A transducer electrical pulse response measurement and correction method, system and apparatus

Abstract

The application discloses a kind of transducer electric pulse response measurement and correction method, system and equipment, it is related to photoacoustic imaging technical field, including: using transducer acquisition microsphere generated photoacoustic signal;The i th element of transducer and the imaging region to be reconstructed are respectively divided using uniform grid, the spatial impulse response of the i th element at microsphere position is calculated;Using spatial impulse response and Fourier transform of photoacoustic signal, the electric pulse response of the i th element is calculated, to build the correction matrix of the i th element, the average correction matrix is obtained by summing and averaging the correction matrix of all elements;When imaging to any object, the photoacoustic signal to be deconvoluted collected by each element is multiplied by the average correction matrix to obtain the recovered photoacoustic signal;The response correction method, system and equipment, the electric pulse response of transducer is more accurately measured, deconvolution in signal domain is carried out and image is reconstructed, to a certain extent, improve image quality.

Description

Technical Field

[0001] The present invention relates to the technical field of photoacoustic imaging, and in particular to a method, system and device for measuring and correcting a transducer electrical pulse response. Background Art

[0002] Photoacoustic imaging is an emerging biomedical imaging technology that combines the advantages of rich optical contrast with high ultrasonic resolution. It holds broad promise and plays an irreplaceable role in the biomedical field. Photoacoustic computed tomography (PACT) is one of the primary implementations of PAT. Its reconstruction algorithm is primarily based on an ideal detector (a point-like detector with full field of view and infinite bandwidth). However, due to limitations in manufacturing processes, cost, and imaging space, practical detectors struggle to meet this requirement, resulting in distortion of the detected PAT signal and, consequently, the reconstructed PAT image.

[0003] Piezoelectric ultrasonic transducers are commonly used photoacoustic signal detectors, and their limited operating bandwidth is the main cause of photoacoustic signal distortion. The operating bandwidth of a transducer is usually described by an amplitude-frequency response curve, a Gaussian-like curve in the frequency domain that reflects the transducer's sensitivity to detecting different frequency components of the signal. When an ideal pulse signal is received by a limited-bandwidth transducer, the actual detected waveform will be distorted due to the loss of some high- and low-frequency information. This distorted waveform is called the electrical pulse response of the transducer. The process of a signal being received by the transducer can be viewed as the multiplication of the signal's spectrum and the amplitude-frequency response curve. Since the spectrum of an ideal pulse signal is a constant, the spectrum of the electrical pulse response can well characterize the shape of the transducer's amplitude-frequency response curve.

[0004] The current machinery industry standard, "General Technical Requirements for Ultrasonic Phased Array Probes (JB / T 11731-2013)," uses the pulse-echo method to measure transducer bandwidth. For large-aperture, multi-element arrays commonly used in photoacoustic imaging, measuring each element individually is time-consuming and difficult to align the reflector with individual elements.

[0005] After obtaining the bandwidth information of the transducer, deconvolution can be performed on this basis to restore the distorted image. In photoacoustic tomography, the image restoration method can be performed in the image domain or the signal domain. In the field of image processing, the process of image blurring can be described as the convolution of a clear image with a point spread function and the superposition of noise, and the inverse process is image domain deconvolution. In actual operation, objects with a size smaller than the system resolution are usually imaged, and this image is used as the point spread function of the system. However, the frequency distribution of the photoacoustic signals emitted by objects of different sizes is different, and the degree to which they are affected by the system bandwidth is also different. For some large-sized objects where only edge information remains in the imaging result due to low-frequency loss, image domain deconvolution cannot restore their original images.

