CN219641581U

CN219641581U - Concave defect detection device

Info

Publication number: CN219641581U
Application number: CN202223525073.1U
Authority: CN
Inventors: 贾睿; 郉志广; 武飞; 冷振; 周钟海; 姚毅
Original assignee: Shenzhen Lingyun Shixun Technology Co ltd
Current assignee: Shenzhen Lingyun Shixun Technology Co ltd
Priority date: 2022-12-22
Filing date: 2022-12-22
Publication date: 2023-09-05
Anticipated expiration: 2032-12-22

Abstract

The utility model relates to the technical field of defect identification, in particular to a concave defect detection device which can solve the problem that a conventional optical system cannot detect concave defects to a certain extent. The device comprises a light source, a distance recording assembly, an image acquisition assembly and an image processing assembly, wherein the light source is positioned above a test article and used for emitting first light rays for irradiating the test article, the test article comprises a sample to be detected and a calibration piece, and the calibration piece comprises a right triangular prism; the light source is connected with the triangular prism in a sliding way, and the inclined surface of the waist in the bottom surface of the triangular prism is a mirror surface; the distance recording component is used for recording the moving distance of the light source; the image acquisition component is positioned above the light source and is used for acquiring second light formed by specular reflection after the first light irradiates the test article; the image processing component is in communication connection with the image acquisition component and is used for receiving the image and acquiring the gray value of the image.

Description

Concave defect detection device

Technical Field

The utility model relates to the technical field of defect identification, in particular to a concave defect detection device.

Background

Because of the uncertainty of quality control in the production of industrial electronic products, various defects are easy to generate on the surface of the products, so that the defects of the products are often required to be detected to remove unqualified products.

In the process of detecting defects of industrial products, the defects are generally detected by a conventional optical system, the conventional optical system photographs a product region containing the defects, and then the defects are determined by analyzing the gray scale and the shape between the background and the defects in an obtained image and by the gray scale difference of the background and the defects.

However, defects of industrial products also include defects such as crush injury, insufficient polishing, seam recess and hemming, and since such defects are the same color as the background of the industrial product, it is only possible to determine whether or not the defects exist and where they exist by the above conventional method, and it is impossible to distinguish whether or not the defects exist in the recess, and when some dirt defects exist on the product, it is impossible to distinguish the defects from the recess type defects from the dimension of the gray scale difference and the shape.

Disclosure of Invention

In order to solve the problem that the conventional optical system cannot detect the concave defects, the utility model provides a concave defect detection device.

Embodiments of the present utility model are implemented as follows:

a first aspect of an embodiment of the present utility model provides a recess defect detection apparatus, including:

light source: the device comprises a test article and a calibration piece, wherein the test article is positioned above the test article and used for emitting first light for irradiating the test article, the test article comprises a sample to be detected and the calibration piece, and the calibration piece comprises a right triangular prism; the light source is in sliding connection with the calibration piece, the sliding direction is a straight line direction parallel to the bottom edge of the bottom surface of the triangular prism, and the inclined surface of the waist of the bottom surface of the triangular prism is a mirror surface;

the distance recording assembly is used for recording the moving distance of the light source;

the image acquisition component is positioned above the light source and is used for acquiring second light formed by specular reflection after the first light irradiates the test article, and when the image acquisition component acquires the image of the calibration piece, the first light irradiates an inclined plane where the waist in the bottom surface of the triangular prism is positioned;

the image processing component is in communication connection with the image acquisition component and is used for receiving the image and acquiring the gray value of the image.

In some embodiments, the calibration piece further comprises a connecting plate, wherein a plurality of triangular prisms are connected to the connecting plate, and angles between planes of two waists in the bottom surface of each triangular prism are different.

In some embodiments, the triangular prisms are arranged linearly along the connecting plate, and angles between planes of two waists in the bottom surfaces of all the triangular prisms sequentially increase along the arrangement direction of the triangular prisms in the connecting plate.

In some embodiments, three triangular prisms are provided, and the angle between the planes of the two waists in the bottom surface of each triangular prism is 0.5 °,1 ° and 1.5 ° in sequence.

In some embodiments, the base in the triangular prism is an isosceles triangle.

In some embodiments, the connection plate is connected with an empty plate for placing a sample to be detected.

In some embodiments, the driving member is further included for driving the light sources to move along the arrangement direction of the triangular prism.

