Femtosecond ultrafast diffraction imaging system and method based on X-ray free electron laser

Abstract

The invention provides a femtosecond ultrafast diffraction imaging system and method based on X-ray free electron laser, and relates to the field of X-ray free electron laser. The femtosecond ultrafast diffraction imaging system of the X-ray free electron laser comprises an X-ray light source used for emitting the X-ray free electron laser; the light path focusing mechanism is arranged on the X-ray free electron laser light path and is used for focusing the X-ray free electron laser; the light control mechanism is arranged on the light path of the X-ray free electron laser focused by the light path focusing mechanism and forms a light control slit; the sample target is arranged at the focal point of the X-ray free electron laser; the sample target is arranged at the focal point of the X-ray free electron laser; the single-photon response detection mechanism is arranged in a diffraction light path generated after the sample is bombarded by the X-ray free electron laser and is used for collecting a diffraction pattern; and the phase workstation is electrically connected with the single-photon response detection mechanism and is used for acquiring diffraction pattern data and performing phase recovery.

Description

Technical Field

[0001] The invention relates to the field of X-ray free electron laser experiments, and in particular to a femtosecond ultrafast diffraction imaging system and method based on X-ray free electron laser. Background Art

[0002] X-ray free electron laser is a scientific research device based on linear electron accelerator, which can produce femtosecond pulse width, ultra-high brightness and fully coherent X-ray laser, and the wavelength can cover the range from far infrared to X-ray band, providing unprecedented opportunities for cutting-edge scientific research in physics, chemistry, life science, materials science and other fields. Therefore, the development of advanced methodology based on X-ray free electron laser can not only expand the ability and level of methodology, but also be widely used in basic scientific research, which has broad practical significance. Among them, coherent diffraction imaging is an advanced lensless imaging method that can achieve three-dimensional imaging of micron-sized crystals, with a spatial resolution of up to ten nanometers, and has a high degree of recognition of atomic displacement and strain in crystals, and has broad application prospects. The energy of free electron laser in the soft X-ray band is generally between 100 and 1000 eV, which is suitable for diffraction research of long-period structures.

[0003] The crystal structure is a periodic structure formed by the orderly arrangement of atoms. Similar to this is the superlattice structure, which is a periodic structure formed by the orderly arrangement of small particles of similar shapes. The superlattice structure is easy to control and suitable for regulating performance. It has broad application prospects in engineering, chemical engineering and optics. At the same time, the superlattice structure has a rich topological structure, which is suitable for research and development in the field of topology. For example, the 2016 Nobel Prize was awarded for the results in the field of two-dimensional topology. However, due to the time resolution capability of the detection method, most of the related research is concentrated on the time scale of microseconds, and is powerless to key scientific problems on a faster time scale, using electron microscopes that have strict requirements on samples. For example, the speed of electron transfer in atoms is usually less than 1 picosecond, while the time scale of magnetic phase transition is usually tens of picoseconds. Therefore, how to study superlattice structures on a faster time scale has always been a difficult problem.

[0004] In summary, there is a need for an imaging system that can study superlattice structures on a femtosecond scale. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a femtosecond ultrafast diffraction imaging system of an X-ray free electron laser, which can study superlattice structures on a femtosecond scale.

[0006] The femtosecond ultrafast diffraction imaging system of X-ray free electron laser provided by the present invention comprises an X-ray light source for emitting X-ray free electron laser; an optical path focusing mechanism, which is arranged on the optical path of the X-ray free electron laser and is used to focus the X-ray free electron laser; a light control mechanism, which is arranged on the optical path of the X-ray free electron laser after being focused by the optical path focusing mechanism and forms a light control slit for controlling the light transmittance of the X-ray free electron laser; a sample target, which is arranged at the focus of the X-ray free electron laser; the sample target, which is arranged at the focus of the X-ray free electron laser; the sample target comprises a plurality of target areas, in which samples are arranged, and a diffraction optical path is generated after the X-ray free electron laser forms a light spot on the sample; a single photon response detection mechanism, which is arranged in the diffraction optical path generated after the X-ray free electron laser bombards the sample and is used to collect diffraction patterns; a phase workstation, which is electrically connected to the single photon response detection mechanism and is used to collect diffraction pattern data and perform phase recovery.

