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 positive optical power, whose object side surface is a concave surface and whose image side surface is a convex surface; a second lens with positive optical power, whose object side surface is a convex surface at a near optical axis and whose image side surface is a convex surface; a third lens with positive optical power, whose object side surface is a concave surface at a near optical axis and whose image side surface is a convex surface at a near optical axis; and a fourth lens with negative optical power, whose object side surface is a concave surface at a near optical axis and whose image side surface is a convex surface at a near optical axis; wherein a real image height IH corresponding to a maximum field angle of the optical lens and an effective focal length f of the optical lens satisfy 1.3<IH / f<1.6; and a curvature radius R7 of the object side surface of the fourth lens and a curvature radius R8 of the image side surface of the fourth lens satisfy -0.45<(R7-R8) / (R7+R8)<-0.2. The optical lens provided by the application can reasonably correct the overall aberration of the optical lens and improve the imaging quality of the optical lens.

Description

Technical Field

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

[0002] With the popularization and wide application of automotive assisted driving technology, the demand for driving safety continues to rise. Driver state recognition has become the core requirement, and its core goal is to predict driving risks and timely remind of standard operations, etc. The in-vehicle DMS lens needs to be particularly adapted to the complex light environment inside the vehicle, and has the characteristics of high relative illumination and low distortion, so as to avoid vignetting or deformation of the image affecting the capture of facial features. At the same time, it needs to meet the strict requirements of the in-vehicle scenario for small size, earthquake resistance, and high temperature resistance. However, the lenses currently available on the market generally have problems such as insufficient edge sharpness and poor light adaptability, making it difficult to support high-precision state recognition. Therefore, developing an optical lens with excellent imaging effects and strong adaptability has become an urgent need for the current industry development. Summary of the Invention

[0003] In view of the above problems, the purpose of the present invention is to provide an optical lens, which has the advantage of excellent imaging quality.

[0004] The technical solution adopted by the present invention is as follows:

[0005] 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:

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

[0007] A second lens with positive optical power, its object side is convex near the optical axis, and its image side is convex;

[0008] A third lens with positive optical power, its object side is concave near the optical axis, and its image side is convex near the optical axis;

[0009] A fourth lens with negative optical power, its object side is concave near the optical axis, and its image side is convex near the optical axis;

[0010] Wherein, 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: 1.3 < IH / f < 1.6; the curvature radius R7 of the object side of the fourth lens and the curvature radius R8 of the image side of the fourth lens satisfy: -0.45 < (R7 - R8) / (R7 + R8) < -0.2.

[0011] Further preferably, the total optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 2.2 < TTL / f < 2.6; 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 < 1.8.

[0012] Further preferably, the maximum field angle FOV of the optical lens and the aperture value Fno of the optical lens satisfy: 30° < FOV / Fno < 43°; 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: 2.7 < IH / EPD < 3.1; 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 radian value θ of the maximum half field angle of the optical lens satisfy: 1 < (IH / 2) / (f×θ) < 1.1; 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: 0.88 < (IH / 2) / (f×Tan(FOV / 2)) < 1.

[0013] Further preferably, 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: 14 < 180°×TTL / (IH / 2) / (FOV / 2) < 19; 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: 50° < f×FOV / IH < 55°.

[0014] Further preferably, the semi-aperture 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: 1 < d1 / (IH / 2) / Tan(FOV / 2) < 1.15; the semi-aperture d1 of the object side of the first lens and the semi-aperture d8 of the image side of the fourth lens satisfy: 0.4 < d1 / d8 < 0.44.

[0015] Further preferably, the focal length f1 of the first lens and the effective focal length f of the optical lens satisfy: 2 < f1 / f < 6; the curvature radius R1 of the object side of the first lens and the effective focal length f of the optical lens satisfy: -0.7 < R1 / f < -0.5; the curvature radius R2 of the image side of the first lens and the effective focal length f of the optical lens satisfy: -0.85 < R2 / f < -0.45.

[0016] More preferably, the focal length f2 of the second lens and the effective focal length f of the optical lens satisfy: 0.8 < f2 / f < 1.2; the object-side curvature radius R3 of the second lens and the effective focal length f of the optical lens satisfy: 0.9 < R3 / f < 1.5; the image-side curvature radius R4 of the second lens and the effective focal length f of the optical lens satisfy: -1.5 < R4 / f < -0.5.

