Method for measuring ultrahigh frequency attenuation coefficient of material

Abstract

The invention discloses a method for measuring an ultrahigh frequency attenuation coefficient of a material, and relates to the technical field of ultrasonic detection. According to the method for measuring the ultrahigh-frequency attenuation coefficient of the material, the measured material is used as a part of the ultrahigh-frequency ultrasonic device, so that adverse effects caused by short working distance and large ultrasonic attenuation of the ultrahigh-frequency ultrasonic device in the measuring process of the ultrahigh-frequency attenuation coefficient are overcome. In the process of measuring the ultra-high frequency attenuation coefficient, diffusion attenuation of an ultra-high frequency ultrasonic device is calibrated by utilizing the sound field characteristics of a circular plane ultrasonic transducer, ultrasonic transmission loss of interfaces of different materials is calibrated according to an ultra-high frequency acoustic transmission line theory, and the actual condition of ultrasonic propagation in the materials is fully considered. And a more accurate ultrahigh frequency attenuation coefficient can be obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of ultrasonic detection, and in particular relates to a method for measuring the ultra-high frequency attenuation coefficient of a material. Background Art

[0002] Ultrahigh frequency ultrasound usually operates at a frequency of 100MHz to 1GHz or higher, and has a wide range of applications in medicine, industry, materials and other fields. In the medical field, it is widely used in skin imaging, ophthalmic imaging, vascular imaging, etc. In the industrial field, ultrahigh frequency ultrasound is used for material inspection, non-destructive testing and welding quality control, and can detect tiny defects and surface defects. The ultrahigh frequency scanning acoustic microscope with ultrahigh frequency ultrasonic transducer as the core component has become a powerful tool for non-destructive testing, biological microstructure imaging, biological cell research, and material performance evaluation. However, as the ultrasonic frequency increases, the ultrasound will show an exponential attenuation, which brings great limitations to the preparation process of ultrahigh frequency ultrasonic devices (such as the lens focusing material of the transducer) and ultrasonic imaging applications. Therefore, it is particularly important to determine the attenuation coefficient in the ultrahigh frequency range.

[0003] At present, there are generally two methods for detecting ultrasonic attenuation coefficient. One is the transmission method, which requires two ultrasonic transducers, one for transmission and one for reception, to perform experiments and calculate the attenuation coefficient by changing the thickness of the material; the other is the reflection method, which only requires one ultrasonic transducer to receive multiple ultrasonic echoes to calculate the attenuation coefficient. However, the ultrasonic attenuation coefficients calculated by these two methods have large errors. Summary of the invention

[0004] In order to solve the above problems existing in the prior art, the present invention provides a method for measuring the ultra-high frequency attenuation coefficient of a material. The technical problem to be solved by the present invention is achieved by the following technical solutions:

[0005] The present invention provides a method for measuring the ultra-high frequency attenuation coefficient of a material, comprising:

[0006] Step 1: Using the material to be tested as the substrate material to prepare an ultra-high frequency ultrasonic device;

[0007] Step 2: Based on the generation and reception of sound wave signals by the ultra-high frequency ultrasonic device, the total attenuation of the material under test is obtained according to the primary echo signal and the secondary echo signal reflected by the bottom of the substrate layer;

[0008] Step 3: Calculate the diffusion attenuation of the ultra-high frequency ultrasonic device based on the acoustic field characteristics of the circular planar ultrasonic transducer;

[0009] Step 4: Calculate the transmission loss of the primary echo signal and the secondary echo signal during the propagation process according to the ultra-high frequency acoustic transmission line theory;

[0010] Step 5: Calculate the ultra-high frequency attenuation coefficient of the material under test according to the total attenuation of the material under test, the diffusion attenuation of the ultra-high frequency ultrasonic device and the transmission loss.

[0011] Compared with the prior art, the present invention has the following beneficial effects:

[0012] The method for determining the ultra-high frequency attenuation coefficient of a material of the present invention uses the material to be measured as a part of an ultra-high frequency ultrasonic device, thereby overcoming the adverse effects of the ultra-high frequency ultrasonic device's short working distance and large ultrasonic attenuation on the ultra-high frequency attenuation coefficient determination process. In the process of determining the ultra-high frequency attenuation coefficient, the diffusion attenuation of the ultra-high frequency ultrasonic device is calibrated using the acoustic field characteristics of a circular planar ultrasonic transducer, and the ultrasonic transmission loss of the interface of different materials is calibrated according to the ultra-high frequency acoustic transmission line theory, fully considering the actual situation of ultrasonic propagation in the material, and a more accurate ultra-high frequency attenuation coefficient can be obtained.

