X-ray real-time imaging apparatus and method based on image plane coherent diffraction imaging

Abstract

The application discloses an X-ray real-time imaging device and method based on an image plane coherent diffraction imaging, and the device comprises an X-ray source, an adjustable slit, an object to be measured, a first three-dimensional translation stage, a multi-focus photon sieve, a second three-dimensional translation stage, an X-ray detector and a computer; the imaging device has the characteristics of single optical path, compactness, simplicity and easy operation, and only a single intensity image needs to be recorded, so that the imaging device robustness can be improved by avoiding multiple operations; the imaging method can be used for X-ray to terahertz band imaging, and can realize accurate reproduction of a complex amplitude image of the object to be measured in real time and on line.

Description

Technical Field

[0001] The present invention relates to coherent diffraction imaging, and in particular to an X-ray real-time imaging device and method based on image plane coherent diffraction imaging. Background Art

[0002] Coherent diffraction imaging is a key technology in materials science and biology, with broad application prospects in materials testing, three-dimensional display, and bioimaging. In materials testing, coherent diffraction imaging can determine the three-dimensional structure of amorphous materials, including the identification of defects and stress fields in nanocrystals and the quantitative detection of non-ordered materials such as nanoparticles. In three-dimensional display, coherent diffraction imaging can image entire cells in three dimensions and can be used to locate specific multi-protein complexes within cells. In bioimaging, coherent diffraction imaging has great potential for imaging large single protein complexes.

[0003] The application of coherent diffraction imaging is increasing in various fields, and research on coherent diffraction imaging is becoming increasingly important. In 1952, Sayre proposed the concept of coherent diffraction imaging and pointed out that if the diffraction pattern between Bragg diffraction peaks is measured with a sufficiently small sampling interval, the lost phase can be recovered using the known information. In 1972, Gerchberg et al. proposed the Gerchberg-Saxton (GS) algorithm when studying the phase retrieval problem in electron microscopy. Two intensity images were measured at the object surface and in the far field, respectively, and phase reconstruction based on diffraction theory was first achieved through an iterative algorithm. Generally, coherent diffraction imaging algorithms require multiple image detectors or mobile image detectors to collect data in multiple planes during the iterative process. The system structure is complex, and multiple iterations are required to converge the optimization. The imaging accuracy is low. Multiple mechanical operations introduce errors such as system vibration. System errors often increase with the number of exposures, limiting the application of real-time imaging detection. Summary of the Invention

[0004] To overcome this limitation, the present invention provides a real-time X-ray imaging device and method based on image-plane coherent diffraction imaging. This method simply records a single intensity image and then uses an image-plane coherent diffraction imaging algorithm to rapidly reconstruct the complex amplitude distribution of the object being measured in real time. This method avoids mechanical errors caused by multiple operations, suppresses air turbulence and system vibration, and significantly improves the robustness of the imaging device. Furthermore, the device utilizes amplitude-type optical elements as its primary optical element, making it suitable as a real-time X-ray imaging device for image-plane coherent diffraction imaging.

[0005] The technical solutions of the present invention are as follows:

[0006] An X-ray real-time imaging device based on image plane coherent diffraction imaging is characterized by comprising an X-ray source, an adjustable slit, a first three-dimensional translation stage for placing an object to be measured, a multi-focus photon sieve, a second three-dimensional translation stage and a computer, and an X-ray detector fixed on the second three-dimensional translation stage;

[0007] The light pulses emitted by the X-ray source are expanded by the adjustable slit, and the expanded light beam serves as the incident light beam, which can cover the object to be measured;

[0008] The incident light beam is incident on the object to be measured, is transmitted through the object to be measured, passes through the multi-focal photon sieve and reaches the X-ray detector;

[0009] The distance between the object to be measured and the multifocal photon sieve is u;

[0010] The distance between the multi-focal photon sieve and the X-ray detector is d;

[0011] The multi-focal photon sieve has n (n = 2, 3, 4, ...) focal lengths, which are f1, f2, ... f n ;

[0012] The output end of the X-ray detector is connected to the input end of the computer;

[0013] The computer has corresponding data recording, acquisition and processing software for recording intensity graphs and data processing.

