All-solid-state ultrafast electro-optic framing imaging system and imaging method

Abstract

The application provides a full solid-state ultrafast electro-optical framing imaging system and an imaging method, and aims to solve the technical problems that the framing images are not completely separated due to the small deflection angle of an electro-optical crystal in the existing ultrafast pulse framing imaging technology based on electro-optical deflection, and the imaging quality and the system response speed are significantly reduced when the problem of the small deflection angle of the electro-optical crystal is solved by increasing the deflection angle through a rotating mirror or the compressed sensing imaging of overlapping beams. The full solid-state ultrafast electro-optical framing imaging system adopts a lithium niobate crystal as an electro-optical deflection device, and arranges an upper electrode array and a lower electrode array on the upper and lower surfaces of the lithium niobate crystal, so that a periodic refractive index distribution is formed in the lithium niobate crystal along the pulse laser emission direction, and the pulse laser passing at different moments is deflected at different angles, thereby ensuring the system response speed and the imaging quality on the basis of meeting the electro-optical crystal deflection angle requirement.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ultrafast imaging, in particular to a full solid-state ultrafast electro-optic framing imaging system and an imaging method. BACKGROUND

[0002] Ultrafast imaging technology is developed from traditional high-speed photography technology, and gradually realizes higher resolution and accuracy. Traditional high-speed photography technology such as digital high-speed image converter tube is difficult to realize picosecond-level and faster time resolution of ultra-high-speed imaging due to the limitation of mechanical shutter speed and the bandwidth of optoelectronic system. At present, although the streak camera of high-speed image converter tube has reached an ultra-high time resolution of 200 fs, it can only realize one-dimensional imaging of the target, and the framing camera can realize two-dimensional imaging, but it is limited by the gating voltage, which further limits the improvement of resolution.

[0003] At present, the ultrafast pulse framing imaging technology based on electro-optic deflection can realize low loss in the imaging process and free modulation of time resolution and spatial distribution by combining multi-pulse sequence and the modulation refractive index deflection of the crystal itself, and can realize ultrafast imaging with low cost, high speed and compact structure. However, the deflection angle of the electro-optic crystal is related to the size structure of the electro-optic crystal and the applied voltage, which leads to a small deflection angle of the existing electro-optic crystal. A small deflection angle of the electro-optic crystal will cause the framing image not to be completely separated and the problem of compressed sensing, which limits the ultrafast resolution of two-dimensional high spatial resolution image, and also challenges the response speed of high-voltage power supply. The industry usually solves the problem of small deflection angle of electro-optic crystal by increasing the deflection angle through rotating mirror or compressed sensing imaging of overlapping beams, but these two ways will reduce the response speed and imaging quality of the system due to the insufficient scanning speed, thereby reducing the accuracy of ultrafast imaging. SUMMARY

[0004] The purpose of the present application is to solve the technical problems of the existing ultrafast pulse framing imaging technology based on electro-optic deflection, that is, the problem of incomplete separation of framing image caused by small deflection angle of electro-optic crystal and the problem of compressed sensing, and the problem of significant reduction of system response speed and imaging quality caused by increasing deflection angle through rotating mirror or compressed sensing imaging of overlapping beams when solving the problem of small deflection angle of electro-optic crystal, and to provide a full solid-state ultrafast electro-optic framing imaging system and an imaging method.

[0005] In order to achieve the above-mentioned purpose, the technical solution provided by the present application is as follows:

[0006] A full solid-state ultrafast electro-optic framing imaging system, characterized in that it comprises a synchronous pulse generator, a signal control unit, a pulse laser, an optical deflection system, a deflection control circuit, a CMOS integral acquisition device and an image processing unit.

[0007] The signal control unit is configured to control the synchronous pulse generator to synchronously generate two groups of timing trigger signals.

[0008] The control signal input ends of the pulse laser and the deflection control circuit are respectively connected to two output ends of the synchronous pulse generator, so as to synchronously trigger the pulse laser and the deflection control circuit by the two groups of timing trigger signals, so that the pulse laser outputs sequence pulse laser and the deflection control circuit generates sequence voltages with different sizes.

[0009] The light deflection system comprises a lithium niobate crystal, an upper electrode array and a lower electrode array; the upper electrode array comprises M triangular upper electrodes and M first ground electrodes, and the lower electrode array comprises M triangular lower electrodes and M second ground electrodes, and M≥2; the triangular upper electrodes, the first ground electrodes, the triangular lower electrodes and the second ground electrodes are all the same in shape and size; the M triangular upper electrodes and the M second ground electrodes are arranged in reverse interlacing on the upper surface of the lithium niobate crystal along the direction of laser transmission, and the M first ground electrodes and the M triangular lower electrodes are arranged in reverse interlacing on the lower surface of the lithium niobate crystal; the M first ground electrodes and the M triangular upper electrodes are in one-to-one correspondence in position, and the M second ground electrodes and the M triangular lower electrodes are in one-to-one correspondence in position.

