Device and method for automatically adjusting sample position in terahertz three-dimensional tomography system

Abstract

The invention discloses a sample position automatic adjustment device for a terahertz three-dimensional tomography system and a method thereof. The device comprises an emission optical path unit, a detection optical path unit, a visible laser rangefinder, and a lifting and translation stage. The fixed end of the emission optical path unit and the fixed end of the detection optical path unit are both rotatably connected to a rotating shaft. The visible laser rangefinder is fixed on the angular bisector of the angle formed by the optical axis of the emission optical path unit and the optical axis of the detection optical path unit. The laser emitted by the visible laser rangefinder and the optical axis of the emission optical path unit and the optical axis of the detection optical path unit are on the same plane. The sample is fixed on the upper surface of the lifting and translation stage. The lifting and translation stage is moved left and right or forward and backward so that the laser spot emitted by the visible laser rangefinder falls on the surface of the sample to be measured. The visible laser rangefinder can detect the distance from the visible laser rangefinder to the upper surface of the sample. The lifting and translation stage is adjusted based on the distance detected by the visible laser rangefinder so that the sample is placed at an optimal sample placement point to achieve imaging with a maximum signal-to-noise ratio.

Description

Technical field:

[0001] The invention belongs to the field of terahertz time-domain spectroscopy systems, and in particular relates to a sample position automatic adjustment device for a terahertz three-dimensional tomography system. Background technology:

[0002] Terahertz time-domain spectroscopy imaging measurement technology is a hot research field that has emerged in the past decade. Typical terahertz waves refer to electromagnetic waves with frequencies between 0.1-10THz (corresponding to wavelengths of 30μm-3mm), which is a section of the electromagnetic spectrum between microwaves and infrared rays. Since the weak forces between / within non-polar macromolecules (hydrogen bonds, van der Waals forces), skeleton vibrations and dipole rotations are just within the THz spectrum range, and the terahertz pulse signal has good time resolution, terahertz time-domain spectroscopy technology and terahertz three-dimensional tomography technology have been rapidly applied in many fields in recent years. Based on the technical advantages of terahertz time-domain spectroscopy technology, fast terahertz time-domain spectroscopy detection technology can quickly measure the spectral characteristic information and material penetration information of the material to be tested. It has a wide range of applications in the fields of semiconductor materials, ultra-high temperature superconducting materials, tomography imaging technology, genetic testing, chemical and biological testing, broadband communications, etc. It is an effective measurement method for material thickness detection, material composition analysis, material layering information measurement, terahertz three-dimensional tomography, etc.

[0003] The terahertz time-domain spectroscopy system based on photoconductive antenna is the most effective terahertz spectral imaging product at present. Its basic principle is: the fiber femtosecond laser emits two beams of femtosecond laser, one of which is used as pump light and transmitted to the photoconductive transmitting antenna through the optical fiber, and generates broadband terahertz waves under the action of bias voltage. The terahertz waves carry the three-dimensional tomography signal of the test sample into the terahertz detection antenna by reflection; the detection light passes through the fast optical delay line, and the terahertz spectrum information carrying the sample information is used for three-dimensional tomography of the sample through spectral analysis technology.

[0004] The output spectrum frequency of the terahertz time-domain spectroscopy system is 0.1-4THz, and the output spectrum is in a band that cannot be directly observed by the human eye. During the reflection imaging of the sample to be tested, the beam waist position of the terahertz wave has the highest imaging signal-to-noise ratio. Since the position of the terahertz wave focused light spot cannot be observed intuitively, during the imaging of irregular samples, the spatial position of the material to be tested needs to be manually adjusted every time the sample position is changed, which not only wastes a lot of manpower and material resources but also increases the existence of accidental errors in the test process. Summary of the invention:

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and seek to design a device for automatically adjusting the sample position of a terahertz three-dimensional tomography system. The device uses the visible light in the laser rangefinder to indicate the defect that the terahertz light spot cannot be effectively focused on the sample surface when the terahertz time-domain spectroscopy system measures irregular objects. The device can realize automatic height adjustment of the object to be measured through an automatic control system. The device adjusts the position of the sample to be measured in real time online through the real-time position information feedback of the laser rangefinder, thereby ensuring the signal-to-noise ratio of the terahertz three-dimensional tomography system and realizing optimized imaging.

