A 20 times high-resolution long working distance object side telecentric machine vision lens and its optical system

Abstract

The present application belongs to the technical field of machine vision optical system design, and particularly relates to a 20 times high-resolution long working distance object side telecentric machine vision lens and an optical system thereof, comprising a front lens group, a light splitting prism and a rear lens group arranged in sequence along the direction from an object plane to an image plane, wherein the front lens group comprises a first lens with positive refractive power, a first cemented lens group with negative refractive power, a second cemented lens group with positive refractive power and a sixth lens with positive refractive power, the rear lens group comprises a seventh lens with positive refractive power and a third cemented lens group with positive refractive power, the sixth lens and the seventh lens are provided with the light splitting prism, and the sixth lens and the light splitting prism are provided with a diaphragm; the rear lens group is located on the refractive path of the light splitting prism, and an illumination light source is located on the reflection path of the light splitting prism. The present application can realize 1 mu m high resolution, long working distance and good object side telecentricity under 20 times magnification, and can match phi 11 mm image plane and coaxial illumination.

Description

Technical Field

[0001] This invention belongs to the field of machine vision optical system design technology, and particularly relates to a 20x high resolution long working distance object-side telecentric machine vision lens and its optical system. Background Technology

[0002] In the field of machine vision inspection, optical lenses are the core imaging devices, and their performance directly determines the accuracy and applicability of the inspection system. The magnification, working distance, object field of view, numerical aperture, and telecentricity of machine vision lenses are mutually restrictive technical parameters. The higher the magnification of a machine vision lens, the smaller the object field of view, the shorter the working distance, and the smaller the numerical aperture, but at the same time, it will bring higher resolution and better telecentricity through correction.

[0003] Because high-magnification machine vision lenses can inspect more precise devices, high resolution can effectively improve the inspection accuracy of inspection equipment, and long working distance and good telecentricity of the optical system can increase the operating space of parts and improve the inspection capability of parts at different working distances, there is an increasingly urgent demand for machine vision lenses with high magnification, high resolution, long working distance and object-side telecentricity in high-end manufacturing industries such as semiconductor wafers, microelectronic components, precision mechanical parts, new energy battery electrodes, optical components and glass products.

[0004] In existing technologies, common machine vision lenses mainly face the following technical contradictions and shortcomings: 1. Parameters are mutually restrictive and difficult to balance: There is an inherent optical design contradiction between magnification, working distance, numerical aperture and object field of view. When the magnification is increased to about 20 times, it usually leads to a sharp reduction in working distance and a decrease in numerical aperture, which limits the ability to clearly image the test object with depth or that requires obstacle avoidance operation.

[0005] 2. Insufficient resolution: Many traditional lenses can only achieve an object resolution of 3-5 micrometers at a magnification of 20x, which is insufficient to meet the current needs for detecting submicron level defects (such as scratches on wafer surfaces and microcracks in precision parts).

[0006] 3. Poor telecentricity: When the working distance of a conventional lens changes slightly under a non-telecentric optical path, the magnification changes accordingly, introducing measurement errors. Although existing telecentric lenses can correct some errors, the telecentricity is often difficult to control stably at high magnification of 20x, affecting the consistency of detection.

[0007] Therefore, how to design a machine vision lens that can achieve 1µm object-space resolution at 20x magnification, maintain a long working distance, and have good object-space telecentricity is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0008] In view of this, the present invention aims to provide a 20x high resolution long working distance object-side telecentric machine vision lens and its optical system to overcome the shortcomings of the prior art and achieve 20x resolution of 1µm object-side, long working distance, object-side telecentricity and coaxial illumination.

[0009] To achieve the above objectives, the technical solution created by this invention is implemented as follows: An optical system for a 20x high-resolution, long-working-distance, telecentric machine vision lens includes a front lens group, a beam splitter, and a rear lens group arranged sequentially along the object plane to the image plane. The front lens group includes a first lens with positive optical power, a first cemented lens group with negative optical power, a second cemented lens group with positive optical power, and a sixth lens with positive optical power, arranged sequentially along the object plane to the image plane. The rear lens group includes a seventh lens with positive optical power and a third cemented lens group with positive optical power, arranged sequentially along the object plane to the image plane. A beam splitter is disposed between the sixth and seventh lenses, and an aperture is disposed between the sixth lens and the beam splitter. The rear lens group is located on the refraction path of the beam splitter, and the illumination source is located on the reflection path of the beam splitter.

