Finding small displacements of recorded speckle patterns: revisited

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An analytical expression for the bias effect in digital speckle correlation is derived based on a Gaussian approximation of the spatial pixel size and array extent. The evaluation is carried out having assumed an incident speckle field. The analysis is focused on speckle displacements in the order of one pixel, thus having no speckle decorrelation. Furthermore, sensitivity is a main issue wherefore we need speckles close to the pixel size, which means that speckle averaging becomes important, and that Nyquist’s criteria may not be fulfilled. Based on these observations, a new correlation method is introduced, which alleviates the need to know the expected shape of the crosscovariance between the original and the off-set recorded speckle pattern. This concept calls for correlating the crosscovariance with the auto covariance, which essentially carries information on the expected shape of the crosscovariance.
Original languageEnglish
Title of host publicationProceedings of SPIE
EditorsFernando Mendoza Santoyo
Number of pages8
PublisherSPIE - International Society for Optical Engineering
Publication date2015
Article number96601J
Publication statusPublished - 2015
EventSPECKLE 2015: VI International Conference on Speckle Metrology - Guanajuato, Mexico
Duration: 24 Aug 201526 Aug 2015


ConferenceSPECKLE 2015
SeriesProceedings of SPIE, the International Society for Optical Engineering

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