A terahertz self-correlation near-field imaging spectrograph system

Abstract

This invention discloses a terahertz autocorrelation near-field imaging spectroscopy system, relating to the interdisciplinary field of micro-nano photonics and terahertz photoelectric detection. The system includes: a terahertz emitter, an optical path adjustment unit, a scattering near-field scanning microscope, a terahertz receiver, a current amplifier, a lock-in amplifier, and a processor. This invention employs autocorrelation near-field imaging spectroscopy, which can obtain the time-domain information of terahertz waves by performing autocorrelation measurements on terahertz pulses. The autocorrelation near-field imaging spectroscopy method in this invention also has the ability to enhance signal intensity and suppress background noise. By controlling the optical path difference and adjusting the optical path, the two signals are accumulated to achieve a modulation of the probe resonance effect, which is beneficial for studying the resonance characteristics of the sample itself.

Description

Technical Field

[0001] This invention relates to the interdisciplinary field of micro-nano photonics and terahertz photoelectric detection, specifically to a terahertz autocorrelation near-field imaging spectroscopy system. Background Technology

[0002] Near-field optical microscopy based on terahertz time-domain spectrometers can achieve both nanoscale terahertz imaging and terahertz spectral generation. However, the terahertz power generated by the terahertz optical guide antenna is typically in the tens of microwatts range, and the size of the probe tip radius differs significantly from the terahertz wavelength, resulting in low near-field coupling efficiency. To improve terahertz scattering efficiency, the probe is made of metal and its length is comparable to the terahertz wavelength. However, this leads to probe resonance in the near-field terahertz spectrum, which is detrimental to the detection of the sample's near-field spectrum. Summary of the Invention

[0003] To achieve terahertz autocorrelation near-field imaging spectroscopy and enable adjustment of probe resonance, this invention provides a terahertz autocorrelation near-field imaging spectroscopy system, the system comprising:

[0004] Terahertz transmitter, optical path adjustment unit, scattering near-field scanning microscope, terahertz receiver, current amplifier, lock-in amplifier and processor;

[0005] The terahertz transmitter is used to generate a first terahertz pulse signal;

[0006] The optical path adjustment unit is used to split the first terahertz pulse signal into a second terahertz pulse signal and a third terahertz pulse signal, and to process the second terahertz pulse signal and irradiate it onto the sample to generate a first near-field signal, and to process the third terahertz pulse signal and irradiate it onto the sample to generate a second near-field signal, and to adjust the time delay difference between the first near-field signal and the second near-field signal.

[0007] The terahertz receiver is used to receive the first near-field signal and the second near-field signal;

[0008] The current amplifier is used to amplify the signal received by the terahertz receiver to obtain an amplified near-field signal, and the lock-in amplifier is used to demodulate the amplified near-field signal to obtain a demodulated signal.

[0009] The processor is used to process the demodulated signal to obtain sample surface information, and to superimpose the demodulated signals corresponding to the first near-field signal and the second near-field signal, and to study the resonance effect of the sample itself based on the superposition result.

[0010] Scattering near-field scanning microscopy is used to illuminate a sample with a terahertz pulse signal, and to acquire a near-field imaging signal containing information about the sample surface using a probe, thereby imaging the sample surface based on the near-field imaging signal.

[0011] This system utilizes a terahertz transmitter to generate a first terahertz pulse signal. Then, an optical path adjustment unit splits the first terahertz pulse signal into two signals with different optical path differences. This facilitates autocorrelation measurement of the terahertz signal and measurement of the probe resonance effect. This design introduces a time delay into near-field measurements, further enabling autocorrelation near-field spectroscopy. A terahertz receiver receives the first and second near-field signals. A current amplifier amplifies the received signal to obtain an amplified near-field signal, and a lock-in amplifier demodulates the amplified near-field signal to obtain a demodulated signal. A processor processes the demodulated signal to obtain sample surface information, and the demodulated signals corresponding to the first and second near-field signals are superimposed. Based on the superposition result, the resonance effect of the sample itself is studied more clearly. A scattering near-field scanning microscope illuminates the sample surface with the terahertz pulse signal, and a probe acquires a near-field imaging signal containing sample surface information. Based on the near-field imaging signal, the sample surface is imaged. Thus, this system achieves terahertz autocorrelation near-field imaging spectroscopy and probe resonance measurement.

