Visual inspection system

Abstract

The utility model relates to the technical field of machine vision detection, and discloses a vision detection system which comprises a first lens assembly and a second lens assembly, and the first lens assembly and the second lens assembly are both Sammer lenses; the first lens assembly and the second lens assembly are configured to obliquely face the working surface, and the optical axis of the first lens assembly and the optical axis of the second lens assembly are in mirror symmetry relative to the normal of the working surface; the first lens assembly is provided with a first coaxial light source, and the second lens assembly is provided with a second coaxial light source; the first coaxial light source is used for supplementing light when the second lens assembly shoots; the second coaxial light source is used for supplementing light when the first lens assembly shoots. Through the above mode, the imaging brightness during oblique shooting can be effectively improved, and the detection accuracy is further improved.

Description

Technical Field

[0001] This application relates to the field of machine vision inspection technology, and specifically to a vision inspection system. Background Technology

[0002] In some machine vision inspection fields, it is necessary to perform inspection by tilting the camera. The key component of the Schamm lens vision inspection system that achieves tilting imaging is based on Schamm's Law, which states that when the extended planes of the object plane, the image plane, and the principal plane of the lens intersect on the same straight line, a clear and comprehensive image can be obtained.

[0003] To improve image brightness, many inspection systems using SAM lenses are equipped with coaxial light sources to output illumination light from the lens via the optical axis. However, since these inspection systems take pictures at an angle relative to the object surface, most of the illumination light output from the lens is reflected to the other side after reaching the object surface. This results in less light entering the lens and a less significant improvement in brightness. Utility Model Content

[0004] In view of the above problems, this application provides a visual inspection system that can effectively improve the imaging brightness when shooting at an angle, thereby improving the accuracy of inspection.

[0005] According to one aspect of the embodiments of this application, a visual inspection system is provided for imaging an object on a work surface, comprising: a first lens assembly and a second lens assembly, both the first lens assembly and the second lens assembly being SAM lenses; both the first lens assembly and the second lens assembly are configured to be tilted towards the work surface, and the optical axes of the first lens assembly and the second lens assembly are mirror-symmetrical with respect to the normal of the work surface; the first lens assembly is equipped with a first coaxial light source, and the second lens assembly is equipped with a second coaxial light source; the first coaxial light source is used to provide supplementary lighting when the second lens assembly is shooting, so that the light emitted from the first lens assembly by the first coaxial light source is reflected after passing through the surface of the object on the work surface and enters the second lens assembly; the second coaxial light source is used to provide supplementary lighting when the first lens assembly is shooting, so that the light emitted from the second lens assembly by the second coaxial light source is reflected after passing through the surface of the object and enters the first lens assembly.

[0006] In one alternative approach, the optical axis of the first lens assembly is configured to have an angle of θ between it and the normal to the working surface, where 0° < θ ≤ 30°.

[0007] In one alternative embodiment, both the first and second lens assemblies are double telecentric Sham lenses. The first lens assembly includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a beam splitter, an aperture stop, a sixth lens, a seventh lens, an eighth lens, a ninth lens, a parallel plate, and an image plane arranged sequentially along its optical path. The image plane is tilted relative to the optical axis of the first lens assembly. The first, third, fourth, sixth, and eighth lenses are all positive lenses, while the second, fifth, seventh, and ninth lenses are all negative lenses. The first cemented lens is formed by bonding the third lens to the fourth lens and the fifth lens to the fifth lens; the second cemented lens is formed by bonding the eighth lens and the ninth lens to the ninth lens; the beam splitter has a reflecting end and a transmitting end; the first coaxial light source is disposed at the reflecting end of the beam splitter; the beam splitter is used to reflect the illumination light output by the first coaxial light source along the optical path of the first lens assembly and finally output it from the first lens assembly; the aperture is disposed at the transmitting end of the beam splitter; the beam splitter is also used to allow the light entering the first lens assembly to be transmitted to reach the image plane; the second lens assembly has the same structure as the first lens assembly.

[0008] In one alternative approach, the effective focal length of the first lens assembly as a whole is f, the focal length of the first lens is f1, the focal length of the second lens is f2, the focal length of the third lens is f3, the focal length of the fourth lens is f4, the focal length of the fifth lens is f5, the focal length of the sixth lens is f6, the focal length of the seventh lens is f7, the focal length of the eighth lens is f8, and the focal length of the ninth lens is f9, satisfying the following relationships: 0.01 < |f1 / f| < 0.07; 0 < |f2 / f| < 0.04; 0.01 < |f3 / f| < 0.05; 0 < |f4 / f| < 0.04; 0 < |f5 / f| < 0.04; 0.01 < |f6 / f| < 0.04; 0 < |f7 / f| < 0.03; 0 < |f8 / f| < 0.035; 0.01 < |f9 / f| < 0.06.

[0009] In one alternative embodiment, the beam splitter is a dichroic prism, the reflecting end of which includes a first reflecting end and a second reflecting end; both the first and second lens assemblies include a front lens group, a first rear lens group, and a second rear lens group; the front lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and the dichroic prism; both the first and second rear lens groups include a sixth lens, a seventh lens, an eighth lens, a ninth lens, a parallel plate, and an image plane, wherein the eighth and ninth lenses in the second rear lens group do not form a third cemented lens; the first rear lens group is located at the dichroic prism. At the transmission end, an aperture stop is provided between the rear and front groups of the first lens, forming a first optical lens group. A dichroic prism is used to transmit light of a predetermined wavelength entering the front group to the image plane in the rear group. The second rear lens group is located at the first reflection end of the dichroic prism. An aperture stop is provided between the rear and front groups, forming a second optical lens group. The dichroic prism is also used to reflect light of a predetermined wavelength entering the front group to the image plane in the rear group. The magnification is different; in the first lens assembly, the first coaxial light source is disposed at the second reflecting end of the dichroic prism. The dichroic prism is used to reflect the light of a first predetermined wavelength in the illumination light output by the first coaxial light source along the optical path of the front lens group and finally output it from the front lens group. The light of the first predetermined wavelength output from the front lens group is reflected by the surface of the subject and first enters the front lens group of the second lens assembly. After being transmitted by the dichroic prism in the second lens assembly, it reaches the first rear lens group of the second lens assembly, or after being reflected by the dichroic prism in the second lens assembly, it reaches the second lens group of the second lens assembly. The first lens assembly includes a rear lens group; in the second lens assembly, a second coaxial light source is disposed at the second reflective end of a dichroic prism. The dichroic prism is used to reflect the light of a second predetermined wavelength in the illumination light output by the second coaxial light source along the optical path of the front lens group and finally output it from the front lens group. The light of the second predetermined wavelength output from the front lens group is reflected by the surface of the subject and first enters the front lens group of the first lens assembly. After being transmitted by the dichroic prism in the first lens assembly, it reaches the first rear lens group of the first lens assembly, or after being reflected by the dichroic prism in the first lens assembly, it reaches the second rear lens group of the first lens assembly.

