Coherent diffractive imaging （CDI） is a lensless imaging technique and can achieve a resolution beyond the Rayleigh or Abbe limit. The ptychographical iterative engine （PIE） is a CDI phase retrieval algorithm that...Coherent diffractive imaging （CDI） is a lensless imaging technique and can achieve a resolution beyond the Rayleigh or Abbe limit. The ptychographical iterative engine （PIE） is a CDI phase retrieval algorithm that uses multiple diffraction patterns obtained through the scan of a localized illumination on the specimen, which has been demonstrated successfully at optical and X-ray wavelengths. In this paper, a general PIE algorithm （gPIE） is presented and demonstrated with an He-Ne laser light diffraction dataset. This algorithm not only permits the removal of the accurate model of the illumination function in PIE, but also provides improved convergence speed and retrieval quality.展开更多
In oil and gas exploration,small-scale karst cavities and faults are important targets.The former often serve as reservoir space for carbonate reservoirs,while the latter often provide migration pathways for oil and g...In oil and gas exploration,small-scale karst cavities and faults are important targets.The former often serve as reservoir space for carbonate reservoirs,while the latter often provide migration pathways for oil and gas.Due to these differences,the classification and identification of karst cavities and faults are of great significance for reservoir development.Traditional seismic attributes and diffraction imaging techniques can effectively identify discontinuities in seismic images,but these techniques do not distinguish whether these discontinuities are karst cavities,faults,or other structures.It poses a challenge for seismic interpretation to accurately locate and classify karst cavities or faults within the seismic attribute maps and diffraction imaging profiles.In seismic data,the scattering waves are associated with small-scale scatters like karst cavities,while diffracted waves are seismic responses from discontinuous structures such as faults,reflector edges and fractures.In order to achieve classification and identification of small-scale karst cavities and faults in seismic images,we propose a diffraction classification imaging method which classifies diffracted and scattered waves in the azimuth-dip angle image matrix using a modified DenseNet.We introduce a coordinate attention module into DenseNet,enabling more precise extraction of dynamic and azimuthal features of diffracted and scattered waves in the azimuth-dip angle image matrix.Leveraging these extracted features,the modified DenseNet can produce reliable probabilities for diffracted/scattered waves,achieving high-accuracy automatic classification of cavities and faults based on diffraction imaging.The proposed method achieves 96%classification accuracy on the synthetic dataset.The field data experiment demonstrates that the proposed method can accurately classify small-scale faults and scatterers,further enhancing the resolution of diffraction imaging in complex geologic structures,and contributing to the localization of karstic fracture-cavern reservoirs.展开更多
The Shanghai soft X-ray free-electron laser(SXFEL)user facility project started in 2016 and is expected to be open to users by 2022.It aims to deliver ultra-intense coherent femtosecond X-ray pulses to five endstation...The Shanghai soft X-ray free-electron laser(SXFEL)user facility project started in 2016 and is expected to be open to users by 2022.It aims to deliver ultra-intense coherent femtosecond X-ray pulses to five endstations covering a range of 100–620 eV for ultrafast X-ray science.Two undulator lines are designed and constructed,based on different lasing modes:self-amplified spontaneous emission and echo-enabled harmonic generation.The coherent scattering and imaging(CSI)endstation is the first of five endstations to be commissioned online.It focuses on high-resolution single-shot imaging and the study of ultrafast dynamic processes using coherent forward scattering techniques.Both the single-shot holograms and coherent diffraction patterns were recorded and reconstructed for nanoscale imaging,indicating the excellent coherence and high peak power of the SXFEL and the possibility of‘‘diffraction before destruction’’experiments at the CSI endstation.In this study,we report the first commissioning results of the CSI endstation.展开更多
Fracture-cave reservoirs in carbonate rocks are characterized by a large difference in fracture and cavity size,and a sharp variation in lithology and velocity,thereby resulting in complex diffraction responses.Some s...Fracture-cave reservoirs in carbonate rocks are characterized by a large difference in fracture and cavity size,and a sharp variation in lithology and velocity,thereby resulting in complex diffraction responses.Some small-scale fractures and caves cause weak diffraction energy and would be obscured by the continuous reflection layer in the imaging section,thereby making them difficult to identify.This paper develops a diffraction wave imaging method in the dip domain,which can improve the resolution of small-scale diffractors in the imaging section.Common imaging gathers(CIGs)in the dip domain are extracted by Gaussian beam migration.In accordance with the geometric differences of the diffraction being quasilinear and the reflection being quasiparabolic in the dip-domain CIGs,we use slope analysis technique to filter waves and use Hanning window function to improve the diffraction wave separation level.The diffraction dip-domain CIGs are stacked horizontally to obtain diffraction imaging results.Wavefield separation analysis and numerical modeling results show that the slope analysis method,together with Hanning window filtering,can better suppress noise to obtain the diffraction dip-domain CIGs,thereby improving the clarity of the diffractors in the diffraction imaging section.展开更多
