Optical lens

Abstract

The application discloses an optical lens, comprising a first lens group, a liquid lens and a second lens group arranged in sequence along an optical axis from an object side to an image side, the first lens group has positive focal power, the second lens group has positive focal power, the first lens group comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens, the second lens group comprises a sixth lens, a seventh lens, an eighth lens and a ninth lens, the first lens has negative focal power, the second lens has negative focal power, the third lens has positive focal power, the fourth lens has positive focal power, the fifth lens has negative focal power, the sixth lens has positive focal power, the seventh lens has negative focal power, the eighth lens has positive focal power, and the ninth lens has negative focal power. The optical lens provided by the embodiment of the application expands the original fixed working distance focusing optical lens into an optical lens with an adjustable working distance within 1935mm, and has the advantages of small size, light weight and low cost.

Description

Optical lens Technical Field

[0001] This invention relates to the field of optical device technology, and more particularly to an optical lens. Background Technology

[0002] With the technological development in the field of intelligent automation, machine vision is being used more and more widely in automated inspection and barcode scanning, especially in areas such as high-precision dimensional measurement, rapid detection of minute defects, and accurate identification of tiny devices, where optical lenses are used.

[0003] Among them, tilt-shift lenses have received widespread attention in applications such as barcode scanning due to their excellent optical performance, such as low distortion, high resolution, and small size, as well as their ability to provide relatively large depth of field and special angle adjustment capabilities.

[0004] However, with the increasing demands for detection speed, although ordinary tilt-shift optical lenses provide a greater depth of field compared to other traditional lenses, they still cannot meet the needs of some application scenarios that require ultra-large depth of field. Furthermore, current tilt-shift optical lenses have a relatively large number of lenses and a relatively complex structure, resulting in heavy optical lenses, large space requirements, and high costs. Summary of the Invention

[0005] This invention provides an optical lens to solve problems such as insufficient depth of field, large size, and high cost.

[0006] This invention provides an optical lens, comprising a first lens group, a liquid lens, and a second lens group arranged sequentially along the optical axis from the object side to the image side;

[0007] The first lens group has positive optical power, and the second lens group has positive optical power;

[0008] The first lens group includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens arranged sequentially from the object side to the image side;

[0009] The second lens group includes a sixth lens, a seventh lens, an eighth lens, and a ninth lens arranged sequentially from the object side to the image side;

[0010] The first lens has negative optical power, the second lens has negative optical power, the third lens has positive optical power, the fourth lens has positive optical power, the fifth lens has negative optical power, the sixth lens has positive optical power, the seventh lens has negative optical power, the eighth lens has positive optical power, and the ninth lens has negative optical power.

[0011] Optionally, the object-side surface of the first lens is convex, and the image-side surface is concave.

[0012] The object-side surface of the second lens is concave, and the image-side surface is also concave.

[0013] The object-side surface of the third lens is convex, and the image-side surface is also convex.

[0014] The object-side surface of the fourth lens is convex, and the image-side surface is also convex.

[0015] The object-side surface of the fifth lens is convex, and the image-side surface is concave.

[0016] The object-side surface of the sixth lens is concave, and the image-side surface is convex.

[0017] The object-side surface of the seventh lens is concave, and the image-side surface is convex.

[0018] The object-side surface of the eighth lens is convex, and the image-side surface is also convex.

[0019] The object-side surface of the ninth lens is concave, and the image-side surface is convex.

[0020] Optionally, the optical lens may also include an aperture stop;

[0021] The aperture is located in the optical path between the fifth lens and the liquid lens;

[0022] or,

[0023] The aperture is located in the optical path between the liquid lens and the sixth lens.

[0024] Optionally, the optical lens further includes a flat glass plate located on the image-side side of the ninth lens;

[0025] The distance between the first lens and the second lens on the optical axis is d1; the distance between the second lens and the third lens on the optical axis is d2; the distance between the third lens and the fourth lens on the optical axis is d3; and the distance between the fourth lens and the fifth lens on the optical axis is d4.

[0026] 1.11mm≤d1≤1.31mm; 0.52mm≤d2≤0.72mm;

[0027] 0.11mm≤d3≤0.31mm; 0.04mm≤d4≤0.24mm;

[0028] The aperture stop is located between the fifth lens and the liquid lens. The distance between the fifth lens and the aperture stop on the optical axis is d5. The distance between the aperture stop and the liquid lens on the optical axis is d6. The distance between the liquid lens and the sixth lens on the optical axis is d7. The distance between the seventh lens and the eighth lens on the optical axis is d8. The distance between the ninth lens and the flat glass on the optical axis is d9.

[0029] 0.55mm≤d5≤0.75mm; 0.05mm≤d6≤0.25mm;

[0030] 0.55mm≤d7≤0.75mm; 0.12mm≤d8≤0.32mm;

[0031] 6.02mm≤d9≤6.82mm.

[0032] Optionally, the diopter of the liquid lens is D, where -9 ≤ D ≤ 6.

[0033] Optionally, the fourth lens has a focal length of f4, and the fifth lens has a focal length of f5.

[0034] -1≤f4 / f5<0.

[0035] Optionally, the distance between the object-side surface of the fourth lens and the image-side surface of the fourth lens on the optical axis is d10, and the distance between the image-side surface of the fifth lens and the object-side surface of the liquid lens on the optical axis is d11, where 0 < d10 / d11 ≤ 5.

[0036] Optionally, the principal ray angle of the optical lens is greater than or equal to 10° and less than or equal to 15°.

[0037] Optionally, the focal length of the second lens is f2, and the focal length of the optical lens is f, -3≤f2 / f<0.

[0038] Optionally, the central radius of curvature of the object side of the second lens is R1, and the central radius of curvature of the image side of the second lens is R2, where 0≤(R1+R2) / (R1-R2)≤1.22.

[0039] Optionally, the sixth lens and the seventh lens form a first cemented lens group;

[0040] And / or,

[0041] The eighth lens and the ninth lens together form the second cemented lens group.

[0042] Optionally, the focal length of the third lens is f3, and the focal length of the fourth lens is f4, where 0 < f3 / f4 ≤ 1.

[0043] Optionally, the thickness of the first lens on the optical axis is d12, and the total optical length of the optical lens is TTL, where 0 < d12 / TTL ≤ 0.08.

[0044] Optionally, the distance between the third lens and the fourth lens on the optical axis is d3, and the distance between the object side surface of the fourth lens and the image side surface of the fourth lens on the optical axis is d10, where 0≤d3 / d10≤5.

[0045] Optionally, the focal length of the fifth lens is f5, the focal length of the sixth lens is f6, and -20 ≤ f5 / f6 < 1.