[0013] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the following specifically cites a preferred embodiment and describes it in detail with the accompanying drawings as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a schematic diagram of a method for determining the ultra-high frequency attenuation coefficient of a material provided by an embodiment of the present invention;

[0015] Figure 2 is a schematic structural diagram of an ultra-high frequency ultrasonic device provided by an embodiment of the present invention;

[0016] Figure 3 It is a schematic diagram of the difference between the primary echo spectrum and the secondary echo spectrum within a selected frequency range provided by an example of an embodiment of the present invention;

[0017] Figure 4 is a schematic diagram of the difference between the diffusion attenuation of a secondary echo signal and the diffusion attenuation of a primary echo signal provided by an example of an embodiment of the present invention;

[0018] Figure 5 is a schematic diagram of transmission loss of two interfaces provided by an example of an embodiment of the present invention;

[0019] Figure 6 It is a schematic diagram of an example of the ultra-high frequency attenuation coefficient of a material under test provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0020] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, a method for measuring the ultra-high frequency attenuation coefficient of a material proposed in accordance with the present invention is described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0021] The above and other technical contents, features and effects of the present invention are clearly presented in the following detailed description of the specific implementation modes in conjunction with the accompanying drawings. Through the description of the specific implementation modes, the technical means and effects adopted by the present invention to achieve the predetermined purpose can be more deeply and specifically understood. However, the attached drawings are only for reference and explanation purposes and are not used to limit the technical solutions of the present invention.

[0022] The embodiment of the present invention provides a method for determining the ultra-high frequency attenuation coefficient of a material, see Figure 1 , Figure 1 Schematic diagram of a method for determining the ultra-high frequency attenuation coefficient of a material provided by an embodiment of the present invention. Figure 1 As shown, the method for determining the ultra-high frequency attenuation coefficient of a material in this embodiment includes:

[0023] Step 1: Use the material to be tested as the substrate layer material to prepare an ultra-high frequency ultrasonic device.

[0024] Since the working distance of the ultra-high frequency ultrasound device is shortened due to the increase in the attenuation coefficient, and the ultrasonic signal will diverge to the surroundings when the ultrasound propagates in the material, causing energy attenuation, in this embodiment, the material to be tested is used as a part of the ultra-high frequency ultrasonic device, which overcomes the adverse effects of the short working distance of the ultra-high frequency ultrasonic device and the large ultrasonic attenuation on the ultra-high frequency attenuation coefficient measurement process.

[0025] In this embodiment, the ultra-high frequency ultrasonic device is a circular planar ultrasonic transducer. Figure 2 , Figure 2 is a schematic diagram of the structure of an ultra-high frequency ultrasonic device provided by an embodiment of the present invention, such as Figure 2 As shown, the ultra-high frequency ultrasonic device of this embodiment includes a substrate layer 1, a first buffer layer 2, a bottom electrode 3, a second buffer layer 4, a piezoelectric layer 5 and a top electrode 6 stacked in sequence from bottom to top. The projection of the piezoelectric layer 5 on the second buffer layer 4 is circular.

[0026] Step 2: Based on the generation and reception of sound wave signals by the ultra-high frequency ultrasonic device, the total attenuation of the material under test is obtained according to the primary echo signal and the secondary echo signal reflected from the bottom of the substrate layer.

[0027] In an optional embodiment, step 2 includes:

[0028] Step 2.1: Use a pulse signal transceiver to make the ultra-high frequency ultrasonic device generate a sound wave signal, and collect a primary echo signal and a secondary echo signal reflected from the bottom of the substrate layer of the ultra-high frequency ultrasonic device.

[0029] Optionally, a pulse signal transceiver can be connected to the bottom electrode 3 and the top electrode 6 of the ultra-high frequency ultrasonic device. The electrical excitation signal generated by the pulse signal transceiver is converted into an ultrasonic signal, i.e., a sound wave signal, through the piezoelectric layer 5. The sound wave signal propagates in the substrate layer 1 and is reflected at the bottom to form an echo signal. The echo signal is converted into an electrical signal through the piezoelectric layer 5. The pulse signal transceiver receives the electrical signal and transmits it to the oscilloscope for display.

[0030] The primary echo signal is an echo signal after the sound wave signal is reflected once at the bottom of the substrate layer 1 , and the secondary echo signal is an echo signal after the sound wave signal is reflected twice at the bottom of the substrate layer 1 .

