A method for designing a CL system and planning a field of view of a dual imaging module
By employing a dual-imaging module design and field-of-view planning approach, the problem of low detection efficiency in single-imaging module CL systems is solved, achieving efficient and accurate detection applicable to various system layouts.
Patent Information
- Application Number
- CN202611131186.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-29
- Publication Date
- 2026-08-25
AI Technical Summary
Existing single-imaging module (CL) systems have low detection efficiency when inspecting large or dispersed areas, making it difficult to meet the needs of modern electronic manufacturing production lines.
A dual-imaging module design is adopted. By rationally determining the spacing constraints and field of view planning of the two imaging modules, synchronous scanning of the two imaging modules is achieved, and the field of view pairing is optimized to improve detection efficiency.
It significantly improves detection efficiency, eliminates X-ray crosstalk, avoids collision risks during scanning, achieves an optimized scanning path and minimizes the number of detections, reduces costs, and is applicable to various system layouts.
Smart Images
Figure CN122631004A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the fields of X-ray nondestructive testing and three-dimensional imaging technology, specifically to a CL system design and field-of-view planning method with dual imaging modules. Background Technology
[0002] With the rapid development of the electronics and information industry, printed circuit boards (PCBs), as the core carrier and interconnection components of electronic products, directly affect the reliability and lifespan of end products through their manufacturing quality. Especially in applications with extremely high reliability requirements, such as 5G communication, high-performance computing, aerospace, and automotive electronics, the processing quality of interconnection structures on PCBs, such as back-drilled holes, blind vias, and buried vias—including hole position accuracy, hole wall roughness, residual adhesive, and plating uniformity—has become a key factor affecting signal integrity and electrical connection reliability. Therefore, efficient and accurate non-destructive testing of these critical structures during PCB manufacturing has significant engineering application value.
[0003] Currently, X-ray computed tomography (CL) has become one of the mainstream methods for non-destructive testing of sheet-like targets such as PCBs. CL technology employs an asymmetric scanning geometry, with the X-ray source and detector moving along specific trajectories on either side of the object under test. This allows for the acquisition of projection data of the target area within a limited angular range, and the reconstruction algorithm is used to restore the three-dimensional structural information of the object's interior. Compared to traditional computed tomography (CT), CL technology has a natural advantage for flat sheet objects, achieving high spatial resolution while maintaining a large inspection area. Therefore, it is widely used for non-destructive testing and defect identification of thin-plate structures such as PCBs, flat panel displays, and MEMS devices.
[0004] In existing CL (Clearing and Conveying) systems, a circular motion scanning imaging mode using a single X-ray source and a single detector is commonly employed. The basic operation involves the X-ray source and detector being positioned on opposite sides of the Field of View (FOV) and moving synchronously in a circular motion around the central axis of the FOV. During this motion, X-ray projection images are acquired from multiple angles, and the internal structural information of the FOV region is ultimately obtained through a 3D reconstruction algorithm. However, this single-imaging-module operating mode has a significant efficiency bottleneck: a single complete circular scan can only acquire data for one FOV region. When the PCB board under test is large or the areas to be inspected are widely distributed, multiple repeated scans are required to cover the entire target area, resulting in excessively long overall inspection times and failing to meet the urgent demand for inspection efficiency in modern electronic manufacturing production lines. Summary of the Invention
[0005] To overcome the shortcomings of the prior art, the present invention aims to provide a CL system design and field-of-view planning method with dual imaging modules. By reasonably determining the spacing constraints when the two imaging modules scan synchronously and optimizing the pairing of multiple fields of view, the two imaging modules can scan the paired two fields of view synchronously, thereby greatly improving the detection efficiency.
