Multi-mode multi-dimensional ultrafast electron microscopic imaging device and imaging method thereof

Abstract

The invention relates to an ultrafast electron microscopic imaging device and an imaging method thereof, in particular to a multi-mode multi-dimensional ultrafast electron microscopic imaging device and an imaging method thereof, and solves the problem that the existing electron microscopic imaging technical scheme is difficult to simultaneously meet the measurement requirements of high time-space-energy-momentum resolution and material diversification. The device comprises a sample cabin, an electron gun, a laser generation module, a secondary electron detector, an STEM detector, an in-cabin plug-in detection assembly, a plug-in camera and an energy filtering electron microscope assembly which are arranged below the sample cabin, and a vacuum system, a hollow sample table is arranged in the sample cabin, and at least two ultrafast pumping laser introduction windows are arranged on the cabin wall of the sample cabin; an ultrafast detection laser introduction window is arranged on the electronic gun shell; the secondary electron detector is arranged obliquely above the sample table; the STEM detector is arranged on the side cabin wall of the sample cabin and is positioned below the sample table; and the in-cabin plug-in detection assembly is arranged below the STEM detector.

Description

TECHNICAL FIELD

[0001] The present application relates to an ultrafast electron microscopy imaging device and an imaging method thereof, in particular to a multi-mode multi-dimension ultrafast electron microscopy imaging device and an imaging method thereof. BACKGROUND

[0002] As one of the most powerful tools for nanoscale structure characterization, electron microscopes, including transmission electron microscope (TEM) and scanning electron microscope (SEM), etc. TEM transmits high-energy electrons through very thin samples, and obtains the internal structure and crystallographic information of the sample according to the diffraction or transmission image formed by the scattering of electrons and atoms; SEM captures secondary electron or backscattered electron signals to obtain the surface topography and composition information of the sample. TEM and SEM can also provide imaging modes such as electron diffraction (ED), scanning transmission electron microscopy (STEM), four-dimensional scanning transmission electron microscopy (4D-STEM), and electron energy loss spectroscopy (EELS). ED technology can analyze the diffraction pattern generated by the electron beam in the crystal to reverse the atomic structure arrangement; STEM or 4D-STEM can greatly enhance the extraction capability of transmission electron in two-dimensional sample Fourier space information by converging the electron beam on the sample and scanning point by point on the sample surface to collect the convergent electron beam diffraction pattern; EELS measures the energy loss spectrum after the non-elastic scattering of electrons and sample, and is used to analyze the element composition and electronic state of the sample. Traditional electron microscopy imaging technology has very high spatial resolution, but its time resolution is usually limited by the frame rate of the recording system (such as CCD camera), and currently it can only reach milliseconds, which is difficult to capture nanosecond or even femtosecond scale dynamic processes, so the ultrafast electron microscopy imaging (UEM) technology emerges as the times require. Ultrafast electron microscopy imaging (UEM) technology combines femtosecond pump laser and electron beam detection to introduce the fourth dimension of time into the electron microscope. One of the femtosecond lasers is directed to the sample position to achieve the dynamic excitation of the sample, and the other femtosecond laser is directed to the photocathode to generate an ultrafast pulsed electron beam. The sample is excited by the light pulse and the sample state is detected by the ultrafast pulsed electron beam with precise delay to capture snapshot images of the sample at different times. The development of ultrafast electron microscopy imaging technology provides important support for the capture of atomic scale dynamic evolution process and original innovation breakthrough demand in important fields such as information technology, quantum science, materials science, and biological science.

[0003] In the research of ultrafast electron microscopy imaging technology, a key technical challenge is to develop an ultrafast electron microscopy imaging technology platform that integrates multiple detection modes and is compatible with multiple sample types, in order to meet the needs of different ultrafast dynamic information such as carrier information, real space information, reciprocal space information, structural information, energy band information, and electronic state information, and to meet the detection needs of block sample reflection imaging and thin film sample transmission imaging.

[0004] Existing ultrafast electron microscopy imaging technologies include: Reference 1 (Yang D., Mohammed OF, Zewail AH, et al. Scanning ultrafast electron microscopy[J]. Proceedings of the National Academy of Sciences, 2010,107(34):14993-14998.) proposes a combination of field emission scanning electron microscopy and pump-probe technology, realizing the construction of an ultrafast scanning electron microscopy imaging system. The ultrafast scanning electron microscope introduces light pulses into the electron gun, causing the filament to emit a photoelectron beam synchronized with the excitation light. The relative timing of the arrival of the pump light and probe electrons at the sample is controlled by an adjustable optical delay line, thus achieving time-domain resolution. The signals generated during imaging are mainly secondary electrons and backscattered electrons generated on the sample surface. Images are recorded by a secondary electron detector and a high-sensitivity imaging system to visualize the diffusion and migration dynamics of photogenerated carriers, while simultaneously obtaining the crystal diffraction (EBSD) pattern. However, this technique can only detect the dynamic information of the sample surface and near the surface, and cannot achieve internal structure imaging in transmission mode. At the same time, it is not equipped with an electron energy loss spectroscopy (EELS) instrument or a photoluminescence detector, and lacks the ability to simultaneously acquire energy spectrum or optical signals.

[0005] Reference 2 (Barantani F., Claude R., Iyikanat F., et al. Ultrafastmomentum-resolved visualization of the interplay between phonon-mediated scattering and plasmons in graphite[J]. Science advances, 2025, 11(14):eadu1001.) and Patent 4 (CN106645236A) demonstrate an ultrafast transmission electron microscopy (EELS) imaging system that combines transmission electron microscopy, electron energy loss spectroscopy (EELS), and pump-probe technology. First, it accelerates the ultrafast pulsed electron beam generated by light pulse excitation to 200 kV, ensuring the high spatial resolution of the ultrafast pulsed electron beam. Second, it utilizes the electron diffraction technology and orthogonal spatial imaging capability inherent in the transmission electron microscope to realize the imaging of the transient changes in the structural and morphological information of the sample. At the same time, EELS enables the system to obtain the electronic state information of the sample. However, the 200 kV electron energy can cause some damage to the sample, severely limiting the dynamic characterization of electron-sensitive materials such as perovskite and biomaterials. In addition, the system cannot capture signals such as secondary electrons and backscattered electrons on the sample surface, and is severely lacking in the ability to explore the dynamic evolution of charge carriers in materials in fields such as information technology and quantum science.

[0006] Reference 3 (Peter S., Peter D., Christian D., and Erdmann S. Low energy nano diffraction (LEND) – A versatile diffraction technique in SEM. Ultramicroscopy, 2020, 213: 112956.) demonstrates a low-energy nanodiffraction device, modified from a scanning electron microscope. This simple yet versatile device operates in the energy range of 0.5 keV to 30 keV. It uses a fluorescent screen and a dedicated vacuum camera to achieve a "diffraction mode" in SEM, enabling the acquisition of single-shot diffraction patterns as well as complete 4D-STEM diffraction patterns. However, this device lacks ultrafast electron imaging capabilities, limiting its observation to static sample information. Furthermore, its transmission electron diffraction pattern is measured through an observation window on the sample chamber, which introduces image distortion due to its angle, requiring post-processing correction. Additionally, the device lacks an electron energy loss spectroscopy (EELS) instrument or a photoluminescence detector, thus lacking the ability to simultaneously acquire energy spectral or optical signals.

[0007] In summary, existing ultrafast electron microscopy imaging techniques often fail to simultaneously meet the requirements of high temporal-spatial-energy-momentum resolution and diverse material measurement when dealing with the detection of complex ultrafast dynamic information in various materials. In particular, they lack comprehensive characterization techniques with multiple modes in complex systems that span multiple scales and materials.

[0008] Therefore, in order to achieve effective integration of multi-type and multi-dimensional material detection, it is urgent to develop a multi-mode, multi-dimensional ultrafast electron microscopy imaging device that integrates scanning reflection electron imaging, scanning transmission electron imaging, electron diffraction, and electron energy analysis. Summary of the Invention

[0009] The purpose of this invention is to address the technical problem that existing ultrafast electron microscopy imaging technologies struggle to simultaneously meet the requirements of high temporal-spatial-energy-momentum resolution and diverse material measurement when dealing with the detection of complex ultrafast dynamic information in various materials, especially in complex systems across scales and materials, where there is a lack of multi-mode, all-round characterization techniques. The invention provides a multi-mode, multi-dimensional ultrafast electron microscopy imaging device and its imaging method.

[0010] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A multi-mode, multi-dimensional ultrafast electron microscopy imaging device, characterized by: It includes a sample chamber, electron gun, laser generation module, secondary electron detector, STEM detector, in-chamber pluggable detection components, pluggable camera and energy-filtering electron microscope components, and vacuum system; The sample chamber is equipped with a sample stage with a hollow center for placing the sample to be tested, and at least two ultrafast pump laser introduction windows are provided on its chamber wall. The electron gun is mounted above the sample chamber, with its electron optical axis pointing vertically downwards and directly above the sample stage, for emitting an ultrafast pulsed electron beam toward the sample to be tested; the electron gun includes an electron gun housing; an ultrafast detection laser introduction window is provided on the electron gun housing; an objective lens with its optical axis coaxial with the electron gun's electron optical axis is provided in the communicating cavity formed by the sealed connection between the electron gun and the sample chamber, located between the lower end of the electron gun and the upper end of the sample chamber; The laser generation module is located outside the sample chamber and electron gun, and is used to generate ultrafast probe laser and ultrafast pump laser. The secondary electron detector is positioned diagonally above the sample stage inside the sample chamber. The STEM detector is installed on the side wall of the sample chamber. Its retractable detector probe is horizontal and located in the area below the sample stage inside the sample chamber. It can extend and retract between the side wall and directly below the sample stage. The pluggable in-cabin detection assembly is used for ultrafast electron diffraction imaging. It includes a through-hole fluorescent screen, a through-hole reflector, and a detection camera I. The through-hole fluorescent screen and the through-hole reflector are arranged with the former above the latter, their through holes coaxial, and their axes parallel to the electron gun's optical axis. They are positioned in the area below the STEM detector inside the sample chamber and can move horizontally between the side wall and directly below the sample stage. The detection window of the detection camera I is located in the reflected light path of the through-hole reflector. The plug-in camera and energy-filtering electron microscope assembly includes, from top to bottom, a adapter component I located below the sample chamber, an energy-filtering electron microscope, and a plug-in camera. The adapter component I seals and fixes the electron entrance of the energy-filtering electron microscope directly below the opening I located on the lower wall of the sample chamber, directly below the sample stage, thus connecting their internal cavities. The plug-in camera is mounted on the side wall of the adapter component I, with its retractable probe extending horizontally into the hollow interior of the adapter component I. It can extend and retract between its location on the side wall and directly below the sample stage, serving for ultrafast four-dimensional scanning transmission electron microscopy imaging and stabilizing the electron source, thereby correcting for diffraction pattern intensity, displacement, and temporal jitter. The vacuum system is connected to the inner cavity of the sample chamber and the electron gun to ensure that the vacuum level meets the requirements.

