Synchrotron radiation X-ray nanometer coaxial holographic imaging focusing method
By introducing the Laplace image clarity recognition function and the EPICS control system, combined with the calculation of optical path geometric relationships, the problem of poor imaging quality in traditional methods is solved, and efficient and automated synchrotron radiation X-ray nano-coaxial holographic imaging is achieved, which is suitable for complex samples and dynamic environments.
Patent Information
- Application Number
- CN202511004766.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-21
- Publication Date
- 2025-09-19
AI Technical Summary
Traditional synchrotron X-ray nano-coaxial holographic imaging technology has poor imaging quality under complex samples and dynamic environments. It is especially susceptible to noise and twin image interference under strong scattering or low contrast conditions, and lacks efficient focusing optimization methods and automated control.
The Laplace image clarity recognition function is combined with equivalent distance scanning technology, and equipment integration is achieved through the EPICS control system. The optical path geometry relationship is used to calculate the object source distance and the object detection distance. The image reconstruction process is optimized by combining Laplace convolution kernel processing and GPU hardware acceleration to achieve automated collaborative motion.
It significantly improves the adaptability and robustness of the imaging system, reduces operational complexity, and improves computational efficiency and imaging accuracy. It is particularly suitable for nanoscale imaging of strongly scattering and low-contrast samples.
Smart Images
Figure CN120668696A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of coaxial holography, and in particular relates to a focusing method for synchrotron radiation X-ray nano coaxial holographic imaging. Background Art
[0002] Synchrotron X-ray nano-coaxial holographic imaging technology has important applications in materials science and biomedicine due to its advantages such as high resolution and non-destructive testing. However, the imaging quality of this technology is highly dependent on the focusing accuracy of the system. Traditional focusing methods, which are typically based on fixed optical path parameters or manual adjustments, are difficult to adapt to the dynamic requirements of complex samples. Especially under strong scattering or low-contrast conditions, they are susceptible to noise and twin image interference, resulting in blurred or distorted reconstructed images.
[0003] Traditional methods typically use independent control units to control the stage and detector, lacking a coordinated motion mechanism. This leads to mechanical vibration and triggering asynchrony, which in turn affects imaging quality. Especially in nanoscale imaging, even small errors in stage positioning accuracy and detector acquisition timing can result in blurred reconstructed images.
[0004] In recent years, researchers have attempted to optimize the focusing process using deep learning (such as the eHoloNet network) or physical model fusion algorithms (such as PhysenNet), but these methods still have significant limitations. Deep learning methods rely on large amounts of labeled data and lack generalization capabilities; while algorithms based on physical models have high computational complexity and are difficult to meet real-time imaging requirements. In addition, traditional focusing criteria (such as gradient functions) are sensitive to noise and have poor stability in dynamic environments or under multi-sample conditions. Therefore, there is an urgent need for a computationally efficient and adaptable focusing optimization method that works in conjunction with an automated and efficient control method to improve the accuracy and reliability of synchrotron radiation X-ray nano-coaxial holographic imaging and significantly reduce operational complexity. Summary of the Invention
[0005] To solve the above technical problems, the present invention provides a focusing method for synchrotron radiation X-ray nano-coaxial holographic imaging to overcome the problems in the existing technology such as difficulty in balancing computational efficiency and accuracy and poor adaptability to strong scattering / low contrast samples.
[0006] To achieve the above object, the present invention adopts the following technical solutions:
[0007] A focusing method for synchrotron radiation X-ray nano-coaxial holographic imaging, comprising:
[0008] Step 101, system establishment and initialization: constructing an optical system including a coherent light source, a focusing lens, a pinhole filter, a sample stage, a detector, and a linear translation stage for controlling the sample stage and the detector;
[0009] Step 102, preliminary debugging: preliminarily adjusting the relative position of the sample and the detector according to the target magnification;
[0010] Step 103, hologram acquisition: using a standard resolution target to acquire a hologram at the current position;
[0011] Step 104, image reconstruction and optimal distance determination: reconstruct the hologram using consecutive equivalent distances, calculate the clarity value of each reconstructed hologram, and select the equivalent distance corresponding to the maximum clarity value as the optimal reconstruction distance;
[0012] Step 105, system parameter calculation: according to the optimal reconstruction distance and system magnification, the actual object source distance and object detection distance of the optical path system are calculated based on the geometric optical relationship, and system imaging is performed according to the actual object source distance and object detection distance.
