CN219996902U - Optical system for detecting appearance defects - Google Patents

Abstract

The utility model provides an optical system for detecting appearance defects, which can accurately detect the appearance defects of mirror products. The system comprises an imaging assembly, a lens assembly and a light source assembly; the imaging assembly, the lens assembly and the light source assembly are sequentially arranged on one side of a product to be detected, and a first central axis of the light source assembly is intersected with and perpendicular to a second central axis of the lens assembly; the light source component comprises a light source, a collimating lens and a plane lens; the light source comprises at least two sub-light sources positioned at different positions, the at least two sub-light sources emit light with at least two wavelengths, and the light emitted by the first sub-light source positioned at the focal length position of the collimating lens is used for vertically irradiating the surface of a product to be detected through the collimating lens and the plane lens; light emitted by each sub-light source is incident on the surface of a product to be detected and enters the imaging component through reflection; the imaging component is used for shooting the surface of the product to be detected through the lens component so as to acquire an image for detecting the appearance defects.

Description

Optical system for detecting appearance defects

Technical Field

The utility model relates to the field of product appearance detection, in particular to an optical system for appearance defect detection.

Background

The mirror product has the appearance defects of weak unevenness, impact scratch, dirt and the like in the production process. The current scheme for detecting the appearance defects of the mirror product mainly comprises the following steps: 1. the inspector observes whether the surface of the mirror product has appearance defects or not; 2. and arranging an area array camera provided with a telecentric lens on a detection site, and carrying out appearance detection on an image shot on the surface of the mirror product through the area array camera.

In the scheme, the manual detection of the appearance defects of the mirror surface products is low in efficiency, and the problem of missed detection can be caused by negligence of people. When the area-array camera is used for detecting the appearance defects of the mirror product, the area-array camera cannot distinguish the weak uneven touch scratches and dirt according to the images, and the accuracy of the appearance detection can be affected.

Accordingly, it is an urgent problem to provide an optical system for detecting an appearance defect of a mirror product with high accuracy.

Disclosure of Invention

The utility model provides an optical system for detecting appearance defects, which can accurately detect the appearance defects of mirror products.

In a first aspect, an optical system for appearance defect detection is provided, comprising an imaging assembly, a lens assembly, and a light source assembly;

the imaging assembly, the lens assembly and the light source assembly are sequentially arranged on one side of a product to be tested, the imaging assembly is coaxial with the lens assembly, and a first central axis of the light source assembly is intersected with and perpendicular to a second central axis of the lens assembly;

the light source assembly comprises a light source, a collimating lens and a plane lens which are sequentially arranged in the direction of the first central axis;

the light source comprises at least two sub-light sources positioned at different positions, the at least two sub-light sources emit light with at least two wavelengths, the at least two sub-light sources comprise a first sub-light source positioned at the focal length position of the collimating lens, and the light emitted by the first sub-light source is used for vertically irradiating the surface of the product to be detected through the collimating lens and the plane lens;

the light emitted by each sub-light source is reflected on the surface of the product to be detected through the plane lens after passing through the collimating lens, and sequentially passes through the plane lens and the lens assembly to enter the imaging assembly after being reflected on the surface of the product to be detected;

the imaging component is used for shooting the surface of the product to be detected through the lens component so as to acquire an image for detecting the appearance defects.

In one example, if the surface of the product to be measured is parallel to a tangential plane of the end surface of the lens assembly facing away from the imaging assembly, an included angle between a plane of the planar lens, which is close to the collimating lens, and the first central axis direction is 45 degrees.

In one example, the at least two sub-light sources further include a second sub-light source, the wavelength of light emitted by the second sub-light source is different from the wavelength of light emitted by other sub-light sources, a straight line where the second sub-light source and the first sub-light source are located is perpendicular to a plane where the surface of the product to be tested is located, and the second sub-light source is located between the first sub-light source and the product to be tested.

In one example, the at least two sub-light sources further include a third sub-light source, the wavelength of light emitted by the third sub-light source is different from the wavelength of light emitted by other sub-light sources, a straight line where the third sub-light source and the first sub-light source are located is perpendicular to a plane where the surface of the product to be measured is located, and the third sub-light source is located between the first sub-light source and the lens assembly.