[0017] More preferably, the focal length f3 of the third lens and the effective focal length f of the optical lens satisfy: 0.9 < f3 / f < 2.1; the object-side curvature radius R5 of the third lens and the effective focal length f of the optical lens satisfy: -0.75 < R5 / f < -0.2; the image-side curvature radius R6 of the third lens and the effective focal length f of the optical lens satisfy: -0.6 < R6 / f < -0.2; the object-side curvature radius R5 of the third lens and the image-side curvature radius R6 of the third lens satisfy: 0 < (R5 - R6) / (R5 + R6) < 0.2.

[0018] More preferably, the focal length f4 of the fourth lens and the effective focal length f of the optical lens satisfy: -2.5 < f4 / f < -0.8; the object-side curvature radius R7 of the fourth lens and the effective focal length f of the optical lens satisfy: -0.4 < R7 / f < -0.2; the image-side curvature radius R8 of the fourth lens and the effective focal length f of the optical lens satisfy: -0.7 < R8 / f < -0.4; the object-side clear aperture semi-diameter d7 of the fourth lens and the object-side clear aperture sagittal height Sag7 of the fourth lens satisfy: -9 < d7 / Sag7 < -3; the image-side clear aperture semi-diameter d8 of the fourth lens and the image-side clear aperture sagittal height Sag8 of the fourth lens satisfy: -12300 < d8 / Sag8 < -9; the object-side curvature radius R7 of the fourth lens and the image-side curvature radius R8 of the fourth lens satisfy: -0.42 < (R7 - R8) / (R7 + R8) < -0.21.

[0019] More preferably, 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: -0.35 < f12 / f34 < 0; the combined focal length f123 of the first lens, the second lens and the third lens and the focal length f4 of the fourth lens satisfy: -0.7 < f123 / f4 < -0.25; the focal length f1 of the first lens and the combined focal length f234 of the second lens, the third lens and the fourth lens satisfy: 1 < f1 / f234 < 4.

[0020] The optical lens provided by this invention has four lenses with optical power. By matching specific surface shapes and allocating reasonable optical power, 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 small size, low distortion, and large image plane. Attached Figure Description

[0021] 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:

[0022] Figure 1 This is a schematic diagram of the optical lens structure in Embodiment 1 of the present invention.

[0023] Figure 2 This is an F-Tan (Theta) distortion curve of the optical lens in Embodiment 1 of the present invention.

[0024] Figure 3 This is an axial aberration curve of the optical lens in Embodiment 1 of the present invention.

[0025] Figure 4 This is a chromatic aberration curve of the optical lens in Embodiment 1 of the present invention.

[0026] Figure 5 This is an MTF curve of the optical lens in Embodiment 1 of the present invention.

[0027] Figure 6 This is a relative illumination curve of the optical lens in Embodiment 1 of the present invention.

[0028] Figure 7 This is a schematic diagram of the optical lens structure in Embodiment 2 of the present invention.

[0029] Figure 8 This is an F-Tan (Theta) distortion curve of the optical lens in Embodiment 2 of the present invention.

[0030] Figure 9 This is an axial aberration curve of the optical lens in Embodiment 2 of the present invention.

[0031] Figure 10 This is a chromatic aberration curve of the optical lens in Embodiment 2 of the present invention.

[0032] Figure 11 This is the MTF curve of the optical lens in Embodiment 2 of the present invention.

[0033] Figure 12 This is a relative illumination curve of the optical lens in Embodiment 2 of the present invention.

[0034] Figure 13 This is a schematic diagram of the optical lens in Embodiment 3 of the present invention.

[0035] Figure 14 This is an F-Tan (Theta) distortion curve of the optical lens in Embodiment 3 of the present invention.

[0036] Figure 15 This is an axial aberration curve of the optical lens in Embodiment 3 of the present invention.

[0037] Figure 16 This is a chromatic aberration curve of the optical lens in Embodiment 3 of the present invention.

[0038] Figure 17 This is an MTF curve of the optical lens in Embodiment 3 of the present invention.

[0039] Figure 18 This is a relative illumination curve of the optical lens in Embodiment 3 of the present invention.

[0040] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] 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.

[0047] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0048] This invention provides an optical lens with four lenses having optical power, which are arranged sequentially from the object side to the imaging plane along the optical axis as a first lens, a second lens, a third lens, and a fourth lens.