Reflection imaging results generally reveal large-scale continuous geological information,and it is difficult to identify small-scale geological bodies such as breakpoints,pinch points,small fault blocks,caves,and fra...Reflection imaging results generally reveal large-scale continuous geological information,and it is difficult to identify small-scale geological bodies such as breakpoints,pinch points,small fault blocks,caves,and fractures,etc.Diffraction imaging is an important method to identify small-scale geological bodies and it has higher resolution than reflection imaging.In the common-offset domain,reflections are mostly expressed as smooth linear events,whereas diffractions are characterized by hyperbolic events.This paper proposes a diffraction extraction method based on double sparse transforms.The linear events can be sparsely expressed by the high-resolution linear Radon transform,and the curved events can be sparsely expressed by the Curvelet transform.A sparse inversion model is built and the alternating direction method is used to solve the inversion model.Simulation data and field data experimental results proved that the diffractions extraction method based on double sparse transforms can effectively improve the imaging quality of faults and other small-scale geological bodies.展开更多
A nonlinear sliding mode adaptive controller for a thin-film diffractive imaging system is designed to achieve accurate pointing direction over the attitude of subarrays in large-diameter mirror arrays.The kinematics ...A nonlinear sliding mode adaptive controller for a thin-film diffractive imaging system is designed to achieve accurate pointing direction over the attitude of subarrays in large-diameter mirror arrays.The kinematics and dynamics equations based on error quaternion and angular velocity are derived,and a diffractive thin-film sub-mirror array controller is designed to point precisely.Moreover,the global stability of the controller is proved by the Lyapunov method.Since the controller can adaptively identify the inertia matrix of each sub-mirror system,it is robust to bounded disturbances and changes in inertia parameters.At the same time,the continuous arctangent function is introduced,which is effectively anti-chattering.The simulation results show that the designed controller can ensure the accurate tracking of the diffractive film in each sub-mirror in the presence of rotational inertia matrix uncertainty and various disturbances.展开更多
Three-dimensional imaging with single orientation is a potential and novel technique. We successfully demonstrate that three-dimensional（3D） structure can be determined by a single orientation diffraction measuremen...Three-dimensional imaging with single orientation is a potential and novel technique. We successfully demonstrate that three-dimensional（3D） structure can be determined by a single orientation diffraction measurement for a phase object of double-layer Mie-scattering silica spheres on a Si3N4 membrane. Coherent diffraction pattern at high numerical aperture was acquired with an optical laser, and the oversampled pattern was projected from a planar detector onto the Ewald sphere.The double-layered spheres are reconstructed from the spherical diffraction pattern and a 2D curvature-corrected pattern,which improve convergence speed and stability of reconstruction.展开更多
Coherent diffractive imaging(CDI),with its lensless geometry and theoretically perfect transfer function,is considered as one of the most promising paradigms to achieve the Abbe resolution limit.However,recent advance...Coherent diffractive imaging(CDI),with its lensless geometry and theoretically perfect transfer function,is considered as one of the most promising paradigms to achieve the Abbe resolution limit.However,recent advances on pushing the resolution limit in high-numerical-aperture(NA)CDIs has thus far been challenging.Here,we report a nearly 0.9NA CDI with an optimized imaging factor(k=0.501),pushing the Abbe resolution diffraction limit for the first time in ultra-high-NA scenarios.Leveraging this the ultra-high NA and the Abbe-limit k-factor,we demonstrate a record-high imaging resolution of 0.57λfor CDIs.Our approach builds upon a novel computational framework termed‘rigorous Fraunhofer diffraction’that eliminates the Ewald sphere effect in CDIs,particularly for high NAs.Our framework transforms the general challenge of high-NA,resolution-limited CDIs from relying on approximate and complicated geometric corrections to a solvable problem through rigorous model-based computation.展开更多
Lensless imaging is an approach to microscopy in which a high-resolution image of an object is reconstructed from one or more measured diffraction patterns,providing a solution in situations where the use of imaging o...Lensless imaging is an approach to microscopy in which a high-resolution image of an object is reconstructed from one or more measured diffraction patterns,providing a solution in situations where the use of imaging optics is not possible.However,current lensless imaging methods are typically limited by the need for a light source with a narrow,stable and accurately known spectrum.We have developed a general approach to lensless imaging without spectral bandwidth limitations or sample requirements.We use two time-delayed coherent light pulses and show that scanning the pulse-to-pulse time delay allows the reconstruction of diffraction-limited images for all the spectral components in the pulse.In addition,we introduce an iterative phase retrieval algorithm that uses these spectrally resolved Fresnel diffraction patterns to obtain high-resolution images of complex extended objects.We demonstrate this two-pulse imaging method with octave-spanning visible light sources,in both transmission and reflection geometries,and with broadband extreme-ultraviolet radiation from a high-harmonic generation source.Our approach enables effective use of low-flux ultra-broadband sources,such as table-top high-harmonic generation systems,for high-resolution imaging.展开更多
The pure γ-Ca2SiO4 （]t-C2S） phase was prepared at 1623 K of calcining temperature, 10 h of holding time and furnace cooling. The 13-C2S phase was obtained through γ-C2S conversion with the following calcination sy...The pure γ-Ca2SiO4 （]t-C2S） phase was prepared at 1623 K of calcining temperature, 10 h of holding time and furnace cooling. The 13-C2S phase was obtained through γ-C2S conversion with the following calcination system which was adopted at 1473 K of calcining temperature, 1 h of holding time and then water-cooling. The conversion rate of γ-C2S was studied by the Rietveld quantitative laboratory X-ray powder diffraction supported by synchrotron X-ray diffraction images. The refinement results show that the final conversion rate of γ-C2S is higher than 92%. The absolute error of the γ-C2S conversion rate between two Rietveld refinements （sample with or without α-Al2O3） is 3.6%, which shows that the Rietveld quantitative X-ray diffraction analysis is an appropriate and accurate method to quantify the γ-C2S conversion rate.展开更多
