Optical lens

Abstract

The invention provides an optical lens, which comprises four lenses with focal power and sequentially comprises a first lens with positive focal power, a second lens with negative focal power, a third lens with positive focal power, a fourth lens with negative focal power, a fifth lens with positive focal power and a sixth lens with negative focal power from an object side to an imaging surface along an optical axis, the second lens has positive focal power, the object side surface of the second lens near the optical axis is a convex surface, and the image side surface of the second lens is a convex surface; the third lens has positive focal power, the object side surface of the third lens is a concave surface near the optical axis, and the image side surface of the third lens is a convex surface near the optical axis; the fourth lens has negative focal power, the object side surface of the fourth lens is a concave surface near the optical axis, and the image side surface of the fourth lens is a convex surface near the optical axis; wherein the real image height IH corresponding to the maximum field angle of the optical lens and the effective focal length f of the optical lens meet the following conditions: 1.3 lt; iH / flt; 1.6); 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 meet the following formula:-0.45 lt; (R7-R8) / (R7 + R8) lt; and-0.2%. According to the optical lens provided by the invention, the overall aberration of the optical lens can be reasonably corrected, and the imaging quality of the optical lens is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of imaging lenses, in particular to an optical lens. BACKGROUND

[0002] With the popularization and wide application of automobile auxiliary driving technology, the demand for driving safety continues to rise, and driver state recognition has become a core demand. The core goal is to predict driving risks and timely remind standard operation. The vehicle-mounted DMS lens needs to be adapted to the complex light environment in the vehicle, with high relative luminance and low distortion characteristics, to avoid the influence of dark corners or deformation on facial feature capture, while meeting the stringent requirements of small size, shock resistance and high temperature resistance in vehicle-mounted scenes. However, the lenses on the market generally have problems such as insufficient edge definition and poor light adaptability, which are difficult to support high-precision state recognition. Therefore, it is an urgent need for the current industry development to develop an optical lens with excellent imaging effect and strong adaptability. SUMMARY

[0003] In view of the above problems, the purpose of the present application is to provide an optical lens with excellent imaging quality.

[0004] The technical scheme adopted by the present application is: An optical lens has four lenses with optical power, which includes, along the optical axis from the object side to the imaging surface: 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 real 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.

[0005] 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 real image height IH corresponding to the maximum field angle of the optical lens satisfy: 1.6<TTL / IH<1.8.

[0006] Further preferably, 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 real 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 real 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; and the real 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.

[0007] Further preferably, the total optical length TTL of the optical lens, the real 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 real image height IH corresponding to the maximum field of view of the optical lens satisfy: 50°<f×FOV / IH<55°.

[0008] Further preferably, the object side half light entrance radius d1 of the first lens, the real 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: 1<d1 / (IH / 2) / Tan(FOV / 2)<1.15; and the object side half light entrance radius d1 of the first lens and the image side half light entrance radius d8 of the fourth lens satisfy: 0.4<d1 / d8<0.44.

[0009] 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 object side curvature radius R1 of the first lens and the effective focal length f of the optical lens satisfy: -0.7<R1 / f<-0.5; and the image side curvature radius R2 of the first lens and the effective focal length f of the optical lens satisfy: -0.85<R2 / f<-0.45.

[0010] Further 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; and 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.

[0011] Further 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 surface 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 surface 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 surface curvature radius R5 of the third lens and the image side surface curvature radius R6 of the third lens satisfy: 0 < (R5-R6) / (R5+R6) < 0.2.

[0012] Further 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 surface 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 surface 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 surface half light entrance radius d7 of the fourth lens and the object side surface sag of the fourth lens Sag7 satisfy: -9 < d7 / Sag7 < -3; the image side surface half light entrance radius d8 of the fourth lens and the image side surface sag of the fourth lens Sag8 satisfy: -12 < d8 / Sag8 < -9; the object side surface curvature radius R7 of the fourth lens and the image side surface curvature radius R8 of the fourth lens satisfy: -0.42 < (R7-R8) / (R7+R8) < -0.21.

