Multi-feature fusion large depth-diameter ratio micropore optical nondestructive measurement device based on depth-diameter ratio constraint

Abstract

The invention belongs to the technical field of optical detection and intelligent visual analysis, and discloses a depth-diameter ratio constraint-based multi-feature fusion large depth-diameter ratio micropore optical nondestructive measurement device, which comprises a workbench, a liftable objective table, an industrial electron microscope, an optical illumination device, a CMOS image sensor, a pull rod sliding table, a driving motor, a driver and an upper computer. Through height adjustment of the objective table and displacement scanning of the pull rod sliding table, multi-position imaging of the micropore in the axial direction is achieved. The device can complete micropore parameter measurement without physical contact, can effectively avoid the problem of unstable measurement caused by a single hole bottom judgment mode, improves the measurement precision and stability of a micropore with a large depth-diameter ratio under a complex imaging condition, is suitable for the fields of precision manufacturing, electronic processing and related engineering, and has wide application prospects. And the method has good practicability and engineering application value.

Description

Technical Field

[0001] This invention belongs to the field of optical inspection and intelligent visual analysis technology, and particularly relates to a multi-feature fusion optical non-destructive measurement device for large aspect ratio micro-apertures based on aspect ratio constraints. Background Technology

[0002] With the rapid development of aerospace, electronics manufacturing, medical devices, and precision machining, high aspect ratio micro-holes are widely used in structural cooling, fluid control, and functional integration. High-precision measurement of parameters such as diameter, depth, and aspect ratio of these micro-holes is crucial for ensuring product performance and processing quality. Existing micro-hole measurement methods mainly include contact measurement and non-contact optical measurement. Contact measurement can easily damage the micro-hole structure and is difficult to apply to scenarios with small apertures and high aspect ratios; while non-contact optical measurement has the advantage of being non-destructive, it still faces the following challenges in practical applications:

[0003] Micropores have small apertures and blurred edges, and complex background structures, making it difficult for traditional image processing methods to stably locate the effective measurement area.

[0004] The lighting conditions at the bottom of the hole are poor, and the focal plane is easily affected by noise and false focus. The reliability of a single depth determination method is insufficient.

[0005] The depth measurement error and the diameter measurement error are superimposed on each other during the depth-to-diameter ratio calculation, which leads to a decrease in the stability of the depth-to-diameter ratio result.

[0006] Measuring the parameters of micro-apertures with large aspect ratios is a challenging task. Due to their extremely small diameter and large aspect ratio, micro-apertures face numerous technical difficulties in non-contact optical measurement. First, the extremely small diameter and blurred edges of the micro-apertures make it difficult for traditional image processing methods to accurately identify their contours. Second, during depth measurement, the imaging effect is easily affected by the direction and intensity of the light source because the bottom of the aperture is in a low-light or even shadowed area. Third, even a slight shift in the focal plane of the microscope can significantly affect image clarity, leading to uncertainty in the depth determination results.

[0007] Therefore, it is necessary to provide a method and apparatus for optical measurement of large aspect ratio micro-apertures that comprehensively analyzes and corrects the depth measurement process under aspect ratio constraints.

[0008] Based on the above analysis, the problems and shortcomings of the existing technology are as follows:

[0009] (1) Micropores have small apertures and blurred edges, and complex background structures, making it difficult for traditional image processing methods to stably locate the effective measurement area;

[0010] (2) The lighting conditions in the bottom area of ​​the hole are poor, and the focal plane is easily affected by noise and false focus. The reliability of the single depth determination is insufficient.

[0011] (3) The depth measurement error and the diameter measurement error are superimposed on each other during the depth-to-diameter ratio calculation, which leads to a decrease in the stability of the depth-to-diameter ratio result. Summary of the Invention

[0012] To address the problems existing in the prior art, this invention provides a multi-feature fusion optical non-destructive measurement device for large aspect ratio micro-apertures based on aspect ratio constraints.

[0013] This invention is implemented as follows: A multi-feature fusion large aspect ratio micro-aperture optical non-destructive measurement device based on aspect ratio constraints includes:

[0014] Workbench;

[0015] The upper end of the workbench is equipped with a liftable platform;

[0016] An industrial electron microscope is installed at the top of the stage, and a variable focus knob is installed at the top of the industrial electron microscope.

[0017] The top of the variable focus knob is equipped with an optical illumination device;

[0018] The optical illumination device is equipped with a CMOS image sensor at its top.

[0019] The CMOS image sensor has a bottom-fixed pull rod slide on one side;

[0020] A drive motor is provided on one side of the pull rod slide;

[0021] A driver is provided on one side of the drive motor;

[0022] A host computer is provided on one side of the driver.

[0023] The host computer is configured to analyze and process micropore parameters under aspect ratio constraints. Furthermore, the liftable stage works in conjunction with a sliding stage, enabling multi-position imaging of the micropore in the axial direction through stage height adjustment and displacement scanning by the industrial electron microscope, thereby generating imaging data for aspect ratio constraint analysis.

[0024] Furthermore, the pull rod slide is used to drive the industrial electron microscope to perform step-by-step scanning along the micro-hole axis to obtain micro-hole image sequences corresponding to different axial positions, and to provide a displacement reference for the generation of depth candidate parameters.