[0007] In a feasible embodiment, the optical path focusing mechanism includes a first focusing mirror and a second focusing mirror arranged in the X-ray free electron laser optical path; the first focusing mirror and the second focusing mirror are arranged relative to the light beam of the X-ray free electron laser and focus the X-ray free electron laser on the sample target.

[0008] In a feasible implementation manner, the light control mechanism includes a first baffle and a second baffle disposed in the X-ray free electron laser light path, and the light control slit is formed between the first baffle and the second baffle.

[0009] In a feasible implementation manner, the sample target includes an adjustment mechanism and a sample target disposed above the adjustment mechanism; the sample target includes a plurality of target areas, and samples are disposed in the target areas.

[0010] In a feasible embodiment, the single-photon response detector includes a supporting platform and a single-photon response detector arranged on the displacement platform; the single-photon response detector includes a first diffraction light plate, a zero-order diffraction light plate and a second diffraction light plate arranged in the diffraction light path; the first diffraction light plate and the second diffraction light plate are arranged relative to the light beam of the X-ray free electron laser and are located in the diffraction light area of ​​the diffraction light path, the zero-order diffraction light plate is arranged in the straight-through area of ​​the diffraction light path, and a light blocking plate is also arranged in front of the zero-order diffraction light plate.

[0011] In a feasible implementation manner, the diameter of the X-ray free electron laser spot on the sample target is 1-20 μm.

[0012] In a feasible embodiment, the materials of the first focusing reflector and the second focusing reflector are independently selected from KB mirror, Fresnel zone plate or X-ray combined refractive lens.

[0013] In a feasible embodiment, the materials of the first baffle and the second baffle are independently selected from single crystal silicon, boron carbide or tungsten carbide; and / or the width of the light-controlling slit is >50μm, the movement accuracy of the first baffle and the second baffle is <1μm, and the movement resolution of the first baffle and the second baffle is <0.2μm.

[0014] In a feasible implementation, the operating frequency of the single photon response detector is >2 Hz, and the resolution of the single photon response detector is >2k.

[0015] In a feasible implementation manner, the sample target is a silicon nitride film window; and / or the number of the target areas is 10 to 30.

[0016] In a feasible implementation manner, the distance between the light control mechanism and the sample target is 100-1000 mm.

[0017] The femtosecond ultrafast diffraction imaging system of an X-ray free electron laser provided by the present invention has the following beneficial effects: the present invention utilizes the femtosecond pulse of an X-ray free electron laser and adopts a method combining plane wave coherent diffraction imaging with Bragg coherent diffraction imaging to study the changes in the three-dimensional morphology and strain structure of a superlattice at the femtosecond level, can realize continuous observation of superlattice materials at the femtosecond level, carry out ultrafast experiments to study key dynamic behaviors, can realize observation of changes in the three-dimensional morphology of samples on a femtosecond time scale, and quantitatively analyze the distribution of the strain field inside the crystal, and can accurately capture changes in the crystal structure in three-dimensional space and on an ultrafast time scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a side view of the overall structure of the present invention.

[0019] Figure 2 It is a schematic diagram of the structure of the sample target in the present invention.

[0020] Reference numerals

[0021] X-ray source 1

[0022] Optical path focusing mechanism 2

[0023] First focusing mirror 21

[0024] Second focusing mirror 22

[0025] Light control mechanism 3

[0026] The first baffle 31

[0027] Second baffle 32

[0028] Light control slit 33

[0029] Sample target 4

[0030] Target Area 41

[0031] Sample 42

[0032] Single photon response detection mechanism 5

[0033] Support platform 51

[0034] Single photon response detector 52

[0035] First diffraction light plate 52.1

[0036] Zero-order diffraction light plate 52.2

[0037] The second diffraction light plate 52.3

[0038] Light barrier 53

[0039] Phase Workstation 6

[0040] Fine adjustment mechanism 7

[0041] Coarse adjustment mechanism 8

[0042] Angle adjustment mechanism 9 DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without creative work belong to the scope of protection of the present invention. In the description of the present invention, it should be noted that the orientation or position relationship indicated by the terms "left side", "right side", "upper side", "lower side", "above", "below" and the like is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0044] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0045] Furthermore, in the description of the present invention, unless otherwise specified, “plurality” means two or more.

