CN111141701A - Rapid super-resolution imaging method and system based on terahertz single pulse - Google Patents
Rapid super-resolution imaging method and system based on terahertz single pulse Download PDFInfo
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Abstract
本发明公开了一种基于太赫兹单脉冲的快速超分辨成像方法及系统，包括激光器、激光分束器、太赫兹波发射器、三维载物台、太赫兹波收集器、倾斜脉冲产生器、太赫兹波调制器、探测器、时间延迟器和运动控制与图像处理系统。本方法根据空气电离产生的等离子体丝直径小、等离子体丝截断处辐射太赫兹能量高的优点，结合太赫兹单脉冲快速测量技术和太赫兹波成像技术，实现了快速超分辨二维成像。本系统的空间分辨率达到50微米，成像速度达到27像素/秒，可以适用于国防、安检和生物医学等领域。
The invention discloses a fast super-resolution imaging method and system based on a terahertz single pulse, comprising a laser, a laser beam splitter, a terahertz wave transmitter, a three-dimensional object stage, a terahertz wave collector, an inclined pulse generator, Terahertz wave modulators, detectors, time delayers, and motion control and image processing systems. According to the advantages of the small diameter of the plasma filament generated by air ionization and the high radiation terahertz energy at the truncation of the plasma filament, the method combines the terahertz single-pulse fast measurement technology and the terahertz wave imaging technology to realize fast super-resolution two-dimensional imaging. The spatial resolution of this system reaches 50 microns, and the imaging speed reaches 27 pixels/second, which can be applied to the fields of national defense, security inspection and biomedicine.
Description
Technical Field
The invention relates to a terahertz generation technology, a terahertz single-pulse measurement technology and a terahertz imaging technology, and belongs to the technical field of rapid super-resolution terahertz wave two-dimensional imaging.
Background
Terahertz (THz) is an electromagnetic wave with a frequency of 0.1 THz to 10 THz, and the wavelength of the electromagnetic wave is 0.03 mm to 3 mm, which is also called millimeter wave or submillimeter wave.
According to the terahertz imaging, terahertz waves are converged and irradiated to a sample to be detected through an optical device, terahertz waves transmitted or reflected from the sample are collected through a detection device, then the terahertz waves containing sample characteristic information are converted into corresponding voltage or current signals through a photoelectric sensor, and finally the signals are converted into terahertz images which are easy to observe through imaging software.
Compared with electromagnetic wave imaging such as gamma rays, X rays and infrared rays, the terahertz wave has unique properties: transient, broadband, low energy and the like, the terahertz imaging technology has become an advantageous imaging technology means besides X-ray imaging and infrared imaging, has become one of key technologies for terahertz application, and has wide application in the aspects of security inspection, nondestructive detection, tissue lesion detection and the like.
In a traditional terahertz time-domain spectroscopy imaging system, a sample to be imaged is generally placed at a focal plane between two groups of terahertz lenses, and although the energy of terahertz waves at the focal point is concentrated, the diameter of a terahertz wave beam at the focal point is large and cannot reach hundreds of microns; and is very susceptible to the diffraction limit of the wavelength, resulting in spatial resolution of only a few hundred microns, which makes sub-wavelength imaging difficult to achieve. In addition, the conventional terahertz time-domain spectroscopy imaging system utilizes a terahertz continuous pulse detection technology to detect optical signals, utilizes mechanical delay to realize time delay, and needs to continuously scan terahertz pulses to extract terahertz waveform signals, so that the defect of low imaging speed exists, and the real-time requirement of rapid scanning imaging cannot be met.
Disclosure of Invention
The invention provides a rapid super-resolution imaging method and system based on a terahertz single pulse, aiming at the problems of low spatial resolution and low imaging speed of a traditional terahertz time-domain spectral imaging system.
According to the method, the advantages of small diameter of a plasma wire generated by air ionization and high radiation terahertz energy at the cut-off position of the plasma wire are combined with a terahertz single-pulse rapid measurement technology and a terahertz wave imaging technology, and rapid super-resolution two-dimensional imaging is realized. The spatial resolution of the system reaches 50 microns, the imaging speed reaches 27 pixels/second, and the system can be applied to the fields of national defense, security inspection, biomedicine and the like.
