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

Abstract

The invention provides an all-solid-state ultrafast electro-optical framing imaging system and an imaging method, which are used for solving the problems that framing images are not completely separated and compressed sensing is caused due to the fact that the deflection angle of an electro-optical crystal is small in the existing ultrafast pulse framing imaging technology based on electro-optical deflection. And the technical problem that the system response speed and the imaging quality are obviously reduced when the problem that the deflection angle of the electro-optical crystal is small is solved through rotating mirror type deflection angle increasing or compressed sensing imaging of overlapped light beams. According to the all-solid-state ultrafast electro-optical framing imaging system, the lithium niobate crystal is adopted as an electro-optical deflection device, and the upper electrode array and the lower electrode array are arranged on the upper surface and the lower surface of the lithium niobate crystal, so that periodic refractive index distribution is formed in the lithium niobate crystal in the pulse laser emitting direction; the pulse laser passing at different moments can deflect at different angles, and the response speed and the imaging quality of the system are ensured on the basis of meeting the deflection angle requirement of the electro-optical crystal.

Description

Technical Field

[0001] The invention relates to ultrafast imaging technology, and in particular to an all-solid-state ultrafast electro-optical framing imaging system and an imaging method. Background Art

[0002] Ultrafast imaging technology has evolved from traditional high-speed photography technology and has gradually achieved higher resolution and accuracy. Traditional high-speed photography technologies such as digital high-speed image converters are limited by mechanical shutter speeds and optoelectronic system bandwidth limitations, making it difficult to achieve ultra-high-speed imaging with picosecond and faster time resolution. At present, although the streak camera of the high-speed image converter has achieved an ultra-high time resolution of 200fs, it can only achieve one-dimensional imaging of the target, and although the framing camera can achieve two-dimensional imaging, it is limited by the gate voltage, which in turn limits the improvement of resolution.

[0003] At present, the ultrafast pulse framing imaging technology based on electro-optical deflection, combined with a multi-pulse sequence and the crystal's own modulated refractive index deflection, can achieve low loss in the imaging process and the characteristics of free modulation time resolution and spatial distribution, and can achieve ultrafast imaging with a low-cost, high-speed and compact structure. However, since the deflection angle of the electro-optical crystal is related to the size structure and applied voltage of the electro-optical crystal, the existing electro-optical crystal has a small deflection angle. The small deflection angle of the electro-optical crystal will lead to incomplete separation of the framed image and compressed sensing problems, which limits the ultrafast resolution of two-dimensional high-spatial resolution images and also poses a challenge to the response speed of the high-voltage voltage source. The industry usually solves the problem of the small deflection angle of the electro-optical crystal by increasing the deflection angle by rotating the mirror or by compressed sensing imaging of overlapping beams. However, due to the insufficient scanning speed of these two methods, the response speed and imaging quality of the system are significantly reduced, thereby reducing the accuracy of ultrafast imaging. Summary of the invention

[0004] The purpose of the present invention is to solve the problems of incomplete separation of framed images and compressed sensing caused by the small deflection angle of the electro-optical crystal in the existing ultrafast pulse framing imaging technology based on electro-optical deflection, as well as the technical problem of significantly reduced system response speed and imaging quality when the problem of the small deflection angle of the electro-optical crystal is solved by increasing the deflection angle by a rotating mirror or compressive sensing imaging of overlapping light beams, and to provide an all-solid-state ultrafast electro-optical framing imaging system and imaging method.

