A double-layer medium defect imaging method and system with improved full focusing algorithm

Abstract

The present invention provides a double-layer medium defect imaging method and system with an improved full-focusing algorithm, which relates to the technical field of ultrasonic phased array nondestructive testing; the method includes: exciting ultrasonic signals into a double-layer specimen through a multi-element ultrasonic transducer, and performing full-matrix data acquisition in the area to be detected, and converting the acquired signals to obtain an echo digital signal matrix; constructing an optimized full-focusing algorithm according to Fermat's principle and Snell's theorem, deriving a refraction compensation expression according to the law of refraction and reflection, and improving the optimized full-focusing algorithm to obtain an improved full-focusing algorithm; calculating the signals corresponding to multiple pixel points in the echo digital signal matrix respectively through the improved full-focusing algorithm, obtaining the echo amplitudes corresponding to the multiple pixel points, and constructing a defect image according to the echo amplitudes corresponding to the multiple pixel points. By performing signal compensation on the echo signal, the echo signal can more accurately characterize the defects of the specimen and generate a clear and visible defect image.

Description

Technical Field

[0001] The present invention mainly relates to the technical field of ultrasonic phased array nondestructive testing, and in particular to a double-layer medium defect imaging method and system with an improved total focusing algorithm. Background Art

[0002] Ultrasonic testing is currently the most widely used and most frequently used non-destructive testing technology. Ultrasonic testing has a wide range of detection objects, a large detection thickness and high sensitivity. It can locate and quantify defects, and is particularly sensitive to defects such as cracks or holes.

[0003] In the nondestructive testing process of chemical equipment, the internal defect detection of double-layer metal media accounts for a very large proportion. However, when the ultrasonic detection object is a double-layer metal medium, the ultrasonic wave will be refracted and reflected when it enters another medium from one medium, resulting in energy loss of the received echo signal; at the same time, the interface of the medium will also reflect the ultrasonic wave, which will cause the echo signal of the defect to be covered by the reflected interface wave signal, resulting in the missed detection of the defect.

[0004] Therefore, an imaging algorithm is needed to enhance the echo signal and reduce the interference of the interface wave signal, so as to solve the problem that the echo signal is covered by the interface wave signal. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a double-layer medium defect imaging method and system with an improved full focusing algorithm in view of the deficiencies in the prior art.

[0006] The technical solution of the present invention to solve the above technical problems is as follows:

[0007] A double-layer medium defect imaging method with an improved total focusing algorithm comprises the following steps:

[0008] A probe chip excitation rule and a probe chip receiving rule are set, and an ultrasonic signal is excited into a preset double-layer test piece through a preset phased array detection component according to the probe chip excitation rule, and a plurality of pixel points are set in a to-be-detected area set in the double-layer test piece, and the ultrasonic signal generates a corresponding echo sound signal at each pixel point, and full-matrix data acquisition is performed on the echo sound signals corresponding to the plurality of pixel points according to the probe chip receiving rule, and an echo sound signal matrix is ​​formed by the plurality of echo sound signals corresponding to the plurality of pixel points;

[0009] Respectively converting a plurality of echo acoustic signals corresponding to a plurality of pixel points in the echo acoustic signal matrix into a plurality of echo digital signals, and forming a digital signal matrix with the plurality of echo digital signals corresponding to the plurality of pixel points;

[0010] The total sound propagation time expression is derived by Fermat's principle and Snell's theorem, an optimized total focusing algorithm is constructed by the total sound propagation time expression, and a refraction compensation expression is derived according to the law of refraction and reflection, and the optimized total focusing algorithm is optimized by the refraction compensation expression to obtain an improved total focusing algorithm;

[0011] The improved full focusing algorithm is used to calculate the echo digital signals corresponding to the multiple pixel points in the area to be detected in the digital signal matrix, respectively, to obtain the compensated echo amplitudes corresponding to the multiple pixel points, and to construct a defect image based on the compensated echo amplitudes corresponding to the multiple pixel points.

[0012] Furthermore, the phased array detection assembly includes an ultrasonic phased array detector and a multi-element ultrasonic transducer;

[0013] The method of exciting the ultrasonic signal into the preset double-layer test piece through the preset phased array detection component according to the probe wafer excitation rule is specifically as follows:

[0014] According to the probe wafer excitation rule, the electrical signal is transmitted to the preset multi-element ultrasonic transducer through the preset ultrasonic phased array detector;

[0015] The electrical signal is converted into an ultrasonic signal by the multi-element ultrasonic transducer, and the ultrasonic signal is excited into a preset double-layer test piece.

[0016] Further, the multi-element ultrasonic transducer includes a plurality of array elements;

[0017] According to the probe chip excitation rule, an ultrasonic signal is excited into a preset double-layer specimen through a preset phased array detection component, and multiple pixel points are set in the to-be-detected area set in the double-layer specimen. The ultrasonic signal generates a corresponding echo sound signal at each pixel point, and full-matrix data acquisition is performed on the echo sound signals corresponding to the multiple pixel points according to the probe chip receiving rule, and the multiple echo sound signals corresponding to the multiple pixel points constitute an echo sound signal matrix, specifically:

[0018] According to the excitation sequence in the probe chip excitation rule, the first ultrasonic signal is excited into the preset double-layer test piece through the first array element, a plurality of pixel points are set in the to-be-detected area set in the double-layer test piece, the first ultrasonic signal generates a corresponding first echo sound signal at each pixel point, and according to the receiving sequence in the probe chip receiving rule, the first echo sound signals corresponding to the plurality of pixel points are respectively received through all array elements, so as to obtain the first echo sound signals corresponding to the plurality of pixel points in each array element;

[0019] According to the excitation order in the probe chip excitation rule, a second ultrasonic signal is excited into the double-layer test piece through a second array element, the second ultrasonic signal generates a corresponding second echo sound signal at each pixel point, and according to the receiving order in the probe chip receiving rule, the second echo sound signals corresponding to multiple pixel points are respectively received through all array elements, so as to obtain the second echo sound signals corresponding to the multiple pixel points in each array element;

[0020] And so on, until the last ultrasonic signal is excited into the double-layer specimen through the last array element according to the excitation sequence in the probe chip excitation rule, the last ultrasonic signal generates a corresponding last echo sound signal at each pixel point, and the last echo sound signals corresponding to multiple pixel points are respectively received by all array elements according to the receiving sequence in the probe chip receiving rule, and the last echo sound signals corresponding to the multiple pixel points in each array element are obtained, so that the echo sound signal matrix is ​​composed of the multiple echo sound signals corresponding to the multiple pixel points in each array element.

[0021] Furthermore, the multiple echo acoustic signals corresponding to the multiple pixel points in the echo acoustic signal matrix are converted into multiple echo digital signals, and the multiple echo digital signals corresponding to the multiple pixel points constitute a digital signal matrix, specifically:

[0022] The multi-element ultrasonic transducer converts the multiple echo acoustic signals corresponding to the multiple pixel points in the echo acoustic signal matrix into the multiple echo electrical signals corresponding to the multiple pixel points, and transmits the multiple echo electrical signals corresponding to the multiple pixel points to the ultrasonic phased array detector;

[0023] The ultrasonic phased array detector converts the multiple echo electrical signals corresponding to the multiple pixel points into multiple echo digital signals corresponding to the multiple pixel points, and the multiple echo digital signals corresponding to the multiple pixel points form a digital signal matrix.

