Ultrafast diffraction imaging system, method and storage medium

Abstract

This application discloses an ultrafast diffraction imaging system, method, and storage medium. The ultrafast diffraction imaging system includes a laser generation module, a time stretching module, an encoding module, an image acquisition module, and a control processing module. The laser generation module emits laser light. The time stretching module is optically connected to the laser generation module and stretches the laser light into a time data stream. The encoding module is optically connected to the time stretching module and encodes the time data stream to obtain an encoding matrix. The image acquisition module is connected to the encoding module and captures the encoding matrix to obtain an observation image. The control processing module is communicatively connected to both the laser generation module and the image acquisition module. The control processing module performs phase reconstruction based on the observation image sent by the image acquisition module to obtain a target phase change sequence frame. This system effectively improves the efficiency of ultrafast diffraction imaging while enabling phase change observation of ultrafast dynamic scenes.

Description

Technical Field

[0001] This application relates to, but is not limited to, the field of ultrafast imaging technology, and in particular to an ultrafast diffraction imaging system, method, and storage medium. Background Technology

[0002] Ultrafast imaging is essentially a high-resolution projection of photoelectric imaging in the time dimension, providing finer-grained image representations of photoelectric imaging over time. Recording transient diffraction processes using ultrafast imaging technology has significant value in both scientific research and engineering applications. Applications of ultrafast imaging include shock wave propagation, laser-induced ultrafast processes, and exciton diffusion. Conventional array-type photoelectric sensors can only sense the intensity of light signals, lacking phase information and unable to record phase changes in the light signal during diffraction. Related technologies typically use ultrafast interferometry to observe phase changes in the light signal during diffraction, employing multiple laser pulses to sequentially illuminate the sample and interfere with an additional reference beam, then using a single detector to record and form an interferogram. However, the reference beam makes the optical structure of the imaging system very complex, resulting in low imaging efficiency. Summary of the Invention

[0003] This application provides an ultrafast diffraction imaging system, method, and storage medium, which can effectively improve the efficiency of ultrafast diffraction imaging.

[0004] In a first aspect, embodiments of this application provide an ultrafast diffraction imaging system, comprising:

[0005] A laser generating module, wherein the laser generating module is used to emit laser light;

[0006] A time stretching module is optically connected to the laser generation module and is used to stretch the laser into a time data stream.

[0007] An encoding module is optically connected to the time stretching module. The encoding module is used to encode the time data stream to obtain an encoding matrix.

[0008] An image acquisition module is connected to the encoding module, and the image acquisition module is used to capture the encoding matrix to obtain an observation image;

[0009] The control processing module is communicatively connected to both the laser generation module and the image acquisition module. The control processing module is used to perform phase reconstruction based on the observed image sent by the image acquisition module to obtain a target phase change sequence frame.

[0010] The ultrafast diffraction imaging system according to the first aspect of this application has at least the following beneficial effects: The ultrafast diffraction imaging system includes a laser generation module, a time stretching module, an encoding module, an image acquisition module, and a control processing module. The time stretching module is optically connected to the laser generation module, the encoding module is optically connected to the time stretching module, the image acquisition module is connected to the encoding module, and the control processing module is communicatively connected to both the laser generation module and the image acquisition module. The control processing module controls the laser generation module to emit laser light. The laser light travels along the optical path to the time stretching module. Utilizing the decomposability of laser light in the spatial and temporal domains, the time stretching module stretches the laser light into a time data stream. This allows the encoding module to encode the time data stream using the different pulse frequency components of the laser light, obtaining an encoding matrix. The encoding matrix is ​​then transmitted along the optical path to the image acquisition module, which captures the encoding matrix, enabling the capture of ultrafast dynamic scenes and obtaining observation images. The control processing module then performs phase reconstruction based on the observation images sent by the image acquisition module to obtain a target phase change sequence frame, effectively improving the efficiency of ultrafast diffraction imaging and enabling the observation of phase changes in ultrafast dynamic scenes. Based on the ultrafast diffraction imaging system provided in this application, the laser is decomposed in both the spatial and temporal domains. The laser is sequentially time-stretched and encoded. The encoded matrix is ​​transmitted along the optical path to the image acquisition module, which then captures the encoded matrix to obtain the observed image, thus enabling the capture of ultrafast dynamic scenes. Finally, the control processing module performs phase reconstruction based on the observed image to obtain a target phase change sequence frame, thereby enabling the observation of phase changes in ultrafast dynamic scenes. Compared with related technologies that use multiple laser pulses to sequentially illuminate the sample and interfere with an additional unstable reference beam, and then use a single detector to expose and record to form an interferogram to observe the phase changes of the light signal during diffraction, this method can effectively improve the efficiency of ultrafast diffraction imaging.