In some embodiments, the image acquisition assembly comprises:

the lens is positioned above the test article and used for collecting the second light;

and the camera is positioned above the lens and connected with the lens.

In some embodiments, the camera employs a line scan camera, the lens employs a telecentric lens, and the light source employs a coaxial light source.

In some embodiments, the distance from the coaxial light source to the calibration piece is 70±2mm.

The utility model has the beneficial effects that: the method comprises the steps that a light source is moved to one side from a connecting point of two waists in the bottom surface of a triangular prism, at the moment, the light source sequentially irradiates different positions of an inclined surface where the waists in the bottom surface of the triangular prism are located, the moving position of the light source is recorded through a distance recording assembly, second light rays are collected through an image collecting assembly to obtain images of different positions of the triangular prism, contrast ratios corresponding to the images of different positions of the triangular prism are obtained through an image processing assembly, and then the contrast ratios are in one-to-one correspondence with the moving distance of the light source to obtain a corresponding relation between standard contrast ratios and the moving distance; and then, the light source is moved to irradiate the suspected defect part of the sample to be detected, the image acquisition component is used for acquiring the image of the sample to be detected, the image processing component is used for acquiring the contrast of the image of the sample to be detected, the contrast of the image of the sample to be detected is substituted into the corresponding relation between the standard contrast and the moving distance, the moving distance of the light source corresponding to the contrast of the image of the sample to be detected can be obtained, and the moving distance can be used for representing the depth of the concave defect, so that whether the concave defect and the defect depth exist or not can be judged, and the whole process of detecting the defect through the concave defect detection device is simple and convenient.

Drawings

In order to more clearly illustrate the embodiments of the present utility model or the technical solutions of the prior art, the drawings that are needed in the embodiments or the description of the prior art will be briefly described below, it will be obvious that the drawings in the following description are some embodiments of the present utility model, and that other drawings can be obtained according to these drawings without inventive effort to a person skilled in the art.

FIG. 1 is a front view of a recessed defect detection device according to one or more embodiments of the present utility model;

FIG. 2 is a top view of a triangular prism in a recessed defect detection apparatus according to one or more embodiments of the present utility model;

FIG. 3 is a schematic diagram illustrating placement of triangular prisms in a recessed defect inspection device according to one or more embodiments of the present utility model;

FIG. 4 is a schematic diagram illustrating operation of a recessed defect detection device according to one or more embodiments of the present utility model;

FIG. 5 is a front view of a fixture in a recessed defect detection device according to one or more embodiments of the present utility model;

fig. 6 is an example of a map of standard contrast versus distance of movement obtained by a dishing defect detection apparatus in accordance with one or more embodiments of the present utility model.

Illustration of:

1, a light source; 2. an image acquisition component; 21. a camera; 22. a lens; 3. an image processing component; 4. a calibration member; 41. triangular prism; 42. a connecting plate; 43. an empty plate; 5. a driving member.

Detailed Description

For the purposes of making the objects, embodiments and advantages of the present utility model more apparent, an exemplary embodiment of the present utility model will be described more fully hereinafter with reference to the accompanying drawings in which exemplary embodiments of the utility model are shown, it being understood that the exemplary embodiments described are merely some, but not all, of the examples of the utility model.

It should be noted that the brief description of the terminology in the present utility model is for the purpose of facilitating understanding of the embodiments described below only and is not intended to limit the embodiments of the present utility model. Unless otherwise indicated, these terms should be construed in their ordinary and customary meaning.

The terms first, second, third and the like in the description and in the claims and in the above-described figures are used for distinguishing between similar or similar objects or entities and not necessarily for describing a particular sequential or chronological order, unless otherwise indicated. It is to be understood that the terms so used are interchangeable under appropriate circumstances.

The terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a product or apparatus that comprises a list of elements is not necessarily limited to all elements explicitly listed, but may include other elements not expressly listed or inherent to such product or apparatus.

Before describing the specific embodiments, the technical terms related to the embodiments of the present utility model will be explained:

contrast ratio: when the image processing component processes the received image, the maximum gray value and the minimum gray value in the image are obtained after the gray histogram of the whole image is obtained, and the contrast is the ratio of the difference value between the maximum gray value and the minimum gray value to the sum of the maximum gray value and the minimum gray value.