[0010] Furthermore, the first cemented lens assembly includes a second lens with positive optical power and a third lens with negative optical power arranged sequentially along the object plane to the image plane; the second cemented lens assembly includes a fourth lens with positive optical power and a fifth lens with negative optical power arranged sequentially along the object plane to the image plane; and the third cemented lens assembly includes an eighth lens with negative optical power and a ninth lens with positive optical power arranged sequentially along the object plane to the image plane.

[0011] Furthermore, the radius of curvature of the front surface of the first lens is -180mm to -40mm, the radius of curvature of the rear surface is -90mm to -7mm, and the center thickness is 1mm to 5mm; The second lens has a front surface curvature radius of 8mm~80mm, a rear surface curvature radius of 15mm~120mm, and a center thickness of 7mm~12mm; The third lens has a front surface curvature radius of 15mm~120mm, a rear surface curvature radius of 5mm~150mm, and a center thickness of 2mm~7mm; The fourth lens has a front surface curvature radius of 2mm~90mm, a rear surface curvature radius of 2mm~110mm, and a center thickness of 4mm~15mm; The fifth lens has a front surface curvature radius of 2mm~110mm, a rear surface curvature radius of -350mm~-40mm, and a center thickness of 2.5mm~14.5mm; The sixth lens has a front surface curvature radius of 2mm~77mm, a rear surface curvature radius of 11mm~170mm, and a center thickness of 3mm~12mm; The seventh lens has a front surface curvature radius of 800mm~inf, a rear surface curvature radius of -800mm~-80mm, and a center thickness of 6mm~18mm; The eighth lens has a front surface curvature radius of 1.5mm to 90mm, a rear surface curvature radius of -80mm to -5mm, and a center thickness of 1.5mm to 5mm. The ninth lens has a front surface curvature radius of -80mm to -5mm, a rear surface curvature radius of -80mm to -5mm, and a center thickness of 1.5mm to 5mm.

[0012] Furthermore, the optical materials of the first lens, third lens, fourth lens, seventh lens, and ninth lens are flint glass, with nd > 1.75 and vd < 35; The optical materials of the second, fifth, sixth, and eighth lenses are crown glass, with nd < 1.60 and vd > 65.

[0013] Furthermore, the distance between the first lens and the second lens is 0.5mm to 30mm; The interval between the third lens and the fourth lens is 1mm to 9mm; The distance between the fifth and sixth lenses is 2.2mm to 12mm; The distance between the sixth lens and the beam splitter is 15mm~35mm; The distance between the beam splitter and the seventh lens is 60mm~90mm; The distance between the seventh and eighth lenses is 5mm to 35mm; The distance between the ninth lens and the image plane is 150mm~400mm.

[0014] Furthermore, the optical system satisfies the following condition: ; ; ; Where f1′ is the image-side focal length of the first lens; f6′ is the image-side focal length of the sixth lens; f7′ is the image-side focal length of the seventh lens; fg1′ is the image-side focal length of the front lens group; and fg2′ is the image-side focal length of the rear lens group.

[0015] Furthermore, the optical system satisfies the following condition: ; ; ; Wherein, fj1′ is the image-side focal length of the first cemented lens group; fj2′ is the image-side focal length of the second cemented lens group; fj3′ is the image-side focal length of the third cemented lens group; fg1′ is the image-side focal length of the front lens group; and fg2′ is the image-side focal length of the rear lens group.

[0016] Furthermore, the optical system satisfies the following condition: ; Where WD is the working distance of the vision lens; TOTR is the distance between the front surface of the first lens and the rear surface of the last lens in the optical system.

[0017] Furthermore, the beam splitter is a semi-transparent and semi-reflective beam splitter with a beam splitting film coated on its cemented surface; the beam splitting ratio of the beam splitter is 1:1.

