A partially coherent hard x-ray laminar diffraction imaging system

Abstract

The application belongs to the field of optical equipment, and specifically discloses a partially coherent hard X-ray laminar diffraction imaging system, which comprises a ray generating light source for emitting high-brightness hard X-rays, and a slit limiting unit, a light beam focusing unit, a coherence degree control unit, an experimental chamber and an image acquisition unit arranged in sequence along the optical axis direction of the high-brightness hard X-rays; the slit limiting unit is used for limiting the light beam divergence of the high-brightness hard X-rays, the light beam focusing unit is used for focusing the high-brightness hard X-ray light beam passing through the slit limiting unit to the light path entrance of the coherence degree control unit, and the coherence degree control unit is used for adjusting the spatial coherence of the high-brightness hard X-rays to form partially coherent hard X-rays and emit the partially coherent hard X-rays to the experimental chamber. Through the structural design of the application, the diffraction image blurring effect caused by the poor coherence of the hard X-rays is effectively inhibited, and the reconstructed image resolution and imaging quality are improved.

Description

Technical Field

[0001] This application belongs to the field of optical equipment, and more specifically, relates to a partially coherent hard X-ray stacked diffraction imaging system. Background Technology

[0002] The development of high-brightness X-ray sources has made non-destructive, high-resolution imaging of microstructures possible. Coherent diffraction imaging technology, based on beam coherence, has overcome the limitations of traditional X-ray optical elements in terms of processing precision and plays a key role in the study of nanoscale materials.

[0003] X-ray ptychography is a typical coherent diffraction imaging technique. It utilizes fully or partially coherent X-ray beams to irradiate a sample in an overlapping scanning manner, acquiring a series of diffraction patterns in the near or far field. Subsequently, a phase retrieval algorithm is used to reconstruct the complex transmission function of the sample and the incident probe information from the diffraction data, which includes redundant information. This technique boasts advantages such as strong robustness, non-destructive testing, and the ability to operate without isolated samples. Its theoretical spatial resolution is primarily limited by the maximum effective diffraction angle received by the detector and the signal-to-noise ratio of the diffraction images.

[0004] Classical X-ray stacked diffraction imaging models typically assume that the incident beam is perfectly coherent in both time and space. However, when hard X-rays are used as the incident beam, due to their extremely short wavelength, the incident beam often exhibits partial coherence and poor stability, resulting in a blurring effect in the diffraction image and thus affecting the final image quality. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this application provides a partially coherent hard X-ray stacked diffraction imaging system, which aims to solve the problem of blurred diffraction images caused by the partial coherence and poor stability of hard X-ray incident beams, resulting in decreased resolution and impaired imaging quality of reconstructed images.

[0006] This application provides a partially coherent hard X-ray stacked diffraction imaging system, which specifically includes a radiation source for emitting high-brightness hard X-rays, and a slit confinement unit, a beam focusing unit, a coherence control unit, an experimental chamber, and an image acquisition unit arranged sequentially along the optical axis of the high-brightness hard X-rays. The slit confinement unit is used to limit the beam divergence of the high-brightness hard X-rays, the beam focusing unit is used to focus the high-brightness hard X-ray beam passing through the slit confinement unit to the optical path entrance of the coherence control unit, and the coherence control unit is used to adjust the spatial coherence of the high-brightness hard X-rays to form partially coherent hard X-rays and project them into the experimental chamber. The experimental chamber includes a shell and an imaging platform. The shell has an internal cavity, and optical path windows on both sides for the partial coherent hard X-rays to pass through. The imaging platform is located inside the cavity. Optical components and sample components are sequentially arranged on the imaging platform along the optical axis of the partial coherent hard X-rays. The sample components are used to mount the imaging sample. The optical components are used to focus the partial coherent hard X-rays into a focused spot and irradiate the imaging sample to generate a diffraction signal. The image acquisition unit is used to receive the diffraction signal and perform stacked diffraction imaging.

[0007] Compared with the prior art, the technical solution conceived in this application, by setting a coherence control unit between the beam focusing unit and the experimental chamber, can actively regulate the spatial coherence of hard X-rays before they are incident on the imaging sample, forming partially coherent hard X-rays with controllable spatial coherence and good stability. This effectively suppresses the blurring effect of diffraction images caused by the poor coherence and unstable fluctuations of hard X-rays themselves. At the same time, through the coordinated cooperation of the slit confinement unit, beam focusing unit, coherence control unit, optical components and sample components arranged sequentially along the optical axis, precise shaping and stable focusing of the partially coherent beam are achieved. This enables the acquired diffraction signal to meet the reconstruction requirements of stacked diffraction imaging, and high-resolution, high-fidelity reconstructed images can be obtained under the condition that the incident beam is partially coherent. This effectively solves the problem of image quality degradation caused by insufficient partial coherence and beam stability.

