Program-controlled phase-shift structured light source, control method and industrial line scanning detection method

Abstract

The invention relates to the technical field of visual inspection, and provides a program-controlled phase-shift structured light source, a control method and an industrial line scanning detection method. The light source comprises a lamp bead module and total reflection lens modules, wherein the lamp bead module is composed of a plurality of lamp beads arranged in a matrix mode, the total reflection lens modules are in one-to-one correspondence with the lamp beads, and the light spot diameter of each single lamp bead on a working face is set so that sine stripes can be formed through seamless splicing when the lamp beads of the same phase in all arrays are synchronously lightened. And the control module rapidly switches the lightened lamp bead groups according to a phase shift time sequence, so that transverse and longitudinal phase shifts of the stripes are realized. According to the industrial line scanning detection method, an object to be detected is made to move, a light source mode is synchronously switched, an image is collected by a line scanning camera, and two working modes of reciprocating movement and phase-divided complete shooting of the object to be detected and one-way continuous movement and rapid light-emitting mode switching of the object to be detected so as to synchronously collect a phase image are supported. And a high-speed, high-precision and compact-structure phase-shift illumination solution is realized while the high-brightness requirement of line scanning detection is met.

Description

Technical Field

[0001] This invention relates to the field of visual inspection technology, and more specifically, to a programmable phase-shift structured light source, a control method, and an industrial line scan inspection method. Background Technology

[0002] Industrial visual inspection plays a crucial role in modern manufacturing, especially in accurately reflecting the height changes of the inspected object using three-dimensional information to improve inspection accuracy and efficiency. Structured light phase-shifting, a common 3D imaging technique, projects periodic stripe spots and shifts them by specific phases (e.g., 90°, 180°, 270°), combining multiple images to jointly solve for height information. It is widely used in quality control and reverse engineering. Industrial visual inspection is mainly divided into two methods: area scan inspection and line scan inspection. Line scan inspection, with its high acquisition frequency (line frequency up to 20kHz), high resolution, and long measurable length, is particularly suitable for large-size, high-speed inspection scenarios, such as 3D modeling of products like television displays. However, the high line frequency of line scan cameras requires illumination sources with brightness far exceeding that of area scan inspection; otherwise, it is difficult to acquire clear images within a short exposure time, which has become a major bottleneck for the widespread adoption of line scan inspection technology.

[0003] Currently, there are two main existing technical solutions for structured light phase-shifting methods. The first solution uses a projector to project structured light, which offers advantages such as good controllability and high fringe clarity. However, the projector's brightness is limited and cannot meet the illumination requirements of a line scan camera at high line frequencies, resulting in insufficient image signal-to-noise ratio. The second solution uses a dedicated line scan light source to illuminate a black-and-white transparent grating, generating fringes through a physical grating. While the brightness is sufficient, the fringe positions are fixed, requiring additional displacement equipment (such as precision mechanical structures) to achieve fringe movement (phase shift). This displacement equipment has extremely high requirements for movement speed and accuracy, leading to a bloated system and increased costs. Furthermore, the delay of mechanical movement is difficult to match the high-frequency acquisition of a line scan camera, limiting its application in high-speed detection scenarios.

[0004] Therefore, there is an urgent need for a new lighting solution that can achieve rapid, programmable phase shift of high-brightness striped light without the need for complex mechanical structures, in order to overcome the limitations of existing technologies and promote the further development of line scan detection technology. Summary of the Invention

[0005] This invention addresses the technical problems existing in the prior art by providing a programmable phase-shifting structured light source, control method, and industrial line scan detection method. It provides a structured light source solution for industrial line scan detection that can meet the requirements of high brightness and achieve fast and accurate phase shifting, thereby overcoming the shortcomings of insufficient light source brightness, bulky equipment, and slow response speed in the prior art.

[0006] According to a first aspect of the present invention, a programmable phase-shift structured light source is provided, comprising an LED module, a lens module, and a control module, wherein: The lamp module includes multiple lamp arrays arranged periodically in rows and / or columns, each lamp array including multiple lamps arranged in an m×m pattern, where m>1; The lens module includes multiple lenses arranged one-to-one with multiple LED beads, used to collimate the light emitted by the corresponding LED beads and project it onto the same working plane. The control module is electrically connected to the LED beads and is used to independently control the turning on and off of each LED bead. The control module is configured to control the synchronous lighting of lamps with the same phase in different lamp arrays according to a preset phase shift timing sequence, so as to form periodic bright and dark stripes on the working plane. The diameter of the light spot of a single LED on the working plane is equal to the stripe spacing of the bright and dark stripes.

[0007] Based on the above technical solution, the present invention can also be improved as follows.

[0008] Optionally, in the lamp module, the horizontal and vertical spacing between adjacent lamps are the same.

