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Improved sampling scheme for LiDAR in Lissajous scanning mode

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Microsystems & Nanoengineering 2022年第3期8卷 29-37页

作者： Junya Wang Gaofei Zhang zheng you School of Mechanical Science and Engineering Huazhong University of Science and Technology430074 WuhanChina Department of Precision Instrument Tsinghua University10084 BeijingChina State Key Laboratory of Precision Measurement Technology and instruments Tsinghua University10084 BeijingChina

MEMS light detection and ranging(LiDAR)is becoming an indispensable sensor in vehicle environment sensing systems due to its low cost and high *** beam scanning trajectory,sampling scheme and gridding are the key technologies of MEMS LiDAR *** Lissajous scanning mode,this paper improves the sampling scheme,through which a denser Cartesian grid of point cloud data at the same scanning frequency can be *** summarizing the rules of the Cartesian grid,a general sampling scheme independent of the beam scanning trajectory patterns is *** and experiment results show that compared with the existing sampling scheme,the resolution and the number of points per frame are both increased by 2 times with the same hardware configuration and scanning frequencies for a MEMS scanning miror(MEMS-SM).This is beneficial for improving the point cloud imaging performance of MEMS LiDAR.

关键词： LiDAR scheme mode

Design rules for dense and rapid Lissajous scanning

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Microsystems & Nanoengineering 2020年第1期6卷 158-164页

作者： Junya Wang Gaofei Zhang zheng you Department of Precision Instrument Tsinghua UniversityBeijingChina State Key Laboratory of Precision Testing Technology and Instruments Tsinghua University10084 BeijingChina Information Engineering University ZhengzhouChina

Lissajous microscanners are very popular in compact laser-scanning applications,such as solid-state light detection and ranging(LIDAR),owing to their high-quality factor and low power *** the Lissajous scanner driven by a two-axis micro-electro-mechanical system scanning mirror(MEMS-SM),the design theory is insufficient to meet the temporal and spatial resolution at the same *** this paper,the greatest common divisor of the two-axis driving frequency is used as the temporal resolution,the concept of the fill factor(FF)is used to describe the spatial resolution of the scanner,and a general algorithm for calculating the FF is *** with the characteristics of the Lissajous trajectory,three design rules of the general Lissajous scanner are proposed,and the design theory of the Lissajous scanner enabling MEMS LIDAR is *** results show that the proposed design rules can effectively meet the LIDAR design requirements.

关键词： scanner LIDAR scanning

Grignard Addition to Quinoxalinium Salt: Synthesis of 1, 2-Dihydro-quinoxaline and 1, 2, 3, 4-Tetrahydroquinoxaline Derivatives

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Chinese Chemical Letters 2006年第2期17卷 165-168页

作者： Lian you zheng Xu BAI The Center for Combinatorial Chemistry and Drug Discovery Jilin University Changchun 130012

Grignard additions to a quinoxalinium salt were studied. Depending on the ratio of the reagents and reaction temperature, 1, 2, 3, 4-tetrahydroquinoxaline and 1, 2-dihydroquinoxaline derivatives could be resulted sele... 详细信息

关键词： Grignard addition quinoxalinium salt dihydroquinoxaline tetrahydroquinoxaline.

Multiple Positive Solutions for a Fourth-order p-Laplacian Sturm-Liouville Boundary Value Problems on Time Scales

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Acta Mathematicae Applicatae Sinica 2015年第2期31卷 287-296页

作者： you-zheng DING Zhong-li WEI School of Mathematics Shandong University Department of Mathematics Shandong Jianzhu University

In this paper, we investigate the existence of multiple positive solutions for the following fourthorder p-Laplacian Sturm-Liouville boundary value problems on time scales ﹛[φp（u^△△（t））]^△△= f（t, u（σ（t）））, t ∈ [a, b],α0 u（a）- β0u^△（a） = 0, γ0 u（σ（b））＋ δ0 u△（σ（b）） = 0,α0（φp（u^△△））（a）- β0（φp（u^△△））△（a） = 0,γ0（φp（u^△△））（σ（b））＋ δ0（φp（u^△△））△（σ（b）） = 0,where φp（s） is the p-Laplacian operator. Under growth conditions on the nonlinearity f some existence results of at least two and three positive solutions for the above problem are obtained by virtue of fixed point theorems on cone. In particular, the nonlinearity f may be both sublinear and superlinear.

