This paper studies the correlation properties of the speckles in the deep Fresnel diffraction region produced by the scattering of rough self-affine fractal surfaces. The autocorrelation function of the speckle intens...This paper studies the correlation properties of the speckles in the deep Fresnel diffraction region produced by the scattering of rough self-affine fractal surfaces. The autocorrelation function of the speckle intensities is formulated by the combination of the light scattering theory of Kirchhoff approximation and the principles of speckle statistics. We propose a method for extracting the three surface parameters, i.e. the roughness w, the lateral correlation length ξ and the roughness exponent α, from the autocorrelation functions of speckles. This method is verified by simulating the speckle intensities and calculating the speckle autocorrelation function. We also find the phenomenon that for rough surfaces with α= 1, the structure of the speckles resembles that of the surface heights, which results from the effect of the peak and the valley parts of the surface, acting as micro-lenses converging and diverging the light waves.展开更多
Heterogeneous nuclear ribonucleoproteins（hn RNPs） belong to the RNA-binding proteins family. They are involved in processing heterogeneous nuclear RNAs（hn RNAs） into mature m RNAs. These proteins participate in ev...Heterogeneous nuclear ribonucleoproteins（hn RNPs） belong to the RNA-binding proteins family. They are involved in processing heterogeneous nuclear RNAs（hn RNAs） into mature m RNAs. These proteins participate in every step of m RNA cycle, such as m RNA export, localization, translation, stability and alternative splicing. At least 14 major hn RNPs, which have structural and functional homologues in mammals, are expressed in Drosophila melanogaster. Until now, six of these hn RNPs are known to be nucleus-localized and associated with the long non-coding RNA（lnc RNA） heat shock responsive u（hsru）in the omega speckle compartments（u-speckles）. The chromatin remodeler ISWI is the catalytic subunit of several ATP-dependent chromatin-remodeling complexes, and it is an essential factor for organization of u-speckles. Indeed, in ISWI null mutant, severe defects in u-speckles structure are detectable. Here, we clarify the role of ISWI in the hn RNPs-hsru interaction. Moreover, we describe how ISWI by its remodeling activity, controls hsru and hn RNPs engagement in u-speckles. Finally, we demonstrate that the sequestration of hn RNPs in u-speckles nuclear compartment is a fundamental event in gene expression control and represents a key step in the regulation of several pathways.展开更多
An optical encryption scheme based on a ghost imaging system with disordered speckles is proposed to obtain a higher security with a small key. In the scheme, Alice produces the random speckle patterns and obtains the...An optical encryption scheme based on a ghost imaging system with disordered speckles is proposed to obtain a higher security with a small key. In the scheme, Alice produces the random speckle patterns and obtains the detection results with the help of a computational ghost imaging（CGI） system. Then Alice permutes the order of the random speckle patterns and shares the permutation sequence as a secure key to the authorized users. With the secure key, Bob could recover the object with the principle of the CGI system, whereas, the unauthorized users could not obtain any information of the object. The numerical simulations and experimental results show that the proposed scheme is feasible with a small key, simultaneously,it has a higher security. When the eavesdropping ratio（ER） is less than 40%, the eavesdropper cannot acquire any useful information. Meanwhile, the authorized users could recover completely with the secure key.展开更多
With a microscopic imaging system composed of microscopic objective,lens and CCD,we observe the complicated structures in the speckle fields on the surface of a rough screen.It is found that such structures contain ri...With a microscopic imaging system composed of microscopic objective,lens and CCD,we observe the complicated structures in the speckle fields on the surface of a rough screen.It is found that such structures contain ridge stripes,large platform-like grains,and shivy grains,exhibiting multiple scales in size and multiple fractalities.Simulations shows these structures are formed by different parts of the rough surface.The experimental curve of the autocorrelation function of the speckle intensity includes the three parts of the central peak,the transition part and the long tail part.Using the sum of self-affine fractal models with different scales and fractalities,we propose theoretically a triple-scale autocorrelation function to describe the speckle field.Fit of this autocorrelation function to the experimental curve gives the values of such parameters as average speckle sizes and fractalities in different scales of the speckle structures.展开更多
Based on the Kirchhoff approximation and the theoretical analysis of the random light fields, the speckle intensity distributions in the extremely deep Fresnel diffraction region are simulated. The fractal property of...Based on the Kirchhoff approximation and the theoretical analysis of the random light fields, the speckle intensity distributions in the extremely deep Fresnel diffraction region are simulated. The fractal property of the speckles as well as the relation between the speckle intensity distribution and the corresponding random surface is investigated. We design a microscope system to detect experimentally the speckles in the extremely deep Fresnel diffraction region, and the experimental results prove the conclusions drawn from our simulations.展开更多
