Terahertz spectrum on-line nondestructive testing system

Abstract

The utility model discloses a terahertz spectrum on-line nondestructive testing system which comprises a spectrograph host and a terahertz probe module which are in signal connection with each other, the bracket is used for mounting and fixing the terahertz probe module; the terahertz probe module is arranged above a coating to be detected, a sliding table is arranged on the support, a displacement device is arranged on the sliding table, and the displacement device is connected with the terahertz probe module and used for driving the terahertz probe module to move up and down; the displacement device moves left and right on the sliding table to drive the terahertz probe module to move left and right so as to detect a terahertz spectrum signal of the coating to be detected; and the spectrometer host is used for processing and analyzing the terahertz spectrum signal so as to obtain peak position data representing the thickness of the coating to be measured. Compared with the prior art, the device has the advantages of being convenient to use, high in stability and small in size.

Description

Technical Field

[0001] The utility model relates to the technical field of terahertz spectrum measurement, and more specifically, to an online nondestructive detection system for terahertz spectrum. Background Art

[0002] In recent years, with the rising prices of fuel and other materials, new energy has been widely used, and the core of new energy is battery. Lithium-ion batteries are more popular because they have longer battery life than ordinary batteries. Lithium-ion batteries generally use lithium alloy metal oxides as positive electrode materials and graphite as negative electrode materials. Among them, the positive electrode material is composed of lithium iron phosphate or ternary lithium and aluminum foil, and the thickness of the coating is generally between 50-200um. Since the coating thickness plays a key role in the performance parameters of the battery, and the uniformity of the coating thickness also affects the reliability and accuracy of the product, the coating thickness needs to be measured in the manufacture of lithium batteries, and the measurement accuracy will also affect the accuracy of the measurement.

[0003] At present, the conventional detection method for battery coating thickness is to use micrometer for post-process sampling. The specific method is: manually measure the thickness at the edge position, but manual measurement is inefficient and has large errors. The proficiency of manual operation and the strength of measurement will affect the measurement results. Therefore, it cannot meet the needs of mass production of high-precision products.

[0004] In view of the shortcomings of manual measurement, laser beam detection is also used in the current process. However, the laser cannot penetrate the conductive medium inside the battery coating. Therefore, after measurement, it can only be calculated by thickness subtraction. The data obtained in this way is the total value of the thickness of the aluminum foil plus the upper and lower coatings. It is difficult to accurately obtain the thickness of a single-sided coating. Utility Model Content

[0005] The utility model aims to overcome at least one defect (deficiency) of the above-mentioned prior art and provide a terahertz spectroscopy online non-destructive testing system for solving the problem of how to accurately measure a single side of a battery coating in real time, so as to improve the thickness processing accuracy of the battery coating.

[0006] Based on this, the technical solution adopted by the utility model is:

[0007] A terahertz spectroscopy online nondestructive testing system, comprising a spectrometer host and a terahertz probe module which are signal-connected to each other;

[0008] The terahertz probe module is arranged above the coating to be tested, and moves up and down and / or left and right above the coating to be tested to detect the terahertz spectrum signal of the coating to be tested;

[0009] The spectrometer host is used to process and analyze terahertz spectrum signals, thereby obtaining peak position data characterizing the thickness of the coating to be measured.

[0010] According to the utility model, a terahertz spectroscopy online nondestructive testing system also includes a bracket for installing and fixing the terahertz probe module, the bracket is provided with a slide, the slide is provided with a displacer, the displacer is connected to the terahertz probe module, and is used to drive the terahertz probe module to move up and down; and the displacer drives the terahertz probe module to move left and right by moving left and right on the slide.

[0011] According to the terahertz spectroscopy online nondestructive testing system described in the utility model, the displacer includes a fixed plate, a movable plate and a height adjustment member connected to each other;

[0012] The fixed plate is connected to the slide, the movable plate is connected to the terahertz probe module, and the height adjustment member is used to drive the movable plate to move up and down on the fixed plate, thereby driving the terahertz probe module to move up and down.

[0013] According to the terahertz spectroscopy online nondestructive testing system described in the utility model, the slide is provided with a fine-tuning motor and an adapter plate connected in sequence;

[0014] The adapter plate is arranged between the fine-tuning motor and the shifter, and is used to fix the fine-tuning motor; the fine-tuning motor is arranged between the slide and the adapter plate, and the fine-tuning motor is connected to the shifter through the adapter plate, and is used to drive the shifter to move up and down, thereby driving the terahertz probe module to move up and down.

