A large dynamic scattering terahertz material imaging and composition analysis device and method

Abstract

The present invention discloses a large-dynamic scattering terahertz material imaging and composition analysis device and method. The device includes a dual-port frequency-sweep excitation signal generation and intermediate frequency signal detection module, a two-way low-noise amplification and mixing module, a low-noise amplification module, an IQ mixing amplification module, a data acquisition module, and an industrial control computer, all of which are sequentially connected. The dual-port frequency-sweep excitation signal generation and intermediate frequency signal detection module are respectively connected to a terahertz signal frequency-doubling transmission module and a terahertz signal frequency-mixing detection module via a switch matrix. A signal transmission adjustment device, a nanoprobe, a piezoelectric body, a two-port excitation source, and a three-dimensional scanning frame for moving the sample to be tested are provided between the terahertz signal frequency-doubling transmission module and the terahertz signal frequency-mixing detection module. The device and method of the present invention can break through the diffraction limit and achieve nanoscale imaging; possess near-field terahertz scattering spectrum analysis capabilities, realize material composition analysis, and achieve large-dynamic testing with an accuracy exceeding 100dB across the entire frequency band.

Description

Technical Field

[0001] The present invention relates to the field of scattering terahertz imaging and component analysis, and in particular to a large dynamic scattering terahertz material imaging and component analysis device and method. Background Art

[0002] Terahertz waves offer advantages such as fingerprint properties, low-energy safety, and strong penetration, making them suitable for three-dimensional imaging and composition analysis of non-metallic materials. However, commonly used structural imaging and composition analysis systems based on terahertz time-domain spectroscopy suffer from the following drawbacks: First, due to the diffraction limit, the system's optimal resolution is no better than half a wavelength; second, due to the frequency resolution of GHz to tens of GHz, detailed composition analysis is impossible; and third, due to the limitations of the test mechanism, the peak-to-peak dynamic range is only 60dB-70dB, making large-scale dynamic testing impossible.

[0003] Based on the needs of all parties, as an emerging imaging and composition analysis technology, scattered terahertz microscopy has attracted much attention. However, most current scattered terahertz microscopy instruments are based on optical sources. Due to the limitations of the testing mechanism, the performance of the optical source is greatly affected by the environment, the terahertz signal energy is weak, the signal-to-noise ratio is poor, and it is difficult to meet the testing requirements. Chinese invention patent application 201810970798.0 discloses a scattered terahertz near-field microscope based on radio frequency electronics methods. This invention only uses terahertz point-frequency continuous waves to achieve near-field microscopic two-dimensional imaging and does not have the ability to analyze material composition. Chinese invention patent application 202110546788.6 discloses an all-electronic terahertz near-field spectrum comprehensive testing device and method. This invention adopts an integrated transmitter-receiver mode with a dynamic range of only 30dB-40dB. It has terahertz near-field two-dimensional imaging and terahertz spectrum detection capabilities, but does not have the ability to analyze material composition and cannot meet application requirements. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides a large dynamic scattering terahertz material imaging and composition analysis device and method, which breaks through the diffraction limit and realizes nanoscale imaging; at the same time, it has the ability to analyze near-field terahertz scattering spectra, can realize material composition analysis, and can achieve large dynamic testing with an accuracy better than 100dB in the entire frequency band.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] A large dynamic scattering terahertz material imaging and component analysis device comprises a dual-port frequency sweeping excitation signal generation and intermediate frequency signal detection module, a two-way low-noise amplification and mixing module, a low-noise amplification module, an IQ mixing amplification module, a data acquisition module, and an industrial control computer, all of which are sequentially connected to each other. The dual-port frequency sweeping excitation signal generation and intermediate frequency signal detection module are respectively connected to a terahertz signal frequency doubling transmission module and a terahertz signal frequency mixing detection module via a switch matrix. A signal transmission adjustment device, a nanoprobe, a piezoelectric body, a two-port excitation source, and a three-dimensional scanning frame for moving a sample to be measured are arranged between the terahertz signal frequency doubling transmission module and the terahertz signal frequency mixing detection module. The nanoprobe is located above the sample to be measured, the piezoelectric body controls the nanoprobe to perform periodic vibration, and the two-port excitation source is respectively connected to the nanoprobe and the IQ mixing amplification module.

[0007] In the above scheme, the dual-port frequency sweep excitation signal generation and intermediate frequency signal detection module includes a frequency reference unit, which is respectively connected to a fine frequency sweep microwave source 1, a fine frequency sweep microwave source 2, and a fine frequency sweep microwave source 3. The fine frequency sweep microwave source 1 is connected to an amplifier 1, the fine frequency sweep microwave source 2 is connected to an amplifier 2, and the fine frequency sweep microwave source 3 is connected to an amplifier 3 and an amplifier 4 through a power divider. The amplifier 3 and the amplifier 4 are respectively connected to a mixer 1 and a mixer 2; the amplifier 1 is connected to the radio frequency signal input end of the switch matrix, the amplifier 2 is connected to the local oscillator signal input end of the switch matrix, the mixer 1 is connected to the reference signal output end of the switch matrix and the two-way low-noise amplification and mixing module, and the mixer 2 is connected to the reference signal output end of the switch matrix and the two-way low-noise amplification and mixing module.

[0008] In the above scheme, the terahertz signal frequency doubling transmission module includes M terahertz signal frequency doubling transmission links, and the terahertz signal frequency mixing detection module includes M terahertz signal frequency mixing detectors. The M terahertz signal frequency doubling transmission links and the M terahertz signal frequency mixing detectors are arranged in a circle on a five-degree-of-freedom precision adjustment frame.

[0009] In a further technical solution, the terahertz signal frequency doubling transmission link includes one frequency doubling link and one mixing link. The frequency doubling link includes an A frequency multiplier, an amplifier five, a B frequency multiplier, an amplifier six, a C frequency multiplier and a single directional coupler connected in sequence to realize the transmission of the terahertz signal into free space; the mixing link includes a G frequency multiplier, an amplifier seven, an F frequency multiplier, an amplifier eight, an E frequency multiplier, an amplifier nine and a D-subharmonic mixer connected in sequence to realize the output of the reference signal; the single directional coupler is connected to the D-subharmonic mixer through an isolator; the link composition of the terahertz signal mixing detector is the same as the mixing link in the terahertz signal frequency doubling transmission link.

