<title>Measurement of dynamic displacements using holographic and speckle interferometry</title>

Abstract

Holographic and Speckle Interferometry provide full-field inspection of surfaces with high accuracy: these techniques offer some useful advantages (e.g. speed, high-precision,...) over other optical nonintrusive inspection techniques. Although the performance and precision of Holographic and Speckle Interferometry are affected by ambient conditions (temperature gradients, air turbulences, ...), the development of special experimental methods allows the use of these techniques directly in-field. An application of these interferometric methods can be foreseen, for example, in traditional testing laboratories or for a direct industrial production control. A great effort is currently in progress at ENEA-Frascati and at JRC-Ispra in order to develop new methods and computerized optoelectronic systems aiming at the application of Holographic and Speckle Interferometry to structural testing. Our most recent experimental results using time-average holographic interferometry and pulsed holographic interferometry for dynamic displacement measurements are presented. A theoretical background of the time-average ESPI procedure is described and some experimental results are shown.