[0049] In some embodiments, the first lens may have positive optical power, its object-side surface may be concave, and its image-side surface may be convex. The second lens may have positive optical power, its object-side surface near the optical axis may be convex, and its image-side surface may be convex. The third lens may have positive optical power, its object-side surface near the optical axis may be concave, and its image-side surface near the optical axis may be convex. The fourth lens may have negative optical power, its object-side surface near the optical axis may be concave, and its image-side surface near the optical axis may be convex.

[0050] In some embodiments, the optical lens may further include an aperture stop, which may be located between the object plane and the first lens. It is understood that the aperture stop is used to limit the amount of light entering the lens, thereby altering the brightness of the image. When the aperture stop is located between the object plane and the first lens, it facilitates the correction of aperture aberrations.

[0051] In some embodiments, the optical lens may further include a filter and a protective glass, which are sequentially arranged between the fourth lens and the imaging surface along the optical axis. The filter is used to filter out interfering light to prevent the interfering light from reaching the imaging surface of the optical lens and affecting normal imaging. The protective glass plays a role in protecting the optical lens, preventing the photosensitive chip from being damaged, and can improve the anti-shock and scratch-resistant capabilities of the optical lens, while having little impact on the imaging quality of the optical lens.

[0052] 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: 1.3 < IH / f < 1.6; the object-side curvature radius R7 of the fourth lens and the image-side curvature radius R8 of the fourth lens satisfy: -0.45 < (R7 - R8) / (R7 + R8) < -0.2. Satisfying the above ranges is beneficial to achieving large target surface imaging of the lens and improving the imaging quality of the optical lens. At the same time, it is beneficial to reduce the aberration generated by the front lens. More specifically: 1.32 < IH / f < 1.51; -0.42 < (R7 - R8) / (R7 + R8) < -0.21.

[0053] In some embodiments, the overall optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 2.2 < TTL / f < 2.6; the overall 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 < 1.8. Satisfying the above ranges is beneficial to achieving the balance between miniaturization of the optical lens and a large image surface, making the lens have a smaller overall length. More specifically: 2.3 < TTL / f < 2.49; 1.64 < TTL / IH < 1.76.

[0054] In some embodiments, the maximum field of view FOV of the optical lens and the aperture value Fno of the optical lens satisfy: 30° < FOV / Fno < 43°; the true image height IH corresponding to the maximum field of view of the optical lens and the entrance pupil diameter EPD of the optical lens satisfy: 2.7 < IH / EPD < 3.1; the true image height IH corresponding to the maximum field of view of the optical lens, the effective focal length f of the optical lens and the radian value θ of the maximum half field of view of the optical lens satisfy: 1 < (IH / 2) / (f×θ) < 1.1; the true image height IH corresponding to the maximum field of view of the optical lens, the effective focal length f of the optical lens and the maximum field of view FOV of the optical lens satisfy: 0.88 < (IH / 2) / (f×Tan(FOV / 2)) < 1. Meeting the above ranges is beneficial to achieving more light input, ensuring high-definition imaging in a dim environment, and thus facilitating obtaining more scene information. And the optical lens can ensure sufficient image plane brightness in the edge field of view, prevent vignetting, and thus improve the imaging quality. At the same time, it can control the optical lens to have a small distortion and provide a clear imaging effect. More specifically: 31.63° < FOV / Fno < 42.12°; 2.84 < IH / EPD < 2.94; 1.07 < (IH / 2) / (f×θ) < 1.1; 0.88 < (IH / 2) / (f×Tan(FOV / 2)) < 0.97.

[0055] In some embodiments, the total optical length TTL of the optical lens, the true image height IH corresponding to the maximum field of view of the optical lens and the maximum field of view FOV of the optical lens satisfy: 14 < 180°×TTL / (IH / 2) / (FOV / 2) < 19; the effective focal length f of the optical lens, the maximum field of view FOV of the optical lens and the true image height IH corresponding to the maximum field of view of the optical lens satisfy: 50° < f×FOV / IH < 55°. Meeting the above ranges is beneficial to balancing the relationship among the total length, image height and field of view of the optical lens. At the same time, it is also beneficial to balancing the relationship among the focal length, field of view and image height of the optical lens. More specifically: 14.88 < 180°×TTL / (IH / 2) / (FOV / 2) < 18.07; 52.33° < f×FOV / IH < 53.27°.

