Large-angle inclined reflective laminated diffraction imaging method and related device

Abstract

The invention discloses a large-angle inclined reflective laminated diffraction imaging method and a related device, and relates to the field of laminated diffraction imaging, and the method comprises the steps: obtaining diffraction images of a sample at different scanning positions in a target region at a preset inclination angle greater than 20 degrees; and according to the diffraction image, performing diffraction light field reconstruction by applying an sPIE iterative algorithm to obtain the amplitude and phase of sample reconstruction. According to the invention, the rotation angle of the sample is amplified, the recovery correction of the sample at a large inclination angle is realized, and compared with the existing inclined reflective laminated imaging with the rotation angle of the sample being about 20 degrees, the invention provides the reflective laminated diffraction imaging with the large inclination angle, so that more detailed information of the sample can be recovered; and clearer detail information of the sample can be recovered, and the phase recovery precision of the sample is improved.

Description

Technical Field

[0001] The present application relates to the field of reflective stacked diffraction imaging, and in particular to a large-angle inclined reflective stacked diffraction imaging method and related devices. Background Art

[0002] As a lensless phase retrieval technology, stacked diffraction imaging significantly improves the convergence speed and noise resistance of traditional phase iterative retrieval algorithms. It has the advantages of large field of view, high contrast, high resolution, no need for marking, long working distance, and no loss of phase low-frequency components. The characteristic of this technology is that there is an overlapping part between two adjacent scanning positions, which makes full use of the convolution theorem. Through iteration, it can reconstruct all the scattered wavefronts of the sample without the need for reference light. In the existing inclined reflective stacked imaging, the rotation angle of the sample is for a small angle. As the angle increases, the path of visible light penetrating the sample becomes longer, and each diffraction image also presents different contrasts and details, so that the hierarchical structure inside the sample can be inferred. Therefore, there is an urgent need for a reflective stacked diffraction imaging technology with a larger tilt angle to restore more detailed information about the sample. Summary of the invention

[0003] The purpose of this application is to provide a large-angle tilted reflective stacked diffraction imaging method and related devices, and proposes a large-angle tilted reflective stacked diffraction imaging method that can restore more detailed information of the sample and improve the phase recovery accuracy of the sample.

[0004] To achieve the above objectives, this application provides the following solutions:

[0005] In a first aspect, the present application provides a large-angle tilted reflective stacked diffraction imaging method, comprising:

[0006] Obtaining diffraction images of the sample at different scanning positions within the target area at a preset tilt angle; the preset tilt angle is greater than 20°;

[0007] According to the diffraction image, the spie iterative algorithm is applied to reconstruct the diffraction light field to obtain the amplitude and phase of the sample reconstruction; the spie iterative algorithm introduces the diffraction distance correction process and the affine transformation process of the reconstructed light field on the basis of the ePIE iterative algorithm.

[0008] In a second aspect, the present application provides a reflective stacked diffraction imaging device with a large tilt angle, comprising: a computer and a laser, a first reflector, a second reflector, a spatial filter, a collimating lens, a probe, a sample and a detector arranged in sequence according to the propagation direction of light;

[0009] The detector is used to collect diffraction images at different scanning positions within the sample target area;

[0010] The computer is used to execute the above-mentioned large-angle tilted reflective stacked diffraction imaging method.

[0011] In a third aspect, the present application provides a computer device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the above-mentioned large-angle tilted reflective stacked diffraction imaging method.

[0012] In a fourth aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-mentioned large-angle tilted reflective stacked diffraction imaging method.

[0013] In a fifth aspect, the present application provides a computer program product, including a computer program, which, when executed by a processor, implements the above-mentioned large-angle tilted reflective stacked diffraction imaging method.

[0014] According to the specific embodiments provided in this application, this application discloses the following technical effects:

[0015] The present application provides a large-angle tilted reflective stacked diffraction imaging method and related devices, which obtain diffraction images of samples at different scanning positions in a target area at a preset tilt angle greater than 20°; according to the diffraction image, the SPI iterative algorithm is applied to reconstruct the diffraction light field to obtain the amplitude and phase of the sample reconstruction. The present invention amplifies the rotation angle of the sample and realizes the restoration and correction of the sample at a large tilt angle. Compared with the existing tilted reflective stacked imaging of samples with a rotation angle of about 20°, the present invention proposes a large-angle tilted reflective stacked diffraction imaging, which can restore more detailed information of the sample, and can also restore clearer detailed information of the sample, thereby improving the phase recovery accuracy of the sample. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 This is a diagram of the application environment of a large-angle tilted reflective stacked diffraction imaging method in one embodiment of the present application;