[0006] To achieve the objective of this invention, the following solution is adopted: A method for designing and planning the field of view of a dual-imaging module CL system includes the following steps: S1: Obtain the test area information of the object to be tested, wherein the test area information includes the position information of multiple test feature points; S2: Determine the spacing constraints that must be satisfied between the two field centers in a dual imaging module system consisting of two imaging modules, so that the two imaging modules can scan simultaneously. S3: Based on the position information of the feature points to be tested, divide all the feature points to be tested into multiple fields of view, with each field of view covering at least one feature point to be tested; S4: Under the premise of satisfying the spacing constraint condition, at least a portion of the multiple fields of view are paired up to form at least one field of view pair, and the unpaired fields of view are treated as independent fields of view. S5: Controls two sets of imaging modules to synchronously scan and acquire projection data of the two fields of view in each field of view pair, and controls a single set of imaging modules to scan and acquire projection data of an independent field of view; S6: Perform 3D reconstruction on the projection data collected from each field of view to obtain the 3D information of each field of view.
[0007] Furthermore, the spacing constraint conditions include: The distance between the focal points of the X-ray sources in the two imaging modules is equal to the distance between the centers of the two detectors, and neither is less than the minimum distance allowed by the dual imaging module system. The minimum allowable spacing of the dual imaging module system is determined by the distance from the focal point of the X-ray source to the center of the field of view, the distance from the center of the field of view to the center of the detector, the tilt angle of the line connecting the focal point of the X-ray source to the center of the detector, the emission angle of the X-ray source, the minimum installation distance between the centers of the two detectors, and the minimum installation distance between the two X-ray sources.
[0008] Furthermore, the minimum allowable spacing of the dual imaging module system is calculated by the following formula: Where SOD is the distance from the focal point of the X-ray source to the center of the field of view to be reconstructed, and ODD is the distance from the center of the field of view to the center of the detector. The angle of inclination of the line connecting the focal point of the X-ray source to the center of the detector. The emission angle of the radiation source. This is the minimum installation distance between the centers of the two detectors. This represents the minimum installation distance between two radiation sources.
[0009] Furthermore, in step S4, the pairing method of at least a portion of the multiple fields of view is matched in pairs to correspond to the spatial motion layout of each X-ray source and each detector in the two imaging modules. The motion layout includes a layout in which two radiation sources share a guide rail and two detectors share a guide rail, or a layout in which two radiation sources use guide rails independently and two detectors use guide rails independently.
[0010] Furthermore, when a layout is adopted in which two radiation sources share a guide rail and two detectors share a guide rail, the specific method for pairing at least a portion of the multiple fields of view in pairs is as follows: Search for the feature points to be tested layer by layer along one direction of the object to be tested. In the same layer, generate the field of view in another direction. Arrange the generated field of view into field of view pairs in order, and ensure that the distance between the two field of view centers in each field of view pair is not less than the minimum distance.
[0011] Furthermore, when a layout is adopted in which two X-ray sources each use their own guide rails independently and two detectors each use their own guide rails independently, the specific method for pairing at least a portion of the multiple fields of view in pairs is as follows: First, perform single-view clustering planning on all the feature points to be tested to obtain several field centers. Then, calculate the group center of all field centers. Divide the field centers into different quadrants according to the group centers. Pair the field centers in the corresponding quadrants and ensure that the distance between the two field centers in each field pair is not less than the minimum distance.
[0012] Furthermore, in step S5, when synchronously scanning and acquiring projection data, the X-ray sources and detectors in the two imaging modules all move in a circle around the central vertical axis of their respective fields of view at the same angular velocity, and acquire projection data from multiple angles during the circular motion, so that the distance between the two X-ray sources and the distance between the two detectors remain unchanged during the scanning process.
[0013] Furthermore, after step S1 and before step S2, a system calibration step for the dual imaging modules is also included: placing a calibration plate with markers at the field of view positions of the two imaging modules respectively, changing the positions of the detector and the X-ray source to acquire multiple projected images, extracting the image positions of the markers, and minimizing the residual between the image positions and the theoretical positions using the least squares method to obtain the pose relationship between the detector and the X-ray source in a unified coordinate system.
[0014] Furthermore, in step S6, the three-dimensional reconstruction uses the FDK reconstruction algorithm of the CL system to reconstruct the projection data of each field of view separately.
[0015] Furthermore, the object to be tested is a flat plate, and the feature point to be tested is the hole position to be tested; The size of each field of view is a pre-defined effective field of view size, which has deducted the edge effect region of the 3D reconstruction.