[0009] Optionally, according to the lighting sequence of the LEDs, the phase difference between LEDs at adjacent lighting times is 2π / m.

[0010] Optionally, the light intensity along the diameter of the light spot of a single LED bead is sinusoidal, and the light intensity through the center of the light spot in the bright and dark stripes is sinusoidal.

[0011] Optionally, the lens is a total internal reflection lens.

[0012] Optionally, the lens includes a centrally located transmission zone and a circumferentially located reflection zone.

[0013] Optionally, all the LEDs are located on the same plane.

[0014] According to a second aspect of the present invention, a control method for a programmable phase-shift structured light source based on the above-described method is provided, comprising: According to the phase shift timing of the m-step phase shift method, the lamps with the same phase in different lamp arrays are controlled to be lit synchronously to form periodic bright and dark stripes on the working plane. The phase shift of the bright and dark stripes is achieved by sequentially switching the lit LED beads.

[0015] Optionally, the m-step phase shift method includes performing a transverse phase shift sub-step and a longitudinal phase shift sub-step; The transverse phase shifter step includes: According to the first preset timing sequence, the LEDs located in the same column position in different LED arrays are lit synchronously in sequence to achieve the phase shift of the bright and dark stripes in the horizontal direction. The phase difference of each horizontal phase shift is 2π / m. The longitudinal phase shift sub-step includes: According to the second preset timing sequence, LEDs located in the same row position in different LED arrays are lit synchronously in sequence to achieve phase shift of bright and dark stripes in the vertical direction. The phase difference of each vertical phase shift is 2π / m.

[0016] According to a third aspect of the present invention, an industrial line scan detection method is provided, which, based on the above-described control method, includes: S1, causing the object to be tested to move relative to the line scan camera and the programmable phase-shifting structured light source in a predetermined direction; S2, during the movement of the object under test, the light emission mode of the light source is switched according to the phase shift sequence of the m-step phase shift method, and the line scan camera simultaneously acquires multiple images of the object under test containing different phase brightness and darkness stripes; S3, based on the acquired multiple images, reconstructs the three-dimensional shape of the object under test.

[0017] Optionally, step S2 specifically includes: Control the object under test to perform multiple reciprocating movements; During each reciprocating movement, the light source remains in a fixed phase emission mode in the m-step phase shift method, and the line scan camera acquires an image of the test object that matches the current phase during the unidirectional movement of the test object. After each reciprocating movement, the object under test is reset to the starting position, and the light source is switched to the emission mode corresponding to the next phase in the m-step phase shift method. The image acquisition process is repeated until images of the object under test with all different phases are obtained.

[0018] Optionally, step S2 specifically includes: Control the object under test to begin continuous movement; During the movement of the object under test, the first and second emission modes of the light source are rapidly switched in a phase shift sequence, and the line scan camera synchronously acquires an image of the object under test each time the emission mode is switched. In the first light emission mode, the transverse phase shifter step is performed; in the second light emission mode, the longitudinal phase shifter step is performed; or, The longitudinal phase shifter step is performed in the first light emission mode, and the transverse phase shifter step is performed in the second light emission mode; Multiple images of the object under test acquired continuously are stitched together to form a composite image. Based on the switching order of the emission modes, images of different phases required by the m-step phase shifting method are separated from the composite image.

[0019] Optionally, the switching time between the first and second light emission modes of the light source is less than 100 microseconds, so that the image lines acquired by the line scan camera in different light emission modes with continuous and extremely short time intervals correspond to the area at basically the same position on the surface of the object under test.

[0020] This invention provides a programmable phase-shift structured light source, control method, and industrial line scan detection method. Multiple LED arrays arranged in an m×m matrix are arranged in rows and / or columns to form LED modules, with each LED corresponding to a lens. This ensures that the diameter of the light spot formed by a single LED on the target working plane after collimation is equal to the stripe spacing. Through precise optical design, high-brightness, electronically phase-shiftable sinusoidal bright and dark stripes can be directly generated on the working surface by controlling the synchronous lighting and switching of LEDs with the same phase in different arrays, replacing traditional mechanical movement devices. The control method defines the logic for timing control of the LED lighting and switching using an m-step phase-shift method, achieving rapid and accurate lateral and longitudinal electronic phase shifts of the bright and dark stripes, providing the necessary phase image sequence for subsequent 3D reconstruction algorithms. Based on the aforementioned light source and control methods, this detection method integrates the steps of object movement, time-series switching of light source, and synchronous acquisition by a line scan camera. Ultimately, it can efficiently and accurately obtain the bright and dark stripe images corresponding to each phase required for the 3D morphology reconstruction of the object under test, making it suitable for high-speed industrial line scan inspection scenarios of various sizes. Attached Figure Description

