A parallel demodulation and intelligent imaging system based on a reconfigurable fiber ultrasonic detection array

Abstract

This invention discloses a parallel demodulation and intelligent imaging system based on a reconfigurable fiber optic ultrasonic detection array, belonging to the field of ultrasonic / photoacoustic detection and imaging technology. A splicing and clamping type of flexibly reconfigurable fiber optic ultrasonic detection array structure is designed, using detachable slots and assembly fixtures for assembly, supporting dynamic splicing and reconfiguration of the array as needed to adapt to diverse detection environments. A wavelength division multiplexing (WDM) to time division multiplexing (TDM) high-capacity, streamlined parallel demodulation system is developed, forming a path-sharing delay system through the coordinated configuration of delay and beam combining, distinguishing multi-channel detection signals in the time domain, while maintaining small size and low cost. A sound velocity inversion-based highly intelligent calibration ultrasonic imaging algorithm is constructed, integrating a deep learning model to adaptively correct sound velocity distortion in non-uniform media, achieving high-quality imaging. This invention achieves flexible layout, streamlined link, and high-fidelity fiber optic array-based ultrasonic / photoacoustic imaging through synergistic optimization of front-end detection, mid-end demodulation, and back-end imaging.

Description

Technical Field

[0001] This invention belongs to the field of ultrasonic / photoacoustic signal detection and imaging technology, and more specifically, relates to a parallel demodulation and intelligent imaging system based on a reconfigurable fiber ultrasonic detection array. Background Technology

[0002] Fiber optic ultrasonic testing technology combines the small size and high toughness of fiber optic ultrasonic transducers, offering advantages such as non-radiation, non-invasiveness, and high sensitivity. It has demonstrated application value in fields such as industrial non-destructive testing, new energy equipment monitoring, and geological exploration. Among these, array-type ultrasonic testing improves time-domain utilization efficiency while enhancing spatial acquisition density, making it more suitable for large-scale, high-speed imaging scenarios.

[0003] However, traditional fiber optic ultrasonic detection arrays often use pre-formed fiber bundles as a base, resulting in limited assembly methods and scalability. Damage to any element can lead to overall array performance degradation or even failure. Furthermore, existing demodulation systems suffer from complex networking links and numerous components. Serial polling modes experience reduced data throughput due to channel switching delays, posing challenges for parallel demodulation. In addition, practical applications demand higher requirements for algorithm universality and image fidelity. Commonly used image synthesis algorithms, such as time reversal and filtered backprojection, rely on strict physical assumptions and are prone to model mismatch and computational redundancy when dealing with inhomogeneous media, requiring urgent improvement.

[0004] Therefore, it is necessary to design a flexibly reconfigurable fiber array structure, develop a high-capacity and streamlined parallel demodulation system, and introduce a highly intelligent calibration image reconstruction algorithm to realize a reconfigurable array-type parallel demodulation and intelligent imaging system with coordinated optimization of the front, middle, and back ends. Summary of the Invention

[0005] To address the aforementioned deficiencies or improvement needs of existing technologies, this invention provides a parallel demodulation and intelligent imaging system based on a reconfigurable fiber optic ultrasonic detection array. The system aims to solve problems such as the fixed front-end array configuration leading to limited integration methods and mismatched detection resources; the redundancy of mid-end multi-channel demodulation links causing high system costs and significant parallelization challenges; and the strong constraints of back-end image reconstruction algorithms resulting in distorted imaging results and difficulty in generalizing applications.

[0006] To achieve the above objectives, the present invention provides a parallel demodulation and intelligent imaging system based on a reconfigurable fiber optic ultrasonic detection array, comprising:

[0007] The laser emission and modulation module is used to provide continuous emission light sources of different wavelengths for each channel block and modulate them into pulsed laser output;

[0008] An ultrasonic emission and detection module is used to provide an ultrasonic or photoacoustic signal emission source and to detect ultrasonic or photoacoustic signals through a fiber optic ultrasonic detection array. The ultrasonic or photoacoustic signals act on the fiber optic ultrasonic detection array elements to form multi-channel detection optical signals.

[0009] The parallel acquisition and processing module is used for signal acquisition and data processing of multi-channel probe optical signals;

[0010] The algorithm execution and imaging module is used to reconstruct images of the target under test and display the results.

[0011] During operation, the pulsed laser from each channel block is transmitted to the ultrasonic emission and detection module. N A fiber optic ultrasonic detection array element; after the ultrasonic or photoacoustic signal is transmitted or reflected by the target, it forms... N The channel probe optical signal, after undergoing delays of varying durations and beam combining in the parallel acquisition and processing module, forms a time domain image. N A sequence of probe optical signals; for N Data analysis and algorithm processing are performed on the sequence of probe light signals to obtain a reconstructed image of the target.

[0012] Furthermore, the laser emission and modulation module includes:

[0013] A multi-wavelength emission light source is used to output multiple single-wavelength continuous lights as independent light sources for each detection block;

[0014] Multiple channel block modulators are used to modulate continuous light of different wavelengths into pulsed laser outputs of each channel block; wherein, the fiber ultrasonic detection array elements in each channel block have the same operating wavelength, which is the single wavelength of the emitted laser provided by the multi-wavelength emission source.

[0015] The signal generator is used to control all channel block modulators, set the modulation waveform, repetition frequency, pulse width and other properties of all channel modulators, and synchronously control the ultrasonic transmitter and data acquisition unit, so that laser emission, ultrasonic emission and signal acquisition can be carried out simultaneously.

[0016] Furthermore, the ultrasonic emission and detection module includes:

[0017] An ultrasonic transmitter is used to emit ultrasonic signals to directly generate ultrasonic waves, or to emit photoacoustic signals and generate ultrasonic waves after photoacoustic conversion.

[0018] The fiber optic ultrasonic detection array consists of multiple fiber optic ultrasonic detection elements. Elements with the same operating wavelength are grouped into the same channel block for detecting ultrasonic signals. Ultrasonic information is fed back by changes in the phase, intensity, and wavelength of the detection light signal within the fiber under acoustic pressure. The relative position of the array to the ultrasonic transmitter depends on the scanning imaging method. Preferably, the target under test is used as the imaging target and placed on a displacement control console. The displacement control console controls the XYZ three-axis translation, allowing the ultrasonic waves to act on different parts of the target under test, achieving full coverage of the scanning range.

[0019] The structure and working principle of the fiber optic ultrasonic detection array are as follows:

[0020] For a single channel block, the fiber optic ultrasonic detection array consists of N It consists of several independent fiber optic ultrasonic detection array elements, typically of micro-ring, grating, or Fabry-Perot type, all using a resonant cavity as the ultrasonic sensing structure. When ultrasound waves act on the ultrasonic sensing structure, the sound pressure causes changes in the phase, intensity, and wavelength of the laser within the fiber, becoming a detection optical signal. This multi-channel detection optical signal carrying ultrasonic information is transmitted to a parallel acquisition and processing module for demodulation, thereby acquiring the ultrasonic information and realizing array-based detection.