[0046] The optical lens provided in this embodiment of the invention is configured with a first lens group, a liquid lens, and a second lens group working together. The variable power of the liquid lens compensates for variations in working distance. By setting the number of lenses (10 optical lenses) in the first and second lens groups located on either side of the liquid lens and the power distribution of each lens, aberrations introduced by the liquid lens when the curvature changes over large depths of field are eliminated. This expands the original fixed-working-distance focusing optical lens into an optical lens with an adjustable working distance within a 1935mm range, giving the optical lens a wider range of applications. With fewer lenses, the total optical length can be reduced to approximately 20mm. Its small size, light weight, and low cost help reduce the overall hardware cost of visual inspection solutions, thereby significantly improving work efficiency.

[0047] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0049] Figure 1 is a schematic diagram of the structure of an optical lens provided in an embodiment of the present invention;

[0050] Figure 2 is a schematic diagram of the optical path of another optical lens provided in an embodiment of the present invention;

[0051] Figure 3 is a field curvature diagram of an optical lens provided in an embodiment of the present invention at a working distance of 65mm;

[0052] Figure 4 is a field curvature diagram of an optical lens provided in an embodiment of the present invention at a working distance of 2000mm;

[0053] Figure 5 shows the distortion diagram of an optical lens provided in an embodiment of the present invention at a working distance of 65mm;

[0054] Figure 6 is a distortion diagram of an optical lens provided in an embodiment of the present invention at a working distance of 2000mm;

[0055] Figure 7 is an optical transfer function diagram of an optical lens provided in an embodiment of the present invention at a working distance of 65mm;

[0056] Figure 8 is an optical transfer function diagram of an optical lens provided in an embodiment of the present invention at a working distance of 2000mm;

[0057] Figure 9 is an axial chromatic aberration diagram of an optical lens provided in an embodiment of the present invention at a working distance of 65mm;

[0058] Figure 10 is an axial chromatic aberration diagram of an optical lens provided in an embodiment of the present invention at a working distance of 2000mm. Detailed Implementation

[0059] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0060] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0061] Figure 1 is a structural schematic diagram of an optical lens provided in an embodiment of the present invention, and Figure 2 is an optical path schematic diagram of another optical lens provided in an embodiment of the present invention. As shown in Figures 1 and 2, the optical lens provided in this embodiment of the present invention includes a first lens group 100, a liquid lens LQ, and a second lens group 200 arranged sequentially from the object side to the image side along the optical axis. The first lens group 100 has positive optical power, and the second lens group 200 also has positive optical power. The first lens group 100 includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, and a fifth lens 5 arranged sequentially from the object side to the image side. The second lens group 200 includes a sixth lens 6, a seventh lens 7, an eighth lens 8, and a ninth lens 9 arranged sequentially from the object side to the image side. The first lens 1 has negative optical power, the second lens 2 has negative optical power, the third lens 3 has positive optical power, the fourth lens 4 has positive optical power, the fifth lens 5 has negative optical power, the sixth lens 6 has positive optical power, the seventh lens 7 has negative optical power, the eighth lens 8 has positive optical power, and the ninth lens 9 has negative optical power.

[0062] The optical axis refers to the principal optical axis of the optical lens. The object side is also called the object side, and the image side is also called the image side.

[0063] Optical power is used to characterize the refractive power of an optical system for an incident parallel beam of light. When the optical power is positive, the refraction is converging, and when the optical power is negative, the refraction is diverging. Furthermore, the larger the absolute value of the optical power, the stronger its ability to bend light, and the smaller the absolute value of the optical power, the weaker its ability to bend light.

[0064] In this embodiment, as shown in Figures 1 and 2, the first lens group 100, the liquid lens LQ, and the second lens group 200 are arranged sequentially along the propagation direction of the incident light, and the centers of each lens in the first lens group 100, the liquid lens LQ, and the second lens group 200 are collinear.

[0065] The first lens group 100 has a positive optical power and is used to guide the main optical path of the object-side field of view, converging the light emitted from each angle of the object-side luminous point.

[0066] Furthermore, the first lens group 100 includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, and a fifth lens 5, and the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, and the fifth lens 5 are arranged sequentially from the object side to the image side along the optical axis.

[0067] The first lens 1 has negative optical power and is mainly used to collect light emitted by the object.

[0068] The second lens 2 has negative optical power and is used to deflect the light rays passing through the first lens 1, thus undertaking a certain degree of optical power adjustment.

[0069] The third lens 3 has positive optical power and is used to reduce the incident angle of light, so that the light can enter the subsequent lenses more smoothly.

[0070] The fourth lens 4 has positive optical power and is used to balance aberrations and ensure the quality of light after passing through the previous lenses.

[0071] The fifth lens 5 has negative optical power and mainly directs light to the object side of the liquid lens LQ (e.g., the location of the aperture stop) to prepare for subsequent light adjustment.

[0072] Referring again to Figures 1 and 2, the optical power of the second lens group 200 is positive. It is used to provide the optical path corresponding to the image-side field of view and to converge the optical paths at various angles of the image side to ensure the image size and the magnification of the optical lens.

[0073] The second lens group 200 includes a sixth lens 6, a seventh lens 7, an eighth lens 8, and a ninth lens 9, which are arranged sequentially from the object side to the image side along the optical axis.

[0074] Furthermore, the sixth lens 6 has a positive optical power, the seventh lens 7 has a negative optical power, the eighth lens 8 has a positive optical power, and the ninth lens 9 has a negative optical power. Through the combination of different lenses and their specific optical power design, the remaining aberrations can be corrected more precisely, ensuring that the light can be accurately focused onto the image plane, and the size of the final image and the optical magnification of the lens can be precisely controlled to ensure good imaging results.

[0075] It should be noted that the ninth lens 9 has negative optical power, which can be used to reduce the field curvature of the optical lens, thereby reducing aberrations and improving image quality.

[0076] Furthermore, as shown in Figures 1 and 2, a liquid lens LQ is disposed between the first lens group 100 and the second lens group 200. The liquid lens LQ is an optical element made of one or more liquids without mechanical connection, which has rapid and stable deformation characteristics under the control of a driving signal.

[0077] The focal length of the liquid lens LQ can be changed by altering the curvature of the liquid within it through external driving signals (such as driving voltage or driving current).

[0078] Therefore, the focusing position of the optical lens can be adjusted in real time by adjusting the driving signal (such as driving voltage or driving current) applied to the liquid lens LQ, i.e., adjusting the focal length of the optical lens. Different driving signals result in different curvature shapes of the liquid lens LQ, thus corresponding to different working distances and achieving fast focusing at various working distances.