[0046] The embodiment of the present invention provides a femtosecond ultrafast diffraction imaging system based on X-ray free electron laser, referring to Figure 1 , including: an X-ray light source 1, used to emit X-ray free electron laser; an optical path focusing mechanism 2, arranged on the X-ray free electron laser optical path, used to focus the X-ray free electron laser; a light control mechanism 3, arranged on the X-ray free electron laser optical path after being focused by the optical path focusing mechanism 2 and forming a light control slit 33, used to control the light transmittance of the X-ray free electron laser; a sample target 4, arranged at the focus of the X-ray free electron laser, the sample target 4 includes a plurality of target areas 41, a sample 42 is arranged in the target area 41, and the X-ray free electron laser forms a diffraction optical path after forming a light spot on the sample 42; a single photon response detection mechanism 5, arranged in the diffraction optical path generated after the X-ray free electron laser bombards the sample 42, and used to collect diffraction patterns; a phase workstation 6, electrically connected to the single photon response detection mechanism 5, used to collect diffraction pattern data and perform phase recovery, and the phase workstation 6 is usually a computer. The present invention utilizes femtosecond pulses of X-ray free electron lasers and adopts a method that combines plane wave coherent diffraction imaging with Bragg coherent diffraction imaging to study the changes in the three-dimensional morphology and strain structure of superlattices at the femtosecond level. It can achieve continuous observation of superlattice materials at the femtosecond level, carry out ultrafast experiments to study key dynamic behaviors, observe changes in the three-dimensional morphology of sample 42 on a femtosecond time scale, and quantitatively analyze the distribution of the strain field inside the crystal, and can accurately capture changes in the crystal structure in three-dimensional space and on an ultrafast time scale.

[0047] In the femtosecond ultrafast diffraction imaging system provided in the embodiment of the present invention, refer to Figure 1, the optical path focusing mechanism 2 includes a first focusing reflector 21 and a second focusing reflector 22 arranged in the optical path of the X-ray free electron laser, the first focusing reflector 21 and the second focusing reflector 22 are arranged relative to the beam of the X-ray free electron laser and focus the X-ray free electron laser on the sample target 4. In the present invention, the focal length of the X-ray free electron laser is adjusted by adjusting the angles of the first focusing reflector 21 and the second focusing reflector 22 to ensure that the focal length of the X-ray free electron laser can be located at the position of the sample target 4. Generally speaking, the angles between the first focusing reflector 21 and the second focusing reflector 22 and the X-ray free laser are the same. Further, the materials of the first focusing reflector 21 and the second focusing reflector 22 are independently selected from KB mirrors, Fresnel zone plates or X-ray combined refractive lenses, preferably KB mirrors, because the light propagation efficiency of KB mirrors is the highest and the light intensity of the light spot after focusing is higher.

[0048] In the femtosecond ultrafast diffraction imaging system provided in the embodiment of the present invention, refer to Figure 1 , the light control mechanism 3 includes a first baffle 31 and a second baffle 32 arranged in the optical path of the X-ray free electron laser, and the light control slit 33 is formed between the first baffle 31 and the second baffle 32. When in use, the first baffle 31 and the second baffle 32 synchronously approach or move away from the light beam of the X-ray free electron laser. The middle area of ​​the X-ray free electron laser is the fully coherent part, and the edge area is the incoherent stray light. The function of the light control slit 33 is to allow the fully coherent part of the X-ray free electron laser to pass through and filter out the stray light of the X-ray free electron laser. In a specific embodiment, the materials of the first baffle 31 and the second baffle 32 are independently selected from single crystal silicon, boron carbide or tungsten carbide, preferably tungsten carbide. In a specific embodiment, the width of the light-controlling slit is >50 μm, where the width is the gap width between the first baffle 31 and the second baffle 32. The movement accuracy of the first baffle 31 and the second baffle 32 is <1 μm, where the movement accuracy is the minimum step length during movement. The movement resolution of the first baffle and the second baffle 32 is <0.2 μm, where the movement resolution refers to the error value during movement.