[0018] Figure 2 A schematic diagram of a process flow of a large-angle tilted reflective stacked diffraction imaging method provided in one embodiment of the present application;

[0019] Figure 3 A schematic diagram of the principle of reflective stacked diffraction imaging provided by an embodiment of the present application;

[0020] Figure 4 A schematic diagram of a manual reflective stacked diffraction imaging experimental device provided in one embodiment of the present application;

[0021] Figure 5 A schematic diagram of diffraction distance correction provided in one embodiment of the present application;

[0022] Figure 6 A schematic diagram of amplitude and phase recovery and reconstruction results provided in an embodiment of the present application;

[0023] Figure 7 A schematic diagram of the structure of a computer device provided in one embodiment of the present application. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0025] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below with reference to the accompanying drawings and specific implementation methods.

[0026] The large-angle tilted reflective stacked diffraction imaging method provided in the embodiment of the present application can be applied to Figure 1 In the application environment shown. Among them, the terminal communicates with the server through the network. The data storage system can store the data that the server needs to process. The data storage system can be set up separately, integrated on the server, or placed on the cloud or other servers. The terminal can send the diffraction images of the sample at different scanning positions in the target area at a preset tilt angle to the server, and the server applies the sPIE (Simple Diffraction Distance Correction) iterative algorithm to reconstruct the diffraction light field based on the diffraction image to obtain the amplitude and phase of the sample reconstruction. The server can feed back the obtained amplitude and phase of the sample reconstruction to the terminal. In addition, in some embodiments, the reflective stacked diffraction imaging method with a large angle tilt can also be implemented by a server or a terminal alone, such as the terminal can directly reconstruct the diffraction light field for the diffraction images of different scanning positions in the target area of ​​the sample at a preset tilt angle, or the server can obtain the diffraction images of the sample at different scanning positions in the target area at a preset tilt angle from the data storage system and reconstruct the diffraction light field.

[0027] The terminals may be, but are not limited to, various desktop computers, laptops, smart phones, tablet computers, IoT devices and portable wearable devices. IoT devices may be smart speakers, smart TVs, smart air conditioners, smart car-mounted devices, etc. Portable wearable devices may be smart watches, smart bracelets, head-mounted devices, etc. The server may be implemented as an independent server or a server cluster consisting of multiple servers, or a cloud server.

[0028] In an exemplary embodiment, Figure 2 As shown, a large-angle tilted reflective stacked diffraction imaging method is provided. The method is executed by a computer device, and can be executed by a computer device such as a terminal or a server alone, or by a terminal and a server together. In the embodiment of the present application, the method is applied to Figure 1 The server in the example is used to illustrate, including the following steps 101 to 102. Among them:

[0029] Step 101, obtaining diffraction images of the sample at different scanning positions in a target area at a preset tilt angle; the preset tilt angle is greater than 20°.

[0030] like Figure 3 and Figure 4 As shown in the figure, a stacked diffraction imaging experimental device is built, the probe size is selected, and the step length is determined according to the probe size and the required overlap rate; the laser wavelength, the diffraction distance from the input image to the CCD camera used to collect the diffraction pattern, the camera pixel size, the number of collected diffraction images (excluding the probe), the scanning step length, and the rotation angle are determined. The data collected using the stacked diffraction imaging experimental device includes a series of diffraction images and a position data file loc.mat. The naming order of the collected diffraction images is the same as the actual scanning order.

[0031] Step 102: According to the diffraction image, the spie iterative algorithm is applied to reconstruct the diffraction light field to obtain the amplitude and phase of the sample reconstruction. The spie iterative algorithm is an improved ePIE iterative algorithm, which introduces the diffraction distance correction process and the affine transformation process of the reconstructed light field on the basis of the ePIE iterative algorithm.