[0013] Further 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.

[0014] The optical lens provided by the present application has four lenses with optical power. Through specific surface shape matching and reasonable optical power distribution, the imaging quality of the optical lens is improved, the aberration is reduced, and the imaging quality of the optical lens is improved, so that the lens has one or more advantages of small volume, small distortion, large image surface, etc. BRIEF DESCRIPTION OF DRAWINGS

[0015] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description, taken in conjunction with the following drawings, in which: Figure 1A schematic view of the optical lens in Embodiment 1 of the present application.

[0016] Figure 2 A F-Tan(Theta) distortion curve of the optical lens in Embodiment 1 of the present application.

[0017] Figure 3 An axial aberration curve of the optical lens in Embodiment 1 of the present application.

[0018] Figure 4 A sagittal color aberration curve of the optical lens in Embodiment 1 of the present application.

[0019] Figure 5 An MTF curve of the optical lens in Embodiment 1 of the present application.

[0020] Figure 6 A relative illumination curve of the optical lens in Embodiment 1 of the present application.

[0021] Figure 7 A schematic view of the optical lens in Embodiment 2 of the present application.

[0022] Figure 8 A F-Tan(Theta) distortion curve of the optical lens in Embodiment 2 of the present application.

[0023] Figure 9 An axial aberration curve of the optical lens in Embodiment 2 of the present application.

[0024] Figure 10 A sagittal color aberration curve of the optical lens in Embodiment 2 of the present application.

[0025] Figure 11 An MTF curve of the optical lens in Embodiment 2 of the present application.

[0026] Figure 12 A relative illumination curve of the optical lens in Embodiment 2 of the present application.

[0027] Figure 13 A schematic view of the optical lens in Embodiment 3 of the present application.

[0028] Figure 14 A F-Tan(Theta) distortion curve of the optical lens in Embodiment 3 of the present application.

[0029] Figure 15 An axial aberration curve of the optical lens in Embodiment 3 of the present application.

[0030] Figure 16 A sagittal color aberration curve of the optical lens in Embodiment 3 of the present application.

[0031] Figure 17MTF curve graph of the optical lens in Embodiment 3 of the present application.

[0032] Figure 18 Relative luminance curve graph of the optical lens in Embodiment 3 of the present application.

[0033] The following detailed description will further describe the present application with reference to the above-mentioned drawings. DETAILED DESCRIPTION

[0034] For a better understanding of the present application, various aspects of the present application will be described in more detail with reference to the accompanying drawings. It is to be noted that the detailed description is only a description of embodiments of the present application and is not intended to limit the scope of the present application in any way. Throughout the specification, like drawing reference numerals refer to like elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0035] It should be noted that the expressions first, second, third, and the like in the present specification are used only to distinguish one feature from another feature, and do not indicate any limitation on the features. Thus, the first lens discussed below can also be referred to as the second lens or the third lens without departing from the teachings of the present application.

[0036] In the drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for convenience of explanation. Specifically, the shape of the spherical surface or aspherical surface shown in the drawings is shown by way of example. That is, the shape of the spherical surface or aspherical surface is not limited to the shape of the spherical surface or aspherical surface shown in the drawings. The drawings are merely examples and are not drawn to scale.

[0037] In this context, the paraxial region refers to a region near the optical axis. If a lens surface is convex and the position of the convex surface is not specified, it means that the lens surface is convex at least in the paraxial region. If a lens surface is concave and the position of the concave surface is not specified, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object is referred to as the object side surface of the lens, and the surface of each lens closest to the image plane is referred to as the image side surface of the lens.

[0038] It should also be understood that the words "comprise", "comprising", "include", "including", and / or "contain", when used in this specification, specify the presence of stated features, elements, and / or components, but do not preclude the presence or addition of one or more other features, elements, components, and / or groups thereof. Furthermore, when describing the embodiments of the present application, the use of "may" means one or more embodiments of the present application. Also, the word "exemplary" is intended to mean an example or an illustration.