[0006] In order to achieve the above-mentioned purpose, the present invention relates to a terahertz three-dimensional tomography system sample position automatic adjustment device, comprising an emission light path unit, a detection light path unit, a visible laser rangefinder, and a lifting and translation stage; the fixed end of the emission light path unit and the fixed end of the detection light path unit are both rotatably connected to a rotating shaft, the visible laser rangefinder is fixed on the angular bisector of the angle formed by the optical axis of the emission light path unit and the optical axis of the detection light path unit, and the laser emitted by the visible laser rangefinder is on the same plane as the optical axis of the emission light path unit and the optical axis of the detection light path unit (referred to as plane A), and the laser emitted by the visible laser rangefinder, the emission light path unit, and the detection light path unit are on the same plane as the optical axis of the emission light path unit. The unit optical axis and the detection optical path unit optical axis intersect at one point, and the intersection is the optimal placement point of the sample. The upper surface of the lifting and translation stage is perpendicular to the plane, and the laser emitted by the visible laser rangefinder is also perpendicular to the upper surface of the lifting and translation stage. The sample is fixed on the upper surface of the lifting and translation stage, and the lifting and translation stage is moved left and right or forward and backward so that the laser spot emitted by the visible laser rangefinder falls on the surface of the sample to be measured. The visible laser rangefinder can detect the distance from the visible laser rangefinder to the upper surface of the sample. The lifting and translation stage is adjusted based on the distance detected by the visible laser rangefinder to place the sample at the optimal sample placement point to achieve imaging with a maximum signal-to-noise ratio.

[0007] Specifically, the terahertz three-dimensional tomography system sample position automatic adjustment device involved in the present invention also includes a real-time feedback system, and the real-time feedback system is respectively connected to the visible light laser rangefinder and the lifting and translation stage.

[0008] The invention relates to a terahertz three-dimensional tomography system sample position automatic adjustment device, which also includes an arc ruler, which is arranged parallel to the plane and the center of the arc ruler is fixed on the rotating shaft.

[0009] Preferably, the scales on the arc scale are symmetrically arranged, gradually increasing from 0 on both sides of the symmetry axis of the arc scale, and the emission optical path unit and the detection optical path unit are symmetrically arranged about the symmetry axis of the arc scale.

[0010] Furthermore, a screw is fixedly arranged along the angle bisector, one end of the screw is rotatably connected to the stepper motor, a slider is threadedly connected to the screw, one end of the connecting rod of the emitting optical path unit is rotatably connected to the movable end of the emitting optical path unit, one end of the connecting rod of the detection optical path unit is rotatably connected to the movable end of the detection optical path unit, and the other end of the connecting rod of the emitting optical path unit and the other end of the connecting rod of the detection optical path unit are hinged on the slider to form a parallelogram.

[0011] The transmitting optical path unit comprises a terahertz transmitting antenna, a first collimating lens, a first focusing lens and a rotating rod of the transmitting optical path unit. The terahertz transmitting antenna, the first collimating lens and the first focusing lens are integrated in a lens barrel. The lens barrel composed of the transmitting optical path unit is fixed on the rotating rod of the transmitting optical path unit. The fixed end of the rotating rod of the transmitting optical path unit is rotatably connected to the rotating shaft. The connecting rod of the transmitting optical path unit is rotatably connected to the movable end of the rotating rod of the transmitting optical path unit. The movable end of the rotating rod of the transmitting optical path unit is in the shape of a pointer. The rotating rod of the transmitting optical path unit is arranged close to the arc ruler and can directly indicate the scale on the arc ruler to obtain the angle between the transmitting optical path unit and the angle bisector. The detection optical path unit comprises a second focusing lens, a second collimating lens, a terahertz detection antenna and a rotating rod of the detection optical path unit. The second focusing lens, the second collimating lens and the terahertz detection antenna are integrated in a lens barrel. The lens barrel integrated with the detection optical path unit is fixed on the rotating rod of the detection optical path unit. The fixed end of the rotating rod of the detection optical path unit is rotatably connected to the rotating shaft. The connecting rod of the detection optical path unit is rotatably connected to the movable end of the rotating rod of the detection optical path unit. The movable end of the rotating rod of the detection optical path unit is in the shape of a pointer. The rotating rod of the detection optical path unit is arranged close to the circular arc scale, and can directly indicate the scale on the circular arc scale to obtain the size of the angle between the detection optical path unit and the angle bisector.

[0012] Preferably, in order not to interfere with other structures, the visible laser rangefinder is fixed on the screw between the stepper motor and the slider.