[0012] In some embodiments, the optical path adjustment unit includes:

[0013] The system comprises a first lens, a second lens, and first to sixth reflectors; wherein, a terahertz transmitter generates a first terahertz pulse signal, which is split into a second terahertz pulse signal and a third terahertz pulse signal by the first lens. The second terahertz pulse signal is reflected sequentially by the first to third reflectors and then enters the second lens, and the third terahertz pulse signal is reflected sequentially by the fourth to sixth reflectors and then enters the second lens; wherein, the second and third reflectors are the first reflection modules, and the fourth and fifth reflectors are the second reflection modules, and the time delay difference between the first near-field signal and the second near-field signal is adjusted by laterally moving the first reflection module and / or the second reflection module.

[0014] The purpose of the first lens is to evenly split the signal into two beams. The first to sixth reflectors reflect the split signals with different optical paths, so that the two signals directly generate a time delay. The specific adjustment method is to move the first reflection module and / or the second reflection module laterally. By moving one or both of the above two modules, the length of the signal transmission path can be adjusted, thereby adjusting the time delay difference between the two signals.

[0015] In some embodiments, the optical path adjustment unit further includes a first parabolic mirror and a second parabolic mirror. The first parabolic mirror is used to converge the signal emitted by the optical path adjustment unit onto the sample surface, and the second parabolic mirror is used to receive the near-field signal generated on the sample and then transmit it to the terahertz receiver.

[0016] In some embodiments, the terahertz transmitter includes a femtosecond laser and an optical guide antenna, wherein the femtosecond laser is used to generate a femtosecond laser to excite the optical guide antenna to generate a terahertz pulse signal.

[0017] In some embodiments, the optical path adjustment unit is further configured to adjust the optical path difference between the first near-field signal and the second near-field signal to perform autocorrelation measurement on the terahertz pulse signal to obtain the time-domain information of the terahertz wave.

[0018] In some embodiments, the optical antenna includes a photoconductive layer and an antenna structure.

[0019] In some embodiments, the first lens is a first high-resistivity silicon lens, and the second lens is a second high-resistivity silicon lens. The use of high-resistivity silicon lenses enables the realization of semi-transparent, semi-reflective terahertz waves.

[0020] In some embodiments, the probe tip size of a scattering near-field scanning microscope has a subwavelength structure, which can achieve higher resolution.

[0021] In some embodiments, when the first reflective module moves, the second and third reflective mirrors move synchronously, and when the second reflective module moves, the fourth and fifth reflective mirrors move synchronously. Synchronous movement ensures a normal reflection path for the optical path and guarantees normal signal transmission.

[0022] In some embodiments, the first to sixth reflectors are silver-plated reflectors. Silver-plated reflectors can effectively reflect signals and reduce signal loss.

[0023] One or more technical solutions provided by this invention have at least the following technical effects or advantages:

[0024] This invention employs autocorrelation near-field imaging spectroscopy, acquiring time-domain information of terahertz waves through autocorrelation measurements of terahertz pulses. Compared to traditional frequency-domain analysis methods, time-domain information contains richer frequency components and waveform characteristics, providing more comprehensive and accurate sample information. Through processing and analysis of the autocorrelation signal, high-resolution near-field imaging spectroscopy results can be obtained, revealing the microstructure and physical properties of the sample. Furthermore, the autocorrelation near-field imaging spectroscopy method in this invention also has the ability to enhance signal intensity and suppress background noise. By controlling the optical path difference and adjusting the optical path, the two signals are accumulated, which can adjust the probe antenna resonance effect, making it more conducive to studying the resonance characteristics of the sample itself. This allows the detected near-field signal to be extracted from background noise, improving signal intensity and signal-to-noise ratio, thereby improving the reliability and accuracy of the measurement results. In summary, the autocorrelation near-field imaging spectroscopy system based on scattering near-field technology in this invention has a more accurate and comprehensive sample information acquisition capability compared to traditional methods, enabling high-resolution near-field imaging and spectral analysis. The application of this system will promote research and application in the field of micro-nano photonics, and provide a powerful tool for materials science, biomedicine and other fields. Attached Figure Description

[0025] The accompanying drawings, which are provided to further illustrate embodiments of the invention and constitute a part of this invention, are not intended to limit the scope of the invention.

[0026] Figure 1 This is a schematic diagram of a terahertz autocorrelation near-field imaging spectroscopy system.

[0027] Among them, 1-terahertz transmitter, 2-first lens, 3-first reflector, 4-second reflector, 5-third reflector, 6-fourth reflector, 7-fifth reflector, 8-sixth reflector, 9-second lens, 10-second parabolic mirror, 11-terahertz receiver, 12-scattering near-field scanning microscope, 13-first parabolic mirror. Detailed Implementation

[0028] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, where there is no conflict, the embodiments of the present invention and the features thereof can be combined with each other.