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

[0040] It should be noted that the embodiments and features of the embodiments in the present application can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0041] The optical lens provided by the embodiments of the present application has four lenses with optical power, which are sequentially arranged along the optical axis from the object side to the imaging surface as the first lens, the second lens, the third lens and the fourth lens.

[0042] In some embodiments, the first lens can have positive optical power, the object side surface thereof can be a concave surface, and the image side surface thereof can be a convex surface. The second lens can have positive optical power, the object side surface thereof can be a convex surface at the near optical axis, and the image side surface thereof can be a convex surface. The third lens can have positive optical power, the object side surface thereof can be a concave surface at the near optical axis, and the image side surface thereof can be a convex surface at the near optical axis. The fourth lens can have negative optical power, the object side surface thereof can be a concave surface at the near optical axis, and the image side surface thereof can be a convex surface at the near optical axis.

[0043] In some embodiments, the optical lens can further include a diaphragm, which can be located between the object plane and the first lens. It can be understood that the diaphragm is used to limit the amount of light to change the brightness of the imaging. When the diaphragm is located between the object plane and the first lens, the correction of the diaphragm aberration is facilitated.

[0044] In some embodiments, the optical lens can further include a filter and a protective glass, which are sequentially arranged along the optical axis between the fourth lens and the imaging surface. The filter is used to filter out the interference light to prevent the interference light from reaching the imaging surface of the optical lens and affecting the normal imaging. The protective glass plays a role of protecting the optical lens, prevents the photosensitive chip from being damaged, and can improve the impact resistance and scratch resistance of the optical lens, while having little effect on the imaging quality of the optical lens.

[0045] In some embodiments, the real image height IH corresponding to the maximum field of view 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 surface radius of curvature R7 of the fourth lens and the image side surface radius of curvature R8 of the fourth lens satisfy: -0.45 < (R7-R8) / (R7+R8) < -0.2. Satisfying the above range is conducive to realizing large target surface imaging of the lens and improving the imaging quality of the optical lens. At the same time, it is conducive to reducing the aberration generated by the front end lens. More specifically: 1.32 < IH / f < 1.51; -0.42 < (R7-R8) / (R7+R8) < -0.21.

[0046] In some embodiments, 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 real image height IH corresponding to the maximum field of view angle of the optical lens satisfy: 1.6 < TTL / IH < 1.8. Satisfying the above range is conducive to achieving a balance between miniaturization and large image of the optical lens, so that the lens has a smaller total length. More specifically: 2.3 < TTL / f < 2.49; 1.64 < TTL / IH < 1.76.

[0047] In some embodiments, the maximum field of view angle FOV of the optical lens and the aperture value Fno of the optical lens satisfy: 30° < FOV / Fno < 43°; the real image height IH corresponding to the maximum field of view angle of the optical lens and the entrance pupil diameter EPD of the optical lens satisfy: 2.7 < IH / EPD < 3.1; the real image height IH corresponding to the maximum field of view angle 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 angle of the optical lens satisfy: 1 < (IH / 2) / (f x θ) < 1.1; the real image height IH corresponding to the maximum field of view angle of the optical lens, the effective focal length f of the optical lens and the maximum field of view angle FOV of the optical lens satisfy: 0.88 < (IH / 2) / (f x Tan(FOV / 2)) < 1. Satisfying the above range is conducive to realizing more light quantity, ensuring that high-definition imaging can be realized in a dim environment, thereby facilitating the acquisition of more scene information. And the optical lens can satisfy that the edge field of view has sufficient image plane brightness, preventing the occurrence of dark corners, thereby improving the imaging quality. At the same time, it can control the optical lens to have smaller distortion, which can provide clear imaging effect. More specifically: 31.63° < FOV / Fno < 42.12°; 2.84 < IH / EPD < 2.94; 1.07 < (IH / 2) / (f x θ) < 1.1; 0.88 < (IH / 2) / (f x Tan(FOV / 2)) < 0.97.

