CN114449431B - A method and system for non-destructive testing of loudspeaker diaphragms using terahertz waves - Google Patents

Abstract

The invention relates to a method and a system for carrying out nondestructive testing on a loudspeaker diaphragm by using terahertz waves. The method comprises the following steps: the terahertz transceiver integrated equipment comprises terahertz transceiver integrated equipment, a gain antenna and a control computer. The terahertz wave is emitted by the emission source, and is converged by the gain antenna and directly irradiated to the surface of the loudspeaker. And the terahertz detector measures the intensity of the reflected terahertz waves and performs time-frequency analysis. The frequency of each point on the surface of the speaker having the maximum energy is obtained, imaging is performed, and the position of the damage or abnormal shape of the speaker is detected from the frequency abnormal point on the image. The present invention does not require expensive ultrasound detection equipment and highly radioactive radiographic equipment. The vibration frequency of each point on the surface of the terahertz wave is obtained by transmitting terahertz waves to a loudspeaker, collecting echo data, analyzing and carrying out time-frequency analysis on phase information. And determining the position of the loudspeaker surface with damage or abnormal shape according to the abnormal frequency occurrence position in the frequency image.

Description

A method and system for non-destructive testing of loudspeaker diaphragms using terahertz waves

technical field

The present invention relates to the field of nondestructive testing of loudspeaker diaphragms using terahertz waves. Specifically, a method and system for non-destructive testing using terahertz waves are provided.

Background technique

With the development of my country's industry and the continuous improvement of the technical level, the requirements for the organizational state and structure of the finished product on the product line are gradually increasing. In this context, non-destructive testing technology has entered the field of vision of the majority of researchers. Non-destructive testing technology refers to using the changes of heat, sound, light, electricity, magnetism and other reactions caused by abnormal structure or defects of materials, combined with advanced Processing methods and special equipment for testing. The main non-destructive testing methods today are the use of ultrasound or X-rays. However, in recent decades, with the in-depth research of researchers in the fields of photonics and electronics, the radiation and detection technology of terahertz waves has also been developed rapidly. Its wavelength is in the range of 0.03mm to 3mm. Compared with ultrasonic nondestructive testing, terahertz wave has higher frequency and the frequency domain coverage of terahertz wave equipment is wider. More detailed object conditions can be obtained by analyzing the terahertz echoes. In addition, terahertz waves have longer wavelengths and are safer than X-ray NDT. This property allows terahertz waves to penetrate the surface material to detect subtle structural changes in the speaker. These advantages make terahertz waves have broad application prospects in the field of non-destructive testing.

Existing non-destructive testing methods are mainly performed by injecting ultrasonic waves into the speaker or using X-rays to irradiate the speaker. Ultrasonic testing has high requirements on the shape of the object to be tested and the grain size of the defect location. The disadvantage of the X-ray detection method is that its radiation is too strong and it is not easy to control and use.

SUMMARY OF THE INVENTION

In view of the above technical deficiencies, the purpose of the present invention is to provide a method and system for nondestructive testing using terahertz waves. After the terahertz wave is reflected on the surface of the speaker, the phase information in the echo can accurately represent the subtle distance change between the speaker and the wave source. Then, the phase information can be analyzed by Hilbert-Huang transform to change the instantaneous frequency and instantaneous amplitude of each point on the speaker surface. By calculating the amplitude, the frequency of each point of the speaker and its corresponding energy can be obtained at this moment. . In addition, the image is drawn by combining the vibration frequency of each point with the maximum energy and the position information of each point. Find the position of abnormal vibration frequency from the image to determine the position of the abnormal defect point of the speaker.