[0006] Because bandwidth-limited photoacoustic image distortion is essentially due to distortion of the signal received by the transducer, signal-domain deconvolution first restores the photoacoustic signal based on the transducer's amplitude-frequency response, and then uses this restored signal to reconstruct the image. While signal-domain deconvolution is effective for any imaging scenario, the results are highly dependent on the accuracy of the amplitude-frequency response measurement. Summary of the Invention

[0007] Based on the technical problems existing in the background technology, the present invention proposes a method, system and equipment for measuring and correcting the electrical pulse response of a transducer. After accurately measuring the electrical pulse response of the transducer, deconvolution of the signal domain is performed and the image is reconstructed, which can improve the image quality to a certain extent.

[0008] The present invention proposes a method for measuring and correcting the electrical pulse response of a transducer, comprising:

[0009] Step 1: using a transducer to collect the photoacoustic signal generated by the microspheres;

[0010] Step 2: Check the transducer The array elements and the imaging area to be reconstructed are divided into uniform grids to calculate the The spatial impulse response of the array element at the microsphere position; using the spatial impulse response and the Fourier transform of the photoacoustic signal, calculate the The electrical pulse response of each array element is used to construct the The correction matrix of each array element is summed and averaged to obtain the average correction matrix;

[0011] Step 3: When imaging any object, the photoacoustic signals to be deconvolved collected by each array element are multiplied by the average correction matrix to perform signal domain deconvolution to obtain the restored photoacoustic signal.

[0012] Furthermore, the transducer The array elements and the imaging area to be reconstructed are divided into uniform grids to calculate the The spatial impulse response of an array element at the position of the microsphere is:

[0013] Use N discrete uniform grids to characterize the transducer array element;

[0014] Discretize the imaging area to be reconstructed into M grids;

[0015] Calculate the The spatial impulse response of each grid in the array element is The spatial impulse responses of N grids in the array elements are summed to obtain the The spatial impulse response of an array element.

[0016] Further, the spatial impulse response and the Fourier transform of the photoacoustic signal are used to calculate the The electrical pulse response of each array element is:

[0017] The convolution operation in the time domain is equivalent to the multiplication operation in the frequency domain. The spatial impulse response of an array element expression:

[0018] ;

[0019] in, is the inverse Fourier transform, is the Fourier transform, For the The spatial impulse response of the array elements is For transducer The photoacoustic signal collected by the array elements is is the theoretical photoacoustic signal of the microsphere, which is regarded as an ideal pulse signal in calculation.

[0020] Furthermore, the receiving process of the photoacoustic signal to be deconvolved is expressed as a convolution process;

[0021] Then each array element corresponds to the restored photoacoustic signal Transformed into a least squares problem:

[0022] ;

[0023] in, is the matrix of electrical pulse responses, is the photoacoustic signal to be deconvolved, is the identity matrix, is an adjustable regularization parameter, Represents the square of the L2 norm.

[0024] Furthermore, each array element corresponds to the restored photoacoustic signal The correction results are as follows:

[0025] ;

[0026] in, for The transpose of for The transpose of is the correction matrix.

[0027] Furthermore, the photoacoustic signal generated by the microspheres is collected by using a transducer, specifically:

[0028] Place the microsphere at the geometric center of the transducer's imaging area, and continuously collect and save Q photoacoustic signals;

[0029] The Q photoacoustic signals collected are summed and averaged, and then denoised to obtain the Photoacoustic signal of an array element .

[0030] A transducer electrical pulse response measurement and correction system includes an acquisition module, an impulse response calculation module, and a signal recovery module;

[0031] The acquisition module uses a transducer to collect the photoacoustic signal generated by the microspheres;

[0032] The impulse response calculation module is used to calculate the The array elements and the imaging area to be reconstructed are divided into uniform grids to calculate the The spatial impulse response of the array element at the microsphere position; using the spatial impulse response and the Fourier transform of the photoacoustic signal, calculate the The electrical pulse response of each array element is used to construct the The correction matrix of each array element is summed and averaged to obtain the average correction matrix;

[0033] In the signal restoration module, when imaging any object, the photoacoustic signals to be deconvolved collected by each array element are multiplied by the average correction matrix to perform signal domain deconvolution to obtain the restored photoacoustic signal.