[0048] In some embodiments, the optical total length TTL of the optical lens, the real image height IH corresponding to the maximum field of view angle of the optical lens, and the maximum field of view angle FOV of the optical lens satisfy: 14 < 180°xTTL / (IH / 2) / (FOV / 2) < 19; the effective focal length f of the optical lens, the maximum field of view angle FOV of the optical lens, and the real image height IH corresponding to the maximum field of view angle of the optical lens satisfy: 50° < f x FOV / IH < 55°. Satisfying the above ranges is conducive to balancing the relationship among the total length, the image height, and the field of view angle of the optical lens. Meanwhile, it is also conducive to balancing the relationship among the focal length, the field of view angle, and the image height of the optical lens. More specifically, 14.88 < 180°xTTL / (IH / 2) / (FOV / 2) < 18.07; 52.33° < f x FOV / IH < 53.27°.

[0049] In some embodiments, the half light passing diameter d1 of the object side of the first lens, the real image height IH corresponding to the maximum field of view angle of the optical lens, and the maximum field of view angle FOV of the optical lens satisfy: 1 < d1 / (IH / 2) / Tan(FOV / 2) < 1.15; the half light passing diameter d1 of the object side of the first lens and the half light passing diameter d8 of the image side of the fourth lens satisfy: 0.4 < d1 / d8 < 0.44. Satisfying the above ranges can reasonably arrange the overall geometric shape of the optical lens and improve its structural stability. Meanwhile, it can ensure smooth transmission of light beams, improve light efficiency, be conducive to complete imaging, and avoid missing of edge pictures.

[0050] 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 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. Satisfying the above ranges reasonably limits the power ratio and surface shape of the first lens, which can converge light rays, lower the height of peripheral light rays, and be conducive 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.

[0051] 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 object-side surface curvature radius R3 of the second lens and the effective focal length f of the optical lens satisfy: 0.9 < R3 / f < 1.5; and the image-side surface curvature radius R4 of the second lens and the effective focal length f of the optical lens satisfy: -1.5 < R4 / f < -0.5. Satisfying the above ranges, the proportion of the refractive power of the second lens and the surface shape thereof are reasonably limited, which is beneficial to light convergence, makes the light trend transition smoothly to the rear, reduces the height of the light incident to the rear, slows down the upward trend of the light, and is beneficial to improving the illumination of the edge field of view. More specifically, 0.83 < f2 / f < 1.18; 0.91 < R3 / f < 1.41; and -1.44 < R4 / f < -0.52.

[0052] 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 surface 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 surface curvature radius R6 of the third lens and the effective focal length f of the optical lens satisfy: -0.6 < R6 / f < -0.2; and the object-side surface curvature radius R5 of the third lens and the image-side surface curvature radius R6 of the third lens satisfy: 0 < (R5-R6) / (R5+R6) < 0.2. Satisfying the above ranges, the proportion of the refractive power of the third lens and the surface shape thereof are reasonably limited, which can optimize the spherical aberration and realize high-quality imaging. More specifically, 0.95 < f3 / f < 2.02; -0.71 < R5 / f < -0.25; -0.53 < R6 / f < -0.25; and 0.01 < (R5-R6) / (R5+R6) < 0.16.

[0053] 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 radius of curvature R7 of the object side surface of the fourth lens and the effective focal length f of the optical lens satisfy: -0.4 < R7 / f < -0.2; the radius of curvature R8 of the image side surface of the fourth lens and the effective focal length f of the optical lens satisfy: -0.7 < R8 / f < -0.4; the half-field radius d7 of the object side surface of the fourth lens and the half-field radius sag7 of the object side surface of the fourth lens satisfy: -9 < d7 / sag7 < -3; the half-field radius d8 of the image side surface of the fourth lens and the half-field radius sag8 of the image side surface of the fourth lens satisfy: -12300 < d8 / sag8 < -9. Satisfying the above ranges, the proportion of the refractive power of the fourth lens and the surface shape thereof are reasonably limited, which can effectively correct the aberration of the optical lens and improve the imaging quality. Meanwhile, the difficulty of aberration correction in the edge field of view can be reduced. 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.

