A high-resolution x-ray scattering spatial correlation imaging system and method

Abstract

The application provides a high-resolution X-ray scattering spatial correlation imaging system, characterized by comprising an X-ray spatial light modulation device and a high-resolution area array detector which are arranged in sequence along the incident direction of X-rays and form a first light path, and the X-ray spatial light modulation device, a sample to be measured and a large-area area array detector which are arranged in sequence along the incident direction of X-rays and form a second light path, and the high-resolution area array detector and the large-area area array detector are electrically connected with a processor. The high-resolution X-ray scattering spatial correlation imaging method and system of the application are based on the combination of the spatial light fluctuation modulation technology, the spatial correlation imaging method and the X-ray scattering method to obtain scattering information with high spatial resolution and imaging. The application discards the high-resolution technical scheme of spot micro-focusing and two-dimensional scanning in view of the problem of low spatial resolution in traditional SAXS / WAXS measurement imaging.

Description

Technical Field

[0001] This invention relates to the field of X-ray scattering imaging technology, and in particular to a high-resolution X-ray scattering spatial correlation imaging system and method using non-focused scanning. Background Technology

[0002] X-ray scattering is a diffuse scattering phenomenon within a small angle range caused by fluctuations in the electron density inside the material within the incident region of the light spot. By acquiring two-dimensional scattering intensity information of the sample through a large-area detector, the nanostructure of large-sized samples can be characterized.

[0003] Traditional X-ray scattering measurement imaging includes small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS). As an important tool for studying the nanoscale structure of materials, it can image in both real space and reciprocal space (where the imaged scattering amplitude is the Fourier transform of the electron density distribution function of the scattering system). It is a multi-dimensional, multi-spatial imaging method and has been widely used in the study of the nanostructure information and spatial distribution of non-uniform materials in samples from biomolecules, polymers, alloys, and other fields. However, in traditional X-ray scattering measurements, the spot size is typically hundreds of micrometers, and a considerable area of ​​the sample is irradiated. For non-uniform samples, the acquired two-dimensional scattering map is a superposition of scattering information from different components within the sample, which can cause confusion and make the resolution of nanostructures in local micro-regions of the sample exceptionally difficult.

[0004] To address this issue, the literature [Hu Tao, Hua Wenqiang, Wang Yudan, et al. X-ray small-angle scattering microtomography based on Kirkpatrick-Baez mirror focusing [J]. Acta Optica Sinica, 2018, 38(1):7] reported the micro-focused X-ray small-angle scattering (μSAXS) technique. This technique uses a micro-focusing device to generate X-ray beams smaller than tens of micrometers, enabling the acquisition of scattering information within local micro-regions of the sample. Combined with two-dimensional scanning of the sample, it allows for the study and analysis of the nanostructure information and distribution of non-uniform systems. However, this method places stringent requirements on the micro-focusing device and high-precision scanning equipment, resulting in complex equipment, high cost, and the long scanning time required, which limits the large-scale application of this method.

[0005] Spatial optical fluctuation modulators are devices that modulate the spatial distribution of an optical field, enabling real-time spatial modulation of beam intensity. Spatial optical fluctuation modulation of X-rays has been successfully applied in numerous publications, such as the literature *Speckle-tracking X-ray phase-contrast imaging for samples with obvious edge-enhancement effect. APPLIED PHYSICS LETTERS[J]. 2017, 111(17)*; and the sandpaper mask used in the literature *Zhang Haipeng, Zhao Changzhe, Ju Xiaolu, et al. Research on improving image quality of crystal diffraction-spectral X-ray ghost imaging based on iterative reconstruction algorithm[J]. Acta Physica Sinica, 2022, 71(7):9*.*, which is an example of an X-ray spatial fluctuation modulation device.