[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention significantly improves scanning imaging efficiency. It employs a dual-imaging module system with two imaging modules. After determining the spacing constraints to ensure simultaneous scanning by both modules, at least a portion of the multiple fields of view are paired to form field-of-view pairs. Subsequently, the two imaging modules synchronously scan and acquire projection data from the two fields of view in each pair. Compared to the traditional single-source, single-detector system, which can only acquire data from one field of view (FOV) per circular motion, this invention can simultaneously acquire data from two FOVs in a single scan, nearly doubling the data acquisition efficiency and significantly shortening the total time for whole-board inspection. This better meets the urgent demand for inspection efficiency in modern electronic manufacturing production lines.
[0017] 2. This invention fundamentally eliminates X-ray crosstalk, ensuring imaging quality. The invention defines the required spacing constraint between the centers of the two fields of view. This constraint defines the correspondence between the focal distance between the X-ray sources and the center distance between the detectors in the two imaging modules, ensuring that each X-ray source's stereo emission angle contains only one corresponding detector, avoiding data contamination caused by the same detector receiving X-rays from multiple sources simultaneously. Field-of-view pairing and synchronous scanning based on this constraint are both premised on this spacing constraint, thus ensuring the purity of the projection data and the accuracy of the reconstructed image while achieving parallel scanning acquisition.
[0018] 3. This invention achieves an optimized scanning path, avoiding collision risks during the scanning process. The invention rationally limits the minimum distance between X-ray sources and detectors through spacing constraints, and ensures that the distance between the centers of the two fields of view in each field of view pairing is not less than this minimum distance. This design allows the two imaging modules to maintain a safe distance during synchronous circular scanning motion, avoiding physical collisions between different X-ray sources, different detectors, and between X-ray sources and detectors, while also ensuring that each imaging module has independent movement space, reducing the mechanical design difficulty and control complexity of the system.
[0019] 4. This invention minimizes the number of scans, reducing detection costs. Based on the actual distribution of the feature points to be measured, this invention divides all feature points into multiple fields of view and pairs these fields of view as much as possible while satisfying spacing constraints, completing the imaging acquisition of the entire area to be measured with the fewest possible scans. Unpaired independent fields of view only require a few single-module scans to complete supplementary acquisition. This dynamic programming approach avoids the time and resource waste caused by repeatedly scanning the same area or using unreasonable scan paths in traditional methods, improving efficiency while reducing X-ray source wear and tear and overall detection costs.
[0020] 5. The method of this invention has strong versatility and is applicable to various system layouts. The method steps of this invention are decoupled from specific mechanical layout methods, making it applicable to the hardware architecture of various dual-imaging module systems. Regardless of whether the two imaging modules adopt a shared or independent guide rail motion layout, as long as the determined spacing constraints are met, field planning, pairing, synchronous scanning, and 3D reconstruction can be completed. This versatility allows this invention to flexibly adapt to CL systems with different mechanical design requirements, and it has good prospects for industrial application.
[0021] 6. This invention forms a complete automated inspection process. From acquiring information about the area to be tested to outputting 3D reconstruction results, the various stages of this invention are logically connected and data transmission is clear. The determined spacing constraints provide a basis for field-of-view pairing, the generated field-of-view pairs and independent fields of view provide control commands for scanning and acquisition, and the acquired projection data provides the data foundation for 3D reconstruction. The entire method fully covers all stages from information input to 3D information output, and can be directly integrated into the control system of CL inspection equipment to realize a fully automated process from loading the object to be tested to outputting the inspection report. Attached Figure Description
[0022] Figure 1 This is a flowchart of the CL system design and field-of-view planning method for dual imaging modules in an embodiment of the present invention; Figure 2 This is a schematic diagram illustrating the collaborative operation of dual X-ray sources and dual detectors in an embodiment of the present invention; Figure 3 This is a schematic diagram illustrating the geometric relationship between the X-ray source and the detector in an embodiment of the present invention; Figure 4 This is a schematic diagram of a common x-direction slide rail for the ray sources in an embodiment of the present invention; Figure 5 This is a schematic diagram of the first row of field of view planning in an embodiment of the present invention; Figure 6 This is a schematic diagram showing that each ray source in this embodiment of the invention uses a slide rail in the x-direction. Figure 7This is a schematic diagram illustrating the division of the field of view center into four quadrants in an embodiment of the present invention; Figure 8 This is a schematic diagram illustrating an example of the operation of the dual imaging module in an embodiment of the present invention; Figure 9 This is a design diagram of the motion range of the detector and the radiation source in an embodiment of the present invention; Figure 10 This is a design diagram showing the positional relationship between the detector and the radiation source in an embodiment of the present invention. Detailed Implementation
[0023] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.