[0015] According to the utility model, a terahertz spectroscopy online nondestructive testing system, the bracket includes a crossbeam for mounting the slide and a support frame for supporting the crossbeam, the support frame is arranged at both ends of the crossbeam, and one end of the support frame is connected to the crossbeam, and the other end is fixed to an external production line;

[0016] The crossbeam is arranged along the width direction of the coating to be tested, the slide is an electric slide, and a slider is provided on the slide, the slider is connected to the displacer, and the electric slide drives the slider to slide left and right through electricity, thereby driving the terahertz probe module to move left and right in the width direction of the coating to be tested.

[0017] According to the utility model, a terahertz spectroscopy online nondestructive testing system is provided with a transmitting antenna and a receiving antenna connected to the spectrometer host signal on the terahertz probe module, and the terahertz probe module includes a shell and a lens group arranged in the shell, and the spectrometer host includes a power module, a control module, a femtosecond laser, a scanning module and a control panel;

[0018] The power module is electrically connected to the control module and the control panel, respectively, and is used to supply power to the control module and the control panel;

[0019] The control module, the femtosecond laser, the scanning module and the receiving antenna are connected in sequence, and one signal of the femtosecond laser is connected to the transmitting antenna to provide the femtosecond laser to the transmitting antenna; another signal of the femtosecond laser is connected to the receiving antenna through the scanning module to provide the femtosecond laser to the receiving antenna; the scanning module is used to process and compensate the optical path of the femtosecond laser so that the optical path of the femtosecond laser reaching the receiving antenna is equal;

[0020] The control module is connected to the transmitting antenna through a femtosecond laser, and is used to provide a bias voltage to the transmitting antenna. Under the action of the bias voltage and the femtosecond laser, the transmitting antenna generates a terahertz light wave;

[0021] The terahertz light wave is projected onto the coating to be tested through the lens group, and is reflected from the coating to be tested to the receiving antenna;

[0022] The terahertz light waves and femtosecond lasers reaching the receiving antenna interact with each other, converting the optical signals into electrical signals and transmitting them to the control module. The control module processes the electrical signals and transmits them to the control panel, which displays the peak position data of the surface and bottom layers of the coating to be tested.

[0023] According to the terahertz spectrum online nondestructive testing system described in the utility model, the lens group includes a first lens, a second lens, a third lens and a fourth lens which are sequentially arranged in the light emitting direction of the terahertz light wave;

[0024] The coating to be tested is arranged in the light emitting direction of the second lens;

[0025] The first lens is used to focus the terahertz beam into a parallel beam; the second lens is used to focus the parallel beam into a small light spot and project it onto the coating to be tested; the third lens is used to receive the light spot reflected from the coating to be tested and convert the light spot into a parallel light spot; the fourth lens is used to focus the parallel light spot onto the receiving antenna;

[0026] The receiving antenna is provided with a silicon lens for receiving parallel light spots.

[0027] According to the utility model, a terahertz spectroscopy online nondestructive testing system, the scanning module includes a fiber collimator, a first half-wave plate, a first plane reflector, a slow scanning motor, a voice coil motor, a second plane reflector, a second half-wave plate and a fiber coupler which are sequentially arranged in the light emitting direction of the femtosecond laser;

[0028] The fiber collimator is electrically connected to the femtosecond laser and is used to convert the femtosecond laser into parallel free-space light;

[0029] The first half-wave plate is used to change the angle of the free-space light, thereby changing the optical power of the laser on the XY axis;

[0030] The first plane reflector is used to reflect the laser onto the slow-scan motor;

[0031] The slow-scan motor is used to adjust the optical path of the laser and compensate for the optical path difference of the laser on the receiving antenna;

[0032] The voice coil motor is provided with a return reflector for reflecting the laser so that the laser incident on the return reflector and the laser emitted from the return reflector form parallel light; the voice coil motor is electrically connected to the control module and moves back and forth under the drive of the control module to collect terahertz light waves and transmit the position information of the return reflector to the control module;

[0033] The second plane reflector is used to reflect the laser onto the second half-wave plate, and then project it onto the optical fiber coupler;

[0034] The optical fiber coupler is connected to the receiving antenna signal and is used to transmit the processed laser to the receiving antenna.

