PHASE-SHIFTING SPECKLE INTERFEROMETRY - A NOISE-REDUCTION FILTER FOR PHASE UNWRAPPING

We present a noise reduction filter for the phase unwrapping of data f rom phase-shifting speckle pattern interferometry. This filter is effe ctive in reducing the noise in wrapped phase maps without affecting th e edges of the phase jumps, so that a simple and fast unwrapping algor ithm can be used. We also discuss a data analysis strategy, including a routine for the recovery of unwrapping errors. The filter performanc e has been evaluated on real data from a fiber optic phase-shifting sp eckle interferometer, which we built for the analysis of out-of-plane deformations, The phase shifting is introduced by current modulation o f the diode laser source. Some results relative to the analysis of ver y noisy phase measurements are presented. (C) 1997 Society of Photo-Op tical Instrumentation Engineers.