Arched detection light source detection method

Abstract

The invention relates to an arched detection light source detection method. The method comprises the following steps: (A) preparing an arched detection light source; (B) placing a to-be-detected product in a product observation area through a conveyor belt or manually; (C) opening an interactive interface, wherein the interactive interface controls the detection module and the light source module through the control module; (D), controlling a light source module through a control module, presenting fringe patterns of different periods, enabling a light source to be incident to the to-be-detected surface of the to-be-detected product, and collecting an image of the to-be-detected surface of the product through an industrial camera of a detection module; and (E) in combination with periodic fringe control, changing of multiple periods can be realized, phase extraction is completed in combination with fringe images of multiple periods, two sinusoidal grating patterns with different frequencies are alternately projected, phase deviation information is shared in a four-step phase shift mode, truncation phase information of two frequencies is obtained, and an absolute phase is calculated by using a multi-frequency heterodyne principle. The method is high in detection efficiency and good in detection effect.

Description

Technical Field

[0001] The present invention relates to the technical field of detecting light sources, and in particular to a method for detecting an arched detecting light source. Background Art

[0002] With the continuous development of the times, surface inspection of products is required after they are produced and processed. At present, the surface quality inspection of products has changed from manual inspection to taking pictures with industrial cameras and then analyzing and inspecting them by computer. However, the light source modules of existing inspection light sources often use a flat light-emitting surface. The flat light-emitting surface can emit less light. When irradiating the surface of curved products, it cannot guarantee that the reflected light will be completely captured by the imaging system. When encountering 2.5D and edge defects on the product surface, it cannot be effectively handled, the image acquisition speed is slow, and the inspection efficiency is low. In addition, the flat light-emitting surface occupies a large space, which is not conducive to the development towards miniaturization, micro-miniaturization and integration.

[0003] At the same time, in existing detection scenarios, the detection efficiency requirements are relatively strict, and generally the higher the detection efficiency, the better. For traditional planar phase light sources, the commonly used method is to perform four phase-shifted images in two directions, for a total of eight phase-shifted images. The four-step shift phase extraction method is then combined with the phase unwrapping algorithm to complete the absolute phase extraction. Further, the absolute phase is used to obtain the corresponding defect characteristics. However, this method of extracting the absolute phase is weak, and the detection accuracy and efficiency are low.

[0004] The existing planar detection light sources in the relevant technology can only emit a small amount of light. When illuminating the surface of a curved product, it cannot guarantee that the reflected light will be completely captured by the imaging system. When encountering 2.5D and edge defects on the product surface, they cannot be effectively handled, resulting in low detection accuracy and efficiency. There is still a lack of better technical solutions. Summary of the Invention

[0005] In view of this, it is necessary to provide a shape detection light source detection method to at least solve the problem that the existing planar detection light source in the relevant technology can emit less light, and when irradiating the surface of the curved product, it cannot guarantee that the reflected light is completely captured by the imaging system. When encountering 2.5D and edge defects on the product surface, it cannot be effectively handled, resulting in low detection accuracy and efficiency.

[0006] The present invention provides a method for detecting an arched detection light source, which includes the following steps:

[0007] (A) Prepare an arched detection light source, the arched detection light source includes a detection module, a control module and an arched light source module, the arched light source module is composed of an arched light-transmitting cover, an arched mounting frame and an LED light source unit, a product observation area is formed below the arched light-transmitting cover, the LED light source unit is spliced ​​together by several groups of flexible circuit boards, several groups of the flexible circuit boards are distributed side by side on the lower surface of the arched mounting frame and are located above the arched light-transmitting cover, several groups of the flexible circuit boards are electrically connected to the control module, an observation gap for observation by the detection module is formed between two adjacent groups of the flexible circuit boards, an observation hole is provided on the arched light-transmitting cover and below the observation gap, the detection module is installed on the upper surface of the arched mounting frame and is located directly above the observation hole; wherein, the line of sight of the detection module passes through the observation gap and the observation hole to observe the product to be detected in the product observation area;

[0008] (B) placing the product to be inspected in the product observation area by a conveyor belt or manually, and waiting for inspection;

[0009] (C) opening an interactive interface, which controls the detection module and the light source module through the control module to select a detection scheme;

[0010] (D) controlling the light source module through the control module to realize the presentation of fringe patterns of different periods and incident the light source onto the surface to be inspected of the product to be inspected, and collecting an image of the surface to be inspected of the product through the industrial camera of the inspection module;

[0011] (E) Combined with periodic fringe control, it is possible to achieve changes in multiple periods. Phase extraction is completed by combining multiple periodic fringe images. Two sinusoidal grating patterns of different frequencies are alternately projected, and the phase offset information is shared through a four-step phase shift. With only four images required, the truncated phase information of the two frequencies is obtained simultaneously, and the absolute phase is calculated using the multi-frequency heterodyne principle.