[0079] In this embodiment, dynamic compensation for the working distance (i.e., object distance) is achieved by changing the curvature of the liquid lens LQ, thereby acting as a zoom function for the entire optical lens. This allows the optical lens to maintain good focusing performance over a wide working distance range, achieving clear imaging at various object distances. For example, the optical lens provided in this embodiment can quickly focus within an object distance range of 65mm-2000mm to obtain a clear image, achieving a depth of field of 1935mm, which helps improve detection efficiency and significantly reduces the cost of detection equipment.

[0080] Among them, because the liquid lens (LQ) is used for focusing, there is no displacement of any lens during the focusing process, resulting in better stability and faster focusing speed.

[0081] Meanwhile, the first lens group 100, the liquid lens LQ, and the second lens group 200 work together to compensate for different working distances by varying the optical power of the liquid lens LQ. By setting the number of lenses in the first lens group 100 and the second lens group 200 located on both sides of the liquid lens LQ and the optical power distribution of each lens, the aberrations introduced by the liquid lens LQ when the curvature changes at large depth of field are eliminated. This expands the original optical lens with a fixed working distance to an optical lens with an adjustable working distance within a range of 1935mm, giving the optical lens a wider range of applications, helping to reduce the overall hardware cost of the visual inspection solution, and significantly improving work efficiency.

[0082] The optical lens provided in this embodiment of the invention can be used to operate in a wide wavelength range of 430nm to 650nm, which includes the main part of the visible spectrum, and is suitable for a variety of high-precision imaging and detection applications.

[0083] Optionally, the liquid lens LQ can be an electrowetting effect lens, which modulates the wetting characteristics of the liquid on the solid surface through an electric field, thereby changing the droplet shape and lens curvature to achieve dynamic adjustment of the focal length. This allows the liquid lens LQ to operate without any mechanical movement, with fast response speed, low energy consumption, and simple structure.

[0084] In other embodiments, the liquid lens LQ may also be other types of liquid lenses, such as graded refractive index lenses, etc., and the embodiments of the present invention do not specifically limit this.

[0085] In summary, the optical lens provided by this invention comprises a first lens group, a liquid lens, and a second lens group that work together. It compensates for variations in working distance by adjusting the optical power of the liquid lens. Furthermore, by setting the number of lenses (10 optical lenses) in the first and second lens groups located on either side of the liquid lens and distributing the optical power of each lens, it eliminates aberrations introduced by the liquid lens when the curvature changes over large depths of field. This expands the original fixed-working-distance focusing optical lens into an adjustable-working-distance optical lens within a 1935mm range, giving it a wider range of applications. With fewer lenses, the total optical length can be reduced to approximately 20mm. Its small size, light weight, and low cost help reduce the overall hardware cost of visual inspection solutions, thereby significantly improving work efficiency.

[0086] As a feasible implementation, as shown in Figures 1 and 2, the object-side surface of the first lens 1 is convex, and the image-side surface is concave; the object-side surface of the second lens 2 is concave, and the image-side surface is concave; the object-side surface of the third lens 3 is convex, and the image-side surface is convex; the object-side surface of the fourth lens 4 is convex, and the image-side surface is convex; the object-side surface of the fifth lens 5 is convex, and the image-side surface is concave; the object-side surface of the sixth lens 6 is concave, and the image-side surface is convex; the object-side surface of the seventh lens 7 is concave, and the image-side surface is convex; the object-side surface of the eighth lens 8 is convex, and the image-side surface is convex; and the object-side surface of the ninth lens 9 is concave, and the image-side surface is convex.

[0087] The object side of a lens refers to the side of the lens facing the object, while the image side refers to the side of the lens facing the image.

[0088] In this embodiment, as shown in Figures 1 and 2, the first lens 1 is a convex-concave lens, meaning that the object-side surface of the first lens 1 convexes towards the object, and the image-side surface of the first lens 1 is concave towards the image. The second lens 2 is a biconcave lens, with both its object-side and image-side surfaces concave towards the image. The third lens 3 is a biconvex lens, with both its object-side and image-side surfaces convex towards the image. The fourth lens 4 is a biconvex lens, with both its object-side and image-side surfaces convex towards the image. The fifth lens 5 is a convex-concave lens, with both its object-side and image-side surfaces concave towards the image. This helps to converge the diverging light rays toward the optical axis and, through the combination of different lenses and their specific surface design (such as convex-concave combination), corrects aberrations to a certain extent. This provides a partially converged and initially corrected beam for the subsequent liquid lens LQ and the second lens group 200, laying the foundation for the final formation of a clear, high-quality image.

[0089] Referring again to Figures 1 and 2, the sixth lens 6 is a concave-convex lens, with its object-side surface concave towards the object side and its image-side surface convex towards the image side. The seventh lens 7 is also a concave-convex lens, with its object-side surface concave towards the object side and its image-side surface convex towards the image side. The eighth lens 8 is a biconvex lens, with both its object-side and image-side surfaces convex towards the object side. The ninth lens 9 is also a concave-convex lens, with its object-side surface concave towards the object side and its image-side surface convex towards the image side. By combining different lenses and using their specific surface designs (e.g., concave-convex combinations), remaining aberrations can be corrected more precisely, ensuring that light rays converge accurately onto the image plane. This allows for precise control of the final image size and the lens's optical magnification, ensuring the final image has high resolution and good visual effects.

[0090] It should be noted that the ninth lens 9 is a concave-convex lens, which helps to reduce the field curvature of the optical lens, thereby reducing aberrations and improving image quality.

[0091] As a possible implementation, as shown in Figures 1 and 2, the optical lens also includes an aperture stop STO, which is located in the optical path between the fifth lens 5 and the liquid lens LQ.

[0092] Alternatively, the aperture stop STO is located in the optical path between the liquid lens LQ and the sixth lens 6.

[0093] The aperture stop STO is used to limit the beam or limit the size of the imaging range (field of view). The aperture stop STO is placed between the fifth lens 5 and the liquid lens LQ, or between the liquid lens LQ and the sixth lens 6. That is, the aperture stop STO is placed in front of or behind the liquid lens LQ. This can control the incident beam and brightness, and improve the imaging quality.

[0094] As a feasible implementation, the aperture stop STO can be located on the edge, frame, or specially designed perforated screen of the liquid lens LQ. Alternatively, the optical lens may not have a separate aperture stop, but can use the edge, frame, etc. of the liquid lens LQ as an aperture stop to limit the size of the beam passing through the lens. This helps to simplify the lens structure and reduce the number of components.

[0095] As a possible implementation, as shown in Figures 1 and 2, the optical lens also includes a flat glass PL, which is located on the image-side side of the ninth lens 9.