[0024] Furthermore, the total sound propagation time expression is derived by using Fermat's principle and Snell's theorem, specifically:

[0025] The sound propagation distance expression is derived according to the Fermat principle. The sound propagation distance expression is used to calculate the sound propagation distance of any echo digital signal corresponding to any pixel point in the area to be detected in the digital signal matrix, and the sound velocity of the double-layer specimen is substituted into the sound propagation distance expression for calculation to obtain the sound propagation time expression, which is:

[0026]

[0027] x=H tanθ i +(zH)tanθs ,

[0028] x i =[(N+1) / 2-i]d,

[0029] Among them, T i is the sound propagation time, x i is the horizontal coordinate of the array element that excites the ultrasonic signal, x it is the horizontal coordinate of the refraction point of the ultrasonic signal at the interface, x is the horizontal coordinate of the pixel point, z is the vertical coordinate of the pixel point, H is the thickness of the first medium, c 1 is the first medium sound velocity, c 2 is the second medium sound velocity, N is the number of array elements, d is the array element spacing, θ i is the incident angle of the ultrasonic signal, θ s is the refraction angle of ultrasonic signal;

[0030] The acoustic refractive index expression is derived according to Snell's theorem. The acoustic refractive index expression is used to calculate the acoustic refractive index of any echo digital signal corresponding to any pixel point in the area to be detected in the digital signal matrix. The acoustic refractive index expression is:

[0031]

[0032] Among them, n 12 is the acoustic refractive index;

[0033] The acoustic propagation time expression and the acoustic refractive index expression are combined to derive the total acoustic propagation time expression through the combined expression. The total acoustic propagation time expression is used to calculate the total acoustic propagation time of any echo digital signal corresponding to any pixel point in the area to be detected in the digital signal matrix. The total acoustic propagation time expression is:

[0034]

[0035] Among them, t ij (x,z) is the total sound propagation time, x j is the horizontal coordinate of the array element that collects the echo sound signal, x jr is the horizontal coordinate of the refraction point of the echo sound signal at the interface.

[0036] Furthermore, the optimized total focusing algorithm is constructed by using the total sound propagation time expression, specifically:

[0037] The total sound propagation time expression is fused by the delay superposition rule to construct an echo amplitude expression, which is used to calculate the echo amplitude corresponding to each pixel point in the area to be detected. The echo amplitude expression is the optimized full focusing algorithm, and the echo amplitude expression is:

[0038]

[0039] Where I(x,z) is the echo amplitude, t ij (x,z) is the total sound propagation time.

[0040] Furthermore, the optimized total focusing algorithm is optimized by the refraction compensation expression to obtain an improved total focusing algorithm, which is specifically:

[0041] The refraction compensation expression and the echo amplitude expression are combined to obtain a compensation echo amplitude expression, which is used to calculate the compensation echo amplitude corresponding to each pixel point in the area to be detected. The compensation echo amplitude expression is an improved full focusing algorithm, and the compensation echo amplitude expression is:

[0042]

[0043] Where I'(x,z) is the compensation echo amplitude, t ij (x,z) is the total sound propagation time, and the refraction compensation expression is:

[0044]

[0045] Among them, T L (θ 1 ,θ L ,θ s ) is the refraction compensation coefficient, ρ 1 is the density of the first medium, ρ 2 is the density of the second medium, c L is the shear wave speed, c s is the longitudinal wave speed, θ s is the incident angle of the longitudinal wave, θ L is the incident angle of the shear wave, c 1 is the first medium sound velocity, θ 1 is the critical angle of the first medium, and · is the multiplication.

[0046] Another technical solution of the present invention to solve the above technical problems is as follows:

[0047] A double-layer medium defect imaging system with an improved full focusing algorithm, comprising:

[0048] A signal acquisition module, used for setting a probe chip excitation rule and a probe chip receiving rule, exciting an ultrasonic signal to a preset double-layer test piece through a preset phased array detection component according to the probe chip excitation rule, setting a plurality of pixel points in a to-be-detected area set in the double-layer test piece, the ultrasonic signal generates a corresponding echo sound signal at each pixel point, and performing full-matrix data acquisition on the echo sound signals corresponding to the plurality of pixel points according to the probe chip receiving rule, so that an echo sound signal matrix is ​​formed by the plurality of echo sound signals corresponding to the plurality of pixel points;

[0049] A signal conversion module, used for converting a plurality of echo acoustic signals corresponding to a plurality of pixel points in the echo acoustic signal matrix into a plurality of echo digital signals, wherein the plurality of echo digital signals corresponding to the plurality of pixel points constitute a digital signal matrix;

[0050] An algorithm improvement module is used to derive an expression of total sound propagation time through Fermat's principle and Snell's theorem, construct an optimized total focusing algorithm through the expression of total sound propagation time, derive a refraction compensation expression according to the law of refraction and reflection, optimize the optimized total focusing algorithm through the refraction compensation expression, and obtain an improved total focusing algorithm;

[0051] An image construction module is used to calculate the echo digital signals corresponding to multiple pixel points in the area to be detected in the digital signal matrix through the improved full focusing algorithm, obtain the compensated echo amplitudes corresponding to the multiple pixel points, and construct a defect image according to the compensated echo amplitudes corresponding to the multiple pixel points.

[0052] The beneficial effects of the present invention are: each probe chip is controlled according to the set probe chip excitation law and probe chip receiving law; the ultrasonic phased array detector and the multi-element ultrasonic transducer are used to complete the excitation processing of the ultrasonic signal and the collection processing of the echo signal. The total focusing algorithm is optimized according to the Fermat principle and Snell's theorem, so that the optimized total focusing algorithm can calculate the propagation time of the sound wave in the double-layer medium, and then calculate the echo amplitude of each pixel point of the sound wave in the area to be detected. Since the sound wave will produce refraction attenuation at the medium interface when propagating in the double-layer medium, the refraction compensation expression is derived to improve the optimized total focusing algorithm to calculate the attenuation coefficient of the echo amplitude of each pixel point, so that the echo signal can more accurately characterize the defects of the test piece, generate a clear and visible defect image, and effectively improve the imaging quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 A flow chart of a double-layer medium defect imaging method with an improved total focusing algorithm provided by an embodiment of the present invention;

[0054] Figure 2 A schematic diagram of equipment connection for an ultrasonic detection signal acquisition test provided in an embodiment of the present invention;

[0055] Figure 3 A schematic diagram of the double-layer medium full-focus imaging provided by an embodiment of the present invention;

[0056] Figure 4 A module block diagram of a double-layer medium defect imaging system with an improved full focusing algorithm provided in an embodiment of the present invention.

