CN115060354A - Full-focusing imaging method and device for piezoelectric micro-mechanical ultrasonic transducer - Google Patents
Full-focusing imaging method and device for piezoelectric micro-mechanical ultrasonic transducer Download PDFInfo
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Abstract
The invention discloses a full-focusing imaging method and a device for a piezoelectric micro-mechanical ultrasonic transducer, wherein the method comprises the following steps: acquiring full-matrix echo data consisting of echo signals of a plurality of piezoelectric micro-mechanical ultrasonic transducer units; preprocessing each echo signal in the full matrix echo data to obtain preprocessed full matrix echo data; and carrying out full-focus imaging on the preprocessed full-matrix echo data by adopting a full-focus imaging and compensation method according to the preprocessed full-matrix echo data to obtain a full-focus original imaging picture. The invention solves the problems of small amplitude, serious noise, low signal-to-noise ratio and poor final imaging quality of echo signals when the piezoelectric micro-mechanical ultrasonic transducer array is used for imaging at present, and improves the final imaging quality; in addition, the invention does not need to control the focusing and deflection of the sound beam and hardware delay control, thereby directly avoiding the use of high-precision hardware delay and greatly reducing the cost of hardware design.
Description
Technical Field
The invention relates to the technical field of imaging of piezoelectric micro-mechanical ultrasonic transducers, in particular to a full-focusing imaging method and device for a piezoelectric micro-mechanical ultrasonic transducer.
Background
The piezoelectric micro-mechanical ultrasonic transducer is an energy transducer which converts electric energy into ultrasonic waves by utilizing the inverse piezoelectric effect of a piezoelectric material, or converts the ultrasonic waves into the electric energy by utilizing the piezoelectric effect, and respectively corresponds to the transmitting state and the receiving state. The piezoelectric micromechanical ultrasonic transducer structure is mainly composed of an electrode layer, a piezoelectric film layer, and an upper silicon layer and a lower silicon layer, as shown in fig. 1 and 2. The upper electrode and the lower electrode of the piezoelectric material are electrified, so that the vibration of the piezoelectric film can be excited, and the ultrasonic wave is generated. Piezoelectric micromachined ultrasonic transducers have wide applications in the fields of medical diagnosis, nondestructive testing, and the like, and as shown in fig. 3, imaging using piezoelectric micromachined ultrasonic transducer arrays is one of them. In the traditional imaging, a hardware delay method is used for controlling the focusing and deflection of an acoustic beam so as to scan a point in a region to be detected and perform delayed superposition on echoes so as to image.
Compared with the traditional bulk piezoelectric ultrasonic transducer, the reflected echo signal received after the piezoelectric micro-mechanical ultrasonic transducer is excited is very weak, and particularly when materials with serious sound attenuation such as metal materials are detected, the reflected echo signal is more easily influenced by external noise signals such as circuits. In the traditional phase-controlled imaging, echoes received by each transducer are directly delayed and superposed, so that the optimization processing such as denoising and propagation compensation is inconvenient to perform in the imaging, and the final imaging quality is poor.
Meanwhile, since the phase control needs to perform sound beam operations such as focusing and deflection, accurate hardware delay control is needed, and the cost is high for accurate hardware delay, which is not beneficial to large-scale popularization.
Disclosure of Invention
The invention aims to provide a full-focusing imaging method and a full-focusing imaging device for a piezoelectric micro-mechanical ultrasonic transducer, and solves the problems of small amplitude, serious noise, low signal-to-noise ratio and poor final imaging quality of an echo signal when a piezoelectric micro-mechanical ultrasonic transducer array is used for imaging at present.
The invention is realized by the following technical scheme:
in a first aspect, the present invention provides a method of fully focused imaging for a piezoelectric micromachined ultrasonic transducer, the method comprising:
acquiring full-matrix echo data consisting of echo signals of a plurality of piezoelectric micro-mechanical ultrasonic transducer units;
preprocessing each echo signal in the full matrix echo data to obtain preprocessed full matrix echo data;
and carrying out full-focus imaging on the preprocessed full-matrix echo data by adopting a full-focus imaging and compensation method according to the preprocessed full-matrix echo data to obtain a full-focus original imaging picture.
