Rapid focusing industrial lens structure, industrial lens, control system and industrial visual inspection device

Abstract

The utility model relates to a machine vision and industrial detection technology, in particular to a rapid focusing industrial lens structure, an industrial lens, a control system and an industrial vision detection device, wherein the rapid focusing industrial lens structure adopts an electrowetting liquid lens to realize millisecond-level automatic focusing. A fast focusing industrial lens structure is composed of eight glass lenses and an electric control liquid lens, and the nominal value of the optical focal length is 35 mm. Within the object distance range of 225-600mm, the liquid lens realizes millisecond-level automatic focusing by adjusting the curvature of a liquid interface, and the optical back focal length and the mechanical back focal length are kept unchanged. Through actual measurement, the absolute value of lens distortion is less than or equal to 2%, the curvature of field is less than or equal to + / -0.2 mm, the full-field relative illumination is greater than or equal to 95%, and the high-resolution imaging requirements of industrial vision, automatic detection and robot precise positioning scenes can be met.

Description

Rapidly focusing industrial lens structure, industrial lenses, control systems, and industrial vision inspection devices Technical Field

[0001] This utility model relates to machine vision and industrial inspection technology, specifically a fast-focusing industrial lens structure, industrial lens, control system, and industrial vision inspection device that uses an electrowetting liquid lens to achieve millisecond-level automatic focusing. Background Technology

[0002] In scenarios such as automated production lines, precision assembly, and surface defect inspection, the focusing speed and image quality of imaging lenses directly affect inspection efficiency and accuracy. Fixed-focus lenses cannot accommodate different working distances, while mechanical zoom lenses require moving lens groups, resulting in large size, complex structure, slow response, and susceptibility to wear.

[0003] The published patent CN104391345B discloses an electrowetting variable focus liquid lens containing a gradient refractive index material, and proposes an automatic zoom scheme for a single electrowetting liquid lens. However, it relies solely on the liquid interface for imaging, resulting in large aberrations, a narrow field of view, and limited light throughput, making it difficult to meet the needs of industrial-grade high-resolution, large-target-area imaging.

[0004] To address the aforementioned shortcomings, there is an urgent need for an integrated design structure that combines liquid lenses with a multi-glass optical system, enabling fast, stable, and closed-loop focal length control through a high-voltage drive circuit, while maintaining high resolution and low distortion. Summary of the Invention

[0005] The purpose of this invention is to provide a fast-focusing industrial lens structure, industrial lens, control system, and industrial vision inspection device to address the shortcomings of existing technologies, aiming to achieve fast, stable, closed-loop focal length control while maintaining high resolution and low distortion.

[0006] This utility model achieves the above-mentioned objective through the following technical solution: a fast-focusing industrial lens structure, characterized in that the industrial lens comprises, from the object side to the image side along the optical axis, the following components in sequence:

[0007] First biconvex lens;

[0008] The first cemented lens is formed by cementing a cemented front biconvex lens and a cemented front biconcave lens together.

[0009] A liquid lens with an internal annular flange forming an aperture structure;

[0010] The second cemented lens is formed by cementing a cemented biconcave lens and a cemented biconvex lens together.

[0011] Second biconvex lens;

[0012] Negative meniscus lens; and

[0013] Protective glass plate;

[0014] The liquid lens is used to adjust the curvature of the liquid interface inside the liquid lens by changing the input voltage through an external control system, thereby adjusting the equivalent focal length of the lens. This enables automatic focusing within an object distance range of 225mm-600mm without moving any solid lens, while maintaining both the optical and mechanical back focal lengths.

[0015] Furthermore, the first biconvex lens, the pre-cemented biconvex lens, and the post-cemented biconvex lens are all made of heavy lanthanum flint glass with a refractive index nd>1.8 and a dispersion coefficient Vd<45.

[0016] The negative meniscus lens is made of light crown glass with a refractive index nd < 1.5 and a dispersion coefficient Vd > 45.

[0017] Furthermore, the protective glass sheet is made of transparent crown glass and has an anti-reflective coating on its image-side surface.

