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Proceedings Paper

Measurement of random and transient deformations of a vibrating plate with multipulse digital holography and their decomposition into eigenmodes
Author(s): Philipp Froening; Giancarlo Pedrini; H. Fessler; Hans J. Tiziani
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Paper Abstract

A rectangular metal plate is randomly excited by a shaker or by the impact of a small rod. To investigate the temporal development of the induced deformation, an optical measuring system for the evaluation of transient deformations is used. A ruby laser, which is able to produce four laser pulses within a few laser pulses within a few microseconds and a setup of three CCD-cameras for recording the four pulses/interferograms were used. The images of the recorded holographic interference patterns are captured digitally with a framegrabber inside a PC. The reconstruction of the holograms is performed also digitally in the computer. For the later is obtained from the complex amplitude and the deformation between two laser pulses is calculated from phase subtraction and phase unwrapping of these two holograms. Each deformation image can be decomposed into the eigenmodes of the plate, which have to be known/measured before. By measurement of four holograms with a known pulses separation one is able to determine the deformation states between each adjacent pulse and at least the temporal development of the deformation and contributing magnitude coefficients of the eigenmodes.

Paper Details

Date Published: 1 June 1998
PDF: 11 pages
Proc. SPIE 3411, Third International Conference on Vibration Measurements by Laser Techniques: Advances and Applications, (1 June 1998); doi: 10.1117/12.307690
Show Author Affiliations
Philipp Froening, Univ. Stuttgart (Germany)
Giancarlo Pedrini, Univ. Stuttgart (Germany)
H. Fessler, Univ. Stuttgart (Germany)
Hans J. Tiziani, Univ. Stuttgart (Germany)

Published in SPIE Proceedings Vol. 3411:
Third International Conference on Vibration Measurements by Laser Techniques: Advances and Applications
Enrico Primo Tomasini, Editor(s)

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