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Proceedings Paper

Digital shearography using stroboscopic illumination in addition to time average method
Author(s): Wolfgang Steinchen; Ymin Gan; Gerhard Kupfer; Peter Maeckel
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Paper Abstract

One of the most interesting and useful applications of shearographic interferometry is the detection, visualization and measurement of the mechanical vibration of opaque objects. Until now the time-average shearography is a qualitative interferometric method for determining the oscillating loadings. The detected gradient of the deformation can be determined by changing the shearing distance. The fringes of the moving object are often faded and become clearer by filtering with FFT and against an uniform background intensity. The fringes formed in time-average shearography of sinusoidal motions have an irradiance described by the Bessel function J02. Quantitative interpretation of the shearogram requires a more precise analysis. Such a technique for extending or decreasing the sensitivity of vibration measurements and for determining the relative phase of vibration across the object surface is the stroboscopic illumination. Stroboscopic shearographic interferometry is a technique which compensates the deficiencies of time-average shearography at the expense of some increase in experimental complexity. However more complex is the recording of stroboscopic shearograms by using two pulses from a double-pulse laser.

Paper Details

Date Published: 22 June 2004
PDF: 11 pages
Proc. SPIE 5503, Sixth International Conference on Vibration Measurements by Laser Techniques: Advances and Applications, (22 June 2004); doi: 10.1117/12.579571
Show Author Affiliations
Wolfgang Steinchen, Univ. Kassel (Germany)
Ymin Gan, Univ. Kassel (Germany)
Gerhard Kupfer, Univ. Kassel (Germany)
Peter Maeckel, industrial-speckle-interferometry - systems (Germany)

Published in SPIE Proceedings Vol. 5503:
Sixth International Conference on Vibration Measurements by Laser Techniques: Advances and Applications
Enrico Primo Tomasini, Editor(s)

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