[0011] According to some embodiments of the first aspect of this application, a filtering module is also included, the filtering module including an objective lens and a pinhole, the objective lens being connected to the time stretching module and the pinhole optical path respectively, and the pinhole being connected to the encoding module optical path.

[0012] According to some embodiments of the first aspect of this application, the time stretching module includes a spatial dispersiver and a temporal dispersiver, wherein the spatial dispersiver is optically connected to the temporal dispersiver.

[0013] According to some embodiments of the first aspect of this application, the encoding module includes a first reflector, a second reflector, a collimator, and a mask, wherein the first reflector, the collimator, the mask, and the second reflector are sequentially optically connected.

[0014] Secondly, embodiments of this application provide an ultrafast diffraction imaging method, applied to the control and processing module of the ultrafast diffraction imaging system described in the first aspect, comprising:

[0015] Acquire the observed image sent by the image acquisition module;

[0016] The observed image is processed using a preset dispersive Fourier transform formula to obtain a frequency-time mapping.

[0017] Based on the frequency-time mapping, the observed image is processed according to a preset optical diffraction algorithm to obtain a diffraction pattern sequence frame;

[0018] Using a preset phase reconstruction algorithm, the diffraction pattern sequence frames are reconstructed to obtain the target phase change sequence frames.

[0019] The ultrafast diffraction imaging method according to the second aspect of this application has at least the following beneficial effects: acquiring the observation image sent by the image acquisition module, processing the observation image using a preset dispersive Fourier transform formula to obtain a frequency-time mapping, so as to process the observation image based on the frequency-time mapping according to a preset light wave diffraction algorithm to obtain a diffraction pattern sequence frame, which can effectively improve the computational efficiency; then using a preset phase reconstruction algorithm to perform phase reconstruction on the diffraction pattern sequence frame to obtain a target phase change sequence frame, thereby realizing the observation of phase changes in ultrafast dynamic scenes while effectively improving the efficiency of ultrafast diffraction imaging.

[0020] According to some embodiments of the second aspect of this application, the dispersive Fourier transform formula is:

[0021]

[0022] Where β is the propagation constant of the optical fiber, ω is the angular frequency, ω0 is the center frequency of the dissipative structure, T is the time within the reference frame, T = t - β1L, L is the length of the optical fiber, t is the optical fiber time, and the m-th derivative of β is...

[0023] According to some embodiments of the second aspect of this application, the optical diffraction algorithm is as follows:

[0024]

[0025] Among them, U P (x, y) are the phasors of the observed image. For phase delay factor, This is the symbol for the Fourier transform.

[0026] According to some embodiments of the second aspect of this application, the step of using a preset phase reconstruction algorithm to perform phase reconstruction on the diffraction pattern sequence frames to obtain a target phase change sequence frame includes:

[0027] Based on the preset initial phase and the first light wave amplitude distribution data of the diffraction pattern sequence frame, the output light wave function is iteratively calculated until the mean square error of the output light wave function is less than the preset error threshold; wherein, in the iterative calculation of the output light wave function, the output light wave function is successfully calculated each time, and a reference diffraction pattern is obtained based on the output light wave function;

[0028] According to the preset phase reconstruction rules, the phase of multiple reference diffraction patterns is reconstructed to obtain the target phase change sequence frame.

[0029] According to some embodiments of the second aspect of this application, the iterative calculation process of the output light wave function based on the preset initial phase and the first light wave amplitude distribution data of the diffraction pattern sequence frame includes:

[0030] Based on the preset initial phase and the first light wave amplitude distribution data of the diffraction pattern sequence frame, the incident light wave function is obtained;

[0031] Perform a Fourier transform on the incident light wave function to obtain the output light wave function and the second light wave amplitude distribution data;

[0032] Based on the first phase and the second amplitude distribution data of the output light wave function, a reference function is obtained;

[0033] Perform an inverse Fourier transform on the reference function to obtain the target function;

[0034] The initial phase is updated using the second phase of the objective function, and a new output light wave function is recalculated based on the updated initial phase.