[0011] Further, we define: the direction parallel to and opposite to the electron optical axis of the electron gun is the positive Z-axis of the spatial coordinate system XYZ; the direction intersecting the Z-axis and parallel to the shortening direction of the detector probe of the STEM detector is the positive Y-axis of the spatial coordinate system XYZ; the positive X-axis of the spatial coordinate system XYZ is determined by the left-hand rule; the rotations about axes parallel to the X-axis, Y-axis, and Z-axis are α rotation, β rotation, and R rotation, respectively. The sample stage is a six-dimensional sample stage with a hollow center, which allows the sample to be tested to move along the X-axis, Y-axis, and Z-axis, as well as rotate α, β, and R. The detection camera I is installed on the side wall of the sample chamber; The fluorescent surface of the through-hole fluorescent screen is horizontal and facing upwards, and the distance between its upper surface and the sample placement surface of the horizontal sample stage is 150.15 mm ± 7 mm; the reflective surface of the through-hole reflector faces upwards. The distance between the receiving surface of the pluggable camera detector and the sample placement surface of the horizontally positioned sample stage is 327.65 mm ± 7 mm.

[0012] Furthermore, the plug-in camera and energy-filtering electron microscope assembly also includes a vacuum tube and a magnetic lens I; The vacuum pipe is located between the sample chamber and the adapter component I; the adapter component I is sealed and fixedly connected to the sample chamber directly below the opening I through the vacuum pipe, and the electron entrance end of the energy filter electron microscope is sealed and fixedly connected to the sample chamber directly below the opening I through the vacuum pipe and the adapter component I, and the inner cavities of the two are connected. The magnetic lens I is mounted on the outer cylindrical surface of the vacuum pipe and is used to laterally focus the transmitted electronic signal and the electronic signal to be analyzed.

[0013] Furthermore, the sample stage includes an α rotary stage, a Z displacement component, a transition component II, an R rotary stage, an X / Y displacement component, a β rotary stage, and a sample holder; The Z-displacement component includes a Z-displacement base layer and a Z-displacement stage; the Z-displacement base layer is rotatably connected to a door set on the side wall of the sample chamber via an α-rotating stage, and can rotate α relative to the door set on the side wall of the sample chamber; the Z-displacement stage is linearly slidably connected to the Z-displacement base layer, and can slide relative to it along the Z-axis direction; The adapter component II is fixedly connected to the lower end of the side of the Z-displacement stage away from the Z-displacement base layer, forming an L-shaped structure with the Z-displacement stage. The R rotary stage, X / Y displacement component, β rotary stage, and sample holder are arranged sequentially from bottom to top on the upper surface of the L-shaped horizontal arm. The rotation axis of the R rotary table is coplanar with the rotation axis of the α rotary table; The X / Y displacement component is located in the middle of the upper surface of the R-rotation platform, and includes an X / Y displacement base layer, an X displacement platform, and a Y displacement platform arranged sequentially from bottom to top. The X / Y displacement base layer is rotatably connected to the transfer component II via the R-rotation platform and can rotate relative to the transfer component II. The X displacement platform is linearly slidably connected to the X / Y displacement base layer and can slide relative to it along the X-axis. The Y displacement platform is linearly slidably connected to the X displacement platform and can slide relative to it along the Y-axis. The β rotary stage is disposed on the Y displacement stage and located on one side of the rotation axis of the R rotary stage, pointing in either the positive or negative direction of the Y axis. It includes a bottom β rotary stage and a top β rotary stage arranged sequentially from bottom to top. The bottom β rotary stage is fixedly connected to the Y displacement stage, and its upper surface is provided with an arc-shaped cylindrical track whose axis is parallel to the Y axis and coplanar with the rotation axis of the R rotary stage. The lower surface of the top β rotary stage is provided with a cylindrical surface adapted to the arc-shaped cylindrical track. The top β rotary stage is rotatably connected to the bottom β rotary stage and can rotate at a preset angle β relative to the bottom β rotary stage in a swinging manner. The sample holder is horizontally arranged along the Y-axis, with one end fixed to the upper surface of the top layer of the β rotary stage and the other end suspended directly above the rotation axis of the R rotary stage. A hollow sample stage structure is provided on the sample stage with the rotation axis of the R rotary stage as the central axis, extending from the lower surface of the adapter component II to the lower surface of the sample holder. Multiple spaced, vertically connected sample holes are provided on the other end of the sample holder to form a hollow sample stage. The other end of the sample holder is used to mount the sample to be tested.

[0014] Furthermore, the sample stage also includes adapter component III and adapter component IV; The adapter component Ⅲ is disposed between the lower part of the X / Y displacement base layer and the upper part of the R rotary table. The X / Y displacement base layer is fixedly connected to the adapter component Ⅲ, and is rotatably connected to the adapter component Ⅱ through the adapter component Ⅲ and the R rotary table. The adapter component IV is disposed between the bottom layer of the β rotary table and the Y displacement table, and is located on one side of the Y-axis of the rotation axis of the R rotary table, either in the positive or negative direction; the bottom layer of the β rotary table is fixedly connected to the Y displacement table through the adapter component IV.

[0015] Furthermore, the in-cabin pluggable detection assembly also includes a pluggable control assembly and a relay optical lens assembly; The insertion and removal control component is installed opposite to the detection camera I on the outside of the sample chamber side wall, and its telescopic rod extends horizontally into the sample chamber; by fixing the through-hole fluorescent screen and through-hole reflector to the free end of the telescopic rod, it can move horizontally between the side chamber wall and directly below the sample stage. The through-hole reflector is a 45° through-hole reflector; The relay optical lens assembly is located in the reflected light path of the through-hole reflector and is installed on the inner and outer sides of the same side wall of the sample chamber as the detection camera I. The beam diameter of the light signal is adjusted by the relay optical lens assembly to match the detection window of the detection camera I.

[0016] Furthermore, the electron gun also includes a cathode filament, a grid electrode, an anode, a high-voltage accelerating tube, a condenser lens I, a condenser lens II, and a scanning coil, which are arranged sequentially along the electron optical axis within the electron gun housing; The ultrafast detection laser introduction window is a focusing lens I, used to focus the ultrafast detection laser onto the cathode filament inside the electron gun housing; the accelerating voltage between the gate electrode and the anode is adjustable from 0V to 30kV. The objective lens is an electrostatic electromagnetic composite lens; The sample chamber wall is provided with two ultrafast pump laser introduction windows, which are respectively focusing lens II and focusing lens III. The optical axes of focusing lens II and focusing lens III are 50°~70° and 70°~110° with the electron optical axis of the electron gun, respectively. They are used to focus the 50°~70° ultrafast pump laser and the 70°~110° ultrafast pump laser onto the sample to be tested on the sample stage.

[0017] Furthermore, the laser generation module includes a laser, a beam splitter, a frequency doubling component and a reflector I arranged sequentially along the optical path, and a laser pulse delay control component, a reflector II and a reflector III arranged sequentially along the transmission optical path of the beam splitter. The laser is used to generate an ultrafast laser beam; The frequency doubling component is used to convert the frequency of the ultrafast laser beam reflected from the beam splitter to obtain an ultrafast probe laser. The focusing lens I is located in the reflected light path of the reflector I. The ultrafast detection laser generated by the laser generation module is emitted to the focusing lens I through the reflector I, and the ultrafast detection laser is focused and guided to the cathode filament inside the electron gun housing through the focusing lens I. The laser pulse delay control component is used to perform wavelength conversion and time control on the ultrafast laser beam in the transmission optical path of the beam splitter to obtain a pump-probe synchronized ultrafast pump laser. The focusing lens II is located on the reflected light path of the reflecting mirror III; The focusing lens III is located on the optical axis of the output end of the laser pulse delay control component, and is distributed on both sides of the reflecting mirror II, respectively, along with the laser pulse delay control component. The reflector II is removable; When the reflector II is working, the ultrafast pump laser of pump-probe synchronization is converted into a 50°~70° ultrafast pump laser through the reflector II and the reflector III and emitted to the focusing lens II. The focusing lens II focuses the 50°~70° ultrafast pump laser onto the sample to be tested on the sample stage. After the reflector II is removed, the ultrafast pump laser obtained by the pump-probe synchronization through the laser pulse delay precision control component is emitted as a 70°~110° ultrafast pump laser to the focusing lens III. The focusing lens III focuses the 70°~110° ultrafast pump laser onto the sample to be tested on the sample stage.

[0018] Furthermore, it also includes a backscattered electron detector, an energy-dispersive X-ray detector, an optical navigation camera, and a plasma cleaning device, all mounted on the sample chamber via flange interfaces. The energy-filtering electron microscope includes an energy-filtering electron microscope tube, a dipole magnet, a magnetic lens II, an energy slit, a magnetic lens III, a magnetic lens IV, a magnetic lens V, a magnetic lens VI, and a magnetic lens VII arranged sequentially along the electron optical axis within the energy-filtering electron microscope tube, and a detection camera II located outside the energy-filtering electron microscope tube with its detection window facing the electron emission port end of the energy-filtering electron microscope tube.

