Near-field speckle scanning phase contrast imaging method and system based on DIC

Abstract

The present invention provides a near-field speckle scanning phase contrast imaging method and system based on DIC, including an image acquisition step: using a speckle scanning phase contrast imaging experimental system to acquire a speckle image and a speckle sample image; the speckle scanning phase contrast imaging experimental system includes a ray source, a speckle generator, a sample, a turntable and a detector; an image processing step: using a unified modulation mode analysis to process the speckle image and the speckle sample image, and outputting the processed image. Under the premise of ensuring that the sample structure information can be effectively extracted, the present invention uses a post-processing step combined with DIC to replace the step of the sample constantly entering and exiting the optical path during the experiment, thereby reducing the requirements of the experimental system on hardware facilities, shortening the experimental time, and enhancing the feasibility of the experiment.

Description

Technical Field

[0001] The present invention relates to the field of near-field speckle phase contrast imaging, and in particular to a near-field speckle scanning phase contrast imaging method and system based on DIC. Background Art

[0002] X-ray near-field speckle phase contrast imaging has attracted much attention due to its excellent sensitivity in measuring the inside of materials. Compared with traditional absorption imaging technology, this technology has higher spatial resolution, phase sensitivity and experimental flexibility, and is particularly suitable for low absorption contrast samples. At present, this technology is mainly used in the field of synchrotron radiation. Under laboratory light sources, that is, conical beams, Unified Modulated Pattern Analysis (UMPA) is mainly used for data analysis and reconstruction.

[0003] There are two main technical routes for the UMPA analysis method: single exposure mode and scanning mode. The single exposure mode performs similarity calculations between two exposure data of multiple pixels in the search window, while the scanning mode performs similarity calculations between multiple exposure data of one pixel. In the scanning mode, as the speckle generator scans, the detector records the light intensity data of each pixel, thereby forming a series of unique one-dimensional vectors. This technical route greatly improves the spatial resolution by increasing the redundancy of the data.

[0004] The currently used scanning mode requires that two sets of data, a reference image and a sample image, be collected when the optical element to be tested exits and enters the optical path. Each set of data includes multiple images, which are taken when the speckle generator is in different positions. The number of images in the two sets of data is equal and corresponds one to one, that is, the corresponding two images are taken when the speckle generator scans the same position. Therefore, each scan requires the sample to continuously enter and exit the optical path and locate to its original position, and the speckle generator is required to scan with the same step length. This places high demands on both experimental hardware and experimental operations. The experiment is time-consuming and complex, which poses challenges to both experimental hardware and operators.

[0005] In summary, although X-ray near-field speckle phase contrast imaging technology has broad application prospects in laboratory light sources, it still faces certain challenges and needs to be further simplified and optimized to improve efficiency and reliability. Summary of the invention

[0006] In view of the defects in the prior art, an object of the present invention is to provide a near-field speckle scanning phase contrast imaging system and method based on DIC.

[0007] According to the present invention, a near-field speckle scanning phase contrast imaging method based on DIC is provided, comprising:

[0008] Image acquisition steps: using a speckle scanning phase contrast imaging experimental system to acquire speckle images and speckle sample images;

[0009] The speckle scanning phase contrast imaging experimental system comprises a ray source, a speckle generator, a sample, a turntable and a detector;

[0010] Image processing steps: Use unified modulation mode analysis to process the speckle image and speckle sample image, and output the processed image.

[0011] Preferably, the image acquisition step includes fixing a speckle generator to acquire a speckle image; using a turntable to carry a sample, moving the sample at a certain step length in a direction perpendicular to the light path for scanning, and acquiring speckle sample images of the sample at different positions.

[0012] Preferably, the image acquisition step includes the following sub-steps:

[0013] Step S1.0: placing a speckle generator into the optical path and taking a number of speckle images at an initial position;

[0014] Step S1.1: Fix the speckle generator to allow the sample to be tested to enter the optical path; control the sample to be scanned in the plane perpendicular to the optical axis through the turntable, collect a speckle sample image of the sample at each different position, and form a set of one-dimensional vectors that record the changing light intensity data;

[0015] Step S1.2: Take several background images and dark signal images.