Further, the acquiring full matrix echo data composed of echo signals of a plurality of piezoelectric micromachined ultrasonic transducer units includes:
sequentially exciting each piezoelectric micro-mechanical ultrasonic transducer unit by adopting a pulse signal to generate a transmitting signal;
receiving the transmitting signal by adopting all piezoelectric micro-mechanical ultrasonic transducer units to obtain an echo signal; and combining each echo signal into full matrix echo data;
wherein the echo signal represents an echo signal emitted by the ith piezoelectric micromachined ultrasonic transducer unit and received by the jth piezoelectric micromachined ultrasonic transducer unit, and is recorded as e ij ，1≤i,j≤k。
The full matrix echo data is comprised of k x k echo signals.
Further, the preprocessing each echo signal in the full matrix echo data includes:
performing wavelet denoising on each echo signal in the full matrix echo data to remove white noise to obtain a first preprocessing signal;
performing band-pass filtering on the first preprocessed signal to filter low-frequency noise and high-frequency noise outside a signal frequency band to obtain a second preprocessed signal;
and performing Hilbert transform on the second preprocessed signal to obtain an envelope of the original signal as each preprocessed echo signal.
Further, the step of performing full focus imaging by the full focus imaging and compensation method is as follows:
step A, dividing a preset imaging area to obtain m × n pixel points; wherein m and n are positive integers;
b, selecting a pixel point p from the divided pixel points, and calculating the distance from the pixel point p to each piezoelectric micro-mechanical ultrasonic transducer unit;
c, selecting a piezoelectric micro-mechanical ultrasonic transducer unit i and a piezoelectric micro-mechanical ultrasonic transducer unit j, calculating the sound wave emitted by the piezoelectric micro-mechanical ultrasonic transducer unit i, and scattering the sound wave to the sound wave propagation path d passed by the piezoelectric micro-mechanical ultrasonic transducer unit j through the pixel point p ij ＝d ip +d jp (ii) a Wherein, d ip Is the distance d from the pixel point p to the piezoelectric micromachined ultrasonic transducer unit i jp The distance from a pixel point p to a piezoelectric micro-mechanical ultrasonic transducer unit j is more than or equal to 1 and less than or equal to k;
step D, calculating the time required by the sound wave propagation path according to the sound wave propagation path and the sound velocity of the sound wave in the to-be-measured piece
c is the sound velocity of sound waves in the piece to be measured; according to the time, extracting the amplitude of the time corresponding to the time in the echo, namely S ij ＝e ij (t ij )，e ij (t ij ) Is one of the full matrix echo data;
e, compensating the amplitude to obtain a compensated final amplitude S ij ′；
Step F, according to the steps C to E, circularly traversing all i and j, and obtaining the final amplitude S of each i and j ij ' and summing to obtain the imaging value A of the pixel point p p I.e. by
And G, circularly traversing all the pixel points according to the steps B to F to obtain a full-focus original imaging image.
Further, the amplitude compensation in step E includes directivity compensation and distance attenuation compensation, and the compensation formula is as follows:
S ij ′＝S ij *w1 ij *w2 ij
wherein, w1 ij For directivity compensation; w2 ij Compensating for distance attenuation; w1 i For transmission directional directivity compensation, w1 j For receiving direction directivity compensation, i is more than or equal to 1, k is more than or equal to j, and x belongs to { i, j }; lambda is the wavelength of sound waves in the piece to be detected; theta x The included angle of the pixel point p piezoelectric micromechanical ultrasonic transducer unit x in the vertical direction is shown.
Further, the method also comprises the step of carrying out image post-processing on the full-focus original imaging picture, and the specific steps are as follows:
carrying out two-dimensional wavelet denoising treatment on the full-focus original imaging graph by adopting a Daubechies wavelet base, and carrying out 4-order decomposition on the full-focus original imaging graph to obtain a high-order sub-band; and carrying out soft threshold mode filtering of self-adaptive threshold on the high-order sub-band to obtain a filtered full-focusing final imaging image.
