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Proceedings Paper

Absolute and dynamic position and shape measurement of fast moving objects employing novel laser Doppler techniques
Author(s): Thorsten Pfister; Philipp Günther; Lars Büttner; Jürgen Czarske
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Paper Abstract

In this contribution a novel laser Doppler distance (LDD) sensor is presented, which allows simultaneous measurement of axial position and tangential velocity and, thus, determination of the shape of moving and especially rotating objects with one single sensor. Conventional laser Doppler velocimeters measure only velocities. A concurrent position measurement can be realized by generating two fan-shaped interference fringe systems with contrary fringe spacing gradients and evaluating the quotient of the two resulting Doppler frequencies. Alternatively, two tilted fringe systems in combination with phase evaluation can be employed. It will be shown that, in contrast to conventional distance sensors, high temporal resolution below 3 μs and high position resolution of about 1 μm can be achieved simultaneously, because the position uncertainty of the LDD sensor is in principle independent of the object velocity. This is advantageous especially for monitoring highly dynamic processes e.g. at turbo machines, where in-process measurements of tip clearance and rotor vibrations are reported for up to 600 m/s blade tip velocity.

Paper Details

Date Published: 3 October 2008
PDF: 12 pages
Proc. SPIE 7155, Ninth International Symposium on Laser Metrology, 715513 (3 October 2008); doi: 10.1117/12.814539
Show Author Affiliations
Thorsten Pfister, Technische Univ. Dresden (Germany)
Philipp Günther, Technische Univ. Dresden (Germany)
Lars Büttner, Technische Univ. Dresden (Germany)
Jürgen Czarske, Technische Univ. Dresden (Germany)

Published in SPIE Proceedings Vol. 7155:
Ninth International Symposium on Laser Metrology
Chenggen Quan; Anand Asundi, Editor(s)

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