Method, device and program product for a magnetization-free design of an ultrasound transducer compatible with an optical pumping magnetometer

Abstract

The application provides a magnetization-free design method, device and program product of an ultrasonic transducer compatible with an optical pumping magnetometer, the method comprising: performing magnetic cleanliness screening on the ultrasonic transducer, and identifying high residual magnetic components and low residual magnetic components in the ultrasonic transducer; replacing the high residual magnetic components with low residual magnetic components; applying a demagnetization process to the low residual magnetic components; and using the optical pumping magnetometer to perform magnetic cleanliness evaluation on the processed ultrasonic transducer, and determining whether the residual magnetic field is lower than a magnetic field threshold. The method realizes reduction of the residual magnetic field of the ultrasonic transducer, and further realizes compatibility of ultrasonic / optoacoustic imaging and an OPM-MEG system.

Description

Technical Field

[0001] This application relates to the field of medical device technology, and more specifically, to a non-magnetic design method, device, and program product for an ultrasonic transducer compatible with an optical pump magnetometer. Background Technology

[0002] Ultrasound imaging, especially photoacoustic imaging (PAI), is considered a structural imaging modality with high potential for spatial and system-level compatibility with OPM-MEG systems due to its ability to provide tissue structure and functional information. Traditional ultrasound transducers are primarily designed for magnetic resonance imaging (MRI) compatibility, also known as "device-environment compatibility." These MRI-compatible ultrasound transducers typically allow for residual magnetic fields at the microtesla (μT) level, with their design goals primarily focused on ensuring device safety and avoiding imaging artifacts in strong static magnetic field environments.

[0003] However, when traditional ultrasound transducers attempt to integrate with OPM-MEG systems, there is a problem of magnetic interference magnitude mismatch. That is, the brain nerve magnetic signals that the OPM-MEG system needs to detect are in the nanotesla (nT) to picotesla (pT) range, while the residual magnetic field of traditional MRI-Compatible ultrasound transducers usually reaches the microtesla (μT) range. The difference between the two is 3 to 6 orders of magnitude. This huge magnetic interference is enough to completely overwhelm the target biological magnetic signal.

[0004] In other words, it is not yet possible to reduce the residual magnetic field of the ultrasonic transducer to achieve compatibility between ultrasonic / photoacoustic imaging and the OPM-MEG system. Summary of the Invention

[0005] The purpose of this application is to provide a non-magnetic design method, device, and program product for an ultrasonic transducer compatible with an optically pumped magnetometer, so as to reduce the residual magnetic field of the ultrasonic transducer and thus achieve compatibility between ultrasonic / photoacoustic imaging and the OPM-MEG system.

[0006] In a first aspect, this application provides a non-magnetized design method for an ultrasonic transducer compatible with an optical pump magnetometer, comprising: performing magnetic cleanliness screening on the ultrasonic transducer and identifying high remanent magnetization components and low remanent magnetization components in the ultrasonic transducer; replacing the high remanent magnetization components with low remanent magnetization components; applying a demagnetization process to the low remanent magnetization components; and using the optical pump magnetometer to evaluate the magnetic cleanliness of the treated ultrasonic transducer and determine whether the residual magnetic field is lower than a magnetic field threshold.

[0007] The aforementioned non-magnetized design method for ultrasonic transducers compatible with optically pumped magnetometers reduces the residual magnetic field of ultrasonic transducers by up to three orders of magnitude through screening, replacement, demagnetization, and evaluation processes. This improves the compatibility of equipment and signals in the OPM-MEG system and ultimately enhances magnetic cleanliness.

[0008] In conjunction with the first aspect, optionally, the step of performing magnetic cleanliness screening on the ultrasonic transducer and identifying high-remanence and low-remanence components in the ultrasonic transducer includes: in a shielded room, controlling the distance between the component under test in the ultrasonic transducer and the sensor of the optical pump magnetometer to not exceed a distance threshold; measuring the DC remanence and AC magnetic noise of the component under test; and determining that the component under test is a high-remanence component when the DC remanence is greater than the measured remanence threshold or the AC magnetic noise has a noise peak within a specified frequency range.

[0009] The aforementioned non-magnetic design method for ultrasonic transducers compatible with optically pumped magnetometers establishes a high-precision magnetic source identification system through control of the test distance and a dual-parameter determination mechanism. This improves the accuracy of identifying magnetic interference sources.

[0010] In conjunction with the first aspect, optionally, the step of using the optically pumped magnetometer to assess the magnetic cleanliness of the treated ultrasonic transducer and determine whether the residual magnetic field is below a magnetic field threshold includes: in a shielded room, controlling the distance between the treated components in the ultrasonic transducer and the sensor of the optically pumped magnetometer to not exceed a distance threshold; measuring the DC remanent magnetization of the treated components; and determining whether the DC remanent magnetization is below an assessment remanent magnetization threshold.