[0018] A 20x high-resolution long working distance object-side telecentric machine vision lens, comprising the optical system of the aforementioned 20x high-resolution long working distance object-side telecentric machine vision lens.

[0019] Compared with the prior art, the present invention can achieve the following beneficial effects: 1. The vision lens and optical system in this solution have ultra-high resolution, achieving an object-space resolution of 1 micrometer (1μm), which can clearly distinguish micron-level minute defects, significantly improving the detection accuracy in the fields of semiconductor, microelectronics and precision component inspection. At the same time, the system magnification reaches 20 times, which can be matched with a camera with a maximum image size of φ11mm. While achieving high magnification, it ensures sufficient field of view coverage, which is convenient for observation and positioning.

[0020] 2. The vision lens and optical system in this solution can still achieve a long working distance at a high magnification of 20x, which increases the operating space between the object being measured and the front end of the lens. This can effectively avoid collisions between the lens and the workpiece or fixture, and adapt to the inspection of parts of different thicknesses or with depth. At the same time, through reasonable optical power distribution and optical path design, it can achieve good object-side telecentric characteristics, effectively reduce the magnification error caused by changes in working distance, and ensure the consistency and repeatability of the detected dimensions within the depth of field.

[0021] 3. The vision lens and optical system in this solution incorporate a beam-splitting prism between the sixth and seventh lenses, enabling coaxial illumination. This effectively illuminates low-contrast areas such as deep holes and grooves. Furthermore, through precise allocation of the optical power of each lens and the cemented lens group, the system maintains excellent aberration correction even after the addition of the prism, ensuring image clarity and uniformity. Each lens is assigned a reasonable optical power allocation, resulting in good correction of spherical aberration, chromatic aberration, coma, and astigmatism. The image quality is stable and reliable, making it suitable for industrial mass production and testing environments. Attached Figure Description

[0022] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the overall structure of the optical system described in Embodiment 1 of the present invention; Figure 2 MTF curve of the optical system described in Embodiment 1 of this invention; Figure 3 This invention creates a distortion curve diagram of the optical system described in Embodiment 1 of the present invention; Figure 4 The dot matrix diagram of the optical system described in Embodiment 1 of the present invention is provided.

[0023] Reference numerals: First lens 1, Second lens 2, Third lens 3, Fourth lens 4, Fifth lens 5, Sixth lens 6, Seventh lens 7, Eighth lens 8, Ninth lens 9, Beam splitter 10, First cemented lens group 11, Second cemented lens group 12, Third cemented lens group 13, Front lens group 14, Rear lens group 15. Detailed Implementation

[0024] To make the purpose, technical solution, and advantages of this invention clearer, the following description is provided in conjunction with the appendix. Figure 1-4 The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and do not constitute a limitation thereof.

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0026] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0027] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0028] The following will refer to the appendix. Figure 1-4 The invention will be described in detail with reference to the embodiments.

[0029] An optical system for a 20x high-resolution, long-working-distance, telecentric machine vision lens includes a front lens group 14, a beam splitter 10, and a rear lens group 15 arranged sequentially along the object-to-image plane direction. The front lens group 14 includes a first lens 1 with positive optical power, a first cemented lens group 11 with negative optical power, a second cemented lens group 12 with positive optical power, and a sixth lens 6 with positive optical power, arranged sequentially along the object-to-image plane direction. The first cemented lens group 11 includes a first lens 1 with positive optical power, a second cemented lens group 12 with positive optical power, and a sixth lens 6 with positive optical power, arranged sequentially along the object-to-image plane direction. The second lens group 12 includes a second lens 2 with optical power and a third lens 3 with negative optical power. The second cemented lens group 12 includes a fourth lens 4 with positive optical power and a fifth lens 5 with negative optical power arranged sequentially along the object plane to the image plane. The rear lens group 15 includes a seventh lens 7 with positive optical power and a third cemented lens group 13 with positive optical power arranged sequentially along the object plane to the image plane. The third cemented lens group 13 includes an eighth lens 8 with negative optical power and a ninth lens 9 with positive optical power arranged sequentially along the object plane to the image plane.

