Objective To investigate a new class of solutions to the isotropic/homogeneous scalar wave equation, which termed limited diffraction beams and realize ultrasonic 3D imaging. Methods Limited diffraction beams were d...Objective To investigate a new class of solutions to the isotropic/homogeneous scalar wave equation, which termed limited diffraction beams and realize ultrasonic 3D imaging. Methods Limited diffraction beams were derived. We performed the study of 3D pulse echo imaging with limited diffraction array beam. To obtain high frame rate images, a single plane wave pulse (broadband) was transmitted with the arrays. Echoes received with the same arrays were processed with Fourier method to construct 3D images. Results Compared with traditional pulse echo imaging, this method has a larger depth of field, high frame rate, and high signal to noise ratio. Conclusion The new method has prospect of high frame rate 3D imaging. In addition, the imaging system based this method is easily implemented and has high quality image.展开更多
In this paper, we extensively study the higher-order harmonic generation of the general limited diffraction m-th- order Bessel beam. The analysis is based on successive approximations of the Khokhlov-Zabolotskaya-Kuzn...In this paper, we extensively study the higher-order harmonic generation of the general limited diffraction m-th- order Bessel beam. The analysis is based on successive approximations of the Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation. Asymptotic expansions are presented for higher-order harmonic Bessel beams in near and far fields. The validity of asymptotic approximation is also analyzed. The higher-order harmonic of the Bessel beam with the lowest zero-order is taken as a special example.展开更多
The imaging capability of conventional lenses is mainly limited by the diffraction of light,and the so-called superlens has been developed allowing the recovery of evanescent waves in the focal plane.However,the remar...The imaging capability of conventional lenses is mainly limited by the diffraction of light,and the so-called superlens has been developed allowing the recovery of evanescent waves in the focal plane.However,the remarkable focusing behavi-or of the superlens is greatly confined in the near-field regime due to the exponential decay of evanescent waves.To tackle this issue,we design a waveguide metasurface-based superlens with an extraordinary quasi-far-field focusing capability beyond the diffraction limit in the present work.Specifically,we analyze the underlying physical mechanism and provide experimental verification of the proposed superlens.The metasurface superlens is formed by an array of gradient nanoslits perforated in a gold slab,and supports transverse-electric(TE)waveguide modes under linearly polar-ized illumination along the long axis of the slits.Numerical results illustrate that exciting such TE waveguide modes can modulate not only optical phase but also evanescent waves.Consequently,some high-spatial-frequency waves can con-tribute to the focusing of the superlens,leading to the quasi-far-field super-resolution focusing of light.Under 405 nm illu-mination and oil immersion,the fabricated superlens shows a focus spot of 98 nm(i.e.λ/4.13)at a focal distance of 1.49μm(i.e.3.68λ)using an oil immersion objective,breaking the diffraction limit ofλ/2.38 in the quasi-far field regime.The developed metasurface optical superlens with such extraordinary capabilities promises exciting avenues to nanolitho-graphy and ultra-small optoelectronic devices.展开更多
Fluorescence nanoscopy provides imaging techniques that overcome the diffraction-limited resolution barrier in light microscopy,thereby opening up a new area of research in biomedical imaging in fields such as neurosc...Fluorescence nanoscopy provides imaging techniques that overcome the diffraction-limited resolution barrier in light microscopy,thereby opening up a new area of research in biomedical imaging in fields such as neuroscience.Here,we review the foremost fluorescence nanoscopy techniques,including descriptions of their applications in elucidating protein architectures and mobility,the real-time determination of synaptic parameters involved in neural processes,three-dimensional imaging,and the tracking of nanoscale neural activity.We conclude by discussing the prospects of fluorescence nanoscopy,with a particular focus on its deployment in combination with related techniques(e.g.,machine learning)in neuroscience.展开更多
Optical microscopy allows us to observe the biological structures and processes within living cells.However,the spatial resolution of the optical microscopy is limited to about half of the wavelength by the light di...Optical microscopy allows us to observe the biological structures and processes within living cells.However,the spatial resolution of the optical microscopy is limited to about half of the wavelength by the light di®raction.Structured illumination microscopy(SIM),a type of new emerging super-resolution microscopy,doubles the spatial resolution by illuminating the specimen with a patterned light,and the sample and light source requirements of SIM are not as strict as the other super-resolution microscopy.In addition,SIM is easier to combine with the other imaging techniques to improve their imaging resolution,leading to the developments of diverse types of SIM.SIM has great potential to meet the various requirements of living cells imaging.Here,we review the recent developments of SIM and its combination with other imaging techniques.展开更多
