Deep micropore three-dimensional measurement optical path system, method, computer device and storage medium

Abstract

The application relates to a deep micropore three-dimensional measurement optical path system, method, computer device and storage medium. The system generates detection light and reference light by using a sweep frequency interference optical path, and the detection light is accurately coupled to a single core of a multi-core optical fiber by using a collimator, a beam splitter, a galvanometer and a microscopic objective lens in a near-end space optical path scanning structure. The light is focused to a measured target point through a far-end endoscope structure, scattered light returns along the original light path, interference signals are formed by combining the scattered light with the reference light, and therefore high-precision three-dimensional measurement of the inner wall of a deep micropore is realized. The design cancels a mechanical rotating mechanism, the size of the probe is only equivalent to that of the multi-core optical fiber, and the problems of optical fiber stress and signal distortion are avoided; meanwhile, the bidirectional common optical path structure improves the anti-interference performance and measurement stability of the system, and realizes small-diameter, high-precision and non-contact deep micropore three-dimensional imaging.

Description

Technical Field

[0001] This application relates to the field of optical measurement and endoscopic detection technology, and in particular to a deep micro-hole three-dimensional measurement optical path system, method, computer equipment and storage medium. Background Technology

[0002] With the development of modern industry towards miniaturization and precision, the application of micro-hole and deep micro-hole structures in aerospace, defense, and precision equipment is becoming increasingly widespread. Taking the film pore of an aero-engine blade as an example, its typical aperture is about 0.2–2.0 mm, and its depth is about 1–20 mm, often with a large aspect ratio. Existing endoscopic measurement systems still face key bottlenecks in high-precision three-dimensional measurement of deep micro-holes. According to the different positions of the scanning mechanism, OCT endoscopes are mostly divided into two categories: proximal scanning and distal scanning. The proximal scanning probe uses a long torque coil and a rotary joint to transmit the rotational motion of the proximal end to the distal optical head to achieve circumferential or helical scanning. This structure is relatively economical in engineering, but the bending of the optical fiber and stress changes during rotation will cause refractive index fluctuations, resulting in non-uniform rotational distortion of the interference signal, which limits the imaging stability and phase accuracy of the system. At the same time, the scanning speed is also constrained by mechanical factors. The distal scanning probe integrates micro-motors, MEMS scanning mirrors, and other devices at the front end of the probe to achieve beam deflection and high-speed scanning, which can avoid signal distortion caused by optical fiber rotation to a certain extent and obtain higher scanning speed. However, the introduction of micromotors and complex micro-optical components significantly increases the structural complexity and outer diameter of the probe. Typical distal scanning probes often have a diameter of 1 to 3 mm or even larger, making it difficult to further shrink to the hundreds of micrometers level, thus making them unsuitable for internal measurements of deep micro-holes with smaller diameters and larger aspect ratios. Summary of the Invention

[0003] Based on this, a deep micro-hole three-dimensional measurement optical path system, method, computer equipment, and storage medium are provided to overcome the problems of fiber optic twisting and signal distortion caused by the proximal rotation mechanism of the endoscope and the technical problems of difficulty in miniaturizing the probe size caused by the remote scanning mechanism in the prior art.

[0004] On the one hand, a deep micro-hole three-dimensional measurement optical path system is provided, the deep micro-hole three-dimensional measurement optical path system including a swept frequency interferometric measurement optical path and an endoscope optical path; The swept-frequency interferometric measurement optical path is used to generate probe light and reference light. The endoscope optical path includes a near-end spatial optical path scanning structure and a far-end endoscope structure. The near-end spatial optical path scanning structure includes a collimator, a beam splitter, a galvanometer, a microscope objective, and a multi-core fiber. The collimator receives the probe light emitted from the swept-frequency interferometric measurement optical path and collimates it into parallel light. After passing through the beam splitter and having its parallel light output angle adjusted by the galvanometer, the light is coupled to a single core of the multi-core fiber by the microscope objective. The light emitted from the far end of the multi-core fiber is focused by the far-end endoscope structure onto a point on the target on the wall of the test aperture. The scattered light from the target is retrieved from the far end of the multi-core fiber and returns to the swept-frequency interferometric measurement optical path via the original optical path. The swept-frequency interferometric measurement optical path combines the scattered light with the reference light to form interference information.

[0005] Furthermore, the end face of the multi-core optical fiber includes multiple independent cores, which are arrayed laterally on the end face. The galvanometer is correspondingly positioned to the multi-core optical fiber, and optical scanning and gating of the multiple cores of the multi-core optical fiber are achieved through the galvanometer. By controlling the deflection angle of the galvanometer, the angle of the beam incident on the microscope objective is changed, so that the focused spot is sequentially coupled to different cores. For each core excited, a depth-oriented distance curve is obtained at the corresponding position on the target under test. By sequentially switching multiple cores, multi-point depth information in a circle or a region is obtained. Combined with the axial relative movement of the distal endoscope structure and the target under test, point cloud data of different axial sections are obtained, and the three-dimensional morphology of the inner wall of the deep micropore is obtained through a three-dimensional reconstruction algorithm.