According to the system, a sample to be imaged is placed at the cut-off position of the plasma wire 403 generated by air ionization, and compared with the terahertz energy and the beam diameter at the focus between the two groups of terahertz lenses, the terahertz energy at the cut-off position of the plasma wire 403 is higher, the diameter of the plasma wire is smaller, the energy of the terahertz wave after passing through the sample can be increased, and the two-dimensional spatial resolution of the sample is improved.
Compared with the traditional terahertz continuous wave detection method, the terahertz wave single-pulse detection is realized by adopting a mode that the pulse front edge is inclined, the optical delay line is not needed to be used for changing the optical path difference delay in single-pulse measurement, the terahertz wave waveform can be detected only by capturing a light spot image containing terahertz wave information by using the scientific camera 804, and the terahertz pulse detection speed is greatly improved. In addition, the terahertz wave single-pulse detection method based on the pulse front edge inclination has the advantages of simple optical path structure and less required optical equipment.
Based on the above principle, the present invention is achieved by the following technical ideas.
The system structure of the invention is composed of the following parts: the terahertz wave imaging device comprises a laser 1, a laser beam splitter 2, a terahertz wave emitter 3, a three-dimensional stage 4, a terahertz wave collector 5, an inclined pulse generator 6, a terahertz wave modulator 7, a detector 8, a time delay 9 and a motion control and image processing system 10.
The laser beam splitter 2 splits the femtosecond laser I emitted by the laser 1 into two beams of light with different energies.
The first beam of light is pump light II, the pump light II drives the terahertz wave emitter 3 to radiate terahertz waves IV, and the terahertz waves IV vertically transmit through a sample 402 to be imaged, then enter the terahertz wave collector 5 and then enter the terahertz wave modulator 7.
The other beam is a detection beam III which passes through an inclined pulse generator 6 to generate a pulse front edge inclination effect to become an inclined detection beam V and then enters a terahertz wave modulator 7.
The terahertz-wave transmitter 3 includes the following three components: a pump light mirror 301, a pump light lens 302, and a BBO crystal 303. Because BBO crystal (the scientific name is barium metaborate crystal) has second-order nonlinear effect, optical frequency doubling can be generated, and terahertz waves with higher energy can be radiated at the air ionization position.
The three-dimensional object stage 4 consists of a ceramic plate 401, a sample to be imaged 402 and a three-dimensional translation stage 404 and is positioned between the terahertz wave emitter 3 and the terahertz wave collector 5; the ceramic plate 401 is used for cutting off the air plasma filament 403, so that the sample 402 to be imaged can be protected from physical breakdown of the air plasma filament 403, and the focused pump light II with high energy can be completely resisted; meanwhile, the ceramic plate 401 has weak absorption to terahertz waves, so that energy loss of the penetrating terahertz waves is smaller; during imaging test, a sample 402 to be imaged is tightly attached to the back of the ceramic plate 401 and is fixed on the three-dimensional translation table 404; the ceramic plate 401 is always kept at the position of the air plasma filament 403 by adjusting the Z-axis direction of the three-dimensional translation stage 404, namely the propagation direction of the terahertz wave IV.
The terahertz-wave collector 5 is composed of a first terahertz-wave lens 501 and a second terahertz-wave lens 502.
The oblique pulse generator 6 is composed of 601 an attenuator, a blazed grating 602, a probe light reflector 603, and a probe light focusing lens 604, and functions to change the probe light III into oblique probe light V by the blazed grating 602.
The terahertz wave modulator 7 consists of a silicon chip 701 and a ZnTe crystal 702, wherein the silicon chip is used for reflecting the inclined detection light V and transmitting the terahertz wave IV; the ZnTe crystal 702 is used as a medium for modulating the terahertz wave IV and the inclined detection light V, and when the terahertz wave IV and the inclined detection light V are simultaneously incident to the ZnTe crystal 702 in a point-sharing manner, the polarization state of the inclined detection light V can be changed, so that the modulated light VI carries the information of the terahertz wave IV.
The detector 8 is composed of a first modulated light lens 801, a second modulated light lens 802, a polarizing plate 803, and a scientific-grade camera 804.