[0035] According to the terahertz spectroscopy online nondestructive testing system described in the utility model, the receiving antenna is provided with a preamplifier and a phase-locked amplifier for converting the terahertz light wave signal into an electrical signal;

[0036] The peak position data of the surface layer and bottom layer of the coating to be tested are the reflection signals of the surface of the coating to be tested and the surface of the aluminum foil layer respectively; the calculation formula of the thickness d of the coating to be tested is: d=c*△t / 2n, wherein c represents the speed of light, △t represents the time delay between the two peak positions, and n represents the refractive index of the coating.

[0037] According to the terahertz spectroscopy online nondestructive testing system described in the utility model, a height sensor is provided in the terahertz probe module, and the height sensor is used to measure the distance between the terahertz probe module and the coating to be tested.

[0038] Compared with the prior art, the beneficial effects of the utility model are:

[0039] The terahertz detection probe of the utility model is installed on the battery coating production line for use, and can perform non-contact optical wave detection on the battery coating, and then detect the thickness of the battery coating in real time online. When the thickness data deviation is large, the process parameters of the coating production line can be adjusted in time according to the information fed back by the spectrometer host, so as to obtain a battery coating with higher accuracy. Compared with the prior art, the utility model has the beneficial effects of being easy to use, high in stability, and small in size. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a structural schematic diagram of the terahertz probe module of the utility model installed on a bracket.

[0041] FIG. 2 is a schematic structural diagram of the terahertz probe module of the present invention.

[0042] FIG3 is a working principle diagram of the spectrometer host of the present utility model.

[0043] Figure 4 is a working principle diagram of the scanning module.

[0044] Figure 5 is a schematic diagram of the reference signal of the terahertz time domain signal.

[0045] Figure 6 is a schematic diagram of the reflected time domain signal of the coating to be tested.

[0046] Figure 7 is a data display diagram of the coating to be tested on the control panel.

[0047] The drawings of the present invention are only used for illustrative purposes and cannot be construed as limiting the present invention. In order to better illustrate the following embodiments, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted. DETAILED DESCRIPTION

[0048] The preferred embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. However, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0049] The terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The singular forms "a", "the" used in the present invention and the appended claims are intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0050] It should be understood that although the terms "first", "second", "third", etc. may be used to describe various information in the present invention, this information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present invention, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0051] The drawings of the present invention are only used for illustrative purposes and cannot be construed as limiting the present invention. In order to better illustrate the following embodiments, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0052] Example 1

[0053] As shown in Figures 1 to 3, this embodiment discloses a terahertz spectroscopy online nondestructive testing system, including a terahertz probe module 100 and a spectrometer host 200 that are mutually signal-connected; wherein the terahertz probe module 100 is arranged above the coating 300 to be tested, and moves up and down and / or left and right above the coating 300 to be tested to detect the terahertz spectrum signal of the coating 300 to be tested; the spectrometer host 200 is used to process and analyze the terahertz spectrum signal, so as to obtain peak position data characterizing the thickness of the coating 300 to be tested. In this technical solution, the terahertz wave can penetrate a coating of a certain thickness, and through the terahertz reflection signal, the reflection peak of the upper surface and the reflection peak from the aluminum foil surface can be intuitively seen, and the time delay between the two reflection peaks is the thickness of the corresponding coating. Among them, the thickness information of different positions on the coating can be measured by a single-point spectrum line method. At the same time, when the terahertz probe module 100 moves left and right / up and down, the coating of the entire width can be detected in real time, so that the process parameters of the coating thickness can be adjusted in time according to the feedback information to ensure that the thickness meets the product design requirements.

[0054] Furthermore, the system also includes a bracket 400 for installing and fixing the terahertz probe module 100, wherein a slide 500 is provided on the bracket 400, and a shifter 600 is provided on the slide 500. The shifter 600 is connected to the terahertz probe module 100 and is used to drive the terahertz probe module 100 to move up and down; and the shifter 600 drives the terahertz probe module 100 to move left and right by moving left and right on the slide 500.

[0055] Specifically, the displacer 600 includes a fixed plate, a movable plate and a height adjustment member connected to each other; the fixed plate is connected to the slide 500, the movable plate is connected to the terahertz probe module 100, and the height adjustment member is used to drive the movable plate to move up and down on the fixed plate, thereby driving the terahertz probe module 100 to move up and down.