[0021] Furthermore, the parallel acquisition and processing module includes:

[0022] 1* N Fiber optic beam splitters are used to evenly divide the emitted laser power of each channel block in a system. N The paths are output to... N One detection channel;

[0023] A circulator is used to transmit probe light signals in a specific order; each circulator includes a first port, a second port, and a third port. m The first channel block n The pulsed laser input to the first n The first port of the circulator reaches the second port through the circulator. The detection light signal carrying the information of the target to be measured enters the circulator through the second port and is output from the third port.

[0024] Delay fiber is used to extend the transmission path of the probe optical signal and achieve time-domain delay;

[0025] A 2*1 fiber optic combiner is used to couple the delay fiber and the probe optical signal output from the circulator into a single probe optical signal output; m The first channel block n After a delay, the path detection optical signal is compared with the first... n -1 channel probe optical signal beam is output, with each channel block connected in series; among which... M The number of channel blocks,m =1, 2, ..., M , n =1, 2, ..., N ;

[0026] A photodetector is used to convert a detection optical signal into an electrical signal for output.

[0027] A data acquisition unit is used to acquire electrical signals output by a photodetector and convert analog electrical signals into digital electrical signals for easier data processing.

[0028] The specific delay method for the delay optical fiber is as follows:

[0029] The system includes M Each channel block contains fiber optic ultrasonic detector elements with the same operating wavelength and sensing performance. Taking any single channel block as an example, it contains elements composed of… N A fiber optic ultrasonic detector array, consisting of [number] fiber optic ultrasonic detector elements, requires a total of [number] configuration elements. N -1 time-delay fiber segments, each with its input end connected to a circulator and its output end connected to a 2*1 fiber combiner. Specifically, the probe light signal of CH_1, after passing through the first circulator, is output directly without going through the time-delay fiber; the probe light signal of CH_2 passes through the second circulator and the first time-delay fiber segment, and is coupled to the probe light signal of CH_1 via the first 2*1 fiber combiner; recursively, CH_ N The detection light signal passes through the first N The circulator, the first N -1 segment of delay fiber, and CH_ N -1 detection light signal via the first N -1 2*1 fiber combiner coupled output, then through the first N -2 segments of delay fiber, and CH_ N -2 detection light signal via the first N - Two 2*1 fiber optic combiners couple the outputs until the final delay fiber, where the probe light signal from CH_1 is coupled to the photodetector via the first 2*1 fiber optic combiner. Thus, in N In the transmission path of the detection optical signal of the fiber optic ultrasonic detection array composed of fiber optic ultrasonic detection elements, the unique transmission path of CH_1 accumulates through... N This time, CH_2's unique transmission path has accumulated through [number] [times]. N -1 time. And so on, this path-sharing delay method saves on the amount of delay fiber required, greatly reducing the system's space footprint.

[0030] Furthermore, the algorithm execution and imaging module includes:

[0031] The terminal controller is used to analyze the electrical signals obtained by the data acquisition unit and further process them through algorithms.

[0032] An image display that presents synthesized two-dimensional or three-dimensional reconstructed images.

[0033] The operating principle of the wavelength division-time division high-capacity simplified parallel demodulation system is as follows:

[0034] (1) Multiple single-wavelength continuous emission lasers are output from a multi-wavelength emission light source to provide emission light sources for each channel block. After being modulated by the modulator of their respective channel blocks, pulsed lasers are output.

[0035] (2) The laser beam after passing through the modulators of each channel block passes through 1* N Fiber optic beam splitters enter respectively N Each detection channel has a circulator configured in each channel to transmit the laser to the fiber optic ultrasonic detection array;

[0036] (3) The ultrasonic transmitter emits ultrasonic waves, which are then reflected or transmitted by the target and act on the fiber ultrasonic detection array, causing a change in the properties of the transmitted light in the fiber and forming a detection light signal carrying ultrasonic information.

[0037] (4) N The channel probe optical signal simultaneously returns to the circulator of the corresponding channel. After passing through different segments of delay fiber, it forms a periodic probe optical signal sequence. This sequence is then combined into a single channel by a 2*1 fiber combiner, carrying the signal... N The single-channel signal of each detection information is then sequentially returned to the photodetector and the data acquisition unit;

[0038] (5) After the collected signals are processed and analyzed by the algorithm, the synthesized image of the target under test is presented on the image display, thus completing the acquisition and restoration of the target structure information.

[0039] Furthermore, the fiber optic ultrasonic detection array structure is a splicing and clamping type that can be flexibly reconfigured, mainly including:

[0040] The detachable assembly clamping structure is used to independently encapsulate the fiber optic ultrasonic detection array elements for disassembly and assembly, and to clamp and protect the fiber optic ultrasonic detection array.

[0041] Furthermore, the detachable assembly clamping structure includes:

[0042] A slotted hollow mold is used to independently encapsulate discrete fiber optic ultrasonic detector array elements; an adhesive filling area is located between the through-hole of the slotted hollow mold and the fiber optic ultrasonic detector array element, used to carry the adhesive; the fiber optic ultrasonic detector array element, as the object to be encapsulated, is bonded to the slotted hollow mold with waterproof adhesive and then inserted through the slot; an assembly and fixing fixture is used to fix the slotted hollow mold to ensure the stability of the encapsulation.

[0043] Furthermore, the assembly and fixing fixture includes:

[0044] A connecting stud, containing external threads, is connected to a fixed connecting rod; a fixed connecting rod is connected to the connecting stud via a threaded connection; a hinged connecting rod, with a fixed length, is connected to the fixed connecting rod via a pin connection; a scissor link, with an adjustable length, is connected to the hinged connecting rod via a hinge connection, the scissor link extending and retracting to adapt to the volume of the clamp; a swinging jaw, with an adjustable jaw angle, is connected to the scissor link via a pin connection, the swinging jaw adapting to the volume of the clamp by changing its rotation angle; adjusting knobs a, b, and c are used to control the angle between the hinged connecting rods, the extension / retraction length of the scissor link, and the rotation angle of the swinging jaw, respectively.

[0045] Furthermore, the assembly method of the fiber optic ultrasonic detection array structure includes the following steps:

[0046] S1. The fiber optic ultrasonic detector elements are sequentially bonded to their respective molds using a waterproof adhesive, and the process is performed under a microscope to ensure that the length of the fiber optic cables extending out of the molds is consistent.

[0047] S2. The individually packaged fiber optic ultrasonic detector elements are spliced ​​together through their built-in slots to form a scanning array with any arrangement, either linear or planar arrays.

[0048] S3. Select the appropriate connection method and connect the connecting stud, fixed link, hinge link, scissor link, and swing gripper in sequence;

[0049] S4. Rotate adjustment knob a to change the included angle between the two hinged links to ensure that the horizontal direction matches the array volume. Rotate adjustment knob b to change the length of the two scissor links to ensure that the vertical direction matches the array volume. Rotate adjustment knob c to change the plane rotation angle of the swing gripper to ensure that it is tightly assembled with the array.

