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稀疏孔径一维旋转合成阵列的成像特性

光学学报 2024年第4期44卷 136-145页

作者：张会燕刘明宁布惠梅董立泉孔令琴赵跃进北京理工大学光电学院北京100081 精密光电测试仪器与技术北京市重点实验室北京100081 北京理工大学长三角研究院(嘉兴) 浙江嘉兴314019

分析了一维多孔径阵列的成像特性,选取子孔径间距比为1∶2的一维非冗余三孔径结构为基阵列,以最大化频域覆盖为设计标准,设计了沿基线方向对基阵列在360°范围内以不同角度进行多次旋转的新型合成孔径结构,以提高中频调制传递函数(IFMTF... 详细信息

分析了一维多孔径阵列的成像特性,选取子孔径间距比为1∶2的一维非冗余三孔径结构为基阵列,以最大化频域覆盖为设计标准,设计了沿基线方向对基阵列在360°范围内以不同角度进行多次旋转的新型合成孔径结构,以提高中频调制传递函数(IFMTF)和系统成像质量。当填充因子为28.51%时,旋转合成得到的九孔径阵列的IFMTF值(0.1223)大于Golay-9阵列的0.0782。仿真和实验结果的定量和定性评价均证明了所提方法的有效性。

关键词：成像系统光学稀疏孔径一维多孔径阵列旋转合成中频调制传递函数频域覆盖

Forest Mapping and Classification with Compact PolInSAR Data

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Journal of Beijing Institute of Technology 2018年第3期27卷 391-398页

作者： Ningxiao Sun yuejin zhao Lin Sun Qiongzhi Wu School of Optoelectronics Beijing Institute of Technology School of Information and Electronics Beijing Institute of Technology

An unsupervised classification method was applied to compact polarimetric-interferometric SAR（C-PolInSAR）data to investigate its potential for forest mapping and *** classification requires an initial class as a training *** this paper,the compact polarimetric entropy H and the optimal coherence spectrumA were computed,and their capabilities for initial classification were *** on the Hand A,apartition method was proposed to subdivide the H-A plane,and initial classes were hence ***,unsupervised C-PolInSAR segmentation procedures based on H-A and the complex coherence matrix J;were *** effectiveness of the unsupervised classification of C-PolInSAR data was demonstrated by using an E-SAR L-band PolInSAR dataset of the Traunstein test site.

关键词： forest mapping unsupervised classification Wishart classifier optimal coherence set com-pact polarimetric-interferometric SAR(C-PolInSAR)

Ultrafast hydrogen bond dynamics of liquid water revealed by terahertz-induced transient birefringence

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Light(Science & Applications) 2020年第1期9卷 707-716页

作者： Hang zhao Yong Tan Liangliang Zhang Rui Zhang Mostafa Shalaby Cunlin Zhang yuejin zhao Xi-Cheng Zhang Beijing Key Laboratory for Precision Optoelectronic Measurement Instrument and Technology School of Optics and PhotonicsBeijing Institute of TechnologyBeijing 100081China Beijing Advanced Innovation Center for Imaging Technology and Key Laboratory of Terahertz Optoelectronics(MoE) Department of PhysicsCapital Normal UniversityBeijing 100048China Shenzhen Institutes of Advanced Technology Chinese Academy of SciencesShenzhen 518055China The Institute of Optics University of RochesterRochesterNY 14627USA

The fundamental properties of water molecules,such as their molecular polarizability,have not yet been *** hydrogen bond network is generally considered to play an important role in the thermodynamic properties of *** terahertz(THz)Kerr effect technique,as a novel tool,is expected to be useful in exploring the low-frequency molecular dynamics of liquid ***,we use an intense and ultrabroadband THz pulse(peak electric field strength of 14.9 MV/cm,centre frequency of 3.9 THz,and bandwidth of 1–10 THz)to resonantly excite intermolecular modes of liquid *** THz field-induced transient birefringence signals are observed in a free-flowing water *** propose a hydrogen bond harmonic oscillator model associated with the dielectric susceptibility and combine it with the Lorentz dynamic equation to investigate the intermolecular structure and dynamics of liquid *** mainly decompose the bipolar signals into a positive signal caused by hydrogen bond stretching vibration and a negative signal caused by hydrogen bond bending vibration,indicating that the polarizability perturbation of water presents competing contributions under bending and stretching conditions.A Kerr coefficient equation related to the intermolecular modes of water is *** ultrafast intermolecular hydrogen bond dynamics of water revealed by an ultrabroadband THz pump pulse can provide further insights into the transient structure of liquid water corresponding to the pertinent modes.