[0013] Furthermore, in step 101, the detector, sample stage, and translation stage establish a distributed control system through EPICS, wherein the translation stage is controlled by the motor module of EPICS, and the detector is driven by the areaDetector of EPICS to achieve triggering and linkage between detector exposure and translation stage movement; and the CSS human-machine interface of EPICS is used to realize real-time status monitoring of the detector image data.
[0014] Furthermore, the parallel coherent light emitted by the coherent light source is focused by the focusing lens. After the pinhole filter filters out the stray light at the focus, it is irradiated to the sample on the sample stage at a preset defocus distance. The light passing through the sample forms an interference pattern on the photosensitive surface of the detector and is recorded.
[0015] Furthermore, in step 104, the clarity of the holograms reconstructed at different virtual equivalent distances is evaluated using a Laplace image clarity recognition function to obtain a clarity value corresponding to each equivalent distance.
[0016] Furthermore, the Laplace image clarity recognition function combined with the response graph variance is used as the image clarity recognition index.
[0017] Furthermore, Laplace convolution kernel processing is applied to the hologram reconstructed at different equivalent distances to obtain its edge response map, the clarity variance value of the edge response map is calculated, and the change in clarity variance value with distance is plotted as a curve. The position with the largest variance value is the position corresponding to the equivalent distance when the image is clearest, and the equivalent distance value when the image is clearest is the optimal reconstruction distance.
[0018] Furthermore, in step 105, according to the geometric relationship of the optical path, the equivalent distance Distance from source , geophysical range The relationship is:
[0019] ,
[0020] The calculation formula of system magnification M is:
[0021] ,
[0022] Using the best reconstruction distance and magnification obtained by reconstruction, the source distance and the probe distance are inferred:
[0023] ,
[0024] .
[0025] Furthermore, step 106 is included, in which the sample or detector is moved to a new position based on the object detection distance or source distance control system, the hologram is collected again and a secondary reconstruction is performed according to the new equivalent distance, and the validity of the actual source distance and object detection distance is verified according to the image quality of the secondary reconstructed hologram.
[0026] In a second aspect, the present invention provides an electronic device comprising: one or more processors; a memory for storing one or more programs; wherein, when the one or more programs are executed by the one or more processors, the one or more processors implement the aforementioned focusing method for synchrotron radiation X-ray nano-coaxial holographic imaging.
[0027] In a third aspect, the present invention provides a computer-readable storage medium having executable instructions stored thereon, which, when executed by a processor, enables the processor to implement the aforementioned focusing method for synchrotron radiation X-ray nano-coaxial holographic imaging.
[0028] The beneficial effects of the present invention are:
[0029] First, by introducing image clarity recognition functions (such as the Laplace operator) combined with equivalent distance scanning technology, the optimal reconstruction distance can be quickly and accurately determined, effectively solving the problem of traditional methods relying on manual adjustment and low efficiency. Second, a parameter calculation model based on optical path geometry can accurately derive key parameters such as source distance and detector distance, significantly improving the system's adaptability at different magnifications. Third, through the application of the EPICS control system, the degree of automation and device response time are significantly improved. The coordinated movement between the translation stage and detector reduces image blur caused by mechanical vibration, supports remote experimental configuration and automated process execution, and significantly reduces operational complexity. Finally, a dynamic adjustment mechanism in the verification process ensures the robustness of the imaging system to complex samples and changing environments. Compared with existing technologies, this invention significantly improves computational efficiency while maintaining high precision. It is particularly suitable for nanoscale imaging of strongly scattering and low-contrast samples, providing more reliable technical support for microstructural research in fields such as materials science and life sciences. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Figure 1 This is a flow chart of a focusing method for synchrotron radiation X-ray nano-coaxial holographic imaging implemented in the present invention;
[0031] Figure 2 The optical path design in the holographic imaging process of the present invention;
[0032] Figure 3 Schematic diagram of the holographic image reconstruction principle of the present invention;
[0033] Figure 4 3. It is a comparison diagram before and after application of the method of the present invention. DETAILED DESCRIPTION
[0034] The present invention will be further described below with reference to the accompanying drawings and examples.
