Optical lens

Abstract

The application discloses an optical lens, which comprises seven lenses and a liquid lens, and sequentially comprises, along an optical axis from an object side to an imaging surface, a first lens with negative optical power, the object side of which is a convex surface and the image side of which is a concave surface; a second lens with negative optical power, the object side of which is a convex surface and the image side of which is a concave surface; a third lens with positive optical power, the object side and the image side of which are both convex surfaces; a fourth lens with positive optical power, the object side and the image side of which are both convex surfaces; a liquid lens with optical power, which presents different focal lengths according to different applied voltages; a fifth lens with positive optical power, the object side and the image side of which are both convex surfaces; a sixth lens with negative optical power, the object side of which is a concave surface and the image side of which is a convex surface; and a seventh lens with positive optical power, the object side of which is a concave surface and the image side of which is a convex surface. The optical lens provided by the application has the advantages of small total length, high relative luminance, high resolving power and the like.

Description

TECHNICAL FIELD

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

[0002] In recent years, with the development of the automation industry, machine vision has achieved explosive growth, and the application field of industrial lenses is also more and more extensive. Due to the characteristics of high resolution, high definition and good stability, industrial lenses are widely used in size measurement, defect detection, image acquisition and other fields.

[0003] In order to realize good image acquisition and analysis function, such industrial lenses usually require high-definition resolution to obtain the image characteristics of the photographed object, and require high relative illumination to ensure the uniformity of the picture illumination. At the same time, in order to make the lens have good imaging effect at different working distances, the lens needs to collect images of different working distances through focusing. However, the focusing mode of the traditional lens is realized based on mechanical movement, such as installing a motor in the lens, driving the lens or the lens group in the lens to move transversely along the optical axis to change the optical spacing between the lenses or the lens and the camera chip, so as to compensate for the shift of the imaging focus of the lens caused by the change of the working distance. However, such mechanical focusing lens has the problems of slow focusing speed, the need for manual focusing and large volume, which is difficult to meet the use requirements of application scenarios with high real-time requirements. SUMMARY

[0004] Therefore, the purpose of the present application is to provide an optical lens with excellent imaging quality.

[0005] The present application achieves the above-mentioned purposes through the following technical solutions.

[0006] The present application provides an optical lens, which comprises seven lenses and one liquid lens, and sequentially comprises, along the optical axis from the object side to the imaging surface:

[0007] The first lens with negative optical power, whose object side surface is convex and whose image side surface is concave;

[0008] The second lens with negative optical power, whose object side surface is convex and whose image side surface is concave;

[0009] The third lens with positive optical power, whose object side surface and image side surface are both convex;

[0010] The fourth lens with positive optical power, whose object side surface and image side surface are both convex;

[0011] The liquid lens with optical power, which presents different focal lengths according to different applied voltages;

[0012] the fifth lens with positive refractive power, both of its object side surface and image side surface are convex;

[0013] the sixth lens with negative refractive power, its object side surface is concave, and its image side surface is convex;

[0014] the seventh lens with positive refractive power, its object side surface is concave, and its image side surface is convex;

[0015] wherein the effective focal length fe of the liquid lens satisfies: fe∈(-∞, -264.55]&[294.12, +∞) mm;

[0016] the effective focal length f of the optical lens and the total track length TTL of the optical lens satisfy: 6.8 < TTL / f < 8.5.

[0017] Further preferably, the total track 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: 3 < TTL / IH < 3.8; and 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: 2 < IH / f < 2.5.

[0018] Further preferably, 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: 0.95 < (IH / 2) / (f x Tan(FOV / 2)) < 1; and the maximum field of view angle FOV of the optical lens and the aperture value Fno of the optical lens satisfy: 32° < FOV / Fno < 40°.

[0019] Further preferably, the focal length f5 of the fifth lens and the effective focal length f of the optical lens satisfy: 0.9 < f5 / f < 1.3; and the object side surface curvature radius R9 of the fifth lens and the image side surface curvature radius R10 of the fifth lens satisfy: -11.4 < R9 / R10 < -5.3.

[0020] Further preferably, the focal length f6 of the sixth lens and the effective focal length f of the optical lens satisfy: -1.5 < f6 / f < -1.1; and the object side surface curvature radius R11 of the sixth lens and the image side surface curvature radius R12 of the sixth lens satisfy: -1 < (R11-R12) / (R11+R12) < -0.5.

[0021] Further preferably, the focal length f7 of the seventh lens and the effective focal length f of the optical lens satisfy: 2.9 < f7 / f < 4.6; and the object side surface curvature radius R13 of the seventh lens and the image side surface curvature radius R14 of the seventh lens satisfy: 14.7 < R13 / R14 < 22.4.

[0022] It is further preferred that the effective focal length f of the optical lens and the combined focal length f56 of the fifth lens and the sixth lens satisfy: 4.2 < f56 / f < 8.8.

[0023] It is further preferred that the effective focal length f of the optical lens and the object side surface curvature radius R11 of the sixth lens satisfy: -1.1 < R11 / f < -0.8; and the effective focal length f of the optical lens and the image side surface curvature radius R12 of the sixth lens satisfy: -8.9 < R12 / f < -5.2.

[0024] It is further preferred that the object side surface curvature radius R13 of the seventh lens and the image side surface curvature radius R14 of the seventh lens satisfy: 0.6 < (R13-R14) / (R13+R14) < 1.