[0030] The first cemented lens group 11 is located in the middle of the front lens group 14 and can correct chromatic aberration and compensate for spherical aberration. The second cemented lens group 12 is located behind the front lens group 14 and can converge light and balance aberrations. The third cemented lens group 13 is located at the end of the rear lens group 15 and can finally focus and control field curvature. By alternating positive and negative cemented lens groups, light of different wavelengths can be converged to the same point to achieve a high resolution of 1μm. The negative cemented lens group in the front group is responsible for diverging light and correcting spherical aberration, while the positive cemented lens group in the rear group is responsible for converging and balancing coma. The reasonable distribution of optical power of the front and rear cemented lens groups keeps the image plane flat. Better correction can be achieved through three cemented lens groups, and better image quality can be achieved by using fewer lenses.

[0031] A beam splitter 10 is provided between the sixth lens 6 and the seventh lens 7 to achieve coaxial illumination. The beam splitter 10 is a semi-transparent and semi-reflective beam splitter 10, and a beam splitting film is coated on its cemented surface. The beam splitting ratio of the beam splitter 10 is 1:1. An aperture is provided between the sixth lens 6 and the beam splitter 10. The rear lens group 15 is located on the refraction path of the beam splitter 10, and the illumination source is located on the reflection path of the beam splitter 10. This can achieve coaxial illumination of the system, and there is enough space between the sixth lens 6 and the seventh lens 7 to accommodate the beam splitter 10 without increasing the overall length of the system and avoiding cutting the light path.

[0032] Figure 1 In the diagram, A represents the object plane, B represents the image plane, and C represents the aperture. The aperture is designed in conjunction with the cemented lens group for better telecentricity.

[0033] The distance between the first lens 1 and the second lens 2 is 0.5mm to 30mm. In this embodiment, as shown in Table 1, the distance between the first lens 1 and the second lens 2 is 11.94mm.

[0034] The distance between the third lens 3 and the fourth lens 4 is 1mm to 9mm. In this embodiment, as shown in Table 1, the distance between the third lens 3 and the fourth lens 4 is 3.12mm.

[0035] The distance between the fifth lens 5 and the sixth lens 6 is 2.2mm to 12mm. In this embodiment, as shown in Table 1, the distance between the fifth lens 5 and the sixth lens 6 is 3.91mm.

[0036] The distance between the sixth lens 6 and the beam splitter 10 is 15mm to 35mm. In this embodiment, as shown in Table 1, the distance between the sixth lens 6 and the beam splitter 10 is 30mm.

[0037] The distance between the beam splitter 10 and the seventh lens 7 is 60mm to 90mm. In this embodiment, as shown in Table 1, the distance between the beam splitter 10 and the seventh lens 7 is 80mm.

[0038] The distance between the seventh lens 7 and the eighth lens 8 is 5mm to 35mm. In this embodiment, as shown in Table 1, the distance between the seventh lens 7 and the eighth lens 8 is 14.35mm.

[0039] The distance between the ninth lens 9 and the image plane is 150mm~400mm. In this embodiment, as shown in Table 1, the distance between the ninth lens 9 and the image plane is 223.74mm.

[0040] The first lens 1 has a front surface curvature radius of -180mm to -40mm, a rear surface curvature radius of -90mm to -7mm, and a center thickness of 1mm to 5mm. Its optical material is flint glass with nd > 1.75 and vd < 35. In this embodiment, as shown in Table 1, the front surface curvature radius of the first lens 1 is -78.65mm, the rear surface curvature radius is -31.31mm, and the center thickness is 4.45mm.

[0041] The second lens 2 has a front surface curvature radius of 8mm~80mm, a rear surface curvature radius of 15mm~120mm, and a center thickness of 7mm~12mm. Its optical material is crown glass with nd<1.60 and vd>65. In this embodiment, as shown in Table 1, the front surface curvature radius of the second lens 2 is 22.41mm and the center thickness is 11.94mm.