[0008] As a further preferred embodiment, the coherence control unit includes a first aperture and a first two-dimensional displacement stage. The first aperture is perpendicular to the optical axis of the high-brightness hard X-ray and has a first perforation. The high-brightness hard X-ray beam passes through the first perforation to adjust the spatial coherence. The first aperture is fixedly mounted on the moving platform of the first two-dimensional displacement stage, and the first two-dimensional displacement stage drives the first aperture to move the first perforation in a plane perpendicular to the optical axis.

[0009] As a further preferred embodiment, the thickness of the first aperture is greater than 300 μm, and the diameter of the first perforation is 30 μm-50 μm.

[0010] As a further preferred embodiment, the first aperture is made of any one of tungsten, gold, or germanium.

[0011] As a further preferred embodiment, the optical component includes a zone plate, a second aperture, and a first three-dimensional displacement stage. The zone plate and the second aperture are both perpendicular to the optical axis of the partially coherent hard X-rays and are sequentially arranged on two different moving platforms of the first three-dimensional displacement stage along the optical axis. The zone plate is used to diffract the partially coherent hard X-rays, and the second aperture has a second perforation.

[0012] As a further preferred embodiment, the optical component further includes a first high-precision three-dimensional displacement stage, which is connected to the moving platform of the first high-precision three-dimensional displacement stage, and the zone plate is fixedly mounted on the moving platform of the first high-precision three-dimensional displacement stage.

[0013] As a further preferred embodiment, the sample assembly includes a second three-dimensional displacement stage, a second high-precision three-dimensional displacement stage, a rotary stage, a high-precision two-dimensional displacement stage, and a sample holder. The second three-dimensional displacement stage is fixedly mounted on the imaging platform. The second high-precision three-dimensional displacement stage is fixedly connected to the moving platform of the second three-dimensional displacement stage. The rotary stage is fixedly connected to the moving platform of the second high-precision three-dimensional displacement stage. The high-precision two-dimensional displacement stage is fixedly connected to the rotating platform of the rotary stage. The sample holder is connected to the moving platform of the high-precision two-dimensional displacement stage. The high-precision two-dimensional displacement stage drives the sample holder to move in a plane perpendicular to the optical axis of the partially coherent hard X-rays to achieve axis alignment of the imaging sample.

[0014] As a further preferred embodiment, the sample holder and the high-precision two-dimensional displacement stage are detachably connected.

[0015] As a further preferred embodiment, the sample holder is a two-dimensional sample holder or a three-dimensional sample holder.

[0016] As a further preferred embodiment, the imaging platform is also equipped with an observation component for monitoring the alignment process of the imaging sample.

[0017] As a further preferred embodiment, the observation assembly includes a microscope camera and a third three-dimensional displacement stage. The third three-dimensional displacement stage is fixedly mounted on the imaging platform, and the microscope camera is fixedly mounted on the moving platform of the third three-dimensional displacement stage. The third three-dimensional displacement stage drives the microscope camera to move so that the imaging sample is located at the center of the microscope camera's field of view and aligned with the microscope camera's focal point.

[0018] As a further preferred embodiment, the imaging platform is also provided with a position measurement unit for measuring the positions of the zone plate and the sample holder.

[0019] As a further preferred embodiment, the position measurement unit includes a laser transceiver and a reflector. The laser transceiver is disposed inside the cavity, and multiple reflectors are disposed on the zone plate and the high-precision two-dimensional displacement stage, respectively. The laser transceiver is used to emit laser light to the reflector and measure the position of the zone plate and the sample holder based on the interference fringes of the emitted and reflected laser light.

[0020] As a further preferred embodiment, the image acquisition unit includes a photon counting detector and a second two-dimensional displacement stage. The photon counting detector is located at the end of the optical axis and is perpendicular to the optical axis. The photon counting detector is fixedly connected to the moving platform of the second two-dimensional displacement stage.

[0021] In summary, compared with the prior art, the technical solutions conceived in this application have the following main technical advantages: 1. This application sets up a coherence control unit between the beam focusing unit and the experimental chamber. This unit can actively control the spatial coherence of high-brightness hard X-rays to form partially coherent hard X-rays that meet the requirements of stacked diffraction imaging. This effectively suppresses the blurring effect of diffraction images caused by the poor coherence of hard X-rays themselves, and improves the resolution and imaging quality of the reconstructed image.

[0022] 2. In this application, high-precision focusing of partially coherent hard X-rays is achieved through the cooperation of a zone plate and a second aperture. The sample assembly achieves precise alignment of the imaging sample in multiple degrees of freedom through multi-stage linkage of a second three-dimensional displacement stage, a second high-precision three-dimensional displacement stage, a rotary stage, and a high-precision two-dimensional displacement stage. Simultaneously, the alignment process is monitored in real time by an observation component, and the positions of the zone plate and sample holder are measured with high precision using a position measurement unit, ensuring that the focused spot accurately illuminates the target area of ​​the imaging sample, significantly improving the acquisition quality of the diffraction signal.