[0010] The side surface of the lithium niobate crystal is located on the light path of the pulse laser, and the sample to be measured is placed between the pulse laser and the lithium niobate crystal, so that the sequence pulse laser loaded with transient information of the sample to be measured at different moments is sequentially incident into the lithium niobate crystal;

[0011] The triangular upper electrodes and the triangular lower electrodes are respectively connected to the voltage output ends of the deflection control circuit, so as to apply sequence voltages to the lithium niobate crystal, so that the pulse laser passing through the lithium niobate crystal at different moments is deflected at different angles to form multiple deflected lasers;

[0012] The CMOS integration and acquisition device is located on the light path of the multiple deflected lasers, and is configured to acquire the multiple deflected lasers to obtain a framing image of the transient information of the sample to be measured at different moments;

[0013] The input end of the image processing unit is connected to the output end of the CMOS integration and acquisition device, and is configured to analyze and process each framing image to obtain the ultrafast process imaging of the sample to be measured.

[0014] Further, the light deflection system further comprises a first plane mirror and a second plane mirror.

[0015] The first plane mirror and the second plane mirror are sequentially arranged in the light path of the multiple deflected lasers, and the angle between the incident surface of the first plane mirror and the exit surface of the lithium niobate crystal is α, the angle between the incident surface of the second plane mirror and the exit surface of the lithium niobate crystal is 180°-α or 180°-α+β, wherein α is 30°-60°, and the value of β is less than or equal to 15°, so as to realize the preset interval requirement of the multiple deflected lasers for frame imaging after being reflected by the first plane mirror and the second plane mirror.

[0016] The CMOS integral acquisition device is arranged in the light path of the multiple deflected lasers reflected by the second plane mirror.

[0017] The distance between the first plane mirror and the second plane mirror should be such that the light reflected by the first plane mirror and the second plane mirror does not interfere with each other.

[0018] Further, the α is 45°.

[0019] The pulse laser adopts a semiconductor pulse laser.

[0020] The transmittance of the lithium niobate crystal is 370-5000 nm>68%, and the absorption loss is <0.1%.

[0021] Further, the upper surface and the lower surface of the lithium niobate crystal are respectively provided with a silicon dioxide film.

[0022] The triangular upper electrode and the second ground electrode are arranged on the silicon oxide film on the upper surface of the lithium niobate crystal.

[0023] The triangular lower electrode and the first ground electrode are arranged on the silicon oxide film on the lower surface of the lithium niobate crystal.

[0024] Further, the light deflection system further comprises a collimating mirror and a fluoride glass optical fiber arranged between the pulse laser and the sample to be measured in sequence along the transmission direction of the light path.

[0025] Further, the light deflection system further comprises a first take-out electrode, a second take-out electrode, a third take-out electrode and a fourth take-out electrode.

[0026] The M triangular upper electrodes are connected to the voltage output end of the deflection control circuit through the first take-out electrode, and the M triangular lower electrodes are connected to the voltage output end of the deflection control circuit through the second take-out electrode.

[0027] The M second ground electrodes are grounded through the third take-out electrode, and the M first ground electrodes are grounded through the fourth take-out electrode.

[0028] Further, the triangular upper electrode, the first ground electrode, the triangular lower electrode and the second ground electrode are all isosceles triangles.

[0029] In addition, the application further provides a full solid-state ultrafast electro-optic framing imaging method, which is characterized by comprising the following steps.

[0030] Step 1, a full solid-state ultrafast electro-optic framing imaging system is built, and a sample to be measured is placed between a pulsed laser and a lithium niobate crystal, and the sample to be measured is located on an outgoing light path of the pulsed laser.

[0031] Step 2, a signal control unit is used to control a synchronous pulse generator to synchronously generate two time sequence trigger signals at a fixed time, so as to synchronously trigger the pulsed laser and a deflection control circuit; sequence pulsed laser emitted by the pulsed laser sequentially passes through the sample to be measured to load transient information at different moments, and then is incident into the lithium niobate crystal; sequence voltages of different sizes generated by the deflection control circuit are synchronously applied to the lithium niobate crystal through an upper electrode array and a lower electrode array, so that the sequence pulsed laser loaded with the transient information at different moments of the sample to be measured is sequentially deflected when passing through the lithium niobate crystal, and multiple deflected lasers containing the transient information at different moments of the sample to be measured are obtained;

[0032] Step 3, a CMOS integral acquisition device is used to acquire the multiple deflected lasers, so as to obtain framing images of the transient information at different moments of the sample to be measured.

[0033] Step 4, an image processing unit is used to analyze and process the framing images of the transient information at different moments of the sample to be measured, so as to obtain ultrafast process imaging of the sample to be measured.

[0034] Further, step 3 is specifically as follows:

[0035] The included angle between the first plane mirror and the second plane mirror is adjusted to meet preset spacing requirements of framing imaging, and the CMOS integral acquisition device is used to acquire multiple deflected lasers that meet the preset spacing requirements of framing imaging after being reflected by the first plane mirror and the second plane mirror in sequence, so as to obtain the framing images of the transient information at different moments of the sample to be measured.

