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mirror-enhanced scanning light-field microscopy for long-term high-speed 3D imaging with isotropic resolution

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Light(Science & Applications) 2021年第12期10卷 2369-2379页

作者： Bo Xiong Tianyi Zhu Yuhan Xiang Xiaopeng Li Jinqiang Yu Zheng Jiang Yihan Niu Dong Jiang Xu Zhang Lu Fang Jiamin Wu Qionghai Dai Department of Automation Tsinghua UniversityBeijing 100084China Institute for Brain and Cognitive Sciences Tsinghua UniversityBeijing 100084China Beijing Laboratory of Brain and Cognitive Intelligence Beijing Municipal Education CommissionBeijing 100084China State Key Laboratory of Membrane Biology Tsinghua University-Peking University Joint Centre for Life SciencesBeijing Frontier Research Center for Biological StructureSchool of Life SciencesTsinghua UniversityBeijing 100084China Beijing Institute of Collaborative Innovation Beijing 100094China Department of Electronic Engineering Tsinghua UniversityBeijing 100084China

Various biological behaviors can only be observed in 3D at high speed over the long term with low ***-field microscopy(LFM)provides an elegant compact solution to record 3D information in a tomographic manner simultaneously,which can facilitate high photon ***,LFM still suffers from the missing-cone problem,leading to degraded axial resolution and ringing effects after ***,we propose a mirrorenhanced scanning LFM(MiSLFM)to achieve long-term high-speed 3D imaging at super-resolved axial resolution with a single objective,by fully exploiting the extended depth of field of LFM with a tilted mirror placed below *** establish the unique capabilities of MiSLFM,we performed extensive experiments,we observed various organelle interactions and intercellular interactions in different types of photosensitive cells under extremely low light ***,we demonstrated that superior axial resolution facilitates more robust blood cell tracking in zebrafish larvae at high speed.

关键词： resolution mirror field

Design and feedforward control of large-rotation two-axis scan mirror assembly with MEMS sensor integration

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Chinese Journal of Aeronautics 2019年第8期32卷 1912-1922页

作者： Hai HUANG Xintao ZHENG Weipeng LI School of Astronautics Beihang University

As a key component of electro-optical systems, a Two-axis Scan mirror AssemblY(TSAY) is usually used for Line-of-Sight(LOS) precision pointing, tracking, scanning, and stabilizing. Therefore, it is necessary for a TSAY to have a large angular range, high dynamic characteristics, and small mirror surface distortion. Furthermore, vibration from carriers of electro-optical systems, such as spacecraft and airplanes, is inevitable, so it is critical to guarantee the control accuracy of a TSAY under vibration. In this paper, a TSAY prototype is designed and developed. To increase the control bandwidth, structural topology optimization is applied to the TSAY’s elliptical mirror to reduce the moment of inertia, meanwhile keeping surface flatness. A flexible hinge is adopted to achieve a large angular range. To suppress the angular perturbation caused by the base linear vibration, an adaptive feedforward loop with base-integrated Micro-Electro-Mechanical System(MEMS) accelerators is constructed to enhance the TSAY’s feedback loop. Simulation and experimental results show that the TSAY prototype’s two-axis mechanical angular ranges are more than ±3.2°, the mirror surface flatness Root Mean Square(RMS) value is better than 0.04 k, and the closed-loop bandwidth is beyond 330 Hz. These are suitable for most applications. Besides, the angular perturbation caused by the base vibration can be suppressed more than 37.7% with the addition of the adaptive feedforward loop.

关键词： Adaptive feedforward Micro-Electro-Mechanical System accelerator Scan mirror Topological optimization Vibration suppression

Benchmarking visual SLAM methods in mirror environments

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Computational Visual Media 2024年第2期10卷 215-241页

作者： Peter Herbert Jing Wu Ze Ji Yu-Kun Lai School of Computer Science and Informatics Cardiff UniversityAbacws BuildingSenghennydd RdCardiff CF244AGUK School of Engineering Cardiff UniversityQueen’s BuildingsThe ParadeCardiff CF243AAUK

Visual simultaneous localisation and mapping(vSLAM)finds applications for indoor and outdoor navigation that routinely subjects it to visual complexities,particularly mirror *** effect of mirror presence(time visible and its average size in the frame)was hypothesised to impact localisation and mapping performance,with systems using direct techniques expected to perform ***,a dataset,MirrEnv,of image sequences recorded in mirror environments,was collected,and used to evaluate the performance of existing representative *** ORB-SLAM3 and BundleFusion appear to show moderate degradation of absolute trajectory error with increasing mirror duration,whilst the remaining results did not show significantly degraded localisation *** mesh maps generated proved to be very inaccurate,with real and virtual reflections colliding in the reconstructions.A discussion is given of the likely sources of error and robustness in mirror environments,outlining future directions for validating and improving vSLAM performance in the presence of planar *** MirrEnv dataset is available at https://***/10.17035/d.2023.0292477898.