[0056] In this embodiment, the height adjustment member is a height adjustment knob. By turning the height adjustment knob, the movable plate moves up and down, thereby driving the terahertz probe module 100 to move up and down, so as to change the distance between the terahertz probe module 100 and the coating 300 to be tested, and ensure that the coating 300 to be tested is located at the focal position of the terahertz probe module 100.

[0057] Furthermore, the slide 500 is provided with a fine-tuning motor 700 and an adapter plate (not shown in the figure) connected in sequence; the fine-tuning motor 700 is mainly provided to electrically fine-tune the height of the terahertz probe module 100 on the coating 300 to be tested, so as to ensure that the height between the coating 300 to be tested and the terahertz probe module 100 is consistent with the focal length requirement of the terahertz probe module 100, thereby ensuring that the signal reflected from the surface of the coating 300 to be tested is optimal. Among them, the adapter plate is arranged between the fine-tuning motor 700 and the shifter 600, and is used to fix the fine-tuning motor 700; the fine-tuning motor 700 is arranged between the slide 500 and the adapter plate, and the fine-tuning motor 700 is connected to the shifter 600 through the adapter plate, and is used to drive the shifter 600 to move up and down, thereby driving the terahertz probe module 100 to move up and down.

[0058] Further, in this embodiment, the bracket 400 includes a crossbeam 410 for mounting the slide 500 and a support frame 420 for supporting the crossbeam 410, the support frame 420 is arranged at both ends of the crossbeam 410, and one end of the support frame 420 is connected to the crossbeam 410, and the other end is fixed to the external production line, specifically installed on the baffle 310 of the production line; the crossbeam 410 is arranged along the width direction of the coating 300 to be tested, wherein both ends of the crossbeam 410 are provided with U-shaped screw hole grooves, one end of the support frame 420 is connected to the U-shaped screw hole groove, and can move left and right in the U-shaped screw hole groove, so as to make a slight adjustment to the width of the crossbeam 410. Among them, the height of the support frame 420 can be adjusted, so as to adjust the height of the terahertz probe module 100 to the coating 300 to be tested, and ensure that the terahertz wave can hit the surface of the coating 300 to be tested.

[0059] The slide 500 of this embodiment is an electric slide, and a slider is provided on the slide 500, and the slider is connected to the displacement device 600. The electric slide 500 drives the slider to slide left and right by electricity, thereby driving the terahertz probe module 100 to move left and right in the width direction of the coating 300 to be tested. The terahertz probe module 100 is driven by the electric slide to move left and right on the coating 300 to be tested, and the coating 300 to be tested runs on the production line, so that the thickness of different positions of the coating 300 to be tested can be detected. The stroke of the electric slide can be designed according to the width of the coating 300 to be tested, so as to ensure that the terahertz probe module 100 can move within the width range of the coating 300 to be tested.

[0060] As shown in FIGS. 2 and 3 , further, the terahertz probe module 100 is provided with a transmitting antenna 800 and a receiving antenna 900 connected to the spectrometer host 200 signal, and the terahertz probe module 100 includes a shell and a lens group arranged in the shell, and the spectrometer host 200 includes a power module 210, a control module 220, a femtosecond laser 230, a scanning module 240 and a control panel 250; wherein the power module 210 is electrically connected to the control module 220 and the control panel 250 respectively, and is used to supply power to the control module 220 and the control panel 250; the control module 220, the femtosecond laser 230, the scanning module 240 and the receiving antenna 900 are connected in sequence, and one signal of the femtosecond laser 230 is connected to the transmitting antenna 800, and is used to provide femtosecond laser to the transmitting antenna 800; another signal of the femtosecond laser 230 is connected to the receiving antenna 900 through the scanning module 240, and is used to provide the receiving antenna 900 with a femtosecond laser. A femtosecond laser is provided; the scanning module 240 is used to process and compensate the optical path of the femtosecond laser so that the optical path of the femtosecond laser reaching the receiving antenna 900 is equal; the control module 220 is connected to the transmitting antenna 800 through the femtosecond laser 230, and is used to provide a bias voltage to the transmitting antenna 800. Under the action of the bias voltage and the femtosecond laser, the transmitting antenna 800 excites the photoconductive antenna inside the transmitting antenna 800 to generate a terahertz light wave; the terahertz light wave is projected onto the coating 300 to be tested through the lens group, and is reflected from the coating 300 to the receiving antenna 900; the terahertz light wave reaching the receiving antenna 900 and the femtosecond laser interact to convert the optical signal into an electrical signal, and transmit it to the control module 220. After the control module 220 processes the electrical signal, it transmits it to the control panel 250, and displays the peak position data of the surface and bottom layers of the coating 300 to be tested through the control panel 250.