[0057] In the accompanying drawings, the names of the components represented by the various marks are as follows:

[0058] 1. Computer; 2. Ultrasonic phased array detector; 3. Multi-element ultrasonic transducer; 4. Double-layer test piece. DETAILED DESCRIPTION

[0059] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0060] Since the imaging effect of the existing full focusing algorithm is not ideal when the echo signal is weak and the interface wave signal is too strong, there is a need for an imaging algorithm that can enhance the echo signal and reduce the interference of the interface wave signal to solve the problem that the defect imaging is not clear and the defect signal is covered by the interface wave signal.

[0061] like Figure 1-Figure 2 As shown, an embodiment of the present invention provides a double-layer medium defect imaging method with an improved total focusing algorithm, comprising the following steps:

[0062] Two pieces of 45# steel with a length of 300 mm, a width of 30 mm, and a thickness of 30 mm were selected as double-layer specimens 4, one of which was a good specimen as the first layer of the double-layer metal medium (i.e., double-layer specimen), and the other was a defective block as the second layer of the double-layer metal medium. Three groove defects were artificially made in the center of the thickness surface of the second layer of the specimen, wherein the length of the groove defect was 30 mm, the width was 2 mm, the depth was 4 mm, and the spacing between the three groove defects was 2 mm.

[0063] The multi-element ultrasonic transducer 3 is connected to the ultrasonic phased array detector 2, and the ultrasonic phased array detector is connected to the computer 1. The ultrasonic phased array detector 2 is a Vantage-64 ultrasonic phased array detector, which is composed of a Vantage-64 array element master and a Vantage-64 phased array signal acquisition unit; the multi-element ultrasonic transducer 3 is a 64-element ultrasonic transducer, which includes an ultrasonic probe, and the ultrasonic probe is composed of 64 chip array elements (that is, the number of phased array elements is 64).

[0064] The specimen parameters were recorded, including the size of the double-layer specimen, the depth of the first layer of the double-layer specimen, and the sound velocity of each layer of the double-layer specimen. The parameters of the 64-element ultrasonic transducer were recorded, including the geometric dimensions of 40 mm × 20 mm × 40 mm, the effective length of 32 mm, the element width of 0.4 mm, and the element spacing of 0.5 mm. The maximum protection voltage and sampling frequency of the ultrasonic probe were determined according to the specimen parameters.

[0065] The specimen parameters and the 64-element ultrasonic transducer parameters are input into the Vantage-64 phased array signal acquisition unit of the Vantage-64 ultrasonic phased array detector, and then the probe chip excitation number, probe chip excitation rule and probe chip receiving rule are set; wherein, the chip of the ultrasonic probe is cut into multiple small independent units, each unit is an array element, so the chip excitation number of each array element is set, and when the array element excites the ultrasonic signal, the corresponding ultrasonic signal is excited according to the probe chip set for each array element.

[0066] According to the probe chip excitation rule, an ultrasonic signal is excited into a preset double-layer test piece through a preset phased array detection component, a plurality of pixel points are set in a to-be-detected area set in the double-layer test piece, the ultrasonic signal generates a corresponding echo sound signal at each pixel point, and full-matrix data acquisition is performed on the echo sound signals corresponding to the plurality of pixel points according to the probe chip receiving rule, and an echo sound signal matrix is ​​formed by the plurality of echo sound signals corresponding to the plurality of pixel points;

[0067] Respectively converting a plurality of echo acoustic signals corresponding to a plurality of pixel points in the echo acoustic signal matrix into a plurality of echo digital signals, and forming a digital signal matrix with the plurality of echo digital signals corresponding to the plurality of pixel points;

[0068] The total sound propagation time expression is derived by Fermat's principle and Snell's theorem, an optimized total focusing algorithm is constructed by the total sound propagation time expression, and a refraction compensation expression is derived according to the law of refraction and reflection, and the optimized total focusing algorithm is optimized by the refraction compensation expression to obtain an improved total focusing algorithm;

[0069] The improved full focusing algorithm is used to calculate the echo digital signals corresponding to the multiple pixel points in the area to be detected in the digital signal matrix, respectively, to obtain the compensated echo amplitudes corresponding to the multiple pixel points, and to construct a defect image based on the compensated echo amplitudes corresponding to the multiple pixel points.

[0070] It should be understood that a coupling agent is also required. The 64-element ultrasonic transducer contacts the surface of the test piece through the coupling agent. The coupling agent provides good acoustic coupling between the ultrasonic transducer and the test piece, and reduces reflection and scattering of ultrasonic waves at the interface.

[0071] The Vantage-64 array element master includes components such as a transmit power controller, an encoder, a signal conversion unit, an I / O panel, and a PCI Express optical cable. The transmit power controller is used to adjust the power of the array element that transmits ultrasound. The encoder is used to calculate the position of each chip array element of the ultrasound probe. The I / O panel is used to transmit the collected echo signal (i.e., echo acoustic signal) to the computer. The Vantage-64 phased array signal acquisition unit is used to transmit the corresponding electrical signal to the 64-element ultrasonic transducer according to the probe chip excitation law, and make the 64-element ultrasonic transducer emit (i.e., excite) the corresponding ultrasonic signal; according to the probe chip receiving law, make the 64-element ultrasonic transducer collect (i.e., receive) the corresponding echo acoustic signal, and convert the echo acoustic signal into an echo electrical signal through the 64-element ultrasonic transducer, and receive the echo electrical signal converted by the 64-element ultrasonic transducer.

[0072] The 64-element ultrasonic transducer is a sensor used to convert acoustic signals and electrical signals into each other, and is connected to the Vantage-64 ultrasonic phased array detector through a dedicated cable. The 64-element ultrasonic transducer converts the collected echo acoustic signal into an echo electrical signal, and the analog signal (i.e., the echo electrical signal) is converted into a digital signal (i.e., the echo digital signal) through a signal conversion unit, and the digital signal is transmitted to the computer through a PCI express optical cable, and the digital signal is focused and imaged by the improved total focusing algorithm in the computer. This also includes importing the test piece parameters, 64-element ultrasonic transducer parameters, the number of probe chip excitations, the probe chip excitation law, and the probe chip receiving law into the improved total focusing algorithm, so that the improved total focusing algorithm can calculate the digital signal and then focus the image.

[0073] In the embodiment of the present invention, the ultrasonic detection cost is low, it is harmless to the human body and is convenient for on-site use. Each probe chip is controlled according to the set probe chip excitation law and probe chip receiving law, and the emission delay of each probe chip of the multi-element ultrasonic transducer can also be analyzed; the ultrasonic phased array detector and the multi-element ultrasonic transducer are used to complete the excitation processing of the ultrasonic signal and the collection processing of the echo signal. The total focusing algorithm is optimized according to the Fermat principle and Snell's theorem, so that the optimized total focusing algorithm can calculate the propagation time of the sound wave in the double-layer medium, and then calculate the echo amplitude of each pixel point of the sound wave in the area to be detected. Since the sound wave will produce refraction attenuation on the medium interface when propagating in the double-layer medium, the refraction compensation expression is derived to improve the optimized total focusing algorithm to calculate the attenuation coefficient of the echo amplitude of each pixel point, so that the echo signal can more accurately characterize the defects of the test piece, generate a clear and visible defect image, and effectively improve the imaging quality.