[0006] Furthermore, the near-end spatial optical path scanning structure also includes a camera, which is configured correspondingly to the beam splitter. The camera is used to visually monitor the end face or coupled spot of the multi-core fiber. By scanning the deflection angle of the galvanometer and identifying the image features when different fiber cores are lit, a mapping table between the galvanometer deflection angle or driving voltage and the fiber core number is established to realize the calibration and selection of multiple fiber cores.

[0007] Furthermore, the distal endoscope structure includes a converging lens, which is located at the distal end of the multi-core optical fiber. The converging lens is used to converge the light emitted from the distal end of the multi-core optical fiber to a single point, thereby converting forward-emitting light into radial focusing.

[0008] Furthermore, the sweep frequency interferometric measurement optical path includes a light source, a ranging optical path unit, and a signal detection and calculation unit. The ranging optical path unit includes a first beam splitter, an auxiliary path, and a first photodetector. The signal detection and calculation unit includes a second beam splitter, a measurement path, a reference path, a circulator, and a second photodetector. The laser output from the light source is split by the first beam splitter to generate a first laser and a second laser. The first laser is sent to the auxiliary path for interference and photoelectric conversion, and the resulting signal is sent to the first photodetector for light source nonlinear correction. The second laser is sent to the second beam splitter for splitting to generate a third laser and a fourth laser. The third laser is used as a probe light and is input to the circulator through the measurement path. After entering the circulator, the probe light is collimated into parallel light by the collimator. The fourth laser is used as a reference light and is input to the second photodetector through the reference path. The scattered light returning from the original optical path returns to the circulator and is combined with the reference light, and the interference signal is retrieved on the second photodetector.

[0009] Furthermore, the ranging optical path unit also includes a third beam splitter and a fourth beam splitter. The auxiliary path is located between the third beam splitter and the fourth beam splitter. The first laser beam is fed into the third beam splitter and split into a fifth laser beam and a sixth laser beam. The fifth laser beam enters the fourth beam splitter through the auxiliary path, and the sixth laser beam enters the fourth beam splitter. The fourth beam splitter is connected to the first photodetector. The signal detection and calculation unit also includes a fifth beam splitter. The circulator is connected to the second photodetector through the fifth beam splitter, and the second beam splitter is connected to the fifth beam splitter through the reference path.

[0010] On the other hand, a method for three-dimensional measurement of deep micropores is provided for use in the aforementioned optical path system for three-dimensional measurement of deep micropores, comprising: The sweeping laser light source output from the sweeping interferometric measurement optical path is split into probe light and reference light by the first beam splitter; The probe light is collimated into parallel light by a collimator. The parallel light is then incident on the microscope objective after passing through a beam splitter and a galvanometer. The angle of the incident beam is changed by adjusting the deflection angle of the galvanometer, so that the focused spot is sequentially coupled to different cores of the multi-core optical fiber. The light emitted from the far end of the multi-core optical fiber is focused onto a point on the target on the wall of the test hole by the far end endoscope structure, and the scattered light from the target returns through the original optical path and is coupled back to the multi-core optical fiber. The scattered light returned by the circulator and beam splitter is combined with the reference light on the second photodetector to form an interference signal. The interference signal is then subjected to spectral linearization correction and depth inversion by the signal detection and calculation unit to obtain the depth-distance curve corresponding to the fiber core position. By controlling the deflection of the galvanometer, optical scanning and gating of multiple cores in a multi-core optical fiber can be achieved, thereby sequentially acquiring multi-point depth information within a circle or a region. By combining the axial relative movement between the remote endoscope structure and the target under test, point cloud data of different axial sections are obtained; the point cloud data are spatially registered and three-dimensionally reconstructed to obtain the three-dimensional morphology of the inner wall of the deep micropore.

[0011] Furthermore, the deep micropore three-dimensional measurement method also includes: Before measuring the target, the end face or coupled spot of the multi-core fiber is visually monitored by a camera. By scanning the deflection angle of the galvanometer and identifying the image features when different fiber cores are lit, a mapping table between the galvanometer deflection angle or driving voltage and the fiber core number is established to calibrate and select multiple fiber cores.

[0012] In another aspect, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of a deep micro-hole three-dimensional measurement optical path system.

[0013] In another aspect, a computer-readable storage medium is provided, on which a computer program is stored, which, when executed by a processor, implements the steps of a deep micro-hole three-dimensional measurement optical path system.