[0012] In step (A) of the above technology, the arched detection light source also includes a heat dissipation shell, the control module is installed inside the heat dissipation shell, the number of the multiple groups of flexible circuit boards is sixteen groups of flexible circuit boards, and the sixteen groups of flexible circuit boards are installed on the arched mounting frame in sequence from left to right to form an arched structure.

[0013] In the above technical solution, in step (A), LED lamp beads are distributed side by side on each group of the flexible circuit boards, and the LED lamp beads are electrically connected to the control module through the flexible circuit boards, and the LED lamp beads are small-package LED lamp beads; wherein, the control module controls the lighting and illumination intensity of the LED lamp beads through the flexible circuit boards to achieve the presentation of striped patterns with different periods, thereby illuminating the products in the product observation area, so that the light source is incident on the surface to be inspected of the product to be inspected, so that the detection module can better observe the surface to be inspected of the product to be inspected.

[0014] In the above technical solution, in step (A), the detection module includes an industrial camera, the industrial camera has a conical structure, and the arched mounting frame is provided with fixing holes for fixing the industrial camera, and the number of the industrial camera, the fixing holes and the observation holes matches; wherein, the industrial camera is fixed to the upper surface of the arched mounting frame through the fixing holes and the industrial camera is embedded in the observation gap, and the line of sight of the industrial camera observes and captures images of the surface to be inspected of the product to be inspected in the product observation area through the observation holes.

[0015] In the above technical solution, in step (A), the number of the industrial cameras, the fixing holes and the observation holes is five, and the five observation holes are arranged on the arched light-transmitting cover at equal intervals and angles from left to right, and the five industrial cameras are respectively installed directly above the five observation holes through the five fixing holes; wherein, the five observation holes and the five industrial cameras form five different observation points, and different numbers and positions of observation points can be used according to the usage requirements of different products to be inspected. For example, when encountering a product to be inspected with a large degree of curvature, observation can be carried out simultaneously through three or five observation points on the top, left and right sides. When encountering a product to be inspected with a smaller curvature, observation can be selected from the observation points on the left and right sides.

[0016] In the above technical solution, in step (D), the process of calculating the absolute phase is as follows:

[0017] (1) Select frequencies f1 and f2, where Δf = |f1-f2| << f1, to ensure the continuity of the subsequent calculation of the beat frequency signal;

[0018] (2) Four images are projected respectively, where I1 is frequency f1, phase shift 0°, I2 is frequency f2, phase shift 90°, I3 is frequency f1, phase shift 180°, and I4 is frequency f2, phase shift 270°;

[0019] (3) Solve the wrapped phase at different frequencies:

[0020] (4) Constructing the beat frequency phase diagram φ beat (x, y) = (φ1(x, y) - φ2(x, y)) mod 2π, where mod is the modulo operation;

[0021]

[0022] (5) Recover the high-frequency absolute phase Φ(x, y) = φ1(x, y) + 2π·k(x, y). After solving the absolute phase, the gradients in two directions are calculated as the phase gradient feature map:

[0023] Where * is the convolution operation

[0024] Beneficial effects of the present invention:

[0025] The present invention forms a curved light source with an arched structure by splicing multiple groups of flexible circuit boards, and adopts a curved LED light source emitting surface to ensure that more incident light is emitted to illuminate the surface to be detected of the product, thereby ensuring that reflected light with a larger curvature is reflected from the surface to be detected, and then more reflected light enters the imaging system for imaging; compared with traditional planar light sources, the present application can be compatible with surfaces to be detected with larger curvatures, improve the precision of precision measurement, and effectively handle 2.5D and edge defects on the surface of the product; the present application can adjust the number of groups of flexible circuit boards according to usage requirements to meet the usage requirements of different lengths and different arch heights, and it occupies less space and has higher space utilization; at the same time, by adopting a control module to drive and control the on and off and light intensity of the light source module The invention can realize multi-angle lighting of the product surface within the product observation area according to the lighting requirements of the product. The arched light-transmitting cover makes the light emitted by the LED light source unit hit the product more evenly. The use of multiple observation holes allows the industrial camera to take pictures of multiple surfaces of the three-dimensional product while ensuring that the opening is small. The pictures are more three-dimensional and the lighting effect is better. It solves the problems of 2.5D and edge defects on the product surface. Compared with the traditional planar light source method that uses eight phase-shifted images in two directions to calculate the absolute phase, the method of solving the absolute phase in the present invention uses multiple gratings of different frequencies for measurement, which can provide higher measurement accuracy. This method uses the beat frequency principle to amplify the small-cycle wrapped phase into a large cycle of phase difference, thereby including the cycle of the entire measurement field of view. Compared with the commonly used dual-frequency eight-image multi-frequency heterodyne method, the method of the present invention simplifies the calculation process and approximates the phase information through four phase images. It also retains the phase characteristic information of the defect and has higher computational efficiency. It can use larger dynamic detection to improve detection accuracy and efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic structural diagram of the present invention with the upper cover removed;

[0027] Figure 2 It is a schematic diagram of the overall structure of the present invention;

[0028] Figure 3 Schematic diagram of the structure of the detection module and the light source module of the present invention;

[0029] Figure 4 This is a schematic structural diagram of an industrial camera and a flexible circuit board according to the present invention;

[0030] Figure 5 It is a structural schematic diagram of the LED light source unit of the present invention. DETAILED DESCRIPTION

[0031] The present invention is described in detail below with reference to specific embodiments and accompanying drawings.

[0032] Please refer to Figures 1 to 5 This embodiment provides a method for detecting an arched detection light source, which includes the following steps:

[0033] (A) Prepare an arched detection light source, which includes a detection module 200, a control module 300 and an arched light source module 400. The arched light source module 400 is composed of an arched light-transmitting cover 41, an arched mounting frame 42 and an LED light source unit 43. A product observation area 500 is formed below the arched light-transmitting cover 41. The LED light source unit 43 is composed of several groups of flexible circuit boards 431. Several groups of the flexible circuit boards 431 are distributed side by side on the lower surface of the arched mounting frame 42 and are located above the arched light-transmitting cover 41. Several groups of the above Each flexible circuit board 431 is electrically connected to the control module 300. An observation gap 600 for observation by the inspection module 200 is formed between two adjacent sets of flexible circuit boards 431. An observation hole 700 is provided on the arched light-transmitting cover 41 below the observation gap 600. The inspection module 200 is mounted on the upper surface of the arched mounting frame 42 and directly above the observation hole 700. The inspection module 200 observes the product to be inspected within the product observation area 500 through the observation gap 600 and the observation hole 700.

[0034] (B) placing the product to be inspected in the product observation area 500 by a conveyor belt or manually, and waiting for inspection;

[0035] (C) Opening the interactive interface, which controls the detection module 200 and the light source module through the control module 300 to select a detection scheme;

[0036] (D) controlling the light source module through the control module 300 to achieve the presentation of fringe patterns of different periods and directing the light source onto the surface of the product to be inspected, and collecting an image of the surface of the product to be inspected through the industrial camera 21 of the inspection module 200;

[0037] (E) Combined with periodic fringe control, it is possible to achieve changes in multiple periods. Phase extraction is completed by combining multiple periodic fringe images. Two sinusoidal grating patterns of different frequencies are alternately projected, and the phase offset information is shared through a four-step phase shift. With only four images required, the truncated phase information of the two frequencies is obtained simultaneously, and the absolute phase is calculated using the multi-frequency heterodyne principle.

[0038] It should be noted that, with such a setting, the present application adopts a method of splicing multiple groups of flexible circuit boards 431 to form a curved light source with an arch structure. By adopting a curved LED light source light-emitting surface, it can ensure that more incident light is emitted to illuminate the surface to be detected of the product, thereby ensuring that reflected light with a larger curvature is reflected from the surface to be detected, and then more reflected light enters the imaging system for imaging; compared with traditional planar light sources, the present application can be compatible with surfaces to be detected with a larger curvature, and due to the structural design of the arched light source module 400, it occupies less space and has a higher space utilization rate; at the same time, the present application can adjust the number of groups of flexible circuit boards 431 according to usage requirements to meet the usage requirements of different lengths and different arch heights, and the observation gap 600 between two adjacent groups of flexible circuit boards 431 is small, which improves the detection accuracy of the present application.