关键词： transient dynamics liquid

Diffraction-Limited Imaging with a Graphene Metalens

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Chinese Physics Letters 2020年第10期37卷 54-60页

作者： Xueyan Li Han Lin yuejin zhao Baohua Jia Beijing Key Laboratory for Precision Optoelectronic Measurement Instrument and Technology School of Optics and PhotonicsBeijing Institute of TechnologyBeijing 100081China Centre for Translational Atomaterials Swinburne University of Technology.P.O.Box 218HawthornVIC 3122Australia The Australian Research Council(ARC)Industrial Transformation Training Centre in Surface Engineering for Advanced Materials(SEAM) Swinburne University of TechnologyP.O.Box 218HawthornVIC 3122Australia

Planar graphene metalens has demonstrated advantages of ultrathin thickness(200 nm),high focusing resolution(343 nm)and efficiency(>32%)and robust mechanical strength and ***,diffraction-limited imaging with such a graphene metalens has not been realized,which holds the key to designing practical integrated imaging *** this work,the imaging rule for graphene metalenses is first derived and theoretically verified by using the Rayleigh-Sommerfeld diffraction theory to simulate the imaging performance of the 200 nm ultrathin graphene *** imaging rule is applicable to graphene metalenses in different immersion media,including water or *** on the theoretical prediction,high-resolution imaging using the graphene metalens with diffraction-limited resolution(500 nm)is demonstrated for the first *** work opens the possibility for graphene metalenses to be applied in particle tracking,microfluidic chips and biomedical devices.

关键词： resolution holds rule

Wide-spectrum optical synthetic aperture imaging via spatial intensity interferometry

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Opto-Electronic Advances 2023年第12期6卷 27-35页

作者： Chunyan Chu Zhentao Liu Mingliang Chen Xuehui Shao Guohai Situ yuejin zhao Shensheng Han Beijing Key Laboratory for Precision Optoelectronic Measurement Instrument and Technology Beijing 100081China School of Optics and Photonics Beijing Institute of TechnologyBeijing 100081China Shanghai Institute of Optics and Fine Mechanics Chinese Academy of SciencesShanghai 201800China University of Chinese Academy of Sciences Beijing 100049China National Laboratory of Aerospace Intelligent Control Technology Beijing 100089China Hangzhou Institute for Advanced Study University of Chinese Academy of SciencesHangzhou 310024China.

High resolution imaging is achieved using increasingly larger apertures and successively shorter *** aperture synthesis is an important high-resolution imaging technology used in *** long baseline amplitude interferometry is susceptible to uncontrollable phase fluctuations,and the technical difficulty increases rapidly as the wavelength *** intensity interferometry inspired by HBT experiment is essentially insensitive to phase fluctuations,but suffers from a narrow spectral bandwidth which results in a lack of effective *** this study,we propose optical synthetic aperture imaging based on spatial intensity *** not only realizes diffraction-limited optical aperture synthesis in a single shot,but also enables imaging with a wide spectral bandwidth,which greatly improves the optical energy efficiency of intensity *** this method is insensitive to the optical path difference between the *** and experiments present optical aperture synthesis diffraction-limited imaging through spatial intensity interferometry in a 100 nm spectral width of visible light,whose maximum optical path difference between the sub-apertures reaches 69λ.This technique is expected to provide a solution for optical aperture synthesis over kilometer-long baselines at optical wavelengths.

关键词： optical synthetic aperture imaging ghost imaging intensity interferometry

Perovskite quantum dot microarrays:In situ fabrication via direct print photopolymerization

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Nano Research 2022年第8期15卷 7681-7687页

作者： Xiu Liu Jianjun Li Pingping Zhang Weitong Lu Gaoling Yang Haizheng Zhong yuejin zhao School of Optics and Photonics Beijing Institute of TechnologyBeijing 100081China MIIT Key Laboratory for Low Dimensional Quantum Structure and Devices School of Materials Sciences&EngineeringBeijing Institute of TechnologyBeijing 100081China MIIT Key Laboratory for Low Dimensional Quantum Structure and Devices Beijing 100081China

Quantum dots color conversion(QDCC)is considered as a facial and versatile way to achieve full-color organic light emitting diode(OLED)and micro-LED display due to the wide color gamut performance and easy ***,the aggregation of QDs and coffee-ring effects after solvent evaporation lowers the light conversion efficiency and emission uniformity in QDs microarrays,raising blue-light leakage or optical ***,we report the fabrication of perovskite quantum dots(PQDs)microarrays by combining the inkjet printing and in situ fabrication of PQDs during the photopolymerization of precursor *** resulting PQDs microarrays exhibit three-dimensional(3D)morphology with hemisphere shape as well as strong photoluminescence,which is desirable for QDCC *** demonstrate the dominant role of ultraviolet(UV)curable precursors and surface functionalized substrate in controlling the shape of microarrays,where significantly increased contact angle(100°)and large height to diameter ratio(0.42)can be *** further demonstrate the potential use of the in situ direct print photopolymerization method for fabricating large-area multicolor patterned pixel microarrays with a wide color gamut and high *** fabrication of 3D PQDs microarrays opens up new opportunities in a variety of applications including photonics integration,micro-LED,and near-field display.