[0032] The above steps 101 to 102 are implemented. With the need of reflective stacked diffraction imaging technology, based on the visible light reflective stacked diffraction imaging technology for tilted samples, imaging is performed at multiple tilt angles. For example, the tilt angle of the sample can be changed from 30°, 45° to 60°, so as to realize imaging of reflective samples tilted at large angles. By combining the diffraction images obtained at the same tilt angle for phase recovery, different tilt angles can provide different viewing angles to observe and reconstruct complex biological or material samples. As the tilt angle increases, the path of visible light penetrating the sample becomes longer, and each diffraction image also presents different contrasts and details, thereby inferring the internal hierarchical structure of the sample, thereby improving the phase recovery accuracy of the sample.

[0033] In another exemplary embodiment of the present application, the preset tilt angle can be any angle within the range of [30°, 60°]; for example, it can be 30°, 45° or 60°, or 35°, 40°, 50° or 55°, etc. Among them, the range of [30°, 60°] is only a relatively concentrated range. For the present invention, tilt angles less than 30° and greater than 60° are also applicable. The present invention proposes large-angle (tilt angle) reflective stack imaging, which makes up for the gap of reflective stack at large angles. Compared with the original small-angle imaging, large angles face greater challenges. The imaging technology of the present invention solves the various problems caused by directly applying large angles on the basis of existing small-angle imaging methods (as the sample angle increases, the change in diffraction distance, angle error and imaging deformation will also increase accordingly), and the present invention obtains an effect similar to that of small-angle reflective stack imaging, achieving a major leap in reflective stack diffraction imaging, and can provide help for related applications such as chip detection in the future. In addition, it should be noted that the imaging method of the present invention focuses on achieving large tilt angle reflective stacked diffraction imaging, and is also applicable to small tilt angles.

[0034] In another exemplary embodiment of the present application, stack reconstruction is an imaging method based on phase recovery technology, which is used to reconstruct the phase information and amplitude information of the sample from a series of diffraction images. During the stack reconstruction process, the sample is scanned step by step by the probe, and a diffraction image is generated at each scanning position. By analyzing these diffraction images, the phase and amplitude information of the sample can be gradually restored. The reconstruction algorithm of stack imaging relies on an iterative algorithm. The iterative recovery algorithm of stack imaging obtains the complex amplitude information of the object surface by restoring the intensity of multiple "layers" of diffraction images. Unlike most phase recovery algorithms, when reconstructing the complex amplitude of each layer, the guessed sample complex amplitude distribution is constrained by the diffraction distribution of other "layers", so it can quickly obtain an accurate solution. Therefore, the iterative recovery algorithm has the advantages of fast convergence speed and elimination of ambiguity of the solution. In the present invention, on the basis of the original coherent diffraction imaging and stack diffraction imaging, by tilting the sample, and using diffraction distance correction and geometric affine stretching on the basis of the GS algorithm and the ePIE iterative algorithm, the transmission and reflection samples tilted at a large angle are restored. The general process of large-angle tilted stacked diffraction imaging is as follows: First, build a stacked imaging diffraction system and place reflective samples of different angles and materials as needed. Secondly, start collecting diffraction images of the required area and guess the initial complex amplitude of the probe. Finally, the ePIE iterative algorithm with position correction is used for reconstruction, and the correction and affine transformation of the diffraction distance are completed during the reconstruction process. In addition, the accurate step size, diffraction distance and rotation angle must be known in order to restore the sample in the collection area well. Therefore, step 102, according to the diffraction image, the spIE iterative algorithm is applied to reconstruct the diffraction light field to obtain the amplitude and phase of the sample reconstruction, which specifically includes:

[0035] (1) Randomly determine the initial complex amplitude distribution diagram of the sample, and determine the initial complex amplitude distribution diagram of the probe based on the collected probe.

[0036] In the present invention, the complex amplitude distribution of the sample is randomly guessed, and the collected probe is restored to the object plane through the GS algorithm as the complex amplitude distribution of the initial guess probe.

[0037] (2) A target scanning position is randomly selected, and the complex amplitude distributions in the current sample complex amplitude distribution map and the current probe complex amplitude distribution map at the current target scanning position are determined respectively, so as to obtain the sample target scanning position complex amplitude distribution map and the probe target scanning position complex amplitude distribution map; initially, the current sample complex amplitude distribution map and the current probe complex amplitude distribution map refer to the sample initial complex amplitude distribution map and the probe initial complex amplitude distribution map.

[0038] (3) Calculating the exit field after the probe interacts with the sample based on the complex amplitude distribution diagram of the current sample target scanning position and the complex amplitude distribution diagram of the current probe target scanning position.