While ptychography is an algorithm based on coherent illumination,satisfactory reconstructions can still be generated in most experiments,even though the radiation sources that are used are not ideally coherent.The un...While ptychography is an algorithm based on coherent illumination,satisfactory reconstructions can still be generated in most experiments,even though the radiation sources that are used are not ideally coherent.The underlying physics of this phenomenon is that the diffraction patterns of partially coherent illumination can be treated as those of purely coherent illumination by altering the intensities of the diffracted beams relative to their real values.On the other hand,due to the inconsistency in the altering interference among all the diffraction beams,noise/distortion is always involved in the reconstructed images.Furthermore,for a weak object,the noise/distortion in the reconstruction can be mostly reduced by using a highly curved beam for illumination in the data recording and forcing the dark field diffraction to be zero in the reconstruction.展开更多
We propose and experimentally demonstrate a noniterative diffractive imaging method for reconstructing the complex-valued transmission function of an object illuminated by spatially partially coherent light from the f...We propose and experimentally demonstrate a noniterative diffractive imaging method for reconstructing the complex-valued transmission function of an object illuminated by spatially partially coherent light from the far-field diffraction pattern.Our method is based on a pinhole array mask,which is specially designed such that the correlation function in the mask plane can be obtained directly by inverse Fourier transforming the diffraction pattern.Compared to the traditional iterative diffractive imaging methods using spatially partially coherent illumination,our method is noniterative and robust to the degradation of the spatial coherence of the illumination.In addition to diffractive imaging,the proposed method can also be applied to spatial coherence property characterization,e.g.,free-space optical communication and optical coherence singularity measurement.展开更多
This review is focused on using computer image analysis as a means of objective and quantitative characterizing optical images of the macroscopic (e.g. microbial colonies) and the microscopic (e.g. single cell) object...This review is focused on using computer image analysis as a means of objective and quantitative characterizing optical images of the macroscopic (e.g. microbial colonies) and the microscopic (e.g. single cell) objects in the microbiological research. This is the way of making many visual inspection assays more objective and less time and labor consuming. Also, it can provide new visually inaccessible information on relation between some optical parameters and various biological features of the microbial cul-tures. Of special interest is application of image analysis in fluorescence microscopy as it opens new ways of using fluorescence based methodology for single microbial cell studies. Examples of using image analysis in the studies of both the macroscopic and the microscopic microbiological objects obtained by various imaging techniques are presented and discussed.展开更多
This study addresses the challenge posed by the small spore size of tomato gray mold,which hinders its identification and enumeration by conventional techniques.This work presents a novel approach for quantifying spor...This study addresses the challenge posed by the small spore size of tomato gray mold,which hinders its identification and enumeration by conventional techniques.This work presents a novel approach for quantifying spore counts of tomato gray mold using diffraction imaging technology and image processing techniques.To construct a device for acquiring diffraction images of tomato gray mold spores,initially,the hyperspectral data pertaining to the gray mold spores of tomatoes was obtained.The characteristic wavelength of the light source of the diffraction image acquisition device was obtained by smoothing,principal component analysis,and comprehensive coefficient weight calculation.Then,the key parameters of the system were simulated,and the diffraction image acquisition device was built.Finally,tomato gray mold spores were counted based on angular spectrum reconstruction and image processing.The findings indicated that the combined contribution rate of the initial and secondary principal components of the original spectral data obtained from tomato gray mold spore samples amounted to 92.271%.The visible range of 435 nm,475 nm,and 720 nm can be selected as the light source for tomato gray mold’s spore diffraction imaging system.CMOS image sensor was installed 45 mm below the micropore with a diameter of 100μm,and the diffraction image obtained by simulation has a clear diffraction fingerprint.The diffraction imaging system can collect diffraction images of disease spores,and the collected diffraction images have clear diffraction fingerprints.The experimental error range was 5.13%-8.57%,and the average error was 6.42%.The error was within a 95%consistency.Therefore,this study can provide a research basis for the classification and recognition of greenhouse disease spores.展开更多