And the time delayer 9 is used for compensating the time delay difference between the electrical trigger signal output by the laser 1 and the modulated light VI signal received by the scientific-grade camera 804 in the system, and ensuring that the optical path difference between the pump light II and the probe light III is consistent.
A motion control and image processing system 10, which is mainly composed of computer hardware and corresponding control and data processing software, and is used for adjusting the repetition frequency of the femtosecond laser I output by the laser 1; controlling the timely movement of the three-dimensional translation stage 404; sending a photographing instruction to the scientific camera 804 to capture a spot image of the modulated light VI, receiving image data sent back by the scientific camera 804, and performing two-dimensional image reconstruction and image preprocessing according to the image data.
Preferably, the laser beam splitter adopts a beam splitter with adjustable splitting energy ratio.
Preferably, the pump light reflector and the probe light reflector adopt low-dispersion femtosecond laser special reflector.
Preferably, the ceramic plate is an alumina ceramic plate having a thickness of 0.3 mm to 0.68 mm.
Preferably, the focal length of the second terahertz lens is smaller than that of the detection light focusing lens.
Preferably, the blazed grating described above employs a high resolution blazed grating with a groove density higher than 1200 lines/mm.
Preferably, the three-dimensional translation stage adopts a three-axis linkage programmable translation stage with the precision of 1 micron.
Preferably, the scientific camera adopts a special beam analysis camera with higher frame rate and higher dynamic range.
Preferably, the pumping light lens, the detection light focusing lens, the first modulation light lens and the second modulation light lens are all plano-convex lenses.
Preferably, the first terahertz lens and the second terahertz lens are both made of a terahertz wave special lens made of polymethylpentene.
Compared with the existing terahertz wave imaging technology, the terahertz wave imaging method has the following three beneficial effects.
The spatial resolution is higher. Compared with terahertz waves at the focus between the two groups of terahertz lens pairs, the diameter of the air plasma filament 403 generated by air ionization is smaller, so that the spatial resolution reaches 50 micrometers.
The image signal-to-noise ratio is higher. The terahertz wave energy at the air plasma wire 403 cut off by the ceramic plate 401 is higher, so that the energy of the terahertz wave after penetrating through the sample 402 to be imaged can be increased, the scientific camera 804 can capture the terahertz wave information more obviously, and the imaging quality of the terahertz wave imaging device is improved.
The imaging speed is faster. In the terahertz wave detection method, a single-pulse measurement mode based on pulse front edge inclination is adopted, and terahertz waveform detection can be realized only by capturing a light spot image containing terahertz wave information by using the scientific camera 804, so that the terahertz pulse detection speed is greatly improved.
Drawings
Fig. 1 is a schematic structural diagram of the system.
Fig. 2 is a schematic diagram of the optical path and signal control of the system. Wherein the dashed lines represent electrical signals and the thick solid lines represent optical signals.
FIG. 3 is a terahertz single-pulse detection schematic diagram based on pulse leading edge inclination.
Fig. 4 is a schematic diagram of the pulse front edge tilt generated by a blazed grating.
Fig. 5 is a flow chart of a two-dimensional imaging of the present system.
Fig. 6 is a flowchart of the search for the Z-axis optimum imaging position.
Fig. 7 is a schematic diagram of the relative spatial positions of an air plasma filament and a sample to be imaged.
Fig. 8 is a flow chart of single point pixel value fitting calculation.
Fig. 9 is a schematic diagram of a two-dimensional scanning mode of a sample to be imaged.
Fig. 10 is a flow chart of two-dimensional image reconstruction and processing.
The legends are respectively
I-femtosecond laser II-pump light III-probe light IV-terahertz wave V-inclined probe light VI-modulated light
1-laser 2-laser beam splitter 3-terahertz wave transmitter 4-three-dimensional objective table
5-terahertz wave collector 6-inclined pulse generator 7-terahertz wave modulator 8-detector
9-time delay 10-motion control and image processing system
301-pump light reflector 302-pump light lens 303-BBO crystal
401-ceramic plate 402-sample 403 to be imaged-air plasma filament 404-three-dimensional translation stage
501-first terahertz lens 502-second terahertz lens
601-attenuation sheet 602-blazed grating 603-detection light reflector 604-detection light focusing lens
701-silicon wafer 702-ZnTe crystal
801-first modulating light lens 802-second modulating light lens 803-polarizer 804-scientific grade camera
Detailed Description
In order to better explain the technical implementation idea of the present invention and to highlight the advantages of the present invention, the following description will be made with reference to the accompanying drawings.