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

[0006] An all-solid-state ultrafast electro-optical framing imaging system, which is special in that it includes a synchronous pulse generator, a signal control unit, a pulse laser, an optical deflection system, a deflection control circuit, a CMOS integration acquisition device and an image processing unit;

[0007] The signal control unit is used to control the synchronization pulse generator to synchronously generate two sets of timing trigger signals;

[0008] The control signal input ends of the pulse laser and the deflection control circuit are respectively connected to the two output ends of the synchronous pulse generator, and are used to synchronously and timingly trigger the pulse laser and the deflection control circuit through two sets of timing trigger signals, so that the pulse laser outputs a sequence of pulse lasers and the deflection control circuit generates sequence voltages of different sizes;

[0009] The optical 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, M≥2; the triangular upper electrode, the first ground electrode, the triangular lower electrode and the second ground electrode are all the same in shape and size; the M triangular upper electrodes and the M second ground electrodes are arranged in an opposite direction and staggered on the upper surface of the lithium niobate crystal along the laser transmission direction, and the M first ground electrodes and the M triangular lower electrodes are arranged in an opposite direction and staggered on the lower surface of the lithium niobate crystal; the positions of the M first ground electrodes and the M triangular upper electrodes correspond one-to-one, and the positions of the M second ground electrodes and the M triangular lower electrodes correspond one-to-one;

[0010] The side of the lithium niobate crystal is located on the outgoing light path of the pulse laser, and the sample to be tested is placed between the pulse laser and the lithium niobate crystal, so that the sequence of pulse lasers is loaded with transient information of the sample to be tested at different times and then incident into the lithium niobate crystal in sequence;

[0011] The triangular upper electrode and the triangular lower electrode are respectively connected to the voltage output end of the deflection control circuit, and are used to apply a sequence voltage to the lithium niobate crystal, so that the pulsed laser passing through the lithium niobate crystal at different times can be deflected at different angles to form multiple deflected laser beams;

[0012] The CMOS integral acquisition device is located on the optical path of multiple deflected laser beams and is used to acquire multiple deflected laser beams to obtain the framed images of transient information of the sample to be tested at different times;

[0013] The input end of the image processing unit is connected to the output end of the CMOS integral acquisition device, and is used to analyze and process each frame image to obtain ultrafast process imaging of the sample to be tested.

[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 located on the optical path of the multiple deflected laser beams, and the angle between the incident surface of the first plane mirror and the exit surface of the lithium niobate crystal is α, and 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 β is less than or equal to 15°, so as to enable the multiple deflected laser beams to achieve the preset spacing requirement of frame imaging after being sequentially reflected by the first plane mirror and the second plane mirror;

[0016] The CMOS integral acquisition device is located on the optical path of the multiple deflected laser beams after being reflected by the second plane mirror;

[0017] The distance between the first plane mirror and the second plane mirror is such that the lights reflected by the first plane mirror 44 and the second plane mirror do not interfere with each other.

[0018] Further, said α=45°;

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

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

[0021] Furthermore, 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 grounding electrode are arranged on the silicon oxide film on the lower surface of the lithium niobate crystal.

[0024] Furthermore, it also includes a collimator and a fluoride glass optical fiber which are sequentially arranged between the pulse laser and the sample to be measured along the light transmission direction.

[0025] Furthermore, the light deflection system further comprises a first output electrode, a second output electrode, a third output electrode and a fourth output electrode;

[0026] The M triangular upper electrodes are connected to the voltage output terminal of the deflection control circuit through the first output electrode, and the M triangular lower electrodes are connected to the voltage output terminal of the deflection control circuit through the second output electrode;

[0027] The M second grounding electrodes are grounded via the third lead-out electrode, and the M first grounding electrodes are grounded via the fourth lead-out electrode.

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

[0029] In addition, the present invention also provides an all-solid-state ultrafast electro-optical framing imaging method, which is special in that it comprises the following steps:

[0030] Step 1, constructing the above-mentioned all-solid-state ultrafast electro-optical framing imaging system, placing the sample to be tested between the pulse laser and the lithium niobate crystal, and making the sample to be tested located on the outgoing light path of the pulse laser;

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

[0032] Step 3: The CMOS integral acquisition device collects multiple deflected laser beams to obtain the framed images of the transient information of the sample to be tested at different times;

[0033] Step 4: the image processing unit analyzes and processes the framed images of the transient information of the sample to be tested at different times to obtain ultrafast process imaging of the sample to be tested.