In one example, the second sub-light source is spaced apart from the first sub-light source by 2 millimeters, and the third sub-light source is spaced apart from the first sub-light source by 2 millimeters.

In one example, each of the sub-light sources includes a light emitting diode and a diaphragm having a size of less than or equal to 3mm×3mm.

In one example, the refractive index of the collimating lens is 1.491, the abbe number of the collimating lens is 55.310, the refractive index of the planar lens is 1.517, and the abbe number of the planar lens is 64.167.

In one example, the ratio of the transmittance to the reflectance of the planar lens is 5:5.

In one example, a distance between an end surface of the planar lens, which is close to the product to be measured, and a surface of the product to be measured is 30±5mm, and the planar lens is coaxial with the lens assembly.

In one example, the lens assembly includes a 35mm fixed focus lens, a distance between a lower surface of the 35mm fixed focus lens and a surface of the product to be measured is 200±5mm, and a focal length of the collimating lens is 35mm.

According to the optical system provided by the embodiment of the utility model, at least two wavelengths of light are emitted through the light source, wherein the light emitted by the first sub-light source positioned at the focal length of the collimating lens is used for being parallelly incident to the plane lens through the collimating lens, so that the light emitted by the first sub-light source can be perpendicularly irradiated to the surface of the product to be measured by simply adjusting the angle between the plane of the plane lens and the plane of the product to be measured (namely, adjusting the included angle alpha between the plane of the plane lens, which is close to the collimating lens, and the direction of the first central axis L1 and the placement angle of the product to be measured). The light of the other sub-light sources except the first sub-light source is not in the focal length position of the collimating lens, so that the light passes through the collimating lens and the plane lens and irradiates the surface of the product to be measured at other angles except the vertical angle. Because the surface of the product to be measured is a mirror surface, if the mirror surface is flat, the light emitted by the first sub-light source can be reflected to the lens component and the imaging component; if the appearance of the product to be detected has defects, the mirror surface is uneven, and light emitted by other sub-light sources can be reflected to the lens assembly and the imaging assembly. Therefore, under the condition that the color of the light changes due to different wavelengths of the light, whether the surface of the product to be detected has defects or not can be efficiently and accurately judged according to the color change in the image of the surface of the product to be detected, and if the surface of the product to be detected has defects, the position of the defects is determined according to the acquired image of the surface of the product to be detected.

Drawings

In order to more clearly illustrate the technical solution of the present utility model, the drawings that are needed in the embodiments will be briefly described below, and it will be obvious to those skilled in the art that other drawings can be obtained from these drawings without inventive effort.

FIG. 1 is a schematic diagram of an optical system for appearance defect detection according to an exemplary embodiment of the present utility model;

FIG. 2 is a schematic view of an exemplary optical path provided by an exemplary embodiment of the present utility model;

FIG. 3 is a schematic view of an exemplary light source structure according to an exemplary embodiment of the present utility model;

fig. 4 is a graph showing actual measurement of a different color defect obtained by using the optical system provided by the utility model.

Detailed Description

The following description of the embodiments of the present utility model will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present utility model, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

In the description of the present utility model, it should be noted that, directions or positional relationships indicated by terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., are based on directions or positional relationships shown in the drawings, are merely for convenience of description and simplification of description, and do not indicate or imply that the apparatus or element to be referred to must have a specific direction, be constructed and operated in the specific direction, and thus should not be construed as limiting the present utility model; the terms "first," "second," "third," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying relative importance, and furthermore, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "coupled," and the like are to be construed broadly, and may be fixedly coupled, detachably coupled, or integrally coupled, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present utility model will be understood in specific cases by those of ordinary skill in the art.

Fig. 1 is a schematic view of an optical system for detecting an appearance defect according to an exemplary embodiment of the present utility model, fig. 2 is a schematic view of an optical path according to an exemplary embodiment of the present utility model, fig. 3 is a schematic view of a light source according to an exemplary embodiment of the present utility model, and an optical system for detecting an appearance defect is described below with reference to fig. 1 to 3.