[0021] Figure 1a This is a front view of a programmable phase-shift structured light source provided in one embodiment. Figure 1b for Figure 1a The image shows a side view of a programmable phase-shift structured light source. Figure 1c This is a cross-sectional view from the lens side. Figure 2 This is a schematic diagram of the working scenario of a programmable phase-shift structured light source provided in one embodiment. Figure 3 for Figure 1a The diagram shows the spot size of a single LED in the bright and dark stripes and the image capture position of the line scan camera during the lateral phase shift of the light source. Figure 4a for Figure 1a The image shows a simulation of the bright and dark fringes formed by the light source on the working plane at time t2 during the lateral phase shift. Figure 4b For time t2, the camera scanned... Figure 4a A schematic diagram of the light intensity distribution at the center of the light spot of the second row of LED beads in the bright and dark stripes; Figure 5a for Figure 1a The diagram shows the bright line formed by the light source on the working plane at time t5 during the longitudinal phase shift. Figure 5b For the camera scanned at time t5 Figure 5a The light intensity distribution at the center of the light spot of the first row of LED beads in the bright line; Figure 5c for Figure 1a The diagram shows the bright line formed by the light source on the working plane at time t6 during the longitudinal phase shift. Figure 5d The camera scanned at time t6 Figure 5c The light intensity distribution at the center of the light spot of the second row of LED beads in the bright line; Figure 6 A schematic diagram of a process for implementing segmented linear scanning detection by reciprocating movement of the test object in one embodiment; Figure 7 To distinguish from Figure 6 Another embodiment provides a schematic diagram of a scheme in which the test object completes a line scan by moving the test object in only one direction.

[0022] The attached diagram lists the components represented by each number as follows: 1. LED bead, 2. Lens, 2a. Transmission area, 2b. Reflection area, 3. Substrate. Detailed Implementation

[0023] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0024] Example 1: Figure 1a This is a schematic diagram of the main view structure of a programmable phase-shifting structured light source provided in this embodiment. Figure 1b This is a schematic diagram of the light source's side view structure. Figure 1c This is a cross-sectional schematic diagram showing the view from the side of a single lens. Figure 2 This is a schematic diagram of the working scenario of the programmable phase-shift structured light source provided in this embodiment.

[0025] Combination Figures 1a-1c As shown, this embodiment provides a programmable phase-shift structured light source, including an LED module, a lens module, and a control module, as well as a substrate 3 (e.g., a PCB). The LED module includes multiple LEDs 1, and the lens module includes multiple lenses 2. The LEDs 1 and lenses 2 are one-to-one and fixedly disposed on the substrate 3, so that all LEDs are located on the same plane.

[0026] Multiple LED chips 1 are soldered onto substrate 3 in a matrix configuration with identical horizontal and vertical spacing (i.e., equal spacing), forming multiple LED chip arrays arranged periodically in rows and columns. Depending on actual needs, the number of LED chip arrays and lenses can be flexibly adjusted to obtain M×N LED chip arrays, where M is the number of cycles in the horizontally arranged LED chip arrays and N is the number of cycles in the vertically arranged LED chip arrays. Figure 1a The dashed line in the middle serves as the dividing line between the LED arrays. M=3 LED array cycles are arranged horizontally, and N=1 LED array cycles are arranged vertically.

[0027] Each LED array consists of m×m LEDs, where m=4 in this embodiment. Each LED 1 is precisely positioned above an independent lens 2, as shown in the diagram. Figure 1c The side-view cross-sectional view is shown. Lens 2 is preferably a total internal reflection lens, which includes a central transmission area 2a and a circumferential reflection area 2b. As shown... Figure 1c As shown, lens 2 collimates the light emitted by lamp bead 1, converting it into approximately parallel light to ensure that the light spot projected onto the same working plane has high brightness and clear boundaries.

[0028] The control module (not shown in the figure) is electrically connected to each lamp bead 1 via the substrate 3, and is used to independently control the turning on and off of each lamp bead 1.

[0029] The control module is configured to control the synchronous lighting of LEDs with the same phase in different LED arrays according to a preset phase shift sequence, so as to form periodic bright and dark stripes on the working plane. The number of periods of the bright and dark stripes is related to the number of periods of the LED array.

[0030] In this embodiment, the light source achieves fringe phase shifting through a control module (purely electronic control). Taking a four-step lateral phase shift (m=4) as an example, the control module operates according to a preset timing sequence (t1~t4), controlling one column of LEDs in the LED array to light up at each moment while keeping the other three columns of LEDs in the same array off. Each column of LEDs represents a phase. In this embodiment, an LED array has four columns of LEDs, so the phases of the LEDs from the first to the fourth column are 0°, 90°, 180°, and 270° respectively. The phase difference between adjacent columns of LEDs is 2π / 4, or 90°.