[0096] The distance between the first lens 1 and the second lens 2 on the optical axis is d1; the distance between the second lens 2 and the third lens 3 on the optical axis is d2; the distance between the third lens 3 and the fourth lens 4 on the optical axis is d3; and the distance between the fourth lens 4 and the fifth lens 5 on the optical axis is d4.

[0097] 1.11mm≤d1≤1.31mm; 0.52mm≤d2≤0.72mm;

[0098] 0.11mm≤d3≤0.31mm; 0.04mm≤d4≤0.24mm;

[0099] The aperture STO is located between the fifth lens 5 and the liquid lens LQ. The distance between the fifth lens 5 and the aperture STO on the optical axis is d5. The distance between the aperture STO and the liquid lens LQ on the optical axis is d6. The distance between the liquid lens LQ and the sixth lens 6 on the optical axis is d7. The distance between the seventh lens 7 and the eighth lens 8 on the optical axis is d8. The distance between the ninth lens 9 and the flat glass PL on the optical axis is d9.

[0100] 0.55mm≤d5≤0.75mm; 0.05mm≤d6≤0.25mm;

[0101] 0.55mm≤d7≤0.75mm; 0.12mm≤d8≤0.32mm;

[0102] 6.02mm≤d9≤6.82mm.

[0103] The distance between adjacent lenses on the optical axis is also known as the optical interval between them.

[0104] Specifically, the optical spacing between the first lens 1 and the second lens 2 is between 1.21 mm ± 0.1 mm, that is, the optical spacing between the first lens 1 and the second lens 2 is greater than or equal to 1.11 mm and less than or equal to 1.31 mm. The optical spacing between the second lens 2 and the third lens 3 is between 0.62 mm ± 0.1 mm, that is, the optical spacing between the second lens 2 and the third lens 3 is greater than or equal to 0.52 mm and less than or equal to 0.72 mm, and so on. The optical spacing between the third lens 3 and the fourth lens 4 is between 0.21 mm ± 0.1 mm, and the optical spacing between the fourth lens 4 and the fifth lens 5 is between 0.14 mm ± 0.1 mm.

[0105] Referring to Figures 1 and 2, the example of the aperture STO being located between the fifth lens 5 and the liquid lens LQ is given. The optical distance between the fifth lens 5 and the aperture STO is between 0.65mm ± 0.1mm; the optical distance between the aperture STO and the liquid lens LQ is between 0.15mm ± 0.1mm.

[0106] In addition, the optical spacing between the liquid lens LQ and the sixth lens 6 is between 0.65mm ± 0.1mm; the optical spacing between the seventh lens 7 and the eighth lens 8 is between 0.22mm ± 0.1mm.

[0107] Furthermore, the optical spacing between the ninth lens 9 and the flat glass PL is between 6.42mm ± 0.4mm.

[0108] In this embodiment, by appropriately setting the spacing between adjacent lenses on the optical axis, it is helpful to further correct imaging aberrations and achieve high-definition imaging over a wide object distance range. Simultaneously, it allows for a more compact overall structure of the optical imaging lens, enabling miniaturized design and facilitating subsequent assembly.

[0109] It should be noted that the optical spacing between the lenses can be flexibly adjusted as needed, and is not limited to the distances listed above.

[0110] As a feasible implementation method, the diopter of the liquid lens LQ is D, -9≤D≤6.

[0111] Specifically, depending on the driving voltage or driving current, the liquid lens LQ will have different diopter to correspond to different working distances.

[0112] In this embodiment, by changing the refractive power range of the liquid lens LQ, the working distance range of the optical lens can be adjusted, thereby expanding the depth of field range of the optical lens.

[0113] Furthermore, by setting the diopter D of the liquid lens LQ to satisfy -9≤D≤6, a large depth of field of 1935mm can be achieved while maintaining image quality. For example, when the diopter of the liquid lens LQ is -9, the working distance of the optical lens can reach 2000mm; when the diopter of the liquid lens LQ is 6, the working distance of the optical lens can reach 65mm.

[0114] In barcode scanning applications, the dynamic adjustment capability of the liquid lens (LQ) allows the optical lens to quickly adapt to barcodes at different distances, ensuring scanning accuracy and efficiency.

[0115] In industrial automation, this optical lens can be used to inspect workpieces at different distances, such as large mechanical parts and small electronic components, providing high-resolution and low-chromatic-difference images and improving inspection accuracy.

[0116] As a feasible implementation, the focal length of the fourth lens 4 is f4, the focal length of the fifth lens 5 is f5, and -1≤f4 / f5<0.

[0117] Among them, the converging ability of the fourth lens 4 allows light to converge more concentratedly at the aperture position after the fifth lens 5, providing a better basis for the dynamic adjustment of the liquid lens LQ.

[0118] The diverging effect of the fifth lens 5 can counteract some of the aberrations introduced by the fourth lens 4, ensuring that the light has been initially corrected before entering the liquid lens LQ.

[0119] In this embodiment, by reasonably setting the focal length ratio of the fourth lens 4 and the fifth lens 5, the same magnification can be achieved under different object distance ranges, so that the optical lens can maintain stable imaging quality at different working distances. This is beneficial to reducing the parallax of the final image, especially in applications with large depth of field, ensuring that different objects from near to far can be clearly imaged.

[0120] As a feasible implementation, the distance between the object side and the image side of the fourth lens 4 on the optical axis is d10, and the distance between the image side and the object side of the liquid lens LQ on the optical axis is d11, where 0 < d10 / d11 ≤ 5.

[0121] Among them, the fourth lens 4, as a converging lens, can further converge the light rays after passing through the third lens 3. The distance d10 between the object side and the image side of the fourth lens 4 on the optical axis (i.e. the thickness of the fourth lens 4) can affect the propagation path of light rays inside the lens, thereby affecting the image quality.

[0122] The fifth lens 5, as a diverging lens, can be used to adjust the path of light rays so that they reach an appropriate diverging state before entering the liquid lens LQ. The distance d11 between the fifth lens 5 and the liquid lens LQ can affect the position of the convergence point of the light rays and the aberration correction effect.

[0123] In this embodiment, by reasonably setting the distance d10 between the object-side surface and the image-side surface of the fourth lens 4 on the optical axis, and the distance d11 between the image-side surface of the fifth lens 5 and the object-side surface of the liquid lens LQ on the optical axis, satisfying 0 < d10 / d11 ≤ 5, it is ensured that light rays can converge more concentratedly to the aperture stop position (i.e., the object-side surface position of the liquid lens LQ) after the fifth lens 5. This design helps to improve the sharpness and resolution of the image and enables the same magnification at different object distances, allowing the optical lens to maintain stable image quality at different working distances. This is beneficial for reducing parallax in the final image, especially in applications with large depth of field, ensuring that different objects from near to far can be clearly imaged.