[0014] The method for performing imaging using the above-mentioned X-ray real-time imaging device based on image plane coherent diffraction imaging is characterized in that the method comprises the following steps:

[0015] 1) Fixing the object to be measured on the first three-dimensional translation stage and fixing the X-ray detector on the second three-dimensional translation stage;

[0016] Turning on the X-ray source, so that the light pulses emitted by the X-ray source are incident on the object to be measured after being expanded by the adjustable slit;

[0017] The multifocal photon sieve has n image planes, and the distances between the n image planes and the multifocal photon sieve are v1, v2, ... v n ;

[0018] The first three-dimensional translation stage and the second three-dimensional translation stage are moved so that a diffraction intensity pattern of the object to be measured appears on the X-ray detector, wherein the diffraction intensity pattern has n non-overlapping diffraction sub-intensity patterns, and the diffraction distances of the n diffraction sub-intensity patterns are d-v1, d-v2, ..., dv n ;

[0019] Recording the diffraction intensity pattern by the X-ray detector;

[0020] 2) Extract n diffraction intensity regions from the intensity map, denoted as I1(x,y,d-v1), I2(x,y,d-v2), ...I n (x,y,dv n ), where (x, y) is the spatial coordinate distribution of the recording surface;

[0021] 3) The extracted n diffraction intensity regions are regarded as diffraction intensity maps recorded on n diffraction surfaces, and an image plane coherent diffraction imaging algorithm is used for iterative calculation to obtain the complex amplitude distribution of the object under test, i.e., imaging. The iterative calculation steps are as follows:

[0022] Assume that the complex amplitude distribution of the measured object on the first diffraction surface is Among them, the amplitude distribution of U(x,y,d-v1) is Phase distribution of U(x,y,d-v1) is an arbitrary constant;

[0023] Transmit U(x, y, d-v1) to the first image plane to obtain the complex amplitude distribution U(x1, y1, v1) of the object under test on the first image plane, and perform scaling calculation on U(x1, y1, v1) to obtain the complex amplitude distribution U(x2, y2, v2) of the object under test on the second image plane;

[0024] Transmit U(x2, y2, v2) to the second diffraction surface to obtain the complex amplitude distribution of the measured object (3) on the second diffraction surface Where H2 is the amplitude distribution of U(x,y,d-v2), is the phase distribution of U(x,y,d-v2);

[0025] Use the recorded intensity value I2(x,y,d-v2) to replace and update the amplitude distribution H2 of U(x,y,d-v2) while maintaining the phase distribution of U(x,y,d-v2) Keep it unchanged and update the calculation formula to:

[0026] The updated U'(x,y,d-v2) is used to continue transmitting to the second image plane, and scaling calculation, transmission, replacement and update are performed to obtain the complex amplitude distribution U'(x,y,d-v3) of the object under test on the third diffraction plane, until it is transmitted to the last diffraction plane, and the complex amplitude distribution U x,y,dv of the object under test on the nth diffraction plane is obtained.n ), and calculate U x,y,dv according to the following formula n )’s normalized mean square error E:

[0027]

[0028] When E is greater than or equal to 10 -3 Repeat the above iterative process to achieve E less than 10 -3 Effect; when E is less than 10 -3 , end the iteration process and set U x,y,dv n ) is transmitted inversely to the nth image plane, and the complex amplitude distribution U(x n ,y n ,v n ), the formula is as follows:

[0029] U(x n ,y n ,v n )=F -1 {F{U(x,y,dv n )}H0(f X ,f Y )},

[0030] in, is the angular spectrum transfer function, F and F -1 Represents Fourier transform and inverse Fourier transform, f X and f Y is the spatial frequency, and λ is the wavelength of the X-ray source.

[0031] Compared with the prior art, the technical effects of the present invention are as follows:

[0032] 1) The device of the present invention has a common optical path, single exposure data acquisition, real-time imaging, simple structure, easy operation, and low environmental requirements.

