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Adaptive-optical 3D microscopy for microfluidic multiphase flows

Light(Advanced Manufacturing) 2024年第3期5卷 105-119页

作者： Clemens Bilsing Erik Nützenadel Sebastian Burgmann Jürgen Czarske Lars Büttner Laboratory of Measurement and Sensor System Techniques TUD Dresden University of Technology01069 DresdenGermany Chair of Fluid Mechanics Bergische Universitát Wuppertal42119 WuppertalGermany BIOLAS Laboratory of Measurement and Sensor System Techniques01069 DresdenGermany

measurements based on optical microscopy can be severely impaired if the access exhibits variations of the refractive *** the case of fluctuating liquid-gas boundaries,refraction introduces dynamical aberrations that increase the measurement *** is prevalent at multiphase flows(***,film flows)that occur in many technical applications as for example in coating and cleaning processes and the water management in fuel *** this paper,we present a novel approach based on adaptive optics for correcting the dynamical aberrations in real time and thus reducing the measurement *** shape of the fluctuating water-air interface is sampled with a reflecting light beam(Fresnel Guide Star)and a Hartmann-Shack sensor which makes it possible to correct its influence with a deformable mirror in a closed ***-dimensional flow measurements are achieved by using a double-helix point spread *** measure the flow inside a sessile,oscillating 50-μl droplet on an opaque gas diffusion layer for fuel cells and show that the temporally varying refraction at the droplet surface causes a systematic underestimation of the flow field magnitude corresponding to the first droplet eigenmode which plays a major role in their detachment *** demonstrate that the adaptive optics correction is able to reduce this systematic ***,the adaptive optics system can pave the way to a deeper understanding of water droplet formation and detachment which can help to improve the efficiency of fuels cells.

关键词： Double-Helix point spread function Adaptive optics Particle tracking velocimetry Aberration correction Depth-resolving microscopy Closed-loop control

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Uncertainty Quantification of Super-Resolution Flow Mapping in Liquid Metals using Ultrasound Localization Microscopy

arXiv

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arXiv 2024年

作者： Weik, David Dou, Zehua Räbiger, Dirk Vogt, Tobias Eckert, Sven Czarske, Jürgen Büttner, Lars Laboratory of Measurement and Sensor System Techniques TU Dresden Dresden01069 Germany Department of Magnetohydrodynamics Helmholtz-Zentrum Dresden-Rossendorf Dresden01314 Germany

Convection of liquid metals drives large natural processes and is important in technical processes. Model experiments are conducted for research purposes where simulations are expensive and the clarification of open questions requires novel flow mapping methods with an increased spatial resolution. In this work, the method of Ultrasound Localization Microscopy (ULM) is investigated for this purpose. Known from microvasculature imaging, this method provides an increased spatial resolution beyond the diffraction limit. Its applicability in liquid metal flows is promising, however the realization and reliability is challenging, as artificial scattering particles or microbubbles cannot be utilized. To solve this issue an approach using nonlinear adaptive beamforming is proposed. This allowed the reliable tracking of particles of which super-resolved flow maps can be deduced. Furthermore, the application in fluid physics requires quantified results. Therefore, an uncertainty quantification model based on the spatial resolution, velocity gradient and measurement parameters is proposed, which allows to estimate the flow maps validity under experimental conditions. The proposed method is demonstrated in magnetohydrodynamic convection experiments. In some occasions, ULM was able to measure velocity vectors within the boundary layer of the flow, which will help for future in-depth flow studies. Furthermore, the proposed uncertainty model of ULM is of generic use in other applications. © 2024, CC BY.

关键词： Magnetohydrodynamics

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Adaptive Holographic Optogenetic Illumination for Human Neural Network Analysis

Adaptive Holographic Optogenetic Illumination for Human Neur...