[0031] More specifically, at time t1, the LEDs in specific phases (e.g., the first column of each subarray, i.e., columns 1, 5, and 9) are synchronously illuminated, forming horizontal stripes with a 0° phase. At time t2, such as... Figure 4aAs shown in the (strials at time t2), the control module switches to illuminating LEDs whose positions are offset by one column (e.g., the second column of each subarray, i.e., columns 2, 6, and 10). Since the physical position of the LEDs shifts by a spacing L, and the period of the synthesized stripes is 4L, this is equivalent to shifting the stripes by 1 / 4 of a period on the plane, resulting in a phase difference of 2π / 4 = 90°. By sequentially illuminating subsequent columns (columns 3, 7, 11; 4, 8, 12), lateral phase shifts of 180° and 270° can be rapidly and mechanically achieved. This process is entirely program-controlled, and the phase shift speed can reach the microsecond level.

[0032] Precise matching between the size of the individual LED spot and the overall stripe period. For example... Figure 3 (Diagram of lateral phase shift) As shown, after collimation by the lens, the diameter D of the light spot formed by a single LED 1 on the target working plane is designed to be equal to the spacing between m LEDs. For example, when m=4 and the spacing between individual LEDs is L, the diameter D of the light spot of a single LED is 4L. This setting allows the light spots of a single LED to seamlessly connect and combine to form a complete bright fringe when the control module synchronously illuminates LEDs in the same phase position (such as the first column in each LED array), and the period of this bright and dark fringe (i.e., the fringe spacing) is exactly equal to the diameter D of the single light spot.

[0033] like Figure 4b As shown in the schematic diagram of the light intensity distribution, simulation results demonstrate that the light intensity distribution along the central cross-section of both single light spots and complete fringes formed by their arrangement exhibits an ideal sinusoidal curve. High-quality sinusoidal fringes form the basis for subsequent high-precision phase calculation and 3D reconstruction algorithms.

[0034] The principle of longitudinal phase shift is exactly the same as that of transverse phase shift, only the controlled dimension is different. For example... Figure 5a and Figure 5c The comparison shows the "bright lines" (i.e., longitudinal stripes) formed by the light source on the working plane at times t5 and t6 in the longitudinal phase shift sequence. This embodiment... Figure 1a The light source structure shown has only one row of LED beads arranged vertically, i.e., N=1. Therefore, only one bright line is obtained from the simulation diagram. If the actual requirement due to the vertical phase shift necessitates arranging more rows of LED beads, i.e., N>1, then multiple parallel bright and dark stripes can be obtained from the simulation diagram.

[0035] More specifically, such as Figure 5a As shown, at time t5, the LEDs in the first row of the LED array are lit; at time t6, the lights switch to the LEDs in the second row of the LED array. This row-sequence switching also achieves the movement of the vertical stripes. Figure 5b and Figure 5dThe comparison is more intuitive, showing the light intensity distribution curves scanned by a line-scan camera at a fixed position (e.g., y=0) at times t5 and t6. It is clear that... Figure 5b and Figure 5d The two curves show a precise phase shift, verifying the successful realization of the longitudinal electronic phase shift. The phase difference also meets the requirement of 2π / m (i.e., 90°).

[0036] It is understood that this embodiment successfully constructs a high-performance line-scan detection programmable phase-shift structured light source through the arrangement of equally spaced LEDs and lens arrays, precise matching design of light spot diameter and fringe period, optical components that generate an ideal sinusoidal light intensity distribution, and fully electronic group control logic. This light source has the following advantages: 1. High brightness output: Efficient collimation by TIR lenses meets the high line frequency illumination requirements of line-scan cameras; 2. Fast and accurate phase shift: Microsecond-level electronic switching, no mechanical delay or wear, high precision and strong reliability; 3. High-quality input signal: The generated fringes have ideal sinusoidal characteristics, providing superior input conditions for 3D reconstruction algorithms. The light source in this embodiment can be perfectly adapted to... Figure 6 The split shooting mode shown and as Figure 7 The efficient unidirectional continuous scanning mode shown fundamentally solves the technical bottlenecks of insufficient brightness in traditional projectors and the bulky and slow mechanical grating phase-shifting system.