Coherent diffraction imaging(CDI)provides lens-free imaging with diffraction-limited resolution and has become an important imaging modality at synchrotron facilities worldwide.The performance of current CDI approache...Coherent diffraction imaging(CDI)provides lens-free imaging with diffraction-limited resolution and has become an important imaging modality at synchrotron facilities worldwide.The performance of current CDI approaches remains limited,particularly in their ability to handle dynamic samples or achieve consistent high-quality reconstructions.Here,we propose a novel coherent imaging approach for dynamic samples,which exploits the inter-frame continuity of the sample’s local structures as an additional constraint in phasing a sequence of diffraction patterns.Our algorithm incorporates an adaptive similarity determination procedure,eliminating the requirement for invariant regions in the sample and ensuring broad applicability to diverse sample types.We demonstrated the feasibility of this technique through experiments on various dynamic samples,achieving high-fidelity reconstructions within a few hundred iterations.With the same simple setup as conventional CDI,high image quality,and the ability to separate the sample transmission from its illumination probe,our method has the potential to significantly advance X-ray imaging and electron microscopy techniques for dynamic sample analysis.展开更多
Single-shot multi-frame phase imaging plays an important role in detecting continuous extreme physical phenomena,particularly suitable for measuring the density of media with non-repeatable changes and uncertainties.H...Single-shot multi-frame phase imaging plays an important role in detecting continuous extreme physical phenomena,particularly suitable for measuring the density of media with non-repeatable changes and uncertainties.However,traditional single-pattern multiplexed imaging faces challenges in retrieving amplitude and phase information of multiple frames without sacrificing spatial resolution and phase accuracy。展开更多
Coherent diffraction imaging(CDI)enables diffraction-limited high-resolution imaging without using high-quality lenses.It will be desirable to combine it with multiple spectral light sources to achieve chemically reso...Coherent diffraction imaging(CDI)enables diffraction-limited high-resolution imaging without using high-quality lenses.It will be desirable to combine it with multiple spectral light sources to achieve chemically resolved imaging capability.Here,we demonstrate a single-frame multiwavelength CDI approach that can provide complex transmittance images of a sample at multiple wavelengths.The superior performance of our method in terms of rapid convergence and improved image quality over current methods has been validated through high-harmonic extreme ultraviolet experiments.The feasibility of our method for single-frame chemical imaging is also demonstrated by the simulation.This work can pave the way for implementing in situ chemical imaging with tabletop high-harmonic generation extreme ultraviolet sources.展开更多
The integration of deep learning into computational imaging has driven substantial advancements in coherent diffraction imaging(CDI).While physics-driven neural networks have emerged as a promising approach through th...The integration of deep learning into computational imaging has driven substantial advancements in coherent diffraction imaging(CDI).While physics-driven neural networks have emerged as a promising approach through their unsupervised learning paradigm,their practical implementation faces critical challenges:measurement uncertainties in physical parameters(e.g.,the propagation distance and the size of sample area)severely degrade reconstruction quality.To overcome this limitation,we propose a deep-learning-enabled spatial sample interval optimization framework that synergizes physical models with neural network adaptability.Our method embeds spatial sample intervals as trainable parameters within a PhysenNet architecture coupled with Fresnel diffraction physics,enabling simultaneous image reconstruction and system parameter calibration.Experimental validation demonstrates robust performance with structural similarity(SSIM)values consistently maintained at 0.6 across diffraction distances spanning of 10-200 mm,using a 1024×1024 region of interest(ROI)from a 1624×1440 CCD(pixel size:4.5μm)under 632.8 nm illumination.This framework has excellent fault tolerance,that is,it can still maintain high-quality image restoration even when the propagation distance measurement error is large.Compared to conventional iterative reconstruction algorithms,this approach can transform fixed parameters into learnable parameters,making almost all image restoration experiments easier to implement,enhancing system robustness against experimental uncertainties.This work establishes,to our knowledge,a new paradigm for adaptive diffraction imaging systems capable of operating in complex real scenarios.展开更多
X-ray diffraction enhanced imaging （DEI） has extremely high sensitivity for weakly absorbing low- Z samples in medical and biological fields. In this paper, we propose an Algebra Reconstruction Technique （ART） ite...X-ray diffraction enhanced imaging （DEI） has extremely high sensitivity for weakly absorbing low- Z samples in medical and biological fields. In this paper, we propose an Algebra Reconstruction Technique （ART） iterative reconstruction algorithm for computed tomography of diffraction enhanced imaging （DEI-CT）. An Ordered Subsets （OS） technique is used to accelerate the ART reconstruction. Few-view reconstruction is also studied, and a partial differential equation （PDE） type filter which has the ability of edge-preserving and denoising is used to improve the image quality and eliminate the artifacts. The proposed algorithm is validated with both the numerical simulations and the experiment at the Beijing synchrotron radiation facility （BSRF）.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11179009 and 50875013)the Beijing Municipal Natural Science Foundation, China (Grant No. 4102036)the Beijing NOVA Program, China (Grant No. 2009A09)
文摘Coherent diffractive imaging （CDI） is a lensless imaging technique and can achieve a resolution beyond the Rayleigh or Abbe limit. The ptychographical iterative engine （PIE） is a CDI phase retrieval algorithm that uses multiple diffraction patterns obtained through the scan of a localized illumination on the specimen, which has been demonstrated successfully at optical and X-ray wavelengths. In this paper, a general PIE algorithm （gPIE） is presented and demonstrated with an He-Ne laser light diffraction dataset. This algorithm not only permits the removal of the accurate model of the illumination function in PIE, but also provides improved convergence speed and retrieval quality.