The embodiment of the utility model provides an optical system for detecting appearance defects, which comprises an imaging component 1, a lens component 2 and a light source component 3. Wherein, imaging module 1, camera lens subassembly 2 and light source subassembly 3 set gradually in one side of the product 4 that awaits measuring, imaging module 1 and camera lens subassembly 2 coaxial, the first central axis L1 of light source subassembly 3 and the crossing just perpendicular of camera lens subassembly's second central axis L2. The light source assembly 3 includes a light source 31, a collimator lens 32, and a plane lens 33, which are disposed in this order in the direction of the first central axis L1. The light source 31 comprises at least two sub-light sources at different positions, the at least two sub-light sources emit light of at least two wavelengths, the at least two sub-light sources comprise a first sub-light source 311 at a focal position of the collimator lens 32, and the light emitted by the first sub-light source 311 is used for perpendicularly irradiating the surface of the product 4 to be measured through the collimator lens 32 and the planar lens 33. The light emitted by each sub-light source is reflected by the plane lens 33 on the surface of the product 4 to be measured after passing through the collimating lens 32, and sequentially passes through the plane lens 33 and the lens assembly 2 to enter the imaging assembly 1 after being reflected by the surface of the product 4 to be measured. The imaging assembly 1 is used for photographing the surface of the product 4 to be tested to acquire an image for appearance defect detection.

In the optical system provided by the embodiment of the utility model, at least two wavelengths of light are emitted by the light source 31, wherein the light emitted by the first sub-light source 311 positioned at the focal length of the collimating lens 32 is used for being incident on the planar lens 33 in parallel by the collimating lens 32, so that the light emitted by the first sub-light source 311 can be vertically irradiated on the surface of the product 4 to be measured by adjusting the angle between the plane of the planar lens 33 and the plane of the surface of the product 4 to be measured (i.e. adjusting the angle α between the plane of the planar lens 33, which is close to the collimating lens 32, and the direction of the first central axis L1, and the placement angle of the product 4 to be measured). The light of the sub-light sources other than the first sub-light source 311 is not at the focal length of the collimator lens 32, and thus, passes through the collimator lens 32 and the plane lens 33, and then irradiates the surface of the product 4 to be measured at angles other than the vertical. Since the surface of the product 4 to be measured is a mirror surface, if the mirror surface is flat, the light emitted by the first sub-light source 311 can be reflected to the lens component 2 and the imaging component 1; if the appearance of the product 4 to be measured has defects, the mirror surface is uneven, and the light emitted by other sub-light sources can be reflected to the lens component 2 and the imaging component 1. Therefore, under the condition that the color of the light changes due to different wavelengths of the light, whether the surface of the product 4 to be detected is defective or not can be efficiently and accurately judged according to the color change in the image of the surface of the product 4 to be detected obtained by the imaging component 1, and if the surface of the product 4 to be detected is judged to be defective, the position of the defect is determined according to the obtained image of the surface of the product 4 to be detected.

In one example, imaging assembly 1 captures images of the surface of product 4 under test using a 500-ten thousand high speed color camera, and lens assembly 2 includes a 35mm fixed focus lens, with imaging assembly 1 and lens assembly 2 assembled together. The 35mm fixed focus lens has the advantages of high focusing speed, stable imaging quality, fine and smooth picture, slight granular sense and accurate photometry, and is favorable for generating high-quality color images.

The 500-ten thousand high-speed color camera adopts a camera with the pixel size of 3.45um by 3.45um and the transmission frame number per second of more than or equal to 74fps, has good shooting effect on the product 4 to be detected moving on the conveyor belt, and is beneficial to the subsequent detection of images.

Illustratively, the collimating lens 32 employs a fresnel lens with a focal length of 35mm.

In one example, each of the above sub-light sources includes a light emitting diode and a diaphragm having a size of less than or equal to 3mm×3mm.

When the size of the lamp beads of the selected light-emitting diode is 3mm multiplied by 3mm, in order to save the material of the diaphragm, the maximum size of the diaphragm is set to be 3mm multiplied by 3mm, and the size of the diaphragm can be adjusted according to actual requirements.

