Terahertz measurement devices and systems

Abstract

The embodiment of the present application provides a terahertz measurement device and system, which relates to the field of spectral imaging technology. The device includes: a body, a transmitting module and a receiving module installed on the top of the body, an optical scanning module installed on the first side of the body, a tracer laser module installed on the second side of the body, and a sensor module installed at the bottom of the body, wherein when the transmitting module stops emitting terahertz light, the tracer laser module emits a tracer laser and transmits it to the sample to be measured to form a laser measurement area, and the center of the tracer laser is coaxial with the center of the terahertz light; the optical scanning module scans the laser measurement area according to the reference scanning path to achieve model reconstruction of the surface of the sample to be measured; the reference scanning path is corrected through the model of the surface of the sample to be measured and the distance detected by the sensor module. The embodiment of the present application solves the problem of difficulty in achieving high-precision terahertz measurement in the related art.

Description

Technical Field

[0001] The present application relates to the technical field of spectral imaging, and in particular to a terahertz measurement device and system. Background Art

[0002] With the development of terahertz science and technology, the use of terahertz spectral imaging technology to measure samples has gradually become widely used. In related technologies, terahertz measurement methods usually use a terahertz time-domain spectrometer combined with a two-dimensional guide rail to measure the sample. However, this method is suitable for flat samples. For curved samples, its measurement accuracy will drop significantly as the curvature of the sample increases, and may even lead to measurement failure.

[0003] Therefore, robots are introduced into terahertz measurement to solve the problem of low measurement accuracy of curved samples by two-dimensional guide rails. At present, robot-based terahertz measurement methods usually adopt the "open-loop" control method of robot offline programming, which has limited improvement on terahertz measurement accuracy.

[0004] From the above, it can be seen that there are still limitations in the relevant technology that make it difficult to achieve high-precision terahertz measurement. Summary of the invention

[0005] Each embodiment of the present application provides a terahertz measurement device and system, which can solve the problem of difficulty in achieving high-precision terahertz measurement in related technologies. The technical solution is as follows:

[0006] According to one aspect of an embodiment of the present application, a terahertz measurement device is provided, comprising a body, a transmitting module and a receiving module installed on the top of the body, an optical scanning module installed on the first side of the body, a tracer laser module installed on the second side of the body, and a sensor module installed on the bottom of the body, wherein when the transmitting module stops emitting terahertz light, the tracer laser module emits a tracer laser and transmits it to the sample to be measured to form a laser measurement area, and the center of the tracer laser is coaxial with the center of the terahertz light; the optical scanning module scans the laser measurement area according to a reference scanning path to achieve model reconstruction of the surface of the sample to be measured; the reference scanning path is corrected by the model of the surface of the sample to be measured and the distance detected by the sensor module, and the distance refers to the distance of the terahertz measurement device relative to the surface of the sample to be measured.

[0007] In an exemplary embodiment, the transmitting module includes a terahertz transmitter, a first parabolic mirror and a second parabolic mirror, wherein the terahertz light is emitted by the terahertz transmitter and transmitted to the sample to be tested via the first parabolic mirror and the second parabolic mirror; the tracer laser passes through the center of the first parabolic mirror so that the center of the tracer laser is coaxial with the center of the terahertz light, and is transmitted to the sample to be tested via the second parabolic mirror.

[0008] In an exemplary embodiment, the device further comprises a spectral optical path module, which is respectively connected to the transmitting module and the receiving module through optical fibers, so that the terahertz light output by the spectral optical path module is respectively transmitted to the transmitting module and the receiving module.

[0009] In an exemplary embodiment, the spectral optical path module outputs terahertz light using a fast and slow dual-mode spectral scanning optical path; the fast and slow dual-mode spectral scanning optical path includes: the femtosecond laser generated by the laser is transmitted to the collimating lens through a single-mode optical fiber for collimation, and then is divided into two beams of femtosecond laser by a polarization beam splitter, one of which is coupled to the optical fiber connected to the transmitting module through a slow delay line with a long optical path, and the other is coupled to the optical fiber connected to the receiving module through a fast delay line with a short optical path.