[0035] Figure 1 This is a flow chart of a focusing method for synchrotron radiation X-ray nano-coaxial holographic imaging according to the present invention. The method mainly includes the following steps:
[0036] Step 101, System Setup and Initialization: Build an optical system including an X-ray source, focusing lens, pinhole filter, sample stage, and detector. The system is integrated using the EPICS control system: (1) Use the motor module to control the stage and establish a PV record with target position (STAGE: X.VAL) and real-time feedback (STAGE: X.RBV); (2) Configure the detector acquisition parameters (CAM: Acquire trigger / CAM: ImageData data stream) through the areaDetector driver.
[0037] Step 102, preliminary debugging: preliminarily adjusting the relative position of the sample and the detector according to the target magnification;
[0038] Step 103, hologram acquisition: using a standard resolution target as a sample to acquire a hologram at the current position;
[0039] Step 104: Image reconstruction and optimal distance determination: Reconstruct the hologram using successive equivalent distances, calculate the clarity of each reconstructed hologram, and select the equivalent distance corresponding to the maximum clarity as the optimal reconstruction distance. Simultaneously, the system magnification is obtained by comparing the relative dimensions in the reconstructed image with the dimensions of the corresponding line pairs in the sample.
[0040] Step 105, system parameter calculation: according to the optimal reconstruction distance and system magnification, the actual object source distance and object detector distance of the optical path system are calculated based on the Fresnel scaling law and geometric optical relationships;
[0041] Step 106, verification and optimization: based on the actual control system, move the sample or detector to a new position, collect the hologram again and perform secondary reconstruction based on the new equivalent distance, and verify the validity of the actual source distance and probe distance calculated in step 105 based on the image quality of the secondary reconstructed hologram. If valid, the subsequent focused imaging system can perform imaging based on the actual source distance and probe distance calculated in step 105.
[0042] In step 101, the optical system primarily consists of a detector (an industrial CCD camera), a precision 3D motion stage, a reflector, a collimator, a focusing lens, a micrometer pinhole, and a laser. The incident light from the light source passes through the reflector and collimator, then is focused by the focusing lens. It then passes through a pinhole filter near the focal point to remove stray light. The light then strikes the sample, where it forms an interference pattern on the detector's photosensitive surface. The camera is connected to a computer via a cable, and a precision 3D motion stage is used to adjust the camera's position to ensure accurate imaging. The reflector is located in front of the camera, facilitating precise adjustment of the optical path. The collimator is used for collimation and beam expansion, the focusing lens focuses the beam for cone-beam projection amplification, and the micrometer pinhole performs spatial filtering at the focal point. Its position is finely adjusted using the adjustment stage. The laser transmits a beam through a lens system, ultimately capturing a hologram on a detector.
[0043] In step 102, the control system can adjust the position of optical components, move the sample and detector, and adjust the source and detector distances. The control system ensures precise control of the entire optical path through the linkage of software and hardware.
[0044] In step 103, a hologram at the current position is acquired using the standard resolution target USAF1951. The standard resolution target USAF1951 is a target used to test the resolution of an imaging system. It contains 6 or 10 groups of patterns, each group of patterns consisting of elements with corresponding group numbers, and is commonly used to calibrate and test the resolution and imaging quality of an imaging system. Figure 2 This paper demonstrates how an optical system can be used to focus a laser beam onto a target object, forming a hologram. Monochromatic light from a laser source is focused by a lens and then irradiated onto the object. The laser light passes through the object and continues to transmit backward, forming the object beam. The direct light that does not pass through the sample forms the reference beam. The object beam and the reference beam interfere at the detector, ultimately forming a hologram that records the complex amplitude information of the object. The quality of the hologram is affected by the optical path distance (L) from the lens to the object and the distance (d) from the object to the detector. These two parameters directly determine the image's focus and resolution. By decoding the hologram, the object's amplitude and phase information can be recovered.
[0045] In step 104, the hologram is reconstructed using a series of virtual equivalent distances, and the clarity of the reconstructed series of holograms is analyzed.
[0046] In step 104, the image reconstruction and optimal distance determination process is implemented using GPU hardware-accelerated just-in-time compilation technology. The wavefront propagation matrix calculation function and the fast Fourier transform function (FT2Dc / IFT2Dc) are dynamically compiled and optimized through a just-in-time compilation decorator (such as @jit) to eliminate the interpretation execution overhead; the parallel computing architecture of the GPU is utilized to simultaneously process multiple hologram reconstruction tasks at equivalent distances, thereby achieving a linear improvement in scanning efficiency; and the pre-allocation mechanism of forced continuous memory storage is used to reduce cache hit failures and improve data throughput.