[0016] Preferably, the image processing step includes using DIC to calculate the displacement pixel difference between samples at different positions, and then intercepting and translating the region of interest to ensure that the sample is always located at the same position in the image; the region of interest includes a speckle pattern and a speckle sample pattern.

[0017] Preferably, in the region of interest, the speckle is continuously translated relative to the sample at the same step length, and each speckle sample image has a speckle image corresponding to it.

[0018] Preferably, the image processing step includes the following sub-steps:

[0019] Step S2.1: pre-processing all images; the pre-processing includes averaging the collected dark signal images and subtracting the average dark signal from all frames;

[0020] Step S2.2: Select the region of interest, use DIC to calculate the pixel displacement between the regions of interest in every two sample images, and translate the regions of interest simultaneously;

[0021] Step S2.3: indirectly measure the deflection angle of the light according to the displacement difference of the speckle on the detector plane, and reconstruct it using unified modulation mode analysis to obtain the absorption map, dark field map and phase shift map.

[0022] According to the present invention, a DIC-based near-field speckle scanning phase contrast imaging system is provided, comprising:

[0023] Image acquisition module: Use the speckle scanning phase contrast imaging experimental system to collect speckle images and speckle sample images;

[0024] The speckle scanning phase contrast imaging experimental system comprises a ray source, a speckle generator, a sample, a turntable and a detector;

[0025] Image processing module: Use unified modulation mode analysis to process speckle images and speckle sample images, and output the processed images.

[0026] Preferably, the image acquisition module includes a fixed speckle generator to acquire speckle images; a turntable is used to carry the sample, the sample is moved in a certain step length perpendicular to the direction of the light path for scanning, and speckle sample images of the sample at different positions are acquired.

[0027] Preferably, the image acquisition module includes the following submodules:

[0028] Module M1.0: put the speckle generator into the optical path and take several speckle patterns at the initial position;

[0029] Module M1.1: Fix the speckle generator to allow the sample to be tested to enter the optical path; control the sample to be scanned in the plane perpendicular to the optical axis through the turntable, collect a speckle sample image of the sample at each different position, and form a set of one-dimensional vectors that record the changing light intensity data;

[0030] Module M1.2: Take several background images and dark signal images.

[0031] Preferably, the image processing module includes using DIC to calculate the displacement pixel difference between samples at different positions, and then intercepting and translating the region of interest to ensure that the sample is always located at the same position in the image; the region of interest includes a speckle pattern and a speckle sample pattern.

[0032] Preferably, in the region of interest, the speckle is continuously translated relative to the sample at the same step length, and each speckle sample image has a speckle image corresponding to it.

[0033] Preferably, the image processing module includes the following submodules:

[0034] Module M2.1: pre-processing all images; the pre-processing includes averaging the collected dark signal images and subtracting the average dark signal from all frames;

[0035] Module M2.2: Select the region of interest, use DIC to calculate the pixel displacement between the regions of interest in every two sample images, and translate the regions of interest simultaneously;

[0036] Module M2.3: The deflection angle of the light is indirectly measured based on the displacement difference of the speckle on the detector plane, and reconstructed using unified modulation pattern analysis to obtain absorption images, dark field images and phase shift images.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1. Under the premise of ensuring that the sample structure information can be effectively extracted, the present invention uses a post-processing step combined with DIC to replace the step of continuously entering and exiting the light path of the sample during the experiment, which reduces the requirements of the experimental system on hardware facilities, shortens the experimental time, and enhances the feasibility of the experiment.

[0039] 2. The present invention does not need to move the speckle generator, but only needs to move the sample to achieve the experimental purpose, thereby reducing the demand for the number of translation stages in the near-field speckle scanning phase contrast imaging method and reducing cost.

[0040] Other beneficial effects of the present invention will be explained in the specific implementation manner through the introduction of specific technical features and technical solutions. Through the introduction of these technical features and technical solutions, those skilled in the art should be able to understand the beneficial technical effects brought about by the technical features and technical solutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0042] Figure 1 The figure is a flow chart of the method of the present invention.