In one example, if the surface of the product 4 to be measured is parallel to the tangential plane of the end surface of the lens assembly 2 facing away from the imaging assembly 1, the angle between the plane of the planar lens 33 adjacent to the collimating lens 32 and the direction of the first central axis L1 is 45 degrees.

The included angle α is, for example, 44.9 degrees, 45 degrees, or 45.1 degrees.

As shown in the optical path of fig. 2, since the first sub-light source 311 is located at the focal length of the collimator lens 32, the light emitted from the first sub-light source 311 is refracted by the collimator lens and then is parallel incident to the plane lens 33. When the included angle α between the planar lens 33 and the direction of the first central axis L1 is 45 degrees or an angle close to 45 degrees, and the product 4 to be measured is placed horizontally (i.e., the surface of the product 4 to be measured is parallel to the tangential plane of the end surface of the lens assembly 2 facing away from the imaging assembly 1), the light emitted by the first sub-light source 311 is reflected by the planar lens 33 and then enters the surface of the product 4 to be measured at an angle of 90 degrees or an angle close to 90 degrees, so that the flat portion of the surface of the product 4 to be measured can reflect the light emitted by the first sub-light source 311 to the lens assembly and the imaging assembly, so that the flat portion of the surface of the product 4 to be measured can be clearly and accurately detected from the image acquired by the imaging assembly.

In one example, the at least two sub-light sources further include a second sub-light source 312, the wavelength of the light emitted by the second sub-light source 312 is different from the wavelength of the light emitted by the other sub-light sources, the straight line L3 of the second sub-light source 312 and the first sub-light source 311 is perpendicular to the plane of the surface of the product 4 to be tested, and the second sub-light source 312 is located between the first sub-light source 311 and the product 4 to be tested. In this example, the other sub-light sources refer to sub-light sources other than the second sub-light source.

As exemplarily shown in fig. 3, the second sub-light source 312 is located directly below the first sub-light source 311.

Illustratively, the wavelength of light emitted from the second sub-light source 312 is different from the wavelength of light emitted from the first sub-light source 311, and the colors of the two lights are different, or even if the colors of the two lights are the same, the saturation of the colors is different, that is, as long as the areas irradiated by the light of a plurality of different wavelengths can be distinguished on the image. For example, the color of the light emitted from the second sub-light source 312 is light red with low saturation, and the color of the light emitted from the first sub-light source 311 is dark red with high saturation. For another example, the color of the light emitted from the second sub-light source 312 is green, and the color of the light emitted from the first sub-light source 311 is red.

Illustratively, the first sub-light source 311 includes a light emitting diode and a red light stop, and the second sub-light source 312 includes a light emitting diode and a green light stop. Wherein, the red light diaphragm is loaded with the red light filter and only allows light with the wavelength of 630-650nm to pass through, and the green light diaphragm is loaded with the green light filter and only allows light with the wavelength of 540-560nm to pass through.

In the above example, the second sub-light source 312 is located on the straight line L3 where the first sub-light source 311 is perpendicular to the plane where the surface 4 of the product to be measured is located, so that the second sub-light source 312 and the first sub-light source 311 can be installed in a row, which can save the material of the back plate for installing the first sub-light source 311 and the second sub-light source 312, and can also inject more light into the collimating lens 32, so that the area where the light emitted by the second sub-light source 312 is incident on the surface of the product to be measured is larger, and the accuracy of detecting the appearance defect is improved.

Illustratively, the distance between the second sub-light source 312 and the first sub-light source 311 is 2mm, and accordingly, the light emitted from the second sub-light source 312 is incident on the surface of the product 4 to be measured at 96.52 degrees. If the surface of the product 4 to be measured is flat, excluding the weak diffuse reflection factor, most of the light emitted from the second sub-light source 312 cannot be reflected into the lens assembly, but is reflected into other directions; if the surface of the product 4 to be measured has a concave-convex surface, the concave-convex surface can reflect the light emitted from the second sub-light source 312 into the lens assembly. Thus, the concave-convex area of the product 4 to be measured can be accurately detected from the image taken by the imaging assembly 1. And if the surface of the product 4 to be detected is a mirror surface, the light emitted by at least two sub-light sources can be better reflected, so that the detection result of the image is more accurate.

