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 Double pulse-electronic speckle interferometry (DP-ESPI)(1993) Pedrini, Giancarlo; Tiziani, Hans J.The double-pulsed speckle interferometry method is very much simpler than the double pulse holographic interferometry and allows a quick analysis of the interferograms without the development of films and hologram reconstructions. It is thus well suited to be used in an industrial environment. Using 3 cameras and three illumination directions (in order to have three sensitivi ty vectors) it is possible to measure 3-D deformations.Item Open Access Double-pulse electronic speckle interferometry for vibration analysis(1994) Pedrini, Giancarlo; Tiziani, Hans J.We describe a double-pulse electronic-speckle-interferometry system. Two separate speckle patterns of an object being tested are recorded within a few microseconds with a CCD camera. Their two images are stored in a frame grabber. The fringes obtained from subtraction are quantitatively analyzed by the spatial-carrier phase-shift method. Using three directions of illumination and one direction of observation, one can record at the same time all the information necessary for the reconstruction of the three-dimensional deformation vector. Applications of this system for measuring the rotating objects are discussed for the case for which a derotator needs to be used. Experimental results are presented.Item Open Access A simplified multi-wavelength ESPI contouring technique based on a diode laser system. 2, Automatic fringe analysis(1993) Peng, Xiang; Zou, Yunlu; Pedrini, Giancarlo; Tiziani, Hans J.A quantitative fringe analyses of interference patterns generated by a multi-wavelength laser diode ESPI contouring system is discussed. The goal is the accurate determination of the topography of an object with steep surface. The phase change related to the surface geometry is calculated with phase-shifting techniques and the results with different contour sensitivities are presented. Some limitations of this ESPI contouring system are also considered from the point of view of practical applications.Item Open Access Double pulse-electronic speckle interferometry(1994) Pedrini, Giancarlo; Tiziani, Hans J.The double-pulsed speckle interferometry method is very much simpler than the double pulse holographic interferometry and allows a quick analysis of the interferograms without the development of films and hologram reconstructions. It is thus well suited for industrial applications. The system can be extended to determine the three components of the deformation by illuminating the object from three directions and by observing with three cameras. Double-pulsed ESPI can be used to measure rotating objects with an optical derotator which compensates the rotation of the object optically.Item Open Access Derivatives obtained directly from displacement data(1994) Zou, Yunlu; Pedrini, Giancarlo; Tiziani, Hans J.Two flexible shearing methods taking the derivative information directly from the data for displacement measurement are reported. The displacement information is obtained using a holographic recording directly on a CCD (charge-coupled-device) chip. Besides the advantage of taking the displacement information and the derivative information from a same set of data, other characteristics of these methods are that the derivative sensitivity can be controlled after recordings and displacement derivatives along arbitrary directions can be chosen easily. One method is based on the electronic recording which keeps the complex amplitudes of the wave fronts in a computer. The other needs only the phase modulo 2π of the displacement.Item Open Access Scatter-plate microscopy with spatially coherent illumination and temporal scatter modulation(2021) Ludwig, Stephan; Ruchka, Pavel; Pedrini, Giancarlo; Peng, Xiang; Osten, WolfgangScatter-plate microscopy (SPM) is a lensless imaging technique for high-resolution imaging through scattering media. So far, the method was demonstrated for spatially incoherent illumination and static scattering media. In this publication, we demonstrate that these restrictions are not necessary. We realized imaging with spatially coherent and spatially incoherent illumination. We further demonstrate that SPM is still a valid imaging method for scatter-plates, which change their scattering behaviour (i.e. the phase-shift) at each position on the plate continuously but independently from other positions. Especially we realized imaging through rotating ground glass diffusers.Item Open Access Contouring by electronic speckle pattern interferometry employing divergent dual beam illumination(1994) Zou, Yunlu; Pedrini, Giancarlo; Tiziani, Hans J.For contouring of large object surfaces by means of electronic speckle pattern interferometry divergent illuminations were used. A method to shift dual illumination beams was employed to obtain contour fringes. The relationship between the fringes and object depth does not have the same form as in the case of collimated illuminations. It shows that the original measurement data can be corrected. Theoretical analysis and experimental results are presented which are in agreement with each other.Item Open Access Remote laboratory for digital holographic metrology(2011) Wilke, Marc; Situ, Guohai; Aleksenko, Igor; Riedel, Margarita; Pedrini, Giancarlo; Jeschke, Sabina; Osten, WolfgangAdvances in information technology open up the potential of combining optical systems with net based infrastructures, allowing for remote inspection and virtual metrology. In this paper, we report our recent work on building a remote laboratory for digital holographic metrology. We describe the architecture and the techniques involved in setting up the remote controlling metrology system. Further consideration will be given to the integration into an advanced infrastructure for remote experimentation, data storage and publication. Some other important issues such as information security will not be addressed.