[0010] In a further technical solution, the multiplication orders of the A multiplier, B multiplier, C multiplier, G multiplier, F multiplier and E multiplier are 2, 3 or 4, the harmonic order of the D-th harmonic mixer is 1, 2, 4 or 6, and satisfy: A×B×C=G×F×E×D.

[0011] In the above scheme, the signal transmission adjustment device includes a first terahertz lens antenna, a first transparent non-polarizing beam splitter, a first reflector, a second reflector, a third reflector, a parabolic mirror, a fourth reflector, a fifth reflector, a sixth reflector, a second transparent non-polarizing beam splitter and a second terahertz lens antenna arranged in sequence, the first terahertz lens antenna is arranged on the terahertz signal frequency doubling transmission module, the second terahertz lens antenna is arranged on the terahertz signal frequency mixing detection module, and the parabolic mirror is located around the sample to be measured; a first visible laser emitter is arranged on one side of the first transparent non-polarizing beam splitter, and a second visible laser emitter is arranged on one side of the second transparent non-polarizing beam splitter; the first transparent non-polarizing beam splitter, the first reflector and the second reflector are located on a five-degree-of-freedom precision adjustment frame two, the fifth reflector, the sixth reflector and the second transparent non-polarizing beam splitter are located on a five-degree-of-freedom precision adjustment frame three, and the parabolic mirror is located on a three-dimensional precision control frame.

[0012] A large dynamic scattering terahertz material imaging and composition analysis method, using the large dynamic scattering terahertz material imaging and composition analysis device as described above, includes the following steps:

[0013] Step 1: The dual-port sweep frequency excitation signal generation and intermediate frequency signal detection module outputs the radio frequency signal and the local oscillator signal, which are transmitted to the terahertz signal frequency multiplication transmission module through the switch matrix, wherein the local oscillator signal is also transmitted to the terahertz signal mixing detection module through the switch matrix;

[0014] Step 2: The local oscillator signal is frequency-multiplied, amplified, and mixed in the terahertz signal frequency-multiplication transmission module to output a reference signal, which is then returned to the dual-port frequency-sweep excitation signal generation and intermediate frequency signal detection module after passing through the switch matrix; the radio frequency signal is frequency-multiplied and amplified in the terahertz signal frequency-multiplication transmission module to output a terahertz signal, which is then passed through a signal transmission and adjustment device to reach the sample to be tested, and interacts with the sample to be tested under the action of the nanoprobe. The terahertz signal containing information about the sample to be tested is passed through the signal transmission and adjustment device to reach the terahertz signal frequency mixing detection module, and is mixed with the local oscillator signal input to the module to obtain a test signal. The test signal is then returned to the dual-port frequency-sweep excitation signal generation and intermediate frequency signal detection module after passing through the switch matrix;

[0015] Step 3: The test signal and the reference signal are mixed in the dual-port swept frequency excitation signal generation and intermediate frequency signal detection module to obtain intermediate frequency signal 1 and intermediate frequency signal 2, and then transmitted to the two-way low-noise amplification and mixing module;

[0016] Step 4: After the IF signal 1 and the IF signal 2 are amplified and mixed in the two-way low-noise amplification and mixing module, the IF signal 3 containing the sample information is obtained. The IF signal 3 is amplified by the low-noise amplification module and then input into the IQ mixing amplification module.

[0017] In step 5, the 2-port excitation source outputs a microwave signal as the input reference signal of the IQ mixer amplifier module. The intermediate frequency signal 3 is mixed with the input reference signal in the IQ mixer amplifier module to obtain amplitude and phase information respectively. Finally, it is collected by the data acquisition module and transmitted to the industrial computer.

[0018] In the above scheme, the analysis method includes two working modes: a point frequency working mode and a sweep frequency working mode. The point frequency working mode is used to realize material imaging, and the sweep frequency working mode is used to perform component analysis.

[0019] In a further technical solution, the point frequency working mode includes the following steps:

[0020] Step 1: Place the sample to be tested on a three-dimensional scanning frame to automatically position the sample and obtain the starting position information (x0, y0) of the sample to be tested within the test area;

[0021] Step 2, parameter setting: including terahertz signal frequency f0, signal power, imaging range, number of pixels, scanning speed, nanoprobe vibration frequency and vibration amplitude;

[0022] Step 3: The piezoelectric body controls the nanoprobe to perform sinusoidal vibration with a set frequency and amplitude;

[0023] Step 4: At the starting position (x0, y0) of the sample, the terahertz signal frequency doubling transmission module generates a terahertz signal with a set frequency of f0, which passes through the first terahertz lens antenna, the first transparent non-polarizing beam splitter, the first reflector, the second reflector, the third reflector, and the parabolic mirror to the surface of the sample to be tested. Under the action of the nanoprobe, the terahertz signal interacts with the sample to be tested. The terahertz signal containing detailed information of the sample to be tested passes through the parabolic mirror, the fourth reflector, the fifth reflector, the sixth reflector, the second transparent non-polarizing beam splitter, and the second terahertz lens antenna to the terahertz signal mixing detection module to obtain a test signal;

[0024] Step 5: The test signal and the reference signal are demodulated to obtain the amplitude and phase of the terahertz signal scattered by the sample under test at the position (x0, y0);

[0025] Step 6: Under the control of the three-dimensional scanning frame, the nanoprobe moves to the position (x1, y1) of the sample to be tested. Repeat steps 4 to 5 to obtain the amplitude and phase of the terahertz signal scattered by the sample to be tested at the position (x1, y1); and so on until the entire sample is traversed, and finally the amplitude and phase of the terahertz signal scattered by the sample to be tested at the position (x1, y1) are obtained.N ,y N ) position;

[0026] Step 7, thereby obtaining the amplitude matrix and phase matrix of the sample to be tested, and based on the imaging algorithm built into the industrial computer, realizing the image α0 of the sample to be tested at the frequency of the terahertz signal f0;

[0027] Step 8, resetting the terahertz signal frequency f1 and signal power;

[0028] Step 9, repeating steps 3 to 7 to obtain an image α1 of the sample to be tested when the terahertz signal has a frequency of f1;

[0029] Step 10, and so on, until the image set of all the set frequencies is obtained.

[0030] Step 11: Based on the multi-image fusion algorithm built into the industrial computer, a two-dimensional or three-dimensional topography image is finally obtained.