[0006] Currently, correlation imaging can be used to image spatial information modulated by a spatial optical fluctuation modulator. Correlation imaging is a technique for recovering the spatial information of an object through correlation measurements of light field intensity. Due to its unique properties compared to traditional imaging, it has attracted much attention from researchers. Typically, in a correlation imaging system, the light emitted from the light source is split into two paths: a reference beam and a probe beam. The reference beam does not pass through the object; its intensity distribution is detected by a detector with spatial resolution. The probe beam illuminates the imaging object, and after interacting with it, its total transmitted light intensity is detected by a barrel detector without spatial resolution. By performing correlation calculations on the intensity values ​​of the two light fields, the spatial information of the imaged object can be reconstructed. In the field of X-ray correlation imaging, due to limited research on X-ray spectrometers, the reference beam and probe beam can also be detected separately by controlling the sample to move out of or into the light path. In practical applications, correlation imaging systems can also omit the reference optical path. Instead, a spatial light modulator generates a known spatial distribution of modulated speckle to illuminate the target object. The light intensity reflected or transmitted from the object in the reference optical path is collected by a single-pixel detector. The collected light intensity and the known modulated speckle are correlated to reconstruct the image of the object. This system is also called computational correlation imaging or single-pixel imaging. The known spatial distribution of the modulated speckle is easily achieved; for example, it can be captured and saved in advance, and images can be captured and saved while changing the state of the spatial light modulator (e.g., changing the position of the sandpaper mask). When needed, the same operation can be performed to acquire the image. In visible light correlation imaging, the spatial distribution of the modulated speckle can be calculated based on the state of a programmable spatial light modulator.

[0007] This simplification of the reference optical path has promoted the development of correlation imaging technology toward practical application. Currently, correlation imaging has shown unique application prospects in visible light imaging, radar imaging, infrared imaging (CN 109640006 A), spectral imaging (CN210862922U), X-ray imaging, and X-ray fluorescence imaging (Yishay Klein, Or Sefi, Hila Schwartz, and Sharon Shwartz, "Chemicalelement mapping by x-ray computational ghost fluorescence," Optica, 2022, 9, 63-70).

[0008] However, no reports have been published on the exploration and research related to the combination of correlation imaging technology and X-ray scattering imaging technology. Summary of the Invention

[0009] The purpose of this invention is to provide a high-resolution X-ray scattering spatial correlation imaging method and system to solve the problem of low spatial resolution in traditional SAXS / WAXS measurement imaging.

[0010] To achieve the above objectives, the present invention provides a high-resolution X-ray scattering spatial correlation imaging system, characterized in that it includes an X-ray spatial light modulation device and a high-resolution area array detector arranged sequentially along the incident direction of X-rays to form a first optical path, and the aforementioned X-ray spatial light modulation device, the sample to be tested, and a large-area area array detector arranged sequentially along the incident direction of X-rays to form a second optical path, wherein both the high-resolution area array detector and the large-area area array detector are electrically connected to a processor.

[0011] The high-resolution X-ray scattering spatial correlation imaging system further includes a beam splitting device, which is arranged in the first optical path between the X-ray spatial light modulation device and the high-resolution area array detector, and in the second optical path between the X-ray spatial light modulation device and the sample to be tested. It is configured to split the incident X-rays into transmitted light and diffracted light with different light intensity ratios but the same light field distribution.

[0012] The beam splitting device is a beam splitting crystal, an X-ray grating, or an X-ray multilayer reflector.

[0013] The first and second optical paths are overlapped, and the high-resolution area array detector, the sample to be tested, and the large-area area array detector are configured as movable optical paths that can be moved in and out.

[0014] The X-ray spatial light modulation device is a digital micro-unit array or a modulation mask that can modulate the distribution of X-ray light field. The modulation mask includes sandpaper of different mesh sizes, porous metal films, or high Z element powder films of different particle sizes and random distribution.

[0015] The X-ray spatial light modulation device is variable to change the modulation of the spatial intensity distribution of the incident X-rays.

[0016] The distance between the high-resolution area array detector located on the first optical path and the incident X-ray source is the same as the distance between the sample to be tested and the incident X-ray source located on the second optical path, and the distance between the large-area area array detector located on the second optical path and the incident X-ray source is 2 to 3 meters.

[0017] The large-area array detector is equipped with a light blocker to block direct light.

[0018] On the other hand, a high-resolution X-ray scattering spatial correlation imaging method is characterized by comprising:

[0019] S101, The high-resolution X-ray scattering spatial correlation imaging system described above was built on the experimental platform;

[0020] S102, Install the sample to be tested;

[0021] S103, the incident X-rays are spatially intensity modulated using an X-ray spatial light modulation device. Then, a high-resolution area array detector is used to record the reference light, and a large-area area array detector is used to record the probe light, thus obtaining an image pair of the reference light and the probe light.

[0022] S104, repeat step S103, and change the X-ray spatial light modulation device each time it is repeated until a sufficient number of reference light and probe light image pairs are collected.

[0023] S105 inputs all the collected reference light and probe light image pairs into the processor, and obtains high spatial resolution two-dimensional scattering image information of the sample under test according to the correlation imaging algorithm.