[0034] Furthermore, in the signal restoration module, the receiving process of the photoacoustic signal to be deconvolved is expressed as a convolution process;

[0035] Then each array element corresponds to the restored photoacoustic signal Transformed into a least squares problem:

[0036]

[0037] in, is the matrix of electrical pulse responses, is the photoacoustic signal to be deconvolved, is the identity matrix, is an adjustable regularization parameter, Represents the square of the L2 norm.

[0038] Each array element corresponds to the restored photoacoustic signal The correction results are as follows:

[0039] ;

[0040] in, for The transpose of for The transpose of is the correction matrix.

[0041] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the correction method described above when executing the computer program.

[0042] The advantages of the transducer electrical pulse response measurement and correction method, system, and device provided by the present invention are that, for various types of ultrasonic transducers with a large number of densely packed array elements commonly used in photoacoustic imaging systems, the microspheres of this embodiment are used as signal sources to quickly and accurately obtain the electrical pulse responses of all array elements. This embodiment, based on the classic Tychonoff regularized deconvolution, proposes an average correction matrix method to assist in noise suppression, avoiding the weakening of photoacoustic signal recovery due to excessively large regularization term parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a schematic diagram of the process of the present invention;

[0044] Figure 2 A schematic diagram of the flow of the electric pulse response correction method and the existing direct reconstruction method;

[0045] Figure 3 Schematic diagram for modeling and characterizing spatial impulse response;

[0046] Figure 4 Schematic diagram of the measured electrical pulse response curve, where the black solid line represents the average value of each array element, and the gray area represents the fluctuation range of the measurement difference between array elements.

[0047] Figure 5 Schematic diagram of the amplitude-frequency response curve, where the black solid line represents the average value of each array element, and the gray area represents the fluctuation range of the measurement difference between array elements;

[0048] Figure 6 Comparison of human finger cross-section images reconstructed before and after photoacoustic signal recovery. Figure 6 (a) is the result of directly acquiring the signal and reconstructing it; Figure 6 (b) is the result of signal correction and reconstruction when the regularization parameter is 0; Figure 6 (c) shows the result of signal correction and reconstruction when the regularization parameter is set to 0.6; Figure 6 (d) is the result of signal correction and reconstruction using the average correction matrix method proposed in this embodiment. DETAILED DESCRIPTION

[0049] The technical solutions of the present invention are described in detail below through specific embodiments. Numerous specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0050] like Figures 1 to 6 As shown, the present invention proposes a method for measuring and correcting the electrical pulse response of a transducer, comprising:

[0051] Step 1: using a transducer to collect the photoacoustic signal generated by the microspheres;

[0052] Step 2: Check the transducer The array elements and the imaging area to be reconstructed are divided into uniform grids to calculate the The spatial impulse response of the array element at the microsphere position; using the spatial impulse response and the Fourier transform of the photoacoustic signal, calculate the The electrical pulse response of each array element is used to construct the The correction matrix of each array element is summed and averaged to obtain the average correction matrix;

[0053] Step 3: When imaging any object, the photoacoustic signals to be deconvolved collected by each array element are multiplied by the average correction matrix to perform signal domain deconvolution to obtain the restored photoacoustic signal.

[0054] This embodiment targets various types of ultrasonic transducers with a large number of densely packed elements, commonly used in photoacoustic imaging systems. It uses the microspheres of this embodiment as signal sources to quickly and accurately obtain the electrical pulse responses of all elements. Building on the classic Tychonoff regularized deconvolution, this embodiment proposes an average correction matrix approach to assist in noise suppression, avoiding overly large regularization parameters that weaken the photoacoustic signal recovery effect.