In a second aspect, the present invention further provides a full-focus imaging apparatus for a piezoelectric micromachined ultrasonic transducer, which supports the full-focus imaging method for the piezoelectric micromachined ultrasonic transducer; the device includes:
the full-matrix echo data acquisition unit is used for acquiring full-matrix echo data consisting of echo signals of the piezoelectric micro-mechanical ultrasonic transducer units;
the preprocessing unit is used for preprocessing each echo signal in the full matrix echo data to obtain preprocessed full matrix echo data;
the full-focus imaging and compensating unit is used for performing full-focus imaging on the preprocessed full-matrix echo data by adopting a full-focus imaging and compensating optimization method according to the preprocessed full-matrix echo data to obtain a full-focus original imaging picture;
and the image post-processing unit is used for performing image post-processing on the full-focus original imaging image, and the image post-processing comprises two-dimensional wavelet denoising processing and self-adaptive threshold filtering to obtain a filtered full-focus final imaging image.
Further, the full matrix echo data acquisition unit includes:
the transmitting signal generating subunit is used for sequentially adopting pulse signals to excite each piezoelectric micro-mechanical ultrasonic transducer unit to generate transmitting signals;
the echo signal subunit is used for receiving the transmitting signal by adopting all the piezoelectric micro-mechanical ultrasonic transducer units to obtain an echo signal;
the full-matrix echo data composition subunit is used for combining each echo signal into full-matrix echo data; wherein the echo signal represents an echo signal emitted by the ith piezoelectric micromachined ultrasonic transducer unit and received by the jth piezoelectric micromachined ultrasonic transducer unit, and is recorded as e ij ，1≤i,j≤k。
The full matrix echo data is comprised of k x k echo signals.
In a third aspect, the present invention provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the method for full focus imaging for a piezoelectric micromachined ultrasonic transducer when executing the computer program.
In a fourth aspect, the present invention is a computer-readable storage medium storing a computer program, which when executed by a processor implements the method for full focus imaging for a piezoelectric micromachined ultrasonic transducer.
Compared with the prior art, the invention has the following advantages and beneficial effects:
1. the invention relates to a full-focusing imaging method and a full-focusing imaging device for a piezoelectric micro-mechanical ultrasonic transducer, which solve the problems of small amplitude, serious noise, low signal-to-noise ratio and poor final imaging quality of echo signals when a piezoelectric micro-mechanical ultrasonic transducer array is used for imaging at present, and improve the final imaging quality; in addition, the invention does not need to control the focusing and deflection of the sound beam and hardware delay control, thereby directly avoiding the use of high-precision hardware delay and greatly reducing the cost of hardware design.
2. The invention relates to a full-focusing imaging method and a device for a piezoelectric micro-mechanical ultrasonic transducer, wherein when full-matrix echo data is preprocessed, a hard threshold mode with a fixed threshold is used for carrying out wavelet denoising to remove white noise, then low-frequency and high-frequency noises outside a signal frequency band are filtered by using band-pass filtering, and finally Hilbert transformation is carried out to obtain an envelope of an original signal; and ensuring that the full matrix echo data is subjected to comprehensive filtering and denoising.
3. The invention relates to a full-focusing imaging method and a device for a piezoelectric micro-mechanical ultrasonic transducer, which utilize full-matrix echo data to carry out full-focusing algorithm imaging and simultaneously use directivity compensation and distance attenuation compensation to correct echo imaging; the accuracy of full-focus imaging is guaranteed.
4. The invention relates to a full-focusing imaging method and a full-focusing imaging device for a piezoelectric micro-mechanical ultrasonic transducer, wherein a soft threshold mode of a self-adaptive threshold is used for carrying out wavelet denoising (and threshold filtering) in image post-processing, so that the signal-to-noise ratio of an image is further enhanced.
Drawings
The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:
fig. 1 is a cross-sectional view of a piezoelectric micromachined ultrasonic transducer structure.
Figure 2 is a 3D diagram of a piezoelectric micromachined ultrasonic transducer structure.
Fig. 3 is a schematic diagram of piezoelectric micromachined ultrasonic transducer array imaging.
FIG. 4 is a schematic diagram of the full focus imaging of the present invention.
Fig. 5 is a flow chart of a full focus imaging method for a piezoelectric micromachined ultrasonic transducer according to the present invention.
Fig. 6 is a detailed flowchart of a full-focus imaging method for a piezoelectric micromachined ultrasonic transducer according to the present invention.
Fig. 7 is a schematic structural diagram of a fully focused imaging device for a piezoelectric micromachined ultrasonic transducer according to the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.