[0029] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0030] Example 1

[0031] Please refer to Figure 1 , Figure 1 This is a schematic diagram of a terahertz autocorrelation near-field imaging spectroscopy system, which includes:

[0032] Terahertz transmitter, optical path adjustment unit, scattering near-field scanning microscope, terahertz receiver, current amplifier, lock-in amplifier and processor;

[0033] The terahertz transmitter is used to generate a first terahertz pulse signal;

[0034] The optical path adjustment unit is used to split the first terahertz pulse signal into a second terahertz pulse signal and a third terahertz pulse signal, and to process the second terahertz pulse signal and irradiate it onto the sample to generate a first near-field signal, and to process the third terahertz pulse signal and irradiate it onto the sample to generate a second near-field signal, and to adjust the time delay difference between the first near-field signal and the second near-field signal.

[0035] The terahertz receiver is used to receive the first near-field signal and the second near-field signal;

[0036] The current amplifier is used to amplify the signal received by the terahertz receiver to obtain an amplified near-field signal, and the lock-in amplifier is used to demodulate the amplified near-field signal to obtain a demodulated signal.

[0037] The processor is used to process the demodulated signal to obtain sample surface information, and to superimpose the demodulated signals corresponding to the first near-field signal and the second near-field signal, and to study the resonance effect of the sample itself based on the superposition result.

[0038] Scattering near-field scanning microscopy is used to illuminate a sample with a terahertz pulse signal, and to acquire a near-field imaging signal containing information about the sample surface using a probe, thereby imaging the sample surface based on the near-field imaging signal.

[0039] A near-field scattering microscope (NFS) is a microscope capable of detecting the near-field distribution of an object's surface. It primarily consists of a terahertz optical path and an atomic force microscope (AFM). Terahertz waves converge at the tip of the AFM via an off-axis parabolic surface, creating a strong localized field between the probe and the sample. During the interaction between the probe and the terahertz waves, an electric dipole is formed, converting the localized terahertz field into a propagating scattered field. To detect this weak scattered field from the background signal, the probe typically operates in tapping mode, modulating the scattered field. Subsequent demodulation allows for the detection of the scattered field. The resolution of near-field imaging is essentially the same as the radius of the AFM tip, thus reaching the tens of nanometers level.

[0040] An optical guide antenna is a device that utilizes semiconductors (typically gallium arsenide and sapphire silicon wafers) and a bimetallic antenna to generate or detect pulsed terahertz signals. When used as a terahertz transmitter, it requires excitation by a femtosecond laser and a DC high voltage applied between the bimetallic antennas. When used as a detector, the optical guide antenna simultaneously inputs the femtosecond laser and the terahertz signal to be measured between the bimetallic electrodes. The femtosecond laser acts as a terahertz signal acquisition switch; by adjusting the external time-delay optical path, the phase difference between the excitation lasers at the transmitter and detector ends is changed, thereby acquiring the complete terahertz time-domain signal.

[0041] In some embodiments, the photoconductive antenna includes a photoconductive layer and an antenna structure. The structure of a terahertz photoconductive antenna generally consists of two parts: a photoconductive layer and an antenna structure. The photoconductive layer is typically made of semiconductor material, and the antenna structure can take different forms, such as microstrip antennas or antenna arrays.

[0042] This invention proposes an autocorrelation near-field imaging spectroscopy system based on scattering-based near-field technology. The system utilizes multiple high-resistivity silicon mirrors and plane mirrors to construct an optical path, ensuring a time delay difference between the two detected near-field signals. By adjusting the positions of the plane mirrors, the optical path difference is controlled, thereby achieving autocorrelation measurement of terahertz waves. In practical applications, the applicant discovered that due to the presence of the needle tip, the measured near-field signal includes not only the near-field signal excited by the interaction between the laser source and the sample under test, but also a signal that is coupled with the needle tip and reflected from the cantilever end to the tip tip and scattered. This system controls the optical path difference between the two terahertz pulses by adjusting the optical path. The sum of the two signals changes the overall signal spectrum, thereby adjusting the resonance effect of the probe antenna, which is beneficial for studying the resonance characteristics of the sample itself. This will point to a direction for the development of scattering-based near-field spectroscopy technology.