[0061] Specifically, the power module 210 is used to convert the external 220V power supply into a 12V power supply to power the control module 220 and the control panel 250. The femtosecond laser 230 and the scanning module 240 are powered by the control module 220. The femtosecond laser 230 of this embodiment is a 1560nm femtosecond laser 230, which is used to excite the terahertz indium gallium arsenide semiconductor antenna to generate terahertz waves.

[0062] Further, the lens group in the terahertz probe module 100 includes a first lens, a second lens, a third lens and a fourth lens which are sequentially arranged in the light-emitting direction of the terahertz light wave; wherein the coating to be tested 300 is arranged in the light-emitting direction of the second lens; the first lens is used to focus the terahertz light beam into a parallel light beam; the second lens is used to focus the parallel light beam into a small light spot and project it onto the coating to be tested 300; the third lens is used to receive the light spot reflected from the coating to be tested 300 and convert the light spot into a parallel light spot; the fourth lens is used to focus the parallel light spot onto the receiving antenna 900; the receiving antenna 900 is provided with a silicon lens for receiving the parallel light spot. The silicon lens focuses the light beam onto the chip surface of the photoconductive antenna. Under the joint action of the femtosecond laser, the terahertz light wave is converted into a current signal. The receiving antenna is also provided with a preamplifier and a phase-locked amplifier, which are used to convert the terahertz current signal into a terahertz voltage signal and transmit it to the control module 220. After data processing, the control module 220 transmits the signal to the control panel 250. The control panel 250 is provided with a touch panel, which has a start function as well as data collection, analysis and display functions.

[0063] In this embodiment, the first lens, the second lens and the fourth lens are focusing lenses, the third lens is a parabolic mirror, and the second lens is used to focus the energy of the terahertz light wave at the focal position, and then incident on the coating 300 to be tested.

[0064] As shown in FIG4 , further, the scanning module 240 includes a fiber collimator 241, a first half-wave plate 242, a first plane reflector 243, a slow-scan motor 244, a voice coil motor 245, a second plane reflector 246, a second half-wave plate 247 and a fiber coupler 248, which are sequentially arranged in the light-emitting direction of the femtosecond laser; wherein the fiber collimator 241 is electrically connected to the femtosecond laser 230, and is used to convert the femtosecond laser into parallel free-space light; the first half-wave plate 242 is used to change the angle of the free-space light, thereby changing the optical power of the laser on the XY axis; the first plane reflector 243 is used to reflect the laser onto the slow-scan motor 244; wherein the first plane reflector 243 reflects the laser at 90° after changing the angle of the laser. The slow scanning motor 244 is used to adjust the optical path of the laser and compensate for the optical path difference of the laser on the receiving antenna 900; the voice coil motor 245 is provided with a return reflector 249, which is used to reflect the laser so that the laser incident on the return reflector 249 and the laser emitted from the return reflector 249 form parallel light; the voice coil motor 245 is electrically connected to the control module 220, and moves back and forth under the drive of the control module 220, for collecting terahertz light waves, and transmitting the position information of the return reflector 249 to the control module 220 through the grating ruler; wherein, when the voice coil motor 245 moves back and forth on the return reflector 249, a standard square wave signal is formed. The second plane reflector 246 is used to reflect the laser onto the second half-wave plate 247, and then project it onto the optical fiber coupler 248; the optical fiber coupler 248 is connected to the receiving antenna signal, and is used to transmit the processed laser to the receiving antenna.

[0065] Furthermore, the terahertz optical signal is processed by the preamplifier on the receiving antenna 900 and becomes a current signal; then it is filtered and amplified by the control module 220, and finally the terahertz frequency domain and time domain signals are displayed on the control panel 250.