[0050] This invention also provides a sound velocity inversion-based highly intelligent calibration ultrasound imaging algorithm, comprising the following operational flow:

[0051] S1. Based on the inherent properties of the material of the target object, standard sound velocity values ​​are defined for different conditions such as healthy matrix, porosity defects, and corroded areas. These values ​​are then randomly filled into a pre-created two-dimensional grid to generate a large number of grid maps containing spatially varying sound velocity values, i.e., the true sound velocity distribution. g ( n true( )};

[0052] S2. Import the real sound velocity distribution model generated in S1 into a numerical solver such as k-Wave or COMSOL to simulate the physical phenomena such as refraction, scattering, and diffraction that occur when ultrasound propagates in a non-uniform medium, as well as the resulting wavefront distortion and signal delay, to obtain the simulated sound pressure signal received by the detection array. q ( n ) sim( t );

[0053] S3. The traditional SAFT (Synthetic Aperture Focusing Technique) algorithm with a fixed uniform reference sound velocity value is used to reconstruct the simulated sound pressure signal generated in S2, outputting a distorted ultrasound image. h ( n )distorted( ), and together with the actual sound speed distribution, form a supervised learning training pair { h ( n distorted( ), g ( n true( )};

[0054] S4. Input the training dataset constructed in S3 into the CS-UNet (ConvNeXt-Swin Transformer-UNet) deep learning correction network for training. This network uses the ConvNeXt module to extract local features such as structures and defects in distorted images, and uses the Swin Transformer encoder to globally model the feature sequence, capturing global distortion caused by non-uniform sound velocity spatial variations. Then, the U-Net decoder uses skip connections to connect the aforementioned local detail features and global semantic features, progressively upsampling to reconstruct the sound velocity distribution map. The network is then optimized using a composite loss function composed of mean squared error loss and structural similarity loss, achieving the inversion mapping from true ultrasound images to the true sound velocity distribution, and finally outputting the calibrated predicted sound velocity distribution. pred( );

[0055] S5. In a real-world test, the detected real ultrasound signal is acquired, and SAFT reconstruction without sound velocity calibration is performed to obtain a measured distorted ultrasound image. This image is then input into a trained CS-UNet deep learning correction network to obtain the actual predicted sound velocity distribution;

[0056] S6. Using the intelligent sound velocity field prediction results obtained in S5 as input, re-execute the sound velocity-calibrated SAFT reconstruction to finally output a high-precision, distortion-free, realistic ultrasound image.

[0057] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve at least the following beneficial effects:

[0058] 1. The parallel demodulation and intelligent imaging system based on a reconfigurable fiber optic ultrasonic detection array provided by this invention optimizes the system from three aspects: array-type detection at the front end, parallel demodulation in the middle, and intelligent imaging at the back end. It designs an array structure that can be flexibly disassembled and freely assembled, develops a demodulation system that supports wavelength division-time division multiplexing and multi-signal simultaneous acquisition, and constructs an imaging algorithm that integrates sound velocity calibration and deep learning, providing technical support for the further application of fiber optic sensing and ultrasonic detection.

[0059] 2. This invention achieves independent packaging of fiber optic ultrasonic detector array elements and overall assembly of the fiber optic ultrasonic detector array through the combined use of slot-type hollow molds and assembly fixtures. Thanks to the detachable assembly design, the diversity and reconfigurability of the detector structure layout are ensured. When any fiber optic ultrasonic detector array element is damaged, it can be flexibly replaced, thereby ensuring the continuity of the overall resources and the effectiveness of the detector array's performance. Simultaneously, the push-in slots facilitate adjustment of the relative positions between the fiber optic ultrasonic detector array elements, which is more accommodating to the unavoidable phenomenon of differences in the elongation of the fiber optic ultrasonic detector array elements during assembly, thus reducing assembly difficulty.

[0060] 3. This invention uses 1* N The basic framework consists of an optical fiber bundler, a time-delay fiber, and a 2*1 optical fiber combiner. Parallel demodulation of multi-channel probe signals is achieved using the fundamental principles of wavelength division multiplexing (WDM) and time division multiplexing. N Fiber optic bundle splitters, time-delay fibers and N Compared to the configuration of *1 fiber combiners, this path-sharing architecture reduces the amount of delay fiber used from ( N -1)* N / 2 reduced to N-1 significantly improves the spatial reuse rate of system resources and the effective transmission rate of detection signals from each channel. Furthermore, the multi-channel detection signals are sequentially returned to a single photodetector based on the difference in delay path length and are received by a single-channel data acquisition unit. This greatly reduces the link complexity and construction cost of the demodulation system and expands the multiplexing capacity of the detection array.

[0061] 4. This invention effectively integrates the concept of ultrasonic velocity calibration in non-uniform media into the SAFT algorithm and builds an end-to-end intelligent deep learning calibration model, achieving high-fidelity output of realistic ultrasonic images. The CS-UNet calibration network extracts local features and analyzes global changes, ensuring that the internal structure of the target under test, which has spatial sound velocity differences, can be accurately identified. Unlike traditional SAFT, which is constrained by inherent sound velocities, this mapping learning model from distorted ultrasonic images to the true sound velocity distribution reflects that the algorithm has stronger adaptability and universality. It can infer the internal sound velocity field from only a single distorted image, providing a feasible technical solution for sound velocity calibration in both known and unknown media. Attached Figure Description

[0062] Figure 1 This is a schematic diagram of the wavelength division-time division high-capacity simplified parallel demodulation system provided by the present invention.

[0063] Figure 2 This is a schematic diagram of the splicing and clamping flexible reconfigurable fiber optic ultrasonic detection array structure provided by the present invention.

[0064] Figure 3 The flowchart of the ultrasonic imaging algorithm for sound velocity inversion-based high-intelligence calibration provided by this invention is shown.

[0065] Figure 4 This is a transmission imaging result diagram of a fiber optic ultrasonic detection array according to an embodiment of the present invention.

[0066] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, including: 1. Multi-wavelength emission light source; 2. First channel block modulator; 3. Last channel block modulator; 4. Signal generator; 5. Ultrasonic transmitter; 6. Target under test; 7. Displacement control console; 8. Fiber optic ultrasonic detection array; 9. 1* N10. Fiber optic bundle splitter, 11. Circulator, 12. Delay fiber, 13. 2*1 fiber optic bundle combiner, 14. Photodetector, 15. Data acquisition unit, 16. Terminal controller, 17. Image display, 18. Detachable assembly clamping structure, 17-1. Slot-type hollow mold, 17-2. Adhesive filling area, 17-3. Fiber optic ultrasonic detection array element, 17-4. Connecting stud, 17-5. Fixing link, 17-6. Adjusting knob a, 17-7. Hinge link, 17-8. Adjusting knob b, 17-9. Scissor link, 17-10. Adjusting knob c, 17-11. Swinging gripper. 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 the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0068] Combination Figure 1 The technical solution adopted in this invention is a wavelength division-time division high-capacity simplified parallel demodulation system. This invention uses transmission ultrasound imaging as an example to demonstrate the system construction method. It includes: a laser emission and modulation module, an ultrasound emission and detection module, a parallel acquisition and processing module, and an algorithm execution and imaging module.

