To the Editor:Gastroscopy is considered to be the main method for diagnosing gastric lesions.[1]But correctly diagnosing different gastric lesions under white light endoscopy(WLE)may be challenging as the morphologica...To the Editor:Gastroscopy is considered to be the main method for diagnosing gastric lesions.[1]But correctly diagnosing different gastric lesions under white light endoscopy(WLE)may be challenging as the morphological manifestations of gastric lesions are varied and some are even subtle.Due to the uneven diagnostic levels across various regions and the scarcity of experienced endoscopists,misdiagnosis and missed diagnosis may occur.In addition,endoscopists are overwhelmed by heavy workloads,and fatigue may lead to a further decline in diagnostic performance,even for experienced endoscopists.展开更多
Fiber-based endoscopes are promising for minimally invasive in vivo biomedical diagnostics.Multicore fibers offer high resolution imaging.However,to avoid image deterioration induced by inter-core coupling,significant...Fiber-based endoscopes are promising for minimally invasive in vivo biomedical diagnostics.Multicore fibers offer high resolution imaging.However,to avoid image deterioration induced by inter-core coupling,significant spacing between cores is required,which limits the active image guiding area of the fiber.Thus,they suffer from low light collection efficiency and decreased signal-to-noise ratio.In this paper,we present a method to increase the collection efficiency by thermally expanding the cores at the facet of a multicore fiber.This expansion is based on the diffusion of doping material of the cores,thus the fiber’s original outer diameter is preserved.By enlarging the core diameter by a factor of 2.8,we increase the intensity of the transmitted light by a factor of up to 2.3.This results in a signal-to-noise ratio increase by a factor of up to 4.6 and significant improvement in the image contrast.The improvement increases with increasing working distance but is already prominent for as small working distance as 0.5 mm.The feasibility of the method is proved experimentally by lensless single-shot imaging of a test chart and incoherent light reflected from clusters of microbeads.The demonstrated approach is an important tool especially in imaging of biological specimens,for which phototoxicity must be avoided,and therefore,high collection efficiency is required.展开更多
This paper presents a lumped particle model for simulating a large number of particles.The lumped particle model is a flexible framework in modeling particle flows,embodying fundamental features that are intrinsic in ...This paper presents a lumped particle model for simulating a large number of particles.The lumped particle model is a flexible framework in modeling particle flows,embodying fundamental features that are intrinsic in particle laden flow,including advection,diffusion and dispersion.In this paper,the particles obey a simplified version of the Bassinet-Boussinesq-Oseen equation for a single spherical particle.However,instead of tracking the individual dynamics of each particle,a weighted spatial averaging procedure is used where the external forces are applied to a“lump”of particles,from which an average position and velocity is derived.The temporal evolution of the particles is computed by partitioning the lumped particle into smaller entities,which are then transported throughout the physical domain.These smaller entities recombine into new particle lumps at their target destinations.For particles prone to the effects of Brownian motion or similar phenomena,a symmetric spreading of the particles is included as well.Numerical experiments show that the lumped particle model reproduces the effects of Brownian diffusion and uniform particle transport by a fluid and gravity.The late time scale diffusive nature of particle motion is also reproduced.展开更多
Minimally invasive endoscopy offers a high potential for biomedical imaging applications.However,conventional fiberoptic endoscopes require lens systems which are not suitable for real-time 3D imaging.Instead,a diffus...Minimally invasive endoscopy offers a high potential for biomedical imaging applications.However,conventional fiberoptic endoscopes require lens systems which are not suitable for real-time 3D imaging.Instead,a diffuser is utilized for passively encoding incoherent 3D objects into 2D speckle patterns.Neural networks are employed for fast computational image reconstruction beyond the optical memory effect.In this paper,we demonstrate single-shot 3D incoherent fiber imaging with keyhole access at video rate.Applying the diffuser fiber endoscope for fluorescence imaging is promising for in vivo deep brain diagnostics with cellular resolution.展开更多