[0024] like Figure 1-10 As shown, this invention provides a CL system design and field-of-view planning method with dual imaging modules, primarily targeting the detection of flat objects such as large-size printed circuit boards (PCBs). When scanning and imaging plate-shaped targets, two X-ray sources and two X-ray detectors are used in conjunction, enabling the simultaneous acquisition of data from two fields of view (FOV). Compared to traditional methods that can only acquire one FOV at a time, this invention significantly improves scanning and imaging efficiency.
[0025] like Figure 1 As shown, the CL system design and field-of-view planning method for dual imaging modules in this embodiment of the invention includes the following steps: S1: Obtain the test area information of the object to be tested, wherein the test area information includes the position information of multiple test feature points.
[0026] S2: Determine the spacing constraints that must be satisfied between the two field centers in a dual imaging module system consisting of two imaging modules, so that the two imaging modules can scan simultaneously.
[0027] S3: Based on the position information of the feature points to be tested, divide all the feature points to be tested into multiple fields of view, with each field of view covering at least one feature point to be tested.
[0028] S4: Under the premise of satisfying the spacing constraint, at least a portion of the multiple fields of view are paired up to form at least one field of view pair, and the unpaired fields of view are treated as independent fields of view.
[0029] S5: Controls two sets of imaging modules to synchronously scan and acquire projection data of the two fields of view in each field of view pair, and controls a single set of imaging modules to scan and acquire projection data of an independent field of view.
[0030] S6: Perform 3D reconstruction on the projection data collected from each field of view to obtain the 3D information of each field of view.
[0031] The design of the CL system and the field-of-view planning method of the dual imaging module in this embodiment of the invention will be further described in detail below.
[0032] like Figure 2 As shown, the system consists of two imaging modules comprised of two X-ray sources and two detectors. By controlling the emission angle of the X-ray sources, the physical distance between the two detectors, and the distance between the two X-ray sources, it can be ensured that each detector receives X-rays emitted from only one source, avoiding interference between different sources. When planning the FOVs of the two imaging modules, the goal is to use as few FOVs as possible to acquire images of all areas under test (such as the drilled holes on a PCB board) while maintaining the spacing between the two FOVs. This allows the two imaging modules to work synchronously, nearly doubling the efficiency of data acquisition.
[0033] In this embodiment, the system consists of two imaging modules composed of two X-ray sources and two detectors. The emission angle of the X-ray sources is controlled between 80 and 120 degrees, and the distances between the X-ray sources and detectors are both controlled to be greater than 200 mm. The distance from the focal point of the X-ray source to the center of the field of view (FOV) to be reconstructed (SOD) is 10-90 mm, and the distance from the center of the FOV to the center of the detector (ODD) is 70-230 mm. Within the stereo emission angle of each X-ray source, there is only one corresponding detector, avoiding the situation where a single detector receives X-rays from multiple X-ray sources, thus preventing X-ray interference.
[0034] In this embodiment, the focal distance of the radiation source is... Spacing from the center of the detector They are equal, and none are less than the minimum spacing allowed by the system. . Calculated using the following formula: in, The angle of inclination of the line connecting the focal point of the X-ray source to the center of the detector. The emission angle of the radiation source. It is the minimum installation distance between the centers of the two detectors. It is the minimum installation distance between two radiation sources.
[0035] In this embodiment, the calibration process used by the system is as follows: a) Place the calibration plate with the marker ball at the fov position of each of the two imaging modules.