[0025] It is further preferred that the object side surface half-field radius d11 of the sixth lens and the object side surface sagittal height Sag11 of the sixth lens satisfy: -0.45 < Sag11 / d11 < -0.25; and the image side surface half-field radius d12 of the sixth lens and the image side surface sagittal height Sag12 of the sixth lens satisfy: -0.1 < Sag12 / d12 < 0.

[0026] The optical lens provided by the present application adopts a combination of seven glass lenses and one liquid lens, and by reasonably distributing the positions and shapes of the lenses, the optical lens has better imaging ability at different object distances and also has good thermal stability. The optical lens has the advantages of small total length, high relative luminance, high resolution, etc. BRIEF DESCRIPTION OF DRAWINGS

[0027] 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:

[0028] Figure 1 A structure schematic diagram of the optical lens provided by the first embodiment of the present application.

[0029] Figure 2 A field curvature curve diagram of the optical lens provided by the first embodiment of the present application.

[0030] Figure 3 An F-Tan(Theta) distortion curve diagram of the optical lens provided by the first embodiment of the present application.

[0031] Figure 4 An axial aberration curve diagram of the optical lens provided by the first embodiment of the present application.

[0032] Figure 5 A transverse chromatic aberration curve diagram of the optical lens provided by the first embodiment of the present application.

[0033] Figure 6 MTF curve of the optical lens provided for the first embodiment of the present application.

[0034] Figure 7 Relative illuminance curve of the optical lens provided for the first embodiment of the present application.

[0035] Figure 8 Structure schematic diagram of the optical lens provided for the second embodiment of the present application.

[0036] Figure 9 Curvature of field curve of the optical lens provided for the second embodiment of the present application.

[0037] Figure 10 F-Tan(Theta) distortion curve of the optical lens provided for the second embodiment of the present application.

[0038] Figure 11 Axial aberration curve of the optical lens provided for the second embodiment of the present application.

[0039] Figure 12 Decentration curve of the optical lens provided for the second embodiment of the present application.

[0040] Figure 13 MTF curve of the optical lens provided for the second embodiment of the present application.

[0041] Figure 14 Relative illuminance curve of the optical lens provided for the second embodiment of the present application.

[0042] Figure 15 Structure schematic diagram of the optical lens provided for the third embodiment of the present application.

[0043] Figure 16 Curvature of field curve of the optical lens provided for the third embodiment of the present application.

[0044] Figure 17 F-Tan(Theta) distortion curve of the optical lens provided for the third embodiment of the present application.

[0045] Figure 18 Axial aberration curve of the optical lens provided for the third embodiment of the present application.

[0046] Figure 19 Decentration curve of the optical lens provided for the third embodiment of the present application.

[0047] Figure 20 MTF curve of the optical lens provided for the third embodiment of the present application.

[0048] Figure 21The relative illumination curve of the optical lens provided in the third embodiment of the present invention.

[0049] Figure 22 This is a schematic diagram of the structure of the liquid lens in the optical lens provided by the present invention. Detailed Implementation

[0050] To better understand the invention, various aspects of the invention 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 the invention and are not intended to limit the scope of the invention 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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 the invention, the word "may" is used to mean "one or more embodiments of the invention." And the term "exemplary" is intended to refer to an example or illustration.

[0055] 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 invention 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 defined herein.

[0056] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0057] The present invention proposes an optical lens, which comprises, along the optical axis from the object side to the imaging plane, the following elements in sequence: a first lens, a second lens, a third lens, a fourth lens, a liquid lens, a fifth lens, a sixth lens, and a seventh lens, wherein the optical centers of each lens are located on the same straight line.

[0058] In some embodiments, the first lens may have negative optical power, with a convex object-side surface and a concave image-side surface. The second lens may have negative optical power, with a convex object-side surface and a concave image-side surface. The third lens may have positive optical power, with both its object-side and image-side surfaces being convex. The fourth lens may have positive optical power, with both its object-side and image-side surfaces being convex. The liquid lens may have optical power, exhibiting different focal lengths depending on the applied voltage, and may contain an aperture stop. The fifth lens may have positive optical power, with both its object-side and image-side surfaces being convex. The sixth lens may have negative optical power, with a concave object-side surface and a convex image-side surface. The seventh lens may have positive optical power, with a concave object-side surface and a convex image-side surface.

[0059] In some embodiments, the optical lens may further include a filter and a protective glass, which are sequentially disposed between the seventh lens and the imaging plane along the optical axis. The filter is used to filter out interfering light, preventing it from reaching the imaging plane of the optical lens and affecting normal imaging. The protective glass protects the optical lens, preventing damage to the image sensor, and improves the lens's shock and scratch resistance, while having almost no impact on the image quality.

[0060] In some embodiments, the fifth lens and the sixth lens can be cemented together to form a cemented lens, which can effectively correct chromatic aberration of the optical lens, reduce the eccentricity sensitivity of the optical lens, balance the aberrations of the optical lens, and improve the imaging quality of the optical lens; it can also reduce the assembly sensitivity of the optical lens, thereby reducing the processing difficulty of the optical lens and improving the assembly yield of the optical lens.