The technical scheme adopted by the present invention to solve its technical problems is:

A method for non-destructive testing of loudspeaker diaphragms using terahertz waves, comprising the following steps:

The terahertz wave with a preset frequency is emitted by the integrated terahertz transceiver device, so that the terahertz wave passes through the gain antenna and irradiates the speaker to be tested along the set propagation direction, and causes it to interfere with the vibration signal of the speaker diaphragm, resulting in interference. echo signal;

By moving the displacement stage, the position of the speaker fixed on it can be adjusted in real time, so that the speaker can move according to the preset step size and trajectory in the plane where the diaphragm is located, so that the terahertz wave scanning irradiation range can cover the entire diaphragm;

Set the sampling times, control the integrated terahertz transceiver device to collect and store a series of echo intensity sequences of terahertz waves corresponding to each sampling point of the diaphragm through the vibration interference of the speaker diaphragm;

Analyze the value of the echo intensity sequence, obtain the echo phase information, and analyze the maximum energy and frequency of each sampling point on the surface of the speaker diaphragm according to the Hilbert-Huang transform;

Visualize the frequency-coordinate map of the maximum energy of each sampling point of the speaker diaphragm, and determine whether the speaker diaphragm to be tested has defects and the location of the defects.

The preset frequency satisfies Shannon's sampling theorem, and is multiplied according to the overtone frequency of the signal to be measured.

The movement of the displacement stage is two-dimensional movement in horizontal and vertical directions in the plane where the speaker diaphragm is located.

The preset track moves row by row and column by column, so that the terahertz wave scans each sampling point on the surface of the speaker diaphragm row by row and column by column.

The analysis of the maximum energy frequency of each sampling point on the surface of the speaker diaphragm according to the Hilbert-Huang transform includes:

1) The terahertz echo signal is decomposed by using the empirical mode decomposition EMD method, and it is decomposed into the form of a combination of multiple empirical mode functions IMFs and residuals. The specific expression is as follows:

Among them, ε(t) is the terahertz echo signal, i is the number of empirical modal components, IMF _i is the intrinsic empirical modal component, and r _K is the residual residual term after subtracting each empirical modal component from the original signal;

2) Hilbert transform is performed on each empirical mode component IMF, and the IMF component is set as x(t), then its Hilbert transform is H[x(t)], and the local estimation is transformed into a global estimation :

Among them, τ refers to the overall time interval of the signal where x(t) is located;

3) The analytical signal of the real-valued function of the echo signal is obtained, and the specific complex number expression is as follows:

为x(t)的解析信号，

是u(t)的希尔伯特变换后的函数H[x(t)]，解析信号

的模和幅角代表二维信号的幅度和相位，即回波信号的瞬时频率和瞬时幅值；where u(t) is a real-valued function,

is the analytical signal of x(t),

is the Hilbert transformed function H[x(t)] of u(t), the analytical signal

The modulus and amplitude of , represent the amplitude and phase of the two-dimensional signal, that is, the instantaneous frequency and instantaneous amplitude of the echo signal;

4) Take the maximum instantaneous amplitude as the maximum energy, obtain the frequency of the maximum energy of the signal at this moment, and regard the frequency as the vibration frequency of this point on the surface of the speaker diaphragm, and use it to make a frequency-coordinate map of the maximum energy.

On the maximum energy frequency spectrum of each sampling point of the speaker diaphragm, determine whether the speaker diaphragm to be tested is damaged or abnormal in shape according to the energy frequency difference between any point and the surrounding points.

A system for non-destructive testing of loudspeaker diaphragms using terahertz waves, comprising: a terahertz transceiver integrated device, a gain antenna, a displacement platform, a control computer, and a speaker to be tested;

The integrated terahertz transceiver device includes a vector network analyzer, a spread spectrum module, and a frequency expander connected in sequence; the waveguide output port of the frequency expander is connected to a gain antenna; the gain antenna is in the shape of a horn, and the opening faces the speaker to be tested The vector network analyzer is connected to the control computer; the terahertz wave is sent out by the vector network analyzer, and after passing through the gain antenna, the beam is directly irradiated to the surface of the speaker, and at the same time, the vector network analyzer as a terahertz detector collects the reflected terahertz wave echo strength sequence signal;