A new mechanism for the generation of high intensity speckles by coupling of overlapping beams is discovered and studied in detail.Using three-dimensional simulations,the coupling of overlapping beams smoothed by phas...A new mechanism for the generation of high intensity speckles by coupling of overlapping beams is discovered and studied in detail.Using three-dimensional simulations,the coupling of overlapping beams smoothed by phase plates and by polarization smoothing are investigated in the regime relevant to inertial confinement fusion studies.It is found that the intensity distribution of the laser beam spot can be changed by nonuniform spatial phase modulation,and the speckles formed by the phase plate can be split into smaller speckles with higher intensities,which is favorable for the generation of laser plasma instabilities.Stimulated Brillouin scattering is compared in simulations with and without coupling of the overlapping incident beams,and the results confirm the enhancement of stimulated Brillouin scattering due to this mechanism.展开更多
Acetone is a widely used volatile organic compound in various industries,and several gas sensors have been developed for its detection and real-time monitoring.This study reported a novel method for determining the ac...Acetone is a widely used volatile organic compound in various industries,and several gas sensors have been developed for its detection and real-time monitoring.This study reported a novel method for determining the acetone vapor concentration based on correlated laser speckles using polymer-dispersed liquid crystals(PDLCs).Here,PDLC films comprising a mixture of the thermotropic nematic liquid crystal(LC)and ultraviolet-curable polymers were fabricated using different LC mass ratios and ultraviolet curing conditions.The laser beam was transmitted through the PDLC film to generate scattered light and speckles.When the PDLC film was exposed to the acetone vapor,the acetone molecules diffused into the PDLC film and interacted with the LC molecules,modifying the orientation of the LC molecules and the equivalent refractive index of the LC droplets.This in turn decreased the correlation coefficient of the speckle images.The experimental results indicated that the PDLC gas sensor was selectively sensitive to different concentrations of the acetone vapor,ranging from 1800 ppm to 3200 ppm.In comparison with traditional LC gas sensors that use a polarizing microscope to detect the change in brightness of the modulated light field,the proposed method is simpler,less expensive,and more robust under external disturbances such as vibrations.展开更多
The first- and second-order statistical properties of ultrasound -speckles reflected from an interface are studied theoretically and experimentally. A theoretical model for predicting statistical properties of ultraso...The first- and second-order statistical properties of ultrasound -speckles reflected from an interface are studied theoretically and experimentally. A theoretical model for predicting statistical properties of ultrasound speckles is constructed based on the Fresnel-Huygens principle and three basic assumptions. Distributions of amplitude and phase of ultrasound speckles in a scattering space are studied. And the study shows that they are in the form of Rayleigh and uniform distribution respectively. Using the proposed model, the average transverse size of the speckles within a scattering domain which are received by a focus probe is investigated. The average transverse size is found to be dependent on the characteristics of the measuring system only, and does not vary with the position in the domain. To verify the applicability of the theoretical model, a special experimental set-up was designed and the corresponding experiments were conducted for measuring the sound pressure of the ultrasound speckles reflected from an interface between water and Aluminium alloy. The numerical results are compared with the experimental ones. The comparison demonstrates that the theoretical model and the three related assumptions are suitable for analysing statistical properties of ultrasound speckles reflected from an interface.展开更多
Information retrieval from visually random optical speckle patterns is desired in many scenarios yet considered challenging.It requires accurate understanding or mapping of the multiple scattering process,or reliable ...Information retrieval from visually random optical speckle patterns is desired in many scenarios yet considered challenging.It requires accurate understanding or mapping of the multiple scattering process,or reliable capability to reverse or compensate for the scattering-induced phase distortions.In whatever situation,effective resolving and digitization of speckle patterns are necessary.Nevertheless,on some occasions,to increase the acquisition speed and/or signal-to-noise ratio(SNR),speckles captured by cameras are inevitably sampled in the sub-Nyquist domain via pixel binning(one camera pixel contains multiple speckle grains)due to finite size or limited bandwidth of photosensors.Such a down-sampling process is irreversible;it undermines the fine structures of speckle grains and hence the encoded information,preventing successful information extraction.To retrace the lost information,super-resolution interpolation for such sub-Nyquist sampled speckles is needed.In this work,a deep neural network,namely SpkSRNet,is proposed to effectively up sample speckles that are sampled below 1/10 of the Nyquist criterion to well-resolved ones that not only resemble the comprehensive morphology of original speckles(decompose multiple speckle grains from one camera pixel)but also recover the lost complex information(human face in this study)with high fidelity under normal-and low-light conditions,which is impossible with classic interpolation methods.These successful speckle super-resolution interpolation demonstrations are essentially enabled by the strong implicit correlation among speckle grains,which is non-quantifiable but could be discovered by the well-trained network.With further engineering,the proposed learning platform may benefit many scenarios that are physically inaccessible,enabling fast acquisition of speckles with sufficient SNR and opening up new avenues for seeing big and seeing clearly simultaneously in complex scenarios.展开更多