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

[0035] The angle between the first plane mirror and the second plane mirror is adjusted to meet the preset spacing requirement of the framing imaging. The CMOS integral acquisition device collects multiple deflected laser beams that meet the preset spacing requirement of the framing imaging after being reflected by the first plane mirror and the second plane mirror in sequence, and obtains the framing images of the transient information of the sample to be tested at different times.

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

[0037] The image processing unit obtains ultrafast process imaging of the undeflected sample under test by inverting the beam propagation theory based on the framed images of the transient information of the sample under test at different times and the voltage deflection angle and displacement characteristics of the lithium niobate crystal.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] 1. The present invention provides an all-solid-state ultrafast electro-optical framing imaging system, which uses a lithium niobate crystal with high responsiveness, high electro-optic coefficient and low transmission loss as an electro-optical 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 pulse laser emission direction, thereby forming a plurality of separated light beams emitted at different angles, that is, applying a sequence voltage to the lithium niobate crystal so that the pulse laser passing through the lithium niobate crystal at different times can achieve different angles of deflection. The imaging system of the present invention has the characteristics of high light transmittance and large deflection angle. Compared with traditional electrical gating, the present invention has a fast scanning speed and a high repetition frequency, and ensures the response speed and imaging quality of the system on the basis of meeting the deflection angle requirements of the electro-optical crystal.

[0040] 2. The present invention provides an all-solid-state ultrafast electro-optical framing imaging system. Compared with a rotating mirror framing camera, the present invention adopts a semiconductor pulse laser and a lithium niobate crystal based on an upper electrode array and a lower electrode array, which effectively reduces the complexity of the system and makes it lightweight, low-cost, and has the characteristics of large dynamic range measurement. At the same time, the core components of the present invention 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, etc., effectively ensuring the stability and reliability of the imaging system.

[0041] 3. The present invention provides an all-solid-state ultrafast electro-optical framing imaging system, which controls the pulse width and pulse number of the pulse laser and the applied voltage of the lithium niobate crystal based on a real-time timing trigger signal, and can dynamically change the time resolution and the number of framing images, and has the advantages of high precision and dynamic adjustment.

[0042] 4. The present invention provides an all-solid-state ultrafast electro-optical framing imaging system, which can effectively shorten the imaging distance by arranging a first plane mirror and a second plane mirror behind a lithium niobate crystal. At the same time, the angle of the first plane mirror or the second plane mirror can be adjusted, thereby adjusting the angle between the first plane mirror and the second plane mirror to achieve the preset spacing requirement of framing imaging.

[0043] 5. The all-solid-state ultrafast electro-optical framing imaging method provided by the present invention is simple, convenient and easy to operate, and effectively guarantees the response speed and imaging quality of the system, thereby improving the accuracy of ultrafast imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a principle block diagram of an embodiment of an all-solid-state ultrafast electro-optical framing imaging system of the present invention;

[0045] Figure 2 It is a structural schematic block diagram of an embodiment of an all-solid-state ultrafast electro-optical framing imaging system of the present invention (a 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-light 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-collimator; 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 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 integration acquisition device 6 and an image processing unit 7.

[0054] The signal control unit 2 is used to output ns-level precise delay control signals 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 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 to synchronously trigger the pulse laser 3 and the deflection control circuit 5 through two sets of timing trigger signals, so that the pulse laser 3 outputs a sequence of pulse lasers with the same time interval, and the deflection control circuit 5 generates sequence voltages of different sizes, that is, generates a step-shaped voltage. The synchronous pulse generator 1 adopts a high-precision, low-disturbance, and wide-range synchronous pulse generator, which can realize accurate delay control of the pulse laser and the optical deflection system 4.

[0056] In this embodiment, the pulse laser 3 adopts a semiconductor pulse laser, which has the characteristics of narrow line width, high repetition rate, and short pulse. The optical dispersion effect is low during the transmission process, and high time resolution and multiple framing numbers can be achieved. In this embodiment, the pulse laser 3 emits visible light with a wavelength of 520nm, the aperture of the pulse laser 3 is 5.6mm, the repetition frequency is 100MHz, the pulse width is ns level, and a sequence of pulse lasers with the same time interval of 10ns is generated. Among them, the pulse width and pulse time interval of the laser emitted by the pulse laser 3 determine the time resolution of the image and the time interval of the framing image. When the pulse time interval is smaller, the detectable framing image time is closer.

