Large-scale computational imaging can provide remarkable space-bandwidth product that is beyond the limit of optical systems.In coherent imaging(CI),the joint reconstruction of amplitude and phase further expands the ...Large-scale computational imaging can provide remarkable space-bandwidth product that is beyond the limit of optical systems.In coherent imaging(CI),the joint reconstruction of amplitude and phase further expands the information throughput and sheds light on label-free observation of biological samples at micro-or even nano-levels.The existing large-scale CI techniques usually require scanning/modulation multiple times to guarantee measurement diversity and long exposure time to achieve a high signal-to-noise ratio.Such cumbersome procedures restrict clinical applications for rapid and lowphototoxicity cell imaging.In this work,a complex-domain-enhancing neural network for large-scale CI termed CI-CDNet is proposed for various large-scale CI modalities with satisfactory reconstruction quality and efficiency.CI-CDNet is able to exploit the latent coupling information between amplitude and phase(such as their same features),realizing multidimensional representations of the complex wavefront.The cross-field characterization framework empowers strong generalization and robustness for various coherent modalities,allowing high-quality and efficient imaging under extremely low exposure time and few data volume.We apply CI-CDNet in various large-scale CI modalities including Kramers–Kronigrelations holography,Fourier ptychographic microscopy,and lensless coded ptychography.A series of simulations and experiments validate that CI-CDNet can reduce exposure time and data volume by more than 1 order of magnitude.We further demonstrate that the high-quality reconstruction of CI-CDNet benefits the subsequent high-level semantic analysis.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
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
We propose and implement a wide-field vibrational phase contrast detection to obtain imaging of imaginary components of third-order nonlinear susceptibility in a coherent anti-Stokes Raman scattering （CARS） microsco...We propose and implement a wide-field vibrational phase contrast detection to obtain imaging of imaginary components of third-order nonlinear susceptibility in a coherent anti-Stokes Raman scattering （CARS） microscope with full suppression of the non-resonant background. This technique is based on the unique ability of recovering the phase of the generated CARS signal based on holographic recording. By capturing the phase distributions of the generated CARS field from the sample and from the environment under resonant illumination, we demonstrate the retrieval of imaginary components in the CARS microscope and achieve background free coherent Raman imaging.展开更多
Return signal processing and reconstruction plays a pivotal role in coherent field imaging, having a significant in- fluence on the quality of the reconstructed image. To reduce the required samples and accelerate the...Return signal processing and reconstruction plays a pivotal role in coherent field imaging, having a significant in- fluence on the quality of the reconstructed image. To reduce the required samples and accelerate the sampling process, we propose a genuine sparse reconstruction scheme based on compressed sensing theory. By analyzing the sparsity of the received signal in the Fourier spectrum domain, we accomplish an effective random projection and then reconstruct the return signal from as little as 10% of traditional samples, finally acquiring the target image precisely. The results of the numerical simulations and practical experiments verify the correctness of the proposed method, providing an efficient processing approach for imaging fast-moving targets in the future.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
AIM:To evaluate the choroidopathy in patients with systemic lupus erythematosus(SLE)using enhanced depth imaging spectral domain optical coherence tomography(EDI SD-OCT)and optical coherence tomography angiography(OCT...AIM:To evaluate the choroidopathy in patients with systemic lupus erythematosus(SLE)using enhanced depth imaging spectral domain optical coherence tomography(EDI SD-OCT)and optical coherence tomography angiography(OCTA).METHODS:A total of 74 patients with SLE and 40 healthy volunteers were included in this cross-sectional study.SLE patients were further divided into three subgroups based on clinical and blood biochemistry findings.Ocular parameters obtained on ophthalmologic examination and optical imaging(EDI SD-OCT and OCTA)included the best corrected distance visual acuity(logMAR CDVA),subfoveal choroidal thickness(SCT),choroidal vascularity index(CVI)and vessel density(VD)of superficial capillary plexus(SCP)and deep capillary plexus(DCP).RESULTS:SLE patients had significantly lower values for CVI and VD of DCP(DVD)than control subjects.Amongst SLE patients,gender and chloroquine dose were found to be independent determinants of CVI while age predicted SCT.Steroid dose was a significant predictor for foveal VD of SCP(SVD),chloroquine dose for parafoveal SVD,gender for total DVD,and gender and steroid dose for perifoveal DVD.No correlation of logMAR CDVA and SCT was noted between SLE patients and control subjects.No correlation of SCT was noted with disease duration,Systemic Lupus Erythematosus Disease Activity Index(SLEDAI)score,hydroxychloroquine(HCQ)dose or steroid dose.No correlation of CVI was noted with patient age,disease duration,SLEDAI score,HCQ dose or steroid dose.No significant difference was noted between SLE subgroups in terms of any of the ocular parameters studied.CONCLUSION:The findings reveal the presence of ocular findings suggestive of early onset choroidopathy on EDI SD-OCT and OCTA in SLE patients,in the absence of ocular manifestations or active disease.展开更多