[0035] Thirdly, embodiments of this application also provide a computer-readable storage medium storing computer-executable instructions for causing a computer to perform the ultrafast diffraction imaging method as described in the second aspect. Attached Figure Description

[0036] The accompanying drawings are provided to further understand the technical solutions of the present invention and constitute a part of the specification. They are used together with the embodiments of the present invention to explain the technical solutions of the present invention, and do not constitute a limitation on the technical solutions of the present invention.

[0037] Figure 1 This is a schematic diagram of a module of an ultrafast diffraction imaging system provided in one embodiment of this application;

[0038] Figure 2 This is a schematic diagram of the optical path of an ultrafast diffraction imaging system provided in another embodiment of this application;

[0039] Figure 3 This is a flowchart of the steps of an ultrafast diffraction imaging method provided in another embodiment of this application;

[0040] Figure 4 This is a flowchart of the steps for obtaining a target phase change sequence frame according to another embodiment of this application;

[0041] Figure 5 This is a flowchart of the iterative calculation processing method provided in another embodiment of this application;

[0042] Figure 6 This is a flowchart of the steps of an ultrafast diffraction imaging method provided in another embodiment of this application. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0044] It is understandable that although functional modules are divided in the device schematic diagram and a logical order is shown in the flowchart, in some cases, the steps shown or described may be performed in a different order than the module division in the device or the order in the flowchart. The terms "first," "second," etc., in the specification, claims, or the aforementioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0045] This application provides an ultrafast diffraction imaging system, method, and storage medium. The ultrafast diffraction imaging system includes a laser generation module, a time stretching module, an encoding module, an image acquisition module, and a control processing module. The time stretching module is optically connected to the laser generation module, the encoding module is optically connected to the time stretching module, the image acquisition module is connected to the encoding module, and the control processing module is communicatively connected to both the laser generation module and the image acquisition module. The control processing module controls the laser generation module to emit laser light. This laser light travels along the optical path to the time stretching module. Utilizing the decomposability of laser light in the spatial and temporal domains, the time stretching module stretches the laser light into a time data stream. This allows the encoding module to encode the time data stream using the different pulse frequency components of the laser light, obtaining an encoding matrix. The encoding matrix is ​​then transmitted along the optical path to the image acquisition module, which captures the encoding matrix, enabling the capture of ultrafast dynamic scenes and obtaining observation images. The control processing module then performs phase reconstruction based on the observation images sent by the image acquisition module, obtaining a target phase change sequence frame, which effectively improves the efficiency of ultrafast diffraction imaging and enables the observation of phase changes in ultrafast dynamic scenes. Based on the ultrafast diffraction imaging system provided in this application, the laser is decomposed in both the spatial and temporal domains. The laser is sequentially time-stretched and encoded. The encoded matrix is ​​transmitted along the optical path to the image acquisition module, which then captures the encoded matrix to obtain the observed image, thus enabling the capture of ultrafast dynamic scenes. Finally, the control processing module performs phase reconstruction based on the observed image to obtain a target phase change sequence frame, thereby enabling the observation of phase changes in ultrafast dynamic scenes. Compared with related technologies that use multiple laser pulses to sequentially illuminate the sample and interfere with an additional unstable reference beam, and then use a single detector to expose and record to form an interferogram to observe the phase changes of the light signal during diffraction, this method can effectively improve the efficiency of ultrafast diffraction imaging.

[0046] The embodiments of this application will be further described below with reference to the accompanying drawings.

[0047] Reference Figure 1 , Figure 1 This is a schematic diagram of a module of an ultrafast diffraction imaging system 100 provided in one embodiment of this application. The ultrafast diffraction imaging system 100 includes:

[0048] Laser generating module 110, which is used to emit laser light;

[0049] The time stretching module 120 is optically connected to the laser generation module 110 and is used to stretch the laser into a time data stream.

[0050] Encoding module 130 is optically connected to time stretching module 120. Encoding module 130 is used to encode the time data stream to obtain an encoding matrix.

[0051] Image acquisition module 140 is connected to encoding module 130. Image acquisition module 140 is used to capture the encoding matrix and obtain the observation image.