[0025] Furthermore, the optical illumination device is an adjustable brightness illumination device, used to adjust the illumination intensity according to the micro-aperture depth-to-diameter ratio and imaging conditions.

[0026] Furthermore, the host computer is configured to extract multiple image feature parameters from the microhole image within the effective measurement area, including at least sharpness features, grayscale features, and contrast features, and to perform fusion analysis on the image feature parameters to generate depth candidate parameters.

[0027] Furthermore, the host computer is configured to generate multiple candidate depth parameters based on the relationship between the fused image feature parameters and the scanning position, and to filter effective depth parameters for depth-to-diameter ratio calculation under the constraint of the micro-aperture diameter parameter. The host computer includes a processor and a memory, the memory of which stores a computer program. When the computer program runs on the processor, it is used to realize optical non-destructive measurement of micro-aperture parameters based on the depth-to-diameter ratio constraint.

[0028] Another objective of this invention is to provide a multi-feature fusion method for non-destructive optical measurement of large aspect ratio micro-apertures based on aspect ratio constraints, comprising:

[0029] Step 1: Obtain the initial optical image of the micropores in the workpiece to be tested;

[0030] Step 2: Analyze the initial optical image based on the target detection model to automatically determine the effective measurement area of ​​the micropore, and use the effective measurement area as the target area for subsequent measurements;

[0031] Step 3: Within the target area, the optical imaging system is scanned at multiple positions along the axial direction of the micropore to obtain micropore image sequences corresponding to different scanning positions;

[0032] Step 4: Extract multiple image feature parameters from the micropore image sequence, including at least sharpness, grayscale and contrast features, and construct depth candidate parameters;

[0033] Step 5: Obtain the diameter parameters of the micropores;

[0034] Step 6: Based on the diameter parameter, select the effective depth parameter for depth-to-diameter ratio calculation under the depth-to-diameter ratio constraint, and calculate the micropore parameter;

[0035] The target detection model is used to identify the spatial distribution of microholes in optical images. It is only used to determine the effective measurement area of ​​the microholes and is not used to directly output the size parameters of the microholes.

[0036] The sharpness features include focus evaluation parameters calculated based on image gradient, Laplacian operator, or frequency domain energy distribution;

[0037] The grayscale feature is the mean grayscale value of image pixels or a grayscale distribution statistical parameter, and the contrast feature is the standard deviation of image pixel grayscale value or a local contrast evaluation parameter.

[0038] The various image feature parameters are normalized and weighted according to preset weights to generate multiple depth candidate parameters to support screening under aspect ratio constraints.

[0039] The depth candidate parameters include multiple depth values ​​corresponding to different axial scanning positions, which is used to avoid measurement instability caused by a single hole bottom determination method.

[0040] Another object of the present invention is to provide a computer device including a memory and a processor, the memory storing a computer program, which, when executed by the processor, causes the processor to perform the steps of the multi-feature fusion method for non-destructive optical measurement of large aspect ratio micro-apertures based on aspect ratio constraints.

[0041] Another object of the present invention is to provide a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the steps of the multi-feature fusion method for non-destructive optical measurement of large aspect ratio micro-apertures based on aspect ratio constraints.

[0042] Another objective of this invention is to provide an information data processing terminal for implementing the multi-feature fusion large aspect ratio micro-aperture optical non-destructive measurement device based on aspect ratio constraints.

[0043] Based on the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solution to be protected by this invention are as follows:

[0044] 1) The introduction of a depth-to-diameter ratio constraint mechanism improves the stability of the depth parameter acquisition process;

[0045] 2) By using multi-feature fusion and candidate parameter screening, the reliability of high aspect ratio micro-hole measurement is improved;

[0046] 3) To achieve automated, non-destructive measurement of micropore diameter, depth, and depth-to-diameter ratio parameters;

[0047] 4) The measurement process is highly automated and suitable for engineering sites and batch testing applications.

[0048] The inventiveness of the invention claims is also reflected in the following important aspects:

[0049] (1) The expected benefits and commercial value of the technical solution of this invention after transformation are as follows:

[0050] This invention addresses the long-standing problems of "inaccuracy, instability, and difficulty in automation" in non-contact optical measurement of micro-holes with large aspect ratios. It proposes a measurement device and method that incorporates the aspect ratio as a constraint into the depth parameter selection process, which has clear engineering application scenarios and industrialization value.

[0051] In fields such as aerospace cooling holes, precision mold micro-holes, electronic packaging through-holes, and medical device micro-holes, the workpieces typically have characteristics of small hole diameters, large quantities, and high requirements for quality consistency. Traditional contact measurement methods are inefficient and prone to damaging the workpieces, while existing optical measurement solutions lack stability under deep hole conditions. This invention can automatically acquire the diameter, depth, and aspect ratio parameters of micro-holes without physical contact, significantly reducing the degree of manual intervention.

[0052] From an industrial application perspective, this invention can be directly integrated into existing industrial electron microscopes or online inspection platforms, reducing the redundant investment in dedicated measurement equipment. It has advantages such as strong equipment compatibility, low deployment cost, and high inspection efficiency, and has good commercial promotion prospects and potential for large-scale application.

