07 Fakultät Konstruktions-, Produktions- und Fahrzeugtechnik
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/8
Browse
110 results
Search Results
Item Open Access Speckleverfahren zur absoluten Abstandsmessung(1987) Hege, Günter; Tiziani, Hans J.Eine ausführliche Untersuchung möglicher Speckleverfahren zur absoluten Abstandsmessung von rauhen Oberflächen hat gezeigt, daß eine axiale Auflösung im Submikrometerbereich nur durch Auswerten der lateralen Specklegeschwindigkeit möglich ist. Hierzu wird bei ruhendem Objekt ein fokussierter Laserstrahl akustooptisch um 0,2 mm periodisch ausgelenkt. Die entstehende Specklebewegung wird von einem Gittersensor erfaßt und von einem Zählprozessor bewertet.Item Open Access Berührungslose optische Echtzeitmesstechnik(1983) Tiziani, Hans J.Es wird über einige Messverfahren der berührungslosen optischen Messtechnik berichtet. Neben dem Einsatz von synthetischen Hologrammen zum Formenvergleich von asphärischen Flächen werden Messverfahren zur Verformungs- und Schwingungsmessung vorgestellt. Der Einsatz fotorefraktiver Kristalle steht noch am Anfang. Verschiedene Anwendungen mit dem BSO-Kristallspeicher werden kurz diskutiert, wie holografische Interferometrie, Konturlinien-Holografie, Speckle-Anwendungen und optische Korrelation. Am Ende wird auch gezeigt, wie eine Dopplershift-Technik zur Geschwindigkeits- und Schwingungsmessung eingesetzt werden kann. Die Ergebnisse werden verglichen mit denen der Doppelpulsholografie.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 Real time metrology with BSO crystals(1982) Tiziani, Hans J.Electro-optical crystals are used for real-time holography, optical data storage, optical information processing and more recently for speckle applications. Many ferro-electric materials were investigated, the Bi12 SiO20 (BSO), a cubic, para-electric and electro-optic material was found to be very useful for real-time holographic interferometry and speckle applications. For the application of the BSO in real-time metrology, the crystals is usually biased with a transverse electric field in the 110 or 100 crystallographic direction. Illuminating the crystal with spatially structured information in the 110 direction as a result of a hologram or speckle pattern, a space charge field is built up, leading to a refractive index variation in the crystal. Double-exposure techniques and time average exposure will be presented for real-time deformation displacement and vibration analysis and for contour line holography using a two-wavelengths method. Young's fringes of double-exposed, or in the time-average recorded speckle patterns will be attractive for real-time deformation displacement and vibration analysis.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 Real-time displacement and tilt analysis by a speckle technique using Bi12SiO20-crystals(1980) Tiziani, Hans J.; Leonhardt, Klaus; Klenk, JürgenStorage of speckle pattern in real time by means of Bi12SiO20-crystals will be reported. Applying the double exposure technique, deformations, displacements as well as tilts can be analysed. The novel speckle technique displays the Young-interference fringes in quasi real time.Item Open Access Application of interferometry and holography for precision measurements(1984) Tiziani, Hans J.Phase measurement techniques are becoming a useful tool for precision measurements. Spatial as well as temporal phase shift methods can be used. Optical testing, where computer analysis of interference fringes is becoming increasing important, will be discussed in connection with testing optical components, microprofiles as well as for testing aspheric surfaces. In addition, methods using heterodyne techniques and real time holography will be described.Item 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, Thomas