[0124] As a feasible implementation method, the principal ray angle of the optical lens is greater than or equal to 10° and less than or equal to 15°.

[0125] The principal ray angle (CRA) refers to the angle between the light ray emitted from the object point and the optical axis on the image plane after passing through the lens system.

[0126] In this embodiment, by setting the principal ray angle CRA of the optical lens to satisfy 10°≤CRA≤15°, it is possible to ensure uniform light distribution on the image plane without significantly increasing the number of lenses. This enables the same magnification across different object distances, which helps reduce parallax in the final image and thus helps to extend the depth of field. It ensures that light can clearly image objects at different distances, especially in applications with large depth of field, such as barcode scanning and industrial inspection, which can effectively reduce aberrations and improve image clarity and resolution.

[0127] As a feasible implementation, the focal length of the second lens 2 is f2, the focal length of the optical lens is f, and -3≤f2 / f<0.

[0128] Among them, the second lens 2, as a diverging lens, can be used to deflect the light after passing through the first lens 1, and undertake a certain task of adjusting the optical power.

[0129] In this embodiment, by appropriately setting the ratio between the focal length f2 of the second lens 2 and the focal length f of the optical lens, aberrations can be effectively balanced, improving the imaging quality of the optical lens. Simultaneously, combined with the dynamic adjustment capability of the liquid lens LQ, the focal length design of the second lens 2 can further optimize the light propagation path, enabling the lens to maintain stable imaging quality at different working distances. Especially in applications with large depth of field, it ensures that different objects from near to far are clearly imaged.

[0130] As a feasible implementation, the central radius of curvature of the object side of the second lens 2 is R1, and the central radius of curvature of the image side of the second lens 2 is R2, where 0≤(R1+R2) / (R1-R2)≤1.22.

[0131] By rationally setting the relationship between the central curvature radius R1 of the object-side surface of the second lens 2 and the central curvature radius R2 of the image-side surface of the second lens 2, aberrations can be effectively reduced without significantly affecting the overall optical power, thereby improving the imaging quality of the optical lens. Simultaneously, combined with the dynamic adjustment capability of the liquid lens (LQ), the focal length design of the second lens 2 can further optimize the light propagation path, enabling the lens to maintain stable imaging quality at different working distances. Especially in applications with large depth of field, it ensures that different objects from near to far are clearly imaged.

[0132] As one possible implementation, as shown in Figures 1 and 2, the sixth lens 6 and the seventh lens 7 form the first cemented lens group 11.

[0133] The first cemented lens group 11, consisting of the sixth lens 6 and the seventh lens 7, helps to reduce the spherical aberration between the near-optical axis and the far-optical axis, thus reducing the impact of chromatic aberration on imaging.

[0134] At the same time, it can effectively reduce the air gap between the sixth lens 6 and the seventh lens 7, thereby further reducing the overall length of the lens. Under the premise of compact structure, it can improve resolution, optimize optical performance such as distortion, and reduce light loss caused by reflection between lenses, thereby improving illumination, thus improving image quality and enhancing the clarity of lens imaging.

[0135] In addition, the use of the first cemented lens group 11 can reduce the number of assembly parts between the two lenses, simplify the assembly process in the lens manufacturing process, reduce costs, effectively reduce the errors that occur when fitting lenses, reduce the tolerance sensitivity of the lens unit due to tilting / eccentricity during the assembly process, and improve imaging resolution and imaging quality.

[0136] As one possible implementation, as shown in Figures 1 and 2, the eighth lens 8 and the ninth lens 9 form the second cemented lens group 12.

[0137] The second cemented lens group 12, consisting of the eighth lens 8 and the ninth lens 9, helps to reduce the spherical aberration between the near-optical axis and the far-optical axis, thus reducing the impact of chromatic aberration on imaging.

[0138] At the same time, it can effectively reduce the air gap between the eighth lens 8 and the ninth lens 9, thereby further reducing the overall length of the lens. Under the premise of compact structure, it can improve resolution, optimize optical performance such as distortion, and reduce light loss caused by reflection between lenses, thereby improving illumination, thus improving image quality and enhancing the clarity of lens imaging.

[0139] In addition, the use of the second cemented lens group 12 can reduce the number of assembly parts between the two lenses, simplify the assembly process in the lens manufacturing process, reduce costs, effectively reduce errors that occur when fitting lenses, reduce the tolerance sensitivity of the lens unit due to tilting / eccentricity during the assembly process, and improve imaging resolution and imaging quality.

[0140] As a feasible implementation, the focal length of the third lens 3 is f3, the focal length of the fourth lens 4 is f4, and 0 < f3 / f4 ≤ 1.

[0141] Among them, the third lens 3, as a converging lens, can further converge the light after passing through the second lens 2, reduce the diffusion angle of the light, and ensure that the light can enter the subsequent lenses more concentratedly.

[0142] The fourth lens 4 also serves as a converging lens. Its larger focal length can be used to balance aberrations and ensure that light rays can converge more concentratedly to the aperture stop position (i.e., the object side position of the liquid lens LQ) after the fifth lens 5.

[0143] In this embodiment, by reasonably setting the focal length f3 of the third lens 3 and the focal length f4 of the fourth lens 4 to satisfy 0 < f3 / f4 ≤ 1, aberrations can be effectively reduced without significantly affecting the overall optical power, thereby improving the imaging quality of the optical lens. Simultaneously, combined with the dynamic adjustment capability of the liquid lens LQ, the same magnification can be achieved across different object distances, which helps reduce parallax in the final image, thus expanding the depth of field and ensuring clear imaging of objects at different distances. This is particularly beneficial in applications with large depth of field, such as barcode scanning and industrial inspection, effectively reducing aberrations and improving image clarity and resolution.

[0144] As a feasible implementation, the thickness of the first lens 1 on the optical axis is d12, the total optical length of the optical lens is TTL, and 0 < d12 / TTL ≤ 0.08.

[0145] The thickness d12 of the first lens 1 on the optical axis can be understood as the distance between the object side and the image side of the first lens 1 on the optical axis.

[0146] The total optical length (TTL) of an optical lens refers to the distance from the center of the optical axis on the object side of the first lens 1 to the image plane.

[0147] The first lens 1, as the first lens in the optical system, can be used to initially introduce light and adjust the incident angle of the light. The thickness d12 of the first lens 1 on the optical axis has a direct impact on the propagation path of the light; an appropriate thickness helps to reduce aberrations and improve image quality.

[0148] In this embodiment, by limiting the ratio between the thickness d12 of the first lens 1 on the optical axis and the total optical length TTL, the size and weight of the lens can be significantly reduced without significantly affecting the optical performance, making it more compact.