[0024] Step S105 specifically includes:

[0025] S1051: Select any pixel (u′,v′) on the large-area array detector, and obtain the scattering correlation imaging information of the pixel (u′,v′) of the large-area array detector according to the correlation imaging algorithm.

[0026] S1052: Traverse all pixels of the large-area array detector to obtain the scattering correlation imaging information of all pixels of the large-area array detector.

[0027] S1053: Scattering-related imaging information S corresponding to each pixel (u′, v′) of a large-area array detector. u′v′ Select the scattering-correlated imaging information S respectively u′v′ The elements corresponding to the pixels (m′,n′) of the high-resolution area array detector are recombined to obtain high spatial resolution two-dimensional scattering image information of the micro-element region corresponding to the pixels (m′,n′) of the high-resolution area array detector on the sample under test.

[0028] The high-resolution X-ray scattering spatial correlation imaging method and system of the present invention are based on spatial light fluctuation modulation technology and the combination of spatial correlation imaging method and X-ray scattering method to obtain scattering information with high spatial resolution and imaging. In view of the problem of low spatial resolution in traditional SAXS / WAXS measurement imaging, the high-resolution technical solution of micro-focusing and two-dimensional scanning of light spot is abandoned.

[0029] The high-resolution X-ray scattering spatial correlation imaging method of this invention has the following advantages: First, large-spot high spatial resolution X-ray scattering imaging based on X-ray spatial light modulation equipment and correlation imaging technology can achieve high spatial resolution that traditional large-spot X-ray scattering measurements cannot achieve. The spatial resolution is far superior to that of the incident spot size and can be consistent with the resolution of spatial intensity modulation. Second, the scheme of this invention does not require focusing the incident spot or performing precise two-dimensional scanning of the sample. The imaging device is relatively simple, with low equipment precision requirements. The scheme of using an X-ray beam splitter to split the beam and simultaneously record the spatially modulated reference light and the scattered signal probe light has a faster imaging speed. It avoids the requirements for micro-focusing devices and high-precision scanning devices, and this method can be applied on a large scale. Attached Figure Description

[0030] Figure 1 This is an overall structural diagram of a high-resolution X-ray scattering spatial correlation imaging system according to a first embodiment of the present invention.

[0031] Figure 2 This is a flowchart of a high-resolution X-ray scattering spatial correlation imaging method according to a second embodiment of the present invention. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments disclosed in the present invention will be described in further detail below with reference to the accompanying drawings.

[0033] First embodiment: A high-resolution X-ray scattering spatial correlation imaging system

[0034] like Figure 1The image shows a high-resolution X-ray scattering spatial correlation imaging system according to an embodiment of the present invention. The imaging system includes an X-ray spatial light modulation device 1, a beam splitter 2 (such as a beam splitter crystal), and a high-resolution area array detector 3 arranged sequentially along the incident direction of X-rays to form a first optical path, and the X-ray spatial light modulation device 1, the beam splitter 2, the sample to be tested 7, and the large-area area array detector 4 arranged sequentially along the incident direction of X-rays to form a second optical path. Both the high-resolution area array detector 3 and the large-area area array detector 4 are electrically connected to a processor 6.

[0035] Therefore, in the high-resolution X-ray scattering spatial correlation imaging system of the present invention, the incident X-rays first pass through the X-ray spatial light modulation device 1 to form spatial fluctuation modulation incident light, and then pass through the beam splitter 2 to split the incident X-rays into two beams with the same light field distribution but different light intensity ratios: transmitted light and diffracted light, with a certain angle between the two beams. The diffracted light has a smaller light intensity ratio, and the diffracted light emitted from the beam splitter 2 is detected and recorded by the high-resolution area array detector 3 in the near field to obtain the X-ray spatial modulation distribution pattern as a reference light. The transmitted light has a larger light intensity ratio, and the transmitted light is incident on the sample 7 to be tested. The scattered signal obtained after passing through the sample 7 is detected and recorded by the large-area area array detector 4 in the far field to obtain the X-ray scattering distribution pattern as the probe light.