Line scan camera: in machine vision, a line scan camera can provide very high resolution when detecting continuous objects or rolling objects. The line scan camera captures only one line as a narrow-band image and then the image processing assembly spells the multiple lines of color stripe images into a complete image, which can create an almost infinite image without stopping capture.

Telecentric lens: the Telecentric lens (Telecentric) can ensure that the obtained image magnification does not change within a certain object distance range, which is very important application for the situation that the measured object is not on the same object plane, and the Telecentric lens has a special parallel light path design.

Coaxial light source: the device provides more uniform illumination than the traditional light source, and simultaneously avoids the reflection of the object, so that the accuracy and reproducibility of machine vision are improved, the coaxial light source can highlight the surface unevenness of the object, and the interference caused by the reflection of the surface is overcome.

An optical axis: refers to the centerline of the beam (beam column), or the axis of symmetry of the optical system.

Divergence angle: the divergence angle is a derivative of the beam radius with respect to the far-field axial position and is used to measure the extent to which the beam diverges outward from its center.

Pixel size: the size of one pixel, the size of the pixel and the number (resolution) of the pixel jointly determine the size of the camera target surface, and the pixel is small, the resolution of the image is high and the information quantity is large; otherwise, the resolution of the image is low and the information quantity is small. Wherein, the pixel represents an image unit, which is the minimum unit for forming a digitized image. The pixels are important marks reflecting the image characteristics, and are data elements with spatial characteristics and spectrum characteristics at the same time. The geometric meaning is the ground area represented by the data value determination, and the physical meaning is that the spectrum variable represents the intensity of the spectrum response in a specific wave band in the pixel. I.e. the features in the same picture element, have only one common gray value.

An image acquisition component: the method is used for image acquisition, specifically, the image is sampled, quantized and then converted into a digital image, and the digital image is input into a frame memory and stored.

An image processing component: the gray scale value acquisition module is used for receiving the image, repairing and synthesizing the received image and the like, and acquiring the gray scale value of the received image.

In some embodiments, as shown in fig. 1 and fig. 2, a device for detecting a concave defect is provided, which specifically includes a light source 1, an image acquisition component 2, a distance recording component and an image processing component 3, where the light source 1 is located above a test article and is used for emitting a first light ray for irradiating the test article, the test article includes a sample to be detected and a calibration component 4, the calibration component 4 includes a triangular prism 41, and a top view of the triangular prism 41 is a right triangle. The light source 1 is slidably connected to the calibration member 4, and the sliding direction is parallel to the linear direction in which the bottom edge of the bottom surface of the triangular prism 41 is located. The inclined surface of the bottom surface of the triangular prism 41 where the waist is located is a mirror surface. The distance recording assembly is used for recording the distance moved by the light source 1. The image acquisition component 2 is located above the light source 1 and is used for acquiring a second light ray formed by specular reflection after the first light ray irradiates the test article so as to form an image of the test article, and when the image acquisition component 2 acquires the image of the calibration piece 4, the first light ray irradiates an inclined plane where a waist in the bottom surface of the triangular prism 41 is located. The image processing component 3 is in communication with the image acquisition component 2, and the image processing component 3 is configured to receive the image and obtain a gray value of the image.

As shown in fig. 3, the triangular prism 41 is vertically disposed, the top and bottom surfaces of the triangular prism 41 are triangular, the side wall is three quadrangles, and the light source 1 irradiates a plane where the middle waist of the bottom edge of the triangular prism 41 is located, that is, an inclined surface of the triangular prism 41.

In some embodiments, in order for the lens 22 to collect as much of the second light as possible, the lens 22 is placed perpendicular to the horizontal plane. As shown in fig. 4, when the concave defect detecting device is used, the light source 1 emits the first light through the condensing rod of the center of a circle, irradiates the inclined surface where the waist is located in the bottom surface of the triangular prism 41, and at this time, the inclined surface where the waist is located in the bottom surface of the triangular prism 41 performs specular reflection on the first light to form the second light, and the second light is coaxially arranged with the camera 21. In some embodiments, in order to make the light source 1 move to two sides, the obtained contrast is the same, as shown in fig. 2, the triangular prism 41 is a triangular prism 41 with an isosceles triangle bottom, and at this time, the light source 1 may start to move from the connection point of two waists in the bottom of the triangular prism 41. In addition, the bottom side length and the waist length of the bottom surface of the triangular prism 41 need to be adapted to the sample to be tested, and the bottom side length and the waist length of the bottom surface of the triangular prism 41 are not specifically limited.