[0023] 3. Through the sequential coordination of the slit confinement unit, beam focusing unit, coherence control unit, optical components, sample components and image acquisition unit, this application forms a complete system from beam shaping, coherence control, high-precision focusing, precise sample positioning to diffraction signal acquisition, to obtain high-resolution reconstructed images, and solves the problem of image quality degradation caused by poor spatial coherence of hard X-rays in the prior art. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the overall structure of a partially coherent hard X-ray stacked diffraction imaging system provided in the embodiments of this application; Figure 2 This is a schematic diagram of the internal structure of the experimental chamber provided in the embodiments of this application; Figure 3This is a schematic diagram of the overall internal structure of the experimental chamber provided in the embodiments of this application; Figure 4 This is a system operation flowchart provided in the embodiments of this application; Figure 5 It is the image of the diffraction pattern obtained by the experiment in the embodiment of this application after taking the natural logarithm; Figure 6 This is a comparison diagram of the reconstruction results of experimental data from the embodiments of this application and the corresponding electron microscope images.

[0025] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1. X-ray source; 2. Slit confinement unit; 3. Beam focusing unit; 4. Coherence control unit; 41. First aperture; 42. First two-dimensional displacement stage; 5. Experimental chamber; 51. Shell; 511. Cavity; 512. Optical path window; 52. Imaging platform; 53. Optical components; 531. Zone plate; 532. Second aperture; 533. First three-dimensional displacement stage; 534. First high-precision three-dimensional displacement stage; 54. Sample assembly; 541. Second three-dimensional displacement stage; 542. Second high-precision three-dimensional displacement stage; 543. High-precision three-dimensional displacement stage; 544. Rotary stage; 545. High-precision two-dimensional displacement stage; 546. Sample holder; 55. Observation assembly; 557. Microscope camera; 558. Third three-dimensional displacement stage; 59. Position measurement unit; 50. Support frame; 51. Granite base; 52. Positioning base plate; 53. Positioning block; 64. Image acquisition unit; 65. Photon counting detector; 66. Second two-dimensional displacement stage; 7. Displacement stage controller; 8. Data acquisition and processing computer; 9. Position data acquisition module. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0027] Reference Figures 1-3 The partially coherent hard X-ray stacked diffraction imaging system disclosed in this application includes a X-ray generating source 1, and a slit confinement unit 2, a beam focusing unit 3, a coherence control unit 4, an experimental chamber 5, and an image acquisition unit 6 arranged sequentially along the optical axis of the high-brightness hard X-rays emitted by the X-ray generating source 1.

[0028] Reference Figure 1The X-ray source 1 is used to emit a high-brightness hard X-ray beam. This high-brightness hard X-ray beam has a high photon flux, which can provide a sufficient signal-to-noise ratio for diffraction images in a short time. Specifically, it can be a laboratory-grade liquid metal jet X-ray source or a synchrotron radiation source. The laboratory-grade liquid metal jet X-ray source generates X-rays by accelerating electrons in an ultra-high vacuum environment under a high-voltage electric field and then impacting them with a molten liquid metal anode. Since this method does not require consideration of anode heat dissipation, it can achieve a photon flux tens to hundreds of times higher than that of traditional solid anode X-ray sources. The synchrotron radiation source directly converts part of the kinetic energy of high-energy electrons into photons by bending magnets or vacuum undulators. In terms of energy conversion efficiency and photon flux, the synchrotron radiation source is significantly superior to the laboratory-grade liquid metal jet X-ray source. Since both of the above-mentioned X-ray source 1 are common sources in this field, they can be selected according to actual needs, and therefore will not be described in detail in this application.

[0029] The slit confinement unit 2 employs a four-blade structure to limit the beam divergence of high-brightness hard X-rays, thereby limiting the receiving angle of subsequent optical elements. It allows only the central cone of the upstream high-brightness hard X-ray to pass through and absorbs excess heat load, meeting the requirements of the downstream optical path. It is also a common slit structure and can be selected according to actual needs. Since it is not an inventive point of this application, it will not be specifically described here.

[0030] The beam focusing unit 3 can select the energy of the high-brightness hard X-ray beam passing through the slit confinement unit 2 and focus the beam to the optical path entrance of the coherence control unit 4, that is, to the first aperture on the first aperture 41 in the coherence control unit 4. Specifically, when the X-ray source 1 is a laboratory-grade liquid metal jet X-ray source, the beam focusing unit 3 uses a Montel mirror, which collimates or focuses only narrowband X-rays near the design energy through grazing incidence total internal reflection, while filtering out X-rays outside the design energy, thus achieving energy selection and focusing. When the X-ray source 1 is a synchrotron radiation source, the beam focusing unit 3 uses a double multilayer monochromator and a set of horizontal and vertical reflecting focusing mirrors. The double multilayer monochromator can obtain higher photon flux by sacrificing some temporal coherence, and the reflecting focusing mirrors are used to focus the high-brightness hard X-rays to the position of the coherence control unit 4.