[0031] In a further technical solution, the frequency sweeping working mode includes the following steps:

[0032] 1) Place the sample to be tested on the 3D scanning frame to realize automatic positioning of the sample to be tested and obtain the center position (x c ,y c );

[0033] 2) Parameter settings: including the terahertz signal starting frequency f1, ending frequency f2, frequency resolution, signal power, scanning speed, probe vibration frequency and vibration amplitude;

[0034] 3) The piezoelectric body controls the nanoprobe to perform sinusoidal vibrations of set frequency and amplitude;

[0035] 4) In the sample (x c ,y c ) position, the terahertz signal frequency doubling transmission module generates a terahertz signal with a frequency of f1-f2 according to a specific frequency resolution, and passes through the first terahertz lens antenna, the first transparent non-polarizing beam splitter, the first reflector, the second reflector, the third reflector, and the parabolic mirror in sequence to the surface of the sample to be tested, and interacts with the sample to be tested under the action of the nanoprobe. The terahertz signal containing detailed information of the sample to be tested passes through the parabolic mirror, the fourth reflector, the fifth reflector, the sixth reflector, the second transparent non-polarizing beam splitter, and the second terahertz lens antenna to the terahertz signal mixing detection module to obtain a test signal;

[0036] 5) The test signal and the reference signal are demodulated to obtain the sample to be tested at (x c ,y c) position;

[0037] 6) Based on the material composition analysis algorithm built into the industrial computer, the composition information of the sample to be tested is finally obtained.

[0038] Through the above technical solution, the large dynamic scattering terahertz material imaging and composition analysis device and method provided by the present invention have the following beneficial effects:

[0039] (1) The present invention adopts all-electronic solid-state frequency multiplication and mixing detection with separate transmission and reception for scattered terahertz near-field signal demodulation, which can achieve large dynamic testing with better than 100dB in the entire frequency band;

[0040] (2) The present invention adopts all-electronic solid-state frequency doubling and mixing detection with separate transmission and reception of terahertz signal generation and detection, which can realize the scattered terahertz near-field spectrum test with Hz-level resolution, which is more conducive to the refined analysis of material composition;

[0041] (3) The present invention uses an ultra-thin transparent non-polarizing beam splitter to effectively suppress multipath interference of the signal, which is more conducive to high signal-to-noise ratio demodulation of scattered terahertz near-field signals;

[0042] (4) The present invention can break through the diffraction limit and achieve nanoscale imaging, providing a new testing idea for terahertz imaging and material composition analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for describing the embodiments or the prior art.

[0044] Figure 1 This is a schematic diagram of module connections of a large dynamic scattering terahertz material imaging and composition analysis device disclosed in an embodiment of the present invention;

[0045] Figure 2 This is a schematic diagram of the dual-port swept frequency excitation signal generation and intermediate frequency signal detection module;

[0046] Figure 3 This is a schematic diagram of the distribution of the terahertz signal frequency doubling transmission module and the terahertz signal frequency mixing detection module;

[0047] Figure 4 Schematic diagram of the terahertz signal frequency doubling transmission link;

[0048] Figure 5 Schematic diagram of the terahertz signal mixing detection module;

[0049] Figure 6 This is a schematic diagram of a 4×M channel switch matrix interface;

[0050] Figure 7 This is a schematic diagram of the connection between the 4×M channel switch matrix and the remaining modules;

[0051] Figure 8 It is a schematic diagram of a signal transmission adjustment device;

[0052] Figure 9 This is the imaging image of the gold-silicon interface;

[0053] Figure 10 The scattered terahertz near-field spectrum of the gold-silicon interface.

[0054] In the figure, 1. first terahertz lens antenna; 2. first transparent non-polarizing beam splitter; 3. first reflector; 4. second reflector; 5. third reflector; 6. parabolic mirror; 7. fourth reflector; 8. fifth reflector; 9. sixth reflector; 10. second transparent non-polarizing beam splitter; 11. second terahertz lens antenna; 12. terahertz signal frequency doubling transmission link; 13. terahertz signal mixing detector; 14. first visible laser emitter; 15. second visible laser emitter; 16. five-degree-of-freedom precision adjustment frame two; 17. five-degree-of-freedom precision adjustment frame three; 18. three-dimensional precision control frame; 19. nanoprobe; 20. piezoelectric body; 21. three-dimensional scanning frame; 22. sample to be measured; 23. five-degree-of-freedom precision adjustment frame one. DETAILED DESCRIPTION

[0055] The technical solutions in the embodiments of the present invention will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present invention.

[0056] The present invention provides a large dynamic scattering terahertz material imaging and composition analysis device, such as Figure 1 and Figure 7 As shown, the system includes a dual-port frequency sweep excitation signal generation and intermediate frequency signal detection module, a two-way low-noise amplification and mixing module, a low-noise amplification module, an IQ mixing amplification module, a data acquisition module, and an industrial control computer, all of which are sequentially connected. The dual-port frequency sweep excitation signal generation and intermediate frequency signal detection module is connected to a terahertz signal frequency doubling transmission module and a terahertz signal mixing detection module via a switch matrix. A signal transmission and adjustment device, a nanoprobe 19, a piezoelectric element 20, a two-port excitation source, and a three-dimensional scanning frame 21 for moving a sample 22 to be tested are provided between the terahertz signal frequency doubling transmission module and the terahertz signal mixing detection module. Nanoprobe 19 is positioned above sample 22, and piezoelectric element 20 controls the periodic vibration of nanoprobe 19. The two-port excitation source is connected to nanoprobe 19 and the IQ mixing amplification module.

[0057] 1. Dual-port swept frequency excitation signal generation and intermediate frequency signal detection module

[0058] like Figure 2As shown, the dual-port swept frequency excitation signal generation and intermediate frequency signal detection module includes a frequency reference unit, which is respectively connected to a fine swept frequency microwave source 1, a fine swept frequency microwave source 2, and a fine swept frequency microwave source 3, the fine swept frequency microwave source 1 is connected to an amplifier 1, the fine swept frequency microwave source 2 is connected to an amplifier 2, the fine swept frequency microwave source 3 is connected to an amplifier 3 and an amplifier 4 through a power divider, and the amplifier 3 and the amplifier 4 are respectively connected to a mixer 1 and a mixer 2; the amplifier 1 is connected to the RF signal input end of the switch matrix, the amplifier 2 is connected to the local oscillator signal input end of the switch matrix, the mixer 1 is connected to the reference signal output end of the switch matrix and the two-way low-noise amplification and mixing module, and the mixer 2 is connected to the reference signal output end of the switch matrix and the two-way low-noise amplification and mixing module.