[0014] The aforementioned optical path system, method, computer equipment, and storage medium for deep micro-aperture 3D measurement solves the problems of interference signal distortion caused by fiber torsion in traditional near-end rotating endoscopes and the difficulty in miniaturizing probe size due to motor integration in far-end scanning endoscopes by combining a swept-frequency interferometric measurement optical path with an endoscope optical path. This system uses a swept-frequency interferometric optical path to generate probe and reference beams, and utilizes a collimator, beam splitter, galvanometer, and microscope objective in the near-end spatial optical path scanning structure to precisely couple the probe beam to a single core of a multi-core fiber. The light is focused onto the target point by the far-end endoscope structure, and the scattered light returns along the original optical path, combining with the reference beam to form an interference signal, thereby achieving high-precision 3D measurement of the inner wall of the deep micro-aperture. This design eliminates the mechanical rotation mechanism, and the probe size is comparable to that of a multi-core fiber, avoiding fiber stress and signal distortion problems. Simultaneously, the bidirectional common optical path structure improves the system's anti-interference and measurement stability, realizing small-diameter, high-precision, non-contact 3D imaging of deep micro-apertures. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a structural block diagram of a deep micro-hole three-dimensional measurement optical path system in one embodiment of this application; Figure 2 This is an internal structural diagram of a computer device in one embodiment of this application. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0018] As described in the background section, with the development of modern industry towards miniaturization and precision, the application of micro-hole and deep micro-hole structures in aerospace, defense, and precision equipment is becoming increasingly widespread. Especially in critical components such as hydraulic system injectors, servo valves, micromotors, nozzle throats, and film cooling holes in aero-engine blades, numerous micro-hole structures with diameters less than 5 mm and large depth-to-diameter ratios exist. The geometric and morphological parameters of these holes, such as diameter, roundness, cylindricity, axial orientation, and wall roughness and integrity, directly affect flow control, cooling efficiency, and the overall safety and reliability of the system. Taking the film cooling hole of an aero-engine blade as an example, its typical diameter is approximately 0.2–2.0 mm, and its depth is approximately 1–20 mm, often with a large depth-to-diameter ratio, placing micron-level or even higher precision requirements on manufacturing and inspection.

[0019] However, measuring micro-deep holes presents significant challenges compared to measuring typical external surfaces or large-aperture structures. On one hand, the space within the hole is extremely limited, making it difficult for conventional probes or optical components to penetrate and maintain a reasonable working distance. On the other hand, the high aspect ratio results in long propagation paths for light or probes within the hole, leading to severe obstruction and easily introducing signal attenuation and interference. Therefore, how to perform high-precision three-dimensional measurements of the inner walls of deep micro-holes with diameters on the order of millimeters or even hundreds of micrometers and with large aspect ratios has become a research hotspot in the field of precision measurement and instrumentation science.

[0020] Endoscopic measurement systems based on white light interferometry or spectral domain / sweep frequency OCT typically use single-mode fiber to transmit the light beam, which is focused and scanned by remote micro-optical elements, enabling the acquisition of high-resolution three-dimensional information of the inner wall within a certain aperture range.

[0021] However, existing endoscopic measurement systems still face key bottlenecks in high-precision three-dimensional measurement of deep micro-holes. Based on the location of the scanning mechanism, OCT endoscopes are mostly divided into two categories: proximal scanning and distal scanning.

[0022] The near-end scanning probe uses a long torque coil and a rotary joint to transmit the rotational motion of the near end to the far-end optical head to achieve circular or spiral scanning. This structure is relatively economical in engineering, but fiber bending and stress changes during rotation can cause refractive index fluctuations, resulting in non-uniform rotational distortion of the interference signal, which limits the imaging stability and phase accuracy of the system. At the same time, the scanning speed is also constrained by mechanical factors.

[0023] Remote scanning probes integrate micromotors, MEMS scanning mirrors, and other devices at the probe tip to achieve beam deflection and high-speed scanning. This can, to some extent, avoid signal distortion caused by rotating optical fibers and achieve higher scanning speeds. However, the introduction of micromotors and complex micro-optical components significantly increases the structural complexity and outer diameter of the probe. Typical remote scanning probes often have diameters of 1–3 mm or even larger, making it difficult to further shrink them to the hundreds of micrometers level. This limits their use for measuring the interiors of deep micro-holes with smaller diameters and larger aspect ratios. Furthermore, the high cost, reliability, and assembly requirements of micromotors also hinder the widespread application of this type of measurement technology in industrial online inspection.

[0024] Furthermore, existing optical endoscopic measurement systems are primarily designed for medical imaging, focusing on large field-of-view imaging capabilities for soft tissues, while lacking sufficient adaptability to measurements of highly reflective and scattering metal inner walls. Within high aspect ratio deep metal micro-apertures, the light beam is prone to multiple reflections and scattering, resulting in significant attenuation of the reflected signal intensity. This, coupled with fiber optic and system-level losses and crosstalk, often leads to a low signal-to-noise ratio and a rapid decrease in measurement accuracy with increasing aperture depth. In summary, current technologies struggle to simultaneously meet the requirements of: probe diameter approaching the hundred-micrometer range, adaptability to high aspect ratio deep micro-apertures, and high-precision three-dimensional measurement.

[0025] Therefore, there is an urgent need to propose a new three-dimensional measurement technology for deep micro-holes that can avoid signal distortion and structural amplification effects introduced by the rotating mechanism while ensuring high measurement accuracy, achieve miniaturization of the endoscopic probe, and have the ability to perform high-efficiency three-dimensional measurement of the inner wall of small holes with high aspect ratio, so as to meet the urgent needs of aerospace and other fields for precision detection of deep micro-holes.