[0149] As a feasible implementation, the distance between the third lens 3 and the fourth lens 4 on the optical axis is d3, and the distance between the object side surface of the fourth lens 4 and the image side surface of the fourth lens 4 on the optical axis is d10, where 0≤d3 / d10≤5.

[0150] The distance d3 between the third lens 3 and the fourth lens 4 on the optical axis can be understood as the axial distance from the image side of the third lens 3 to the object side of the fourth lens 4.

[0151] The distance d10 between the object side and the image side of the fourth lens 4 on the optical axis can be understood as the thickness of the fourth lens 4 on the optical axis.

[0152] In this embodiment, by reasonably limiting the distance d3 between the third lens 3 and the fourth lens 4 on the optical axis and the distance d10 between the object side and the image side of the fourth lens 4 on the optical axis to satisfy 0≤d3 / d10≤5, the propagation path of light can be optimized and aberrations reduced without significantly affecting the overall optical power. Simultaneously, combined with the dynamic adjustment capability of the liquid lens LQ, the same magnification can be achieved across different object distances, which helps reduce parallax in the final image, thereby expanding the depth of field and ensuring clear imaging of objects at different distances.

[0153] As a feasible implementation, the focal length of the fifth lens 5 is f5, the focal length of the sixth lens 6 is f6, and -20≤f5 / f6<1.

[0154] Specifically, by reasonably limiting the focal length f5 of the fifth lens 5 and the focal length f6 of the sixth lens 6 to -20 ≤ f5 / f6 < 1, the absolute value of the focal length of the fifth lens 5 is greater than that of the sixth lens 6. In this case, the fifth lens 5 has a larger divergence angle than the sixth lens 6, allowing it to optimize the light path over a wider angular range and reduce aberrations. Simultaneously, combined with the dynamic adjustment capability of the liquid lens LQ, the same magnification can be achieved across different object distances, which helps reduce parallax in the final image, thereby expanding the depth of field and ensuring clear imaging of objects at different distances.

[0155] As one feasible implementation, the object-side radius of curvature of the first lens 1 is 15.2 mm ± 0.1 mm, and the image-side radius of curvature is 6.3 mm ± 0.1 mm. The object-side radius of curvature of the second lens 2 is -22.2 mm ± 0.2 mm, and the image-side radius of curvature is 15.4 mm ± 0.1 mm. The object-side radius of curvature of the third lens 3 is 987.2 mm ± 0.1 mm, and the image-side radius of curvature is -21.2 mm ± 0.2 mm. The object-side radius of curvature of the fourth lens 4 is 15.6 mm ± 0.2 mm, and the image-side radius of curvature is 19.2 mm ± 0.2 mm. The object-side radius of curvature of the fifth lens 5 is 8.3 mm ± 0.1 mm, and the image-side radius of curvature is 5.2 mm ± 0.1 mm. The sixth lens 6 has an object-side radius of curvature of -21.1 mm ± 0.1 mm and an image-side radius of curvature of -5.4 mm ± 0.2 mm. The seventh lens 7 has an object-side radius of curvature of -5.4 mm ± 0.2 mm and an image-side radius of curvature of -8.6 mm ± 0.2 mm. The eighth lens 8 has an object-side radius of curvature of 18.2 mm ± 0.1 mm and an image-side radius of curvature of -7.3 mm ± 0.1 mm. The ninth lens 9 has an object-side radius of curvature of -7.3 mm ± 0.1 mm and an image-side radius of curvature of -22.4 mm ± 0.2 mm.

[0156] The radius of curvature represents the degree of curvature of the lens surface. A positive value means that the surface bends toward the object plane with the center of the circle closer to the image plane; a negative value means that the surface bends toward the image plane with the center of the circle closer to the object plane.

[0157] In this embodiment, by reasonably setting the curvature radii of the object-side and image-side surfaces of each lens, imaging aberrations can be further corrected and imaging quality improved. At the same time, combined with the dynamic adjustment capability of the liquid lens LQ, the same magnification can be achieved under different object distances, which helps to reduce the parallax of the final image, thereby expanding the depth of field and ensuring that light can clearly image objects at different distances.

[0158] As a feasible implementation, the first lens 1 has a refractive index of 1.56±0.05 and an Abbe number of 64.8±0.02. The second lens 2 has a refractive index of 1.78±0.05 and an Abbe number of 34.2±0.02. The third lens 3 has a refractive index of 1.65±0.05 and an Abbe number of 55.3±0.02. The fourth lens 4 has a refractive index of 1.76±0.05 and an Abbe number of 45.8±0.02. The fifth lens 5 has a refractive index of 1.90±0.05 and an Abbe number of 30.6±0.02. The sixth lens 6 has a refractive index of 1.65±0.05 and an Abbe number of 58.6±0.02. The seventh lens 7 has a refractive index of 1.78±0.05 and an Abbe number of 30.6±0.02. The refractive index of the eighth lens 8 is 1.56±0.05, and the Abbe number is 56.6±0.02. The refractive index of the ninth lens 9 is 1.82±0.05, and the Abbe number is 23.6±0.02.

[0159] The refractive index is the ratio of the speed of light in a vacuum to the speed of light in the medium. It is mainly used to describe a material's ability to refract light, and different materials have different refractive indices.

[0160] The Abbe number is an index used to represent the dispersion ability of a transparent medium. The more severe the dispersion of the medium, the smaller the Abbe number; conversely, the less severe the dispersion of the medium, the larger the Abbe number.

[0161] In this embodiment, by reasonably limiting the refractive index and Abbe number of each lens, aberrations can be corrected to a greater extent and the imaging quality can be improved. At the same time, combined with the dynamic adjustment capability of the liquid lens LQ, the same magnification can be achieved under different object distances, which helps to reduce the parallax of the final image, thereby expanding the depth of field and ensuring that light can be clearly imaged on objects at different distances.

[0162] It should be noted that the radius of curvature, refractive index, and Abbe number of the first lens 1 to the ninth lens 9 mentioned above are examples of the case where each lens is a glass spherical mirror, but are not limited to this.

[0163] In other embodiments, the first lens 1 to the ninth lens 9 may also be a plastic aspherical mirror, a glass spherical mirror, or a combination of the two, and the embodiments of the present invention do not specifically limit this.

[0164] In addition, to ensure image quality, the aperture deviation of each lens is small, and the radius of curvature of each lens can be constrained within the range of three apertures of Newton's rings. While achieving a wide object distance range and improving image quality, it also makes each lens uniform in thickness, thus making it easy to process and convenient to assemble.