关键词： visual simultaneous localisation and mapping(vSLAM) mirror localisation mapping reflection datase

Far-field vector-diffraction of off-axis parabolic mirror under oblique incidence

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Chinese Physics B 2020年第3期29卷 190-201页

作者： Xia-Hui Zeng Xi-Yao Chen Department of Physics&Electronic Information Engineering Minjiang UniversityFuzhou 350108China

Based on a full vector-diffraction theory, a detailed theoretical study is carried out, aiming at providing a clear insight into the effects of different focusing and off-axis parabola parameters on far-field vector-diffraction properties of an offaxis parabolic mirror in the presence of misalignments of the incoming beam. The physical origin of these effects is also explored. The results show that the far-field intensity profile is altered by the distortion-, coma-, and astigmatism-like aberrations, which are caused by oblique incidence rather than inherent aberrations for the off-axis configuration. The radius of 90% encircled energy also increases but does not change monotonically with incident beam size increasing, or rather,it first decreases and then increases. The focal shift strongly depends on the effective focal length and oblique incidence angle, but it is almost independent of the beam size, which affects the focusing spot patterns. The intensity distribution produces a higher astigmatic image with off-axis angle increasing. Coma-like aberration starts to become dominant with beam size increasing and results in larger curved propagation trajectory. The incident polarization also affects the intensity distribution. The variation in the Strehl ratio with oblique incidence angle strongly depends on the misalignment direction and beam size as well. In addition, we find that the difference in locus between the catacaustic and the diffraction focus in the meridian is small. But the locus of the sagittal foci is obviously different from the locus of the meridian foci and the catacaustic focus. Moreover, the peak intensity of the sagittal focus is maximum, and the ratio of the peak intensity to that in the meridian plane is approximately 1.5. Understanding these effects is valuable for assessing a practical focused intensity and describing the motion of charged particles under a strong electric field in ultraintense laser–matter interaction.

关键词： laser beam focusing off-axis parabolic mirror vector-diffraction theory oblique incidence

Towards automatic freeform optics design: coarse and fine search of the three-mirror solution space

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Light(Science & Applications) 2021年第4期10卷 660-670页

作者： Benqi Zhang Guofan Jin Jun Zhu State Key Laboratory of Precision Measurement Technology and Instruments Departm ent of Precision InstrumentTsinghua UniversityBeijing 100084China

Design of an optical system,whether classic or novel,in the past or the present,requires significant effort from the *** addition to design methods and theories,the designer’s skills and experience in optical system design are particularly important,which may require years of practice to *** diversity and variety of results are limited because of the difficulty,time,and labor costs *** this article,we propose an automatic design method for freeform optics that can achieve a diverse range of three-mirror *** optical specifications and the design constraints are the only inputs required,and a variety of results can be obtained *** output results have various structures and various optical power distributions with high imaging *** implementing the design method,designers can not only realize an overview of the solution space of the three-mirror freeform system,but can also focus on specific designs.

关键词： mirror optics system

Spin-preserving chiral photonic crystal mirror

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Light(Science & Applications) 2020年第1期9卷 1787-1798页

作者： Behrooz Semnani Jeremy Flannery Rubayet Al Maruf Michal Bajcsy Institute for Quantum Computing(IQC) University of WaterlooWaterloo N2L3G1 ONCanada Department of Electrical&Computer Engineering University of WaterlooWaterloo N2L3G1 ONCanada Department of Physics and Astronomy University of WaterlooWaterloo N2L3G1 ONCanada

Chirality refers to a geometric phenomenon in which objects are not superimposable on their mirror *** made of nanoscale chiral elements can exhibit chiroptical effects,such as dichroism for left-and right-handed circularly polarized light,which makes these structures highly suitable for applications ranging from quantum information processing and quantum optics to circular dichroism spectroscopy and molecular *** the same time,strong chiroptical effects have been challenging to achieve even in synthetic optical media,and chiroptical effects for light with normal incidence have been speculated to be prohibited in thin,lossless quasi-two-dimensional ***,we report an experimental realization of a giant chiroptical effect in a thin monolithic photonic crystal *** conventional mirrors,our mirror selectively reflects only one spin state of light while preserving its handedness,with a near-unity level of circular *** operational principle of the photonic crystal mirror relies on guided-mode resonance(GMR)with a simultaneous excitation of leaky transverse electric(TE-like)and transverse magnetic(TM-like)Bloch modes in the photonic crystal *** modes are not reliant on the suppression of radiative losses through long-range destructive interference,and even small areas of the photonic crystal exhibit robust circular *** its simplicity,the mirror strongly outperforms earlier reported structures and,contrary to a prevailing notion,demonstrates that near-unity reflectivity contrast for opposite helicities is achievable in a quasi-two-dimensional structure.