[0026] like Figure 1 As shown in the figure, an embodiment of the present invention proposes a deep micro-hole three-dimensional measurement optical path system, which includes a swept-frequency interferometric measurement optical path and an endoscope optical path.

[0027] The swept-frequency interferometric measurement optical path is used to generate probe light and reference light. The endoscope optical path includes a near-end spatial optical path scanning structure and a far-end endoscope structure. The near-end spatial optical path scanning structure includes a collimator, a beam splitter, a galvanometer, a microscope objective, and a multi-core fiber. The collimator receives the probe light emitted from the swept-frequency interferometric measurement optical path and collimates it into parallel light. After passing through the beam splitter and having its parallel light output angle adjusted by the galvanometer, the light is coupled to a single core of the multi-core fiber by the microscope objective. The light emitted from the far end of the multi-core fiber is focused by the far-end endoscope structure onto a point on the target on the wall of the test aperture. The scattered light from the target is retrieved from the far end of the multi-core fiber and returns to the swept-frequency interferometric measurement optical path via the original optical path. The swept-frequency interferometric measurement optical path combines the scattered light with the reference light to form interference information.

[0028] Specifically, by combining the frequency-sweeping interferometry optical path with the endoscope optical path, high-precision three-dimensional measurement without the need for a mechanical rotation mechanism is achieved. In the system, the frequency-sweeping interferometry optical path is responsible for generating the probe light and reference light, and uses the principle of optical frequency sweeping interferometry to achieve high-resolution depth ranging; the endoscope optical path adopts a design that separates the near-end spatial optical path scanning structure from the far-end endoscope structure. The collimator, beam splitter, galvanometer, microscope objective, and multi-core fiber work together to ensure that the probe light, after being adjusted by the galvanometer angle, is efficiently coupled by the microscope objective into a single core of the multi-core fiber, forming a stable and controllable incident channel.

[0029] After the light is transmitted to the remote end via the multi-core optical fiber, it is focused onto the target point on the wall of the measured aperture by the remote endoscope structure, and the scattered light is collected. The scattered light returns to the swept-frequency interference optical path through the original optical path, and combines with the reference light to form an interference signal. Through this bidirectional common optical path structure design, the incident light and the return light share the optical channel, effectively eliminating phase drift and signal fluctuations caused by optical path separation or vibration, and improving the system's anti-interference ability and measurement stability.

[0030] Therefore, this application achieves precise point-to-point measurement inside deep micro-holes without requiring a rotating fiber optic body or a remote motor scanning mechanism. The system not only significantly reduces the probe's structural size, allowing the endoscope diameter to approach that of a multi-core fiber optic cable (hundreds of micrometers), but also avoids signal distortion caused by mechanical rotation. Compared to traditional proximal or distal scanning endoscopes, this approach achieves significant improvements in optical stability, measurement accuracy, probe miniaturization, and scanning speed, meeting the requirements for non-contact three-dimensional topography measurement of high aspect ratio and micro-hole structures.

[0031] Furthermore, the end face of the multi-core optical fiber includes multiple independent cores, which are arrayed laterally on the end face. The galvanometer is correspondingly positioned to the multi-core optical fiber, and optical scanning and gating of the multiple cores of the multi-core optical fiber are achieved through the galvanometer. By controlling the deflection angle of the galvanometer, the angle of the beam incident on the microscope objective is changed, so that the focused spot is sequentially coupled to different cores. For each core excited, a depth-oriented distance curve is obtained at the corresponding position on the target under test. By sequentially switching multiple cores, multi-point depth information in a circle or a region is obtained. Combined with the axial relative movement of the distal endoscope structure and the target under test, point cloud data of different axial sections are obtained, and the three-dimensional morphology of the inner wall of the deep micropore is obtained through a three-dimensional reconstruction algorithm.

[0032] This method utilizes a multi-core fiber end-face array structure combined with near-end galvanometer control to achieve optical-electronic scanning and gating of each fiber core, eliminating the need for mechanical rotation of the fiber or probe. By controlling the deflection angle of the galvanometer, the incident light spot is sequentially coupled to different fiber cores, thereby achieving multi-point depth scanning on the target surface. This approach effectively avoids signal distortion and positioning errors caused by fiber torsion in traditional rotating endoscope probes, improving system reliability and scanning speed. Combined with axial movement and 3D reconstruction algorithms, complete point cloud data of the inner wall of deep micropores can be continuously acquired, achieving high-precision and rapid 3D imaging.

[0033] Furthermore, the near-end spatial optical path scanning structure also includes a camera, which is configured correspondingly to the beam splitter. The camera is used to visually monitor the end face or coupled spot of the multi-core fiber. By scanning the deflection angle of the galvanometer and identifying the image features when different fiber cores are lit, a mapping table between the galvanometer deflection angle or driving voltage and the fiber core number is established to realize the calibration and selection of multiple fiber cores.