[0037] Example 2: Based on Example 1, this example provides a control method for the aforementioned programmable phase-shift structured light source, including the following steps: First, the control module generates control commands according to the preset m-step phase shift method timing (m=4 in this embodiment, i.e., a four-step phase shift method). At each phase shift moment (e.g., t1), the control module synchronously illuminates all periodically arranged LED arrays that are in the exact same relative position (i.e., the same phase). For example, it illuminates all LEDs in the first column of each 4×4 LED array. The LEDs in the same column that are illuminated synchronously, after being collimated by their corresponding lenses, will have their light spots seamlessly stitched together on the target working plane, forming a complete bright fringe with a sinusoidal light intensity distribution. The multiple parallel bright fringes formed by the parallel columns of illuminated LEDs together constitute a pattern like... Figure 4a The light and dark fringes shown are illustrated in the appendix. The sinusoidal distribution characteristics of the light intensity of these fringes can be found in the appendix. Figure 4b .

[0038] Subsequently, when phase shifting is required, the control module sequentially switches the illuminated LED groups according to the corresponding phases of the LEDs. By precisely changing the groups of illuminated LEDs (i.e., switching phases), the synthesized sinusoidal bright and dark stripes are displaced on the working plane, thereby achieving purely electronic stripe phase shifting without any mechanical moving parts.

[0039] More specifically, this embodiment decomposes the phase shifting process of the above-mentioned step phase shifting method into sub-steps in two dimensions: horizontal and vertical.

[0040] Combination Figure 3 , Figure 4a , Figure 4b As shown, the transverse phase shift sub-step is implemented as follows: The control module sequentially and synchronously illuminates LEDs located in the same column sequence position in different LED arrays according to the first preset timing sequence (such as the time sequence of t1, t2, t3, t4).

[0041] At time t1 (0° phase): the LEDs in columns 1, 5, 9... of all LED arrays (i.e., the first column of each 4×4 subarray) are lit.

[0042] At time t2 (90° phase): as follows Figure 4a (Simulation diagram of bright and dark stripes at time t2) shows that the control module switches commands to light up the LEDs in columns 2, 6, 10... of all arrays (i.e., the second column of each subarray). See attached... Figure 3 As shown, because the physical position of the LED bead is shifted laterally by a spacing L, and the diameter of a single light spot D is equal to 4L (i.e., one fringe period), the synthesized sinusoidal fringe is shifted laterally by 1 / 4 of a period on the plane.

[0043] At time t3 (180° phase): Similarly, the control module switches the command to light up the LEDs in columns 3, 7, 11... of all arrays (i.e., the 3rd column of each subarray).

[0044] At time t4 (270° phase): Similarly, the control module switches the command to light up the LEDs in columns 4, 8, 12... of all arrays (i.e., the 4th column of each subarray).

[0045] Figure 4b The image shows the light intensity distribution curve obtained by the line scan camera at time t2, which is a standard sine wave. When a lateral phase shift occurs, this sine wave shifts horizontally. From time t1 to t2, the phase change of this curve is 2π / 4, or 90°. Repeating this process to times t3 and t4 achieves lateral phase shifts of 180° and 270°, respectively.

[0046] Combination Figures 5a-5d As shown, the principle of the longitudinal phase shift sub-step is the same as that of the transverse phase shift, but the control dimension is carried out along the row direction.

[0047] The control module sequentially and synchronously illuminates LEDs located in the same row position in different LED arrays according to the second preset timing sequence (such as the time sequence of t5, t6, t7, t8).

[0048] At time t5 (0° phase): the LEDs in the first row of the entire LED array are illuminated. Figure 1a The example light source structure shown creates a vertical "bright line" on the working plane, as follows. Figure 5a As shown in the simulation diagram.

[0049] At time t6 (90° phase): as follows Figure 5c As shown, the control module switches to illuminating the second row of LEDs in the LED array, causing the bright line to shift longitudinally on the plane.

[0050] At time t7 (180° phase): Similarly, the control module switches to illuminating the LEDs in the 3rd row of the LED array, causing the bright line to shift longitudinally on the plane.

[0051] At time t8 (270° phase): Similarly, the control module switches to illuminating the LEDs in the 4th row of the LED array, causing the bright line to shift longitudinally on the plane.

[0052] Figure 5b and Figure 5d These are the light intensity distribution curves acquired by a line scan camera at a fixed position (e.g., on the horizontal line y=0) at times t5 and t6, respectively. (Comparison) Figure 5b and Figure 5d The two curves clearly show a significant phase shift between them. This phase shift is caused by the switching of the lit LEDs from the first row to the second row, and the phase difference is precisely 2π / 4, or 90°. Figure 5b and Figure 5d The results demonstrate that by switching the LED groups in row order, it is possible to achieve the electronic phase shift of the longitudinal stripes.

[0053] The control method provided in this embodiment completes the phase shift process through electrical signal switching at a speed of microseconds (far faster than any mechanical motion). The phase shift accuracy is determined by the processing and arrangement accuracy of the LED beads, eliminating the backlash error, wear, and vibration problems of the mechanical system. The lateral and longitudinal phase shift sub-steps can be flexibly combined or executed individually through programming (such as completing all lateral phase shifts first and then executing longitudinal phase shifts, or executing them alternately) to adapt to different detection scenarios, greatly improving the long-term reliability and stability of the system. The fast electronic phase shift method supports efficient line scan detection schemes, making it possible to quickly acquire images of all phases during a single pass of the object under test, greatly improving detection efficiency.

