Measurement of the temporal evolution of periodic induced displacement derivatives using stroboscopic electronic speckle-shearing interferometry

Single pulsed subtraction electronic speckle-shearing pattern interferometr y is used to measure the time evolution of deformations induced by periodic impulse loading on a metal plate. This is accomplished with a stroboscopic system based on a pulsed laser and an interline-transfer CCD camera runnin g at 60 frames/s. In a few seconds, a sequence of hundreds of interferogram s is recorded with an effective sampling time interval of some tens of micr oseconds. We describe the experimental setup used to generate the transient deformation on the metal plate and also the synchronization of laser pulse s and image acquisition. Several correlation fringe patterns are presented, showing the time evolution of the deformation. Finally, these data are use d to calculate optical phase maps and displacement derivative fields for di fferent times after the application of the dynamic load on the object. (C) 2001 Society of Photo-Optical Instrumentation Engineers.