基金supported by Science Fund for Creative Research Groups of the National Natural Science Foundation of China,No.42321002。
文摘In oil and gas exploration,small-scale karst cavities and faults are important targets.The former often serve as reservoir space for carbonate reservoirs,while the latter often provide migration pathways for oil and gas.Due to these differences,the classification and identification of karst cavities and faults are of great significance for reservoir development.Traditional seismic attributes and diffraction imaging techniques can effectively identify discontinuities in seismic images,but these techniques do not distinguish whether these discontinuities are karst cavities,faults,or other structures.It poses a challenge for seismic interpretation to accurately locate and classify karst cavities or faults within the seismic attribute maps and diffraction imaging profiles.In seismic data,the scattering waves are associated with small-scale scatters like karst cavities,while diffracted waves are seismic responses from discontinuous structures such as faults,reflector edges and fractures.In order to achieve classification and identification of small-scale karst cavities and faults in seismic images,we propose a diffraction classification imaging method which classifies diffracted and scattered waves in the azimuth-dip angle image matrix using a modified DenseNet.We introduce a coordinate attention module into DenseNet,enabling more precise extraction of dynamic and azimuthal features of diffracted and scattered waves in the azimuth-dip angle image matrix.Leveraging these extracted features,the modified DenseNet can produce reliable probabilities for diffracted/scattered waves,achieving high-accuracy automatic classification of cavities and faults based on diffraction imaging.The proposed method achieves 96%classification accuracy on the synthetic dataset.The field data experiment demonstrates that the proposed method can accurately classify small-scale faults and scatterers,further enhancing the resolution of diffraction imaging in complex geologic structures,and contributing to the localization of karstic fracture-cavern reservoirs.
基金the Shanghai Soft X-ray Free-Electron Laser Facility beamline projectionfunded by the Major State Basic Research Development Program of China(No.2017YFA0504802)+1 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB 37040303)National Natural Science Foundation of China(No.21727817).
文摘The Shanghai soft X-ray free-electron laser(SXFEL)user facility project started in 2016 and is expected to be open to users by 2022.It aims to deliver ultra-intense coherent femtosecond X-ray pulses to five endstations covering a range of 100–620 eV for ultrafast X-ray science.Two undulator lines are designed and constructed,based on different lasing modes:self-amplified spontaneous emission and echo-enabled harmonic generation.The coherent scattering and imaging(CSI)endstation is the first of five endstations to be commissioned online.It focuses on high-resolution single-shot imaging and the study of ultrafast dynamic processes using coherent forward scattering techniques.Both the single-shot holograms and coherent diffraction patterns were recorded and reconstructed for nanoscale imaging,indicating the excellent coherence and high peak power of the SXFEL and the possibility of‘‘diffraction before destruction’’experiments at the CSI endstation.In this study,we report the first commissioning results of the CSI endstation.
基金funded jointly by the National Natural Science Foundation of China(No.41104069)Shandong Province Higher Educational Science and Technology Program(No.J17KA197)+1 种基金Open Foundation of Shandong Provincial Key Laboratory of Depositional Mineralization&Sedimentary Minerals of Shandong University of Science and Technology(No.DMSM2018018)Chunhui Research Foundation of Shengli College,China University of Petroleum(No.KY2017007)。
文摘Fracture-cave reservoirs in carbonate rocks are characterized by a large difference in fracture and cavity size,and a sharp variation in lithology and velocity,thereby resulting in complex diffraction responses.Some small-scale fractures and caves cause weak diffraction energy and would be obscured by the continuous reflection layer in the imaging section,thereby making them difficult to identify.This paper develops a diffraction wave imaging method in the dip domain,which can improve the resolution of small-scale diffractors in the imaging section.Common imaging gathers(CIGs)in the dip domain are extracted by Gaussian beam migration.In accordance with the geometric differences of the diffraction being quasilinear and the reflection being quasiparabolic in the dip-domain CIGs,we use slope analysis technique to filter waves and use Hanning window function to improve the diffraction wave separation level.The diffraction dip-domain CIGs are stacked horizontally to obtain diffraction imaging results.Wavefield separation analysis and numerical modeling results show that the slope analysis method,together with Hanning window filtering,can better suppress noise to obtain the diffraction dip-domain CIGs,thereby improving the clarity of the diffractors in the diffraction imaging section.