The displacement platform is a two-dimensional platform, including a servo motor, a driver, a transverse linear motion module and a longitudinal linear motion module. The speaker is fixed on the transverse motion module, and the transverse linear motion module and the longitudinal linear motion module are driven by the servo motor. The movement module moves, thereby adjusting the position of the speaker; the driver is connected with the control computer through the communication interface;

The control computer includes a storage unit and a processing unit, the storage unit stores a program, and the processing unit loads the program to execute the method steps described above, so as to detect defects or abnormal shapes and positions on the surface of the speaker diaphragm.

The surface of the speaker is covered with tin foil to improve the transmittance of echo signals.

The present invention has the following beneficial effects and advantages:

1. The present invention provides a new non-destructive testing method, which utilizes the high spatial resolution of terahertz waves to achieve fine measurement of loudspeakers and determine defects on their surfaces.

2. The present invention adopts the method of phase recovery, which can accurately measure the subtle distance change between the loudspeaker and the detection device, and then determine the defect position on the loudspeaker surface and the frequency change with the maximum energy around it.

3. The present invention uses a displacement translation stage to move the loudspeaker. Since the emission source of the terahertz wave is fixed, the use of this translation stage can cover the terahertz wave to various positions on the speaker surface.

4. The present invention can perform detection without contacting the speaker, and the radiation energy of the terahertz wave is low, which is safe and reliable.

Description of drawings

Figure 1 is a schematic diagram of non-destructive testing of speakers using terahertz waves.

Figure 2 is a flow chart of the present invention.

Fig. 3 is the detection result of the present invention when the loudspeaker is playing 150Hz pure tone; (a) the vibration amplitude image of the loudspeaker diaphragm; (b) the phase image of the loudspeaker diaphragm vibration; (c) each point of the loudspeaker has maximum energy frequency image.

Fig. 4 is the detection result of the present invention when the loudspeaker is playing 400Hz pure tone; (a) the vibration amplitude image of the loudspeaker diaphragm, (b) the phase image of the loudspeaker diaphragm vibration (c) the maximum energy of each point of the loudspeaker frequency image.

Among them, 1 is a terahertz transceiver integrated device, a terahertz emission source and a terahertz detector, 2 is a gain antenna, 3 is a speaker, 4 is a displacement translation stage, and 5 is an electronic computer.

Detailed ways

In order to make the above objects, features and advantages of the present invention more clearly understood, the specific implementation methods of the present invention will be described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the invention. Therefore, the present invention is not limited by the specific implementation disclosed below.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terms used herein in the description of the invention are for the purpose of describing particular implementations only and are not intended to limit the invention.

FIG. 1 is a schematic diagram of the system structure of the present invention. The invention uses terahertz waves to perform non-destructive testing on the speaker diaphragm. The system includes: a terahertz transceiver integrated device 1 , a gain antenna 2 and a sound source speaker 3 , a displacement translation stage 4 and an electronic computer 5 . The integrated terahertz transceiver 1 includes a vector network analyzer, a spread spectrum module, and a frequency expander connected in sequence; the waveguide output port of the frequency expander is connected to a booster antenna; The vector network analyzer is connected to the control computer 5 . The terahertz wave is emitted by the vector network analyzer, and after passing through the gain antenna, the beam is condensed and directly irradiates the surface of the speaker 3 . At the same time, the vector network analyzer, which is used as a terahertz detector, measures the intensity of the reflected terahertz wave, and the control computer 5 detects the defect position on the surface of the speaker through the principle of time-frequency analysis. By moving the displacement stage, the position of the speaker fixed on it is adjusted in real time, so that the speaker moves according to the preset step size and trajectory in the plane where the diaphragm is located, so that the terahertz wave scanning irradiation range can cover the entire diaphragm.