[0061] In some embodiments, the liquid lens, from the object side to the imaging surface, sequentially includes a first surface, a second surface, a third surface, a fourth surface, a fifth surface, and a sixth surface. An aperture is provided at the fourth surface to narrow the range of light emitted from the forward optical system. The first, second, third, fifth, and sixth surfaces are all planar, while the fourth surface is curved and can have different radii of curvature depending on the applied driving voltage, thereby allowing the liquid lens to have different optical powers. More specifically, when the optical lens starts working, a certain starting voltage is applied to the liquid lens according to the current working object distance. At this time, the fourth surface in the liquid lens will have a certain radius of curvature, and the liquid lens will have a corresponding focal length. Together with the other seven lenses, it can make the optical lens in the best imaging state. When the working object distance of the optical lens changes within the preset working range, the driving voltage applied to the liquid lens will be automatically adjusted to change the radius of curvature of the fourth surface, and thus the focal length of the liquid lens will also change accordingly. That is, according to the different working object distances required by the optical lens, the driving voltage applied to the liquid lens can be automatically adjusted to make the liquid lens have a corresponding focal length, and thus the optical lens can have a suitable focal length (the overall focal length of the optical lens is adjusted within a small range), realizing the function of autofocus, so that the optical lens has high resolution at different working object distances.

[0062] In some embodiments, when the working object distance OBJ of the optical lens satisfies: OBJ≥150mm, the driving voltage U applied to the liquid lens satisfies: 35V≤U≤45V, and the effective focal length fe (mm) of the liquid lens satisfies: (-∞, -264.55]&[294.12, +∞). That is, when the optical lens works at a certain range of working object distances, the driving voltage applied to the liquid lens will be automatically adjusted within a certain range. At the same time, the automatic adjustment of the driving voltage will cause a corresponding change in the radius of curvature of the fourth surface on the liquid lens. The radius of curvature of the fourth surface satisfies Re (mm) satisfies: Re∈(-∞, -14.67]&[16.32, +∞). The corresponding change in the radius of curvature of the fourth surface will correspondingly change the optical power of the liquid lens, making it have a certain range of positive or negative optical power, thereby causing a small change in the focal length of the optical lens. In other words, by changing the driving voltage on the liquid lens at different working object distances, the radius of curvature of the liquid lens can be changed, thereby making the liquid lens present different focal lengths. This satisfies the requirement that the optical lens has relatively clear imaging quality at different working object distances, and also enables the optical lens to achieve fast autofocus at different working object distances.

[0063] In some embodiments, the effective focal length f of the optical lens and the overall optical length TTL of the optical lens satisfy: 6.8 < TTL / f < 8.5. By satisfying the above range, through reasonable control of the overall optical length and the effective focal length of the optical lens within a reasonable range, the requirement for miniaturization of the optical lens is met. More specifically, 7.51 < TTL / f < 7.81.

[0064] In some embodiments, 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: 3 < TTL / IH < 3.8. By satisfying the above range, it is beneficial to achieve the balance of small volume and large image plane of the optical lens, enabling the lens to have a smaller overall length while having higher resolution ability. More specifically, 3.3 < TTL / IH < 3.46.

[0065] 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: 2 < IH / f < 2.5. By satisfying the above range, reasonable control of the relationship between the image height and the focal length helps the optical lens to achieve high pixel characteristics. More specifically, 2.25 < IH / f < 2.28.

[0066] In some embodiments, the true image height IH corresponding to the maximum field angle of the optical lens, the effective focal length f of the optical lens, and the maximum field angle FOV of the optical lens satisfy: 0.95 < (IH / 2) / (f × Tan(FOV / 2)) < 1. By satisfying the above range, it is beneficial to control the optical lens to have a smaller distortion. More specifically, 0.95 < (IH / 2) / (f × Tan(FOV / 2)) < 0.97.

[0067] In some embodiments, the maximum field angle FOV of the optical lens and the aperture value Fno of the optical lens satisfy: 32° < FOV / Fno < 40°. By satisfying the above range, it is defined that the optical lens has a suitable field angle and aperture value, which can collect light at a large angle and obtain good imaging quality. More specifically, 35.35° < FOV / Fno < 36.74°.

[0068] In some embodiments, the focal length f5 of the fifth lens and the effective focal length f of the optical lens satisfy: 0.9 < f5 / f < 1.3; the curvature radius R9 of the object side of the fifth lens and the curvature radius R10 of the image side of the fifth lens satisfy: -11.4 < R9 / R10 < -5.3. By satisfying the above range, by making the fifth lens have a suitable positive focal length and surface shape, it is beneficial to smoothly transition the light transmitted by the front liquid lens, effectively reduce field curvature, and improve the imaging quality of the optical lens. More specifically, 1.04 < f5 / f < 1.15; -10.32 < R9 / R10 < -5.86.

[0069] In some embodiments, the focal length f6 of the sixth lens and the effective focal length f of the optical lens satisfy: -1.5 < f6 / f < -1.1; the radius of curvature R11 of the object side surface of the sixth lens and the radius of curvature R12 of the image side surface of the sixth lens satisfy: -1 < (R11 - R12) / (R11 + R12) < -0.5. Satisfying the above ranges and defining that the fifth lens has an appropriate negative optical power and surface shape can diverge the light rays emitted by the fifth lens, making the light rays in the peripheral field of view show an upward trend, which is beneficial for the image points on the imaging surface to be away from the optical axis, so as to facilitate achieving the effect of matching with a large chip, obtaining a larger picture, and can be glued to the fifth lens with a positive optical power, effectively eliminating aberrations and improving the resolution ability of the optical lens. More specifically, -1.35 < f6 / f < -1.3; -0.8 < (R11 - R12) / (R11 + R12) < -0.72.

[0070] In some embodiments, the focal length f7 of the seventh lens and the effective focal length f of the optical lens satisfy: 2.9 < f7 / f < 4.6; the radius of curvature R13 of the object side surface of the seventh lens and the radius of curvature R14 of the image side surface of the seventh lens satisfy: 14.7 < R13 / R14 < 22.4. Satisfying the above ranges and making the seventh lens have a suitable positive focal length and surface shape can reduce various aberrations of the optical lens and improve the imaging quality. More specifically, 3.18 < f7 / f < 4.17; 16.36 < R11 / R12 < 20.36.