[0019] Meanwhile, the present invention also provides an imaging method for the above-mentioned multi-mode, multi-dimensional ultrafast electron microscopy imaging device, which is characterized by including the following steps: Step 1: Construct a multi-mode, multi-dimensional ultrafast electron microscopy imaging device. During construction, the ultrafast detection laser introduction window on the electron gun shell is set as focusing lens I, and two ultrafast pump laser introduction windows are set on the sample chamber wall, which are focusing lenses II and III, respectively. The angles between the optical axes of focusing lenses II and III and the electron optical axis of the electron gun are 50°~70° and 70°~110°, respectively. Then, all the retractable parts in each component of the constructed multi-mode, multi-dimensional ultrafast electron microscopy imaging device are in the retracted state, and each component is in the closed state or in a non-working standby state. Step 2: Install the sample to be tested onto the sample stage of the multi-mode multi-dimensional ultrafast electron microscopy imaging device in the standby state where all components are in the off state or non-working state in Step 1, and then close the door of the sample chamber. Step 3: Using the vacuum system, evacuate the inner cavities of the sample chamber and electron gun in the multi-mode multi-dimensional ultrafast electron microscopy imaging device, which was closed in Step 2, so that the inner cavities of both are evacuated to and maintained at the required vacuum level. Step 4: Based on the detection requirements of the sample to be tested installed on the sample stage in Step 2, select the imaging operation process from the following four imaging modes. After each imaging mode is executed, if the imaging mode contains multiple sub-imaging modes, after each sub-imaging mode is executed, all retractable components in the multi-mode multi-dimensional ultrafast electron microscopy imaging device constructed in Step 1 are retracted, and all components are in a closed or non-working standby state. The four imaging modes are: Imaging Mode A: Ultrafast Scan Reflection Mode The imaging process is as follows: Step A.1: The laser generation module generates an ultrafast probe laser and a 50°~70° ultrafast pump laser; the ultrafast probe laser generated by the laser generation module is emitted to the focusing lens I, and the ultrafast probe laser is focused and guided into the electron gun housing through the focusing lens I, so that the electron gun emits an ultrafast pulsed electron beam towards the sample under test; the 50°~70° ultrafast pump laser generated by the laser generation module is emitted to the focusing lens II, and the 50°~70° ultrafast pump laser is focused and guided onto the sample under test on the sample stage through the focusing lens II, so as to pump and excite the sample under test; Step A.2: The secondary electron detector is used to receive the secondary electrons generated by the interaction between the ultrafast pulsed electron beam emitted by the electron gun to the sample in step A.1 and the pumped sample, so as to realize the surface morphology and carrier imaging and complete the ultrafast scanning reflection mode. Imaging Mode B: Ultrafast Scan Transmission Mode The imaging mode B is divided into two sub-imaging modes: sub-imaging mode B1 and sub-imaging mode B2; Sub-imaging mode B1: Ultrafast conventional scanning transmission mode The imaging process is as follows: Step B1.1: The laser generation module generates an ultrafast probe laser and a 50°~70° ultrafast pump laser; the ultrafast probe laser generated by the laser generation module is emitted to the focusing lens I, and the ultrafast probe laser is focused and guided into the electron gun housing through the focusing lens I, so that the electron gun emits an ultrafast pulsed electron beam towards the sample under test; the 50°~70° ultrafast pump laser generated by the laser generation module is emitted to the focusing lens II, and the 50°~70° ultrafast pump laser is focused and guided onto the sample under test on the sample stage through the focusing lens II, so as to pump and excite the sample under test; Step B1.2: Extend the detector probe of the STEM detector to directly below the sample stage so that it can receive the transmission electron signal I generated by the interaction between the ultrafast pulsed electron beam emitted by the electron gun to the sample in step B1.1 and the pumped sample, so as to achieve topographic imaging and complete the ultrafast conventional scanning transmission mode. Sub-imaging mode B2: Ultrafast four-dimensional scanning transmission mode The imaging process is as follows: Step B2.1: The laser generation module generates an ultrafast probe laser and a 50°~70° ultrafast pump laser; the ultrafast probe laser generated by the laser generation module is emitted to the focusing lens I, and the ultrafast probe laser is focused and guided into the electron gun housing through the focusing lens I, so that the electron gun emits an ultrafast pulsed electron beam towards the sample under test; the 50°~70° ultrafast pump laser generated by the laser generation module is emitted to the focusing lens II, and the 50°~70° ultrafast pump laser is focused and guided onto the sample under test on the sample stage through the focusing lens II, so as to pump and excite the sample under test; Step B2.2: Extend the probe end of the plug-in camera to directly below the sample stage so that it can receive the transmission electron signal I generated by the interaction between the ultrafast pulsed electron beam emitted by the electron gun to the sample in step B2.1 and the pumped sample, so as to realize ultrafast four-dimensional scanning transmission electron microscopy imaging and complete the ultrafast four-dimensional scanning transmission mode. Imaging mode C: Ultrafast electron diffraction mode The imaging process is as follows: Step C.1: The laser generation module generates an ultrafast probe laser and a 50°~70° ultrafast pump laser; the ultrafast probe laser generated by the laser generation module is emitted to the focusing lens I, and the focusing lens I focuses the ultrafast probe laser into the electron gun housing, so that the electron gun emits an ultrafast pulsed electron beam towards the sample under test; the 50°~70° ultrafast pump laser generated by the laser generation module is emitted to the focusing lens II, and the focusing lens II focuses the 50°~70° ultrafast pump laser onto the sample under test on the sample stage, so as to pump and excite the sample under test; Step C.2: Move the through-hole fluorescent screen and through-hole reflector directly below the sample stage, and extend the probe end of the plug-in camera directly below the sample stage; use the probe camera I to capture the transmitted electron signal I generated by the interaction between the ultrafast pulsed electron beam emitted by the electron gun to the sample in step C.1 and the pumped sample, which passes through the through-hole fluorescent screen and the through-hole reflector in sequence, and the optical signal reflected by the through-hole reflector, to achieve reciprocal space information imaging of the sample; use the probe end of the plug-in camera to receive the transmitted electron signal I generated by the interaction between the ultrafast pulsed electron beam emitted by the electron gun to the sample in step C.1 and the pumped sample, which passes through the through-hole fluorescent screen and the through-hole reflector in sequence, and the transmitted electron signal II passing through the central through-hole of both, to detect the stability of the electron source, to correct the intensity, displacement and time jitter of the diffraction pattern, and to complete the ultrafast electron diffraction mode; Imaging Mode D: Energy-Filtered Electron Microscopy Imaging Mode The imaging process is as follows: Step D.1: The laser generation module generates an ultrafast probe laser and a 70°~110° ultrafast pump laser; the ultrafast probe laser generated by the laser generation module is emitted to the focusing lens I, and the ultrafast probe laser is focused and guided into the electron gun housing through the focusing lens I, so that the electron gun emits an ultrafast pulsed electron beam towards the sample under test; the 70°~110° ultrafast pump laser generated by the laser generation module is emitted to the focusing lens III, and the 70°~110° ultrafast pump laser is focused and guided onto the sample under test on the sample stage through the focusing lens III, so as to pump and excite the sample under test; Step D.2: The energy-filtered electron microscope is used to receive the electron signal to be analyzed generated by the interaction between the ultrafast pulsed electron beam emitted by the electron gun to the sample in step D.1 and the pumped sample, thereby realizing energy-filtered electron microscopy imaging and completing the energy-filtered electron microscopy imaging mode.

[0020] The beneficial effects of this invention are: (1) The multi-mode, multi-dimensional ultrafast electron microscopy imaging device of the present invention solves the problem that the electron beam of conventional electron microscopes cannot directly penetrate the sample stage by designing a compact, hollow six-dimensional sample stage, thus providing a universal sample stage for both reflection and transmission imaging modes and creating the basic conditions for its integration. Then, through a novel structural design, it integrates a scanning electron microscope, an in-chamber pluggable probe assembly, a pluggable camera, an energy-filtering electron microscope, an ultrafast probe laser introduction window, at least two ultrafast pump laser introduction windows, and the universal sample stage for both reflection and transmission. Compared with traditional ultrafast scanning electron microscopes or ultrafast transmission electron microscopes, it can simultaneously provide ultra-fast electron microscopy imaging. This invention employs multiple imaging modes, including fast scanning reflection electron imaging, ultrafast scanning transmission electron imaging, ultrafast electron diffraction imaging, and energy-filtered electron microscopy, offering advantages such as versatility, high temporal-spatial-energy-momentum resolution, and wide applicability. It can simultaneously meet the detection requirements of reflection imaging for bulk samples and transmission imaging for thin-film samples, significantly improving sample compatibility. Therefore, this invention addresses the technical challenge of existing ultrafast electron microscopy techniques in simultaneously meeting the high temporal-spatial-energy-momentum resolution and diverse material measurement needs when dealing with the detection of complex ultrafast dynamic information in various materials, particularly in complex systems spanning multiple scales and materials, where a comprehensive characterization technique with multiple modes is lacking. This invention's multi-mode, multi-dimensional ultrafast electron microscopy imaging device effectively improves the ability to acquire spatial information from samples.

[0021] (2) In the multi-mode multi-dimensional ultrafast electron microscopy imaging device of the present invention, an ultrafast probe laser introduction window and two ultrafast pump laser introduction windows are preferably designed. The ultrafast probe laser introduction window is a focusing lens I, and the two ultrafast pump laser introduction windows are a focusing lens II and a focusing lens III, respectively. The angles between the optical axis of the focusing lens II and the focusing lens III and the electron optical axis of the electron gun are 50°~70° and 70°~110°, respectively. This design can not only realize conventional pump-probe imaging of ultrafast laser and electron beam, but also meet the experimental requirements of laser modulation of electron through dielectric sample. It can also be used to study the interaction between light and electron, greatly improving the flexibility of the experiment and making it highly versatile.

[0022] (3) In the multi-mode, multi-dimensional ultrafast electron microscopy imaging device of the present invention, the sample stage is preferably a six-dimensional sample stage with a hollow center. The hollow center design allows it to be both reflective and transmissive, simultaneously meeting the detection requirements of reflection imaging of bulk samples and transmission imaging of thin film samples, thus improving sample compatibility. The six-dimensional design allows for adjustment of the sample in six degrees of freedom, further improving sample compatibility. In addition, the accelerating voltage between the gate electrode and the anode of the electron gun is preferably controlled within an adjustable range of 0V to 30kV in the present invention. This also avoids damage to the sample caused by excessively high electron energy. Therefore, the present invention can be used for the kinetic characterization of electron-sensitive materials such as perovskite materials and biomaterials, and the compatibility of sample materials is also greatly improved.

[0023] (4) In the multi-mode, multi-dimensional ultrafast electron microscopy imaging device of the present invention, an in-chamber pluggable detector component is designed. With a fixed size of the through-hole fluorescent screen, the length of the detector camera I is shortened, and a wider range of ultrafast electron diffraction patterns can be collected. At the same time, the central opening of the fluorescent screen and the reflector that receive the transmitted electron signal in the in-chamber pluggable detector component is adopted, that is, a through-hole fluorescent screen and a through-hole reflector. With this design, the diffracted electrons and the transmitted electron signal II that directly passes through the central through-hole of the through-hole fluorescent screen and the through-hole reflector are respectively imaged to the detector camera I and the pluggable camera. In this way, on the one hand, the diffracted electrons are used to detect sample information; on the other hand, the transmitted electron signal II that directly passes through the central through-hole of the through-hole fluorescent screen and the through-hole reflector is used to monitor the jitter of the transmitted electron signal in real time, detect the stability of the electron source, and realize the correction of the intensity, displacement and time jitter of the diffraction pattern, thereby improving the experimental accuracy and ultrafast electron imaging resolution.

[0024] (5) In the multi-mode, multi-dimensional ultrafast electron microscopy imaging device of the present invention, a pluggable camera is designed below the sample chamber. On the one hand, it can be used for ultrafast four-dimensional scanning transmission electron microscopy imaging, which greatly enhances the ability to resolve the spatial structure information of two-dimensional samples. On the other hand, it can be used for ultrafast electron diffraction imaging to receive the transmission electron signal II that passes directly through the through-hole fluorescent screen and the through-hole reflector center through-hole, monitor the jitter of the transmission electron signal in real time, detect the stability of the electron source, and realize the correction of the intensity, displacement and time jitter of the diffraction pattern, so as to improve the experimental accuracy and ultrafast electron imaging resolution.

[0025] (6) In the multi-mode, multi-dimensional ultrafast electron microscopy imaging device of the present invention, preferably, a condenser lens I and a condenser lens II are arranged sequentially along the electron optical axis inside the electron gun housing. The dual condenser lens electron optical path system can take into account both electron beam flux and time and spatial resolution to obtain the best focusing effect. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of an embodiment of the multi-mode, multi-dimensional ultrafast electron microscopy imaging device of the present invention (sample stage and vacuum system are not shown in the diagram). Figure 2 This is a schematic diagram of the structure of the pluggable detector component inside the cabin in an embodiment of the multi-mode, multi-dimensional ultrafast electron microscopy imaging device of the present invention. Figure 3 This is a schematic diagram of the plug-in camera and energy-filtering electron microscope assembly in an embodiment of the multi-mode, multi-dimensional ultrafast electron microscopy imaging device of the present invention. Figure 4 This is a schematic diagram of the sample stage structure from two different perspectives in an embodiment of the multi-mode, multi-dimensional ultrafast electron microscopy imaging device of the present invention, wherein: (1) is a schematic diagram of the sample stage structure from the first perspective; (2) is a schematic diagram of the sample stage structure from the second perspective; Figure 5 This is a schematic diagram illustrating four imaging modes achievable using an embodiment of the multi-mode, multi-dimensional ultrafast electron microscopy imaging device of the present invention, wherein: (A) is the ultrafast scanning reflection mode; (B) is the ultrafast scanning transmission mode; (C) is the ultrafast electron diffraction mode; (D) is the energy-filtered electron microscopy imaging mode.