[0055] In this embodiment, step 1, using a transducer to collect the photoacoustic signal generated by the microspheres, is specifically as follows:

[0056] (a1) Preparation of microsphere phantoms as photoacoustic sources;

[0057] First, a 3% (by weight) solution of purified agar powder is prepared and heated. Once dissolved, it is poured into a cylindrical mold. Next, under a stereomicroscope, a black polystyrene ball (approximately 40 micrometers in diameter) is picked up with a needle and placed in the center of the agar solution, gently pressing with the needle until it is submerged. After the agar solution is allowed to solidify, the microsphere phantom is complete.

[0058] (a2) Collecting the photoacoustic signal of the microspheres, such as Figure 4 and5 As shown;

[0059] In order to ensure the signal-to-noise ratio, the single laser pulse energy used in the experiment is about 60 millijoules. First, place the microsphere phantom at the geometric center of the imaging area of ​​the transducer, then illuminate the microsphere with a near-infrared light pulse and observe the collected signal. Since the transducer in this embodiment uses focused array elements, in order to maximize the intensity of the collected signal, the stepper motor is operated to move the transducer so that the microsphere is as coplanar as possible with the focus of each array element. At this time, the maximum signal peak can be observed. After the signal stabilizes, continuously collect Q (for example, 200 times, the specific number of collections can be set as needed) signals and save them. After summing and averaging the Q continuously collected photoacoustic signals and denoising, the first signal is obtained. Photoacoustic signal of an array element .

[0060] This embodiment uses microspheres as signal sources to quickly and accurately obtain the electrical pulse responses of all array elements.

[0061] In one embodiment, step 2: the transducer The array elements and the imaging area to be reconstructed are divided into uniform grids to calculate the The spatial impulse response of the array element at the microsphere position; using the spatial impulse response and the Fourier transform of the photoacoustic signal, calculate the The electrical pulse response of each array element is used to construct the The correction matrix of the array elements is:

[0062] The calculation process of the spatial impulse response is as follows:

[0063] Analyzing the process from photoacoustic signal generation to reception, we can obtain:

[0064] ; (1)

[0065] in, is the theoretical photoacoustic signal of the microsphere, For the The electrical pulse response of each array element, For the The spatial impulse response of an array element at the position of the microsphere is represented by the symbol “ " represents a convolution operation. For example, in simulations, the originally N-shaped signal is broadened to varying degrees by the electrical impulse response (EIR) and spatial impulse response (SIR), causing distortion, which further affects the photoacoustic imaging results.

[0066] Because the microsphere used in the experiment is sufficiently small, it can be approximated as a spherical sound source with a uniform initial sound pressure distribution. Analytical solutions are described in numerous publications, such as Diebold, Gerald J. and T. Sun. "PROPERTIES OF PHOTOACOUSTIC WAVES IN ONE, TWO, AND THREE DIMENSIONS." Acustica 80 (1994): 339-351, and will not be repeated here. Furthermore, in this example, since the center frequency of the transducer used is approximately 5 MHz, the spectrum of the 40-micron microsphere near 5 MHz is sufficiently flat, so it can be directly treated as an ideal pulse signal for processing. The spatial impulse response (SIR) refers to the response of an array element of a certain size to an ideal pulse signal and is related to the array element's geometry and the location of the signal source.

[0067] In this example, the spatial impulse response (SIR) of each array element is obtained by simulation in Matlab software using the array element size provided by the transducer manufacturer. That is, N discrete uniform grids are used to represent the transducer's first array elements; discretize the imaging area to be reconstructed into M grids; calculate the The spatial impulse response of each grid in the array element is The spatial impulse responses of N grids in the array elements are summed to obtain the The spatial impulse response of an array element.

[0068] It should be noted that , M, N are rounded up, is the element index of the transducer, and its value depends on the number of elements of the specific transducer. For example, if a focused annular array transducer with 512 elements is used to receive the photoacoustic signal, then , or if a transducer with 128 elements is used, then , or other numerical array element transducers.