[0043] The technical solution adopted in this invention is as follows:

[0044] like Figure 1 As shown, an autocorrelation near-field spectroscopy system based on a scattering near-field scanning microscope includes a terahertz transmitter 1, an optical path adjustment unit, a scattering near-field scanning microscope 12, a terahertz receiver 11, a current amplifier, a lock-in amplifier, and a processor.

[0045] The optical path adjustment unit includes:

[0046] The system comprises a first lens 2, a second lens 9, a first reflector 3, a second reflector 4, a third reflector 5, a fourth reflector 6, a fifth reflector 7, and a sixth reflector 8; wherein, a terahertz transmitter generates a first terahertz pulse signal, which is split into a second terahertz pulse signal and a third terahertz pulse signal by the first lens. The second terahertz pulse signal is reflected sequentially by the first to third reflectors and then enters the second lens, and the third terahertz pulse signal is reflected sequentially by the fourth to sixth reflectors and then enters the second lens; wherein, the second and third reflectors are the first reflection modules, and the fourth and fifth reflectors are the second reflection modules, and the time delay difference between the first near-field signal and the second near-field signal is adjusted by laterally moving the first reflection module and / or the second reflection module.

[0047] The first lens 2 and the second lens 9 are high-resistivity silicon lenses (BS), and the first reflector 3, the second reflector 4, the third reflector 5, the fourth reflector 6, the fifth reflector 7 and the sixth reflector 8 are silver-plated reflectors.

[0048] In some embodiments, the optical path adjustment unit further includes a first parabolic mirror 13 and a second parabolic mirror 10. The first parabolic mirror is used to converge the signal emitted by the optical path adjustment unit onto the sample surface, and the second parabolic mirror is used to receive the near-field signal generated on the sample and then transmit it to the terahertz receiver.

[0049] A femtosecond laser is used to generate a femtosecond laser beam, which excites a transmitting optical guide antenna to generate a terahertz pulse signal. The terahertz pulse is split into two beams by a first high-resistivity silicon mirror (BS). One beam passes through the first to third reflecting mirrors and reaches the second high-resistivity silicon mirror (BS). After reflection, the beam converges and interacts with the sample to generate the first near-field signal. The other laser beam reaches the second high-resistivity silicon mirror (BS) after multiple reflections. After transmission, it converges and interacts with the sample to generate the second near-field signal. Both signals are received by the optical guide antenna, whose rear end is sequentially connected to a current amplifier and a lock-in amplifier.

[0050] High-resistivity silicon (BS) mirrors are used to split terahertz beams, thereby creating a time delay difference in the signal under test. By accumulating the two signals, the spectrum of the near-field signal is effectively changed, which is beneficial for studying the resonant characteristics of the sample itself.

[0051] Scattering near-field scanning microscopy is based on near-field optics and the tapping scanning mode of atomic force microscopy. Terahertz pulse signals generated by a terahertz emitter via a light-guided antenna are focused onto the sample surface through an external optical path. When the terahertz waves interact with the sample surface, scattering occurs. The probe amplifies the weak near-field signal, converting the localized terahertz field into a propagating scattered field. These scattered near-field signals contain information related to the localized interactions with the sample, providing high-resolution surface morphology and optical properties.

[0052] In the tapping mode, a small-amplitude, high-frequency excitation force is applied to the probe using piezoelectric ceramics, causing the probe to vibrate back and forth on the sample surface. After the atomic force laser is incident on the cantilever surface of the probe, it is reflected to the four-quadrant receiver. When the probe contacts the uneven surface of the sample, a certain force is generated between the tip and the sample, which reflects the signal to the four-quadrant receiver. After processing, topological imaging is achieved.

[0053] The optical guide antenna is a device composed of semiconductor materials (such as gallium arsenide or sapphire silicon wafers) and a bimetallic antenna. It can convert near-field signals into electrical signals, which can then be amplified and processed by electronic devices.

[0054] The method for autocorrelation near-field spectroscopy based on scattering near-field scanning microscopy using this system includes the following steps:

[0055] S1: Constructing the time-delay optical path. This can be achieved using multiple high-resistivity silicon (BS) mirrors and silver-plated reflectors. By adjusting the position and angle of these optical elements, the split terahertz waves can be made to arrive at the sample surface at different times, thus creating an optical path difference. This design allows for the introduction of a time delay in near-field measurements, further enabling autocorrelation near-field spectroscopy measurements. The construction of the time-delay optical path is crucial for achieving accurate time delays.