[0042] The third lens 3 has a front surface curvature radius of 15mm~120mm, a rear surface curvature radius of 5mm~150mm, and a center thickness of 2mm~7mm. Its optical material is flint glass with nd>1.75 and vd<35. In this embodiment, as shown in Table 1, the third lens 3 has a front surface curvature radius of 54.18mm, a rear surface curvature radius of 18.72mm, and a center thickness of 4.61mm.

[0043] The fourth lens 4 has a front surface curvature radius of 2mm~90mm, a rear surface curvature radius of 2mm~110mm, and a center thickness of 4mm~15mm. Its optical material is flint glass with nd>1.75 and vd<35. In this embodiment, as shown in Table 1, the front surface curvature radius of the fourth lens 4 is 25.23mm and the center thickness is 11.98mm.

[0044] The fifth lens 5 has a front surface curvature radius of 2mm~110mm, a rear surface curvature radius of -350mm~-40mm, and a center thickness of 2.5mm~14.5mm. Its optical material is crown glass with nd<1.60 and vd>65. In this embodiment, as shown in Table 1, the fifth lens 5 has a front surface curvature radius of 20.14mm, a rear surface curvature radius of -107.54mm, and a center thickness of 6.57mm.

[0045] The sixth lens 6 has a front surface curvature radius of 2mm~77mm, a rear surface curvature radius of 11mm~170mm, and a center thickness of 3mm~12mm. Its optical material is crown glass with nd<1.60 and vd>65. In this embodiment, as shown in Table 1, the sixth lens 6 has a front surface curvature radius of 23.56mm, a rear surface curvature radius of 53.91mm, and a center thickness of 4.19mm.

[0046] The seventh lens 7 has a front surface radius of curvature of 800mm~inf (representing an infinite value, which can approach a plane), a rear surface radius of curvature of -800mm~-80mm, and a center thickness of 6mm~18mm. Its optical material is flint glass, nd>1.75, vd<35. In this embodiment, as shown in Table 1, the front surface radius of curvature of the seventh lens 7 is 2244.07mm, the rear surface radius of curvature is -286.52mm, and the center thickness is 8.01mm.

[0047] The front surface curvature radius of the eighth lens 8 is 1.5mm~90mm, the rear surface curvature radius is -80mm~-5mm, and the center thickness is 1.5mm~5mm. Its optical material is crown glass with nd<1.60 and vd>65. In this embodiment, as shown in Table 1, the front surface curvature radius of the eighth lens 8 is 22.81mm and the center thickness is 3.65mm.

[0048] The ninth lens 9 has a front surface curvature radius of -80mm to -5mm, a rear surface curvature radius of -80mm to -5mm, and a center thickness of 1.5mm to 5mm. Its optical material is flint glass with nd > 1.75 and vd < 35. In this embodiment, as shown in Table 1, the ninth lens 9 has a front surface curvature radius of -12.11mm, a rear surface curvature radius of -19.09mm, and a center thickness of 2mm.

[0049] In this embodiment, only two glass materials are used to meet the system performance requirements, effectively reducing the coating cost. Those skilled in the art can replace more materials according to the actual situation to meet the color difference correction. The focal length allocation system in this embodiment is more efficient in aberration correction, and the focal length allocation has found the best balance point.

[0050] In this embodiment, the optical system must meet the following conditions: ; ; ; ; ; ; Wherein, f1′ is the image-side focal length of the first lens 1; f6′ is the image-side focal length of the sixth lens 6; f7′ is the image-side focal length of the seventh lens 7; fg1′ is the image-side focal length of the front lens group 14; fg2′ is the image-side focal length of the rear lens group 15; fj1′ is the image-side focal length of the first cemented lens group 11; fj2′ is the image-side focal length of the second cemented lens group 12; and fj3′ is the image-side focal length of the third cemented lens group 13.

[0051] The optical system satisfies the following conditions: ; Where WD is the working distance of the vision lens; TOTR is the distance between the front surface of the first lens and the rear surface of the last lens in the optical system.