[0027] The annotations in the attached figures are explained as follows: 1-Laser, 2-Ultrafast laser beam, 3-Beam splitter, 4-Reflector IV, 5-Laser pulse delay control component, 6-Frequency doubling component, 7-Ultrafast probe laser, 8-Electron gun housing, 9-Focusing lens I, 10-Cathode filament, 11-Gate electrode, 12-Anode, 13-High voltage accelerating tube, 14-Condenser I, 15-Condenser II, 16-Scanning coil, 17-Objective lens, 18-Ultrafast pulsed electron beam, 19-Focusing lens II, 20-Sample chamber, 21-Focusing lens III, 22-50°~70° ultrafast pump laser, 23-70°~110° ultrafast pump laser, 24-Sample to be tested, 25-Transmitted electron signal I, 26-Secondary electron, 27-Secondary electron detector, 28-STEM detector, 29-Detector probe, 3 0-In-cabin plug-in detection assembly, 31-Magnetic lens I, 32-Plug-in camera and energy-filtering electron microscope assembly, 33-Plug-in control assembly, 34-Telescopic rod, 35-Through-aperture fluorescent screen, 36-Through-aperture reflector, 37-Transmitted electron signal II, 38-Optical signal, 39-Relay optical lens assembly, 40-Detection camera I, 41-Electron signal to be analyzed, 42-Plug-in camera, 43-Adapter component I, 44-Energy-filtering electron microscope tube, 45-Dipole magnet, 46-Electron beam, 47-Low-energy electron beam I, 48-Low-energy electron beam II, 49-Magnetic lens II, 50-Energy slit, 51-Magnetic lens III, 52-Magnetic lens IV, 53-Magnetic lens V, 54-Magnetic lens VI, 55-Magnetic lens VII, 56-Detection camera II, 57- Z-displacement stage, 58-transfer component II, 59-R-rotation stage, 60-transfer component III, 61-X / Y displacement component, 62-transfer component IV, 63-β-rotation stage, 64-hollow sample stage structure, 65-sample holder, 66-sample hole, 67-reflector I, 68-reflector II, 69-reflector III. Detailed Implementation

[0028] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0029] See Figure 1 The present invention discloses a multi-mode, multi-dimensional ultrafast electron microscopy imaging device, comprising a sample chamber 20, an electron gun, a laser generation module, a secondary electron detector 27, a STEM detector 28, an in-chamber pluggable detection assembly 30, a pluggable camera and energy-filtering electron microscope assembly 32, and a vacuum system (not shown in the figure).

[0030] The sample chamber 20 is equipped with a sample stage with a hollow center for placing the sample 24 to be tested. Figure 1 The sample stage is not shown in the image; the sample stage is located in... Figure 1Below the sample chamber 24 (for mounting the sample 24), at least two ultrafast pump laser introduction windows are provided on its bulkhead. In this embodiment, the sample chamber 20 has two ultrafast pump laser introduction windows on its bulkhead, which are focusing lens II 19 and focusing lens III 21, respectively. The optical axes of focusing lens II 19 and focusing lens III 21 are 50°~70° and 70°~110° with the electron gun optical axis, respectively, and are used to focus the 50°~70° ultrafast pump laser 22 and the 70°~110° ultrafast pump laser 23 onto the sample 24 on the sample stage.

[0031] The electron gun is mounted above the sample chamber 20, with its electron optical axis pointing vertically downwards and directly above the sample stage. It is used to emit an ultrafast pulsed electron beam 18 towards the sample 24 to be tested. The electron gun includes an electron gun housing 8. An ultrafast detection laser introduction window is provided on the electron gun housing 8. An objective lens 17, with its optical axis coaxial with the electron gun's electron optical axis, is provided in the communicating cavity formed by the sealed connection between the electron gun and the sample chamber 20, located between the lower end of the electron gun and the upper end of the sample chamber 20. In this embodiment, in addition to the electron gun housing 8, the electron gun also includes a cathode filament 10, a grid electrode 11, an anode 12, and a high-voltage accelerating tube 13, which are sequentially arranged along the electron optical axis within the electron gun housing 8. The electron gun housing 8 includes a condenser lens I 14, a condenser lens II 15, and a scanning coil 16. The ultrafast detection laser introduction window on the electron gun housing 8 is a focusing lens I 9, which is used to focus the ultrafast detection laser 7 to the cathode filament 10 inside the electron gun housing 8 to generate an ultrafast pulsed electron beam 18. The generated ultrafast pulsed electron beam 18 is accelerated by the accelerating voltage between the gate electrode 11 and the anode 12, and propagates downward through the high-voltage accelerating tube 13. This propagation process is focused by the dual condenser lens electron optical path system of condenser lens I 14 and condenser lens II 15, controlled by the electron beam of the scanning coil 16, and focused by the objective lens 17, and finally reaches the sample 24 to be tested, where electrons interact with matter. In this embodiment, a condenser lens I 14 and a condenser lens II 15 are sequentially arranged along the electron optical axis inside the electron gun housing 8, employing a dual-condenser lens electron optical path system. This system can balance electron beam flux and temporal and spatial resolution, achieving optimal focusing effect. Furthermore, in this embodiment, to avoid damage to the sample from excessively high electron energy, the accelerating voltage between the gate electrode 11 and the anode 12 is preferably adjustable from 0V to 30kV. In this embodiment, the objective lens 17 is an electrostatic electromagnetic composite lens.

[0032] The aforementioned laser generation module is located outside the sample chamber 20 and the electron gun, and is used to generate ultrafast probe laser 7 and ultrafast pump laser. In this embodiment, the laser generation module includes a laser 1, a beam splitter 3, a frequency doubling component 6 and a reflector I 67 arranged sequentially along the optical path of the beam splitter 3, and a laser pulse delay control component 5, a reflector II 68, and a reflector III 69 arranged sequentially along the transmission optical path of the beam splitter 3. Laser 1 is used to generate an ultrafast laser beam 2; in this embodiment, a femtosecond laser is selected for laser 1, and the generated ultrafast laser beam 2 is a femtosecond laser beam. The ultrafast laser beam 2 generated by laser 1 is split into two ultrafast laser beams by the beam splitter 3.

[0033] The aforementioned frequency doubling component 6 is used to perform frequency conversion on the ultrafast laser beam reflected by the beam splitter 3 to obtain the ultrafast probe laser 7; in this embodiment, the ultrafast probe laser 7 is an ultraviolet femtosecond probe laser. Besides the ultraviolet femtosecond probe laser of this embodiment, the ultrafast probe laser 7 can also be ultrafast probe lasers of other wavelengths such as visible light or near-infrared light, or other timescales such as attoseconds, picoseconds, or nanoseconds. The aforementioned focusing lens I9 is ​​located on the reflected light path of the reflector I67. The ultrafast probe laser 7 generated by the laser generation module is emitted to the focusing lens I9 through the reflector I67, and the focusing lens I9 focuses the ultrafast probe laser 7 onto the cathode filament 10 inside the electron gun housing 8 to generate an ultrafast pulsed electron beam 18.

[0034] The aforementioned laser pulse delay control component 5 is used to perform wavelength conversion and time control on the ultrafast laser beam in the transmission optical path of the beam splitter 3 to obtain a pump-probe synchronized ultrafast pump laser. In this embodiment, the laser pulse delay control component 5 includes four reflecting mirrors IV4 arranged sequentially along the optical path. The aforementioned focusing lens II19 is located on the reflected optical path of the reflecting mirror III69; the aforementioned focusing lens III21 is located on the optical axis of the output end of the laser pulse delay control component 5, and is distributed on both sides of the aforementioned reflecting mirror II68, respectively; the aforementioned reflecting mirror II68 is removable; according to the detection requirements of the sample 24 to be tested, by making the reflecting mirror II68 work and removing the reflecting mirror II68, the ultrafast pump laser at different angles is guided to the sample 24 to be tested on the sample stage, specifically: When mirror II 68 is working, the pump-probe synchronized ultrafast pump laser is converted into a 50°~70° ultrafast pump laser 22 through mirror II 68 and mirror III 69 and emitted to focusing lens II 19. The focusing lens II 19 focuses the 50°~70° ultrafast pump laser 22 onto the sample 24 on the sample stage. After mirror II 68 is removed, the pump-probe synchronized ultrafast pump laser obtained by the laser pulse delay control component 5 is emitted as a 70°~110° ultrafast pump laser 23 to focusing lens III 21. The focusing lens III 21 focuses the 70°~110° ultrafast pump laser 23 onto the sample 24 on the sample stage.

[0035] As described above, the 50°~70° ultrafast pump laser 22 and the 70°~110° ultrafast pump laser 23 generated by the laser generation module do not operate simultaneously. The 50°~70° ultrafast pump laser 22 is used to pump and excite the sample 24 under test, followed by electron pulse detection, and is suitable for ultrafast scanning reflection mode, ultrafast scanning transmission mode, and ultrafast electron diffraction mode, etc. The 70°~110° ultrafast pump laser 23 is used to provide a periodic light field for the photonic crystal at the position of the sample 24 under test, and can be used for electron pulse compression, etc., suitable for energy-filtered electron microscopy imaging mode. In this embodiment, the 50°~70° ultrafast pump laser 22 generated by the laser generation module is a 50°~70° infrared femtosecond pump laser; the 70°~110° ultrafast pump laser 23 generated by the laser generation module is a 70°~110° infrared femtosecond pump laser. In addition to being the infrared femtosecond pumped laser of this embodiment, the 50°~70° ultrafast pumped laser 22 and the 70°~110° ultrafast pumped laser 23 can also be ultrafast pumped lasers of other wavelengths such as extreme ultraviolet light, ultraviolet light, visible light, near-infrared light or infrared light, and other time scales such as attosecond, picosecond or nanosecond.

[0036] The aforementioned secondary electron detector 27 is located diagonally above the sample stage inside the sample chamber 20; in this embodiment, the secondary electron detector 27 is an ET secondary electron detector, and its signal output end extends out of the chamber wall.

[0037] The aforementioned STEM detector 28 is mounted on the side wall of the sample chamber 20. Its retractable detector probe 29 is horizontal and located below the sample stage inside the sample chamber 20, and can extend and retract between the side wall and directly below the sample stage. In this embodiment, the detector probe 29 of the STEM detector 28 is a semiconductor electronic detector.