It should be understood that the light source 1, the image capturing assembly 2 and the image processing assembly 3 may be connected to the workbench through connectors such as a bracket, a supporting table or a working frame, and the connection modes of the light source 1, the image capturing assembly 2 and the image processing assembly 3 to the workbench are not specifically limited herein. The distance recording assembly is connected to the calibration member 4.

When detecting whether a concave defect exists in a sample to be detected, firstly, moving the light source 1 horizontally to one side from a connecting point of two waists in the bottom surface of the triangular prism 41, at the moment, sequentially irradiating the light source 1 on different positions of an inclined surface where the waists in the bottom surface of the triangular prism 41 are positioned, recording the moving position of the light source 1 through a distance recording assembly, wherein the moving distance of the light source 1 is generally calculated in millimeters, and the moving distance of the light source 1 is set according to actual conditions; the second light is collected through the image collection assembly 2, images of different positions of the triangular prism 41 are obtained, the maximum gray value and the minimum gray value corresponding to the images of different positions of the triangular prism 41 are obtained through the image processing assembly 3, corresponding contrast can be obtained according to the maximum gray value and the minimum gray value in each image, and then the contrast is in one-to-one correspondence with the moving distance of the light source 1, so that the corresponding relation between standard contrast and the moving distance is obtained.

And then the light source 1 is moved, so that the light source 1 irradiates the suspected defect part of the sample to be detected, an image of the sample to be detected is obtained through the image acquisition component 2, and the maximum gray value and the minimum gray value in the image of the sample to be detected are obtained through the image processing component 3, so that the contrast of the image of the sample to be detected is obtained. Finally, substituting the contrast of the sample image to be detected into the corresponding relation between the standard contrast and the moving distance, the moving distance of the light source 1 corresponding to the contrast of the sample image to be detected can be obtained, and the moving distance can be used for representing the depth of the concave defect, so that whether the concave defect and the defect depth exist or not can be judged, and when the contrast is 0, namely, the moving distance of the light source 1 is 0, the fact that the concave defect does not exist on the sample to be detected is indicated.

The gray value range in the image is generally 0-255. The image processing component 3 may convert the acquired image into a gray level map by a component method, a maximum value method, an average value method or a weighted average method, acquire a plurality of gray level values in the image by a binarization method, determine the contrast of each image by a manual calculation method based on the determination of the maximum gray level value and the minimum gray level value, and further, one-to-one correspond the distance moved by the light source 1 to the contrast of the corresponding image, and list the corresponding relationship table, or complete the process of acquiring the contrast by the terminal device and one-to-one correspond the distance moved by the light source 1 to the contrast of the corresponding image, and then output the corresponding relationship table of standard contrast-moving distance by the terminal device. The terminal can be, but not limited to, various personal computers, notebook computers, smart phones and tablet computers, and can communicate with an independent server or a server cluster formed by a plurality of servers through a network.

By adopting the concave defect detection device to judge whether defects exist or not, and comparing the mode of acquiring the depth of the defects with the mode of detecting through a conventional optical system or the mode of detecting through a deep learning model, the accuracy is high, the applicability is strong, the detection process is convenient, and the condition of over-detection or omission detection is not easy to occur; compared with the detection mode by using a three-dimensional sensor such as a line-induced contour scanner, binocular vision and the like, the method has low cost and high applicability.

It can be understood that when a sample to be detected has a plurality of defects, the image acquisition component 2 can be used for simultaneously photographing the defects in the sample to be detected, or each defect in the sample to be detected is photographed independently, so that the gray value in each defect image is obtained through the image processing component 3, the contrast of each defect image is obtained, and then the moving distance of the light source 1 corresponding to each defect is found according to the corresponding relation between standard contrast and moving distance, namely, the depth of each concave defect.

In some embodiments, as shown in fig. 1, the image acquisition assembly 2 includes a lens 22 and a camera 21, the lens 22 being located above the test article and configured to collect the second light. The camera 21 is located above the lens 22 and is connected with the lens 22 through threads, and the camera 21 is used for collecting second light and forming an image. The image acquisition assembly 2 is simple in structure, low in cost and easy to set up, and the operation process is relatively simple, so that the efficiency of detecting the concave defects is improved.