[0031] It should be noted that when collecting the primary echo signal and the secondary echo signal, it is ensured that the selected time interval includes all the echo signals.

[0032] Step 2.2: Perform Fourier transform on the primary echo signal and the secondary echo signal to obtain the corresponding primary echo spectrum and secondary echo spectrum.

[0033] In this embodiment, the corresponding frequency spectrum obtained by performing Fourier transform on the two echo signals reflects the corresponding amplitude of the sound wave signal at different frequencies. In the frequency spectrum, the amplitude is expressed in dB. It should be noted that when performing Fourier transform, the time width is equal.

[0034] Step 2.3: Determine the echo center frequency according to the primary echo spectrum and the secondary echo spectrum, select a frequency range according to the echo center frequency, and make a difference between the primary echo spectrum and the secondary echo spectrum within the selected frequency range to obtain the total attenuation of the measured material.

[0035] Step 3: Calculate the diffusion attenuation of the ultra-high frequency ultrasonic device based on the acoustic field characteristics of the circular planar ultrasonic transducer.

[0036] Diffusion attenuation mainly refers to the phenomenon that when the sound wave signal propagates in the medium, the sound intensity is weakened only due to the expansion of the ultrasonic front area. In this process, the total sound energy remains unchanged, and this type of attenuation has nothing to do with the attenuation of the material.

[0037] In an optional embodiment, step 3 includes:

[0038] Step 3.1: According to the propagation distance of the acoustic wave signal and the selected frequency range, the diffusion attenuation of the primary echo signal and the diffusion attenuation of the secondary echo signal are calculated.

[0039] In this embodiment, the diffusion attenuation is calculated according to the following formula:

[0040] C={[cos(2π / s)-J1(2π / s)] 2 +[sin(2π / s)-J1(2π / s)] 2} 0.5 ;

[0041] Where s = x*v L / f*a 2 ;

[0042] Where J1 is the order Bessel function, x is the propagation distance of the sound wave signal, v is L is the longitudinal wave velocity of the material being tested, f is the selected frequency range, and a is the effective radius of the ultra-high frequency ultrasonic device.

[0043] In this embodiment, the propagation distance of the acoustic wave signal is related to the thickness of the material being measured. For the primary echo signal, the propagation distance of the acoustic wave signal is twice the thickness of the material being measured, and for the secondary echo signal, the propagation distance of the acoustic wave signal is four times the thickness of the material being measured. The effective radius of the ultra-high frequency ultrasonic device is the effective radius of the piezoelectric layer material.

[0044] Step 3.2: Subtract the diffusion attenuation of the secondary echo signal from the diffusion attenuation of the primary echo signal to obtain the diffusion attenuation of the ultra-high frequency ultrasonic device.

[0045] In this embodiment, the diffusion attenuation of the ultra-high frequency ultrasonic device can be expressed as: C2-C1, C1 is the diffusion attenuation of the primary echo signal, and C2 is the diffusion attenuation of the secondary echo signal.

[0046] Step 4: Calculate the transmission loss of the primary echo signal and the secondary echo signal during the propagation process according to the ultra-high frequency acoustic transmission line theory.

[0047] It should be noted that if the size of the two different materials is much larger than the wavelength of the ultra-high frequency ultrasound, and the incident direction is perpendicular, then the acoustic impedance calculation formula is: Z = ρ × C, ρ, C are material density and sound speed respectively, and the simplest sound pressure transmission and reflection formulas can be used to calculate the sound pressure transmission coefficient and the sound pressure reflection coefficient, and then the ultrasonic energy loss at the material interface can be calculated. However, in the ultra-high frequency range (> 100MHz), when the material thickness is equivalent to the wavelength of the ultra-high frequency ultrasound, the material acoustic impedance required will have errors, especially near the resonant frequency of the piezoelectric film in the ultra-high frequency device. Since the thickness of the piezoelectric film is about half the length of the ultra-high frequency ultrasound, the above method for calculating the characteristic impedance of the material is no longer applicable, and the acoustic impedance of the material is related to the frequency of the ultrasound. Therefore, in this embodiment, the acoustic transmission line theory is introduced to calculate the acoustic impedance at the boundary of two different materials.