[0056] In some embodiments, 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 the optical lens, and the maximum field angle FOV of the optical lens satisfy: 1 < d1 / (IH / 2) / Tan(FOV / 2) < 1.15; the clear aperture radius d1 of the object side surface of the first lens and the clear aperture radius d8 of the image side surface of the fourth lens satisfy: 0.4 < d1 / d8 < 0.44. Meeting the above ranges can reasonably arrange the overall geometry of the optical lens and improve its structural stability. At the same time, it can ensure smooth beam transmission, improve the light input efficiency, be beneficial to complete imaging, and avoid missing edge images.

[0057] In some embodiments, the focal length f1 of the first lens and the effective focal length f of the optical lens satisfy: 2 < f1 / f < 6; the radius of curvature R1 of the object side surface of the first lens and the effective focal length f of the optical lens satisfy: -0.7 < R1 / f < -0.5; the radius of curvature R2 of the image side surface of the first lens and the effective focal length f of the optical lens satisfy: -0.85 < R2 / f < -0.45. Meeting the above ranges can reasonably limit the proportion of the optical power of the first lens and its surface shape, converge light rays, reduce the height of peripheral light rays, and be beneficial to reducing the aperture of the rear lens. More specifically: 2.07 < f1 / f < 5.95; -0.67 < R1 / f < -0.55; -0.8 < R2 / f < -0.48.

[0058] In some embodiments, the focal length f2 of the second lens and the effective focal length f of the optical lens satisfy: 0.8 < f2 / f < 1.2; the radius of curvature R3 of the object side surface of the second lens and the effective focal length f of the optical lens satisfy: 0.9 < R3 / f < 1.5; the radius of curvature R4 of the image side surface of the second lens and the effective focal length f of the optical lens satisfy: -1.5 < R4 / f < -0.5. Meeting the above ranges can reasonably limit the proportion of the optical power of the second lens and its surface shape, be beneficial to light ray convergence, make the light ray trend transition smoothly to the rear, reduce the height of the light rays incident on the rear, slow down the upward trend of the light rays, and be beneficial to improving the illuminance of the edge field of view. More specifically: 0.83 < f2 / f < 1.18; 0.91 < R3 / f < 1.41; -1.44 < R4 / f < -0.52.

[0059] In some embodiments, the focal length f3 of the third lens and the effective focal length f of the optical lens satisfy: 0.9 < f3 / f < 2.1; the object-side curvature radius R5 of the third lens and the effective focal length f of the optical lens satisfy: -0.75 < R5 / f < -0.2; the image-side curvature radius R6 of the third lens and the effective focal length f of the optical lens satisfy: -0.6 < R6 / f < -0.2; the object-side curvature radius R5 of the third lens and the image-side curvature radius R6 of the third lens satisfy: 0 < (R5 - R6) / (R5 + R6) < 0.2. Meeting the above ranges and reasonably defining the proportion of the optical power and the surface shape of the third lens can optimize spherical aberration and achieve high-quality imaging. More specifically: 0.95 < f3 / f < 2.02; -0.71 < R5 / f < -0.25; -0.53 < R6 / f < -0.25; 0.01 < (R5 - R6) / (R5 + R6) < 0.16.

[0060] In some embodiments, the focal length f4 of the fourth lens and the effective focal length f of the optical lens satisfy: -2.5 < f4 / f < -0.8; the object-side curvature radius R7 of the fourth lens and the effective focal length f of the optical lens satisfy: -0.4 < R7 / f < -0.2; the image-side curvature radius R8 of the fourth lens and the effective focal length f of the optical lens satisfy: -0.7 < R8 / f < -0.4; the object-side clear aperture semi-diameter d7 of the fourth lens and the object-side clear aperture sagittal height Sag7 of the fourth lens satisfy: -9 < d7 / Sag7 < -3; the image-side clear aperture semi-diameter d8 of the fourth lens and the image-side clear aperture sagittal height Sag8 of the fourth lens satisfy: -12300 < d8 / Sag8 < -9. Meeting the above ranges and reasonably defining the proportion of the optical power and the surface shape of the fourth lens can effectively correct the aberration of the optical lens, improve the imaging quality. At the same time, it can also reduce the difficulty of aberration correction in the edge field of view. More specifically: -2.42 < f4 / f < -0.89; -0.31 < R7 / f < -0.24; -0.69 < R8 / f < -0.45; -8.84 < d7 / Sag7 < -3.08; -12210.4 < d8 / Sag8 < -9.45.

