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Proceedings Paper

Two-wavelength contouring for shape and deformation measurement
Author(s): Martin Dale; Clive H. Buckberry; David P. Towers
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Paper Abstract

Electronic Speckle Patterin Interferometry (E.S.P.I.) is a holographic interferometry technique technique that can be used to measure out-of- plane deformations and vibration amplitudes up to a few microns with an accuracy of a few nanometres, in near real time. Two-wavelength holographic contouing is an adaptation of this technique that utilises two lasers in an E.S.P.I. system, generating fringes with spacing determined by the frequency difference between the two lasers. Careful choice of laser wavelengths enables us to measure the shape of an object on a scale and accuracy that is more useful in engineering applications. In addition, by measuring the shape of an object before and after the application of a static load, deformation can be measured on this same enginering scale. The engineering drive for this technology is to gain high spatial resolution modal information on light structures (e.g. body panels) with a non-contacting measurement device. The shape and vibration data can then be mapped to each other on a pixel to pixel basis, giving over a quarter of a million data points containing position, vibration amplitude and vibration phase information. This data can then be used to create hybrid Finite Element/Experimental models or be used to predict the noise radiation levels from a vibrating object. In the system described here the 2 laser wavelengths are applied simultaneously giving the capability to obtain the object shape in an engineering environment, i.e. away from a stable optical table. The model data is obtained in a similar manner and therefore the complete system is operable in engineering laboratories.

Paper Details

Date Published: 31 August 2000
PDF: 10 pages
Proc. SPIE 4076, Optical Diagnostics for Industrial Applications, (31 August 2000); doi: 10.1117/12.397947
Show Author Affiliations
Martin Dale, Rover Group Ltd. (United Kingdom)
Clive H. Buckberry, Rover Group Ltd. (United Kingdom)
David P. Towers, Rover Group Ltd. (United Kingdom)

Published in SPIE Proceedings Vol. 4076:
Optical Diagnostics for Industrial Applications
Neil A. Halliwell, Editor(s)

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