High-quality terahertz signal adjusting method

Abstract

The invention discloses a high-quality terahertz signal adjusting method. The method comprises the following steps: firstly, controlling a delay position of a delay line to move to a position where the amplitude of a terahertz signal is maximum by using control software, and displaying the amplitude of the signal; then, the three-dimensional precise moving platforms of the photoconductive excitation antenna, the terahertz lens I, the terahertz lens II and the photoconductive detection antenna are repeatedly and sequentially adjusted, so that the amplitude of the terahertz signal reaches the maximum; then sequentially moving a certain one-dimensional position of a three-dimensional precision platform of a photoconductive excitation antenna, a terahertz lens I, a terahertz lens II and a photoconductive detection antenna with a relatively small fixed value, recording, and collecting and storing terahertz spectrum data when moving a fixed value every time; comparing all the stored terahertz spectrum data to obtain the position of each three-dimensional precision platform when the terahertz spectrum range is widest; and moving the three-dimensional precision platform according to the recorded position and collecting a terahertz signal. The terahertz signals acquired through the steps have high signal quality.

Description

Technical Field

[0001] The present invention mainly relates to the technical field of free-space terahertz time-domain spectroscopy, and specifically designs a terahertz signal adjustment method with a wide spectrum range and a high dynamic range. Background Art

[0002] Terahertz time-domain spectroscopy is an emerging spectral detection technology. Compared with electromagnetic waves in other frequency bands, terahertz waves have unique properties such as fingerprint, penetration, safety, and transientness, which makes them have incomparable advantages in the field of spectral detection. Terahertz time-domain spectroscopy is of great value in studying the spectral characteristics of materials, analyzing the composition structure of materials, and characterizing the optical properties of materials. It has been widely used in many fields such as spectral analysis, safety detection, and biomedicine.

[0003] High-efficiency spectral analysis of materials depends on the terahertz time-domain spectroscopy system having a high terahertz signal dynamic range and a wide spectrum width. Currently, due to the development of terahertz photonic devices, it is difficult to obtain high-quality terahertz signals. In order to improve the quality of terahertz signals, the terahertz time-domain spectroscopy system built based on the existing photonic device module mainly adjusts the optical device to maximize the terahertz signal amplitude, that is, it is assumed that the terahertz signal quality is best at this time. Through repeated adjustments and material spectrum detection, it is found that when the terahertz signal amplitude is the largest, its spectrum range and dynamic range are not the maximum. Therefore, we cannot blindly pursue the maximum terahertz signal amplitude. We urgently need a terahertz signal adjustment method with a high dynamic range and a wide spectrum width. Summary of the invention

[0004] 1. Technical problem to be solved by the invention: The present invention provides a high-quality terahertz signal adjustment method to solve the problem of unsatisfactory terahertz spectrum width and dynamic range in the existing free-space terahertz time-domain spectroscopy system.

[0005] 2. Technical solution: To achieve the above object, the technical solution provided by the present invention is: a high-quality terahertz signal adjustment method, which uses a free-space terahertz time-domain spectroscopy system to collect terahertz signals, and controls the delay line delay position through system control software, adjusts the three-dimensional position of each component of the terahertz quasi-optical transmission module to obtain the maximum value of the terahertz signal, and combines the control variable method to find the optimal position of each component when generating high-quality terahertz signals in turn, so as to achieve high-quality terahertz signal collection; the method includes the following steps in sequence: S1, the control software controls the delay line to move the delay position to the point where the terahertz signal amplitude is maximum; S2, repeatedly adjusting the three-dimensional precision platform of the photoconductive excitation antenna, the terahertz lens 1, the terahertz lens 2, and the photoconductive detection antenna in sequence to maximize the amplitude of the terahertz signal; S3, based on the control variable method, the three-dimensional position of the photoconductive excitation antenna is moved in sequence by a small fixed value and recorded, and the terahertz spectrum data is collected and saved every time a fixed value is moved; S4, comparing all the saved terahertz spectrum data, finding the position of the three-dimensional precision platform of the photoconductive excitation antenna when the spectrum width is the widest and the dynamic range is the largest, and moving it; S5, based on the control variable method, sequentially move the terahertz lens by a fixed value in a three-dimensional position and record it, and collect and save terahertz spectrum data every time it moves a fixed value; S6, comparing all the saved terahertz spectrum data, finding the position of the terahertz lens-three-dimensional precision platform when the spectrum width is the widest and the dynamic range is the largest, and moving it; S7, based on the control variable method, sequentially move the two-dimensional and three-dimensional positions of the terahertz lens by a small fixed value and record them, and collect and save terahertz spectrum data every time a fixed value is moved; S8, comparing all the saved terahertz spectrum data, finding the position of the two-dimensional and three-dimensional precision platform of the terahertz lens when the spectrum width is the widest and the dynamic range is the largest, and moving it; S9, based on the control variable method, the three-dimensional position of the photoconductive detection antenna is moved in sequence by a small fixed value and recorded, and the terahertz spectrum data is collected and saved each time a fixed value is moved; S10, comparing all the saved terahertz spectrum data, finding the position of the three-dimensional precision platform of the photoconductive detection antenna when the spectrum width is the widest and the dynamic range is the largest, and moving it; S11. The control software collects the terahertz signal, and the obtained terahertz signal has good signal quality.

