Optical interferometric techniques are being increasingly used in industry. These non contact techniques, using laser methods based on speckle interferometry, assure a greater accuracy in measuring displacements caused by deformations. One such technique, Electronic Speckle Pattern Interferometry (ESPI), has been used successfully, by analysis of the reaction of mechanical components to induced mechanical or thermal stress, for the measurements of in-situ, real time, full-field, in-plane and out-of-plane displacements and the detection of detachments, micro-cracks occurring as internal and external defects.