Optical lens

Abstract

The application discloses an optical lens, which comprises a first group with positive refractive power, a liquid lens with refractive power, a second group with positive refractive power and an imaging surface along the optical axis from the object side to the imaging surface in sequence. The first group comprises a first lens with positive refractive power, a second lens with negative refractive power, a third lens with negative refractive power and a fourth lens with positive refractive power from the object side to the imaging surface in sequence. The liquid lens presents different focal lengths according to different applied voltages. The second group comprises a fifth lens with positive refractive power, a sixth lens with negative refractive power, a seventh lens with positive refractive power, an eighth lens with positive refractive power and a ninth lens with negative refractive power from the object side to the imaging surface in sequence. The optical lens has the advantages of fast focusing, small volume, high image quality and the like.

Description

Technical Field

[0001] This invention relates to the field of imaging lens technology, and in particular to an optical lens. Background Technology

[0002] In recent years, with the development of the automation industry, machine vision has experienced explosive growth, and the application fields of industrial lenses have become increasingly widespread. Due to their characteristics of high resolution, high definition, and good stability, industrial lenses are widely used in fields such as dimensional measurement, defect detection, and image acquisition.

[0003] To achieve good image acquisition and analysis capabilities, these industrial lenses typically require high-resolution imaging to capture the image features of the subject and high relative illumination to ensure uniform illumination. Simultaneously, to ensure good imaging performance at different working distances, the lens needs to acquire images at varying distances through focusing. However, traditional lens focusing methods rely on mechanical motion. For example, a motor is installed inside the lens to drive lens elements or lens groups to move laterally along the optical axis, changing the optical spacing between lens elements or between the lens and the camera sensor, thereby compensating for the shift in focus caused by changes in working distance. However, these mechanically focusing lenses suffer from slow focusing speeds, the need for manual focusing, and large size, making them unsuitable for applications with high real-time requirements. Summary of the Invention

[0004] Therefore, the purpose of this invention is to provide an optical lens that has at least the advantages of fast autofocus, small size, and high image quality.

[0005] The present invention achieves the above objectives through the following technical solutions.

[0006] This invention provides an optical lens comprising, along the optical axis from the object side to the imaging plane, the following elements in sequence: a first group having positive optical power, the first group comprising, from the object side to the imaging plane, a first lens having positive optical power, a second lens having negative optical power, a third lens having negative optical power, and a fourth lens having positive optical power; a liquid lens having optical power, the liquid lens exhibiting different focal lengths depending on the applied voltage; and a second group having positive optical power, the second group comprising, from the object side to the imaging plane, a fifth lens having positive optical power, a sixth lens having negative optical power, a seventh lens having positive optical power, an eighth lens having positive optical power, and a ninth lens having negative optical power.

[0007] In some embodiments, the object-side surface of the first lens is convex, and the image-side surface of the first lens is concave.

[0008] In some embodiments, the object-side surface of the second lens is convex, and the image-side surface of the second lens is concave.

[0009] In some embodiments, the object-side surface of the third lens is convex, and the image-side surface of the third lens is concave.

[0010] In some embodiments, the object-side surface of the fourth lens is convex, and the image-side surface of the fourth lens is concave.

[0011] In some embodiments, the object-side surface of the fifth lens is convex or concave, and the image-side surface of the fifth lens is convex.

[0012] In some embodiments, the object-side surface of the sixth lens is concave, and the image-side surface of the sixth lens is convex.

[0013] In some embodiments, the object-side surface of the seventh lens is convex or concave, and the image-side surface of the seventh lens is convex.

[0014] In some embodiments, the object-side surface of the eighth lens is convex, and the image-side surface of the eighth lens is convex.

[0015] In some embodiments, the object-side surface of the ninth lens is concave, and the image-side surface of the ninth lens is convex.

[0016] In some embodiments, the third lens and the fourth lens form a cemented lens.

[0017] In some embodiments, the fifth lens and the sixth lens form a cemented lens.

[0018] In some embodiments, the liquid lens is provided with an aperture.

[0019] In some embodiments, a filter and a protective glass are provided between the ninth lens and the imaging surface.

[0020] In some embodiments, the total optical length (TTL) of the optical lens satisfies: TTL < 24 mm.

[0021] In some embodiments, the effective focal length f of the optical lens satisfies: 7mm < f < 9mm.

[0022] In some embodiments, the maximum field of view (FOV) of the optical lens satisfies: FOV > 50°.