[0053] (2) The technical solution of the present invention also solves a technical problem that the industry has long wanted to solve but has never been able to solve successfully:

[0054] Due to their small aperture and large depth, high aspect ratio micro-apertures commonly suffer from problems such as insufficient illumination at the bottom of the aperture, blurred images, and non-unique focal plane determination during optical imaging. For a long time, technicians have mainly relied on maximum sharpness or a single feature extremum to determine the position of the bottom of the aperture. However, in practical applications, this method is easily affected by local noise and abnormal reflections, making it difficult to obtain stable and reliable measurement results.

[0055] This invention employs a holistic technical solution combining multi-position axial scanning, multi-feature fusion, and aspect ratio constraint screening. This transforms the previously difficult-to-accurate determination of the hole bottom position into a problem of rationally selecting a set of depth candidate parameters, effectively avoiding the risk of misjudgment caused by the failure of a single criterion. This technical approach fundamentally improves the stability of optical measurements of large aspect ratio micro-apertures, solving a key technical problem that has long been a focus of the industry but has been difficult to completely overcome.

[0056] (3) The technical solution of the present invention overcomes long-standing technical prejudices:

[0057] Existing technologies often suffer from a technical bias: they assume that microaperture depth must be determined by a unique and definitive focal plane position at the bottom of the aperture, treating depth measurement as an isolated image determination problem. Under this approach, the reliability of the measurement results is difficult to guarantee when imaging conditions are complex or the aperture bottom features are not obvious.

[0058] This invention overcomes the aforementioned technical biases by proposing a novel approach that does not force a single, definitive determination of the hole bottom location. Instead, it generates multiple candidate depth parameters and filters them under depth-to-diameter ratio constraints, allowing the determination of depth parameters to be cross-validated with the geometric characteristics of the micropore. This approach combines optical imaging analysis with structural physical rationality, significantly improving the stability and engineering applicability of measurement results under complex working conditions. Attached Figure Description

[0059] Figure 1 This is a structural diagram of a multi-feature fusion, high aspect ratio micro-aperture optical non-destructive measurement device based on aspect ratio constraints, provided in an embodiment of the present invention.

[0060] Figure 2 This is a top view of the multi-feature fusion large aspect ratio micro-aperture optical non-destructive measurement device based on aspect ratio constraints provided in an embodiment of the present invention.

[0061] Figure 3 It involves acquiring images of different focal planes through axial scanning and extracting multiple features to construct a set of depth candidate parameters.

[0062] Figure 4 This is a feature-displacement response curve provided in an embodiment of the present invention.

[0063] Figure 5 This is a flowchart of a multi-feature fusion method for non-destructive optical measurement of large aspect ratio micro-apertures based on aspect ratio constraints, provided in an embodiment of the present invention.

[0064] Figure 6 This is the overall flowchart provided in the embodiments of the present invention.

[0065] Figure 7 This is a fitting graph of the simulation experiment provided in the embodiment of the present invention.

[0066] Figure 1 The components are: 1. Worktable; 2. Stage; 3. Industrial electron microscope; 4. Variable focus knob; 5. Optical illumination device; 6. CMOS image sensor; 7. Pull rod slide; 8. Drive motor; 9. Driver; 10. Host computer. Detailed Implementation

[0067] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0068] like Figure 1 , Figure 2 As shown, an embodiment of the present invention provides a multi-feature fusion large aspect ratio micro-aperture optical non-destructive measurement device based on aspect ratio constraints, comprising:

[0069] A height-adjustable stage 2 is provided at the upper end of the worktable 1 for fixing the workpiece to be tested. An industrial electron microscope 3 is positioned above the stage 2, used to magnify and image the micropore structure in the workpiece. A variable focus knob 4 is provided at the upper end of the industrial electron microscope 3 for adjusting the focal length of the imaging system. An optical illumination device 5 is provided above the variable focus knob 4, providing illumination to the micropore area. A CMOS image sensor 6 is provided above the optical illumination device 5, used to acquire optical images of the micropores. A bottom-fixed pull rod slide 7 is provided on one side of the CMOS image sensor 6, used to drive the industrial electron microscope 3 to perform displacement scanning along a predetermined direction. A drive motor 8 is provided on one side of the pull rod slide 7, providing the motion power for the pull rod slide 7. A driver 9 is provided on one side of the drive motor 8, used to control the operating state of the drive motor 8. The driver 9 is electrically connected to a host computer 10, which receives CMOS images. Image data acquired by image sensor 6 is analyzed and processed to determine the micropore parameters under aspect ratio constraints.

[0070] like Figure 3 As shown, when measuring micropores, this invention acquires multiple optical images of the micropores at different axial positions using an axial scanning method. Specifically, under the control of the host computer 10, the pull rod slide 7 drives the industrial electron microscope 3 to move gradually along the micropore axis, allowing the CMOS image sensor 6 to acquire corresponding micropore images at different focal plane positions, thereby forming a multi-focal plane image sequence that corresponds one-to-one with the axial displacement.

[0071] Based on the multi-focal plane image sequence, the host computer 10 extracts sharpness features, grayscale features, and contrast features from the microhole images corresponding to each axial position within the effective measurement area determined by the target area adaptive positioning module. These features are used to characterize the variation of microhole imaging characteristics with axial position. Comprehensive analysis of these various image features provides a data foundation for subsequent construction of feature-displacement response curves, generation of depth candidate parameters, and selection of effective depth parameters under aspect ratio constraints.