[0033] 2) The imaging device of the present invention is compact and the imaging method is simple to operate, which can avoid multiple operations and improve the robustness of the imaging device. The complex amplitude image of the object under test can be quickly and in real time restored using the recorded single intensity image.

[0034] 3) The present invention adopts amplitude-type optical elements and can be applied to the field of X-ray imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the structure of the X-ray real-time imaging device based on image plane coherent diffraction imaging of the present invention;

[0036] Figure 2 This is a diagram showing the imaging principle of the multifocal photon sieve of the present invention. DETAILED DESCRIPTION

[0037] The present invention will be further described below with reference to the embodiments and drawings, but the scope of protection of the present invention should not be limited thereto.

[0038] Please refer to Figure 1 , Figure 1 The present invention is an X-ray real-time imaging device based on image plane coherent diffraction imaging, comprising an X-ray source 1, an adjustable slit 2, a first three-dimensional translation stage 4 for placing a measured object 3, a multi-focal photon sieve 5, a second three-dimensional translation stage 6, a computer 8, and an X-ray detector 7 fixed on the second three-dimensional translation stage 6;

[0039] The light pulses emitted by the X-ray source 1 are expanded by the adjustable slit 2, and the expanded light beam serves as the incident light beam, which can cover the object to be measured 3;

[0040] The incident light beam is incident on the object 3 to be measured, passes through the object 3 to be measured, and then passes through the multi-focal photon sieve 5 to reach the X-ray detector 7;

[0041] The distance between the measured object 3 and the multifocal photon sieve 5 is u;

[0042] The distance between the multi-focal photon sieve 5 and the X-ray detector 7 is d;

[0043] The multi-focal photon sieve 5 has n (n = 2, 3, 4, ...) focal lengths, which are f1, f2, ... f n ;

[0044] The output end of the X-ray detector 7 is connected to the input end of the computer 8;

[0045] The computer 8 has corresponding data recording, acquisition and processing software for recording intensity maps and data processing.

[0046] The method for performing imaging using the X-ray real-time imaging device based on image plane coherent diffraction imaging is characterized in that the method comprises the following steps:

[0047] 1) Fixing the object to be measured 3 on the first three-dimensional translation stage 4 and fixing the X-ray detector 7 on the second three-dimensional translation stage 6;

[0048] Turning on the X-ray source 1, the light pulses emitted by the X-ray source 1 are incident on the object to be measured 3 after being beam expanded by the adjustable slit 2;

[0049] The multifocal photon sieve 5 has n image planes, and the distances between the n image planes and the multifocal photon sieve 5 are v1, v2, ... v n ;

[0050] Move the first three-dimensional translation stage 4 and the second three-dimensional translation stage 6 so that an intensity map of the object 3 appears on the X-ray detector 7, wherein the intensity map has n non-overlapping diffraction sub-intensity maps, and the diffraction distances of the n diffraction sub-intensity maps are d-v1, d-v2, ..., dv n ;

[0051] The intensity map is recorded by the X-ray detector 7;

[0052] 2) Extract n diffraction intensity regions from the intensity map, denoted as I1(x,y,d-v1), I2(x,y,d-v2), ...I n (x,y,dv n ), where (x, y) is the spatial coordinate distribution of the recording surface (e.g. Figure 2 shown);

[0053] 3) The extracted n diffraction intensity regions are regarded as intensity maps recorded on n diffraction surfaces, and an image plane coherent diffraction imaging algorithm is used to perform iterative calculations to obtain the complex amplitude distribution of the measured object 3, i.e., imaging. The iterative calculation steps are as follows:

[0054] Assume that the complex amplitude distribution of the measured object 3 on the first diffraction surface is Among them, the amplitude distribution of U(x,y,d-v1) is Phase distribution of U(x,y,d-v1) is an arbitrary constant;

[0055] Transmit U(x, y, d-v1) to the first image plane to obtain the complex amplitude distribution U(x1, y1, v1) of the object 3 under test on the first image plane, and perform scaling calculation on U(x1, y1, v1) to obtain the complex amplitude distribution U(x2, y2, v2) of the object 3 under test on the second image plane;