[0010] In one alternative configuration, the first optical lens group has a magnification of PMAG1 and an aperture of F.NO1, where PMAG1 = -1 and F.NO1 = 8.5; the second optical lens group has a magnification of PMAG2 and an aperture of F.NO2, where PMAG2 = -0.7 and F.NO2 = 8.5.

[0011] In an alternative embodiment, in the first rear lens group, the angle between the parallel plate and the optical axis of the first rear lens group is 90.657°; in the second rear lens group, the angle between the parallel plate and the optical axis of the second rear lens group is 91.496°.

[0012] In an alternative embodiment, the effective focal length of the first optical lens group is f a , and the effective focal length of the second optical lens group is f b , the effective focal length of the first rear lens group is f c , and the effective focal length of the second rear lens group is f d , which satisfy the following relationships: 0.02 < f c / f a <0.06; 0.02 < f d / f b <0.05.

[0013] In an alternative embodiment, the refractive indices of the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are Nd1, Nd2, Nd3, Nd4, and Nd5 respectively, and the Abbe numbers are Vd1, Vd2, Vd3, Vd4, and Vd5 respectively, which satisfy the following relationships: 1.45 < Nd1 < 1.75, 50 < Vd1 < 75; 1.60 < Nd2 < 2.00, 25 < Vd2 < 50; 1.50 < Nd3 < 1.70, 40 < Vd3 < 75; 1.40 < Nd4 < 1.75, 50 < Vd4 < 75; 1.65 < Nd5 < 2.00, 35 < Vd5 < 55; in the first rear lens group, the refractive indices of the sixth lens, the seventh lens, the eighth lens, and the ninth lens are Nd a6 , Nd a7 , Nd a8 , and Nd a9 , and the Abbe numbers are Vd a6 , Vd a7 , Vd a8 , and Vd a9 , which satisfy the following relationships: 1.80 < Nd a6 <2.00, 20 < Vd a6 <40; 1.40 < Nd a7 <1.75, 20 < Vd a7 <45; 1.70 < Nd a8 <2.00, 40 < Vd a8 <65; 1.55 < Nd a9 <1.80, 18 < Vd a9 <40; in the second rear lens group, the refractive indices of the sixth lens, the seventh lens, the eighth lens, and the ninth lens are Nd b6 , Nd b7 , Ndb8 and Nd b9 The Abbe numbers are Vd b6 Vd b7 Vd b8 and Vd b9 It satisfies the following relationship: 1.80 <Nd b6 <2.00, 20 <Vd b6 <40; 1.50 <Nd b7 <1.75, 20 <Vd b7 <45; 1.80 <Nd b8 <2.00, 40 <Vd b8 <65; 1.45 <Nd b9 <1.72, 18 <Vd b9 <40.

[0014] In one alternative approach, the vision inspection system also includes a third lens assembly configured to face vertically toward the work surface.

[0015] In the visual inspection system provided in this application embodiment, since the optical axis of the first lens assembly and the optical axis of the second lens assembly are mirror-symmetric with respect to the normal, that is, the angle between the optical axis of the first lens assembly and the normal is equal to the angle between the optical axis of the second lens assembly and the normal, this allows the coaxial illumination light emitted from one lens assembly along its optical axis to be reflected more along the optical axis of the other lens assembly after reaching the object surface, thereby effectively improving the imaging brightness of the other lens assembly and ensuring the accuracy of the visual inspection results.

[0016] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0017] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0018] Figure 1 A schematic diagram illustrating the imaging principle of a Sham lens;

[0019] Figure 2 A schematic diagram of the optical path for providing illumination and supplemental lighting for an existing Sham lens equipped with a coaxial light source;

[0020] Figure 3 This is a block diagram of the visual inspection system provided in the embodiments of this application;

[0021] Figure 4 This is a structural block diagram of the first lens assembly in the visual inspection system provided in the embodiments of this application;

[0022] Figure 5 for Figure 4 The corresponding optical path diagram of the first lens assembly;

[0023] Figure 6 This is a structural block diagram of a first lens assembly in a visual inspection system provided in another embodiment of this application;

[0024] Figure 7 for Figure 6 The corresponding optical path diagram of the first lens assembly;

[0025] Figure 8 This is a schematic diagram of the imaging principle of the first optical lens group;

[0026] Figure 9 This is a schematic diagram of the imaging principle of the second optical lens group;

[0027] Figure 10 This is a structural diagram of the parallel flat plate in the rear group of the first shot;

[0028] Figure 11 This is a structural diagram of the parallel plate in the rear group of the second lens;

[0029] Figure 12 The modulation transfer function (MTF) plot of the first optical lens group;

[0030] Figure 13 The modulation transfer function (MTF) plot of the second optical lens group;

[0031] Figure 14 This is a system point diagram of the first optical lens group;

[0032] Figure 15 This is a system point diagram of the second optical lens group;

[0033] Figure 16 The distortion diagram is for the first optical lens group;

[0034] Figure 17 The distortion diagram is for the second optical lens group;

[0035] Figure 18 This is a structural block diagram of a visual inspection system provided in another embodiment of this application.