[0071] In some embodiments, the effective focal length f of the optical lens and the combined focal length f56 of the fifth and sixth lenses satisfy: 4.2 < f56 / f < 8.8. Satisfying the above ranges can effectively correct the chromatic aberration of the optical lens, reduce the eccentricity sensitivity of the optical lens, balance the aberrations of the optical lens, and improve the imaging quality of the optical lens; it can also reduce the assembly sensitivity of the optical lens, thereby reducing the processing difficulty of the optical lens and improving the assembly yield of the optical lens. More specifically, 4.71 < f56 / f < 8.06.

[0072] In some embodiments, the effective focal length f of the optical lens and the radius of curvature R11 of the object side surface of the sixth lens satisfy: -1.1 < R11 / f < -0.8; the effective focal length f of the optical lens and the radius of curvature R12 of the image side surface of the sixth lens satisfy: -8.9 < R12 / f < -5.2. Satisfying the above ranges and reasonably defining the surface shape of the sixth lens is beneficial for increasing the imaging area. More specifically, -0.96 < R11 / f < -0.88; -8.08 < R12 / f < -5.71.

[0073] In some embodiments, the radius of curvature R13 of the object side surface of the seventh lens and the radius of curvature R14 of the image side surface of the seventh lens satisfy: 0.6 < (R13 - R14) / (R13 + R14) < 1. Meeting the above range can limit the surface shape of the seventh lens, has the characteristic of correcting field curvature, and is beneficial to the correction of the aberration of the entire optical lens. More specifically, 0.87 < (R13 - R14) / (R13 + R14) < 0.92.

[0074] In some embodiments, the clear aperture semi-diameter d11 of the object side surface of the sixth lens and the sagittal height Sag11 of the clear aperture of the object side surface of the sixth lens satisfy: -0.45 < Sag11 / d11 < -0.25; the clear aperture semi-diameter d12 of the image side surface of the sixth lens and the sagittal height Sag12 of the clear aperture of the image side surface of the sixth lens satisfy: -0.1 < Sag12 / d12 < 0. Meeting the above range helps to control the trend of the light rays in the marginal field of view and highlights the detailed information of the central field of view of the optical lens. More specifically, -0.39 < Sag11 / d11 < -0.31; -0.06 < Sag12 / d12 < -0.03.

[0075] In some embodiments, the effective focal length f of the optical lens and the back focal length BFL of the optical lens satisfy: 0.85 < BFL / f < 1.05. Meeting the above range defines that the optical lens has an appropriate back focal length, which is convenient for arranging the positions of each lens reasonably and reduces the processing and assembly difficulty at the same time. More specifically, 0.92 < BFL / f < 0.95.

[0076] In some embodiments, the maximum field of view FOV of the optical lens, the effective focal length f of the optical lens, and the true image height IH corresponding to the maximum field of view of the optical lens satisfy: 43.72° < f×FOV / IH < 47°. Meeting the above range can balance the requirements of large-range detection and high-quality imaging and improve the adaptability of the optical lens. More specifically, 43.71° < f×FOV / IH < 43.83°.

[0077] In some embodiments, the sum ∑CT of the central thicknesses of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens and the total optical length TTL of the optical lens satisfy: 0.35 < ∑CT / TTL < 0.5. Meeting the above range can achieve high pixel characteristics and improve the imaging quality of the optical lens by reasonably defining the central thicknesses of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens and the total optical length of the optical lens. More specifically, 0.41 < ∑CT / TTL < 0.44.

[0078] In some embodiments, the sum of the central thicknesses ∑CT of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens and the effective focal length f of the optical lens satisfy: 2.8 < ∑CT / f < 3.7. Meeting the above range can effectively correct the field curvature and distortion of the optical lens and improve the imaging quality of the optical lens. More specifically, 3.16 < ∑CT / f < 3.34.

[0079] In some embodiments, the effective focal length f of the optical lens and the focal length f1 of the first lens satisfy: -3.3 < f1 / f < -1.9. Meeting the above range makes the first lens have a negative optical power and can diverge the light passing through it, which is beneficial to achieving a small front aperture. More specifically, -3.01 < f1 / f < -2.15.

[0080] In some embodiments, the effective focal length f of the optical lens and the focal length f2 of the second lens satisfy: -3.3 < f2 / f < -2. Meeting the above range makes the second lens have a negative optical power and has the effect of diverging light. At the same field angle, it further diverges the light exiting from the image side of the first lens, can disperse the central light and the marginal light of each field, and enables the rear optical system to have a larger light receiving surface to receive the light exiting from the image side of the second lens, achieving a larger light input and being beneficial to increasing the relative illuminance. More specifically, -2.98 < f2 / f < -2.27.

[0081] In some embodiments, the focal length f3 of the third lens and the effective focal length f of the optical lens satisfy: 3.1 < f3 / f < 8.1. Meeting the above range limits the third lens to have an appropriate positive optical power, which is beneficial to the convergence of light, enables the light entering the system from the front to smoothly enter the rear optical system, makes the light trend smoother, optimizes the aberration, and improves the resolution. More specifically, 3.45 < f3 / f < 7.37.

[0082] In some embodiments, the focal length f4 of the fourth lens and the effective focal length f of the optical lens satisfy: 2.2 < f4 / f < 3.5. Meeting the above range is beneficial to the convergence of light, is beneficial to making the light enter the rear lens smoothly, and further can reduce the field curvature and correct the off-axis point aberration of the optical lens. More specifically, 2.42 < f4 / f < 3.15.