[0034] By introducing a camera into the near-end optical path, automatic calibration between the galvanometer angle and the fiber core position was achieved. The camera can monitor the brightness changes of the multi-core fiber end face or coupled spot in real time, and combine image recognition to determine the spot characteristics when different fiber cores are excited, thereby establishing a one-to-one mapping relationship between the galvanometer deflection angle or driving voltage and the fiber core number. This calibration mechanism eliminates the error of manual calibration, improves the accuracy and repeatability of optical scanning, and enables the galvanometer scanning to stably select the target fiber core. As a result, rapid initialization and high-stability operation of the multi-channel optical scanning system were achieved, providing a reliable guarantee for rotationless electronic scanning.

[0035] Furthermore, the distal endoscope structure includes a converging lens, which is located at the distal end of the multi-core optical fiber. The converging lens is used to converge the light emitted from the distal end of the multi-core optical fiber to a single point, thereby converting forward-emitting light into radial focusing.

[0036] A converging lens is placed at the far end of the multi-core optical fiber, enabling radial focusing of forward-emitting light from different fiber cores within the deep micro-aperture. This transforms the light transmission direction from axial to lateral illumination. This structure allows the target point to be located at any radial position on the aperture wall, achieving lateral measurement capabilities. This converging optical design ensures efficient use of light energy and improves the uniformity of illumination and focusing accuracy at the target point. Compared to traditional endoscopic probes that rely on mechanical rotation to achieve field-of-view coverage, this solution is compact, fast-responding, and significantly reduces the probe diameter, making it particularly suitable for deep-hole inspection scenarios on the order of hundreds of micrometers.

[0037] Furthermore, the sweep frequency interferometric measurement optical path includes a light source, a ranging optical path unit, and a signal detection and calculation unit. The ranging optical path unit includes a first beam splitter, an auxiliary path, and a first photodetector. The signal detection and calculation unit includes a second beam splitter, a measurement path, a reference path, a circulator, and a second photodetector. The laser output from the light source is split by the first beam splitter to generate a first laser and a second laser. The first laser is sent to the auxiliary path for interference and photoelectric conversion, and the resulting signal is sent to the first photodetector for light source nonlinear correction. The second laser is sent to the second beam splitter for splitting to generate a third laser and a fourth laser. The third laser is used as a probe light and is input to the circulator through the measurement path. After entering the circulator, the probe light is collimated into parallel light by the collimator. The fourth laser is used as a reference light and is input to the second photodetector through the reference path. The scattered light returning from the original optical path returns to the circulator and is combined with the reference light, and the interference signal is retrieved on the second photodetector.

[0038] The light source is preferably an FDML light source, which is a high-speed frequency-sweeping laser light source based on the Fourier Domain Mode Locking principle. It achieves extremely high sweep rate and coherence by placing a long-delay fiber and a tunable filter within the fiber ring cavity, ensuring that the frequency scanning period of the filter is strictly synchronized with the round-trip time of the light within the cavity.

[0039] By constructing a complete signal generation and detection system for the swept-frequency interferometric measurement optical path, high-precision interferometric ranging of the scattered light from the target was achieved. The swept-frequency laser output from the light source is split into measurement and reference beams through multi-stage beam splitting. Nonlinear correction is performed through an auxiliary path, significantly improving the linearity of the spectral scan and the ranging accuracy. The circulator and multi-beam splitting structure ensure stable distribution and beam combining of the probe and reference beams on the optical path, guaranteeing a high signal-to-noise ratio output of the interferometric signal. Finally, the interferometric signal obtained on the photodetector can be directly used for depth inversion, achieving nanometer-level optical path difference measurement capability and providing high-quality raw data for subsequent 3D topography reconstruction.

[0040] Furthermore, the ranging optical path unit also includes a third beam splitter and a fourth beam splitter. The auxiliary path is located between the third beam splitter and the fourth beam splitter. The first laser beam is fed into the third beam splitter and split into a fifth laser beam and a sixth laser beam. The fifth laser beam enters the fourth beam splitter through the auxiliary path, and the sixth laser beam enters the fourth beam splitter. The fourth beam splitter is connected to the first photodetector. The signal detection and calculation unit also includes a fifth beam splitter. The circulator is connected to the second photodetector through the fifth beam splitter, and the second beam splitter is connected to the fifth beam splitter through the reference path.

[0041] In this design, a third, fourth, and fifth beam splitter are further introduced into the swept-frequency interferometric optical path, optimizing the optical path distribution structure. Through multi-stage beam splitting, the light intensity of the auxiliary path and the main measurement path can be independently adjusted, allowing the nonlinear correction signal and the interference signal to be obtained simultaneously, thus improving system stability and calibration accuracy. The multi-channel photoelectric detection design enables the system to perform real-time correction while maintaining high optical power utilization, suppressing measurement errors caused by light source wavelength drift. This optical path topology enhances the dynamic range of signal detection, improves the clarity of interference fringes and the accuracy of spectral reconstruction, thereby significantly improving the stability and repeatability of the three-dimensional measurement results.