AIM：To assess peripapillary retinal nerve fiber layer（RNFL）and choroidal thickness obtained with enhanced depth imaging（EDI）mode compared with those obtained without EDI mode using Heidelberg Spectralis optical c...AIM：To assess peripapillary retinal nerve fiber layer（RNFL）and choroidal thickness obtained with enhanced depth imaging（EDI）mode compared with those obtained without EDI mode using Heidelberg Spectralis optical coherence tomography（OCT）.METHODS：Fifty eyes of 25 normal healthy subjects and32 eyes of 20 patients with different eye diseases were included in the study.All subjects underwent 3.4 mm diameter peripapillary circular OCT scan centered on the optic disc using both the conventional and the EDI OCT protocols.The visualization of RNFL and choroidoscleral junction was assessed using an ordinal scoring scale.The paired t-test,intraclass correlation coefficient（ICC）,95%limits of agreement（LoA）,and Bland and Altman plots were used to test the agreement of measurements.RESULTS：The visibility score of RNFL obtained with and without EDI was of no significant difference（P=0.532）,the visualization of choroidoscleral junction was better using EDI protocol than conventional protocol（P〈0.001）.Peripapillary RNFL thickness obtained with EDI was slightly thicker than that obtained without EDI（103.25±9.42μm vs 101.87±8.78μm,P=0.010）.The ICC of the two protocols was excellent with the value of 0.867 to 0.924,the 95%LoA of global RNFL thickness was between-10.0 to 7.4μm.Peripapillary choroidal thickness obtained with EDI was slightly thinner than that obtained without EDI（147.23±51.04μm vs 150.90±51.84μm,P〈0.001）.The ICC was also excellent with the value of 0.960 to 0.987,the 95%LoA of global choroidal thickness was between-12.5 to 19.8μm.CONCLUSION：Peripapillary circular OCT scan with or without EDI mode shows comparable results in the measurement of peripapillary RNFL and choroidal thickness.展开更多
An experimental measurement was performed us- ing time-resolved particle image velocimetry （TRPIV） to in- vestigate the spatial topological character of coherent struc- tures in wall-bounded turbulence of polymer ad...An experimental measurement was performed us- ing time-resolved particle image velocimetry （TRPIV） to in- vestigate the spatial topological character of coherent struc- tures in wall-bounded turbulence of polymer additive solu- tion. The fully developed near-wall turbulent flow fields with and without polymer additives at the same Reynolds number were measured by TRPIV in a water channel. The compar- isons of turbulent statistics confirm that due to viscoelastic structure of long-chain polymers, the wall-normal velocity fluctuation and Reynolds shear stress in the near-wall region are suppressed significantly. Furthermore, it is noted that such a behavior of polymers is closely related to the decease of the motion of the second and forth quadrants, i.e., the ejection and sweep events, in the near-wall region. The spa- tial topological mode of coherent structures during bursts has been extracted by the new mu-level criteria based on locally averaged velocity structure function. Although the general shapes of coherent structures are unchanged by polymer additives, the fluctuating velocity, velocity gradient, velocity strain rate and vorticity of coherent structures during burst events are suppressed in the polymer additive solution com- pared with that in water. The results show that due to the polymer additives the occurrence and intensity of coherent structures are suppressed, leading to drag reduction.展开更多
Nature has shown us that the microstructure of the skin of fast-swimming sharks in the ocean can reduce the skin friction drag due to the well-known shark-skin effect.In the present study,the effect of shark-skin-insp...Nature has shown us that the microstructure of the skin of fast-swimming sharks in the ocean can reduce the skin friction drag due to the well-known shark-skin effect.In the present study,the effect of shark-skin-inspired riblets on coherent vortex structures in a turbulent boundary layer（TBL） is investigated.This is done by means of tomographic particle image velocimetry（TPIV） measurements in channel fl ws over an acrylic plate of drag-reducing riblets at a friction Reynolds number of 190.The turbulent fl ws over drag-reducing riblets are verifie by a planar time-resolved particle image velocimetry（TRPIV） system initially,and then the TPIV measurements are performed.Two-dimensional（2D） experimental results with a dragreduction rate of around 4.81% are clearly visible over