[0057] like Figure 3 , Figure 4 As shown, the light 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 370-5000nm>68% and an absorption loss of <0.1%. The upper surface and the lower surface of the lithium niobate crystal 41 are respectively provided with a silicon oxide film to improve the insulation performance. In this embodiment, the upper electrode array 42 includes 100 triangular upper electrodes 421 and 100 first grounding electrodes 422, and the lower electrode array includes 100 triangular lower electrodes 431 and 100 second grounding electrodes 432. The triangular upper electrode 421, the first grounding electrode 422, the triangular lower electrode 431 and the second grounding electrode 432 are all the same in shape and size, and their shape is 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 grounding electrodes 432 are arranged on the silicon oxide film on the upper surface of the lithium niobate crystal 41 in an inversely staggered manner along the laser transmission direction, and 100 first grounding electrodes 422 and 100 triangular lower electrodes 431 are arranged on the silicon oxide film on the lower surface of the lithium niobate crystal 41 in an inversely staggered manner; the positions of the 100 first grounding electrodes 422 and the 100 triangular upper electrodes 421 correspond one-to-one, and the positions of the 100 second grounding electrodes 432 and the 100 triangular lower electrodes 431 correspond one-to-one.

[0058] During measurement, the side of the lithium niobate crystal 41 needs to be located on the exit optical path of the pulse laser 3, and the sample to be measured needs to be placed between the pulse laser 3 and the lithium niobate crystal 41. Even if the sample to be measured and the lithium niobate crystal 41 are on the same horizontal line as the output aperture of the pulse laser 3, at this time, the pulse laser beam surface can just cover the sample to be measured, so that the sequence pulse laser is loaded with transient information of the sample to be measured at different times, and then sequentially incident into the lithium niobate crystal 41. 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 voltage, are applied to the lithium niobate crystal 41 through the triangular upper electrode 421 and the triangular lower electrode 431, so that the pulse lasers passing through the lithium niobate crystal 41 at different times are subjected to electro-optical angle deflection under different field strengths, forming multiple deflected laser beams.

[0059] The optical path of the sequence pulse laser is defined as the y-axis, the direction perpendicular to the y-axis on the horizontal plane is the x-axis, and the direction perpendicular to the xy plane is the z-axis. In the present invention, 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 pulse laser. 100 triangular upper electrodes 421 are connected to the voltage output end of the deflection control circuit 5 through the first output electrode 46, and 100 first grounding electrodes 422 are grounded through the fourth output 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 grounding electrode 422; at the same time, 100 triangular lower electrodes 431 are connected to the voltage output end of the deflection control circuit 5 through the second output electrode 47, and 100 second grounding electrodes 432 are grounded through the third output 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 grounding electrode 432. When sequence voltages of different magnitudes are applied to the lithium niobate crystal 41, the positive and negative voltages are periodically distributed in the y-axis direction, and accordingly, the refractive index is also periodically distributed in the y-axis direction, thereby realizing a periodic refractive index distribution similar to that of 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 under ideal conditions, the refractive index at different heights is constant. Therefore, after applying voltage along the Z-axis direction of the lithium niobate crystal 41, a refractive index difference will occur at the boundary of each electrode region in the xy plane; when the pulsed laser is incident vertically on the side of the crystal, the light beam is perpendicular to the zx plane. When it is further incident on the electrode region, the interface between the electrode region and the non-electrode region is an inclined plane perpendicular to the xy plane. At this time, there is a certain angle between the light beam and the inclined plane. At this time, both the x-axis and y-axis directions are obliquely incident, and an 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 provided on the side, when a sequence of pulsed lasers loaded with transient information of the sample to be tested at different times is incident on the inside of the lithium niobate crystal 41, the sequence of pulsed lasers propagates along the y-axis direction, effectively avoiding the birefringence effect. Since the laser can maintain its Gaussian shape and roundness 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 tested is large or its transient process is dangerous, the sample to be tested needs to be placed at a position far away from the pulse laser 3. Therefore, a collimator 8 and a fluoride glass optical fiber 9 can be sequentially arranged between the pulse laser 3 and the sample to be tested along the optical transmission direction, and the pulse laser is transmitted to the surface of the sample to be tested through the collimator 8 and the fluoride glass optical fiber 9 under the premise of safety. When the surface of the sample to be tested is large, a beam expander needs to be added behind the collimator 8 to increase the illumination surface of the pulse laser.