[0011] The aforementioned non-magnetized design method for ultrasonic transducers compatible with optically pumped magnetometers also establishes a reliable magnetic cleanliness verification system, providing a clearer standard for judging whether ultrasonic transducers achieve OPM compatibility.

[0012] In conjunction with the first aspect, optionally, after controlling the distance between the processed components in the ultrasonic transducer and the sensor of the optical pump magnetometer to not exceed a distance threshold in the shielded room, the step of using the optical pump magnetometer to evaluate the magnetic cleanliness of the processed ultrasonic transducer and determine whether the residual magnetic field is lower than the magnetic field threshold further includes: measuring the AC magnetic noise of the processed components; and determining whether the AC magnetic noise has a noise peak within a specified frequency range.

[0013] The aforementioned non-magnetized design method for ultrasonic transducers compatible with optically pumped magnetometers, by adding AC magnetic noise assessment, can more comprehensively detect the magnetic compatibility of the transducer under dynamic operating conditions, avoid the impact of AC interference on ultrasensitive magnetic measurements, and ensure that OPM compatibility requirements are met in both DC and AC dimensions.

[0014] In conjunction with the first aspect, optionally, after applying the demagnetizing process to the low remanent magnetization component, the method further includes: verifying the electroacoustic performance of the treated ultrasonic transducer; wherein the electroacoustic performance parameters include at least one of center frequency, relative bandwidth, and sensitivity.

[0015] The aforementioned non-magnetized design method for ultrasonic transducers compatible with optically pumped magnetometers, through verification of electroacoustic performance, ensures that the improvement in magnetic cleanliness does not sacrifice acoustic performance, achieving synergistic optimization of magnetic and electrical properties. This ensures the integrity of the core functions of the ultrasonic transducer.

[0016] In conjunction with the first aspect, optionally, the step of verifying the electroacoustic performance of the processed ultrasonic transducer includes: calculating the electrical performance using an electrical performance formula; wherein the electrical performance formula is: ; In the formula, f c The center frequency is represented by BW, the relative bandwidth by S, and the sensitivity by f. l and f u These are the lower cutoff frequency and upper cutoff frequency, respectively, at -6dB. i The output voltage V is the excitation voltage amplitude. o Defined as the echo voltage amplitude, where L is the test distance.

[0017] The aforementioned non-magnetized design method for ultrasonic transducers compatible with optically pumped magnetometers further improves the accuracy and comparability of performance evaluation by calculating electroacoustic parameters using standardized formulas. It also ensures that the improvement in magnetic cleanliness does not come at the expense of acoustic performance.

[0018] In conjunction with the first aspect, optionally, the ultrasonic transducer has multiple channels; before calculating the electrical performance using the electrical performance formula, the electroacoustic performance verification of the processed ultrasonic transducer includes: extracting the envelope of the original echo signal of each channel; wherein the formula for calculating the envelope is: ; In the formula, t represents time, x c (t) represents the original echo signal, e c (t) represents the envelope, and H represents the Hilbert transform; the original echo signal of each channel is shifted and compensated using the median of the envelope of each channel as the reference time point so that the main peak of the envelope is aligned with the reference time point.

[0019] The aforementioned non-magnetic design method for ultrasonic transducers compatible with optically pumped magnetometers effectively eliminates the impact of geometric errors on performance evaluation through multi-channel signal processing, envelope extraction, and time alignment, ultimately further improving the accuracy of evaluation and verification.

[0020] In conjunction with the first aspect, optionally, before performing magnetic cleanliness screening on the ultrasonic transducer and identifying high-remanence and low-remanence components in the ultrasonic transducer, the method further includes: applying a plurality of calibration magnetic fields of known strength to the optical pump magnetometer; fitting the response curve output by the optical pump magnetometer using a magnetic strength calculation formula; wherein, the magnetic strength calculation formula is: ; In the formula, R(f) is the effective value of the calibration magnetic field, which characterizes the relationship between the effective value of the signal and the frequency f. A and C are fitting parameters, f0 represents the center frequency, and BW represents the relative bandwidth. The optically pumped magnetometer is calibrated using the response curve.

[0021] The aforementioned non-magnetic design method for ultrasonic transducers compatible with optically pumped magnetometers ensures the accuracy of the measuring tools and the screening and evaluation results by first calibrating the OPM system, thus providing a more reliable benchmark for the entire magnetic cleanliness assessment.

[0022] Secondly, this application also provides a non-magnetic design device compatible with ultrasonic transducers and optically pumped magnetometers, comprising: The screening module is used to screen the ultrasonic transducer for magnetic cleanliness and identify high-remanence and low-remanence components in the ultrasonic transducer; the replacement module is used to replace the high-remanence components with low-remanence components; the demagnetizing module is used to apply a demagnetizing process to the low-remanence components; and the evaluation module is used to evaluate the magnetic cleanliness of the treated ultrasonic transducer using the optical pump magnetometer and determine whether the residual magnetic field is below the magnetic field threshold.