[0052] The control processing module 150 is communicatively connected to the laser generation module 110 and the image acquisition module 140, respectively. The control processing module 150 is used to perform phase reconstruction based on the observation image sent by the image acquisition module 140 to obtain the target phase change sequence frame.

[0053] It should be noted that the embodiments of this application do not limit the specific type of the laser generation module 110, which can be a mode-locked laser, a femtosecond pulsed laser, or a fiber laser, etc. Similarly, the embodiments of this application do not limit the specific type of the image acquisition module 140, which can be a synchronous stripe camera, a femtosecond stripe camera, or a high dynamic range stripe camera, etc.

[0054] Understandably, the control processing module 150 controls the laser generation module 110 to emit a laser beam. This laser beam travels along the optical path to the time stretching module 120. Utilizing the decomposability of the laser beam in both the spatial and temporal domains, the time stretching module 120 stretches the laser beam into a time data stream. This allows the encoding module 130 to encode the time data stream using the different pulse frequency components of the laser beam, obtaining an encoding matrix. The encoding matrix is ​​then transmitted along the optical path to the image acquisition module 140, enabling the image acquisition module 140 to quickly capture the encoding matrix, thus achieving the capture of ultrafast dynamic scenes and obtaining observation images. The control processing module 150 then performs phase reconstruction based on the observation images sent by the image acquisition module 140, obtaining a target phase change sequence frame. This enables high-precision quantitative imaging of the phase process in non-repeatable ultrafast dynamic scenes, and while achieving phase change observation of ultrafast dynamic scenes, it effectively improves the efficiency of ultrafast diffraction imaging. Based on the ultrafast diffraction imaging system 100 provided in this application, the laser is decomposed in both the spatial and temporal domains. The laser is time-stretched and encoded sequentially. The encoded matrix is ​​transmitted along the optical path to the image acquisition module 140, which then captures the encoded matrix to obtain the observation image, thus realizing the capture of ultrafast dynamic scenes. Finally, the control processing module 150 performs phase reconstruction based on the observation image to obtain the target phase change sequence frame, thereby realizing the observation of phase changes in ultrafast dynamic scenes. Compared with the related technologies that use multiple laser pulses to sequentially illuminate the sample and interfere with an additional unstable reference beam, and then use a single detector to expose and record to form an interferogram to observe the phase changes of the light signal during diffraction, this method does not require specific light source constraints, has a simple optical path, and can effectively improve the efficiency of ultrafast diffraction imaging.

[0055] Reference Figure 2 In some embodiments of this application, the ultrafast diffraction imaging system 100 further includes a filtering module 160, which includes an objective lens 161 and a pinhole 162. The objective lens 161 is optically connected to the time stretching module 120 and the pinhole 162, respectively, and the pinhole 162 is optically connected to the encoding module 130.

[0056] It should be noted that the embodiments of this application do not limit the type of objective lens 161; it can be a 4X objective lens, a 10X objective lens, etc. It is understood that using a 4X objective lens can reduce light loss.

[0057] Understandably, objective lens 161 is connected to the time stretching module 120 and pinhole 162 optical paths respectively, and pinhole 162 is connected to the encoding module 130 optical path. The time stretching module 120 stretches the laser in time to obtain a time data stream. This time data stream passes through objective lens 161 and pinhole 162 of the filtering module 160 in sequence to achieve spatial filtering of the time data stream, thereby improving the quality of the output time data stream so that the encoding module 130 can encode it, effectively improving the accuracy and efficiency of the encoding.

[0058] In some embodiments of this application, the time stretching module 120 includes a spatial dispersiver 121 and a temporal dispersiver 122, with the spatial dispersiver 121 and the temporal dispersiver 122 optically connected.

[0059] Understandably, the laser generated by the laser generation module 110 passes sequentially along the optical path through the spatial dispersor 121 and the temporal dispersor 122. The laser enters the spatial dispersor 121, which maps the laser into a 1D or 2D rainbow beam. The dynamic sample 200 is placed behind the spatial dispersor 121, and the rainbow beam illuminates the dynamic sample 200. Because the laser pulse frequency components are different, their corresponding spatial coordinates on the dynamic sample 200 are also different, enabling the encoding of the rainbow beam. The encoded rainbow beam returns to the spatial dispersor 121, which reassembles the encoded rainbow beam into a single laser pulse. This laser pulse enters the temporal dispersor 122 along the optical path, where it undergoes pulse spectrum mapping or temporal stretching to create a 1D temporal data stream.