关键词： mirror crystal circular

Inversion/mirror Symmetry-Protected Dirac Cones in Distorted Ruby Lattices

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Chinese Physics Letters 2020年第12期37卷 66-73页

作者： Lei Sun Xiaoming Zhang Han Gao Jian Liu Feng Liu Mingwen Zhao School of Physics and State Key Laboratory of Crystal Materials Shandong UniversityJinan 250100China Department of Materials Science and Engineering University of UtahSalt Lake CityUtah 84112USA Collaborative Innovation Center of Light Manipulations and Applications Shandong Normal UniversityJinan 250358China

The exotic electronic band structures of Ruby and Star lattices,characterized by Dirac cone and nontrivial topology,offer a unique platform for the study of two-dimensional(2D)Dirac *** general,an ideal isotropic Dirac cone is protected by time reversal symmetry and inversion,so that its robustness against lattice distortion is not only of fundamental interest but also crucial to practical *** we systematically investigate the robustness of Dirac cone in a Ruby lattice against four typical lattice distortions that break the inversion and/or mirror symmetry in the transition from Ruby to *** a tight-binding approach,we show that the isotropic Dirac cones and their related topological features remain intact in the rotationally distorted lattices that preserve the inversion symmetry(i-Ruby lattice)or the in-plane mirror symmetry(m-Ruby lattice).On the other hand,the Dirac cones are gapped in the a-and b-Ruby lattices that break both these lattice symmetries or ***,a rotational unitary matrix is identified to transform the original into the distorted *** symmetry-protected Dirac cones were also verified in photonic crystal *** robust Dirac cones revealed in the non-mirror symmetric i-Ruby and non-centrosymmetric m-Ruby lattices provide a general guidance for the design of 2D Dirac materials.

关键词： Dirac symmetry mirror

Study on plasma cleaning of the large-scale first mirror of the charge exchange recombination spectroscopy diagnostic on EAST

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Plasma Science and Technology 2020年第3期22卷 24-33页

作者： Jiao PENG Rong YAN Junling CHEN Rui DING Yingying LI Fali CHONG Institute of Plasma Physics Chinese Academy of SciencesHefei 230031People’s Republic of China Xuzhou University of Technology Xuzhou 221000People’s Republic of China

In the Experimental Advanced Superconducting Tokamak(EAST),the reflectivity of the charge exchange recombination spectroscopy(CXRS)first mirror(FM)was dramatically dropped down to 20%of the original value after the operation of two EAST experimental campaigns from 2014-2015,leading to degradation of the signal intensity of the CXRS diagnostic to an unacceptably low *** radio frequency(RF)plasma cleaning of the CXRS FM with a dimension of 303×81×76 mm3 and a small curvature of 0.008 mm-1 was performed to remove deposits to recover the *** 168 h cleaning by RF plasma,the maximum specular reflectivity of the FM could reach 92%of the original value at 532 nm,making the cleaned CXRS FM eligible to be reused for the CXRS diagnostic in the 2016 EAST *** tests of sputtering polished mirror samples were performed to explore the cleaning uniformity and possible damage to the mirror *** specular reflectivity did not show obvious dependence on locations along the surface with the same cleaning *** measured surface roughness gradually increased with sputtering *** reflectivity remained almost unchanged regardless of different sputtering times and locations,indicating negligible damage to the FM surface even after 100 h *** recontaminated CXRS FM in the 2016 EAST campaign was firstly cleaned for 81 h,and the least reflectivity recovery for areas with relatively thick deposits was only 40%.After continuing cleaning to 147 h,redeposition of the sputtered residual deposits on the FM surface was *** the future for in situ cleaning of the FMs in EAST and ITER,deposits should be removed timely when they are very thin taking into account a very long cleaning time and presumable redeposition of thick and nonuniform deposits.

关键词： first mirror CXRS EAST plasma cleaning cleaning uniformity

mirror,mirror on the wall,who is the best of them all?Artificial intelligence versus gastroenterologists in solving clinical problems

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Gastroenterology Report 2023年第1期11卷 579-581页

作者： Felice Benedicenti Tommaso Pessarelli Mattia Corradi Marco Michelon Nicoletta Nandi Pietro Lampertico Maurizio Vecchi Lucia Scaramella Luca Elli Department of Pathophysiology and Transplantation University of MilanMilanItaly Gastroenterology and Endoscopy Unit Foundation IRCCS Ca’Granda Ospedale Maggiore PoliclinicoMilanItaly Division of Gastroenterology and Hepatology CRC“A.M.and A.Migliavacca”Center for the Study of Liver DiseaseFoundation IRCCS Ca’Granda Ospedale Maggiore PoliclinicoMilanItaly

Introduction Artificial intelligence(AI)is a concept that commonly refers to machines mimicking human cognitive behavior during learning and problem-solving[1].Chatbots are a typical example of an AI system,capable of interacting with humans[2].ChatGPT(OpenAI,San Francisco,CA,USA)[3]is a new-generation chatbot that captures the context and relationship between words in input sequences through multiple layers of self-attention and feedforward neural ***,it predicts the most likely“token”to succeed the previous one based on patterns in its training ***,it is a self-contained system that does not copy existing information[4].

关键词： token neural mirror