[0018] Furthermore, the radius of curvature of the liquid lens is +32.86 mm at an object distance of 225 mm and -41.33 mm at an object distance of 600 mm.

[0019] The driving voltage range of the liquid lens module is 0–70V.

[0020] An industrial lens, comprising the fast-focusing industrial lens structure described in any one of the foregoing embodiments, further comprising:

[0021] The lens barrel is used to position the first biconvex lens, the first cemented lens, the second cemented lens, the second biconvex lens, and the negative meniscus lens on the same optical axis.

[0022] Furthermore, the nominal focal length of this industrial lens is 35mm;

[0023] The distortion of this industrial lens is controlled within ±2% in the 450–650nm wavelength band;

[0024] The field curvature of this industrial lens is controlled within ±0.2mm, and the relative illuminance across the entire field of view is not less than 95%.

[0025] A control system for driving a liquid lens assembly includes a control module, the control module comprising:

[0026] The microcontroller is used to calculate the driving voltage based on the target distance or image feedback data;

[0027] Digital-to-analog converter for outputting low-voltage analog voltage;

[0028] High-voltage amplifiers are used to amplify low-voltage analog voltages to the adjustable high voltages required for the operation of liquid lenses; and

[0029] The output port is electrically connected to the opposing electrode of the liquid lens via a flexible ribbon cable;

[0030] The liquid lens assembly is a liquid lens of any of the industrial lens structures described above.

[0031] Furthermore, it also includes a distance measurement module, the output of which is connected to the microcontroller signal to provide target distance data.

[0032] Furthermore, the microcontroller incorporates an image sharpness evaluation algorithm to calculate image contrast in real time and fine-tune the drive voltage to form a closed-loop autofocus.

[0033] The output voltage range of the high-voltage amplifier is 30 volts to 70 volts.

[0034] An industrial vision inspection device includes an industrial lens and a control system;

[0035] The industrial lens, from the object side to the image side along the optical axis, comprises:

[0036] First biconvex lens;

[0037] The first cemented lens is formed by cementing a cemented front biconvex lens and a cemented front biconcave lens together.

[0038] A liquid lens with an internal annular flange forming an aperture structure;

[0039] The second cemented lens is formed by cementing a cemented biconcave lens and a cemented biconvex lens together.

[0040] Second biconvex lens;

[0041] Negative meniscus lens; and

[0042] Protective glass plate;

[0043] The industrial lens further includes: a lens barrel for positioning the first biconvex lens, the first cemented lens, the second cemented lens, the second biconvex lens, and the negative meniscus lens on the same optical axis;

[0044] The control system is electrically connected to the liquid lens to enable the industrial lens to quickly and automatically focus and image dynamic targets.

[0045] The beneficial effects of this utility model are:

[0046] 1. Fast focusing: The liquid lens can complete the travel of several centimeters of a traditional lens with a tiny deformation, achieving millisecond-level focusing without any mechanical moving parts.

[0047] 2. Compact size: By eliminating the guide rail and drive mechanism, the lens module size can be reduced by about 60%, making it suitable for space-constrained devices.

[0048] 3. Excellent optical performance: Through the optimized design of eight glass lenses + liquid lenses, the field curvature is ≤ ±0.2mm, the distortion is ≤ ±2%, the relative illumination is ≥95%, and the imaging remains clear even at multiple object distances.

[0049] 4. Long lifespan and high reliability: No frictional wear parts, theoretical lifespan up to 10 years. 8 More than once; it maintains a stable focus even under vibration.

[0050] 5. Low power consumption: Liquid lenses consume very low current only during focusing, and the overall power consumption is significantly lower than that of mechanical lenses. Attached Figure Description

[0051] Figure 1 is a schematic diagram of the structure of the liquid lens of this utility model.

[0052] Figure 2 is a schematic diagram of the exploded layout of the fast-focusing industrial lens structure of this utility model.

[0053] Figure 3 shows the focused spot size of this industrial lens at an object distance of 225mm.

[0054] Figure 4 shows the focused spot size of this industrial lens at an object distance of 350mm.