[0074] That is, the echo signal is enhanced by performing full matrix data acquisition on the echo signal and delaying and superimposing the echo amplitude of the echo signal collected by each array element corresponding to each pixel. By performing signal compensation on the echo signal and reducing the interference of the interface wave signal, the echo signal can more accurately characterize the defects of the test piece and generate a clear and visible defect image, thus solving the problem of unclear defect imaging caused by weak echo signal and defect signal being covered by the interface wave signal.

[0075] Preferably, the phased array detection assembly comprises an ultrasonic phased array detector and a multi-element ultrasonic transducer;

[0076] The method of exciting the ultrasonic signal into the preset double-layer test piece through the preset phased array detection component according to the probe wafer excitation rule is specifically as follows:

[0077] According to the probe wafer excitation rule, the electrical signal is transmitted to the preset multi-element ultrasonic transducer through the preset ultrasonic phased array detector;

[0078] The electrical signal is converted into an ultrasonic signal by the multi-element ultrasonic transducer, and the ultrasonic signal is excited into a preset double-layer test piece.

[0079] In the embodiment of the present invention, the electrical signal for exciting the ultrasonic signal is sequentially transmitted to the ultrasonic transducer through the probe chip excitation rule, so that the chip array element corresponding to the ultrasonic probe excites the ultrasonic signal to propagate in the double-layer test piece, thereby realizing ultrasonic detection.

[0080] Preferably, the multi-element ultrasonic transducer comprises a plurality of elements (i.e., 64 chip elements);

[0081] According to the probe chip excitation rule, an ultrasonic signal is excited into a preset double-layer specimen through a preset phased array detection component, and multiple pixel points are set in the to-be-detected area set in the double-layer specimen. The ultrasonic signal generates a corresponding echo sound signal at each pixel point, and full-matrix data acquisition is performed on the echo sound signals corresponding to the multiple pixel points according to the probe chip receiving rule, and the multiple echo sound signals corresponding to the multiple pixel points constitute an echo sound signal matrix, specifically:

[0082] According to the excitation sequence in the probe chip excitation rule, the first ultrasonic signal is excited into the preset double-layer test piece through the first array element, a plurality of pixel points are set in the to-be-detected area set in the double-layer test piece, the first ultrasonic signal generates a corresponding first echo sound signal at each pixel point, and according to the receiving sequence in the probe chip receiving rule, the first echo sound signals corresponding to the plurality of pixel points are respectively received through all array elements, so as to obtain the first echo sound signals corresponding to the plurality of pixel points in each array element;

[0083] According to the excitation order in the probe chip excitation rule, a second ultrasonic signal is excited into the double-layer test piece through a second array element, the second ultrasonic signal generates a corresponding second echo sound signal at each pixel point, and according to the receiving order in the probe chip receiving rule, the second echo sound signals corresponding to multiple pixel points are respectively received through all array elements, so as to obtain the second echo sound signals corresponding to the multiple pixel points in each array element;

[0084] And so on, until the last ultrasonic signal is excited into the double-layer specimen through the last array element according to the excitation sequence in the probe chip excitation rule, the last ultrasonic signal generates a corresponding last echo sound signal at each pixel point, and the last echo sound signals corresponding to multiple pixel points are respectively received by all array elements according to the receiving sequence in the probe chip receiving rule, and the last echo sound signals corresponding to the multiple pixel points in each array element are obtained, so that the echo sound signal matrix is ​​composed of the multiple echo sound signals corresponding to the multiple pixel points in each array element.

[0085] It should be understood that the signal matrix is ​​composed of a two-dimensional array, where the number of rows corresponds to the number of array elements, and the number of columns corresponds to the number of time sampling points. For example, there are N array elements, each of which samples at T time points according to the sampling frequency, then the data can be represented as a matrix of N rows and T columns. The probe chip receiving rule is: all array elements simultaneously receive the echo sound signal of the ultrasonic signal excited by the same array element. The 64-element ultrasonic transducer uses a surface array probe with 64 array elements (i.e., an 8×8 surface array probe) to excite the ultrasonic signal into the double-layer specimen.

[0086] Specifically, step 1, according to the excitation order of the probe wafer excitation rule, the i-th ultrasonic signal is excited into the double-layer specimen through the i-th array element, and the i-th ultrasonic signal is reflected by the double-layer specimen to generate the i-th echo sound signal (that is, the i-th ultrasonic signal generates the i-th echo sound signal at multiple pixel points in the to-be-detected area set in the double-layer specimen), wherein N array elements are 64 array elements (N=1, ..., i, j, ..., 64);

[0087] Step 2, collecting the ith echo sound signal corresponding to multiple pixel points in the to-be-detected area through 64 array elements respectively according to the receiving order of the probe chip receiving rule, obtaining the ith echo sound signal corresponding to the 64 array elements, and each array element saves the collected ith echo sound signal;

[0088] Step 3, repeating steps 1-2 until each array element excites an ultrasonic signal into the double-layer specimen, and each array element collects echo sound signals corresponding to the ultrasonic signals excited by each array element at multiple pixel points.

[0089] For further understanding, first, according to the excitation sequence of the probe chip excitation rule, the ultrasonic signal (i.e., the first ultrasonic signal) is excited into the double-layer specimen through the first array element (i.e., the first array element) of the ultrasonic probe, the ultrasonic signal is reflected by the double-layer specimen, and according to the receiving sequence of the probe chip receiving rule, the echo signal (i.e., the first echo sound signal) of the reflected ultrasonic signal is received and saved by all array elements; then, the corresponding ultrasonic signals are excited in turn through the remaining array elements until the last array element excites the corresponding ultrasonic signal (i.e., the last ultrasonic signal), all array elements receive the corresponding echo signals (i.e., the last echo sound signal) and save them, and a signal matrix containing 64×64=4096 echo sound signals is obtained.

[0090] Among them, multiple pixel points in the area to be detected are calculated by sampling frequency and the number of array elements, and the corresponding pixel point coordinates are obtained, and each ultrasonic signal and echo sound signal passes through multiple pixel points in the area to be detected.

[0091] In the embodiment of the present invention, each array element in the ultrasonic transducer array is traversed through full matrix data acquisition to generate a complete signal matrix. The signal data corresponding to each group of transmitting array elements and receiving array elements is used as an element of the signal matrix, providing rich data information. Multiple echo signals passing through the target pixel point in the area to be detected are collected to determine whether there is a defect at the corresponding pixel point based on the time it takes for the echo signal to propagate to all array elements and the echo amplitude at the corresponding pixel point.

[0092] Preferably, the multiple echo acoustic signals corresponding to the multiple pixel points in the echo acoustic signal matrix are converted into multiple echo digital signals respectively, and the multiple echo digital signals corresponding to the multiple pixel points constitute a digital signal matrix, specifically:

[0093] The multi-element ultrasonic transducer converts the multiple echo acoustic signals corresponding to the multiple pixel points in the echo acoustic signal matrix into the multiple echo electrical signals corresponding to the multiple pixel points, and transmits the multiple echo electrical signals corresponding to the multiple pixel points to the ultrasonic phased array detector;

[0094] The ultrasonic phased array detector converts the multiple echo electrical signals corresponding to the multiple pixel points into multiple echo digital signals corresponding to the multiple pixel points, and the multiple echo digital signals corresponding to the multiple pixel points form a digital signal matrix.