[0036] The reference numerals in the detailed embodiments are as follows:

[0037] 10. Schahm lens; 11. Coaxial light source; 20. Object plane;

[0038] 100. Visual inspection system;

[0039] 110. First lens assembly; 111. First lens; 112. Second lens; 113. Third lens; 114. Fourth lens; 115. Fifth lens; 116. Sixth lens; 117. Seventh lens; 118. Eighth lens; 119. Ninth lens; 1123. First cemented lens; 1145. Second cemented lens; 1189. Third cemented lens;

[0040] 1101, First coaxial light source; 1102, Beam splitter; 1103, Aperture stop; 1104, Parallel plate; 1105, Image plane; 1105', Mirror image plane; 1106, Dichroic prism;

[0041] 120. Second lens assembly; 1201. Second coaxial light source;

[0042] 131. Front group of the lens; 1321. Rear group of the first lens; 1322. Rear group of the second lens;

[0043] 130. Third lens assembly;

[0044] 200, working surface; 210, normal line;

[0045] 300. The object being photographed; 310. The surface of the object. Detailed Implementation

[0046] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0047] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0048] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0049] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0050] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A exists, A and B exist simultaneously, and B exists. In addition, the character " / " in this document generally indicates that the related objects before and after it have an "or" relationship.

[0051] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0052] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0053] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; 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; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0054] For the specific principles of Sham lens imaging, please refer to [link / reference]. Figure 1 It follows Scham's Law, which states that a clear image can be obtained when the extended planes of the object plane, the image plane, and the principal plane of the lens intersect on the same straight line.

[0055] Existing Sham lens 10 Figure 2As shown, it is equipped with a coaxial light source 11, which is tilted relative to the object surface 20 during shooting. Based on this, the coaxial illumination light (indicated by the dashed arrow in the figure) output from the Sham lens 10 will obliquely illuminate the object surface 20. For a smooth object surface 20, the light will be reflected to the other side of the object surface 20, so that the light cannot return to the Sham lens 10, thus failing to effectively improve the brightness of the image. For a rough object surface 20, although the light undergoes diffuse reflection on the object surface 20, most of the light will still be reflected to the other side, and only a small portion of the light may be reflected into the Sham lens 10. Similarly, it is difficult to significantly improve the brightness of the image, thus making it difficult to ensure the accuracy of visual inspection.

[0056] In view of the above problems, this application proposes a visual inspection system that uses a first lens assembly and a second lens assembly, both of which are Sham lenses, to capture images of a subject on a working surface at an angle. The optical axes of the first and second lens assemblies are mirror-symmetrical with respect to the normal of the working surface. Since both the first and second lens assemblies are equipped with coaxial light sources, the light output from the coaxial light source on the first lens assembly provides supplementary lighting for the second lens assembly, and vice versa. This allows more light that is obliquely incident on the surface of the subject from one side to enter the lens assembly on the other side after being reflected, thereby effectively improving the brightness of the image captured by the other lens assembly and ensuring the accuracy of the visual inspection results.

[0057] Please refer to the following first. Figure 3 The figure shows an optical path diagram of the visual inspection system provided in an embodiment of this application. As shown, the visual inspection system 100 is used to capture images of a subject 300 on a working surface 200. The visual inspection system 100 includes a first lens assembly 110 and a second lens assembly 120, both of which are SAM lenses. Both the first lens assembly 110 and the second lens assembly 120 are configured to be tilted towards the working surface 200, and the optical axes of the first lens assembly 110 and the second lens assembly 120 are mirror-symmetrical with respect to the normal 210 of the working surface 200. The first lens assembly 110 is equipped with a first coaxial light source 1101, and the second lens assembly 120 is equipped with a second coaxial light source 1201.

[0058] The first coaxial light source 1101 is used to provide supplementary lighting during shooting by the second lens assembly 120, so that the light emitted from the first lens assembly 1101 by the first coaxial light source 1101 is reflected by the surface (i.e., object surface 310) of the subject 300 and enters the second lens assembly 120. The specific optical path of this light is as follows: Figure 3 The dashed arrows on the left and right sides point downwards and upwards, respectively.

[0059] The second coaxial light source 1201 is used to provide supplemental lighting during shooting by the first lens assembly 110, so that the light emitted from the second coaxial light source 1201 from the second lens assembly 120 is reflected by the object surface 310 and enters the first lens assembly 110. The specific optical path of this light is as follows: Figure 3 The dashed arrows on the right and left sides point downwards and upwards, respectively.

[0060] It should be noted that in actual testing, when only one side of the object 300 needs to be photographed, only one lens assembly (first lens assembly 110 or second lens assembly 120) can be turned on to capture the image, while the other lens assembly (second lens assembly 120 or first lens assembly 110) can only turn on its coaxial light source (second coaxial light source 1201 or first coaxial light source 1101) to provide supplementary lighting for the other lens assembly.

[0061] Of course, when it is necessary to perform shooting and detection on multiple sides of the subject 300, the first lens assembly 110 and the second lens assembly 120 can be turned on at the same time, and the first coaxial light source 1101 and the second coaxial light source 1201 can be turned on at the same time. The first lens assembly 110 and the second lens assembly 120 can simultaneously take pictures of the subject 300 to achieve visual detection on multiple sides of the subject 300.

[0062] In the visual inspection system 100 provided in this application embodiment, since the optical axis of the first lens assembly 110 and the optical axis of the second lens assembly 120 are mirror-symmetric with respect to the normal 210, that is, the angle between the optical axis of the first lens assembly 110 and the normal 210 is equal to the angle between the optical axis of the second lens assembly 120 and the normal 210, both are... Figure 3 As shown in θ, this allows the coaxial illumination light emitted from one lens assembly along its optical axis to be reflected more along the optical axis of the other lens assembly after reaching the object surface 310, thereby effectively improving the imaging brightness of the other lens assembly and ensuring the accuracy of the visual inspection results.