[0055] Figure 5 shows the focused spot size of this industrial lens at an object distance of 600mm.

[0056] Figure 6 shows the astigmatism and distortion curves at an object distance of 225 mm.

[0057] Figure 7 shows the astigmatism and distortion curves at an object distance of 350 mm.

[0058] Figure 8 shows the astigmatism and distortion curves at an object distance of 600 mm.

[0059] Figure 9 shows the relative illumination curve of this industrial lens at an object distance of 225mm.

[0060] Figure 10 shows the relative illumination curve of this industrial lens at an object distance of 350mm.

[0061] Figure 11 shows the relative illumination curve of this industrial lens at an object distance of 600mm. Detailed Implementation

[0062] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present utility model, and not all of them. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present utility model. It is understood that the accompanying drawings are provided for reference and illustration only, and are not intended to limit the present utility model. The connection relationships shown in the drawings are only for clear description and do not limit the connection method.

[0063] As shown in Figures 1 to 11, this utility model relates to a fast-focusing industrial lens structure based on a liquid lens, an industrial lens, a control system for driving the liquid lens assembly, and an industrial vision inspection device. It is suitable for industrial vision inspection, automated image acquisition and other scenarios, and has the advantages of compact structure, fast focusing and clear imaging.

[0064] A fast-focusing industrial lens structure, characterized in that the industrial lens comprises, from the object side (the side of the object to be measured) to the image side (the side of the camera sensor) along the optical axis, the following components in sequence: a first biconvex lens; a first cemented lens; a liquid lens with an internal annular flange forming an aperture structure; a second cemented lens; a second biconvex lens; a negative meniscus lens; and a protective glass sheet;

[0065] The first cemented lens is formed by cementing a cemented front biconvex lens and a cemented front biconcave lens together.

[0066] The second cemented lens is formed by cementing a cemented biconcave lens and a cemented biconvex lens together.

[0067] The liquid lens is used to adjust the curvature of the liquid interface inside the liquid lens by changing the input voltage through an external control system, thereby adjusting the equivalent focal length of the lens. This enables automatic focusing within an object distance range of 225mm-600mm without moving any solid lens, while maintaining both the optical and mechanical back focal lengths.

[0068] This invention introduces an electrowetting liquid lens into a traditional glass optical system and optimizes the sequence and parameters of each lens stage. This allows the lens to autofocus within a wide object distance range of 225mm to 600mm using millisecond-level curvature adjustment of the liquid lens, while all solid lenses remain stationary throughout the process. This "electronically controlled focal length - fixed back focus" design completely eliminates mechanical focusing mechanisms such as stepper motors and slide rails. It eliminates the risk of defocusing caused by wear and vibration, and reduces the focusing response time from hundreds of milliseconds for mechanical drives to several milliseconds for electrowetting drives, significantly improving the shooting speed and reliability of automated production lines.

[0069] To ensure image quality under rapid focusing conditions, the lens incorporates a first biconvex lens and a first cemented lens before the liquid lens. These two lenses, working in conjunction with each other's positive and negative refractive forces, perform primary convergence of the object-side principal ray and simultaneously correct axial spherical aberration and chromatic aberration. The annular flange inside the liquid lens serves as an aperture stop, cutting off light at its narrowest point, reducing stray light, and providing ample aperture for subsequent lens elements. Following the liquid lens, a second cemented lens, a second biconvex lens, and a negative meniscus lens are sequentially arranged to perform secondary achromatic correction, control field curvature, and suppress distortion. After complete optical path distribution, the distortion of the imaging system is compressed to within ±2% across the entire field of view, the field curvature is controlled within ±0.2mm, and the relative illumination remains above 95%. This ensures high-speed focusing while still outputting high-resolution, low-distortion, and uniformly bright images.