[0059] The function of the frequency reference unit is to achieve the same frequency and phase of the fine-sweep microwave source 1, the fine-sweep microwave source 2 and the fine-sweep microwave source 3, ensuring that the three signal sources can generate radio frequency signals with the same frequency and phase.

[0060] The functions of the fine frequency swept microwave source 1, the fine frequency swept microwave source 2 and the fine frequency swept microwave source 3 are to simultaneously generate linear frequency modulated microwave signals with a frequency coverage of 10 MHz to 26.5 GHz, with a frequency resolution better than 1 Hz.

[0061] The function of the power divider is to split the microwave signal generated by the fine frequency swept microwave source 3 into two microwave signals.

[0062] The function of the amplifier 1 is to amplify and output the microwave signal generated by the fine frequency swept microwave source 1 as the input end of the radio frequency signal in the switch matrix.

[0063] The function of the second amplifier is to amplify and output the microwave signal generated by the second fine frequency swept microwave source as the input end of the local oscillator signal in the switch matrix.

[0064] The functions of amplifier three and amplifier four are to amplify and output the two microwave signals generated by the power divider, and serve as reference signal input terminals of mixer one and mixer two respectively.

[0065] The function of mixer 1 is to mix the test signal output by the terahertz signal mixing detection module with the reference signal input by amplifier 3 to obtain intermediate frequency signal 1.

[0066] The function of the second mixer is to mix the reference signal output by the terahertz signal frequency doubling transmission module with the reference signal input by the fourth amplifier to obtain the second intermediate frequency signal.

[0067] 2. Terahertz signal frequency doubling emission module and terahertz signal mixing detection module

[0068] The terahertz signal frequency doubling transmission module includes M terahertz signal frequency doubling transmission links 12, and the terahertz signal mixing detection module includes M terahertz signal mixing detectors 13, such as Figure 3 As shown, M terahertz signal frequency doubling transmission chains 12 and M terahertz signal frequency mixing detectors 13 are arranged in a circle on a five-degree-of-freedom precision adjustment frame 23 .

[0069] The function of the five-degree-of-freedom precision adjustment frame 23 is to control the terahertz signal frequency doubling transmission module and the terahertz signal mixing detection module to perform precise adjustment in the five directions of xyz, pitch and rotation.

[0070] In order to achieve full frequency band coverage of 50GHz to 3000GHz, the optional combinations of terahertz signal frequency doubling transmission modules include: one combination is 50GHz to 75GHz, 75GHz to 110GHz, 110GHz to 170GHz, 170GHz to 220GHz, 220GHz to 330GHz, 330GHz to 500GHz, 500GHz to 750GHz, 750GHz to 1100GHz, 1100GHz to 1700GHz, 1700GHz to 2200GHz, 2200GHz to 3000GHz, a total of 11 frequency bands, in this case M=11; the other combination is 50GHz to 60GHz, 60GHz to 90GHz, 90GHz to 140GHz, 140GHz to 260GHz There are 10 frequency bands in total: 260GHz to 400GHz, 400GHz to 600GHz, 600GHz to 900GHz, 900GHz to 1400GHz, 1400GHz to 2600GHz, and 2600GHz to 3000GHz. In this case, M = 10. The optional combination of the terahertz signal frequency mixing detection module is the same as that of the terahertz signal frequency doubling transmission module.

[0071] like Figure 4 As shown, the terahertz signal frequency doubling transmission link 12 includes one frequency doubling link and one frequency mixing link.

[0072] The frequency multiplication link includes a frequency multiplier A, amplifier five, frequency multiplier B, amplifier six, frequency multiplier C and a single directional coupler connected in sequence. The RF signal generated by the dual-port swept frequency excitation signal generation and intermediate frequency signal detection module is input into the frequency multiplier A. After a series of frequency multiplication amplification, the terahertz signal is output into free space.

[0073] The mixing link includes a G frequency multiplier, amplifier seven, F frequency multiplier, amplifier eight, E frequency multiplier, amplifier nine and D-subharmonic mixer connected in sequence. A single directional coupler is connected to the D-subharmonic mixer through an isolator to ensure that the terahertz signal can only flow from the frequency multiplication link to the mixing link, and vice versa.

[0074] The local oscillator signal generated by the dual-port swept frequency excitation signal generation and intermediate frequency signal detection module is input into the G frequency multiplier. After a series of frequency multiplication amplification, it is mixed with the terahertz signal input by the frequency multiplication link to output the reference signal.

[0075] The multiplication orders of the A multiplier, the B multiplier, the C multiplier, the G multiplier, the F multiplier, and the E multiplier are 2, 3, or 4, the harmonic order of the D-th harmonic mixer is 1, 2, 4, or 6, and they satisfy: A×B×C=G×F×E×D.

[0076] Taking the 750 GHz to 1100 GHz frequency band as an example, A = 3, B = 4, C = 6, G = 2, F = 3, E = 3, and D = 4. It should be noted that the above frequency multiplier times are only one implementation method of this embodiment and should not be construed as limiting the present invention.

[0077] The link composition of the terahertz signal frequency mixing detector 13 is the same as the frequency mixing link in the terahertz signal frequency doubling transmission link 12, such as Figure 5 As shown, the local oscillator signal generated by the dual-port swept-frequency excitation signal generation and intermediate frequency signal detection module is input into the G frequency multiplier of the terahertz signal mixing detector 13. The terahertz signal containing the test sample information is input into the D subharmonic mixer of the terahertz signal mixing detector 13. After a series of frequency multiplication and amplification, the local oscillator signal is mixed with the input terahertz signal to output the test signal. The function of the terahertz signal mixing detector 13 is to achieve high-sensitivity detection of scattered terahertz signals.

[0078] 3. Switch Matrix

[0079] The switch matrix in the embodiment of the present invention is a 4×M channel switch matrix, and the interface is as follows: Figure 6 As shown, it includes RF ports, local oscillator ports, test ports, and reference ports. The RF port includes one input port 0 and M output ports; the local oscillator port includes one input port 0 and 2M output ports; the test port includes one input port 0 and M output ports; and the reference port includes one input port 0 and M output ports. The value of M depends on the selected frequency band.