关键词： time scales p-Laplacian equation positive solution fixed point theorem

Fundamentals of phase-only liquid crystal on silicon (LCOS) devices

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Light(Science & Applications) 2014年第1期3卷 43-52页

作者： Zichen Zhang zheng you Daping Chu State Key Laboratory of Precision Measurement Technology and Instruments Collaborative Innovation Center for Micro/Nano FabricationDevice and SystemDepartment of Precision InstrumentTsinghua UniversityBeijing 100084China Electrical Engineering Division Department of EngineeringUniversity of CambridgeCambridge CB30FAUK

This paper describes the fundamentals of phase-only liquid crystal on silicon(LCOS)technology,which have not been previously discussed in *** technology is widely utilized in high efficiency applications for real-time holography and diffractive *** paper begins with a brief introduction on the developmental trajectory of phase-only LCOS technology,followed by the correct selection of liquid crystal(LC)materials and corresponding electro-optic effects in such *** is focused on the essential requirements of the physical aspects of the LC layer as well as the indispensable parameters for the response time of the ***,the basic functionalities embedded in the complementary metal oxide semiconductor(CMOS)silicon backplane for phase-only LCOS devices are illustrated,including two typical addressing ***,the application of phase-only LCOS devices in real-time holography will be introduced in association with the use of cutting-edge computer-generated holograms.

关键词： electro-optic effect liquid crystal material liquid crystal on silicon device real-time holography

Chiral thermally activated delayed fluorescence materials for circularly polarized organic light-emitting diodes

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Science China Chemistry 2024年第4期67卷 1097-1116页

作者： Li Yuan Yi-Pin Zhang you-Xuan zheng State Key Laboratory of Coordination Chemistry Collaborative Innovation Center of Advanced MicrostructuresJiangsu Key Laboratory of Advanced Organic MaterialsSchool of Chemistry and Chemical EngineeringNanjing UniversityNanjing 210023China

Chirality is an important natural characteristic of organic molecules,and chiral organic molecules have shown extensive application in areas such as pharmaceutical development and material *** from the ability to achieve circularly polarized luminescence(CPL),chiral luminescent materials have shown potential applications in anti-glare display,optical communication and,3D display,*** to the ability to harvest both singlet and triplet excitons by a fast reverse intersystem crossing process without involving noble metals,chiral thermally activated delayed fluorescence(TADF)materials with point chirality,axial chirality,planar chirality and helical chirality are regarded as the state-of-the-art materials for circularly polarized organic light-emitting diodes(CP-OLEDs).In recent years,the chiral TADF materials and CP-OLEDs have rapidly developed,but unfortunately,the dissymmetry factors(g)are far from the requirement of practical *** ideal emitters and devices should have both high efficiency and a g factor,or at least a balance between these two *** review gives an overview of recent progress in chiral TADF materials,with a particular focus on the chiral skeleton,CPL property and device ***,the molecular design concept,device structure and methods to improve the g factors of chiral materials and CP-OLEDs are also discussed.