[0165] Understandably, the shape parameters of each lens can be flexibly adjusted as needed, and are not limited to the parameters listed above. The curvature and materials of all the lenses mentioned above can also be optimized through various aberration corrections, thereby ensuring the optical performance and stability of the optical lens.

[0166] As one feasible implementation, the liquid lens LQ includes a driving circuit assembly, which is used to apply a driving voltage or driving current to the electrodes of the liquid lens LQ to adjust the curvature of the object side and image side of the liquid lens, thereby changing the focal length and achieving focusing at different working distances.

[0167] Specific embodiments of the optical lens applicable to the above-described embodiments are further described below with reference to the accompanying drawings.

[0168] Table 1 details the radius of curvature, thickness, refractive index, and Abbe number of each lens in the optical lens provided in the embodiment, using a feasible implementation method. The optical lenses in Table 1 can correspond to the lenses shown in Figures 1 and 2.

[0169] Table 1. Parameters of each lens in an optical lens

[0170] Surface No. Radius of Curvature Thickness Refractive Index Abbe Number 1 15.2 1.2 2 1.5 6 6 4.8 2 6.3 1.2 1 3 -2 2 1.1 2 1.7 8 3 4.2 4 15.4 0.6 2 5 9 8 7.2 1.9 8 1.6 5 5 5.3 6 -2 1.2 0.2 1 7 15.6 1.5 6 1.7 6 4 5.8 8 19.2 0.1 4 9 8.3 2.9 8 1.9 0 3 0.6 1 0 5.2 0.8 0 LQ\ 0.6 5 1 1 -2 1.1 1.2 3 1.6 5 8.6 1 2 -5.4 0.8 8 1.7 8 3 0.6 1 3 -8.6 0.2 2 1 4 1 8.2 2.3 4 1.5 6 5 6.6 1 5 -7.3 1.2 4 1.8 2 2 3.6 1 6 -2 2.4 6.4 2 surface

[0171] A lens typically comprises two surfaces, each serving as a refractive surface. The surface numbers in Table 1 are assigned based on the surface of each lens. Surface number 1 is the object-side surface of the first lens 1, and surface number 2 is the image-side surface of the first lens 1. Surface number 3 is the object-side surface of the second lens 2, and surface number 4 is the image-side surface of the second lens 2. Surface number 5 is the object-side surface of the third lens 3, and surface number 6 is the image-side surface of the third lens 3. Surface number 7 is the object-side surface of the fourth lens 4, and surface number 8 is the image-side surface of the fourth lens 4. Surface number 9 is the object-side surface of the fifth lens 5, and surface number 10 is the image-side surface of the fifth lens 5. Surface number 11 is the object-side surface of the sixth lens 6, surface number 12 is either the image-side surface of the sixth lens 6 or the object-side surface of the seventh lens 7, surface number 13 is the image-side surface of the seventh lens 7, and surface number 14 is the object-side surface of the eighth lens 8. The image-side surface of the eighth lens 8 (surface number 15) is the object-side surface of the ninth lens 9, and the image-side surface of the ninth lens 9 (surface number 16) is the image-side surface of the ninth lens 9.

[0172] The radius of curvature represents the curvature of the lens surface. A positive radius of curvature value indicates that the center of curvature is on the image side of the surface, while a negative radius of curvature value indicates that the center of curvature is on the image side of the surface. A backslash "\" in the radius of curvature column indicates that the surface is flat. The unit of radius of curvature is mm. The value in the thickness column indicates the axial distance between the current surface and the next surface, also in mm. The refractive index column indicates the refractive index of the medium between the current surface and the next surface. A blank space in the refractive index column represents the refractive index of air, which is 1. The Abbe number represents the dispersion characteristics of the material between the current surface and the next surface; a blank space indicates that the current location is air.

[0173] The optical lens operates at a wavelength between 430nm and 650nm, with a working distance between 65mm and 2000mm, a maximum field of view of 882.2mm ± 5mm, and a focal length of 8mm ± 0.5mm.

[0174] This optical lens can achieve focusing without moving the lens by applying a driving signal to the liquid lens to cause its surface to deform rapidly.

[0175] Therefore, the optical lens in the above embodiment can focus quickly within the object distance range of 65mm-2000mm, which not only improves the efficiency of detection, but also greatly reduces the cost of detection equipment and labor costs.

[0176] Furthermore, Figure 3 is a field curvature diagram of an optical lens provided in an embodiment of the present invention at a working distance of 65mm, and Figure 4 is a field curvature diagram of an optical lens provided in an embodiment of the present invention at a working distance of 2000mm. As shown in Figures 3 and 4, the solid line represents the tangential curve, while the dashed line represents the sagittal curve. The unit of the horizontal axis is millimeters, and the vertical axis corresponds to the (half) field of view of the optical lens + Y.

[0177] Figure 5 shows the distortion diagram of an optical lens provided in an embodiment of the present invention at a working distance of 65mm, and Figure 6 shows the distortion diagram of an optical lens provided in an embodiment of the present invention at a working distance of 2000mm. As shown in Figures 5 and 6, the horizontal axis represents the percentage of distortion, and the vertical axis corresponds to the (half) field of view of the optical lens.

[0178] The analytical images presented in this embodiment only study half-field performance. From the field curvature and distortion diagrams of the optical lenses at different working distances, it can be seen that the field curvature of the optical lens provided in this embodiment is effectively controlled at working distances of 65mm and 2000mm. Meanwhile, the largest distortion generally occurs at the entire edge of the field of view, and the distortion gradually increases according to the field of view. The maximum distortion of this optical lens is 1%. Therefore, the distortion of the optical lens at working distances of 65mm and 2000mm is also well corrected, enabling the optical lens to maintain high imaging quality over a wide range of working distances.

[0179] Figure 7 shows the optical transfer function (OTF) of an optical lens provided in this embodiment at a working distance of 65mm, and Figure 8 shows the OTF of an optical lens provided in this embodiment at a working distance of 2000mm. As shown in Figures 7 and 8, the horizontal axis represents spatial frequency, and the vertical axis represents the modulus of the OTF. The solid line represents the tangential curve, while the dashed line represents the sagittal curve. The figures show the spatial transfer function of the optical lens in its working band, which is one of the performance parameters of the optical lens in this band and is a way to evaluate the resolution of the optical lens. The modulation transfer function (FFT MTF) graphs for each Fourier transform show the corresponding tangential and sagittal curves for different fields of view. A higher OTF modulus results in a clearer image. Figures 7 and 8 show that the optical lens provided in this embodiment has excellent imaging quality over a wide field of view at working distances of 65mm and 2000mm.