[0061] 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: -0.35 < f12 / f34 < 0; the combined focal length f123 of the first lens, the second lens and the third lens and the focal length f4 of the fourth lens satisfy: -0.7 < f123 / f4 < -0.25; the focal length f1 of the first lens and the combined focal length f234 of the second lens, the third lens and the fourth lens satisfy: 1 < f1 / f234 < 4. Meeting the above ranges is conducive to making the details at the edge and center of the picture consistent and avoiding blurring or deformation. More specifically: -0.33 < f12 / f34 < -0.01; -0.66 < f123 / f4 < -0.28; 1.09 < f1 / f234 < 3.98.

[0062] In some embodiments, the focal length f1 of the first lens and the focal length f2 of the second lens satisfy: 2.3 < f1 / f2 < 5.5. Meeting the above range and reasonably distributing the proportion of the optical power of the first lens and the second lens is conducive to correcting aberration and improving imaging clarity. More specifically: 2.44 < f1 / f2 < 5.09.

[0063] In some embodiments, the focal length f1 of the first lens and the focal length f3 of the third lens satisfy: 2 < f1 / f3 < 3.2. Meeting the above range and reasonably distributing the proportion of the optical power of the first lens and the third lens is conducive to precisely adjusting the total focal length, coordinating the light input efficiency, and improving the imaging brightness in low-light environments. More specifically: 2.15 < f1 / f3 < 2.96.

[0064] In some embodiments, the focal length f1 of the first lens and the focal length f4 of the fourth lens satisfy: -4 < f1 / f4 < -2.1. Meeting the above range and reasonably distributing the proportion of the optical power of the first lens and the fourth lens is conducive to balancing performance and structure, meeting the small-size design, and ensuring the imaging stability in complex light environments. More specifically: -3.86 < f1 / f4 < -2.29.

[0065] In some embodiments, the radius of curvature R2 of the image side of the first lens and the radius of curvature R3 of the object side of the second lens satisfy: -14 < (R2 - R3) / (R2 + R3) < -2. Meeting the above range is conducive to the smooth transition of light, reducing the scattering and loss of light during refraction, improving the overall light input efficiency of the lens, and making the imaging bright and uniform. More specifically: -13.01 < (R2 - R3) / (R2 + R3) < -2.08.

[0066] In some embodiments, the radius of curvature R4 of the image side surface of the second lens and the radius of curvature R5 of the object side surface of the third lens satisfy: 0.2 < (R4 - R5) / (R4 + R5) < 0.4. Meeting the above range is beneficial to correcting aberration and improving the picture clarity and detail restoration. More specifically: 0.27 < (R4 - R5) / (R4 + R5) < 0.35.

[0067] In some embodiments, the radius of curvature R6 of the image side surface of the third lens and the radius of curvature R7 of the object side surface of the fourth lens satisfy: 3.6 < (R6 + R7) / (R6 - R7) < 1020. Meeting the above range is beneficial to optimizing the collaborative performance between adjacent lenses and achieving the characteristic of small volume. More specifically: 3.65 < (R6 + R7) / (R6 - R7) < 1019.7.

[0068] In some embodiments, the optical lens satisfies the following conditional expressions: 2.5 mm < f < 3.1 mm; 65° < FOV < 85°; 1.3 mm < EPD < 1.45 mm; 6 mm < TTL < 7 mm; 1.8 < Fno < 2.3; 3.8 mm < IH < 4.1 mm; 20° < CRA < 23°; 1.7 mm < BFL < 1.8 mm. In the above conditional expressions, f represents the effective focal length of the optical lens, FOV represents the maximum field of view angle of the optical lens, EPD represents the entrance pupil diameter of the optical lens, TTL represents the 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 BFL represents the back focal length of the optical lens. Meeting the above range, the optical lens has at least one or more advantages such as small volume, small distortion, and large image plane. More specifically: 2.64 mm < f < 3 mm; 69.5° < FOV < 80.1°; 1.34 mm < EPD < 1.4 mm; 6.57 mm < TTL < 6.91 mm; 1.89 < Fno < 2.21; 3.94 mm < IH < 3.99 mm; 20.99° < CRA < 22.12°; 1.74 mm < BFL < 1.76 mm.