[0054] 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. Satisfying the above ranges, the details of the picture edge and the center are consistent, and blurring or deformation is avoided. More specifically, -0.33 < f12 / f34 < -0.01; -0.66 < f123 / f4 < -0.28; 1.09 < f1 / f234 < 3.98.

[0055] 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. Satisfying the above range, the proportion of the refractive power of the first lens and the second lens is reasonably distributed, which is beneficial to correcting aberration and improving imaging clarity. More specifically, 2.44 < f1 / f2 < 5.09.

[0056] 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. Satisfying the above range, the proportion of the refractive power of the first lens and the third lens is reasonably distributed, which is beneficial to accurately adjusting the total focal length, coordinating the light efficiency and improving the imaging brightness in a low-light environment. More specifically, 2.15 < f1 / f3 < 2.96.

[0057] 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. Satisfying the above range, the proportion of the optical power of the first lens and the fourth lens is reasonably distributed, which is conducive to balancing performance and structure, meeting the small size design, and guaranteeing the imaging stability in complex light environment. More specifically: -3.86 < f1 / f4 < -2.29.

[0058] In some embodiments, the image-side surface curvature radius R2 of the first lens and the object-side surface curvature radius R3 of the second lens satisfy: -14 < (R2-R3) / (R2+R3) < -2. Satisfying the above range is conducive to smooth transition of light, reducing scattering and loss of light in the refraction process, improving the overall light efficiency of the lens, and making the imaging bright and uniform. More specifically: -13.01 < (R2-R3) / (R2+R3) < -2.08.

[0059] In some embodiments, the image-side surface curvature radius R4 of the second lens and the object-side surface curvature radius R5 of the third lens satisfy: 0.2 < (R4-R5) / (R4+R5) < 0.4. Satisfying the above range is conducive to correcting aberration, improving picture clarity and detail restoration. More specifically: 0.27 < (R4-R5) / (R4+R5) < 0.35.

[0060] In some embodiments, the image-side surface curvature radius R6 of the third lens and the object-side surface curvature radius R7 of the fourth lens satisfy: 3.6 < (R6+R7) / (R6-R7) < 1020. Satisfying the above range is conducive to optimizing the synergistic performance between adjacent lenses, achieving small size characteristics. More specifically: 3.65 < (R6+R7) / (R6-R7) < 1019.7.

[0061] In some embodiments, the optical lens satisfies the following conditional expressions: 2.5mm < f < 3.1mm; 65° < FOV < 85°; 1.3mm < EPD < 1.45mm; 6mm < TTL < 7mm; 1.8 < Fno < 2.3; 3.8mm < IH < 4.1mm; 20° < CRA < 23°; 1.7mm < BFL < 1.8mm. 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 real image height corresponding to the maximum field of view angle of the optical lens, CRA represents the chief ray angle of incidence at the maximum image height of the optical lens, and BFL represents the back focal length of the optical lens. Satisfying the above ranges, the optical lens has one or more advantages such as small volume, small distortion, large image surface, etc. More specifically: 2.64mm < f < 3mm; 69.5° < FOV < 80.1°; 1.34mm < EPD < 1.4mm; 6.57mm < TTL < 6.91mm; 1.89 < Fno < 2.21; 3.94mm < IH < 3.99mm; 20.99° < CRA < 22.12°; 1.74mm < BFL < 1.76mm.

[0062] In some embodiments, the lens material in the optical lens provided by the present application can be glass or plastic. When the lens material is plastic, the production cost can be effectively reduced. 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 application adopts a four-piece lens structure with glass-plastic hybrid arrangement. 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. The glass-plastic hybrid structure can improve the thermal stability, effectively reduce the cost, correct the aberration, reduce the volume, and provide an optical lens product with higher performance-price ratio.