[0023] In some embodiments, the image height IH corresponding to the maximum field of view of the optical lens satisfies: IH > 8mm.

[0024] In some embodiments, the aperture value Fno of the optical lens satisfies: Fno < 2.4.

[0025] In some embodiments, the working object distance OBJ of the optical lens satisfies: 100mm≤OBJ≤400mm.

[0026] In some embodiments, the driving voltage U of the liquid lens satisfies: 30.0V < U < 50.0V.

[0027] In some embodiments, the effective focal length fb of the liquid lens satisfies: |fb|>200mm.

[0028] In some embodiments, the effective focal length fa of the first group and the effective focal length f of the optical lens satisfy: 1.5 < fa / f < 7.0.

[0029] In some embodiments, the effective focal length fc of the second group and the effective focal length f of the optical lens satisfy: 0.6 < fc / f < 1.6.

[0030] In some implementations, the effective focal length fa of the first group and the effective focal length fc of the second group satisfy: 2.0 < fa / fc < 7.0.

[0031] In some embodiments, the effective focal length f1 of the first lens and the effective focal length f of the optical lens satisfy: 2.0 < f1 / f < 4.0.

[0032] In some embodiments, the effective focal length f2 of the second lens and the effective focal length f of the optical lens satisfy: -2.0 < f2 / f < -0.5.

[0033] In some embodiments, the effective focal length f3 of the third lens and the effective focal length f of the optical lens satisfy: -1.2 < f3 / f < -0.2.

[0034] In some embodiments, the effective focal length f4 of the fourth lens and the effective focal length f of the optical lens satisfy: 0.1 < f4 / f < 0.8.

[0035] In some embodiments, the effective focal length f5 of the fifth lens and the effective focal length f of the optical lens satisfy: 0.2 < f5 / f < 0.7.

[0036] In some embodiments, the effective focal length f6 of the sixth lens and the effective focal length f of the optical lens satisfy: -0.6 < f6 / f < -0.2.

[0037] In some embodiments, the effective focal length f7 of the seventh lens and the effective focal length f of the optical lens satisfy the condition: 0.5 < f7 / f < 1.5.

[0038] In some embodiments, the effective focal length f8 of the eighth lens and the effective focal length f of the optical lens satisfy: 1.0 < f8 / f < 3.0.

[0039] In some embodiments, the effective focal length f9 of the ninth lens and the effective focal length f of the optical lens satisfy: -3.5 < f9 / f < -1.5.

[0040] In some embodiments, the total optical length (TTL) of the optical lens and the effective focal length (f) of the optical lens satisfy the condition: 2.5 < TTL / f < 3.5.

[0041] In some embodiments, the image height IH corresponding to the maximum field of view of the optical lens and the effective focal length f of the optical lens satisfy the following condition: 1.1 < IH / f < 1.5.

[0042] In some embodiments, the radius of curvature R1 of the object side of the first lens and the radius of curvature R2 of the image side of the first lens satisfy: 0.1 < R1 / R2 < 0.4.

[0043] In some embodiments, the radius of curvature R3 of the object side of the second lens and the radius of curvature R4 of the image side of the second lens satisfy: 2.5 < R3 / R4 < 8.0.

[0044] In some embodiments, the radius of curvature R6 of the object side of the fourth lens and the radius of curvature R7 of the image side of the fourth lens satisfy: 0 < R6 / R7 < 0.5.

[0045] In some embodiments, the radius of curvature R15 of the object side of the sixth lens and the radius of curvature R16 of the image side of the sixth lens satisfy: 0 < R15 / R16 < 0.05.

[0046] In some embodiments, the radius of curvature R19 of the object side of the eighth lens and the radius of curvature R20 of the image side of the eighth lens satisfy: -5.0 < R19 / R20 < -0.5.

[0047] In some embodiments, the radius of curvature R21 of the object side of the ninth lens and the radius of curvature R22 of the image side of the ninth lens satisfy: 0.05 < R21 / R22 < 0.5.

[0048] Compared with the prior art, the optical lens provided by the present invention has at least the following beneficial effects:

[0049] (1) The optical lens provided by the present invention adopts a combination of nine conventional lenses and one liquid lens. By reasonably allocating the liquid lens and the focal length relationship of each lens, the optical lens has good imaging ability at different object distances and good thermal stability. At the same time, by reasonably configuring the thickness, spacing and surface shape of each lens, the optical lens has advantages such as small total length, high relative illumination, large image plane, high resolution and autofocus.