[0056] S2 Autocorrelation Measurement: This method utilizes a time-delayed optical path and terahertz autocorrelation to measure the autocorrelation of terahertz pulses, obtaining the time-domain information of the terahertz wave. Terahertz autocorrelation is a process of accumulating the input signal with its own delayed signal; by changing the delay time, the autocorrelation signal of the terahertz wave can be obtained.

[0057] S3 Near-Field Imaging: Terahertz laser light is guided to a near-field probe. The near-field probe can be a metal probe or a fiber optic probe, with a subwavelength-sized structure at its tip. The terahertz wave is focused onto the sample surface by a parabolic mirror. As the probe approaches the sample surface, an interaction occurs between the near-field probe and the sample, generating a near-field effect. These interactions lead to localized enhancement and scattering of the terahertz wave, thus producing a near-field signal containing information about the sample surface. Due to the special structure of the near-field probe, a strong local field can be formed between the probe and the sample, enabling high-resolution imaging. In actual measurements, the near-field signal is scattered using an atomic force microscope (AFM). The AFM has a nanoscale probe that can measure the fine structure of the sample surface. Changes in the near-field signal can be detected when the probe vibrates on the sample surface. This change can be obtained by adjusting the relative motion between the probe and the sample. By demodulating the near-field signal using a lock-in amplifier, high-resolution information about the sample surface can be obtained using a near-field imaging system.

[0058] S4 data processing: By performing a Fourier transform on the autocorrelation signal, the time-domain signal is converted into a frequency-domain signal, yielding the spectral information of the terahertz wave. This spectral information can be used for material property analysis, composition identification, and other applications.

[0059] This invention utilizes a terahertz laser generated by a photoconductive antenna terahertz transmitter and adjusts the optical path through a series of optical components. First, the laser beam is split into two beams by a first high-resistivity silicon mirror (BS). One beam passes through multiple silver-plated mirrors, and the other beam passes through multiple silver-plated mirrors. Finally, the two laser beams are reflected or transmitted by a second high-resistivity silicon mirror (BS) to a parabolic mirror, where they are focused onto the sample surface and interact with the sample. In practical applications, the measurement of near-field signals faces several challenges, one of which is the presence of the probe tip. Besides the near-field signal excited by the interaction with the laser source, there is also a signal coupled to the probe tip and scattered to the tip after secondary reflection. To effectively extract the detected near-field signal and improve the signal strength and signal-to-noise ratio, and to adjust the probe antenna resonance effect, this invention employs a strategy of controlling the optical path difference and adjusting the optical path. By controlling the optical path difference, i.e., using the high-resistivity silicon mirror and silver-plated mirrors, an appropriate time delay can be introduced, creating a time difference between the signal scattered by the probe tip and the original signal. During signal accumulation, the two signals can be effectively superimposed. Simultaneously, optimizing the layout and position of optical elements enables effective collection and detection of near-field signals. This optimizes the coupling efficiency between the detector and the near-field signal, increasing signal strength, which is highly beneficial for studying the resonant characteristics of the sample itself. By superimposing tip scattering to induce two signals, the near-field signal obtained in the experiment becomes clearer and more reliable, providing a solid foundation for further data analysis and research.

[0060] In summary, by controlling the optical path difference and adjusting the optical path as described above, this invention enables the adjustment of the probe antenna resonance effect in experiments, which is beneficial for studying the resonance characteristics of the sample itself. This allows for more reliable and accurate measurement results.

[0061] This implementation is as follows Figure 1As shown, the second reflecting mirror 4 and the third reflecting mirror 5 can be moved left and right, and similarly, the fourth reflecting mirror 6 and the fifth reflecting mirror 7 can also move left and right, achieving precise control of the optical path difference. The laser generated by the terahertz transmitter through the optical guide antenna is split by a high-resistivity silicon (BS) mirror. The split laser beam reaches the parabolic mirror through different optical paths, and is focused onto the sample surface by the parabolic mirror, interacting with the sample. Near-field signals are generated at different time points. These signals are received by the optical guide antenna and connected to a current amplifier to be converted into electrical signals. Subsequently, a lock-in amplifier performs demodulation processing, finally extracting the pure near-field signal, achieving high-precision measurement and response of the sample. Since the first generated near-field signal includes tip scattering and coupled secondary scattering signals, two peak signals are observed in the time domain. However, through autocorrelation measurement, the near-field signal scattered by the laser with a longer optical path can be superimposed with the first generated near-field signal. This allows for the study of the resonant characteristics of the sample itself, obtaining high-quality measurement results.