基金supported by National Natural Science Foundation of China(41974166)Natural Science Foundation of Hebei Province(D2019403082,D2021403010)+1 种基金Hebei Province“three-threethree talent project”(A202005009)Funding for the Science and Technology Innovation Team Project of Hebei GEO University(KJCXTD202106)
文摘Reflection imaging results generally reveal large-scale continuous geological information,and it is difficult to identify small-scale geological bodies such as breakpoints,pinch points,small fault blocks,caves,and fractures,etc.Diffraction imaging is an important method to identify small-scale geological bodies and it has higher resolution than reflection imaging.In the common-offset domain,reflections are mostly expressed as smooth linear events,whereas diffractions are characterized by hyperbolic events.This paper proposes a diffraction extraction method based on double sparse transforms.The linear events can be sparsely expressed by the high-resolution linear Radon transform,and the curved events can be sparsely expressed by the Curvelet transform.A sparse inversion model is built and the alternating direction method is used to solve the inversion model.Simulation data and field data experimental results proved that the diffractions extraction method based on double sparse transforms can effectively improve the imaging quality of faults and other small-scale geological bodies.
基金supported by the Central University Basic Research Fund of China(No.3072022CFJ0202)the Central University Basic Research Fund of China(No.3072022CFJ0204)。
文摘A nonlinear sliding mode adaptive controller for a thin-film diffractive imaging system is designed to achieve accurate pointing direction over the attitude of subarrays in large-diameter mirror arrays.The kinematics and dynamics equations based on error quaternion and angular velocity are derived,and a diffractive thin-film sub-mirror array controller is designed to point precisely.Moreover,the global stability of the controller is proved by the Lyapunov method.Since the controller can adaptively identify the inertia matrix of each sub-mirror system,it is robust to bounded disturbances and changes in inertia parameters.At the same time,the continuous arctangent function is introduced,which is effectively anti-chattering.The simulation results show that the designed controller can ensure the accurate tracking of the diffractive film in each sub-mirror in the presence of rotational inertia matrix uncertainty and various disturbances.
基金Project supported by the Major State Basic Research Development Program of China(Grant No.2014CB910401)the National Natural Science Foundation of China(Grant Nos.31430031,21390414,and U1332118)
文摘Three-dimensional imaging with single orientation is a potential and novel technique. We successfully demonstrate that three-dimensional（3D） structure can be determined by a single orientation diffraction measurement for a phase object of double-layer Mie-scattering silica spheres on a Si3N4 membrane. Coherent diffraction pattern at high numerical aperture was acquired with an optical laser, and the oversampled pattern was projected from a planar detector onto the Ewald sphere.The double-layered spheres are reconstructed from the spherical diffraction pattern and a 2D curvature-corrected pattern,which improve convergence speed and stability of reconstruction.
基金supported by National Natural Science Foundation of China(52130504,52450258)Key Research and Development Program of Hubei Province(2021BAA013)+2 种基金Innovation Project of Optics Valley Laboratory(OVL2023PY003)Guangdong Basic and Applied Basic Research Foundation(2023A1515030149)Major Science and Technology Innovation Project of HUST(2024ZDKJCX09).
文摘Coherent diffractive imaging(CDI),with its lensless geometry and theoretically perfect transfer function,is considered as one of the most promising paradigms to achieve the Abbe resolution limit.However,recent advances on pushing the resolution limit in high-numerical-aperture(NA)CDIs has thus far been challenging.Here,we report a nearly 0.9NA CDI with an optimized imaging factor(k=0.501),pushing the Abbe resolution diffraction limit for the first time in ultra-high-NA scenarios.Leveraging this the ultra-high NA and the Abbe-limit k-factor,we demonstrate a record-high imaging resolution of 0.57λfor CDIs.Our approach builds upon a novel computational framework termed‘rigorous Fraunhofer diffraction’that eliminates the Ewald sphere effect in CDIs,particularly for high NAs.Our framework transforms the general challenge of high-NA,resolution-limited CDIs from relying on approximate and complicated geometric corrections to a solvable problem through rigorous model-based computation.
基金This work is financed in part by an NWO-groot investment grant of the Netherlands Organisation for Scientific Research(NWO)and Laserlab Europe(JRA Bioptichal)SW acknowledges support from NWO Veni grant 680-47-402.
文摘Lensless imaging is an approach to microscopy in which a high-resolution image of an object is reconstructed from one or more measured diffraction patterns,providing a solution in situations where the use of imaging optics is not possible.However,current lensless imaging methods are typically limited by the need for a light source with a narrow,stable and accurately known spectrum.We have developed a general approach to lensless imaging without spectral bandwidth limitations or sample requirements.We use two time-delayed coherent light pulses and show that scanning the pulse-to-pulse time delay allows the reconstruction of diffraction-limited images for all the spectral components in the pulse.In addition,we introduce an iterative phase retrieval algorithm that uses these spectrally resolved Fresnel diffraction patterns to obtain high-resolution images of complex extended objects.We demonstrate this two-pulse imaging method with octave-spanning visible light sources,in both transmission and reflection geometries,and with broadband extreme-ultraviolet radiation from a high-harmonic generation source.Our approach enables effective use of low-flux ultra-broadband sources,such as table-top high-harmonic generation systems,for high-resolution imaging.