[0050] (2) The optical lens provided by the present invention expands the original fixed working distance industrial lens into an autofocus lens with an adjustable working distance within a certain range (working object distance is 100mm-400mm) by applying liquid lens to the optical path design, which greatly expands the application range of the optical lens and improves the detection efficiency of the optical lens.

[0051] (3) The optical lens provided by the present invention can adjust the focus position of the entire optical system in real time by controlling the driving voltage of the liquid lens, so as to achieve the purpose of fast focusing at different working distances and make the optical lens have high resolution at different object distances.

[0052] (4) The optical lens provided by the present invention uses liquid lens to achieve autofocus, and the lens does not shift during the focusing process, which makes the overall stability of the optical lens better. Attached Figure Description

[0053] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0054] Figure 1 This is a schematic diagram of the structure of an optical lens provided in the first embodiment of the present invention;

[0055] Figure 2 The distortion curve of the optical lens provided in the first embodiment of the present invention;

[0056] Figure 3 A transverse chromatic aberration curve of an optical lens provided in the first embodiment of the present invention;

[0057] Figure 4 The MTF curve of the optical lens provided in the first embodiment of the present invention;

[0058] Figure 5 A relative illumination curve of an optical lens provided in the first embodiment of the present invention;

[0059] Figure 6 This is a schematic diagram of the structure of an optical lens provided in the second embodiment of the present invention;

[0060] Figure 7The distortion curve of the optical lens provided in the second embodiment of the present invention;

[0061] Figure 8 A transverse chromatic aberration curve of an optical lens provided in the second embodiment of the present invention;

[0062] Figure 9 The MTF curve of the optical lens provided in the second embodiment of the present invention;

[0063] Figure 10 A relative illumination curve of an optical lens provided in the second embodiment of the present invention;

[0064] Figure 11 This is a schematic diagram of the structure of an optical lens provided in the third embodiment of the present invention;

[0065] Figure 12 The distortion curve of the optical lens provided in the third embodiment of the present invention;

[0066] Figure 13 A transverse chromatic aberration curve of an optical lens provided in the third embodiment of the present invention;

[0067] Figure 14 MTF curve of the optical lens provided in the third embodiment of the present invention;

[0068] Figure 15 A relative illumination curve of an optical lens provided in the third embodiment of the present invention;

[0069] Figure 16 This is a schematic diagram of the structure of the liquid lens in the optical lens provided by the present invention. Detailed Implementation

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] The present invention proposes an optical lens, which comprises, along the optical axis from the object side to the imaging plane, the following components in sequence: a first group, a liquid lens, and a second group.

[0078] The first group has positive optical power and includes a first lens, a second lens, a third lens and a fourth lens in sequence along the optical axis from the object side to the imaging surface; the liquid lens can present different focal lengths according to different applied voltages and has an aperture stop inside; the second group has positive optical power and includes a fifth lens, a sixth lens, a seventh lens, an eighth lens and a ninth lens in sequence along the optical axis from the object side to the imaging surface.

[0079] Specifically, the first lens has positive optical power, its object-side surface is convex, and its image-side surface is concave; the second lens has negative optical power, its object-side surface is convex, and its image-side surface is concave; the third lens has negative optical power, its object-side surface is convex, and its image-side surface is concave; the fourth lens has positive optical power, its object-side surface is convex, and its image-side surface is concave; the fifth lens has positive optical power, its object-side surface is either convex or concave, and its image-side surface is convex; the sixth lens has negative optical power, its object-side surface is concave, and its image-side surface is convex; the seventh lens has positive optical power, its object-side surface is either convex or concave, and its image-side surface is convex; the eighth lens has positive optical power, its object-side surface is convex, and its image-side surface is convex; and the ninth lens has negative optical power, its object-side surface is concave, and its image-side surface is convex.

[0080] In some embodiments, the third lens and the fourth lens form a cemented lens, and the fifth lens and the sixth lens form a cemented lens, which are used to share the chromatic aberration correction of the optical lens, improve the resolution of the optical lens, and at the same time make the structure of the optical lens compact, which is conducive to the miniaturization of the optical lens.

[0081] 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 second surface to narrow the range of light emitted from the forward optical system. The first, second, fourth, fifth, and sixth surfaces are all planar, while the third 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 third surface in the liquid lens will have a certain radius of curvature, and the liquid lens will have a corresponding focal length. Combined with other lens groups, 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 third 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.

