Article
Optics
Yibo Zou, JiaQiang Li, Yusheng Ju
Summary: This paper proposes two innovative data fusion methods for reconstructing surfaces produced by directed energy deposition additive manufacturing. These methods provide solutions for microscopic surface reconstruction and representation in multiscales.
Article
Chemistry, Multidisciplinary
Felix Steinmeyer, Dorothee Hueser, Rudolf Meess, Martin Stein
Summary: The novel physical measurement standard (PMS) for roughness measurements on involute gears bridges the gap between roughness measurements on planar surfaces and gear measurements, providing calibrated roughness values for various parameters and allowing measurements with both classic profilometers and gear measurement systems.
APPLIED SCIENCES-BASEL
(2021)
Article
Engineering, Multidisciplinary
Jie Li, Lin Chen, Wenbo Yang, Dun Liu, Xuedong Cao
Summary: This paper proposes a scanning distance measuring interferometer method for accurately measuring the transmitted wavefront of large-aperture flat optics. The feasibility of this method is validated by comparing the results with a phase measuring interferometer.
Article
Optics
Lipeng Wan, Tianbao Yu, Daomu Zhao, Wolfgang Loffler
Summary: By using a conventional arrayed image sensor and 2D Fourier analysis, it is possible to resolve sub-micrometer periodic patterns with a resolution far beyond the Nyquist limit set by the pixel size. This method also enables wavelength sensing with high resolving power.
LASER & PHOTONICS REVIEWS
(2023)
Article
Physics, Applied
Muhammad Avicenna Naradipa, Prayudi Lianto, Gilbert See, Arvind Sundarrajan, Andrivo Rusydi
Summary: Metallic contaminants in complex heterostructures play important roles in determining physical properties and devices' performance. This study investigates the optical properties and influence of metal contaminants on device performance in polyimide heterostructures using spectroscopic ellipsometry and finite-difference time-domain calculations.
APPLIED PHYSICS LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Long Wang, Ruimin Xue, Wenhai Jiao, Liang Hu, Jianping Chen, Guiling Wu
Summary: This article presents a time-delayed local two-way optical frequency comparison scheme with improved stability and verifies its performance through theoretical analysis and experiments. The results show that the fractional instability of the optical frequency comparison over a 50-km fiber link can be significantly reduced. Furthermore, the effect of inhomogeneous phase noise along the fiber link is also modeled and experimentally verified for the first time.
JOURNAL OF LIGHTWAVE TECHNOLOGY
(2022)
Article
Materials Science, Coatings & Films
Brodan Richter, Tim Radel, Frank E. Pfefferkorn
Summary: Poor fatigue life caused by rough and irregular surfaces is a significant challenge for additive manufacturing. Laser polishing, using a laser to irradiate, melt, and smooth the surface, is a solution. This study examines the laser polishing of cobalt-chromium samples produced through laser powder bed fusion. The influence of various laser processing parameters on surface smoothing is analyzed, with laser power playing the most important role. The starting surface condition and variability caused by particle adherence are also discussed. This work provides an important overview of processing aspects for advancing the commercialization of additive manufacturing technology in part finishing.
SURFACE & COATINGS TECHNOLOGY
(2022)
Article
Engineering, Industrial
J. H. T. Chan, D. Tang, J. Williamson, H. Martin, A. J. Henning, X. Jiang
Summary: This article explores the potential for miniaturized metasurface-based optical sensors, specifically a chromatic confocal sensor for position measurement. The design and fabrication process of metasurfaces based on truncated-waveguide type meta-atoms is described, and experimental evaluation confirms their potential as a new generation of miniature, lightweight, low-cost optical sensors for future data-driven manufacturing technologies.
CIRP ANNALS-MANUFACTURING TECHNOLOGY
(2023)
Article
Optics
Niladri Modak, Swain Ashutosh, Shyamal Guchhait, Sayantan Das, Alok Kumar Pan, Nirmalya Ghosh
Summary: This study reveals the inherent non-separability of optical beam shifts and connects it to wave phenomena and metrological applications. The findings also indicate the practical impact of optical beam shifts on metrology and the generation of high-quality non-separable states of classical light fields.