[0013] Specifically, the visible laser rangefinder is fixed to the upper part of the adjustment frame through a two-axis adjustment frame, the adjustment frame is fixed on the screw rod, the two-axis adjustment frame is used to adjust the pitch and yaw, and the adjustment frame is an existing lifting rod.

[0014] The present invention relates to a method for automatically adjusting the position of a sample in a terahertz three-dimensional tomography system, comprising the following steps:

[0015] (1) Adjust the adjustment frame and the two-axis adjustment frame so that the laser emitted by the visible laser rangefinder intersects the optical axis of the transmitting optical path unit and the optical axis of the detecting optical path unit at one point;

[0016] (2) Place the sample on the upper surface of the lifting and translation stage, start the visible laser rangefinder, move the lifting and translation stage forward, backward, left and right according to the position of the light spot, so that the light spot falls on the sample to be measured, and then the visible laser rangefinder measures the distance d between it and the upper surface of the sample, and sends the value to the real-time feedback system;

[0017] (3) If d>d2, move the lifting and translation stage 9 upwards; if d<d2, move the lifting and translation stage downwards until d=d2, and the adjustment is completed. d is the distance between the visible laser rangefinder 8 and the upper surface of the sample, and d2 is the distance between the visible laser rangefinder and the optimal sample placement point, which are known quantities.

[0018] A laser rangefinder is an instrument that uses the time delay of a pulsed laser to accurately measure the distance to a target. A visible light laser rangefinder not only has the advantages of accurate distance measurement, small focused spot size, and high monochromaticity, but also has high brightness and can be easily observed by the human eye. The adjustment of this device can effectively indicate the focused spot position of the terahertz signal. Combining the angle information of the terahertz reflection signal with the distance information of the laser rangefinder can effectively realize the automatic adjustment of the placement position of the sample to be measured, and finally adjust the imaging position of the sample to be measured to the spot focusing position of the terahertz time-domain spectroscopy system, so that the system can image the sample with a high signal-to-noise ratio.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. By fixing the fixed ends of the emission optical path unit and the detection optical path unit, the focal positions of the emission optical path and the detection optical path are guaranteed to remain unchanged, which provides a theoretical basis for distance measurement, realizes automatic adjustment of the sample position, facilitates operators to test the samples, reduces the probability of random errors in test data caused by improper human operation, and improves test accuracy;

[0021] 2. First, a four-link structure including an emission optical path unit, a detection optical path unit, an emission optical path unit connecting rod, and a detection optical path unit connecting rod was constructed. Driven by a stepper motor, the axial symmetric adjustment of the emission optical path unit and the detection optical path unit was achieved. Description of the drawings:

[0022] Figure 1 The present invention is a stereoscopic diagram of a sample position automatic adjustment device for a terahertz three-dimensional tomography system.

[0023] Figure 2 The present invention is a schematic diagram of the structure of a sample position automatic adjustment device for a terahertz three-dimensional tomography system (including a real-time feedback system).

[0024] Figure 3 The present invention is a plan view of a sample position automatic adjustment device for a terahertz three-dimensional tomography system. Specific implementation method:

[0025] The present invention will be further described below through specific embodiments in conjunction with the accompanying drawings.

[0026] Embodiment 1:

[0027] The present embodiment relates to a terahertz three-dimensional tomography system sample position automatic adjustment device, comprising an emitting optical path unit 2, a detecting optical path unit 3, a visible laser rangefinder 8, and a lifting and translation stage 9; the fixed end of the emitting optical path unit 2 and the fixed end of the detecting optical path unit 3 are both rotatably connected to a rotating shaft 13, the visible laser rangefinder 8 is fixed on the angular bisector of the angle formed by the optical axis of the emitting optical path unit 2 and the optical axis of the detecting optical path unit 3, and the laser emitted by the visible laser rangefinder 8 and the optical axis of the emitting optical path unit 2 and the optical axis of the detecting optical path unit 3 are on the same plane (referred to as plane A), that is, the laser emitted by the visible laser rangefinder 8 and the optical axis of the emitting optical path unit 2 are on the same plane (referred to as plane A). The axis and the optical axis of the detection optical path unit 3 intersect at one point, and the intersection is the optimal placement point of the sample. The upper surface of the lifting and translation stage 9 is perpendicular to the plane (plane A). At the same time, the laser emitted by the visible laser rangefinder 8 is also perpendicular to the upper surface of the lifting and translation stage 9. The sample is fixed on the upper surface of the lifting and translation stage 9. The lifting and translation stage 9 is moved left and right or forward and backward so that the laser spot emitted by the visible laser rangefinder 8 falls on the surface of the sample to be measured. The visible laser rangefinder 8 can detect the distance from the visible laser rangefinder 8 to the upper surface of the sample. The lifting and translation stage 9 is adjusted based on the distance detected by the visible laser rangefinder 8 to place the sample at the optimal sample placement point to achieve imaging with a maximum signal-to-noise ratio.