From Helmholtz equation of the harmonic electromagnetic waves, the integral equations of the light field at the medium boundaries are obtained by use of the Green's theorem and are discretized into linear equation...From Helmholtz equation of the harmonic electromagnetic waves, the integral equations of the light field at the medium boundaries are obtained by use of the Green's theorem and are discretized into linear equation set with the values of the light field and its derivative as the unknowns. On solving the linear equation set, we realize the rigorous computations of the light fields at the boundaries. Then the intensities of the light waves scattered by the random self-affine fractal surfaces in the optical near-field are calculated, and the propagation characteristics, the evolutions of the contrast and the intensity probability density function of the near-field speckles are studied in detail. The near-field speckles are much different from the conventional speckles in the diffraction regions and in the imaging systems. There are obvious local fluctuations in the intensity distributions of the near-field speckles and such fluctuations disappear after propagating a distance of one wavelength from the medium surfaces. For the random surfaces with smaller lateral correlation lengths, the speckle contrasts approach the saturation values and the speckle fields approach Gaussian distribution within the near-field, while for the random surfaces with larger lateral correlation lengths, such evolutions become comparatively slow.展开更多
Imaging through scattering medium is challenging but important for different applications.Most advances rely on computational image reconstruction from scattering signals.In these conventional investigations,speckles ...Imaging through scattering medium is challenging but important for different applications.Most advances rely on computational image reconstruction from scattering signals.In these conventional investigations,speckles were always treated as scrambled grainy patterns.Directly seeing through scattering diffusers has never been realized.Here,we report a new strategy to see through random diffusers directly using self-imaging of speckles.By analyzing the physics,a direct observation strategy through scattering media is reported with improved image quality.Using this method,we experimentally demonstrated reconstruction-free real-time imaging of static and moving objects with their actual orientation information under single-wavelength and white light illumination.We also proposed a modified speckle autocorrelation imaging(SAI)method inspired by the self-imaging results.Importantly,our strategy requires no pre-calibration or acquisition of point-spread-function,no active control of wavefronts or complicated equipment,nor iterations or carefully adjusted parameters,paving the way towards rapid and high-quality imaging through scattering diffusers.展开更多
Histological changes that occur during microsporogenesis are documented in a gene-cytoplasmic male sterile rice ( Oryza saliva L.) line, Zhen Shan 97A, its maintainer line, Zhen Shan 97B, and the restorer line, Ce64 o...Histological changes that occur during microsporogenesis are documented in a gene-cytoplasmic male sterile rice ( Oryza saliva L.) line, Zhen Shan 97A, its maintainer line, Zhen Shan 97B, and the restorer line, Ce64 of a Mine hybrid rice production system. In the restorer line, Ce64, the developing microsporocytes have dense cytoplasm and a distinct set of circumferential microtubules around the nucleus. Successive cytokinesis results in the formation of tetrads. The microtubules within the cells of tetrads and microspores radiate from the surface of the nucleus towards the outer edge of the cytoplasm. Subsequent pollen development is normal. During the course of microspore formation tubulin speckles can be found in the cytoplasm. The general pattern of development and microtubule organization in the maintainer lined Zhen Shan 97B, is similar to Ce64, except that a few more tubulin speckles appear during microspore formation. In the case of the mate sterile line, Zhen Shan 97A, a number of abnormalities can be discerned during early microsporogenesis. These include vacuoles forming within the developing microsporocyte and faintly stained microtubules with no defined distribution pattern. Prominent tubulin speckles are common within the cytoplasm. For those microsporocytes that undergo meiosis, no defined organizational patterns of microtubules can be found within the tetrad. All microspores abort soon after. Abnormalities and defects in microtubule organization observed in Zhen Shan 97A showed that complex interactions between the cytoplasm and the nucleus began at very early stage of microsporocyte development.展开更多
Meiotic resumption in mammalian oocytes involves nuclear and organelle structural changes,notably the chromatin configuration transition from a non-surrounding nucleolus(NSN)to surrounding nucleolus(SN)in germinal ves...Meiotic resumption in mammalian oocytes involves nuclear and organelle structural changes,notably the chromatin configuration transition from a non-surrounding nucleolus(NSN)to surrounding nucleolus(SN)in germinal vesicle oocytes.In the current study,we found that nuclear speckles(NSs),a subnuclear structure mainly composed of serine-arginine(SR)proteins,changed from a diffuse spotted distribution in mouse NSN oocytes to an aggregated pattern in SN oocytes.We also found that the SR protein-specific kinase 1(SRPK1),an enzyme that phosphorylates SR proteins,co-localized with NSs at the SN stage,and that NSN oocytes failed to transition to SN oocytes after the inhibition of SRPK1 activity.Furthermore,the typical structure of the chromatin ring around the nucleolus in SN oocytes collapsed after treatment with an SRPK1 inhibitor.Mechanistically,phosphorylated SR proteins were found to be related to chromatin as shown by a salt extraction experiment,and in situ DNaseⅠassay showed that the accessibility of chromatin was enhanced in SN oocytes when SRPK1 was inhibited,accompanied by a decreased repressive modification on histone and the abnormal recurrence of a transcriptional signal.In conclusion,our results indicated that SRPK1-regulated phosphorylation of SR proteins was involved in the NSN-SN transition and played an important role in maintaining the condensed nucleus of SN oocytes via interacting with chromatin.展开更多