[0069] Specifically, the laser emission and modulation module includes: a multi-wavelength emission light source 1, a first channel block modulator 2, a last channel block modulator 3, and a signal generator 4. The multi-wavelength emission light source 1 is connected to multiple channel block modulators, including the first channel block modulator 2 and the last channel block modulator 3, and all of these multiple channel block modulators are controlled by the signal generator 4.

[0070] The multi-wavelength emission light source 1 can be generated by external modulation and can output multiple quasi-continuous emission lasers of different wavelengths.

[0071] The external modulation method preferably uses a narrow-linewidth continuous spectrum laser as the initial emitted laser. It is then passed through a phase modulator such as an electro-optic phase modulator and an intensity modulator such as a Mach-Zehnder modulator to form an optical frequency comb. The laser is then amplified into a high peak power pulsed laser by an amplifier such as an erbium-doped fiber amplifier. The spectrum is then broadened by the nonlinear effect of a nonlinear medium such as a highly nonlinear fiber. Finally, wavelength division multiplexing is performed by a wavelength division multiplexing device such as a waveguide array grating or a wavelength division multiplexer to generate a multi-wavelength quasi-continuous emission laser.

[0072] The first channel block modulator 2, the last channel block modulator 3, and other system-connected multiple channel block modulators, preferably acousto-optic modulators, electro-optic modulators, etc., can modulate the quasi-continuous laser emitted by the multi-wavelength emission light source 1 into a pulse sequence output.

[0073] The signal generator 4 simultaneously sends commands to multiple channel block modulators connected to the system, such as the first channel block modulator 2 and the last channel block modulator 3, to control key parameters such as the modulation output waveform, laser emission repetition frequency, and pulse width.

[0074] To further explain, the ultrasonic emission and detection module includes: an ultrasonic transmitter 5, a target 6, a displacement control console 7, a fiber optic ultrasonic detection array 8, and a detachable assembly clamping structure 17. The ultrasonic waves emitted by the ultrasonic transmitter 5 act on the target 6, which is placed on the displacement control console 7 and remains relatively stationary, while the fiber optic ultrasonic detection array 8 detects the signals.

[0075] The ultrasonic transmitter 5 can be selected as an ultrasonic signal transmitter or a photoacoustic signal transmitter, used to directly transmit ultrasonic signals or to transmit ultrasonic signals after photoacoustic conversion.

[0076] The target to be tested 6 is selected according to the application scenario of the system. For example, when applied to industrial defect detection, the target to be tested 6 can be selected as a weld point, weld seam, etc.; when applied to new energy equipment monitoring, the target to be tested 6 can be selected as a battery, electric rod, etc.; and when applied to geological exploration, the target to be tested 6 can be selected as layered rock and soil, mud, etc.

[0077] The displacement control console 7 can be selected as a two-dimensional, three-dimensional, or multi-dimensional displacement stage according to the actual imaging scanning method, and its flexible movement can be controlled by writing a control program.

[0078] The arrangement of the fiber optic ultrasonic detector array 8 is related to the scanning imaging method. When performing transmission imaging, the fiber optic ultrasonic detector array 8 and the ultrasonic transmitter 5 are located on opposite sides of the target 6 under test. At this time, the fiber optic ultrasonic detector array 8 receives the ultrasonic signal after penetrating the target 6 under test. When performing reflection imaging, the fiber optic ultrasonic detector array 8 and the ultrasonic transmitter 5 are located on the same side of the target 6 under test. At this time, the fiber optic ultrasonic detector array 8 receives the ultrasonic signal reflected or scattered by the target 6 under test.

[0079] More specifically, the structure and working principle of the fiber optic ultrasonic detection array 8 are as follows:

[0080] For a single channel block, the fiber optic ultrasonic detection array 8 consists of... NThe system comprises several independent fiber optic ultrasonic detection array elements 17-3 with highly consistent performance, each possessing the same ultrasonic sensing structure. This invention uses a flat-cavity structure in a Fabry-Perot type as an example to fabricate multiple fiber optic ultrasonic detection array elements 17-3. Using transmission ultrasonic imaging as an example, the ultrasonic transmitter 5 is an ultrasonic signal transmitter. The ultrasonic wave is transmitted through the target 6 and acts on the fiber optic ultrasonic detection array 8, causing a change in the Fabry-Perot cavity length in this embodiment. This alters the multi-beam interference conditions within the cavity, leading to changes in the phase, intensity, and other properties of the detection light. The difference in light wave properties before and after the acoustic pressure effect is demodulated using the oblique demodulation method to ultimately obtain ultrasonic information.

[0081] To further explain, the parallel acquisition and processing module includes: 1* N Fiber optic bundle splitter 9, circulator 10, delay fiber 11, 2*1 fiber optic bundle combiner 12, photodetector 13, data acquisition unit 14. The 1* N The fiber optic splitter 9 is connected to the first port of the circulator 10, the second port of the circulator 10 is connected to the fiber optic ultrasonic detection array 8, the third port of the circulator 10 is connected to the time-delay fiber 11, the other end of the time-delay fiber 11 is connected to the 2*1 fiber optic combiner 12, and then sequentially connected to the photodetector 13 and the data acquisition unit 14.

[0082] The 1* N Fiber beam splitter 9 splits the quasi-continuous emission laser corresponding to each channel block into multiple beams. N bundle, each entering N One detection channel.

[0083] The circulator 10 allows the laser to enter through the first port and exit through the second port to the fiber optic ultrasonic detection array 8. After the sound pressure acts on the fiber optic ultrasonic detection array 8, the detection light is then input through the second port of the circulator 10 and output through the third port to the delay fiber 11.

[0084] The delay fiber 11 is composed of single-mode fiber of a custom length. N The probe light from each probe channel will pass through different numbers of delay fiber segments. For CH_ N , will go through N -1 segment of delayed fiber, CH_ N -1 will pass through N -2 segments of time-delay fiber, and so on up to CH_1 which does not pass through time-delay fiber. It is easy to see that there is a constant transmission time difference between the probe light signals of adjacent channels. This time difference is the transmission time of the probe light in a segment of time-delay fiber, thus making... N The channel probe optical signals are separated in the time domain and collected sequentially according to the length of the transmission path. Therefore,N The channel probe light is simultaneously detected by the fiber optic ultrasonic probe array 8. N Each fiber optic ultrasonic detector element 17-3 receives and transmits signals, and there is no problem of aliasing of the detector light signals, thus achieving the purpose of parallel demodulation.

[0085] The 2*1 fiber optic combiner 12 combines two beams of light into a single output beam, and is used in conjunction with the delay fiber 11. (And 1*) N Fiber optic beam splitter, delay fiber, N Compared to the delay method of *1 fiber optic combiner, this 1* N The configuration of fiber optic bundle splitters, time-delay fibers, and multiple 2*1 fiber combiners reduces the amount of time-delay fiber used from ( N -1)* N / 2 reduced to N -1, significantly reducing device power consumption. For the probe optical signal in CH_2, its transmission path includes the exclusive path of the probe optical signal in CH_1; for the probe optical signal in CH_3, its transmission path includes the exclusive paths of the probe optical signals in CH_2 and CH_1, and so on. N The probe optical signal in the middle contains CH_ in its transmission path. N -1、CH_ N -2, ..., CH_1 are dedicated paths for probe optical signals. Therefore, this delay configuration architecture breaks the traditional parallel architecture's independent transmission mode for each channel path. N The transmission of each detection optical signal via path sharing greatly improves the spatial reuse efficiency of system resources. The throughput of each detection channel on its exclusive path segment and the effective transmission rate of the detection optical signal are significantly improved, and the overall complexity of the system link is greatly reduced.