Specifically, as shown in the optical path of fig. 2, the second sub-light source 312 is located directly below the first sub-light source 311, and the first parallel light 321 emitted by the second sub-light source 312 after passing through the collimating lens 32 has an included angle with the second parallel light emitted by the first sub-light source 311 after passing through the collimating lens 32, where the incident angle of the first parallel light is greater than the incident angle of the second parallel light. The angle of incidence of the first parallel light after being reflected by the planar lens 33 on the surface of the product 4 to be measured is 96.52 degrees.

It should be understood that the distance between the second sub-light source 312 and the first sub-light source 311 corresponds to the angle of incidence of the light emitted from the second sub-light source 312 on the surface of the product 4 to be measured. The distance between the second sub-light source 312 and the first sub-light source 311 can be set according to needs, which is not limited in the present utility model. When the interval is 2mm, the second sub-light source 312 is ensured to have a proper difference from 90 degrees when the angle of incidence to the surface of the product 4 to be measured is 96.52 degrees, so that the concave-convex area is detected. And because if the interval is too small can make the processing degree of difficulty promote greatly, consequently the interval is 2 millimeters when guaranteeing the detection effect for the processing degree of difficulty is unlikely to too big, thereby guaranteed machining efficiency. In addition, as the size of the interval influences the angle of incidence of the second sub-light source to the surface of the product 4 to be detected, the concave-convex degree of the concave-convex area which can be detected by different angles is different, and therefore, the size of the interval can be adjusted according to the detection requirement of the product 4 to be detected.

In one example, the at least two sub-light sources further include a third sub-light source 313, the wavelength of the light emitted by the third sub-light source 313 is different from the wavelength of the light emitted by the other sub-light sources, and a straight line between the third sub-light source 313 and the first sub-light source 311 is perpendicular to a plane where the surface of the product to be measured is located, so that the third sub-light source 313 is located on the straight line L3 and between the first sub-light source 311 and the lens assembly. In this example, the other sub-light sources refer to sub-light sources other than the third sub-light source.

Illustratively, as shown in fig. 3, the third sub-light source 313 is located directly above the first sub-light source 311.

In one possible design of the utility model, the light source may comprise only a first sub-light source and a second sub-light source; alternatively, in another possible design, the light source may comprise only a first sub-light source and a third sub-light source; alternatively, in another possible design, the light source may comprise a first sub-light source, a second sub-light source and a third sub-light source at the same time.

Of course, in addition to the first sub-light source, the light source provided by the utility model may further include other sub-light sources different from the second sub-light source and the third sub-light source, so long as the light emitted by the other sub-light sources can be reflected to the lens assembly and the imaging assembly when the appearance of the product to be tested is defective.

Illustratively, if the light sources include the first sub light source 311 and the second sub light source 312, the wavelengths of the light emitted from the third sub light source 313 are different from those of the light emitted from the first sub light source 311 and the second sub light source 312, the colors of the three lights are different, or even if the colors of the three lights are the same, the saturation of the colors is different, that is, as long as the areas irradiated by the light of a plurality of different wavelengths can be distinguished on the image. For example, the colors of the light emitted from the third sub-light source 313, the second sub-light source 312, and the first sub-light source 311 are red, but the saturation of the three is different. For another example, the color of the light emitted from the third sub-light source 313 is blue, the color of the light emitted from the second sub-light source 312 is green, and the color of the light emitted from the first sub-light source 311 is red.

Illustratively, the third sub-light source 313 comprises a light emitting diode and a blue light stop, wherein the blue light stop carries a blue filter allowing only light of wavelengths 460-480nm to pass through.

In the above example, if the third sub-light source 313 is located on the straight line L3, the light source includes the second sub-light source 312 and the third sub-light source 313, and since the third sub-light source 313, the first sub-light source 311 and the second sub-light source 312 can be installed in a row, not only the material of the back plate for installing the first sub-light source 311, the second sub-light source 312 and the third sub-light source 313 can be saved, but also more light can be injected into the collimating lens 32, so that the area of the light emitted by the third sub-light source 313, which is injected into the surface of the product to be detected, is larger, and the accuracy of detecting the appearance defect is improved.