[0052] In this application embodiment, the relevant data of the optical system are shown in Table 1 below: Table 1

[0053] In this embodiment, the image-side focal length of the front lens group 14 is fg1′=36.05mm, the image-side focal length of the rear lens group 15 is fg2′=34.06mm, the image-side focal length of the first lens 1 is f1′=52.59mm, the image-side focal length of the sixth lens 6 is f6′=91.74mm, the image-side focal length of the seventh lens 7 is f7′=268.97mm, the image-side focal length of the first cemented lens group 11 is fj1′=-85.82mm, the image-side focal length of the second cemented lens group 12 is fj2′=47.86mm, and the image-side focal length of the third cemented lens group 13 is fj3′=36.448mm.

[0054] In this embodiment, the optical parameters of the optical system are shown in Table 2 below: Table 2

[0055] In this embodiment, the formula for calculating the resolution is 0.65. λ / NA, where λ is the wavelength, all lenses are spherical lenses, no aspherical lenses are used, and they have good processing performance.

[0056] In this embodiment, each lens is assigned an appropriate optical power, so that the optical power assigned to each lens can achieve a good aberration optimization effect.

[0057] Instructions are required. Figure 1 This is a schematic diagram of the overall structure of the optical system. Figure 2The diagram shown is the MTF curve of the optical system in this embodiment. Figure 3 The diagram shown is a distortion curve of the optical system in this embodiment. Figure 4 The diagram shown is a dot matrix of the optical system in this embodiment.

[0058] Example 2 A 20x high-resolution long working distance object-side telecentric machine vision lens includes the optical system of the 20x high-resolution long working distance object-side telecentric machine vision lens in Embodiment 1. Since the optical system has been described in detail in Embodiment 1, it will not be repeated in this embodiment.

[0059] The machine vision lens in this embodiment operates in the visible light band, has a magnification of 20x, a numerical aperture better than 0.35, a working distance less than or equal to 40mm, an object-side field of view of φ0.55mm, a full-field telecentricity better than 0.01, a maximum matched image plane size of φ11mm, and an object-side resolution better than 1um@550nm.

[0060] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0061] 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 system for a 20x high-resolution, long-working-distance, telecentric machine vision lens, characterized in that: The system includes a front lens group (14), a beam splitter (10), and a rear lens group (15) arranged sequentially along the object plane to the image plane. The front lens group (14) includes a first lens (1) with positive optical power, a first cemented lens group (11) with negative optical power, a second cemented lens group (12) with positive optical power, and a sixth lens (6) with positive optical power, arranged sequentially along the object plane to the image plane. The rear lens group (15) includes a seventh lens (7) with positive optical power and a third cemented lens group (13) with positive optical power, arranged sequentially along the object plane to the image plane. A beam splitter (10) is arranged between the sixth lens (6) and the seventh lens (7), and an aperture is arranged between the sixth lens (6) and the beam splitter (10). The rear lens group (15) is located on the refraction path of the beam splitter (10), and the illumination source is located on the reflection path of the beam splitter (10).

2. The optical system of the 20x high-resolution long working distance object-side telecentric machine vision lens according to claim 1, characterized in that: The first cemented lens group (11) includes a second lens (2) with positive optical power and a third lens (3) with negative optical power arranged sequentially along the object plane to the image plane; the second cemented lens group (12) includes a fourth lens (4) with positive optical power and a fifth lens (5) with negative optical power arranged sequentially along the object plane to the image plane; the third cemented lens group (13) includes an eighth lens (8) with negative optical power and a ninth lens (9) with positive optical power arranged sequentially along the object plane to the image plane.