Figure 2 is a flow chart of the present invention. By emitting terahertz waves to the speaker whose surface is covered with tin foil, the terahertz waves are reflected on the surface of the speaker. In order to ensure that the information on the speaker surface is collected, a displacement translation stage is used to move the speaker. After analyzing and imaging the collected terahertz echo signal, the vibration frequency with the maximum energy of each point on the speaker surface is extracted, so as to determine the defect position on the speaker surface, including the following processes:

1. a method of using terahertz wave to carry out nondestructive testing to loudspeaker diaphragm, is characterized in that, comprises the following steps

Step 1. Build a transmitting system capable of transmitting terahertz waves. Connecting the VNA with a spread spectrum module and frequency extender increases its frequency range to 220-325GHz.

Step 2. A gain antenna with a corresponding frequency range is installed at the front end of the frequency expander, so that the terahertz waves emitted by the vector network analyzer (VNA) are concentrated on the surface of the speaker.

Step 3. Set the parameters in the vector network analyzer so that its sampling frequency is not lower than 6 times the maximum frequency of the sound played by the speaker under test.

Step 4. Start the speaker to play the sound and simultaneously start the data acquisition program and the displacement translation stage control program to collect the terahertz echoes.

Step 5: Analyze the echo signal and obtain the phase information of the signal; analyze the phase information through the Hilbert-Huang transformation to obtain the vibration frequency with the maximum energy at each point on the speaker surface.

The detailed steps are as follows:

Step 1. Build a transmitting system capable of transmitting terahertz waves. Connecting the VNA with a spread spectrum module and frequency extender increases its frequency range to 220-325GHz.

Step 2. A gain antenna with a corresponding frequency range is installed at the front end of the frequency expander, so that the terahertz waves emitted by the vector network analyzer (VNA) are concentrated on the speaker.

Step 3. Set the parameters in the vector network analyzer so that its sampling frequency is not lower than 6 times the maximum frequency of the sound played by the measured speaker.

3.1. The setting of the sampling frequency of the vector network analyzer, including:

a. Set the parameters in the vector network analyzer, including the number of sampling points n and the IF bandwidth m;

b. Calculate the sampling frequency:

Among them, the scanning time t is calculated by the vector network analyzer according to the number of sampling points n and the intermediate frequency bandwidth m;

c. If the calculated sampling frequency f _s satisfies the Shannon sampling theorem, stop setting the parameters, otherwise return to step a to reset the parameters.

The Shannon sampling theorem formula is as follows:

结果的小数部分，N则是整数部分，f_max是待测回波信号中的扬声器播放声音的最大频率。这样就能够测出扬声器播放的声音中的最大频率。然而在扬声器工作中经常出现所播放声音的泛音。泛音的波长通常为基音的整数分之一，也就是说泛音的频率会是扬声器播放的声音频率的整数倍。其中二次泛音以及三次泛音最为常见。因此本实施例中为了要测得扬声器发生主要三次泛音的区域需要将矢量网络分析仪的采样频率设置到扬声器播放声音的最大频率的6倍以上。Among them, f _{s, min} is the lowest frequency of f _s , B is the bandwidth of the sound signal to be measured, and M is the

The fractional part of the result, N is the integer part, and _fmax is the maximum frequency of the sound played by the speaker in the echo signal to be measured. This allows you to measure the maximum frequency in the sound played by the speaker. However, overtones of the sound being played are often present in loudspeaker operation. The wavelength of the overtone is usually an integer fraction of the fundamental tone, which means that the frequency of the overtone will be an integer multiple of the sound frequency played by the speaker. The second and third overtones are the most common. Therefore, in this embodiment, in order to measure the area where the loudspeaker produces main third overtone, it is necessary to set the sampling frequency of the vector network analyzer to be more than 6 times the maximum frequency of the sound played by the loudspeaker.