[0062] The autocorrelation measurement method utilizes terahertz autocorrelation technology to sum the input signal with its own delayed signal. By adjusting the delay time, the autocorrelation signal of the terahertz wave can be obtained. In this invention, by controlling the length of the optical path and the time delay, the interaction between the near-field signal generated by the first laser beam and the near-field signal generated by the second laser beam (which has a longer optical path) is achieved. By superimposing these two signals, a measurement result with high signal-to-noise ratio and high resolution can be obtained. Through the above optimization and the application of the autocorrelation measurement method, this invention enables high-precision measurement and response of samples.

[0063] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the invention.

[0064] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A terahertz self-correlation near-field imaging spectrograph system, characterized in that, The system includes: Terahertz transmitter, optical path adjustment unit, scattering near-field scanning microscope, terahertz receiver, current amplifier, lock-in amplifier and processor; The terahertz transmitter is used to generate a first terahertz pulse signal; The optical path adjustment unit is used to split the first terahertz pulse signal into a second terahertz pulse signal and a third terahertz pulse signal, and to process the second terahertz pulse signal and irradiate it onto the sample to generate a first near-field signal, and to process the third terahertz pulse signal and irradiate it onto the sample to generate a second near-field signal, and to adjust the time delay difference between the first near-field signal and the second near-field signal. The terahertz receiver is used to receive the first near-field signal and the second near-field signal; The current amplifier is used to amplify the signal received by the terahertz receiver to obtain an amplified near-field signal, and the lock-in amplifier is used to demodulate the amplified near-field signal to obtain a demodulated signal. The processor is used to process the demodulated signal to obtain sample surface information, and to superimpose the demodulated signals corresponding to the first near-field signal and the second near-field signal, and to study the resonance effect of the sample itself based on the superposition result. Scattering near-field scanning microscopy is used to illuminate the sample surface with a terahertz pulse signal, and to acquire near-field imaging signals containing information about the sample surface using a probe, thereby imaging the sample surface based on the near-field imaging signals. 2.The terahertz self-correlation near-field imaging spectrograph system according to claim 1, characterized in that, The optical path adjustment unit includes: The system comprises a first lens, a second lens, and first to sixth reflectors; wherein, a terahertz transmitter generates a first terahertz pulse signal, which is split into a second terahertz pulse signal and a third terahertz pulse signal by the first lens. The second terahertz pulse signal is reflected sequentially by the first to third reflectors and then enters the second lens, and the third terahertz pulse signal is reflected sequentially by the fourth to sixth reflectors and then enters the second lens; wherein, the second and third reflectors are the first reflection modules, and the fourth and fifth reflectors are the second reflection modules, and the time delay difference between the first near-field signal and the second near-field signal is adjusted by laterally moving the first reflection module and / or the second reflection module. 3.The terahertz self-referencing near-field imaging spectrograph system of claim 1, wherein, The optical path adjustment unit further includes a first parabolic mirror and a second parabolic mirror. The first parabolic mirror is used to converge the signal emitted by the optical path adjustment unit onto the sample surface, and the second parabolic mirror is used to receive the near-field signal generated on the sample and then transmit it to the terahertz receiver.

4. The terahertz self-referencing near-field imaging spectrograph system according to claim 1, wherein, The terahertz transmitter includes a femtosecond laser and an optical guide antenna, wherein the femtosecond laser is used to generate a femtosecond laser to excite the optical guide antenna to generate a terahertz pulse signal.

5. The terahertz self-referencing near-field imaging spectrograph system according to claim 1, wherein, The optical path adjustment unit is also used to adjust the optical path difference between the first near-field signal and the second near-field signal to perform autocorrelation measurement on the terahertz pulse signal and obtain the time-domain information of the terahertz wave.

6. A terahertz autocorrelation near-field imaging spectroscopy system according to claim 4, characterized in that, An optical guide antenna consists of a photoconductive layer and an antenna structure.

7. The terahertz self-referencing near-field imaging spectrograph system according to claim 2, wherein, The first lens is a first high-resistivity silicon lens, and the second lens is a second high-resistivity silicon lens. 8.The terahertz self-referencing near-field imaging spectrograph system of claim 1, wherein, The probe tip of a scattering near-field scanning microscope has a subwavelength structure. 9.The terahertz self-referencing near-field imaging spectrograph system of claim 2, wherein, When the first reflective module moves, the second and third reflective mirrors move synchronously; when the second reflective module moves, the fourth and fifth reflective mirrors move synchronously.

10. The terahertz self-referencing near-field imaging spectrograph system according to claim 2, wherein, The first to sixth reflectors are silver-plated reflectors.

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