关键词： quantum dots perovskite in situ fabrication inkjet printing microarrays

Laser Methane Sensor and the Study of Cross Interference

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Journal of Beijing Institute of Technology 2018年第3期27卷 419-425页

作者： Yanfang Li yuejin zhao Tingting Zhang Jie Hu Yubin Wei Tongyu Liu School of Optoelectronics Beijing Institute of Technology Shandong Key Laboratory of Optical Fiber Sensing Technologies

A methane sensor system was designed based on tunable diode laser absorption spectroscopy(TDLAS)technology and the feature of vertical cavity surface emitting laser(VCSEL)with wavelengths up to several *** studied the gas present in the methane sensor’s common operation *** absorption spectrum stimulation and experiments,we analyzed the cross interference of the gas of H2 O,CO and CO2 to methane *** results prove that this laser methane sensor has the characteristics of high stability and anti-cross interference.

关键词： tunable diode laser absorption spectroscopy(TDLAS) vertical cavity surface emitting laser(VCSEL) methane sensor cross interference

The Mandatory Energy Efficiency Standard for Distribution Transformer soon Publicized in China

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China Standardization 2005年第3期50卷 16-19页

作者： By zhao yuejin

Owning to the rapid economy development in China and sharp increase of energyconsumption in recent years, energy shortage is increasingly apparent and becoming an importantobstacle to the sustainable development of our economy. With the aim to relieve the problem ofenergy shortage, the State Development and Reform Commission places the great emphasis ofenergy-saving work on improving energy efficiency of industrial energy-consuming products inenergy-saving work. The General Administration of Quality Supervision, Inspection and Quarantine ofthe People's Republic of China (AQSIQ) has issued and implemented two energy efficiency standardsfor three-phase induction motors and displacement air compressor, and will soon issue another twoenergy efficiency standards for clean- water centrifugal pumps and ventilation fans. The transformeris a kind of electric equipment widely used in many industries in national economy, with featuresof great amount of use, long period of operation and tremendous potential of energy-saving. So, itis necessary to develop the standard of energy efficiency for distribution transformers.

关键词： The Mandatory Energy Efficiency Standard for Distribution Transformer soon Publicized in China

Transient evolution of quasifree electrons of plasma in liquid water revealed by optical-pump terahertz-probe spectroscopy

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Advanced Photonics 2021年第1期3卷 56-62页

作者： Yong Tan Hang zhao Rui Zhang yuejin zhao Cunlin Zhang Xi-Cheng Zhang Liangliang Zhang Beijing Institute of Technology School of Optics and Photonics Beijing Key Laboratory for Precision Optoelectronic Measurement Instruments and Technology Chinese Academy of Sciences Shenzhen Institutes of Advanced Technology Capital Normal University Beijing Advanced Innovation Center for Imaging Technology and Key Laboratory of Terahertz Optoelectronics (MoE)Department of Physics University of Rochester Institute of Optics

The fundamental properties of laser-induced plasma in liquid water, such as the ultrafast electron migration and solvation, have not yet been clarified. We use 1650-nm femtosecond laser pulses to induce the plasma in a stable free-flowing water film under the strong field ionization mechanism. Moreover, we adopt intense terahertz(THz) pulses to probe the ultrafast temporal evolution of quasifree electrons of the laserinduced plasma in water on the subpicosecond scale. For the first time, the THz wave absorption signal with a unique two-step decay characteristic in time domain is demonstrated, indicating the significance of electron solvation in water. We employ the Drude model combined with the multilevel intermediate model and particlein-a-box model to simulate and analyze the key information of quasifree electrons, such as the frequencydomain absorption characteristics and solvation ratio. In particular, we observe that the solvation capacity of liquid water decreases with the increase of pumping energy. Up to ～50% of quasifree electrons cannot be captured by traps associated with the bound states as the pumping energy increases to 90 μJ∕pulse. The ultrafast electron evolution in liquid water revealed by the optical-pump/THz-probe experiment provides further insights into the formation and evolution mechanisms of liquid plasma.

关键词： terahertz liquid water plasma solvation