[0039] The calculated exit field is:

[0040] ψ n,j (r) = O n,j (r)P n,j (r).

[0041] Among them, ψ n,j (r) represents the output field corresponding to the scanning position j at the nth iteration; n,j (r) represents the complex amplitude distribution diagram at the sample scanning position j during the nth iteration; P n,j (r) represents the complex amplitude distribution diagram at the probe scanning position j in the nth iteration; r represents the guessed area of ​​the object, that is, the value range of a diffraction pattern on the x-axis and y-axis.

[0042] (4) Calculate the diffraction light field of the current output field on the observation plane according to the Fresnel diffraction transmission model. The diffraction distance used when applying the Fresnel diffraction transmission model for Fresnel diffraction is the distance corrected by the preset tilt angle.

[0043] The outgoing field propagates through a certain distance of Fresnel diffraction, and the corresponding complex amplitude distribution is:

[0044]

[0045] In the formula, Ψ n,j (u) represents the diffraction light field corresponding to the scanning position j at the nth iteration; Fresnel{·} represents the Fresnel diffraction propagation model, and i is an imaginary unit. n,j (u) is the amplitude, For phase.

[0046] Since the rotation of the sample will cause different diffraction distances due to different distances from the object plane to the image plane, which will cause defocus on the image restoration, it is necessary to recalculate the diffraction distance according to the different rotation angles of the sample and the different step sizes during the scanning process during the ePIE iterative algorithm to reduce the defocus caused by the diffraction distance error and improve the image restoration quality. The specific principle of diffraction distance calculation is as follows Figure 5 As shown in the figure, a total of 49 diffraction patterns consisting of 7 rows and 7 columns are taken as an example, θ is the rotation angle of the sample, y is the scanning step length, and x is the diffraction distance error caused by the rotation between each scanned image, such as: z1 = z-ytanθ, z2 = z+ytanθ, and other diffraction distances can be obtained in the same way. Finally, Fresnel diffraction propagation is performed based on the diffraction distance to obtain the diffraction light field.

[0047] (5) Using the measured diffraction light intensity to replace the amplitude of the current diffraction light field to obtain a new diffraction light field; the measured diffraction light intensity is determined based on the diffraction image at the corresponding scanning position.

[0048] Using the known intensity information I on the diffraction image j (u) Replace the amplitude of the diffracted light field and obtain a new diffracted light field distribution:

[0049]

[0050] Among them, ψ' n,j (u) represents the new diffracted light field; I j (u) represents the diffraction light intensity on the diffraction image corresponding to the scanning position j at the nth iteration.

[0051] (6) According to the Fresnel diffraction transmission model, the new diffraction light field is propagated back to the sample surface to obtain a new output field.

[0052] Performing inverse Fresnel transform on the new diffracted light field obtained in the previous step gives a new object exit field:

[0053] ψ′ n,j (r) = iFresnel{Ψ′ n,j (u)}.

[0054] In the formula, ψ' n,j (r) represents the new outgoing field; iFresnel{·} represents Fresnel inverse diffraction propagation.

[0055] (7) According to the exit field at the current target scanning position and the new exit field, the current sample complex amplitude distribution map and the current probe complex amplitude distribution map are updated respectively to obtain an updated sample complex amplitude distribution map and an updated probe complex amplitude distribution map.

[0056] The purpose of updating the complex amplitude function of the sample and probe is to gradually approximate the complex amplitude distribution of the real sample and probe. Once the predetermined number of iterations is reached or the convergence criterion is met, the updated complex amplitude function can be used to generate the final recovered amplitude and phase. The following is the update formula:

[0057]

[0058] In the formula, O n+1 (r) represents the updated sample complex amplitude distribution diagram; n (r) represents the complex amplitude distribution diagram of the sample before updating corresponding to the scanning position j; represents the conjugate of the probe complex amplitude at the jth scanning position, P represents the square of the maximum modulus of the probe complex amplitude at the jth scanning position.n+1 (r) represents the updated probe complex amplitude distribution diagram; P n (r) represents the probe complex amplitude distribution diagram before updating corresponding to the scanning position j; represents the conjugate of the sample complex amplitude at the jth scanning position, It represents the square of the maximum modulus of the sample complex amplitude at the jth scanning position. α and β are both feedback coefficients, which are used to change the update step size. Their values ​​will affect the convergence speed and stability of the algorithm.