[0006] Preferably, the free-space terahertz time-domain spectroscopy system uses a photoconductive excitation antenna to generate terahertz waves, uses a photoconductive detection antenna to detect terahertz waves, uses control software to control the delay position movement of the delay line, uses control software to collect and display the terahertz frequency domain spectrum, and uses control software to display the terahertz signal amplitude in real time.

[0007] Preferably, the terahertz quasi-optical transmission module is composed of a photoconductive excitation antenna, a terahertz lens 1, a terahertz lens 2, a photoconductive detection antenna, and a three-dimensional precision platform for supporting the various components.

[0008] Preferably, the terahertz excitation antenna generates a terahertz wave which is incident on the terahertz lens 1 in parallel, is focused by the terahertz lens 1 and then incident on the terahertz lens 2, is expanded and collimated by the terahertz lens 2 and is transmitted to the photoconductive detection antenna.

[0009] Preferably, the terahertz lens 1 and the terahertz lens 2 have the same focal length and are confocal.

[0010] Preferably, the fixed value in step S7 is set to 0.05 mm.

[0011] 3. Beneficial effects: Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects: The present invention uses the control variable method to gradually move the three-dimensional position of each component with a fixed value and record the spectrum data. This delicate operation can find the best position with the widest spectrum width and the largest dynamic range, significantly improving the quality of terahertz signals. Compared with the rough setting of component positions in traditional methods, this precise adjustment can better tap the potential of the system and reduce problems such as signal distortion and attenuation.

[0012] The present invention not only adjusts a single component, but optimizes multiple key components in the terahertz quasi-optical transmission module in sequence, taking into account the impact of the interaction between the components on the terahertz signal transmission, so that the entire signal transmission link reaches the optimal state, and finally realizes high-quality signal acquisition.

[0013] The present invention strictly follows the control variable method when adjusting the position of each component, and only changes the position of one component at a time while keeping the other components unchanged. This scientific experimental method ensures the repeatability and reliability of the results. Different operators can obtain similar high-quality terahertz signals by following the same steps, which is conducive to the verification of experimental results and further research.

[0014] The present invention operates the whole process through the control software of the free space terahertz time domain spectroscopy system, and realizes automation and digitization from the control of the delay line delay position to the collection and storage of spectrum data. This not only improves the convenience of operation, but also ensures the accuracy and integrity of data recording, and facilitates the subsequent analysis and processing of experimental data.

[0015] The present invention can be applied to a variety of scenarios that require high-quality terahertz signals, such as terahertz imaging, terahertz spectroscopy analysis, etc. By obtaining high-quality signals, key performance indicators such as resolution and sensitivity in these applications can be improved, and the adaptability and practicality of the system in different fields can be enhanced. The operator can adjust the parameters such as the scanning start position, end position, step length, and scanning speed within a certain range according to specific experimental requirements and system configuration, so that the method has a certain flexibility and can better adapt to different terahertz time-domain spectroscopy systems and experimental conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a flow chart of the method of the present invention; Figure 2 is a schematic diagram of a terahertz quasi-optical transmission module; Figure 3 This is a schematic diagram of the control software interface of the terahertz time-domain spectroscopy system. DETAILED DESCRIPTION

[0017] To facilitate understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. Several embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0018] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "page", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicating orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0019] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0020] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed", "provided with", etc. should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be internal communication between two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0021] It should be noted that the structures not introduced in the present invention are the same as the prior art or can be implemented by using the prior art, and are not described in detail here because they do not involve the design points and improvement directions of the present invention. Example

[0022] See attached Figures 1 to 3A high-quality terahertz signal adjustment method is proposed. A free-space terahertz time-domain spectroscopy system is used to collect terahertz signals. The delay line delay position is controlled by the system control software. The three-dimensional position of each component of the terahertz quasi-optical transmission module is adjusted to obtain the maximum value of the terahertz signal. The optimal position of each component when generating high-quality terahertz signals is found in turn by combining the control variable method, thereby realizing high-quality terahertz signal acquisition.