[0069] M is the number of grid cells after the imaging area is discretized in the computer. The value of M can be 1,000, 10,000, 100,000, 1 million, 10 million, or even more. As long as computer memory allows, the larger the M setting, the finer the grid and the better the simulation effect. For example, if the imaging area is an 80 mm square area, and is discretized into a series of 0.5 mm square grids, the value of M is 25600. Alternatively, imaging areas of other sizes can be divided into grids of different side lengths. It is also understood that for the same imaging area, the value of M will also be different when using grids of different sizes.

[0070] N is the number of grid cells after the shape of a single array element is discretized in the computer. N can be 1,000, 10,000, 100,000, 1 million, 10 million, or even more. Similarly, as computer memory permits, a larger N setting results in a finer grid and better simulation results. For example, if an array element 14 mm high and 0.39 mm wide is discretized into a series of square grids with sides of 10 microns, the value of N is 54,600. Alternatively, for array elements of other sizes, grids of different side lengths can be used. It is also understood that the value of N will also vary when the same array element is divided using grids of different sizes.

[0071] Specifically, the modeling of a single array element is as follows: Figure 3 As shown, in the simulation A discrete uniform grid represents a cylindrical focusing array element with a height of 14 mm, a width of 0.39 mm, and a focal length of 36 mm. Then, the imaging area of ​​interest of any size is discretized into M grids. Since the spatial impulse response SIR is related to the relative position of the signal source and the array element, a total of M SIRs need to be calculated in this scenario for subsequent use. Specifically, The spatial impulse response of the array elements in the mth grid in the imaging area It can be expressed as:

[0072] ; (2)

[0073] in, Indicates the The first array element Received at discrete grids, , from the The pulse signal excited at each grid, . No. The response of each array element to this pulse signal is expressed as the sum of the signals received by each discrete grid.

[0074] The calculation process of the electric pulse response is as follows:

[0075] The convolution operation in the time domain is equivalent to the multiplication operation in the frequency domain. The spatial impulse response of an array element expression:

[0076] ; (3)

[0077] in, is the inverse Fourier transform, is the Fourier transform, For the The spatial impulse response of the array elements is For transducer The photoacoustic signal collected by the array elements is is the theoretical photoacoustic signal of the microsphere.

[0078] The electric pulse response is calculated in the above manner, taking into account the SIR effect related to the microsphere position, and the result is closer to the real electric pulse response.

[0079] In this embodiment, a correction matrix for each array element is obtained through steps one to three. The correction matrices of all array elements are summed and averaged to obtain an average correction matrix. This can be used to correct and restore photoacoustic signals collected under a limited bandwidth. That is, the average correction matrix is ​​used to deconvolve the photoacoustic signals to be deconvolved collected by each array element, thereby restoring the photoacoustic signal.

[0080] In one embodiment, in step 3, when imaging an arbitrary object, the photoacoustic signals to be deconvolved collected by each array element are multiplied by the average correction matrix to perform signal domain deconvolution to obtain a restored photoacoustic signal, specifically:

[0081] Photoacoustic signals affected by electrical pulse responses collected experimentally The receiving process (i.e. the photoacoustic signal to be deconvolved) can also be expressed as a convolution process:

[0082] ; (4)

[0083] in, Represents the signal not affected by the electric pulse response, that is, the expected signal correction result. is the electrical pulse response, is the matrix of electrical pulse responses.

[0084] The convolution operation with the electrical impulse response EIR can be written as matrix multiplication, and EIR is denoted by length A vector of This vector represents the elements, we can get the expression of the matrix H composed of the electric pulse response:

[0085] ; (5)

[0086] Then at this time The solution can be transformed into a least squares problem:

[0087] ; (6)

[0088] in, is the identity matrix, is an adjustable regularization parameter, Represents the square of the L2 norm.

[0089] The first term on the right side of the equation To preserve the fidelity, a regularization term is added to optimize the correction result, taking into account that in some cases the correction result will amplify the noise. Through further calculation, the correction result of the signal of a certain array element can be expressed as:

[0090] ; (7)

[0091] in, for The transpose of for The transpose of is the correction matrix.