[0028] Specifically, the distance between the visible laser rangefinder 8 and the upper surface of the sample is d, which is directly measured by the visible laser rangefinder 8, and d=d1+d2, d2 is the distance between the visible laser rangefinder 8 and the optimal sample placement point (intersection point), which is a known quantity, and d1 is the distance between the upper surface of the sample and the optimal sample placement point (intersection point), that is, the displacement of the lifting and translation stage 9.

[0029] Specifically, the terahertz three-dimensional tomography system sample position automatic adjustment device involved in this embodiment also includes a real-time feedback system 14, which is connected to the visible light laser rangefinder 8 and the lifting and translation stage 9 respectively, and reads the distance d sent by the visible light laser rangefinder 8 in real time. If d>d2, the lifting and translation stage 9 is controlled to move upward, and if d<d2, the lifting and translation stage 9 is controlled to move downward until d=d2. The lifting and translation stage is an existing electric lifting and translation stage, which can accurately and automatically control the displacement of lifting and lowering, and can also move in the front, back, left and right directions.

[0030] During use, the angle between the emission optical path unit 2 and the detection optical path unit 3 needs to be continuously adjusted according to actual conditions. In order to facilitate the adjustment of the angle and accurately read the angle, the automatic adjustment device for the sample position of a terahertz three-dimensional tomography system involved in this embodiment also includes an arc ruler 10, which is arranged parallel to the plane A, and the center of the arc ruler 10 is fixed on the rotating shaft 13. The movable ends of the emission optical path unit 2 and the detection optical path unit 3 are rotated to adjust the angle between the emission optical path unit 2 and the detection optical path unit 3, and the angle of the angle is determined in real time through the scale on the arc ruler 10.

[0031] Preferably, the scales on the arc scale 10 are symmetrically arranged, gradually increasing from 0 on both sides of the symmetry axis of the arc scale, and the emission optical path unit 2 and the detection optical path unit 3 are symmetrically arranged about the symmetry axis of the arc scale, so as to facilitate the synchronous movement of the emission optical path unit 2 and the detection optical path unit 3.

[0032] Furthermore, in order to ensure that during the angle adjustment process, the visible laser rangefinder 8 is always fixed on the angular bisector of the angle formed by the optical axis of the emitting optical path unit 2 and the optical axis of the detection optical path unit 3, a screw 12 is fixedly arranged along the angular bisector, one end of the screw 12 is rotatably connected to the stepper motor 1, a slider 11 is threadedly connected to the screw 12, one end of the emitting optical path unit connecting rod 4 is rotatably connected to the moving end of the emitting optical path unit 2, one end of the detection optical path unit connecting rod 6 is rotatably connected to the moving end of the detection optical path unit 2, the other end of the emitting optical path unit connecting rod 4 and the other end of the detection optical path unit connecting rod 6 are hinged on the slider 11, the emitting optical path unit 2 and the detection optical path unit 3 are of equal length, and the lengths of the emitting optical path unit connecting rod and the detection optical path unit connecting rod are equal. The stepper motor 1 drives the screw 12 to rotate, and then synchronously adjusts the angle between the optical axis of the emitting optical path unit 2 and the angular bisector, and between the optical axis of the detection optical path unit 3 and the angular bisector through the emitting optical path unit connecting rod 4 and the detection optical path unit connecting rod 6, so that the angle between the optical axis of the emitting optical path unit 2 and the optical axis of the detection optical path unit 3 rotates within a range of 0-180°.