[0054] Example 3: Based on the foregoing embodiments, this embodiment also provides an industrial line scan detection method, the basic system layout for implementing this method is as follows: Figure 2 As shown, it includes a programmable phase-shift structured light source, a line scan camera, and an object under test (DUT). The DUT is moved by a motor. Figure 6 and Figure 7 As shown, the shooting position of the line scan camera ( Figure 6 The position of the dashed line (in the middle) is fixed in space. Therefore, driven by the motor, different parts of the object being measured will pass through the fixed imaging line in front of the camera in sequence.

[0055] This embodiment provides an industrial line scan detection method, including steps S1 to S3.

[0056] S1, causing the object to be tested to move relative to the line scan camera and the programmable phase-shifting structured light source in a predetermined direction.

[0057] like Figure 2 As shown, this step involves moving the object under test using a motor, thereby achieving relative movement between the object under test, the camera, and the light source. For example, activating a drive mechanism (such as a linear motor) causes the object under test to move at a constant speed relative to the light source and the camera in a predetermined direction.

[0058] S2, during the movement of the object under test, the emission mode of the light source is switched according to the phase shift sequence of the m-step phase shift method (e.g., m=4), and the line scan camera simultaneously acquires multiple images of the object under test containing different phase brightness and darkness fringes. The following explanation uses a combination of 4 horizontal phase shift steps and 4 vertical phase shift steps as an example.

[0059] Throughout the movement of the object under test, the control module rapidly switches the light emission mode of the light source (i.e., controls the illumination of different phase groups of LEDs) strictly according to the timing sequence of the 4-step phase-shifting method. The line scan camera is strictly synchronized with the light source switching signal. As the object moves, the camera, at its fixed shooting position, continuously acquires images of the object under test passing through that position. Each time the light source switches to a new phase mode, the camera acquires a line or a strip image under that phase. Through the continuous movement of the object, a series of images covering the entire test area of ​​the object and including all necessary phases (such as 0°, 90°, 180°, 270°) are finally acquired.

[0060] S3, based on the acquired multiple images, reconstructs the three-dimensional shape of the object under test.

[0061] This step inputs multiple images with different phases acquired in step S2 into the 3D reconstruction algorithm. Algorithms such as phase unwrapping are used to calculate the intensity changes of the same object point in different phase images, determining its absolute phase. Then, combined with system calibration parameters, the complete 3D shape of the object under test is finally reconstructed.

[0062] Example 4: Based on Example 3, this example performs the following in step S2: Figure 6 The image acquisition scheme shown is a multi-stage complete shooting mode during the reciprocating motion of the object under test.

[0063] In this embodiment, the image acquisition process is as follows: 1. Initial reciprocating stroke and first phase image acquisition: The system starts from the initial position.

[0064] First, the control module sets the light source to the first fixed emission mode in the 4-step phase-shifting method (e.g., the row or column lighting mode corresponding to the 0° phase). Then, as shown in the attached... Figure 6 As shown, the motor drives the object under test to begin its first unidirectional movement. Throughout this movement, the light source mode remains unchanged, and the line scan camera continuously acquires image lines at its fixed shooting position. After the object under test finishes moving, the camera has scanned the entire test area of ​​the object and stitched it together internally to generate a complete image of the object under test with 0° phase fringes.

[0065] 2. Reset and Phase Switching: After the first complete image is acquired, the control module drives the motor to reset the object under test to the starting position (i.e., the attached image). Figure 6 (The return step in the process). Subsequently, the control module switches the light source to the next fixed emission mode (e.g., the LED group corresponding to a 90° phase).

[0066] 3. Repeat until completion: The test object begins its second unidirectional movement, repeating the above acquisition process to obtain a second complete 90° phase image. This "reset-phase switching-unidirectional movement acquisition" cycle continues until, according to the phase shift method requirements (e.g., 4 or 8 cycles), all the required complete test object images with different phases are obtained.

[0067] Example 5: Based on Example 3, this example performs the following in step S2: Figure 7 The image acquisition scheme shown is a scheme in which the object under test is scanned by moving in only one direction.