[0072] like Figure 4 By adopting the above technical solution, the worktable provides a stable mechanical support foundation for the entire measuring device, and the precision displacement actuator is used to realize high-precision scanning motion in the axial direction of the micro-hole, thereby providing a reliable displacement reference for obtaining the micro-hole depth parameter under constrained conditions; the optical imaging unit and the image acquisition unit work together to realize continuous imaging of the micro-hole at different axial positions, providing the original data basis for subsequent multi-feature analysis and parameter screening.

[0073] The host computer processing unit is equipped with a target area adaptive positioning module. The target area adaptive positioning module is built based on a deep learning target detection algorithm. It is used to analyze the initial image of the micropores, automatically identify the spatial position of the micropores in the image, and determine the effective measurement area containing the micropore opening and its neighborhood.

[0074] By adopting the above technical solution, the target area adaptive positioning module can accurately locate the micropore position under complex background conditions, providing spatial constraints for subsequent correlation analysis of depth and diameter parameters, and avoiding interference from irrelevant areas on the depth-to-diameter ratio constraint analysis process.

[0075] The host computer processing unit is also equipped with a focal plane analysis and depth calculation module. Under the constraint of the effective measurement area determined by the target area adaptive positioning module, the focal plane analysis and depth calculation module controls the precision displacement actuator to perform multi-position scanning along the axial direction of the microhole and acquires the corresponding microhole image sequence at different scanning positions.

[0076] By adopting the above technical solution, focal plane scanning can be performed under the constraint of the target area, which can screen depth candidate parameters in the subsequent aspect ratio constraint analysis process and reduce depth misjudgment caused by local false focal points.

[0077] The focal plane analysis and depth calculation module is used to extract multiple image feature parameters from the micro-hole image sequence, including at least sharpness features, grayscale distribution features, and contrast change features, and to construct response curves of the image feature parameters as the scanning position changes.

[0078] By adopting the above technical solution, the joint introduction of multiple image features can provide multi-dimensional evaluation criteria for depth candidate parameters, making the subsequent screening of depth parameters under aspect ratio constraints more reliable.

[0079] The focal plane analysis and depth calculation module normalizes the various image feature parameters and performs weighted fusion according to preset weights to form a comprehensive feature response function. By analyzing the change relationship of the comprehensive feature response function in the scanning direction, the position of the micro-hole opening and multiple depth candidate positions are determined.

[0080] By adopting the above technical solution, the comprehensive feature response function formed by multi-feature fusion provides a basis for the generation of depth candidate parameters, so that the depth parameters no longer depend on a single extreme value judgment, which is conducive to further screening under the constraint of depth-to-diameter ratio.

[0081] Based on the orifice position and the multiple depth candidate positions, and combined with the displacement parameters of the precision displacement actuator, a set of depth candidate parameters is generated; at the same time, combined with the spatial scale information output by the target area adaptive positioning module, the diameter parameters of the micro-hole are obtained, and effective depth parameters for depth-to-diameter ratio calculation are selected under the constraint of depth-to-diameter ratio.

[0082] like Figure 5 As shown, the present invention provides a multi-feature fusion method for non-destructive optical measurement of large aspect ratio micro-apertures based on aspect ratio constraints, comprising:

[0083] S101, Obtain the initial optical image of the micropores in the workpiece to be tested;

[0084] S102, the initial optical image is analyzed based on the target detection model to automatically determine the effective measurement area of ​​the micropore, and the effective measurement area is used as the target area for subsequent measurements;

[0085] S103, within the target area, the optical imaging system is scanned at multiple positions along the axial direction of the micropore to obtain micropore image sequences corresponding to different scanning positions;

[0086] S104, extract at least a variety of image feature parameters, including sharpness, grayscale and contrast features, from the micropore image sequence, and construct depth candidate parameters;

[0087] S105, obtain the diameter parameters of the micropores;

[0088] S106, Based on the diameter parameter, under the aspect ratio constraint, select the effective depth parameter for aspect ratio calculation, and calculate the micropore parameter;

[0089] The target detection model is used to identify the spatial distribution of microholes in optical images. It is only used to determine the effective measurement area of ​​the microholes and is not used to directly output the size parameters of the microholes.

[0090] The sharpness features include focus evaluation parameters calculated based on image gradient, Laplacian operator, or frequency domain energy distribution;

[0091] The grayscale feature is the mean grayscale value of image pixels or a grayscale distribution statistical parameter, and the contrast feature is the standard deviation of image pixel grayscale value or a local contrast evaluation parameter.

[0092] The various image feature parameters are normalized and weighted according to preset weights to generate multiple depth candidate parameters to support screening under aspect ratio constraints.

[0093] The depth candidate parameters include multiple depth values ​​corresponding to different axial scanning positions, which is used to avoid measurement instability caused by a single hole bottom determination method.

[0094] Another object of the present invention is to provide a computer device including a memory and a processor, the memory storing a computer program, which, when executed by the processor, causes the processor to perform the steps of the multi-feature fusion method for non-destructive optical measurement of large aspect ratio micro-apertures based on aspect ratio constraints.