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Digital Holography and Three-Dimensional Imaging, DH 2022

作者： Schmieder, F. Habibey, R. Busskamp, V. Czarske, J.W. Büttner, L. Laboratory of Measurement and Sensor System Techniques TU Dresden Dresden01062 Germany Universitäts-Augenklinik Bonn University of Bonn Ernst-Abbe-Straße 2 Bonn53127 Germany TU Dresden Dresden Germany Cluster of Excellence Physics of Life TU Dresden Germany

A two-wavelength optogenetic stimulation platform with high spatiotemporal resolution and inherent aberration correction is presented. By stimulating single neurons, we investigated the temporal evolution of connectiv... 详细信息

ISBN: (纸本)9781957171128

关键词： Stem cells

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Uncertainty Budget in the Ldv-Based Radius measurement

SSRN

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SSRN 2024年

作者： Shi, Shengyu Wu, Yongwei Li, Xiang Yin, Xiaochun Kuschmierz, Robert Czarske, Jürgen National Engineering Research Center of Novel Equipment for Polymer Processing Key Laboratory of Polymer Processing Engineering Ministry of Education Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced Manufacturing School of Mechanical and Automobile Engineering South China University of Technology Guangzhou510640 China Laboratory for Measurement and Sensor System Techniques Technische Universität Dresden Dresden01069 Germany

Laser Doppler velocimeter (LDV) allows for the measurement of the lateral velocity of a rotating cylindrical workpiece, thus, enabling the absolute radius measurement, showing great application prospect. However, several adverse factors exist that decrease the measurement accuracy, for example, the variation of the fringe spacing, the variation of the rotating frequency, the spindle error motions, and the Doppler frequency estimation, which, unfortunately, have been seldom studied. In this context, this paper comprehensively analyzes the uncertainty in the LDV-based radius measurement. First, we construct an LDV sensor and calibrate its fringe spacing. Then, the LDV-based radius measurement is modeled as an algebraic equation, suggesting that the radius is indirectly measured from several input quantities, including the Doppler frequency, the fringe spacing, and the rotation frequency, each of which owns an input uncertainty, propagating into the measurement result. Ultimately, a detailed budget for the measurement uncertainty is provided. © 2024, The Authors. All rights reserved.

关键词： Laser Doppler velocimeters

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Planar mapping of the liquid fraction of froth using ultrasound Flächige Darstellung des Wassergehaltes von Schaum mittels Ultraschall 21

Planar mapping of the liquid fraction of froth using ultraso...

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21. ITG/GMA-Fachtagung sensoren und Messsysteme - 21st ITG/GMA Conference on sensors and Measuring systems

作者： Emmerich, Hannes Knüpfer, Leon Trtik, Pavel Eckert, Kerstin Heitkam, Sascha Starke, Eric Weik, David Büttner, Lars Czarske, Jürgen Technical University Dresden Laboratory of Measurement and Sensor System Techniques Dresden01069 Germany Helmholtz-Zentrum Dresden-Rossendorf Institute of Fluid Dynamics Dresden01328 Germany Paul Scherrer Institut Laboratory for Neutron Scattering and Imaging Villigen5232 Switzerland Technical University Dresden Institute of Process Engineering and Environmental Technology Dresden01069 Germany SICK Engineering GmbH Bergener Ring 27 Ottendorf-Okrilla01458 Germany

ISBN: (纸本)9783800758364

Flotation processes are essential processes for resource separation, the monitoring of which can save vast amounts of water and energy. To control them, it is necessary to measure the phase fractions present in the froth. Currently, no suitable measurement method exists that can be easily integrated into the existing process and has a penetration depth of more than 5 cm. Therefore, in this paper we present a measurement system for determining the liquid distribution in foam using ultrasound. To counteract the strong attenuating effect of the foam on the ultrasound, we use low-frequency probes with a center frequency of 135 kHz. Electrodes determine an integral liquid fraction by conductivity measurement. Within a liquid range of 0.17 ·10−2 to 0.82 ·10−2, the measurement system was first calibrated for a penetration depth of 9.2 cm and validated by simultaneous neutron imaging. An absolute and relative measurement uncertainty of 0.23 ·10−2 and 42.5 % was the respective result. A resolution of 7.5 mm in the axial, 13 mm in lateral direction and 1 Hz in time were obtained. In a dynamic inhomogeneous case, the measurement system was additionally validated for a use case. This investigation represents a first step towards process optimization in flotation processes. © VDE VERLAG GMBH ∙ Berlin ∙ Offenbach.

