Optical memory effect-based speckle-correlated technology has been developed for reconstructing hidden objectsfrom disordered speckle patterns,achieving imaging through scattering layers.However,the lighting efficienc...Optical memory effect-based speckle-correlated technology has been developed for reconstructing hidden objectsfrom disordered speckle patterns,achieving imaging through scattering layers.However,the lighting efficiency and fieldof view of existing speckle-correlated imaging systems are limited.Here,a near-infrared low spatial coherence fiberrandom laser illumination method is proposed to address the above limitations.Through the utilization of random Rayleighscattering within dispersion-shifted fibers to provide feedback,coupled with stimulated Raman scattering for amplification,a near-infrared fiber random laser exhibiting a high spectral density and extremely low spatial coherence is generated.Based on the designed fiber random laser,speckle-correlated imaging through scattering layers is achieved,with highlighting efficiency and a large imaging field of view.This work improves the performance of speckle-correlated imagingand enriches the research on imaging through scattering medium.展开更多
The Shanghai soft X-ray free-electron laser(SXFEL)user facility project started in 2016 and is expected to be open to users by 2022.It aims to deliver ultra-intense coherent femtosecond X-ray pulses to five endstation...The Shanghai soft X-ray free-electron laser(SXFEL)user facility project started in 2016 and is expected to be open to users by 2022.It aims to deliver ultra-intense coherent femtosecond X-ray pulses to five endstations covering a range of 100–620 eV for ultrafast X-ray science.Two undulator lines are designed and constructed,based on different lasing modes:self-amplified spontaneous emission and echo-enabled harmonic generation.The coherent scattering and imaging(CSI)endstation is the first of five endstations to be commissioned online.It focuses on high-resolution single-shot imaging and the study of ultrafast dynamic processes using coherent forward scattering techniques.Both the single-shot holograms and coherent diffraction patterns were recorded and reconstructed for nanoscale imaging,indicating the excellent coherence and high peak power of the SXFEL and the possibility of‘‘diffraction before destruction’’experiments at the CSI endstation.In this study,we report the first commissioning results of the CSI endstation.展开更多
Three-dimensional imaging with single orientation is a potential and novel technique. We successfully demonstrate that three-dimensional（3D） structure can be determined by a single orientation diffraction measuremen...Three-dimensional imaging with single orientation is a potential and novel technique. We successfully demonstrate that three-dimensional（3D） structure can be determined by a single orientation diffraction measurement for a phase object of double-layer Mie-scattering silica spheres on a Si3N4 membrane. Coherent diffraction pattern at high numerical aperture was acquired with an optical laser, and the oversampled pattern was projected from a planar detector onto the Ewald sphere.The double-layered spheres are reconstructed from the spherical diffraction pattern and a 2D curvature-corrected pattern,which improve convergence speed and stability of reconstruction.展开更多
目的通过调查非压迫黑(dark without pressure,DWOP)在参加空军招飞医学选拔的健康青少年人群中的分布规律,提高空军招飞医学选拔对非压迫黑病变的认识,为优化医学选拔评价标准提供理论依据。方法使用超广角激光眼底扫描系统和光学相干...目的通过调查非压迫黑(dark without pressure,DWOP)在参加空军招飞医学选拔的健康青少年人群中的分布规律,提高空军招飞医学选拔对非压迫黑病变的认识,为优化医学选拔评价标准提供理论依据。方法使用超广角激光眼底扫描系统和光学相干光断层扫描对2021—2022年参加空军招飞医学选拔的学生进行眼底检查,统计非压迫黑的发生率及累及范围等临床特征。结果共有744名学生(1488只眼)纳入研究,其中女112名(224只眼)、男632名(1264只眼)。9名学生13只眼检出存在DWOP,检出率0.87%。其中,男7名11只眼(检出率0.87%),女2名2只眼(检出率0.89%)。4名学生被检出双眼存在DWOP。10只眼(76.92%)病变分布在鼻侧象限,其中8只眼(61.5%)病变与视盘相连。所有学生均未检出视力、视野等视功能异常。结论DWOP不是一种视网膜/脉络膜色素改变或玻璃体/视网膜交界面改变,无直接证据支持DWOP能够引起视功能改变。在空军招飞医学选拔中,学员眼底检查发现存在非压迫黑体征,但不合并其他眼底异常改变的,不做单项不合格结论。展开更多
The paper puts forward a method of virtual keyboard key positioning based on infrared laser reflection and image processing technology. In this paper, the positioning principle is introduced first. And the experimenta...The paper puts forward a method of virtual keyboard key positioning based on infrared laser reflection and image processing technology. In this paper, the positioning principle is introduced first. And the experimental system is established based on image acquisition, image transformation, threshold selection and binarization processing and identification of key placement. Tested in the indoor environment, the method can achieve characters input efficiently and accurately. And the key positioning has high accuracy, validity and reliability. So the method which has a high practical value provides a good theoretical basis for design of virtual keyboard application.展开更多
Using different noble gases,argon,neon and helium,we are able to generate by high-harmonic generation(HHG) just a few harmonic orders in the spectral range 10-35 nm with a photon flux of～2.10 12 photons/(harmonic cm2...Using different noble gases,argon,neon and helium,we are able to generate by high-harmonic generation(HHG) just a few harmonic orders in the spectral range 10-35 nm with a photon flux of～2.10 12 photons/(harmonic cm2 s) for argon and～10 10 photons/(harmonic cm2 s) for helium. The few-harmonic-order radiation is used for coherent diffractive imaging directly without any spectral filter. A spatial resolution of～100 nm is achieved using a～30 nm HHG source.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.62375040 and 11974071)the Sichuan Science and Technology Program(Grant Nos.2022ZYD0108 and 2023JDRC0030).