[0060] In some embodiments of this application, the encoding module 130 includes a first reflector 131, a second reflector 132, a collimator 133, and a mask 134, with the first reflector 131, the collimator 133, the mask 134, and the second reflector 132 connected in sequence via optical paths.

[0061] It should be noted that the embodiments of this application do not limit the specific number and position of the reflectors. They may include a first reflector 131 and a second reflector 132, or they may include a first reflector 131, a second reflector 132, a third reflector, and a fourth reflector, etc. The goal is to enable the angle adjustment of the time data stream so that the time data stream can be accurately transmitted to the target position.

[0062] Understandably, the time data stream is transmitted to the encoding module 130 via the optometry path, passing sequentially through the first reflector 131, collimator 133, mask 134, and second reflector 132. The first reflector 131 adjusts the angle of the time data stream, ensuring it accurately reaches the collimator 133. The collimator 133 then collimates the time data stream to improve directional stability and guides it to illuminate the mask 134, resulting in an encoding matrix. The mask 134 is pre-loaded with a random matrix, which is used to encode the time data stream, effectively improving encoding efficiency while maintaining accuracy. Subsequently, the second reflector 132 transmits the encoding matrix to the image acquisition module 140. Upon reaching the fully open slit, the image acquisition module 140 captures the encoded matrix, recording the ultra-fast dynamic scene and obtaining the observed image.

[0063] It is understood that the ultrafast diffraction imaging system 100 provided in this application embodiment can achieve ultrafast dynamic scene phase imaging with high spatial and temporal resolution using a simple optical setup, and can use lasers with different pulse durations to achieve temporal resolution on the nanosecond to femtosecond scale. It can quantitatively characterize ultrafast dynamic scene phase processes such as transient changes in materials caused by electromagnetic radiation, laser-matter interactions, and laser entry into biological cells, achieving high-precision quantitative imaging of non-repeatable ultrafast dynamic scene phase processes.

[0064] Reference Figure 3 , Figure 3 This is a flowchart of another embodiment of the ultrafast diffraction imaging method provided in this application. This ultrafast diffraction imaging method is applied to the control and processing module 150 of the aforementioned ultrafast diffraction imaging system 100. The ultrafast diffraction imaging method includes, but is not limited to, the following steps:

[0065] Step S310: Acquire the observation image sent by the image acquisition module;

[0066] Step S320: The observed image is processed using a preset dispersive Fourier transform formula to obtain a frequency-time mapping.

[0067] Step S330: Based on frequency-time mapping, the observed image is processed according to a preset optical wave diffraction algorithm to obtain a diffraction pattern sequence frame;

[0068] Step S340: Using a preset phase reconstruction algorithm, phase reconstruction is performed on the diffraction pattern sequence frames to obtain the target phase change sequence frames.

[0069] Understandably, the image acquisition module 140 acquires the observed image, processes it using a preset dispersive Fourier transform formula, maps the optical spectrum of the laser to a time-domain waveform using the dispersive Fourier transform formula, and obtains a frequency-time mapping. This facilitates real-time spectral measurement of ultrafast dynamic scenes. Subsequently, based on the frequency-time mapping, the observed image is processed according to a preset optical diffraction algorithm to obtain a diffraction pattern sequence frame, which can effectively improve computational efficiency. Then, a preset phase reconstruction algorithm is used to reconstruct the phase of the diffraction pattern sequence frame to obtain a target phase change sequence frame. This enables high-precision quantitative imaging of the phase process of non-repeatable ultrafast dynamic scenes. Furthermore, while realizing the observation of phase changes in ultrafast dynamic scenes, it can effectively improve the efficiency of ultrafast diffraction imaging.

[0070] In some embodiments of this application, the dispersive Fourier transform formula is:

[0071]

[0072] Where β is the propagation constant of the optical fiber, ω is the angular frequency, ω0 is the center frequency of the dissipative structure, T is the time within the reference frame, T = t - β1L, L is the length of the optical fiber, t is the optical fiber time, and the m-th derivative of β is...