[0070] Furthermore, the liquid lens is less than 3mm thick and also functions as an aperture stop, eliminating the need for a separate mechanical aperture. All solid lenses are assembled at fixed intervals, eliminating moving focusing components; assembly is completed with a one-time gluing or threaded fastening of the lens barrel structure. Thanks to this compact layout, the overall length and weight of the lens are reduced by approximately 60% and 50% respectively compared to mechanical zoom lenses of the same focal length, facilitating integration into space-constrained high-speed inspection modules or collaborative robot end effects. During focusing, only the liquid lens draws power momentarily, resulting in virtually zero static power consumption, making it ideal for extended online operation.

[0071] In summary, this solution, through its overall design of "electronically controlled liquid lens + multi-glass lens collaborative correction," overcomes the shortcomings of large aberrations and limited light transmission of a single liquid lens, and completely replaces the traditional mechanical focusing mechanism. It achieves high-speed, wear-free, miniaturized autofocus, and maintains industrial-grade high resolution, low distortion, and high illumination imaging quality under various object distance conditions, significantly improving the efficiency and stability of automated inspection and precision assembly scenarios.

[0072] Specifically:

[0073] Figure 1 shows a schematic diagram of the liquid lens used in this invention. A liquid lens is a special optical element that uses changes in the shape of a liquid interface to adjust the focal length. By applying voltage to change its surface curvature, it achieves rapid automatic focusing. This embodiment uses an electrically controlled liquid lens, which features fast response speed, small size, and simple structure.

[0074] Figure 2 shows an exploded view of the layout of the fast-focusing industrial lens structure of this utility model. Arranged sequentially along the optical axis, it includes lenses 1-7, corresponding to a first biconvex lens, a cemented front biconvex lens, a cemented front biconcave lens, a cemented rear biconcave lens, a cemented rear biconvex lens, a second biconvex lens, and a negative meniscus lens, respectively. It also includes a liquid lens, a protective glass sheet, and an image sensor. Wherein:

[0075] A cemented pre-convex lens and a cemented pre-concave lens are cemented together to form a first cemented lens.

[0076] A cemented biconcave lens and a cemented biconvex lens are cemented together to form a second cemented lens.

[0077] A liquid lens is disposed between the first cemented lens and the second cemented lens;

[0078] The protective glass plate serves as a filter, and the image sensor acts as a detector. By controlling the liquid lens to change the focal length, the focal point of the entire lens system is adjusted.

[0079] Figures 3 to 5 show the focused spot size of this industrial lens at different object distances (225mm, 350mm, and 600mm). As can be seen from the figures, a small spot size can be formed under all object distance conditions, indicating that the liquid lens has excellent focusing performance and can achieve high-precision focusing at different working distances with high image clarity. This fully verifies the optical effectiveness of the structure of this utility model.

[0080] Figures 6 to 8 show the astigmatism and distortion curves at object distances of 225mm, 350mm, and 600mm, respectively. The left image in each set is the field curvature curve, and the right image is the distortion curve. The figures show that the field curvature values ​​are all controlled within ±0.2mm, indicating effective field curvature correction; the distortion values ​​are all controlled within ±2%, indicating good image distortion control, low imaging distortion, and high image fidelity.

[0081] Figures 9 to 11 show the relative illumination curves of the lens at different object distances (225mm, 350mm, and 600mm). The results show that the relative illumination is greater than 95% at each working distance, indicating that the lens has good illumination uniformity across the entire field of view, with no obvious vignetting and uniform image brightness distribution, which is beneficial for improving image quality and the stability of subsequent image processing.

[0082] In summary, as can be seen from the specific embodiments described above, the fast-focusing industrial lens structure based on liquid lenses proposed in this utility model can achieve fast and accurate focusing at multiple object distances, and has good imaging clarity, distortion control capability, and illumination uniformity. It is suitable for industrial application scenarios with high requirements for image quality.

[0083] In detail:

[0084] This design presents an industrial lens with a focal length of 35mm, utilizing a liquid lens for focusing. Without altering the lens's optical or mechanical back focus, the lens refocuses onto the camera's optical sensor surface by voltage-driven changes in the radius of curvature of the liquid lens, regardless of the object's distance. Due to the absence of mechanical structures, it achieves rapid focusing and boasts a lifespan of hundreds of millions of repetitions.