Based on the above principle, as shown in fig. 1 and fig. 2, the hardware functional modules involved in the present invention are divided into the following parts: the terahertz wave imaging device comprises a laser, a laser beam splitter, a terahertz wave transmitter, a three-dimensional object stage, a terahertz wave collector, a tilt pulse generator, a terahertz wave modulator, a detector, a time delay device and a motion control and image processing system.
In the system, the laser adopts a titanium sapphire regenerative amplification femtosecond laser, the output power is not lower than 7 watts, the pulse width is about 35 femtoseconds, the repetition frequency is 1000 hertz, the wavelength is 800 nanometers, and the energy stability is within 1 percent.
The laser beam splitter divides the laser source into two beams of light with different energies: pump light and probe light. In the system, the energy ratio of the pump light to the probe light is 9: 1.
The terahertz wave transmitter includes the following three optical devices: a pump light reflector, a pump light lens and a BBO crystal. Wherein, the pumping light reflector adopts a low-dispersion femtosecond laser special mirror; the focal length of the pump light lens is 500 mm, and the light inlet surface is a convex surface; the distance between the BBO crystal and the pump light lens is 200 mm.
The three-dimensional object stage is composed of a ceramic plate, a sample to be imaged and a three-dimensional translation stage. In the system, the ceramic plate is an alumina ceramic plate with the thickness of 0.68 mm, and the size is 100 mm x 100 mm; the three-dimensional translation stage adopts a three-axis linkage programmable translation stage with the precision of 1 micron, and the maximum stroke distance of each axis is 80 millimeters.
The terahertz wave collector consists of a first terahertz lens and a second terahertz lens. In the system; the first terahertz lens and the second terahertz lens are made of polymethyl pentene and are special terahertz wave lenses, and focal lengths of the first terahertz lens and the second terahertz lens are 150 mm and 100 mm respectively.
The inclined pulse generator is composed of an attenuation sheet, a blazed grating, a detection light reflector and a detection light focusing lens. In the system, the adjustable attenuation degree range of the attenuation sheet is 10% -90%; the blazed wavelength of the blazed grating is 800 nanometers, and the groove density is 1200 lines/millimeter; the focus of the probe light focusing lens is 200 mm.
The terahertz wave modulator consists of a silicon wafer and ZnTe crystals, wherein in the system, the thickness of the silicon wafer is 1 mm, and the size of the silicon wafer is 40 mm by 40 mm; the thickness of the ZnTe crystal is 1 mm.
The detector is composed of a first modulation light lens, a second modulation light lens, a polaroid and a scientific-grade camera. In the system, the focal lengths of the first modulation optical lens and the second modulation optical lens are respectively 150 mm and 100 mm; the scientific camera adopts a special camera for beam analysis, the maximum resolution is 1928 × 1448, and the frame rate at the full resolution is 27 fps.
The time delayer adopts a digital delay generator. In the system, the delayed trigger pulse time of the camera is set by combining the electrical parameters of the scientific camera and the optical path distance of the system.
The system adopts a high-performance desktop computer, and carries out secondary software development based on a program package of a scientific camera and a three-dimensional translation platform; in addition, according to the light spot image of the captured modulated light, the light spot image data is read in real time, and two-dimensional image reconstruction and image preprocessing are performed according to the signal.
The system adopts a single-pulse detection method based on pulse leading edge inclination to realize the detection of the terahertz waves, and the terahertz wave rapid detection principle of the system is explained in more detail below.
