报告简介：The precise 4D shape measurement of fast rotating objects is important at several applications. One task is the monitoring of the workpiece diameter inside of a lathe, also during machining (in-situ and on-line: in-line). Other rotating objects to be measured are crankshafts, camshafts, magnetic bearings and vacuum pump shafts. The tolerances of the object dimensions are reduced more and more. Currently distance measurement techniques often have to offer resolutions in the nanometer range, also at moving surfaces. A non-incremental interferometer based on two mutually tilted interference fringe systems has been realized for this task. The distance is coded in the phase difference between the generated interference signals corresponding to the fringe systems. Large tilting angles between the interference fringe systems are necessary for a high sensitivity. However, due to the speckle effect at rough surfaces, different envelopes and phase jumps of the interference signals occur. At large tilting angles, these signals become dissimilar, resulting in a small correlation coefficient and a high measurement uncertainty. Based on a novel matching of illumination and receiving optics [1], the correlation coefficient and the phase difference estimation have been improved significantly. For axial displacement measurements of recurring rough surfaces, laterally moving with high velocities of 5 m∕s, an uncertainty of 110 nm has been attained with high temporal resolution.

The same measurement technique has been applied for in-situ monitoring of polymer composite rotors [2]. The complexity of the polymer fiber-reinforced composite materials requires in-process time-resolved measurements under realistic conditions. This enables the tracking of the evolution of damages under dynamic loads in order to predict the structural integrity of composite rotors for turbo machines. Three interferometric sensors have been employed in order to measure the radial expansion of high-speed rotors. At surface speeds of more than 300 m/s the radial expansion has been determined with sub-micron standard deviation. A comparison of the measured data with the numerically calculated data is performed to improve the simulation. This procedure will support the realization of a new kind of reliable lightweight fiber-reinforced polymer rotors.

报告人：Prof. Jürgen Czarske studied physics and electrical engineering at the Leibniz University of Hanover, Germany, where he received also his Ph. D. degree in 1995 and venia legendi (habilitation) in 2003. Between 1995 and 2004, he was with the Laser Zentrum Hannover (LZH), Germany, a private institute of research and technology. Since December 2004 he is full professor and director of the laboratory for measurement and testing techniques in the faculty of electrical and computer engineering at the TU Dresden, Germany.

Prof. Czarske is member of the Review Board on Measurement Systems of the German Research Foundation (DFG). Among other honors he has been awarded 2008 by an international Berthold Leibinger innovation prize and 2011 by the Best Conference Paper Prize of Controls, Diagnostics and Instrumentation Committee of ASME (American Society of Mechanical Engineers) in Vancouver, Canada.

报告时间地点：Tsinghua University, Laser Technology and Modern Measurement Laboratory, Department of Precision Instruments and Mechanology, Institute of Opto-electronic Engineering, Beijing, invited by Prof. Shulian Zhang

10 o´clock at Monday, May 12, 2014