[0086] The photodetector 13 receives a single-channel probe optical signal sequence input from the 2*1 fiber combiner 12, the sequence containing N A detection light signal carrying ultrasonic information. Compared to the traditional parallel architecture... N Channel detection optical signal and N Compared to the mode where each photodetector 13 is connected and transmitted in a one-to-one correspondence, the number of photodetectors 13 used is reduced from... N Reducing the number of components from one to one optimizes device maintainability while saving system costs.

[0087] The data acquisition unit 14 receives the converted electrical signal input from the single photodetector 13, facilitating subsequent data processing. This is in contrast to the common features found in multi-channel parallel demodulation systems. NThe channel data acquisition device uses a single-channel data acquisition device to achieve multi-channel data input, thus increasing the number of channels of the data acquisition device 14 from... N The number of systems has been reduced to one, lowering the system setup cost.

[0088] To further explain, the algorithm execution and imaging module includes a terminal controller 15 and an image display 16. One end of the terminal controller 15 is connected to the data acquisition unit 14, and the other end is connected to the image display 16.

[0089] The terminal controller 15 analyzes and processes the detection information stored by the data acquisition unit 14, and visualizes the effective detection signal of the target 6 under test by means of the ultrasonic imaging algorithm with high-intelligence calibration based on sound velocity inversion.

[0090] The image display 16 displays the synthesized real ultrasound image, providing intuitive feedback on the imaging results.

[0091] More specifically, the operating principle of the wavelength division-time division high-capacity simplified parallel demodulation system is as follows:

[0092] (1) The multi-wavelength emission light source outputs multiple single-wavelength quasi-continuous emission lasers, which are then modulated by the corresponding channel block modulators to form pulsed light output. The signal generator synchronously controls all channel block modulators, ultrasonic transmitters, and data acquisition devices.

[0093] (2) The pulsed laser, modulated by each channel block, passes through 1* N Fiber optic beam splitters enter respectively N Each detection channel, equipped with a circulator, transmits laser light to the fiber optic ultrasonic detection array, and... N Each fiber optic ultrasonic detection array element corresponds one-to-one;

[0094] (3) After the ultrasonic or photoacoustic signal emitted by the ultrasonic transmitter acts on the target to be tested, it acts on the ultrasonic sensing structure of the fiber optic ultrasonic detection array by transmission or reflection, forming a detection optical signal modulated by sound pressure and outputting it through the circulator.

[0095] (4) With the combined action of the delay fiber and the 2*1 fiber combiner, and by leveraging the basic principles of time-division multiplexing and the delay method of shared path, N The channel probe optical signal can be distinguished in the time domain, forming a signal sequence according to the length of the transmission path, returning to a single photodetector, and being collected by a single-channel data acquisition unit;

[0096] (5) Carry NAfter the single beam of light from the channel probe signal is converted by photoelectric conversion, the data is analyzed and processed by the terminal controller to extract the signal that can correctly feed back the information of the target under test. Then, the shape of the target under test is reconstructed through image synthesis, and the final two-dimensional or three-dimensional image is presented on the image display.

[0097] More specifically, the 1* N The selection criteria for fiber optic bundle splitter 9 and 2*1 fiber optic bundle combiner 12 are as follows:

[0098] In any channel block, 1* N The number of beams split by the fiber beam splitter 9 is the same as the number of elements in the fiber ultrasonic detection array 8, and the splitting ratio is the same, ensuring that the laser is uniformly distributed. N One detection channel. The coupling ratio of the 2*1 fiber combiner 12 is selected based on the power difference between the two incident beams. It is necessary to ensure that the difference in power (i.e., the power distribution) between the two incident beams after passing through the two arms of the combiner is minimized, as well as the power loss before and after coupling is minimized, thereby maintaining the stability and balance of the system. Assume that the powers of the two incident beams are respectively... P 1. P 2. The coupling ratio of the fiber optic combiner is i : k The selection of the actual coupling ratio involves the following formula:

[0099] (1)

[0100] (2)

[0101] (3)

[0102] (4)

[0103] in, i , k These are the coupling ratio coefficients of the first and second coupling arms of the fiber combiner, respectively. Z ＋ Represent the set of positive integers, as shown in equation (1). S This represents a condition that the sum of two positive integers is 100. i , k The set of all . P 1. P 2. The optical power of the two incident beams respectively. P 1· i / 100 represents the first incident light beam. P 1. Power distribution after the first arm of the fiber combiner P 2. k / 100 indicates the second incident light beam P2. The power distribution after passing through the second arm of the fiber combiner is as shown in equation (2), Δ P ( i,k ) is the coupling ratio after i : k The absolute value of the difference in power distribution between the two beams after they are combined by the fiber combiner. As shown in equation (3), S 1 is S A subset of represents the set of coupling ratios that minimize the difference in power distribution between two beams. i 1, k 1) Represents a set S Any combination of coupling ratios in the equation. As shown in equation (4), when the optimization objective is satisfied... i , k When the values ​​are not unique, a secondary optimization is performed, selecting the solution with the smallest absolute value of the difference in coupling ratios. i* , k* As the coupling ratio of a practical fiber optic combiner, it avoids excessive contribution from a single coupling arm and improves the stability of the optical power after combining.

[0104] More specifically, the length of the delay fiber 11 is selected based on the following criteria:

[0105] The length of the delay fiber determines the transmission delay of the detection signal in each channel. t 1. The specific value depends on it and the pulse width of the rectangular pulse sequence modulated by the modulator. t 0. Time from the emission of ultrasonic or photoacoustic signals to the acquisition of detection signals t The relationship between 2 involves the following formula:

[0106] (5)

[0107] (6)

[0108] (7)

[0109] (8)

[0110] in, RF The pulse emission repetition frequency is... DC The high-level duty cycle is as shown in equation (5). t 0 indicates the modulation pulse width. d f Let c be the length of each delay fiber segment, and c be the speed of light, typically taken as 3 × 10⁻⁶. 8 m / s, as shown in equation (6), t 1 represents the transmission delay caused by each segment of delay fiber. l 1 represents the vertical distance between the fiber optic ultrasonic detection array and the target under test. l2 represents the vertical distance between the ultrasonic transmitter and the target being measured. d s v represents the thickness of the target to be measured. w The speed at which ultrasound travels through water is typically taken as 1500 m / s. v s The speed at which ultrasonic waves travel through the target is related to the material, as shown in equation (7). t 2 represents the time from transmission to reception of the ultrasonic or photoacoustic signal. Considering the differences in the transmission paths of sound waves and light waves in the four imaging methods of transmission ultrasound, reflection ultrasound, transmission photoacoustics, and reflection photoacoustic imaging, the signal transmission and reception times are listed in Equation (7) in turn. Equation (8) represents the basic relationship that needs to be considered when selecting the length of the delay fiber, and the modulation pulse width... t 0 cannot be too small, otherwise the returned detection signal will not be collected; t The value of 0 cannot be too large, otherwise it would violate the fundamental requirements of the Nyquist sampling theorem. Furthermore, the transmission delay introduced by the transmission fiber... t 1. The value cannot be too small, otherwise the multi-channel detection signals will alias, making it impossible to distinguish them in the time domain; t 1. At the same time, the length should not be too large, otherwise it will lead to more power loss, reduce imaging depth, and waste configuration resources. Therefore, it is necessary to weigh various factors and reasonably set the optimal length of the delay fiber to ensure that multi-channel detection signals are accurately distinguished while saving configuration resources and system space as much as possible.