[0036] Further, step 4 is specifically as follows:

[0037] The image processing unit is used to obtain the ultrafast process imaging of the sample to be measured without deflection through light beam propagation theory inversion, according to the framing images of the transient information at different moments of the sample to be measured, and in combination with voltage deflection angle and displacement characteristics of the lithium niobate crystal.

[0038] The application has the following beneficial effects compared with the prior art:

[0039] 1. The full solid-state ultrafast electro-optic framing imaging system provided by the application adopts lithium niobate crystal with high response, high electro-optic coefficient and low transmission loss as an electro-optic deflection device, and densely arranges an upper electrode array and a lower electrode array on the upper and lower surfaces of the lithium niobate crystal, so that a periodic refractive index distribution is formed in the lithium niobate crystal along the direction of the pulsed laser light, thereby forming a plurality of separated beams emitted at different angles, i.e. the pulsed laser light passing through the lithium niobate crystal at different times is deflected at different angles by applying a sequence voltage to the lithium niobate crystal. The imaging system has the characteristics of high light transmittance and large deflection angle. Compared with the traditional electrical gating, the scanning speed is fast, the repetition frequency is high, and the response speed and imaging quality of the system are ensured on the basis of meeting the deflection angle requirement of the electro-optic crystal.

[0040] 2. Compared with the rotating mirror type framing camera, the full solid-state ultrafast electro-optic framing imaging system provided by the application adopts a semiconductor pulsed laser and lithium niobate crystal based on an upper electrode array and a lower electrode array, effectively reduces the complexity of the system, and has the characteristics of light weight, low cost and large dynamic range measurement. Meanwhile, the core components of the application do not contain liquid or gas, and the use of all solid-state components can ensure that the imaging system is not easily affected by external stress and effectively ensure the stability and reliability of the imaging system.

[0041] 3. The full solid-state ultrafast electro-optic framing imaging system provided by the application can dynamically change the time resolution and the number of framing images based on the real-time timing trigger signal to control the pulse width, the number of pulses of the pulsed laser and the applied voltage of the lithium niobate crystal, and has the advantages of high precision and dynamic adjustment.

[0042] 4. The full solid-state ultrafast electro-optic framing imaging system provided by the application can effectively shorten the imaging distance by arranging a first plane mirror and a second plane mirror behind the lithium niobate crystal, and can adjust the included angle between the first plane mirror and the second plane mirror by adjusting the angle of the first plane mirror or the second plane mirror, thereby meeting the preset spacing requirement of framing imaging.

[0043] 5. The full solid-state ultrafast electro-optic framing imaging method provided by the application is simple, convenient and easy to operate, and effectively ensures the response speed and imaging quality of the system, thereby improving the accuracy of ultrafast imaging. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 It is a principle block diagram of an embodiment of the full solid-state ultrafast electro-optic framing imaging system provided by the application;

[0045] Figure 2 It is a structural schematic block diagram of an embodiment of the full solid-state ultrafast electro-optic framing imaging system provided by the application (the signal control unit is not shown);

[0046] Figure 3 Schematic diagram of the structure of the light deflection system in an embodiment of the present invention (the first plane mirror and the second plane mirror are not shown);

[0047] Figure 4 for Figure 3 A partial perspective enlarged view of the .

[0048] The specific reference numerals are as follows:

[0049] 1-synchronous pulse generator; 2-signal control unit; 3-pulse laser;

[0050] 4 - optical deflection system, 41 - lithium niobate crystal, 42 - upper electrode array, 421 - triangular upper electrode, 422 - first ground electrode, 431 - triangular lower electrode, 432 - second ground electrode, 44 - first plane mirror, 45 - second plane mirror, 46 - first output electrode, 47 - second output electrode, 48 - third output electrode; 49 - fourth output electrode;

[0051] 5-deflection control circuit; 6-CMOS integration acquisition device; 7-image processing unit; 8-collimating mirror; 9-fluoride glass optical fiber. DETAILED DESCRIPTION

[0052] In order to make the advantages and features of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0053] like Figure 1 、 Figure 2 As shown, an all-solid-state ultrafast electro-optical framing imaging system includes a synchronization pulse generator 1, a signal control unit 2, a pulse laser 3, an optical deflection system 4, a deflection control circuit 5, a CMOS integration acquisition device 6 and an image processing unit 7.

[0054] The signal control unit 2 is used to output a ns-level precise delay control signal according to the clock signal generated by the internal signal oscillator generator, so as to control the synchronous pulse generator 1 to synchronously generate two sets of timing trigger signals with extremely narrow pulse widths.

[0055] The control signal inputs of the pulse laser 3 and the deflection control circuit 5 are connected to the two outputs of the synchronization pulse generator 1, respectively. These two timing trigger signals synchronize and trigger the pulse laser 3 and the deflection control circuit 5, causing the pulse laser 3 to output a sequence of laser pulses with equal time intervals and the deflection control circuit 5 to generate a sequence of voltages with varying magnitudes, i.e., a stepped voltage. Synchronization pulse generator 1 utilizes a high-precision, low-disturbance, wide-range synchronization pulse generator, enabling precise delay control between the pulse laser and the optical deflection system 4.