[0068] In this embodiment, step S2 is executed as follows: First, control the object to be tested to begin moving continuously and unidirectionally at a constant speed (as shown in the attached image). Figure 7 The object under test moves from its position at time t1 to its position at time t3 (without returning). During this movement, the control module strictly follows the phase shift sequence, rapidly switching between two emission modes of the light source: the first emission mode is used to perform the lateral phase shift sub-step (i.e., sequentially illuminating different columns of LED groups to generate lateral stripe phase shift), and the second emission mode is used to perform the longitudinal phase shift sub-step (i.e., sequentially illuminating different rows of LED groups to generate longitudinal stripe phase shift). The execution order of these two modes can be interchanged according to the detection requirements. Each time the light source switches its emission mode (e.g., from the first step of lateral phase shift to the second step, or from lateral phase shift to longitudinal phase shift), the line scan camera located at a fixed shooting position simultaneously acquires an image of one line (or one narrow band) of the object under test.

[0069] Throughout the unidirectional movement of the object under test, the light source continuously switches rapidly between the two emission modes at each step, while the camera synchronously acquires data. Finally, all the sequentially acquired image rows are stitched together into a long composite image. Since the switching of the light source is strictly performed according to a preset, periodically repeating phase shift sequence (for example, a complete cycle includes 4 horizontal steps and 4 vertical steps, totaling 8 modes), all image rows corresponding to the same emission mode (i.e., the same phase) can be extracted from this composite image according to the switching order of the light source (for example, all rows acquired in the first step of the first emission mode can be extracted), and each can be reassembled into a complete image of the object under test with a specific phase, thereby separating all the different phase images required by the m-step phase shift method.

[0070] To achieve the aforementioned efficient and accurate image separation and 3D reconstruction, this embodiment also imposes strict requirements on the switching speed. Specifically, the switching time between the first and second emission modes, as well as between steps within the same mode, must be less than 100 microseconds, for example, 50 microseconds. This extremely short switching time ensures that the displacement of the surface area of ​​the object being measured corresponding to adjacent image rows acquired by the line scan camera in continuous, short-interval different emission modes is minimal due to the movement of the object, and can be approximated as areas corresponding to essentially the same position on the surface. This characteristic is crucial to ensuring that the phase images separated from the synthetic image of a single scan can be precisely aligned in space, thereby meeting the algorithmic requirements of subsequent phase calculation and high-precision 3D reconstruction.

[0071] The above embodiments of the present invention provide a programmable phase-shift structured light source, control method, and industrial line scan detection method. By arranging LEDs in an m×m matrix with equal spacing and configuring a TIR (total internal reflection) lens for each LED to collimate the light, the diameter of the light spot formed by a single LED on the target working plane is precisely equal to the spacing between m LEDs. The control module synchronously illuminates LEDs in the same phase position (such as in the same row or column) according to a preset phase-shift sequence (e.g., a four-step phase-shift method). The resulting light spots with a sinusoidal intensity distribution are seamlessly stitched together to form complete sinusoidal stripes. By rapidly and sequentially switching the illuminated LED groups (e.g., switching by column order to achieve lateral phase shift, and switching by row order to achieve vertical phase shift), electronic phase shifting of the stripes can be achieved without any mechanical movement. In industrial line scan inspection applications, this method supports two efficient modes: one is a mode in which the test object moves back and forth and the phase images are captured completely; the other is a mode in which the test object moves continuously in only one direction, the light source switches between horizontal and vertical phase shift modes at a speed of microseconds, the camera acquires image lines synchronously, and finally all phase images are separated from a composite image.

[0072] This invention first achieves a significant improvement in phase shift speed and accuracy. The electronic phase shift speed can reach the microsecond level, far exceeding that of mechanical methods, and the accuracy is guaranteed by the precision of the lamp chip manufacturing and arrangement, eliminating backlash error and wear. Second, the light source system has high reliability and a compact structure, completely eliminating the need for precise mechanical displacement devices, simplifying the system structure and improving long-term stability. Third, this invention offers high illumination quality and detection efficiency. The TIR lens ensures high brightness output, meeting the requirements of line scan cameras, and generating high-quality sinusoidal fringes. In particular, it supports a highly efficient mode that allows for the acquisition of all phase images in a single pass of an object, greatly improving the throughput of online detection. Finally, this invention offers flexible control; the timing of lateral and longitudinal phase shifts can be flexibly configured through software programming to adapt to the needs of different detection scenarios.

[0073] It should be noted that the descriptions of each embodiment in the above embodiments have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0074] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0075] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in one or more blocks of the flowchart illustrations and / or one or more blocks of the block diagrams.

[0076] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means that implement the functions specified in one or more flowcharts and / or one or more block diagrams.

[0077] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, such that the instructions, which execute on the computer or other programmable apparatus, provide steps for implementing the functions specified in one or more flowcharts and / or one or more block diagrams.