[0010] In an exemplary embodiment, the spectral optical path module further includes a reflector for adjusting the alignment of the free-space optical path before the femtosecond laser is coupled to the optical fiber.

[0011] In an exemplary embodiment, the device further comprises a beam conditioning module mounted at the bottom of the body, and the sensor module is mounted at the bottom of the beam conditioning module for performing secondary focusing and modulation on the terahertz light.

[0012] In an exemplary embodiment, the beam conditioning module is a terahertz lens. The shape of the terahertz lens is hemispherical and the material of the terahertz lens is polymethylpentene (TPX).

[0013] In an exemplary embodiment, the target field of the optical scanning module is centered on the measuring direction of the terahertz measuring device, and the measuring direction of the terahertz measuring device is the incident direction of the terahertz light emitted by the transmitting module.

[0014] According to one aspect of an embodiment of the present application, a terahertz measurement system includes a processor and a robotic arm, and also includes the terahertz measurement device as described above, wherein the terahertz measurement device is installed at one end of the robotic arm, and when the processor controls the robotic arm to move according to a corrected reference scanning path, the terahertz measurement device follows the movement of the robotic arm.

[0015] In an exemplary embodiment, the system further includes a collection module for receiving terahertz light output by the terahertz measurement device and reflected by the sample to be measured, so that the processor measures the surface of the sample to be measured according to the received terahertz light.

[0016] The beneficial effects of the technical solution provided by this application are:

[0017] In the above technical solution, a tracer laser module and a sensor module are added to the terahertz measurement device, so that when the terahertz measurement is stopped, the tracer laser module emits a tracer laser and transmits it to the sample to be measured, forming a laser measurement area for the optical scanning module to scan according to the reference scanning path, so as to realize model reconstruction of the surface of the sample to be measured, and then form a corrected reference scanning path through the model of the surface of the sample to be measured and the distance detected by the sensor module for use in terahertz measurement, thereby realizing high-precision terahertz measurement of arbitrary curved surfaces. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in describing the embodiments of the present application are briefly introduced below.

[0019] Figure 1 is a schematic diagram of a terahertz measurement system according to the present application;

[0020] Figure 2 is a schematic diagram of a terahertz measurement device according to the present application;

[0021] Figure 3 is a schematic diagram of a terahertz measurement device according to an exemplary embodiment;

[0022] Figure 4 is a schematic diagram of optical paths of a transmitting module and a tracing laser module according to an exemplary embodiment;

[0023] Figure 5 is a schematic diagram of a beam conditioning module according to an exemplary embodiment;

[0024] Figure 6 is a schematic diagram of a fast and slow dual-mode spectral scanning optical path according to an exemplary embodiment;

[0025] Figure 7 is a schematic flow chart of a terahertz measurement process according to an exemplary embodiment;

[0026] Figure 8 is a schematic diagram showing a measurement direction of a terahertz measurement device according to an exemplary embodiment;

[0027] Fig. 9is a schematic diagram of a terahertz time-domain spectroscopy image according to an exemplary embodiment. DETAILED DESCRIPTION

[0028] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be interpreted as limiting the present application.

[0029] It will be understood by those skilled in the art that, unless expressly stated, the singular forms "one", "said", and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present application refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when we refer to an element as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be an intermediate element. In addition, the "connection" or "coupling" used herein may include wireless connection or wireless coupling. The term "and / or" used herein includes all or any unit and all combinations of one or more associated listed items.

[0030] As mentioned above, in order to improve the accuracy of terahertz measurement for curved surface samples, robots are introduced into terahertz measurement, which can also be understood as collaborative robots. At present, there are two ways to program robots: teaching programming and offline programming.

[0031] Compared with teaching programming, offline programming can plan complex paths for complex measurement tasks and obtain a more accurate reference scanning path. In addition, the offline programming simulation system can simulate the measurement task so that the generated simulation path can be modified and optimized in real time, making the reference scanning path more reasonable. The simulation does not affect the robot's work, which can greatly improve the robot's operating efficiency.

[0032] Therefore, robot-based terahertz measurement methods generally adopt an "open-loop" control method with offline programming. However, the reference scanning path obtained by simulation often deviates from the actual scanning path formed when performing terahertz measurement on the sample to be measured, which has limited effect on improving the accuracy of terahertz measurement.