[0180] Figure 9 shows the axial chromatic aberration diagram of an optical lens provided in an embodiment of the present invention at a working distance of 65mm, and Figure 10 shows the axial chromatic aberration diagram of an optical lens provided in an embodiment of the present invention at a working distance of 2000mm. Figure 9 shows the axial chromatic aberration diagrams of the optical lens at a working distance of 65mm at wavelengths of 430nm, 486nm, 546nm, 588nm, and 656nm, and Figure 10 shows the axial chromatic aberration diagrams of the optical lens at a working distance of 2000mm at wavelengths of 430nm, 486nm, 546nm, 588nm, and 656nm. As shown in Figures 9 and 10, the above-mentioned axial chromatic aberrations respectively reflect the imaging aberrations of the optical lenses at working distances of 65mm and 2000mm at different wavelengths. The distribution of aberrations at different wavelengths is also an important way to evaluate the overall imaging characteristics of an optical system. From the analysis of the figures, it can be seen that the optical lens achieves a good effect in correcting chromatic aberration.

[0181] It should be noted that this embodiment expands the focusing range of the original fixed focal length optical lens by 1935mm, thereby expanding the application scenarios of the optical lens and saving manpower and overall costs to a great extent.

[0182] In this embodiment of the invention, the optical lens has a small number of lenses and low cost, the depth of field can reach within the range of 1935mm, the working distance can be between 65mm and 2000mm, the magnification can reach more than 90%, it has a wide wavelength range of 430nm-650nm, and the parallax and aberration are small.

[0183] Among them, by controlling the driving voltage or driving current of the liquid lens to adjust the focus position of the optical lens in real time, the goal of fast focusing at different working distances can be achieved. During the focusing process, the lens does not shift, resulting in better stability and faster focusing speed. At the same time, driving the optical lens does not require the use of drive motors or other equipment, which not only makes the overall size smaller and the structure more compact, but also makes it more convenient to use and relatively cheaper. It can avoid the problems of high testing costs and low efficiency caused by moving the internal lens of the camera or moving the position of the camera when testing ultra-large depth of field.

[0184] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0185] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. An optical lens, characterized in that, The optical lens comprises a first lens group, a liquid lens, and a second lens group arranged sequentially from the object side to the image side along the optical axis; the first lens group has positive optical power, and the second lens group has positive optical power; the first lens group consists of a first lens, a second lens, a third lens, a fourth lens, and a fifth lens arranged sequentially from the object side to the image side; the second lens group consists of a sixth lens, a seventh lens, an eighth lens, and a ninth lens arranged sequentially from the object side to the image side; the first lens has negative optical power, the second lens has negative optical power, the third lens has positive optical power, and the fourth lens has positive optical power. The first lens has a positive optical power, the second lens has a concave object side and the third lens has a convex object side and the fourth lens has a convex object side and the fifth lens has a convex object side and the sixth lens has a concave object side and the sixth lens has a convex object side and the sixth lens has a convex object side and the seventh lens has a positive optical power. The object side of the first lens is convex, and the image side is concave. The object side of the second lens is concave, and the image side is concave. The seventh lens has a concave object-side surface and a convex image-side surface; the eighth lens has a convex object-side surface and a convex image-side surface; the ninth lens has a concave object-side surface and a convex image-side surface; the optical lens also includes a flat glass plate located on one side of the image-side surface of the ninth lens; the distance between the first lens and the second lens on the optical axis is d1; the distance between the second lens and the third lens on the optical axis is d2; the distance between the third lens and the fourth lens on the optical axis is d3; the distance between the fourth lens and the fifth lens on the optical axis is... d4; 1.11mm≤d1≤1.31mm; 0.52mm≤d2≤0.72mm; 0.11mm≤d3≤0.31mm; 0.04mm≤d4≤0.24mm; The distance between the liquid lens and the sixth lens on the optical axis is d7, the distance between the seventh lens and the eighth lens on the optical axis is d8, and the distance between the ninth lens and the flat glass on the optical axis is d9; 0.55mm≤d7≤0.75mm; 0.12mm≤d8≤0.32mm; 6.02mm≤d9≤6.82mm.

2. The optical lens according to claim 1, characterized in that, The optical lens further includes an aperture stop; the aperture stop is located in the optical path between the fifth lens and the liquid lens; or, the aperture stop is located in the optical path between the liquid lens and the sixth lens.

3. The optical lens according to claim 2, characterized in that, The aperture is located between the fifth lens and the liquid lens. The distance between the fifth lens and the aperture on the optical axis is d5, and the distance between the aperture and the liquid lens on the optical axis is d6; 0.55mm≤d5≤0.75mm; 0.05mm≤d6≤0.25mm.

4. The optical lens according to claim 1, characterized in that, The diopter of the liquid lens is D, where -9 ≤ D ≤ 6.

5. The optical lens according to claim 1, characterized in that, The focal length of the fourth lens is f4, the focal length of the fifth lens is f5, and -1 ≤ f4 / f5 < 0.

6. The optical lens according to claim 1, characterized in that, The distance between the object-side surface of the fourth lens and the image-side surface of the fourth lens on the optical axis is d10, and the distance between the image-side surface of the fifth lens and the object-side surface of the liquid lens on the optical axis is d11, where 0 < d10 / d11 ≤ 5.

7. The optical lens according to claim 1, characterized in that, The principal ray angle of the optical lens is greater than or equal to 10° and less than or equal to 15°.

8. The optical lens according to claim 1, characterized in that, The focal length of the second lens is f2, and the focal length of the optical lens is f, -3≤f2 / f<0.

9. The optical lens according to claim 1, characterized in that, The central radius of curvature of the object side of the second lens is R1, and the central radius of curvature of the image side of the second lens is R2, 0≤(R1+R2) / (R1-R2)≤1.

22.

10. The optical lens according to claim 1, characterized in that, The sixth lens and the seventh lens form a first cemented lens group; and / or, the eighth lens and the ninth lens form a second cemented lens group.

11. The optical lens according to claim 1, characterized in that, The focal length of the third lens is f3, the focal length of the fourth lens is f4, and 0 < f3 / f4 ≤ 1.

12. The optical lens according to claim 1, characterized in that, The thickness of the first lens on the optical axis is d12, and the total optical length of the optical lens is TTL, where 0 < d12 / TTL ≤ 0.

08.

13. The optical lens according to claim 1, characterized in that, The distance between the third lens and the fourth lens on the optical axis is d3, and the distance between the object side surface and the image side surface of the fourth lens on the optical axis is d10, where 0≤d3 / d10≤5.

14. The optical lens according to claim 1, characterized in that, The focal length of the fifth lens is f5, the focal length of the sixth lens is f6, and -20 ≤ f5 / f6 < 1.

Images