triangle riblets with a peak-to-peak spacing s＋of 14,indicating from the drag-reducing performance that the buffer layer within the TBL has thickened;the logarithmic law region has shifted upward and the Reynolds shear stress decreased.A comparison of the spatial topological distributions of the spanwise vorticity of coherent vortex structures extracted at different wall-normal heights through the improved quadrant splitting method shows that riblets weaken the amplitudesof the spanwise vorticity when ejection（Q2） and sweep（Q4） events occur at the near wall,having the greatest effect on Q4 events in particular.The so-called quadrupole statistical model for coherent structures in the whole TBL is verified Meanwhile,their spatial conditional-averaged topological shapes and the spatial scales of quadrupole coherent vortex structures as a whole in the overlying turbulent fl w over riblets are changed,suggesting that the riblets dampen the momentum and energy exchange between the regions of near-wall and outer portion of the TBL by depressing the bursting events（Q2 and Q4）,thereby reducing the skin friction drag.展开更多
AIM：To evaluate the peripapillary choroidal thickness（PPCT） in Chinese children,and to analyze the influencing factors.METHODS： PPCT was measured with enhanced depth imaging optical coherence tomography（EDI-OCT）...AIM：To evaluate the peripapillary choroidal thickness（PPCT） in Chinese children,and to analyze the influencing factors.METHODS： PPCT was measured with enhanced depth imaging optical coherence tomography（EDI-OCT） in 70children（53 myopes and 17 non-myopes） aged 7 to 18 y,with spherical equivalent refractive errors between 0.50and-5.87 diopters（D）.Peripapillary choroidal imaging was performed using circular scans of a diameter of 3.4 mm around the optic disc.PPCT was measured by EDI-OCT in six sectors： nasal（N）,superonasal（SN）,superotemporal（ST）,temporal（T）,inferotemporal（IT）and inferonasal（IN）,as well as global RNFL thickness（G）.RESULTS： The mean global PPCT was 165.49±33.76 μm.The temporal,inferonasal,inferotemporal PPCT were significantly thinner than the nasal,superonasal,superotemporal segments PPCT were significantly thinner in the myopic group at temporal,superotemporal and inferotemporal segments.The axial length was significantly associated with the average global（β=-0.419,P =0.014）,superonasal（β=-2.009,P=0.049） and inferonasal（β=-2.000,P=0.049） PPCT.The other factors（gender,age,SE） were not significantly associated with PPCT.CONCLUSION： PPCT was thinner in the myopic group at temporal,superotemporal and inferotemporal segments.The axial length was found to be negatively correlated to PPCT.We need more further studies about the relationship between PPCT and myopia.展开更多
AIM:To characterize spectral-domain optical coherence tomography(SD-OCT)features of chorioretinal folds in orbital mass imaged using enhanced depth imaging(EDI).METHODS:Prospective observational case-control study was...AIM:To characterize spectral-domain optical coherence tomography(SD-OCT)features of chorioretinal folds in orbital mass imaged using enhanced depth imaging(EDI).METHODS:Prospective observational case-control study was conducted in 20 eyes of 20 patients,the uninvolved eye served as a control.All the patients underwent clinical fundus photography,computed tomography,EDI SDOCT imaging before and after surgery.Two patients with cavernous hemangiomas underwent intratumoral injection of bleomycin A5;the remaining patients underwent tumor excision.Patients were followed 1 to 14mo following surgery(average follow up,5.8mo).RESULTS:Visual acuity prior to surgery ranged from 20/20 to 20/200.Following surgery,5 patients’visual acuity remained unchanged while the remaining 15 patients had a mean letter improvement of 10(range 4 to 26 letters).Photoreceptor inner/outer segment defects were found in 10 of 15 patients prior to surgery.Following surgical excision,photoreceptor inner/outer segment defects fully resolved in 8 of these 10 patients.CONCLUSION:Persistence of photoreceptor inner/outer segment defects caused by compression of the globe by an orbital mass can be associated with reduced visual prognosis.Our findings suggest that photoreceptor inner/outer segment defects on EDI SD-OCT could be an indicator for immediate surgical excision of an orbital mass causing choroidal compression.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
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
Accurate characterization of high-power laser parameters,especially the near-field and far-field distributions,is crucial for inertial confinement fusion experiments.In this paper,we propose a method for computational...Accurate characterization of high-power laser parameters,especially the near-field and far-field distributions,is crucial for inertial confinement fusion experiments.In this paper,we propose a method for computationally reconstructing the complex amplitude of high-power laser beams using modified coherent modulation imaging.This method has the advantage of being able to simultaneously calculate both the near-field(intensity and wavefront/phase)and far-field(focal-spot)distributions using the reconstructed complex amplitude.More importantly,the focal-spot distributions at different focal planes can also be calculated.To verify the feasibility,the complex amplitude optical field of the highpower pulsed laser was measured after static aberrations calibration.Experimental results also indicate that the near-field wavefront resolution of this method is higher than that of the Hartmann measurement.In addition,the far-field focal spot exhibits a higher dynamic range(176 dB)than that of traditional direct imaging(62 dB).展开更多