[0063] In some embodiments, the first lens, the second lens, the third lens, and the fourth lens can adopt a spherical lens or an aspherical lens. Compared with the spherical structure, the aspherical structure can effectively reduce the aberration of the optical system, thereby reducing the number of lenses and the size of the lenses, and better realizing the miniaturization of the lens. More specifically, the first lens in the optical lens provided by the present application can adopt a spherical lens or an aspherical lens, and the second lens, the third lens, and the fourth lens can adopt an aspherical lens.

[0064] In various embodiments of the present application, when the lens adopts an aspherical lens, the shape of each aspherical surface of the optical lens satisfies the following equation: ; Wherein, z is the distance of the curved surface and the curved surface vertex in the direction of the optical axis, h is the distance of the optical axis to the curved surface, c is the curvature of the curved surface vertex, K is the quadratic curved surface coefficient, B, C, D, E, F are the fourth order, sixth order, eighth order, tenth order, twelfth order curved surface coefficients respectively.

[0065] The application will be further described in the following embodiments. In each embodiment, the thickness, the radius of curvature, the material selection of each lens in the optical lens are different, and the specific differences can be referred to the parameter table of each embodiment. The following embodiments are only the preferred embodiments of the application, but the embodiments of the application are not limited to the following embodiments only, any change, replacement, combination or simplification made without departing from the innovative points of the application should be regarded as equivalent replacement mode, and all are included in the protection scope of the application.

[0066] Embodiment 1 Please refer to Figure 1 , which is a structural schematic diagram of the optical lens 100 provided in the embodiment 1 of the application, the optical lens 100 includes, along the optical axis from the object side to the imaging surface, a diaphragm ST, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a filter G1 and a protective glass G2.

[0067] The first lens L1 has positive focal power, the object side S1 thereof is a concave surface, and the image side S2 thereof is a convex surface; The second lens L2 has positive focal power, the object side S3 thereof is a convex surface at the near optical axis, and the image side S4 thereof is a convex surface; The third lens L3 has positive focal power, the object side S5 thereof is a concave surface at the near optical axis, and the image side S6 thereof is a convex surface at the near optical axis; The fourth lens L4 has negative focal power, the object side S7 thereof is a concave surface at the near optical axis, and the image side S8 thereof is a convex surface at the near optical axis; The object side S9 and the image side S10 of the filter G1 are both planes; The object side S11 and the image side S12 of the protective glass G2 are both planes; The imaging surface S13 is a plane.

[0068] The first lens L1 adopts a glass spherical lens, and the second lens L2, the third lens L3 and the fourth lens L4 adopt plastic aspherical lenses.

[0069] The related parameters of each lens in the optical lens 100 in the embodiment 1 are shown in Table 1-1.

[0070] Table 1-1 The surface type parameters of the aspherical lenses of the optical lens 100 in the embodiment 1 are shown in Table 1-2.

[0071] Table 1-2 In the present embodiment, the F-Tan(Theta) distortion curve, the axial aberration curve, the lateral chromatic aberration curve, the MTF curve and the relative illumination curve of the optical lens 100 are shown in FIGS. 1-2, 1-3, 1-4, 1-5 and 1-6 respectively. Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6

[0072] Figure 2 The F-Tan(Theta) distortion curve of Example 1 is shown in FIG. 1-2, 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 angle (unit: °). As can be seen from the figure, the F-Tan(Theta) distortion of the optical lens 100 is controlled within ±6%, which shows that the distortion of the optical lens 100 is well corrected.

[0073] Figure 3 The axial aberration curve of Example 1 is shown in FIG. 1-3, which represents the axial 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 offset of the axial aberration is controlled within -0.03mm~0.01mm, which shows that the optical lens 100 can better correct the axial aberration.