Example 1
Based on the problems that when the piezoelectric micro-mechanical ultrasonic transducer array is used for imaging at present, the amplitude of an echo signal is small, the noise is serious, the signal-to-noise ratio is low, and the final imaging quality is poor; the invention designs a full-focusing imaging method for a piezoelectric micro-mechanical ultrasonic transducer, which comprises the steps of firstly collecting full-matrix echo data formed by echo signals of a plurality of piezoelectric micro-mechanical ultrasonic transducer units; secondly, preprocessing the full matrix echo data obtained by the piezoelectric micro-mechanical ultrasonic transducer unit, wherein the preprocessing comprises removing white noise by using wavelet denoising, and filtering low-frequency and high-frequency noise outside a signal frequency band by using band-pass filtering, so that the signal noise is greatly reduced, the signal-to-noise ratio is improved, and meanwhile, the envelope of an original signal is obtained by using Hilbert transform to enhance useful information of the signal. Then, when full-matrix echo data is used for full-focusing algorithm imaging, directivity compensation and distance attenuation compensation are introduced simultaneously, loss in the transmission process is corrected, and therefore image quality is improved. Finally, wavelet denoising (and threshold filtering) is used for further removing artifacts and noise in the image, and a full-focus final imaging image is obtained.
In addition, the invention does not need to control the focusing and deflection of the sound beam and hardware delay control, thus directly avoiding the use of high-precision hardware delay and greatly reducing the cost of hardware design; meanwhile, optimization processing such as denoising and compensation can be carried out, and the final imaging quality is improved.
As shown in fig. 4 to 6, the present invention relates to a full focus imaging method for a piezoelectric micromachined ultrasonic transducer, as shown in fig. 5 and 6, the method includes:
a total of k piezoelectric micro-mechanical ultrasonic transducer units are arranged;
sequentially exciting each piezoelectric micro-mechanical ultrasonic transducer unit by adopting a pulse signal to generate a transmitting signal;
simultaneously, all piezoelectric micro-mechanical ultrasonic transducer units are adopted to receive the transmitted signals to obtain echo signals; and combining each echo signal into full matrix echo data; the full matrix echo data is comprised of k x k echo signals.
Wherein the echo signal represents an echo signal emitted by the ith piezoelectric micromachined ultrasonic transducer unit and received by the jth piezoelectric micromachined ultrasonic transducer unit, and is recorded as e ij ，1≤i,j≤k。
For example: exciting a piezoelectric micro-mechanical ultrasonic transducer unit by adopting a pulse signal to generate a transmitting signal;
simultaneously, receiving the transmitting signal by adopting all piezoelectric micro-mechanical ultrasonic transducer units to obtain k echo signals;
then each piezoelectric micromechanical ultrasonic transducer unit is excited by a pulse signal in turn, so that k × k echo signals are obtained.
Step 2, preprocessing each echo signal in the full matrix echo data to obtain preprocessed full matrix echo data, which specifically comprises:
for each echo signal e in the full matrix echo data ij Removing white noise by wavelet denoising to obtain a first preprocessing signal;
performing band-pass filtering on the first preprocessed signal to filter low-frequency noise and high-frequency noise outside a signal frequency band to obtain a second preprocessed signal;
and performing Hilbert transform on the second preprocessed signal to obtain an envelope of the original signal as each preprocessed echo signal.
Specifically, the specific process of wavelet denoising is as follows:
echo signal e using Daubechies wavelet basis ij 4 order decomposition is performed due to the original echo signal e ij And (3) carrying out hard threshold mode filtering with a fixed threshold on the high-order subband w obtained by decomposition, wherein the hard threshold mode filtering formula is as follows:
wherein w h For the first preprocessed signal, the threshold T is selected in relation to the signal-to-noise ratio of the particular signal, as an example:
where L is the length of the subband coefficient vector.
Specifically, the specific process of band-pass filtering is as follows:
using a Butterworth bandpass filter whose high and low cutoff frequency settings are related to the center frequency and-6 dB bandwidth of the piezoelectric micromachined ultrasonic transducer cell, to name one example: the-6 dB bandwidth of the piezoelectric micro-mechanical ultrasonic transducer unit using the 2MHz central frequency is 1.5 MHz-2.5 MHz, and in order to reduce the information loss of the original echo, the high-low cut-off frequency of a band-pass filter can be 4MHz and 300 kHz.