关键词： Ultrasonics

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Transmission of structured light through a multimode fiber using digital optical phase conjugation

Transmission of structured light through a multimode fiber u...

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Digital Holography and Three-Dimensional Imaging, DH 2019

作者： Büttner, Lars Thümmler, Martin Koukourakis, Nektarios Czarske, Jürgen Technische Universität Dresden Faculty of Electrical and Computer Engineering Laboratory of Measurement and Sensor System Techniques Helmholtzstraße 18 Dresden01069 Germany

The generation of a localized fringe system through a multimode fiber at a certain distance to the distal fiber end without additional relay optics is reported. Perspectives for application in measurement are given. &... 详细信息

ISBN: (纸本)9781943580590

关键词： Multimode fibers

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Electrolyte spraying within H2 bubbles during water electrolysis

arXiv

引用

arXiv 2024年

作者： Bashkatov, Aleksandr Bürkle, Florian Demirkır, Çayan Ding, Wei Sanjay, Vatsal Babich, Alexander Yang, Xuegeng Mutschke, Gerd Czarske, Jürgen Lohse, Detlef Krug, Dominik Büttner, Lars Eckert, Kerstin Institute of Fluid Dynamics Helmholtz-Zentrum Dresden-Rossendorf Bautzner Landstrasse 400 Dresden01328 Germany Physics of Fluids Group Max Planck Center for Complex Fluid Dynamics MESA+ Institute J. M. Burgers Centre for Fluid Dynamics University of Twente P.O. Box 217 Enschede7500AE Netherlands Laboratory for Measurement and Sensor System Techniques Faculty of Electrical and Computer Engineering Technische Universität Dresden Helmholtzstr. 18 Dresden01069 Germany Max Planck Institute for Dynamics and Self-Organization Am Fassberg 17 Göttingen37077 Germany Institute of Process Engineering and Environmental Technology Technische Universität Dresden Dresden01062 Germany

Electrolytically generated gas bubbles can significantly hamper the overall electrolysis efficiency. Therefore it is crucial to understand their dynamics in order to optimise water electrolyzer systems. Here we demonstrate a distinct transport mechanism where coalescence with microbubbles drives electrolyte droplets, resulting from the fragmentation of the Worthington jet, into the gas phase during hydrogen evolution reaction, both in normal and microgravity environments. This indicates that the H2 bubble is not only composed of hydrogen gas and vapor but also includes electrolyte fractions. Reminiscent of bursting bubbles on a liquid-gas interface, this behavior results in a flow inside the bubble, which is further affected by Marangoni convection at the gas-electrolyte interface, highlighting interface mobility. In the case of electrode-attached bubbles, the sprayed droplets form electrolyte puddles at the bubble-electrode contact area, affecting the dynamics near the three-phase contact line and favoring bubble detachment from the electrode. The results of this work unravel important insights into the physicochemical aspects of electrolytic gas bubbles, integral for optimizing gas-evolving electrochemical systems. Besides, our findings are essential for studying the limits of jet formation and rupture relevant to acid mist formation in electrowinning, generation of sea spray aerosols, impact of droplets on liquid surfaces, etc. © 2024, CC BY.

关键词： Hydrogen evolution reaction

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Ultrasound Imaging in Hot Melts with Time Reversal Virtual Arrays

Ultrasound Imaging in Hot Melts with Time Reversal Virtual A...