[0083] In some embodiments, the combined focal length f56 of the fifth lens and the sixth lens and the combined focal length f567 of the fifth lens, the sixth lens and the seventh lens satisfy: 1.7 < f56 / f567 < 3.5. Satisfying the above range and reasonably distributing the proportion of the focal length of the cemented lens group in the focal length of the rear lens group can effectively correct the chromatic aberration of the optical lens, reduce the eccentricity sensitivity of the optical lens, balance the aberration of the optical lens, and improve the imaging quality of the optical lens.

[0084] In some embodiments, the effective focal length f of the optical lens and the object-side curvature radius R5 of the third lens satisfy: 5 < R5 / f < 14.5; the effective focal length f of the optical lens and the image-side curvature radius R6 of the third lens satisfy: -14.5 < R6 / f < -5. Satisfying the above range, the object side and the image side of the third lens are symmetric surface types, which is beneficial to the correction of various aberrations of the optical lens and improves the imaging quality of the optical lens. More specifically, 5.51 < R5 / f < 13.15; -13.15 < R6 / f < -5.51.

[0085] In some embodiments, the effective focal length f of the optical lens and the object-side curvature radius R13 of the seventh lens satisfy: -61 < R13 / f < -37; the effective focal length f of the optical lens and the image-side curvature radius R14 of the seventh lens satisfy: -3.1 < R14 / f < -1.9. Satisfying the above range, the light trend is smoothly transitioned to the rear, the height of the light incident on the rear is reduced, the upward trend of the light is slowed down, and the light energy loss caused by the excessive main light angle of the large field of view light reaching the imaging surface is avoided, which is beneficial to improving the illuminance of the edge field of view and is beneficial to achieving a short optical total length. More specifically, -55.66 < R13 / f < -41.98; -2.78 < R14 / f < -2.11.

[0086] In some embodiments, the image-side curvature radius R6 of the third lens and the object-side curvature radius R7 of the fourth lens satisfy: -4.7 < R6 / R7 < -1.7. Satisfying the above range can reduce the light deflection angle and make the light trend smoother; at the same time, it can correct coma and field curvature, improve the flatness of imaging, and improve the imaging quality of the optical lens. More specifically, -4.27 < R6 / R7 < -1.86.

[0087] In some embodiments, the distance CT67 between the sixth lens and the seventh lens on the optical axis and the central thickness CT7 of the seventh lens satisfy: 2.9 < CT67 / CT7 < 6. Satisfying the above range, by reasonably limiting the air gap between the sixth lens and the seventh lens on the optical axis and the central thickness of the seventh lens, the reasonable arrangement of each lens in the optical lens can be maintained, and the structural stability of the optical lens can be improved. More specifically, 3.21 < CT67 / CT7 < 5.48.

[0088] In some embodiments, the optical lens satisfies the following conditional expressions: 3 mm < f < 3.6 mm; 90° < FOV < 110°; 1.1 mm < EPD < 1.3 mm; 22.4 mm < TTL < 28.5 mm; 2.5 < Fno < 3; 7 mm < IH < 8 mm; 14° < CRA < 16°; 2.8 mm < BFL < 3.4 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 f-number 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 chief 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 ranges, the optical lens has at least one or more advantages such as a small total length, a relatively large field of view angle, a large image plane, and high resolution. Preferably, the optical lens satisfies the following conditional expressions: 3.29 mm < f < 3.33 mm; 98° < FOV < 100°; 1.17 mm < EPD < 1.21 mm; 24.79 mm < TTL < 25.91 mm; 2.7 < Fno < 2.81; 7.4 mm < IH < 7.6 mm; 14.69° < CRA < 14.81°; 3 mm < BFL < 3.2 mm.

[0089] In some embodiments, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens can be made of all-glass lenses or a combination of glass and plastic, and both can achieve good imaging effects. In this application, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are all made of glass lenses.

[0090] In some embodiments, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens can be spherical lenses or aspherical lenses. Compared with the aspherical structure, the spherical structure can reduce the processing difficulty and production cost. More specifically, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens of the present invention are all spherical lenses.

[0091] In various embodiments of the present invention, when the lens is an aspherical lens, the shapes of the aspherical surfaces of the optical lens satisfy the following equation:

[0092]

[0093] where z is the distance between the surface and the vertex of the surface in the optical axis direction, h is the distance from the optical axis to the surface, c is the curvature of the vertex of the surface, K is the conic coefficient, and B, C, D, E, and F are the fourth-order, sixth-order, eighth-order, tenth-order, and twelfth-order surface coefficients respectively.

[0094] 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.

[0095] First Embodiment

[0096] Please see Figure 1 The diagram shows a schematic of the structure of an optical lens 100 provided in the first embodiment of the present invention. It consists of seven lenses and one liquid lens. The optical lens 100 includes, along the optical axis from the object side to the imaging surface S24, the following components in sequence: a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a liquid lens E1, a fifth lens L5, a sixth lens L6, a seventh lens L7, a filter G1, and a protective glass G2. The optical centers of each lens are located on the same straight line.

[0097] Among them, the first lens L1 has negative optical power, its object side S1 is convex, and its image side S2 is concave.

[0098] The second lens L2 has negative optical power, its object side S3 is convex, and its image side S4 is concave.

[0099] The third lens L3 has positive optical power, and its object side S5 and image side S6 are both convex surfaces.

[0100] The fourth lens L4 has positive optical power, and both its object-side surface S7 and image-side surface S8 are convex.