The high temporal and spatial coherence of free electron lasers(FELs)reduces the uniformity of the illumination field,leading to scattering effects that blur the edges of patterns,resulting in diminished accuracy and ...The high temporal and spatial coherence of free electron lasers(FELs)reduces the uniformity of the illumination field,leading to scattering effects that blur the edges of patterns,resulting in diminished accuracy and clarity.Traditional imaging models regard the light source as fully incoherent,making it difficult to assess the impact of partially coherent light fields on imaging.If FELs are used in imaging systems,their coherence must be considered.To address this issue,this study explores the relationship between coherence,imaging quality and speckle contrast through a simulation method based on random phases.The method divides the light beam into temporal and spatial coherence cells,analyzes their interactions,and simulates imaging results under different coherence conditions.Additionally,speckle patterns for various illumination modes are calculated to evaluate their effects on speckle contrast and illumination uniformity.The results indicate that under different illumination modes,illumination uniformity decreases as coherence increases,while speckle contrast increases with higher coherence.In terms of imaging quality,higher coherence leads to an increase in both line edge roughness(LER)and line width roughness(LWR),thereby reducing the imaging quality.Additionally,the narrower the line width,the greater the impact of coherence on the imaging quality,resulting in poorer imaging performance.展开更多
Microcirculation imaging is crucial in understanding the function and health of various tissues and organs.However,conventional imaging methods suffer from fluorescence label dependency,lack of depth resolution,and qu...Microcirculation imaging is crucial in understanding the function and health of various tissues and organs.However,conventional imaging methods suffer from fluorescence label dependency,lack of depth resolution,and quantification inaccuracy.Here,we report a light-sheet dynamic light-scattering imaging(LSHDSI)system to overcome these shortcomings.LSH-DSI utilizes selected plane illumination for an optical sectioning,while a time-frequency analysis method retrieves blood flow velocity estimates from dynamic changes in the detected light intensity.We have performed imaging experiments with zebrafish embryos to obtain angiographs from the trunk and head regions.The results show that LSH-DSI can capture label-free tomographic images of microvasculature and three-dimensional quantitative maps of local blood flow velocities.展开更多
Structured illumination,a wide-field imaging approach used in microscopy to enhance image resolution beyond the system's diffraction limits,is a well-studied technique that has gained significant traction over the...Structured illumination,a wide-field imaging approach used in microscopy to enhance image resolution beyond the system's diffraction limits,is a well-studied technique that has gained significant traction over the last two decades.However,when translated to endoscopic systems,severe deformations of illumination patterns occur due to the large depth of field(DOF)and the 3D nature of the targets,introducing significant implementation challenges.Hence,this study explores a speckle-based system that best suits endoscopic practices to enhance image resolution by using random illumination patterns.The study presents a prototypic model of an endoscopic add-on,its design,and fabrication facilitated by using the speckle structured illumination endoscopic(SSIE)system.The imaging results of the SSIE are explained on a colon phantom model at different imaging planes with a wide field of view(FOV)and DOF.The obtained imaging metrics are elucidated and compared with state-of-the-art(SOA)high-resolution endoscopic techniques.Moreover,the potential for a clinical translation of the prototypic SSIE model is also explored in this work.The incorporation of the add-on and its subsequent results on the colon phantom model could potentially pave the way for its successful integration and use in futuristic clinical endoscopic trials.展开更多
Laser speckle contrast imaging(LSCI)is a noninvasive,label-free technique that allows real-time investigation of the microcirculation situation of biological tissue.High-quality microvascular segmentation is critical ...Laser speckle contrast imaging(LSCI)is a noninvasive,label-free technique that allows real-time investigation of the microcirculation situation of biological tissue.High-quality microvascular segmentation is critical for analyzing and evaluating vascular morphology and blood flow dynamics.However,achieving high-quality vessel segmentation has always been a challenge due to the cost and complexity of label data acquisition and the irregular vascular morphology.In addition,supervised learning methods heavily rely on high-quality labels for accurate segmentation results,which often necessitate extensive labeling efforts.Here,we propose a novel approach LSWDP for high-performance real-time vessel segmentation that utilizes low-quality pseudo-labels for nonmatched training without relying on a substantial number of intricate labels and image pairing.Furthermore,we demonstrate that our method is more robust and effective in mitigating performance degradation than traditional segmentation approaches on diverse style data sets,even when confronted with unfamiliar data.Importantly,the dice similarity coefficient exceeded 85%in a rat experiment.Our study has the potential to efficiently segment and evaluate blood vessels in both normal and disease situations.This would greatly benefit future research in life and medicine.展开更多
基金Project supported by the National Natural Science Foundation of China （Grant No 69978012）, and by the National Key Basic Research Special Foundation （NKBRSF） of China （Grant No G1999075200）.