[0049] In the femtosecond ultrafast diffraction imaging system provided in the embodiment of the present invention, refer to Figure 1 The sample target 4 is provided with a fine adjustment mechanism 7, a coarse adjustment mechanism 8 and an angle adjustment mechanism 9 in sequence below the sample target 4. The coarse adjustment mechanism 8 and the fine adjustment mechanism 7 can realize the movement of the sample target 4 in three directions of XYZ. The resolution of the fine adjustment mechanism 7 is ≤10nm, and the resolution of the coarse adjustment mechanism 8 is ≤1μm. The moving direction can be referred to Figure 1, the angle adjustment mechanism 9 can realize the rotation adjustment of the sample target 4 around the three directions of X, Y and Z. The purpose of the rotation along the X-axis and Y-axis is to find the diffraction surface of the sample 42, and the rotation along the Z-axis is the scanning direction. The resolution of the angle adjustment mechanism 9 is ≤0.1°. In a specific embodiment, the stroke of the coarse adjustment mechanism 8 in the X and Y directions is greater than ±100mm, the stroke in the Z direction is greater than ±50mm, and the overall load is greater than 0.6kg; the stroke of the fine adjustment mechanism 7 in the X and Y directions is greater than ±10μm, the resolution is ≤10nm, the stroke in the Z direction is greater than ±5μm, the resolution is ≤10nm, and the overall load is greater than 0.5kg; the rotation range of the angle adjustment mechanism 9 along the X and Y axes is greater than 15°, the resolution is better than 0.1°, the rotation range along the Z axis is greater than 360°, the resolution is better than 0.001°, and the overall load is greater than 1kg. In a preferred embodiment, the angle adjustment mechanism 9 can use Huber's integrated angle translation stage, which includes a two-axis bow angle translation stage 5203.80 and a single-axis rotation translation stage 480 connected up and down; the coarse adjustment mechanism 8 can use Huber's integrated linear translation stage, which includes an XY translation stage 5102.50 and a Z translation stage 2103.D40 connected up and down; the fine adjustment mechanism 7 can use SmarAct's integrated piezoelectric translation stage, which includes an XY translation stage PLF3232-xy.60 and a Z translation stage PLF3232-z.60 connected up and down.

[0050] In the femtosecond ultrafast diffraction imaging system provided in the embodiment of the present invention, refer to Figure 1 The sample target 4 includes an adjustment mechanism and a sample target 4 disposed above the adjustment mechanism. The sample target 4 includes a plurality of target areas 41, and a sample 42 is disposed in the target area 41. As an illustration, when the X-ray free electron laser passes through the sample 42, a diffraction light path is generated. The diffraction light paths generated for different samples 42 are also different. Therefore, if different diffraction light paths are to be collected, different samples 42 must be disposed in the plurality of target areas 41. The spot of the X-ray free electron laser is usually only located on the sample 42 in one target area 41, that is, the X-ray free electron laser usually irradiates only one sample 42 in each experiment. When the spot of the X-ray free electron laser is to fall on different samples 42, the position of the sample target 4 can be moved by controlling the fine adjustment mechanism 7 and the coarse adjustment mechanism 8, so that different samples 42 are aligned with the spot of the X-ray free electron laser. In a specific embodiment, the sample target 4 is a silicon nitride film window. In another specific embodiment, the number of the target areas 41 is 10 to 30, preferably 25.