[0023] The aforementioned non-magnetic design device for ultrasonic transducers and optically pumped magnetometers has the same beneficial effects as the method for non-magnetic design devices for ultrasonic transducers and optically pumped magnetometers provided in the first aspect or any alternative embodiment of the first aspect, and will not be elaborated here.

[0024] Thirdly, this application also provides a program product, including a computer program / instructions that, when executed by a processor, implement the methods described above.

[0025] The above-described program product has the same beneficial effects as the ultrasonic transducer and optically pumped magnetometer compatible non-magnetic design device method provided by the first aspect or any alternative embodiment of the first aspect, which will not be elaborated here. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 A schematic diagram of a compatible demagnetized ultrasonic array system provided in the embodiments of this application; Figure 2 A first flowchart of a non-magnetic design method for an ultrasonic transducer compatible with an optically pumped magnetometer provided in an embodiment of this application; Figure 3 A detailed flowchart of step S120 in the non-magnetization design method for an ultrasonic transducer compatible with an optically pumped magnetometer provided in the embodiments of this application. Figure 4 A detailed flowchart of step S180 in the non-magnetization design method for an ultrasonic transducer compatible with an optically pumped magnetometer provided in the embodiments of this application. Figure 5 A second flowchart of a non-magnetic design method for an ultrasonic transducer compatible with an optically pumped magnetometer provided in an embodiment of this application; Figure 6 A detailed flowchart of step S170 in the non-magnetization design method for an ultrasonic transducer compatible with an optically pumped magnetometer provided in the embodiments of this application. Figure 7 A first functional block diagram of a non-magnetized design device compatible with an ultrasonic transducer and an optically pumped magnetometer provided in an embodiment of this application; Figure 8 This is a second functional block diagram of a non-magnetized design device compatible with an ultrasonic transducer and an optically pumped magnetometer, provided in an embodiment of this application.

[0028] Explanation of reference numerals in the attached figures: 10. Demagnetized ultrasonic array system; 1. Conveyor belt; 2. Magnetic shielding cavity; 3. Channel ultrasonic array; 4. Optical pump magnetometer. Detailed Implementation

[0029] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this application.

[0031] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0032] Please refer to Figure 1 , Figure 1 This is a schematic diagram of a compatible demagnetized ultrasonic array system provided in the embodiments of this application. For ease of understanding, the compatible demagnetized ultrasonic array system 10 will be described first.

[0033] The channel ultrasound array 3 can be a demagnetized 128-channel ultrasound array, which repeatedly enters and exits the magnetically shielded cavity 2 via the conveyor belt 1. At the same time, the optically pumped magnetometer 4 is located nearby to monitor the changes in the magnetic field caused by the channel ultrasound array 3.

[0034] Please refer to Figure 2 , Figure 2 This is a first flowchart of a non-magnetic design method for an ultrasonic transducer compatible with an optically pumped magnetometer, provided in this application embodiment. The non-magnetic design method for an ultrasonic transducer compatible with an optically pumped magnetometer provided in this application embodiment includes: Step S120: Perform magnetic cleanliness screening on the ultrasonic transducer and identify high-remanence and low-remanence components in the ultrasonic transducer.

[0035] In step S120 above, magnetic cleanliness screening refers to the residual magnetic field detection of various components of the ultrasonic transducer in a controlled environment using high-sensitivity magnetic field measurement tools such as optically pumped magnetometers, in order to distinguish between high-remanence and low-remanence components. Specifically, the screening process includes testing all critical components inside the transducer one by one, such as: piezoelectric chip, matching layer, backing material, shell, shielding layer, connector, circuit board, and solder.

[0036] Step S140: Replace the high remanence component with a low residual magnetism component.

[0037] In step S140 above, the replacement operation can be based on the screening results, replacing high-remanent-magnetic components, such as connectors, screws, and backing materials made of ferromagnetic or high-remanent-magnetic materials, with low-remanent-magnetic materials. Low-remanent-magnetic materials include, but are not limited to, phosphor bronze connectors, PEEK shells, polyurethane backing materials, and copper foil shielding layers, which can be used to replace traditional metal pins, metal shells, backing materials containing metal fillers, and ferromagnetic shielding layers, respectively. The replacement process typically requires attention to demagnetization processes, such as using silver solder for connections, to avoid introducing new magnetic sources.

[0038] Step S160: Apply a demagnetizing process to components with low residual magnetism.

[0039] In step S160 above, the demagnetization process targets metal components that have not been replaced after screening, such as solder or piezoelectric electrodes, by applying an alternating decaying magnetic field or thermal annealing to reduce their residual magnetization. Demagnetization parameters, such as magnetic field strength, frequency, and time, can be adjusted according to the component's material characteristics, ensuring that the component's electroacoustic performance is not damaged.

[0040] Step S180: Use an optically pumped magnetometer to assess the magnetic cleanliness of the treated ultrasonic transducer and determine whether the residual magnetic field is below the magnetic field threshold.