BACKGROUND Optical coherence tomography(OCT)enables high-resolution,non-invasive visualization of retinal structures.Recent evidence suggests that retinal layer alterations may reflect central nervous system changes a...BACKGROUND Optical coherence tomography(OCT)enables high-resolution,non-invasive visualization of retinal structures.Recent evidence suggests that retinal layer alterations may reflect central nervous system changes associated with psychiatric disorders such as schizophrenia(SZ).AIM To develop an advanced deep learning model to classify OCT images and distinguish patients with SZ from healthy controls using retinal biomarkers.METHODS A novel convolutional neural network,Self-AttentionNeXt,was designed by integrating grouped self-attention mechanisms,residual and inverted bottleneck blocks,and a final 1×1 convolution for feature refinement.The model was trained and tested on both a custom OCT dataset collected from patients with SZ and a publicly available OCT dataset(OCT2017).RESULTS Self-AttentionNeXt achieved 97.0%accuracy on the collected SZ OCT dataset and over 95%accuracy on the public OCT2017 dataset.Gradient-weighted class activation mapping visualizations confirmed the model’s attention to clinically relevant retinal regions,suggesting effective feature localization.CONCLUSION Self-AttentionNeXt effectively combines transformer-inspired attention mechanisms with convolutional neural networks architecture to support the early and accurate detection of SZ using OCT images.This approach offers a promising direction for artificial intelligence-assisted psychiatric diagnostics and clinical decision support.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
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
AIM： To predict the visual outcome in patients undergoing macular hole surgery by two novel three-dimensional morphological parameters on optical coherence tomography （OCT）： area ratio factor （ARF） and volume ra...AIM： To predict the visual outcome in patients undergoing macular hole surgery by two novel three-dimensional morphological parameters on optical coherence tomography （OCT）： area ratio factor （ARF） and volume ratio factor （VRF）. METHODS： A clinical case series was conducted, including 54 eyes of 54 patients with an idiopathic macular hole （IMH）. Each patient had an OCT examination before and after surgery. Morphological parameters of the macular hole, such as minimum diameter, base diameter, and height were measured. Then, the macular hole index （Mill）, tractional hole index （THI）, and hole form factor （HFF） were calculated. Meanwhile, novel postoperative macular hole （MH） factors, ARF and VRF were calculated by three-dimensional morphology. Bivariate correlations were performed to acquire asymptotic significance values between the steady best corrected visual acuity （BCVA） after surgery and 2D/3D arguments of MH by the Pearson method with two-tailed test. All significant factors were analyzed by the receiver operating characteristic （ROC） curve analysis of SPSS software which were responsible for vision recovery. ROC curves analyses were performed to further discuss the different parameters on the prediction of visual outcome. RESULTS： The mean and standard deviation values of patients＇ age, symptoms duration, and follow-up time were 64.8＋8.9y （range： 28-81）, 18.6＋11.5d （range： 2-60）, and 11.4＋0.4mo （range： 6-24）, respectively. Steady-post-BCVA analyzed with bivariate correlations was found to be significantly correlated with base diameter （r＇0.521, P〈0.001）, minimum diameter （r=0.514, P〈0.001）, MHI （r -0.531, P〈0.001）, THI （r=-0.386, P=-0.004）, HFF （r=-0.508, P〈0.001）, and ARF （r=-0.532, P〈0.001）. Other characteristic parameters such as age, duration of surgery, height, diameter hole index, and VRF were not statistically significant with steady-post-BCVA. According to area under the curve （AUC） values, values of ARF, MHI, HFF, minimum diameter, THI, and base diameter are 0.806, 0.772, 0.750, 0.705, 0.690, and 0.686, respectively. However, Steady-post-BCVA analysis with bivariate correlations for VRF was no statistical significance. Results of ROC curve analysis indicated that the MHI value, HFF, and ARF was greater than 0.427, 1.027 and 1.558 respectively which could correlate with better visual acuity. CONCLUSION： Compared with MHI and HFF, ARF could effectively express three-dimensional characteristics of macular hole and achieve better sensitivity and specificity. Thus, ARF could be the most effective parameter to predict the visual outcome in macular hole surgery.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
基金supported by the National Natural Science Foundation of China(Grant Nos.61827901,61991451,62131003)the BIT Research and Innovation Promoting Project(Grant No.2022YCXZ006).