LASER & PHOTONICS REVIEWS
(2023)
Article
Optics
Lei Huang, Lukas Lienhard, Tianyi Wang, Francois Polack, Josep Nicolas, Steven Hulbert, Mourad Idir
Summary: We have developed the Multi-Pitch Nano-accuracy Surface Profiler (MPNSP) to characterize strongly curved X-ray mirrors for diffraction-limited soft X-ray focusing. The measurement process involves forward-and-backward scans along the tangential direction at multiple pitch angles. Our research and development aim to measure strongly curved X-ray mirrors with a large slope range while maintaining high measurement repeatability and self-consistency.
OPTICS AND LASERS IN ENGINEERING
(2023)
Article
Optics
Hugo Jonquiere, Laurent M. Mugnier, Renaud Mercier-Ythier
Summary: This study revisits Surrel's work on harmonic insensitive phase shift algorithms in deflectometry and demonstrates that DFT algorithms are suitable for combating print-through phenomenon and performing better in terms of noise. Through experiments and simulations, it shows that carefully chosen DFT algorithms can improve high spatial frequency measurement capabilities of a deflectometry setup.
OPTICS AND LASERS IN ENGINEERING
(2021)
Article
Optics
Martin Cizek, Lenka Pravdova, Tuan Minh Pham, Adam Lesundak, Jan Hrabina, Josef Lazar, Thomas Pronebner, Elke Aeikens, Jorg Premper, Ondrej Havlis, Radek Velc, Vladimir Smotlacha, Lada Altmannova, Thorsten Schumm, Josef Vojtech, Anton Niessner, Ondrej Cip
Summary: Challenging experiments in fundamental physics require highly coherent optical frequency references with suppressed phase noise. This study presents a path to realize a delocalized optical frequency reference for spectroscopy of the isomeric state of Thorium-229 atom, which is crucial for the development of the next generation nuclear clock. A 235 km long phase-coherent stabilized cross-border fibre link has been established, connecting two metrology laboratories and using optical frequency combs to discipline highly-coherent lasers. The deployment of digital signal processing techniques and measurement of phase noise power spectral density demonstrate the functionality and reliability of the link.
Article
Engineering, Electrical & Electronic
Chen Wang, Xianyu Meng, Grzegorz Krolczyk, Heming Wei
Summary: Quantitative characterization and uncertainty evaluation of areal step height are increasingly important in semiconductor manufacturing. Traditional methods face problems of repeatability and reproducibility. To address this issue, we propose a cluster-based method that converts step characterizations into Euclidean distances through data reconstruction and K-means clustering, eliminating the need for plane fitting.
IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT
(2022)
Article
Chemistry, Analytical
Claudia Daffara, Sara Mazzocato
Summary: This study demonstrates the use and usefulness of surface metrology based on scanning conoscopic holography for monitoring treatments on a Venetian masterpiece. Through statistical analysis and the complementary use of multiple parameters, the noninvasive nature of the treatment on the painting surface was confirmed, and the use of these parameters in the field of cultural heritage science was discussed.
Article
Optics
Yuanyuan Sun, Yihan Wang, Daodang Wang, Stanley Pau, Rongguang Liang
Summary: We proposed a Wollaston-prism-based snapshot phase-shifting diffraction phase microscope (WP-SPDPM) for low-coherence snapshot quantitative phase imaging and videography. The system utilizes a Wollaston prism to separate two orthogonally linearly polarized beams, and a pinhole is used for the reference beam. By simultaneously acquiring four phase-shifted interferograms with a polarization camera, a high spatial resolution phase map is accurately retrieved. The WP-SPDPM is a powerful tool for accurate and robust quantitative phase measurement with a significant potential for real-time phase imaging.
OPTICS AND LASERS IN ENGINEERING
(2023)
Editorial Material
Instruments & Instrumentation
Andreas Fischer
TM-TECHNISCHES MESSEN
(2022)
Article
Instruments & Instrumentation
Yannik Schaedler, Michael Sorg, Andreas Fischer
Summary: This paper proposes a measurement approach for the regional coverage of power demand and the influence of storage systems, which can be used to estimate storage parameters and determine storage capacity.