The terahertz single-pulse detection principle based on pulse leading edge inclination is shown in fig. 3. Firstly, after the detection light is incident to the blazed grating, the diffracted detection light can generate a pulse front edge inclination phenomenon; after being reflected by a silicon wafer, the pulse front edge inclined detection light and the terahertz wave penetrating through the silicon wafer are transmitted in a collinear way and enter a ZnTe crystal; due to the fact that the terahertz waves can enable ZnTe to generate a birefringence effect, the birefringence effect can change the polarization state of the detection light to generate an optical modulation effect, the modulated detection light is programmed to modulate the light and carries terahertz wave information; capturing a modulated light spot image carrying terahertz wave information by using a camera, wherein the image is composed of a series of longitudinal stripes with alternate light and shade and unequal brightness; and finally, further data processing is carried out according to the light spot image, and a terahertz wave curve can be drawn.
In general, the included angle between the equal amplitude surface and the equal phase surface in the laser is zero, and when the laser passes through a dispersion element (prism or grating), a certain included angle is formed between the equal amplitude surface (energy plane) and the equal phase surface of the pulse due to the refraction or diffraction principle, that is, the leading edge of the pulse is inclined.
The system adopts blazed gratings to realize the pulse front edge inclination. The principle of the pulse leading edge inclination generated by the blazed grating is shown in fig. 4, a beam of light is incident on the grating at a certain angle, each small groove can be regarded as a coherent sub-light source, and since the size of each small groove and the incident wavelength are in the same order of magnitude, the light diffracted from the small grooves will interfere. When a beam of laser is incident on the blazed grating at a certain angle, light diffracted by the grating is subjected to dispersion, and light diffracted by adjacent small grooves has a certain optical path difference, so that the pulse front edge is inclined.
Assuming that the distance between two adjacent grooves of the blazed grating is d, the blazed angle isABlazed wavelength ofF(ii) a The incident angle of the light beam isBDiffraction angle ofCThe angle of inclination of the leading edge of the pulse isD(ii) a The grating equation is:
whereinmFor spectral order, the general default ism=1, namely:
whileL 1=LsinB，L2=LsinC，W I =LcosBThe maximum spatial distance between the sub-beams after diffraction by the blazed grating is as follows:
the diameter of the light beam after diffraction by the blazed grating is as follows:
and (3) calculating the inclination angle of the pulse front edge by combining the formula (3) and the formula (4):
according to the formula of angular dispersion of blazed gratings:
substituting equation (6) into equation (5) has:
when a blazed grating with a groove density of 1200 lines/mm is used, the angle of inclination of the pulse front is about 28 degrees, and the maximum spatial distance between the sub-beams after diffraction by the blazed grating can reach 20 picoseconds.
According to the imaging system workflow diagram of fig. 5, the imaging steps of the present system can be simplified into four steps.
Step one, determining the Z-axis maximum imaging position of the three-dimensional translation table. The aim is to ensure that a sample to be imaged is at the position where the terahertz wave energy is strongest.
The searching process of the most imaging position of the Z axis is shown in fig. 6, firstly, a sample to be imaged is not placed on the three-dimensional object stage temporarily, and terahertz waves are guaranteed to act on the ceramic plate directly; then, acquiring a fitting pixel value of the current position every time the Z-axis position moves once until the scanning of all the Z-axis positions is completed to obtain a fitting pixel value sequence; and finally, selecting a stable maximum value image area according to the pixel value sequence, and finally obtaining the optimal imaging position of the Z axis.
And step two, fixing the sample to be imaged. Fig. 7 shows the spatial relative positions of the ceramic plate, the sample to be imaged and the air plasma filament, and the specific implementation method is as follows.
After the optimal imaging position of the Z axis is determined, the ceramic plate is cut off at the middle position of the air plasma wire, a sample to be imaged is tightly attached to the back of the ceramic plate and is fixed on the three-dimensional translation table, and the imaging surface of the sample to be imaged is ensured to be vertical to the Z axis. Wherein the XOY plane is an imaging plane, the Z axis is the propagation direction of the terahertz waves, and the X axis, the Y axis and the Z axis are mutually vertical in pairs.
And step three, scanning and obtaining fitting pixel values of all pixel points. The flow of obtaining the fitted pixel values is shown in fig. 8, and the specific implementation process is as follows.
First, a foreground streak image P is acquired. Collecting a fringe image of the probe light as a background fringe image P1 in the case where no terahertz wave is incident; starting terahertz waves, and collecting a stripe image P2 of modulated light with terahertz wave information; the two images are subtracted pixel by pixel P2-P1, and the obtained difference image is used as the foreground stripe image P of the current pixel.