[0042] exist Figure 1 In this diagram, FDML represents the light source, beam splitter 1 represents the first beam splitter, beam splitter 2 represents the second beam splitter, beam splitter 3 represents the third beam splitter, beam splitter 4 represents the fourth beam splitter, beam splitter 5 represents the fourth beam splitter, photodetector 1 represents the first photodetector, and photodetector 2 represents the second photodetector.

[0043] Based on the principle of 3D scanning and rotation-free imaging, a multi-core optical fiber has multiple independent cores on its end face, arranged in an array. By controlling the deflection angle of the near-end galvanometer, the angle of the beam incident on the microscope objective is changed, allowing the focused spot to be precisely coupled to different cores sequentially. This enables "electronic scanning" selection of multiple cores without rotating the fiber itself or using torque coils or micromotors. Each core excitation acquires a depth-oriented distance curve at the corresponding position on the target. By sequentially switching multiple cores, multi-point depth information within a circle or area can be obtained. Combined with the axial relative movement of the probe and the workpiece, point cloud data of different axial sections can be acquired. Finally, the 3D morphology of the inner wall of the deep micropore is obtained through a 3D reconstruction algorithm.

[0044] To ensure a one-to-one correspondence between the galvanometer scanning angle and the position of the multi-core fiber, this invention further employs an automatic calibration technique based on galvanometer / fiber core matching. Due to the small diameter (approximately 1.8 μm) and limited numerical aperture of the multi-core fiber core, even a slight deviation in the exit angle of the microscope objective can cause the beam to fail to accurately couple to the target fiber core, resulting in crosstalk between channels and fluctuations in coupling efficiency. The system incorporates an auxiliary imaging unit at the near end to visually monitor the end face or coupling spot of the multi-core fiber. By scanning the galvanometer angle and identifying the image characteristics when different fibers are illuminated, a mapping table is established between the galvanometer deflection angle or driving voltage and the fiber core number, enabling automatic calibration and rapid gating of the multi-core fiber. During measurement, this calibration relationship is invoked, allowing for stable and repeatable multi-point scanning without mechanical rotation, thus replacing the rotating mechanism in traditional endoscopes.

[0045] In summary, this invention utilizes the combined principle of low-coherence interferometric ranging and multi-core fiber multi-channel transmission. It achieves optical scanning and gating of multiple fiber cores through a near-end galvanometer and converts forward-looking light into radial focusing with a far-end side-viewing optical structure. This enables high-precision three-dimensional measurement of the inner wall of deep micro-holes by a small-diameter endoscopic probe without the need for a mechanical rotation mechanism. It effectively overcomes the problems of signal distortion and difficulty in miniaturizing probes that exist in existing near-end rotation and far-end micro-motor scanning endoscopes.

[0046] The superiority of this system lies in utilizing the multi-path characteristics of multi-core optical fibers, avoiding signal distortion caused by fiber torsion due to the torque coil placed at the near end of the near-end scanning probe. Simultaneously, the use of galvanometer scanning increases scanning speed and improves measurement efficiency. It also avoids the need for a motor to be integrated into the far-end scanning probe, which would lead to a more complex probe structure and increased size. The diameter of the endoscope based on multi-core optical fibers is minimized to the diameter of the multi-core optical fiber itself. This reduces the diameter of the aperture that the endoscope can measure from the millimeter level to the hundreds of micrometer level. Furthermore, the accuracy is less affected by the aperture depth, making it particularly advantageous for measuring apertures with large depth-to-diameter ratios.

[0047] On the other hand, a method for three-dimensional measurement of deep micropores is provided for use in the aforementioned optical path system for three-dimensional measurement of deep micropores, comprising: The sweeping laser light source output from the sweeping interferometric measurement optical path is split into probe light and reference light by the first beam splitter; The probe light is collimated into parallel light by a collimator. The parallel light is then incident on the microscope objective after passing through a beam splitter and a galvanometer. The angle of the incident beam is changed by adjusting the deflection angle of the galvanometer, so that the focused spot is sequentially coupled to different cores of the multi-core optical fiber. The light emitted from the far end of the multi-core optical fiber is focused onto a point on the target on the wall of the test hole by the far end endoscope structure, and the scattered light from the target returns through the original optical path and is coupled back to the multi-core optical fiber. The scattered light returned by the circulator and beam splitter is combined with the reference light on the second photodetector to form an interference signal. The interference signal is then subjected to spectral linearization correction and depth inversion by the signal detection and calculation unit to obtain the depth-distance curve corresponding to the fiber core position. By controlling the deflection of the galvanometer, optical scanning and gating of multiple cores in a multi-core optical fiber can be achieved, thereby sequentially acquiring multi-point depth information within a circle or a region. By combining the axial relative movement between the remote endoscope structure and the target under test, point cloud data of different axial sections are obtained; the point cloud data are spatially registered and three-dimensionally reconstructed to obtain the three-dimensional morphology of the inner wall of the deep micropore.

