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Metasurface array for single-shot spectroscopic ellipsometry

Light(Science & Applications) 2024年第5期13卷 835-842页

作者： Shun Wen Xinyuan Xue Shuai Wang Yibo Ni Liqun Sun Yuanmu Yang Department of Precision Instrument State Key Laboratory of Precision Measurement Technology and InstrumentsTsinghua UniversityBeijing 100084China

Spectroscopic ellipsometry is a potent method that is widely adopted for the measurement of thin film thickness and refractive *** conventional ellipsometers utilize mechanically rotating polarizers and grating-based spectrometers for spectropolarimetric ***,we demonstrated a compact metasurface array-based spectroscopic ellipsometry system that allows single-shot spectropolarimetric detection and accurate determination of thin film properties without any mechanical *** silicon-based metasurface array with a highly anisotropic and diverse spectral response is combined with iterative optimization to reconstruct the full Stokes polarization spectrum of the light reflected by the thin film with high ***,the film thickness and refractive index can be determined by fitting the measurement results to a proper material model with high *** approach opens up a new pathway towards a compact and robust spectroscopic ellipsometry system for the high throughput measurement of thin film properties.

关键词： properties. spectroscopic film

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Elliptical encirclement control capable of reinforcing performances for UAVs around a dynamic target

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Defence technology（防务技术） 2024年第2期32卷 104-119页

作者： Fei Zhang Xingling Shao Yi Xia Wendong Zhang National Key Laboratory for Electronic Measurement Technology School of Instrument and ElectronicsNorth University of ChinaTaiyuan030051China

Most researches associated with target encircling control are focused on moving along a circular orbit under an ideal environment free from external ***,elliptical encirclement with a time-varying observation radius,may permit a more flexible and high-efficacy enclosing solution,whilst the non-orthogonal property between axial and tangential speed components,non-ignorable environmental perturbations,and strict assignment requirements empower elliptical encircling control to be more challenging,and the relevant investigations are still *** this line,an appointed-time elliptical encircling control rule capable of reinforcing circumnavigation performances is developed to enable Unmanned Aerial Vehicles(UAVs)to move along a specified elliptical path within a predetermined reaching *** remarkable merits of the designed strategy are that the relative distance controlling error can be guaranteed to evolve within specified regions with a designer-specified convergence ***,wind perturbations can be online counteracted based on an unknown system dynamics estimator(USDE)with only one regulating parameter and high computational *** tool demonstrates that all involved error variables are ultimately limited,and simulations are implemented to confirm the usability of the suggested control algorithm.

关键词： Elliptical encirclement Reinforced performances Wind perturbations UAVs

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Wearable Leg Movement Monitoring System for High-Precision Real-Time Metabolic Energy Estimation and Motion Recognition

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Research 2024年第2期2023卷 417-429页

作者： Jinfeng Yuan Yuzhong Zhang Shiqiang Liu Rong Zhu State Key Laboratory of Precision Measurement Technology and Instruments Department of Precision InstrumentTsinghua UniversityBeijing 100084China

Comprehensive and quantitative assessment of human physical activity in daily life is valuable for healthcare,especially for those who suffer from obesity and neurological disorders or are at high risk of *** wearable devices,e.g.,smartwatches,are insufficient and inaccurate for monitoring highly dynamic limb movements and assessing human ***,we report a new wearable leg movement monitoring system incorporating a custom-made motion sensor with machine learning algorithm to perceive human motion accurately and comprehensively during diverse walking and running *** system enables real-time multimodal perceptions of personal identity,motion state,locomotion speed,and energy expenditure for wearers.A general law of extracting real-time metabolic energy from leg movements is verified although individual gaits show *** addition,we propose a novel sensing configuration combining unilateral lower leg movement velocity with its angular rate to achieve high accuracy and good generalizability while simplifying the wearable *** performances in personal identification(accuracy of 98.7%)and motion-state recognition(accuracy of 93.7%)are *** wearable system also exhibites high-precision real-time estimations of locomotion speed(error of 3.04%to 9.68%)and metabolic energy(error of 4.18%to 14.71%)for new subjects across various time-varying *** wearable system allows reliable leg movement monitoring and quantitative assessment of bodily kinematic and kinetic behaviors during daily activities,as well as safe identity authentication by gait parameters,which would greatly facilitate smart life,personal healthcare,and rehabilitation training.