[0080] Taking a single frequency band as an example, the interface diagram between the dual-port sweep excitation signal generation and intermediate frequency signal detection module, the terahertz signal frequency doubling transmission module, the terahertz signal mixing detection module and the 4×M channel switch matrix is shown as follows: Figure 7As shown. The RF signal output by amplifier 1 in the dual-port sweep excitation signal generation and intermediate frequency signal detection module is connected to the input end of the RF port of the switch matrix, the local oscillator signal output by amplifier 2 in the dual-port sweep excitation signal generation and intermediate frequency signal detection module is connected to the input end of the local oscillator port of the switch matrix, the reference signal output by the Dth harmonic mixer in the terahertz signal frequency multiplication transmission module is connected to the input end of the reference port of the switch matrix, and the test signal output by the Dth harmonic mixer in the terahertz signal mixing detection module is connected to the input end of the test port of the switch matrix; the radiation port of the switch matrix Output terminal No. 5 of the frequency port is connected to the A frequency multiplier in the terahertz signal frequency doubling transmission module, output terminal No. 5 of the local oscillator port of the switch matrix is connected to the G frequency multiplier in the terahertz signal frequency doubling transmission module, output terminal No. 4 of the local oscillator port of the switch matrix is connected to the G frequency multiplier in the terahertz signal mixing detection module, output terminal No. 5 of the test port of the switch matrix is connected to mixer 1 in the dual-port swept frequency excitation signal generation and intermediate frequency signal detection module, and output terminal No. 5 of the reference port of the switch matrix is connected to mixer 2 in the dual-port swept frequency excitation signal generation and intermediate frequency signal detection module.

[0081] 4. Signal transmission adjustment device

[0082] like Figure 8 As shown, the signal transmission adjustment device includes a first terahertz lens antenna 1, a first transparent non-polarizing beam splitter 2, a first reflector 3, a second reflector 4, a third reflector 5, a parabolic mirror 6, a fourth reflector 7, a fifth reflector 8, a sixth reflector 9, a second transparent non-polarizing beam splitter 10 and a second terahertz lens antenna 11, which are arranged in sequence. The first terahertz lens antenna 1 is arranged on a terahertz signal frequency doubling transmission link 12, the second terahertz lens antenna 11 is arranged on a terahertz signal mixing detector 13, and the parabolic mirror 6 is arranged on a fourth reflector 7, a fifth reflector 8, a sixth reflector 9, a second transparent non-polarizing beam splitter 10 and a second terahertz lens antenna 11. The mirror 6 is located around the sample to be tested 22; a first visible laser emitter 14 is set on one side of the first transparent non-polarizing beam splitter 2, and a second visible laser emitter 15 is set on one side of the second transparent non-polarizing beam splitter 10; the first transparent non-polarizing beam splitter 2, the first reflector 3 and the second reflector 4 are located on the five-degree-of-freedom precision adjustment frame 2 16, the fifth reflector 8, the sixth reflector 9 and the second transparent non-polarizing beam splitter 10 are located on the five-degree-of-freedom precision adjustment frame 3 17, and the parabolic mirror 6 is located on the three-dimensional precision control frame 18.

[0083] The function of the first terahertz lens antenna 1 is to realize the output of the terahertz signal in parallel beam into free space for long-distance transmission, and the function of the second terahertz lens antenna 11 is to realize the input of the terahertz signal containing the information of the sample to be tested 22 into the terahertz signal mixing detector 13 in parallel beam.

[0084] The first visible laser emitter 14 emits a first visible laser, which is used to guide the propagation path of the terahertz signal to ensure that the terahertz signal emitted by the terahertz signal frequency doubling generation link can correctly reach the tip of the nanoprobe 19; the second visible laser emitter 15 emits a second visible laser, which is used to ensure that the terahertz signal scattered by the nanoprobe 19 can be detected by the terahertz signal mixing detector 13.

[0085] The first transparent non-polarizing beam splitter 2 and the second transparent non-polarizing beam splitter 10 (ITO) have the following functions: first, to ensure that the terahertz signal can be transmitted efficiently; second, to ensure that the visible laser can be transmitted along the same path as the terahertz signal. The thickness of ITO is c / (2B), where c=3×10 8 m / s, B is the bandwidth of each frequency band, from which we can know that different frequency bands require different ITO thicknesses.

[0086] The function of the five-degree-of-freedom precision adjustment frame 2 16 is to automatically realize the automatic precision adjustment of the first transparent non-polarizing beam splitter 2, the first reflector 3 and the second reflector 4 in the five directions of xyz-pitch-rotation according to the working frequency band selected by the software, so as to ensure that the terahertz signal in the working frequency band and the laser can work in the same way; the function of the five-degree-of-freedom precision adjustment frame 3 17 is to automatically realize the automatic precision adjustment of the fifth reflector 8, the sixth reflector 9 and the second transparent non-polarizing beam splitter 10 in the five directions of xyz-pitch-rotation according to the working frequency band selected by the software, so as to ensure that the terahertz signal in the working frequency band and the laser can work in the same way.

[0087] The function of the first to sixth reflecting mirrors 3 to 9 is to achieve strong reflection of the terahertz signal and the visible laser.

[0088] The function of the parabolic mirror 6 is to ensure that the terahertz signals of M frequency bands can be focused onto the tip of the nanoprobe 19.

[0089] The function of the nanoprobe 19 is to realize the interaction between the terahertz signal and the sample to be measured 22, coupling and realizing strong scattering at the same time.

[0090] The function of the piezoelectric body 20 is to precisely control the nanoprobe 19 to perform periodic vibration with a fixed frequency and a fixed amplitude.

[0091] The function of the three-dimensional precision control frame 18 is to realize the automatic positioning of the parabolic mirror 6 so that the terahertz signals of M frequency bands can be focused on the tip of the nanoprobe 19.

[0092] The function of the three-dimensional scanning frame 21 is to realize the three-dimensional movement of the sample 22 to be tested with nanometer-level precision.

[0093] 5. Other signal processing modules

[0094] The functions of the 2-port excitation source include two aspects: one is to output a sinusoidal wave signal with a fixed frequency and fixed period as the excitation signal of the nanoprobe 19; the other is to output a microwave signal with the same frequency and phase as the excitation signal of the nanoprobe 19 as the input reference signal of the IQ mixing amplifier module.