[0043] Figure 2 It is a schematic diagram of the speckle scanning phase contrast imaging experimental system in the present invention.

[0044] Figure 3 It is a flowchart of the steps of the reconstruction method in the present invention.

[0045] Description of reference numerals:

[0046] Radiation source 1 turntable 4

[0047] Speckle Generator 2 Detector 5

[0048] Sample 3 DETAILED DESCRIPTION

[0049] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0050] Reference Figure 1 and Figure 2 As shown,

[0051] 1. A near-field speckle scanning phase contrast imaging method based on DIC (Digital Image Correlation, DIC), comprising:

[0052] Firstly, a near-field speckle scanning phase contrast imaging experimental system is constructed.

[0053] The experimental system includes a ray source 1, a speckle generator 2, a sample 3, a turntable 4 and a detector 5;

[0054] The speckle generator 2 remains stationary, and the speckle image is first collected. Then a turntable 4 is used to carry the sample 3, and the sample 3 is moved in a certain step length perpendicular to the optical path for scanning, and speckle sample images at different positions of the sample 3 are collected. In this experimental step, the speckle generator 2 always remains stationary, and the sample 3 only needs to be translated in a fixed step length. There is no need to use two turntables 4 to simultaneously control the speckle generator 2 to perform translation scanning in a fixed step length, and there is no need for the sample 3 to constantly enter and exit the optical path and be precisely positioned.

[0055] Reference Figure 3 As shown, a DIC-based near-field speckle scanning phase contrast imaging reconstruction method is then used.

[0056] The method includes image pre-processing, DIC calculation of sample 3 displacement and translation of the region of interest, and analysis and reconstruction of the region of interest using unified modulated pattern analysis (UMPA).

[0057] Specifically, DIC is used to calculate the displacement pixel difference between sample 3 at different positions, and the region of interest (including speckle image and speckle sample image) is intercepted and translated according to the calculated displacement pixel difference, so as to ensure that sample 3 is always located at the same position in the image, speckle is continuously translated with the same step length relative to sample 3, and each speckle sample image has a speckle image corresponding to it. In this step, by calculating the displacement between samples and performing interception and translation, the absolute motion of sample 3 relative to speckle is converted into the relative motion of speckle relative to sample 3.

[0058] Under the premise of ensuring that the sample structure information can be effectively extracted, the present invention uses a post-processing step combined with DIC to replace the step of continuously moving the sample in and out of the light path during the experiment, thereby reducing the requirements of the experimental system on hardware facilities, shortening the experimental time, and enhancing the feasibility of the experiment.

[0059] The above is a basic embodiment of the present invention. The technical solution of the present invention is further described below through a preferred embodiment.

[0060] Example 1

[0061] Reference Figure 1 and Figure 2 As shown, the near-field speckle scanning symmetric imaging system of the present invention includes a ray source 1, a speckle generator 2, a sample 3, a turntable 4 and a detector 5. During the experiment, the micro-focus X-rays generated by the X-ray source pass through the speckle generator 2 and carry the random signal modulated by the generator through the sample 3 to be tested. The sample 3 is scanned in a direction perpendicular to the optical axis (the direction indicated by the blue arrow in the figure). The X-ray near-field speckle as a "marker" of the light will be displaced in the process. The detector 5 captures the intensity, energy and position of the X-rays and converts them into electrical signals for storage. Specifically, the following steps are included:

[0062] Step S1: The speckle generator 2 enters the optical path and takes several speckle patterns at the initial position;

[0063] Step S2: the speckle generator 2 remains stationary, the sample 3 to be tested enters the optical path, and the sample 3 is scanned in a plane perpendicular to the optical axis by the control of the turntable 4. A speckle sample image is collected at each different position of the sample 3 to form a set of one-dimensional vectors that record the changing light intensity data;

[0064] Step S3: taking a number of background images and dark signal images;

[0065] Reference Figure 3 As shown, the DIC-based near-field speckle scanning phase contrast imaging reconstruction method of the present invention includes image pre-processing, DIC calculation of sample displacement and translation of the region of interest, and analysis and reconstruction of the region of interest. The specific steps are as follows:

[0066] Step Q1: Pre-process all images, including averaging the collected dark signal images, subtracting the average dark signal from all frames to eliminate the influence of dark current; dividing the reference and sample images by the dark-corrected background image to process the background non-uniformity in the image and remove the influence of the background on the image data; averaging the speckle images taken when the sample exits the light path to eliminate the influence of random errors on the image data;

[0067] Step Q2: Select the region of interest, use DIC to calculate the pixel displacement between the regions of interest of every two sample images, and translate the region of interest (including the speckle sample image and the speckle pattern) simultaneously according to the calculated displacement to ensure that the position of the sample 3 remains unchanged in the region of interest, and each speckle sample image has a speckle pattern corresponding to it;

[0068] Step Q3: For the regions of interest of the speckle pattern and the speckle sample pattern, the deflection angle of the light is indirectly measured according to the displacement difference of the speckle on the plane of the detector 5, and unified modulated pattern analysis (UMPA) is used for reconstruction to obtain absorption images, dark field images, and phase shift images.

[0069] The present invention does not need to move the speckle generator, and only needs to move the sample to achieve the experimental purpose, thereby reducing the demand for the number of displacement stages in the near-field speckle scanning phase contrast imaging method and reducing cost expenditure.

[0070] The present invention also provides a DIC-based near-field speckle scanning phase contrast imaging system, which can be realized by executing the process steps of the DIC-based near-field speckle scanning phase contrast imaging method, that is, those skilled in the art can understand the DIC-based near-field speckle scanning phase contrast imaging method as a preferred implementation of the DIC-based near-field speckle scanning phase contrast imaging system.

[0071] Specifically, a DIC-based near-field speckle scanning phase contrast imaging system includes:

[0072] Image acquisition module: Use the speckle scanning phase contrast imaging experimental system to collect speckle images and speckle sample images;

[0073] The speckle scanning phase contrast imaging experimental system comprises a ray source, a speckle generator, a sample, a turntable and a detector;

[0074] Image processing module: Use unified modulation mode analysis to process speckle images and speckle sample images, and output the processed images.

[0075] The image acquisition module includes a fixed speckle generator to acquire speckle images; a turntable is used to carry the sample, and the sample is moved in a certain step length perpendicular to the light path for scanning to acquire speckle sample images at different positions of the sample.

[0076] The image acquisition module includes the following submodules:

[0077] Module M1.0: put the speckle generator into the optical path and take several speckle patterns at the initial position;

[0078] Module M1.1: Fix the speckle generator to allow the sample to be tested to enter the optical path; control the sample to be scanned in the plane perpendicular to the optical axis through the turntable, collect a speckle sample image of the sample at each different position, and form a set of one-dimensional vectors that record the changing light intensity data;

[0079] Module M1.2: Take several background images and dark signal images.

[0080] The image processing module includes using DIC to calculate the displacement pixel difference between samples at different positions, and then intercepting and translating the region of interest to ensure that the sample is always located at the same position in the image; the region of interest includes a speckle image and a speckle sample image.

[0081] In the region of interest, the speckle is continuously translated relative to the sample at the same step length, and each speckle sample image has a speckle image corresponding to it.

[0082] The image processing module includes the following submodules:

[0083] Module M2.1: pre-processing all images; the pre-processing includes averaging the collected dark signal images and subtracting the average dark signal from all frames;

[0084] Module M2.2: Select the region of interest, use DIC to calculate the pixel displacement between the regions of interest in every two sample images, and translate the regions of interest simultaneously;

[0085] Module M2.3: The deflection angle of the light is indirectly measured based on the displacement difference of the speckle on the detector plane, and reconstructed using unified modulation pattern analysis to obtain absorption images, dark field images and phase shift images.