[0082] In some implementations, when the working object distance OBJ of the optical lens satisfies: 100mm≤OBJ≤400mm, the driving voltage U applied to the liquid lens satisfies: 30.0V<U<50.0V, and the focal length fb of the liquid lens satisfies: |fb|>200mm. That is, when the optical lens works within a certain range of working object distances, the driving voltage applied to the liquid lens will be automatically adjusted within a certain range. At this time, the liquid lens will have a certain range of positive or negative optical power due to the corresponding change in the radius of curvature of the third surface. More preferably, when the working object distance OBJ of the optical lens satisfies: 100mm≤OBJ≤400mm, the driving voltage U applied to the liquid lens satisfies: 30.0V<U<50.0V, the radius of curvature R10 of the third surface in the liquid lens satisfies: R10∈(-∞, -15.5)&(13.7,+∞), and the focal length fb of the liquid lens satisfies: fb∈(-∞, -276)&(245,+∞). That is, at different working object distances (100mm≤OBJ≤400mm), by changing the driving voltage on the liquid lens (30.0V<U<50.0V), the radius of curvature of the liquid lens can be changed, thereby making the liquid lens present different focal lengths (|fb|>200mm), so that the optical lens has relatively clear imaging quality at different object distances, that is, to realize the fast autofocus function of the optical lens at different object distances.

[0083] In some implementations, the effective focal length fa of the first group and the effective focal length f of the optical lens satisfy the condition: 1.5 < fa / f < 7.0. Meeting this range, by appropriately setting the focal length ratio of the first group before the liquid lens, facilitates a smooth transition of light, allowing light to enter the aperture and liquid lens at a relatively gentle angle. This reduces the impact of the liquid lens on the system's sensitivity and relative illumination, ensuring high image quality at different working object distances.

[0084] In some implementations, the effective focal length fc of the second group and the effective focal length f of the optical lens satisfy the condition: 0.6 < fc / f < 1.6. By satisfying this range and appropriately setting the focal length ratio of the second group after the liquid lens, the aberrations caused by the first group and the liquid lens can be effectively corrected, enabling the optical lens to have better imaging quality at different working object distances.

[0085] In some implementations, the effective focal length fa of the first group and the effective focal length fc of the second group satisfy the condition: 2.0 < fa / fc < 7.0. By satisfying this range and appropriately setting the focal length ratio of the front and rear lens groups of the liquid lens, it is possible to pair it with a variable-focus liquid lens to quickly achieve automatic focusing of the system, ensuring that the lens can achieve high resolution at different working object distances.

[0086] In some embodiments, the effective focal length f1 of the first lens and the effective focal length f of the optical lens satisfy the following condition: 2.0 < f1 / f < 4.0; the radius of curvature R1 of the object side of the first lens and the radius of curvature R2 of the image side of the first lens satisfy the following condition: 0.1 < R1 / R2 < 0.4. By satisfying these ranges and rationally setting the optical power and surface shape of the first lens, the light entering the first lens can be effectively converged into the optical system, reducing the difficulty of aberration correction, ensuring the imaging quality of the optical lens, and simultaneously enabling the optical system to have a larger light throughput, thus improving the imaging illumination of the optical lens.

[0087] In some embodiments, the effective focal length f2 of the second lens and the effective focal length f of the optical lens satisfy the following condition: -2.0 < f2 / f < -0.5; the radius of curvature R3 of the object-side surface of the second lens and the radius of curvature R4 of the image-side surface of the second lens satisfy the following condition: 2.5 < R3 / R4 < 8.0. By satisfying the above ranges and reasonably setting the optical power and surface shape of the second lens, the aberrations caused by the positive refractive power of the first lens can be effectively balanced, thereby improving the imaging resolution of the optical lens.

[0088] In some embodiments, the effective focal length f3 of the third lens and the effective focal length f of the optical lens satisfy the condition: -1.2 < f3 / f < -0.2. Meeting this range allows the third lens to have a larger negative refractive power, which helps to accelerate the refraction of light and promotes the miniaturization of the optical lens structure.

[0089] In some embodiments, the effective focal length f4 of the fourth lens and the effective focal length f of the optical lens satisfy the following condition: 0.1 < f4 / f < 0.8; the radius of curvature R6 of the object side of the fourth lens and the radius of curvature R7 of the image side of the fourth lens satisfy the following condition: 0 < R6 / R7 < 0.5. By satisfying these ranges and setting the fourth lens to have a large positive refractive power, light can be effectively converged, allowing light to enter the aperture and liquid lens at a relatively gentle angle, reducing the influence of the liquid lens on the system's sensitivity and relative illumination, and ensuring high imaging quality at different working object distances.