Illustratively, the distance between the third sub-light source and the first sub-light source is 2mm, and accordingly, the light emitted from the third sub-light source 313 is incident on the surface of the product to be measured at 83.48 degrees. If the surface of the product 4 to be measured is flat, excluding the weak diffuse reflection factor, most of the light emitted from the third sub-light source 313 cannot be reflected into the lens assembly, but is reflected into other directions; if the surface of the product to be measured 4 has a concave-convex shape, the concave-convex surface can reflect the light emitted from the third sub-light source 313 into the lens assembly. Thus, the concave-convex area of the product 4 to be measured can be accurately detected from the image taken by the imaging assembly 1. And if the surface of the product 4 to be detected is a mirror surface, the light emitted by at least two sub-light sources can be better reflected, so that the detection result of the image is more accurate. When the interval is 2mm, it is ensured that the third sub-light source 313 is incident to the surface of the product 4 to be measured at an angle of 83.48 degrees, which can have a proper difference from 90 degrees, thereby detecting the concave-convex area. And because if the interval is too small can make the processing degree of difficulty promote greatly, consequently the interval is 2 millimeters when guaranteeing the detection effect for the processing degree of difficulty is unlikely to too big, thereby guaranteed machining efficiency. In addition, as the size of the interval influences the angle of incidence of the third sub-light source to the surface of the product 4 to be detected, the concave-convex degree of the concave-convex area which can be detected by different angles is different, and therefore, the size of the interval can be adjusted according to the detection requirement of the product 4 to be detected.

Specifically, as shown in the optical path of fig. 2, the third sub-light source 313 is located directly above the first sub-light source 311, and an included angle exists between the third parallel light emitted from the third sub-light source 313 after passing through the collimating lens 32 and the second parallel light 322 emitted from the first sub-light source 311 after passing through the collimating lens 32, and the incident angle of the third parallel light 323 is smaller than the incident angle of the second parallel light. After being reflected by the plane lens 33, the third parallel light is incident to the surface of the product 4 to be measured at an angle of 83.48 degrees.

In one example, the refractive index of the collimator lens 32 is 1.491, the abbe number of the collimator lens 32 is 55.310, the refractive index of the planar lens 33 is 1.517, and the abbe number of the planar lens 33 is 64.167.

Specifically, the refractive index is the ratio of the propagation speed of light in vacuum to the propagation speed of light in the medium, and is mainly used to describe the refractive power of materials to light, and the refractive indexes of different materials are different. The larger the refractive index, the stronger the refractive power of the material to light; conversely, the smaller the refractive index, the weaker the refractive power of the material to light. The Abbe number is an index indicating the dispersive power of the transparent medium; the smaller the Abbe number, the more severe the medium dispersion; conversely, the larger the Abbe number, the more slightly the dispersion of the medium.

It should be understood that by reasonably selecting the refractive index of the collimating lens 32 and the planar lens 33, the light emitted from the light source is reflected to the surface of the product 4 to be measured through a collimating lens 32 and a planar lens 33, and the light utilization rate can be improved. By reasonably selecting the Abbe numbers of the collimating lens 32 and the plane lens 33, the chromatic dispersion of the collimating lens 32 and the plane lens 33 on light can be reduced in the light transmission process, the single color of the illumination area of each wavelength on the surface of the product 4 to be detected is ensured, and the imaging effect of the surface of the product to be detected is improved.

In one example, the ratio of the transmittance to the reflectance of the planar lens 33 is 5:5.

It should be understood that the ratio of the transmittance and the reflectance of the planar lens 33 can be adjusted according to actual requirements.

In one example, the distance between the end surface of the planar lens 33 near the product 4 to be measured and the surface of the product 4 to be measured is 30±5mm, and the planar lens 33 is coaxial with the lens assembly 2, which is advantageous in that light transmitted from the planar lens 33 can be sufficiently incident into the lens assembly 2.

In one example, the lens assembly 2 comprises a 35mm fixed focus lens, and the distance between the lower surface of the 35mm fixed focus lens 2 and the surface of the product 4 to be measured is 200±5mm, at which distance the quality of the image obtained by the imaging assembly 1 is optimal.