[0056] Transmit U(x2, y2, v2) to the second diffraction surface to obtain the complex amplitude distribution of the measured object 3 on the second diffraction surface Where H2 is the amplitude distribution of U(x,y,d-v2), is the phase distribution of U(x,y,d-v2);

[0057] Use the recorded intensity value I2(x,y,d-v2) to replace and update the amplitude distribution H2 of U(x,y,d-v2) while maintaining the phase distribution of U(x,y,d-v2) Keep it unchanged and update the calculation formula to:

[0058] The updated U'(x, y, d-v2) is continuously transmitted to the second image plane, and scaling calculation, transmission, replacement and update are performed to obtain the complex amplitude distribution U'(x, y, d-v3) of the object 3 under test on the third diffraction plane, until it is transmitted to the last diffraction plane, and the complex amplitude distribution U(x, y, dv n ), and calculate U(x,y,dv n )’s normalized mean square error E:

[0059]

[0060] When E is greater than or equal to 10 -3 Repeat the above iterative process to achieve E less than 10 -3 Effect; when E is less than 10 -3 , end the iteration process and set U x,y,dv n ) is transmitted inversely to the nth image plane, and the complex amplitude distribution U(x n ,y n ,v n ), the formula is as follows:

[0061] U(x n ,y n ,v n )=F -1 {F{U(x,y,dv n )}H0(f X ,f Y )},

[0062] in, is the angular spectrum transfer function, F and F -1 Represents Fourier transform and inverse Fourier transform, f X and f Y is the spatial frequency, and λ is the wavelength of the X-ray source 1.

[0063] Example:

[0064] The central wavelength of the X-ray source 1 is 2.8 nm, and the quad-focal photon sieve 5 (such as Figure 2The focal lengths of the X-ray real-time imaging device based on image plane coherent diffraction imaging are as follows: Figure 1 As shown, it includes an X-ray source 1, an adjustable slit 2, a first three-dimensional translation stage 4 for placing a measured object 3, a quadruple-focal photon sieve 5, a second three-dimensional translation stage 6 and a computer 8, and an X-ray detector 7 fixed on the second three-dimensional translation stage 6;

[0065] The light pulse emitted by the X-ray source 1 passes through the adjustable slit 2 and serves as an incident light beam, and the incident light beam can cover the object to be measured 3;

[0066] The incident light beam is incident on the object 3 to be measured, passes through the object 3 to be measured, and then passes through the quad-focal photon sieve 5 to reach the X-ray detector 7;

[0067] The distance between the object to be measured 3 and the quad-focal photon sieve 5 is u;

[0068] The distance between the quad-focal photon sieve 5 and the X-ray detector 7 is d;

[0069] The quad-focal photon sieve 5 has four focal lengths, which are f1, f2, f3 and f4 respectively;

[0070] The output end of the X-ray detector 7 is connected to the input end of the computer 8;

[0071] The computer 8 has corresponding data recording, acquisition and processing software for recording intensity maps and data processing.

[0072] The method for performing imaging using the X-ray real-time imaging device based on image plane coherent diffraction imaging is characterized in that the method comprises the following steps:

[0073] 1) Fixing the object to be measured 3 on the first three-dimensional translation stage 4 and fixing the X-ray detector 7 on the second three-dimensional translation stage 6;

[0074] Turning on the X-ray source 1, the light pulses emitted by the X-ray source 1 are incident on the object to be measured 3 after being beam expanded by the adjustable slit 2;

[0075] The multifocal photon sieve 5 has four image planes, and the distances between the four image planes and the quadfocal photon sieve 5 are v1, v2, v3 and v4 respectively;

[0076] Moving the first three-dimensional translation stage 4 and the second three-dimensional translation stage 6 so that an intensity map of the object 3 appears on the X-ray detector 7, wherein the intensity map has n non-overlapping diffraction sub-intensity maps, and the diffraction distances of the four diffraction sub-intensity maps are d-v1, d-v2, d-v3, and d-v4, respectively;