[0101] The fifth lens L5 has positive optical power, and both its object-side surface S15 and image-side surface S16 are convex.

[0102] The sixth lens L6 has negative optical power, its object side S16 is concave, and its image side S17 is convex.

[0103] The fifth lens L5 and the sixth lens L6 form a cemented lens group with positive optical power, that is, the cemented surface of the image side and the object side of the fifth lens L5 is S16.

[0104] The seventh lens L7 has positive optical power, its object side surface S18 is concave, and its image side surface S19 is convex.

[0105] Both the object-side surface S20 and the image-side surface S21 of the filter G1 are planar.

[0106] The object side S22 and the image side S23 of the protective glass G2 are both flat.

[0107] The first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7 are glass spherical lenses.

[0108] Please also see Figure 22 The liquid lens E1, from the object side to the imaging surface, includes a first surface S9, a second surface S10, a third surface S11, a fourth surface S12, a fifth surface S13, and a sixth lens S14. The aperture stop ST is located at the fourth surface S12. The first surface S9, the second surface S10, the fourth surface S12, the fifth surface S13, and the sixth lens S14 are all planar. The third surface S11 is curved and can have different radii of curvature depending on the applied driving voltage, thus allowing the liquid lens E1 to have different optical powers. For example, when the working object distance OBJ of the optical lens satisfies: OBJ≥150mm, the driving voltage U applied to the liquid lens satisfies: 38.05V≤U≤39.95V, and the effective focal length fe (mm) of the liquid lens satisfies: fe∈[-2738.54, -573.54].

[0109] The relevant parameters of each lens element in the optical lens 100 provided in this embodiment are shown in Table 1-1.

[0110] Table 1-1

[0111]

[0112]

[0113] In this embodiment, when the working object distance OBJ of the optical lens satisfies: OBJ≥150mm, the driving voltage U applied to the liquid lens satisfies: 38.05V≤U≤39.95V, the radius of curvature Re of the third surface satisfies: Re∈[-155.69, -32.61]mm, the effective focal length fe of the liquid lens satisfies: fe∈[-2738.54, -573.54]mm, and the effective focal length f of the optical lens satisfies: 3.29mm≤f≤3.31mm. More specifically, when the optical lens is at the optimal working object distance of 300mm, the voltage applied to the liquid lens is 39V (this voltage is the starting voltage), the radius of curvature of the third surface in the liquid lens is -53.68mm, the effective focal length of the liquid lens is -944.17mm, and the effective focal length of the optical lens is 3.3mm. The relevant parameters of the optical lens 100 provided in this embodiment at the optimal working distance, minimum working distance, and maximum working distance are shown in Table 1-2.

[0114] Table 1-2

[0115] Best working object distance Minimum working object distance Maximum working object distance OBJ (mm) 300 150 Infinity f (mm) 3.30 3.29 3.31 U (V) 39.00 39.95 38.05 fe (mm) -944.17 -2738.54 -573.54 Re (mm) -53.68 -155.69 -32.61

[0116] Figure 2 The field curvature curve of the optical lens 100 in this embodiment is shown, which represents the degree of curvature of light of different wavelengths in the meridional and sagittal image planes. The horizontal axis represents the offset (unit: mm), and the vertical axis represents the half field of view (unit: °). As can be seen from the figure, the field curvature of the meridional and sagittal image planes is controlled within ±0.05 mm, indicating that the optical lens can effectively correct the field curvature.

[0117] Figure 3 The F-Tan (Theta) distortion curve of the optical lens 100 in this embodiment is shown, which represents the distortion at different field-of-view angles on the imaging plane. The horizontal axis represents the distortion value (unit: %), and the vertical axis represents the half field of view (unit: °). As can be seen from the figure, the distortion value is controlled within ±4%, indicating that the optical lens can correct distortion well.

[0118] Figure 4 The diagram shows the axial aberration curve of the optical lens 100 in this embodiment, which represents the aberration of each wavelength on the optical axis at the imaging plane. The horizontal axis represents the axial aberration value (unit: mm), and the vertical axis represents the normalized pupil radius. As can be seen from the figure, the axial aberration offset is controlled within ±0.02 mm, indicating that the optical lens can effectively correct axial aberration.

[0119] Figure 5 The diagram shows the transverse chromatic aberration curve of the optical lens 100 in this embodiment. It represents the chromatic aberration of each wavelength relative to the center wavelength (0.55 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 ±5 μm, indicating that the optical lens can effectively correct chromatic aberration.

[0120] Figure 6 The modulation transfer function (MTF) curve of the optical lens 100 in this embodiment is shown, which represents the lens imaging modulation at different spatial frequencies in 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 this embodiment is above 0.45 throughout the entire half-image height, exhibiting good imaging quality and good detail resolution in both low-frequency and high-frequency conditions.

[0121] Figure 7The diagram shows the relative illumination curve of the optical lens 100 in this embodiment, which represents the relative illumination value at different image heights on the imaging plane. The horizontal axis represents the half field of view (unit: °), and the vertical axis represents the relative illumination value (unit: %). As can be seen from the figure, 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 has good relative illumination.

[0122] Second Embodiment

[0123] Please see Figure 8 The figure shows a schematic diagram of the structure of the optical lens 200 provided in the second embodiment of the present invention. The structure of the optical lens 200 is roughly the same as that of the optical lens 100 in the first embodiment. The main difference is that the parameters of the liquid lens are different, and the curvature radius, thickness and spacing between each lens are different.

[0124] The relevant parameters of each lens element in the optical lens 200 provided in this embodiment are shown in Table 2-1.

