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Proceedings Paper

Real-time measurement of in-plane vibration by double-aperture laser speckle interferometry
Author(s): Nobuyuki Iwatsuki; Kouichi Morikawa; Iwao Hayashi
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Paper Abstract

This paper describes the real-time measurement of in-plane vibration using an improved double-aperture laser speckle interferometer. To detect the in-plane vibration in real- time, a new signal processing system which can detect the phase angle of the frequency component of the interference fringes in real-time by calculating Fourier coefficients is proposed. The proposed real-time signal processing system is composed of a pulse generator, a sin/cos generator and an A/D converter controlled by a personal computer, and of an analog electronic circuit made of analog IC's. The linearity of the output signal of the prototype due to a number of the detected fringes and noises is experimentally examined. In- plane static displacement and vibration displacements of a specimen driven by a piezostack are measured with a new laser speckle interferometer equipped with the proposed signal processing system and are calibrated with a gap sensor. The measured static in-plane displacements varied in proportion to the given displacement with reproductive error variation with the maximum value of 0.5 micrometers . The vibration displacements measured with the laser speckle interferometer were detected with the maximum sampling frequency of 470Hz. This new laser speckle interferometer thus achieved the measurement of in-plane vibration in real-time.

Paper Details

Date Published: 1 June 1998
PDF: 8 pages
Proc. SPIE 3411, Third International Conference on Vibration Measurements by Laser Techniques: Advances and Applications, (1 June 1998); doi: 10.1117/12.307717
Show Author Affiliations
Nobuyuki Iwatsuki, Tokyo Institute of Technology (Japan)
Kouichi Morikawa, Tokyo Institute of Technology (Japan)
Iwao Hayashi, Tokyo Institute of Technology (Japan)

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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