[0033] The transmitting optical path unit 2 includes a terahertz transmitting antenna, a first collimating lens, a first focusing lens and a transmitting optical path unit rotating rod 5. The terahertz transmitting antenna, the first collimating lens and the first focusing lens are integrated in a lens barrel. The lens barrel composed of the transmitting optical path unit 2 is fixed on the transmitting optical path unit rotating rod 5. The fixed end of the transmitting optical path unit rotating rod 5 is rotatably connected to the rotating shaft 13. The transmitting optical path unit connecting rod 4 is rotatably connected to the movable end of the transmitting optical path unit rotating rod 5. The movable end of the transmitting optical path unit rotating rod 5 is in the shape of a pointer. The transmitting optical path unit rotating rod 5 is arranged close to the circular arc scale 10, and can directly indicate the scale on the circular arc scale 10 to obtain the angle between the transmitting optical path unit 2 and the angle bisector. Similarly, the detection optical path unit 3 includes a second focusing lens, a second collimating lens, a terahertz detection antenna and a detection optical path unit rotating rod 7. The second focusing lens, the second collimating lens and the terahertz detection antenna are integrated in a lens barrel. The lens barrel integrated with the detection optical path unit is fixed on the detection optical path unit rotating rod 7. The fixed end of the detection optical path unit rotating rod 7 is rotatably connected to the rotating shaft 13. The detection optical path unit connecting rod 6 is rotatably connected to the movable end of the detection optical path unit rotating rod 7. The movable end of the detection optical path unit rotating rod 7 is in the shape of a pointer. The detection optical path unit rotating rod 7 is arranged close to the arc scale 10, and can directly indicate the scale on the arc scale 10 to obtain the angle between the detection optical path unit 3 and the angle bisector. The integrated arrangement facilitates the synchronous adjustment of the height of each optical element of the emission optical path unit 2 or the detection optical path unit 3.

[0034] Preferably, in order not to interfere with other structures, the visible laser rangefinder 8 is fixed on the screw 12 between the stepping motor 1 and the slider 11. Specifically, the visible laser rangefinder 8 is fixed to the upper part of the adjustment frame 13 through a two-axis adjustment frame, and the adjustment frame 13 is fixed on the screw 12. The two-axis adjustment frame is used to adjust the pitch and yaw. The adjustment frame 13 is specifically an existing lifting rod to achieve height adjustment.

[0035] The present embodiment relates to a method for automatically adjusting the position of a sample in a terahertz three-dimensional tomography system, which specifically includes the following steps:

[0036] (1) Adjust the adjustment frame 13 and the two-axis adjustment frame so that the laser emitted by the visible laser rangefinder 8 intersects the optical axis of the emitting optical path unit 2 and the optical axis of the detecting optical path unit 3 at one point;

[0037] (2) placing the sample on the upper surface of the lifting and translation stage 9, starting the visible laser rangefinder 8, moving the lifting and translation stage forward, backward, left and right according to the position of the light spot, so that the light spot falls on the sample to be measured, and then the visible laser rangefinder 8 measures the distance d between it and the upper surface of the sample, and sends the value to the real-time feedback system 14;

[0038] (3) If d>d2, move the lifting and translation stage 9 upwards; if d<d2, move the lifting and translation stage 9 downwards until d=d2, and the adjustment is completed.

Claims

1. A sample position automatic adjustment device for a terahertz three-dimensional tomography system, characterized in that: It includes an emitting optical path unit, a detecting optical path unit, a visible laser rangefinder, and a lifting and translation stage; the fixed end of the emitting optical path unit and the fixed end of the detecting optical path unit are both rotatably connected to the rotating shaft, the visible laser rangefinder is fixed on the angular bisector of the angle formed by the optical axis of the emitting optical path unit and the optical axis of the detecting optical path unit, and the laser emitted by the visible laser rangefinder is on the same plane as the optical axis of the emitting optical path unit and the optical axis of the detecting optical path unit, and the laser emitted by the visible laser rangefinder, the optical axis of the emitting optical path unit and the optical axis of the detecting optical path unit intersect at one point, which is the sample The best placement point for the sample is determined, the upper surface of the lifting and translation stage is perpendicular to the plane, and the laser emitted by the visible laser rangefinder is also perpendicular to the upper surface of the lifting and translation stage. The sample is fixed on the upper surface of the lifting and translation stage, and the lifting and translation stage is moved left and right or front and back to make the laser spot emitted by the visible laser rangefinder fall on the surface of the sample to be measured. The visible laser rangefinder can detect the distance from the visible laser rangefinder to the upper surface of the sample. Based on the distance detected by the visible laser rangefinder, the lifting and translation stage is adjusted to place the sample at the best sample placement point to achieve imaging with maximum signal-to-noise ratio.

2. The automatic sample position adjustment device for a terahertz three-dimensional tomography system according to claim 1, characterized in that: The sample position automatic adjustment device of the terahertz three-dimensional tomography system also includes a real-time feedback system, which is respectively connected to the visible light laser rangefinder and the lifting and translation stage.