[0048] In this embodiment, the acoustic transmission line in the ultra-high frequency ultrasonic device is divided into four layers, namely the rear-end medium of the ultra-high frequency ultrasonic device (not limited to air, water, etc.), the material to be measured, the piezoelectric material and the front-end medium of the ultra-high frequency ultrasonic device (in this embodiment, the material of the front-end medium is the same as that of the rear-end medium). In the ultra-high frequency ultrasonic device, the thickness of the buffer layer (the first buffer layer 2 and the second buffer layer 4) and the electrode (the bottom electrode 3 and the top electrode 6) is much smaller than the ultrasonic length, and this part can be ignored.

[0049] In an optional embodiment, step 4 includes:

[0050] Step 4.1: According to the acoustic impedance of the material under test and the acoustic impedance of the rear-end medium of the ultra-high frequency ultrasonic device during the test, the reflection coefficient of the interface between the material under test and the rear-end medium is calculated.

[0051] In this embodiment, the primary echo signal includes a primary reflection of the interface between the back-end medium and the material to be measured. Then, the reflection coefficient of the interface between the material to be measured and the back-end medium is calculated according to the following formula:

[0052]

[0053] Where Z1 is the acoustic impedance of the material being measured, and Z2 is the acoustic impedance of the back-end medium.

[0054] Step 4.2: Calculate the reflection coefficient of the material interface between the material under test and the piezoelectric layer based on the acoustic impedance of the material under test, the acoustic impedance of the material of the piezoelectric layer of the ultra-high frequency ultrasonic device, and the acoustic impedance of the front-end medium of the ultra-high frequency ultrasonic device during the test.

[0055] In this embodiment, the secondary echo signal includes two reflections at the interface between the back-end medium and the material under test, the reflection coefficient of which is the same as R1, and one reflection at the material interface between the material under test and the piezoelectric layer. Then, the reflection coefficient of the material interface between the material under test and the piezoelectric layer is calculated according to the following formula:

[0056]

[0057] in, Z in is the equivalent acoustic impedance of the piezoelectric layer and the outside air,

[0058] Where, Z1 is the acoustic impedance of the material being measured, Z3 is the acoustic impedance of the material of the piezoelectric layer of the ultra-high frequency ultrasonic device, Z4 is the acoustic impedance of the front-end medium, l is the thickness of the piezoelectric layer, v L is the longitudinal wave velocity of the material being tested, f is the selected frequency range, and j is the imaginary unit.

[0059] Step 4.3: According to the reflection coefficient of the interface between the material under test and the back-end medium and the reflection coefficient of the interface between the material under test and the piezoelectric layer, the transmission loss of the primary echo signal and the secondary echo signal during the propagation process is determined.

[0060] Optionally, the transmission loss of the interface during the propagation of ultrasound can be obtained by performing a logarithmic transformation on the sound pressure and then converting it into dB form. In this embodiment, the transmission loss of the interface between the measured material and the rear-end medium is expressed as The transmission loss at the material interface between the material under test and the piezoelectric layer is expressed as Then, the transmission loss of a single echo signal during propagation can be expressed as The transmission loss of the secondary echo signal during propagation can be expressed as

[0061] Step 5: Calculate the UHF attenuation coefficient of the material under test based on the total attenuation of the material under test, the diffusion attenuation of the UHF ultrasonic device, and the transmission loss.

[0062] In this embodiment, after the diffusion attenuation and transmission loss of the ultra-high frequency ultrasonic device are removed from the total attenuation of the measured material, the attenuation coefficient of the measured material itself is calculated. Specifically, the ultra-high frequency attenuation coefficient of the measured material is calculated according to the following formula:

[0063]

[0064] Among them, B1 is the primary echo spectrum within the selected frequency range, B2 is the secondary echo spectrum within the selected frequency range, is the transmission loss at the interface between the material being tested and the back-end medium, is the transmission loss of the material interface between the material under test and the piezoelectric layer, C1 is the diffusion attenuation of the primary echo signal, C2 is the diffusion attenuation of the secondary echo signal, and L is the thickness of the material under test.

[0065] The method for measuring the ultra-high frequency attenuation coefficient of a material in an embodiment of the present invention uses the material to be measured as a part of an ultra-high frequency ultrasonic device, thereby overcoming the adverse effects of the ultra-high frequency ultrasonic device's short working distance and large ultrasonic attenuation on the ultra-high frequency attenuation coefficient measurement process. In the process of measuring the ultra-high frequency attenuation coefficient, the diffusion attenuation of the ultra-high frequency ultrasonic device is calibrated using the acoustic field characteristics of a circular planar ultrasonic transducer, and the ultrasonic transmission loss at the interface of different materials is calibrated according to the ultra-high frequency acoustic transmission line theory, fully considering the actual situation of ultrasonic propagation in the material, and a more accurate ultra-high frequency attenuation coefficient can be obtained.