[0062] The first plane mirror 44 and the second plane mirror 45 are used to further separate the output light. The first plane mirror 44 and the second plane mirror 45 are sequentially located on the optical path of the multiple deflected laser beams, 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, 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, wherein α is usually 30° to 60°, preferably 45°, and β is less than or equal to 15°, that is, the first plane mirror 44 and the second plane mirror 45 are arranged in parallel, or a certain angle is set between the first plane mirror 44 and the second plane mirror 45, so that the multiple deflected laser beams are sequentially reflected by the first plane mirror 44 and the second plane mirror 45 to achieve the preset spacing requirements of the frame imaging. At the same time, 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 and the second plane mirror does not interfere with each other. Since different pulsed lasers arrive at the first plane mirror 44 at different times and positions, the distances of their reflected light propagating between the two mirror surfaces are different, which increases the position difference when arriving at the surface of the second plane mirror 45. When a certain angle is set between the first plane mirror 44 and the second plane mirror 45, the difference in their spatial position deflection will be further increased. In actual use, the angle of the first plane mirror 44 or the second plane mirror 45 can be adjusted by an adjustable knob, and then the angle between the first plane mirror 44 and the second plane mirror 45 can be adjusted to achieve the preset spacing requirements of the frame imaging.

[0063] The deflection control circuit 5 is composed of a high-voltage power supply module. Since the lithium niobate crystal 41 has a good linear electro-optical effect, and a voltage is applied along the z-axis direction of the lithium niobate crystal 41, its electro-optic coefficient and the corresponding refractive index change greatly. To achieve higher time resolution and number of framing, the deflection ability of the lithium niobate crystal 41 is particularly important. Therefore, a voltage is applied to a plurality of triangular upper electrodes 421 and triangular lower electrodes 431 arranged in an array through the deflection control circuit 5, thereby achieving a periodic voltage distribution.

[0064] The specific process of generating sequence voltages of different magnitudes in the deflection control circuit 5 is as follows: under the trigger of the first trigger signal of the timing trigger signal, as the pulse laser enters the lithium niobate crystal 41, the deflection control circuit 5 applies a kV voltage to the lithium niobate crystal 41 at the same time; when the trigger signal of the next moment arrives, as the pulse laser enters the lithium niobate crystal 41, the deflection control circuit 5 applies a voltage different from the previous moment to the lithium niobate crystal 41 at the same time, and the voltage magnitude can be a multiple of the previous moment, and so on, so that the deflection control circuit 5 applies a step voltage to the lithium niobate crystal 41 under the trigger signals at multiple different moments. By controlling the change of voltage, the adjustability of the beam angle can be achieved, and the adjustable spacing of the framed image can be achieved; the cyclic output of the step voltage can achieve the cyclic scanning integration of the beam.

[0065] The CMOS integral acquisition device 6 is located on the optical path after the multiple deflected laser beams are reflected by the second plane mirror, and is used to collect the multiple deflected laser beams to obtain the framed images of the transient information of the sample to be tested at different times. In this embodiment, the CMOS integral acquisition device 6 adopts a scientific research-grade sCMOS camera, which has the advantages of low power consumption and low noise, high readout rate, high dynamic range, low cost, compactness and high integration, but its frame rate is low, and it can realize rapid acquisition and imaging of the outgoing light of the light deflection system 4, and distribute the images at different times to the entire acquisition plane. The present invention has high requirements for the resolution and pixel size of the sCMOS camera. In order to meet the multi-frame imaging of the pulsed laser and improve the spatial resolution at the same time, the resolution of the sCMOS camera needs to be 2048×2048, and the pixel size is 6.5um. When the frame rate of the sCMOS camera is increased, each frame can realize multi-frame imaging, and the system can increase the multiple cycle rate scanning to achieve faster imaging.