Specifically, Hilbert transform transforms the echo signal into a complex domain using Hilbert (Hilbert) transform, so that envelope information of scattered echoes in the signal can be extracted, and each preprocessed echo signal is obtained.
And 3, carrying out full-focus imaging on the preprocessed full-matrix echo data by adopting a full-focus imaging and compensation method according to the preprocessed full-matrix echo data to obtain a full-focus original imaging picture. The method specifically comprises the following steps:
step A, dividing a preset imaging area to obtain m × n pixel points; wherein m and n are positive integers;
b, selecting a pixel point p from the divided pixel points, and calculating the distance from the pixel point p to each piezoelectric micro-mechanical ultrasonic transducer unit;
c, selecting a piezoelectric micro-mechanical ultrasonic transducer unit i and a piezoelectric micro-mechanical ultrasonic transducer unit j, calculating the sound wave emitted by the piezoelectric micro-mechanical ultrasonic transducer unit i, and scattering the sound wave to the sound wave propagation path d passed by the piezoelectric micro-mechanical ultrasonic transducer unit j through the pixel point p ij ＝d ip +d jp (ii) a Wherein d is ip Is the distance d from the pixel point p to the piezoelectric micromachined ultrasonic transducer unit i jp The distance from a pixel point p to a piezoelectric micro-mechanical ultrasonic transducer unit j is more than or equal to 1 and less than or equal to k;
step D, calculating the time required by the sound wave propagation path according to the sound wave propagation path and the sound velocity of the sound wave in the to-be-measured piece
c is the sound velocity of sound waves in the piece to be measured; according to the time, extracting the amplitude of the time corresponding to the time in the echo, namely S ij ＝e ij (t ij )，e ij (t ij ) Is one of the full matrix echo data;
e, compensating the amplitude to obtain a compensated final amplitude S ij ′；
Step F, according to the steps C to E, all the i and j are circularly traversed, and the final time of each i and j is obtainedAmplitude S ij ' and summing to obtain the imaging value A of the pixel point p p I.e. by
And G, circularly traversing all the pixel points according to the steps B to F to obtain a full-focus original imaging image.
As a further implementation, the compensating of the amplitude in step E includes directivity compensation and distance attenuation compensation, and the compensation formula is as follows:
S ij ′＝S ij *w1 ij *w2 ij
wherein, w1 ij For directivity compensation, w2 ij For distance attenuation compensation, w1 i For transmission directional directivity compensation, w1 j For receiving direction directivity compensation, i is more than or equal to 1, k is more than or equal to j, and x belongs to { i, j }; λ is the wavelength of the acoustic wave in the object to be measured, θ x The included angle of the pixel point p piezoelectric micromechanical ultrasonic transducer unit x in the vertical direction is shown.
The invention has the following advantages:
1. according to the full-focus imaging method for the piezoelectric micro-mechanical ultrasonic transducer array, when full-matrix echo data are preprocessed, a hard threshold mode with a fixed threshold is used for carrying out wavelet denoising and white noise removal, then low-frequency noise and high-frequency noise outside a signal frequency band are filtered by using band-pass filtering, and finally Hilbert transform is carried out to obtain an envelope of an original signal; ensuring that the full matrix echo data is subjected to comprehensive filtering and denoising.
2. The invention aims at the full focusing imaging method of the piezoelectric micro-mechanical ultrasonic transducer array, full focusing algorithm imaging is carried out by utilizing full matrix echo data, and directivity compensation and distance attenuation compensation are simultaneously used for correcting echo imaging; the accuracy of full-focus imaging is guaranteed.
3. In the invention, aiming at the full-focusing imaging method of the piezoelectric micro-mechanical ultrasonic transducer array, a soft threshold mode of self-adaptive threshold is used for carrying out wavelet denoising (and threshold filtering) in image post-processing, thereby further enhancing the signal-to-noise ratio of the image.
4. The invention adopts a full-focusing imaging method and improves the method to carry out optimization processing such as denoising and compensation on the piezoelectric micro-mechanical ultrasonic transducer without hardware delay control, thereby improving the final imaging quality.
