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12 December 1997 Transient deformation measurement using dual-pulse addition ESPI
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An electronic speckle pattern interferometry system based on a frequency-doubled twin Nd:YAG laser emitting dual pulses at a TV camera field rate (50 Hz) was developed to analyze addition fringes generated by transient deformation of a test object. The main advance has been the automatic, quantitative analysis of dual-pulsed addition ESPI data by the introduction of carrier fringes and the application of Fourier methods. The carrier fringes are introduced between dual pulses by tilting the reference beam with a mirror driven by a galvanometer. The resulting deformation-modulated addition fringes are enhanced with a variance filter before evaluation of the phase distribution using a Fourier transform method with bandpass filtering. From the wrapped phase distribution, a continuous phase map is reconstructed using an iterative weighted least- squares unwrapper. The linear phase distribution associated with the carrier fringes is removed by evaluating it with a least-squares fitting algorithm. Preliminary results obtained for a thin plate submitted to an acoustic shock show the suitability of the system for the quantitative evaluation of transient deformation fields.
© (1997) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
David I. Farrant, Guillermo H. Kaufmann, Jon N. Petzing, John Raymond Tyrer, Bozenko F. Oreb, and David Kerr "Transient deformation measurement using dual-pulse addition ESPI", Proc. SPIE 3173, Ultrahigh- and High-Speed Photography and Image-based Motion Measurement, (12 December 1997);

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