[0063] like Figure 3 As shown, the angle between the optical axis and the normal 210 of the first lens assembly 110 and the angle θ between the optical axis and the normal 210 of the second lens assembly 120 can be set to 0° < θ ≤ 30°. Setting θ to any value within the range of greater than 0 and less than 30° can effectively ensure clear imaging when shooting at an angle, thus guaranteeing the accuracy of visual inspection results.

[0064] Both the first lens assembly 110 and the second lens assembly 120 are double telecentric Scharm lenses, and they have the same structure. Taking the first lens assembly 110 as an example, ... Figure 4As shown, it may include a first lens 111, a second lens 112, a third lens 113, a fourth lens 114, a fifth lens 115, a beam splitter 1102, an aperture stop 1103, a sixth lens 116, a seventh lens 117, an eighth lens 118, a ninth lens 119, a parallel plate 1104, and an image plane 1105 arranged sequentially along the optical path direction (horizontal direction in the figure). The image plane 1105 is inclined relative to the optical axis (horizontal straight line in the figure) of the first lens assembly 110 to achieve tilted imaging.

[0065] In this configuration, the first lens 111, the third lens 113, the fourth lens 114, the sixth lens 116, and the eighth lens 118 are all positive lenses, while the second lens 112, the fifth lens 115, the seventh lens 117, and the ninth lens 119 are all negative lenses. The second lens 112 and the third lens 113 are bonded together to form the first cemented lens 1123, the fourth lens 114 and the fifth lens 115 are bonded together to form the second cemented lens 1145, and the eighth lens 118 and the ninth lens 119 are bonded together to form the third cemented lens 1189.

[0066] The beam splitter 1102 can be a beam-splitting prism or a dichroic prism. The beam splitter 1102 has a transmission end and a reflection end. The first coaxial light source 1101 is disposed at the reflection end of the beam splitter 1102. Figure 4 As shown by the middle arrow, the beam splitter 1102 is used to reflect the illumination light output by the first coaxial light source 1101 along the optical path of the first lens assembly 110 and finally output it from the first lens assembly 110.

[0067] The aperture 1103 is disposed at the transmission end of the beam splitter 1102, such as... Figure 5 The optical path shown includes a beam splitter 1102 that allows light entering the first lens assembly 110 to be transmitted to the image plane 1105, thereby achieving tilted imaging.

[0068] In this embodiment, a series of lenses and optical elements are first used to achieve tilted imaging of the object 300 on the working surface 200. Furthermore, the first lens assembly 110 employs a double telecentric Sham lens, where the first lens 111, second lens 112, third lens 113, fourth lens 114, and fifth lens 115 constitute an object-side telecentric lens. Based on this, a beam splitter 1102 is placed between the fifth lens 115 and the aperture stop 1103, and the first coaxial light source 1101 is positioned... At the reflective end of the beam splitter 1102, the illumination light emitted by the first coaxial light source 1101, after reflection by the beam splitter 1102 and processing by the object-side telecentric lens, can project illumination light with low telecentricity. This illumination light uniformly illuminates the object 300, ensuring uniform brightness distribution when the first coaxial light source 1101 provides supplementary illumination to the object 300. This guarantees high brightness uniformity when the second lens assembly 120 images under the supplementary illumination of the first coaxial light source 1101, thereby better ensuring the accuracy of the detection results. The second lens assembly 120 operates similarly and will not be described in detail here.

[0069] To ensure clear imaging during tilted shooting, this application further designs the focal lengths of each lens accordingly. Specifically, the effective focal length of the first lens assembly 110 as a whole is f, the focal length of the first lens 111 is f1, the focal length of the second lens 112 is f2, the focal length of the third lens 113 is f3, the focal length of the fourth lens 114 is f4, the focal length of the fifth lens 115 is f5, the focal length of the sixth lens 116 is f6, the focal length of the seventh lens 117 is f7, the focal length of the eighth lens 118 is f8, and the focal length of the ninth lens 119 is f9, which satisfy the following relationship:

[0070] 0.01<|f1 / f|<0.07; 0<|f2 / f|<0.04; 0.01<|f3 / f|<0.05; 0<|f4 / f|<0.04; 0<|f5 / f |<0.04; 0.01<|f6 / f|<0.04; 0<|f7 / f|<0.03; 0<|f8 / f|<0.035; 0.01<|f9 / f|<0.06.

[0071] Similarly, the second lens assembly 120 also satisfies the above relationship.

[0072] Taking product defect detection as an example, in actual inspection operations, the products produced may have different types of defects. Some are relatively large defects, such as obvious damage or dents on the product surface, while others are minor defects, such as small scratches on the product surface.

[0073] To address this issue and enable simultaneous inspection of both the overall product and its details in a single photograph, this application further proposes an implementation method, which can be found in the following details. Figure 6 The beam splitter 1102 is a dichroic prism 1106, and the reflecting end of the dichroic prism 1106 includes a first reflecting end and a second reflecting end. The first lens assembly 110 includes a front lens group 131, a first rear lens group 1321, and a second rear lens group 1322.

[0074] The front lens group 131 includes a first lens 111, a second lens 112, a third lens 113, a fourth lens 114, a fifth lens 115, and a dichroic prism 1106. Both the first rear lens group 1321 and the second rear lens group 1322 include a sixth lens 116, a seventh lens 117, an eighth lens 118, a ninth lens 119, a parallel plate 1104, and an image plane 1105. However, the eighth lens 118 and the ninth lens 119 in the second rear lens group 1322 do not form the third cemented lens 1189.