[0036] b) While ensuring that the calibration plate can image the corresponding detector, change the position of the detector and the X-ray source to acquire projection images at different positions.
[0037] c) Extract the image position of each marker ball, and use the least squares calibration method to minimize the residual between the image position and the theoretical position of each marker ball. This completes the calibration and yields the positional relationship between the detector and the X-ray source in a unified coordinate system.
[0038] In this embodiment, the system's data acquisition method is as follows: all radiation sources and detectors perform synchronous circular motions around the central vertical axis of their respective fovs at the same angular velocity, simultaneously acquiring X-ray projection data corresponding to various angles on the circumference. This acquisition method keeps the distance between the two radiation sources and the distance between the two detectors constant, avoiding collisions and preventing radiation interference between different radiation sources.
[0039] In this embodiment, the layout of the two imaging modules is as follows: two X-ray sources share a single slide rail (set as the x-direction), with a spacing greater than the minimum spacing. At this time, the two ray sources can simultaneously achieve movement in the x and y directions, and their x coordinates remain the same throughout the movement, such as... Figure 4 As shown. The two detectors also share a single x-axis slide rail, with a spacing greater than the minimum spacing. It can also achieve movement in both the x and y directions simultaneously, and its x coordinate remains the same throughout the movement.
[0040] At this point, the fovea sizes of the two imaging modules are identical. Let the width and height of the fovea be w and h, respectively, corresponding to the x and y directions of the system. The fovea here already considers the edge effects of 3D reconstruction, removing invalid edges and resulting in a usable fovea. Taking PCB board hole position measurement as an example, the system's dual fovea planning process is as follows: a) Find the hole with the smallest y-coordinate. .
[0041] b) Set the search range for the y-value as... Find all the test points within this range. , where r is the reconstruction radius required for a single borehole measurement.
[0042] c) Find the test point within the above search. Minimum aperture in the x-direction .
[0043] d) with The range determines the first fov: fov1.
[0044] e) For the remaining test points Repeat step cd until the search range for y-values is obtained. All fovs within: fov1-fovN, where N is the number of fovs.
[0045] f) From the first Starting with a certain number of fovs, determine if the distance from the center of the first fov to the center of the first fov is less than 1. If so, then determine the next fov (the first fov). (number of cases), until the distance between the centers of two fovs is not less than 1 / 2. .
[0046] g) Using the first fov (fov1) and the Mth fov (fovM) as a pair, the second and the (M+1)th fov as a second pair, and so on, we can... All fovs within the range are planned as paired fov pairs, and those that do not pair successfully are retained as independent fovs.
[0047] h) When performing field-of-view scanning imaging, adjust the focal distance between the X-ray sources to be equal to the distance between the current fov and the center. Each X-ray source is responsible for one of the fovs, and data acquisition of two fovs is performed simultaneously.
[0048] i) Use another imaging module to collect data from the independent FOV.
[0049] j) From To begin, plan the remaining holes with y-coordinates greater than this value, and repeat the steps of ai until the planning and imaging of all holes on the entire sheet are completed.
[0050] In this embodiment, the layout of the two imaging modules is as follows: Figure 6 As shown, each of the two X-ray sources uses a slide rail (set as the x-direction), enabling independent movement in both the x and y directions. Each of the two detectors also uses a slide rail in the x-direction, allowing independent movement in both the x and y directions. The distance between the X-ray source focal points and the distance between the detector centers are both greater than the minimum distance. : At this point, the fovea sizes of the two imaging modules remain identical. Let the width and height of the fovea be w and h, respectively, corresponding to the x and y directions of the system. The fovea here already considers the edge effects of 3D reconstruction, removing invalid edges and resulting in a usable fovea. Taking PCB board hole position measurement as an example, the dual fovea planning process of the system is as follows: a) Use conventional clustering to perform single fov planning on the test holes of the whole plate to obtain the center positions of N fovs, where N is the number of fovs on the whole plate.
[0051] b) Calculate the group center of N fovs. : By dividing all fov (centers) into four quadrants (1, 2, 3, and 4) through the group center, such as... Figure 7 As shown.