[0036] In this embodiment, the X-ray spatial light modulation device 1 can be a digital micro-unit array, or a modulation mask that modulates the distribution of the X-ray light field, such as sandpaper of different mesh sizes, porous metal films, high-Z element powder films of different particle sizes and random distribution, or other non-uniform masks. The micro-units of the X-ray spatial light modulation device 1 can be unstructured, or their structure can be indistinguishable. The structural dimensions of the micro-units of the X-ray spatial light modulation device 1 are consistent with the pixel size of the high-resolution area array detector 3, meaning that the spatial resolution of the high-resolution area array detector 3 matches the spatial resolution of the X-ray spatial light modulation device 1. The adjusted light field of the X-ray spatial light modulation device 1 preferably satisfies a Hadamard matrix distribution for better results, but other distributions of the adjusted light field are also applicable. The aforementioned sandpaper of different mesh sizes, porous metal films, high-Z element powder films of different particle sizes and random distribution, or other non-uniform masks can modulate the incident X-rays, forming spatially random speckle patterns. In summary, the X-ray spatial light modulation device 1 will generate X-ray pseudothermal light, providing sufficient and necessary conditions for subsequent correlation imaging.

[0037] The X-ray spatial light modulation device 1 is variable, allowing for variations in the spatial intensity distribution modulation of the incident X-rays. Thus, while varying the spatial intensity distribution modulation of the incident X-rays, different probe and reference beams are recorded multiple times until a sufficient number of probe and reference beam image pairs are recorded. The digital micro-unit array independently controls the switching state of each of its micro-units to intercept or allow the incident X-rays to pass through, thereby enabling the variation of the X-ray spatial light modulation device 1. Furthermore, the modulation mask, such as sandpaper, changes its position through step scanning, further enabling the variation of the X-ray spatial light modulation device 1.

[0038] It should be noted that the number of image pairs of probe and reference light obtained from the transformation of the X-ray spatial light modulation device 1 is not fixed. A higher number of image pairs results in a better signal-to-noise ratio. Furthermore, the number of image pairs is also related to the number of pixels in the high-resolution area array detector 3; a higher pixel count requires more image pairs of probe and reference light. The required number of image pairs of probe and reference light is approximately on the same order of magnitude as the number of pixels in the high-resolution area array detector 3. Combined with compressed sensing algorithms, the number can be further reduced.

[0039] In this embodiment, the beam splitter 2 can be a beam splitting crystal such as a face-centered cubic silicon (Si) crystal, an X-ray grating, or an X-ray multilayer mirror. The size of the beam splitter 2 can cover the incident light spot. When the angle between the crystal plane of the beam splitter 2 and the incident direction of the X-ray satisfies the Bragg angle corresponding to the incident X-ray, diffraction will occur on the (001) crystal plane to form one diffracted beam and another transmitted beam. The X-ray grating can also split the incident X-rays into two or more beams with the same light field but different intensity ratios, and the main beam and the diffracted beam form a certain angle. The X-ray multilayer mirror can also split the incident X-rays into two or more beams with the same light field but different intensity ratios, and the main beam and the diffracted beam form a certain angle. Thus, the beam splitter 2 can split the incident X-rays into two beams with different intensity ratios but the same light field distribution, one of which is the transmitted light with a higher intensity ratio, and the other is the diffracted light with a lower intensity ratio. In this embodiment, the portion of the first optical path downstream of the beam splitter 2 is a diffraction optical path, which allows the diffracted light to reach the high-resolution area array detector 3; the portion of the second optical path downstream of the beam splitter 2 is a transmission optical path, which allows the transmitted light to pass through the sample to be tested 7 and reach the large-area area array detector 4.

[0040] In some other embodiments, the beam splitter 2 can be omitted, the first and second optical paths are overlapped, and the high-resolution area array detector 3, the sample 7 to be tested, and the large-area area array detector 4 are configured as movable-in and movable-out optical paths. That is, the beam splitting function of the beam splitter 2 can be replaced by a virtual beam splitting scheme that controls the movement of the sample into and out of the optical path. That is, without the beam splitter 2, the sample 7 to be tested is moved out of the optical path, and the high-resolution area array detector 3 is moved into the original position of the sample 7 in the optical path. The reference light obtained after modulation by the X-ray spatial light modulation device 1 is detected and recorded. Then, the high-resolution area array detector 3 is moved out of the optical path, and the sample 7 to be tested and the large-area area array detector 4 are moved into the original optical path. The scattering image is detected and recorded, and recorded as the probe light. In this way, the two beams of light split by the original beam splitter 2 can be collected step by step.

[0041] In this embodiment, the distance between the high-resolution area array detector 3 located on the first optical path and the incident X-ray source is the same as the distance between the sample under test 7 located on the second optical path and the incident X-ray source. The distance between the large-area area array detector 4 located on the second optical path and the incident X-ray source meets the signal acquisition requirements of scattering imaging, approximately 2 to 3 meters, and the scattering imaging is small-angle scattering (SAXS) or wide-angle scattering (WAXS).

