Fresnel wavefront propagation model for shearography shape measurement

Arun Anand; Roger M. Groves; Xavier Schwab; Giancarlo Pedrini; Wolfgang Osten

doi:10.1117/12.725985

18 June 2007 Fresnel wavefront propagation model for shearography shape measurement

Arun Anand, Roger M. Groves, Xavier Schwab, Giancarlo Pedrini, Wolfgang Osten

Proceedings Volume 6617, Modeling Aspects in Optical Metrology; 66170Q (2007) https://doi.org/10.1117/12.725985
Event: Optical Metrology, 2007, Munich, Germany

Abstract

This paper describes a new technique for modelling slope fringes in shearography using Fresnel wavefront propagation. Shearography is a full-field speckle interferometry technique usually used for displacement gradient and for shape measurement. One feature of shearography is that it uses a close to common path interferometer. This has the advantage of reducing sensitivity to environmental disturbances, but the disadvantage of a non-linear response. Previously one of the authors has used a ray tracing model of the fringe formation to improve the shape and slope measurement capabilities of shearography. The calculation involved was relatively time consuming as it required the calculation of the phase for each camera pixel individually. In this new Fresnel wavefront propagation model the approach is different. The system is modelled by propagation of the entire wavefront. This includes propagating the light through optical elements, such as a lens. This initial study has been for the formation of slope fringes in shearography using the source displacement technique. The advantages of this new technique are that it is easier to introduce optical elements and the effects of speckle noise into the simulation.

Citation Download Citation

Arun Anand, Roger M. Groves, Xavier Schwab, Giancarlo Pedrini, and Wolfgang Osten "Fresnel wavefront propagation model for shearography shape measurement", Proc. SPIE 6617, Modeling Aspects in Optical Metrology, 66170Q (18 June 2007); https://doi.org/10.1117/12.725985

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