[0047] In step 104, the Laplace image clarity recognition function is used to evaluate the clarity of the hologram reconstructed at different virtual equivalent distances, and the clarity value corresponding to each equivalent distance is obtained. Based on this, Figure 3 As shown in the figure, a curve of image clarity changing with equivalent distance is plotted. This curve reflects the quality change trend of image reconstruction at different equivalent distances, from which we can accurately find the position where the clarity reaches the maximum value. , as the "optimal reconstruction distance". For example, =0.912 means that when the equivalent propagation distance between the sample and the detector is 0.912 mm, the image reconstruction effect is optimal and the image details are clearest. Based on this, the current optimal focusing state of the system can be determined, providing a basis for subsequent magnification calculation and imaging system adjustment.
[0048] In step 104, the Laplace function is combined with the variance of the response graph as an indicator of image clarity. The Laplace convolution kernel is applied to the hologram reconstructed at different equivalent distances to obtain its edge response graph; then, the variance of the response graph is calculated to reflect the richness of image details. Since the edge information of the clear image is more significant, the Laplace response changes more dramatically, and its variance value is also larger. Therefore, by plotting the change of the clarity variance value with distance as a curve (such as Figure 3 As shown in the figure, the equivalent distance when the image is clearest (that is, the position with the largest variance value) can be intuitively judged, and this equivalent distance value is selected as the "optimal reconstruction distance".
[0049] In step 105, to achieve a quantitative conversion between the image spatial dimensions and the actual physical dimensions, an accurate estimation of the system magnification M is required. To this end, a standard resolution test target (e.g., USAF 1951) is used for calibration. By analyzing the pixel widths of known structures in the image and combining them with the physical parameters of the target, the magnification of the imaging system is inferred. An area with a clear spatial frequency in the standard resolution target (e.g., a certain group of elements) is selected, and the pixel width N of the structure in the image is measured. Based on its corresponding physical width D, the magnification can be calculated using the following formula:
[0050] ,
[0051] Where M is the magnification; is the pixel size of the detector in For the frequency in line pairs per millimeter (lp / mm) in the resolution test target, the formula for the structure width D can be expressed as:
[0052] ,
[0053] in, is the spatial frequency of the fringe group (line pairs per mm), and n is the number of line pairs selected. Combining the two equations, the general expression for magnification is as follows:
[0054] ,
[0055] Taking the USAF1951 target as an example, we select the 4th element of the 4th group (its corresponding spatial frequency is 5 lp / mm) and observe that it occupies a total of 16 lines (i.e. 8 pairs of lines) in the image, totaling N=266 pixels. If the size of a single pixel of the image sensor is , the magnification is calculated as follows:
[0056] ,
[0057] In step 105, the actual object source distance and object detection distance of the optical path system are calculated based on the optimal reconstruction distance and magnification obtained in step 104. According to the geometric relationship of the optical path, the following formula is obtained:
[0058] (1) Equivalent distance Distance from source , geophysical range The relationship is:
[0059] ,
[0060] (2) The expression of magnification is:
[0061] ,
[0062] (3) Using the optimal reconstruction distance and magnification obtained by reconstruction, we can infer:
[0063] ,
[0064] ,
[0065] According to the example of step 104 =0.912, =4.0858, the actual source distance can be calculated from the above formula =0.2953, geophysical range =0.223.
[0066] In step 106, in order to verify the accuracy of the source distance and the geophysical distance calculated in steps 104 and 105, the sample is controlled to move a certain distance S to reach the new geophysical distance and source distance , collect the sample hologram at that position. Use the new source distance and probe distance to calculate the corresponding new equivalent reconstruction distance, and reconstruct the hologram. Because of the sensitivity to the equivalent distance, the accuracy of the equivalent distance can be judged according to the quality of the secondary reconstructed image. An accurate equivalent distance can obtain a clear secondary reconstructed image, otherwise the secondary reconstructed image is blurred. Figure 4 The left side is the optimal reconstruction of the hologram in step 103, and the right side is the secondary reconstructed hologram at the new position in step 106 using the object detection distance and object source distance calculated in steps 104 and 105. The two figures obtain consistent imaging clarity, which proves the effectiveness of this method.
[0067] In a second aspect, the present invention provides an electronic device comprising: one or more processors; a memory for storing one or more programs; wherein, when the one or more programs are executed by the one or more processors, the one or more processors implement the aforementioned focusing method for synchrotron radiation X-ray nano-coaxial holographic imaging.