[0023] The terahertz quasi-optical transmission module consists of a photoconductive excitation antenna, a terahertz lens 1, a terahertz lens 2, a photoconductive detection antenna, and a three-dimensional precision platform that supports each component. The terahertz excitation antenna generates a terahertz wave that is incident on the terahertz lens 1 in parallel, and then is focused by the terahertz lens 1 and incident on the terahertz lens 2. The terahertz wave is expanded and collimated by the terahertz lens 2 and transmitted to the photoconductive detection antenna. The terahertz lens 1 and the terahertz lens 2 have the same focal length and are confocal.

[0024] The free-space terahertz time-domain spectroscopy system uses a photoconductive excitation antenna to generate terahertz waves, a photoconductive detection antenna to detect terahertz waves, a control software to control the delay position movement of the delay line, a control software to collect and display the terahertz frequency domain spectrum, and a control software to display the terahertz signal amplitude in real time.

[0025] The following steps are included in sequence: S1. Open the terahertz time-domain spectroscopy system control software, select the correct phase-locked amplifier and translation stage communication serial port, set the appropriate scanning start position, end position, step length and scanning speed, and click the acquisition button to start collecting terahertz signals. After the acquisition is completed, click the Move to Peak button to control the delay line to move to the maximum amplitude of the terahertz signal; it can quickly find the delay line position with a large signal amplitude, providing a better initial state for further optimization of signal quality. This helps to reduce the workload of subsequent adjustments and improve the overall adjustment efficiency.

[0026] S2. Repeatedly adjust the three-dimensional precision platform of the photoconductive excitation antenna, terahertz lens 1, terahertz lens 2, and photoconductive detection antenna in sequence to maximize the terahertz signal amplitude. Through repeated adjustments, a relatively good positional relationship between the components can be found, effectively improving the signal strength and laying the foundation for subsequent more precise adjustments. This method of combining manual adjustment with subsequent control variable method adjustment, while ensuring a certain adjustment accuracy, also avoids the blindness that may be caused by complex and fine adjustments at the beginning. Repeatedly adjust the three-dimensional precision platform of the photoconductive excitation antenna, terahertz lens 1, terahertz lens 2, and photoconductive detection antenna to maximize the terahertz signal amplitude. By adjusting the positions of these key components, the optical path of the terahertz signal during transmission is optimized, signal loss is reduced, and signal strength is enhanced.

[0027] S3. Based on the control variable method, the three-dimensional position of the photoconductive excitation antenna is moved in sequence by a fixed value of 0.05 mm and recorded. After each movement of 0.05 mm, the terahertz spectrum data is collected and the frequency domain data save button is clicked. This step is to explore the influence of the photoconductive excitation antenna on the terahertz spectrum characteristics at different three-dimensional positions, and to provide a basis for finding the best position through detailed data collection.

[0028] S4. Compare all the saved terahertz spectrum data, find and move the three-dimensional precision platform position of the photoconductive excitation antenna when the spectrum width is the widest and the dynamic range is the largest; this step determines the optimal position of the photoconductive excitation antenna, so that the terahertz signal has the best spectrum characteristics at the position of the photoconductive excitation antenna.

[0029] S5. Based on the control variable method, the three-dimensional position of the terahertz lens is moved by 0.05 mm in sequence and recorded. Every time it moves 0.05 mm, terahertz spectrum data is collected and the frequency domain data save button is clicked. This step is to explore the impact of the position change of the terahertz lens on the terahertz spectrum and to prepare for determining its optimal position.

[0030] S6. Compare all the saved terahertz spectrum data, find the position of the three-dimensional precision platform of the terahertz lens 1 when the spectrum width is the widest and the dynamic range is the largest, and move it; this step determines the optimal position of the terahertz lens 1, so that the terahertz signal has the best spectrum characteristics at the position of the terahertz lens 1.

[0031] S7, based on the control variable method, move the two-dimensional and three-dimensional positions of the terahertz lens by 0.05 mm in sequence and record them, collect terahertz spectrum data every 0.05 mm movement and click the frequency domain data save button; S8. Compare all the saved terahertz spectrum data, find the position of the two-dimensional precision platform of the terahertz lens when the spectrum width is the widest and the dynamic range is the largest, and click the frequency domain data save button; Steps S7-S8 are to determine the optimal position of the terahertz lens two.