[0095] It should be understood that the multiple echo electrical signals corresponding to the multiple pixel points are converted into multiple echo digital signals corresponding to the multiple pixel points through the signal conversion unit of the ultrasonic phased array detector, the multiple echo digital signals corresponding to the multiple pixel points are output to the PCI express interface through the I / O panel, the multiple echo digital signals corresponding to the multiple pixel points are received from the PCI express interface through the PCI express optical cable and transmitted to the computer, and the multiple echo digital signals corresponding to the multiple pixel points are calculated and processed through the improved full focusing algorithm in the computer.

[0096] In an embodiment of the present invention, an echo signal reflected by a double-layer test piece is collected by an ultrasonic transducer and converted into an echo electrical signal for transmission to an ultrasonic phased array detector, which then converts the electrical signal into a digital signal that can be calculated and processed by an improved total focusing algorithm.

[0097] Preferably, if Figure 3 As shown, the double-layer specimen is composed of a first medium and a second medium, and the first medium and the second medium are between the interface. When an ultrasonic signal is excited into the double-layer specimen, the ultrasonic signal is refracted at the interface and propagates to each pixel point in the area to be detected, generating an echo signal at each pixel point, and the echo signal is refracted at the interface.

[0098] The total sound propagation time expression is derived by using Fermat's principle and Snell's theorem, specifically:

[0099] The sound propagation distance expression is derived according to the Fermat principle. The sound propagation distance expression is used to calculate the sound propagation distance of any echo digital signal corresponding to any pixel point in the area to be detected in the digital signal matrix, and the sound velocity of the double-layer specimen is substituted into the sound propagation distance expression for calculation to obtain the sound propagation time expression, which is:

[0100]

[0101] x=H tanθ i +(zH)tanθ s ,

[0102] x i =[(N+1) / 2-i]d,

[0103] Among them, T i is the sound propagation time, x i is the horizontal coordinate of the array element that excites the ultrasonic signal, x it is the horizontal coordinate of the refraction point of the ultrasonic signal at the interface, x is the horizontal coordinate of the pixel point, z is the vertical coordinate of the pixel point, H is the thickness of the first medium, c 1 is the first medium sound velocity, c 2is the second medium sound velocity, N is the number of array elements, d is the array element spacing, θ i is the incident angle of the ultrasonic signal, θ s is the refraction angle of ultrasonic signal;

[0104] The acoustic refractive index expression is derived according to Snell's theorem. The acoustic refractive index expression is used to calculate the acoustic refractive index of any echo digital signal corresponding to any pixel point in the area to be detected in the digital signal matrix. The acoustic refractive index expression is:

[0105]

[0106] Among them, n 12 is the acoustic refractive index;

[0107] The acoustic propagation time expression and the acoustic refractive index expression are combined to derive the total acoustic propagation time expression through the combined expression. The total acoustic propagation time expression is used to calculate the total acoustic propagation time of any echo digital signal corresponding to any pixel point in the area to be detected in the digital signal matrix. The total acoustic propagation time expression is:

[0108]

[0109] Among them, t ij (x,z) is the total sound propagation time, x j is the horizontal coordinate of the array element that collects the echo sound signal, x jr is the horizontal coordinate of the refraction point of the echo sound signal at the interface.

[0110] Preferably, the optimization total focusing algorithm is constructed by using the total sound propagation time expression, specifically:

[0111] The total sound propagation time expression is fused by the delay superposition rule to construct an echo amplitude expression, which is used to calculate the echo amplitude corresponding to each pixel point in the area to be detected. The echo amplitude expression is the optimized full focusing algorithm, and the echo amplitude expression is:

[0112]

[0113] Where I(x,z) is the echo amplitude, t ij (x,z) is the total sound propagation time.

[0114] It should be understood that the step of constructing an optimized total focusing algorithm through the total sound propagation time expression is to optimize the total focusing algorithm through the total sound propagation time expression on the basis of the total focusing algorithm.

[0115] Specifically, the ultrasonic signal is reflected and refracted once when passing through the first layer of medium, and then continues to propagate through the first layer of medium after refraction, and generates an echo sound signal when it reaches the pixel point. The echo sound signal passes through the first layer of medium from the second layer of medium and is refracted and reflected again. The propagation process includes multiple calculation parameters, namely: the number of phased array elements is N, the element width is a, the element spacing is d, the sound speed of the ultrasonic wave in the first layer of medium and the second layer of medium is c1, c2 respectively, the thickness of the first layer of medium is H, and the coordinate point of the i-th element is Y i For the ultrasonic signal emitted by the i-th array element, the refraction point from the first layer of medium into the second layer of medium in the double-layer specimen is S i , the incident angle is θ i , the refraction angle is θ s , any pixel point in the second layer of medium is F(x,z), x is the horizontal coordinate of pixel point F, z is the vertical coordinate of pixel point F, and the refraction point from the second layer of medium into the first layer of medium is S j , the coordinate point of the jth array element is Y j .

[0116] According to Fermat's principle, the sound beam always propagates along the path that takes the shortest time. It can be determined that the ultrasonic signal propagates from the i-th array element to the refraction point S i , and then refracted to the sound beam propagation path of pixel point F, and the sound propagation time expression T of the propagation process is obtained according to the sound beam propagation path i .

[0117] According to Snell's theorem (i.e., shell theorem): when the refracted wave is in the incident plane, the ratio of the sine of the incident angle to the sine of the refraction angle is a constant, i.e., the refractive index, expressed as n 12 , refractive index n 12 is the relative refractive index of the first medium and the second medium, and is proportional to the sound velocity of the corresponding medium, so the expression of the acoustic refractive index n is obtained 12 .

[0118] The simultaneous expression of acoustic propagation time and acoustic refractive index n 12 Calculate and get the time when the ultrasonic signal emitted by the i-th array element reaches the pixel F as T i Similarly, the time it takes for the echo signal of the ultrasonic signal emitted by the i-th array element to reach the j-th array element from the pixel point F through the reflection point is T j . Thus, the ultrasonic signal is obtained from the i-th array element to the pixel point F, generating the echo sound signal, and the time for the echo sound signal to reach the j-th array element from the pixel point F, and then the total sound propagation time expression t corresponding to the ultrasonic signal and the echo sound signal is derived ij (x,z).

[0119] The total sound propagation time of the echo sound signals received by the 64 array elements at the pixel point F is calculated by the total sound propagation time expression. The total sound propagation time of the 64 echo sound signals is calculated by the delay superposition rule to obtain the echo amplitude expression I(x,z).

[0120] It should be understood that the array element spacing d is the distance between the centers of two adjacent array elements, that is, the distance between the array elements head to head. Since the coordinates of each pixel point can be calculated by the sampling frequency and the number of array elements, the coordinates of each array element and the coordinates of each pixel point in the area to be detected are known quantities. The total acoustic propagation time of the echo acoustic signal is the sum of the acoustic propagation time of the ultrasonic signal and the acoustic propagation time of the echo acoustic signal.