[0095] The function of the 2-way low-noise amplification and mixing module is to amplify the intermediate frequency signal 1 and the intermediate frequency signal 2 and then perform mixing processing to obtain the intermediate frequency signal 3 containing the sample detail information.

[0096] The function of the low-noise amplifier module is to amplify the intermediate frequency signal 3 containing sample detail information.

[0097] The function of the IQ mixing amplifier module is to realize the IQ mixing processing of the intermediate frequency signal 3 containing the sample detail information and the input reference signal of the IQ mixing amplifier module to obtain amplitude and phase information respectively.

[0098] The function of the high-speed data acquisition module is to realize the digital acquisition of amplitude and phase.

[0099] The entire testing software is built into the industrial computer, and the obtained amplitude and phase information can be used to achieve material imaging and composition analysis.

[0100] The present invention provides a large dynamic scattering terahertz material imaging and composition analysis method. The working principle of the above device includes the following process:

[0101] Step 1: The dual-port sweep frequency excitation signal generation and intermediate frequency signal detection module outputs the radio frequency signal and the local oscillator signal, which are transmitted to the terahertz signal frequency multiplication transmission module through the switch matrix, wherein the local oscillator signal is also transmitted to the terahertz signal mixing detection module through the switch matrix;

[0102] Step 2: The local oscillator signal is frequency-multiplied, amplified, and mixed in the terahertz signal frequency-multiplication transmission module to output a reference signal, which is then returned to the dual-port frequency-sweep excitation signal generation and intermediate frequency signal detection module after passing through the switch matrix; the radio frequency signal is frequency-multiplied and amplified in the terahertz signal frequency-multiplication transmission module to output a terahertz signal, which is then passed through the signal transmission and adjustment device to reach the sample to be tested 22, and interacts with the sample to be tested 22 under the action of the nanoprobe 19. The terahertz signal containing information about the sample to be tested 22 is passed through the signal transmission and adjustment device to reach the terahertz signal frequency mixing detection module, and is mixed with the local oscillator signal input to the module to obtain a test signal. The test signal is then returned to the dual-port frequency-sweep excitation signal generation and intermediate frequency signal detection module after passing through the switch matrix;

[0103] Step 3: The test signal and the reference signal are mixed in the dual-port swept frequency excitation signal generation and intermediate frequency signal detection module to obtain intermediate frequency signal 1 and intermediate frequency signal 2, and then transmitted to the two-way low-noise amplification and mixing module;

[0104] Step 4: After the IF signal 1 and the IF signal 2 are amplified and mixed in the two-way low-noise amplification and mixing module, the IF signal 3 containing the sample information is obtained. The IF signal 3 is amplified by the low-noise amplification module and then input into the IQ mixing amplification module.

[0105] In step 5, the 2-port excitation source outputs a microwave signal as the input reference signal of the IQ mixer amplifier module. The intermediate frequency signal 3 is mixed with the input reference signal in the IQ mixer amplifier module to obtain amplitude and phase information respectively. Finally, it is collected by the data acquisition module and transmitted to the industrial computer.

[0106] The specific analysis methods include point frequency working mode and sweep frequency working mode. The point frequency working mode is used to achieve material imaging, and the sweep frequency working mode is used for component analysis.

[0107] The dot frequency working mode includes the following steps:

[0108] Step 1: Place the sample 22 to be tested on the three-dimensional scanning frame 21 to achieve automatic positioning of the sample and obtain the starting position information (x0, y0) of the sample 22 to be tested within the test area;

[0109] Step 2, parameter setting: including terahertz signal frequency f0, signal power, imaging range (1 μm × 1 μm to 100 μm × 100 μm), number of pixels (128 × 128 to 4096 × 4096), scanning speed (0.1 Hz to 2 Hz), vibration frequency and amplitude of the nanoprobe 19;

[0110] Step 3: The piezoelectric body 20 controls the nanoprobe 19 to perform sinusoidal vibration with a set frequency and amplitude;

[0111] Step 4: At the sample starting position (x0, y0), the terahertz signal frequency doubling transmission module generates a terahertz signal with a set frequency of f0, which passes through the first terahertz lens antenna 1, the first transparent non-polarizing beam splitter 2, the first reflector 3, the second reflector 4, the third reflector 5, and the parabolic mirror 6 to the surface of the sample to be tested 22. Under the action of the nanoprobe 19, the terahertz signal interacts with the sample to be tested 22. The terahertz signal containing detailed information of the sample to be tested 22 passes through the parabolic mirror 6, the fourth reflector 7, the fifth reflector 8, the sixth reflector 9, the second transparent non-polarizing beam splitter 10, and the second terahertz lens antenna 11 to the terahertz signal mixing detection module to obtain a test signal;

[0112] Step 5: The test signal and the reference signal are demodulated to obtain the amplitude and phase of the terahertz signal scattered by the sample 22 at the position (x0, y0);

[0113] Step 6: Under the control of the three-dimensional scanning frame 21, the nanoprobe 19 moves to the position (x1, y1) of the sample 22 to be tested. Repeat steps 4 to 5 to obtain the amplitude and phase of the terahertz signal scattered by the sample 22 to be tested at the position (x1, y1); and so on until the entire sample is traversed, and finally the amplitude and phase of the terahertz signal scattered by the sample 22 to be tested at the position (x1, y1) are obtained. N ,y N ) position;

[0114] Step 7, thereby obtaining the amplitude matrix and phase matrix of the sample to be tested 22, and based on the imaging algorithm built into the industrial computer, realizing the image α0 of the sample to be tested 22 at the frequency of the terahertz signal f0;

[0115] Step 8, resetting the terahertz signal frequency f1 and signal power;

[0116] Step 9, repeating steps 3 to 7 to obtain an image α1 of the sample 22 under the terahertz signal frequency f1;

[0117] Step 10, and so on, until the image set of all the set frequencies is obtained.

[0118] Step 11, based on the multi-image fusion algorithm built into the industrial computer, a two-dimensional or three-dimensional image is finally obtained, such as Figure 9 Image of the gold-silicon interface shown.