[0069] In some embodiments, the lens material in the optical lens provided by the present invention can be glass or plastic. When the lens material is plastic, the production cost can be effectively reduced. On the other hand, when the lens material is glass, the geometric chromatic aberration of the optical system can be effectively corrected by the low dispersion characteristic of the glass itself. The optical lens provided by the present invention adopts a lens structure with a combination of four glass and plastic lenses. More specifically, the first lens can adopt a glass lens, and the second lens, the third lens, and the fourth lens can adopt plastic lenses. Adopting a glass and plastic hybrid structure can improve the thermal stability, effectively reduce the cost, correct aberration, reduce the volume, and provide an optical lens product with higher cost performance.

[0070] In some embodiments, the first, second, third, and fourth lenses can be spherical 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 their size, and better achieving lens miniaturization. More specifically, in the optical lens provided by this invention, the first lens can be a spherical or aspherical lens, and the second, third, and fourth lenses can be aspherical lenses.

[0071] 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:

[0072] ;

[0073] 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.

[0074] 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.

[0075] Example 1

[0076] Please see Figure 1 The figure shown is a schematic diagram 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 surface, the following components in sequence: aperture ST, first lens L1, second lens L2, third lens L3, fourth lens L4, filter G1, and protective glass G2.

[0077] Among them, the first lens L1 has positive optical power, its object side S1 is concave, and its image side S2 is convex.

[0078] The second lens L2 has positive optical power, its object side S3 is convex near the optical axis, and its image side S4 is convex.

[0079] The third lens L3 has positive optical power, its object side S5 is concave near the optical axis, and its image side S6 is convex near the optical axis.

[0080] The fourth lens L4 has negative optical power, its object side S7 is concave near the optical axis, and its image side S8 is convex near the optical axis.

[0081] The object-side surface S9 and the image-side surface S10 of filter G1 are both planar.

[0082] The object side S11 and image side S12 of the protective glass G2 are both flat.

[0083] The imaging plane S13 is a plane.

[0084] The first lens L1 is a glass spherical lens, while the second lens L2, the third lens L3, and the fourth lens L4 are plastic aspherical lenses.

[0085] The relevant parameters of each lens in the optical lens 100 in Example 1 are shown in Table 1-1.

[0086] Table 1-1

[0087]

[0088] The surface profile parameters of the aspherical lens of the optical lens 100 in Example 1 are shown in Table 1-2.

[0089] Table 1-2

[0090]

[0091] In this embodiment, the F-Tan (Theta) distortion curve, axial aberration curve, transverse chromatic aberration curve, MTF curve, and relative illumination curve of the optical lens 100 are respectively as follows: Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 As shown.

[0092] Figure 2 The F-Tan (Theta) distortion curve of Example 1 is shown, which represents the F-Tan (Theta) distortion at different image heights on the imaging plane. The horizontal axis represents the distortion value (unit: %), and the vertical axis represents the half field of view (unit: °). As can be seen from the figure, the F-Tan (Theta) distortion of the optical lens 100 is controlled within ±6%, indicating that the distortion of the optical lens 100 is well corrected.

[0093] Figure 3The diagram shows the axial aberration curves for Embodiment 1, which represent the aberrations of each wavelength along 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 diagram, the axial aberration offset is controlled within -0.03 mm to 0.01 mm, indicating that the optical lens 100 can effectively correct axial aberrations.

[0094] Figure 4 The diagram shows the transverse chromatic aberration curves for Example 1, representing the chromatic aberration of each wavelength relative to the center wavelength (0.94 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.

[0095] Figure 5 The MTF (Modulation Transfer Function) curve of Example 1 is shown, which represents the lens imaging modulation at different spatial frequencies in various fields of view. The horizontal axis represents spatial frequency (unit: lp / mm), and the vertical axis represents MTF value. As can be seen from the figure, the MTF value of this example is above 0.4 throughout the entire field of view. Within the range of 0–120 lp / mm, the MTF curve decreases smoothly and uniformly from the center to the edge of the field of view, exhibiting good imaging quality and good detail resolution at both low and high frequencies.

[0096] 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 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 70% at the maximum half-field angle, indicating that the optical lens 100 has good relative illumination.

[0097] Example 2

[0098] Please see Figure 7 The figure shows 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 first lens L1 is a glass aspherical lens; the optical parameters such as the radius of curvature and lens thickness of each lens surface are different.

[0099] The relevant parameters of each lens in the optical lens 200 in Example 2 are shown in Table 2-1.

[0100] Table 2-1

[0101]

[0102] The surface profile parameters of the aspherical lens of the optical lens 200 in Example 2 are shown in Table 2-2.

