A Method for Real Time and Continuous Acquisition of Interferogram of ESPI for Non-Destructive Evaluation

Electronic Speckle Pattern Interferometry (ESPI) is a highly sensitive optoelectronic whole field technique used for measuring surface displacement strain analysis, surface roughness, surface contour etc. This nondestructive evaluation technique permits measurement of deformations in the micrometer and sub micrometer ranges produced in a test specimen under different loading conditions. In ESPI technique, the speckle patterns act as information carriers of different deformation states of the test specimen. These speckle patterns of the object before and after loading are electronically detected and digitally processed to generate interference fringes. In this paper a method for real time and continuous acquisition of ESPI images and the simultaneous electronic processing is discussed.