[0121] According to the reciprocity principle: the emission and reception process of sound waves is reversible, that is, t ij (x,z)=t ji (x,z). For the same pixel F, when the ith array element transmits an ultrasonic signal and propagates to the pixel F, the total acoustic propagation time generated by the echo acoustic signal generated and received by the jth array element is equal to the total acoustic propagation time generated by the jth array element transmitting an ultrasonic signal and propagating to the pixel F, the echo acoustic signal generated and received by the ith array element. Therefore, when calculating the total acoustic propagation time for the same pixel, a large amount of calculation can be reduced and the calculation rate can be improved.

[0122] The delay superposition rule is: according to the propagation speed of ultrasound in the specimen and the arrival time of the echo signal, all echo signals at the corresponding pixel points are superimposed according to a certain delay amount.

[0123] In the embodiment of the present invention, since the distances of the echo acoustic signal to different receiving array elements are different, there will be a time delay, so the echo signals at the same pixel point received by each array element should be delayed and superimposed by the delay superposition rule to ensure the consistency of the receiving time. The total focusing algorithm is optimized according to the Fermat principle and Snell's theorem, so that the optimized total focusing algorithm can perform total focusing imaging on the double-layer medium specimen.

[0124] Preferably, the refraction compensation expression is derived according to the law of refraction and reflection, specifically:

[0125] The refraction compensation expression is derived according to the law of refraction and reflection. The refraction compensation expression is used to calculate the refracted longitudinal wave energy (i.e., the refraction compensation coefficient) of the ultrasonic signal in the double-layer specimen. The refraction compensation expression is:

[0126]

[0127] Among them, T L (θ 1 ,θ L ,θ s) is the refraction compensation coefficient, ρ 1 is the density of the first medium, ρ 2 is the density of the second medium, c L is the shear wave speed, c s is the longitudinal wave speed, θ s is the incident angle of the longitudinal wave, θ L is the incident angle of shear wave, c 1 is the first medium sound velocity, θ 1 is the critical angle of the first medium, and · is the multiplication.

[0128] Specifically, according to the law of refraction and reflection, when the incident angle of the sound beam is between the first critical angle and the second critical angle, the longitudinal wave will simultaneously generate a refracted shear wave and a refracted longitudinal wave when incident, wherein the energy distribution of the refracted longitudinal wave satisfies the initial projection compensation expression, which is:

[0129]

[0130] Among them, sinθ L ; 0; -cosθ represent the components in the x, y, and z directions respectively. Since the imaging result is a two-dimensional plane, the -cosθ component in the z direction is 0, so the simplified projection compensation expression is:

[0131]

[0132] It should be understood that in the field of ultrasound, the first critical angle and the second critical angle generally refer to the situation where the sound beam is refracted when it propagates between different media. These critical angles have an important impact on the propagation and imaging of ultrasound. The first critical angle is: when ultrasound passes through a medium, such as water to air or water to human tissue, refraction occurs; the first critical angle means that when the ultrasound incident angle reaches a certain value, the refracted wave propagates along the medium on the interface at an angle of 90 degrees. At this time, the incident angle is called the first critical angle; exceeding this angle, the ultrasound will not be able to penetrate the medium, and total reflection will occur. The second critical angle: when ultrasound is emitted from one medium to another, if the incident angle is greater than the first critical angle, total reflection will occur; when the incident angle increases to another critical value, that is, the second critical angle, the refracted wave will be able to pass through the boundary and propagate into the second medium.

[0133] In the embodiment of the present invention, since the ultrasonic signal will be refracted and reflected at the interface when propagating in the double-layer medium, resulting in energy loss of the echo signal, the optimized total focusing algorithm is improved by deriving a projection compensation expression through the law of refraction and reflection to enhance the energy of the echo signal and make the defect image clearer.

[0134] Preferably, the optimized total focusing algorithm is optimized by the refraction compensation expression to obtain an improved total focusing algorithm, specifically:

[0135] The refraction compensation expression and the echo amplitude expression are combined to obtain a compensation echo amplitude expression, which is used to calculate the compensation echo amplitude corresponding to each pixel point in the area to be detected. The compensation echo amplitude expression is an improved full focusing algorithm, and the compensation echo amplitude expression is:

[0136]

[0137] Where I'(x,z) is the compensation echo amplitude, t ij (x,z) is the total sound propagation time, T L (θ 1 ,θ L ,θ s ) is the refraction compensation coefficient.

[0138] Preferably, the improved full focusing algorithm is used to calculate the echo digital signals corresponding to the multiple pixel points in the area to be detected in the digital signal matrix to obtain the compensated echo amplitudes corresponding to the multiple pixel points, specifically:

[0139] The echo digital signal corresponding to any pixel point in the to-be-detected area in the digital signal matrix is ​​calculated by the improved full-focusing algorithm to obtain a compensated echo amplitude of any pixel point;

[0140] The above steps are repeated until the echo digital signals corresponding to all the pixel points in the detection area in the digital signal matrix are calculated to obtain the compensated echo amplitudes corresponding to the multiple pixel points.

[0141] It should be understood that S1, calculating the echo amplitude of the echo sound signal of the ultrasonic signal emitted by the first array element at the first pixel point (i.e. calculating the echo amplitude of the first echo sound signal respectively stored in 64 array elements), includes first calculating the total sound propagation time of the first echo sound signal in each array element through the echo amplitude expression to obtain 64 total sound propagation times of the first echo sound signal, and then respectively calculating the echo amplitude of the echo sound signal of the 64 total sound propagation times of the first echo sound signal at the first pixel point to obtain 64 first echo amplitudes, and calculating the 64 first echo amplitudes through the delay superposition rule to obtain the first total echo amplitude of the first pixel point;

[0142] S2, repeat S1, calculate the total echo amplitudes of the second echo sound signal to the 64th echo sound signal in sequence, calculate the average of the 64 total echo amplitudes, and obtain the echo amplitude corresponding to the first pixel;

[0143] S3, performing projection compensation on the echo amplitude corresponding to the first pixel point through a projection compensation expression to obtain a compensated echo amplitude corresponding to the first pixel point;

[0144] S4, repeat S1-S3 to calculate the compensation echo amplitudes corresponding to the remaining pixel points, until the compensation echo amplitudes corresponding to all pixel points in the area to be detected are calculated, and the compensation echo amplitudes corresponding to the plurality of pixel points are obtained.

[0145] In the embodiment of the present invention, the amplitude of the echo signals at all the pixel points in the detection area is calculated to obtain an amplitude image capable of characterizing the defects of the double-layer test piece.

[0146] Preferably, after the step of constructing a defect image according to the echo amplitudes corresponding to the plurality of pixel points, the method further includes judging defects of the double-layer test piece according to the defect image, specifically:

[0147] When the amplitudes of the defect and normal structure echoes are different, it is judged that there is a defect; since the defect part causes strong reflection or scattering of the ultrasonic wave, these defects usually appear as bright areas in the defect image, and their amplitudes are significantly higher than the amplitudes of the surrounding normal defect-free areas.

[0148] It should be understood that the interference of the interface echo will cause bright areas in the defect image of the defect-free area of ​​the double-layer specimen, which will lead to misjudgment of defects. Therefore, refraction compensation is performed on the echo amplitude of each pixel point to reduce the interference of the interface echo on the echo signal at each pixel point.