[0038] See Figure 1 and Figure 2The aforementioned pluggable detector assembly 30 is used for ultrafast electron diffraction imaging. It includes a through-hole fluorescent screen 35, a through-hole reflector 36, and a detector camera I 40. The through-hole fluorescent screen 35 and the through-hole reflector 36 are arranged in the area below the STEM detector 28 in the sample chamber 20, with the fluorescent surface of the former horizontal and facing upward, the reflector of the latter facing upward, the former located above the latter, and the through holes of both coaxial and the axis parallel to the electron optical axis of the electron gun. It can move horizontally between the side wall and directly below the sample stage. The detection window of the detector camera I 40 is located in the reflected light path of the through-hole reflector 36. In this embodiment, the detector camera I 40 is mounted on the side wall of the sample chamber 20. The distance between the upper surface of the through-hole fluorescent screen 35 and the sample placement surface of the horizontally positioned sample stage is 150.15 mm ± 7 mm, which is taken as 150.15 mm in this embodiment. In this embodiment, to facilitate the movement of the through-hole fluorescent screen 35 and the through-hole reflector 36, the aforementioned in-chamber pluggable detection assembly 30 preferably further includes a pluggable adjustment assembly 33; the pluggable adjustment assembly 33 is installed outside the side wall of the sample chamber 20, and its telescopic rod 34 extends horizontally into the sample chamber 20; by fixing the aforementioned through-hole fluorescent screen 35 and the through-hole reflector 36 to the free end of the aforementioned telescopic rod 34, it can be moved horizontally between the side wall and directly below the sample stage; in this embodiment, the pluggable adjustment assembly 33 is preferably installed opposite to the detection camera I 40 on the outside of the side wall of the sample chamber 20. In this embodiment, the aforementioned in-chamber pluggable detection assembly 30 preferably also includes a relay optical lens assembly 39; the relay optical lens assembly 39 is located in the reflected light path of the through-hole reflector 36, and is installed on the inner and outer sides of the same side wall of the sample chamber 20 as the detection camera I 40, respectively; the relay optical lens assembly 39 adjusts the beam diameter of the light signal to adapt to the detection window of the detection camera I 40. In this embodiment, the relay optical lens assembly 39 consists of a vacuum observation window and a lens assembly; the vacuum observation window is mainly used to connect the sample chamber, transmit optical signals, and fix the lens assembly; the lens assembly includes a convex lens I, a concave lens, and a convex lens II arranged sequentially along the optical path. In this embodiment, the through-hole reflector 36 is a 45° through-hole reflector, the optical axis of the relay optical lens assembly 39 is horizontal, and it is coaxial with the telescopic rod 34 of the insertion and removal control assembly 33. The ultrafast pulsed electron beam 18 emitted by the electron gun interacts with the pumped and excited sample 24 to generate a transmitted electron signal I 25. After reaching the through-hole fluorescent screen 35, part of the transmitted electron signal is converted into an optical signal by the through-hole fluorescent screen 35, and then reflected by the through-hole reflector 36 and converted into an optical signal 38. After passing through the relay optical lens assembly 39, it is captured by the detection camera I 40 to realize the inverted space information imaging of the sample 24. The transmitted electron signal II 37 passing through the through-hole fluorescent screen 35 and the central through-hole of the through-hole reflector 36 is received by the detection end of the plug-in camera 42 to detect the stability of the electron source and realize the correction of the intensity, displacement and time jitter of the diffraction pattern.The detection camera I 40 can be a CCD or CMOS detection camera; the plug-in camera 42 can be a CCD, CMOS or direct electronic detection camera with plug-in function.

[0039] See Figure 1 and Figure 3The aforementioned plug-in camera and energy-filtering electron microscope assembly 32 includes, from top to bottom, a adapter component I 43 and an energy-filtering electron microscope arranged below the sample chamber 20, and also includes a plug-in camera 42. An opening I is provided on the lower wall of the sample chamber 20 directly below the sample stage. The electron entrance end of the energy-filtering electron microscope is sealed and fixed to the opening I of the sample chamber 20 directly below the aforementioned opening I through the adapter component I 43, and the inner cavities of the two are connected. The plug-in camera 42 is installed on the side wall of the adapter component I 43, and its retractable probe end extends horizontally into the hollow part inside the adapter component I 43. It can extend and retract between the side wall where it is located and directly below the sample stage, and is used for ultrafast four-dimensional scanning transmission electron microscopy imaging and to detect the stability of the electron source, so as to correct the intensity, displacement and time jitter of the diffraction pattern. The distance between the receiving surface of the probe end of the plug-in camera 42 and the sample placement surface of the sample stage in a horizontal state is 327.65 mm ± 7 mm, and 327.65 mm is taken in this embodiment. In this embodiment, to effectively improve the response capability to weak transmitted electron signals, the plug-in camera is preferably a low-energy direct electron detection camera with high quantum detection efficiency. To achieve better imaging quality in both ultrafast electron diffraction mode and energy-filtered electron microscopy imaging mode, and to achieve higher resolution, the plug-in camera and energy-filtered electron microscope assembly 32 preferably further includes a vacuum pipe and a magnetic lens I 31. The vacuum pipe is located between the sample chamber 20 and the adapter I 43. The adapter I 43 is sealed and fixedly connected to the sample chamber 20 directly below the opening I via the vacuum pipe. The vacuum pipe and adapter I 43 seal and fix the electron entrance of the energy-filtered electron microscope directly below the opening I of the sample chamber 20, and connect their internal cavities. The magnetic lens I 31 is mounted on the outer cylindrical surface of the vacuum pipe and is used for lateral focusing of the transmitted electron signal and the electron signal 41 to be analyzed. In this embodiment, the energy-filtering electron microscope includes an energy-filtering electron microscope tube 44, a dipole magnet 45, a magnetic lens II 49, an energy slit 50, a magnetic lens III 51, a magnetic lens IV 52, a magnetic lens V 53, a magnetic lens VI 54, and a magnetic lens VII 55 arranged sequentially along the electron optical axis within the energy-filtering electron microscope tube 44, and a detection camera II 56 with its detection window facing the electron emission port end of the energy-filtering electron microscope tube 44 and located outside the energy-filtering electron microscope tube 44.The ultrafast pulsed electron beam 18 emitted by the electron gun interacts with the pumped and excited sample 24 to generate the analyzed electron signal 41, which passes sequentially through the aforementioned opening I, vacuum pipe, and transition component I 43, and enters the electron entrance of the energy-filtering electron microscope. It first undergoes a 70°~110° deflection by the dipole magnet 45, where the electron deflection radius decreases as the electron energy decreases. Under the influence of the magnetic field, the analyzed electron signal 41 is separated into electron beams 46, low-energy electron beam I 47, and low-energy electron beam II 48, arranged in descending order of radial size. Subsequently, it passes through the energy selection via magnetic lens II 49, energy slit 50, magnetic lens III 51, magnetic lens IV 52, magnetic lens V 53, magnetic lens VI 54, and magnetic lens VII 55, and is finally received by the detection camera II 56. The detection camera II 56 can be a CCD, CMOS, or direct electron detector.

[0040] The aforementioned vacuum system is connected to the sample chamber 20 and the inner cavity of the electron gun to ensure that the vacuum level meets the requirements. In this embodiment, the vacuum system includes one turbomolecular pump, one mechanical pump, and two ion pumps.

[0041] To enable the multi-mode, multi-dimensional ultrafast electron microscopy imaging device of this invention to possess more imaging modes and cleaning functions, the device preferably also has backscattered electron detectors, energy-dispersive X-ray detectors, optical navigation cameras, and other detectors or cameras, as well as plasma cleaning equipment, installed on the sample chamber 20 via flange interfaces. This multi-mode, multi-dimensional ultrafast electron microscopy imaging device integrates multiple reflection and transmission imaging modes, including ultrafast scanning reflection mode, ultrafast scanning transmission mode, ultrafast electron diffraction mode, and energy-filtered electron microscopy imaging mode. In reflection imaging mode, secondary electron detectors 27 and backscattered electron detectors capture secondary electrons and backscattered electrons generated on the sample surface, respectively, achieving nanoscale resolution imaging of sample surface dynamics. Energy-dispersive X-ray detectors acquire X-ray characteristic wavelengths to analyze the elemental composition and content of micro-regions in the material. In transmission imaging mode, STEM detectors 28, in-chamber pluggable detector components 30, and pluggable cameras 42 are used to characterize the sample structure dynamics, and energy-filtered electron microscopes are used to achieve electron energy-resolution imaging. In summary, the multi-mode, multi-dimensional ultrafast electron microscopy imaging device of this invention can provide information on samples in multiple dimensions, such as space, time, energy, and elements, under non-equilibrium conditions, effectively improving the ability to analyze ultrafast response processes of materials.

[0042] See Figure 4In (1) and (2), in order to enable multiple degrees of freedom adjustment of the sample and further improve the compatibility of the sample, the sample stage in this embodiment is preferably a six-dimensional sample stage with a hollow center. Definition: The direction parallel to and opposite to the electron optical axis of the electron gun is the positive Z-axis of the spatial coordinate system XYZ; the direction of the shortening direction of the detector probe 29, which intersects the Z-axis and is parallel to the STEM detector 28, is the positive Y-axis of the spatial coordinate system XYZ; the positive X-axis of the spatial coordinate system XYZ is determined by the left-hand rule; the rotations around axes parallel to the X-axis, Y-axis, and Z-axis are α rotation, β rotation, and R rotation, respectively; then the sample stage in this embodiment can enable the sample 24 to move along the X-axis, Y-axis, and Z-axis directions and to rotate α, β, and R.

[0043] See Figure 4 In (1) and (2), the sample stage in this embodiment includes an α rotary stage, a Z displacement component, a transition component II 58, an R rotary stage 59, an X / Y displacement component 61, a β rotary stage 63, and a sample holder 65.