[0031] The coherence control unit 4 is used to adjust the spatial coherence of the high-brightness hard X-rays after energy selection and focusing by the beam focusing unit 3, so as to form partially coherent hard X-rays and inject them into the cavity 511 of the experimental chamber 5. The coherence control unit 4 serves as a secondary light source. The coherence control unit 4 includes a first aperture 41 and a first two-dimensional displacement stage 42. The first aperture 41 is perpendicular to the optical axis of the high-brightness hard X-rays and has a first perforation. The high-brightness hard X-ray beam passes through the first perforation to adjust the spatial coherence. While stabilizing its spatial coherence, the level of coherence can be controlled according to actual needs. The first aperture 41 is fixedly installed on the moving platform of the first two-dimensional displacement stage 42. The first two-dimensional displacement stage 42 drives the first aperture 41 to move the first perforation in a plane perpendicular to the optical axis, that is, in a plane along the X and Y directions, so that the first perforation and the focal point of the partially coherent hard X-ray beam are coaxially aligned along the Z-axis. The first aperture 41 controls the spatial coherence of hard X-rays by adjusting the size of the light source point, thereby forming partially coherent light in space. In this embodiment, the thickness of the first aperture 41 is greater than 300 μm, the diameter of the first perforation is 30 μm-50 μm, and the first aperture 41 is made of any one of tungsten, gold, or germanium. When the diameter of the first perforation is 50 μm, the first aperture 41 is made of tungsten; when the diameter of the first perforation is 30 μm, the first aperture 41 is made of gold. The first perforation is required to allow only the light from the focal point of the beam focused by the beam focusing unit 3 to pass through.

[0032] Reference Figures 2-3 The experimental chamber 5 includes a shell 51 and an imaging platform 52. The shell 51 has an internal cavity 511, and both sides of the shell 51 have optical path windows 512 for some coherent hard X-rays to pass through. Both optical path windows 512 are coaxially aligned with the optical axis of the partially coherent hard X-rays. The interior of the cavity 511 is set to a vacuum or helium atmosphere to prevent air from causing attenuation and scattering of the partially coherent hard X-rays. Multiple vacuum flanges are provided at the front and rear ends of the cavity 511 to provide a vacuum or helium atmosphere for imaging. Removable sealing covers are provided on both sides and the top of the cavity 511 for easy adjustment of the imaging platform 52 inside. Specifically, one of the removable sealing covers can be switched to vacuum feedthrough mode to enable circuit connection in vacuum operating mode. The imaging platform 52 is located inside the cavity 511 and is made of Invar steel. Optical components 53 and sample components 54 are arranged sequentially on the imaging platform 52 along the optical axis of the partially coherent hard X-rays. The sample components 54 are used to carry and transport the sample and perform sample scanning motion. The optical components 53 are used to diffract the partially coherent hard X-rays, focus the partially coherent hard X-rays into a focused spot, and make the focused spot irradiate the imaging sample to generate a diffraction signal.

[0033] In this embodiment, the cavity 511 and the imaging platform 52 are separate structures. A support frame 57 is connected to the bottom of the housing 51. The bottom of the imaging platform 52 is connected to a granite base 58 outside the housing 51 via steel support columns. A vacuum bellows is fitted around the steel support columns to ensure the airtightness of the cavity. The granite base 58 enhances the stability of the imaging platform 52. A positioning base plate 59 is connected to the bottom of the frame via steel columns. When the frame is in place, the positioning base plate 59 is flush with the ground. In experimental conditions, the granite base 58 rests on the positioning base plate 59. In non-experimental conditions, the granite base is supported on the frame by support beams. The granite base and the imaging platform 52 can be moved as a whole by lifting the frame. A positioning block 591 is installed on the positioning base plate 59 to position the granite base 58 and reduce positioning errors.

[0034] Specifically, the optical component 53 includes a zone plate 531, a second aperture 532, a first three-dimensional displacement stage 533, and a first high-precision three-dimensional displacement stage 534. The first three-dimensional displacement stage 533 is a dual-platform three-dimensional displacement stage. The zone plate 531 and the second aperture 532 are both perpendicular to the optical axis of some coherent hard X-rays and are sequentially arranged on two different moving platforms of the first three-dimensional displacement stage 533 along the optical axis. Specifically, the first high-precision three-dimensional displacement stage 534 is fixedly installed on the moving platform of the first three-dimensional displacement stage 533 near the coherence control unit 4, and the zone plate 531 is fixedly installed on the moving platform of the first high-precision three-dimensional displacement stage 534 to achieve precise movement of the zone plate 531. The zone plate 531 is used to diffract some coherent hard X-rays. The zone plate 531 is made of gold deposited on Si3N4, with a zone thickness of about 1250nm, an outermost ring width of 50nm, corresponding to a diffraction-limited focal diameter of 50nm, and a theoretical focal length of 72.56mm at an X-ray energy of 10keV. The second aperture 532 is mounted on another moving platform of the first three-dimensional displacement stage 533 and has a second perforation. The second aperture 532 has a thickness of more than 300 μm and is made of gold material. The diameter of the second perforation is 30 μm. The second perforation and the zone plate 531 are coaxially arranged on the Z-axis. The second aperture 532 is used to select the partially coherent hard X-rays after diffraction. Specifically, it is used to block diffraction light of other orders except ±1st order diffraction light in order to obtain focused X-rays.