[0149] In the embodiment of the present invention, a pixel point in the defect image whose amplitude brightness is higher than the amplitude brightness of nearby pixels is determined as a defect.

[0150] like Figure 4 As shown, an embodiment of the present invention provides a double-layer medium defect imaging system with an improved full focusing algorithm, comprising:

[0151] A signal acquisition module, used for setting a probe chip excitation rule and a probe chip receiving rule, exciting an ultrasonic signal to a preset double-layer test piece through a preset phased array detection component according to the probe chip excitation rule, setting a plurality of pixel points in a to-be-detected area set in the double-layer test piece, the ultrasonic signal generates a corresponding echo sound signal at each pixel point, and performing full-matrix data acquisition on the echo sound signals corresponding to the plurality of pixel points according to the probe chip receiving rule, so that an echo sound signal matrix is ​​formed by the plurality of echo sound signals corresponding to the plurality of pixel points;

[0152] A signal conversion module, used for converting a plurality of echo acoustic signals corresponding to a plurality of pixel points in the echo acoustic signal matrix into a plurality of echo digital signals, wherein the plurality of echo digital signals corresponding to the plurality of pixel points constitute a digital signal matrix;

[0153] An algorithm improvement module is used to derive an expression of total sound propagation time through Fermat's principle and Snell's theorem, construct an optimized total focusing algorithm through the expression of total sound propagation time, derive a refraction compensation expression according to the law of refraction and reflection, optimize the optimized total focusing algorithm through the refraction compensation expression, and obtain an improved total focusing algorithm;

[0154] An image construction module is used to calculate the echo digital signals corresponding to multiple pixel points in the area to be detected in the digital signal matrix through the improved full focusing algorithm, obtain the compensated echo amplitudes corresponding to the multiple pixel points, and construct a defect image according to the compensated echo amplitudes corresponding to the multiple pixel points.

[0155] The above-mentioned double-layer medium defect imaging system with improved total focusing algorithm can refer to the implementation content and beneficial effects of the double-layer medium defect imaging method with improved total focusing algorithm described above, which will not be repeated here.

[0156] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0157] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A double-layer medium defect imaging method with an improved total focusing algorithm, characterized in that: The steps include: A probe chip excitation rule and a probe chip receiving rule are set, and an ultrasonic signal is excited into a preset double-layer test piece through a preset phased array detection component according to the probe chip excitation rule, and a plurality of pixel points are set in a to-be-detected area set in the double-layer test piece, and the ultrasonic signal generates a corresponding echo sound signal at each pixel point, and full-matrix data acquisition is performed on the echo sound signals corresponding to the plurality of pixel points according to the probe chip receiving rule, and an echo sound signal matrix is ​​formed by the plurality of echo sound signals corresponding to the plurality of pixel points; Respectively converting a plurality of echo acoustic signals corresponding to a plurality of pixel points in the echo acoustic signal matrix into a plurality of echo digital signals, and forming a digital signal matrix with the plurality of echo digital signals corresponding to the plurality of pixel points; The total sound propagation time expression is derived by Fermat's principle and Snell's theorem, an optimized total focusing algorithm is constructed by the total sound propagation time expression, and a refraction compensation expression is derived according to the law of refraction and reflection, and the optimized total focusing algorithm is optimized by the refraction compensation expression to obtain an improved total focusing algorithm, including: The total sound propagation time expression is fused by the delay superposition rule to construct an echo amplitude expression, which is used to calculate the echo amplitude corresponding to each pixel point in the area to be detected. The echo amplitude expression is the optimized full focusing algorithm, and the echo amplitude expression is: Where I(x,z) is the echo amplitude, t ij (x,z) is the total sound propagation time; The refraction compensation expression and the echo amplitude expression are combined to obtain a compensation echo amplitude expression, which is used to calculate the compensation echo amplitude corresponding to each pixel point in the area to be detected. The compensation echo amplitude expression is an improved full focusing algorithm, and the compensation echo amplitude expression is: Where I'(x,z) is the compensation echo amplitude, t ij (x,z) is the total sound propagation time, and the refraction compensation expression is: Among them, T L (θ1,θ L ,θ s ) is the refraction compensation coefficient, ρ1 is the first medium density, ρ2 is the second medium density, c L is the shear wave speed, c s is the longitudinal wave speed, θ s is the incident angle of the longitudinal wave, θ L is the incident angle of the shear wave, c1 is the sound velocity of the first medium, θ1 is the critical angle of the first medium; The improved full focusing algorithm is used to calculate the echo digital signals corresponding to the multiple pixel points in the area to be detected in the digital signal matrix, respectively, to obtain the compensated echo amplitudes corresponding to the multiple pixel points, and to construct a defect image based on the compensated echo amplitudes corresponding to the multiple pixel points.

2. The double-layer medium defect imaging method according to claim 1, characterized in that: The phased array detection component includes an ultrasonic phased array detector and a multi-element ultrasonic transducer; The method of exciting the ultrasonic signal into the preset double-layer test piece through the preset phased array detection component according to the probe wafer excitation rule is specifically as follows: According to the probe wafer excitation rule, the electrical signal is transmitted to the preset multi-element ultrasonic transducer through the preset ultrasonic phased array detector; The electrical signal is converted into an ultrasonic signal by the multi-element ultrasonic transducer, and the ultrasonic signal is excited into a preset double-layer test piece.

3. The double-layer medium defect imaging method according to claim 2, characterized in that: The multi-element ultrasonic transducer comprises a plurality of array elements; According to the probe chip excitation rule, an ultrasonic signal is excited into a preset double-layer specimen through a preset phased array detection component, and multiple pixel points are set in the to-be-detected area set in the double-layer specimen. The ultrasonic signal generates a corresponding echo sound signal at each pixel point, and full-matrix data acquisition is performed on the echo sound signals corresponding to the multiple pixel points according to the probe chip receiving rule, and the multiple echo sound signals corresponding to the multiple pixel points constitute an echo sound signal matrix, specifically: According to the excitation sequence in the probe chip excitation rule, the first ultrasonic signal is excited into the preset double-layer test piece through the first array element, a plurality of pixel points are set in the to-be-detected area set in the double-layer test piece, the first ultrasonic signal generates a corresponding first echo sound signal at each pixel point, and according to the receiving sequence in the probe chip receiving rule, the first echo sound signals corresponding to the plurality of pixel points are respectively received through all array elements, so as to obtain the first echo sound signals corresponding to the plurality of pixel points in each array element; According to the excitation order in the probe chip excitation rule, a second ultrasonic signal is excited into the double-layer test piece through a second array element, the second ultrasonic signal generates a corresponding second echo sound signal at each pixel point, and according to the receiving order in the probe chip receiving rule, the second echo sound signals corresponding to multiple pixel points are respectively received through all array elements, so as to obtain the second echo sound signals corresponding to the multiple pixel points in each array element; And so on, until the last ultrasonic signal is excited into the double-layer specimen through the last array element according to the excitation sequence in the probe chip excitation rule, the last ultrasonic signal generates a corresponding last echo sound signal at each pixel point, and the last echo sound signals corresponding to multiple pixel points are respectively received by all array elements according to the receiving sequence in the probe chip receiving rule, and the last echo sound signals corresponding to the multiple pixel points in each array element are obtained, so that the echo sound signal matrix is ​​composed of the multiple echo sound signals corresponding to the multiple pixel points in each array element.