[0059] (8) The updated sample complex amplitude distribution map is used as the current sample complex amplitude distribution map, the updated probe complex amplitude distribution map is used as the current probe complex amplitude distribution map, and a scanning position is selected from the unselected scanning positions as the current target scanning position, and the step of "respectively determining the complex amplitude distributions in the current sample complex amplitude distribution map and the current probe complex amplitude distribution map at the current target scanning position to obtain the sample target scanning position complex amplitude distribution map and the probe target scanning position complex amplitude distribution map" is returned to the step of "respectively determining the complex amplitude distributions in the current sample complex amplitude distribution map and the current probe complex amplitude distribution map at the current target scanning position to obtain the sample target scanning position complex amplitude distribution map and the probe target scanning position complex amplitude distribution map", and processing all diffraction images once is regarded as one spie iteration process, so until all scanning positions are traversed, the reconstructed sample complex amplitude distribution map and the reconstructed probe complex amplitude distribution map are obtained.

[0060] (9) Determine whether the SPIE iteration termination condition is met; the SPIE iteration termination condition is that the mean square error (MSE) between the current reconstructed sample complex amplitude distribution map and the detected sample diffraction image is less than a preset error value or the current SPIE iteration number reaches a preset SPIE iteration number.

[0061] (10) If not, then use the currently reconstructed sample complex amplitude distribution map as the current sample complex amplitude distribution map, and use the currently reconstructed probe complex amplitude distribution map as the current probe complex amplitude distribution map, and return to the step of "randomly selecting a target scanning position, and determining the complex amplitude distributions in the current sample complex amplitude distribution map and the current probe complex amplitude distribution map at the current target scanning position respectively."

[0062] (11) If yes, then an affine transformation is performed on the complex amplitude distribution map of the currently reconstructed sample according to a preset tilt angle to obtain a final complex amplitude distribution map of the reconstructed sample.

[0063] (12) The amplitude and phase of the sample reconstruction are obtained based on the complex amplitude distribution diagram of the final reconstructed sample.

[0064] Figure 6It is a schematic diagram of the amplitude and phase recovery reconstruction results, where (a)-(c) are the amplitude diagrams of the reconstructed samples at tilt angles of 30°, 45°, and 60°, respectively. The sample used is the USAF1951 resolution plate, where the horizontal numbers 2 and 3 represent the second and third groups, and the vertical numbers 2, 3, 4, 5, 6 represent the second, third, fourth, fifth, and sixth line pairs. Using the method of the present invention, the sixth pair of the fifth group can be seen, that is, the resolution is 8.77um. (d)-(f) are the phase distributions of the reconstructed samples at tilt angles of 30°, 45°, and 60°, respectively. (g)-(i) are the convergence of the mean square error after 50 iterations at different tilt angles. From Figure 6 It can be seen that by using the method of the present invention, a resolution of 8.77 um can be achieved, the phase recovery effect is good, very close to the truth, and the convergence speed is very fast, which can be converged in about 10 times.

[0065] Given a known rotation angle, such as θ (unit: degree), calculate the stretch factor S in the x direction x , the stretch factor is due to the image rotation, which will stretch or compress in the x direction. x It is to correct the stretching or compression effect in the x direction. The stretch factor is calculated as follows:

[0066] Since the aspect ratio of the image needs to be maintained, the stretch factor S in the y direction is y is set to 1, which means no stretching or compression in the y direction. In order to rotate and stretch the image, you need to create an affine transformation matrix as follows:

[0067]

[0068] In the formula, S x is the stretch factor in the x direction, S y is the stretching factor in the y direction. According to this formula, the complex amplitude distribution map of the reconstructed sample is affine transformed.

[0069] In this embodiment, the advantages of the present invention are explained from three aspects: phase recovery accuracy, resolution and calculation efficiency:

[0070] 1. For phase recovery accuracy, the present invention uses mean square error for calculation, comparing the difference between the reconstructed and recovered phase and the true phase. The MSE value simulated by computer can reach about 0.0003, and the reconstruction effect of the present invention is relatively good.

[0071] 2. Regarding resolution, the present invention uses the spie iterative algorithm, and its resolution can reach 10 microns. The higher the resolution, the richer the imaging details. Therefore, the reconstruction effect obtained by the present invention using the spie iterative algorithm is also better.