[0035] The sample assembly 54 includes a second three-dimensional displacement stage 541, a second high-precision three-dimensional displacement stage 542, a rotary stage 543, a high-precision two-dimensional displacement stage 544, and a sample holder 545. The second three-dimensional displacement stage 541 is fixedly mounted on the imaging platform 52 and is used to initially align the imaging sample and the optical assembly 53 coaxially on the Z-axis in two-dimensional imaging; in three-dimensional imaging, it is used to align the rotation axis of the rotary stage 543 with the center of the optical path. The second high-precision three-dimensional displacement stage 542 is fixedly connected to the moving platform of the second three-dimensional displacement stage 541, and the rotary stage 543 is fixedly connected to the moving platform of the second high-precision three-dimensional displacement stage 542, with the rotation axis located on the Y-axis, and is used to rotate the imaging sample to obtain experimental results from different angles in the three-dimensional experimental mode. The high-precision two-dimensional displacement stage 544 is fixedly connected to the rotating platform of the rotary stage 543, and the sample holder 545 is connected to the moving platform of the high-precision two-dimensional displacement stage 544. The high-precision two-dimensional displacement stage 544 drives the sample holder 545 to move in a plane perpendicular to the optical axis of the partially coherent hard X-rays to achieve the alignment of the imaging sample. The sample holder 545 is used to carry and transport samples. It is detachably connected to the high-precision two-dimensional displacement stage 544. The sample holder 545 can be a two-dimensional sample holder 545 or a three-dimensional sample holder 545. The two-dimensional sample holder 545 is used to support two-dimensional samples, and the three-dimensional sample holder 545 is used to support three-dimensional samples. It can be selected according to actual needs. The two-dimensional sample holder 545 can fix the imaging sample in a plane perpendicular to the optical axis. The three-dimensional sample needs to be transferred to the three-dimensional sample holder 545 for fixation after micro-nano processes (such as focused ion beam cutting).

[0036] Furthermore, the imaging platform 52 is also equipped with an observation component 55 for monitoring the alignment process of the imaging sample and a position measurement unit 56 for measuring the positions of the zone plate 531 and the sample holder 545. The optical component 53, sample component 54, observation component 55, and position measurement unit 56 work together to obtain a partially coherent X-ray nanofocused spot, align and scan the sample, and acquire high-precision position information at high speed. The observation component 55 includes a microscope camera 551 and a third three-dimensional displacement stage 552. The third three-dimensional displacement stage 552 is fixedly mounted on the imaging platform 52, and the microscope camera 551 is fixedly mounted on the moving platform of the third three-dimensional displacement stage 552. The third three-dimensional displacement stage 552 drives the microscope camera 551 to move so that the imaging sample is located at the center of the field of view of the microscope camera 551 and aligned with the focal point of the microscope camera 551. The position measurement unit 56 includes a laser transceiver, a reflector, a probe holder, and a laser collimating probe. The probe holder supports the laser collimating probe, which is used to collimate and emit laser light. The laser transceiver is located inside the cavity 511 to emit and receive reflected laser light. Multiple reflectors are provided, respectively mounted on the zone plate 531 and the high-precision two-dimensional displacement stage 544, for reflecting and emitting laser light. Three probe holders are provided, two of which are connected to the imaging platform 52 to support the laser collimating probe for measuring the positional offset between the zone plate 531 and the sample holder 545 in the X and Y axes. The third probe holder is connected to the second high-precision three-dimensional displacement stage 542 to support the laser collimating probe for measuring the relative positional offset between the sample holder 545 and the zone plate 531 in the Z axis. The laser transceiver is used to emit laser light towards the reflector and measure the positions of the zone plate 531 and sample holder 545 based on the interference fringes of the emitted and reflected laser light. It calculates the absolute distances between the sample holder 545 and the zone plate 531 and the laser collimating probes in the X and Y axes, as well as the relative distance between the sample holder 545 and the zone plate 531. Five laser collimating probes are provided, each mounted on a probe holder and connected to the laser transceiver via optical fibers. The reflector reflects the emitted laser light, and the emitted and reflected laser light creates a Fabry-Perot cavity at the junction of the probe and the optical fiber. This cavity is transmitted through the optical fiber to the laser transceiver, where the precise distance is obtained by calculating the interference fringes.

[0037] Image acquisition unit 6 is used to receive coherent diffraction signals and perform stacked diffraction imaging, collecting the diffraction field spectrum formed by the far-field propagation of partially coherent X-rays after their interaction with the imaging sample, thus realizing a stacked scanning experiment on the sample. Specifically, it includes a photon counting detector 61 and a second two-dimensional displacement stage 62. The photon counting detector 61 is located at the end of the optical path and perpendicular to the optical axis, and is fixedly connected to the moving platform of the second two-dimensional displacement stage 62. In this embodiment, the photon counting detector 61 has four 256×256 pixel detector modules, with a single pixel size of 55μm. In two-dimensional scanning mode, it is used to acquire and record the coherent diffraction signals generated by the interaction of partially coherent hard X-rays with the imaging sample; in three-dimensional scanning mode, it is used to acquire and record the two-dimensional coherent diffraction signals corresponding to different angles during a 180° rotation of partially coherent hard X-rays with the imaging sample.