关键词： chiral thermally activated delayed fluorescence material chiral skeleton circularly polarized luminescence circularly polarized organic light-emitting diodes dissymmetry factor

A real-time detection and positioning method for small and weak targets using a 1D morphology-based approach in 2D images

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Light(Science & Applications) 2018年第1期7卷 1063-1071页

作者： Min-Song Wei Fei Xing zheng you Department of Precision Instrument Tsinghua UniversityBeijing 100084China State Key Laboratory of Precision Measurement Technology and Instruments Tsinghua UniversityBeijing 100084China Department of Mechanical Engineering University of CaliforniaBerkeleyCA 94720USA

A small and weak target detection method is proposed in this work that outperforms all other methods in terms of real-time *** is the first time that two-dimensional(2D)images are processed using only one-dimensional1D structuring elements in a morphology-based approach,enabling the real-time hardware implementation of the whole image processing method.A parallel image readout and processing structure is introduced to achieve an ultra-low latency time on the order of nanoseconds,and a hyper-frame resolution in the time domain can be achieved by combining the row-by-row structure and the electrical rolling shutter *** results suggest that the expected target can be successfully detected under various interferences with an accuracy of 0.1 pixels(1σ)under the worst sky night test condition and that a centroiding precision of better than 0.03 pixels(1σ)can be reached for static *** real-time detection method with high robustness and accuracy is attractive for application to all types of real-time small target detection systems,such as medical imaging,infrared surveillance,and target measurement and tracking,where an ultra-high processing speed is required.

关键词： high robustness and accuracy 1D morphology-based approach row-by-row structure real-time detection method small and weak target detection and positioning

A wide-field and high-resolution lensless compound eye microsystem for real-time target motion perception

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Microsystems & Nanoengineering 2022年第4期8卷 199-207页

作者： Li Zhang Haiyang Zhan Xinyuan Liu Fei Xing zheng you Department of Precision Instrument Tsinghua UniversityBeijing 100084China State Key Laboratory of Precision Measurement Technology and Instrument Tsinghua UniversityBeijing 100084China Beijing Advanced Innovation Center for Integrated Circuits Beijing 100084China

Optical measurement systems suffer from a fundamental tradeoff between the field of view(FOV),the resolution and the update rate.A compound eye has the advantages of a wide FOV,high update rate and high sensitivity to motion,providing inspiration for breaking through the constraint and realizing high-performance optical ***,most existing studies on artificial compound eyes are limited by complex structure and low resolution,and they focus on imaging instead of precise ***,a high-performance lensless compound eye microsystem is developed to realize target motion perception through precise and fast orientation *** microsystem splices multiple sub-FOVs formed by long-focal subeyes,images targets distributed in a panoramic range into a single multiplexing image sensor,and codes the subeye aperture array for distinguishing the targets from different sub-FOVs.A wide-field and high resolution are simultaneously realized in a simple and easy-to-manufacture microelectromechanical system(MEMS)aperture ***,based on the electronic rolling shutter technique of the image sensor,a hyperframe update rate is achieved by the precise measurement of multiple time-shifted spots of one *** microsystem achieves an orientation measurement accuracy of 0.0023°(3σ)in the x direction and 0.0028°(3σ)in the y direction in a cone FOV of 120°with an update rate~20 times higher than the frame *** study provides a promising approach for achieving optical measurements with comprehensive high performance and may have great significance in various applications,such as vision-controlled directional navigation and high-dynamic target tracking,formation and obstacle avoidance of unmanned aerial vehicles.

关键词： precise resolution compound

Stop Gaps and Single Defect States of Acoustic Waves in Two-Dimensional Lattice of Liquid Cylinders

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Chinese Physics Letters 2001年第6期18卷 785-787页

作者： WU Fu-Gen LIU zheng-you LIU you-Yan Department of Applied Physics South China University of TechnologyGuangzhou 510641 Department of Applied Physics Guangdong University of TechnologyGuangzhou 510090

The acoustic wave band structures and single defect states of the two-dimensional periodic composite media of water(mercury)cylinders with circular cross section in mercury(water)host was studied by using the plane-waves method and supercell *** find that the numbers of the gaps in the first 50 bands vs filling fraction have the similar results as gap/midgap ratio of the lowest gap in the period *** one band gap exhibits in wide range of filling fraction,and several defect states are created inside the band gaps in single defect *** influences of filling fraction and defect radius on the band structure are investigated.

关键词： defect mercury fraction