[0066] Further, the peak position data corresponding to the surface layer and bottom layer of the coating to be tested can be seen on the control panel 250, and the peak position data of the surface layer and bottom layer of the coating to be tested 300 are respectively the reflection signals of the surface of the coating to be tested 300 and the surface of the aluminum foil layer; in this embodiment, FIG5 is the reference signal of the terahertz time domain signal, and FIG6 is the reflection time domain signal of the coating to be tested. FIG7 is the real-time thickness measurement data of the coating to be tested 300. Among them, the calculation formula of the thickness d of the coating to be tested 300 is: d=c*△t / 2n, wherein c represents the speed of light, △t represents the time delay between the two peaks, and n represents the refractive index of the coating.

[0067] Among them, the thickness data of the coating to be tested 300 can be calculated by AI algorithm and displayed in real time on the control panel 250. At the same time, the test results can be fed back to the coating coating equipment through serial communication. If the thickness deviation of the coating is large, an alarm will be issued so that the process parameters can be adjusted in time, thereby improving the thickness processing accuracy of the battery coating and further improving the product quality of the battery.

[0068] Furthermore, a height sensor is provided in the terahertz probe module 100 , and the height sensor is used to measure the distance between the terahertz probe module 100 and the coating 300 to be tested.

[0069] Furthermore, in order to increase the area of ​​the measurement range, the probe of the terahertz probe module 100 can also be changed to a surface vibration scanning mode to perform surface vibration scanning imaging, and at the same time extract spectral line data from the imaging data to calculate thickness data, so that the measured data is more accurate and the measurement precision is higher.

[0070] Among them, the processing of battery coating mainly includes unwinding, printing coating, baking and rolling. The terahertz spectroscopy online nondestructive testing system of this technical solution can be used after the printing coating process of the battery coating to detect the thickness of the wet coating after printing, and can also be used after the baking process to detect the thickness of the dry coating, and can also be used after the rolling process to detect the thickness of the coating after rolling, thereby realizing the detection of coating processes at different stages, forming a closed-loop detection, and ultimately improving the quality of the product.

[0071] Obviously, the above embodiments of the utility model are only examples for clearly explaining the technical solution of the utility model, and are not intended to limit the specific implementation methods of the utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the claims of the utility model shall be included in the protection scope of the claims of the utility model.

Claims

1. A terahertz spectroscopy online nondestructive testing system, characterized in that: It includes a spectrometer host and a terahertz probe module which are signal-connected to each other; The terahertz probe module is disposed above the coating to be tested, and moves up and down and / or left and right above the coating to be tested to detect the terahertz spectrum signal of the coating to be tested; The spectrometer host is used to process and analyze terahertz spectrum signals, thereby obtaining peak position data characterizing the thickness of the coating to be measured; The terahertz probe module is provided with a transmitting antenna and a receiving antenna connected to the spectrometer host signal, and the terahertz probe module includes a shell and a lens group arranged in the shell, and the spectrometer host includes a power module, a control module, a femtosecond laser, a scanning module and a control panel; The power module is electrically connected to the control module and the control panel, respectively, and is used to supply power to the control module and the control panel; The control module, the femtosecond laser, the scanning module and the receiving antenna are connected in sequence, and one signal of the femtosecond laser is connected to the transmitting antenna to provide the femtosecond laser to the transmitting antenna; another signal of the femtosecond laser is connected to the receiving antenna through the scanning module to provide the femtosecond laser to the receiving antenna; the scanning module is used to process and compensate the optical path of the femtosecond laser so that the optical path of the femtosecond laser reaching the receiving antenna is equal; The control module is connected to the transmitting antenna through a femtosecond laser, and is used to provide a bias voltage to the transmitting antenna. Under the action of the bias voltage and the femtosecond laser, the transmitting antenna generates a terahertz light wave; The terahertz light wave is projected onto the coating to be tested through the lens group, and is reflected from the coating to be tested to the receiving antenna; The terahertz light waves and femtosecond lasers reaching the receiving antenna interact with each other, converting the optical signals into electrical signals and transmitting them to the control module. The control module processes the electrical signals and transmits them to the control panel, which displays the peak position data of the surface and bottom layers of the coating to be tested.

2. The terahertz spectroscopy online nondestructive testing system according to claim 1, characterized in that: It also includes a bracket for installing and fixing the terahertz probe module, the bracket is provided with a slide, the slide is provided with a displacer, the displacer is connected to the terahertz probe module, and is used to drive the terahertz probe module to move up and down; and the displacer drives the terahertz probe module to move left and right by moving left and right on the slide.

