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.
|Period||24/08/2015 → 26/08/2015|
|Series||Proceedings of SPIE, the International Society for Optical Engineering|
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