In the implementation of CARS nanoscopy, signal strength decreases with focal volume size decreasing. A crucial problem that remains to be solved is whether the reduced signal generated in the suppressed focal volume ...In the implementation of CARS nanoscopy, signal strength decreases with focal volume size decreasing. A crucial problem that remains to be solved is whether the reduced signal generated in the suppressed focal volume can be detected. Here reported is a theoretical analysis of detection limit (DL) to time-resolved CARS (T-CARS) nanoscopy based on our proposed additional probe-beam-induced phonon depletion (APIPD) method for the low concentration samples. In order to acquire a detailed shot-noise limited signal-to-noise (SNR) and the involved parameters to evaluate DL, the T-CARS process is described with full quantum theory to estimate the extreme power density levels of the pump and Stokes beams determined by saturation behavior of coherent phonons, which are both actually on the order of ~ 109 W/cm2. When the pump and Stokes intensities reach such values and the total intensity of the excitation beams arrives at a maximum tolerable by most biological samples in a certain suppressed focal volume (40-nm suppressed focal scale in APIPD method), the DL correspondingly varies with exposure time, for example, DL values are 103 and 102 when exposure times are 20 ms and 200 ms respectively.展开更多
The plasmon waveguide based on double chain of gold cylinders is studied using the finite-difference time-domain method (FDTD). The wavelength of the incident Gaussian beam ranges from 650 to 1200nm, and the corresp...The plasmon waveguide based on double chain of gold cylinders is studied using the finite-difference time-domain method (FDTD). The wavelength of the incident Gaussian beam ranges from 650 to 1200nm, and the corresponding attenuation factors are calculated. We also present a Y-splitter with 90° splitting angle, each branch in the form of double chains. The transmission efficiencies for different wavelengths are evaluated.展开更多
A 1178 J near diffraction limited 527 nm laser is realized in a complete closed-loop adaptive optics(AO)controlled off-axis multi-pass amplification laser system.Generated from a fiber laser and amplified by the pre-a...A 1178 J near diffraction limited 527 nm laser is realized in a complete closed-loop adaptive optics(AO)controlled off-axis multi-pass amplification laser system.Generated from a fiber laser and amplified by the pre-amplifier and the main amplifier,a 1053 nm laser beam with the energy of 1900 J is obtained and converted into a 527 nm laser beam by a KDP crystal with 62%conversion efficiency,1178 J and beam quality of 7.93 times the diffraction limit(DL).By using a complete closed-loop AO configuration,the static and dynamic wavefront distortions of the laser system are measured and compensated.After correction,the diameter of the circle enclosing 80%energy is improved remarkably from 7.93DL to 1.29DL.The focal spot is highly concentrated and the 1178 J,527 nm near diffraction limited laser is achieved.展开更多
Fluorescence microscopy has become an essential tool for biological research because it can be minimally invasive, acquire data rapidly, and target molecules of interest with specific labeling strategies. However, the...Fluorescence microscopy has become an essential tool for biological research because it can be minimally invasive, acquire data rapidly, and target molecules of interest with specific labeling strategies. However, the diffraction-limited spatial resolution, which is classically limited to about 200 nm in the lateral direction and about 500 nm in the axial direction, hampers its application to identify delicate details of subcellular structure. Extensive efforts have been made to break diffraction limit for obtaining high-resolution imaging of a biological specimen. Various methods capable of obtaining super-resolution images with a resolution of tens of nanometers are currently available. These super-resolution techniques can be generally divided into three primary classes: (1) patterned illumination- based super-resolution imaging, which employs spatially and temporally modulated illumination light to reconstruct sub-diffraction structures; (2) single-molecule localization-based super-resolution imaging, which localizes the profile center of each individual fluo- rophore at subdiffraction precision; (3) bleaching/blinking-based super-resolution imaging. These super-resolution techniques have been utilized in different biological fields and provide novel insights into several new aspects of life science. Given unique technical merits and commercial availability of super-resolution fluorescence microscope, increasing applications of this powerful technique in life science can be expected.展开更多
The conceptual of Hefei Advanced Light Source, which is an advanced VUV and Soft X-ray source, was developed at NSRL of USTC. According to the synchrotron radiation user requirements and the trends of SR source develo...The conceptual of Hefei Advanced Light Source, which is an advanced VUV and Soft X-ray source, was developed at NSRL of USTC. According to the synchrotron radiation user requirements and the trends of SR source development, some accelerator-based schemes were considered and compared; furthermore storage ring with ultra low emittance was adopted as the baseline scheme of HALS. To achieve ultra low emittance, some focusing structures were studied and optimized in the lattice design. Compromising of emittance, onmomentum and off-momentum dynamic aperture and ring scale, five bend acromat (FBA) was employed. In the preliminary design of HALS, the emittance was reduced to sub nm·rad, thus the radiation up to water window has full lateral coherence. The brilliance of undulator radiation covering several eVs to keVs range is higher than that of HLS by several orders. The HALS should be one of the most advanced synchrotron radiation light sources in the world.展开更多