文摘Large-scale computational imaging can provide remarkable space-bandwidth product that is beyond the limit of optical systems.In coherent imaging(CI),the joint reconstruction of amplitude and phase further expands the information throughput and sheds light on label-free observation of biological samples at micro-or even nano-levels.The existing large-scale CI techniques usually require scanning/modulation multiple times to guarantee measurement diversity and long exposure time to achieve a high signal-to-noise ratio.Such cumbersome procedures restrict clinical applications for rapid and lowphototoxicity cell imaging.In this work,a complex-domain-enhancing neural network for large-scale CI termed CI-CDNet is proposed for various large-scale CI modalities with satisfactory reconstruction quality and efficiency.CI-CDNet is able to exploit the latent coupling information between amplitude and phase(such as their same features),realizing multidimensional representations of the complex wavefront.The cross-field characterization framework empowers strong generalization and robustness for various coherent modalities,allowing high-quality and efficient imaging under extremely low exposure time and few data volume.We apply CI-CDNet in various large-scale CI modalities including Kramers–Kronigrelations holography,Fourier ptychographic microscopy,and lensless coded ptychography.A series of simulations and experiments validate that CI-CDNet can reduce exposure time and data volume by more than 1 order of magnitude.We further demonstrate that the high-quality reconstruction of CI-CDNet benefits the subsequent high-level semantic analysis.
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 the National Natural Science Foundation of China under Grant Nos 11174019,61322509 and 11121091the National Basic Research Program of China under Grant No 2013CB921904
文摘We propose and implement a wide-field vibrational phase contrast detection to obtain imaging of imaginary components of third-order nonlinear susceptibility in a coherent anti-Stokes Raman scattering （CARS） microscope with full suppression of the non-resonant background. This technique is based on the unique ability of recovering the phase of the generated CARS signal based on holographic recording. By capturing the phase distributions of the generated CARS field from the sample and from the environment under resonant illumination, we demonstrate the retrieval of imaginary components in the CARS microscope and achieve background free coherent Raman imaging.
基金supported by the National Natural Science Foundation of China(Grant No.61505248)the Fund from Chinese Academy of Sciences,the Light of"Western"Talent Cultivation Plan"Dr.Western Fund Project"(Grant No.Y429621213)
文摘Return signal processing and reconstruction plays a pivotal role in coherent field imaging, having a significant in- fluence on the quality of the reconstructed image. To reduce the required samples and accelerate the sampling process, we propose a genuine sparse reconstruction scheme based on compressed sensing theory. By analyzing the sparsity of the received signal in the Fourier spectrum domain, we accomplish an effective random projection and then reconstruct the return signal from as little as 10% of traditional samples, finally acquiring the target image precisely. The results of the numerical simulations and practical experiments verify the correctness of the proposed method, providing an efficient processing approach for imaging fast-moving targets in the future.
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.
文摘AIM:To evaluate the choroidopathy in patients with systemic lupus erythematosus(SLE)using enhanced depth imaging spectral domain optical coherence tomography(EDI SD-OCT)and optical coherence tomography angiography(OCTA).METHODS:A total of 74 patients with SLE and 40 healthy volunteers were included in this cross-sectional study.SLE patients were further divided into three subgroups based on clinical and blood biochemistry findings.Ocular parameters obtained on ophthalmologic examination and optical imaging(EDI SD-OCT and OCTA)included the best corrected distance visual acuity(logMAR CDVA),subfoveal choroidal thickness(SCT),choroidal vascularity index(CVI)and vessel density(VD)of superficial capillary plexus(SCP)and deep capillary plexus(DCP).RESULTS:SLE patients had significantly lower values for CVI and VD of DCP(DVD)than control subjects.Amongst SLE patients,gender and chloroquine dose were found to be independent determinants of CVI while age predicted SCT.Steroid dose was a significant predictor for foveal VD of SCP(SVD),chloroquine dose for parafoveal SVD,gender for total DVD,and gender and steroid dose for perifoveal DVD.No correlation of logMAR CDVA and SCT was noted between SLE patients and control subjects.No correlation of SCT was noted with disease duration,Systemic Lupus Erythematosus Disease Activity Index(SLEDAI)score,hydroxychloroquine(HCQ)dose or steroid dose.No correlation of CVI was noted with patient age,disease duration,SLEDAI score,HCQ dose or steroid dose.No significant difference was noted between SLE subgroups in terms of any of the ocular parameters studied.CONCLUSION:The findings reveal the presence of ocular findings suggestive of early onset choroidopathy on EDI SD-OCT and OCTA in SLE patients,in the absence of ocular manifestations or active disease.
