07 Fakultät Konstruktions-, Produktions- und Fahrzeugtechnik
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/8
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Item Open Access A novel approach to determine decorrelation effect in a dual-beam electronic speckle pattern interferometer(1992) Peng, Xiang; Diao, Hongyan; Zou, Yunlu; Tiziani, Hans J.An intrinsic decorrelation effect in a dual-beam ESPI system for contouring application is quantified by simple image processing techniques incorporating experimental data of speckle patterns. Practical limits for the range of application on contouring an object are also considered from the point of view of automatic fringe analysis. An acceptable degree of decorrelation due to the tilt of illuminating beams has been established.Item Open Access A family of total Lagrangian Petrov-Galerkin Cosserat rod finite element formulations(2023) Eugster, Simon R.; Harsch, JonasThe standard in rod finite element formulations is the Bubnov-Galerkin projection method, where the test functions arise from a consistent variation of the ansatz functions. This approach becomes increasingly complex when highly nonlinear ansatz functions are chosen to approximate the rod's centerline and cross-section orientations. Using a Petrov-Galerkin projection method, we propose a whole family of rod finite element formulations where the nodal generalized virtual displacements and generalized velocities are interpolated instead of using the consistent variations and time derivatives of the ansatz functions. This approach leads to a significant simplification of the expressions in the discrete virtual work functionals. In addition, independent strategies can be chosen for interpolating the nodal centerline points and cross-section orientations. We discuss three objective interpolation strategies and give an in-depth analysis concerning locking and convergence behavior for the whole family of rod finite element formulations.Item Open Access Fast bidirectional vector wave propagation method showcased on targeted noise reduction in imaging fiber bundles using 3D-printed micro optics(2023) Wende, Marco; Drozella, Johannes; Herkommer, AloisItem Open Access Determination of the thermally induced focal shift of processing optics for ultrafast lasers with average powers of up to 525 W(2018) Faas, Sebastian; Förster, Daniel J.; Weber, Rudolf; Graf, ThomasThe continuous increase of the average laser power of ultrafast lasers is a challenge with respect to the thermal load of the processing optics. The power which is absorbed in an optical element leads to a temperature increase, temperature gradients, changing refractive index and shape, and finally causes distortions of the transmitted beam. In a first-order approximation this results in a change of the focal position, which may lead to an uncontrolled change of the laser machining process. The present study reports on investigations on the focal shift induced in thin plano-convex lenses by a high-power ultra-short pulsed laser with an average laser power of up to 525 W. The focal shift was determined for lenses made of different materials (N-BK7, fused silica) and with different coatings (un-coated, broadband coating, specific wavelength coating).Item Open Access Estimation of the depth limit for percussion drilling with picosecond laser pulses(2018) Förster, Daniel J.; Weber, Rudolf; Holder, Daniel; Graf, ThomasItem Open Access General mathematical model for the period chirp in interference lithography(2023) Bienert, Florian; Graf, Thomas; Abdou Ahmed, MarwanItem Open Access Optische Phänomene in Natur und Alltag(2018) Haist, TobiasDieses eBook soll Ihnen helfen, optische Phänomene in Natur und Alltag zu sehen und diese zu verstehen. Es ist als Begleitung (Skript) zur Vorlesung "Optische Phänomene" am Institut für Technische Optik der Universität Stuttgart entstanden. Hauptzielgruppe sind daher Studenten der Physik, des Maschinenbaus und des Studium Generale.Item Open Access Depth from axial differential perspective(2022) Faulhaber, Andreas; Krächan, Clara; Haist, TobiasWe introduce an imaging-based passive on-axis technique for measuring the distance of individual objects in complex scenes. Two axially separated pupil positions acquire images (can be realized simultaneously or sequentially). Based on the difference in magnification for objects within the images, the distance to the objects can be inferred. The method avoids some of the disadvantages of passive triangulation sensors (e.g., correspondence, shadowing), is easy to implement and offers high lateral resolution. Due to the principle of operation it is especially suited for applications requiring only low to medium axial resolution. Theoretical findings, as well as follow-up experimental measurements, show obtainable resolutions in the range of few centimeters for distances of up to several meters.Item Open Access High precision laser supported close range distance measurements(1992) Tiziani, Hans J.Optical methods become useful tools for dimensional measurements. Methods based on triangulation, time of flight, phase measurements and interferometry are used and will be further developed. Multiple wavelength interferometry allows the reduction of the sensitivity by a range extension leading to robust measuring systems. Superheterodyne interferometric techniques based on two wavelength heterodyne interferometry will also be discussed and experimental results will be shown.Item Open Access Optische Interferometrie in der Meßtechnik(1993) Tiziani, Hans J.Die Interferometrie ist ein wichtiges und vielseitiges Werkzeug für die Präzisionsmeßtechnik geworden. Dazu haben die Enwicklung des Lasers als kohärente Lichtquelle und die Methoden der automatischen Streifenauswertung wesentlich beigetragen. Sie tragen einen entscheidenden Anteil am Erfolg beim industriellen Einsatz der Verfahren. Hochauflösende CCD-Arrays, aber auch die rasante Entwicklung von leistungsfähigen Kleinrechnern machen den Einsatz der laseroptischen Verfahren attraktiv. Mehr Information kann aus den Interferogrammen entnommen werden, was zu größeren Meßbereichen und Meßgenauigkeiten führt. Interferometrische Verfahren sind einsatzbar zur hochgenauen Streckenvermessung bzw. der Messung von Verschiebungen bis 50 m und zur Mikrostrukturvermessung mit Auslösungen im Bereich von Nanometern und besser. Interferometrie bietet sich auch zur Qualitätssicherung und Oberflächenvermessung an, aber auch in der Spektroskopie und zur Geschwindigkeitsmessung.