Investigations of ultrafast processes occurring on the nanoscale require a combination of femtosecond pulses and nanometer spatial resolution.However,controlling femtosecond pulses with nanometer accuracy is very chal...Investigations of ultrafast processes occurring on the nanoscale require a combination of femtosecond pulses and nanometer spatial resolution.However,controlling femtosecond pulses with nanometer accuracy is very challenging,as the limitations imposed both by dispersive optics on the time duration of a pulse and by the spatial diffraction limit on the focusing of light must be overcome simultaneously.In this paper,we provide a universal method that allows full femtosecond pulse control in subdiffraction-limited areas.We achieve this aim by exploiting the intrinsic coherence of the second harmonic emission from a single nonlinear nanoparticle of deep subwavelength dimensions.The method is proven to be highly sensitive,easy to use,quick,robust and versatile.This approach allows measurements of minimal phase distortions and the delivery of tunable higher harmonic light in a nanometric volume.Moreover,the method is shown to be compatible with a wide range of particle sizes,shapes and materials,allowing easy optimization for any given sample.This method will facilitate the investigation of light–matter interactions on the femtosecond–nanometer level in various areas of scientific study.展开更多
文摘Objective To investigate a new class of solutions to the isotropic/homogeneous scalar wave equation, which termed limited diffraction beams and realize ultrasonic 3D imaging. Methods Limited diffraction beams were derived. We performed the study of 3D pulse echo imaging with limited diffraction array beam. To obtain high frame rate images, a single plane wave pulse (broadband) was transmitted with the arrays. Echoes received with the same arrays were processed with Fourier method to construct 3D images. Results Compared with traditional pulse echo imaging, this method has a larger depth of field, high frame rate, and high signal to noise ratio. Conclusion The new method has prospect of high frame rate 3D imaging. In addition, the imaging system based this method is easily implemented and has high quality image.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11074038 and 11374051)
文摘In this paper, we extensively study the higher-order harmonic generation of the general limited diffraction m-th- order Bessel beam. The analysis is based on successive approximations of the Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation. Asymptotic expansions are presented for higher-order harmonic Bessel beams in near and far fields. The validity of asymptotic approximation is also analyzed. The higher-order harmonic of the Bessel beam with the lowest zero-order is taken as a special example.
基金support by the National Natural Science Foundation of China(52075410,51975483,51622509)the Fundamental Research Funds for the Central Universities(31020190504001)+3 种基金the 111 Project(B13044),the Dean Fund(2019GDYJY05)the Collaborative Innov-ation Center Project of Shaanxi Provincial Department of Education(20JY031)the Natural Science Basic Research Plan in Shaanxi Province of China(2018JQ6012)the Hong Kong Polytechnic University through the“Life Science Research”project(1-ZVH9),and the City University of Hong Kong(9610456).
文摘The imaging capability of conventional lenses is mainly limited by the diffraction of light,and the so-called superlens has been developed allowing the recovery of evanescent waves in the focal plane.However,the remarkable focusing behavi-or of the superlens is greatly confined in the near-field regime due to the exponential decay of evanescent waves.To tackle this issue,we design a waveguide metasurface-based superlens with an extraordinary quasi-far-field focusing capability beyond the diffraction limit in the present work.Specifically,we analyze the underlying physical mechanism and provide experimental verification of the proposed superlens.The metasurface superlens is formed by an array of gradient nanoslits perforated in a gold slab,and supports transverse-electric(TE)waveguide modes under linearly polar-ized illumination along the long axis of the slits.Numerical results illustrate that exciting such TE waveguide modes can modulate not only optical phase but also evanescent waves.Consequently,some high-spatial-frequency waves can con-tribute to the focusing of the superlens,leading to the quasi-far-field super-resolution focusing of light.Under 405 nm illu-mination and oil immersion,the fabricated superlens shows a focus spot of 98 nm(i.e.λ/4.13)at a focal distance of 1.49μm(i.e.3.68λ)using an oil immersion objective,breaking the diffraction limit ofλ/2.38 in the quasi-far field regime.The developed metasurface optical superlens with such extraordinary capabilities promises exciting avenues to nanolitho-graphy and ultra-small optoelectronic devices.