[0041] In step S180 above, the evaluation process can be carried out in a shielded room. The processed ultrasonic transducer is sent to the OPM sensor via an automatic sample delivery system to measure its DC remanence and AC magnetic noise. The magnetic field threshold can be set to the nanotesla level, for example, 1.5 nT.

[0042] Preferably, the "entry-exit" test can be repeated multiple times during the evaluation process to verify consistency. The evaluation is passed when the magnetic cleanliness is below the magnetic field threshold.

[0043] In the above process, the residual magnetic field of the ultrasonic transducer was reduced by up to three orders of magnitude through screening, replacement, demagnetization and evaluation, which improved the compatibility of equipment and signals in the OPM-MEG system and ultimately improved the magnetic cleanliness.

[0044] Please refer to Figure 3 , Figure 3 This is a flowchart illustrating step S120 in the non-magnetic design method for an ultrasonic transducer compatible with an optically pumped magnetometer provided in this application embodiment. In some optional embodiments, step S120 includes: Step S121: In the shielded room, control the distance between the component under test in the ultrasonic transducer and the sensor of the optically pumped magnetometer to not exceed the distance threshold.

[0045] In step S121 above, the distance threshold is typically set to within 1 centimeter (cm) to simulate the real-world working scenario of the OPM-MEG system. The shielded chamber can be constructed of three layers of permalloy with a shielding coefficient of not less than 100 dB to eliminate external magnetic field interference. The component under test (DUT) is fed into the OPM sensing area along a fixed trajectory using a non-magnetic automatic sample delivery system, such as a POM rack and PU belt, and stops at a designated position to ensure precise distance control. The distance setting is based on the sensitivity characteristics of the OPM; too small a distance may lead to mechanical collision risks, while too large a distance may reduce measurement sensitivity. 1 cm is usually an optimized value that balances safety and sensitivity.

[0046] Step S122: Measure the DC residual magnetism and AC magnetic noise of the component under test.

[0047] In step S122 above, the DC remanent magnetization is measured by the OPM (Optical Power Module) to measure the magnetic field offset introduced during static docking, with units of nanotesla (nT) or microtesla (μT). The AC magnetic noise is measured by acquiring time-series magnetic field data through the OPM and performing power spectral density analysis, with a focus on checking the noise level in the 1–100 Hz frequency band, which is the OPM's operating frequency band. Before measurement, the OPM typically needs to compensate for the residual static magnetic field in the shielded room using a compensation coil and complete phase alignment along the sensitive axis to ensure linear stability. DC remanent magnetization is expressed as peak-to-peak value or RMS value, and AC magnetic noise is expressed as noise spectral density (unit: T / √Hz).

[0048] Step S123: If the DC remanence is greater than the measurement remanence threshold or the AC magnetic noise has a noise peak within the specified frequency range, the component under test is determined to be a high remanence component.

[0049] In step S123 above, the remanence threshold can be set to 10 nT, and the specified frequency range can be 1–100 Hz. Specifically, the judgment logic can be as follows: if the DC remanence is ≥10 nT (e.g., reaching the μT level), or if the AC magnetic noise exhibits a distinguishable noise peak within the 1–100 Hz range (e.g., 7.8 fT / √Hz), and the noise spectral density is significantly higher than the OPM background noise, then the component can be judged as a high remanence component; otherwise, it is considered a low remanence component.

[0050] For example, the DC remanence of snap-fit ​​connectors and metal screws reaches the μT level, and therefore can still be judged as high remanence.

[0051] In the above implementation process, a high-precision magnetic source identification system was established by controlling the test distance and using a dual-parameter judgment mechanism. This improved the accuracy of identifying magnetic interference sources.

[0052] Please refer to Figure 4 , Figure 4This is a flowchart illustrating step S180 in the non-magnetization design method for an ultrasonic transducer compatible with an optically pumped magnetometer provided in this application embodiment. In some optional embodiments, step S180 includes: Step S181: In the shielded room, control the distance between the processed components in the ultrasonic transducer and the sensor of the optically pumped magnetometer to not exceed the distance threshold.

[0053] In step S181 above, the distance threshold can be set to 1cm, which can be achieved through an automatic sample delivery system.

[0054] Step S182: Measure the DC residual magnetism of the processed components.

[0055] In step S182 above, the DC residual magnetism measurement method can be the same as in step S122 above, except that the object measured in step S182 is the entire ultrasonic transducer.

[0056] Step S183: Determine whether the DC residual magnetism is below the evaluation residual magnetism threshold.

[0057] In step S183 above, for example, the remanence threshold is set to 1.5 nT. If the DC remanence is <1.5 nT, then it passes; otherwise, replacement or demagnetization is performed.

[0058] Similarly, in the above implementation process, a reliable magnetic cleanliness verification system was established, providing a clearer standard for judging whether an ultrasonic transducer has achieved OPM compatibility.