Lensless fiber endomicroscopy,an emergent paradigm shift for minimally-invasive microscopic optical imaging and targeted light delivery,holds transformative potential,especially in biomedicine.Leveraging holographic d...Lensless fiber endomicroscopy,an emergent paradigm shift for minimally-invasive microscopic optical imaging and targeted light delivery,holds transformative potential,especially in biomedicine.Leveraging holographic detection and physical or computational wavefront correction,it enables three-dimensional imaging in an unprecedentedly small footprint,which is crucial for various applications such as brain surgery.This perspective reviews the recent breakthroughs,highlighting potential emerging applications,and pinpointing gaps between innovation and real-world applications.As the research in this realm accelerates,the novel breakthroughs and existing frontiers highlighted in this perspective can be used as guidelines for researchers joining this exciting domain.展开更多
Quantitative phase imaging(QPI)is a label-free technique providing both morphology and quantitative biophysical information in biomedicine.However,applying such a powerful technique to in vivo pathological diagnosis r...Quantitative phase imaging(QPI)is a label-free technique providing both morphology and quantitative biophysical information in biomedicine.However,applying such a powerful technique to in vivo pathological diagnosis remains challenging.Multi-core fiber bundles(MCFs)enable ultra-thin probes for in vivo imaging,but current MCF imaging techniques are limited to amplitude imaging modalities.We demonstrate a computational lensless microendoscope that uses an ultra-thin bare MCF to perform quantitative phase imaging with microscale lateral resolution and nanoscale axial sensitivity of the optical path length.The incident complex light field at the measurement side is precisely reconstructed from the far-field speckle pattern at the detection side,enabling digital refocusing in a multi-layer sample without any mechanical movement.The accuracy of the quantitative phase reconstruction is validated by imaging the phase target and hydrogel beads through the MCF.With the proposed imaging modality,three-dimensional imaging of human cancer cells is achieved through the ultra-thin fiber endoscope,promising widespread clinical applications.展开更多
Minimally invasive endoscopes are indispensable in biomedicine.Coherent fiber bundles(CFBs)enable ultrathin lensless endoscopes.However,the propagation of light through a CFB suffers from phase distortions and aberrat...Minimally invasive endoscopes are indispensable in biomedicine.Coherent fiber bundles(CFBs)enable ultrathin lensless endoscopes.However,the propagation of light through a CFB suffers from phase distortions and aberrations that can cause images to be scrambled.The correction of such aberrations has been demonstrated using various techniques for wavefront control,especially using spatial light modulators(SLMs).This study investigates a novel aberration correction without SLM for the creation of an efficient and compact system.The memory effect of CFBs enables a paradigm shift in the use of static diffractive optical elements(DOEs)instead of dynamic modulation with SLM.We introduce DOEs produced by 2-photon polymerization lithography for phase conjugation on a CFB for focusing,raster scanning,and imaging.Furthermore,a DOE with random patterns is used to encode the three-dimensional(3D)object information in a 2D speckle pattern that propagates along the ultra-thin CFB.Neural networks decode the speckles to retrieve the 3D object information using single-shot imaging.Both DOE methods have compact low-cost concepts in common,and both pave the way for minimally invasive 3D endomicroscopy with benefits for optical imaging in biomedicine.展开更多
Quantitative phase imaging (QPI) has emerged as method for investigating biological specimen and technical objects. However, conventional methods often suffer from shortcomings in image quality, such as the twin image...Quantitative phase imaging (QPI) has emerged as method for investigating biological specimen and technical objects. However, conventional methods often suffer from shortcomings in image quality, such as the twin image artifact. A novel computational framework for QPI is presented with high quality inline holographic imaging from a single intensity image. This paradigm shift is promising for advanced QPI of cells and tissues.展开更多