[0072] 3. Computational efficiency: After computer simulation, the time required for the SPI iterative algorithm of the present invention to perform phase recovery is: 50 iterations require about 100 seconds, and the computational efficiency is also relatively high.

[0073] The present application also provides an application scenario, which applies the above-mentioned large-angle tilted reflective stacked diffraction imaging method. Specifically: The application scope of the large-angle tilted reflective stacked diffraction imaging method provided by this embodiment is not only limited to the field of scientific research, but also extends to practical applications such as industry, medicine and biology. In the industrial field, this technology can be used to detect tiny defects, surface morphology and material properties, and improve product quality and manufacturing efficiency. In medicine, stacked diffraction imaging technology can be used in medical imaging, such as histology, pathology and neuroscience research, to help doctors accurately diagnose diseases and develop personalized treatment plans. In the field of biology, this technology helps to study the microstructure and function of biological samples, explore the mysteries of life and promote the development of biomedical science.

[0074] In an exemplary embodiment, Figure 3 and Figure 4 As shown, a reflective stacked diffraction imaging device with a large tilt angle is provided, comprising: a computer and a laser, a first reflector, a second reflector, a spatial filter, a collimating lens, a probe, a sample and a detector arranged in sequence according to the propagation direction of light;

[0075] The detector is used to collect diffraction images at different scanning positions in the sample target area.

[0076] The computer is used to execute the large-angle tilted reflective stacked diffraction imaging method described in Example 1.

[0077] like Figure 4 As shown, an optical stack diffraction imaging experimental device that can realize single-wavelength at one time was built, specifically a reflective stack diffraction imaging experimental device. The sample was scanned and the scanned sample was phase-recovered by adjusting the sample position. The experimental device used a helium-neon laser (DH-HN250) with a wavelength of 632.8nm; the plane wave stack diffraction imaging optical path was realized by a slide, and the incident light beam was expanded by spatial filtering through a microscope objective and a pinhole; then a framed converging lens with a suitable focal length was selected, and a collimated light beam was obtained after adjusting the position; in the plane wave optical path in the vertical direction after adjustment, a reflector, a sample stage and a CCD (pixel size: 5.86um, resolution: 1920×1200) were added in sequence; among them, two reflectors were required to make the light beam emitted by the laser in a straight line, and the Daheng GCM-901603M stage was selected as the sample stage. Figure 4The specific experimental parameters shown are as follows: Laser: the laser uses a helium-neon laser with a wavelength of 632.8 nm; M1, M2: reflectors; SF: spatial filter; CL: collimating lens; Pinhole: probe; xyz Stage: three-dimensional translation stage; Sample: sample; CCD: a CCD camera with a pixel size of 5.86 um and a resolution of 1920×1200.

[0078] In an exemplary embodiment, a computer device is provided. The computer device may be a server or a terminal. The internal structure diagram thereof may be as follows: Figure 7 As shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, referred to as I / O) and a communication interface. The processor, the memory and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store amplitude and phase data reconstructed by the sample. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a large-angle tilted reflective stack diffraction imaging method is implemented.

[0079] Those skilled in the art will understand that Figure 7 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components. In an exemplary embodiment, a computer device is provided, including a memory and a processor, wherein a computer program is stored in the memory, and the processor implements the steps in the above-mentioned method embodiments when executing the computer program.

[0080] In an exemplary embodiment, a computer-readable storage medium is provided, storing a computer program, and when the computer program is executed by a processor, the steps in the above method embodiments are implemented.

[0081] In an exemplary embodiment, a computer program product is provided, including a computer program, and when the computer program is executed by a processor, the steps in the above method embodiments are implemented.

[0082] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant regulations.

[0083] Those of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM may be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0084] The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. The non-relational database may include a distributed database based on blockchain, etc., but is not limited thereto. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, etc., but is not limited thereto.

[0085] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0086] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A large-angle tilted reflective stack diffraction imaging method, It is characterized in that include: Obtaining diffraction images of the sample at different scanning positions within the target area at a preset tilt angle; The preset inclination angle is greater than 20°; According to the diffraction image, the spie iterative algorithm is applied to reconstruct the diffraction light field to obtain the amplitude and phase of the sample reconstruction; the spie iterative algorithm introduces the diffraction distance correction process and the affine transformation process of the reconstructed light field on the basis of the ePIE iterative algorithm.