[0051] In the femtosecond ultrafast diffraction imaging system provided in the embodiment of the present invention, refer to Figure 1The single-photon response detector includes a supporting platform 51 and a single-photon response detector 52 arranged on a displacement platform, and the single-photon response detector 52 includes a first diffraction light plate 52.1, a zero-order diffraction light plate 52.2 and a second diffraction light plate 52.3 arranged in the diffraction light path; the first diffraction light plate 52.1 and the second diffraction light plate 52.3 are arranged relative to the light beam of the X-ray free electron laser and are located in the diffraction light area of ​​the diffraction light path, the zero-order diffraction light plate 52.2 is arranged in the straight-through area of ​​the diffraction light path, and a light blocking plate 53 is also arranged in front of the zero-order diffraction light plate 52.2. After passing through the sample target 4, the X-ray free electron laser forms a diffraction light path, where the diffraction light path is divided into two regions, namely the diffraction light region and the direct light region. The diffraction light in the diffraction light region hits the first diffraction light plate 52.1 and the second diffraction light plate 52.3 and forms a light spot, which is the Bragg diffraction pattern of the sample 42. The diffraction light in the direct light region first hits the light shielding plate 53, and then the light wave bypasses the light shielding plate 53 to form a secondary diffraction light again. This part of the secondary diffraction light hits the zero-order diffraction light plate 52.2 and forms a light spot. The light spot formed by the secondary diffraction light is the zero-order diffraction pattern of the sample 42. In a specific embodiment, the operating frequency of the single-photon response detector 52 is greater than 2Hz, the pixel size is greater than 2K pixels, the distance between the single-photon response detector 52 and the sample target 4 is 100-1000mm, and the step accuracy is less than 1mm. As an illustration, the distance between the single photon response detector 52 and the sample target 4 is usually determined by the size of the sample 42, and needs to satisfy that the sampling frequency is greater than the Nyquist frequency, and generally requires an oversampling rate greater than 2. In actual measurement, it is generally required that each diffraction edge has at least two pixels. For example, for a sample 42 of 2 mm size, a 15 mm pixel size detector is placed at 166 mm, and an oversampling rate of 30 can be achieved. This embodiment also provides a method for using a femtosecond ultrafast diffraction imaging system based on an X-ray free electron laser, which includes at least the following steps:

[0052] 1) Preparation and calibration of the optical path, adjusting the position of the sample target 4 to align the center of the light spot with the sample 42; since the light spot of the X-ray free electron laser used in this experiment is at the micron level, it is necessary to determine the position of the light spot on the sample 42 before the experiment, which will help to screen the experimental samples 42 of interest during the experiment; by controlling the coarse adjustment mechanism 8, the fine adjustment mechanism 7 and the angle adjustment mechanism 9, the position and angle of the sample target 4 relative to the light spot can be adjusted, and the sample 42 to be tested in the sample target 4 can be moved to the exact center of the light spot.

[0053] 2) Collecting diffraction spots, bombarding the sample 42 with X-ray free electrons, and collecting the Bragg diffraction pattern and the zero-order diffraction pattern through the single photon response detector 52 .

[0054] 3) Phase recovery: perform phase recovery on the Bragg diffraction pattern and the zero-order diffraction pattern to obtain high-resolution morphological imaging and internal strain imaging, respectively. The mainstream method of phase recovery is to use an iterative algorithm to cyclically perform fast Fourier transform on the diffraction spot in reciprocal space and positive space. The restriction in the reciprocal space is the amplitude information obtained from the diffraction pattern, and the restriction in the positive space is the estimated crystal boundary. In each cycle in the reciprocal space, the amplitude is rewritten to the amplitude of the measured diffraction pattern, while the phase information is retained. After a sufficient number of cyclic iterations, the algorithm converges to obtain the final reconstruction result. Through this method, the three-dimensional morphological structure of sample 42 can be obtained, and the theoretical limiting resolution can reach the size of the superlattice unit, which generally ranges from a few nanometers to tens of nanometers. As an illustration, the core of phase recovery is the image processing algorithm. There are currently many image processing algorithms that can achieve phase recovery, and they will not be given one by one here.

[0055] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A femtosecond ultrafast diffraction imaging system based on X-ray free electron laser, characterized in that: include: An X-ray light source (1) for emitting X-ray free electron laser; An optical path focusing mechanism (2) is arranged on the optical path of the X-ray free electron laser and is used to focus the X-ray free electron laser; A light control mechanism (3) is arranged on the optical path of the X-ray free electron laser after being focused by the optical path focusing mechanism (2) and forms a light control slit (33) for controlling the light transmittance of the X-ray free electron laser; A sample target (4) is arranged at the focus of the X-ray free electron laser; the sample target (4) comprises a plurality of target areas (41), a sample (42) is arranged in each of the target areas (41), and the X-ray free electron laser generates a diffraction light path after forming a light spot on the sample (42); A single photon response detection mechanism (5) is arranged in the diffraction light path generated after the X-ray free electron laser bombards the sample (42) and is used to collect diffraction patterns; The phase workstation (6) is electrically connected to the single photon response detection mechanism (5) and is used to collect diffraction pattern data and perform phase recovery.