文摘Optical memory effect-based speckle-correlated technology has been developed for reconstructing hidden objectsfrom disordered speckle patterns,achieving imaging through scattering layers.However,the lighting efficiency and fieldof view of existing speckle-correlated imaging systems are limited.Here,a near-infrared low spatial coherence fiberrandom laser illumination method is proposed to address the above limitations.Through the utilization of random Rayleighscattering within dispersion-shifted fibers to provide feedback,coupled with stimulated Raman scattering for amplification,a near-infrared fiber random laser exhibiting a high spectral density and extremely low spatial coherence is generated.Based on the designed fiber random laser,speckle-correlated imaging through scattering layers is achieved,with highlighting efficiency and a large imaging field of view.This work improves the performance of speckle-correlated imagingand enriches the research on imaging through scattering medium.
基金the Shanghai Soft X-ray Free-Electron Laser Facility beamline projectionfunded by the Major State Basic Research Development Program of China(No.2017YFA0504802)+1 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB 37040303)National Natural Science Foundation of China(No.21727817).
文摘The Shanghai soft X-ray free-electron laser(SXFEL)user facility project started in 2016 and is expected to be open to users by 2022.It aims to deliver ultra-intense coherent femtosecond X-ray pulses to five endstations covering a range of 100–620 eV for ultrafast X-ray science.Two undulator lines are designed and constructed,based on different lasing modes:self-amplified spontaneous emission and echo-enabled harmonic generation.The coherent scattering and imaging(CSI)endstation is the first of five endstations to be commissioned online.It focuses on high-resolution single-shot imaging and the study of ultrafast dynamic processes using coherent forward scattering techniques.Both the single-shot holograms and coherent diffraction patterns were recorded and reconstructed for nanoscale imaging,indicating the excellent coherence and high peak power of the SXFEL and the possibility of‘‘diffraction before destruction’’experiments at the CSI endstation.In this study,we report the first commissioning results of the CSI endstation.
基金Project supported by the Major State Basic Research Development Program of China(Grant No.2014CB910401)the National Natural Science Foundation of China(Grant Nos.31430031,21390414,and U1332118)
文摘Three-dimensional imaging with single orientation is a potential and novel technique. We successfully demonstrate that three-dimensional（3D） structure can be determined by a single orientation diffraction measurement for a phase object of double-layer Mie-scattering silica spheres on a Si3N4 membrane. Coherent diffraction pattern at high numerical aperture was acquired with an optical laser, and the oversampled pattern was projected from a planar detector onto the Ewald sphere.The double-layered spheres are reconstructed from the spherical diffraction pattern and a 2D curvature-corrected pattern,which improve convergence speed and stability of reconstruction.
文摘目的通过调查非压迫黑(dark without pressure,DWOP)在参加空军招飞医学选拔的健康青少年人群中的分布规律,提高空军招飞医学选拔对非压迫黑病变的认识,为优化医学选拔评价标准提供理论依据。方法使用超广角激光眼底扫描系统和光学相干光断层扫描对2021—2022年参加空军招飞医学选拔的学生进行眼底检查,统计非压迫黑的发生率及累及范围等临床特征。结果共有744名学生(1488只眼)纳入研究,其中女112名(224只眼)、男632名(1264只眼)。9名学生13只眼检出存在DWOP,检出率0.87%。其中,男7名11只眼(检出率0.87%),女2名2只眼(检出率0.89%)。4名学生被检出双眼存在DWOP。10只眼(76.92%)病变分布在鼻侧象限,其中8只眼(61.5%)病变与视盘相连。所有学生均未检出视力、视野等视功能异常。结论DWOP不是一种视网膜/脉络膜色素改变或玻璃体/视网膜交界面改变,无直接证据支持DWOP能够引起视功能改变。在空军招飞医学选拔中,学员眼底检查发现存在非压迫黑体征,但不合并其他眼底异常改变的,不做单项不合格结论。
文摘The paper puts forward a method of virtual keyboard key positioning based on infrared laser reflection and image processing technology. In this paper, the positioning principle is introduced first. And the experimental system is established based on image acquisition, image transformation, threshold selection and binarization processing and identification of key placement. Tested in the indoor environment, the method can achieve characters input efficiently and accurately. And the key positioning has high accuracy, validity and reliability. So the method which has a high practical value provides a good theoretical basis for design of virtual keyboard application.
文摘Using different noble gases,argon,neon and helium,we are able to generate by high-harmonic generation(HHG) just a few harmonic orders in the spectral range 10-35 nm with a photon flux of～2.10 12 photons/(harmonic cm2 s) for argon and～10 10 photons/(harmonic cm2 s) for helium. The few-harmonic-order radiation is used for coherent diffractive imaging directly without any spectral filter. A spatial resolution of～100 nm is achieved using a～30 nm HHG source.