[0039] In order to further realize the construction of an arched curved light source, in some optional embodiments, in step (A), the above-mentioned arched detection light source also includes a heat dissipation shell 100, the above-mentioned control module 300 is installed inside the above-mentioned heat dissipation shell 100, and the number of the above-mentioned flexible circuit boards 431 is sixteen groups of the above-mentioned flexible circuit boards 431. The sixteen groups of the above-mentioned flexible circuit boards 431 are installed in sequence from left to right on the above-mentioned arched mounting frame 42 to form an arched structure.

[0040] In order to realize the luminous function of the curved light source, in some optional implementation schemes, in step (A), LED lamp beads 432 are distributed side by side on each group of the above-mentioned flexible circuit boards 431, and the above-mentioned LED lamp beads 432 are electrically connected to the above-mentioned control module 300 through the above-mentioned flexible circuit boards 431, and the above-mentioned LED lamp beads 432 are small-packaged LED lamp beads 432; wherein, the above-mentioned control module 300 controls the lighting and illumination intensity of the above-mentioned LED lamp beads 432 through the above-mentioned flexible circuit boards 431 to realize the presentation of striped patterns with different periods, thereby illuminating the products in the above-mentioned product observation area 500, so that the light source is incident on the surface to be inspected of the product to be inspected, so that the above-mentioned inspection module 200 can better observe the surface to be inspected of the product to be inspected.

[0041] It should be noted that with such a setting, the present application adopts small-package LED lamp beads 432, such as 2020LED lamp beads or 0402LED lamp beads, which can effectively increase the density of the lamp beads and improve the phase accuracy of subsequent display; and the control module 300 adopts a static display driving scheme to drive the LED lamp beads 432, which can greatly improve the refresh speed of the phase stripes, and the refresh speed can reach more than 200khz, which effectively supports the image acquisition speed of mainstream linear array industrial cameras and area array industrial cameras, and improves the detection efficiency of this application.

[0042] In order to achieve observation and image acquisition of the surface to be inspected of the product to be inspected, in some optional embodiments, in step (A), the above-mentioned detection module 200 includes an industrial camera 21, the above-mentioned industrial camera 21 has a conical structure, and the above-mentioned arched mounting frame 42 is provided with a fixing hole 421 for fixing the above-mentioned industrial camera 21, and the number of the above-mentioned industrial camera 21, the above-mentioned fixing hole 421 and the above-mentioned observation hole 700 matches; wherein, the above-mentioned industrial camera 21 is fixed to the upper surface of the above-mentioned arched mounting frame 42 through the above-mentioned fixing hole 421 and the above-mentioned industrial camera 21 is embedded in the above-mentioned observation gap 600, and the line of sight of the above-mentioned industrial camera 21 observes and acquires images of the surface to be inspected of the product to be inspected in the above-mentioned product observation area 500 through the above-mentioned observation hole 700.

[0043] In order to further realize the observation and image acquisition of the surface to be inspected of the product to be inspected, in some optional implementation methods, in step (A), the number of the above-mentioned industrial cameras 21, the above-mentioned fixing holes 421 and the above-mentioned observation holes 700 is five, and the five above-mentioned observation holes 700 are arranged on the above-mentioned arched light-transmitting cover 41 at equal intervals and angles from left to right, and the five above-mentioned industrial cameras 21 are respectively installed directly above the five above-mentioned observation holes 700 through the five above-mentioned fixing holes 421; wherein, the five above-mentioned observation holes 700 and the five above-mentioned industrial cameras 21 form five different observation points, and different numbers and positions of observation points can be performed according to the usage requirements of different products to be inspected. For example, when encountering a product to be inspected with a large degree of curvature, observation can be carried out simultaneously through three or five of the above-mentioned observation points on the top, left and right sides. When encountering a product to be inspected with a smaller curvature, the above-mentioned observation points on the left and right sides can be selected for observation.