[0086] Those skilled in the art know that, in addition to realizing the system and its various devices, modules, and units provided by the present invention in a purely computer-readable program code, it is entirely possible to realize the same functions in the form of logic gates, switches, application-specific integrated circuits, programmable logic controllers, and embedded microcontrollers by logically programming the method steps. Therefore, the system and its various devices, modules, and units provided by the present invention can be considered as a hardware component, and the devices, modules, and units included therein for realizing various functions can also be regarded as structures within the hardware component; the devices, modules, and units for realizing various functions can also be regarded as both software modules for realizing the method and structures within the hardware component.

[0087] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0088] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A near-field speckle scanning phase contrast imaging method based on DIC, characterized in that: include: Image acquisition steps: using a speckle scanning phase contrast imaging experimental system to acquire speckle images and speckle sample images; The speckle scanning phase contrast imaging experimental system comprises a ray source, a speckle generator, a sample, a turntable and a detector; Image processing steps: using unified modulation mode analysis to process the speckle image and the speckle sample image, and outputting the processed image; The image acquisition step includes fixing a speckle generator to acquire a speckle image; Use a turntable to carry the sample, move the sample in a certain step length perpendicular to the light path for scanning, and collect speckle sample images at different positions of the sample; The image processing step includes using DIC to calculate the displacement pixel difference between samples at different positions, and then intercepting and translating the region of interest to ensure that the sample is always located at the same position in the image; the region of interest includes a speckle pattern and a speckle sample pattern; In the region of interest, the speckle is continuously translated relative to the sample at the same step length, and each speckle sample image has a speckle image corresponding to it.

2. The DIC-based near-field speckle scanning phase contrast imaging method according to claim 1, characterized in that: The image acquisition step includes the following sub-steps: Step S1.0: placing a speckle generator into the optical path and taking a number of speckle images at an initial position; Step S1.1: Fix the speckle generator to allow the sample to be tested to enter the optical path; control the sample to be scanned in the plane perpendicular to the optical axis through the turntable, collect a speckle sample image of the sample at each different position, and form a set of one-dimensional vectors that record the changing light intensity data; Step S1.2: Take several background images and dark signal images.

3. The DIC-based near-field speckle scanning phase contrast imaging method according to claim 1, characterized in that: The image processing step includes the following sub-steps: Step S2.1: pre-processing all images; the pre-processing includes averaging the collected dark signal images and subtracting the average dark signal from all frames; Step S2.2: Select the region of interest, use DIC to calculate the pixel displacement between the regions of interest in every two sample images, and translate the regions of interest simultaneously; Step S2.3: indirectly measure the deflection angle of the light according to the displacement difference of the speckle on the detector plane, and reconstruct it using unified modulation mode analysis to obtain the absorption map, dark field map and phase shift map.

4. A near-field speckle scanning phase contrast imaging system based on DIC, characterized in that: include: Image acquisition module: Use the speckle scanning phase contrast imaging experimental system to collect speckle images and speckle sample images; The speckle scanning phase contrast imaging experimental system comprises a ray source, a speckle generator, a sample, a turntable and a detector; Image processing module: uses unified modulation mode analysis to process speckle images and speckle sample images, and outputs processed images; The image acquisition module includes a fixed speckle generator to acquire speckle images; Use a turntable to carry the sample, move the sample in a certain step length perpendicular to the light path for scanning, and collect speckle sample images at different positions of the sample; The image processing module includes using DIC to calculate the displacement pixel difference between samples at different positions, and then intercepting and translating the region of interest to ensure that the sample is always located at the same position in the image; the region of interest includes a speckle pattern and a speckle sample pattern; In the region of interest, the speckle is continuously translated relative to the sample at the same step length, and each speckle sample image has a speckle image corresponding to it.

5. The DIC-based near-field speckle scanning phase contrast imaging system according to claim 4, characterized in that: The image acquisition module includes the following submodules: Module M1.0: put the speckle generator into the optical path and take several speckle patterns at the initial position; Module M1.1: Fix the speckle generator to allow the sample to be tested to enter the optical path; control the sample to be scanned in the plane perpendicular to the optical axis through the turntable, collect a speckle sample image of the sample at each different position, and form a set of one-dimensional vectors that record the changing light intensity data; Module M1.2: Take several background images and dark signal images.

Images