文摘This paper studies the correlation properties of the speckles in the deep Fresnel diffraction region produced by the scattering of rough self-affine fractal surfaces. The autocorrelation function of the speckle intensities is formulated by the combination of the light scattering theory of Kirchhoff approximation and the principles of speckle statistics. We propose a method for extracting the three surface parameters, i.e. the roughness w, the lateral correlation length ξ and the roughness exponent α, from the autocorrelation functions of speckles. This method is verified by simulating the speckle intensities and calculating the speckle autocorrelation function. We also find the phenomenon that for rough surfaces with α= 1, the structure of the speckles resembles that of the surface heights, which results from the effect of the peak and the valley parts of the surface, acting as micro-lenses converging and diverging the light waves.
基金supported by an Associazione Italiana Ricerca sul Cancro (AIRC) (MFAG-12779) fellowshipsupported by My First Airc Grant (MFAG) number 12779 from AIRC to M.C.O
文摘Heterogeneous nuclear ribonucleoproteins（hn RNPs） belong to the RNA-binding proteins family. They are involved in processing heterogeneous nuclear RNAs（hn RNAs） into mature m RNAs. These proteins participate in every step of m RNA cycle, such as m RNA export, localization, translation, stability and alternative splicing. At least 14 major hn RNPs, which have structural and functional homologues in mammals, are expressed in Drosophila melanogaster. Until now, six of these hn RNPs are known to be nucleus-localized and associated with the long non-coding RNA（lnc RNA） heat shock responsive u（hsru）in the omega speckle compartments（u-speckles）. The chromatin remodeler ISWI is the catalytic subunit of several ATP-dependent chromatin-remodeling complexes, and it is an essential factor for organization of u-speckles. Indeed, in ISWI null mutant, severe defects in u-speckles structure are detectable. Here, we clarify the role of ISWI in the hn RNPs-hsru interaction. Moreover, we describe how ISWI by its remodeling activity, controls hsru and hn RNPs engagement in u-speckles. Finally, we demonstrate that the sequestration of hn RNPs in u-speckles nuclear compartment is a fundamental event in gene expression control and represents a key step in the regulation of several pathways.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61475075 and 61271238)the Open Research Fund of Key Lab of Broadband Wireless Communication and Sensor Network Technology,Ministry of Education,China(Grant No.NYKL2015011)
文摘An optical encryption scheme based on a ghost imaging system with disordered speckles is proposed to obtain a higher security with a small key. In the scheme, Alice produces the random speckle patterns and obtains the detection results with the help of a computational ghost imaging（CGI） system. Then Alice permutes the order of the random speckle patterns and shares the permutation sequence as a secure key to the authorized users. With the secure key, Bob could recover the object with the principle of the CGI system, whereas, the unauthorized users could not obtain any information of the object. The numerical simulations and experimental results show that the proposed scheme is feasible with a small key, simultaneously,it has a higher security. When the eavesdropping ratio（ER） is less than 40%, the eavesdropper cannot acquire any useful information. Meanwhile, the authorized users could recover completely with the secure key.
基金the National Natural Science Foundation of China under Grant Nos 10974122 and 10874105.
文摘With a microscopic imaging system composed of microscopic objective,lens and CCD,we observe the complicated structures in the speckle fields on the surface of a rough screen.It is found that such structures contain ridge stripes,large platform-like grains,and shivy grains,exhibiting multiple scales in size and multiple fractalities.Simulations shows these structures are formed by different parts of the rough surface.The experimental curve of the autocorrelation function of the speckle intensity includes the three parts of the central peak,the transition part and the long tail part.Using the sum of self-affine fractal models with different scales and fractalities,we propose theoretically a triple-scale autocorrelation function to describe the speckle field.Fit of this autocorrelation function to the experimental curve gives the values of such parameters as average speckle sizes and fractalities in different scales of the speckle structures.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.10974122 and 10874105)the Science and Technology Research Project of Shandong Province of China(Grant No.2009GG10001005)+1 种基金the Shandong Distinguished Middleaged and Young Scientist Encourage and Reward Foundation,China(Grant Nos.2007BS04031 and BS2009SF020)the State Key Development Program for Basic Research of China(Grant No.2006CB806003)
文摘Based on the Kirchhoff approximation and the theoretical analysis of the random light fields, the speckle intensity distributions in the extremely deep Fresnel diffraction region are simulated. The fractal property of the speckles as well as the relation between the speckle intensity distribution and the corresponding random surface is investigated. We design a microscope system to detect experimentally the speckles in the extremely deep Fresnel diffraction region, and the experimental results prove the conclusions drawn from our simulations.
基金supported by the National Natural Sci-ence Foundation of China(Grant Nos.12275032,12035002,and 12205021)the Project supported by CAEP Foundation(Grant No.CX20210040).