[0038] In this embodiment, the first three-dimensional displacement stage 533, the second three-dimensional displacement stage 541, and the third three-dimensional displacement stage 552 are all mechanical displacement stages. The first three-dimensional displacement stage 533 is used to align the zone plate 531 and the second aperture 532 coaxially with the X-ray in the Z-axis direction, which can compensate for positioning errors; in particular, it controls the independent movement of the second aperture 532 in the Z-axis direction to adjust the distance between the second aperture 532 and the zone plate 531. The second three-dimensional displacement stage 541 is used to align the imaging sample to the optical path in two-dimensional imaging; in three-dimensional imaging, it is used to align the rotation center of the first high-precision one-dimensional rotation axis to the optical path. The third three-dimensional displacement stage 552 is used to adjust the distance from the microscope camera 551 to the sample and the position of the sample in the field of view of the microscope camera 551 for precise observation. The first high-precision three-dimensional displacement stage 534, the second high-precision three-dimensional displacement stage 542, the rotary stage 543, and the high-precision two-dimensional displacement stage 544 are all piezoelectric ceramic displacement stages. A first high-precision three-dimensional displacement stage 534 is mounted on a first three-dimensional displacement stage 533, and a zone plate 531 is mounted on the first high-precision three-dimensional displacement stage 534 to precisely align the zone plate 531 with the optical path in the Z-axis direction. A second high-precision three-dimensional displacement stage 542 is mounted on the second three-dimensional displacement stage 541, and can perform object scanning motion and send data acquisition trigger signals. In two-dimensional imaging, it is used to precisely align the sample with the optical path in the Z-axis direction, and in three-dimensional imaging, it is used to precisely align the rotation center of the rotary stage 543 with the optical path. The rotary stage 543 is mounted on the second high-precision three-dimensional displacement stage 542 to rotate the three-dimensional sample. A high-precision two-dimensional displacement stage 544 is mounted on the rotary stage 543 for precise axis alignment of the three-dimensional sample, aligning the sample with the rotation center of the rotary stage 543.

[0039] This embodiment also includes a displacement stage controller 7 and a data acquisition and processing computer 8. The displacement stage controller 7 is connected to the second high-precision three-dimensional displacement stage 542 and is used to control the second high-precision three-dimensional displacement stage 542 to perform scanning motion of the imaging sample and to issue trigger signals. In addition, the displacement stage controller 7 is also connected to the photon counting detector 61 and the position data acquisition module 9 through a trigger line, and is used to simultaneously trigger the acquisition of diffraction signals and high-precision position data. The position data acquisition module 9 includes a data acquisition unit connected to the laser transceiver. The position data acquisition unit receives the trigger signal from the displacement stage controller 7, reads the internal signals of the laser transceiver through the data transmission line connected to the laser transceiver, calculates the precise position data, and records and saves it. The data acquisition and processing computer 8 includes multiple modules, which are used to control the movement of each displacement stage and the rotary stage 543, control the opening and closing of the laser transceiver, preset the equipment parameters, and acquire and store test data. It processes the diffraction signals and high-precision position information obtained in the experiment through a reconstruction algorithm to obtain the complex transmission function of the object and the complex amplitude of the probe.

[0040] In optics, fully coherent light can be represented by a single complex amplitude function. However, due to the finite geometry and energy dissipation characteristics of the light source, incident hard X-rays are usually not ideally fully coherent waves. Their light field exhibits statistical phase fluctuations in both spatial and temporal dimensions, resulting in only partial correlation between light field points at different spatial locations or times. Therefore, a single complex amplitude function cannot fully describe the physical properties of the beam. It must be considered as a weighted sum of multiple coherent modes that are independent in both time and space to more accurately represent the physical properties of the beam. Thus, mode decomposition can be used to solve for the complex transmission function of an object.

[0041] The multimodal algorithm performs a computational deconvolution process. It treats the blurred diffraction pattern received by the photon counting detector 61 as the result of intensity superposition at the detector end after multiple quasi-monochromatic, fully coherent mode beams independently pass through the imaging sample. By independently updating the phase and correcting the energy distribution of each modal component in each iteration, the algorithm extracts and precisely strips away the higher-order incoherent background hidden behind the main mode, thereby reconstructing a near-fully coherent image. In this embodiment, the multimodal algorithm is used to reconstruct the acquired diffraction data, resulting in the image shown below. Figure 6 The reconstruction results shown in the figure indicate that the region of interest in the sample contains line pairs with a half-period of 30 nm.