2. The femtosecond ultrafast diffraction imaging system according to claim 1, characterized in that: The optical path focusing mechanism (2) comprises a first focusing reflector (21) and a second focusing reflector (22) arranged in the optical path of the X-ray free electron laser; the first focusing reflector (21) and the second focusing reflector (22) are arranged relative to the light beam of the X-ray free electron laser and focus the X-ray free electron laser on a sample (42).

3. The femtosecond ultrafast diffraction imaging system according to claim 1 or 2, characterized in that: The light control mechanism (3) comprises a first baffle (31) and a second baffle (32) arranged in the X-ray free electron laser light path, and the light control slit (33) is formed between the first baffle (31) and the second baffle (32).

4. The femtosecond ultrafast diffraction imaging system according to claim 1, characterized in that: A fine adjustment mechanism (7), a coarse adjustment mechanism (8) and an angle adjustment mechanism (9) are sequentially arranged below the sample target (4); the resolution of the fine adjustment mechanism (7) is ≤10 nm, the resolution of the coarse adjustment mechanism (8) is ≤1 μm, and the resolution of the angle adjustment mechanism (9) is ≤0.1°.

5. The femtosecond ultrafast diffraction imaging system according to claim 1, characterized in that: The single-photon response detector comprises a supporting platform (51) and a single-photon response detector (52) arranged on the displacement platform; The single-photon response detector (52) comprises a first diffraction light plate (52.1), a zero-order diffraction light plate (52.2) and a second diffraction light plate (52.3) arranged in a diffraction light path; the first diffraction light plate (52.1) and the second diffraction light plate (52.3) are arranged relative to the light beam of the X-ray free electron laser and are located in the diffraction light area of ​​the diffraction light path, the zero-order diffraction light plate (52.2) is arranged in the straight-through area of ​​the diffraction light path, and a light blocking plate (53) is also arranged in front of the zero-order diffraction light plate (52.2).

6. The femtosecond ultrafast diffraction imaging system according to claim 2, characterized in that: The materials of the first focusing reflector (21) and the second focusing reflector (22) are independently selected from KB mirrors, Fresnel zone plates or X-ray combined refractive lenses.

7. The femtosecond ultrafast diffraction imaging system according to claim 3, characterized in that: The materials of the first baffle (31) and the second baffle (32) are independently selected from single crystal silicon, boron carbide or tungsten carbide; and / or the width of the light-controlling slit (33) is greater than 50 μm, the movement accuracy of the first baffle (31) and the second baffle (32) is less than 1 μm, and the movement resolution of the first baffle (31) and the second baffle (32) is less than 0.2 μm.

8. The femtosecond ultrafast diffraction imaging system according to claim 1, characterized in that: The operating frequency of the single-photon response detector (52) is >2 Hz, and the resolution of the single-photon response detector (52) is >2k.

9. The femtosecond ultrafast diffraction imaging system according to claim 1, characterized in that: The diameter of the X-ray free electron laser spot on the sample target (4) is 2 to 20 μm; and / or the number of the target areas (41) is 10 to 30; and / or the distance between the light control mechanism (3) and the sample target (4) is 100 to 1000 mm.

10. A method for using the femtosecond ultrafast diffraction imaging system according to any one of claims 1 to 9, comprising at least the following steps: 1) Preparation and calibration of the optical path, adjusting the position of the sample target (4) to align the center of the light spot with the sample (42); 2) collecting diffraction spots, bombarding the sample (42) with X-ray free electrons, and collecting the Bragg diffraction pattern and the zero-order diffraction pattern through a single photon response detector (52); 3) Phase recovery: Phase recovery is performed on the Bragg diffraction pattern and the zero-order diffraction pattern to obtain high-resolution topographic imaging and internal strain imaging, respectively.

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