Example 2
As shown in fig. 5 and fig. 6, the difference between this embodiment and embodiment 1 is that the method further includes performing image post-processing on the fully-focused original imaging image, and the specific steps are as follows:
performing two-dimensional wavelet denoising treatment on the full-focus original imaging graph by adopting a Daubechies wavelet base, and performing 4-order decomposition on the full-focus original imaging graph to obtain a high-order sub-band; and carrying out soft threshold mode filtering of self-adaptive threshold on the high-order sub-band to obtain a filtered full-focusing final imaging image.
Specifically, the method comprises the following steps: the specific process of two-dimensional wavelet denoising is as follows:
performing 4-order decomposition on the image by using a Daubechies wavelet basis, and performing adaptive threshold soft threshold mode filtering on the high-order sub-band w obtained by decomposition, wherein the soft threshold mode filtering formula is as follows:
the adaptive threshold T is estimated using the Stein unbiased likelihood:
(1) the square w of the sub-band coefficients is ordered from small to large 2 Sorting and obtaining new waitingEstimate vector w n ＝sort(w 2 )；
(2) Computing a risk vector
Wherein y is more than or equal to 1 and less than or equal to L, and L is the length of the sub-band coefficient vector;
(3) get the minimum value of the risk vector corresponding to i min ＝argmin(r y ) And calculating a threshold value
Where alpha is a correction factor that can be set to 0.05,
the estimated value of the standard deviation of the subband coefficient and the mean is the median.
Specifically, the method comprises the following steps: threshold filtering may also be performed. Selecting the highest imaging value A in the image max For imaging amplitude less than A max The x z pixels are zeroed and z is related to the actual signal and imaging quality, with a typical example being 0.2.
Example 3
As shown in fig. 7, the present embodiment is different from embodiment 1 in that the present embodiment provides a full-focus imaging apparatus for a piezoelectric micromachined ultrasonic transducer, which supports a full-focus imaging method for a piezoelectric micromachined ultrasonic transducer described in embodiment 1 or embodiment 2; the device includes:
the full matrix echo data acquisition unit is used for acquiring full matrix echo data consisting of echo signals of a plurality of piezoelectric micro-mechanical ultrasonic transducer units;
the preprocessing unit is used for preprocessing each echo signal in the full matrix echo data to obtain preprocessed full matrix echo data;
the full-focus imaging and compensating unit is used for performing full-focus imaging on the preprocessed full-matrix echo data by adopting a full-focus imaging and compensating optimization method according to the preprocessed full-matrix echo data to obtain a full-focus original imaging picture;
and the image post-processing unit is used for performing image post-processing on the full-focus original imaging image, and the image post-processing comprises two-dimensional wavelet denoising processing and self-adaptive threshold filtering to obtain a filtered full-focus final imaging image.
In this embodiment, the full-matrix echo data acquiring unit includes:
the transmitting signal generating subunit is used for sequentially adopting pulse signals to excite each piezoelectric micro-mechanical ultrasonic transducer unit to generate transmitting signals;
the echo signal subunit is used for receiving the transmitting signal by adopting all the piezoelectric micro-mechanical ultrasonic transducer units to obtain an echo signal;
the full-matrix echo data composition subunit is used for combining each echo signal into full-matrix echo data; wherein the echo signal represents an echo signal emitted by the ith piezoelectric micromachined ultrasonic transducer unit and received by the jth piezoelectric micromachined ultrasonic transducer unit, and is recorded as e ij ，1≤i,j≤k。
The full matrix echo data is comprised of k x k echo signals.
The execution process of each unit is executed according to the flow steps of the full-focusing imaging method for the piezoelectric micromachined ultrasonic transducer described in embodiment 1, and details are not repeated in this embodiment.
Meanwhile, the invention also provides a computer device, which comprises a memory, a processor and a computer program stored in the memory and capable of running on the processor, wherein the processor executes the computer program to realize the full-focus imaging method for the piezoelectric micromechanical ultrasonic transducer.
Meanwhile, the invention further provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to realize the full focus imaging method for the piezoelectric micromechanical ultrasonic transducer.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. A method of full focus imaging for a piezoelectric micromachined ultrasound transducer, the method comprising:
acquiring full-matrix echo data consisting of echo signals of a plurality of piezoelectric micro-mechanical ultrasonic transducer units;
preprocessing each echo signal in the full matrix echo data to obtain preprocessed full matrix echo data;
and carrying out full-focus imaging on the preprocessed full-matrix echo data by adopting a full-focus imaging and compensation method according to the preprocessed full-matrix echo data to obtain a full-focus original imaging picture.