基金the Zhangjiang National Innovation Demonstration Zone(ZJ2019-ZD-005)the National Natural Science Foundation of China(11874267)supported by a fellowship of the China Postdoctoral Science Foundation(2020M671169)。
文摘Fluorescence nanoscopy provides imaging techniques that overcome the diffraction-limited resolution barrier in light microscopy,thereby opening up a new area of research in biomedical imaging in fields such as neuroscience.Here,we review the foremost fluorescence nanoscopy techniques,including descriptions of their applications in elucidating protein architectures and mobility,the real-time determination of synaptic parameters involved in neural processes,three-dimensional imaging,and the tracking of nanoscale neural activity.We conclude by discussing the prospects of fluorescence nanoscopy,with a particular focus on its deployment in combination with related techniques(e.g.,machine learning)in neuroscience.
基金This study was partly supported by the National Key Basic Research Program of China (973 Program)under Grant No.2015CB352006the National Natural Science Foundation of China under Grants Nos.61335011 and 61405035Program for Changjiang Scholars and Innovative Research Team in University under Grant No.IRT 15R10.
文摘Optical microscopy allows us to observe the biological structures and processes within living cells.However,the spatial resolution of the optical microscopy is limited to about half of the wavelength by the light di®raction.Structured illumination microscopy(SIM),a type of new emerging super-resolution microscopy,doubles the spatial resolution by illuminating the specimen with a patterned light,and the sample and light source requirements of SIM are not as strict as the other super-resolution microscopy.In addition,SIM is easier to combine with the other imaging techniques to improve their imaging resolution,leading to the developments of diverse types of SIM.SIM has great potential to meet the various requirements of living cells imaging.Here,we review the recent developments of SIM and its combination with other imaging techniques.
基金Project supported by the National Basic Research Program of China(Grant No.2012CB825802)the Major Scientific Instruments Equipment Development of China(Grant No.2012YQ15009203)+1 种基金the National Natural Science Foundation of China(Grant Nos.60878053 and 11004136)the State Key Laboratory of Precision Measurement Technology and Instruments,Tsinghua University,China(Grant No.DL12-01)
文摘In the implementation of CARS nanoscopy, signal strength decreases with focal volume size decreasing. A crucial problem that remains to be solved is whether the reduced signal generated in the suppressed focal volume can be detected. Here reported is a theoretical analysis of detection limit (DL) to time-resolved CARS (T-CARS) nanoscopy based on our proposed additional probe-beam-induced phonon depletion (APIPD) method for the low concentration samples. In order to acquire a detailed shot-noise limited signal-to-noise (SNR) and the involved parameters to evaluate DL, the T-CARS process is described with full quantum theory to estimate the extreme power density levels of the pump and Stokes beams determined by saturation behavior of coherent phonons, which are both actually on the order of ~ 109 W/cm2. When the pump and Stokes intensities reach such values and the total intensity of the excitation beams arrives at a maximum tolerable by most biological samples in a certain suppressed focal volume (40-nm suppressed focal scale in APIPD method), the DL correspondingly varies with exposure time, for example, DL values are 103 and 102 when exposure times are 20 ms and 200 ms respectively.
基金Supported by the National Basic Research Programme of China under Grant No 2006CB921900, the National Natural Science Foundation of China under Grant No 10604052, the Programme for New Century Excellent Talents in University, the Knowledge Innovation Project of Chinese Academy of Sciences under Gait No KGCX2-YW-103, the Programme of the Education Department of Anhui Province under Grant No 2006kj074A, the China Postdoctoral Science Foundation of China under Grant No 20060400205, the K. C. Wong Education Foundation of Hong Kong.
文摘The plasmon waveguide based on double chain of gold cylinders is studied using the finite-difference time-domain method (FDTD). The wavelength of the incident Gaussian beam ranges from 650 to 1200nm, and the corresponding attenuation factors are calculated. We also present a Y-splitter with 90° splitting angle, each branch in the form of double chains. The transmission efficiencies for different wavelengths are evaluated.
基金the National Natural Science Foundation of China(Nos.61775199 and 61775112).