基金Project supported by the National Natural Science Foundation of China(No.51102181)the National Basic Research Program (973) of China(No.2009CB623104)the Open Fund of Large Apparatus of Tongji University(Nos.0002012004 and 0002012012),China
文摘The pure γ-Ca2SiO4 （]t-C2S） phase was prepared at 1623 K of calcining temperature, 10 h of holding time and furnace cooling. The 13-C2S phase was obtained through γ-C2S conversion with the following calcination system which was adopted at 1473 K of calcining temperature, 1 h of holding time and then water-cooling. The conversion rate of γ-C2S was studied by the Rietveld quantitative laboratory X-ray powder diffraction supported by synchrotron X-ray diffraction images. The refinement results show that the final conversion rate of γ-C2S is higher than 92%. The absolute error of the γ-C2S conversion rate between two Rietveld refinements （sample with or without α-Al2O3） is 3.6%, which shows that the Rietveld quantitative X-ray diffraction analysis is an appropriate and accurate method to quantify the γ-C2S conversion rate.
基金supported by the Funds from the Engineering and Physical Sciences Research Council(Grant No.EP/E034055/1)the One Hundred Talent Project of the Chinese Academy of Sciences and the Financial Support(Grant No.GFZX0205010502.12)
文摘While ptychography is an algorithm based on coherent illumination,satisfactory reconstructions can still be generated in most experiments,even though the radiation sources that are used are not ideally coherent.The underlying physics of this phenomenon is that the diffraction patterns of partially coherent illumination can be treated as those of purely coherent illumination by altering the intensities of the diffracted beams relative to their real values.On the other hand,due to the inconsistency in the altering interference among all the diffraction beams,noise/distortion is always involved in the reconstructed images.Furthermore,for a weak object,the noise/distortion in the reconstruction can be mostly reduced by using a highly curved beam for illumination in the data recording and forcing the dark field diffraction to be zero in the reconstruction.
基金This work was supported by the National Natural Science Foundation of China(Nos.11774250 , 91750201)the National Natural Science Fund for Distinguished Young Scholars(No.11525418)the sponsorship of Jiangsu Overseas Research and Training Program for Prominent Young and Middle-aged University Teachers and Presidents.This work is also part of the research program“Novel design shapes for complex optical systems,”with Project No.12797,which is(partly)financed by the Netherlands Organization for Scientific Research(NWO).
文摘We propose and experimentally demonstrate a noniterative diffractive imaging method for reconstructing the complex-valued transmission function of an object illuminated by spatially partially coherent light from the far-field diffraction pattern.Our method is based on a pinhole array mask,which is specially designed such that the correlation function in the mask plane can be obtained directly by inverse Fourier transforming the diffraction pattern.Compared to the traditional iterative diffractive imaging methods using spatially partially coherent illumination,our method is noniterative and robust to the degradation of the spatial coherence of the illumination.In addition to diffractive imaging,the proposed method can also be applied to spatial coherence property characterization,e.g.,free-space optical communication and optical coherence singularity measurement.
文摘This review is focused on using computer image analysis as a means of objective and quantitative characterizing optical images of the macroscopic (e.g. microbial colonies) and the microscopic (e.g. single cell) objects in the microbiological research. This is the way of making many visual inspection assays more objective and less time and labor consuming. Also, it can provide new visually inaccessible information on relation between some optical parameters and various biological features of the microbial cul-tures. Of special interest is application of image analysis in fluorescence microscopy as it opens new ways of using fluorescence based methodology for single microbial cell studies. Examples of using image analysis in the studies of both the macroscopic and the microscopic microbiological objects obtained by various imaging techniques are presented and discussed.
基金partially supported by the National Natural Science Foundation of China(Grant Nos.32071905,3217895,and 32201686)Priority Academic Program Development of Jiangsu Higher Education Institutions(Grant No.PAPD-2023-87)+3 种基金Agricultural Equipment Department of Jiangsu University(Grant No.NZXB20210106)National Key Research and Development Program for Young Scientists(Grant No.2022YFD2000013)General Program of Basic Science(Natural Science)Research in Higher Education Institutions of Jiangsu Province(Grant No.23KJB210004)Natural Science Foundation of Jiangsu Province for Youth(Grant No.BK20240880).
文摘This study addresses the challenge posed by the small spore size of tomato gray mold,which hinders its identification and enumeration by conventional techniques.This work presents a novel approach for quantifying spore counts of tomato gray mold using diffraction imaging technology and image processing techniques.To construct a device for acquiring diffraction images of tomato gray mold spores,initially,the hyperspectral data pertaining to the gray mold spores of tomatoes was obtained.The characteristic wavelength of the light source of the diffraction image acquisition device was obtained by smoothing,principal component analysis,and comprehensive coefficient weight calculation.Then,the key parameters of the system were simulated,and the diffraction image acquisition device was built.Finally,tomato gray mold spores were counted based on angular spectrum reconstruction and image processing.The findings indicated that the combined contribution rate of the initial and secondary principal components of the original spectral data obtained from tomato gray mold spore samples amounted to 92.271%.The visible range of 435 nm,475 nm,and 720 nm can be selected as the light source for tomato gray mold’s spore diffraction imaging system.CMOS image sensor was installed 45 mm below the micropore with a diameter of 100μm,and the diffraction image obtained by simulation has a clear diffraction fingerprint.The diffraction imaging system can collect diffraction images of disease spores,and the collected diffraction images have clear diffraction fingerprints.The experimental error range was 5.13%-8.57%,and the average error was 6.42%.The error was within a 95%consistency.Therefore,this study can provide a research basis for the classification and recognition of greenhouse disease spores.