[0059] Please continue to refer to Figure 4 In some optional implementations, after step S181, step S180 further includes: Step S184: Measure the AC magnetic noise of the processed components.

[0060] In step S184 above, AC magnetic noise measurement can be performed by power spectral density analysis to check for abnormal peaks in the 1–100 Hz frequency band.

[0061] Step S185: Determine whether there are noise peaks in the AC magnetic noise within the specified frequency range.

[0062] In step S185 above, for example, if the noise spectral density is consistent with the OPM background noise and there are no significant peaks, the evaluation is passed.

[0063] In the above implementation process, by adding AC magnetic noise assessment, the magnetic compatibility of the transducer under dynamic operating conditions can be detected more comprehensively, avoiding the impact of AC interference on ultra-sensitive magnetic measurement, and ensuring that OPM compatibility requirements are met in both DC and AC dimensions.

[0064] Please refer to Figure 5 , Figure 5 This is a second flowchart of the non-magnetic design method for an ultrasonic transducer compatible with an optically pumped magnetometer provided in this application embodiment. In some optional embodiments, after step S160, the non-magnetic design method for an ultrasonic transducer compatible with an optically pumped magnetometer provided in this application embodiment further includes: Step S170: Verify the electroacoustic performance of the processed ultrasonic transducer.

[0065] In step S170 above, the electroacoustic performance parameters include at least one of center frequency, relative bandwidth, and sensitivity. Electroacoustic performance verification can be performed using the pulse-echo method, specifically by immersing the ultrasonic transducer in a water load, emitting a pulse signal with an excitation voltage of 100V, receiving the echo from a plane reflector, and acquiring the signal using an oscilloscope.

[0066] In the above implementation process, the verification of electroacoustic performance ensured that the improvement in magnetic cleanliness did not sacrifice acoustic performance, achieving synergistic optimization of magnetic and electrical properties. This ensured the integrity of the core functions of the ultrasonic transducer.

[0067] Please refer to Figure 6 , Figure 6 This is a flowchart illustrating step S170 in the non-magnetic design method for an ultrasonic transducer compatible with an optically pumped magnetometer provided in this application embodiment. In some optional embodiments, step S170 includes: Step S173: Calculate the electrical performance using the electrical performance formula.

[0068] In step S173 above, the frequency domain response can be obtained based on the Fast Fourier Transform (FFT). For example, extracting f from the echo signal... l and f u Calculate V o And BW. V o The half-peak to peak value can be retrieved. The electrical performance formula is: ; In the formula, f c The center frequency is represented by BW, the relative bandwidth by S, and the sensitivity by f. l and f u These are the lower cutoff frequency and upper cutoff frequency, respectively, at -6dB. i The output voltage V is the excitation voltage amplitude. o Defined as the echo voltage amplitude, where L is the test distance.

[0069] In the above implementation process, the electroacoustic parameters are calculated using standardized formulas, further improving the accuracy and comparability of performance evaluation. Furthermore, it ensures that the improvement in magnetic cleanliness does not come at the expense of acoustic performance.

[0070] Please continue to refer to Figure 6 In some alternative implementations, the ultrasonic transducer has multiple channels. For example, a 128-channel linear array ultrasonic transducer (model: DRS10L128-0.2×5-FPC-D1(D1-14)-nT, Guangzhou Dopule Electronic Technology Co., Ltd., China) has 128 channels.

[0071] Accordingly, before step S173, step S170 includes: Step S171: Extract the envelope of the original echo signal of each channel.

[0072] In step S171 above, envelope extraction is achieved through Hilbert transform, converting the oscillating signal into a smooth profile to facilitate the location of the main peak. This eliminates signal phase fluctuations and highlights amplitude information. The formula for calculating the envelope is: ; In the formula, t represents time, x c (t) represents the original echo signal, e c (t) represents the envelope, and H represents the Hilbert transform.

[0073] Step S172: Using the median of the envelope of each channel as the reference time point, perform translation compensation on the original echo signal of each channel so that the main peak of the envelope is aligned with the reference time point.

[0074] In step S172 above, the alignment operation resolves the time delay differences between channels caused by the non-parallelism of the probe and the reflector. The median of the main peak time of the envelope of all channels is calculated as a reference, and the signals of each channel are shifted to align the main peaks in the time domain. Edge samples generated during the alignment process are ignored in subsequent statistics.

[0075] In the above implementation process, multi-channel signal processing, through envelope extraction and time alignment, effectively eliminates the impact of geometric errors on performance evaluation, and ultimately further improves the accuracy of evaluation and verification.

[0076] Please continue to refer to Figure 5 In some optional implementations, prior to step S120, the non-magnetic design method for ultrasonic transducers compatible with optically pumped magnetometers provided in this application embodiment further includes: Step S111: Apply a calibration magnetic field of known strength to the optically pumped magnetometer.