[0095] Another object of the present invention is to provide a computer-readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the steps of the multi-feature fusion method for non-destructive optical measurement of large aspect ratio micro-apertures based on aspect ratio constraints.

[0096] Another objective of this invention is to provide an information data processing terminal for implementing the multi-feature fusion large aspect ratio micro-aperture optical non-destructive measurement device based on aspect ratio constraints.

[0097] like Figure 6 As shown, the method of the present invention includes:

[0098] 1. Perform initial imaging of the micropores and acquire micropore images;

[0099] 2. Determine the effective measurement area of ​​the micropore based on the target detection algorithm;

[0100] 3. Perform multi-position scanning along the axial direction of the micropore under the constraint of the effective measurement area;

[0101] 4. Extract various image features from the scanned micropore image sequence and generate candidate depth parameters;

[0102] 5. Based on the micropore diameter parameter, select effective depth parameters and calculate micropore parameters under the depth-to-diameter ratio constraint.

[0103] Specific implementation of the present invention:

[0104] This invention provides a large aspect ratio micro-aperture optical non-destructive measurement device based on aspect ratio constraint, comprising a worktable, a precision displacement execution module, a stage, an optical imaging module, an image acquisition module, and a host computer processing module. The modules cooperate with each other in spatial structure and functional logic to form a large aspect ratio micro-aperture optical non-destructive measurement system with aspect ratio parameter as the constraint target.

[0105] The worktable, serving as the fundamental support structure of the entire measuring device, is used for the unified installation and fixation of the precision displacement execution module, optical imaging module, and host computer processing module. The worktable employs a high-rigidity structural design, effectively suppressing external vibrations and minor mechanical disturbances generated during system operation, thereby avoiding optical imaging blurring or displacement measurement errors caused by structural instability. In the measurement of micro-apertures with large aspect ratios, the focal plane position change is typically on the order of micrometers or even smaller. Therefore, providing a reliable mechanical foundation for the entire system through a highly stable worktable structure is a prerequisite for ensuring the stability of subsequent depth candidate parameter acquisition.

[0106] A precision displacement execution module is mounted on the worktable to drive the stage to perform precise linear displacement along the axial direction of the micro-aperture. The precision displacement execution module includes a motor, a driver, and a linear motion mechanism, preferably a lead screw and slide structure, which converts the rotational motion of the motor into stable and controllable linear displacement. During operation, the host computer processing module sends control commands to the driver, which then controls the motor to rotate, causing the stage to move gradually along the axial direction of the micro-aperture, thus providing the physical displacement basis for imaging at different axial positions of the micro-aperture.

[0107] The stage, mounted on the precision displacement actuator, is used to support and fix the workpiece to be measured. The workpiece surface has one or more micro-holes with a large aspect ratio. The stage fixes the workpiece using clamping, pressing, or positioning structures to ensure that the workpiece does not shift, tilt, or rotate during measurement. In aspect ratio measurement, the consistency of the workpiece's spatial position directly affects the correlation analysis results between depth candidate parameters and diameter parameters; therefore, the stability of the stage structure is crucial for subsequent parameter selection.

[0108] An optical imaging module is positioned above the stage and is used to magnify and image the micropore opening and its internal region. The optical imaging module preferably employs an electron optical microscope, and its magnification can be adjusted according to different micropore sizes to accommodate the imaging requirements of micropores with varying diameters and aspect ratios. By adjusting the focal length and magnification of the optical imaging module, the micropore opening contour and internal structure can be clearly presented at different axial positions, providing an imaging basis for generating depth candidate parameters.

[0109] The image acquisition module is connected to the optical imaging module and is used to convert the micro-hole images acquired by the optical imaging module into digital image signals, which are then transmitted to the host computer processing module in real time. The image acquisition module preferably uses a high-resolution CMOS image sensor to ensure complete acquisition of micro-hole wall edges, orifice contours, and detailed information within the micro-hole. During the measurement process, the image acquisition module, driven by the precision displacement actuator, can continuously acquire micro-hole images at different axial positions, forming an image sequence corresponding to each axial displacement.

[0110] To improve the imaging quality of the bottom region of a high aspect ratio microaperture, an illumination unit is arranged around the optical imaging module. This illumination unit is preferably a ring-shaped structure, with its inner diameter matching the diameter of the objective lens of the optical imaging module, allowing the illumination light to be incident along the axial direction of the microaperture. This illumination structure design effectively reduces the impact of shadows, reflections, and uneven illumination on the microaperture imaging quality, especially improving the brightness distribution in deep aperture regions, thus providing favorable conditions for subsequent multi-feature analysis and depth candidate parameter determination.

[0111] The host computer processing module, serving as the core of the entire system's data processing and control, is electrically connected to the image acquisition module to receive micro-hole image data and communicatively connected to the precision displacement execution module to control its motion. The host computer processing module integrates a target area adaptive positioning module, a focal plane analysis module, a multi-feature extraction and fusion module, and a parameter calculation and result output module. These modules work collaboratively to achieve automated measurement of micro-hole parameters under depth-to-diameter ratio constraints.

[0112] In the specific measurement process, the optical imaging module first acquires an initial optical image of the micropore at the initial position, and then transmits the initial image to the host computer processing module via the image acquisition module. The host computer processing module calls the target area adaptive positioning module to analyze and process the initial image to determine the spatial distribution of the micropore in the image.