[0077] The intensity map is recorded by the X-ray detector 7;

[0078] 2) Extract four diffraction intensity regions from the intensity map, denoted as I1(x,y,d-v1), I2(x,y,d-v2), I3(x,y,d-v3) and I4(x,y,d-v4), where (x,y) is the spatial coordinate distribution of the recording surface (e.g. Figure 2 shown);

[0079] 3) The four extracted diffraction intensity regions are regarded as intensity maps recorded on the four diffraction planes, and an image plane coherent diffraction imaging algorithm is used to perform iterative calculations to obtain the complex amplitude distribution of the object 3 under test, i.e., imaging. The iterative calculation steps are as follows:

[0080] Assume that the complex amplitude distribution of the measured object 3 on the first diffraction surface is Among them, the amplitude distribution of U x,y,d-v1) is Phase distribution of U x,y,d-v1) is an arbitrary constant;

[0081] Transmit U x, y, d-v1) to the first image plane to obtain the complex amplitude distribution U(x1, y1, v1) of the object 3 under test on the first image plane, and perform scaling calculation on U(x1, y1, v1) to obtain the complex amplitude distribution U(x2, y2, v2) of the object 3 under test on the second image plane;

[0082] Transmit U(x2, y2, v2) to the second diffraction surface to obtain the complex amplitude distribution of the measured object 3 on the second diffraction surface Where H2 is the amplitude distribution of U(x,y,d-v2), is the phase distribution of U(x,y,d-v2);

[0083] Use the recorded intensity value I2(x,y,d-v2) to replace and update the amplitude distribution H2 of U(x,y,d-v2) while maintaining the phase distribution of U(x,y,d-v2) Keep it unchanged and update the calculation formula to:

[0084] The updated U'(x,y,d-v2) is continuously transmitted to the second image plane, and scaling calculation and transmission are performed to obtain the complex amplitude distribution U'(x,y,d-v3) of the object 3 under test on the third diffraction plane. This is continued until it is transmitted to the last diffraction plane, and the complex amplitude distribution U(x,y,d-v4) of the object 3 under test on the fourth diffraction plane is obtained. The normalized mean square error E of U(x,y,d-v4) is calculated:

[0085]

[0086] When E is greater than or equal to 10 -3 Repeat the above iterative process to achieve E less than 10 -3 Effect; when E is less than 10 -3 , end the iterative process, and transmit U(x,y,d-v4) inversely to the fourth image plane, thus obtaining the complex amplitude distribution U(x4,y4,v 34 ), the formula is as follows:

[0087] U(x4,y4,v4)=F -1 {F{U(x,y,d-v4)}H0(f X ,f Y )},

[0088] in, is the angular spectrum transfer function, F and F -1 Represents Fourier transform and inverse Fourier transform, f X and f Y is the spatial frequency, and λ is the wavelength of the X-ray source 1.

[0089] Experiments show that the present invention has a simple structure, simple operation, small size, and low environmental requirements. It can quickly and in real time obtain complex amplitude images of the object being measured, avoid multiple mechanical operations, improve the robustness of the imaging device, and realize real-time imaging from X-rays to terahertz bands.

[0090] The specific embodiments described above further illustrate the objectives, technical solutions, and beneficial effects of the present invention. It should be understood that the above description is merely a specific implementation example of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. An X-ray real-time imaging device based on image plane coherent diffraction imaging, characterized in that: The invention comprises an X-ray source (1), an adjustable slit (2), a first three-dimensional translation stage (4) for placing a measured object (3), a multi-focus photon sieve (5), a second three-dimensional translation stage (6), a computer (8), and an X-ray detector (7) fixed on the second three-dimensional translation stage (6); The light pulses emitted by the X-ray source (1) are expanded through the adjustable slit (2), and the expanded light beam serves as an incident light beam, which can cover the object to be measured (3); The incident light beam is incident on the object to be measured (3), is transmitted through the object to be measured (3), and then passes through the multi-focal photon sieve (5) to reach the X-ray detector (7); The distance between the measured object (3) and the multifocal photon sieve (5) is u; The distance between the multi-focal photon sieve (5) and the X-ray detector (7) is d; The multi-focal photon sieve (5) has n focal lengths, n≥2, and the focal lengths are f1, f2, ..., fn, respectively, and can obtain n non-overlapping diffractometer intensity maps in the X-ray detector; The output end of the X-ray detector (7) is connected to the input end of the computer (8); The computer (8) has corresponding data recording, acquisition and processing software for recording intensity maps and data processing.