[0056] In this embodiment, pulse laser 3 utilizes a semiconductor pulse laser, which features narrow linewidth, high repetition rate, and short pulses. This reduces optical dispersion during transmission, enabling high temporal resolution and a large number of framing operations. In this embodiment, pulse laser 3 emits visible light with a wavelength of 520 nm, an aperture of 5.6 mm, a repetition rate of 100 MHz, and a pulse width in the nanosecond range, generating a sequence of laser pulses with equal time intervals of 10 nanoseconds. The pulse width and pulse time interval of the laser emitted by pulse laser 3 determine the temporal resolution of the image and the time interval between the framing images. A smaller pulse time interval results in closer time between the detectable framing images.

[0057] like Figure 3 、 Figure 4 As shown, the optical deflection system 4 includes a lithium niobate crystal 41, an upper electrode array 42, a lower electrode array, a first plane mirror 44, and a second plane mirror 45. The lithium niobate crystal 41 has a high spectral transmittance range, with a transmittance of >68% from 370 to 5000 nm and an absorption loss of <0.1%. Silicon oxide films are provided on the upper and lower surfaces of the lithium niobate crystal 41 to improve insulation performance. In this embodiment, the upper electrode array 42 includes 100 triangular upper electrodes 421 and 100 first ground electrodes 422, and the lower electrode array includes 100 triangular lower electrodes 431 and 100 second ground electrodes 432. The triangular upper electrode 421, the first ground electrode 422, the triangular lower electrode 431, and the second ground electrode 432 are all of the same shape and size, preferably an isosceles triangle. In this embodiment, the triangular upper electrode 421 and the triangular lower electrode 431 are copper metal electrodes. 100 triangular upper electrodes 421 and 100 second ground electrodes 432 are arranged in an opposite direction and staggered along the laser transmission direction on the silicon oxide film on the upper surface of the lithium niobate crystal 41, and 100 first ground electrodes 422 and 100 triangular lower electrodes 431 are arranged in an opposite direction and staggered on the silicon oxide film on the lower surface of the lithium niobate crystal 41; the positions of the 100 first ground electrodes 422 and the 100 triangular upper electrodes 421 correspond one-to-one, and the positions of the 100 second ground electrodes 432 and the 100 triangular lower electrodes 431 correspond one-to-one.

[0058] When measuring, the side of the lithium niobate crystal 41 needs to be located on the light path of the pulsed laser 3, and the sample to be measured is placed between the pulsed laser 3 and the lithium niobate crystal 41, that is, the sample to be measured and the lithium niobate crystal 41 are on the same horizontal line with the output aperture of the pulsed laser 3, at this time, the pulsed laser beam can cover the sample to be measured, and after the sequence pulsed laser loads the transient information of the sample to be measured at different times, it is incident into the lithium niobate crystal 41 in turn. At the same time, under the triggering of the timing trigger signal, the sequence voltages of different sizes generated in the deflection control circuit 5, that is, the step voltages, are applied to the lithium niobate crystal 41 through the triangular upper electrode 421 and the triangular lower electrode 431, so that the pulsed laser passing through the lithium niobate crystal 41 at different times is deflected at different field strengths, and a plurality of deflected lasers are formed.

[0059] The light path of the sequence pulsed laser is defined as the y-axis, the direction perpendicular to the y-axis in the horizontal plane is the x-axis, and the direction perpendicular to the xy plane is the z-axis. In the present application, the lithium niobate crystal 41 is a z-cut cuboid, which means that the z-axis is the height direction of the lithium niobate crystal 41, and the thickness of the lithium niobate crystal 41 needs to exceed the diameter of at least one pulsed laser. The 100 triangular upper electrodes 421 are connected to the voltage output end of the deflection control circuit 5 through the first lead-out electrode 46, and the 100 first ground electrodes 422 are grounded through the fourth lead-out electrode 49, so that a positive voltage with a positive refractive change rate is formed between the triangular upper electrode 421 and the corresponding first ground electrode 422. At the same time, the 100 triangular lower electrodes 431 are connected to the voltage output end of the deflection control circuit 5 through the second lead-out electrode 47, and the 100 second ground electrodes 432 are grounded through the third lead-out electrode 48, so that a negative voltage with a negative refractive change rate is formed between the triangular lower electrode 431 and the corresponding second ground electrode 432. When sequence voltages of different sizes are applied to the lithium niobate crystal 41, positive and negative voltages are periodically distributed in the y-axis direction, and correspondingly, the refractive index is also periodically distributed in the y-axis direction, thereby realizing a periodic refractive index distribution similar to a triangular prism. The specific deflection principle is as follows: since the field strength of the lithium niobate crystal 41 in the z-axis direction is constant in an ideal case, the refractive index at different height positions is constant, so after applying a voltage along the z-axis direction of the lithium niobate crystal 41, the boundary of each electrode region in the xy plane will produce a refractive index difference; when the pulsed laser is vertically incident on the side of the crystal, at this time the beam is perpendicular to the zx plane, and when it is further incident on the electrode region, the boundary surface between the electrode region and the non-electrode region is a slope surface perpendicular to the xy plane, at this time the beam and the slope surface form a certain angle, at this time the x-axis and y-axis directions are both oblique incidence, and angle deflection occurs in the xy plane.