TM-TECHNISCHES MESSEN
(2022)
Article
Instruments & Instrumentation
Axel von Freyberg, Marina Terlau, Dirk Stoebener, Andreas Fischer
Summary: For small quantities of forming large metal sheets, incremental sheet forming is a cost-effective alternative to deep drawing. However, tool deflections can cause increased form deviations. By measuring the tool deflection in real time with an optical multi-sensor system, the geometric deviations of the manufactured part can be minimized. The proposed system uses a large number of inexpensive sensors to measure the angle to a point light source on the tool, allowing for accurate calculation of the tool position in the three-dimensional manufacturing volume.
TM-TECHNISCHES MESSEN
(2023)
Article
Instruments & Instrumentation
Daniel Gleichauf, Felix Oehme, Ann-Marie Parrey, Michael Sorg, Nicholas Balaresque, Andreas Fischer
Summary: Thermographic flow visualization is a well-established imaging method for localizing laminar-turbulent flow transition on wind turbines. This study investigates the potential of using this method to detect changes in flow transition position caused by wind gusts. It is proven through theory and experiments on real wind turbines that flow state changes can be detected within seconds using thermographic flow visualization. This opens up possibilities for analyzing unsteady flow phenomena on wind turbines.
TM-TECHNISCHES MESSEN
(2023)
Article
Energy & Fuels
Felix Oehme, Daniel Gleichauf, Nicholas Balaresque, Michael Sorg, Andreas Fischer
Summary: This study presents and verifies a thermographic detection and localization method for unsteady flow separation on an operating wind turbine. The method utilizes an infrared thermographic measurement approach to achieve high spatial resolution. By analyzing the thermodynamic response behavior of the surface temperature, a two-step signal processing approach is proposed. The results show that the method successfully detects and localizes unsteady flow separation with high resolution.
FRONTIERS IN ENERGY RESEARCH
(2022)
Article
Optics
Andreas Fischer
Summary: By evaluating the speckle contrast or image auto-correlation, the roughness parameter Sq can be measured. This study derives the measurement uncertainty limits for four sources of uncertainty, including surface roughness, speckle noise, quantum shot noise, and camera noise. The results show that speckle noise is the largest contributor to measurement uncertainty, leading to a minimal achievable relative uncertainty of 1%-2% for Sq = (0.03 - 0.15).
Article
Engineering, Industrial
Andreas Fischer, Andreas Tausendfreund, Raphael Hess, Timm Petersen, Dirk Stoebener
Summary: In electrical discharge machining, measuring the induced mechanical stress is crucial for developing process models to enhance the fatigue strength of the machined part. High-speed digital speckle photography is introduced to measure the load fields on the workpiece side with a lateral displacement resolution of 28 nm and spatiotemporal resolution of 29 μm and 40 μs, respectively. This allows for the temporal resolution of the load effects of individual 100 μs short discharge pulses and characterizes the occurring spatial load inhomogeneities and their dynamics, enriching our understanding of the machining process.
CIRP ANNALS-MANUFACTURING TECHNOLOGY
(2023)
Article
Engineering, Mechanical
Bjoern Espenhahn, Lukas Schumski, Daniel Meyer, Dirk Stoebener, Andreas Fischer
Summary: Investigations on coolant flow in a running grinding machine aim to understand the interaction between fluid, workpiece, and tool and correlate flow dynamics with cooling efficiency. Using Particle Image Velocimetry (PIV), flow measurements of metal working fluid (MWF) are visualized. Without a workpiece, the measurements reveal the deflection and entrainment of MWF with the tool, indicating a maximum cooling capacity at 80% of the tool's circumferential velocity. By implementing an optical transparent workpiece, flow measurements in the decreasing gap between the workpiece and grinding wheel reveal a deceleration stagnation before the contact zone, providing the necessary data to understand flow-based cooling mechanisms in grinding processes.