[0113] The target region adaptive localization module is built on a deep learning target detection algorithm. Through semantic-level analysis of the microhole images, it automatically identifies the spatial location of the microholes in the image and determines the effective measurement region containing the microhole opening and its neighborhood. By limiting the effective measurement region, the subsequent depth candidate parameter generation process will only be performed within this region, thus avoiding interference from background structures on the aspect ratio constraint analysis process.

[0114] After determining the effective measurement area, the host computer processing module controls the precision displacement execution module to perform multi-position scanning along the axial direction of the micropore under the constraint of the area, and acquires the corresponding micropore image at each scanning position, forming a sequence of micropore images arranged in axial displacement order. Through this scanning process, complete information reflecting the changes in micropore imaging characteristics with axial position can be obtained.

[0115] The focal plane analysis module processes the micro-aperture image sequence frame by frame, extracting various image feature parameters from each frame to characterize imaging changes. These image feature parameters include at least sharpness features, grayscale distribution features, and contrast variation features, each reflecting the changes in imaging quality of the micro-aperture opening and the area within the aperture from different perspectives.

[0116] In high aspect ratio micro-hole measurement scenarios, the imaging conditions at the bottom of the hole are complex, and relying on only a single image feature can easily lead to misjudgment. Therefore, this embodiment introduces multiple image features to describe the imaging state of the micro-hole image at different axial positions from multiple dimensions, providing a more comprehensive basis for the subsequent generation and selection of depth candidate parameters.

[0117] After multi-feature extraction, the multi-feature fusion module normalizes the extracted image features and performs weighted fusion according to preset weights to construct a comprehensive feature response function. This comprehensive feature response function describes the overall trend of microaperture imaging characteristics changing with axial displacement.

[0118] By analyzing the variation relationship of the comprehensive feature response function in the scanning direction, the focal plane analysis module can identify multiple regions with significant feature changes corresponding to different axial positions and record them as depth candidate positions, rather than directly determining a unique hole bottom position.

[0119] Based on the multiple candidate depth positions and the displacement parameters of the precision displacement execution module, the host computer processing module generates a corresponding set of candidate depth parameters. This set of candidate depth parameters describes the possible depth ranges of the microhole at different reasonable axial positions.

[0120] After obtaining the set of depth candidate parameters, the host computer processing module further combines the spatial scale information output by the target area adaptive positioning module to perform geometric analysis on the micropore opening area and calculate the diameter parameters of the micropore.

[0121] Subsequently, the host computer processing module performs depth-to-diameter ratio constraint analysis on the depth candidate parameter set based on the diameter parameter, filters out the depth candidate parameters that meet the preset reasonable depth-to-diameter ratio range, and determines them as effective depth parameters for depth-to-diameter ratio calculation.

[0122] After determining the effective depth parameters, the host computer processing module calculates the depth-to-diameter ratio of the micropore based on the effective depth parameters and diameter parameters, and displays or stores the measurement results through the result output module.

[0123] Through the above specific implementation methods, the present invention realizes a complete measurement process from adaptive positioning of the target area, multi-position imaging, multi-feature fusion analysis to the selection of aspect ratio constraint parameters, so that depth parameters are no longer obtained in isolation, but are determined under aspect ratio constraints, thereby significantly improving the stability and reliability of the measurement of micro-hole parameters with large aspect ratios.

[0124] Example 1: Basic Optical Measurement Device Structure

[0125] This embodiment provides a device for optical non-destructive measurement of micro-holes with large aspect ratios, including a worktable, a liftable stage, an optical imaging unit, an axial scanning mechanism, an image acquisition unit, a motion control unit, and a data processing unit. The workpiece to be measured is placed on the liftable stage, the optical imaging unit is located directly above the micro-hole and aligned with the axis of the micro-hole, and the axial scanning mechanism drives the optical imaging unit to move gradually along the axial direction of the micro-hole, enabling the optical imaging unit to acquire image information of the inside of the micro-hole at different depth positions.

[0126] The data processing unit communicates with the image acquisition unit and motion control unit to synchronously acquire scanning displacement information and image information. It uses multi-position micro-hole image sequences as the data basis for subsequent feature extraction and depth analysis, thus providing the necessary input conditions for subsequent aspect ratio constraint screening. By acquiring image sequences corresponding to complete axial positions, the instability problem caused by relying solely on a single imaging position for depth parameters is avoided.

[0127] Example 2: Axial scanning and multi-position imaging process

[0128] In this embodiment, the axial scanning mechanism employs a linear drive method, causing the optical imaging unit to move gradually downwards or upwards along the micro-aperture axis at preset step intervals. At each scanning position, a micro-aperture image is acquired, forming a sequence of micro-aperture images arranged in the scanning order. This image sequence is used to characterize the relationship between the micro-aperture imaging characteristics and axial displacement.

[0129] By synchronously controlling the scanning displacement and image acquisition, each micro-hole image is associated with its corresponding axial position, forming an image sequence with positional information annotations. This provides a foundation for establishing the relationship between image features and axial position changes.