关键词： smart enable monitoring

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A new method of continuous blood pressure monitoring using multichannel sensing signals on the wrist

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Microsystems & Nanoengineering 2023年第5期9卷 141-150页

作者： Liangqi Wang Shuo Tian Rong Zhu State Key Laboratory of Precision Measurement Technology and Instrument Department of Precision InstrumentTsinghua University100084 BeijingChina

Hypertension is a worldwide health problem and a primary risk factor for cardiovascular *** monitoring of blood pressure has important clinical value for the early diagnosis and prevention of cardiovascular ***,existing technologies for wearable continuous blood pressure monitoring are usually inaccurate,rely on subject-specific calibration and have poor generalization across individuals,which limit their practical ***,we report a new blood pressure measurement method and develop an associated wearable device to implement continuous blood pressure monitoring for new *** wearable device detects cardiac output and pulse waveform features through dual photoplethysmography(PPG)sensors worn on the palmar and dorsal sides of the wrist,incorporating custom-made interface sensors to detect the wearing contact pressure and skin *** detected multichannel signals are fused using a machine-learning algorithm to estimate continuous blood pressure in real *** dual PPG sensing method effectively eliminates the personal differences in PPG signals caused by different people and different wearing *** proposed wearable device enables continuous blood pressure monitoring with good generalizability across individuals and demonstrates promising potential in personal health care applications.

关键词： multichannel continuous method

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Electrostatic generator enhancements for powering IoT nodes via efficient energy management

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Microsystems & Nanoengineering 2024年第2期10卷 143-152页

作者： Zibo Wu Zeyuan Cao Junchi Teng Rong Ding Jiani Xu Xiongying Ye State Key Laboratory of Precision Measurement Technology and Instruments Department of Precision InstrumentTsinghua University100084BeijingChina

Electrostatic generators show great potential for powering widely distributed electronic devices in Internet of Things(IoT)***,a critical issue limiting such generators is their high impedance mismatch when coupled to electronics,which results in very low energy utilization ***,we present a high-performance energy management unit(EMU)based on a spark-switch tube and a buck converter with an RF *** optimizing the elements and parameters of the EMU,a maximum direct current output power of 79.2 mW m^(-2)rps^(-1)was reached for a rotary electret generator with the EMU,achieving 1.2 times greater power output than without the ***,the maximum power of the contact-separated triboelectric nanogenerator with an EMU is 1.5 times that without the *** excellent performance is attributed to the various optimizations,including utilizing an ultralow-loss spark-switch tube with a proper breakdown voltage,adding a matched input capacitor to enhance available charge,and incorporating an RF inductor to facilitate the high-speed energy transfer *** on this extremely efficient EMU,a compact self-powered wireless temperature sensor node was demonstrated to acquire and transmit data every 3.5 s under a slight wind speed of 0.5 m/*** work greatly promotes the utilization of electrostatic nanogenerators in practical applications,particularly in IoT nodes.

关键词： IoT power generator

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Three-dimensional computer holography with phase space tailoring

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PhotoniX 2024年第1期5卷 141-158页

作者： Runze Zhu Lizhi Chen Jiasheng Xiao Hao Zhang Department of Precision Instrument State Key Laboratory of Precision Measurement Technology and InstrumentsTsinghua UniversityBeijing 100084China

Computer holography is a prominent technique for reconstructing customized threedimensional(3D)diffraction ***,the quality of optical reconstruction remains a fundamental challenge in 3D computer holography,especially for the 3D diffraction fields with physically continuous and extensive depth ***,we propose a 3D computer-generated hologram(CGH)optimization framework with phase space *** on phase space analysis of the space and frequency properties in both lateral and axial directions,the intensity of the 3D diffraction field is adequately sampled across a large depth *** sampling ensures the reconstructed intensity distribution to be comprehensively constrained with physical consistency.A physicsinformed loss function is constructed based on the phase space tailoring to optimize the CGH with suppression of vortex *** and optical experiments demonstrate the proposed method significantly enhances the 3D optical reconstructions with suppressed speckle noise across a continuous and extensive depth range.