This paper presents an extension of the lumped particle model in[1]to include the effects of particle collisions.The lumped particle model is a flexible framework for the modeling of particle laden flows,that takes in...This paper presents an extension of the lumped particle model in[1]to include the effects of particle collisions.The lumped particle model is a flexible framework for the modeling of particle laden flows,that takes into account fundamental features,including advection,diffusion and dispersion of the particles.In this paper,we transform a binary collision model and concepts from kinetic theory into a collision procedure for the lumped particle framework.We apply this new collision procedure to investigate numerically the role of particle collisions in the hindered settling effect.The hindered settling effect is characterized by an increase in the effective drag coefficient CD that influences each particle in the flow.This coefficient is given by CD=(1−φ)−nC∗D,whereφis the volume fraction of particles,C∗D is the drag coefficient for a single particle,and n≃4.67 for creeping flow.We obtain an approximation for CD/C∗D by calculating the effective work done by collisions,and comparing that to the work done by the drag force.In our numerical experiments,we observe a minimal value of n=3.0.Moreover,by allowing high energy dissipation,an approximation for the classical value for creeping flow,n=4.7,is reproduced.We also obtain high values for n,up to n=6.5,which is consistent with recent physical experiments on the sedimentation of sand grains.展开更多
First introduced in[2],the lumped particle framework is a flexible and numerically efficient framework for the modelling of particle transport in fluid flow.In this paper,the framework is expanded to simulate multicom...First introduced in[2],the lumped particle framework is a flexible and numerically efficient framework for the modelling of particle transport in fluid flow.In this paper,the framework is expanded to simulate multicomponent particle-laden fluid flow.This is accomplished by introducing simulation protocols tomodel particles over a wide range of length and time scales.Consequently,we present a time ordering scheme and an approximate approach for accelerating the computation of evolution of different particle constituents with large differences in physical scales.We apply the extended framework on the temporal evolution of three particle constituents in sandladen flow,and horizontal release of spherical particles.Furthermore,we evaluate the numerical error of the lumped particle model.In this context,we discuss the Velocity-Verlet numerical scheme,and show how to apply this to solving Newton’s equations within the framework.We show that the increased accuracy of the Velocity-Verlet scheme is not lost when applied to the lumped particle framework.展开更多
基金supported by grants from 1·3·5 project for Artificial Intelligence,West China Hospital,Sichuan University(No.ZYAI24006)Cadres Health Research Project of Sichuan Province(No.ZH2024-102)+2 种基金National Natural Science Foundation of China(No.62376169)National Natural Science Foundation of China(No.62406205)National Natural Science Foundation of China(No.62206093).
文摘To the Editor:Gastroscopy is considered to be the main method for diagnosing gastric lesions.[1]But correctly diagnosing different gastric lesions under white light endoscopy(WLE)may be challenging as the morphological manifestations of gastric lesions are varied and some are even subtle.Due to the uneven diagnostic levels across various regions and the scarcity of experienced endoscopists,misdiagnosis and missed diagnosis may occur.In addition,endoscopists are overwhelmed by heavy workloads,and fatigue may lead to a further decline in diagnostic performance,even for experienced endoscopists.
基金Funded by Deutsche Forschungsgemeinschaft(Grant No.DFG Cz 55/47-1)European Regional Development Fund(100689045)+1 种基金Arbeitsgemeinschaft industrielle Gemeinschaftsforschung(Grant No.21802)Saxonian Government.
文摘Fiber-based endoscopes are promising for minimally invasive in vivo biomedical diagnostics.Multicore fibers offer high resolution imaging.However,to avoid image deterioration induced by inter-core coupling,significant spacing between cores is required,which limits the active image guiding area of the fiber.Thus,they suffer from low light collection efficiency and decreased signal-to-noise ratio.In this paper,we present a method to increase the collection efficiency by thermally expanding the cores at the facet of a multicore fiber.This expansion is based on the diffusion of doping material of the cores,thus the fiber’s original outer diameter is preserved.By enlarging the core diameter by a factor of 2.8,we increase the intensity of the transmitted light by a factor of up to 2.3.This results in a signal-to-noise ratio increase by a factor of up to 4.6 and significant improvement in the image contrast.The improvement increases with increasing working distance but is already prominent for as small working distance as 0.5 mm.The feasibility of the method is proved experimentally by lensless single-shot imaging of a test chart and incoherent light reflected from clusters of microbeads.The demonstrated approach is an important tool especially in imaging of biological specimens,for which phototoxicity must be avoided,and therefore,high collection efficiency is required.