[0066] Further, the method for measuring the ultra-high frequency attenuation coefficient of a material of the present invention is described by using a specific example. The material to be measured is single crystal silicon, and the structure of an ultra-high frequency ultrasonic device is first prepared using the single crystal silicon. Figure 2 As shown, the material of the first buffer layer 2 is silicon dioxide, the material of the bottom electrode 3 is platinum, the material of the second buffer layer 4 is lithium niobate, the material of the piezoelectric layer 5 is lead zirconate titanate, and the material of the top electrode 6 is gold. Secondly, based on the generation and reception of sound wave signals by the ultra-high frequency ultrasonic device, the collected primary echo signal and secondary echo signal reflected from the bottom of the substrate layer of the ultra-high frequency ultrasonic device are subjected to Fourier transform to obtain the corresponding spectrum, and the echo center frequency is determined to be 150MHz, and the selected frequency range is 140-160MHz. The primary echo spectrum B1 and the secondary echo spectrum B2 are subtracted within the selected frequency range to obtain the total attenuation B1-B2 of the material under test, see Figure 3 , Figure 3 This is a schematic diagram of the difference between the primary echo spectrum and the secondary echo spectrum within a selected frequency range provided by an example of an embodiment of the present invention. Then, the diffusion attenuation C1 of the primary echo signal and the diffusion attenuation C2 of the secondary echo signal are calculated according to the diffusion attenuation formula, and the diffusion attenuation of the secondary echo signal and the diffusion attenuation of the primary echo signal are subtracted to obtain the diffusion attenuation C2-C1 of the ultra-high frequency ultrasonic device. Please refer to Figure 4 , Figure 4 This is a schematic diagram of the difference between the diffusion attenuation of the secondary echo signal and the diffusion attenuation of the primary echo signal provided by an embodiment of the present invention. Then, the reflection coefficient R1 of the interface between the measured material and the back-end medium and the reflection coefficient R2 of the interface between the measured material and the piezoelectric layer material are calculated according to the reflection coefficient calculation formula, and the logarithmic transformation is performed and then converted into dB form to obtain the transmission loss of the interface between the measured material and the back-end medium. Transmission loss at the interface between the material under test and the piezoelectric layer See also Figure 5 , Figure 5 is a schematic diagram of the transmission loss of two interfaces provided by an embodiment of the present invention. Finally, according to the calculation formula of the ultra-high frequency attenuation coefficient, after the diffusion attenuation and transmission loss of the ultra-high frequency ultrasonic device are removed from the total attenuation of the measured material, the attenuation coefficient α of the measured material itself is calculated, see Figure 6 , Figure 6 It is a schematic diagram of an example of the ultra-high frequency attenuation coefficient of a material under test provided by an embodiment of the present invention.

[0067] 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 are intended to cover non-exclusive inclusion, so that an article or device including a series of elements includes not only those elements, but also other elements not explicitly listed. In the absence of further restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the article or device including the elements. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The orientation or position relationship indicated by "upper", "lower", "left", "right", etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0068] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A method for determining the ultra-high frequency attenuation coefficient of a material, characterized in that: include: Step 1: Using the material to be tested as the substrate material to prepare an ultra-high frequency ultrasonic device; Step 2: Based on the generation and reception of sound wave signals by the ultra-high frequency ultrasonic device, the total attenuation of the material under test is obtained according to the primary echo signal and the secondary echo signal reflected by the bottom of the substrate layer; Step 3: Calculate the diffusion attenuation of the ultra-high frequency ultrasonic device based on the acoustic field characteristics of the circular planar ultrasonic transducer; Step 4: Calculate the transmission loss of the primary echo signal and the secondary echo signal during the propagation process according to the ultra-high frequency acoustic transmission line theory; Step 5: Calculate the ultra-high frequency attenuation coefficient of the material under test according to the total attenuation of the material under test, the diffusion attenuation of the ultra-high frequency ultrasonic device and the transmission loss.

2. The method for measuring the ultra-high frequency attenuation coefficient of a material according to claim 1, characterized in that: The ultra-high frequency ultrasonic device is a circular planar ultrasonic transducer, and comprises a substrate layer, a first buffer layer, a bottom electrode, a second buffer layer, a piezoelectric layer and a top electrode which are stacked in sequence from bottom to top.