3. The automatic sample position adjustment device for a terahertz three-dimensional tomography system according to claim 2, characterized in that: The automatic sample position adjustment device of the terahertz three-dimensional tomography system also includes an arc ruler, which is arranged parallel to the plane and the center of the arc ruler is fixed on the rotating shaft.

4. The automatic sample position adjustment device for a terahertz three-dimensional tomography system according to claim 3, characterized in that: The scales on the arc scale are symmetrically arranged, and gradually increase from 0 to both sides of the symmetry axis of the arc scale. The emission optical path unit and the detection optical path unit are symmetrically arranged about the symmetry axis of the arc scale.

5. The automatic sample position adjustment device for a terahertz three-dimensional tomography system according to claim 4, characterized in that: A screw is fixedly arranged along the angle bisector, one end of the screw is rotatably connected to the stepping motor, a slider is threadedly connected to the screw, one end of the connecting rod of the emitting optical path unit is rotatably connected to the movable end of the emitting optical path unit, one end of the connecting rod of the detection optical path unit is rotatably connected to the movable end of the detection optical path unit, and the other end of the connecting rod of the emitting optical path unit and the other end of the connecting rod of the detection optical path unit are hinged on the slider to form a parallelogram.

6. The automatic sample position adjustment device for a terahertz three-dimensional tomography system according to claim 5, characterized in that: The transmitting optical path unit comprises a terahertz transmitting antenna, a first collimating lens, a first focusing lens and a rotating rod of the transmitting optical path unit. The terahertz transmitting antenna, the first collimating lens and the first focusing lens are integrated in a lens barrel. The lens barrel composed of the transmitting optical path unit is fixed on the rotating rod of the transmitting optical path unit. The fixed end of the rotating rod of the transmitting optical path unit is rotatably connected to the rotating shaft. The connecting rod of the transmitting optical path unit is rotatably connected to the movable end of the rotating rod of the transmitting optical path unit. The movable end of the rotating rod of the transmitting optical path unit is in the shape of a pointer. The rotating rod of the transmitting optical path unit is arranged close to the arc scale and can directly indicate the scale on the arc scale to obtain the angle between the transmitting optical path unit and the angle bisector. The detection optical path unit comprises a second focusing lens, a second collimating lens, a terahertz detection antenna and a rotating rod of the detection optical path unit. The second focusing lens, the second collimating lens and the terahertz detection antenna are integrated in a lens barrel. The lens barrel integrated with the detection optical path unit is fixed on the rotating rod of the detection optical path unit. The fixed end of the rotating rod of the detection optical path unit is rotatably connected to the rotating shaft. The connecting rod of the detection optical path unit is rotatably connected to the movable end of the rotating rod of the detection optical path unit. The movable end of the rotating rod of the detection optical path unit is in the shape of a pointer. The rotating rod of the detection optical path unit is arranged close to the circular arc scale, and can directly indicate the scale on the circular arc scale to obtain the size of the angle between the detection optical path unit and the angle bisector.

7. The automatic sample position adjustment device for a terahertz three-dimensional tomography system according to claim 6, characterized in that: It can be seen that the laser rangefinder is fixed on the screw between the stepper motor and the slider.

8. The automatic sample position adjustment device for a terahertz three-dimensional tomography system according to claim 7, characterized in that: The visible laser rangefinder is fixed on the upper part of the adjusting frame through a two-axis adjusting frame, the adjusting frame is fixed on the screw rod, the two-axis adjusting frame is used to adjust the pitch and yaw, and the adjusting frame is an existing lifting rod.

9. A method for adjusting the sample position automatic adjustment device of a terahertz three-dimensional tomography system according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) Adjust the adjustment frame and the two-axis adjustment frame so that the laser emitted by the visible laser rangefinder intersects the optical axis of the transmitting optical path unit and the optical axis of the detecting optical path unit at one point; (2) Place the sample on the upper surface of the lifting and translation stage, start the visible laser rangefinder, move the lifting and translation stage forward, backward, left and right according to the position of the light spot, so that the light spot falls on the sample to be measured, and then the visible laser rangefinder measures the distance d between it and the upper surface of the sample, and sends d to the real-time feedback system; (3) If d>d2, move the lifting and translation stage upward; if d<d2, move the lifting and translation stage downward until d=d2 to complete the adjustment. d is the distance between the visible laser rangefinder and the upper surface of the sample, and d2 is the distance between the visible laser rangefinder and the optimal sample placement point, which are known quantities.

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