[0044] The aforementioned Z-displacement component includes a Z-displacement base layer and a Z-displacement stage 57. The Z-displacement base layer is rotatably connected to a door located on the side wall of the sample chamber 20 via an α-rotating stage, and can rotate α relative to the door located on the side wall of the sample chamber 20. The Z-displacement stage 57 is linearly slidably connected to the Z-displacement base layer, and can slide relative to it along the Z-axis. The adapter component II 58 is fixedly connected to the lower end of the side of the Z-displacement stage 57 away from the Z-displacement base layer, forming an L-shaped structure with the Z-displacement stage 57. The R-rotating stage 59, X / Y displacement component 61, β-rotating stage 63, and sample support 65 are arranged sequentially from bottom to top on the upper surface of the horizontal arm of the aforementioned L-shaped structure. The rotation axis of the R-rotating stage 59 is coplanar with the rotation axis of the α-rotating stage. The X / Y displacement component 61 is located in the middle of the upper surface of the R rotary stage 59. It includes an X / Y displacement base layer, an X displacement stage, and a Y displacement stage arranged sequentially from bottom to top. The X / Y displacement base layer is rotatably connected to the adapter component II 58 via the R rotary stage 59 and can rotate relative to the adapter component II 58. For ease of processing, the sample stage in this embodiment preferably also includes an adapter component III 60. The adapter component III 60 is disposed between the lower part of the X / Y displacement base layer and the upper part of the R rotary stage 59. The X / Y displacement base layer is fixedly connected to the adapter component III 60 and rotatably connected to the adapter component II 58 via the adapter component III 60 and the R rotary stage 59. The X displacement stage is linearly slidably connected to the X / Y displacement base layer and can slide relative to it along the X-axis. The Y displacement stage is linearly slidably connected to the X displacement stage and can slide relative to it along the Y-axis. The β rotary stage 63 is disposed on the Y displacement stage and is located on the positive Y-axis of the rotation axis of the R rotary stage 59. The sample stage, located on one side pointing in either the positive or negative direction, includes a bottom layer and a top layer of a β-rotary stage arranged sequentially from bottom to top. The bottom layer of the β-rotary stage is fixedly connected to the Y-displacement stage, and its upper surface is provided with an arc-shaped cylindrical track whose axis is parallel to the Y-axis and coplanar with the rotation axis of the R-rotary stage 59. For ease of processing, the sample stage in this embodiment preferably also includes a transition component IV 62. The transition component IV 62 is disposed between the bottom layer of the β-rotary stage and the Y-displacement stage, and is located on one side pointing in either the positive or negative direction of the Y-axis of the rotation axis of the R-rotary stage 59. The bottom layer of the β-rotary stage is fixedly connected to the Y-displacement stage through the transition component IV 62. The lower surface of the top layer of the β-rotary stage is provided with a cylindrical surface adapted to the aforementioned arc-shaped cylindrical track. The top layer of the β-rotary stage is rotatably connected to the bottom layer of the β-rotary stage and can rotate at a preset angle β relative to the bottom layer of the β-rotary stage in a swinging manner. In this embodiment, the β-rotary stage 63 is an externally purchased component, model number PG-50-11206.The sample holder 65 is horizontally positioned along the Y-axis, with one end fixed to the upper surface of the top layer of the aforementioned β-rotary stage and the other end suspended directly above the rotation axis of the aforementioned R-rotary stage 59. A hollow sample stage structure 64, extending from the lower surface of the adapter component II 58 to the lower surface of the sample holder 65, is provided on the sample stage with the rotation axis of the R-rotary stage 59 as its central axis. Multiple spaced, vertically connected sample holes 66 are provided on the other end of the sample holder 65 to form a hollow sample stage, satisfying the conditions for integrated transmission imaging mode. The other end of the sample holder 65 is used to mount the sample to be tested 24. In this embodiment, the sample to be tested 24 is a copper mesh sample. In this embodiment, the sample stage retains the α-rotary stage, Z-displacement substrate, and Z-displacement stage 57 of the scanning electron microscope. The Z-displacement substrate is rotatably connected to a hatch located on the side wall of the sample chamber 20 via the α-rotary stage.

[0045] See Figure 5 The present invention also provides an imaging method for the above-mentioned multi-mode, multi-dimensional ultrafast electron microscopy imaging device, comprising the following steps: Step 1: Construct a multi-mode, multi-dimensional ultrafast electron microscopy imaging device. During construction, the ultrafast detection laser introduction window on the electron gun housing 8 is set as a focusing lens I 9, and two ultrafast pump laser introduction windows are set on the sample chamber 20 wall, namely focusing lens II 19 and focusing lens III 21, respectively. The angles between the optical axes of focusing lens II 19 and focusing lens III 21 and the electron optical axis of the electron gun are 50°~70° and 70°~110°, respectively. Then, all the retractable parts in each component of the constructed multi-mode, multi-dimensional ultrafast electron microscopy imaging device are in the retracted state, and each component is in the closed state or in a non-working standby state. Step 2: Install the sample 24 to be tested onto the sample stage of the multi-mode multi-dimensional ultrafast electron microscopy imaging device in the standby state where all components are in the off state or non-working state in Step 1, and then close the door of the sample chamber 20. Step 3: Using the vacuum system described above, evacuate the inner cavities of the sample chamber 20 and the electron gun in the multi-mode multi-dimensional ultrafast electron microscopy imaging device with the doors closed in Step 2, so that the inner cavities of both are evacuated to and maintained at the required vacuum level. Step 4: Based on the detection requirements of the sample 24 to be tested installed on the sample stage in Step 2, select the imaging operation process from the following four imaging modes. After each imaging mode is executed, if the imaging mode contains multiple sub-imaging modes, after each sub-imaging mode is executed, all retractable components in the multi-mode multi-dimensional ultrafast electron microscopy imaging device constructed in Step 1 are retracted, and all components are put into a closed or non-working standby state. The above four imaging modes are: (a) SeeFigure 5 (A) Imaging mode A: Ultrafast scanning reflectance mode The imaging process is as follows: Step A.1: The laser generation module generates an ultrafast probe laser 7 and a 50°~70° ultrafast pump laser 22; the ultrafast probe laser 7 generated by the laser generation module is emitted to the focusing lens I9, and the ultrafast probe laser 7 is focused and guided into the electron gun housing 8 through the focusing lens I9, so that the electron gun emits an ultrafast pulsed electron beam 18 towards the sample 24 under test; the 50°~70° ultrafast pump laser 22 generated by the laser generation module is emitted to the focusing lens II19, and the 50°~70° ultrafast pump laser 22 is focused and guided onto the sample 24 under test on the sample stage through the focusing lens II19, so as to pump and excite the sample 24 under test; Step A.2: The secondary electron detector 27 described above receives the secondary electrons 26 generated by the interaction between the ultrafast pulsed electron beam 18 emitted by the electron gun to the sample 24 in step A.1 and the pumped and excited sample 24, so as to realize the surface morphology and carrier imaging and complete the ultrafast scanning reflection mode. (ii) See Figure 5 (B) Imaging mode B: Ultrafast scanning transmission mode The above imaging mode B is divided into two sub-imaging modes: sub-imaging mode B1 and sub-imaging mode B2; Sub-imaging mode B1: Ultrafast conventional scanning transmission mode The imaging process is as follows: Step B1.1: The laser generation module generates an ultrafast probe laser 7 and a 50°~70° ultrafast pump laser 22; the ultrafast probe laser 7 generated by the laser generation module is emitted to the focusing lens I9, and the ultrafast probe laser 7 is focused and guided into the electron gun housing 8 through the focusing lens I9, so that the electron gun emits an ultrafast pulsed electron beam 18 towards the sample 24 under test; the 50°~70° ultrafast pump laser 22 generated by the laser generation module is emitted to the focusing lens II19, and the 50°~70° ultrafast pump laser 22 is focused and guided onto the sample 24 under test on the sample stage through the focusing lens II19, so as to pump and excite the sample 24 under test; Step B1.2: Extend the detector probe 29 of the STEM detector 28 to directly below the sample stage so that it can receive the transmission electron signal I25 generated by the interaction between the ultrafast pulsed electron beam 18 emitted by the electron gun to the sample 24 in step B1.1 and the pumped and excited sample 24, so as to achieve topographic imaging and complete the ultrafast conventional scanning transmission mode. Sub-imaging mode B2: Ultrafast four-dimensional scanning transmission mode The imaging process is as follows: Step B2.1: The laser generation module generates an ultrafast probe laser 7 and a 50°~70° ultrafast pump laser 22; the ultrafast probe laser 7 generated by the laser generation module is emitted to the focusing lens I9, and the ultrafast probe laser 7 is focused and guided into the electron gun housing 8 through the focusing lens I9, so that the electron gun emits an ultrafast pulsed electron beam 18 towards the sample 24 under test; the 50°~70° ultrafast pump laser 22 generated by the laser generation module is emitted to the focusing lens II19, and the 50°~70° ultrafast pump laser 22 is focused and guided onto the sample 24 under test on the sample stage through the focusing lens II19, so as to pump and excite the sample 24 under test; Step B2.2: Extend the probe end of the plug-in camera 42 to directly below the sample stage so that it can receive the transmission electron signal I25 generated by the interaction between the ultrafast pulsed electron beam 18 emitted by the electron gun to the sample 24 in step B2.1 and the pumped and excited sample 24, so as to realize ultrafast four-dimensional scanning transmission electron microscopy imaging and complete the ultrafast four-dimensional scanning transmission mode. (III) See Figure 5 (C), Imaging mode C: Ultrafast electron diffraction mode The imaging process is as follows: Step C.1: The laser generation module generates an ultrafast probe laser 7 and a 50°~70° ultrafast pump laser 22; the ultrafast probe laser 7 generated by the laser generation module is emitted to the focusing lens I9, and the ultrafast probe laser 7 is focused and guided into the electron gun housing 8 through the focusing lens I9, so that the electron gun emits an ultrafast pulsed electron beam 18 towards the sample 24 under test; the 50°~70° ultrafast pump laser 22 generated by the laser generation module is emitted to the focusing lens II19, and the 50°~70° ultrafast pump laser 22 is focused and guided onto the sample 24 under test on the sample stage through the focusing lens II19, so as to pump and excite the sample 24 under test; Step C.2: Move the via fluorescent screen 35 and via reflector 36 directly below the sample stage, and extend the probe end of the plug-in camera 42 directly below the sample stage; use the probe camera I 40 to capture the transmitted electron signal I 25 generated by the interaction between the ultrafast pulsed electron beam 18 emitted by the electron gun to the sample 24 in step C.1 and the pumped sample 24, which passes sequentially through the via fluorescent screen 35 and via reflector 36, and then the optical signal 38 reflected by the via reflector 36, to achieve... The inverted space information imaging of the sample 24 is performed. The detector end of the plug-in camera 42 is used to receive the transmission electron signal I25 generated by the interaction between the ultrafast pulsed electron beam 18 emitted by the electron gun to the sample 24 in step C.1 and the pumped and excited sample 24. After passing through the through-hole fluorescent screen 35 and the through-hole reflector 36, the transmission electron signal II37 passes through the central through-hole of the two to detect the stability of the electron source, realize the correction of the intensity, displacement and time jitter of the diffraction pattern, and complete the ultrafast electron diffraction mode. (iv) See Figure 5 (D), Imaging mode D: Energy-filtered electron microscopy imaging mode The imaging process is as follows: Step D.1: The laser generation module generates an ultrafast probe laser 7 and a 70°~110° ultrafast pump laser 23; the ultrafast probe laser 7 generated by the laser generation module is emitted to the focusing lens I9, and the ultrafast probe laser 7 is focused and guided into the electron gun housing 8 through the focusing lens I9, so that the electron gun emits an ultrafast pulsed electron beam 18 towards the sample 24 under test; the 70°~110° ultrafast pump laser 23 generated by the laser generation module is emitted to the focusing lens III21, and the 70°~110° ultrafast pump laser 23 is focused and guided onto the sample 24 under test on the sample stage through the focusing lens III21, so as to pump and excite the sample 24 under test; Step D.2: The energy-filtered electron microscope described above is used to receive the ultrafast pulsed electron beam 18 emitted by the electron gun to the sample 24 in step D.1 and the electron signal 41 generated by the interaction between the sample 24 and the pumped sample 24, thereby realizing energy-filtered electron microscopy imaging and completing the energy-filtered electron microscopy imaging mode.

