Normalization and smoothing algorithm for electronic speckle-pattern interferometry fringes

This work points out that a modification of the fringe analysis method proposed by Kreis may serve as a normalization and filtering method for electronic speckle-pattern interferometry (ESPI) fringes. By rotating a half-plane in the frequency space, a fringe pattern may be normalized without being distorted significantly. If a passband filter is used during the rotation, a smoothed fringe pattern is obtained. Experimental verification is presented using images obtained from ESPI.