[0060] Since a positive voltage is formed between each triangular upper electrode 421 and the corresponding first ground electrode 422, a negative voltage is formed between each triangular lower electrode 431 and the corresponding second ground electrode 432, and no electrode is arranged on the side surface, when a sequence pulse laser carrying the transient information of the sample at different time is incident into the lithium niobate crystal 41, the sequence pulse laser propagates along the y-axis direction, effectively avoiding the birefringence effect. Since the laser can maintain its Gaussian shape and circularity when propagating in the lithium niobate crystal 41, the propagation through the lithium niobate crystal 41 has little effect on the beam quality.

[0061] When the energy of the sample to be measured is large or its transient process is dangerous, the sample to be measured needs to be arranged at a position far away from the pulse laser 3, so that the collimating mirror 8 and the fluoride glass fiber 9 are arranged in sequence along the light path transmission direction between the pulse laser 3 and the sample to be measured. Under the premise of safety, the pulse laser is delivered to the surface of the sample to be measured through the collimating mirror 8 and the fluoride glass fiber 9. When the surface of the sample to be measured is large, a beam expander is also needed behind the collimating mirror 8 to increase the illumination area of the pulse laser.

[0062] The first plane mirror 44 and the second plane mirror 45 are used for further position separation of the output light. The first plane mirror 44 and the second plane mirror 45 are arranged in sequence on the light path of the multi-beam deflected laser, the angle between the incident surface of the first plane mirror 44 and the exit surface of the lithium niobate crystal 41 is α, and the angle between the incident surface of the second plane mirror 45 and the exit surface of the lithium niobate crystal 41 is 180°-α or 180°-α+β, where α is usually 30°-60°, preferably 45°, and β is less than or equal to 15°, i.e. the first plane mirror 44 and the second plane mirror 45 are arranged in parallel, or a certain angle is arranged between the first plane mirror 44 and the second plane mirror 45, which is used to make the multi-beam deflected laser meet the preset spacing requirements of the framing imaging after being reflected by the first plane mirror 44 and the second plane mirror 45 in sequence. At the same time, the distance between the first plane mirror 44 and the second plane mirror 45 should be such that the reflected light does not interfere with each other. Since different pulse lasers arrive at the first plane mirror 44 at different times and positions, the distance of the reflected light propagating between the two mirror surfaces is different, which increases the position difference of the light reaching the surface of the second plane mirror 45. When a certain angle is arranged between the first plane mirror 44 and the second plane mirror 45, the spatial position deflection difference will further increase. In actual use, the angle of the first plane mirror 44 or the second plane mirror 45 can be adjusted by the adjustable knob, and then the angle between the first plane mirror 44 and the second plane mirror 45 is adjusted to meet the preset spacing requirements of the framing imaging.

[0063] The deflection control circuit 5 is composed of a high-voltage power module. Since the lithium niobate crystal 41 has a good linear electro-optic effect, and a voltage is applied to the lithium niobate crystal 41 along the z-axis direction, the electro-optic coefficient and the corresponding refractive index change are large. To achieve higher time resolution and framing number, the deflection capability of the lithium niobate crystal 41 is particularly important. Therefore, the deflection control circuit 5 applies a voltage to the multiple arrayed triangular upper electrodes 421 and triangular lower electrodes 431, so as to realize periodic voltage distribution.

[0064] The specific process of generating sequence voltages with different sizes in the deflection control circuit 5 is as follows: under the triggering of the first trigger signal of the timing trigger signal, as the pulsed laser enters the lithium niobate crystal 41, the deflection control circuit 5 applies a kV-level voltage on the lithium niobate crystal 41 at the same time; when the next trigger signal arrives, as the pulsed laser enters the lithium niobate crystal 41, the deflection control circuit 5 applies a voltage different from the voltage at the previous time on the lithium niobate crystal 41 at the same time, and the voltage size can be a multiple of the voltage at the previous time. In this way, the deflection control circuit 5 applies a step voltage to the lithium niobate crystal 41 under the triggering of multiple different timing signals. By controlling the change of the voltage, the adjustability of the beam angle can be realized, and the spacing of the framing image can be adjusted; the cyclic output of the step voltage can realize the cyclic scanning integration of the light beam.

[0065] The CMOS integration and collection device 6 is located on the light path of the multiple deflected lasers reflected by the second plane mirror, and is used for collecting the multiple deflected lasers to obtain the framing images of the transient information of the sample at different times. In this embodiment, the CMOS integration and collection device 6 adopts a scientific sCMOS camera, which has the advantages of low power consumption, low noise, high readout rate, high dynamic range, low cost, compactness and high integration, but the frame rate is low. The sCMOS camera can realize fast collection and imaging of the outgoing light of the light deflection system 4, and can distribute the images at different times on the entire collection plane. In this application, the resolution and pixel size of the sCMOS camera are required to be high. In order to realize multiple imaging of pulsed laser and improve the spatial resolution, the resolution of the sCMOS camera needs to be 2048x2048, and the pixel size needs to be 6.5um. When the frame rate of the sCMOS camera is increased, multiple framing imaging can be realized for each frame, and the system can realize faster imaging by increasing the multiple cycle rate scanning.