And secondly, carrying out pixel value fitting according to the foreground fringe image P. Firstly, carrying out coordinate correction on the foreground stripe image P; then, calculating the gray level mean value of each column to obtain a gray level mean value sequence; then drawing a terahertz waveform curve according to the mean sequence; and finally, calculating the energy integral value of the waveform as a fitting pixel value of the current pixel.
In the pixel scan order, the system uses a "bow" scan, as shown in FIG. 9. After the sample to be imaged starts from the position (X1, Y1) and the fitted pixel value of the current position is obtained, the sample to be imaged moves to the next position according to the arrow direction in the figure to obtain the fitted pixel value of the position; and repeating the steps until the scanning of all the positions is completed, and obtaining a fitting pixel matrix.
And fourthly, performing two-dimensional image reconstruction and image preprocessing according to the fitted pixel matrix. The two-dimensional image reconstruction and processing flow is shown in fig. 10, and the specific implementation process is as follows.
Firstly, performing normalization processing on a fitting pixel matrix, and simultaneously performing data type conversion to realize two-dimensional image reconstruction; next, the imaging color mode is selected: the gray mode or the pseudo color mode is selected according to the normalized data types respectively; then, respectively carrying out image preprocessing on the two mode images, including median filtering, gray level enhancement and color rendering enhancement, so as to improve the quality of the two-dimensional image; and finally outputting a two-dimensional image of the sample to be detected.
Claims (7)
1. A rapid super-resolution imaging method and system based on a terahertz monopulse are characterized by comprising a laser (1), a laser beam splitter (2), a terahertz wave emitter (3), a three-dimensional object stage (4), a terahertz wave collector (5), an inclined pulse generator (6), a terahertz wave modulator (7), a detector (8), a time delayer (9) and a motion control and image processing system (10).
2. The terahertz monopulse-based fast super-resolution imaging method and system as claimed in claim 1, wherein the femtosecond laser (I) output from the laser (1) is split into two beams of light with different energies by the laser beam splitter (2): pump light (II) and probe light (III); the pumping light (II) drives the terahertz wave emitter (3) to radiate terahertz waves (IV), the terahertz waves (IV) are firstly vertically transmitted through a sample to be imaged (402) and then sequentially incident to the terahertz wave collector (5) and the terahertz wave modulator (7); the detection light (III) enters the inclined pulse generator (6), the leading edge of the pulse inclines to be changed into inclined detection light (V), and then the inclined detection light enters the terahertz wave modulator (7).
3. The terahertz monopulse-based rapid super-resolution imaging method and system according to claim 1, wherein the terahertz wave (IV) and the inclined probe light (V) are modulated in the terahertz wave modulator (7), so that the polarization state of the inclined probe light (V) is changed to become modulated light (VI); modulated light (VI) enters the detector (8) at normal incidence; the time delay device (9) controls the time difference of pulse trigger signals between the laser (1) and the detector (8), the motion control and image processing system (10) sends a photographing instruction to the detector (8) to capture real-time imaging signals, and finally, two-dimensional images are obtained through data processing.
4. The terahertz monopulse-based rapid super-resolution imaging method and system according to claim 1, wherein the three-dimensional stage (4) is located between the terahertz wave emitter (3) and the terahertz wave collector (5) and is composed of a ceramic plate (401), a sample (402) to be imaged and a three-dimensional translation stage (404); wherein, the sample (402) to be imaged is clung to the back of the ceramic plate (401), both are fixed on the three-dimensional translation stage (404), and the sample (402) to be imaged and the ceramic plate (401) are both ensured to be positioned at the position where the air plasma wire (403) is generated.
5. The terahertz single-pulse-based rapid super-resolution imaging method and system according to claim 2, characterized in that a single-pulse detection mode based on pulse front edge tilt is adopted to rapidly detect terahertz waves; the inclined pulse generator (6) is composed of an attenuation sheet (601), a blazed grating (602), a detection light reflecting mirror (603) and a detection light focusing lens (604), and aims to enable the leading edge of a pulse of detection light (III) to incline to become inclined detection light (V).