[0077] In step S110 above, the calibration magnetic field can be generated by a function signal generator and a calibration coil, and the magnetic field strength can be 100 pT with an adjustable frequency range of 1–100 Hz.

[0078] Step S112: Fit the response curve output by the optically pumped magnetometer using the magnetic intensity calculation formula.

[0079] In step S112 above, the fitting process can measure the R(f) output of the OPM by changing the frequency f, and determine the center frequency and relative bandwidth using a nonlinear least squares fitting formula. The magnetic strength calculation formula is: ; In the formula, R(f) is the effective value of the calibration magnetic field signal, which characterizes the relationship between the effective value of the signal and the frequency f. A and C are fitting parameters, f0 represents the center frequency, and BW represents the relative bandwidth.

[0080] Step S113: Calibrate the optically pumped magnetometer using the response curve.

[0081] In step S113 above, the OPM can be verified to be operating in the linear interval by comparing the degree of agreement between the measured response and the theoretical model. For example, check whether R(f) is consistent with the theoretical model.

[0082] In the above process, the accuracy of the measuring tools and the screening and evaluation results were ensured by first calibrating the OPM system, thus providing a more reliable benchmark for the entire magnetic cleanliness assessment.

[0083] Please refer to Figure 7 , Figure 7 This is a first functional block diagram of the non-magnetic design device 600 compatible with ultrasonic transducers and optically pumped magnetometers provided in this application embodiment. Based on the same concept, this application embodiment provides a non-magnetic design device 600 compatible with ultrasonic transducers and optically pumped magnetometers, comprising: The screening module 610 is used to perform magnetic cleanliness screening on the ultrasonic transducer and identify high remanence and low remanence components in the ultrasonic transducer. Replacement module 620, used to replace the high remanent magnetization component with a low residual magnetization component; Demagnetizing module 630 is used to apply a demagnetizing process to the low residual magnetism component; Evaluation module 640 is used to evaluate the magnetic cleanliness of the processed ultrasonic transducer using the optically pumped magnetometer and to determine whether the residual magnetic field is below the magnetic field threshold.

[0084] Please continue to refer to Figure 7As an optional implementation, during the process of screening the magnetic cleanliness of the ultrasonic transducer and identifying high-remanence and low-remanence components in the ultrasonic transducer, the screening module 610 is specifically used to: in a shielded room, control the distance between the component under test in the ultrasonic transducer and the sensor of the optical pump magnetometer to not exceed a distance threshold; measure the DC remanence and AC magnetic noise of the component under test; and determine that the component under test is a high-remanence component when the DC remanence is greater than the measured remanence threshold or the AC magnetic noise has a noise peak within a specified frequency range.

[0085] Please continue to refer to Figure 7 As an optional implementation, in the process of using the optically pumped magnetometer to evaluate the magnetic cleanliness of the treated ultrasonic transducer and determine whether the residual magnetic field is lower than the magnetic field threshold, the evaluation module 640 is specifically used to: in a shielded room, control the distance between the treated components in the ultrasonic transducer and the sensor of the optically pumped magnetometer to not exceed a distance threshold; measure the DC remanent magnetization of the treated components; and determine whether the DC remanent magnetization is lower than the evaluation remanent magnetization threshold.

[0086] Please continue to refer to Figure 7 As an optional implementation, in the process of using the optical pump magnetometer to evaluate the magnetic cleanliness of the treated ultrasonic transducer and determine whether the residual magnetic field is lower than the magnetic field threshold, the evaluation module 640 is further used to: measure the AC magnetic noise of the treated components; and determine whether the AC magnetic noise has a noise peak within a specified frequency range.

[0087] Please refer to Figure 8 , Figure 8 This is a second functional block diagram of the demagnetization design device 600 compatible with an ultrasonic transducer and an optically pumped magnetometer provided in this application embodiment. As an optional implementation, the demagnetization design device 600 compatible with an ultrasonic transducer and an optically pumped magnetometer provided in this application embodiment further includes a verification module 650. After applying a demagnetization process to the low-remanence component, the verification module 650 is used to: verify the electroacoustic performance of the processed ultrasonic transducer; wherein the electroacoustic performance parameters include at least one of center frequency, relative bandwidth, and sensitivity.

[0088] Please continue to refer to Figure 8 As an optional implementation, during the electroacoustic performance verification of the processed ultrasonic transducer, the verification module 650 is specifically used to: calculate the electrical performance using an electrical performance formula; wherein the electrical performance formula is: ; In the formula, f cThe center frequency is represented by BW, the relative bandwidth by S, and the sensitivity by f. l and f u These are the lower cutoff frequency and upper cutoff frequency, respectively, at -6dB. i The output voltage V is the excitation voltage amplitude. o Defined as the echo voltage amplitude, where L is the test distance.