[0032] S9, based on the control variable method, the three-dimensional position of the photoconductive detection antenna is moved in sequence by 0.05 mm and recorded, and the terahertz spectrum data is collected every 0.05 mm movement and the frequency domain data save button is clicked; S10, compare all the saved terahertz spectrum data, find and move the three-dimensional precision platform position of the photoconductive detection antenna when the spectrum width is the widest and the dynamic range is the largest; steps S9-S10 are to determine the best three-dimensional position of the photoconductive detection antenna to optimize the quality of the detected terahertz signal.

[0033] S11. Click the acquisition button on the control software interface to collect the terahertz signal. The terahertz signal obtained at this time has a high signal quality. Finally, click the acquisition button on the control software interface to collect the terahertz signal. At this time, since the optimal positions of the key components (photoconductive excitation antenna, terahertz lens 1, terahertz lens 2, photoconductive detection antenna) have been determined before, the collected terahertz signal has a high signal quality.

[0034] The above-described embodiments only express a certain implementation mode of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the patent scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.

Claims

1. A high-quality terahertz signal adjustment method, characterized in that: A free-space terahertz time-domain spectroscopy system is used to collect terahertz signals, and the delay line delay position is controlled by the system control software, and the three-dimensional position of each component of the terahertz quasi-optical transmission module is adjusted to obtain the maximum value of the terahertz signal. The optimal position of each component when generating high-quality terahertz signals is found in turn by combining the control variable method, so as to realize high-quality terahertz signal collection; the following steps are included in sequence: S1, the control software controls the delay line to move the delay position to the point where the terahertz signal amplitude is maximum; S2, repeatedly adjusting the three-dimensional precision platform of the photoconductive excitation antenna, the terahertz lens 1, the terahertz lens 2, and the photoconductive detection antenna in sequence to maximize the amplitude of the terahertz signal; S3, based on the control variable method, the three-dimensional position of the photoconductive excitation antenna is moved in sequence by a small fixed value and recorded, and the terahertz spectrum data is collected and saved every time a fixed value is moved; S4, comparing all the saved terahertz spectrum data, finding the position of the three-dimensional precision platform of the photoconductive excitation antenna when the spectrum width is the widest and the dynamic range is the largest, and moving it; S5, based on the control variable method, sequentially move the terahertz lens by a fixed value in a three-dimensional position and record it, and collect and save terahertz spectrum data every time it moves a fixed value; S6, comparing all the saved terahertz spectrum data, finding the position of the terahertz lens-three-dimensional precision platform when the spectrum width is the widest and the dynamic range is the largest, and moving it; S7, based on the control variable method, sequentially move the two-dimensional and three-dimensional positions of the terahertz lens by a small fixed value and record them, and collect and save terahertz spectrum data every time a fixed value is moved; S8, comparing all the saved terahertz spectrum data, finding the position of the two-dimensional and three-dimensional precision platform of the terahertz lens when the spectrum width is the widest and the dynamic range is the largest, and moving it; S9, based on the control variable method, the three-dimensional position of the photoconductive detection antenna is moved in sequence by a small fixed value and recorded, and the terahertz spectrum data is collected and saved each time a fixed value is moved; S10, comparing all the saved terahertz spectrum data, finding the position of the three-dimensional precision platform of the photoconductive detection antenna when the spectrum width is the widest and the dynamic range is the largest, and moving it; S11. The control software collects the terahertz signal, and the obtained terahertz signal has good signal quality.

2. The adjustment method according to claim 1, characterized in that: The free-space terahertz time-domain spectroscopy system uses a photoconductive excitation antenna to generate terahertz waves, a photoconductive detection antenna to detect terahertz waves, a control software to control the delay position movement of the delay line, a control software to collect and display the terahertz frequency domain spectrum, and a control software to display the terahertz signal amplitude in real time.

3. The adjustment method according to claim 1, characterized in that: The terahertz quasi-optical transmission module consists of a photoconductive excitation antenna, a terahertz lens 1, a terahertz lens 2, a photoconductive detection antenna, and a three-dimensional precision platform that supports each component.

4. The adjustment method according to claim 1, characterized in that: The terahertz wave generated by the terahertz excitation antenna is incident on the terahertz lens 1 in parallel, and after being focused by the terahertz lens 1, it is incident on the terahertz lens 2, and is expanded and collimated by the terahertz lens 2 and transmitted to the photoconductive detection antenna.

5. The adjustment method according to claim 1, characterized in that: The terahertz lens 1 and the terahertz lens 2 have the same focal length and are confocal.

6. The adjustment method according to claim 1, characterized in that: The fixed value in step S7 is set to 0.05 mm.

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