[0048] This method achieves a complete three-dimensional measurement process from light source to data reconstruction by coordinating the operation of frequency-sweeping light source output, galvanometer scanning, fiber optic coupling, and interferometric signal detection. The probe light is precisely scanned and coupled to different channels of a multi-core optical fiber via a galvanometer, enabling electronic scanning of multiple points in space. The depth curve obtained through interferometric detection is processed by signal calculation and a three-dimensional reconstruction algorithm to form the complete three-dimensional morphology of the measured hole wall. This method effectively avoids the structural complexity and optical jitter problems caused by mechanical rotation mechanisms, achieving non-contact, rotation-free three-dimensional measurement of deep micro-holes. The overall solution boasts technical advantages of high speed, high stability, and high spatial resolution.

[0049] Furthermore, the deep micropore three-dimensional measurement method also includes: Before measuring the target, the end face or coupled spot of the multi-core fiber is visually monitored by a camera. By scanning the deflection angle of the galvanometer and identifying the image features when different fiber cores are lit, a mapping table between the galvanometer deflection angle or driving voltage and the fiber core number is established to calibrate and select multiple fiber cores.

[0050] The system employs an automated visual calibration process prior to measurement, establishing an accurate mapping between the galvanometer deflection angle and the positions of each fiber core in a multi-core fiber. By monitoring the coupling spot and analyzing brightness changes using a camera, automatic identification and numbering are achieved, ensuring precise coupling of the beam to the target fiber core during galvanometer scanning. This calibration process eliminates scanning mismatches caused by assembly errors or optical path offsets, improving channel consistency and coupling efficiency stability. This enables rapid and reliable multi-point optical scanning without any mechanical rotation or complex adjustments, significantly enhancing the system's measurement accuracy and repeatability.

[0051] The aforementioned optical path system and method for deep micro-aperture 3D measurement solves the problems of interference signal distortion caused by fiber torsion in traditional near-end rotating endoscopes and the difficulty in miniaturizing the probe size due to motor integration in far-end scanning endoscopes by combining a swept-frequency interferometric measurement optical path with an endoscope optical path. This system uses a swept-frequency interferometric optical path to generate probe and reference beams, and utilizes a collimator, beam splitter, galvanometer, and microscope objective in the near-end spatial optical path scanning structure to precisely couple the probe beam to a single core of a multi-core fiber. The light is focused onto the target point by the far-end endoscope structure, and the scattered light returns along the original optical path, combining with the reference beam to form an interference signal, thereby achieving high-precision 3D measurement of the inner wall of the deep micro-aperture. This design eliminates the mechanical rotation mechanism, and the probe size is comparable to that of a multi-core fiber, avoiding fiber stress and signal distortion problems. Simultaneously, the bidirectional common optical path structure improves the system's anti-interference and measurement stability, realizing small-diameter, high-precision, non-contact 3D imaging of deep micro-apertures.

[0052] In one embodiment, a computer device is provided, which may be a server, and its internal structure diagram may be as follows: Figure 2 As shown, the computer device includes a processor, memory, network interface, and database connected via a system bus. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and database. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The database stores data for a deep micro-aperture three-dimensional measurement optical path system. The network interface communicates with external terminals via a network connection. When the computer program is executed by the processor, it implements a deep micro-aperture three-dimensional measurement optical path system.

[0053] Those skilled in the art will understand that Figure 2 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0054] In one embodiment, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of a deep micropore three-dimensional measurement method.

[0055] For specific limitations on the steps implemented by the processor when executing a computer program, please refer to the limitations on the method of the deep micro-hole three-dimensional measurement optical path system mentioned above, which will not be repeated here.

[0056] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps of a deep micropore three-dimensional measurement method.

[0057] For specific limitations on the steps implemented when a computer program is executed by a processor, please refer to the limitations on the method of the optical path system for deep micro-hole three-dimensional measurement mentioned above, which will not be repeated here.

[0058] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0059] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0060] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A deep micro-aperture three-dimensional measurement optical path system, characterized in that, The deep micro-hole three-dimensional measurement optical path system includes a swept-frequency interferometric measurement optical path and an endoscope optical path; The swept-frequency interferometric measurement optical path is used to generate probe light and reference light. The endoscope optical path includes a near-end spatial optical path scanning structure and a far-end endoscope structure. The near-end spatial optical path scanning structure includes a collimator, a beam splitter, a galvanometer, a microscope objective, and a multi-core fiber. The collimator receives the probe light emitted from the swept-frequency interferometric measurement optical path and collimates it into parallel light. After passing through the beam splitter and having its parallel light output angle adjusted by the galvanometer, the light is coupled to a single core of the multi-core fiber by the microscope objective. The light emitted from the far end of the multi-core fiber is focused by the far-end endoscope structure onto a point on the target on the wall of the test aperture. The scattered light from the target is retrieved from the far end of the multi-core fiber and returns to the swept-frequency interferometric measurement optical path via the original optical path. The swept-frequency interferometric measurement optical path combines the scattered light with the reference light to form interference information.