[0033] It can be seen from the above that the related technology still has the defect of being difficult to achieve high-precision terahertz measurement.

[0034] To this end, the terahertz measurement device provided in the present application can effectively improve the accuracy of the scanning path, form a corrected reference scanning path, and further effectively improve the accuracy of terahertz measurement of arbitrary curved surfaces.

[0035] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below with reference to the accompanying drawings.

[0036] See also Figure 1 An embodiment of the present application provides a terahertz measurement system, which includes a terahertz measurement device 1, a system control module 2 and a collaborative robot module 3.

[0037] The system control module 2 includes but is not limited to: a processor 21 , an acquisition module 22 , a phase-locked amplifier 23 , a voice coil motor (ACS) 24 , and a bias voltage module 25 .

[0038] The collaborative robot module 3 includes but is not limited to: a robotic arm 31 and its controller 32 .

[0039] In one embodiment, the terahertz measurement device 1 is installed at one end of the robotic arm 31. When the processor 21 controls the robotic arm 31 to move according to the reference scanning path, the terahertz measurement device 1 moves with the robotic arm to achieve scanning imaging of the sample to be measured.

[0040] The system control module 2 can receive the terahertz light reflected by the sample to be measured and output by the terahertz measurement device 1 through the data acquisition module 22 , so that the processor 21 measures the surface of the sample to be measured according to the received terahertz light.

[0041] That is to say, on the one hand, the terahertz measurement system provides a terahertz measurement mode. Specifically, the frequency-adjustable square wave voltage signal is amplified by the bias voltage module 25 and connected to the electrode of the photoconductive antenna in the transmitting module 11 to form a bias electric field of the terahertz source, thereby emitting terahertz light and transmitting it to the sample to be measured, and finally reflecting the sample to be measured to the receiving module 12. At the same time, the phase-locked amplifier 23 filters and amplifies the analog signal output by the receiving module 12 (the reflected terahertz light is amplified by the preamplifier 183 to form a terahertz time domain waveform), so that the data acquisition card 22 can use the analog-to-digital converter to sample the output signal of the phase-locked amplifier 23, and finally input the collected signal into the processor 21 to achieve terahertz measurement of the sample to be measured.

[0042] On the other hand, the terahertz measurement system provides an offline programming optimization mode. Specifically, by adding a tracer laser module 14 and a sensor module 15 to the terahertz measurement device 1, when the terahertz measurement is stopped, the tracer laser module 14 emits a tracer laser and transmits it to the sample to be measured, forming a laser measurement area for the optical scanning module 13 to scan according to the reference scanning path to achieve model reconstruction of the surface of the sample to be measured, and then through the model of the surface of the sample to be measured and the distance detected by the sensor module 15, a corrected reference scanning path is formed for use in terahertz measurement.

[0043] It is worth mentioning that the frequency-adjustable square wave voltage signal is provided by the bias voltage module 25, with a voltage of 0 to 60V, a duty cycle of 50%, and a modulation frequency of 10KHz to 100KHz. This modulation frequency can be flexibly adjusted according to the actual needs of the application scenario, thereby effectively reducing the influence of the square wave voltage signal on the low-frequency electronic crosstalk signal, for example, the modulation frequency is 20KHz.

[0044] See also Figure 2 The embodiment of the present application provides a terahertz measurement device 1, which includes but is not limited to: a body 10, a transmitting module 11 and a receiving module 12 installed on the top of the body 10, an optical scanning module 13 installed on the first side of the body 10, a tracer laser module 14 installed on the second side of the body 10, and a sensor module 15 installed on the bottom of the body 10. Among them, the tracer laser module 14 is used to realize the visualization of the terahertz light scanning path, so as to assist the terahertz measurement; the sensor module 15 can be used to detect the distance between the terahertz measurement device 1 and the surface of the sample to be measured, and can also be used to detect the direction of the terahertz measurement device 1 relative to the surface normal vector of the sample to be measured.