[0075] like Figure 7 As shown in the optical path, the rear group 1321 of the first lens is located at the transmission end of the dichroic prism 1106. An aperture 1103 is provided between the rear group 1321 of the first lens and the front group 131 of the lens. The rear group 1321 of the first lens and the front group 131 of the lens form the first optical lens group. The dichroic prism 1106 is used to allow light of a predetermined wavelength in the light entering the front group 131 to be transmitted to the image plane 1105 of the rear group 1321 of the first lens.

[0076] The imaging principle of the first optical lens group is as follows: Figure 8 As shown, the angle between the object plane 310 and the principal plane of the lens is... The angle between the image plane 1105 and the principal plane of the lens is β1, and β1 must satisfy the following relationship: Where PMAG1 represents the magnification of the first optical lens group. In the specific example shown in the figure... The angles between the object plane 310 and the image plane 1105 and the optical axis are both 70°, which does not constitute a limitation on specific parameters.

[0077] like Figure 7 As shown in the optical path diagram, the rear group 1322 of the second lens is located at the first reflecting end of the dichroic prism 1106. An aperture stop 1103 is provided between the rear group 1322 and the front group 131 of the second lens. The rear group 1322 and the front group 131 of the second lens form a second optical lens group. The dichroic prism 1106 is also used to reflect light of a predetermined wavelength from the light entering the front group 131 to reach the image plane 1105 of the rear group 1322. The magnification of the first optical lens group and the second optical system group is different.

[0078] The imaging principle of the second optical lens group is as follows: Figure 9As shown, the image plane 1105 in the second optical lens group is mirrored with respect to the reflecting surface of the dichroic prism 1106 as the mirror image plane 1105', and the angle between the object plane 310 and the principal plane of the lens is... The angle between the image plane 1105 and the principal plane of the lens is β2, and β2 must satisfy the following relationship: Where PMAG2 represents the magnification of the second optical lens group. In the specific example shown in the figure... β2 = 14.3°, meaning the angle between the object plane 310 and the optical axis is 70°, and the angle between the mirror image plane 1105' and the optical axis is 75.7°.

[0079] like Figure 6 and Figure 7 As shown, in the first lens assembly 110, a first coaxial light source 1101 is disposed at the second reflective end of a dichroic prism 1106. The dichroic prism 1106 is used to reflect light of a first predetermined wavelength from the illumination light output by the first coaxial light source 1101 along the optical path of the front lens group 131 and finally output it from the front lens group 131. Please further combine Figure 3 The light of the first predetermined wavelength output from the front lens group 131 of the first lens assembly 110 is reflected by the surface of the subject 300 and enters the front lens group 131 of the second lens assembly 120. Then, it can be transmitted through the dichroic prism 1106 in the second lens assembly 120 and reach the rear lens group 1321 in the second lens assembly 120 to improve the brightness of the image of the rear lens group 1321. Alternatively, it can be reflected by the dichroic prism 1106 in the second lens assembly 120 and reach the rear lens group 1322 in the second lens assembly 120 to improve the brightness of the image of the rear lens group 1322.

[0080] Similarly, in the second lens assembly 120, the second coaxial light source 1201 is disposed at the second reflective end of the dichroic prism 1106. The dichroic prism 1106 is used to reflect the light of the second predetermined wavelength in the illumination light output by the second coaxial light source 1201 along the optical path of the front lens group 131 and finally output it from the front lens group 131. The light of the second predetermined wavelength output from the front lens group 131 in the second lens assembly 120 is reflected by the surface of the subject 300 and enters the front lens group 131 in the first lens assembly 110. Then, it can be transmitted through the dichroic prism 1106 in the first lens assembly 110 to reach the first rear lens group 1321 in the first lens assembly 120 to improve the brightness of the image of the first rear lens group 1321. Alternatively, it can be reflected through the dichroic prism 1106 in the first lens assembly 110 to reach the second rear lens group 1322 in the first lens assembly 110 to improve the brightness of the image of the second rear lens group 1322.

[0081] It should be noted that the first predetermined wavelength is different from the second predetermined wavelength to ensure that the light output by the first coaxial light source 1101 is not reflected by the beam splitter 1106 onto the second coaxial light source 1102 after being reflected by the surface of the subject 300 and entering the second lens assembly 120, because the light reflected onto the second coaxial light source 1102 cannot achieve the effect of increasing brightness.

[0082] Specifically, the coatings on the dichroic prisms 1106 in the first lens assembly 110 and the second lens assembly 120 corresponding to the second reflective end can be set differently, so that the dichroic prisms 1106 in the first lens assembly 110 reflects light of the first predetermined wavelength to its second reflective end, and the dichroic prisms 1106 in the second lens assembly 120 reflects light of the second predetermined wavelength to its second reflective end.

[0083] In this embodiment, based on the shared front lens group 131, the principle of transmitting and reflecting light of different wavelengths using the dichroic prism 1106 is utilized. This not only reflects and coaxially outputs the illumination light output from the first coaxial light source 1101, but also transmits and reflects light of different wavelengths into the first rear lens group 1321 and the second rear lens group 1322 respectively. Since the magnification of the first rear lens group 1321 and the second rear lens group 1322 is different, multiple images with different magnifications can be formed in a single shot. The overall product can be visually inspected through the image with a smaller magnification, while the details on the product can be visually inspected through the image with a larger magnification, thereby achieving a more comprehensive inspection of the product and ensuring the reliability of the inspection results.

[0084] In some embodiments, the first optical lens group (including the front lens group 131 and the rear lens group 1321) has a magnification PMAG1 = -1 and an aperture number F.NO1 = 8.5. The second optical lens group (including the front lens group 131 and the rear lens group 1322) has a magnification PMAG2 = -0.7 and an aperture number F.NO2 = 8.5.

[0085] Furthermore, such as Figure 10 As shown, in the rear group 1321 of the first lens, the parallel plate 1104 is aligned with the optical axis of the rear group 1321. Figure 10 The angle α1 between the midpoints (as shown by the dashed line) is 90.657°; Figure 11 As shown, in the second lens rear group 1322, the parallel plate 1104 is aligned with the optical axis of the first lens rear group 1321. Figure 11 The included angle α2 between the two points (shown by the dashed midpoint) is 91.496°. The purpose of this setting is to correct optical astigmatism by tilting the parallel plate 1104.