文摘A new mechanism for the generation of high intensity speckles by coupling of overlapping beams is discovered and studied in detail.Using three-dimensional simulations,the coupling of overlapping beams smoothed by phase plates and by polarization smoothing are investigated in the regime relevant to inertial confinement fusion studies.It is found that the intensity distribution of the laser beam spot can be changed by nonuniform spatial phase modulation,and the speckles formed by the phase plate can be split into smaller speckles with higher intensities,which is favorable for the generation of laser plasma instabilities.Stimulated Brillouin scattering is compared in simulations with and without coupling of the overlapping incident beams,and the results confirm the enhancement of stimulated Brillouin scattering due to this mechanism.
基金supported by the Key Research and Development Program of Shanxi Province,China(Grant No.202102030201002)the Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China(Grant No.IRT_17R70)+2 种基金the State Key Program of National Natural Science of China(Grant No.11434007)the 111 Project,China(Grant No.D18001)the Fund for Shanxi“1331 Project”Key Subjects Construction,China.
文摘Acetone is a widely used volatile organic compound in various industries,and several gas sensors have been developed for its detection and real-time monitoring.This study reported a novel method for determining the acetone vapor concentration based on correlated laser speckles using polymer-dispersed liquid crystals(PDLCs).Here,PDLC films comprising a mixture of the thermotropic nematic liquid crystal(LC)and ultraviolet-curable polymers were fabricated using different LC mass ratios and ultraviolet curing conditions.The laser beam was transmitted through the PDLC film to generate scattered light and speckles.When the PDLC film was exposed to the acetone vapor,the acetone molecules diffused into the PDLC film and interacted with the LC molecules,modifying the orientation of the LC molecules and the equivalent refractive index of the LC droplets.This in turn decreased the correlation coefficient of the speckle images.The experimental results indicated that the PDLC gas sensor was selectively sensitive to different concentrations of the acetone vapor,ranging from 1800 ppm to 3200 ppm.In comparison with traditional LC gas sensors that use a polarizing microscope to detect the change in brightness of the modulated light field,the proposed method is simpler,less expensive,and more robust under external disturbances such as vibrations.
基金This work was supported by the National Natural Science Foundation of China (10074017).
文摘The first- and second-order statistical properties of ultrasound -speckles reflected from an interface are studied theoretically and experimentally. A theoretical model for predicting statistical properties of ultrasound speckles is constructed based on the Fresnel-Huygens principle and three basic assumptions. Distributions of amplitude and phase of ultrasound speckles in a scattering space are studied. And the study shows that they are in the form of Rayleigh and uniform distribution respectively. Using the proposed model, the average transverse size of the speckles within a scattering domain which are received by a focus probe is investigated. The average transverse size is found to be dependent on the characteristics of the measuring system only, and does not vary with the position in the domain. To verify the applicability of the theoretical model, a special experimental set-up was designed and the corresponding experiments were conducted for measuring the sound pressure of the ultrasound speckles reflected from an interface between water and Aluminium alloy. The numerical results are compared with the experimental ones. The comparison demonstrates that the theoretical model and the three related assumptions are suitable for analysing statistical properties of ultrasound speckles reflected from an interface.
基金Agency for Science,Technology and Research(A18A7b0058)Innovation and Technology Commission(GHP/043/19SZ,GHP/044/19GD)+2 种基金Hong Kong Research Grant Council(15217721,C5078-21EF,R5029-19)Guangdong Science and Technology Department(2019A1515011374,2019BT02X105)National Natural Science Foundation of China(81627805,81930048)。
文摘Information retrieval from visually random optical speckle patterns is desired in many scenarios yet considered challenging.It requires accurate understanding or mapping of the multiple scattering process,or reliable capability to reverse or compensate for the scattering-induced phase distortions.In whatever situation,effective resolving and digitization of speckle patterns are necessary.Nevertheless,on some occasions,to increase the acquisition speed and/or signal-to-noise ratio(SNR),speckles captured by cameras are inevitably sampled in the sub-Nyquist domain via pixel binning(one camera pixel contains multiple speckle grains)due to finite size or limited bandwidth of photosensors.Such a down-sampling process is irreversible;it undermines the fine structures of speckle grains and hence the encoded information,preventing successful information extraction.To retrace the lost information,super-resolution interpolation for such sub-Nyquist sampled speckles is needed.In this work,a deep neural network,namely SpkSRNet,is proposed to effectively up sample speckles that are sampled below 1/10 of the Nyquist criterion to well-resolved ones that not only resemble the comprehensive morphology of original speckles(decompose multiple speckle grains from one camera pixel)but also recover the lost complex information(human face in this study)with high fidelity under normal-and low-light conditions,which is impossible with classic interpolation methods.These successful speckle super-resolution interpolation demonstrations are essentially enabled by the strong implicit correlation among speckle grains,which is non-quantifiable but could be discovered by the well-trained network.With further engineering,the proposed learning platform may benefit many scenarios that are physically inaccessible,enabling fast acquisition of speckles with sufficient SNR and opening up new avenues for seeing big and seeing clearly simultaneously in complex scenarios.
基金sponsored by the National Natural Science Foundation of China(Grant No.69978012)by the National Key Basic Research Special Foundation(NKBRSF)of China(Grant No.G1999075200).