[0074] Figure 4 The lateral chromatic aberration curve of Example 1 is shown in FIG. 1-4, which represents the lateral chromatic aberration of each wavelength at different image heights on the imaging plane relative to the central wavelength (0.94μm), the horizontal axis represents the lateral chromatic aberration value of each wavelength relative to the central wavelength (unit: μm), and the vertical axis represents the normalized field angle. As can be seen from the figure, the lateral chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±1μm, which shows that the optical lens 100 can better correct the lateral chromatic aberration.

[0075] Figure 5 The MTF (Modulation Transfer Function) curve of Example 1 is shown in FIG. 1-5, which represents the lens imaging modulation degree of different spatial frequencies under each field of view, the horizontal axis represents the spatial frequency (unit: lp / mm), and the vertical axis represents the MTF value. As can be seen from the figure, the MTF value of the present embodiment is above 0.4 within the full field of view, and in the range of 0~120lp / mm, the MTF curve uniformly and smoothly decreases from the center to the edge of the field of view, and has good imaging quality and good detail resolution ability in the case of low frequency and high frequency.

[0076] Figure 6 ​The relative luminance curve of the optical lens 100 is shown in FIG. 1, which represents the relative luminance values of different field angles on the imaging plane, the horizontal axis represents the half field angle (unit: °), and the vertical axis represents the relative luminance (unit: %). As can be seen from the figure, the relative luminance value of the optical lens 100 is still greater than 70% at the maximum half field angle, which indicates that the optical lens 100 has good relative luminance.

[0077] Embodiment 2 Please refer to Figure 7 , which is a structural schematic diagram of the optical lens 200 provided in Embodiment 2 of the present application. Compared with Embodiment 1, the main difference is that the first lens L1 is a glass aspheric lens; the optical parameters such as the curvature radius of each lens surface and the lens thickness are different.

[0078] The related parameters of each lens in the optical lens 200 in Embodiment 2 are shown in Table 2-1.

[0079] Table 2-1 The surface type parameters of the aspheric lens of the optical lens 200 in Embodiment 2 are shown in Table 2-2.

[0080] Table 2-2 In this embodiment, the F-Tan(Theta) distortion curve, the axial aberration curve, the vertical axis chromatic aberration curve, the MTF curve and the relative luminance curve of the optical lens 200 are shown in Figure 8 、 Figure 9 、 Figure 10 、 Figure 11 、 Figure 12 respectively.

[0081] As can be seen from Figure 8 , the F-Tan(Theta) distortion of the optical lens 200 is controlled within ±6%, which indicates that the distortion of the optical lens 200 is well corrected.

[0082] As can be seen from Figure 9 , the shift of the axial aberration is controlled within -0.05mm~0.01mm, which indicates that the optical lens 200 can well correct the axial aberration.

[0083] As can be seen from Figure 10 , the vertical axis chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±1μm, which indicates that the optical lens 200 can well correct the vertical axis chromatic aberration.

[0084] As can be seen from Figure 11As can be seen from the MTF curves in the full field of view, the MTF values of the optical lens 200 in the full field of view are all greater than 0.4, the MTF curves are uniformly and smoothly decreased from the center to the edge of the field of view in the range of 0-120 lp / mm, and the optical lens 200 has good imaging quality and good detail resolution capability in the case of low frequency and high frequency.

[0085] From Figure 12 As can be seen from the relative illumination curves of the optical lens 200 in the maximum half field of view, the relative illumination value of the optical lens 200 is still greater than 70%, which indicates that the optical lens 200 has good relative illumination.

[0086] Embodiment 3 Please refer to Figure 13 , which is a structural schematic diagram of the optical lens 300 provided in Embodiment 3 of the present application. Compared with Embodiment 1, the main difference is that the optical parameters such as the radius of curvature of each lens surface and the lens thickness are different.

[0087] The related parameters of each lens in the optical lens 300 in Embodiment 3 are shown in Table 3-1.

[0088] Table 3-1 The surface type parameters of the aspherical lens of the optical lens 300 in Embodiment 3 are shown in Table 3-2.