[0130] Example 3: Multi-feature extraction and fusion process

[0131] In this embodiment, sharpness features, grayscale features, and contrast features are extracted from the obtained micro-hole image sequence. The sharpness feature is used to reflect whether the current imaging position is in an effective focusing state, the grayscale feature is used to reflect the change in reflectance brightness inside the hole, and the contrast feature is used to reflect the degree of distinguishability between the hole wall and the background.

[0132] After normalizing the above-mentioned multiple image features, they are weighted and fused according to preset weights to obtain the relationship between the fused feature curve and the axial position. Based on the local extrema, stable intervals or trends of the fused features, multiple depth candidate parameters corresponding to different axial positions are generated.

[0133] Example 4: Deep Candidate Parameter Generation and Screening Mechanism

[0134] In this embodiment, by analyzing the curve of the fusion feature changing with the scanning position, multiple positions that meet the requirements of stable focus, reasonable grayscale distribution and continuous contrast change are selected as depth candidate parameters, instead of selecting only a single position with the highest sharpness as the hole bottom position, thereby avoiding misjudgment caused by local noise or abnormal reflection.

[0135] Subsequently, an aspect ratio constraint is introduced to proportionally match candidate depth parameters with micro-aperture diameter parameters, limiting them to a preset reasonable aspect ratio range. Only depth parameters that satisfy the aspect ratio constraint range are retained as valid depth parameters for the final micro-aperture parameter output, thereby suppressing the interference of abnormal imaging positions on the measurement results.

[0136] Example 5: Automatic Target Area Positioning Process

[0137] In this embodiment, the initial optical image is first analyzed, and a target detection model is used to identify the spatial distribution of micropores in the image and determine the effective measurement area of ​​the micropores. This process is only used to locate the micropore region to avoid background structures interfering with subsequent imaging and feature extraction processes.

[0138] The effective measurement area output by the target detection model serves as a spatial constraint for subsequent axial scanning and image analysis, thereby ensuring that subsequent processing is performed only on the micropore body region, improving the stability and reliability of feature extraction and depth analysis.

[0139] Example 6: Engineering Applications of Aspect Ratio Constraints

[0140] In this embodiment, the depth-to-diameter ratio constraint is used to limit the ratio between the effective depth parameter and the micro-hole diameter parameter. When the ratio of a candidate depth parameter to the micro-hole diameter parameter deviates from the allowable range of the process, the depth parameter is removed from the effective set, thereby avoiding misidentification of hole wall reflection or stray reflection as the hole bottom position.

[0141] By introducing a depth-to-diameter ratio constraint, the final output micro-aperture parameters not only conform to the variation law of optical imaging characteristics, but also meet the physical rationality in terms of process and structure, thereby improving the engineering usability of the measurement results.

[0142] Example 7: System Implementation

[0143] In this embodiment, the optical imaging subsystem, axial scanning subsystem, image acquisition subsystem, motion control subsystem, and data processing subsystem are integrated into a unified control platform, and the data processing subsystem uniformly schedules the scanning process, image acquisition process, and feature analysis process.

[0144] Each subsystem interacts with other systems through a communication interface, enabling real-time sharing of image data, displacement data, and analysis results within the system, thus achieving a complete automated measurement process from imaging and analysis to output.

[0145] Example 8: Industrial Online Inspection Application Scenarios

[0146] In this embodiment, the device is applied to a micro-hole processing production line to perform online or offline inspection on the processed workpieces. After the workpiece enters the inspection station, it is automatically positioned, and the device completes micro-hole region identification, axial scanning, multi-feature fusion analysis, and depth-to-diameter ratio constraint screening, and outputs micro-hole parameters for quality judgment.

[0147] The test results can be used to adjust the processing equipment or screen unqualified workpieces, thereby achieving closed-loop control of micro-hole processing quality and improving production stability and product consistency.

[0148] Based on the above embodiments, the results of testing the pore diameter, pore depth, and depth-to-diameter ratio of the standard sample using the technical solution of the present invention are shown below:

[0149] Table 1 Measurement data for Sample 1

[0150]

[0151] Table 2 Measurement data for Sample 2

[0152]

[0153] Table 3 Measurement data for sample 3

[0154]

[0155] This invention used 13 sets of data for linear fitting, and the above three sets of example data are given. The fitting graph is shown below. Figure 7 As shown. Fitting relationship:

[0156]

[0157] This invention selects 13 groups of samples with known standard depth-to-diameter ratios, measures the micropore depth-to-diameter ratio of the samples, and compares the measurement results with the corresponding standard depth-to-diameter ratios. Using the standard depth-to-diameter ratio as the independent variable and the depth-to-diameter ratio measured by this invention as the dependent variable, a linear fitting analysis is performed on the data of the 13 groups of samples.

[0158] Analysis of the fitting results shows a good linear correspondence between the measured depth-to-diameter ratio and the standard depth-to-diameter ratio. The slope of the fitted line is close to 1, the intercept is close to 0, and the overall distribution does not show any obvious systematic shift. These results indicate that the present invention can accurately reflect the true trend of micropore depth-to-diameter ratio changes within different depth-to-diameter ratio ranges, and the measurement results show high consistency with the standard values.

[0159] Therefore, by combining multi-position axial scanning, multi-feature fusion analysis, and depth-to-diameter ratio constraint screening, this invention can effectively suppress measurement deviations caused by local imaging anomalies or false focal points, and improve the stability and reliability of micro-hole depth-to-diameter ratio measurement results.