[0042] The following is an explanation through specific embodiments: The experimental scenario in this embodiment is as follows: the X-ray source 1 is a synchrotron radiation source, a vacuum undulator is used as the photon source, and the beam focusing unit 3 is a double multilayer monochromator and horizontal and vertical reflecting focusing mirrors.

[0043] The first step is to position and install the experimental chamber 5. Using a crane, the frame and the granite base 58 supporting it are installed together with the imaging platform 52 on the optical path. The frame and the granite base 58 are then separated, and the positioning block 591 is used to reduce the error of the optical component 53 and the sample component 54 relative to the optical path during the positioning and installation process.

[0044] The second step is beam focusing and coherent light acquisition. The horizontal and vertical reflecting focusing mirrors are adjusted to focus the X-rays onto the first aperture 41 to increase the coherent flux; the first two-dimensional displacement stage 42 is controlled to align the center of the first aperture 41 with the center of the focused beam. Calculations and measurements show that when using a 50μm pinhole as the secondary light source, spatially coherent light is obtained, with a coherent flux reaching 1.5 × 10⁹ photons per second.

[0045] The third step involves aligning the optical component 53 with the sample component 54. The second two-dimensional displacement stage 62 is controlled to align the photon counting detector 61 with the beam, and attenuation components such as aluminum foil are added. The photon counting detector 61 is used to calibrate the position of the strongest beam. The second aperture 532 is installed, and the first three-dimensional displacement stage 533 is controlled to align the second aperture 532 with the calibrated position. The zone plate 531 is installed, and the first high-precision three-dimensional displacement stage 534 is controlled to precisely align the zone plate 531 with the X-ray beam, the second aperture 532, and the photon counting detector 61 in a third-direction Z-axis coaxial configuration. The sample is installed, and the second three-dimensional displacement stage 541 is controlled to precisely align the sample with the X-ray beam, the zone plate 531, the second aperture 532, and the photon counting detector 61 in a third-direction Z-axis coaxial configuration. In two-dimensional imaging mode, the second three-dimensional displacement stage 541 is controlled to find the region of interest in the sample; in three-dimensional imaging mode, the third three-dimensional displacement stage 552 is controlled to move the microscope camera 551 so that the sample is located at the camera focus and the center of the camera field of view, the rotary stage 543 is controlled to rotate 360°, and the displacement stage 23 is controlled to repeatedly translate until the sample no longer shifts during the rotation.

[0046] The fourth step is to configure the high-precision position measurement system. Adjust the laser collimating probe to align the emitted laser with the reflector, configure the sampling parameters, connect the second high-precision three-dimensional displacement stage 542, the photon counting detector 61, and the position data acquisition module 9, and use the displacement stage controller 7 as the trigger source to perform position data sampling tests.

[0047] Step 5: Diffraction image and position data acquisition. Select the region of interest for the sample, execute the scanning program, and control the second high-precision three-dimensional displacement stage 542 to emit an electrical signal when it reaches the predetermined position. The photon counting detector 61 receives the electrical signal and begins data acquisition.

[0048] Step 6: Rotate the sample to acquire diffraction images at different angles. This step is only used in 3D imaging. The rotating stage 543 is controlled to rotate around the rotation center, and the photon counting detector 61 collects the coherent diffraction signals of the sample at different angles, such as... Figure 5 As shown.

[0049] Step 7: Data Processing and Image Reconstruction. The experimental data processing module extracts the positional data corresponding to each diffraction pattern, imports it into the algorithm to obtain the sample's complex transmission function and probe complex amplitude. For three-dimensional data, the algorithm recovers the distribution of the sample's complex transmission function under each projection, performs pixel-level precise alignment of the object's complex transmission function under each projection, and uses a computed tomography (CT) reconstruction algorithm to recover the sample's three-dimensional structure, such as... Figure 6 As shown.

[0050] It should be understood that expressions such as "comprising" and "may include" as used in this application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In this application, terms such as "comprising" and / or "having" may be interpreted as indicating a specific characteristic, number, operation, constituent element, component, or combination thereof, but should not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0051] It should be understood that the terms “center,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “inner,” “outer,” “clockwise,” “counterclockwise,” “axial,” “radial,” and “circumferential” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0052] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0053] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0054] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A partially coherent hard X-ray stacked diffraction imaging system, characterized in that, It includes a radiation source (1) for emitting high-brightness hard X-rays, and a slit confinement unit (2), a beam focusing unit (3), a coherence control unit (4), an experimental chamber (5), and an image acquisition unit (6) arranged sequentially along the optical axis of the high-brightness hard X-rays. The slit confinement unit (2) is used to limit the beam divergence of the high-brightness hard X-rays. The beam focusing unit (3) is used to focus the high-brightness hard X-ray beam passing through the slit confinement unit (2) to the optical path entrance of the coherence control unit (4). The coherence control unit (4) is used to adjust the spatial coherence of the high-brightness hard X-rays to form partially coherent hard X-rays and project them into the experimental chamber (5). The experimental chamber (5) includes a shell (51) and an imaging platform (52). The shell (51) has a cavity (511) inside, and optical path windows (512) for the partial coherent hard X-rays to pass through are provided on both sides of the shell (51). The imaging platform (52) is located inside the cavity (511). Optical components (53) and sample components (54) are arranged sequentially on the imaging platform (52) along the optical axis of the partial coherent hard X-rays. The sample components (54) are used to mount the imaging sample. The optical components (53) are used to focus the partial coherent hard X-rays into a focused spot and make the focused spot irradiate the imaging sample to generate a diffraction signal. The image acquisition unit (6) is used to receive the diffraction signal and perform stacked diffraction imaging.