文摘From Helmholtz equation of the harmonic electromagnetic waves, the integral equations of the light field at the medium boundaries are obtained by use of the Green's theorem and are discretized into linear equation set with the values of the light field and its derivative as the unknowns. On solving the linear equation set, we realize the rigorous computations of the light fields at the boundaries. Then the intensities of the light waves scattered by the random self-affine fractal surfaces in the optical near-field are calculated, and the propagation characteristics, the evolutions of the contrast and the intensity probability density function of the near-field speckles are studied in detail. The near-field speckles are much different from the conventional speckles in the diffraction regions and in the imaging systems. There are obvious local fluctuations in the intensity distributions of the near-field speckles and such fluctuations disappear after propagating a distance of one wavelength from the medium surfaces. For the random surfaces with smaller lateral correlation lengths, the speckle contrasts approach the saturation values and the speckle fields approach Gaussian distribution within the near-field, while for the random surfaces with larger lateral correlation lengths, such evolutions become comparatively slow.
文摘Imaging through scattering medium is challenging but important for different applications.Most advances rely on computational image reconstruction from scattering signals.In these conventional investigations,speckles were always treated as scrambled grainy patterns.Directly seeing through scattering diffusers has never been realized.Here,we report a new strategy to see through random diffusers directly using self-imaging of speckles.By analyzing the physics,a direct observation strategy through scattering media is reported with improved image quality.Using this method,we experimentally demonstrated reconstruction-free real-time imaging of static and moving objects with their actual orientation information under single-wavelength and white light illumination.We also proposed a modified speckle autocorrelation imaging(SAI)method inspired by the self-imaging results.Importantly,our strategy requires no pre-calibration or acquisition of point-spread-function,no active control of wavefronts or complicated equipment,nor iterations or carefully adjusted parameters,paving the way towards rapid and high-quality imaging through scattering diffusers.
文摘Histological changes that occur during microsporogenesis are documented in a gene-cytoplasmic male sterile rice ( Oryza saliva L.) line, Zhen Shan 97A, its maintainer line, Zhen Shan 97B, and the restorer line, Ce64 of a Mine hybrid rice production system. In the restorer line, Ce64, the developing microsporocytes have dense cytoplasm and a distinct set of circumferential microtubules around the nucleus. Successive cytokinesis results in the formation of tetrads. The microtubules within the cells of tetrads and microspores radiate from the surface of the nucleus towards the outer edge of the cytoplasm. Subsequent pollen development is normal. During the course of microspore formation tubulin speckles can be found in the cytoplasm. The general pattern of development and microtubule organization in the maintainer lined Zhen Shan 97B, is similar to Ce64, except that a few more tubulin speckles appear during microspore formation. In the case of the mate sterile line, Zhen Shan 97A, a number of abnormalities can be discerned during early microsporogenesis. These include vacuoles forming within the developing microsporocyte and faintly stained microtubules with no defined distribution pattern. Prominent tubulin speckles are common within the cytoplasm. For those microsporocytes that undergo meiosis, no defined organizational patterns of microtubules can be found within the tetrad. All microspores abort soon after. Abnormalities and defects in microtubule organization observed in Zhen Shan 97A showed that complex interactions between the cytoplasm and the nucleus began at very early stage of microsporocyte development.
基金National Natural Science Foundation of China(Grant Nos.32070838 and 82301874)Open Fund of State Key Laboratory of Reproductive Medicine,Nanjing Medical University(Grant No.SKLRM K202102)。
文摘Meiotic resumption in mammalian oocytes involves nuclear and organelle structural changes,notably the chromatin configuration transition from a non-surrounding nucleolus(NSN)to surrounding nucleolus(SN)in germinal vesicle oocytes.In the current study,we found that nuclear speckles(NSs),a subnuclear structure mainly composed of serine-arginine(SR)proteins,changed from a diffuse spotted distribution in mouse NSN oocytes to an aggregated pattern in SN oocytes.We also found that the SR protein-specific kinase 1(SRPK1),an enzyme that phosphorylates SR proteins,co-localized with NSs at the SN stage,and that NSN oocytes failed to transition to SN oocytes after the inhibition of SRPK1 activity.Furthermore,the typical structure of the chromatin ring around the nucleolus in SN oocytes collapsed after treatment with an SRPK1 inhibitor.Mechanistically,phosphorylated SR proteins were found to be related to chromatin as shown by a salt extraction experiment,and in situ DNaseⅠassay showed that the accessibility of chromatin was enhanced in SN oocytes when SRPK1 was inhibited,accompanied by a decreased repressive modification on histone and the abnormal recurrence of a transcriptional signal.In conclusion,our results indicated that SRPK1-regulated phosphorylation of SR proteins was involved in the NSN-SN transition and played an important role in maintaining the condensed nucleus of SN oocytes via interacting with chromatin.