[0052] c) Ensure that the distance between the two FOV centers is not less than Under the given conditions, fovs in the first quadrant are paired with fovs in the fourth quadrant, and fovs in the second quadrant are paired with fovs in the third quadrant. The pairing order is from left to right and from top to bottom. Fovs that do not pair successfully are retained as independent fovs.
[0053] d) When performing field-of-view scanning imaging, adjust the focal distance between the X-ray sources to be equal to the center distance between the current fov pairs. Each X-ray source is responsible for one of the fov pairs, and data acquisition of two fov pairs is performed simultaneously.
[0054] e) After completing the scanning of all FOV pairs, scan the individual FOVs separately using one imaging module until the data acquisition of all FOVs on the entire board is completed.
[0055] In this embodiment, the classic FDK reconstruction method of the CL system can be used to perform three-dimensional reconstruction on each of the collected FOV data.
[0056] The following will further illustrate the CL system design and field-of-view planning method of the dual imaging module in this embodiment of the invention with specific engineering examples.
[0057] like Figure 8 As shown, two detectors are located above the system, each using an x-axis slide rail (1100mm travel) and a y-axis slide rail (1000mm travel), allowing for independent xy-plane displacement. Two X-ray sources are located below the system, each using an x-axis slide rail (1000mm travel), a y-axis slide rail (900mm travel), and a z-axis slide rail (100mm travel, starting from below the PCB board), allowing for independent three-dimensional displacement. By changing the Z-axis height of the X-ray sources, the system's reconstruction resolution (magnification) can be adjusted.
[0058] like Figure 9 As shown, the x-axis movement range of both detectors is 0-1100mm, the y-axis movement range of detector 1 is 250-1000mm, and the y-axis movement range of detector 2 is 0-750mm. The x-axis movement range of both radiation sources is 0-1000mm, the y-axis movement range of radiation source 1 is 250-900mm, and the y-axis movement range of radiation source 2 is 0-650mm.
[0059] like Figure 10 As shown, the distance from the focal point of the X-ray source to the center of the FOV to be reconstructed (SOD) is 32 mm, and the distance from the center of the FOV to the center of the detector (ODD) is 128 mm. With an inclination angle of 30 degrees, the z-axis distance from the center of the detector to the center of the X-ray source is 138.56 mm. If the detector pixel size is 50 μm, the system resolution (3D reconstruction accuracy) is 10 μm. The emission angles of both X-ray sources are 100 degrees, and the minimum distance is... .
[0060] The system workflow is as follows: a) Place the PCB board to be tested onto the stage; b) Import the hole position information to be tested on the PCB board; c) Use a CCD positioning camera to accurately position the PCB board and obtain the precise position of the hole position to be tested; d) Perform dual FOV planning based on the hole position; e) Start the X-ray source and detector; f) Control the X-ray source and detector to synchronously acquire data from the planned dual FOV (FOV pair); g) Use the classic FDK algorithm to perform three-dimensional reconstruction on the acquired FOV data; h) Repeat steps fg until the FOV pair is acquired; i) Acquire and reconstruct the remaining single FOV data.
[0061] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.
Claims
1. A design and field-of-view planning method for a dual-imaging module CL system, characterized in that, Includes the following steps: S1: Obtain the test area information of the object to be tested, wherein the test area information includes the position information of multiple test feature points; S2: Determine the spacing constraints that must be satisfied between the two field centers in a dual imaging module system consisting of two imaging modules, so that the two imaging modules can scan simultaneously. S3: Based on the position information of the feature points to be tested, divide all the feature points to be tested into multiple fields of view, with each field of view covering at least one feature point to be tested; S4: Under the premise of satisfying the spacing constraint condition, at least a portion of the multiple fields of view are paired up to form at least one field of view pair, and the unpaired fields of view are treated as independent fields of view. S5: Controls two sets of imaging modules to synchronously scan and acquire projection data of the two fields of view in each field of view pair, and controls a single set of imaging modules to scan and acquire projection data of an independent field of view; S6: Perform 3D reconstruction on the projection data collected from each field of view to obtain the 3D information of each field of view.