文摘This paper presents a lumped particle model for simulating a large number of particles.The lumped particle model is a flexible framework in modeling particle flows,embodying fundamental features that are intrinsic in particle laden flow,including advection,diffusion and dispersion.In this paper,the particles obey a simplified version of the Bassinet-Boussinesq-Oseen equation for a single spherical particle.However,instead of tracking the individual dynamics of each particle,a weighted spatial averaging procedure is used where the external forces are applied to a“lump”of particles,from which an average position and velocity is derived.The temporal evolution of the particles is computed by partitioning the lumped particle into smaller entities,which are then transported throughout the physical domain.These smaller entities recombine into new particle lumps at their target destinations.For particles prone to the effects of Brownian motion or similar phenomena,a symmetric spreading of the particles is included as well.Numerical experiments show that the lumped particle model reproduces the effects of Brownian diffusion and uniform particle transport by a fluid and gravity.The late time scale diffusive nature of particle motion is also reproduced.
基金supported by the German Research Foundation(DFG)under grant(CZ 55/48-1).
文摘Minimally invasive endoscopy offers a high potential for biomedical imaging applications.However,conventional fiberoptic endoscopes require lens systems which are not suitable for real-time 3D imaging.Instead,a diffuser is utilized for passively encoding incoherent 3D objects into 2D speckle patterns.Neural networks are employed for fast computational image reconstruction beyond the optical memory effect.In this paper,we demonstrate single-shot 3D incoherent fiber imaging with keyhole access at video rate.Applying the diffuser fiber endoscope for fluorescence imaging is promising for in vivo deep brain diagnostics with cellular resolution.
基金organized by Projekt DEAL.German Research Foundation(DFG)grant CZ55/40,CZ55/47European Research Council(ERC)Horizon 2020 research and innovation program(grant no.101002406)+1 种基金Shanghai Artificial Intelligence Laboratory,National Key R&D Program of China(2022ZD0160100)Else Kroner Fresenius Center for digital Heath(EKFZ)and Competence Center for Biomedical Computational Laser Systems(BIOLAS).
文摘Lensless fiber endomicroscopy,an emergent paradigm shift for minimally-invasive microscopic optical imaging and targeted light delivery,holds transformative potential,especially in biomedicine.Leveraging holographic detection and physical or computational wavefront correction,it enables three-dimensional imaging in an unprecedentedly small footprint,which is crucial for various applications such as brain surgery.This perspective reviews the recent breakthroughs,highlighting potential emerging applications,and pinpointing gaps between innovation and real-world applications.As the research in this realm accelerates,the novel breakthroughs and existing frontiers highlighted in this perspective can be used as guidelines for researchers joining this exciting domain.
基金Deutsche Forschungsgemeinschaft(DFG)grant CZ55/40-1Tsinghua Scholarship for Overseas Graduate Studies grant 2020023+1 种基金European Union’s Horizon 2020 research and innovation programs No.953121(project FLAMIN-GO)Open Access funding enabled and organized by Projekt DEAL。
文摘Quantitative phase imaging(QPI)is a label-free technique providing both morphology and quantitative biophysical information in biomedicine.However,applying such a powerful technique to in vivo pathological diagnosis remains challenging.Multi-core fiber bundles(MCFs)enable ultra-thin probes for in vivo imaging,but current MCF imaging techniques are limited to amplitude imaging modalities.We demonstrate a computational lensless microendoscope that uses an ultra-thin bare MCF to perform quantitative phase imaging with microscale lateral resolution and nanoscale axial sensitivity of the optical path length.The incident complex light field at the measurement side is precisely reconstructed from the far-field speckle pattern at the detection side,enabling digital refocusing in a multi-layer sample without any mechanical movement.The accuracy of the quantitative phase reconstruction is validated by imaging the phase target and hydrogel beads through the MCF.With the proposed imaging modality,three-dimensional imaging of human cancer cells is achieved through the ultra-thin fiber endoscope,promising widespread clinical applications.