[0086] The first optical lens group and the second optical lens group can be configured according to the following parameters: 0.02 < f c / f a < 0.06; 0.02 < f d / f b < 0.05. Where f a is the effective focal length of the first optical lens group, f b is the effective focal length of the second optical lens group, f c is the effective focal length of the rear group 1321 of the first lens, f d is the effective focal length of the rear group 1322 of the second lens.

[0087] For the materials of the lenses in the front group 131 of the lens, they can be configured according to the following parameters: 1.45 < Nd1 < 1.75, 50 < Vd1 < 75; 1.60 < Nd2 < 2.00, 25 < Vd2 < 50; 1.50 < Nd3 < 1.70, 40 < Vd3 < 75; 1.40 < Nd4 < 1.75, 50 < Vd4 < 75; 1.65 < Nd5 < 2.00, 35 < Vd5 < 55. Where Nd1, Nd2, Nd3, Nd4 and Nd5 are the refractive indices of the first lens 111, the second lens 112, the third lens 113, the fourth lens 114 and the fifth lens 115 respectively, and Vd1, Vd2, Vd3, Vd4 and Vd5 are the Abbe numbers of the first lens 111, the second lens 112, the third lens 113, the fourth lens 114 and the fifth lens 115 respectively.

[0088] For the materials of the lenses in the rear group 1321 of the first lens, they can be configured according to the following parameters: 1.80 < Nd a6 < 2.00, 20 < Vd a6 < 40; 1.40 < Nd a7 < 1.75, 20 < Vd a7 < 45; 1.70 < Nd a8 < 2.00, 40 < Vd a8 < 65; 1.55 < Nd a9 < 1.80, 18 < Vd a9 < 40. Where Nd a6 , Nd a7 , Nd a8 and Nd a9 are the refractive indices of the sixth lens 116, the seventh lens 117, the eighth lens 118 and the ninth lens 119 in the rear group 1321 of the first lens respectively, and Vd a6 , Vd a7 , Vd a8 and Vd a9These are the Abbe numbers of the sixth lens 116, the seventh lens 117, the eighth lens 118, and the ninth lens 119 in the rear group 1321 of the first lens, respectively.

[0089] The materials for each lens in the rear group 1322 of the second lens can be configured according to the following parameters: 1.80 <Nd b6 <2.00, 20 <Vd b6 <40; 1.50 <Nd b7 <1.75, 20 <Vd b7 <45; 1.80 <Nd b8 <2.00, 40 <Vd b8 <65; 1.45 <Nd b9 <1.72, 18 <Vd b9 <40. Among them, Nd b6 、Nd b7 、Nd b8 and Nd b9 The refractive indices, Vd, of the sixth lens 116, seventh lens 117, eighth lens 118, and ninth lens 119 in the rear group 1322 of the second lens are respectively. b6 Vd b7 Vd b8 and Vd b9 These are the Abbe numbers of the sixth lens 116, the seventh lens 117, the eighth lens 118, and the ninth lens 119 in the rear group 1322 of the second lens, respectively.

[0090] Furthermore, regarding the dimensions of each lens in the front group 131, the radii of curvature of the front surface (the surface facing the object plane 310, hereinafter the same) and the rear surface (the surface facing the image plane 1105, hereinafter the same) of the first lens 111 are R, respectively. 11 and R 12 The center thickness along the optical axis is d1, and the same parameters of the second lens 112 are R. 21 R 22 And d2, and so on for the other lenses, these parameters can be configured as follows: 30mm <R 11 <70mm, R 12 For infinity, 4mm <d1<7mm;-30mm<R 21 <-10mm, -120mm <R 22 <-80mm, 4mm <d2<7mm;-120mm<R 31 =R 22 -80mm, -30mm <R 32 <-10mm, 7mm <d3<8.8mm;25mm<R 41 <55mm, -45mm <R 42<-20mm, 6.5mm <d4<8.5mm;-45mm<R 51 =R 42 <-20mm, 320mm <R 52 <400mm, 6.5mm <d5<8.5mm。

[0091] Regarding the dimensions of each lens in the rear group 1321 of the first lens, the radii of curvature of the front and rear surfaces of the sixth lens 116 are R and R, respectively. a61 and R a62 The center thickness along the optical axis is d a6 The same applies to the other lenses; these parameters can be configured as follows: 45mm <R a61 <85mm, -180mm <R a62 <-130mm, 6.5mm <d a6 <8.5mm; -40mm <R a71 -20mm, -40mm <R a72 <-20mm, 2mm <d a7 <4mm; -390mm <R a81 -320mm, -35mm <R a82 <-10mm, 6mm <d a8 <8.5mm; -35mm <R a91 =R a82 -10mm, -65mm <R a92 <-30mm, 2mm <d a9 <4mm.

[0092] Regarding the dimensions of each lens in the rear group 1322 of the second lens, the radii of curvature of the front and rear surfaces of the sixth lens 116 are R and R, respectively. b61 and R b62 The center thickness along the optical axis is d b6 The same applies to the other lenses; these parameters can be configured as follows: 50mm <R b61 <85mm, -150mm <R b62 <-100mm, 6.5mm <d b6 <8.5mm; -35mm <R b71 <-10mm, 20mm <R b72 <40mm, 2mm <d b7 <4mm; 200mm <R b81 <250mm, -40mm <R b82 <-20mm, 6.5mm <d b8 <8mm; -40mm <R b91 <-10mm, -60mm <Rb92 <-30mm, 2mm <d b9 <4mm.

[0093] The working distance between the first lens assembly 110 and the object plane 310 along the optical axis can be set to any value within the range of 100mm to 150mm.