[0085] This solution is a liquid focusing industrial lens, which consists of eight glass lenses and one liquid lens. Referring to Figure 2, the eight glass lenses are: a first biconvex lens 1, a pre-cemented biconvex lens 2, a pre-cemented biconcave lens 3, a post-cemented biconcave lens 4, a post-cemented biconvex lens 5, a second biconvex lens 6, a negative meniscus lens 7, and a protective glass sheet 8. The liquid lens 100 performs the focusing function. From object to image, the lens consists of: a first biconvex lens; a first cemented doublet lens (composed of a pre-cemented biconvex lens and a pre-cemented biconcave lens); the liquid lens 100; a second cemented doublet lens (composed of a post-cemented biconcave lens and a biconvex lens); a second biconvex lens; a negative meniscus lens; and a protective glass lens. The lens stop is placed inside the liquid lens and is served by a structural component inside the liquid lens. The protective glass plate 8 is a filter, and a detector 9 is located on one side of it.

[0086] See Figure 2:

[0087] The first biconvex lens 1 is the first lens, made of heavy lanthanum flint glass, with a refractive index nd>1.8 and a dispersion coefficient Vd<45;

[0088] The cemented biconvex lens 2, serving as the second lens, is made of flint glass with a refractive index nd > 1.55 and a dispersion coefficient Vd < 45.

[0089] The cemented biconcave lens 3, serving as the third lens, is made of heavy lanthanum flint glass with a refractive index nd > 1.8 and a dispersion coefficient Vd > 35.

[0090] The cemented biconcave lens 4 is the fourth lens, made of heavy flint glass with a refractive index nd>1.7 and a dispersion coefficient Vd>35;

[0091] After cementation, the biconvex lens 5 is the fifth lens, made of lanthanum flint glass with a refractive index nd>1.7 and a dispersion coefficient Vd<30;

[0092] The second biconvex lens 6, which is the sixth lens, is made of heavy lanthanum flint glass with a refractive index nd>1.75 and a dispersion coefficient Vd>45.

[0093] Negative meniscus lens 7, the seventh lens, is made of light crown glass with a refractive index nd < 1.5 and a dispersion coefficient Vd > 45.

[0094] The protective glass lens 8, i.e. the filter, is the eighth lens. It is made of crown glass with a refractive index nd>1.2 and a dispersion coefficient Vd>45.

[0095] See Table 1 below for details:

[0096] Surface curvature radius / mm, thickness / mm, refractive index, dispersive surface, inf 35 0.00 14 8.89 4.27 1.88 40.85 2 -16 5.46 2.00 31 5.5 25.5 0 1.60 39.2 24 -3 5.1 3 1.5 0 1.83 37.2 15 1 1.2 7 2.00 6 inf 1.50 7 inf 0.80 1.52 5 4.5 8 inf 1.9 6 1.4 3 4.4 9 R 0.5 9 1.5 3 4.4 10 inf 0.1 3 1.5 5 6. 411inf 0.55 1.525 4.512inf 2.0013 -16.38 1.50 1.722 9.501412.03 4.46 1.744 9.2215 -17.45 8.51162 8.59 4.97 1.8046.5817 -43.48 8.9718 -16.34 1.50 1.497 0.4419 -76.3710.0020inf 0.70 1.525 8.6421inf 0.70 Image plane inf surface

[0097] Table 1 lists the corresponding radius of curvature, thickness, refractive index, and dispersion value in millimeters and dimensionless form to ensure that the imaging system meets industrial-grade resolution requirements.

[0098] The parameters of the liquid lens corresponding to different object distances are detailed in Table 2 below:

[0099] Object distance, liquid lens curvature radius R / mm, first liquid thickness D1 / mm, second liquid thickness D2 / mm, 225mm, 32.86, 1.82, 7.22, 350mm, Inf, 1.96, 5.85, 600mm, -4, 1.33, 2.07, 4.76 surface

[0100] Table 2 data illustrates that as the object distance increases, the radius of curvature of the liquid lens adjusts, achieving dynamic focal length adaptation. Without moving optical elements, significant focal length changes are achieved through minute deformation, resulting in a compact system with rapid response.