[0066] The input end of the image processing unit 7 is connected to the output end of the CMOS integration and collection device 6 through a high-speed data line, and is used for analyzing and processing each framing image to obtain the ultrafast process imaging of the sample to be measured.

[0067] The image processing system cuts and compares the multi-divisional images, and determines the corresponding image time according to the arrangement position. Since the image information of the light beam is displaced in space with the angle shift in the electro-optical deflection process, there is a propagation loss and distance deviation, so it is necessary to correct and reconstruct the deflection of the lithium niobate crystal 41. According to the voltage deflection angle and displacement characteristics of the lithium niobate crystal 41, the ultrafast process imaging of the undeviated sample can be obtained by the light beam propagation theory.

[0068] In order to meet the detection needs of ultrafast events in multiple scenes, the time resolution and time range of detection in the present application can be adjusted according to actual conditions. The time resolution can be dynamically changed by controlling and changing the output width of the pulse laser through real-time timing trigger signals. The event time range collected can be dynamically adjusted by changing the time interval of the pulse laser. At the same time, according to the image information collected by the CMOS integral acquisition device 6, the working parameters of the system can be adjusted in real time to achieve the appropriate output beam condition.

[0069] In addition, the number of divisional images of the present application can be adjusted. Specifically, the time interval and the number of pulses of the pulse laser are adjusted through the timing trigger signal control, and the deflection angle of the pulse laser is controlled through the deflection control circuit 5, and the included angle of the first plane mirror 44 and the second plane mirror 45 is adjusted to control the deflection interval distance of the divisional images, so that the number of detection time of ultrafast events can be adjusted, and different numbers of divisional images can be obtained on the sCOMS camera. It can be seen that the voltage control of the present application makes the adjustment of the number of divisional images more convenient.

[0070] Since the deflection angle θ of the outgoing light and the incident light of the light deflection system 4 is:

[0071]

[0072] Wherein, n o is the refractive index of the lithium niobate crystal 41, l is the length of the lithium niobate crystal 41, r is the electro-optic coefficient of the lithium niobate crystal 41, ω is the aperture of the lithium niobate crystal 41, i.e. the optical clear aperture, which refers to the region of the lithium niobate crystal 41 that effectively transmits or transmits the light beam. In actual size, it can be understood as the width and height of the crystal, E Z is the electric field in the z-axis direction.

[0073] The spatial resolution R is the total number of distinguishable points, which can be defined as R=θ / α, and α is the angular resolution, which is α=1.22λ / ω under the Rayleigh criterion, and λ is the wavelength of the laser pulse, so:

[0074]

[0075] Wherein, V is the voltage applied to the lithium niobate crystal 41, and d is the height of the lithium niobate crystal 41.

[0076] It can be seen that the spatial resolution R has a relationship with the voltage V applied on the lithium niobate crystal 41, the aperture ω of the lithium niobate crystal 41, the length l of the lithium niobate crystal 41, and the refractive index n of the lithium niobate crystal 41. o

[0077] In the specific test, in order to ensure the stability of each component, the anti-vibration case A and the anti-vibration case B are further arranged in the embodiment. The pulse laser 3, the collimating mirror 8 and the fluoride glass fiber 9 are connected in sequence through the tail fiber port and then fixed in the anti-vibration case A through a support. The synchronous pulse generator 1 is connected with the pulse laser 3 through a wire and fixed in the anti-vibration case A. The anti-vibration case A serves as a laser output module, and the laser output port serves as a bare port. The lithium niobate crystal 41, the first plane mirror 44, the second plane mirror 45, the deflection control circuit 5 and the CMOS integral acquisition device 6 are respectively fixed in the anti-vibration case B. The deflection control circuit 5 is connected with the synchronous pulse generator 1 in the anti-vibration case A, the first lead-out electrode 46 and the second lead-out electrode 47 of the lithium niobate crystal 41 through wires respectively, so as to realize signal transmission. At the same time, the light transmission surface (side surface) of the lithium niobate crystal 41 is exposed on the surface of the case, so that the pulse laser emitted from the anti-vibration case A can be incident after passing through the transient event of the sample to be tested.

[0078] The application further provides a full-solid-state ultrafast electro-optic framing imaging method, which specifically comprises the following steps.

[0079] Step 1, a full-solid-state ultrafast electro-optic framing imaging system is built, the synchronous pulse generator 1 is initialized and set, the sample to be tested is placed between the pulse laser 3 and the lithium niobate crystal 41, and the sample to be tested is located on the light path of the pulse laser 3.