In connection with the above embodiments and fig. 1 to 3 and tables one and two below, a specific embodiment is listed below. In the optical system provided by the embodiment of the utility model, a 500-ten-thousand high-speed camera 1 and a 35-mm fixed-focus lens 2 are assembled together. A light source component 3 is arranged below the 35mm fixed focus lens 2, and a product 4 to be tested is arranged below the light source component 3.

The light source assembly 3 includes a light source 31, a collimator lens 32 and a planar lens 33, wherein the distance between the end surface of the planar lens 33, which is close to the product 4 to be measured, and the surface of the product 4 to be measured is 30 + -5 mm, and the distance between the lower surface of the 35mm fixed focus lens 2 and the surface of the product 4 to be measured is 200 + -5 mm. The angle α between the plane of the planar lens 33 adjacent to the collimator lens 32 and the direction of the first central axis L1 is 45 degrees.

In one possible design, the physical parameters of the various elements involved in the optical path are as shown in table one:

list one

Face number	Radius of curvature (mm)	Thickness (mm)	Refractive index	Abbe number
					LED Aperture	Infinty	35
Finier lens	Infinty	1.5	1.491	55.310
					2	-19.000	85
MIRROR	Infinty	1	1.517	64.167
					IMA	Infinty	60

In table 1, the surface numbers are used to denote the surface numbers of the respective elements, LED Aperture denotes the surface of the diaphragm facing the collimator lens 32, finish lens denotes the surface of the collimator lens 32 facing the LED Aperture, 2 denotes the surface of the collimator lens 32 facing the planar lens 33, MIRROR denotes the surface of the planar lens 33 facing the collimator lens 32, and IMA denotes the image surface. The radius of curvature represents the degree of curvature of the lens surface, a positive value represents the surface curved to the image plane side, a negative value represents the surface curved to the object plane side, and Infiniy is infinity, i.e. plane; thickness represents the distance from the central axis of the current surface to the next surface, and the unit of curvature radius and thickness are millimeters (mm); in the refractive index column, the space represents that the current position is air, and the refractive index is 1; in the abbe number column, the space represents that the current position is air, and the abbe number is 0. It should be noted that the parameters of the camera, the lens, and the light source in table 1 may be adjusted according to the actual situation, and are not limited to the above.

In one possible design, the physical parameters of the collimating lens 32 are shown in the following table two:

watch II

Wherein the conic coefficient is less than-1 for hyperbolas, -1 for parabolas, -1 to 0 for ellipses, and 0 for spheres. The 2 nd and 4 th order terms are the 2 nd order term coefficient and the 4 th order term coefficient, respectively, in the refractive index distribution polynomial of the collimator lens 32.

The physical parameters of the collimating lens 32 can be adjusted according to the actual requirements.

As shown in fig. 3, in one example, the first sub-light source 311 emits red light, the second sub-light source 312 emits green light, and the third sub-light source 313 emits blue light. The first sub-light source 311 is located at the focal length position of the collimator lens 32, the second sub-light source 312 is located directly below the first sub-light source 311 with a pitch of 2mm, and the third sub-light source 313 is located directly above the first sub-light source 311 with a pitch of 2mm.

On the basis of the above embodiment, the red light emitted from the first sub-light source 311 is incident on the surface of the product 4 to be measured at 90 degrees, the green light emitted from the second sub-light source 312 is incident on the surface of the product 4 to be measured at 96.52 degrees, and the blue light emitted from the third sub-light source 313 is incident on the surface of the product 4 to be measured at 83.48 degrees. Three kinds of light are reflected to the fixed focus lens 2 through the surface of the product 4 to be detected, and the imaging of the imaging component 1 uses different colors to represent uneven surfaces. The surface with weak scratches detected based on the imaging of the imaging assembly 1 is shown in fig. 4, in which the weak scratches are represented by curves within a rectangular frame. The light reflected into the lens is weaker and the brightness is darker due to the smaller degree of the concave-convex of the weak scratches. Therefore, in the detected image with the weak scratches, the color and the luminance of the region of the weak scratches are greatly different from those of the surrounding region, so that the weak scratches in the image can be efficiently detected.