基金Supported by Wenzhou Municipal Science and Technology Bureau(No.Y20150257)
文摘AIM：To assess peripapillary retinal nerve fiber layer（RNFL）and choroidal thickness obtained with enhanced depth imaging（EDI）mode compared with those obtained without EDI mode using Heidelberg Spectralis optical coherence tomography（OCT）.METHODS：Fifty eyes of 25 normal healthy subjects and32 eyes of 20 patients with different eye diseases were included in the study.All subjects underwent 3.4 mm diameter peripapillary circular OCT scan centered on the optic disc using both the conventional and the EDI OCT protocols.The visualization of RNFL and choroidoscleral junction was assessed using an ordinal scoring scale.The paired t-test,intraclass correlation coefficient（ICC）,95%limits of agreement（LoA）,and Bland and Altman plots were used to test the agreement of measurements.RESULTS：The visibility score of RNFL obtained with and without EDI was of no significant difference（P=0.532）,the visualization of choroidoscleral junction was better using EDI protocol than conventional protocol（P〈0.001）.Peripapillary RNFL thickness obtained with EDI was slightly thicker than that obtained without EDI（103.25±9.42μm vs 101.87±8.78μm,P=0.010）.The ICC of the two protocols was excellent with the value of 0.867 to 0.924,the 95%LoA of global RNFL thickness was between-10.0 to 7.4μm.Peripapillary choroidal thickness obtained with EDI was slightly thinner than that obtained without EDI（147.23±51.04μm vs 150.90±51.84μm,P〈0.001）.The ICC was also excellent with the value of 0.960 to 0.987,the 95%LoA of global choroidal thickness was between-12.5 to 19.8μm.CONCLUSION：Peripapillary circular OCT scan with or without EDI mode shows comparable results in the measurement of peripapillary RNFL and choroidal thickness.
基金supported by the National Natural Science Foundation of China(11272233)National Key Basic Research and Development Program(2012CB720101)2012 opening subjects of The State Key Laboratory of Nonlinear Mechanics(LNM),Institute of Mechanics,Chinese Academy of Sciences
文摘An experimental measurement was performed us- ing time-resolved particle image velocimetry （TRPIV） to in- vestigate the spatial topological character of coherent struc- tures in wall-bounded turbulence of polymer additive solu- tion. The fully developed near-wall turbulent flow fields with and without polymer additives at the same Reynolds number were measured by TRPIV in a water channel. The compar- isons of turbulent statistics confirm that due to viscoelastic structure of long-chain polymers, the wall-normal velocity fluctuation and Reynolds shear stress in the near-wall region are suppressed significantly. Furthermore, it is noted that such a behavior of polymers is closely related to the decease of the motion of the second and forth quadrants, i.e., the ejection and sweep events, in the near-wall region. The spa- tial topological mode of coherent structures during bursts has been extracted by the new mu-level criteria based on locally averaged velocity structure function. Although the general shapes of coherent structures are unchanged by polymer additives, the fluctuating velocity, velocity gradient, velocity strain rate and vorticity of coherent structures during burst events are suppressed in the polymer additive solution com- pared with that in water. The results show that due to the polymer additives the occurrence and intensity of coherent structures are suppressed, leading to drag reduction.
基金supported by the National Natural Science Foundation of China (Grants 11332006,11272233,and 11411130150)the foundation from the China Scholarship Council (CSC) (Grant 201306250092)the Foundation Project for Outstanding Doctoral Dissertations of Tianjin University
文摘Nature has shown us that the microstructure of the skin of fast-swimming sharks in the ocean can reduce the skin friction drag due to the well-known shark-skin effect.In the present study,the effect of shark-skin-inspired riblets on coherent vortex structures in a turbulent boundary layer（TBL） is investigated.This is done by means of tomographic particle image velocimetry（TPIV） measurements in channel fl ws over an acrylic plate of drag-reducing riblets at a friction Reynolds number of 190.The turbulent fl ws over drag-reducing riblets are verifie by a planar time-resolved particle image velocimetry（TRPIV） system initially,and then the TPIV measurements are performed.Two-dimensional（2D） experimental results with a dragreduction rate of around 4.81% are clearly visible over triangle riblets with a peak-to-peak spacing s＋of 14,indicating from the drag-reducing performance that the buffer layer within the TBL has thickened;the logarithmic law region has shifted upward and the Reynolds shear stress decreased.A comparison of the spatial topological distributions of the spanwise vorticity of coherent vortex structures extracted at different wall-normal heights through the improved quadrant splitting method shows that riblets weaken the amplitudesof the spanwise vorticity when ejection（Q2） and sweep（Q4） events occur at the near wall,having the greatest effect on Q4 events in particular.The so-called quadrupole statistical model for coherent structures in the whole TBL is verified Meanwhile,their spatial conditional-averaged topological shapes and the spatial scales of quadrupole coherent vortex structures as a whole in the overlying turbulent fl w over riblets are changed,suggesting that the riblets dampen the momentum and energy exchange between the regions of near-wall and outer portion of the TBL by depressing the bursting events（Q2 and Q4）,thereby reducing the skin friction drag.