[0080] ​Step 2, the synchronization pulse generator 1 is controlled by the signal control unit 2 to synchronously generate two time sequence trigger signals at a fixed time, so as to synchronously trigger the pulse laser 3 and the deflection control circuit 5; the sequence pulse laser output by the pulse laser 3 at the same time interval is sequentially incident to the to-be-detected sample after passing through the collimating mirror 8 and the fluoride glass optical fiber 9, and the pulse laser at different moments records the transient information of the to-be-detected sample at different moments; after the transient information of the to-be-detected sample at different moments is loaded, the sequence pulse laser is incident to the inside of the lithium niobate crystal 41 again. The sequence voltage of different sizes generated by the deflection control circuit 5 is synchronously applied to the lithium niobate crystal 41 through the upper electrode array 42 and the lower electrode array, so that the sequence pulse laser loaded with the transient information of the to-be-detected sample at different moments is deflected at different angles when passing through the lithium niobate crystal 41, and a plurality of separated beams deflected at different angle positions are formed on the xy plane, that is, a plurality of deflected lasers containing the transient information of the to-be-detected sample at different moments are obtained. The plurality of deflected lasers change with the time sequence system control, and it needs to be pointed out that the time sequence trigger signal of the synchronization pulse generator 1 and the applied voltage of the deflection control circuit 5 can be adjusted, so as to achieve real-time adjustment according to different scenes and conditions, and realize adjustable time resolution and number of frames.

[0081] Step 3, the plurality of deflected lasers are sequentially reflected by the first plane mirror 44 and the second plane mirror 45 and then incident to the CMOS integral acquisition device 6, and in the process, the preset spacing requirement of frame imaging is realized by adjusting the included angle between the first plane mirror 44 and the second plane mirror 45. After the adjustment is completed, the CMOS integral acquisition device 6 acquires the plurality of deflected lasers and obtains the frame images of the transient information of the to-be-detected sample at different moments.

[0082] Step 4, the image processing unit 7 obtains the ultrafast process imaging of the to-be-detected sample without deflection by means of the beam propagation theory inversion according to the frame images of the transient information of the to-be-detected sample at different moments and in combination with the voltage deflection angle and displacement characteristics of the lithium niobate crystal 41.

[0083] The above description is only used to illustrate the technical solutions of the present application, and is not a limitation. For ordinary skilled persons in the art, the specific technical solutions recorded in the above embodiments can be modified, or some technical features can be replaced, and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions protected by the present application.

Claims

1. A full solid-state ultrafast electro-optic framing imaging system, characterized in that: it comprises a synchronous pulse generator (1), a signal control unit (2), a pulse laser (3), an optical deflection system (4), a deflection control circuit (5), a CMOS integral acquisition device (6) and an image processing unit (7); the signal control unit (2) is used for controlling the synchronous pulse generator (1) to synchronously generate two groups of time sequence trigger signals; the control signal input ends of the pulse laser (3) and the deflection control circuit (5) are respectively connected to the two output ends of the synchronous pulse generator (1), which are used for synchronously timing triggering the pulse laser (3) and the deflection control circuit (5) through the two groups of time sequence trigger signals, so that the pulse laser (3) outputs sequence pulse laser and the deflection control circuit (5) generates sequence voltages with different sizes; the optical deflection system (4) comprises a lithium niobate crystal (41), an upper electrode array (42) and a lower electrode array; the upper electrode array (42) comprises M triangular upper electrodes (421) and M first ground electrodes (422), and the lower electrode array comprises M triangular lower electrodes (431) and M second ground electrodes (432), and M≥2; the triangular upper electrode (421), the first ground electrode (422), the triangular lower electrode (431) and the second ground electrode (432) are all the same in shape and size; the M triangular upper electrodes (421) and the M second ground electrodes (432) are reversely staggered on the upper surface of the lithium niobate crystal (41) along the laser transmission direction, and the M first ground electrodes (422) and the M triangular lower electrodes (431) are reversely staggered on the lower surface of the lithium niobate crystal (41); the M first ground electrodes (422) and the M triangular upper electrodes (421) correspond to each other in position, and the M second ground electrodes (432) and the M triangular lower electrodes (431) correspond to each other in position; the side surface of the lithium niobate crystal (41) is located on the light path of the pulse laser (3), and a sample to be measured is placed between the pulse laser (3) and the lithium niobate crystal (41), so that the sequence pulse laser loaded with transient information of the sample to be measured at different times enters the lithium niobate crystal (41) in turn; the triangular upper electrode (421) and the triangular lower electrode (431) are respectively connected to the voltage output end of the deflection control circuit (5), which is used for applying sequence voltages to the lithium niobate crystal (41), so that the pulse laser passing through the lithium niobate crystal (41) at different times is deflected at different angles to form a plurality of deflected lasers; the CMOS integral acquisition device (6) is located on the light path of the plurality of deflected lasers, which is used for collecting the plurality of deflected lasers to obtain framing images of the transient information of the sample to be measured at different times; and the input end of the image processing unit (7) is connected to the output end of the CMOS integral acquisition device (6), which is used for analyzing and processing each framing image to obtain the ultrafast process imaging of the sample to be measured.