2. The large-angle tilted reflective stacked diffraction imaging method according to claim 1, It is characterized in that According to the diffraction image, the SPI iterative algorithm is applied to reconstruct the diffraction light field to obtain the amplitude and phase of the sample reconstruction, specifically including: Randomly determine the sample initial complex amplitude distribution diagram, and determine the probe initial complex amplitude distribution diagram based on the collected probe; A target scanning position is randomly selected, and the complex amplitude distributions at the current target scanning position in the current sample complex amplitude distribution map and the current probe complex amplitude distribution map are determined respectively, to obtain the sample target scanning position complex amplitude distribution map and the probe target scanning position complex amplitude distribution map; initially, the current sample complex amplitude distribution map and the current probe complex amplitude distribution map refer to the sample initial complex amplitude distribution map and the probe initial complex amplitude distribution map; Calculate the exit field after the probe interacts with the sample according to the complex amplitude distribution diagram of the current sample target scanning position and the complex amplitude distribution diagram of the current probe target scanning position; The diffraction light field of the current output field on the observation plane is calculated according to the Fresnel diffraction transmission model; the diffraction distance used when the Fresnel diffraction transmission model is applied to perform Fresnel diffraction is the distance corrected by the preset tilt angle; Using the measured diffraction light intensity to replace the amplitude of the current diffraction light field to obtain a new diffraction light field; the measured diffraction light intensity is determined according to the diffraction image at the corresponding scanning position; According to the Fresnel diffraction transmission model, the new diffracted light field is back-propagated to the sample surface to obtain a new output field; According to the exit field at the current target scanning position and the new exit field, the current sample complex amplitude distribution map and the current probe complex amplitude distribution map are updated respectively to obtain an updated sample complex amplitude distribution map and an updated probe complex amplitude distribution map; Using the updated sample complex amplitude distribution map as the current sample complex amplitude distribution map, using the updated probe complex amplitude distribution map as the current probe complex amplitude distribution map, and selecting a scanning position from the unselected scanning positions as the current target scanning position, returning to step "respectively determining the complex amplitude distributions at the current target scanning position in the current sample complex amplitude distribution map and the current probe complex amplitude distribution map, and obtaining the sample target scanning position complex amplitude distribution map and the probe target scanning position complex amplitude distribution map", until all scanning positions are traversed, and the reconstructed sample complex amplitude distribution map and the reconstructed probe complex amplitude distribution map are obtained; Determine whether the SPIE iteration termination condition is met; the SPIE iteration termination condition is that the mean square error (MSE) between the current reconstructed sample complex amplitude distribution map and the detected sample diffraction image is less than a preset error value or the current SPIE iteration number reaches a preset SPIE iteration number; If not, then use the currently reconstructed sample complex amplitude distribution map as the current sample complex amplitude distribution map, use the currently reconstructed probe complex amplitude distribution map as the current probe complex amplitude distribution map, and return to step "randomly select a target scanning position, and determine the complex amplitude distributions at the current target scanning position in the current sample complex amplitude distribution map and the current probe complex amplitude distribution map respectively"; If yes, then perform an affine transformation on the current reconstructed sample complex amplitude distribution map according to a preset tilt angle to obtain a final reconstructed sample complex amplitude distribution map; The amplitude and phase of sample reconstruction are obtained based on the final reconstructed sample complex amplitude distribution diagram.

3. A reflective stacked diffraction imaging device with a large tilt angle, It is characterized in that include: A computer and a laser, a first reflector, a second reflector, a spatial filter, a collimating lens, a probe, a sample and a detector arranged in sequence according to the propagation direction of light; The detector is used to collect diffraction images of the sample at different scanning positions in the target area at a preset tilt angle; the preset tilt angle is greater than 20°; The computer is used to execute the large-angle tilted reflective stacked diffraction imaging method described in any one of claims 1 to 4.

4. A computer device, include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the large-angle tilted reflective stacked diffraction imaging method described in any one of claims 1-2.

5. A computer-readable storage medium having a computer program stored thereon, It is characterized in that When the computer program is executed by a processor, the large-angle tilted reflective stacked diffraction imaging method described in any one of claims 1-2 is implemented.

6. A computer program product comprising a computer program, It is characterized in that When the computer program is executed by a processor, the large-angle tilted reflective stacked diffraction imaging method described in any one of claims 1-2 is implemented.

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