[0066] The input end of the image processing unit 7 is connected to the output end of the CMOS integral acquisition device 6 through a high-speed data line, and is used to analyze and process each frame image to obtain ultrafast process imaging of the sample to be tested.

[0067] The image processing system cuts and compares the multi-frame images and determines the corresponding image time according to the arrangement position. Since the beam image information is spatially displaced with the angle offset during the electro-optical deflection process, there is a propagation loss and distance deviation, so the deflection of the lithium niobate crystal 41 needs to be corrected and reconstructed. According to the voltage deflection angle and displacement characteristics of the lithium niobate crystal 41, the ultrafast process imaging of the undeflected sample to be tested can be inverted through the beam propagation theory.

[0068] In order to meet the detection requirements of ultrafast events in multiple scenarios, the time resolution and time range of the detection in the present invention can be adjusted according to the actual situation. The time resolution can be dynamically changed by controlling the real-time timing trigger signal and changing the output width of the pulsed laser. By changing the time interval of the pulsed laser, the time range of the collected event can be dynamically adjusted. At the same time, according to the image information collected by the CMOS integration collection device 6, the working parameters of the system can be adjusted in real time to achieve a suitable output beam condition.

[0069] In addition, the number of the framed images of the present invention can be adjusted. Specifically, the time interval and the number of pulses of the pulsed laser are adjusted by controlling the timing trigger signal, and the deflection angle of the pulsed laser is controlled by the deflection control circuit 5, and the angle between the first plane mirror 44 and the second plane mirror 45 is adjusted to control the deflection interval distance of the framed images, so that the number of detection moments of ultrafast events can be adjusted, and different numbers of framed images can be obtained on the sCOMS camera. It can be seen that the voltage control of the present invention makes it more convenient to adjust the number of detected framed images.

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

[0071]

[0072] Among them, 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, that is, the optical aperture, which refers to the area 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. Z is the electric field in the z-axis direction.

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

[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 is related to the voltage V applied to 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 Are related.

[0077] During the specific test, in order to ensure the stability of each component, a shockproof chassis A and a shockproof chassis B are also provided in this embodiment. Among them, the pulse laser 3, the collimator 8 and the fluoride glass optical fiber 9 are connected in sequence through the pigtail port and fixed in the shockproof chassis A through a bracket. The synchronous pulse generator 1 is connected to the pulse laser 3 through a wire and fixed together in the shockproof chassis A. The shockproof chassis A serves as a laser output module, and the laser output port serves as an exposed 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 shockproof chassis B. The deflection control circuit 5 is respectively connected to the synchronous pulse generator 1 in the shockproof chassis A, the first output electrode 46 and the second output electrode 47 of the lithium niobate crystal 41 through a wire to realize signal transmission. At the same time, the light-transmitting surface (side) of the lithium niobate crystal 41 is exposed on the chassis surface, which is convenient for the pulse laser emitted from the shockproof chassis A to be incident after passing through the transient event of the sample to be tested.

[0078] The present invention also provides an all-solid-state ultrafast electro-optical framing imaging method, which specifically comprises the following steps:

[0079] Step 1, build the above-mentioned all-solid-state ultrafast electro-optical framing imaging system, initialize and set the synchronous pulse generator 1; place the sample to be tested between the pulse laser 3 and the lithium niobate crystal 41, and make the sample to be tested located on the output light path of the pulse laser 3.