2. The method according to claim 1, wherein the acquiring full-matrix echo data composed of echo signals of a plurality of piezoelectric micromachined ultrasonic transducer units comprises:
sequentially exciting each piezoelectric micro-mechanical ultrasonic transducer unit by adopting a pulse signal to generate a transmitting signal;
receiving the transmitted signal by adopting all piezoelectric micro-mechanical ultrasonic transducer units to obtain an echo signal; and combining each echo signal into full matrix echo data;
wherein the echo signal represents an echo signal emitted by the ith piezoelectric micromachined ultrasonic transducer unit and received by the jth piezoelectric micromachined ultrasonic transducer unit, and is recorded as e ij ，1≤i,j≤k。
3. The method according to claim 1, wherein the preprocessing each echo signal in the full matrix echo data comprises:
performing wavelet denoising on each echo signal in the full matrix echo data to remove white noise to obtain a first preprocessing signal;
performing band-pass filtering on the first preprocessed signal to filter low-frequency noise and high-frequency noise outside a signal frequency band to obtain a second preprocessed signal;
and performing Hilbert transform on the second preprocessed signal to obtain an envelope of the original signal as each preprocessed echo signal.
4. The method according to claim 1, wherein the step of performing full-focus imaging by the full-focus imaging and compensation method comprises:
step A, dividing a preset imaging area to obtain m × n pixel points; wherein m and n are positive integers;
b, selecting a pixel point p from the divided pixel points, and calculating the distance from the pixel point p to each piezoelectric micro-mechanical ultrasonic transducer unit;
c, selecting a piezoelectric micro-mechanical ultrasonic transducer unit i and a piezoelectric micro-mechanical ultrasonic transducer unit j, calculating the sound wave emitted by the piezoelectric micro-mechanical ultrasonic transducer unit i, and scattering the sound wave to the sound wave propagation path d passed by the piezoelectric micro-mechanical ultrasonic transducer unit j through the pixel point p ij ＝d ip +d jp (ii) a Wherein d is ip Is the distance d from the pixel point p to the piezoelectric micromachined ultrasonic transducer unit i jp The distance from a pixel point p to a piezoelectric micro-mechanical ultrasonic transducer unit j is more than or equal to 1 and less than or equal to k;
step D, calculating the time required by the sound wave propagation path according to the sound wave propagation path and the sound velocity of the sound wave in the to-be-measured piece
c is the sound velocity of sound waves in the piece to be measured; according to the aboveTime, extracting the amplitude of the time corresponding to the time in the echo, i.e. S ij ＝e ij (t ij )，e ij (t ij ) Is one of the full matrix echo data;
e, compensating the amplitude to obtain a compensated final amplitude S ij ′；
Step F, according to the steps C to E, circularly traversing all i and j, and obtaining the final amplitude S of each i and j ij ' and summing to obtain the imaging value A of the pixel point p p I.e. by
And G, circularly traversing all the pixel points according to the steps B to F to obtain a full-focus original imaging image.
5. The full-focus imaging method for the piezoelectric micromachined ultrasonic transducer according to claim 4, wherein the amplitude compensation in step E includes a directivity compensation and a distance attenuation compensation, and the compensation formula is as follows:
S ij ′＝S ij *w1 ij *w2 ij
wherein, w1 ij For directivity compensation; w2 ij Compensating for distance attenuation; w1 i For transmission directional directivity compensation, w1 j For receiving directional compensation, 1 ≦i, j is less than or equal to k, and x belongs to { i, j }; lambda is the wavelength of sound waves in the piece to be measured; theta x The included angle of the pixel point p piezoelectric micromechanical ultrasonic transducer unit x in the vertical direction is shown.
6. The method according to claim 1, further comprising performing image post-processing on the fully focused raw imaging map, specifically including the steps of:
carrying out two-dimensional wavelet denoising treatment on the full-focus original imaging graph by adopting a Daubechies wavelet base, and carrying out 4-order decomposition on the full-focus original imaging graph to obtain a high-order sub-band; and carrying out soft threshold mode filtering of self-adaptive threshold on the high-order sub-band to obtain a filtered full-focusing final imaging image.