[0089] Table 3-2 In this embodiment, the F-Tan(Theta) distortion curve, the axial aberration curve, the transverse aberration curve, the MTF curve and the relative illumination curve of the optical lens 300 are shown in Figure 14 、 Figure 15 、 Figure 16 、 Figure 17 、 Figure 18 respectively.

[0090] From Figure 14 As can be seen from the F-Tan(Theta) distortion curve of the optical lens 300, the F-Tan(Theta) distortion is controlled within-15%~5%, which indicates that the distortion of the optical lens 300 can be corrected.

[0091] From Figure 15 As can be seen from the axial aberration curve of the optical lens 300, the offset of the axial aberration is controlled within-0.04mm~0.01mm, which indicates that the optical lens 300 can better correct the axial aberration.

[0092] From Figure 16 As can be seen from the transverse aberration curve of the optical lens 300, the transverse aberration of the longest wavelength and the shortest wavelength is controlled within ±2μm, which indicates that the optical lens 300 can better correct the transverse aberration.

[0093] FromFigure 17 As can be seen from the MTF curves, the MTF values of the optical lens according to the embodiments are all above 0.4 in the full field of view, and the MTF curves are uniformly and smoothly decreased from the center to the edge of the field of view in the range of 0-120 lp / mm, and the optical lens has good imaging quality and good detail resolution in the case of low frequency and high frequency.

[0094] From Figure 18 As can be seen from the relative illumination curves, the relative illumination values of the optical lens are still greater than 60% at the maximum half field of view, which indicates that the optical lens 300 has good relative illumination.

[0095] Referring to Tables 4-1 and 4-2, the optical characteristics corresponding to the above embodiments are shown, including the effective focal length f, the total track length TTL, the aperture value Fno, the chief ray angle of maximum image height CRA, the real image height IH corresponding to the maximum field of view, the maximum field of view FOV, the entrance pupil diameter EPD, the back focal length BFL, and the numerical values corresponding to each conditional expression in the embodiments.

[0096] Table 4-1 Table 4-2 In summary of the above embodiments, the optical lens provided by the present application has four lenses with optical power, and through specific surface shape matching and reasonable optical power distribution, the imaging quality of the optical lens can be improved, the aberration can be reduced, and the imaging quality of the optical lens can be improved, so that the lens has one or more advantages such as small size, small distortion, large image surface, etc.

[0097] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0098] The above embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as a limitation on the scope of the patent of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of protection of the present application. Therefore, the protection scope of the patent of the present application should be subject to 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.

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 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.

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 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: 1 < d1 / (IH / 2) / Tan(FOV / 2) < 1.15; 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: 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 < f1 / f < 6; The radius of curvature 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 radius of curvature 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.

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 radius of curvature R3 of the object side 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 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 radius of curvature R5 of the object side of the third lens and the effective focal length f of the optical lens satisfy: -0.75 < R5 / f < -0.2; The radius of curvature R6 of the image side of the third lens and the effective focal length f of the optical lens satisfy: -0.6 < R6 / f < -0.2; The radius of curvature R5 of the object side of the third lens and the radius of curvature R6 of the image side 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 radius of curvature R7 of the object side surface of the fourth lens and the effective focal length f of the optical lens satisfy: -0.4 < R7 / f < -0.2; the radius of curvature R8 of the image side surface of the fourth lens and the effective focal length f of the optical lens satisfy: -0.7 < R8 / f < -0.4; the clear aperture semi-diameter d7 of the object side surface of the fourth lens and the sagittal height Sag7 of the clear aperture of the object side surface of the fourth lens satisfy: -9 < d7 / Sag7 < -3; the clear aperture semi-diameter d8 of the image side surface of the fourth lens and the sagittal height Sag8 of the clear aperture of the image side surface of the fourth lens satisfy: -12300 < d8 / Sag8 < -9; 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: -0.42 < (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.

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