4. The double-layer medium defect imaging method according to claim 2, characterized in that: The multiple echo acoustic signals corresponding to the multiple pixel points in the echo acoustic signal matrix are respectively converted into multiple echo digital signals, and the multiple echo digital signals corresponding to the multiple pixel points constitute a digital signal matrix, specifically: The multi-element ultrasonic transducer converts the multiple echo acoustic signals corresponding to the multiple pixel points in the echo acoustic signal matrix into the multiple echo electrical signals corresponding to the multiple pixel points, and transmits the multiple echo electrical signals corresponding to the multiple pixel points to the ultrasonic phased array detector; The ultrasonic phased array detector converts the multiple echo electrical signals corresponding to the multiple pixel points into multiple echo digital signals corresponding to the multiple pixel points, and the multiple echo digital signals corresponding to the multiple pixel points form a digital signal matrix.

5. The double-layer medium defect imaging method according to claim 1, characterized in that: The total sound propagation time expression is derived by using Fermat's principle and Snell's theorem, specifically: The sound propagation distance expression is derived according to the Fermat principle. The sound propagation distance expression is used to calculate the sound propagation distance of any echo digital signal corresponding to any pixel point in the area to be detected in the digital signal matrix, and the sound velocity of the double-layer specimen is substituted into the sound propagation distance expression for calculation to obtain the sound propagation time expression, which is: x=H tanθi+(zH)tanθs, x i =[(N+1) / 2-i]d, Among them, T i is the sound propagation time, x i is the horizontal coordinate of the array element that excites the ultrasonic signal, x it is the horizontal coordinate of the refraction point of the ultrasonic signal at the interface, x is the horizontal coordinate of the pixel point, z is the vertical coordinate of the pixel point, H is the thickness of the first medium, c1 is the sound velocity of the first medium, c2 is the sound velocity of the second medium, N is the number of array elements, d is the array element spacing, θ i is the incident angle of the ultrasonic signal, θ s is the refraction angle of ultrasonic signal; The acoustic refractive index expression is derived according to Snell's theorem. The acoustic refractive index expression is used to calculate the acoustic refractive index of any echo digital signal corresponding to any pixel point in the area to be detected in the digital signal matrix. The acoustic refractive index expression is: Among them, n 12 is the acoustic refractive index; The acoustic propagation time expression and the acoustic refractive index expression are combined to derive the total acoustic propagation time expression through the combined expression. The total acoustic propagation time expression is used to calculate the total acoustic propagation time of any echo digital signal corresponding to any pixel point in the area to be detected in the digital signal matrix. The total acoustic propagation time expression is: Among them, t ij (x,z) is the total sound propagation time, x j is the horizontal coordinate of the array element that collects the echo sound signal, x jr is the horizontal coordinate of the refraction point of the echo sound signal at the interface.

6. A double-layer medium defect imaging system with an improved full focusing algorithm, characterized in that: include: A signal acquisition module, used for setting a probe chip excitation rule and a probe chip receiving rule, exciting an ultrasonic signal to a preset double-layer test piece through a preset phased array detection component according to the probe chip excitation rule, setting a plurality of pixel points in a to-be-detected area set in the double-layer test piece, the ultrasonic signal generates a corresponding echo sound signal at each pixel point, and performing full-matrix data acquisition on the echo sound signals corresponding to the plurality of pixel points according to the probe chip receiving rule, so that an echo sound signal matrix is ​​formed by the plurality of echo sound signals corresponding to the plurality of pixel points; A signal conversion module, used for converting a plurality of echo acoustic signals corresponding to a plurality of pixel points in the echo acoustic signal matrix into a plurality of echo digital signals, wherein the plurality of echo digital signals corresponding to the plurality of pixel points constitute a digital signal matrix; The algorithm improvement module is used to derive the total sound propagation time expression by Fermat's principle and Snell's theorem, construct an optimized total focusing algorithm by the total sound propagation time expression, derive the refraction compensation expression according to the law of refraction and reflection, optimize the optimized total focusing algorithm by the refraction compensation expression, and obtain an improved total focusing algorithm, including: The total sound propagation time expression is fused by the delay superposition rule to construct an echo amplitude expression, which is used to calculate the echo amplitude corresponding to each pixel point in the area to be detected. The echo amplitude expression is the optimized full focusing algorithm, and the echo amplitude expression is: Where I(x,z) is the echo amplitude, t ij (x,z) is the total sound propagation time; The refraction compensation expression and the echo amplitude expression are combined to obtain a compensation echo amplitude expression, which is used to calculate the compensation echo amplitude corresponding to each pixel point in the area to be detected. The compensation echo amplitude expression is an improved full focusing algorithm, and the compensation echo amplitude expression is: Where I'(x,z) is the compensation echo amplitude, t ij (x,z) is the total sound propagation time, and the refraction compensation expression is: Among them, T L (θ1,θ L ,θ s ) is the refraction compensation coefficient, ρ1 is the first medium density, ρ2 is the second medium density, c L is the shear wave speed, c s is the longitudinal wave speed, θ s is the incident angle of the longitudinal wave, θ L is the incident angle of the shear wave, c1 is the sound velocity of the first medium, θ1 is the critical angle of the first medium; An image construction module is used to calculate the echo digital signals corresponding to multiple pixel points in the area to be detected in the digital signal matrix through the improved full focusing algorithm, obtain the compensated echo amplitudes corresponding to the multiple pixel points, and construct a defect image according to the compensated echo amplitudes corresponding to the multiple pixel points.

7. The double-layer medium defect imaging system according to claim 6, characterized in that: The phased array detection component includes an ultrasonic phased array detector and a multi-element ultrasonic transducer; In the signal acquisition module, the ultrasonic signal is excited into the preset double-layer test piece through the preset phased array detection component according to the probe wafer excitation rule, specifically: According to the probe wafer excitation rule, the electrical signal is transmitted to the preset multi-element ultrasonic transducer through the preset ultrasonic phased array detector; The electrical signal is converted into an ultrasonic signal by the multi-element ultrasonic transducer, and the ultrasonic signal is excited into a preset double-layer test piece.

8. The double-layer medium defect imaging system according to claim 7, characterized in that: The signal conversion module is specifically used for: The plurality of echo acoustic signals corresponding to the plurality of pixel points in the echo acoustic signal matrix are respectively converted into a plurality of echo electrical signals corresponding to the plurality of pixel points by the multi-element ultrasonic transducer, and the plurality of echo electrical signals corresponding to the plurality of pixel points are transmitted to the ultrasonic phased array detector; The ultrasonic phased array detector converts the multiple echo electrical signals corresponding to the multiple pixel points into multiple echo digital signals corresponding to the multiple pixel points, and the multiple echo digital signals corresponding to the multiple pixel points form a digital signal matrix.

Images