Step 4. Start the control program of the displacement translation stage, control the vector network analyzer to transmit terahertz waves to the speaker, collect the terahertz echo signals, and store them in the form of scattering S parameters;

4.1. When collecting data on each point on the speaker surface, fix the speaker on the displacement translation stage, so that the speaker moves two-dimensionally in both horizontal and vertical directions on the plane where its diaphragm is located according to the preset trajectory. The translation stage control program sets it to move 1mm in 1s, and the overall movement range covers the area of the speaker diaphragm. The preset track moves row by row and column by column, so that the laser scans each sampling point on the speaker diaphragm row by row and column by column.

Step 5: Analyze the terahertz echo signal, obtain phase information, and analyze the frequency with the maximum energy at each point on the speaker surface through the Hilbert-Huang transform.

5.1. The frequency with the maximum energy at each point on the speaker surface is analyzed through the Hilbert-Huang transform, including:

The terahertz echo signal is decomposed using the proposed empirical mode decomposition (EMD) algorithm in the Hilbert-Huang transform, and decomposed into the form of a combination of multiple empirical mode functions (IMFs) and residuals . The specific expression is shown in the following formula.

In formula (3), ε(t) is the echo signal of the terahertz wave, IMF _i is the K intrinsic empirical mode components, and r _K is the residual residual term after subtracting the IMF from the original signal. When performing empirical mode decomposition, first determine the upper and lower envelopes of the original signal of the terahertz echo. After the upper and lower envelopes are determined, take the average of the ordinates of two points on the two lines with the same abscissa but different ordinates, and then obtain the mean line of the two envelopes. The intermediate signal obtained after subtracting the mean line from the original signal of the terahertz wave needs to be judged by IMF. If the intermediate signal is in the entire data segment, the number of extreme points and the number of zero-crossing points must be equal or the difference cannot exceed one at most. In addition, the average value of the upper envelope formed by the local maximum points and the lower envelope formed by the local minimum points at any time is zero, that is, the upper and lower envelopes are relative to the time axis. local symmetry. If the intermediate signal satisfies the above conditions, the intermediate signal is an IMF component of the original signal of the terahertz wave. When performing the next IMF decomposition, the original echo signal can be decomposed by repeating the operation after subtracting the obtained IMF component from the original echo signal.

After each IMF component of the original signal is obtained, Hilbert transform is performed on each IMF component. Let the IMF component be x(t) and its Hilbert transform to be H[x(t)]

The significance of the Hilbert transform realized by formula (4) is to convert a local estimate into a global estimate. From a physical point of view, τ refers to the overall time interval of the signal where x(t) is located.

换句话说，希尔伯特是将原始信号通过一个滤波器或者一个转向器。从物理意义上来说，一个实值函数的解析信号可以表示为实值函数本身与其希尔伯特变换的和。具体表现形式如下所示。It can be seen from equation (4) that the result of the Hilbert transform is the output of the linear time-invariant system of the input x(t). The impulse response of the system is

In other words, Hilbert is passing the original signal through a filter or a diverter. In a physical sense, the analytic signal of a real-valued function can be represented as the sum of the real-valued function itself and its Hilbert transform. The specific form is as follows.

为u(t)的解析信号。

是u(t)的希尔伯特变换后的函数。在此过程中，解析信号的实部与虚部的功率谱相同而且其自相关函数相同。希尔伯特变换的实际意义在于将接收到的实信号转换成解析信号。在该变换过程中，一维的信号变成了二维复平面上的信号。复数的模和幅角代表二维信号的幅度和相位，从而得出信号的瞬时频率和瞬时幅值。在得到回波信号的瞬时频率和瞬时幅值后即可得出该信号在该时刻所含有的具有最大能量的频率。本发明将该频率视作扬声器振膜表面该点的主要振动频率并存储。In formula (5), u(t) is a real-valued function,

is the analytical signal of u(t).