[0073] It is understandable that, considering only second-order dispersion and neglecting nonlinear effects and losses in the optical fiber, the impulse response function can be expressed as:

[0074]

[0075] Where β²L corresponds to the group velocity dispersion of the optical fiber, and its time-domain response function is:

[0076]

[0077] Then the output pulse A(0,T) is:

[0078]

[0079] According to the definition of Fourier transform, the formula for dispersive Fourier transform can be obtained:

[0080]

[0081] in, This represents the Fourier transform of the function A(0,T). As can be seen from the dispersive Fourier transform formula, after time stretching, the spectral information of the laser is mapped onto the time domain, thus obtaining a frequency-time mapping.

[0082] In some embodiments of this application, the light wave diffraction algorithm is as follows:

[0083]

[0084] Among them, U P (x,y) represents the phasor of the observed image. For phase delay factor, This is the symbol for the Fourier transform.

[0085] It is understandable that the electromagnetic vector for a monochromatic electromagnetic wave can be expressed as: E(r,t)=U(r)e -iwt ,

[0086] At the same time, the phasor U(r) satisfies the Helmholtz equation: in,

[0087] Let the distance between the diffraction screen and the observation screen be z, then U Q (x,y) and U S (x, y) are the phasors on the diffraction screen and the observation screen, respectively.

[0088] In the frequency domain, the spectral functions corresponding to the phasors on the diffraction screen and the observation screen are G. Q (f x ,f y ) and G S (f x ,f y Then we have:

[0089]

[0090]

[0091] Therefore, U s (x,y) is G s (f x ,f y The inverse Fourier transform of ) gives:

[0092]

[0093] Substituting this expression into the Helmholtz equation, and assuming that U satisfies the Helmholtz equation, we obtain:

[0094] After calculation and simplification, we obtain:

[0095]

[0096] And G Q (f x ,f y ) is a particular solution of the equation at z = 0.

[0097] Therefore, the result of light waves propagating along the z-axis, in the frequency domain, is the diffracted spectrum G of the light wave. Q (f x ,f y Multiply by a z-related phase delay factor

[0098] The propagation of a light wave in free space from the diffraction screen to the observation screen is equivalent in the frequency domain to passing through a region with a radius of... For an ideal low-pass filter, using Fourier transform notation, the optical wave diffraction algorithm can be obtained as follows:

[0099]

[0100] Reference Figure 4 In one embodiment, Figure 3 Step S340 in the illustrated embodiment also includes, but is not limited to, the following steps:

[0101] Step S410: Based on the preset initial phase and the first light wave amplitude distribution data of the diffraction pattern sequence frame, perform iterative calculation of the output light wave function until the mean square error of the output light wave function is less than the preset error threshold; wherein, in the iterative calculation of the output light wave function, the output light wave function is successfully calculated each time, and the reference diffraction pattern is obtained based on the output light wave function.

[0102] Step S420: According to the preset phase reconstruction rules, the phase of multiple reference diffraction patterns is reconstructed to obtain the target phase change sequence frame.

[0103] It should be noted that the embodiments of this application do not limit the specific content of the preset phase reconstruction rules. They can be based on time order rules or the order in which the reference diffraction patterns are obtained. It is understood that performing phase reconstruction on multiple reference diffraction patterns according to time order rules can yield a more accurate target phase change sequence frame, thereby ensuring the authenticity and reliability of phase change observations of ultrafast dynamic scenes.

[0104] Understandably, iteratively calculating the output wavefunction based on the preset initial phase and the first light wave amplitude distribution data of the diffraction pattern sequence frame until the mean square error of the output wavefunction is less than a preset error threshold can effectively improve the reliability of obtaining the reference diffraction pattern based on the output wavefunction. In the iterative calculation of the output wavefunction, each successful calculation of the output wavefunction yields a reference diffraction pattern, which is then used to reconstruct the phase of multiple reference diffraction patterns according to a preset phase reconstruction rule, thereby obtaining the target phase change sequence frame. This enables high-precision quantitative imaging of the phase process in non-repeatable ultrafast dynamic scenes, and effectively improves the efficiency of ultrafast diffraction imaging while observing the phase changes in ultrafast dynamic scenes.