[0068] In a third aspect, the present invention provides a computer-readable storage medium having executable instructions stored thereon, which, when executed by a processor, enables the processor to implement the aforementioned focusing method for synchrotron radiation X-ray nano-coaxial holographic imaging.
[0069] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.
Claims
1. A focusing method for synchrotron radiation X-ray nano-coaxial holographic imaging, characterized in that: include: Step 101, system establishment and initialization: constructing an optical system including a coherent light source, a focusing lens, a pinhole filter, a sample stage, a detector, and a linear translation stage for controlling the sample stage and the detector; Step 102, preliminary debugging: preliminarily adjusting the relative position of the sample and the detector according to the target magnification; Step 103, hologram acquisition: using a standard resolution target to acquire a hologram at the current position; Step 104, image reconstruction and optimal distance determination: reconstruct the hologram using consecutive equivalent distances, calculate the clarity value of each reconstructed hologram, and select the equivalent distance corresponding to the maximum clarity value as the optimal reconstruction distance; Step 105, system parameter calculation: according to the optimal reconstruction distance and system magnification, the actual object source distance and object detection distance of the optical path system are calculated based on the geometric optical relationship, and system imaging is performed according to the actual object source distance and object detection distance.
2. The focusing method for synchrotron radiation X-ray nano-coaxial holographic imaging according to claim 1, characterized in that: In step 101, the detector, sample stage, and translation stage establish a distributed control system through EPICS, wherein the translation stage is controlled by the motor module of EPICS, and the detector is driven by the areaDetector of EPICS to achieve triggering and linkage between detector exposure and translation stage movement; and the CSS human-machine interface of EPICS is used to achieve real-time status monitoring of the detector image data.
3. The focusing method for synchrotron radiation X-ray nano-coaxial holographic imaging according to claim 2, characterized in that: The parallel coherent light emitted by the coherent light source is focused by the focusing lens. After the pinhole filter filters out the stray light at the focus, it is irradiated to the sample on the sample stage at a preset defocus distance. The light passing through the sample forms an interference pattern on the photosensitive surface of the detector and is recorded.
4. The focusing method for synchrotron radiation X-ray nano-coaxial holographic imaging according to claim 1, characterized in that: In step 104, the clarity of the holograms reconstructed at different virtual equivalent distances is evaluated using the Laplace image clarity recognition function to obtain a clarity value corresponding to each equivalent distance.
5. The focusing method for synchrotron radiation X-ray nano-coaxial holographic imaging according to claim 4, characterized in that: The Laplace image clarity recognition function combined with the response graph variance is used as the image clarity recognition index.
6. The focusing method for synchrotron radiation X-ray nano-coaxial holographic imaging according to claim 5, characterized in that: Laplace convolution kernel processing is applied to the hologram reconstructed at different equivalent distances to obtain its edge response map, calculate the clarity variance value of the edge response map, and plot the change of the clarity variance value with distance as a curve. The position with the largest variance value is the position corresponding to the equivalent distance when the image is clearest, and the equivalent distance value when the image is clearest is the optimal reconstruction distance.
7. The focusing method for synchrotron radiation X-ray nano-coaxial holographic imaging according to claim 1, characterized in that: In step 105, according to the geometric relationship of the optical path, the equivalent distance Distance from source , geophysical range The relationship is: ， The calculation formula of system magnification M is: ， Using the best reconstruction distance and magnification obtained by reconstruction, the source distance and the probe distance are inferred: ， 。 8. The focusing method for synchrotron radiation X-ray nano-coaxial holographic imaging according to claim 1, characterized in that: The method further includes step 106, wherein the sample or detector is moved to a new position based on the object detection distance or the object source distance control system, the hologram is collected again and a secondary reconstruction is performed according to the new equivalent distance, and the validity of the actual object source distance and the object detection distance is verified according to the image quality of the secondary reconstructed hologram.
9. An electronic device, characterized in that: include: one or more processors; Memory: used to store one or more programs; Wherein, when one or more programs are executed by the one or more processors, the one or more processors implement the focusing method of synchrotron radiation X-ray nano-coaxial holographic imaging as described in any one of claims 1-8.
10. A computer-readable storage medium, characterized in that Executable instructions are stored thereon, which, when executed by a processor, enable the processor to implement a focusing method for synchrotron radiation X-ray nano-coaxial holographic imaging as described in any one of claims 1-8.