文摘The high temporal and spatial coherence of free electron lasers(FELs)reduces the uniformity of the illumination field,leading to scattering effects that blur the edges of patterns,resulting in diminished accuracy and clarity.Traditional imaging models regard the light source as fully incoherent,making it difficult to assess the impact of partially coherent light fields on imaging.If FELs are used in imaging systems,their coherence must be considered.To address this issue,this study explores the relationship between coherence,imaging quality and speckle contrast through a simulation method based on random phases.The method divides the light beam into temporal and spatial coherence cells,analyzes their interactions,and simulates imaging results under different coherence conditions.Additionally,speckle patterns for various illumination modes are calculated to evaluate their effects on speckle contrast and illumination uniformity.The results indicate that under different illumination modes,illumination uniformity decreases as coherence increases,while speckle contrast increases with higher coherence.In terms of imaging quality,higher coherence leads to an increase in both line edge roughness(LER)and line width roughness(LWR),thereby reducing the imaging quality.Additionally,the narrower the line width,the greater the impact of coherence on the imaging quality,resulting in poorer imaging performance.
基金supported by the following funding sources:Ministry of Education-Singapore MOE2019-T2-2-094 Ministry of Education-Singapore Tier I R-397-000-327-114 ScienceTechnology Project of Jiangsu Province(Grant No.BZ2022056)Biomedical and Health Technology Platform,National University of Singapore(Suzhou)Research Institute.
文摘Microcirculation imaging is crucial in understanding the function and health of various tissues and organs.However,conventional imaging methods suffer from fluorescence label dependency,lack of depth resolution,and quantification inaccuracy.Here,we report a light-sheet dynamic light-scattering imaging(LSHDSI)system to overcome these shortcomings.LSH-DSI utilizes selected plane illumination for an optical sectioning,while a time-frequency analysis method retrieves blood flow velocity estimates from dynamic changes in the detected light intensity.We have performed imaging experiments with zebrafish embryos to obtain angiographs from the trunk and head regions.The results show that LSH-DSI can capture label-free tomographic images of microvasculature and three-dimensional quantitative maps of local blood flow velocities.
文摘Structured illumination,a wide-field imaging approach used in microscopy to enhance image resolution beyond the system's diffraction limits,is a well-studied technique that has gained significant traction over the last two decades.However,when translated to endoscopic systems,severe deformations of illumination patterns occur due to the large depth of field(DOF)and the 3D nature of the targets,introducing significant implementation challenges.Hence,this study explores a speckle-based system that best suits endoscopic practices to enhance image resolution by using random illumination patterns.The study presents a prototypic model of an endoscopic add-on,its design,and fabrication facilitated by using the speckle structured illumination endoscopic(SSIE)system.The imaging results of the SSIE are explained on a colon phantom model at different imaging planes with a wide field of view(FOV)and DOF.The obtained imaging metrics are elucidated and compared with state-of-the-art(SOA)high-resolution endoscopic techniques.Moreover,the potential for a clinical translation of the prototypic SSIE model is also explored in this work.The incorporation of the add-on and its subsequent results on the colon phantom model could potentially pave the way for its successful integration and use in futuristic clinical endoscopic trials.
基金supported by grants fromthe State Key Laboratory of Vaccines for Infectious Diseases,Xiang An Biomedicine Laboratory(2023XAKJ0101031)National Natural Science Foundation of China(81971665)+8 种基金Natural Science Foundation of Fujian Province(2021J011366)Medical and Health Guidance Project of Xiamen(3502Z20214ZD1016)Xiamen Health High-Level Talent Training Program,Ningxia Hui Autonomous Region Key Research and Development Program(2022BEG03127)Fundamental Research Funds for the Central Universities of China(20720210117)Fujian Province Science and Technology Plan Guiding Project(2022Y0002)National Natural Science Foundation of China(62005048)Natural Science Foundation of Fujian Province(2020J01158)Ministry of Education Industry-university Cooperative Education Project(220606053295218)XMU Undergraduate Innovation and Entrepreneurship Training Programs(2023X805,2023X808,2023Y1109).
文摘Laser speckle contrast imaging(LSCI)is a noninvasive,label-free technique that allows real-time investigation of the microcirculation situation of biological tissue.High-quality microvascular segmentation is critical for analyzing and evaluating vascular morphology and blood flow dynamics.However,achieving high-quality vessel segmentation has always been a challenge due to the cost and complexity of label data acquisition and the irregular vascular morphology.In addition,supervised learning methods heavily rely on high-quality labels for accurate segmentation results,which often necessitate extensive labeling efforts.Here,we propose a novel approach LSWDP for high-performance real-time vessel segmentation that utilizes low-quality pseudo-labels for nonmatched training without relying on a substantial number of intricate labels and image pairing.Furthermore,we demonstrate that our method is more robust and effective in mitigating performance degradation than traditional segmentation approaches on diverse style data sets,even when confronted with unfamiliar data.Importantly,the dice similarity coefficient exceeded 85%in a rat experiment.Our study has the potential to efficiently segment and evaluate blood vessels in both normal and disease situations.This would greatly benefit future research in life and medicine.