2. The deep micro-hole three-dimensional measurement optical path system according to claim 1, characterized in that, The end face of the multi-core optical fiber includes multiple independent cores arranged in an array on the end face. The galvanometer is correspondingly positioned to the multi-core optical fiber, enabling optical scanning and selection of the multiple cores. By controlling the deflection angle of the galvanometer, the angle of the beam incident on the microscope objective is changed, allowing the focused spot to be coupled sequentially to different cores. For each core excited, a depth-oriented distance curve is acquired at the corresponding position on the target under test. By sequentially switching multiple cores, multi-point depth information within a circle or area is obtained. Combined with the axial relative movement of the distal endoscope structure and the target under test, point cloud data of different axial sections are acquired, and the three-dimensional morphology of the inner wall of the deep micropore is obtained through a three-dimensional reconstruction algorithm.

3. The deep micro-hole three-dimensional measurement optical path system according to claim 1, characterized in that, The near-end spatial optical path scanning structure also includes a camera, which is configured in correspondence with the beam splitter. The camera is used to visually monitor the end face or coupled spot of the multi-core fiber. By scanning the deflection angle of the galvanometer and identifying the image features when different fiber cores are lit, a mapping table between the galvanometer deflection angle or driving voltage and the fiber core number is established to realize the calibration and selection of multiple fiber cores.

4. The deep micro-hole three-dimensional measurement optical path system according to claim 1, characterized in that, The distal endoscope structure includes a converging lens, which is located at the distal end of the multi-core optical fiber. The converging lens is used to converge the light emitted from the distal end of the multi-core optical fiber to a single point, thereby converting forward-emitting light into radial focusing.

5. The deep micro-hole three-dimensional measurement optical path system according to claim 1, characterized in that, The sweeping interferometric measurement optical path includes a light source, a ranging optical path unit, and a signal detection and calculation unit. The ranging optical path unit includes a first beam splitter, an auxiliary path, and a first photodetector. The signal detection and calculation unit includes a second beam splitter, a measurement path, a reference path, a circulator, and a second photodetector. The laser output from the light source is split by the first beam splitter to generate a first laser and a second laser. The first laser is sent to the auxiliary path for interference and photoelectric conversion, and the resulting signal is sent to the first photodetector for light source nonlinear correction. The second laser is sent to the second beam splitter for splitting to generate a third laser and a fourth laser. The third laser is used as a probe light and is input to the circulator through the measurement path. After entering the circulator, the probe light is collimated into parallel light by the collimator. The fourth laser is used as a reference light and is input to the second photodetector through the reference path. The scattered light returning from the original optical path returns to the circulator and is combined with the reference light, and the interference signal is retrieved on the second photodetector.

6. The deep micro-hole three-dimensional measurement optical path system according to claim 5, characterized in that, The ranging optical path unit further includes a third beam splitter and a fourth beam splitter. The auxiliary path is located between the third beam splitter and the fourth beam splitter. The first laser beam is fed into the third beam splitter and split into a fifth laser beam and a sixth laser beam. The fifth laser beam enters the fourth beam splitter through the auxiliary path, and the sixth laser beam enters the fourth beam splitter. The fourth beam splitter is connected to the first photodetector. The signal detection and calculation unit further includes a fifth beam splitter. The circulator is connected to the second photodetector through the fifth beam splitter. The second beam splitter is connected to the fifth beam splitter through the reference path.

7. A method for three-dimensional measurement of deep micropores, used in the optical path system for three-dimensional measurement of deep micropores as described in any one of claims 1 to 6, characterized in that, include: The sweeping laser light source output from the sweeping interferometric measurement optical path is split into probe light and reference light by the first beam splitter; The probe light is collimated into parallel light by a collimator. The parallel light is then incident on the microscope objective after passing through a beam splitter and a galvanometer. The angle of the incident beam is changed by adjusting the deflection angle of the galvanometer, so that the focused spot is sequentially coupled to different cores of the multi-core optical fiber. The light emitted from the far end of the multi-core optical fiber is focused onto a point on the target on the wall of the test hole by the far end endoscope structure, and the scattered light from the target returns through the original optical path and is coupled back to the multi-core optical fiber. The scattered light returned by the circulator and beam splitter is combined with the reference light on the second photodetector to form an interference signal. The interference signal is then subjected to spectral linearization correction and depth inversion by the signal detection and calculation unit to obtain the depth-distance curve corresponding to the fiber core position. By controlling the deflection of the galvanometer, optical scanning and gating of multiple cores in a multi-core optical fiber can be achieved, thereby sequentially acquiring multi-point depth information within a circle or a region. By combining the axial relative movement between the remote endoscope structure and the target under test, point cloud data of different axial sections are obtained; the point cloud data are spatially registered and three-dimensionally reconstructed to obtain the three-dimensional morphology of the inner wall of the deep micropore.

8. The method for three-dimensional measurement of deep micropores according to claim 7, characterized in that, Also includes: Before measuring the target, the end face or coupled spot of the multi-core fiber is visually monitored by a camera. By scanning the deflection angle of the galvanometer and identifying the image features when different fiber cores are lit, a mapping table between the galvanometer deflection angle or driving voltage and the fiber core number is established to calibrate and select multiple fiber cores.

9. A computer device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method of claim 7 or 8.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method of claim 7 or 8.

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