2. The full solid-state ultrafast electro-optic framing imaging system according to claim 1, characterized in that: the optical deflection system (4) further comprises a first plane mirror (44) and a second plane mirror (45). ​ ​ ​ ​ ​ ​ ​ ​ ​ The first plane mirror (44) and the second plane mirror (45) are sequentially arranged in the light path of the multiple deflected lasers, and the angle between the incident surface of the first plane mirror (44) and the exit surface of the lithium niobate crystal (41) is α, the angle between the incident surface of the second plane mirror (45) and the exit surface of the lithium niobate crystal (41) is 180°-α or 180°-α+β, wherein α is 30°-60°, and β is less than or equal to 15°, so that the multiple deflected lasers can be reflected by the first plane mirror (44) and the second plane mirror (45) to achieve the preset spacing requirement of the framing imaging; The CMOS integral acquisition device (6) is arranged in the light path of the multiple deflected lasers reflected by the second plane mirror (45); The distance between the first plane mirror (44) and the second plane mirror (45) should be such that the light reflected by the first plane mirror (44) and the second plane mirror (45) does not interfere with each other.

3. The all-solid-state ultrafast electro-optical framing imaging system according to claim 2, characterized in that: The α is 45°. The pulse laser (3) is a semiconductor pulse laser. The transmittance of the lithium niobate crystal (41) is 370-5000 nm>68%, and the absorption loss is <0.1%.

4. The all-solid-state ultrafast electro-optical framing imaging system according to any one of claims 1-3, characterized in that: The upper surface and the lower surface of the lithium niobate crystal (41) are respectively provided with a silicon dioxide film. The triangular upper electrode (421) and the second ground electrode (432) are arranged on the silicon oxide film on the upper surface of the lithium niobate crystal (41). The triangular lower electrode (431) and the first ground electrode (422) are arranged on the silicon oxide film on the lower surface of the lithium niobate crystal (41).

5. The all-solid-state ultrafast electro-optical framing imaging system according to claim 4, characterized in that: It further comprises a collimating mirror (8) and a fluoride glass optical fiber (9) arranged in sequence between the pulse laser (3) and the sample to be measured along the light path transmission direction.

6. The all-solid-state ultrafast electro-optical framing imaging system according to claim 5, characterized in that: The light deflection system (4) further comprises a first take-out electrode (46), a second take-out electrode (47), a third take-out electrode (48), and a fourth take-out electrode (49). The M triangular upper electrodes (421) are connected to the voltage output end of the deflection control circuit (5) through the first take-out electrode (46), and the M triangular lower electrodes (431) are connected to the voltage output end of the deflection control circuit (5) through the second take-out electrode (47). The M second ground electrodes (432) are grounded through the third take-out electrode (48), and the M first ground electrodes (422) are grounded through the fourth take-out electrode (49).

7. The all-solid-state ultrafast electro-optical framing imaging system according to claim 6, characterized in that: The triangular upper electrode (421), the first ground electrode (422), the triangular lower electrode (431), and the second ground electrode (432) are all isosceles triangles.

8. An all-solid-state ultrafast electro-optic framing imaging method, characterized by, The method comprises the following steps: Step 1, set up a full solid-state ultrafast electro-optic framing imaging system according to any one of claims 1-7, place the sample to be tested between the pulsed laser (3) and the lithium niobate crystal (41), and make the sample to be tested on the light path of the pulsed laser (3); Step 2, control the synchronous pulse generator (1) to generate two time sequence trigger signals at a fixed time through the signal control unit (2) to synchronously trigger the pulsed laser (3) and the deflection control circuit (5); the sequence pulsed laser emitted by the pulsed laser (3) sequentially enters the lithium niobate crystal (41) after loading the transient information of the sample to be tested at different times; the sequence voltage of different sizes generated by the deflection control circuit (5) is synchronously applied to the lithium niobate crystal (41) through the upper electrode array (42) and the lower electrode array, so that the sequence pulsed laser loaded with the transient information of the sample to be tested at different times realizes deflection at different angles when it sequentially passes through the lithium niobate crystal (41), and multiple deflected lasers containing the transient information of the sample to be tested at different times are obtained; Step 3, the CMOS integral acquisition device (6) acquires multiple deflected lasers to obtain the framing images of the transient information of the sample to be tested at different times; Step 4, the image processing unit (7) analyzes and processes the framing images of the transient information of the sample to be tested at different times to obtain the ultrafast process imaging of the sample to be tested.

9. The all-solid-state ultrafast electro-optic framing camera method of claim 8, wherein, Step 3 is specifically: Adjust the included angle between the first plane mirror (44) and the second plane mirror (45) to meet the preset spacing requirements of framing imaging, and the CMOS integral acquisition device (6) acquires multiple deflected lasers that meet the preset spacing requirements of framing imaging after being reflected by the first plane mirror (44) and the second plane mirror (45) in sequence to obtain the framing images of the transient information of the sample to be tested at different times.

10. The all-solid-state ultrafast electro-optic framing camera method of claim 9, wherein, Step 4 is specifically: The image processing unit (7) obtains the ultrafast process imaging of the sample to be tested without deflection through the light beam propagation theory inversion according to the framing images of the transient information of the sample to be tested at different times and in combination with the voltage deflection angle and displacement characteristics of the lithium niobate crystal (41).

Images