3. The terahertz spectroscopy online nondestructive testing system according to claim 2, characterized in that: The displacer comprises a fixed plate, a movable plate and a height adjustment member connected to each other; The fixed plate is connected to the slide, the movable plate is connected to the terahertz probe module, and the height adjustment member is used to drive the movable plate to move up and down on the fixed plate, thereby driving the terahertz probe module to move up and down.

4. The terahertz spectroscopy online nondestructive testing system according to claim 2, characterized in that: The slide is provided with a fine-tuning motor and an adapter plate connected in sequence; The adapter plate is arranged between the fine-tuning motor and the shifter, and is used to fix the fine-tuning motor; the fine-tuning motor is arranged between the slide and the adapter plate, and the fine-tuning motor is connected to the shifter through the adapter plate, and is used to drive the shifter to move up and down, thereby driving the terahertz probe module to move up and down.

5. The terahertz spectroscopy online nondestructive testing system according to claim 2, characterized in that: The bracket includes a crossbeam for mounting the slide and a support frame for supporting the crossbeam, wherein the support frame is arranged at two ends of the crossbeam, and one end of the support frame is connected to the crossbeam, and the other end is fixed to an external production line; The crossbeam is arranged along the width direction of the coating to be tested, the slide is an electric slide, and a slider is provided on the slide, the slider is connected to the displacer, and the electric slide drives the slider to slide left and right through electricity, thereby driving the terahertz probe module to move left and right in the width direction of the coating to be tested.

6. The terahertz spectroscopy online nondestructive testing system according to claim 1, characterized in that: The lens group includes a first lens, a second lens, a third lens and a fourth lens which are sequentially arranged in the light emitting direction of the terahertz light wave; The coating to be tested is arranged in the light emitting direction of the second lens; The first lens is used to focus the terahertz beam into a parallel beam; the second lens is used to focus the parallel beam into a small light spot and project it onto the coating to be tested; the third lens is used to receive the light spot reflected from the coating to be tested and convert the light spot into a parallel light spot; The fourth lens is used to focus the parallel light spot onto the receiving antenna; The receiving antenna is provided with a silicon lens for receiving parallel light spots.

7. The terahertz spectroscopy online nondestructive testing system according to claim 1, characterized in that: The scanning module includes a fiber collimator, a first half-wave plate, a first plane reflector, a slow-scan motor, a voice coil motor, a second plane reflector, a second half-wave plate and a fiber coupler which are sequentially arranged in the light-emitting direction of the femtosecond laser; The fiber collimator is electrically connected to the femtosecond laser and is used to convert the femtosecond laser into parallel free-space light; The first half-wave plate is used to change the angle of the free-space light, thereby changing the optical power of the laser on the XY axis; The first plane reflector is used to reflect the laser onto the slow-scan motor; The slow-scan motor is used to adjust the optical path of the laser and compensate for the optical path difference of the laser on the receiving antenna; The voice coil motor is provided with a return reflector for reflecting the laser so that the laser incident on the return reflector and the laser emitted from the return reflector form parallel light; the voice coil motor is electrically connected to the control module and moves back and forth under the drive of the control module to collect terahertz light waves and transmit the position information of the return reflector to the control module; The second plane reflector is used to reflect the laser onto the second half-wave plate, and then project it onto the optical fiber coupler; The optical fiber coupler is connected to the receiving antenna signal and is used to transmit the processed laser to the receiving antenna.

8. The terahertz spectroscopy online nondestructive testing system according to claim 1, characterized in that: The receiving antenna is provided with a preamplifier and a phase-locked amplifier for converting the terahertz light wave signal into an electrical signal; The peak position data of the surface layer and bottom layer of the coating to be tested are the reflection signals of the surface of the coating to be tested and the surface of the aluminum foil layer respectively; the calculation formula of the thickness d of the coating to be tested is: d=c*△t / 2n, wherein c represents the speed of light, △t represents the time delay between the two peak positions, and n represents the refractive index of the coating.

9. The terahertz spectroscopy online nondestructive testing system according to claim 1, characterized in that: A height sensor is arranged in the terahertz probe module, and the height sensor is used to measure the distance between the terahertz probe module and the coating to be measured.

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