[0046] In summary, the multi-mode, multi-dimensional ultrafast electron microscopy imaging device of this invention can operate in four imaging modes: ultrafast scanning reflection mode, ultrafast scanning transmission mode, ultrafast electron diffraction mode, and energy-filtered electron microscopy imaging mode. It can accurately measure different ultrafast dynamic information such as sample surface / interface carrier information, real space information, reciprocal space information, structural information, band structure information, and electronic state information. This multi-mode, multi-dimensional ultrafast electron microscopy imaging device integrates and couples multiple ultrafast electron imaging functions, enabling high-resolution electron dynamics detection and attosecond electron pulse generation and measurement in multiple modes and dimensions, and has broad prospects for scientific research and application.

Claims

1. A multi-mode, multi-dimensional ultrafast electron microscopy imaging device, characterized in that: It includes a sample chamber (20), an electron gun, a laser generating module, a secondary electron detector (27), a STEM detector (28), an in-chamber pluggable detection assembly (30), a pluggable camera and energy-filtering electron microscope assembly (32), and a vacuum system; The sample chamber (20) is equipped with a sample stage with a hollow center, and at least two ultrafast pump laser introduction windows are provided on its chamber wall. The electron gun is mounted above the sample chamber (20), with its electron optical axis pointing vertically downward and located directly above the sample stage; the electron gun includes an electron gun housing (8); an ultrafast detection laser introduction window is provided on the electron gun housing (8); an objective lens (17) with its optical axis coaxial with the electron gun's electron optical axis is provided in the communicating cavity formed by the sealed connection between the electron gun and the sample chamber (20), located between the lower end of the electron gun and the upper end of the sample chamber (20). The laser generation module is located outside the sample chamber (20) and the electron gun, and is used to generate ultrafast probe laser (7) and ultrafast pump laser; The secondary electron detector (27) is located diagonally above the sample stage inside the sample chamber (20); The STEM detector (28) is installed on the side wall of the sample chamber (20). Its retractable detector probe (29) is horizontal and located in the area below the sample stage inside the sample chamber (20), and can extend and retract between the side wall and directly below the sample stage. The pluggable detection assembly (30) includes a through-hole fluorescent screen (35), a through-hole reflector (36), and a detection camera I (40). The through-hole fluorescent screen (35) and the through-hole reflector (36) are arranged in the area below the STEM detector (28) in the sample chamber (20) with the former above the latter, the through holes of the two being coaxial, and the axis being parallel to the electron optical axis of the electron gun. They can be moved horizontally between the side chamber wall and directly below the sample stage. The detection window of the detection camera I (40) is located in the reflected light path of the through-hole reflector (36). The plug-in camera and energy-filtering electron microscope assembly (32) includes a adapter component I (43) and an energy-filtering electron microscope arranged sequentially from top to bottom below the sample chamber (20), and also includes a plug-in camera (42); the electron entrance end of the energy-filtering electron microscope is sealed and fixedly connected to the opening I located directly below the sample stage on the lower wall of the sample chamber (20) through the adapter component I (43), and the inner cavities of the two are connected; the plug-in camera (42) is installed on the side wall of the adapter component I (43), and its retractable probe extends horizontally into the hollow part inside the adapter component I (43), and can extend and retract between the side wall and directly below the sample stage; The vacuum system is connected to the sample chamber (20) and the inner cavity of the electron gun.

2. The multi-mode, multi-dimensional ultrafast electron microscopy imaging device according to claim 1, characterized in that: Definition: The direction parallel to and opposite to the electron optical axis of the electron gun is the positive Z-axis of the spatial coordinate system XYZ; the direction of the shortening direction of the detector probe (29) intersecting the Z-axis and parallel to the STEM detector (28) is the positive Y-axis of the spatial coordinate system XYZ; the positive X-axis of the spatial coordinate system XYZ is determined by the left-hand rule; the rotations about axes parallel to the X-axis, Y-axis, and Z-axis are α rotation, β rotation, and R rotation, respectively; The sample stage is a six-dimensional sample stage with a hollow center, which allows the sample to be tested (24) to move along the X-axis, Y-axis, and Z-axis, as well as rotate α, β, and R. The detection camera I (40) is installed on the side wall of the sample chamber (20); The fluorescent surface of the through-hole fluorescent screen (35) is horizontal and facing upward, and the distance between its upper surface and the sample placement surface of the sample stage in a horizontal state is 150.15 mm ± 7 mm; the reflective surface of the through-hole reflector (36) faces upward. The distance between the receiving surface of the plug-in camera (42) and the sample placement surface of the horizontally positioned sample stage is 327.65 mm ± 7 mm.

3. The multi-mode, multi-dimensional ultrafast electron microscopy imaging device according to claim 2, characterized in that: The plug-in camera and energy-filtering electron microscope assembly (32) also includes a vacuum tube and a magnetic lens I (31). The vacuum pipe is located between the sample chamber (20) and the adapter component I (43); the adapter component I (43) is sealed and fixedly connected to the sample chamber (20) directly below the opening I through the vacuum pipe, and the electron entrance end of the energy filter electron microscope is sealed and fixedly connected to the sample chamber (20) directly below the opening I through the vacuum pipe and the adapter component I (43), and the inner cavities of the two are connected. The magnetic lens I (31) is mounted on the outer cylindrical surface of the vacuum pipe and is used to laterally focus the transmitted electronic signal and the electronic signal to be analyzed (41).

4. The multi-mode, multi-dimensional ultrafast electron microscopy imaging device according to claim 3, characterized in that: The sample stage includes an α rotary stage, a Z displacement component, a transition component II (58), an R rotary stage (59), an X / Y displacement component (61), a β rotary stage (63), and a sample holder (65). The Z-displacement component includes a Z-displacement base layer and a Z-displacement stage (57); the Z-displacement base layer is rotatably connected to the door set on the side wall of the sample chamber (20) via an α-rotating stage, and can rotate α relative to the door set on the side wall of the sample chamber (20); The Z-displacement stage (57) is linearly slidably connected to the Z-displacement base layer and can slide relative to it along the Z-axis direction; The adapter component II (58) is fixedly connected to the lower end of the side of the Z displacement stage (57) away from the Z displacement base layer, forming an L-shaped structure with the Z displacement stage (57); The R rotary stage (59), X / Y displacement component (61), β rotary stage (63) and sample holder (65) are arranged sequentially from bottom to top on the upper surface of the L-shaped horizontal arm. The rotation axis of the R rotary table (59) is coplanar with the rotation axis of the α rotary table; The X / Y displacement component (61) is located in the middle of the upper surface of the R rotary table (59), and includes an X / Y displacement base layer, an X displacement stage, and a Y displacement stage arranged sequentially from bottom to top; the X / Y displacement base layer is rotatably connected to the adapter component II (58) through the R rotary table (59), and can rotate relative to the adapter component II (58); the X displacement stage is linearly slidably connected to the X / Y displacement base layer, and can slide relative to it along the X-axis; the Y displacement stage is linearly slidably connected to the X displacement stage, and can slide relative to it along the Y-axis. The β rotary stage (63) is set on the Y displacement stage and located on one side of the rotation axis of the R rotary stage (59) in the positive or negative direction of the Y axis. It includes a bottom β rotary stage and a top β rotary stage arranged from bottom to top. The bottom β rotary stage is fixedly connected to the Y displacement stage. Its upper surface is provided with an arc-shaped cylindrical track with an axis parallel to the Y axis and coplanar with the rotation axis of the R rotary stage (59). The lower surface of the top β rotary stage is provided with a cylindrical surface adapted to the arc-shaped cylindrical track. The top β rotary stage and the bottom β rotary stage are rotatably connected and can rotate at a preset angle β relative to the bottom β rotary stage in a swinging manner. The sample holder (65) is horizontally arranged along the Y-axis, with one end fixed to the upper surface of the top layer of the β rotary stage and the other end suspended directly above the rotation axis of the R rotary stage (59). A hollow sample stage structure (64) is provided on the sample stage with the rotation axis of the R rotary stage (59) as the center axis, extending from the lower surface of the adapter component II (58) to the lower surface of the sample holder (65). Multiple spaced and vertically connected sample holes (66) are provided on the other end of the sample holder (65) to form a hollow sample stage. The other end of the sample holder (65) is used to install the sample to be tested (24).

5. The multi-mode, multi-dimensional ultrafast electron microscopy imaging device according to claim 4, characterized in that: The sample stage also includes adapter component III (60) and adapter component IV (62). The adapter component Ⅲ (60) is located between the X / Y displacement base layer and the R rotary table (59). The X / Y displacement base layer is fixedly connected to the adapter component Ⅲ (60) and is rotatably connected to the adapter component Ⅱ (58) through the adapter component Ⅲ (60) and the R rotary table (59). The adapter component Ⅳ (62) is located between the bottom layer of the β rotary table and the Y displacement table, and is located on one side of the Y axis of the rotation axis of the R rotary table (59) pointing in the positive or negative direction; the bottom layer of the β rotary table is fixedly connected to the Y displacement table through the adapter component Ⅳ (62).

6. The multi-mode, multi-dimensional ultrafast electron microscopy imaging device according to claim 3, characterized in that: The in-cabin pluggable detection assembly (30) also includes a pluggable control assembly (33) and a relay optical lens assembly (39). The insertion and removal control assembly (33) is installed opposite to the detection camera I (40) on the outside of the side wall of the sample chamber (20), and its telescopic rod (34) extends horizontally into the sample chamber (20); by fixing the through-hole fluorescent screen (35) and the through-hole reflector (36) to the free end of the telescopic rod (34), it can move horizontally between the side wall and directly below the sample stage; The through-hole reflector (36) is a 45° through-hole reflector; The relay optical lens assembly (39) is located in the reflected light path of the through-hole reflector (36) and is installed on the inner and outer sides of the same side wall of the sample chamber (20) as the detection camera I (40). The beam diameter of the light signal is adjusted by the relay optical lens assembly (39) to match the detection window of the detection camera I (40).

7. The multi-mode, multi-dimensional ultrafast electron microscopy imaging device according to any one of claims 1 to 6, characterized in that: The electron gun also includes a cathode filament (10), a grid electrode (11), an anode (12), a high-voltage accelerating tube (13), a condenser lens I (14), a condenser lens II (15), and a scanning coil (16) arranged sequentially along the electron optical axis inside the electron gun housing (8). The ultrafast detection laser introduction window is a focusing lens I (9), used to focus the ultrafast detection laser (7) onto the cathode filament (10) inside the electron gun housing (8); the accelerating voltage between the gate electrode (11) and the anode (12) is adjustable from 0V to 30kV; The objective lens (17) is an electrostatic electromagnetic composite lens; The sample chamber (20) has two ultrafast pump laser introduction windows on its walls, and the two ultrafast pump laser introduction windows are focusing lens II (19) and focusing lens III (21), respectively. The optical axes of focusing lens II (19) and focusing lens III (21) are 50°~70° and 70°~110° with the electron optical axis of the electron gun, respectively. They are used to focus the 50°~70° ultrafast pump laser (22) and 70°~110° ultrafast pump laser (23) onto the sample to be tested (24) on the sample stage.