关键词： Computer-generated holograms Spatial light modulation Threedimensional display Phase space optics

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Non-intrusive Load Monitoring Using Gramian Angular Field Color Encoding in Edge Computing

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Chinese Journal of Electronics 2022年第4期31卷 595-603页

作者： CHEN Junfeng WANG Xue Department of Precision Instrument State Key Laboratory of Precision Measurement Technology and Instrument Tsinghua University

Non-intrusive load monitoring(NILM)can infer the status of the appliances in operation and their energy consumption by analyzing the energy data collected from monitoring devices. With the rapid increase of electric loads in amount and type, the traditional way of uploading all energy data to cloud is facing enormous challenges. It becomes increasingly significant to construct distinguishable load signatures and build robust classification models for NILM. In this paper, we propose a load signature construction method for load recognition task in home scenarios. The load signature is based on the Gramian angular field encoding theory,which is convenient to construct and significantly reduces the data transmission volume of the network. Moreover,edge computing architecture can reasonably utilize computing resources and relieve the pressure of the *** experimental results on NILM datasets demonstrate that the proposed method obtains superior performance in the recognition of household appliances under insufficient resources.

关键词： Non-intrusive load monitoring (NILM) Appliance recognition Gramian angular field (GAF) Edge computing Load signature

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Vehicle-Mounted Polarization Orientation Strategy Considering Inclined Pavement and Occlusion Conditions

IEEE Transactions on Intelligent Vehicles

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IEEE Transactions on Intelligent Vehicles 2024年 1-12页

作者： Wu, Xindong Liu, Jun Shen, Chong Cao, Huiliang Wang, Chenguang Tang, Jun State Key Laboratory of Dynamic Measurement Technology and the School of Instrument and Electronics North University of China Taiyuan China

How to obtain reliable vehicle heading information in the event of GNSS rejection is the key part of the current navigation scheme. In this paper, a vehicle-mounted polarization orientation strategy for sloping roads and occlusion is investigated. For inclined road circumstances, a polarization orientation scheme with tilt compensation ability is designed which is not limited to the field of view of the image polarization compass, and a vision modulation model is provided. On this premise, a solar azimuth region orientation (SAO) strategy is developed, which lowers the measurement error caused by occlusion, and improves the image polarization compass's robustness under complex road conditions. Furthermore, outdoor experiments are delivered to testify the effectiveness of the method. In the vehicle experiment, the root mean square error (RMSE) is reduced by more than 82% when compared to the typical polarization orientation technique. IEEE

关键词： Navigation

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Metasurface designed with quantitative field distributions

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Light(Science & Applications) 2023年第6期12卷 941-942页

作者： Shuai Wang Yuanmu Yang State Key Laboratory for Precision Measurement Technology and Instruments Department of Precision InstrumentTsinghua UniversityBeijing 100084China

A new method for designing metasurfaces has been proposed and demonstrated,which allows for the generation of precise quantitative field *** unique approach involves combining a tandem neural network with an iterative algorithm to optimize the metasurface design,enabling accurate control over the intensity and polarization of the resulting *** strategy is both efficient and robust and has the potential to accelerate the development of metasurface devices with complex functionalities.

关键词： field. surface field

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Light People:*** Mazur speaks about ultrafast optics and education

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Light(Science & Applications) 2024年第3期13卷 402-406页

作者： Chenzi Guo Yang Li Changchun Institute of Optics Fine Mechanics and PhysicsChinese Academy of SciencesChangchunChina State Key Laboratory of Precision Measurement Technology and Instrument Department of Precision InstrumentTsinghua UniversityBeijingChina

*** Mazur is a great influencer over and beyond the optics *** a physicist,he is a pioneer of ultrafast optics and was one of the inventors of colliding-pulse mode-locked *** an educator,he not only gave talks to thousands,but also revolutionized teaching with his globally renowned methodology“Peer Instruction”.As a leader and entrepreneur,he co-founded several companies and was President of Optica(formerly the Optical Society)and currently is the Chair of the Optica ***,Light:Science&Applications talked with *** Mazur about his opinions on research,education and *** full interview video can be found in the Supplementary File.

关键词： optics education companies

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