[0089] Please continue to refer to Figure 8 As an optional implementation, the ultrasonic transducer has multiple channels; Accordingly, during the electroacoustic performance verification of the processed ultrasonic transducer, the verification module 650 is further configured to: extract the envelope of the original echo signal of each channel; wherein the formula for calculating the envelope is: ; In the formula, t represents time, x c (t) represents the original echo signal, e c (t) represents the envelope, and H represents the Hilbert transform; Using the median of the envelope of each channel as a reference time point, the original echo signal of each channel is shifted and compensated so that the main peak of the envelope is aligned with the reference time point.

[0090] Please continue to refer to Figure 8 As an optional implementation, the non-magnetized design device 600 compatible with ultrasonic transducers and optically pumped magnetometers provided in this application embodiment further includes a calibration module 660. Before performing magnetic cleanliness screening on the ultrasonic transducer and identifying high-remanence and low-remanence components in the ultrasonic transducer, the calibration module 660 is used to: apply a calibration magnetic field of known intensity to the optically pumped magnetometer; and fit the response curve output by the optically pumped magnetometer using a magnetic strength calculation formula; wherein, the magnetic strength calculation formula is: ; In the formula, R(f) is the effective value of the calibration magnetic field, which characterizes the relationship between the effective value of the signal and the frequency f, A and C are fitting parameters respectively, f0 represents the center frequency, and BW represents the relative bandwidth; The optically pumped magnetometer was calibrated using the response curve.

[0091] It should be understood that this device corresponds to the above-described embodiment of the non-magnetic design method compatible with ultrasonic transducers and optically pumped magnetometers, and is capable of performing the various steps involved in the above-described method embodiments. The specific functions of this device can be found in the description above, and detailed descriptions are omitted here to avoid repetition. The device includes at least one software functional module that can be stored in memory or embedded in the device's operating system (OS) in the form of software or firmware.

[0092] Based on the same concept, this embodiment provides a program product. Specifically, the program product is a computer program product, including a computer program or instructions. When the computer program or instructions are executed by a processor, they can implement the methods described in any embodiment of this application.

[0093] The computer program product may be embodied on one or more computer-readable media. The computer-readable media may be, but is not limited to, volatile memory (such as random access memory RAM), non-volatile memory (such as read-only memory ROM, programmable read-only memory PROM, erasable programmable read-only memory EPROM, electrically erasable programmable read-only memory EEPROM, flash memory), magnetic storage devices (such as hard disk drives, magnetic tapes), optical storage devices (such as optical disc CD-ROM, digital versatile optical disc DVD), or any suitable combination of the above.

[0094] Specifically, the computer program or instructions may be stored in the computer-readable medium. When the computer-readable medium containing the computer program or instructions is loaded onto an electronic device with processing capabilities, the processor of the electronic device is able to read and execute the computer program or instructions. The processor's execution of the instructions causes the electronic device to perform the method steps described in the embodiments of this application.

[0095] Those skilled in the art will understand that the computer program product can exist in various forms, including but not limited to: Standalone packaged software: Software packages that are stored on physical media (such as CDs, USB flash drives, and memory cards) and sold or distributed independently.

[0096] Pre-installed software: Firmware or part of the system / application software that has been pre-programmed or installed in the device's memory (such as ROM, Flash) at the factory.

[0097] Network distribution: Software installation packages, update packages, or applications downloaded or streamed from servers, app stores (such as Apple App Store, Google Play), software repositories, etc. via the Internet, mobile networks, etc.

[0098] Embedded software: As part of the control system of specialized equipment (such as medical imaging equipment, industrial testing equipment), it is stored in the internal memory of the device.

[0099] Cloud Service / SaaS: Deployed in a cloud computing environment, users remotely access and invoke the program's functions through client software, web browsers, or application programming interfaces (APIs) (i.e., the "Software as a Service" model). In this case, the program's execution occurs on a cloud server, but the instructions themselves and the core logic for implementing their functions still fall under the category of the computer program product.

[0100] License key / activation code: A digital key separate from the main program but used to unlock or activate the program to enable the functions of the method, and is considered part of or an accessory to the product.

[0101] Regardless of the specific form in which the computer program product is provided or distributed, as long as the computer program or instructions contained therein can implement the methods described in the embodiments of this application when executed by a processor, they fall within the protection scope of the computer program product described in this embodiment.

[0102] The computer program product in this embodiment can be used to cause an electronic device with processing capabilities to perform the steps in the various methods provided in the embodiments of this application.

[0103] The controller can be a microprocessor (MCU), a digital signal processor (DSP), or a programmable logic device (FPGA).

[0104] It should be understood that the disclosed apparatus and methods can also be implemented in other ways, given the several embodiments provided in this application. The apparatus embodiments described above are merely illustrative. For example, the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of apparatus, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code, which contains one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, or they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0105] In addition, the functional modules in the various embodiments of this application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0106] The above description is only an optional implementation of the embodiments of this application, but the protection scope of the embodiments of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the embodiments of this application should be covered within the protection scope of the embodiments of this application.