6. The terahertz monopulse-based fast super-resolution imaging method and system as claimed in claim 3, wherein the time delay device (9) is used to compensate the time delay difference between the electrical trigger signal of the laser (1) and the modulated light (VI) signal received by the scientific camera (804) in the system, so as to ensure the optical path difference between the pump light (II) and the probe light (III) to be consistent.
7. The terahertz monopulse-based rapid super-resolution imaging method and system according to claim 3, wherein when the sample (402) to be imaged is scanned in a point-by-point moving manner in a zigzag manner, the scientific camera (804) acquires a difference spot image signal of the modulated light (VI) with or without the terahertz wave (IV); the motion control and image processing system (10) corrects the coordinates of the difference light spot image, draws a corresponding terahertz waveform, calculates the energy integral value of the terahertz waveform and takes the energy integral value as a fitting pixel value of the current moving position of the sample (402) to be imaged; when the sample (402) to be imaged completes all point moving scanning, a two-dimensional fitting pixel value matrix is obtained; the motion control and image processing system (10) normalizes the two-dimensional fitting pixel value matrix, and finally performs two-dimensional image reconstruction and image preprocessing.
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Cited By (7)
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| CN112504991A (en) * | 2020-11-26 | 2021-03-16 | 西南科技大学 | Terahertz optical parameter extraction method and system for solid powder |
| CN112894149A (en) * | 2021-01-21 | 2021-06-04 | 北京理工大学 | Ultrafast continuous three-dimensional imaging system and method for ablating object by ultrashort pulse laser |
| CN113314852A (en) * | 2021-05-25 | 2021-08-27 | 上海交通大学 | Plasma modulator and electromagnetic wave vector microscopic sensor |
| CN114760404A (en) * | 2022-04-22 | 2022-07-15 | 五邑大学 | Laser pulse observation device |
| CN116067494A (en) * | 2023-02-20 | 2023-05-05 | 中国人民解放军国防科技大学 | Terahertz Single Shot Measurement System |
| CN116224606A (en) * | 2023-02-10 | 2023-06-06 | 中国科学院上海光学精密机械研究所 | Device and method for joint control of space and time of ultra-intense and ultra-short laser |
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| CN112504991A (en) * | 2020-11-26 | 2021-03-16 | 西南科技大学 | Terahertz optical parameter extraction method and system for solid powder |
| CN112504991B (en) * | 2020-11-26 | 2022-04-22 | 西南科技大学 | Terahertz optical parameter extraction method and system for solid powder |
| CN112894149A (en) * | 2021-01-21 | 2021-06-04 | 北京理工大学 | Ultrafast continuous three-dimensional imaging system and method for ablating object by ultrashort pulse laser |
| CN112894149B (en) * | 2021-01-21 | 2021-11-30 | 北京理工大学 | Ultrafast continuous three-dimensional imaging system and method for ablating object by ultrashort pulse laser |
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| CN113314852A (en) * | 2021-05-25 | 2021-08-27 | 上海交通大学 | Plasma modulator and electromagnetic wave vector microscopic sensor |
| CN114760404A (en) * | 2022-04-22 | 2022-07-15 | 五邑大学 | Laser pulse observation device |
| CN114760404B (en) * | 2022-04-22 | 2023-07-21 | 五邑大学 | Laser pulse observation equipment |
| CN116224606A (en) * | 2023-02-10 | 2023-06-06 | 中国科学院上海光学精密机械研究所 | Device and method for joint control of space and time of ultra-intense and ultra-short laser |
| CN116067494A (en) * | 2023-02-20 | 2023-05-05 | 中国人民解放军国防科技大学 | Terahertz Single Shot Measurement System |
| CN116067494B (en) * | 2023-02-20 | 2023-10-03 | 中国人民解放军国防科技大学 | Terahertz single shot measurement system |
| CN116382023A (en) * | 2023-04-07 | 2023-07-04 | 深圳技术大学 | Tens of millions of frame frequency ultra-high speed terahertz imaging system |
| CN116382023B (en) * | 2023-04-07 | 2023-10-13 | 深圳技术大学 | Tens of millions of frame frequency ultra-high speed terahertz imaging system |
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