[0045] In one embodiment, the first side portion and the second side portion of the body are not opposite to each other. For example, the first side portion may be the left side portion or the right side portion of the body, and the second side portion may be the front side portion or the rear side portion of the body; or, the first side portion may be the front side portion or the rear side portion of the body, and the second side portion may be the left side portion or the right side portion of the body, which is not limited here. Figure 3 FIG. 4 shows a schematic diagram of a specific structure of a terahertz measurement device in one embodiment. Figure 3 As shown, the installation position of the tracking laser module is located at the front side of the body, and the installation position of the optical scanning module is located at the left side of the body.

[0046] Please refer to Figure 2The embodiment of the present application provides a terahertz measurement device 1, which also includes: a beam conditioning module 16 installed at the bottom of the body 10, and a sensor module 15 installed at the bottom of the beam conditioning module 16, which is used to perform secondary focusing and modulation on the terahertz light to collect and transmit evanescent waves, slow down the attenuation of the evanescent waves, and thus realize sub-wavelength terahertz beams, which is conducive to super-resolution imaging in the far field. Figure 3 FIG. 4 shows a schematic diagram of a specific structure of a terahertz measurement device in one embodiment. Figure 2 As shown, the beam conditioning module is located between the body and the sensor module.

[0047] In one embodiment, the beam conditioning module is a terahertz lens, and the shape of the terahertz lens is hemispherical.

[0048] In one embodiment, the material of the terahertz lens is polymethylpentene (TPX), and the refractive index of the material in the terahertz lens is 1.45, and the light transmittance is 90% to 92%.

[0049] Therefore, on the one hand, by integrating the beam conditioning module into the terahertz measurement device, it is beneficial to both the transmission of the tracer laser and the sub-wavelength terahertz beam of the terahertz band injection effect generated by the terahertz lens; on the other hand, the beam conditioning module can be detachably connected to the bottom of the main body, which is beneficial to the subsequent upgrade and replacement, and can effectively improve the installation efficiency.

[0050] See also Figure 4 An embodiment of the present application provides a terahertz measurement device. In the terahertz measurement device, the transmitting module 11 includes but is not limited to: a terahertz transmitter 111 , a first parabolic mirror 112 and a second parabolic mirror 113 .

[0051] like Figure 4 As shown, the optical path of the transmitting module 11 includes: the terahertz light is emitted by the terahertz transmitter 111, and is transmitted to the sample to be tested 17 through the first parabolic mirror 112 and the second parabolic mirror 113. In one embodiment, the first parabolic mirror 112 and the second parabolic mirror 113 are off-axis parabolic mirrors, which are arranged in the body in an upper and lower spatially staggered manner.

[0052] Continue reading Figure 4 The optical path of the tracer laser module 14 includes: the tracer laser passes through the center of the first parabolic mirror 112 so that the center of the tracer laser is coaxial with the center of the terahertz light, and is transmitted to the sample 17 to be tested through the second parabolic mirror 113.

[0053] Therefore, by making the center of the tracing laser coaxial with the center of the terahertz light, it is not only beneficial to use off-line programming optimization and coordinate system correction of the robot control with field-correctable errors, but also beneficial to realize the visual tracing means to intuitively display the terahertz light scanning path to assist terahertz measurement.

[0054] See also Figure 5 The embodiment of the present application provides a terahertz measurement device 1, which also includes: a spectral optical path module 18, which is connected to the transmitting module 11 and the receiving module 12 through an optical fiber 181, so that the terahertz light output by the spectral optical path module 18 is transmitted to the transmitting module 11 and the receiving module 12 respectively.

[0055] In one embodiment, the spectral optical path module outputs terahertz light using a fast and slow dual-mode spectral scanning optical path. Specifically, the spectral optical path module includes but is not limited to: a laser and a delay line module, and the delay line module further includes: a slow delay line and a fast delay line, thereby forming a fast and slow dual-mode spectral scanning optical path.

[0056] In one embodiment, Figure 6 As shown, the fast and slow dual-mode spectral scanning optical path includes: the femtosecond laser generated by the laser 182 is transmitted to the collimator lens C1 (Collimator) through a single-mode optical fiber (Fiber) for collimation, and then is split into two femtosecond laser beams by a polarization beam splitter BS (Beam Splitter), one of which is coupled to the optical fiber connected to the transmitting module 11 through a slow delay line with a long optical path through a coupler FC1 (Fiber Couple), and the other femtosecond laser is coupled to the optical fiber connected to the receiving module 12 through a fast delay line with a short optical path through a coupler FC2. Among them, in the fast and slow dual-mode spectral scanning optical path, the spectral optical path module also includes: a plurality of reflectors (M1-M5) for adjusting and aligning the free space optical path before the femtosecond laser is coupled to the optical fiber.

