Measurement of surface strain using multi-component pulsed laser shearography with coherent fibre-optic bundles

D. Francis; S. W. James; R. P. Tatam

doi:10.1117/12.725444

18 June 2007 Measurement of surface strain using multi-component pulsed laser shearography with coherent fibre-optic bundles

D. Francis, S. W. James, R. P. Tatam

Author Affiliations +

Proceedings Volume 6616, Optical Measurement Systems for Industrial Inspection V; 66162S (2007) https://doi.org/10.1117/12.725444
Event: Optical Metrology, 2007, Munich, Germany

Abstract

Quantitative surface strain measurement using shearography requires the calculation of six components of displacement gradient. This is done using shearography instrumentation with at least three measurement channels combined with two orthogonal shear directions. These channels take the form of either multiple illumination or observation directions. The system presented here is based on the illumination of the object of interest using a pulsed Nd:YAG laser and the observation of the object from four separate positions arranged in a square around the illuminating beam. Images from the four observation positions are transported to a shearing interferometer using coherent fibre-optic imaging bundles, where they are spatially multiplexed onto the sensor of a single CCD camera. Displacement gradient measurements from a static test object are presented and compared to the results of a computational model. Phase analysis is carried out using two approaches, temporal phase stepping and the carrier fringe technique, with the aim of extending the application of the instrument to the monitoring of dynamic loading events.

Citation Download Citation

D. Francis, S. W. James, and R. P. Tatam "Measurement of surface strain using multi-component pulsed laser shearography with coherent fibre-optic bundles", Proc. SPIE 6616, Optical Measurement Systems for Industrial Inspection V, 66162S (18 June 2007); https://doi.org/10.1117/12.725444

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