[0101] This plan:

[0102] By embedding an electrowetting liquid lens into an eight-element glass optical system, millisecond-level mechanical focusing is achieved, fundamentally eliminating the wear and vibration problems caused by stepper motors and drive screws. An integrated annular flange diaphragm replaces the traditional iris, reducing the overall lens length by 60% and weight by nearly half, significantly reducing the load on the robot and gripping mechanism. A three-section lens barrel with positioning pins ensures coaxiality error does not exceed five micrometers, maintaining stable imaging even in high-speed vibration environments. The control system, through dual feedback from ranging and image, completes closed-loop autofocus in just three milliseconds, increasing the detection cycle time by more than 15 times compared to traditional mechanical zoom. The liquid lens exhibits no contact wear, with a focusing life exceeding 100 million cycles; a temperature compensation algorithm ensures focal length drift of less than 1% within a temperature range of -10°C to 60°C, meeting the requirements for outdoor and high / low temperature production line applications. In terms of optical performance, the center and edge modulation transfer functions at various object distances are both above 0.45, distortion is less than 2%, and edge illumination remains above 95%, accommodating both high-resolution measurement and defect detection. In summary, this lens combines advantages in speed, accuracy, lifespan, and size, which can significantly improve the inspection efficiency of industrial vision systems and reduce maintenance costs.

[0103] The liquid lens consists of two immiscible transparent liquids (dielectric and conductive liquids) encapsulated within a miniature glass cavity. The liquid interface is naturally spherical when there is no voltage. When an external control system applies a variable voltage of 0–70V, the conductive liquid changes its contact angle with the electrode layer due to the electrowetting effect, driving the curvature of the liquid interface to be smoothly adjustable between positive, zero, and negative, thereby changing the equivalent focal length.

[0104] The focusing process is as follows: First, the camera or host computer determines the target distance based on laser ranging, depth algorithms, or preset object distance; second, the control algorithm calculates the required voltage V by looking up a table or interpolating. t Subsequently, the high-voltage drive module boosts the voltage to V in milliseconds. t The liquid interface instantly undergoes a curvature change, shifting the focal point of the principal ray to the detector's focal plane. Finally, closed-loop fine-tuning can be performed using image contrast or phase detection to achieve optimal sharpness. Throughout the process, the eight glass lenses remain stationary, ensuring stable optical and mechanical back focal lengths.

[0105] The first biconvex lens and the first cemented lens perform primary convergence and on-axis aberration correction for the object beam; the internal annular flange (aperture stop) is located at the narrowest point of the liquid lens cavity to suppress stray light and ensure edge illumination; the second cemented lens, the second biconvex lens, and the negative meniscus lens further correct astigmatism, field curvature, and distortion. Since the liquid lens only changes the focal length without changing the distance between the glass lenses, the system aberration margin is always within the design controllable range.

[0106] Tests showed that within an object distance range of 225mm-600mm, the curvature of the liquid lens could cover the entire focusing stroke by continuously varying from +32.86mm to -41.33mm; at the zero curvature point (350mm object distance), the interface tended to be planar, and the system aberrations reached a minimum, which is the factory calibration reference surface.

[0107] Through the aforementioned electrowetting drive and multi-lens collaborative correction, this lens achieves the fusion of millisecond-level mechanical wear-free focusing, miniaturized lens barrel structure, and industrial-grade high-quality imaging.

[0108] In the specification and claims of this application, the terms "comprising / including" and "having / including" and variations thereof are used to specify the presence of the stated features, values, steps or components, but do not exclude the presence or addition of one or more other features, values, steps, components or combinations thereof.

[0109] Some features of this invention are described in different embodiments for clarity; however, these features may also be described in combination in a single embodiment. Conversely, some features of this invention are described only in a single embodiment for brevity; however, these features may also be described individually or in any suitable combination in different embodiments.