is the Hilbert transformed function of u(t). In this process, the real and imaginary parts of the analytical signal have the same power spectrum and the same autocorrelation function. The practical significance of the Hilbert transform is to convert the received real signal into an analytical signal. During this transformation, the one-dimensional signal becomes a signal on the two-dimensional complex plane. The modulus and amplitude of the complex numbers represent the amplitude and phase of the two-dimensional signal, and thus the instantaneous frequency and instantaneous amplitude of the signal. After obtaining the instantaneous frequency and instantaneous amplitude of the echo signal, the frequency with the maximum energy contained in the signal at this moment can be obtained. The present invention regards this frequency as the main vibration frequency of this point on the surface of the speaker diaphragm and stores it.

When the frequency with the maximum energy of each point on the diaphragm is obtained, the frequency data is combined with the position of the point and imaged with this data. If the diaphragm of the loudspeaker is damaged or incomplete in shape, the generated image can judge the quality or damage of the diaphragm at the actual location through the abnormal frequency that occurs abnormally in a certain area. Generally, the vibration frequency with the greatest energy at the damaged location will suddenly change, and this will cause the surrounding area to also have this frequency change. Therefore, if there is a sudden change of vibration frequency in the image, it can indicate that the shape of the speaker has changed at that position.

Fig. 3 is the detection result of the present invention when the loudspeaker is playing 150Hz pure tone; wherein, (a) is the vibration amplitude image of the loudspeaker diaphragm; (b) is the phase image of the vibration of the loudspeaker diaphragm; Vibration center frequency image of the point. Fig. 4 is the detection result of the present invention when the loudspeaker is playing 400Hz pure tone; (a) is the vibration amplitude image of the loudspeaker diaphragm, (b) is the phase image of the loudspeaker diaphragm vibration, and (c) is the vibration of each point of the loudspeaker In the center frequency image, it can be seen from (c) of Figure 3 and (c) of Figure 4 that the yellow dots are distributed in the frequency abnormality when the speaker is working, and it can be determined that this is the abnormal position.

The above are the main features of the present invention. It should be pointed out that for those skilled in the art, without departing from the principles of the present invention, several improvements and modifications can be made. These improvements and modifications should be It is regarded as the protection scope of the present invention.

Claims (8)

1. a method of using terahertz wave to carry out nondestructive testing to loudspeaker diaphragm, is characterized in that, comprises the following steps: The terahertz wave with a preset frequency is emitted by the integrated terahertz transceiver device, so that the terahertz wave passes through the gain antenna and irradiates the speaker to be tested along the set propagation direction, and causes it to interfere with the vibration signal of the speaker diaphragm, resulting in interference. echo signal; By moving the displacement stage, the position of the speaker fixed on it can be adjusted in real time, so that the speaker can move according to the preset step size and trajectory in the plane where the diaphragm is located, so that the terahertz wave scanning irradiation range can cover the entire diaphragm; Set the sampling times, and control the integrated terahertz transceiver device to collect and store a series of echo intensity sequences of terahertz waves corresponding to each sampling point of the diaphragm through the vibration interference of the speaker diaphragm; Analyze the value of the echo intensity sequence, obtain the echo phase information, and analyze the maximum energy and frequency of each sampling point on the surface of the speaker diaphragm according to the Hilbert-Huang transform; Visualize the frequency-coordinate map of the maximum energy of each sampling point of the speaker diaphragm, and determine whether the speaker diaphragm to be tested has defects and the location of the defects. 2. a kind of method that uses terahertz wave to carry out nondestructive testing to loudspeaker diaphragm according to claim 1, it is characterized in that, described preset frequency satisfies Shannon sampling theorem, and carries out multiple times according to the overtone frequency of the signal to be measured set up. 3. a kind of method that uses terahertz wave to carry out nondestructive testing to loudspeaker diaphragm according to claim 1, it is characterized in that, described displacement stage moves to carry out horizontal and vertical two directions in the plane where loudspeaker diaphragm is located 2D movement. 4. A method for non-destructive testing of loudspeaker diaphragms using terahertz waves according to claim 1 or 3, wherein the preset trajectory is to move row by row and column by column, so that the terahertz waves affect the surface of the loudspeaker diaphragm. Each sampling point is scanned row by row and column by column. 5. a kind of method that uses terahertz wave to carry out nondestructive testing to loudspeaker diaphragm according to claim 1, it is characterized in that, described according to Hilbert-Huang transform analysis loudspeaker diaphragm surface each sampling point maximum Energy frequencies, including: 1) The terahertz echo signal is decomposed by using the empirical mode decomposition EMD method, and it is decomposed into the form of a combination of multiple empirical mode functions IMFs and residuals. The specific expression is as follows:

Among them, ε(t) is the terahertz echo signal, i is the number of empirical modal components, IMF _i is the intrinsic empirical modal component, and r _K is the residual residual term after subtracting each empirical modal component from the original signal; 2) Hilbert transform is performed on each empirical mode component IMF, and the IMF component is set as x(t), then its Hilbert transform is H[x(t)], and the local estimation is transformed into a global estimation :

Among them, τ refers to the overall time interval of the signal where x(t) is located; 3) The analytical signal of the real-valued function of the echo signal is obtained, and the specific complex number expression is as follows:

where u(t) is a real-valued function,

is the analytical signal of x(t),

is the Hilbert transformed function H[x(t)] of u(t), the analytical signal

The modulus and amplitude of , represent the amplitude and phase of the two-dimensional signal, that is, the instantaneous frequency and instantaneous amplitude of the echo signal; 4) Take the maximum instantaneous amplitude as the maximum energy, obtain the frequency of the maximum energy of the signal at this moment, and regard the frequency as the vibration frequency of this point on the surface of the speaker diaphragm, and use it to make a frequency-coordinate map of the maximum energy. 6. A method for non-destructive testing of loudspeaker diaphragms using terahertz waves according to claim 1, characterized in that, on the maximum energy frequency spectrum of each sampling point of the loudspeaker diaphragm, according to any point and surrounding The energy frequency difference of each point determines whether the speaker diaphragm to be tested is damaged or abnormal in shape. 7. A system for nondestructive testing of loudspeaker diaphragms using terahertz waves is characterized in that comprising: a terahertz transceiver integrated device (1), a gain antenna (2), a displacement platform (4), a control computer (5), The speaker to be tested (3); The integrated terahertz transceiver device (1) includes a vector network analyzer, a spread spectrum module, and a frequency expander connected in sequence; a waveguide output port of the frequency expander is connected to a booster antenna (2); the booster antenna (2) It is in the shape of a horn, and the opening faces the speaker to be measured (3); the vector network analyzer is connected to the control computer (5); the terahertz wave is sent out by the vector network analyzer, and is beamed after the gain antenna (2) and directly irradiated to the speaker ( 3) On the surface, at the same time, a vector network analyzer serving as a terahertz detector collects the reflected terahertz echo intensity sequence signal; The displacement platform (4) is a two-dimensional platform, comprising a servo motor, a driver, a transverse linear motion module and a longitudinal linear motion module, the speaker (3) is fixed on the transverse motion module, and the transverse linear motion is driven by the servo motor The movement module and the longitudinal linear movement module move, thereby adjusting the position of the speaker (3); the driver is connected with the control computer (5) through a communication interface; The control computer (5) includes a storage part and a processing part inside, the storage part stores a program, and the processing part loads the program to execute the method steps according to any one of claims 1-6, so as to realize the defects or defects on the surface of the speaker diaphragm. Abnormal morphological location detection. 8 . The system for non-destructive testing of loudspeaker diaphragms using terahertz waves according to claim 7 , wherein the loudspeaker ( 3 ) is covered with tin foil to improve echo signal transmittance. 9 .

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