基金supported by the National Natural Science Foundation of China(Grant no.12074167)the Shenzhen Science and Technology Innovation Program(Grant no.JCYJ20241202125334045).
文摘Coherent diffraction imaging(CDI)provides lens-free imaging with diffraction-limited resolution and has become an important imaging modality at synchrotron facilities worldwide.The performance of current CDI approaches remains limited,particularly in their ability to handle dynamic samples or achieve consistent high-quality reconstructions.Here,we propose a novel coherent imaging approach for dynamic samples,which exploits the inter-frame continuity of the sample’s local structures as an additional constraint in phasing a sequence of diffraction patterns.Our algorithm incorporates an adaptive similarity determination procedure,eliminating the requirement for invariant regions in the sample and ensuring broad applicability to diverse sample types.We demonstrated the feasibility of this technique through experiments on various dynamic samples,achieving high-fidelity reconstructions within a few hundred iterations.With the same simple setup as conventional CDI,high image quality,and the ability to separate the sample transmission from its illumination probe,our method has the potential to significantly advance X-ray imaging and electron microscopy techniques for dynamic sample analysis.
基金China Postdoctoral Science Foundation(2023M743252,2024T170846)Key Research and Development Program of Zhejiang Province(2024SSYS0014)National Natural Science Foundation of China(62205304).
文摘Single-shot multi-frame phase imaging plays an important role in detecting continuous extreme physical phenomena,particularly suitable for measuring the density of media with non-repeatable changes and uncertainties.However,traditional single-pattern multiplexed imaging faces challenges in retrieving amplitude and phase information of multiple frames without sacrificing spatial resolution and phase accuracy。
基金supported by the National Natural Science Foundation of China(No.12074167)the Shenzhen ScienceandTechnologyInnovationProgram(No.JCYJ20241202125334045)。
文摘Coherent diffraction imaging(CDI)enables diffraction-limited high-resolution imaging without using high-quality lenses.It will be desirable to combine it with multiple spectral light sources to achieve chemically resolved imaging capability.Here,we demonstrate a single-frame multiwavelength CDI approach that can provide complex transmittance images of a sample at multiple wavelengths.The superior performance of our method in terms of rapid convergence and improved image quality over current methods has been validated through high-harmonic extreme ultraviolet experiments.The feasibility of our method for single-frame chemical imaging is also demonstrated by the simulation.This work can pave the way for implementing in situ chemical imaging with tabletop high-harmonic generation extreme ultraviolet sources.
基金supported by the Basic and Applied Basic Research Foundation of Guangdong Province(No.2022A1515110203)the Science and Technology Research Project of Jiangxi Provincial Department of Education(No.GJJ203501)。
文摘The integration of deep learning into computational imaging has driven substantial advancements in coherent diffraction imaging(CDI).While physics-driven neural networks have emerged as a promising approach through their unsupervised learning paradigm,their practical implementation faces critical challenges:measurement uncertainties in physical parameters(e.g.,the propagation distance and the size of sample area)severely degrade reconstruction quality.To overcome this limitation,we propose a deep-learning-enabled spatial sample interval optimization framework that synergizes physical models with neural network adaptability.Our method embeds spatial sample intervals as trainable parameters within a PhysenNet architecture coupled with Fresnel diffraction physics,enabling simultaneous image reconstruction and system parameter calibration.Experimental validation demonstrates robust performance with structural similarity(SSIM)values consistently maintained at 0.6 across diffraction distances spanning of 10-200 mm,using a 1024×1024 region of interest(ROI)from a 1624×1440 CCD(pixel size:4.5μm)under 632.8 nm illumination.This framework has excellent fault tolerance,that is,it can still maintain high-quality image restoration even when the propagation distance measurement error is large.Compared to conventional iterative reconstruction algorithms,this approach can transform fixed parameters into learnable parameters,making almost all image restoration experiments easier to implement,enhancing system robustness against experimental uncertainties.This work establishes,to our knowledge,a new paradigm for adaptive diffraction imaging systems capable of operating in complex real scenarios.
基金Supported by National Natural Science Foundation of China (10875066)Program for New Century Excellent Talents in University (NCET-05-0060)
文摘X-ray diffraction enhanced imaging （DEI） has extremely high sensitivity for weakly absorbing low- Z samples in medical and biological fields. In this paper, we propose an Algebra Reconstruction Technique （ART） iterative reconstruction algorithm for computed tomography of diffraction enhanced imaging （DEI-CT）. An Ordered Subsets （OS） technique is used to accelerate the ART reconstruction. Few-view reconstruction is also studied, and a partial differential equation （PDE） type filter which has the ability of edge-preserving and denoising is used to improve the image quality and eliminate the artifacts. The proposed algorithm is validated with both the numerical simulations and the experiment at the Beijing synchrotron radiation facility （BSRF）.