[0090] In some implementations, the effective focal length f5 of the fifth lens and the effective focal length f of the optical lens satisfy the condition: 0.2 < f5 / f < 0.7. Meeting this range allows for a smoother light transition by appropriately setting the optical power of the fifth lens, balancing various aberrations generated by the preceding lenses and the liquid lens, and improving the imaging quality of the optical system.

[0091] In some embodiments, the effective focal length f6 of the sixth lens and the effective focal length f of the optical lens satisfy the following condition: -0.6 < f6 / f < -0.2; the radius of curvature R15 of the object side of the sixth lens and the radius of curvature R16 of the image side of the sixth lens satisfy the following condition: 0 < R15 / R16 < 0.05. By satisfying these ranges and appropriately setting the optical power and surface shape of the sixth lens, it can be paired with the fifth lens to reasonably correct the chromatic aberration of the system and improve the imaging quality of the optical system; furthermore, it can increase the light height emitted from the liquid lens, resulting in a larger image height.

[0092] In some implementations, the effective focal length f7 of the seventh lens and the effective focal length f of the optical lens satisfy the condition: 0.5 < f7 / f < 1.5. Meeting this range allows for a more efficient setting of the optical power of the seventh lens, which helps to further converge light rays, reduce the angle between the principal ray and the optical axis at the edge of the field of view, decrease the difficulty of aberration correction, and improve the imaging quality of the optical system.

[0093] In some embodiments, the effective focal length f8 of the eighth lens and the effective focal length f of the optical lens satisfy the following condition: 1.0 < f8 / f < 3.0; the radius of curvature R19 of the object side of the eighth lens and the radius of curvature R20 of the image side of the eighth lens satisfy the following condition: -5.0 < R19 / R20 < -0.5. By satisfying these ranges and appropriately setting the optical power and surface shape of the eighth lens, light convergence can be accelerated, thereby increasing the height of light focusing. This increases the photosensitive area of ​​the image plane and effectively improves the imaging quality of the optical system.

[0094] In some embodiments, the effective focal length f9 of the ninth lens and the effective focal length f of the optical lens satisfy the following condition: -3.5 < f9 / f < -1.5; the radius of curvature R21 of the object-side surface of the ninth lens and the radius of curvature R22 of the image-side surface of the ninth lens satisfy the following condition: 0.05 < R21 / R22 < 0.5. By satisfying these ranges and rationally setting the optical power and surface shape of the ninth lens, it is beneficial to increase the incident angle of light entering the image plane, thereby effectively improving the imaging quality of the optical system while achieving large target surface imaging.

[0095] In some implementations, the total optical length (TTL) of the optical lens and the effective focal length (f) of the optical lens satisfy the condition: 2.5 < TTL / f < 3.5. Meeting this range ensures both miniaturization and better convergence of light onto the imaging surface, which is beneficial for achieving a larger imaging area.

[0096] In some implementations, the image height IH corresponding to the maximum field of view of the optical lens and the effective focal length f of the optical lens satisfy the following condition: 1.1 < IH / f < 1.5. Satisfying the above range enables the optical lens to achieve its telephoto characteristics, allowing it to capture high-definition images even at relatively close working object distances, and also enables it to achieve its large image plane characteristics, presenting more image details and realizing high-pixel imaging.

[0097] In one implementation, the first, second, third, fourth, fifth, sixth, seventh, eighth, and ninth lenses can be made entirely of glass or a combination of glass and plastic; both methods achieve good imaging results. In this application, to improve the image quality of the lens, all lenses are made of glass.

[0098] 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.

[0099] First Embodiment

[0100] Please see Figure 1The diagram shows a schematic of the structure of an optical lens 100 provided in the first embodiment of the present invention. The optical lens 100 includes, along the optical axis from the object side to the imaging surface S27, 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, an eighth lens L8, a ninth lens L9, a filter G1, and a protective glass G2. The optical centers of each lens are located on the same straight line.