[0094] In one alternative example, the parameters of each lens in the front lens group 131, the first rear lens group 1321, and the second rear lens group 1322 can be configured as follows:

[0095] Table 1: Front Group Parameters of Lens

[0096]

[0097] Table 2: Parameters of the rear group of the first lens

[0098]

[0099] Table 3: Parameters of the Rear Group of the Second Lens

[0100]

[0101]

[0102] like Figure 12 As shown in the figure, the modulation transfer function (MTF) of the first optical lens group is plotted. The horizontal axis represents resolution in line pairs / mm, and the vertical axis represents contrast in the range of 0-1. The average MTF value for each field of view has a contrast greater than 0.3 at a resolution of 95 line pairs / mm, and the entire MTF curve is compact, indicating that the lens has a high resolution. The magnification of the first optical lens group is -1x, thus the object-side optical resolution of the first optical lens group can reach 5.2μm.

[0103] like Figure 13 As shown in the figure, the modulation transfer function (MTF) plot of the second optical lens group is displayed. The average MTF value for each field of view has a contrast greater than 0.3 at a resolution of 95 line pairs / mm, and the entire MTF curve is close to the diffraction-limited curve, indicating that the lens has a very high resolution. The magnification of the second optical lens group is -0.7x, thus the object-side optical resolution of the second optical lens group can reach 7.5μm.

[0104] Therefore, on the same working surface 200, the first optical lens group can meet the high-precision detection requirements, while the second optical lens group can meet the large field-of-view detection requirements.

[0105] Please see Figure 14 and Figure 15The figure shows a system point diagram of the first optical lens group and the second optical lens group, respectively. From Figure 14 As can be seen, for the first optical lens group, at a wavelength of 588nm, the Airy disk radius is 6.125μm, the blur radius at the center of the field of view is 1.671μm, and the blur radius at the edge of the field of view is 2.544μm. The blur radius across the entire field of view is smaller than the Airy disk radius, achieving good imaging results. Figure 15 As can be seen, for the second optical lens group, at a wavelength of 588nm, the Airy disk radius is 6.111μm, the blur disk radius at the center of the field of view is 2.592μm, and the blur disk radius at the edge of the field of view is 1.469μm. The blur disk radius across the entire field of view is smaller than the Airy disk radius, achieving good imaging results.

[0106] Please refer to further information. Figure 16 and Figure 17 The figure shows the distortion of the first and second optical lens groups, respectively. Figure 16 As can be seen, for the first optical lens group, at a wavelength of 588nm, the maximum distortion across the entire field of view is 0.074%, and the telecentricity is less than 0.1°, indicating that the lens exhibits very low distortion and low telecentricity. Low distortion means that the degree of distortion in the image is very small, providing almost distortion-free imaging and helping to maintain image accuracy and reliability. Low telecentricity enables clear imaging over a wide range. Figure 17 As can be seen, for the second optical lens group, at a wavelength of 588nm, the maximum distortion across the entire field of view is 0.0548%, and the telecentricity is less than 0.1°, indicating that the lens exhibits very low distortion and low telecentricity. Low distortion means that the degree of distortion in the image is very small, providing almost distortion-free imaging and helping to maintain image accuracy and reliability. Low telecentricity enables clear imaging over a wide range.

[0107] Further, please refer to Figure 18 The visual inspection system 100 also includes a third lens assembly 130, which is configured to face the work surface 200 vertically. The third lens assembly 130 is used to take a frontal shot of the object 300 on the work surface 200 to achieve visual inspection of the front of the object 300.

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way.

Claims

1. A visual inspection system for capturing images of objects on a work surface, characterized in that, include: A first lens assembly and a second lens assembly, both of which are SAM lenses; Both the first lens assembly and the second lens assembly are configured to be tilted toward the working surface, and the optical axes of the first lens assembly and the second lens assembly are mirror-symmetrical with respect to the normal of the working surface. The first lens assembly is equipped with a first coaxial light source, and the second lens assembly is equipped with a second coaxial light source; The first coaxial light source is used to provide supplementary lighting when the second lens assembly is shooting, so that the light emitted from the first lens assembly by the first coaxial light source is reflected by the surface of the object being photographed on the working surface and then enters the second lens assembly. The second coaxial light source is used to provide supplemental lighting when the first lens assembly is shooting, so that the light emitted from the second lens assembly by the second coaxial light source is reflected by the surface of the subject and then enters the first lens assembly.

2. The visual inspection system according to claim 1, characterized in that, The optical axis of the first lens assembly is configured such that the angle between it and the normal to the working surface is θ, where 0° < θ ≤ 30°.

3. The visual inspection system according to claim 1, characterized in that, Both the first lens assembly and the second lens assembly are double telecentric SAM lenses. The first lens assembly includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a beam splitter, an aperture stop, a sixth lens, a seventh lens, an eighth lens, a ninth lens, a parallel plate, and an image plane arranged sequentially along its optical path direction. The image plane is inclined relative to the optical axis of the first lens assembly. Wherein, the first lens, the third lens, the fourth lens, the sixth lens and the eighth lens are all positive lenses, and the second lens, the fifth lens, the seventh lens and the ninth lens are all negative lenses; The second lens and the third lens are bonded together to form a first cemented lens, the fourth lens and the fifth lens are bonded together to form a second cemented lens, and the eighth lens and the ninth lens are bonded together to form a third cemented lens. The beam splitter has a reflective end and a transmissive end. The first coaxial light source is disposed at the reflective end of the beam splitter. The beam splitter is used to reflect the illumination light output by the first coaxial light source along the optical path of the first lens assembly and finally output it from the first lens assembly. The aperture is disposed at the transmission end of the beam splitter, and the beam splitter is also used to allow light entering the first lens assembly to be transmitted to the image plane; The second lens assembly has the same structure as the first lens assembly.