[0042] In this embodiment, the high-resolution area array detector 3 and the large-area area array detector 4 can be X-ray indirect imaging detectors based on sensor types such as CCD / CMOS / amorphous silicon / semiconductor oxide (IGZO), or they can be direct imaging detectors such as amorphous selenium or X-ray photon counting. The high-resolution area array detector 3 has a resolution in the range of several micrometers to tens of micrometers, and its effective area is larger than the spot size, i.e., both its length and width are in the range of hundreds of micrometers. The large-area area array detector 4 has a resolution in the range of tens of micrometers to hundreds of micrometers, and its effective area has both its length and width in the range of tens of centimeters.

[0043] The large-area array detector 4 is equipped with a light blocker 5 to block the direct light (i.e., transmitted light). The size of the light blocker 5 needs to cover the size of the direct light spot, and the thickness depends on the material. The purpose is to reduce the direct light spot and avoid strong light damaging the large-area array detector 4.

[0044] The processor 6 is configured to receive all image pairs of the probe light and reference light, and perform correlation calculations using a spatial correlation imaging algorithm to obtain high spatial resolution two-dimensional scattering image information of the sample under test 7 (i.e., the two-dimensional scattering intensity distribution of all spatial micro-regions of the sample under test). The processor then uses this high spatial resolution two-dimensional scattering image information to analyze and obtain the corresponding nanostructure information of each micro-region. The spatial resolution of the two-dimensional scattering image information is significantly better than the incident X-ray spot size, and can be consistent with the resolution of the high-resolution detector in the reference optical path.

[0045] The second embodiment is a high-resolution X-ray scattering spatial correlation imaging method.

[0046] like Figure 2 The image shown is a high-resolution X-ray scattering spatial correlation imaging method according to a second embodiment of the present invention. This imaging method may specifically include:

[0047] Step S101: Build the high-resolution X-ray scattering spatial correlation imaging system described above on the experimental platform;

[0048] Step S102: Install the sample to be tested 7;

[0049] In this embodiment, a beam splitter 2 is used. Therefore, installing the sample to be tested 7 includes placing the sample to be tested 7 on the second optical path and downstream of the beam splitter 2.

[0050] Thus, the incident X-rays undergo spatial intensity modulation by the X-ray spatial light modulation device 1, and after being split by the beam splitter 2, the transmitted light is output to the sample under test 7. The scattered signal of the sample under test 7 continues to be transmitted to the large-area array detector 4 and is recorded as the probe light. The other optical path split by the beam splitter is transmitted to the high-resolution array detector 3 and is recorded as the reference light.

[0051] In step S103, the incident X-rays are spatially intensity modulated using the X-ray spatial light modulation device 1. Then, the reference light is recorded using the high-resolution area array detector 3, and the probe light is recorded using the large-area area array detector 4, thus obtaining an image pair of the reference light and the probe light.

[0052] Step S104: Repeat step S103, and transform the X-ray spatial light modulation device 1 each time it is repeated until a sufficient number of reference light and probe light image pairs are acquired.

[0053] In this embodiment, the number of image pairs of reference light and probe light is on the same order of magnitude as the number of pixels of the high-resolution area array detector 3.

[0054] Among them, reference light I k for:

[0055]

[0056] Detector light S k for:

[0057]

[0058] Among them, I k As a reference light, S kFor the probe light, k is the number of imaging iterations, i.e., the kth imaging; M and N are the number of rows and columns of the matrix of the high-resolution area array detector 3, and m and n are the row and column coordinates of the matrix of the high-resolution area array detector 3; U and V are the number of rows and columns of the matrix of the large-area area array detector 4, and u and v are the row and column coordinates of the matrix of the large-area area array detector 4; I mn k S represents the light intensity at the pixel in the m-th row and n-th column of the high-resolution area array detector 3 during the k-th imaging; uv k Let be the light intensity at the pixel in the u-th row and v-th column of the large-area array detector 4 during the k-th imaging.

[0059] In step S105, all the collected image pairs of reference light and probe light are input into processor 6, and high spatial resolution two-dimensional scattering image information of the sample under test 7 is obtained according to the correlation imaging algorithm.

[0060] Step S105 specifically includes:

[0061] Step S1051: Select any pixel (u′, v′) on the large-area array detector 4, and obtain the scattering correlation imaging information of the pixel (u′, v′) of the large-area array detector 4 according to the correlation imaging algorithm.