基金This work was supported by the German Research Foundation(DFG)under grants(CZ 55/47-1)and(CZ 55/48-1).
文摘Minimally invasive endoscopes are indispensable in biomedicine.Coherent fiber bundles(CFBs)enable ultrathin lensless endoscopes.However,the propagation of light through a CFB suffers from phase distortions and aberrations that can cause images to be scrambled.The correction of such aberrations has been demonstrated using various techniques for wavefront control,especially using spatial light modulators(SLMs).This study investigates a novel aberration correction without SLM for the creation of an efficient and compact system.The memory effect of CFBs enables a paradigm shift in the use of static diffractive optical elements(DOEs)instead of dynamic modulation with SLM.We introduce DOEs produced by 2-photon polymerization lithography for phase conjugation on a CFB for focusing,raster scanning,and imaging.Furthermore,a DOE with random patterns is used to encode the three-dimensional(3D)object information in a 2D speckle pattern that propagates along the ultra-thin CFB.Neural networks decode the speckles to retrieve the 3D object information using single-shot imaging.Both DOE methods have compact low-cost concepts in common,and both pave the way for minimally invasive 3D endomicroscopy with benefits for optical imaging in biomedicine.
文摘Quantitative phase imaging (QPI) has emerged as method for investigating biological specimen and technical objects. However, conventional methods often suffer from shortcomings in image quality, such as the twin image artifact. A novel computational framework for QPI is presented with high quality inline holographic imaging from a single intensity image. This paradigm shift is promising for advanced QPI of cells and tissues.
文摘This paper presents an extension of the lumped particle model in[1]to include the effects of particle collisions.The lumped particle model is a flexible framework for the modeling of particle laden flows,that takes into account fundamental features,including advection,diffusion and dispersion of the particles.In this paper,we transform a binary collision model and concepts from kinetic theory into a collision procedure for the lumped particle framework.We apply this new collision procedure to investigate numerically the role of particle collisions in the hindered settling effect.The hindered settling effect is characterized by an increase in the effective drag coefficient CD that influences each particle in the flow.This coefficient is given by CD=(1−φ)−nC∗D,whereφis the volume fraction of particles,C∗D is the drag coefficient for a single particle,and n≃4.67 for creeping flow.We obtain an approximation for CD/C∗D by calculating the effective work done by collisions,and comparing that to the work done by the drag force.In our numerical experiments,we observe a minimal value of n=3.0.Moreover,by allowing high energy dissipation,an approximation for the classical value for creeping flow,n=4.7,is reproduced.We also obtain high values for n,up to n=6.5,which is consistent with recent physical experiments on the sedimentation of sand grains.
基金The presented work was funded by a research grant from Statoil.
文摘First introduced in[2],the lumped particle framework is a flexible and numerically efficient framework for the modelling of particle transport in fluid flow.In this paper,the framework is expanded to simulate multicomponent particle-laden fluid flow.This is accomplished by introducing simulation protocols tomodel particles over a wide range of length and time scales.Consequently,we present a time ordering scheme and an approximate approach for accelerating the computation of evolution of different particle constituents with large differences in physical scales.We apply the extended framework on the temporal evolution of three particle constituents in sandladen flow,and horizontal release of spherical particles.Furthermore,we evaluate the numerical error of the lumped particle model.In this context,we discuss the Velocity-Verlet numerical scheme,and show how to apply this to solving Newton’s equations within the framework.We show that the increased accuracy of the Velocity-Verlet scheme is not lost when applied to the lumped particle framework.
