Impact of multiple usages of digital filters on speckle contrast and phase maps

Various digital filters have been use to remove unwanted noise in speckle pattern used in the field of Electronic speckle pattern interferometer (ESPI). However, multiple usages of these digital filters can contribute to significant drop in speckle contrast leading to loss of phase information. This paper reports effect of multiple usages of various digital filters namely, Median, Gaussian and Average on the speckle contrast and ultimately on the phase maps. This study also compares effectiveness of these three digital filters in removing noise from speckle patterns.