In order not to change the conventional optical system, the second light enters the camera 21 in a mode of approximately parallel light to form images, so that the camera 21 can collect images more effectively, the camera 21 adopts the line scanning camera 21, the lens 22 adopts the telecentric lens 22, and the light source 1 adopts the coaxial light source 1. Telecentricity of telecentric lens 22 is generally within 0.1 °, so that divergence angle is low, when light parallel to the optical axis enters lens 22 for imaging, stray light received by telecentric lens 22 is less, which helps camera 21 to obtain a complete image, and the distance from the lower surface of telecentric lens 22 to calibration piece 4 is 120±2mm. Compared with the area array camera, the line scanning camera 21 has less stray light acquired when receiving the second light instantly. Because the lens 22 needs to have proper pixel size, cameras 21 with different parameters are selected based on different precision and field requirements, and when the telecentric lens 22 is adopted, line scan cameras 21 with pixel size of 7um and 50KHz are selected so as to be convenient for adapting shooting speed. The coaxial light source 1 is used for illumination by using light with smaller divergence angle, the distance between the lower surface of the coaxial light source 1 and the calibration piece 4 is 70+/-2 mm, and at the moment, the normal movement of the light source 1 is not influenced, and the image acquisition assembly 2 is also beneficial to accurately acquiring images.

In order to facilitate the operator to conveniently adjust the position of the light source 1, as shown in fig. 1, the device for detecting a concave defect further includes a driving member 5, and the driving member 5 may adopt any structure capable of driving the light source 1 to move. In some embodiments, the driving piece 5 adopts a triaxial displacement optical platform, the sliding part of the triaxial displacement optical platform is assembled with the coaxial light source 1 through bolts, the light source 1 is subjected to translational adjustment through the triaxial displacement optical platform, the adjustment range is +/-20 mm, the adjustment process of the light source 1 is simple and convenient, and the movement distance is accurate.

Since the depth of the recess defect is large, at this time, if the angle between the planes of the waists of the two bottom surfaces of the triangular prism 41 adopted in calibration is small, the obtained contrast difference is large, and the gray value of a part of the acquired image exceeds 255, the corresponding relationship between the measured standard contrast and the moving distance is inaccurate, and thus the method is not suitable for detecting the recess defect with large depth, in some embodiments, as shown in fig. 5, the calibration piece 4 further includes a connecting plate 42, the connecting plate 42 is horizontally placed, a plurality of right triangular prisms 41 are bonded on the connecting plate, and the angle between the planes of the two waists of the bottom surface of each triangular prism 41 is different. At this time, by moving the light source 1, the light source 1 is sequentially irradiated onto the plurality of triangular prisms 41, and the correspondence relationship between the standard contrast and the moving distance of each triangular prism 41 is recorded. After the contrast of the sample to be detected is obtained, a proper standard contrast-moving distance correspondence is selected for matching according to the rough estimated value of the depth of the concave defect, so as to accurately determine the depth of the concave defect.

In some embodiments, in order to make it difficult for an operator to mix the standard contrast-movement distance relationship corresponding to each triangular prism 41, the plurality of triangular prisms 41 are linearly arranged along the connection plate 42, and the angles between the planes of the two waists in the bottom surfaces of all triangular prisms 41 sequentially increase along the arrangement direction of the triangular prisms 41 in the connection plate 42. At this time, the corresponding standard contrast-moving distance correspondence may be sequentially arranged according to the order of the triangular prisms 41, so that the chaotic standard contrast-moving distance correspondence is not easy to be generated, and thus the accurate detection of the concave defects of the sample to be detected is facilitated.

In some embodiments, three triangular prisms 41 are provided, and the angle between the planes of the two waists in the bottom surface of each triangular prism 41 is 0.5 °,1 ° and 1.5 ° in order. At this time, the detection of a plurality of defects can be satisfied, if the angle between the planes of the two waists in the bottom surface of the triangular prism 41 is smaller, the contrast in the corresponding image is too weak, and the detection is not suitable for accurately detecting the defect with larger concave depth; if the angle between the planes of the two waists in the bottom surface of the triangular prism 41 is large, the contrast ratio in the corresponding image is too strong, so that the accurate corresponding relationship between the concave degree and the moving distance of the light source 1 is not easy to be obtained, and the depth of the defect cannot be obtained accurately in the later stage.