[0101] Among them, the first lens L1 has positive optical power, its object-side surface S1 is convex, and its image-side surface S2 is concave; the second lens L2 has negative optical power, its object-side surface S3 is convex, and its image-side surface S4 is concave; the third lens L3 has negative optical power, its object-side surface S5 is convex, and its image-side surface is concave; the fourth lens L4 has positive optical power, its object-side surface is convex, and its image-side surface S7 is concave, and the third lens L3 and the fourth lens L4 form a cemented lens with a cemented surface S6; the fifth lens L5 has positive optical power, its object-side surface S14 is convex, and its image-side surface is convex; the sixth lens L6 has... The sixth lens has negative optical power, with its object-side surface concave and its image-side surface S16 convex. The fifth lens L5 and the sixth lens L6 form a cemented lens with a cemented surface S15. The seventh lens L7 has positive optical power, with its object-side surface S17 concave and its image-side surface S18 convex. The eighth lens L8 has positive optical power, with its object-side surface S19 convex and its image-side surface S20 convex. The ninth lens L9 has negative optical power, with its object-side surface S21 concave and its image-side surface S22 convex. The object-side surface S23 and image-side surface S24 of the filter G1 are both flat. The object-side surface S25 and image-side surface S26 of the protective glass G2 are both flat.

[0102] Please see Figure 16 The diagram shows a schematic of a liquid lens E1 provided by the present invention. The liquid lens E1, from the object side to the imaging surface, includes a first surface S8, a second surface S9, a third surface S10, a fourth surface S11, a fifth surface S12, and a sixth surface S13. An aperture stop is located at the second surface S9. The first, second, and fourth surfaces S8, S9, S11, S12, and S13 are all planar. The third surface S10 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 100mm ≤ OBJ ≤ 400mm, the driving voltage U applied to the liquid lens satisfies 30.0V < U < 50.0V, and the focal length fb of the liquid lens satisfies |fb| > 200mm.

[0103] In this embodiment, when the working object distance OBJ of the optical lens satisfies 100mm≤OBJ≤400mm, the driving voltage U applied to the liquid lens satisfies 35.3V<U<45.8V. At this time, the radius of curvature R10 of the third surface satisfies R10∈(-∞,-15.5)&(13.7,+∞), and the focal length fb of the liquid lens satisfies fb∈(-∞,-276)&(245,+∞). More specifically, when the optical lens is in the optimal working object distance state, a certain starting voltage is applied to the liquid lens, the radius of curvature of the third surface in the liquid lens is -53.6mm, and the focal length of the liquid lens is -956.3mm.

[0104] The relevant parameters of each lens element of the optical lens 100 provided in this embodiment are shown in Table 1.

[0105] Table 1

[0106]

[0107]

[0108] Figure 2 The distortion curve of 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 field-of-view angle (unit: °). As can be seen from the figure, the distortion value is controlled within -4%, indicating that the optical lens can correct distortion very well.

[0109] Figure 3 The modulation transfer function (MTF) curve of 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 0.43 throughout the entire field of view. In the range of 0 to 99 lp / mm, the MTF curve decreases smoothly and evenly from the center to the edge of the field of view, exhibiting good imaging quality and good detail resolution at both low and high frequencies.

[0110] Figure 4 The diagram shows the transverse chromatic aberration curves of this embodiment, representing the chromatic aberration of each wavelength relative to the center wavelength (0.57 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 ±3.5 μm, indicating that this optical lens can excellently correct chromatic aberration at the edge of the field of view and the secondary spectrum of the entire image plane.

[0111] Figure 5The relative illumination curve of this embodiment is shown, which represents the relative illumination value (unit: %) at different image heights on the imaging plane. The horizontal axis represents the image height (unit: mm), and the vertical axis represents the relative illumination value. As can be seen from the figure, the relative illumination value of the optical lens is still greater than 65% at the maximum half-image height, indicating that the optical lens has good relative illumination.

[0112] Second Embodiment

[0113] Please see Figure 6 The diagram shows a schematic of the structure of an 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 differences are: the curvature radius, thickness, spacing between lenses, and materials of each lens are different. When the working object distance OBJ of the optical lens satisfies: 100mm≤OBJ≤400mm, the driving voltage U applied to the liquid lens satisfies: 35.3V<U<45.6V. At this time, the curvature radius R10 of the third surface of the liquid lens satisfies: R10∈(-∞,-15.5)&(14.4,+∞), and the focal length fb of the liquid lens satisfies: fb∈(-∞,-278)&(258,+∞). More specifically, when the optical lens is in the optimal working object distance state, a certain starting voltage is applied to the liquid lens, the curvature radius of the third surface in the liquid lens is -52.9mm, and the focal length of the liquid lens is -944.5mm.