[0111] More specifically, the theoretical capacity influencing factors of the fiber optic ultrasonic detection array 8 are as follows:

[0112] For single-channel blocks N Channel fiber ultrasonic detection array consists of N It consists of fiber optic ultrasonic detection array elements with identical structures and consistent operating wavelengths, and the number of reused elements is [number missing]. N The number of and the final system output power entering the photodetector P out Minimum detectable power supported by the photodetector P min The relevant formula is:

[0113] (9)

[0114] (10)

[0115] in, P CH_1 , P CH_2 The optical power of the two incident beams before entering the 2*1 fiber combiner connecting CH_1 and CH_2 is not specified. i* CH_1、 k * CH_2 represents the coupling ratio of the selected 2*1 fiber combiner connecting CH_1 and CH_2, calculated as follows: P CH_1 · i * CH_1 / 100 represents the distributed power after passing through the first arm of the fiber combiner, calculated as follows: P CH_2 · k * CH_2 / 100 represents the distributed power after passing through the second arm of the fiber combiner. I i* CH_1k* CH_2 The insertion loss of the fiber combiner with the selected coupling ratio is given by equation (9). P out This indicates that the final output power of the system after the delay must satisfy the condition shown in equation (10), i.e. P out Greater than the minimum detectable power of the photodetector P min Therefore, when N Channel detection light signal passes through N -1 segment of delayed optical fiber and N - After one 2*1 coupler, the final output power to a single photodetector P out Meeting the above requirements proves that the channel block supports accommodating a certain number of reuses. N The fiber optic ultrasonic detection array. The total number of multiplexed fiber optic ultrasonic detection arrays in the system is the sum of the number of multiplexed channels. In actual system construction, factors such as the RF drive power allocation of the signal generator and the impedance matching between the signal generator and the modulators of each channel also need to be considered.

[0116] Combination Figure 2 The technical solution adopted in this invention is a splicing and clamping flexible reconfigurable array structure. It includes a detachable assembly clamping structure 17.

[0117] like Figure 2 As shown in (a) and (b), the detachable assembly clamping structure 17 serves to encapsulate, fix, and protect the fiber optic ultrasonic detection array 8. It includes: a slot-type hollow mold 17-1, an adhesive filling area 17-2, fiber optic ultrasonic detection array elements 17-3, and an assembly and fixing fixture.

[0118] The slotted hollow mold 17-1 has a cylindrical through hole in the center for independently encapsulating the fiber optic ultrasonic detection array element 17-3; and concave and convex slots around the perimeter for overall fixing of the fiber optic ultrasonic detection array 8.

[0119] The adhesive filling section 17-2 is used to bond the fiber optic ultrasonic detection array element 17-3 and the slot-type hollow mold 17-1. The adhesive is preferably a liquid adhesive with good waterproof properties and strong flowability.

[0120] The fiber optic ultrasonic detector array element 17-3, as the object to be packaged, is independently packaged in the slot-type hollow mold 17-1, and the amount of protrusion exposed from the mold is kept as consistent as possible during the sealing process. If there are slight differences, the flatness of the arrangement of the multiple fiber optic ultrasonic detector array elements 17-3 can be further optimized by changing the relative positions of adjacent slot-type hollow molds 17-1.

[0121] To further explain, the assembly and fixing fixture includes a connecting stud 17-4, a fixing link 17-5, an adjusting knob a 17-6, a hinge link 17-7, an adjusting knob b 17-8, a scissor link 17-9, an adjusting knob c 17-10, and a swing gripper 17-11.

[0122] The connecting stud 17-4, the fixed connecting rod 17-5, the hinge connecting rod 17-7, the scissor connecting rod 17-9, and the swing gripper 17-11 are connected in pairs.

[0123] The adjustment knobs a 17-6, b 17-8, and c 17-10 are used to adjust the connecting rod angle, extension / retraction amount, and plane rotation angle, so as to secure and fix the slot-type hollow mold 17-1.

[0124] Figure 2 Image (c) shows a three-dimensional schematic diagram of a slot-type hollow mold 17-1 containing the independently packaged fiber optic ultrasonic detector element 17-3. N Taking a 25-fiber ultrasonic detection array as an example, such as Figure 2 As shown in (d) and (e), the fiber optic ultrasonic detection array can be arranged in various detection forms, such as 5×5×5×5×5 or 1×3×5×7×5×3×1, realizing multi-dimensional high integration from point array, linear array to area array. It can be assembled into a detection layout that is conducive to scanning according to the needs of the detection scenario or the characteristics of the target volume.

[0125] More specifically, the assembly method of the fiber optic ultrasonic detection array structure includes the following steps:

[0126] S1. The fiber optic ultrasonic detector elements are sequentially bonded to their respective slot-type hollow molds using adhesive, and the process is performed under a microscope to ensure that the length of the fiber extending out of the mold is consistent.

[0127] S2. Attach the fiber optic ultrasonic detection array elements. NIndependent slotted hollow molds are spliced ​​together to form a scanning array with arbitrary arrangement, such as a linear or planar array. The slots are then pushed forward to further adjust the relative positions of the fiber optic ultrasonic detector array elements to ensure the flatness of the scanning arrangement of the fiber optic ultrasonic detector array elements.

[0128] S3. Connect the connecting stud to the fixed link by means of threaded connection, connect the fixed link to the hinge link by means of pin connection, connect the hinge link to the scissor link by means of hinge connection, and connect the scissor link to the swing gripper by means of pin connection.

[0129] S4. Rotate adjustment knob a to adjust the included angle between the hinge links to an angle that matches the packaged array volume in the horizontal direction. Rotate adjustment knob b to adjust the extension and retraction of the scissor link to a length that matches the packaged array volume in the vertical direction. Rotate adjustment knob c to adjust the plane rotation angle of the swing jaw to ensure a tight fit with the packaged fiber optic ultrasonic detection array.