[0057] In one embodiment, the maximum output power of the laser is 110 mW, and the diameter of the single-mode optical fiber is 0.5 m.

[0058] In one embodiment, the single-mode optical fiber is a single-mode polarization-maintaining optical fiber.

[0059] In one embodiment, the fast delay line uses a voice coil motor to drive a retroreflector for fast scanning, with a scanning range of 20 mm, a corresponding laser delay of 130 ps, ​​and a scanning frequency of ≥ 1 Hz. The delay position is fed back by a grating ruler with an accuracy of up to 0.1 μm.

[0060] Under the effect of the above embodiments, on the one hand, in combination with a robot and a terahertz measuring device, the terahertz measuring system is suitable for terahertz nondestructive testing of arbitrary curved surfaces; on the other hand, in combination with a tracing laser module and a sensor module, the robot control adopts offline programming optimization and coordinate system correction with field-correctable errors, and a visual tracing method is implemented to intuitively display the terahertz light scanning path to assist terahertz measurement; on the other hand, in combination with a beam conditioning module, high-resolution imaging of the far field is achieved, and finally a terahertz measurement system for arbitrary curved surfaces with high precision, high resolution, high integration, good compactness, and easy installation is realized.

[0061] Now combined Figures 7 to 9 , and the terahertz measurement system in the above embodiments, the terahertz measurement process is described in detail as follows:

[0062] like Figure 7 As shown, the terahertz measurement process may include the following steps:

[0063] Step 310, robot pre-calibration:

[0064] The first step is to establish a robot model based on improved DH parameters. Specifically, the robot kinematics modeling is performed according to the improved DH parameters, including the forward kinematics and inverse kinematics of the robot, and the robot kinematic parameters are determined. The robot model involved in each embodiment of the present application is an AUBO I5 robot. Of course, in other application scenarios, other models of robots can also be used, which does not constitute a specific limitation here.

[0065] The second step is to calibrate the robot kinematic parameters using a visual measurement system, determine the calibrated robot kinematic parameters, and obtain a robot model based on the calibrated robot kinematic parameters. Specifically, the calibration includes but is not limited to: robot base coordinate system calibration and connecting rod torsion angle calibration.

[0066] The third step is to calibrate the tool coordinate system. Due to the introduction of the terahertz measurement device, the robot tool coordinate system changes, and the center of the flange at the end of the robot (that is, the end of the robot arm connected to the terahertz measurement device) is translated to the focus of the terahertz measurement device. To this end, the tool coordinate system needs to be recalibrated. Specifically, the tool coordinate system is calibrated using the visual measurement system and the probe to obtain the transformation matrix between the robot end flange center coordinate system and the tool coordinate system, which is:

[0067]

[0068] Among them, T tool Represents the transformation matrix, Toolx represents the X-axis of the tool coordinate system, tooly represents the Y-axis of the tool coordinate system, and toolz represents the Z-axis of the tool coordinate system.

[0069] Then, based on this transformation matrix, the coordinate system at the center of the robot end flange can be transformed to obtain the coordinate system at the focus of the terahertz measurement device for use in subsequent terahertz measurements.

[0070] Step 330, robot pre-offline programming:

[0071] Based on the robot model and tool coordinate system calibration in step 310, a virtual simulation space is established using offline programming software, and the virtual simulation space is matched with the actual space where the sample to be tested is located with respect to the position of the sample to be tested. The motion path of the robot is planned using a Cartesian space trajectory planning method.

[0072] At the same time, combined with the surface normal at the interpolation point, the motion path planned for the robot is simulated, thereby realizing the reference scanning path planning and pre-offline programming of the laser measurement area, and generating the control script of the reference scanning path through post-processing.

[0073] Thus, based on the virtual simulation space, a reference scanning path is obtained through the first offline programming.