2. The partially coherent hard X-ray stacked diffraction imaging system as described in claim 1, characterized in that, The coherence control unit (4) includes a first aperture (41) and a first two-dimensional displacement stage (42). The first aperture (41) is perpendicular to the optical axis of the high-brightness hard X-ray and has a first perforation. The high-brightness hard X-ray beam passes through the first perforation to adjust the spatial coherence. The first aperture (41) is fixedly installed on the moving platform of the first two-dimensional displacement stage (42). The first two-dimensional displacement stage (42) drives the first aperture (41) to move the first perforation in a plane perpendicular to the optical axis.

3. The partially coherent hard X-ray stacked diffraction imaging system as described in claim 2, characterized in that, The thickness of the first aperture (41) is greater than 300 μm, and the diameter of the first perforation is 30 μm-50 μm; and / or, the first aperture (41) is made of any one of tungsten, gold or germanium.

4. The partially coherent hard X-ray stacked diffraction imaging system as described in claim 1, characterized in that, The optical component (53) includes a zone plate (531), a second aperture (532), and a first three-dimensional displacement stage (533). The zone plate (531) and the second aperture (532) are both perpendicular to the optical axis of the partially coherent hard X-rays and are sequentially arranged on two different moving platforms of the first three-dimensional displacement stage (533) along the optical axis. The zone plate (531) is used to diffract the partially coherent hard X-rays. The second aperture (532) has a second perforation. And / or, the optical component (53) further includes a first high-precision three-dimensional displacement stage (534). The first high-precision three-dimensional displacement stage (534) is connected to the moving platform of the first three-dimensional displacement stage (533), and the zone plate (531) is fixedly installed on the moving platform of the first high-precision three-dimensional displacement stage (534).

5. The partially coherent hard X-ray stacked diffraction imaging system as described in claim 4, characterized in that, The sample assembly (54) includes a second three-dimensional displacement stage (541), a second high-precision three-dimensional displacement stage (542), a rotary stage (543), a high-precision two-dimensional displacement stage (544), and a sample holder (545). The second three-dimensional displacement stage (541) is fixedly mounted on the imaging platform (52). The second high-precision three-dimensional displacement stage (542) is fixedly connected to the moving platform of the second three-dimensional displacement stage (541). The rotary stage (543) is fixedly connected to the moving platform of the second high-precision three-dimensional displacement stage (542). The high-precision two-dimensional displacement stage (544) is fixedly connected to the rotating platform of the rotary stage (543). The sample holder (545) is connected to the moving platform of the high-precision two-dimensional displacement stage (544). The high-precision two-dimensional displacement stage (544) drives the sample holder (545) to move in a plane perpendicular to the optical axis of the partially coherent hard X-ray to achieve the alignment of the imaging sample.

6. The partially coherent hard X-ray stacked diffraction imaging system as described in claim 5, characterized in that, The sample holder (545) and the high-precision two-dimensional displacement stage (544) are detachably connected; and / or, the sample holder (545) is a two-dimensional sample holder (545) or a three-dimensional sample holder (545).

7. The partially coherent hard X-ray stacked diffraction imaging system as described in claim 5, characterized in that, The imaging platform (52) is also equipped with an observation component (55) for monitoring the alignment process of the imaging sample.

8. The partially coherent hard X-ray stacked diffraction imaging system as described in claim 7, characterized in that, The observation component (55) includes a microscope camera (551) and a third three-dimensional displacement stage (552). The third three-dimensional displacement stage (552) is fixedly mounted on the imaging platform (52). The microscope camera (551) is fixedly mounted on the moving platform of the third three-dimensional displacement stage (552). The third three-dimensional displacement stage (552) drives the microscope camera (551) to move so that the imaging sample is located at the center of the field of view of the microscope camera (551) and aligned with the focal point of the microscope camera (551).

9. The partially coherent hard X-ray stacked diffraction imaging system as described in claim 5, characterized in that, The imaging platform (52) is also provided with a position measurement unit (56) for measuring the position of the zone plate (531) and the sample holder (545).

10. The partially coherent hard X-ray stacked diffraction imaging system as described in claim 1, characterized in that, The image acquisition unit (6) includes a photon counting detector (61) and a second two-dimensional displacement stage (62). The photon counting detector (61) is located at the end of the optical axis and is perpendicular to the optical axis. The photon counting detector (61) is fixedly connected to the moving platform of the second two-dimensional displacement stage (62).

Images