[0119] The sweep frequency working mode includes the following steps:

[0120] 1) Place the sample 22 to be tested on the three-dimensional scanning frame 21 to automatically position the sample 22 to be tested and obtain the center position (x c ,y c );

[0121] 2) Parameter settings: including the terahertz signal starting frequency f1, ending frequency f2, frequency resolution (≥100 Hz), signal power, scanning speed (0.1 Hz to 2 Hz), probe vibration frequency and vibration amplitude (the vibration amplitude is generally the probe resonance amplitude × 0.8, and the frequency corresponding to this amplitude is selected as the vibration frequency);

[0122] 3) The piezoelectric body 20 controls the nanoprobe 19 to perform sinusoidal vibrations of set frequency and amplitude;

[0123] 4) In the sample (x c ,y c) position, the terahertz signal frequency doubling emission module generates a terahertz signal with a frequency of f1-f2 according to a specific frequency resolution, and passes through the first terahertz lens antenna 1, the first transparent non-polarizing beam splitter 2, the first reflector 3, the second reflector 4, the third reflector 5, and the parabolic mirror 6 to the surface of the sample to be tested 22 in sequence, and interacts with the sample to be tested 22 under the action of the nanoprobe 19. The terahertz signal containing detailed information of the sample to be tested 22 passes through the parabolic mirror 6, the fourth reflector 7, the fifth reflector 8, the sixth reflector 9, the second transparent non-polarizing beam splitter 10 and the second terahertz lens antenna 11 to the terahertz signal mixing detection module to obtain a test signal;

[0124] 5) The test signal and the reference signal are demodulated to obtain the sample to be tested 22 at (x c ,y c ) position, such as the amplitude and phase of the scattered terahertz signal Figure 10 The scattered terahertz near-field spectrum of the gold-silicon interface is shown;

[0125] 6) Based on the material composition analysis algorithm built into the industrial computer, the composition information of the sample to be tested 22 is finally obtained.

[0126] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A large dynamic scattering terahertz material imaging and composition analysis device, characterized in that: It includes a dual-port sweep frequency excitation signal generation and intermediate frequency signal detection module, a two-way low-noise amplification and mixing module, a low-noise amplification module, an IQ mixing amplification module, a data acquisition module and an industrial control computer, which are sequentially connected to each other. The dual-port sweep frequency excitation signal generation and intermediate frequency signal detection module are respectively connected to a terahertz signal frequency doubling transmission module and a terahertz signal frequency mixing detection module through a switch matrix. A signal transmission adjustment device, a nanoprobe, a piezoelectric body, a two-port excitation source and a three-dimensional scanning frame for moving a sample to be tested are arranged between the terahertz signal frequency doubling transmission module and the terahertz signal frequency mixing detection module. The nanoprobe is located above the sample to be tested, and the piezoelectric body controls the nanoprobe to perform periodic vibration. The two-port excitation source is respectively connected to the nanoprobe and the IQ mixing amplification module. The dual-port frequency sweep excitation signal generation and intermediate frequency signal detection module includes a frequency reference unit, which is respectively connected to a fine frequency sweep microwave source 1, a fine frequency sweep microwave source 2, and a fine frequency sweep microwave source 3. The fine frequency sweep microwave source 1 is connected to an amplifier 1, the fine frequency sweep microwave source 2 is connected to an amplifier 2, and the fine frequency sweep microwave source 3 is connected to an amplifier 3 and an amplifier 4 through a power divider. The amplifier 3 and the amplifier 4 are respectively connected to a mixer 1 and a mixer 2; the amplifier 1 is connected to the radio frequency signal input end of the switch matrix, the amplifier 2 is connected to the local oscillator signal input end of the switch matrix, the mixer 1 is connected to the reference signal output end of the switch matrix and the two-way low-noise amplification and mixing module, and the mixer 2 is connected to the reference signal output end of the switch matrix and the two-way low-noise amplification and mixing module; The terahertz signal frequency doubling transmission module includes M terahertz signal frequency doubling transmission links, and the terahertz signal frequency mixing detection module includes M terahertz signal frequency mixing detectors. The M terahertz signal frequency doubling transmission links and the M terahertz signal frequency mixing detectors are arranged in a circle on a five-degree-of-freedom precision adjustment frame. The terahertz signal frequency multiplication transmission link includes a frequency multiplication link and a frequency mixing link. The frequency multiplication link includes an A frequency multiplier, an amplifier five, a B frequency multiplier, an amplifier six, a C frequency multiplier, and a single directional coupler connected in sequence to realize the transmission of the terahertz signal into free space; the frequency mixing link includes a G frequency multiplier, an amplifier seven, an F frequency multiplier, an amplifier eight, an E frequency multiplier, an amplifier nine, and a D-subharmonic mixer connected in sequence to realize the output of the reference signal; the single directional coupler is connected to the D-subharmonic mixer through an isolator; the link composition of the terahertz signal frequency mixing detector is the same as the frequency mixing link in the terahertz signal frequency multiplication transmission link; The multiplication orders of the A frequency multiplier, B frequency multiplier, C frequency multiplier, G frequency multiplier, F frequency multiplier and E frequency multiplier are 2, 3 or 4, the harmonic order of the D-th harmonic mixer is 1, 2, 4 or 6, and satisfy: A×B×C=G×F×E×D.

2. The large dynamic scattering terahertz material imaging and composition analysis device according to claim 1, characterized in that: The signal transmission adjustment device includes a first terahertz lens antenna, a first transparent non-polarizing beam splitter, a first reflector, a second reflector, a third reflector, a parabolic mirror, a fourth reflector, a fifth reflector, a sixth reflector, a second transparent non-polarizing beam splitter and a second terahertz lens antenna, which are arranged in sequence. The first terahertz lens antenna is arranged on a terahertz signal frequency doubling transmission module, the second terahertz lens antenna is arranged on a terahertz signal frequency mixing detection module, and the parabolic mirror is located around the sample to be measured; a first visible laser emitter is arranged on one side of the first transparent non-polarizing beam splitter, and a second visible laser emitter is arranged on one side of the second transparent non-polarizing beam splitter; the first transparent non-polarizing beam splitter, the first reflector and the second reflector are located on a five-degree-of-freedom precision adjustment frame second, the fifth reflector, the sixth reflector and the second transparent non-polarizing beam splitter are located on a five-degree-of-freedom precision adjustment frame third, and the parabolic mirror is located on a three-dimensional precision control frame.