In order to facilitate an operator to quickly photograph a sample to be detected after obtaining the corresponding relationship between the standard contrast and the moving distance, as shown in fig. 5, one side of the connecting plate 42 is integrally connected with a blank plate 43, and the blank plate 43 can be coplanar with the connecting plate 42 and is used for placing the sample to be detected. At this time, the placing process of the sample to be detected is convenient, and the process of irradiating the sample to be detected by the light source 1 is convenient.

It is understood that the distance recording assembly may be any mechanism capable of recording a distance, for example, the distance recording assembly may use knots, and the distance between adjacent knots in the knots is fixed, which is a preset distance for each movement of the light source 1, and the distance recording assembly is not particularly limited in this embodiment. In some embodiments, the distance recording assembly is a graduated scale, and the zero graduation line of the graduated scale is flush with the connection point of the two waists in the bottom surface of the triangular prism 41. The distance recording assembly may be bolted to the connection plate 42 or may be fixed to the driving member 5. When the light source 1 moves, the moving distance of the light source 1 can be recorded by manually or by equipment reading the scales on the readable ruler, so that the method is simple and efficient.

Next, for example, the correspondence between the image obtained by the above-mentioned recessed defect detecting device and the measured standard contrast-moving distance is shown in fig. 6, where the standard contrast-moving distance correspondence is based on the standard contrast-moving distance correspondence quantified when the angle of the irradiation inclined plane is 1 ° (in fig. 6, the moving distance is represented by the on-axis light adjustment amount), and as shown in fig. 6, when the contrast in the sample image to be detected is obtained, the corresponding defect depth can be obtained by comparing the standard contrast-moving distance correspondence, for example, when the contrast in the sample image to be detected is 62.8%, the corresponding light source 1 translates by 6mm, and at this time, the recessed degree of the sample image to be detected is relatively obvious.

It should be noted that, for inclined surfaces with different angles, the corresponding relationship between the primary standard contrast and the moving distance is obtained, and then the method can be used for detecting the concave defects of the sample to be detected for many times.

The embodiment of the present utility model has the advantages that the concave defect detection device detects the images of the different positions of the calibration piece 4, then determines the corresponding relation between the standard contrast and the moving distance according to the contrast of each image and the moving distance of the light source 1, then determines the suspected defect position of the sample to be detected through the concave defect detection device, compares the contrast in the image of the sample to be detected with the contrast in the corresponding relation between the standard contrast and the moving distance, so as to determine the moving distance of the corresponding light source 1, and the moving distance of the corresponding light source 1 is the depth of the concave defect. The whole concave defect detection device is low in cost, simple to operate, efficient and convenient in defect detection process, and capable of accurately obtaining the depth of concave defects.

The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above examples illustrate only a few embodiments of the utility model, which are described in detail and are not to be construed as limiting the scope of the utility model. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the utility model, which are all within the scope of the utility model. Accordingly, the scope of protection of the present utility model is to be determined by the appended claims.

Claims

1. A dishing defect detection apparatus, comprising:

2. The dishing defect detection apparatus of claim 1, wherein the calibration member further comprises a connection plate to which a plurality of triangular prisms are connected, the angle between the planes of the two waists in the bottom surface of each triangular prism being different.

3. The depressed defect detecting apparatus of claim 2, wherein a plurality of said triangular prisms are arranged linearly along said connecting plate, and angles between planes of two waists in all of bottom surfaces of said triangular prisms are sequentially increased along an arrangement direction of said triangular prisms in said connecting plate.

4. The dishing defect inspection apparatus of claim 3 wherein three triangular prisms are provided and the angles between the planes of the two waists in the base of each triangular prism are in turn 0.5 °,1 ° and 1.5 °.

5. The recessed defect detection device of claim 1, wherein the bottom surface of the triangular prism is an isosceles triangle.

6. The dishing defect detection apparatus according to claim 2, wherein the connection plate is connected with an empty plate for placing a sample to be detected.

7. The recessed defect detection apparatus as claimed in claim 3, further comprising a driving member for driving the light sources to move in the direction of the triangular prism arrangement.

8. The dishing defect detection apparatus of claim 1, wherein said image acquisition assembly comprises:

and the camera is positioned above the lens and connected with the lens.

9. The dishing defect detection apparatus of claim 8, wherein said camera is a line scan camera, said lens is a telecentric lens, and said light source is a coaxial light source.

10. The dishing defect detection apparatus of claim 9, wherein the distance from the coaxial light source to the calibration member is 70 ± 2mm.