[0105] Additionally, refer to Figure 5 In one embodiment, Figure 4 Step S410 in the illustrated embodiment also includes, but is not limited to, the following steps:

[0106] Step S510: Obtain the incident light wave function based on the preset initial phase and the first light wave amplitude distribution data of the diffraction pattern sequence frame;

[0107] Step S520: Perform a Fourier transform on the incident light wave function to obtain the output light wave function and the second light wave amplitude distribution data;

[0108] Step S530: Obtain the reference function based on the first phase and second amplitude distribution data of the output light wave function;

[0109] Step S540: Perform an inverse Fourier transform on the reference function to obtain the target function;

[0110] Step S550: Update the initial phase using the second phase of the objective function, and recalculate the new output light wave function based on the updated initial phase.

[0111] Understandably, based on the preset initial phase and the amplitude distribution data of the first light wave in the diffraction pattern sequence frame, the incident light wave function is obtained. Subsequently, a Fourier transform is performed on the incident light wave function to obtain the output light wave function and the amplitude distribution data of the second light wave. Based on the first phase and the amplitude distribution data of the output light wave function, a reference function is obtained. Then, an inverse Fourier transform is performed on the reference function to obtain the target function. Finally, the second phase of the target function is used to update the initial phase, and a new output light wave function is recalculated based on the updated initial phase. Through multi-level iterative calculation processing, the reliability of obtaining the reference diffraction pattern based on the output light wave function can be effectively improved.

[0112] It is understood that, in one embodiment, an initial phase on the input plane can be randomly set, denoted as . Combined with the measured light wave amplitude distribution data |F(x,y)| on the known input plane, the incident light wave function f(x,y) is constructed. Then, a Fourier transform is performed on f(x,y) to obtain the output light wave function g(u,v) on the output plane. The first phase of g(u,v) is taken and combined with the measured second light wave amplitude distribution data |G(u,v)| on the output plane to construct g′(u,v). An inverse Fourier transform is performed on g′(u,v) to obtain the target function f′(x,y). The second phase of f′(x,y) is then compared with the initial phase. Update and replace The new output wavefunction is recalculated based on the updated initial phase. In this embodiment, the mean square error of the output wavefunction can be expressed as: SSE=[∫∫(|g(u,v)|-|G(u,v)| 2 dudv] / [|G(u,v)| 2 dudv].

[0113] Additionally, refer to Figure 6 In one embodiment, the ultrafast diffraction imaging method may further include, but is not limited to, the following steps:

[0114] Step S610: Acquire the observation image sent by the image acquisition module;

[0115] Step S620: Input the observed image into the preset image reconstruction model to obtain a dynamic scene diffraction pattern sequence frame;

[0116] Step S630: Phase reconstruction is performed on the dynamic scene diffraction pattern sequence frames using the preset GS algorithm to obtain the dynamic scene phase information sequence frames.

[0117] Understandably, after the dynamic process of the laser is encoded by the encoding module 130, the image acquisition module 140 cuts out the dynamic scene and captures the cut scene to obtain a compressed dynamic scene diffraction pattern, i.e., the observation image. The control and processing module 150 of the ultrafast diffraction imaging system 100 acquires the observation image sent by the image acquisition module 140 and inputs the observation image into a preset image reconstruction model to obtain a dynamic scene diffraction pattern sequence frame. Then, the preset GS algorithm is used to perform phase reconstruction on the dynamic scene diffraction pattern sequence frame to obtain a dynamic scene phase information sequence frame, which can realize the observation of phase changes of ultrafast dynamic scenes.

[0118] Furthermore, one embodiment of this application provides a computer-readable storage medium storing computer-executable instructions that are executed by a processor or controller. For example, execution by a processor causes the processor to perform the ultrafast diffraction imaging method applied to the control processing module 150 of the ultrafast diffraction imaging system 100 described above, for example, performing the above-described... Figure 3 Method steps S310 to S340 in the middle Figure 4 Method steps S410 to S420 in the middle Figure 5 Method steps S510 to S550 and Figure 6 Method steps S610 to S630 are described above. Those skilled in the art will understand that all or some of the steps in the methods disclosed above, and the system, can be implemented as software, firmware, hardware, and suitable combinations thereof. Some or all physical components can be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application-specific integrated circuit. Such software can be distributed on a computer-readable medium, which can include computer storage media (or non-transitory media) and communication media (or transient media). As is known to those skilled in the art, the term computer storage media includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disc (DVD) or other optical disc storage, magnetic cartridges, magnetic tape, disk storage or other magnetic storage devices, or any other medium that can be used to store desired information and is accessible to a computer. Furthermore, as is known to those skilled in the art, communication media typically contain computer-readable instructions, data structures, program modules, or other data in modulated data signals such as carrier waves or other transmission mechanisms, and may include any information delivery medium.