[0103] Table 2-2

[0104]

[0105] In this embodiment, the F-Tan (Theta) distortion curve, axial aberration curve, transverse chromatic aberration curve, MTF curve, and relative illumination curve of the optical lens 200 are respectively as follows: Figure 8 , Figure 9 , Figure 10 , Figure 11 , Figure 12 As shown.

[0106] from Figure 8 As can be seen, the F-Tan (Theta) distortion of optical lens 200 is controlled within ±6%, indicating that the distortion of optical lens 200 has been well corrected.

[0107] from Figure 9 As can be seen, the axial aberration offset is controlled within -0.05mm to 0.01mm, indicating that the optical lens 200 can correct axial aberration well.

[0108] from Figure 10 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 11 As 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 smoothly and evenly from the center to the edge of the field of view. It has good imaging quality and good detail resolution in both low and high frequency conditions.

[0110] from Figure 12 As can be seen, the relative illumination value of the optical lens is still greater than 70% at the maximum half field of view, indicating that the optical lens 200 has good relative illumination.

[0111] Example 3

[0112] Please see Figure 13 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.

[0113] The relevant parameters of each lens in the optical lens 300 in Example 3 are shown in Table 3-1.

[0114] Table 3-1

[0115]

[0116] The surface profile parameters of the aspherical lens of the optical lens 300 in Example 3 are shown in Table 3-2.

[0117] Table 3-2

[0118]

[0119] In this embodiment, the F-Tan (Theta) distortion curve, axial aberration curve, transverse chromatic aberration curve, MTF curve, and relative illumination curve of the optical lens 300 are respectively as follows: Figure 14 , Figure 15 , Figure 16 , Figure 17 , Figure 18 As shown.

[0120] from Figure 14 As can be seen, the F-Tan (Theta) distortion of optical lens 300 is controlled within -15% to 5%, indicating that the distortion of optical lens 300 can be corrected.

[0121] from Figure 15 As can be seen, the axial aberration offset is controlled within -0.04mm to 0.01mm, indicating that the optical lens 300 can correct axial aberration well.

[0122] from Figure 16 As can be seen, the transverse chromatic aberration of the longest and shortest wavelengths is controlled within ±2μm, indicating that the optical lens 300 can effectively correct transverse chromatic aberration.

[0123] from Figure 17 As 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 smoothly and evenly from the center to the edge of the field of view. It has good imaging quality and good detail resolution in both low and high frequency conditions.

[0124] from Figure 18 As can be seen, the relative illumination value of the optical lens is still greater than 60% at the maximum half field of view, indicating that the optical lens 300 has good relative illumination.

[0125] Please refer to Tables 4-1 and 4-2 for the optical characteristics corresponding to the above embodiments, including the effective focal length f, total optical length TTL, aperture value Fno, principal ray incident angle CRA at maximum image height, true image height IH corresponding to the maximum field of view, maximum field of view FOV, entrance pupil diameter EPD, back focal length BFL, and the values ​​corresponding to each conditional expression in each embodiment.

[0126] Table 4-1

[0127]

[0128] Table 4-2

[0129]

[0130] In summary, the optical lens provided by the present invention has 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 small size, low distortion, and large image plane.

[0131] 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.

[0132] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but 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 all fall within the protection scope of the present invention. Therefore, the protection scope 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 sequentially includes from the object side to the imaging surface along the optical axis: A first lens with positive optical power, whose object side is concave and whose image side is convex; A second lens with positive optical power, whose object side is convex near the optical axis and whose image side is convex; A third lens with positive optical power, whose object side is concave near the optical axis and whose image side is convex near the optical axis; A fourth lens with negative optical power, whose object side is concave near the optical axis and whose image side is convex near the optical axis; Wherein, 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: 1.3 < IH / f < 1.6; the curvature radius R7 of the object side of the fourth lens and the curvature radius R8 of the image side of the fourth lens satisfy: -0.45 < (R7 - R8) / (R7 + R8) < -0.2; the focal length f1 of the first lens and the effective focal length f of the optical lens satisfy: 2 < f1 / f < 6; 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: 1 < d1 / (IH / 2) / Tan(FOV / 2) < 1.

15.

2. The optical lens according to claim 1, characterized in that, The optical lens satisfies at least one of the following conditional expressions. The overall optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 2.2 < TTL / f < 2.6; the overall 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 < 1.

8.