2. The CL system design and field-of-view planning method with dual imaging modules according to claim 1, characterized in that, The spacing constraints include: The distance between the focal points of the X-ray sources in the two imaging modules is equal to the distance between the centers of the two detectors, and neither is less than the minimum distance allowed by the dual imaging module system. The minimum allowable spacing of the dual imaging module system is determined by the distance from the focal point of the X-ray source to the center of the field of view, the distance from the center of the field of view to the center of the detector, the tilt angle of the line connecting the focal point of the X-ray source to the center of the detector, the emission angle of the X-ray source, the minimum installation distance between the centers of the two detectors, and the minimum installation distance between the two X-ray sources.
3. The CL system design and field-of-view planning method with dual imaging modules according to claim 2, characterized in that, The minimum allowable spacing of the dual imaging module system is calculated by the following formula: Where SOD is the distance from the focal point of the X-ray source to the center of the field of view to be reconstructed, and ODD is the distance from the center of the field of view to the center of the detector. The angle of inclination of the line connecting the focal point of the X-ray source to the center of the detector. The emission angle of the radiation source. This is the minimum installation distance between the centers of the two detectors. This represents the minimum installation distance between two radiation sources.
4. The CL system design and field-of-view planning method with dual imaging modules according to claim 2, characterized in that, In step S4, the pairing method of at least a portion of the multiple fields of view is matched in pairs to correspond to the spatial motion layout of each X-ray source and each detector in the two imaging modules. The motion layout includes a layout in which two radiation sources share a guide rail and two detectors share a guide rail, or a layout in which two radiation sources use guide rails independently and two detectors use guide rails independently.
5. The CL system design and field-of-view planning method with dual imaging modules according to claim 4, characterized in that, When a layout is adopted in which two radiation sources share a common guide rail and two detectors share a common guide rail, the specific method for pairing at least a portion of the multiple fields of view in pairs is as follows: Search for the feature points to be tested layer by layer along one direction of the object to be tested. In the same layer, generate the field of view in another direction. Arrange the generated field of view into field of view pairs in order, and ensure that the distance between the two field of view centers in each field of view pair is not less than the minimum distance.
6. The CL system design and field-of-view planning method with dual imaging modules according to claim 4, characterized in that, When a layout is adopted in which two X-ray sources each use their own guide rails independently and two detectors each use their own guide rails independently, the specific method for pairing at least a portion of the multiple fields of view in pairs is as follows: First, perform single-view clustering planning on all the feature points to be tested to obtain several field centers. Then, calculate the group center of all field centers. Divide the field centers into different quadrants according to the group centers. Pair the field centers in the corresponding quadrants and ensure that the distance between the two field centers in each field pair is not less than the minimum distance.
7. The CL system design and field-of-view planning method with dual imaging modules according to claim 1, characterized in that, In step S5, when synchronously scanning and acquiring projection data, the X-ray sources and detectors in the two imaging modules move in circles around the central vertical axis of their respective fields of view at the same angular velocity, and acquire projection data from multiple angles during the circular motion, so that the distance between the two X-ray sources and the distance between the two detectors remain unchanged during the scanning process.
8. The CL system design and field-of-view planning method with dual imaging modules according to claim 1, characterized in that, After step S1 and before step S2, the system also includes a step of calibrating the dual imaging modules: placing a calibration plate with markers at the field of view positions of the two imaging modules respectively, changing the positions of the detector and the X-ray source to acquire multiple projected images, extracting the image positions of the markers, and using the least squares method to minimize the residual between the image positions and the theoretical positions, thereby obtaining the pose relationship between the detector and the X-ray source in a unified coordinate system.
9. The CL system design and field-of-view planning method with dual imaging modules according to claim 1, characterized in that, In step S6, the three-dimensional reconstruction uses the FDK reconstruction algorithm of the CL system to reconstruct the projection data of each field of view separately.
10. The CL system design and field-of-view planning method with dual imaging modules according to claim 1, characterized in that, The object to be tested is a flat plate, and the feature points to be tested are the holes to be tested. The size of each field of view is a pre-defined effective field of view size, which has deducted the edge effect area of the 3D reconstruction.