文摘A 1178 J near diffraction limited 527 nm laser is realized in a complete closed-loop adaptive optics(AO)controlled off-axis multi-pass amplification laser system.Generated from a fiber laser and amplified by the pre-amplifier and the main amplifier,a 1053 nm laser beam with the energy of 1900 J is obtained and converted into a 527 nm laser beam by a KDP crystal with 62%conversion efficiency,1178 J and beam quality of 7.93 times the diffraction limit(DL).By using a complete closed-loop AO configuration,the static and dynamic wavefront distortions of the laser system are measured and compensated.After correction,the diameter of the circle enclosing 80%energy is improved remarkably from 7.93DL to 1.29DL.The focal spot is highly concentrated and the 1178 J,527 nm near diffraction limited laser is achieved.
基金supported by the grants from the National Natural Science Foundation of China(Nos.11174089 and 61138003)the Instrument Developing Project of the Chinese Academy of Sciences(No.YZ201263)+2 种基金the Instrument Function Developing Project of the Chinese Academy of Sciences(No.yg2012032)the Key Project of Department of Education of Guangdong Province(No.cxzd1112)Guangzhou Municipal Science and Technology Program Project(No.2012J5100004)
文摘Fluorescence microscopy has become an essential tool for biological research because it can be minimally invasive, acquire data rapidly, and target molecules of interest with specific labeling strategies. However, the diffraction-limited spatial resolution, which is classically limited to about 200 nm in the lateral direction and about 500 nm in the axial direction, hampers its application to identify delicate details of subcellular structure. Extensive efforts have been made to break diffraction limit for obtaining high-resolution imaging of a biological specimen. Various methods capable of obtaining super-resolution images with a resolution of tens of nanometers are currently available. These super-resolution techniques can be generally divided into three primary classes: (1) patterned illumination- based super-resolution imaging, which employs spatially and temporally modulated illumination light to reconstruct sub-diffraction structures; (2) single-molecule localization-based super-resolution imaging, which localizes the profile center of each individual fluo- rophore at subdiffraction precision; (3) bleaching/blinking-based super-resolution imaging. These super-resolution techniques have been utilized in different biological fields and provide novel insights into several new aspects of life science. Given unique technical merits and commercial availability of super-resolution fluorescence microscope, increasing applications of this powerful technique in life science can be expected.
基金Supported by National Natural Science Foundation (10875127, 10675117)Foundation of NSRL
文摘The conceptual of Hefei Advanced Light Source, which is an advanced VUV and Soft X-ray source, was developed at NSRL of USTC. According to the synchrotron radiation user requirements and the trends of SR source development, some accelerator-based schemes were considered and compared; furthermore storage ring with ultra low emittance was adopted as the baseline scheme of HALS. To achieve ultra low emittance, some focusing structures were studied and optimized in the lattice design. Compromising of emittance, onmomentum and off-momentum dynamic aperture and ring scale, five bend acromat (FBA) was employed. In the preliminary design of HALS, the emittance was reduced to sub nm·rad, thus the radiation up to water window has full lateral coherence. The brilliance of undulator radiation covering several eVs to keVs range is higher than that of HLS by several orders. The HALS should be one of the most advanced synchrotron radiation light sources in the world.
基金This research was funded by the MICINN(programs Consolider Ingenio-2010:CSD2007-046-NanoLight.es,Plan Nacional FIS2009-0123:Optical NanoAntennas)the European Union(ERC Advanced Grant 247330-NanoAntennas)+2 种基金LP acknowledges financial support from the Marie-Curie International Fellowship COFUND and ICFOnest programFP received support from the European Commission through the Erasmus Mundus Joint Doctorate Programme Europhotonics(Grant No.159224-1-2009-1-FR-ERA MUNDUS-EMJD)DB acknowledges support from a Rubicon Grant of the Netherlands Organization for Scientific Research.
文摘Investigations of ultrafast processes occurring on the nanoscale require a combination of femtosecond pulses and nanometer spatial resolution.However,controlling femtosecond pulses with nanometer accuracy is very challenging,as the limitations imposed both by dispersive optics on the time duration of a pulse and by the spatial diffraction limit on the focusing of light must be overcome simultaneously.In this paper,we provide a universal method that allows full femtosecond pulse control in subdiffraction-limited areas.We achieve this aim by exploiting the intrinsic coherence of the second harmonic emission from a single nonlinear nanoparticle of deep subwavelength dimensions.The method is proven to be highly sensitive,easy to use,quick,robust and versatile.This approach allows measurements of minimal phase distortions and the delivery of tunable higher harmonic light in a nanometric volume.Moreover,the method is shown to be compatible with a wide range of particle sizes,shapes and materials,allowing easy optimization for any given sample.This method will facilitate the investigation of light–matter interactions on the femtosecond–nanometer level in various areas of scientific study.