9. The optical lens according to claim 1, characterized in that, The clear aperture semi-diameter d1 of the object side of the first lens and the clear aperture semi-diameter d8 of the image side of the fourth lens satisfy: 1.2 < d1 / d8 < 1.

5.

10. The optical lens according to claim 1, characterized in that, The image-side half-aperture height SAG8 of the fourth lens, the object-side half-aperture height SAG7 of the fourth lens, and the center thickness CT4 of the fourth lens satisfy the following condition: 0.01 < (SAG8 - SAG7) / CT4 < 0.05.

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