[0062] The formula for calculating the scattering correlation imaging information of pixels (u′, v′) of the large-area array detector 4 is as follows:

[0063]

[0064] Where K is the total number of images, and k is the number of images; S u’v’ k Let be the light intensity at the pixel in the u'th row and v'th column of the large-area array detector 4 during the kth imaging.

[0065] The scattering correlation imaging information of pixels (u′, v′) of the large-area array detector 4 is represented as follows:

[0066]

[0067] in, It is the intensity of the scattering signal generated by the interaction between the micro-region corresponding to the pixel in the m-th row and n-th column of the high-resolution area array detector 3 and the sample under test on the pixel (u′, v′) of the large-area area array detector 4.

[0068] It should be noted that the above algorithm is the most basic correlation imaging algorithm. In addition, there are differential correlation imaging algorithms, normalized correlation imaging algorithms, compressed sensing correlation imaging algorithms, artificial intelligence correlation imaging algorithms, etc., all of which can be easily combined with this patent to calculate the scattering correlation imaging information S of the pixels (u′, v′) of the large-area array detector 4. u ′v′ .

[0069] Step S1052: Traverse all pixels of the large-area array detector 4 to obtain the scattering correlation imaging information of all pixels of the large-area array detector 4.

[0070] The probe light S before correlation calculation was performed k It is a scattered signal within a large light spot area, which has low resolution. This invention repeats the signal K times to exchange spatial resolution for many times.

[0071] Step S1053: For each pixel (u′, v′) of the large-area array detector 4, the scattering correlation imaging information S u′v′ Select the scattering-correlated imaging information S respectively u′v′ The elements corresponding to the pixels (m′,n′) of the high-resolution area array detector 3 are recombined to obtain the high spatial resolution two-dimensional scattering image (SAXS / WAXS image) information of the micro-element region corresponding to the pixels (m′,n′) of the high-resolution area array detector 3 on the sample under test 7.

[0072] Among them, the high spatial resolution two-dimensional scattering image information of the micro-element region corresponding to the pixel (m′,n′) of the high-resolution area array detector 3 on the sample under test 7 is as follows:

[0073]

[0074] This represents the high spatial resolution two-dimensional scattering image information of the micro-element region corresponding to the pixel (m′,n′) of the high-resolution area array detector 3, which is inverse spatial information. It is the intensity of the scattering signal generated by the interaction between the micro-region corresponding to the pixel in the m'th row and n'th column of the high-resolution area array detector 3 and the sample under test on the pixel (u,v) of the large-area area array detector 4.

[0075] In addition, step S1054 may be included: based on the relationship between the scattering signal and the scattering cross section in the scattering imaging, the two-dimensional scattering image information is processed by integration, curve fitting, coordinate transformation, etc., to recover the high spatial resolution scattering intensity / scattering cross section / scattering curve characteristic value and other parameters of the micro-element region corresponding to the pixel (m′,n′) of the high-resolution array detector 3 on the sample, and obtain the crystallization information, pore size distribution, orientation information and other nanostructure information of the corresponding region of the sample.

[0076] The core innovation of this patent lies in obtaining high-resolution scattering intensity imaging data from low-resolution scattering experimental data based on spatial correlation imaging (i.e., As for the calculation formulas for recovering the high spatial resolution scattering cross-section / scattering curve characteristic values ​​of the corresponding micro-element region and the corresponding region's crystallization information, pore size distribution, orientation information, and other nanostructure information from high-resolution scattering experimental data, each scholar, experiment, and material has its own personalized formula analysis.

[0077] The explanation is as follows:

[0078] X-ray scattering refers to the scattering phenomenon within a small-angle (SAXS) and large-angle (WAXS) range that deviates from the original beam when irradiated by X-rays, due to fluctuations in the electron density within the material. The most basic theoretical model of scattering experiments can be described as follows: an X-ray plane wave irradiates a unit surface element of a material, scattering to form a spherical wave. The ratio of the intensity of the scattered wave recorded by the detector to the intensity of the incident wave is called the scattering cross section. The scattering cross section can also be understood as the probability of scattering occurring on a unit surface element. Because the vibration frequency of X-rays is too high, current detector technology cannot detect the phase information of X-rays; therefore, the measured X-ray intensity information is the scattering intensity, which is also the modulus square of the scattering amplitude. Data processing operations such as integrating the scattering intensity within a specific scattering angle or azimuth range on the X-ray scattering intensity distribution of a sample can yield the corresponding scattering curve. Further data processing operations such as fitting the obtained specific scattering curve can reveal nanostructure information such as crystallization information, pore size distribution, and orientation information in the corresponding region of the sample. The data processing methods differ for different types of samples. For example, the crystal form, crystallinity, and orientation information of polymers, the pore distribution and crystal form information of carbon fibers, and the distribution of cellulose crystals inside wood, etc. Each scholar, experiment, and material has its own personalized formula analysis.