[0114] The relevant parameters of each lens element of the optical lens 200 provided in this embodiment are shown in Table 2.

[0115] Table 2

[0116]

[0117] Figures 7 to 10 The distortion curve, MTF curve, lateral chromatic aberration curve, and relative illuminance curve of this embodiment are shown respectively. From Figure 7 As can be seen, the distortion value is controlled within -4%, indicating that the optical lens can correct distortion very well; from Figure 8 As can be seen, the MTF value is above 0.43 throughout the entire field of view. Within the range of 0–99 lp / mm, the MTF curve decreases smoothly and evenly from the center to the edge of the field of view, demonstrating good image quality and detail resolution at both low and high frequencies. Figure 9 As can be seen, the transverse chromatic aberration of the longest and shortest wavelengths is controlled within ±3.5μm, indicating that the optical lens can excellently correct chromatic aberration at the edges of the field of view and the second-order spectrum of the entire image plane; from Figure 10As can be seen, the relative illumination value of the optical lens is still greater than 65% at the maximum half-image height, indicating that the optical lens has good relative illumination.

[0118] Third Embodiment

[0119] Please see Figure 11 The diagram shows a schematic of the structure of an optical lens 300 provided in the third embodiment of the present invention. This optical lens 300 has a structure largely the same as the optical lens 100 in the first embodiment, with the main differences being: the object-side surface of the fifth lens is concave, the object-side surface of the seventh lens is convex, and the radius of curvature, thickness, spacing, and material of each lens are different. Furthermore, when the working object distance OBJ of the optical lens satisfies: 100mm ≤ OBJ ≤ 400mm, the driving voltage U applied to the liquid lens satisfies... When the voltage is 35.7V < U < 45.1V, the radius of curvature R10 of the third surface satisfies: R10∈(-∞,-16.8)&(16.1,+∞), and the focal length fb of the liquid lens satisfies: fb∈(-∞,-300)&(288,+∞). More specifically, when the optical lens is in the optimal working object distance state, after applying a certain starting voltage to the liquid lens, the radius of curvature of the third surface in the liquid lens is -55.4mm, and the focal length of the liquid lens is -989.0mm.

[0120] The relevant parameters of each lens element of the optical lens 300 provided in this embodiment are shown in Table 3.

[0121] Table 3

[0122]

[0123]

[0124] Figures 12 to 15 The distortion curve, MTF curve, lateral chromatic aberration curve, and relative illuminance curve of this embodiment are shown respectively. From Figure 12 As can be seen, the distortion value is controlled within -4%, indicating that the optical lens can correct distortion very well; from Figure 13 As can be seen, the MTF value is above 0.46 throughout the entire field of view. Within the range of 0–99 lp / mm, the MTF curve decreases smoothly and evenly from the center to the edge of the field of view, demonstrating good image quality and detail resolution at both low and high frequencies. Figure 14 As can be seen, the transverse chromatic aberration of the longest and shortest wavelengths is controlled within ±3.5μm, indicating that the optical lens can excellently correct chromatic aberration at the edges of the field of view and the second-order spectrum of the entire image plane; from Figure 15 As can be seen, the relative illumination value of the optical lens is still greater than 65% at the maximum half-image height, indicating that the optical lens has good relative illumination.

[0125] Please refer to Table 4, which shows the optical characteristics of the optical lenses provided in the three embodiments above, including the total optical length TTL, aperture value Fno, effective focal length f, maximum field of view FOV, image height IH corresponding to the maximum field of view, working object distance OBJ, driving voltage U of the liquid lens, and effective focal length fb of the liquid lens. It also includes the relevant values ​​corresponding to each condition in the above conditional expressions.

[0126] Table 4

[0127]

[0128]

[0129] In summary, the optical lens provided by this invention has at least the following advantages:

[0130] (1) The optical lens provided by the present invention adopts a combination of nine glass lenses and one liquid lens. By reasonably allocating the liquid lens and the focal length relationship of each lens, the optical lens has good imaging ability at different object distances and good thermal stability. At the same time, by reasonably configuring the thickness of each lens, the spacing between each lens and the surface shape of each lens, the optical lens has advantages such as small total length, high relative illumination, large image plane, high resolution and autofocus.

[0131] (2) The optical lens provided by the present invention expands the original fixed working distance focusing industrial lens into an autofocus lens with an adjustable working distance within a certain range (working object distance is 100mm-400mm) by applying liquid lens to the optical path design, which greatly expands the application range of the optical lens and improves the detection efficiency of the optical lens.