[0160] It should be noted that embodiments of the present invention can be implemented in hardware, software, or a combination of both. The hardware portion can be implemented using dedicated logic; the software portion can be stored in memory and executed by a suitable instruction execution system, such as a microprocessor or dedicated-design hardware. Those skilled in the art will understand that the above-described devices and methods can be implemented using computer-executable instructions and / or included in processor control code, for example, such code provided on a carrier medium such as a disk, CD, or DVD-ROM, a programmable memory such as read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. The devices and modules of the present invention can be implemented by hardware circuitry such as very large-scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, or programmable hardware devices such as field-programmable gate arrays, programmable logic devices, etc., or by software executed by various types of processors, or by a combination of the above-described hardware circuitry and software, such as firmware.

[0161] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A multi-feature fusion optical non-destructive measurement device for large aspect ratio micro-apertures based on aspect ratio constraints, characterized in that, include: Workbench; A liftable loading platform is set on the workbench; An optical imaging unit is installed on the liftable platform; An axial scanning mechanism that moves relative to the optical imaging unit; An image acquisition unit connected to the optical imaging unit; The motion control unit is connected to the axial scanning mechanism; And a data processing unit that is communicatively connected to the image acquisition unit and the motion control unit; The data processing unit is configured as follows: During the axial scanning of micropores, a sequence of micropore images at multiple locations is acquired. Sharpness features, grayscale features, and contrast features are extracted from the image sequences, and these features are fused to generate multiple depth candidate parameters. Based on the micropore diameter parameter, the candidate depth parameters are screened under the depth-to-diameter ratio constraint to determine the effective depth parameter for depth-to-diameter ratio calculation, and the micropore measurement results are output. The depth-to-diameter ratio constraint is used to limit the ratio between the effective depth parameter and the micro-hole diameter parameter in order to suppress the interference of abnormal focusing positions on the measurement results.

2. The apparatus as claimed in claim 1, characterized in that, The axial scanning mechanism includes a linear drive structure that drives the optical imaging unit to move step by step along the axis of the micro-aperture, and is used to provide a corresponding axial displacement reference for the depth candidate parameters.

3. The apparatus as described in claim 1, characterized in that, The optical imaging unit includes an industrial electron microscope and an optical illumination assembly. The brightness of the optical illumination assembly is adjustable to adjust the illumination intensity according to the aperture diameter ratio and imaging status.

4. The apparatus as claimed in claim 1, characterized in that, The data processing unit is configured to normalize the sharpness features, grayscale features, and contrast features, and then perform weighted fusion according to preset weights to generate the depth candidate parameters.

5. A multi-feature fusion method for non-destructive optical measurement of large aspect ratio micro-apertures based on aspect ratio constraints, characterized in that, Includes the following steps: Obtain an initial optical image containing the micropores; The effective measurement area of ​​the micropore in the initial optical image is determined based on the target detection model; The optical imaging system is scanned at multiple positions along the axial direction of the micropore within the effective measurement area to acquire a sequence of micropore images. Sharpness features, grayscale features, and contrast features are extracted from the micropore image sequence, and the features are fused to generate multiple depth candidate parameters; Obtain the diameter parameters of the micropores; Under the constraint of aspect ratio, the candidate depth parameters are screened to determine the effective depth parameters, and the micropore measurement results are output based on the effective depth parameters and the diameter parameters.

6. The method as described in claim 5, characterized in that, The target detection model is only used to determine the spatial distribution location and effective measurement area of ​​the micropores, and is not used to output micropore size parameters.

7. The method as described in claim 5, characterized in that, The sharpness features are calculated based on image gradient changes, Laplacian response, or frequency domain energy distribution.

8. The method as described in claim 5, characterized in that, The depth candidate parameters include multiple depth values ​​corresponding to different axial scanning positions, which are used to avoid measurement instability caused by a single hole bottom position determination method.

9. A multi-feature fusion optical non-destructive measurement system for large aspect ratio micro-apertures based on aspect ratio constraints, characterized in that, include: The optical imaging subsystem is used to magnify and image the micro-hole opening and the area inside the hole in the workpiece under test, and to form corresponding optical images of the micro-hole at different axial positions. The axial scanning subsystem is used to drive the optical imaging subsystem or the workpiece under test to perform multi-position relative displacement along the axial direction of the microhole under the control of the data processing subsystem, so as to obtain a microhole image sequence that corresponds one-to-one with the axial displacement. An image acquisition subsystem, connected to an optical imaging subsystem, is used to convert the micro-aperture optical image into digital image data and transmit it to a data processing subsystem. The motion control subsystem, connected to the axial scanning subsystem, is used to control the scanning direction, scanning step size and scanning sequence of the axial scanning subsystem according to the control instructions of the data processing subsystem, thereby realizing controllable scanning in the axial direction of the micropore; The data processing subsystem, connected to the image acquisition subsystem and the motion control subsystem, is used to process the acquired micropore image sequence.

10. The system as described in claim 9, characterized in that, The data processing subsystem includes a processor and a memory. The memory stores a computer program, which, when run on the processor, is used to execute the multi-feature fusion method for non-destructive optical measurement of large aspect ratio micro-apertures based on aspect ratio constraints.

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