[0130] Combination Figure 3 The technical solution adopted in this invention is a high-intelligence ultrasonic imaging algorithm based on sound velocity inversion. It includes the following operational flow:

[0131] S1. Based on material properties and taking defect detection as an example, the ultrasonic transmission speeds under various conditions such as healthy, corroded, porous, cracked, and inclusion-laden conditions are defined and denoted as follows: g 1. g 2、…、 g last To more closely approximate reality, tiny, random perturbations can be added to the defined speed of sound. This is achieved by changing the number, location, size, and combination of defects, and then randomly arranging them to fill the space. N A pre-created two-dimensional grid, as shown in equation (11), outputs a large number of independent real sound velocity distributions. g ( n true( )} N n =1.

[0132] (11)

[0133] in, = ( x , y ) represents a two-dimensional spatial coordinate vector. g true( () is defined in a two-dimensional mesh within the computational domain G The true sound speed distribution f fill (·) represents the geometric constraint filling function, Θ randomIt represents a set of parameters that control the random shape, location, size, etc. of defects.

[0134] S2. Ultrasonic waves exhibit scattering and reflection during actual transmission, leading to wavefront distortion and signal delay. To simplify the problem, as shown in equation (12), a scalar non-uniform wave equation is used to describe the acoustic pressure field. The actual sound velocity distribution obtained in S1 is then loaded into the numerical solver to simulate the propagation process of ultrasonic waves in a non-uniform medium, as shown in equation (13). The results are then calculated to obtain the distribution of each... g ( n true( The simulated sound pressure signal received by the corresponding fiber optic ultrasonic detection array element q ( n ) sim( t ).

[0135] (12)

[0136] (13)

[0137] in, q ( , t ) indicates spatial location ,time t The sound pressure field at that location. u ( , t () represents the excitation source function, used to simulate ultrasonic wave emission signals. q ( n ) sim( t ) represents the first fiber optic ultrasonic detection array n The sound pressure time series of each array element's location. n The value of is 1, 2, ... N .

[0138] S3. Using a fixed and uniform reference sound velocity value, the simulated sound pressure signal output from S2 is subjected to traditional SAFT algorithm for image synthesis. Since the sound velocity is set to a single sound velocity in a uniform medium, it does not match the actual non-uniform sound velocity distribution in the medium. Therefore, the output is a distorted ultrasound image with incorrect time delay propagation calculation. This distorted ultrasound image is then combined with the real sound velocity distribution to form a supervised learning training pair, and the training dataset is output. Ψ = {( h ( n distorted( ), g ( n true( ))} N n =1.

[0139] in, h ( n distorted( () represents a distorted ultrasound image synthesized at a fixed, uncalibrated sound velocity. It should be noted that the current training scheme is primarily targeted at specific material categories, but this training architecture has good scalability and can be used to construct a general training set by incorporating data from multiple material types, thereby enabling the inversion of sound velocity distributions for different materials.

[0140] S4. Construct a CS-UNet hybrid architecture deep learning correction network, which integrates a ConvNeXt backbone for extracting local features, a Swin Transformer encoder for capturing global changes, and a U-Net decoder for fusing multi-scale features and reconstructing images, as shown in Equations (14) and (15). By optimizing the composite loss function that combines mean square error loss and structural similarity loss, the network outputs an accurate predicted sound velocity distribution, thus completing the accurate mapping from distorted ultrasound images to the true sound velocity distribution.

[0141] (14)

[0142] (15)

[0143] in, j θ The parameters are θ The CS-UNet deep learning correction network model. pred( ( ) represents the predicted sound speed distribution output by the trained model. δ MSE , δ MAE , δ SSIN These are the mean squared error loss, mean absolute error loss, and structural similarity loss, respectively. The weighting coefficients of these three are adjusted accordingly. α , β , γ (The sum of the three is 1). The gradient is calculated using the backpropagation algorithm, and the composite loss function is minimized using optimizers such as Adam, AdaGrad, and L-BFGS to find the optimal network parameters. θ * This leads to the optimal training model, which outputs a predicted sound speed distribution that is closer to the true sound speed distribution.

[0144] S5. In a complete test, real ultrasonic signals are first acquired, and uncalibrated SAFT imaging is performed using the fixed sound velocity of ultrasonic waves propagating in a homogeneous medium in the target as the physical parameter to obtain a measured distorted ultrasonic image. This image is then input into the CS-UNet correction network trained in S4 to obtain the actual predicted sound velocity distribution of the real sound velocity distribution inside the target.

[0145] S6. Using the actual predicted sound velocity distribution from S5 as parameters, the SAFT algorithm after sound velocity calibration is executed for imaging. By eliminating defocus and distortion caused by sound velocity errors, a high-quality, distortion-free calibrated ultrasound image is finally output.

[0146] According to some embodiments of the present invention, Figure 4 This is a transmission imaging result diagram of a fiber optic ultrasonic probe array according to an embodiment of the present invention. Taking a four-element fiber optic ultrasonic probe array as an example, the imaging function of the system is verified and compared with the results of single-point ultrasonic imaging.

[0147] In one embodiment of the present invention, the four-element fiber optic ultrasonic imaging system uses a fiber optic beam splitter to achieve a uniform splitting ratio of 1×4. The system is configured with three equidistant delay fibers and three different 2*1 fiber couplers with varying coupling ratios. Compared to a traditional four-element demodulation system, the amount of delay fiber used is reduced by half, the number of photodetectors and data acquisition units is reduced to one-quarter of the original, and the imaging efficiency is increased fourfold. In this embodiment, the target under test is a standard single-sided tin-plated universal board with uniformly distributed disk-shaped vias. To construct clear acoustic contrast features, a raised pattern in the shape of a capital letter "H" is prepared on the surface of the board using solder, with increased solder usage at the four corners of the pattern. A two-dimensional scan of a 15 mm × 15 mm area is performed in the XY plane using a transmission ultrasonic imaging mode.

[0148] like Figure 4 In (a), the imaging results of the four-element fiber ultrasonic detection array are presented as normalized grayscale images, with the brightness of the colors reflecting the signal strength. Testing showed that the outline of the "H"-shaped pattern was clearly reproduced, and according to the actual fabrication process of "non-tin through-hole - low-tin solid hole - high-tin solid hole," it exhibited three imaging layering states: "strong signal - medium signal - weak signal." This indicates that the system has the ability to identify and reproduce the morphology of the target under test. Taking the results of this embodiment as an example, this invention can be used in fields such as circuit board defect detection and health monitoring of new energy equipment.

[0149] Furthermore, single-point fiber optic ultrasound imaging was conducted as a control experiment. A single fiber optic ultrasound detector was used to perform ultrasound imaging on the same target with the same scan step size and detection area. The results are as follows: Figure 4As shown in (b) of the figure, the contrast of single-point imaging is significantly lower than that of array imaging, making it difficult to clearly reproduce the hole outline and accurately reflect the structural information of the target under test. Furthermore, the scanning time is four times that of a four-element fiber ultrasonic detection array. This result confirms that the present invention achieves a dual improvement in imaging efficiency and quality.

[0150] The technical features of the embodiments described above can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. It should be noted that the terms "in one embodiment," "for example," and "again" in this invention are intended to illustrate the invention and are not intended to limit the invention.