[0110] Finally, it should be noted that any cross-referencing or superposition of the various embodiments of this solution by those skilled in the art still falls within the original disclosure scope of this solution. Furthermore, the above descriptions are merely preferred embodiments of this utility model and are not intended to limit this utility model. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A fast-focusing industrial lens structure, characterized in that, The fast-focusing industrial lens structure, from the object side to the image side along the optical axis, includes: a first biconvex lens; a first cemented lens, formed by cementing a pre-cemented biconvex lens and a pre-cemented biconcave lens; a liquid lens with an internal aperture structure; a second cemented lens, formed by cementing a post-cemented biconcave lens and a post-cemented biconvex lens; a second biconvex lens; a negative meniscus lens; and a protective glass sheet; wherein the liquid lens is used to adjust the curvature of the liquid interface inside the liquid lens by changing the input voltage.

2. The fast-focusing industrial lens structure according to claim 1, characterized in that, The first biconvex lens, the pre-cemented biconvex lens, and the post-cemented biconvex lens are all made of heavy lanthanum flint glass with a refractive index nd>1.8 and a dispersion coefficient Vd<45; the negative meniscus lens is made of light crown glass with a refractive index nd<1.5 and a dispersion coefficient Vd>45.

3. The fast-focusing industrial lens structure according to claim 1, characterized in that, The protective glass sheet is made of transparent crown glass and has an anti-reflective coating on its image-side surface.

4. The fast-focusing industrial lens structure according to claim 1, characterized in that, The liquid lens has a radius of curvature of +32.86 mm at an object distance of 225 mm and a radius of curvature of -41.33 mm at an object distance of 600 mm; the driving voltage range of the liquid lens is 0–70 V.

5. An industrial lens, characterized in that, The fast-focusing industrial lens structure according to any one of claims 1-4 further includes: a lens barrel for positioning the first biconvex lens, the first cemented lens, the liquid lens, the second cemented lens, the second biconvex lens, the negative meniscus lens, and the protective glass sheet on the same optical axis.

6. The industrial lens according to claim 5, characterized in that, The nominal focal length of this industrial lens is 35mm; the distortion of this industrial lens in the 450–650nm band is controlled within ±2%; the field curvature of this industrial lens is controlled within ±0.2mm, and the relative illumination across the entire field of view is not less than 95%.

7. A control system for a fast-focusing industrial lens, characterized in that, The system includes a control module comprising: a microcontroller for calculating a driving voltage based on target distance or image feedback data; a digital-to-analog converter for outputting a low-voltage analog voltage; a high-voltage amplifier for amplifying the low-voltage analog voltage to an adjustable high voltage required for the operation of the liquid lens; and an output port electrically connected to the opposing electrode of the liquid lens via a flexible cable; wherein the liquid lens assembly is a liquid lens of the industrial lens structure described in any one of claims 1-5.

8. The control system for a fast-focusing industrial lens according to claim 7, characterized in that, It also includes a distance measurement module, whose output is connected to the microcontroller signal to provide target distance data.

9. The control system for a fast-focusing industrial lens according to claim 7, characterized in that, The microcontroller has a built-in image sharpness evaluation algorithm for real-time calculation of image contrast and fine-tuning of the drive voltage to form a closed-loop autofocus; the output voltage range of the high-voltage amplifier is 30 volts to 70 volts.

10. A visual inspection device for a fast-focusing industrial lens, characterized in that: The system includes an industrial lens and a control system. The industrial lens, from the object side to the image side along the optical axis, comprises: a first biconvex lens; a first cemented lens, formed by cementing a pre-cemented biconvex lens and a pre-cemented biconcave lens; a liquid lens with an internal annular flange forming an aperture structure; a second cemented lens, formed by cementing a post-cemented biconcave lens and a post-cemented biconvex lens; a second biconvex lens; a negative meniscus lens; and a protective glass sheet. The industrial lens also includes a lens barrel for positioning the first biconvex lens, the first cemented lens, the liquid lens, the second cemented lens, the second biconvex lens, the negative meniscus lens, and the protective glass sheet on the same optical axis. The control system is electrically connected to the liquid lens to enable rapid automatic focusing imaging of dynamic targets by the industrial lens.

Images