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Proceedings Paper

Novel interferometric technique for the measurement of vibration and displacement of rotating components
Author(s): J. Czarske; P. Günther
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Paper Abstract

In microelectronics, vacuum techniques such as turbo molecular pumps have to fulfill the demand of lowest vibrations. The standard measurement technique for this purpose is the laser Doppler vibrometer. However, vibration measurements of fast rotating objects such as vacuum pump shafts are challenging due to the laterally moving speckle pattern. In order to overcome this drawback, a novel non-incremental interferometric technique is presented for precise shape, vibration and displacement measurements of high speed rotating objects. Two inclined interference fringe systems are generated in one measurement volume. Their signal phase difference depends on the axial position and their signal frequency corresponds to the lateral velocity. Thus, simultaneous position and velocity measurements can be accomplished. However, the tilted interference fringe systems result in different speckle patterns and therefore in a low crosscorrelation coefficient of the scattering signals. Holographic methods have shown the way to overcome this problem. The scientific finding is to use different receiving angles in correspondence of the different inclination angles of the interference fringe systems in order to enhance the cross-correlation coefficient significantly. By this, to our best knowledge, worldwide unique method a standard position deviation of only 110 nm has been achieved also at high speeds over 10 m/s. Since the axial position and lateral velocity are measured simultaneously, shape and vibration measurements of rotating components can be accomplished by only one sensor. This non-incremental interferometric technique has been applied especially to vacuum pumps, rotating at 48,000 rpm. Substantial vibration evaluations of the rotating shaft have been performed.

Paper Details

Date Published: 26 April 2012
PDF: 9 pages
Proc. SPIE 8430, Optical Micro- and Nanometrology IV, 843002 (26 April 2012); doi: 10.1117/12.928180
Show Author Affiliations
J. Czarske, Technische Univ. Dresden (Germany)
P. Günther, Technische Univ. Dresden (Germany)

Published in SPIE Proceedings Vol. 8430:
Optical Micro- and Nanometrology IV
Christophe Gorecki; Anand K. Asundi; Wolfgang Osten, Editor(s)

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