7. A full focus imaging apparatus for a piezoelectric micromachined ultrasonic transducer, characterized in that the apparatus supports a full focus imaging method for a piezoelectric micromachined ultrasonic transducer as claimed in any one of claims 1 to 6; the device comprises:
the full-matrix echo data acquisition unit is used for acquiring full-matrix echo data consisting of echo signals of the piezoelectric micro-mechanical ultrasonic transducer units;
the preprocessing unit is used for preprocessing each echo signal in the full matrix echo data to obtain preprocessed full matrix echo data;
the full-focus imaging and compensating unit is used for performing full-focus imaging on the preprocessed full-matrix echo data by adopting a full-focus imaging and compensating optimization method according to the preprocessed full-matrix echo data to obtain a full-focus original imaging picture;
and the image post-processing unit is used for performing image post-processing on the full-focus original imaging image, and the image post-processing comprises two-dimensional wavelet denoising processing and self-adaptive threshold filtering to obtain a filtered full-focus final imaging image.
8. The fully focused imaging apparatus for piezoelectric micromachined ultrasonic transducer according to claim 7, wherein the full matrix echo data acquisition unit comprises:
the transmitting signal generating subunit is used for sequentially adopting pulse signals to excite each piezoelectric micro-mechanical ultrasonic transducer unit to generate transmitting signals;
the echo signal subunit is used for receiving the transmitting signal by adopting all the piezoelectric micro-mechanical ultrasonic transducer units to obtain an echo signal;
the full-matrix echo data composition subunit is used for combining each echo signal into full-matrix echo data; wherein the echo signal represents an echo signal emitted by the ith piezoelectric micromachined ultrasonic transducer unit and received by the jth piezoelectric micromachined ultrasonic transducer unit, and is recorded as e ij ，1≤i,j≤k。
9. A computer device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, characterized in that the processor implements a method of full focus imaging for a piezoelectric micromachined ultrasonic transducer according to any one of claims 1 to 6 when executing the computer program.
10. A computer-readable storage medium, in which a computer program is stored which, when being executed by a processor, carries out a method of full focus imaging for a piezoelectric micromachined ultrasonic transducer according to any one of claims 1 to 6.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115791974A (en) * | 2023-02-02 | 2023-03-14 | 汕头市超声检测科技有限公司 | Fitting curve-based all-focusing imaging directivity weighting calculation method |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108594228A (en) * | 2018-04-28 | 2018-09-28 | 西安电子科技大学 | Spatial target posture method of estimation based on ISAR image refocusings |
| CN113808092A (en) * | 2021-09-09 | 2021-12-17 | 广州大学 | Method, system, device and medium for detecting debonding defect of steel pipe concrete interface |
-
2022
- 2022-06-30 CN CN202210762277.2A patent/CN115060354A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108594228A (en) * | 2018-04-28 | 2018-09-28 | 西安电子科技大学 | Spatial target posture method of estimation based on ISAR image refocusings |
| CN113808092A (en) * | 2021-09-09 | 2021-12-17 | 广州大学 | Method, system, device and medium for detecting debonding defect of steel pipe concrete interface |
Non-Patent Citations (4)
| Title |
|---|
| 刘建全 等: "钢轨缺陷的超声相控阵波数成像算法", 应用声学, vol. 37, no. 6, 30 November 2018 (2018-11-30), pages 3 * |
| 焦敬品;李勇强;杜礼;何存富;吴斌;: "板结构裂纹兰姆波阵列复合成像方法研究", 仪器仪表学报, no. 03, 15 March 2016 (2016-03-15) * |
| 王冲;毛捷;廉国选;: "阵元固体指向性补偿对超声全聚焦成像的优化研究", 应用声学, no. 05, 13 September 2018 (2018-09-13), pages 1 - 6 * |
| 韩松 等: "小波技术在消除全聚焦成像中伪像的研究", 仪器仪表标准化与计量, 26 April 2022 (2022-04-26), pages 1 - 2 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115791974A (en) * | 2023-02-02 | 2023-03-14 | 汕头市超声检测科技有限公司 | Fitting curve-based all-focusing imaging directivity weighting calculation method |
| CN115791974B (en) * | 2023-02-02 | 2023-08-22 | 汕头市超声检测科技有限公司 | Full-focus imaging directivity weighting calculation method based on fitting curve |
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