Proceedings PaperPhase-Shifting Speckle Interferometry
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Speckle patterns have high-frequency phase data, which make finding the absolute phase of a single speckle pattern difficult. However, the phase of the difference between two correlated speckle patterns can be determined by applying phase-shifting techniques to speckle interferometry, which will quantitatively determine the phase of double-exposure speckle measurements. The technique uses computer control to take data and calculate phase without an intermediate recording step. The randomness of the speckle causes noisy data points that are removed by data processing routines. A study of the phase errors attributable to decorrelation of the speckle patterns shows a 33° rms error for 10 waves of tilt. One application of this technique is finding the phase of deformations, where up to 10 waves of wavefront deformation can easily be measured. Results of deformations caused by tilt of a metal plate and a disbond in a honeycomb structure brazed to an aluminum plate are shown.