[0074] Step 350, field calibration and offline programming secondary optimization:

[0075] First, turn off the terahertz measurement function, that is, stop the emission module from emitting terahertz light, and turn on the tracer laser, that is, control the tracer laser module to emit the tracer laser, which is transmitted to the sample to be measured through the optical path and forms a laser measurement area. Figure 4 As shown, when the optical scanning module scans the laser measurement area according to the reference scanning path, the sensor module 15 and the optical scanning module move with the movement of the tracer laser, and the sensor module 15, the optical scanning module and the tracer laser light output point 141 are relatively fixed, which is also understood to be kept still, so that the lens in the optical scanning module is always aimed at the laser measurement area, thereby realizing model reconstruction of the surface of the sample to be measured.

[0076] The processor determines the actual deviation of the distance between the terahertz measuring device and the surface of the sample to be tested and the normal direction through the model indicated by the sample to be tested and the distance between the terahertz measuring device and the surface of the sample to be tested detected by the sensor model, so as to obtain the deviation value between the actual trajectory and the reference scanning path, and uses the deviation value to correct the reference scanning path, thereby improving the accuracy of the scanning path and forming a corrected scanning path.

[0077] Therefore, based on the actual space (site) where the sample to be tested is located, a revised reference scanning path is obtained through a second offline programming.

[0078] Step 370, terahertz measurement:

[0079] Turn on the terahertz measurement function and the tracer laser, that is, the transmitting module emits terahertz light, which is transmitted to the sample to be measured through the optical path, and is reflected by the sample to be measured and transmitted to the receiving module. At the same time, the tracer laser whose center is coaxial with the center of the terahertz light is used to intuitively display the terahertz light scanning path.

[0080] like Figure 8 As shown, the optical path of the terahertz light specifically includes: the terahertz light is emitted from the opening at the bottom of the main body after passing through two off-axis parabolic mirrors that are displaced in the upper and lower spaces, and is focused by the beam conditioning module to be incident on the surface of the sample to be measured (the incident angle is 30 degrees); after the terahertz light is reflected on the surface of the sample to be measured, the reflected terahertz light carrying the surface information of the sample to be measured (such as texture) enters the terahertz measurement device from the opening at the bottom of the main body, and is also incident on the receiving module after passing through two off-axis parabolic mirrors.

[0081] It is explained here that if Figure 8 As shown, the measuring direction of the terahertz measuring device is the incident direction of the terahertz light emitted by the transmitting module, and this is used as the center of the target field of the optical scanning module, thereby ensuring the accuracy of the scanning imaging.

[0082] The terahertz measurement of the sample to be measured is performed according to the corrected scanning path. Specifically:

[0083] In the first step, the terahertz measurement system continuously collects the waypoint information of the end of the robot arm fed back in real time by the robot arm controller, and combines it with the aforementioned conversion matrix to obtain the three-dimensional spatial coordinate information corresponding to the terahertz measurement device according to the waypoint information of the end of the robot arm.

[0084] In the second step, in combination with the three-dimensional spatial coordinate information corresponding to the terahertz measurement device, for each coordinate information, the terahertz time domain waveform from the receiving module is subjected to a time domain or frequency domain-based algorithm to obtain the terahertz imaging parameters.

[0085] The third step is to reconstruct the terahertz time-domain spectrum image of the sample surface according to the terahertz imaging parameters, such as Fig. 9 As shown, the terahertz measurement of the sample to be measured is performed according to the terahertz time-domain spectrum image to obtain the terahertz measurement result of the sample to be measured.

[0086] Through the above process, the terahertz measurement device and the robot are combined, and the robot is used as the carrier of the terahertz measurement device, which gives full play to the advantage of the robot's high flexibility. The robot is pre-calibrated, pre-offline programmed, on-site calibrated and offline programming secondary optimization, which not only effectively improves the accuracy of the scanning path, but also realizes high-precision "flexible" terahertz non-destructive testing of arbitrary curved surface samples, and finally realizes a robot-based terahertz adaptive measurement system.

