Singlemode optical fiber electronic speckle pattern interferometry

Abstract

This paper describes two electronic speckle pattern interferometric (ESPI) systems using single mode optical fibers, namely, conventional ESPI and phase shifting ESPI (PSESPI), and their applications to the inspection of unbonds in carbon-epoxy honeycomb composite structures. It is observed that phase shifting ESPI produces fringe patterns of higher contrast than conventional ESPI. With the remarkably good quality fringe patterns obtained with both systems, subsequent quantitative analysis of the fringes can be achieved with accuracy, hence enhancing the potential of holographic NDT for in-situ industrial applications.