[0044] It should be noted that such a configuration, by adopting the structural design of the observation hole 700, enables the industrial camera 21 to be connected to the imaging optical path of the surface to be inspected. Since densely packed small-packaged LED lamp beads 432 are used, it is necessary to ensure that the opening is as small as possible. Therefore, a structural design with five observation holes 700 is adopted, which can achieve imaging of different angles of view. On the one hand, when performing surface defect detection, blind spots of the view can be avoided; on the other hand, through imaging of different views, the image stitching technology can be used to complete the stitching of a large view, thereby improving the detection accuracy of the present application;

[0045] It should be noted that the hardware designed in this application can control the light emission of the lamp bead 432, such as periodic control of the same frequency, through different phase stripe changes, and subsequently using a 4-step phase shift algorithm, or a 6-step phase shift and other phase shift calculation methods to complete the phase feature calculation of the image, or use periodic control of different frequencies, through multi-frequency interpolation phase calculation, to complete the phase feature calculation of the image, and through different image preprocessing methods, it is possible to complete the calculation of features such as phase gradient, thereby completing the feature enhancement of defects; compared with traditional lighting, the use of phase feature lighting can improve the contrast of defect features. In addition, compared with traditional planar light sources, it can avoid the blind spot of phase reflection, increase the multi-angle incidence of the phase light source, and further improve the detection accuracy.

[0046] In order to achieve better assembly and installation, in some optional embodiments, the heat dissipation housing 100 includes a base 12 and an upper cover 13 , the arched through groove 11 is provided at the lower end of the base 12 , and the upper cover 13 covers the upper end of the base 12 .

[0047] In order to further improve the assembly and installation, in some optional embodiments, a first arched slot is provided on the inner wall of the base, the arched light-transmitting cover 41 is clamped in the first arched slot and covers the arched through groove 11, and a second arched slot is provided on the inner wall of the base, the arched mounting frame 42 is clamped in the second arched slot and is located above the arched light-transmitting cover 41.

[0048] In order to achieve the heat dissipation function, in some optional embodiments, heat dissipation holes 14 are provided on both sides of the base, which can effectively discharge the heat generated by the industrial camera 21, the control module 300 and the light source module 400 during operation, thereby extending the service life.

[0049] In some optional implementations, in step (D), the process of calculating the absolute phase is as follows:

[0050] (1) Select frequencies f1 and f2, where Δf = |f1-f2| << f1, to ensure the continuity of the subsequent calculation of the beat frequency signal;

[0051] (2) Four images are projected respectively, where I1 is frequency f1, phase shift 0°, I2 is frequency f2, phase shift 90°, I3 is frequency f1, phase shift 180°, and I4 is frequency f2, phase shift 270°;

[0052] (3) Solve the wrapped phase at different frequencies:

[0053] (4) Constructing the beat frequency phase diagram φ beat (x, y) = (φ1(x, y) - φ2(x, y)) mod 2π, where mod is the modulo operation;

[0054]

[0055] (5) Recover the high-frequency absolute phase Φ(x, y) = φ1(x, y) + 2π·k(x, y). After solving the absolute phase, the gradients in two directions are calculated as the phase gradient feature map:

[0056] Where * is the convolution operation

[0057] It should be noted that compared to the traditional planar light source method of calculating absolute phase using eight phase-shifted images in two directions, the method for solving absolute phase in the present invention utilizes multiple gratings of different frequencies for measurement, which can provide higher measurement accuracy. This method uses the beat frequency principle to amplify the small-period wrapped phase into a large period of phase difference, thereby encompassing the period of the entire measurement field of view. Compared to the commonly used dual-frequency eight-image multi-frequency heterodyne method, the method of the present invention simplifies the calculation process and approximates the phase information through four phase images, similarly retaining the phase characteristic information of the defect, and has higher computational efficiency and can use larger dynamic detection.

[0058] It should be noted that the above method is still applicable to obtaining the corresponding absolute phase information by calculating by changing the number of frequencies, and is not limited to introducing two or three frequencies.

[0059] In the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connected," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention in specific circumstances.

[0060] The standard parts used in the present invention can all be purchased from the market, and special-shaped parts can be customized according to the description in the specification and the drawings. The specific connection methods of each part adopt conventional means such as mature bolts, rivets, welding, etc. in the existing technology. The machinery, parts and equipment all adopt conventional models in the existing technology, and the circuit connection adopts the conventional connection method in the existing technology, which will not be described in detail here.