[0125] Table 2-1

[0126]

[0127]

[0128] In this embodiment, when the working object distance OBJ of the optical lens satisfies: OBJ≥150mm, the driving voltage U applied to the liquid lens satisfies: 39.47V≤U≤41.5V, the radius of curvature Re of the third surface satisfies: Re∈(-∞, -79.32]&[72.18, +∞)mm, and the effective focal length fe of the liquid lens satisfies: fe∈(-∞, -1395.28]&[1269.66, +∞)mm. At this time, the effective focal length f of the optical lens satisfies: 3.3mm≤f≤3.32mm. More specifically, when the optical lens is at the optimal working object distance of 300mm, the voltage applied to the liquid lens is 40.57V (this voltage is the starting voltage), the radius of curvature of the third surface in the liquid lens is 595.99mm, the effective focal length of the liquid lens is 10483.45mm, and the effective focal length of the optical lens is 3.31mm. The relevant parameters of the optical lens 200 provided in this embodiment at the optimal working distance, minimum working distance, and maximum working distance are shown in Table 2-2.

[0129] Table 2-2

[0130] Best working object distance Minimum working object distance Maximum working object distance OBJ (mm) 300 150 Infinity f (mm) 3.31 3.30 3.32 U (V) 40.57 41.50 39.47 fe (mm) 10483.45 1269.66 -1395.28 Re (mm) 595.99 72.18 -79.32

[0131] Figures 9 to 14The field curvature curve, F-Tan (Theta) distortion curve, axial aberration curve, transverse chromatic aberration curve, MTF curve, and relative illumination curve of the optical lens 200 in this embodiment are shown.

[0132] from Figure 9 As can be seen, the field curvature of the meridional image plane and the sagittal image plane is controlled within ±0.04mm, indicating that the optical lens can correct the field curvature well.

[0133] from Figure 10 As can be seen, the distortion value is controlled within ±4%, indicating that the optical lens can correct distortion well.

[0134] from Figure 11 As can be seen, the axial aberration offset is controlled within ±0.02mm, indicating that the optical lens can correct axial aberration well.

[0135] from Figure 12 As can be seen, the transverse chromatic aberration of the longest and shortest wavelengths is controlled within ±5μm, indicating that the optical lens can correct chromatic aberration well.

[0136] from Figure 13 As can be seen from the data, the MTF value of this embodiment is above 0.5 throughout the entire half-image height, and it has good imaging quality and good detail resolution in both low and high frequency conditions.

[0137] from Figure 14 As can be seen, the relative illumination value of the optical lens is still greater than 55% at the maximum half field of view, indicating that the optical lens has good relative illumination.

[0138] Third Embodiment

[0139] Please see Figure 15 The figure shows a schematic diagram of the structure of the optical lens 300 provided in the third embodiment of the present invention. The structure of the optical lens 300 is roughly the same as that of the optical lens 100 in the first embodiment. The main difference is that the parameters of the liquid lens are different, and the curvature radius, thickness, spacing between lenses, and materials of each lens are different.

[0140] The relevant parameters of each lens element in the optical lens 300 provided in this embodiment are shown in Table 3-1.

[0141] Table 3-1

[0142]

[0143]

[0144] In this embodiment, when the working object distance OBJ of the optical lens satisfies: OBJ≥150mm, the driving voltage U applied to the liquid lens satisfies: 38.97V≤U≤41.11V, the radius of curvature Re of the third surface satisfies: Re∈(-∞, -52.59]&[114.02, +∞)mm, and the effective focal length fe of the liquid lens satisfies: fe∈(-∞, -925.14]&[2005.55, +∞)mm. At this time, the effective focal length f of the optical lens satisfies: 3.31mm≤f≤3.33mm. More specifically, when the optical lens is at the optimal working object distance of 300mm, the voltage applied to the liquid lens is 40V (this voltage is the starting voltage), the radius of curvature of the third surface in the liquid lens is -173.13mm, the effective focal length of the liquid lens is -3045.36mm, and the effective focal length of the optical lens is 3.32mm. The relevant parameters of the optical lens 300 provided in this embodiment at the optimal working distance, minimum working distance, and maximum working distance are shown in Table 3-2.

[0145] Table 3-2

[0146] Best working object distance Minimum working object distance Maximum working object distance OBJ (mm) 300 150 Infinity f (mm) 3.32 3.31 3.33 U (V) 40.00 41.11 38.97 fe (mm) -3045.36 2005.55 -925.14 Re (mm) -173.13 114.02 -52.59

[0147] Figures 16 to 21 The field curvature curve, F-Tan (Theta) distortion curve, axial aberration curve, transverse chromatic aberration curve, MTF curve, and relative illumination curve of the optical lens 300 in this embodiment are shown.

[0148] from Figure 16 As can be seen, the field curvature of the meridional image plane and the sagittal image plane is controlled within ±0.04mm, indicating that the optical lens can correct the field curvature well.

[0149] from Figure 17 As can be seen, the distortion value is controlled within ±4%, indicating that the optical lens can correct distortion well.

[0150] from Figure 18 As can be seen, the axial aberration offset is controlled within ±0.02mm, indicating that the optical lens can correct axial aberration well.

[0151] from Figure 19 As can be seen, the transverse chromatic aberration of the longest and shortest wavelengths is controlled within ±4μm, indicating that the optical lens can correct chromatic aberration well.

[0152] from Figure 20 As can be seen from the data, the MTF value of this embodiment is above 0.6 throughout the entire half-image height, and it has good imaging quality and good detail resolution in both low and high frequency conditions.