4. The visual inspection system according to claim 3, characterized in that, The effective focal length of the first lens assembly as a whole is f, the focal length of the first lens is f1, the focal length of the second lens is f2, the focal length of the third lens is f3, the focal length of the fourth lens is f4, the focal length of the fifth lens is f5, the focal length of the sixth lens is f6, the focal length of the seventh lens is f7, the focal length of the eighth lens is f8, and the focal length of the ninth lens is f9, which satisfy the following relationship: 0.01 < |f1 / f| < 0.07; 0 < |f² / f| < 0.04; 0.01 < |f3 / f| < 0.05; 0 < |f4 / f| < 0.04; 0 < |f5 / f| < 0.04; 0.01 < |f6 / f| < 0.04; 0 < |f7 / f| < 0.03; 0 < |f8 / f| < 0.035; 0.01 < |f9 / f| < 0.

06.

5. The visual inspection system according to claim 3, characterized in that, The beam splitter is a dichroic prism, and the reflective end of the dichroic prism includes a first reflective end and a second reflective end. Both the first lens assembly and the second lens assembly include a front lens group, a first rear lens group, and a second rear lens group; The front lens group includes the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the dichroic prism; Both the first rear lens group and the second rear lens group include the sixth lens, the seventh lens, the eighth lens, the ninth lens, the parallel plate, and the image plane. The eighth lens and the ninth lens in the second rear lens group do not form the third cemented lens. The first rear lens group is located at the transmission end of the dichroic prism. The aperture is provided between the first rear lens group and the front lens group. The first rear lens group and the front lens group form a first optical lens group. The dichroic prism is used to allow light of a predetermined wavelength in the light entering the front lens group to be transmitted to the image plane in the first rear lens group. The second rear lens group is located at the first reflecting end of the dichroic prism. The aperture is provided between the second rear lens group and the front lens group. The second rear lens group and the front lens group form a second optical lens group. The dichroic prism is also used to reflect light of a predetermined wavelength in the light entering the front lens group to reach the image plane in the second rear lens group. The magnification of the rear group of the first lens is different from that of the rear group of the second lens; In the first lens assembly, the first coaxial light source is disposed at the second reflective end of the dichroic prism. The dichroic prism is used to reflect the light of a first predetermined wavelength in the illumination light output by the first coaxial light source along the optical path of the front lens group and finally output it from the front lens group. The light of the first predetermined wavelength output from the front lens group is reflected by the surface of the subject and first enters the front lens group in the second lens assembly. After being transmitted by the dichroic prism in the second lens assembly, it reaches the first rear lens group in the second lens assembly, or after being reflected by the dichroic prism in the second lens assembly, it reaches the second rear lens group in the second lens assembly. In the second lens assembly, the second coaxial light source is disposed at the second reflective end of the dichroic prism. The dichroic prism is used to reflect the light of the second predetermined wavelength in the illumination light output by the second coaxial light source along the optical path of the front lens group and finally output it from the front lens group. The light of the second predetermined wavelength output from the front lens group is reflected by the surface of the subject and first enters the front lens group of the first lens assembly. After being transmitted by the dichroic prism in the first lens assembly, it reaches the first rear lens group of the first lens assembly, or after being reflected by the dichroic prism in the first lens assembly, it reaches the second rear lens group of the first lens assembly.

6. The visual inspection system according to claim 5, characterized in that, The magnification of the first optical lens group is PMAG1, and the aperture number of the first optical lens group is F.NO1, where PMAG1 = -1 and F.NO1 = 8.5; The magnification of the second optical lens group is PMAG2, and the aperture number of the first optical lens group is F.NO2, where PMAG2 = -0.7 and F.NO2 = 8.

5.

7. The visual inspection system according to claim 5, characterized in that, In the rear group of the first lens, the angle between the parallel plate and the optical axis of the rear group of the first lens is 90.657°. In the rear group of the second lens, the angle between the parallel plate and the optical axis of the rear group of the second lens is 91.496°.

8. The visual inspection system according to claim 5, characterized in that, The effective focal length of the first optical lens group is f a The effective focal length of the second optical lens group is f. b The effective focal length of the rear element of the first lens is f. c The effective focal length of the rear element of the second lens is f. d It satisfies the following relationship: 0.02<f c / f a <0.06; 0.02<f d / f b <0.05。 9. The visual inspection system according to claim 5, characterized in that, The refractive indices of the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are Nd1, Nd2, Nd3, Nd4, and Nd5, respectively, and their Abbe numbers are Vd1, Vd2, Vd3, Vd4, and Vd5, respectively, satisfying the following relationship: 1.45 <Nd1<1.75,50<Vd1<75; 1.60 <Nd2<2.00,25<Vd2<50; 1.50 <Nd3<1.70,40<Vd3<75; 1.40 <Nd4<1.75,50<Vd4<75; 1.65 <Nd5<2.00,35<Vd5<55; In the rear group of the first lens, the refractive indices of the sixth lens, the seventh lens, the eighth lens, and the ninth lens are Nd, respectively. a6 、Nd a7 、Nd a8 and Nd a9 The Abbe numbers are Vd a6 Vd a7 Vd a8 and Vd a9 It satisfies the following relationship: 1.80<Nd a6 <2.00,20<Vd a6 <40; 1.40<Nd a7 <1.75,20<Vd a7 <45; 1.70<Nd a8 <2.00,40<Vd a8 <65; 1.55<Nd a9 <1.80,18<Vd a9 <40; In the rear group of the second lens, the refractive indices of the sixth lens, the seventh lens, the eighth lens, and the ninth lens are Nd, respectively. b6 、Nd b7 、Nd b8 and Nd b9 The Abbe numbers are Vd b6 Vd b7 Vd b8 and Vd b9 It satisfies the following relationship: 1.80<Nd b6 <2.00,20<Vd b6 <40; 1.50<Nd b7 <1.75,20<Vd b7 <45; 1.80<Nd b8 <2.00,40<Vd b8 <65; 1.45<Nd b9 <1.72,18<Vd b9 <40。 10. The visual inspection system according to any one of claims 1-9, characterized in that, The visual inspection system also includes a third lens assembly configured to face the working surface perpendicularly.

Images