[0061] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for detecting an arched detection light source, characterized in that: It includes the following steps: (A) Prepare an arched detection light source, the arched detection light source includes a detection module, a control module and an arched light source module, the arched light source module is composed of an arched light-transmitting cover, an arched mounting frame and an LED light source unit, a product observation area is formed below the arched light-transmitting cover, the LED light source unit is spliced ​​together by several groups of flexible circuit boards, several groups of the flexible circuit boards are distributed side by side on the lower surface of the arched mounting frame and are located above the arched light-transmitting cover, several groups of the flexible circuit boards are electrically connected to the control module, an observation gap for observation by the detection module is formed between two adjacent groups of the flexible circuit boards, an observation hole is provided on the arched light-transmitting cover and below the observation gap, the detection module is installed on the upper surface of the arched mounting frame and is located directly above the observation hole; wherein, the line of sight of the detection module passes through the observation gap and the observation hole to observe the product to be detected in the product observation area; (B) placing the product to be inspected in the product observation area by a conveyor belt or manually, and waiting for inspection; (C) opening an interactive interface, which controls the detection module and the light source module through the control module to select a detection scheme; (D) controlling the light source module through the control module to realize the presentation of fringe patterns of different periods and incident the light source onto the surface to be inspected of the product to be inspected, and collecting an image of the surface to be inspected of the product through the industrial camera of the inspection module; (E) Combined with periodic fringe control, it is possible to achieve changes in multiple periods. Phase extraction is completed by combining multiple periodic fringe images. Two sinusoidal grating patterns of different frequencies are alternately projected, and the phase offset information is shared through a four-step phase shift. With only four images required, the truncated phase information of the two frequencies is obtained simultaneously, and the absolute phase is calculated using the multi-frequency heterodyne principle.

2. The method for detecting an arched light source according to claim 1, wherein: In step (A), the arched detection light source also includes a heat dissipation shell, the control module is installed inside the heat dissipation shell, the number of the multiple groups of flexible circuit boards is sixteen groups of flexible circuit boards, and the sixteen groups of flexible circuit boards are installed on the arched mounting frame from left to right in sequence to form an arched structure.

3. The method for detecting an arched light source according to claim 2, wherein: In step (A), LED lamp beads are distributed side by side on each group of the flexible circuit boards, and the LED lamp beads are electrically connected to the control module through the flexible circuit boards. The LED lamp beads are small-packaged LED lamp beads; wherein, the control module controls the lighting and illumination intensity of the LED lamp beads through the flexible circuit boards to achieve the presentation of striped patterns with different periods, thereby illuminating the products in the product observation area, making the light source incident on the surface to be inspected of the product to be inspected, so that the detection module can better observe the surface to be inspected of the product to be inspected.

4. The method for detecting an arched light source according to claim 1, wherein: In step (A), the detection module includes an industrial camera, the industrial camera has a conical structure, and the arched mounting frame is provided with fixing holes for fixing the industrial camera, and the number of the industrial camera, the fixing holes and the observation holes matches; wherein, the industrial camera is fixed to the upper surface of the arched mounting frame through the fixing holes and the industrial camera is embedded in the observation gap, and the line of sight of the industrial camera observes and captures images of the surface to be inspected of the product to be inspected in the product observation area through the observation holes.

5. The method for detecting an arched light source according to claim 1, wherein: In step (A), the number of the industrial cameras, the fixing holes and the observation holes is five, and the five observation holes are arranged on the arched light-transmitting cover at equal intervals and angles from left to right, and the five industrial cameras are respectively installed directly above the five observation holes through the five fixing holes; wherein, the five observation holes and the five industrial cameras form five different observation points, and different numbers and positions of observation points can be performed according to the usage requirements of different products to be inspected. For example, when encountering a product to be inspected with a large degree of curvature, observation can be performed simultaneously through three or five observation points on the top, left and right sides. When encountering a product to be inspected with a smaller curvature, observation can be selected from the observation points on the left and right sides.

6. The method for detecting an arched light source according to claim 1, wherein: In step (D), the process of calculating the absolute phase is as follows: (1) Select frequencies f1 and f2, where Δf = |f1-f2| << f1, to ensure the continuity of the subsequent calculation of the beat frequency signal; (2) Four images are projected respectively, where I1 is frequency f1, phase shift 0°, I2 is frequency f2, phase shift 90°, I3 is frequency f1, phase shift 180°, and I4 is frequency f2, phase shift 270°; (3) Solve the wrapped phase at different frequencies: (4) Constructing the beat frequency phase diagram φ beat (x, y) = (φ1(x, y) - φ2(x, y)) mod 2π, where mod is the modulo operation; (5) Restore the absolute phase of high frequency After solving the absolute phase, the gradients in two directions are obtained as the gradient feature map of the phase: Where * is the convolution operation

Images