[0079] Therefore, the high-resolution X-ray scattering spatial correlation imaging system of the present invention utilizes an X-ray spatial light modulation device to generate X-ray incident light with different spatial fluctuation modulations, and uses a beam splitter to split the incident light into two beams. The diffracted light is directly used to record the incident spatially modulated light field, while the transmitted light is incident on the sample and used to record the sample's scattering pattern. Using the spatially modulated light field as the reference light and the corresponding scattering pattern as the probe light, by recording the reference light and probe light multiple times in a sufficient number of times, the high spatial resolution two-dimensional scattering image information of the sample under test is calculated using a spatial correlation imaging algorithm. In the spatial correlation imaging calculation of scattering information, each pixel in the probe light field is used as an independent point probe signal in the correlation imaging and correlated with the two-dimensional plane probe signal in the reference light field. In this way, by traversing all the pixels of the probe light, the two-dimensional scattering light field distribution in any micro-region on the sample can be obtained.

[0080] The theoretical basis of the high-resolution X-ray scattering spatial correlation imaging system of the present invention is that the coherence length of the X-ray beam emitted by the current micro-focus X-ray tube and the X-ray beam emitted by synchrotron radiation is usually on the micrometer scale. Therefore, the coherent superposition of scattered light from sample micro-areas larger than the micrometer scale can be ignored, that is, the mutual interference between particles can be ignored when calculating the scattering intensity of the system. Thus, at the sample location, based on the spatially modulated optical field resolution (i.e., the resolution of the high-resolution detector in the reference optical path), the X-ray incident spot is divided into several differential units. Each differential unit has a different nanostructure distribution and corresponding scattering cross-section and scattering intensity. The sample distribution within each differential unit can be considered uniform. The scattering signal is the signal generated by the interaction between all the X-rays (spot area) incident on the sample received from a distance by the large-area array detector 4 and the sample in that area. One or more parameters obtained through data processing from the signal on the large-area array detector 4 represent the scattering intensity or scattering properties of this area. Furthermore, the scattering cross-section of each differential unit is independent; that is, the scattering map acquired during the experiment can be considered as a direct, incoherent sum of the scattering distributions corresponding to all differential units on the incident spot. Through spatial correlation imaging, the scattering cross-section and scattering intensity within any differential unit can be calculated independently. The size of the differential unit matches the resolution of the high-resolution array detector 3, thus improving the resolution.

[0081] Traditional X-ray scattering data analysis, lacking spatial resolution in this case, can only assume that the sample's internal structure is uniform within the incident light spot area (which may not actually be uniform, but is simply indistinguishable). The result is average nanostructure information of the sample, with a resolution equal to the size of the light spot.

[0082] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Various variations can be made to the above embodiments of the present invention. All simple and equivalent changes and modifications made in accordance with the claims and description of this application fall within the protection scope of the claims of this patent. All aspects not described in detail in this invention are conventional technical content.