3. The optical lens according to claim 1, characterized in that, The optical lens satisfies at least one of the following conditional expressions. The maximum field angle FOV of the optical lens and the f-number Fno of the optical lens satisfy: 30° < FOV / Fno < 43°; 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: 2.7 < IH / EPD < 3.1; 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 radian value θ of the maximum semi-field angle of the optical lens satisfy: 1 < (IH / 2) / (f×θ) < 1.1; 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: 0.88 < (IH / 2) / (f×Tan(FOV / 2)) < 1.

4. The optical lens according to claim 1, characterized in that, The optical lens satisfies at least one of the following conditional expressions. The overall 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: 14 < 180°×TTL / (IH / 2) / (FOV / 2) < 19; 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: 50° < f×FOV / IH < 55°.

5. The optical lens according to claim 1, characterized in that, The optical lens satisfies at least one of the following conditional expressions. 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: 1.32 < IH / f < 1.51; the curvature radius R7 of the object side surface of the fourth lens and the curvature radius R8 of the image side surface of the fourth lens satisfy: -0.42 < (R7 - R8) / (R7 + R8) < -0.21; 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: 0.4 < d1 / d8 < 0.

44.

6. The optical lens according to claim 1, characterized in that, The optical lens satisfies at least one of the following conditional expressions. The focal length f1 of the first lens and the effective focal length f of the optical lens satisfy: 2.07 < f1 / f < 5.95; the curvature radius R1 of the object side surface of the first lens and the effective focal length f of the optical lens satisfy: -0.7 < R1 / f < -0.5; the curvature radius R2 of the image side surface of the first lens and the effective focal length f of the optical lens satisfy: -0.85 < R2 / f < -0.

45.

7. The optical lens according to claim 1, characterized in that, The optical lens satisfies at least one of the following conditional expressions. The focal length f2 of the second lens and the effective focal length f of the optical lens satisfy: 0.8 < f2 / f < 1.2; the curvature radius R3 of the object side surface of the second lens and the effective focal length f of the optical lens satisfy: 0.9 < R3 / f < 1.5; the curvature radius R4 of the image side surface of the second lens and the effective focal length f of the optical lens satisfy: -1.5 < R4 / f < -0.

5.

8. The optical lens according to claim 1, characterized in that, The optical lens satisfies at least one of the following conditional expressions. The focal length f3 of the third lens and the effective focal length f of the optical lens satisfy: 0.9 < f3 / f < 2.1; the curvature radius R5 of the object side surface of the third lens and the effective focal length f of the optical lens satisfy: -0.75 < R5 / f < -0.2; the curvature radius R6 of the image side surface of the third lens and the effective focal length f of the optical lens satisfy: -0.6 < R6 / f < -0.2; the curvature radius R5 of the object side surface of the third lens and the curvature radius R6 of the image side surface of the third lens satisfy: 0 < (R5 - R6) / (R5 + R6) < 0.

2.

9. The optical lens according to claim 1, characterized in that, The optical lens satisfies at least one of the following conditional expressions. The focal length f4 of the fourth lens and the effective focal length f of the optical lens satisfy: -2.5 < f4 / f < -0.8; the object-side curvature radius R7 of the fourth lens and the effective focal length f of the optical lens satisfy: -0.4 < R7 / f < -0.2; the image-side curvature radius R8 of the fourth lens and the effective focal length f of the optical lens satisfy: -0.7 < R8 / f < -0.4; the object-side clear aperture semi-diameter d7 of the fourth lens and the object-side clear aperture sagittal height Sag7 of the fourth lens satisfy: -9 < d7 / Sag7 < -3; the image-side clear aperture semi-diameter d8 of the fourth lens and the image-side clear aperture sagittal height Sag8 of the fourth lens satisfy: -12300 < d8 / Sag8 < -9; the object-side curvature radius R7 of the fourth lens and the image-side curvature radius R8 of the fourth lens satisfy: -0.42 < (R7 - R8) / (R7 + R8) < -0.

21.

10. The optical lens according to claim 1, characterized in that, The optical lens satisfies at least one of the following conditional expressions. 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: -0.35 < f12 / f34 < 0; the combined focal length f123 of the first lens, the second lens, and the third lens and the focal length f4 of the fourth lens satisfy: -0.7 < f123 / f4 < -0.25; the focal length f1 of the first lens and the combined focal length f234 of the second lens, the third lens, and the fourth lens satisfy: 1 < f1 / f234 < 4.

Images