10 December 1993 Electronic speckle techniques in noisy environments
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The main sources of noise that lead to speckle phase distortion and decorrelation are identified and methods to overcome these are suggested. An automated continuous reference updating technique is shown to be able to avoid speckle decorrelation induced by object drift or low frequency vibrations. A second improvement using the introduction of phase shift, and the addition of surface information during every image acquisition, is demonstrated to insure fringe pattern stability even in the presence of relatively high frequency noise due to thermal currents or air flow. Furthermore, phase modulation is used to reduce the speckle effect by removing the speckle phase term. The application of these techniques to the task of nondestructive detection of structural defects in aluminum plates is demonstrated in a very noisy environment.
© (1993) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Bruno F. Pouet, Bruno F. Pouet, Sridhar Krishnaswamy, Sridhar Krishnaswamy, } "Electronic speckle techniques in noisy environments", Proc. SPIE 2003, Interferometry VI: Techniques and Analysis, (10 December 1993); doi: 10.1117/12.165485; https://doi.org/10.1117/12.165485

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