3. The optical system of the 20x high-resolution long working distance object-side telecentric machine vision lens according to claim 2, characterized in that: The first lens (1) has a front surface curvature radius of -180mm to -40mm, a rear surface curvature radius of -90mm to -7mm, and a center thickness of 1mm to 5mm; The second lens (2) has a front surface curvature radius of 8mm~80mm, a rear surface curvature radius of 15mm~120mm, and a center thickness of 7mm~12mm; The third lens (3) has a front surface curvature radius of 15mm~120mm, a rear surface curvature radius of 5mm~150mm, and a center thickness of 2mm~7mm; The fourth lens (4) has a front surface curvature radius of 2mm~90mm, a rear surface curvature radius of 2mm~110mm, and a center thickness of 4mm~15mm; The fifth lens (5) has a front surface curvature radius of 2mm~110mm, a rear surface curvature radius of -350mm~-40mm, and a center thickness of 2.5mm~14.5mm; The sixth lens (6) has a front surface curvature radius of 2mm~77mm, a rear surface curvature radius of 11mm~170mm, and a center thickness of 3mm~12mm; The seventh lens (7) has a front surface curvature radius of 800mm~inf, a rear surface curvature radius of -800mm~-80mm, and a center thickness of 6mm~18mm; The radius of curvature of the front surface of the eighth lens (8) is 1.5mm~90mm, the radius of curvature of the rear surface is -80mm~-5mm, and the center thickness is 1.5mm~5mm; The front surface curvature radius of the ninth lens (9) is -80mm to -5mm, the rear surface curvature radius is -80mm to -5mm, and the center thickness is 1.5mm to 5mm.

4. The optical system of the 20x high-resolution long working distance object-side telecentric machine vision lens according to claim 3, characterized in that: The optical materials of the first lens (1), the third lens (3), the fourth lens (4), the seventh lens (7), and the ninth lens (9) are flint glass, with nd>1.75 and vd<35; The optical materials of the second lens (2), the fifth lens (5), the sixth lens (6), and the eighth lens (8) are crown glass, with nd < 1.60 and vd > 65.

5. The optical system of the 20x high-resolution long working distance object-side telecentric machine vision lens according to claim 2, characterized in that: The distance between the first lens (1) and the second lens (2) is 0.5mm to 30mm; The distance between the third lens (3) and the fourth lens (4) is 1mm to 9mm; The distance between the fifth lens (5) and the sixth lens (6) is 2.2mm to 12mm; The distance between the sixth lens (6) and the beam splitter (10) is 15mm~35mm; The distance between the beam splitter (10) and the seventh lens (7) is 60mm~90mm; The distance between the seventh lens (7) and the eighth lens (8) is 5mm to 35mm; The distance between the ninth lens (9) and the image plane is 150mm~400mm.

6. The optical system of the 20x high-resolution long working distance object-side telecentric machine vision lens according to claim 2, characterized in that: The optical system satisfies the following conditions: ； ； ； Wherein, f1′ is the image-side focal length of the first lens (1); f6′ is the image-side focal length of the sixth lens (6); f7′ is the image-side focal length of the seventh lens (7); fg1′ is the image-side focal length of the front lens group (14); and fg2′ is the image-side focal length of the rear lens group (15).

7. The optical system of the 20x high-resolution long working distance object-side telecentric machine vision lens according to claim 2, characterized in that: The optical system satisfies the following conditions: ； ； ； Wherein, fj1′ is the image-side focal length of the first cemented lens group (11); fj2′ is the image-side focal length of the second cemented lens group (12); fj3′ is the image-side focal length of the third cemented lens group (13); fg1′ is the image-side focal length of the front lens group (14); and fg2′ is the image-side focal length of the rear lens group (15).

8. The optical system of the 20x high-resolution long working distance object-side telecentric machine vision lens according to claim 1, characterized in that: The optical system satisfies the following conditions: 0.1 ≤ |WD / TOTR| ≤ 0.2; Where WD is the working distance of the vision lens; TOTR is the distance between the front surface of the first lens and the rear surface of the last lens in the optical system.

9. The optical system of the 20x high-resolution long working distance object-side telecentric machine vision lens according to claim 1, characterized in that: The beam splitter (10) is a semi-transparent and semi-reflective beam splitter (10), and a beam splitting film is coated on its adhesive surface; the beam splitting ratio of the beam splitter (10) is 1:

1.

10. A 20x high-resolution long working distance telecentric machine vision lens, characterized in that: An optical system comprising the 20x high-resolution long working distance object-oriented telecentric machine vision lens according to any one of claims 1-9.

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