[0092] The above method is used to correct and restore the photoacoustic signal. is the weight of the regularization term. The fidelity term amplifies the high- and low-frequency information in the photoacoustic signal. In environments with poor signal-to-noise ratios, this can over-amplify the high- and low-frequency noise in the signal. The regularization term can be understood as the energy spectrum of the restored signal. In the least squares framework, increasing the regularization term weight suppresses the energy of the restored signal, thereby suppressing the gain to the noise.

[0093] This example uses a focused annular array transducer with 512 elements, with a diameter of 80 mm, to receive photoacoustic signals. During the experiment, near-infrared light pulses emitted by a tunable laser system illuminated the experimental sample to stimulate the photoacoustic signal. The signal was collected using a signal acquisition system (Verasonics system), and then image reconstruction was performed using a filtered back-projection algorithm. This example captured photoacoustic signals from a leaf vein phantom and a human finger cross-section. Without electrical pulse response correction, the imaging quality of the thicker trunk of the leaf vein was poor, as shown in the following example. Figure 2 As shown in (a), this is mainly due to the limited bandwidth of the transducer, which causes the original signal to lose some low-frequency information. After the correction method of this embodiment, the imaging quality of the thicker trunk part of the leaf vein is better, and the image quality is obtained. Figure 2 as shown in (b).

[0094] like Figure 4 The electrical pulse response measured in the example is shown, and the corresponding photoacoustic signal intensity value is used to calculate the correction matrix. Figure 5 As shown in the figure, the signal spectrum after Fourier transform of the electric pulse response, and its amplitude intensity distribution indicates the bandwidth of the array element. It can be seen that the response to the signal near 5MHz is the strongest, while the response to the low-frequency signal deviating from 5MHz is relatively low.

[0095] Figure 5 yes Figure 4The Fourier transform results of the data in the embodiment essentially describe the bandwidth characteristics of the transducer. The measurement results of this embodiment are relatively accurate, so the effect of signal correction based on this is relatively obvious.

[0096] For finger cross-sectional imaging, the loss of low-frequency information causes some relatively large vein cross-sections to appear hollow, such as Figure 6 As shown in (a). When the regularization parameter in formula (6) When set to 0, the low and high frequencies of the signal can be restored with maximum gain, but at the same time, high frequency noise will be amplified and additional artifacts will be introduced, such as Figure 6 By increasing the regularization coefficient , reducing the weight of the fidelity term in the least squares problem of formula (6) can suppress noise amplification, but also weaken the gain of the effective signal frequency band, such as Figure 6 (c) shows that the center of the vein section above the finger section is brighter. Figure 6 (b) has decreased.

[0097] Considering that the array elements of the transducer are designed and produced according to the same standard, the electrical pulse responses between the elements are not very different. The correction matrices of each element can be summed and averaged. In this way, the random noise carried by the correction matrix can be further eliminated, while the similar bandwidth gain information between the elements can still be retained. The final reconstruction effect is as follows: Figure 6 As shown in (d), the noise is removed while the maximum preservation is achieved. Figure 6 (b) shows the restoration effect.

[0098] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A method for measuring and correcting the electrical pulse response of a transducer, characterized in that: include: Step 1: using a transducer to collect the photoacoustic signal generated by the microspheres; Step 2: Check the transducer The array elements and the imaging area to be reconstructed are divided into uniform grids to calculate the The spatial impulse response of each array element at the microsphere position; Using the spatial impulse response and the Fourier transform of the photoacoustic signal, the convolution operation in the time domain is equivalent to the multiplication operation in the frequency domain, and the first The electrical pulse response of each array element is used to construct the The correction matrix of each array element is summed and averaged to obtain the average correction matrix; No. The electrical pulse response of an array element expression: ； in, is the inverse Fourier transform, is the Fourier transform, For the The spatial impulse response of the array elements is For transducer The photoacoustic signal collected by the array elements is is the theoretical photoacoustic signal of the microsphere, which is regarded as an ideal pulse signal in the calculation; Step 3: When imaging any object, the photoacoustic signals to be deconvolved collected by each array element are multiplied by the average correction matrix to perform signal domain deconvolution to obtain the restored photoacoustic signal.