3. The method for measuring the ultra-high frequency attenuation coefficient of a material according to claim 1, characterized in that: The step 2 comprises: Step 2.1: using a pulse signal transceiver to enable the ultra-high frequency ultrasonic device to generate a sound wave signal, and collecting a primary echo signal and a secondary echo signal reflected from the bottom of the substrate layer of the ultra-high frequency ultrasonic device; Step 2.2: Performing Fourier transform on the primary echo signal and the secondary echo signal to obtain corresponding primary echo spectrum and secondary echo spectrum; Step 2.3: Determine the echo center frequency according to the primary echo spectrum and the secondary echo spectrum, select a frequency range according to the echo center frequency, and make a difference between the primary echo spectrum and the secondary echo spectrum within the selected frequency range to obtain the total attenuation of the measured material.

4. The method for measuring the ultra-high frequency attenuation coefficient of a material according to claim 1, characterized in that: The step 3 comprises: Step 3.1: Calculate the diffusion attenuation of the primary echo signal and the diffusion attenuation of the secondary echo signal according to the propagation distance of the acoustic wave signal and the selected frequency range; Step 3.2: Subtract the diffusion attenuation of the secondary echo signal from the diffusion attenuation of the primary echo signal to obtain the diffusion attenuation of the ultra-high frequency ultrasonic device.

5. The method for measuring the ultra-high frequency attenuation coefficient of a material according to claim 4, characterized in that: The diffusion attenuation is calculated according to the following formula: C={[cos(2π / s)-J1(2π / s)] 2 +[sin(2π / s)-J1(2π / s)] 2 } 0.5 ; Where s = x*v L / f*a 2 ; Where J1 is the order Bessel function, x is the propagation distance of the sound wave signal, v is L is the longitudinal wave velocity of the material being tested, f is the selected frequency range, and a is the effective radius of the ultra-high frequency ultrasonic device.

6. The method for measuring the ultra-high frequency attenuation coefficient of a material according to claim 1, characterized in that: The step 4 comprises: Step 4.1: Calculate the reflection coefficient of the interface between the material under test and the rear-end medium according to the acoustic impedance of the material under test and the acoustic impedance of the rear-end medium of the ultra-high frequency ultrasonic device during the test; Step 4.2: Calculate the reflection coefficient of the material interface between the material under test and the piezoelectric layer according to the acoustic impedance of the material under test, the acoustic impedance of the material of the piezoelectric layer of the ultra-high frequency ultrasonic device, and the acoustic impedance of the front-end medium of the ultra-high frequency ultrasonic device during the test; Step 4.3: Determine the transmission loss of the primary echo signal and the secondary echo signal during propagation according to the reflection coefficient of the interface between the material under test and the back-end medium and the reflection coefficient of the interface between the material under test and the piezoelectric layer.

7. The method for measuring the ultra-high frequency attenuation coefficient of a material according to claim 6, characterized in that: The reflection coefficient of the interface between the measured material and the back-end medium is calculated according to the following formula: Where Z1 is the acoustic impedance of the material being measured, and Z2 is the acoustic impedance of the back-end medium.

8. The method for measuring the ultra-high frequency attenuation coefficient of a material according to claim 7, characterized in that: The reflection coefficient of the material interface between the material under test and the piezoelectric layer is calculated according to the following formula: in, Where, Z1 is the acoustic impedance of the material being measured, Z3 is the acoustic impedance of the material of the piezoelectric layer of the ultra-high frequency ultrasonic device, Z4 is the acoustic impedance of the front-end medium, l is the thickness of the piezoelectric layer, v L is the longitudinal wave velocity of the material being tested, f is the selected frequency range, and j is the imaginary unit.

9. The method for measuring the ultra-high frequency attenuation coefficient of a material according to claim 8, characterized in that: The transmission loss of the primary echo signal during propagation is expressed as The transmission loss of the secondary echo signal during propagation is expressed as in, is the transmission loss at the interface between the material being tested and the back-end medium, is the transmission loss of the material interface between the material under test and the piezoelectric layer, 10. The method for measuring the ultra-high frequency attenuation coefficient of a material according to claim 1, characterized in that: The ultra-high frequency attenuation coefficient of the material under test is calculated according to the following formula: Among them, B1 is the primary echo spectrum within the selected frequency range, B2 is the secondary echo spectrum within the selected frequency range, is the transmission loss at the interface between the material being tested and the back-end medium, is the transmission loss of the material interface between the material under test and the piezoelectric layer, C1 is the diffusion attenuation of the primary echo signal, C2 is the diffusion attenuation of the secondary echo signal, and L is the thickness of the material under test.

Images