Abstract
A 2-D in-plane displacement sensitive fiber electronic speckle pattern interferometry (ESPI) is developed. With a fiber optics beam splitter of one input and four outputs, two sets of dual-beam interferometrical configuration are constructed in orthogonal directions to determine in-plane displacements completely. A CCD camera with a zoom lens is located at 320 mm to approximately 550 mm away from the specimen to provide adequate space for operation. A testing area ranging from 1.4 mm X 1 mm up to 30 mm X 24 mm can be examined in quasi real-time. In general, the system is capable of determining in-plane displacement and deformation generated by any means. Incorporating with the hole drilling technique, it is currently used to measure residual stress. Two applications are reported in this paper. One is to determine residual stress of a thick cylinder consisting of two concentric circular tubes with interference fit. A simple approach to interpret the value of residual stress from the displacement contour is presented. The other application is to analyze residual stress of recordable optical compact discs (CD-R).