[0080] Step 2, the signal control unit 2 controls the synchronous pulse generator 1 to synchronously generate two timing trigger signals at a fixed time, so as to synchronously trigger the pulse laser 3 and the deflection control circuit 5; the sequence pulse lasers with the same time interval output by the pulse laser 3 are sequentially incident on the sample to be tested after passing through the collimator 8 and the fluoride glass optical fiber 9, and the pulse lasers at different times record the transient information of the sample to be tested at different times; after loading the transient information of the sample to be tested at different times, they are then incident on the inside of the lithium niobate crystal 41. The sequence voltages of different magnitudes generated by the deflection control circuit 5 are synchronously applied to the lithium niobate crystal 41 through the upper electrode array 42 and the lower electrode array, so that the sequence pulse lasers loaded with the transient information of the sample to be tested at different times are deflected at different angles when passing through the lithium niobate crystal 41 in sequence, and multiple separated light beams emitted at different angles are formed on the xy plane, that is, multiple deflected laser beams containing the transient information of the sample to be tested at different times are obtained. The multiple deflected laser beams change with the control of the timing system. It should be pointed out that the timing trigger signal of the synchronization pulse generator 1 and the applied voltage of the deflection control circuit 5 can be adjusted to achieve real-time adjustment according to different scenes and situations, and realize the adjustable time resolution and number of frames.

[0081] Step 3: The multiple deflected laser beams are sequentially reflected by the first plane mirror 44 and the second plane mirror 45 and then incident on the CMOS integral acquisition device 6. During the process, the preset spacing requirement of the framing imaging needs to be achieved by adjusting the angle between the first plane mirror 44 and the second plane mirror 45. After the adjustment is completed, the CMOS integral acquisition device 6 collects the multiple deflected laser beams to obtain the framing images of the transient information of the sample to be tested at different times.

[0082] Step 4, the image processing unit 7 obtains the ultrafast process imaging of the undeflected sample to be tested by inverting the beam propagation theory based on the framed images of the transient information of the sample to be tested at different times and the voltage deflection angle and displacement characteristics of the lithium niobate crystal 41.

[0083] The above description is only used to illustrate the technical solution of the present invention rather than to limit it. For ordinary professional and technical personnel in the field, the specific technical solution recorded in the above embodiment can be modified, or some of the technical features therein can be replaced by equivalents, and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution protected by the present invention.

Claims

1. An all-solid-state ultrafast electro-optical 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 integration acquisition device (6) and an image processing unit (7); The signal control unit (2) is used to control the synchronization pulse generator (1) to synchronously generate two sets of timing 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), and are used to synchronously and timingly trigger the pulse laser (3) and the deflection control circuit (5) through two sets of timing trigger signals, so that the pulse laser (3) outputs a sequence of pulse lasers and the deflection control circuit (5) generates sequence voltages of different magnitudes; The light 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 grounding electrodes (422), the lower electrode array comprises M triangular lower electrodes (431) and M second grounding electrodes (432), M≥2; the triangular upper electrode (421), the first grounding electrode (422), the triangular lower electrode (431) and the second grounding electrode (432) are all of the same shape and size ; M triangular upper electrodes (421) and M second grounding electrodes (432) are arranged in an opposite and staggered manner on the upper surface of the lithium niobate crystal (41) along the laser transmission direction, and M first grounding electrodes (422) and M triangular lower electrodes (431) are arranged in an opposite and staggered manner on the lower surface of the lithium niobate crystal (41); the positions of the M first grounding electrodes (422) and the M triangular upper electrodes (421) correspond one to one, and the positions of the M second grounding electrodes (432) and the M triangular lower electrodes (431) correspond one to one; The side surface of the lithium niobate crystal (41) is located on the output light path of the pulse laser (3), and the sample to be tested is placed between the pulse laser (3) and the lithium niobate crystal (41), so that the sequence of pulse lasers is loaded with transient information of the sample to be tested at different times and then sequentially incident into the lithium niobate crystal (41); 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) and are used to apply a sequence voltage to the lithium niobate crystal (41) so that the pulsed laser passing through the lithium niobate crystal (41) at different times can be deflected at different angles to form multiple beams of deflected laser light; The CMOS integral acquisition device (6) is located on the optical path of the multiple deflected laser beams and is used to acquire the multiple deflected laser beams to obtain the framed images of the transient information of the sample to be tested at different times; The input end of the image processing unit (7) is connected to the output end of the CMOS integral acquisition device (6) and is used to analyze and process each frame image to obtain ultrafast process imaging of the sample to be tested.