2. The method for measuring and correcting the electrical pulse response of a transducer according to claim 1, wherein: The transducer The array elements and the imaging area to be reconstructed are divided into uniform grids to calculate the The spatial impulse response of an array element at the position of the microsphere is: Use N discrete uniform grids to characterize the transducer array element; Discretize the imaging area to be reconstructed into M grids; Calculate the The spatial impulse response of each grid in the array element is The spatial impulse responses of N grids in the array elements are summed to obtain the The spatial impulse response of an array element.

3. The method for measuring and correcting the electrical pulse response of a transducer according to claim 1, wherein: In step 3, the receiving process of the photoacoustic signal to be deconvolved is expressed as a convolution process; Then each array element corresponds to the restored photoacoustic signal Transformed into a least squares problem: ； in, is the matrix of electrical pulse responses, is the photoacoustic signal to be deconvolved, is the identity matrix, is an adjustable regularization parameter, Represents the square of the L2 norm.

4. The method for measuring and correcting the electrical pulse response of a transducer according to claim 3, wherein: Each array element corresponds to the restored photoacoustic signal The correction results are as follows: ； in, for The transpose of for The transpose of is the correction matrix.

5. The method for measuring and correcting the electrical pulse response of a transducer according to claim 1, wherein: The photoacoustic signal generated by the microspheres is collected by using a transducer, specifically: Place the microsphere at the geometric center of the transducer's imaging area, and continuously collect and save Q photoacoustic signals; The Q photoacoustic signals collected are summed and averaged, and then denoised to obtain the Photoacoustic signal of an array element .

6. A transducer electrical pulse response measurement and correction system, characterized in that: It includes an acquisition module, an impulse response calculation module and a signal restoration module; The acquisition module uses a transducer to collect the photoacoustic signal generated by the microspheres; The impulse response calculation module is used to calculate the The array elements and the imaging area to be reconstructed are divided into uniform grids to calculate the The spatial impulse response of each array element at the microsphere position; Using the spatial impulse response and the Fourier transform of the photoacoustic signal, the convolution operation in the time domain is equivalent to the multiplication operation in the frequency domain, and the first The electrical pulse response of each array element is used to construct the The correction matrix of each array element is summed and averaged to obtain the average correction matrix; In the signal restoration module, when imaging any object, the photoacoustic signals to be deconvolved collected by each array element are multiplied by the average correction matrix to perform signal domain deconvolution to obtain the restored photoacoustic signal; Among them, The electrical pulse response of an array element expression: ； in, is the inverse Fourier transform, is the Fourier transform, For the The spatial impulse response of the array elements is For transducer The photoacoustic signal collected by the array elements is is the theoretical photoacoustic signal of the microsphere, which is regarded as an ideal pulse signal in calculation.

7. The transducer electrical pulse response measurement and correction system according to claim 6, characterized in that: In the signal restoration module, the receiving process of the photoacoustic signal to be deconvolved is expressed as a convolution process; Then each array element corresponds to the restored photoacoustic signal Transformed into a least squares problem: in, is the matrix of electrical pulse responses, is the photoacoustic signal to be deconvolved, is the identity matrix, is an adjustable regularization parameter, Represents the square of the L2 norm.

8. The transducer electrical pulse response measurement and correction system according to claim 7, characterized in that: Each array element corresponds to the restored photoacoustic signal The correction results are as follows: ； in, for The transpose of for The transpose of is the correction matrix.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the correction method according to any one of claims 1 to 5 is implemented.

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