8. The multi-mode, multi-dimensional ultrafast electron microscopy imaging device according to claim 7, characterized in that: The laser generating module includes a laser (1), a beam splitter (3), a frequency doubling component (6) and a reflector I (67) arranged sequentially along the optical path, and a laser pulse delay control component (5), a reflector II (68) and a reflector III (69) arranged sequentially along the transmission optical path of the beam splitter (3). The laser (1) is used to generate an ultrafast laser beam (2); The frequency doubling component (6) is used to perform frequency conversion on the ultrafast laser beam reflected by the beam splitter (3) to obtain an ultrafast probe laser (7). The focusing lens I (9) is located on the reflected light path of the reflector I (67). The ultrafast detection laser (7) generated by the laser generation module is emitted to the focusing lens I (9) through the reflector I (67). The ultrafast detection laser (7) is focused by the focusing lens I (9) and directed to the cathode filament (10) inside the electron gun housing (8). The laser pulse delay control component (5) is used to perform wavelength conversion and time control on the ultrafast laser beam in the transmission optical path of the beam splitter (3) to obtain a pump-probe synchronized ultrafast pump laser. The focusing lens II (19) is located on the reflected light path of the reflecting mirror III (69); The focusing lens Ⅲ (21) is located on the optical axis of the output end of the laser pulse delay control component (5), and is distributed on both sides of the reflecting mirror Ⅱ (68) along with the laser pulse delay control component (5); The reflector II (68) is removable; When the reflector II (68) is working, the ultrafast pump laser of pump-probe synchronization is converted into 50°~70° ultrafast pump laser (22) through the reflector II (68) and the reflector III (69) and emitted to the focusing lens II (19). The 50°~70° ultrafast pump laser (22) is focused by the focusing lens II (19) and directed to the sample to be tested (24) on the sample stage. After the reflector II (68) is removed, the ultrafast pump laser obtained by the pump-probe synchronization through the laser pulse delay control component (5) is emitted as the 70°~110° ultrafast pump laser (23) to the focusing lens III (21), and the 70°~110° ultrafast pump laser (23) is focused and guided to the sample to be tested (24) on the sample stage by the focusing lens III (21).

9. The multi-mode, multi-dimensional ultrafast electron microscopy imaging device according to claim 8, characterized in that: It also includes a backscattered electron detector, an energy-dispersive X-ray detector, an optical navigation camera, and a plasma cleaning device, all mounted on the sample chamber (20) via flange interfaces. The energy-filtering electron microscope includes an energy-filtering electron microscope tube (44), a dipole magnet (45), a magnetic lens II (49), an energy slit (50), a magnetic lens III (51), a magnetic lens IV (52), a magnetic lens V (53), a magnetic lens VI (54), and a magnetic lens VII (55) arranged sequentially along the electron optical axis within the energy-filtering electron microscope tube (44), and also includes a detection camera II (56) with its detection window facing the electron emission port end of the energy-filtering electron microscope tube (44) and located outside the energy-filtering electron microscope tube (44).

10. An imaging method for the multi-mode, multi-dimensional ultrafast electron microscopy imaging apparatus according to any one of claims 1 to 9, characterized in that, Includes the following steps: Step 1: Construct a multi-mode, multi-dimensional ultrafast electron microscopy imaging device. During construction, the ultrafast detection laser introduction window on the electron gun shell (8) is set as a focusing lens I (9), and two ultrafast pump laser introduction windows are set on the sample chamber (20) wall. The two ultrafast pump laser introduction windows are focusing lenses II (19) and III (21), respectively. The angles between the optical axes of focusing lenses II (19) and III (21) and the electron optical axis of the electron gun are 50°~70° and 70°~110°, respectively. Then, the retractable parts in each component of the constructed multi-mode, multi-dimensional ultrafast electron microscopy imaging device are all in the retracted state, and each component is in the closed state or the non-working standby state. Step 2: Install the sample to be tested (24) onto the sample stage of the multi-mode multi-dimensional ultrafast electron microscopy imaging device in the standby state where each component is in the off state or non-working state in Step 1, and then close the door of the sample chamber (20). Step 3: Using the vacuum system, evacuate the inner cavity of the sample chamber (20) and electron gun in the multi-mode multi-dimensional ultrafast electron microscopy imaging device, which was closed in Step 2, so that the inner cavity of both is evacuated to and maintained at the required vacuum level. Step 4: Based on the detection requirements of the sample to be tested (24) installed on the sample stage in Step 2, select the imaging operation process from the following four imaging modes. After each imaging mode is executed, if the imaging mode contains multiple sub-imaging modes, after each sub-imaging mode is executed, the retractable components of each component in the multi-mode multi-dimensional ultrafast electron microscopy imaging device constructed in Step 1 are all in a retracted state, and each component is in a closed state or a non-working standby state. The four imaging modes are: Imaging Mode A: Ultrafast Scan Reflection Mode The imaging process is as follows: Step A.1: The laser generation module generates an ultrafast probe laser (7) and a 50°~70° ultrafast pump laser (22); the ultrafast probe laser (7) generated by the laser generation module is emitted to the focusing lens I (9), and the ultrafast probe laser (7) is focused and guided into the electron gun housing (8) through the focusing lens I (9) so that the electron gun emits an ultrafast pulsed electron beam (18) towards the sample to be tested (24); the 50°~70° ultrafast pump laser (22) generated by the laser generation module is emitted to the focusing lens II (19), and the 50°~70° ultrafast pump laser (22) is focused and guided onto the sample to be tested (24) on the sample stage through the focusing lens II (19) so as to pump and excite the sample to be tested (24); Step A.2: The secondary electron detector (27) is used to receive the secondary electrons (26) generated by the interaction between the ultrafast pulsed electron beam (18) emitted by the electron gun to the sample (24) in step A.1 and the pumped sample (24), so as to realize the surface morphology and carrier imaging and complete the ultrafast scanning reflection mode. Imaging Mode B: Ultrafast Scan Transmission Mode The imaging mode B is divided into two sub-imaging modes: sub-imaging mode B1 and sub-imaging mode B2; Sub-imaging mode B1: Ultrafast conventional scanning transmission mode The imaging process is as follows: Step B1.1: The laser generation module generates an ultrafast probe laser (7) and a 50°~70° ultrafast pump laser (22); the ultrafast probe laser (7) generated by the laser generation module is emitted to the focusing lens I (9), and the ultrafast probe laser (7) is focused and guided into the electron gun housing (8) through the focusing lens I (9) so that the electron gun emits an ultrafast pulsed electron beam (18) towards the sample to be tested (24); the 50°~70° ultrafast pump laser (22) generated by the laser generation module is emitted to the focusing lens II (19), and the 50°~70° ultrafast pump laser (22) is focused and guided onto the sample to be tested (24) on the sample stage through the focusing lens II (19) so as to pump and excite the sample to be tested (24); Step B1.2: Extend the detector probe (29) of the STEM detector (28) to directly below the sample stage, so that it receives the transmission electron signal I (25) generated by the interaction between the ultrafast pulsed electron beam (18) emitted by the electron gun to the sample (24) in step B1.1 and the pumped and excited sample (24), so as to realize the topographic imaging and complete the ultrafast conventional scanning transmission mode. Sub-imaging mode B2: Ultrafast four-dimensional scanning transmission mode The imaging process is as follows: Step B2.1: The laser generation module generates an ultrafast probe laser (7) and a 50°~70° ultrafast pump laser (22); the ultrafast probe laser (7) generated by the laser generation module is emitted to the focusing lens I (9), and the ultrafast probe laser (7) is focused and guided into the electron gun housing (8) through the focusing lens I (9) so that the electron gun emits an ultrafast pulsed electron beam (18) towards the sample to be tested (24); the 50°~70° ultrafast pump laser (22) generated by the laser generation module is emitted to the focusing lens II (19), and the 50°~70° ultrafast pump laser (22) is focused and guided onto the sample to be tested (24) on the sample stage through the focusing lens II (19) so as to pump and excite the sample to be tested (24); Step B2.2: Extend the probe end of the plug-in camera (42) to directly below the sample stage so that it can receive the transmission electron signal I (25) generated by the interaction between the ultrafast pulsed electron beam (18) emitted by the electron gun to the sample (24) in step B2.1 and the pumped and excited sample (24), so as to realize ultrafast four-dimensional scanning transmission electron microscopy imaging and complete the ultrafast four-dimensional scanning transmission mode. Imaging mode C: Ultrafast electron diffraction mode The imaging process is as follows: Step C.1: The laser generation module generates an ultrafast probe laser (7) and a 50°~70° ultrafast pump laser (22); the ultrafast probe laser (7) generated by the laser generation module is emitted to the focusing lens I (9), and the ultrafast probe laser (7) is focused and guided into the electron gun housing (8) through the focusing lens I (9) so that the electron gun emits an ultrafast pulsed electron beam (18) towards the sample to be tested (24); the 50°~70° ultrafast pump laser (22) generated by the laser generation module is emitted to the focusing lens II (19), and the 50°~70° ultrafast pump laser (22) is focused and guided onto the sample to be tested (24) on the sample stage through the focusing lens II (19) so as to pump and excite the sample to be tested (24); Step C.2: Move the through-hole fluorescent screen (35) and through-hole reflector (36) directly below the sample stage, and extend the probe end of the plug-in camera (42) directly below the sample stage; use the probe camera I (40) to capture the transmitted electron signal I (25) generated by the interaction between the ultrafast pulsed electron beam (18) emitted by the electron gun to the sample (24) in step C.1 and the pumped and excited sample (24), which passes through the through-hole fluorescent screen (35) and through-hole reflector (36) in sequence, and the optical signal (38) reflected by the through-hole reflector (36). To achieve inverted space information imaging of the sample to be tested (24); the probe end of the plug-in camera (42) receives the transmission electron signal I (25) generated by the interaction between the ultrafast pulsed electron beam (18) emitted by the electron gun to the sample to be tested (24) in step C.1 and the pumped and excited sample to be tested (24). After passing through the through-hole fluorescent screen (35) and the through-hole reflector (36) in sequence, the transmission electron signal II (37) passes through the through hole in the center of the two to detect the stability of the electron source, realize the correction of the intensity, displacement and time jitter of the diffraction pattern, and complete the ultrafast electron diffraction mode; Imaging Mode D: Energy-Filtered Electron Microscopy Imaging Mode The imaging process is as follows: Step D.1: The laser generation module generates an ultrafast probe laser (7) and a 70°~110° ultrafast pump laser (23); the ultrafast probe laser (7) generated by the laser generation module is emitted to the focusing lens I (9), and the ultrafast probe laser (7) is focused and guided into the electron gun housing (8) through the focusing lens I (9) so that the electron gun emits an ultrafast pulsed electron beam (18) towards the sample to be tested (24); the 70°~110° ultrafast pump laser (23) generated by the laser generation module is emitted to the focusing lens III (21), and the 70°~110° ultrafast pump laser (23) is focused and guided onto the sample to be tested (24) on the sample stage through the focusing lens III (21) so as to pump and excite the sample to be tested (24); Step D.2: The energy-filtered electron microscope is used to receive the ultrafast pulsed electron beam (18) emitted by the electron gun to the sample (24) in step D.1 and the electron signal (41) generated by the interaction between the sample (24) and the pumped sample, thereby realizing energy-filtered electron microscopy imaging and completing the energy-filtered electron microscopy imaging mode.

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