[0151] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A parallel demodulation and intelligent imaging system based on reconfigurable fibered ultrasound probe array, characterized in that, include: The laser emission and modulation module is used to provide continuous emission light sources of different wavelengths for each channel block and modulate them into pulsed laser output; An ultrasonic emission and detection module is used to provide an ultrasonic or photoacoustic signal emission source and to detect ultrasonic or photoacoustic signals through a fiber optic ultrasonic detection array. The ultrasonic or photoacoustic signals act on the fiber optic ultrasonic detection array elements to form multi-channel detection optical signals. The fiber optic ultrasonic detection array is a splicing clamping array structure, including multiple detachable assembly clamping structures (17) arranged in the fiber optic ultrasonic detection array. Each detachable assembly clamping structure (17) includes a slot-type hollow mold (17-1), an adhesive filling area (17-2), a fiber optic ultrasonic detection array element (17-3), and an assembly fixing fixture, which are used to independently encapsulate the fiber optic ultrasonic detection array element (17-3) and assemble it into an adjustable fiber optic ultrasonic detection array according to the detection arrangement requirements. The parallel acquisition and processing module is used for signal acquisition and data processing of multi-channel probe optical signals; The parallel acquisition and processing module includes: 1* N Fiber beam splitter (9) is used to uniformly split the pulsed laser from each channel block into N Beam output; circulator (10), each circulator (10) includes a first port, a second port and a third port, the third... m The first channel block n The pulsed laser input to the first n The first port of the circulator (10) leads to the second port. The detection light signal carrying the target information enters the circulator (10) through the second port and is output from the third port. The delay fiber (11) is used to extend the transmission path of each detection light signal. The 2*1 fiber combiner (12) is connected to the delay fiber (11). m The first channel block n After a delay, the path detection optical signal is compared with the first... n -1 channel probe optical signal beam is output, with each channel block connected in series; among which... M The number of channel blocks, m =1, 2, ..., M , n =1, 2, ..., N ; photodetector (13), used to convert the detection light signal into an electrical signal output; data acquisition unit (14), used to convert the analog electrical signal into a digital electrical signal; The algorithm execution and imaging module is used to perform image reconstruction on the target under test and display the results; the image reconstruction of the target under test includes: During the training phase, standard sound velocity values ​​under different states are defined and randomly filled into a two-dimensional simulation grid based on the inherent properties of the target under test, generating a real sound velocity distribution containing spatially varying sound velocity values. The physical propagation of ultrasound in a non-uniform medium is simulated to obtain the simulated sound pressure signal received by the fiber optic ultrasonic detection array. The traditional synthetic aperture focusing algorithm SAFT with a fixed uniform sound velocity is used to output distorted ultrasound images, which are then paired with the real sound velocity distribution to form a supervised learning training pair. The training dataset is input into the CS-UNet deep learning correction network to achieve the inversion mapping from distorted ultrasound images to the real sound velocity distribution, and output the predicted sound velocity distribution. In the application phase, the measured distorted ultrasound image is obtained by using SAFT reconstruction without sound velocity calibration, and then input into the trained CS-UNet correction network to obtain the actual predicted sound velocity distribution; the prediction result is substituted into the sound velocity calibrated SAFT reconstruction algorithm to output a distortion-free calibrated ultrasound image. During operation, the pulsed laser from each channel block is transmitted to the ultrasonic emission and detection module. N A fiber optic ultrasonic detection array element; after the ultrasonic or photoacoustic signal is transmitted or reflected by the target, it forms... N The channel probe optical signal, after undergoing delays of varying durations and beam combining in the parallel acquisition and processing module, forms a time domain image. N A sequence of probe optical signals; for N Data analysis and algorithm processing are performed on the sequence of probe light signals to obtain a reconstructed image of the target.

2. The parallel demodulation and intelligent imaging system based on a reconfigurable fiber optic ultrasonic detection array according to claim 1, characterized in that, The laser emission and modulation module includes: A multi-wavelength emission light source (1) is used to output continuous light of different wavelengths; Multiple channel block modulators are used to modulate continuous light of different wavelengths into pulsed laser outputs for each channel block; The signal generator (4) is used to control all channel block modulators, set pulse laser parameters, and synchronously trigger laser emission, ultrasonic emission, and signal acquisition.

3. The parallel demodulation and intelligent imaging system based on a reconfigurable fiber optic ultrasonic detection array according to claim 1, characterized in that, The ultrasonic emission and detection module includes: An ultrasonic transmitter (5) is used to transmit ultrasonic or photoacoustic signals; The fiber optic ultrasonic detection array (8) is used to detect ultrasonic or photoacoustic signals carrying information about the target to be tested. The ultrasonic information is fed back by the difference in the properties of the detection optical signals in the fiber before and after the sound pressure action, forming a multi-channel detection optical signal.

4. The parallel demodulation and intelligent imaging system based on a reconfigurable fiber optic ultrasonic detection array according to claim 1, characterized in that, The algorithm execution and imaging module includes: Terminal controller (15) for data analysis and image processing; An image display (16) is used to present a two-dimensional or three-dimensional reconstructed image of the target (6) under test.

5. The parallel demodulation and intelligent imaging system based on a reconfigurable fiber optic ultrasonic detection array according to claim 1, characterized in that, The assembly and fixing fixture includes: The connecting stud (17-4) provides horizontal support; the fixed connecting rod (17-5) provides vertical support; the hinged connecting rod (17-7) has a fixed length and an adjustable angle; the scissor connecting rod (17-9) has a fixed rotation angle and an adjustable length, which can be adjusted to accommodate the volume of the clamp by changing the extension amount; the swinging jaw (17-11) has a fixed jaw length and an adjustable plane rotation angle, which can be adjusted to accommodate the volume of the clamp by changing the rotation angle; adjusting knobs a (17-6), b (17-8), and c (17-10) are used to control the angle between the hinged connecting rods (17-7), the extension length of the scissor connecting rod (17-9), and the plane rotation angle of the swinging jaw (17-11), respectively.

6. The parallel demodulation and intelligent imaging system based on a reconfigurable fiber optic ultrasonic detection array according to claim 5, characterized in that, The assembly method of the fiber optic ultrasonic detection array (8) includes the following steps: Inject waterproofing agent into the adhesive filling area (17-2) to fix the fiber optic ultrasonic detector array element (17-3) into the slot-type hollow mold (17-1), ensuring consistent elongation. Connect the individually packaged fiber optic ultrasonic detector array elements through the slots, arranging them into an array of arbitrary detection forms. Adjust the relative positions of the fiber optic ultrasonic detector array elements by pushing the slots to ensure the detection end faces are flat. Connect the connecting studs (17-4), fixing rods (17-5), hinged rods (17-7), scissor rods (17-9), and swing grippers (17-11) sequentially. Rotate adjustment knob a (17-6) to adjust the angle between the hinged rods (17-7) to ensure the horizontal direction matches the array volume. Rotate adjustment knob b (17-8) to adjust the extension length of the scissor rods (17-9) to ensure the vertical direction matches the array volume. Rotate adjustment knob c... (17-10) Adjust the plane rotation angle of the swing gripper (17-11) to ensure tight clamping with the array.

Images