FLOW MEASUREMENT AND INSTRUMENTATION
(2023)
Article
Materials Science, Characterization & Testing
Friederike Jensen, Josefa Feline Jerg, Michael Sorg, Andreas Fischer
Summary: Defects such as voids in wind turbine blades affect premature rain erosion, particularly at the leading edge. Active thermography enables non-contact in-situ inspection of leading edges. Thermographic investigations reveal that sub-surface defects make the blades more susceptible to erosion, and erosion onset depends on defect depth. The development from sub-surface to surface defects can be visualized, allowing damage stage to be assigned to an erosion stage.
NDT & E INTERNATIONAL
(2023)
Article
Instruments & Instrumentation
Alina Ross, Nicholas Balaresque, Andreas Fischer
Summary: Cup anemometers are widely used in the wind energy industry, and their performance is classified based on the IEC 61400-50-1:2022 standard. However, this standard does not adequately consider the effects of temperature and density.
TM-TECHNISCHES MESSEN
(2023)
Article
Multidisciplinary Sciences
Daniel Niederer, Natalie Mengis, Max Wiessmeier, Matthias Keller, Wolf Petersen, Andree Ellermann, Tobias Drenck, Christian Schoepp, Amelie Stoehr, Andreas Fischer, Andrea Achtnich, Raymond Best, Lucia Pinggera, Matthias Krause, Daniel Guenther, Maren Janko, Christoph Kittl, Turgay Efe, Karl-Friedrich Schuettler, Lutz Vogt, Michael Behringer, Thomas Stein
Summary: Exploratory moderation-mediation models were used to identify various functional factors that contribute to self-report functional abilities after ACL reconstruction. Pain was found to be the strongest factor in the early rehabilitation phase, while time since reconstruction played a major role in the early and mid phases. Other variables such as COVID-19-associated restrictions and rehabilitation dosage also had an impact.
SCIENTIFIC REPORTS
(2023)
Article
Chemistry, Analytical
Marina Terlau, Axel von Freyberg, Dirk Stoebener, Andreas Fischer
Summary: In order to address the large geometric deviations caused by the deflection of the forming tool, it is necessary to measure the tool tip position in real time. A multi-sensor system based on triangulation is used to accurately measure the tool tip position.
Article
Optics
Leon Schweickhardt, Andreas Tausendfreund, Dirk Stoebener, Andreas Fischer
Summary: Digital speckle photography is a displacement field measurement method using laser speckles as markers. It provides a fast and precise measurement with only one reference image, making it suitable for in-process measurements in manufacturing engineering. The method's accuracy is affected by higher-order displacement gradients, which has been studied through simulations using isotropic Gaussian surface topographies and digital image correlation. The results show that the random error is proportional to the first-order displacement gradient, while the systematic error is influenced by the evaluation algorithm, second-order gradient, and subset size. The findings from the simulative study suggest that the relative error caused by displacement gradients in practical displacement measurements is below 2.5%.
JOURNAL OF THE EUROPEAN OPTICAL SOCIETY-RAPID PUBLICATIONS
(2023)
Article
Green & Sustainable Science & Technology
Paula Helming, Alex Intemann, Klaus-Peter Webersinke, Axel von Freyberg, Michael Sorg, Andreas Fischer
Summary: The size of wind turbines has increased, emphasizing the importance of efficient structural health monitoring. A terrestrial laser scanner (TLS) is used to measure blade deformation and tower-blade tip clearance, allowing for effective monitoring of wind turbine structures.
WIND ENERGY SCIENCE
(2023)
Article
Engineering, Manufacturing
Lukas Schumski, Nikolai Guba, Bjoern Espenhahn, Dirk Stobener, Andreas Fischer, Daniel Meyer
Summary: The free jet and the interaction area during grinding were analyzed using new measurement techniques, which allowed for the assessment of the free jet geometry and velocities, velocity distribution, and the amount of metalworking fluid (MWF) in the interaction area. The main findings indicated that the free jet velocity remained constant, the velocity distribution was influenced by the flow rate, and a new image parameter (black pixel fraction) was derived for evaluating the MWF supply.
JOURNAL OF MANUFACTURING AND MATERIALS PROCESSING
(2022)