基金Supported by Major Scientific and Technological Projects in Zhejiang Province,China(No.2013c03048-3)the Science and Technology Plan Project of Wenzhou Science and Technology Bureau(No.Y20150284)Medical Scientific Research Foundation of Zhejiang Province(No.2016ZDA016)
文摘AIM：To evaluate the peripapillary choroidal thickness（PPCT） in Chinese children,and to analyze the influencing factors.METHODS： PPCT was measured with enhanced depth imaging optical coherence tomography（EDI-OCT） in 70children（53 myopes and 17 non-myopes） aged 7 to 18 y,with spherical equivalent refractive errors between 0.50and-5.87 diopters（D）.Peripapillary choroidal imaging was performed using circular scans of a diameter of 3.4 mm around the optic disc.PPCT was measured by EDI-OCT in six sectors： nasal（N）,superonasal（SN）,superotemporal（ST）,temporal（T）,inferotemporal（IT）and inferonasal（IN）,as well as global RNFL thickness（G）.RESULTS： The mean global PPCT was 165.49±33.76 μm.The temporal,inferonasal,inferotemporal PPCT were significantly thinner than the nasal,superonasal,superotemporal segments PPCT were significantly thinner in the myopic group at temporal,superotemporal and inferotemporal segments.The axial length was significantly associated with the average global（β=-0.419,P =0.014）,superonasal（β=-2.009,P=0.049） and inferonasal（β=-2.000,P=0.049） PPCT.The other factors（gender,age,SE） were not significantly associated with PPCT.CONCLUSION： PPCT was thinner in the myopic group at temporal,superotemporal and inferotemporal segments.The axial length was found to be negatively correlated to PPCT.We need more further studies about the relationship between PPCT and myopia.
基金Supported by National Natural Science Foundation of China(No.81300805)。
文摘AIM:To characterize spectral-domain optical coherence tomography(SD-OCT)features of chorioretinal folds in orbital mass imaged using enhanced depth imaging(EDI).METHODS:Prospective observational case-control study was conducted in 20 eyes of 20 patients,the uninvolved eye served as a control.All the patients underwent clinical fundus photography,computed tomography,EDI SDOCT imaging before and after surgery.Two patients with cavernous hemangiomas underwent intratumoral injection of bleomycin A5;the remaining patients underwent tumor excision.Patients were followed 1 to 14mo following surgery(average follow up,5.8mo).RESULTS:Visual acuity prior to surgery ranged from 20/20 to 20/200.Following surgery,5 patients’visual acuity remained unchanged while the remaining 15 patients had a mean letter improvement of 10(range 4 to 26 letters).Photoreceptor inner/outer segment defects were found in 10 of 15 patients prior to surgery.Following surgical excision,photoreceptor inner/outer segment defects fully resolved in 8 of these 10 patients.CONCLUSION:Persistence of photoreceptor inner/outer segment defects caused by compression of the globe by an orbital mass can be associated with reduced visual prognosis.Our findings suggest that photoreceptor inner/outer segment defects on EDI SD-OCT could be an indicator for immediate surgical excision of an orbital mass causing choroidal compression.
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supported by the Project of the Ministry of Industry and Information Technology(Grant No.TC220H05L)the National Natural Science Foundation of China(NSFC)(Grant Nos.61905261,61827816 and 11875308)+1 种基金the Shanghai Sailing Program(Grant No.18YF1426600)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA25020306).