[0078] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0079] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A programmable phase-shifting structured light source, characterized in that, It includes an LED module, a lens module, and a control module, among which: The lamp module includes multiple lamp arrays arranged periodically in rows and / or columns, each lamp array including multiple lamps arranged in an m×m pattern, where m>1; The lens module includes multiple lenses arranged one-to-one with multiple LED beads, used to collimate the light emitted by the corresponding LED beads and project it onto the same working plane. The control module is electrically connected to the LED beads and is used to independently control the turning on and off of each LED bead. The control module is configured to control the synchronous lighting of lamps with the same phase in different lamp arrays according to a preset phase shift timing sequence, so as to form periodic bright and dark stripes on the working plane. The diameter of the light spot of a single LED on the working plane is equal to the stripe spacing of the bright and dark stripes.

2. The programmable phase-shifting structured light source according to claim 1, characterized in that, In the lamp module, the horizontal and vertical spacing between adjacent lamps are the same.

3. The programmable phase-shifting structured light source according to claim 1, characterized in that, According to the lighting sequence of the LEDs, the phase difference between LEDs at adjacent lighting times is 2π / m.

4. A programmable phase-shifting structured light source according to claim 3, characterized in that, The light intensity along the diameter of a single LED spot exhibits a sinusoidal distribution, and the light intensity through the center of the spot in the bright and dark stripes also exhibits a sinusoidal distribution.

5. A programmable phase-shifting structured light source according to claim 1, characterized in that, The lens is a total internal reflection lens.

6. A programmable phase-shifting structured light source according to claim 5, characterized in that, The lens includes a transmission zone in the middle and a reflection zone around the transmission zone.

7. A programmable phase-shifting structured light source according to claim 1, characterized in that, All the LEDs are located on the same plane.

8. A control method for a programmable phase-shift structured light source, characterized in that, Based on any one of claims 1 to 7, the programmable phase-shift structured light source comprises: According to the phase shift timing of the m-step phase shift method, the lamps with the same phase in different lamp arrays are controlled to be lit synchronously to form periodic bright and dark stripes on the working plane. The phase shift of the bright and dark stripes is achieved by sequentially switching the lit LED beads.

9. The control method for a programmable phase-shifting structured optical source according to claim 8, characterized in that, The m-step phase shift method includes performing transverse phase shift sub-steps and longitudinal phase shift sub-steps; The transverse phase shifter step includes: According to the first preset timing sequence, the LEDs located in the same column position in different LED arrays are lit synchronously in sequence to achieve the phase shift of the bright and dark stripes in the horizontal direction. The phase difference of each horizontal phase shift is 2π / m. The longitudinal phase shift sub-step includes: According to the second preset timing sequence, LEDs located in the same row position in different LED arrays are lit synchronously in sequence to achieve phase shift of bright and dark stripes in the vertical direction. The phase difference of each vertical phase shift is 2π / m.

10. An industrial line scan detection method, characterized in that, Based on the control method described in claim 8 or 9, the industrial line scan detection method includes: S1, causing the object to be tested to move relative to the line scan camera and the programmable phase-shifting structured light source in a predetermined direction; S2, during the movement of the object under test, the light emission mode of the light source is switched according to the phase shift sequence of the m-step phase shift method, and the line scan camera simultaneously acquires multiple images of the object under test containing different phase brightness and darkness stripes; S3, based on the acquired multiple images, reconstructs the three-dimensional shape of the object under test.

11. The industrial line scan detection method according to claim 10, characterized in that, Step S2 specifically includes: Control the object under test to perform multiple reciprocating movements; During each reciprocating movement, the light source remains in a fixed phase emission mode in the m-step phase shift method, and the line scan camera acquires an image of the test object that matches the current phase during the unidirectional movement of the test object. After each reciprocating movement, the object under test is reset to the starting position, and the light source is switched to the emission mode corresponding to the next phase in the m-step phase shift method. The image acquisition process is repeated until images of the object under test with all different phases are obtained.

12. The industrial line scan detection method according to claim 10, characterized in that, Step S2 specifically includes: Control the object under test to begin continuous movement; During the movement of the object under test, the first and second emission modes of the light source are rapidly switched in a phase shift sequence, and the line scan camera synchronously acquires an image of the object under test each time the emission mode is switched. In the first light emission mode, the transverse phase shifter step is performed; in the second light emission mode, the longitudinal phase shifter step is performed; or, The longitudinal phase shifter step is performed in the first light emission mode, and the transverse phase shifter step is performed in the second light emission mode; Multiple images of the object under test acquired continuously are stitched together to form a composite image. Based on the switching order of the emission modes, images of different phases required by the m-step phase shifting method are separated from the composite image.

13. The industrial line scan detection method according to claim 12, characterized in that, The switching time between the first and second light emission modes of the light source is less than 100 microseconds, so that the image lines acquired by the line scan camera in different light emission modes correspond to the area at basically the same position on the surface of the object under test.

Images