2. The all-solid-state ultrafast electro-optical framing imaging system according to claim 1, characterized in that: The light 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 located on the optical path of the multiple deflected laser beams, 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, 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, wherein α is 30° to 60°, and β is less than or equal to 15°, so that the multiple deflected laser beams are sequentially reflected by the first plane mirror (44) and the second plane mirror (45) to achieve a preset spacing requirement for frame imaging; The CMOS integral collection device (6) is located on the optical path of the multiple deflected laser beams after being reflected by the second plane mirror (45); The distance between the first plane mirror (44) and the second plane mirror (45) is such that the lights reflected by the first plane mirror (44) and the second plane mirror (45) do not interfere with each other.

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

4. An all-solid-state ultrafast electro-optical framing imaging system according to any one of claims 1 to 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 grounding 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 grounding 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 also includes a collimator (8) and a fluoride glass optical fiber (9) which are sequentially arranged 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 output electrode (46), a second output electrode (47), a third output electrode (48) and a fourth output electrode (49); M triangular upper electrodes (421) are connected to the voltage output end of the deflection control circuit (5) through a first output electrode (46), and M triangular lower electrodes (431) are connected to the voltage output end of the deflection control circuit (5) through a second output electrode (47); The M second grounding electrodes (432) are grounded via the third lead-out electrode (48), and the M first grounding electrodes (422) are grounded via the fourth lead-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 grounding electrode (422), the triangular lower electrode (431) and the second grounding electrode (432) are all isosceles triangles.

8. An all-solid-state ultrafast electro-optical framing imaging method, characterized in that: The following steps are involved: Step 1, constructing an all-solid-state ultrafast electro-optical framing imaging system as described in any one of claims 1 to 7, placing a sample to be tested between a pulse laser (3) and a lithium niobate crystal (41), and placing the sample to be tested on the outgoing light path of the pulse laser (3); Step 2, the signal control unit (2) controls the synchronous pulse generator (1) to synchronously generate two timing 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 emitted by the pulse laser (3) sequentially passes through the sample to be tested to load its transient information at different times, and then is incident on the inside of the lithium niobate crystal (41); the sequence voltages of different magnitudes generated by the deflection control circuit (5) are 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 sample to be tested at different times is deflected at different angles when it passes through the lithium niobate crystal (41) sequentially, thereby obtaining multiple beams of deflected lasers containing the transient information of the sample to be tested at different times; Step 3, the CMOS integral acquisition device (6) acquires multiple deflected laser beams to obtain segmented images of transient information of the sample to be tested at different times; Step 4: the image processing unit (7) performs analysis and processing based on the framed images of the transient information of the sample to be tested at different times to obtain ultrafast process imaging of the sample to be tested.

9. The all-solid-state ultrafast electro-optical framing imaging method according to claim 8, characterized in that: Step 3 is as follows: The angle between the first plane mirror (44) and the second plane mirror (45) is adjusted to meet the preset spacing requirement of the framing imaging, and the CMOS integral acquisition device (6) acquires multiple deflected laser beams that meet the preset spacing requirement of the framing imaging after being reflected by the first plane mirror (44) and the second plane mirror (45) in sequence, so as to obtain framing images of transient information of the sample to be tested at different times.

10. The all-solid-state ultrafast electro-optical framing imaging method according to claim 9, characterized in that: Step 4 is as follows: The image processing unit (7) obtains ultrafast process imaging of the undeflected sample to be tested by inverting the beam propagation theory based on the framed images of transient information of the sample to be tested at different times and combining the voltage deflection angle and displacement characteristics of the lithium niobate crystal (41).

Images