[0132] (3) The optical lens provided by the present invention can adjust the focus position of the entire optical system in real time by controlling the driving voltage of the liquid lens, so as to achieve the purpose of fast focusing at different working distances and make the optical lens have high resolution at different object distances.

[0133] (4) The optical lens provided by the present invention uses liquid lens to achieve autofocus, and the lens does not shift during the focusing process, which makes the overall stability of the optical lens better.

[0134] 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.

[0135] 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 nine lenses and one liquid lens, characterized in that, Along the optical axis from the object side to the imaging plane, the following are included in sequence: A first group having positive optical power, the first group comprising, from the object side to the imaging plane, a first lens having positive optical power, a second lens having negative optical power, a third lens having negative optical power, and a fourth lens having positive optical power; A liquid lens with optical power, wherein the liquid lens exhibits different focal lengths depending on the applied voltage; A second group having positive optical power, the second group comprising, from the object side to the imaging plane, a fifth lens having positive optical power, a sixth lens having negative optical power, a seventh lens having positive optical power, an eighth lens having positive optical power, and a ninth lens having negative optical power. Wherein, the effective focal length fa of the first group and the effective focal length fc of the second group satisfy: 2.0 < fa / fc < 7.0; The total optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy the condition: 2.5 < TTL / f < 3.

5.

2. The optical lens according to claim 1, characterized in that, The effective focal length f1 of the first lens and the effective focal length f of the optical lens satisfy: 2.0 < f1 / f < 4.

0.

3. The optical lens according to claim 1, characterized in that, The effective focal length f2 of the second lens and the effective focal length f of the optical lens satisfy: -2.0 < f2 / f < -0.

5.

4. The optical lens according to claim 1, characterized in that, The effective focal length f3 of the third lens and the effective focal length f of the optical lens satisfy the condition: -1.2 < f3 / f < -0.

2.

5. The optical lens according to claim 1, characterized in that, The effective focal length f4 of the fourth lens and the effective focal length f of the optical lens satisfy the condition: 0.1 < f4 / f < 0.

8.

6. The optical lens according to claim 1, characterized in that, The effective focal length f5 of the fifth lens and the effective focal length f of the optical lens satisfy the condition: 0.2 < f5 / f < 0.

7.

7. The optical lens according to claim 1, characterized in that, The effective focal length f6 of the sixth lens and the effective focal length f of the optical lens satisfy the condition: -0.6 < f6 / f < -0.

2.

8. The optical lens according to claim 1, characterized in that, The effective focal length f7 of the seventh lens and the effective focal length f of the optical lens satisfy the condition: 0.5 < f7 / f < 1.

5.

9. The optical lens according to claim 1, characterized in that, The effective focal length f8 of the eighth lens and the effective focal length f of the optical lens satisfy the condition: 1.0 < f8 / f < 3.

0.

10. The optical lens according to claim 1, characterized in that, The effective focal length f9 of the ninth lens and the effective focal length f of the optical lens satisfy the condition: -3.5 < f9 / f < -1.

5.

11. The optical lens according to claim 1, characterized in that, The optical lens satisfies one or more of the following characteristics; The effective focal length fa of the first group and the effective focal length fc of the second group satisfy: 2.232≤fa / fc≤5.413; The total optical length TTL of the optical lens and the effective focal length f of the optical lens satisfy: TTL / f = 2.988; The object-side surface of the first lens is convex, and the image-side surface of the first lens is concave. The object-side surface of the second lens is convex, and the image-side surface of the second lens is concave. The object-side surface of the third lens is convex, and the image-side surface of the third lens is concave. The object-side surface of the fourth lens is convex, and the image-side surface of the fourth lens is concave. The object-side surface of the fifth lens is either convex or concave, and the image-side surface of the fifth lens is convex. The object-side surface of the sixth lens is concave, and the image-side surface of the sixth lens is convex. The object-side surface of the seventh lens is either convex or concave, and the image-side surface of the seventh lens is convex. The object-side surface of the eighth lens is convex, and the image-side surface of the eighth lens is also convex. The object-side surface of the ninth lens is concave, and the image-side surface of the ninth lens is convex.

12. The optical lens according to claim 1, characterized in that, The image height IH corresponding to the maximum field of view of the optical lens and the effective focal length f of the optical lens satisfy the following: 1.1 < IH / f < 1.5.

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