Note that the above is only a preferred embodiment of the present utility model and the technical principle applied. Those skilled in the art will appreciate that the utility model is not limited to the specific embodiments described herein, and that features of the various embodiments of the utility model may be partially or fully coupled or combined with each other and may be co-operated and technically driven in various ways. Various obvious changes, rearrangements, combinations and substitutions can be made by those skilled in the art without departing from the scope of the utility model. Therefore, while the utility model has been described in connection with the above embodiments, the utility model is not limited to the embodiments, but may be embodied in many other equivalent forms without departing from the spirit or scope of the utility model, which is set forth in the following claims.

Claims (10)

1. An optical system for detecting appearance defects is characterized by comprising an imaging assembly, a lens assembly and a light source assembly;

the imaging assembly, the lens assembly and the light source assembly are sequentially arranged on one side of a product to be tested, the imaging assembly is coaxial with the lens assembly, and a first central axis of the light source assembly is intersected with and perpendicular to a second central axis of the lens assembly;

the light source assembly comprises a light source, a collimating lens and a plane lens which are sequentially arranged in the direction of the first central axis;

the light source comprises at least two sub-light sources positioned at different positions, the at least two sub-light sources emit light with at least two wavelengths, the at least two sub-light sources comprise a first sub-light source positioned at the focal length position of the collimating lens, and the light emitted by the first sub-light source is used for vertically irradiating the surface of the product to be detected through the collimating lens and the plane lens;

the light emitted by each sub-light source is reflected on the surface of the product to be detected through the plane lens after passing through the collimating lens, and sequentially passes through the plane lens and the lens assembly to enter the imaging assembly after being reflected on the surface of the product to be detected;

the imaging component is used for shooting the surface of the product to be detected through the lens component so as to acquire an image for detecting the appearance defects.

2. The optical system of claim 1, wherein if the surface of the product to be measured is parallel to a tangential plane of an end surface of the lens assembly facing away from the imaging assembly, an angle between a plane of the planar lens adjacent to the collimating lens and the first central axis direction is 45 degrees.

3. The optical system according to claim 1 or 2, wherein the at least two sub-light sources further comprise a second sub-light source, the wavelength of the light emitted by the second sub-light source is different from the wavelength of the light emitted by the other sub-light sources, the straight line between the second sub-light source and the first sub-light source is perpendicular to the plane of the surface of the product to be measured, and the second sub-light source is located between the first sub-light source and the product to be measured.

4. The optical system of claim 3, wherein the at least two sub-light sources further comprise a third sub-light source, the wavelength of light emitted by the third sub-light source is different from the wavelength of light emitted by other sub-light sources, the straight line between the third sub-light source and the first sub-light source is perpendicular to the plane of the surface of the product to be measured, and the third sub-light source is located between the first sub-light source and the lens assembly.

5. The optical system of claim 4, wherein the second sub-light source is spaced apart from the first sub-light source by 2 millimeters and the third sub-light source is spaced apart from the first sub-light source by 2 millimeters.

6. An optical system according to claim 1 or 2, wherein each of the sub-light sources comprises a light emitting diode and a diaphragm, the diaphragm having dimensions of less than or equal to 3mm x 3mm.

7. An optical system according to claim 1 or 2, wherein the refractive index of the collimator lens is 1.491, the abbe number of the collimator lens is 55.310, the refractive index of the planar lens is 1.517, and the abbe number of the planar lens is 64.167.

8. An optical system according to claim 1 or 2, wherein the ratio of the transmittance to the reflectance of the planar lens is 5:5.

9. An optical system according to claim 1 or 2, wherein the distance between the end face of the planar lens adjacent to the product to be measured and the surface of the product to be measured is 30±5mm, the planar lens being coaxial with the lens assembly.

10. An optical system according to claim 1 or 2, wherein the lens assembly comprises a 35mm fixed focus lens, the distance between the lower surface of the 35mm fixed focus lens and the surface of the product to be measured is 200±5mm, and the focal length of the collimating lens is 35mm.