[0153] fromFigure 21 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 has good relative illumination.

[0154] Please refer to Table 4, which shows the optical characteristics of the optical lenses provided in the above three embodiments at the optimal working object distance, including the working object distance OBJ, effective focal length f, total optical length TTL, maximum field of view FOV, true image height IH corresponding to the maximum field of view, aperture value Fno, driving voltage U of the liquid lens, and effective focal length fe of the liquid lens. It also includes the relevant values ​​corresponding to each condition in the above conditional expressions.

[0155] Table 4

[0156]

[0157]

[0158] In summary, the optical lens provided by this invention has at least the following advantages:

[0159] The optical lens provided by this invention uses a combination of seven lenses and one liquid lens. By rationally allocating the liquid lens and the focal length relationship of each lens, the optical lens has good imaging capability at different object distances while also having good thermal stability. At the same time, by rationally configuring the thickness of each lens, the spacing between each lens, and the surface shape matching of each lens, the optical lens has advantages such as small overall length, high relative illumination, and high resolution.

[0160] 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.

[0161] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. An optical lens comprising seven lenses and one liquid lens, characterized in that, It sequentially includes from the object side to the imaging surface along the optical axis: A first lens with a negative optical power, whose object side is convex and whose image side is concave; A second lens with a negative optical power, whose object side is convex and whose image side is concave; A third lens with a positive optical power, whose object side and image side are both convex; A fourth lens with a positive optical power, whose object side and image side are both convex; A liquid lens with an optical power, and the liquid lens presents different focal lengths according to different applied voltages; A fifth lens with a positive optical power, whose object side and image side are both convex; A sixth lens with a negative optical power, whose object side is concave and whose image side is convex; A seventh lens with a positive optical power, whose object side is concave and whose image side is convex; Wherein, the effective focal length fe of the liquid lens satisfies: fe ∈ (-∞, -264.55] & [294.12, +∞) mm; The effective focal length f of the optical lens and the optical total length TTL of the optical lens satisfy: 6.8 < TTL / f < 8.5; The optical total length TTL of the optical lens and the true image height IH corresponding to the maximum field angle of the optical lens satisfy: 3 < TTL / IH < 3.8; 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: 2 < IH / f < 2.5; 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: 0.95 < (IH / 2) / (f × Tan(FOV / 2)) < 1; The maximum field angle FOV of the optical lens and the aperture value Fno of the optical lens satisfy: 32° < FOV / Fno < 40°.

2. The optical lens according to claim 1, characterized in that, The effective focal length f of the optical lens and the optical total length TTL of the optical lens satisfy: 7.51 < TTL / f < 7.81; The optical total length TTL of the optical lens and the true image height IH corresponding to the maximum field angle of the optical lens satisfy: 3.3 < TTL / IH < 3.46; 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: 2.25 < IH / f < 2.

28.

3. The optical lens according to claim 1, characterized in that, The true image height IH corresponding to the maximum field angle of the optical lens, the effective focal length f of the optical lens and the maximum field angle FOV of the optical lens satisfy: 0.95 < (IH / 2) / (f × Tan(FOV / 2)) < 0.97; The maximum field angle FOV of the optical lens and the aperture value Fno of the optical lens satisfy: 35.35° < FOV / Fno < 36.74°.

4. The optical lens according to claim 1, characterized in that, The focal length f5 of the fifth lens and the effective focal length f of the optical lens satisfy: 0.9 < f5 / f < 1.3; The object side curvature radius R9 of the fifth lens and the image side curvature radius R10 of the fifth lens satisfy: -11.4 < R9 / R10 < -5.

3.

5. The optical lens according to claim 1, characterized in that, The focal length f6 of the sixth lens and the effective focal length f of the optical lens satisfy: -1.5 < f6 / f < -1.1; the object-side curvature radius R11 of the sixth lens and the image-side curvature radius R12 of the sixth lens satisfy: -1 < (R11 - R12) / (R11 + R12) < -0.

5.

6. The optical lens according to claim 1, characterized in that, The focal length f7 of the seventh lens and the effective focal length f of the optical lens satisfy: 2.9 < f7 / f < 4.6; the object-side curvature radius R13 of the seventh lens and the image-side curvature radius R14 of the seventh lens satisfy: 14.7 < R13 / R14 < 22.

4.

7. The optical lens according to claim 1, characterized in that, The effective focal length f of the optical lens and the combined focal length f56 of the fifth lens and the sixth lens satisfy: 4.2 < f56 / f < 8.

8.

8. The optical lens according to claim 1, characterized in that, The effective focal length f of the optical lens and the object-side curvature radius R11 of the sixth lens satisfy: -1.1 < R11 / f < -0.8; the effective focal length f of the optical lens and the image-side curvature radius R12 of the sixth lens satisfy: -8.9 < R12 / f < -5.

2.

9. The optical lens according to claim 1, characterized in that, The object-side curvature radius R13 of the seventh lens and the image-side curvature radius R14 of the seventh lens satisfy: 0.6 < (R13 - R14) / (R13 + R14) < 1.

10. The optical lens according to claim 1, characterized in that, The object-side clear aperture semi-diameter d11 of the sixth lens and the object-side clear aperture semi-diameter sagitta Sag11 of the sixth lens satisfy: -0.45 < Sag11 / d11 < -0.25; the image-side clear aperture semi-diameter d12 of the sixth lens and the image-side clear aperture semi-diameter sagitta Sag12 of the sixth lens satisfy: -0.1 < Sag12 / d12 < 0.

Images