3. A large dynamic scattering terahertz material imaging and component analysis method, using the large dynamic scattering terahertz material imaging and component analysis device according to claim 1, characterized in that: The process includes the following: Step 1: The dual-port sweep frequency excitation signal generation and intermediate frequency signal detection module outputs the radio frequency signal and the local oscillator signal, which are transmitted to the terahertz signal frequency multiplication transmission module through the switch matrix, wherein the local oscillator signal is also transmitted to the terahertz signal mixing detection module through the switch matrix; Step 2: The local oscillator signal is frequency-multiplied, amplified, and mixed in the terahertz signal frequency-multiplication transmission module to output a reference signal, which is then returned to the dual-port frequency-sweep excitation signal generation and intermediate frequency signal detection module after passing through the switch matrix; the radio frequency signal is frequency-multiplied and amplified in the terahertz signal frequency-multiplication transmission module to output a terahertz signal, which is then passed through a signal transmission and adjustment device to reach the sample to be tested, and interacts with the sample to be tested under the action of the nanoprobe. The terahertz signal containing information about the sample to be tested is passed through the signal transmission and adjustment device to reach the terahertz signal frequency mixing detection module, and is mixed with the local oscillator signal input to the module to obtain a test signal. The test signal is then returned to the dual-port frequency-sweep excitation signal generation and intermediate frequency signal detection module after passing through the switch matrix; Step 3: The test signal and the reference signal are mixed in the dual-port swept frequency excitation signal generation and intermediate frequency signal detection module to obtain intermediate frequency signal 1 and intermediate frequency signal 2, and then transmitted to the two-way low-noise amplification and mixing module; Step 4: After the IF signal 1 and the IF signal 2 are amplified and mixed in the two-way low-noise amplification and mixing module, the IF signal 3 containing the sample information is obtained. The IF signal 3 is amplified by the low-noise amplification module and then input into the IQ mixing amplification module. In step 5, the 2-port excitation source outputs a microwave signal as the input reference signal of the IQ mixer amplifier module. The intermediate frequency signal 3 is mixed with the input reference signal in the IQ mixer amplifier module to obtain amplitude and phase information respectively. Finally, it is collected by the data acquisition module and transmitted to the industrial computer.

4. The large dynamic scattering terahertz material imaging and composition analysis method according to claim 3, characterized in that: The analysis method includes two working modes: a point frequency working mode and a sweep frequency working mode. The point frequency working mode is used to realize material imaging, and the sweep frequency working mode is used to perform component analysis.

5. The large dynamic scattering terahertz material imaging and composition analysis method according to claim 4, characterized in that: The dot frequency working mode includes the following steps: Step 1: Place the sample to be tested on the 3D scanning frame to achieve automatic positioning of the sample and obtain the starting position information of the sample to be tested in the test area ( x 0, y 0); Step 2, parameter setting: including terahertz signal frequency f 0. Signal power, imaging range, number of pixels, scanning speed, nanoprobe vibration frequency and vibration amplitude; Step 3: The piezoelectric body controls the nanoprobe to perform sinusoidal vibration with a set frequency and amplitude; Step 4, at the sample starting position ( x 0, y 0), the terahertz signal frequency doubling transmission module generates a set frequency of f The terahertz signal of 0 passes through the first terahertz lens antenna, the first transparent non-polarizing beam splitter, the first reflector, the second reflector, the third reflector, and the parabolic mirror in sequence to the surface of the sample to be tested, and interacts with the sample to be tested under the action of the nanoprobe. The terahertz signal containing detailed information of the sample to be tested passes through the parabolic mirror, the fourth reflector, the fifth reflector, the sixth reflector, the second transparent non-polarizing beam splitter, and the second terahertz lens antenna to the terahertz signal mixing detection module to obtain a test signal; Step 5: The test signal and the reference signal are demodulated to obtain the sample to be tested ( x 0, y 0) The amplitude and phase of the scattered terahertz signal at position; Step 6: Under the control of the 3D scanning frame, the nanoprobe moves to the sample to be tested ( x 1, y 1) position, repeat steps 4-5 to obtain the sample to be tested at ( x 1, y 1) The amplitude and phase of the scattered terahertz signal at the position; and so on until the entire sample is traversed, and finally the sample to be tested is obtained at ( x N , y N ) The amplitude and phase of the scattered terahertz signal at the position; Step 7, thus obtaining the amplitude matrix and phase matrix of the sample to be tested, based on the imaging algorithm built into the industrial computer, the sample to be tested is f Image at 0 frequency α 0; Step 8: Reset the terahertz signal frequency f 1. Signal power; Step 9, repeat steps 3 to 7 to achieve the test sample under the terahertz signal f Image at 1 frequency α 1; Step 10, and so on, until the image set ℜ of all the set frequencies is obtained; Step 11: Based on the multi-image fusion algorithm built into the industrial computer, a two-dimensional or three-dimensional topography image is finally obtained.

6. The large dynamic scattering terahertz material imaging and composition analysis method according to claim 4, characterized in that: The frequency sweeping working mode comprises the following steps: 1) Place the sample to be tested on the 3D scanning frame to automatically locate the sample to be tested and obtain the center position of the sample within the test area ( x c , y c ); 2) Parameter setting: including the starting frequency of the terahertz signal f 1. Stop frequency f 2. Frequency resolution, signal power, scanning speed, probe vibration frequency and vibration amplitude; 3) The piezoelectric body controls the nanoprobe to perform sinusoidal vibrations of set frequency and amplitude; 4) In the sample ( x c , y c ) position, the terahertz signal frequency doubling transmission module generates a frequency of f 1- f 2, passes through the first terahertz lens antenna, the first transparent non-polarizing beam splitter, the first reflector, the second reflector, the third reflector, and the parabolic mirror to the surface of the sample to be tested, and interacts with the sample to be tested under the action of the nanoprobe. The terahertz signal containing detailed information of the sample to be tested passes through the parabolic mirror, the fourth reflector, the fifth reflector, the sixth reflector, the second transparent non-polarizing beam splitter, and the second terahertz lens antenna to the terahertz signal mixing detection module to obtain a test signal; 5) The test signal and the reference signal are demodulated to obtain the sample to be tested ( x c , y c ) The amplitude and phase of the scattered terahertz signal at the position; 6) Based on the material composition analysis algorithm built into the industrial computer, the composition information of the sample to be tested is finally obtained.

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