Claims

1. A non-magnetic design method for an ultrasonic transducer compatible with an optically pumped magnetometer, characterized in that, include: The ultrasonic transducer was subjected to magnetic cleanliness screening, and high-remanence and low-remanence components in the ultrasonic transducer were identified. Replace the high remanence component with a low residual magnetism component; A demagnetizing process is applied to the low remanent magnetization component; and The magnetic cleanliness of the treated ultrasonic transducer was assessed using the optically pumped magnetometer, and it was determined whether the residual magnetic field was below the magnetic field threshold.

2. The method according to claim 1, characterized in that, The step of performing magnetic cleanliness screening on the ultrasonic transducer and identifying high-remanence and low-remanence components in the ultrasonic transducer includes: In the shielded room, the distance between the component under test in the ultrasonic transducer and the sensor of the optically pumped magnetometer is controlled to not exceed a distance threshold. Measure the DC remanence and AC magnetic noise of the component under test; and If the DC residual magnetism is greater than the measured residual magnetism threshold or the AC magnetic noise has a noise peak within a specified frequency range, the component under test is determined to be a high residual magnetism component.

3. The method according to claim 1, characterized in that, The step of using the optically pumped magnetometer to assess the magnetic cleanliness of the treated ultrasonic transducer and determine whether the residual magnetic field is below the magnetic field threshold includes: In the shielded room, the distance between the processed components in the ultrasonic transducer and the sensor of the optically pumped magnetometer is controlled to not exceed a distance threshold. Measure the DC remanence of the processed components; and Determine whether the DC residual magnetism is below the evaluation residual magnetism threshold.

4. The method according to claim 3, characterized in that, In the shielded room, after controlling the distance between the treated components of the ultrasonic transducer and the sensor of the optically pumped magnetometer to not exceed a distance threshold, the step of using the optically pumped magnetometer to evaluate the magnetic cleanliness of the treated ultrasonic transducer and determine whether the residual magnetic field is below a magnetic field threshold further includes: Measure the AC magnetic noise of the processed components; and Determine whether the AC magnetic noise has a noise peak within a specified frequency range.

5. The method according to claim 1, characterized in that, After applying the demagnetizing process to the low-remanence component, the method further includes: The processed ultrasonic transducer is subjected to electroacoustic performance verification; wherein the electroacoustic performance parameters include at least one of center frequency, relative bandwidth and sensitivity.

6. The method according to claim 1, characterized in that, The electroacoustic performance verification of the processed ultrasonic transducer includes: The electrical performance is calculated using an electrical performance formula; wherein the electrical performance formula is: ； In the formula, f c The center frequency is represented by BW, the relative bandwidth by S, and the sensitivity by f. l and f u These are the lower cutoff frequency and upper cutoff frequency, respectively, at -6dB. i The output voltage V is the excitation voltage amplitude. o Defined as the echo voltage amplitude, where L is the test distance.

7. The method according to claim 6, characterized in that, in, The ultrasonic transducer has multiple channels; Before calculating the electrical performance using the electrical performance formula, the step of verifying the electroacoustic performance of the processed ultrasonic transducer includes: Extract the envelope of the original echo signal of each channel; wherein the formula for calculating the envelope is: ； In the formula, t represents time, x c (t) represents the original echo signal, e c (t) represents the envelope, and H represents the Hilbert transform; Using the median of the envelope of each channel as a reference time point, the original echo signal of each channel is shifted and compensated so that the main peak of the envelope is aligned with the reference time point.

8. The method according to claim 1, characterized in that, Before performing magnetic cleanliness screening on the ultrasonic transducer and identifying high-remanence and low-remanence components in the ultrasonic transducer, the method further includes: Several calibration magnetic fields of known strength are applied to the optically pumped magnetometer; The response curve output by the optically pumped magnetometer is fitted using a magnetic intensity calculation formula; wherein the magnetic intensity calculation formula is: ； In the formula, R(f) is the effective value of the calibration magnetic field, which characterizes the relationship between the effective value of the signal and the frequency f, A and C are fitting parameters respectively, f0 represents the center frequency, and BW represents the relative bandwidth; The optically pumped magnetometer was calibrated using the response curve.

9. A non-magnetic design device compatible with an ultrasonic transducer and an optically pumped magnetometer, characterized in that, include: The screening module is used to perform magnetic cleanliness screening on the ultrasonic transducer and identify high remanence and low remanence components in the ultrasonic transducer. A replacement module is used to replace the high remanent magnetization component with a low residual magnetization component; A demagnetizing module is used to apply a demagnetizing process to the low residual magnetism component. The evaluation module is used to evaluate the magnetic cleanliness of the processed ultrasonic transducer using the optically pumped magnetometer and to determine whether the residual magnetic field is below the magnetic field threshold.

10. A program product, characterized in that, Includes a computer program / instruction that, when executed by a processor, implements the method as described in any one of claims 1 to 8.

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