2. A method for performing imaging using the X-ray real-time imaging device based on image plane coherent diffraction imaging according to claim 1, characterized in that: The method comprises the following steps: 1) fixing the object to be measured (3) on the first three-dimensional translation stage (4), and fixing the X-ray detector (7) on the second three-dimensional translation stage (6); The X-ray source (1) is turned on, and the light pulses emitted by the X-ray source (1) are incident on the object to be measured (3) after being expanded by the adjustable slit (2); The multifocal photon sieve (5) has n image planes, and the distances between the n image planes and the multifocal photon sieve (5) are v1, v2, ... v n ; The first three-dimensional translation stage (4) and the second three-dimensional translation stage (6) are moved so that an intensity map of the object to be measured (3) appears on the X-ray detector (7), wherein the intensity map has n non-overlapping diffraction sub-intensity maps, and the diffraction distances of the n diffraction sub-intensity maps are d-v1, d-v2, ..., dv n ; The intensity map is recorded by the X-ray detector (7); 2) Extract n diffraction intensity regions from the intensity map, denoted as I1(x,y,d-v1), I2(x,y,d-v2), ...I n (x,y,dv n ), where (x, y) is the spatial coordinate distribution of the recording surface; 3) The extracted n diffraction intensity regions are respectively regarded as diffraction intensity maps recorded on n diffraction surfaces, and an image plane coherent diffraction imaging algorithm is used to perform iterative calculations to obtain the complex amplitude distribution of the measured object (3), i.e., imaging. The iterative calculation steps are as follows: Assume that the complex amplitude distribution of the measured object (3) on the first diffraction surface is Among them, the amplitude distribution of U(x,y,d-v1) is Phase distribution of U(x,y,d-v1) is an arbitrary constant; Transmitting U(x, y, d-v1) to the first image plane to obtain the complex amplitude distribution U(x1, y1, v1) of the object under test (3) on the first image plane, and performing scaling calculation on U(x1, y1, v1) to obtain the complex amplitude distribution U(x2, y2, v2) of the object under test (3) on the second image plane; Transmit U(x2, y2, v2) to the second diffraction surface to obtain the complex amplitude distribution of the measured object (3) on the second diffraction surface Where H2 is the amplitude distribution of U(x,y,d-v2), is the phase distribution of U(x,y,d-v2); Use the recorded intensity value I2(x,y,d-v2) to replace and update the amplitude distribution H2 of U(x,y,d-v2) while maintaining the phase distribution of U(x,y,d-v2) Keep it unchanged and update the calculation formula to: The updated U'(x,y,d-v2) is continuously transmitted to the second image plane, and scaling calculation, transmission, replacement and update are performed to obtain the complex amplitude distribution U'(x,y,d-v3) of the object under test (3) on the third diffraction plane, until it is transmitted to the last diffraction plane, and the complex amplitude distribution U(x,y,dv n ), and calculate U(x,y,dv n )’s normalized mean square error E: When E is greater than or equal to 10 -3 Repeat the above iterative process to achieve E less than 10 -3 Effect; when E is less than 10 -3 , end the iteration process and set U(x,y,dv n ) is transmitted inversely to the nth image plane, and the complex amplitude distribution U(x n ,y n ,v n ), the formula is as follows: U(x n ,y n ,v n )=F -1 {F{U(x,y,d-v n )}H0(f X ,f Y )}, in, is the angular spectrum transfer function, F and F -1 represent Fourier and inverse Fourier transforms, respectively, f X and f Y is the spatial frequency, and λ is the wavelength of the X-ray source (1).

Images