引用

IEEE International Ultrasonics Symposium

作者： Richard Nauber Lars Buttner Jurgen Czarske Laboratory of Measurement and Sensor System Techniques Faculty of Electrical and Computer Engineering TU Dresden Dresden Germany

Industrial processes, such as silicon crystal growth for the photovoltaics industry, continuous steel casting, plastics and aluminum extrusion, involve hot, opaque liquids. Noninvasive inline monitoring is desirable to improve the quality of the products and the resource efficiency of the process. However, ultrasound-based imaging methods are severely limited by the transducer's resistance to high *** propose a method for imaging hot liquids using an ultrasound phased-array probe attached to a multi-mode waveguide (MMWG) for thermal decoupling. The complex wave propagation through the MMWG leads to a strongly distorted image, which is addressed with a time reversal virtual array (TRVA). The TRVA method performs a system identification and compensates the distortions based on the time-reversal invariance of sound propagation. We demonstrate planar imaging with this method in liquid tin at ≈ 300℃, well above the destruction limit of the transducers. The characterization of the imaging properties of the system showed a spatial resolution better than 1.6 mm. The proposed method for imaging through MMWG may open a new window into a variety of technical and industrial processes involving hot, opaque liquids in harsh environments.

关键词： Imaging Ultrasonic imaging Liquids Acoustics Tin Temperature measurement Ultrasonic variables measurement

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OS03.7.A AUTOFLUORESCENCE BASED RECOGNITION OF BRAIN TUMORS WITH A CONVOLUTIONAL NEURAL NETWORK

引用

Neuro-Oncology 2023年第SUPPLEMENT_2期25卷 ii15-ii16页

作者： Richter, S Dremel, J Wang, T Eyüpoglu, I Czarske, J Kirsche, K Kuschmierz, R Polanski, W Uckermann, O University Hospital Carl Gustav Carus at the TU Dresden Department of Neurosurgery Dresden Germany Else Kröner-Fresenius Center for Digital Health Dresden Germany TU Dresden Laboratory of Measurement and Sensor System Techniques Dresden Germany TU Dresden Faculty of Medicine Carl Gustav Carus Division of Medical Biology Department of Psychiatry and Psychotherapy Dresden Germany

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Optical tip vibration measurement in CNC milling machines 19

Optical tip vibration measurement in CNC milling machines

引用

19th International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2019

作者： Zhang, Hao Kuschmierz, Robert Löser, Michael Ihlenfeldt, Steffen Shi, Shengyu Czarske, Jürgen Laboratory of Measurement and Sensor System Techniques Technische Universität Dresden Dresden01062 Germany Institute of Mechatronic Engineering TU Dresden Dresden Germany Key Laboratory of Polymer Processing Engineering of Ministry of Education National Engineering Research Center of Novel Equipment for Polymer Processing School of Mechanical and Automobile Engineering South China University of Technology Guangzhou510640 China

ISBN: (纸本)9780995775145

Vibrations of milling tools, especially of slender end mills, are one of the main contributors to shape deviations of machined work pieces in the milling process. For milling machines, the vibration behaviour depends on the spindle speed and end mill properties. Numerical models can help to predict vibrational behaviour and reduce vibrations. This requires measuring the frequency response of the end mill. We propose a system for investigating the frequency response function inside of a milling machine under different rotational speeds. It consists of an automated impact unit generating vibrations with a known force and a novel Mach-Zehnder interferometer based sensor. The sensor enables simultaneous axial distance and lateral velocity measurement at fast rotating surfaces with submicron uncertainty and measurement rates up to 50 kHz. The bidirectional vibration frequencies are estimated by the signal-processing algorithm depending on the geometric relationship of the displacement in two directions. © 2019 European Society for Precision Engineering and Nanotechnology, Conference Proceedings - 19th International Conference and Exhibition, EUSPEN 2019. All rights reserved.

关键词： Frequency response

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