[0119] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0120] The above is a detailed description of the preferred embodiments of this application. However, this application is not limited to the above embodiments. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of this application. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. An ultrafast diffraction imaging system, characterized in that, include: A laser generating module, wherein the laser generating module is used to emit laser light; A time stretching module is optically connected to the laser generation module and is used to stretch the laser into a time data stream. An encoding module is optically connected to the time stretching module. The encoding module is used to encode the time data stream to obtain an encoding matrix. An image acquisition module is connected to the encoding module, and the image acquisition module is used to capture the encoding matrix to obtain an observation image; The control processing module is communicatively connected to both the laser generation module and the image acquisition module. The control processing module is used to perform phase reconstruction based on the observed image sent by the image acquisition module to obtain a target phase change sequence frame.

2. The ultrafast diffraction imaging system according to claim 1, characterized in that, It also includes a filtering module, which includes an objective lens and a pinhole. The objective lens is connected to the time stretching module and the pinhole optical path, respectively, and the pinhole is connected to the encoding module optical path.

3. The ultrafast diffraction imaging system according to claim 1, characterized in that, The time stretching module includes a spatial dispersiver and a temporal dispersiver, with the spatial dispersiver and the temporal dispersiver optically connected.

4. The ultrafast diffraction imaging system according to claim 1, characterized in that, The encoding module includes a first reflector, a second reflector, a collimator, and a mask, wherein the first reflector, the collimator, and the mask are sequentially optically connected.

5. An ultrafast diffraction imaging method, applied to the control and processing module of the ultrafast diffraction imaging system according to any one of claims 1 to 4, characterized in that, include: Acquire the observed image sent by the image acquisition module; The observed image is processed using a preset dispersive Fourier transform formula to obtain a frequency-time mapping. Based on the frequency-time mapping, the observed image is processed according to a preset optical diffraction algorithm to obtain a diffraction pattern sequence frame; Using a preset phase reconstruction algorithm, the diffraction pattern sequence frames are reconstructed to obtain the target phase change sequence frames.

6. The ultrafast diffraction imaging method according to claim 5, characterized in that, The dispersive Fourier transform formula is as follows: Where β is the propagation constant of the optical fiber, ω is the angular frequency, ω0 is the center frequency of the dissipative structure, T is the time within the reference frame, T = t - β1L, L is the length of the optical fiber, t is the optical fiber time, and the m-th derivative of β is...

7. The ultrafast diffraction imaging method according to claim 5, characterized in that, The optical diffraction algorithm is as follows: Among them, U P (x,y) is the phasor of the observed image. For phase delay factor, This is the symbol for the Fourier transform.

8. The ultrafast diffraction imaging method according to claim 5, characterized in that, The step of using a preset phase reconstruction algorithm to perform phase reconstruction on the diffraction pattern sequence frames to obtain the target phase change sequence frames includes: Based on the preset initial phase and the first light wave amplitude distribution data of the diffraction pattern sequence frame, the output light wave function is iteratively calculated until the mean square error of the output light wave function is less than the preset error threshold; wherein, in the iterative calculation of the output light wave function, the output light wave function is successfully calculated each time, and a reference diffraction pattern is obtained based on the output light wave function; According to the preset phase reconstruction rules, the phase of multiple reference diffraction patterns is reconstructed to obtain the target phase change sequence frame.

9. The ultrafast diffraction imaging method according to claim 8, characterized in that, The iterative calculation of the output light wave function based on the preset initial phase and the first light wave amplitude distribution data of the diffraction pattern sequence frame includes: Based on the preset initial phase and the first light wave amplitude distribution data of the diffraction pattern sequence frame, the incident light wave function is obtained; Perform a Fourier transform on the incident light wave function to obtain the output light wave function and the second light wave amplitude distribution data; Based on the first phase and the second amplitude distribution data of the output light wave function, a reference function is obtained; Perform an inverse Fourier transform on the reference function to obtain the target function; The initial phase is updated using the second phase of the objective function, and a new output light wave function is recalculated based on the updated initial phase.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer-executable instructions for causing a computer to perform the ultrafast diffraction imaging method as described in any one of claims 5 to 9.

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