文摘Accurate characterization of high-power laser parameters,especially the near-field and far-field distributions,is crucial for inertial confinement fusion experiments.In this paper,we propose a method for computationally reconstructing the complex amplitude of high-power laser beams using modified coherent modulation imaging.This method has the advantage of being able to simultaneously calculate both the near-field(intensity and wavefront/phase)and far-field(focal-spot)distributions using the reconstructed complex amplitude.More importantly,the focal-spot distributions at different focal planes can also be calculated.To verify the feasibility,the complex amplitude optical field of the highpower pulsed laser was measured after static aberrations calibration.Experimental results also indicate that the near-field wavefront resolution of this method is higher than that of the Hartmann measurement.In addition,the far-field focal spot exhibits a higher dynamic range(176 dB)than that of traditional direct imaging(62 dB).
文摘BACKGROUND Optical coherence tomography(OCT)enables high-resolution,non-invasive visualization of retinal structures.Recent evidence suggests that retinal layer alterations may reflect central nervous system changes associated with psychiatric disorders such as schizophrenia(SZ).AIM To develop an advanced deep learning model to classify OCT images and distinguish patients with SZ from healthy controls using retinal biomarkers.METHODS A novel convolutional neural network,Self-AttentionNeXt,was designed by integrating grouped self-attention mechanisms,residual and inverted bottleneck blocks,and a final 1×1 convolution for feature refinement.The model was trained and tested on both a custom OCT dataset collected from patients with SZ and a publicly available OCT dataset(OCT2017).RESULTS Self-AttentionNeXt achieved 97.0%accuracy on the collected SZ OCT dataset and over 95%accuracy on the public OCT2017 dataset.Gradient-weighted class activation mapping visualizations confirmed the model’s attention to clinically relevant retinal regions,suggesting effective feature localization.CONCLUSION Self-AttentionNeXt effectively combines transformer-inspired attention mechanisms with convolutional neural networks architecture to support the early and accurate detection of SZ using OCT images.This approach offers a promising direction for artificial intelligence-assisted psychiatric diagnostics and clinical decision support.
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 National Natural Science Foundation of China(No.61675124No.81501559)+1 种基金Natural Science Foundation of the Higher Education Institutions of Jiangsu Province,China(No.15KJB310015)Science and Technology Foundation of Nantong Technology Bureau(No.MS12015180)
文摘AIM： To predict the visual outcome in patients undergoing macular hole surgery by two novel three-dimensional morphological parameters on optical coherence tomography （OCT）： area ratio factor （ARF） and volume ratio factor （VRF）. METHODS： A clinical case series was conducted, including 54 eyes of 54 patients with an idiopathic macular hole （IMH）. Each patient had an OCT examination before and after surgery. Morphological parameters of the macular hole, such as minimum diameter, base diameter, and height were measured. Then, the macular hole index （Mill）, tractional hole index （THI）, and hole form factor （HFF） were calculated. Meanwhile, novel postoperative macular hole （MH） factors, ARF and VRF were calculated by three-dimensional morphology. Bivariate correlations were performed to acquire asymptotic significance values between the steady best corrected visual acuity （BCVA） after surgery and 2D/3D arguments of MH by the Pearson method with two-tailed test. All significant factors were analyzed by the receiver operating characteristic （ROC） curve analysis of SPSS software which were responsible for vision recovery. ROC curves analyses were performed to further discuss the different parameters on the prediction of visual outcome. RESULTS： The mean and standard deviation values of patients＇ age, symptoms duration, and follow-up time were 64.8＋8.9y （range： 28-81）, 18.6＋11.5d （range： 2-60）, and 11.4＋0.4mo （range： 6-24）, respectively. Steady-post-BCVA analyzed with bivariate correlations was found to be significantly correlated with base diameter （r＇0.521, P〈0.001）, minimum diameter （r=0.514, P〈0.001）, MHI （r -0.531, P〈0.001）, THI （r=-0.386, P=-0.004）, HFF （r=-0.508, P〈0.001）, and ARF （r=-0.532, P〈0.001）. Other characteristic parameters such as age, duration of surgery, height, diameter hole index, and VRF were not statistically significant with steady-post-BCVA. According to area under the curve （AUC） values, values of ARF, MHI, HFF, minimum diameter, THI, and base diameter are 0.806, 0.772, 0.750, 0.705, 0.690, and 0.686, respectively. However, Steady-post-BCVA analysis with bivariate correlations for VRF was no statistical significance. Results of ROC curve analysis indicated that the MHI value, HFF, and ARF was greater than 0.427, 1.027 and 1.558 respectively which could correlate with better visual acuity. CONCLUSION： Compared with MHI and HFF, ARF could effectively express three-dimensional characteristics of macular hole and achieve better sensitivity and specificity. Thus, ARF could be the most effective parameter to predict the visual outcome in macular hole surgery.
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.