Claims

1. A high-resolution X-ray scattering spatial correlation imaging method, characterized in that, include: Step S101: A high-resolution X-ray scattering spatial correlation imaging system is built on the experimental platform. The high-resolution X-ray scattering spatial correlation imaging system includes an X-ray spatial light modulation device and a high-resolution area array detector arranged sequentially along the incident direction of X-rays to form a first optical path, and the X-ray spatial light modulation device, the sample to be tested, and a large-area area array detector arranged sequentially along the incident direction of X-rays to form a second optical path. Both the high-resolution area array detector and the large-area area array detector are electrically connected to a processor. The incident X-rays first pass through an X-ray spatial light modulation device to form spatial fluctuation modulation incident light, and then pass through a beam splitter to split the incident X-rays into two beams with the same light field distribution but different light intensity proportions: transmitted light and diffracted light. The diffracted light has a smaller light intensity proportion. The diffracted light emitted from the beam splitter is detected and recorded by a high-resolution area array detector in the near field to obtain the X-ray spatial modulation distribution pattern as a reference light. The transmitted light has a larger light intensity proportion. The transmitted light is incident on the sample to be tested. The scattered signal obtained after passing through the sample is detected and recorded by a large-area area array detector in the far field to obtain the X-ray scattering distribution pattern as the probe light. Step S102: Install the sample to be tested; Step S103: Spatial intensity modulation of incident X-rays is performed using an X-ray spatial light modulation device. Then, a reference light is recorded using a high-resolution area array detector, and a probe light is recorded using a large-area area array detector to obtain an image pair of reference light and probe light. Step S104: Repeat step S103, changing the X-ray spatial light modulation device each time it is repeated, until a sufficient number of reference light and probe light image pairs are acquired. Reference light I k for: ， Among them, I k The reference light is k, the number of imaging iterations is k; M and N are the number of rows and columns of the high-resolution area array detector matrix, and m and n are the row and column coordinates of the high-resolution area array detector matrix; U and V are the number of rows and columns of the large-area area array detector matrix; I mn k Let be the light intensity at the pixel in the m-th row and n-th column of the high-resolution area array detector during the k-th imaging. Step S105: Input all the collected image pairs of reference light and probe light into the processor, and obtain the high spatial resolution two-dimensional scattering image information of the sample under test according to the correlation imaging algorithm. Step S105 specifically includes: Step S1051: Select any pixel on the large-area array detector. Based on the correlation imaging algorithm, the pixels of the large-area array detector are obtained. Scattering-related imaging information; Pixels of a large-area array detector The formula for calculating scattering-correlated imaging information is: ， Where K is the total number of images, k is the number of images, and I k For reference light; S u’v’ k Let be the light intensity at the pixel in the u'-th row and v'-th column of the large-area array detector during the k-th imaging; Pixels of a large-area array detector The scattering-correlated imaging information is represented as follows: ， in, The scattered signal generated by the interaction between the micro-region corresponding to the pixel in the m-th row and n-th column of the high-resolution area array detector and the sample under test is displayed on the large-area area array detector pixels. Strength on; Step S1052: Traverse all pixels of the large-area array detector to obtain the scattering correlation imaging information of all pixels of the large-area array detector. Step S1053: For each pixel of the large-area array detector Corresponding scattering correlation imaging information Select the scattering-related imaging information respectively Pixels of high-resolution area array detectors in The corresponding elements are recombined to obtain the pixels on the sample under test corresponding to the high-resolution area array detector. High spatial resolution two-dimensional scattering image information of the corresponding micro-element region; Pixels on the sample under test and the high-resolution area array detector High spatial resolution two-dimensional scattering image information of the corresponding micro-element region for: ， It is the intensity of the scattering signal generated by the interaction between the micro-region corresponding to the pixel in the m'th row and n'th column of the high-resolution area array detector and the sample under test on the pixel (u,v) of the large-area area array detector.

2. The high-resolution X-ray scattering spatial correlation imaging method according to claim 1, characterized in that, It also includes a beam splitting device, which is arranged in the first optical path between the X-ray spatial light modulation device and the high-resolution area array detector, and in the second optical path between the X-ray spatial light modulation device and the sample to be tested. It is configured to split the incident X-rays into transmitted light and diffracted light with different light intensity ratios but the same light field distribution.

3. The high-resolution X-ray scattering spatial correlation imaging method according to claim 2, characterized in that, The beam splitting device is a beam splitting crystal, an X-ray grating, or an X-ray multilayer reflector.

4. The high-resolution X-ray scattering spatial correlation imaging method according to claim 1, characterized in that, The first and second optical paths are overlapped, and the high-resolution area array detector, the sample to be tested, and the large-area area array detector are configured as movable optical paths that can be moved in and out.

5. The high-resolution X-ray scattering spatial correlation imaging method according to claim 1, characterized in that, The X-ray spatial light modulation device is a digital micro-unit array or a modulation mask that can modulate the distribution of X-ray light field. The modulation mask includes sandpaper of different mesh sizes, porous metal films, or high Z element powder films of different particle sizes and random distribution.

6. The high-resolution X-ray scattering spatial correlation imaging method according to claim 5, characterized in that, The X-ray spatial light modulation device is variable to change the modulation of the spatial intensity distribution of the incident X-rays.

7. The high-resolution X-ray scattering spatial correlation imaging method according to claim 1, characterized in that, The distance between the high-resolution area array detector located on the first optical path and the incident X-ray source is the same as the distance between the sample to be tested and the incident X-ray source located on the second optical path, and the distance between the large-area area array detector located on the second optical path and the incident X-ray source is 2 to 3 meters.

8. The high-resolution X-ray scattering spatial correlation imaging method according to claim 1, characterized in that, The large-area array detector is equipped with a light blocker to block direct light.

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