[0087] It should be understood that, although the steps in the flowchart of the accompanying drawings are displayed in sequence as indicated by the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least a part of the steps in the flowchart of the accompanying drawings may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and their execution order is not necessarily sequential, but can be executed in turn or alternately with other steps or at least a part of the sub-steps or stages of other steps.

[0088] The above description is only a partial implementation method of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A terahertz measurement system, comprising a processor and a robotic arm, characterized in that: The system also includes a terahertz measuring device, which includes a body, a transmitting module and a receiving module installed on the top of the body, an optical scanning module installed on the first side of the body, a tracer laser module installed on the second side of the body, and a sensor module installed on the bottom of the body, wherein the tracer laser module is used to realize the visualization of the terahertz light scanning path to assist the terahertz measurement; the sensor module is used to detect the distance between the terahertz measuring device and the surface of the sample to be measured, and to detect the direction of the terahertz measuring device relative to the normal vector of the surface of the sample to be measured, wherein: When the emission module is stopped from emitting terahertz light, the tracer laser module emits a tracer laser and transmits it to the sample to be measured to form a laser measurement area, and the center of the tracer laser is coaxial with the center of the terahertz light; The optical scanning module scans the laser measurement area according to the reference scanning path to achieve model reconstruction of the surface of the sample to be measured; The processor determines the actual deviation between the distance between the terahertz measuring device and the surface of the sample to be measured and the normal direction through the model of the surface of the sample to be measured and the distance between the terahertz measuring device and the surface of the sample to be measured detected by the sensor module, so as to obtain the deviation value between the actual trajectory and the reference scanning path, and uses the deviation value to correct the reference scanning path, so as to improve the accuracy of the scanning path, thereby forming a corrected scanning path; The terahertz measurement device is installed at one end of the mechanical arm, and when the processor controls the mechanical arm to move according to the corrected scanning path, the terahertz measurement device moves with the mechanical arm; The terahertz measurement of the sample to be measured is carried out according to the corrected scanning path.

2. The system according to claim 1, characterized in that The transmitting module includes a terahertz transmitter, a first parabolic mirror and a second parabolic mirror, wherein: The terahertz light is emitted by the terahertz emitter and transmitted to the sample to be tested via the first parabolic mirror and the second parabolic mirror; The tracer laser passes through the center of the first parabolic mirror, so that the center of the tracer laser is coaxial with the center of the terahertz light, and is transmitted to the sample to be tested through the second parabolic mirror.

3. The system according to claim 1, characterized in that The device also includes a spectral optical path module, which is connected to the transmitting module and the receiving module respectively through optical fibers, so that the terahertz light output by the spectral optical path module is transmitted to the transmitting module and the receiving module respectively.

4. The system according to claim 3, characterized in that The spectral optical path module outputs terahertz light using a fast and slow dual-mode spectral scanning optical path; The fast-slow dual-mode spectral scanning optical path includes: the femtosecond laser generated by the laser is transmitted to the collimating lens through a single-mode optical fiber for collimation, and then is divided into two femtosecond laser beams by a polarization beam splitter, one of which is coupled to the optical fiber connected to the transmitting module through a slow delay line with a long optical path, and the other is coupled to the optical fiber connected to the receiving module through a fast delay line with a short optical path.

5. The system according to claim 4, characterized in that The spectral optical path module also includes a reflector for adjusting the alignment of the free space optical path before the femtosecond laser is coupled to the optical fiber.

6. The system according to claim 1, wherein: The device also includes a beam conditioning module installed at the bottom of the body, and the sensor module is installed at the bottom of the beam conditioning module for performing secondary focusing and modulation on the terahertz light.

7. The system according to claim 6, characterized in that The beam conditioning module is a terahertz lens. The shape of the terahertz lens is hemispherical and the material of the terahertz lens is polymethylpentene.

8. The system according to any one of claims 1 to 7, characterized in that: The target field of the optical scanning module is centered on the measuring direction of the terahertz measuring device, and the measuring direction of the terahertz measuring device is the incident direction of the terahertz light emitted by the transmitting module.

9. The system according to claim 1, characterized in that The system further comprises a collection module for receiving the terahertz light output by the terahertz measurement device and reflected by the sample to be measured, so that the processor measures the surface of the sample to be measured according to the received terahertz light.

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