Electro-optic holography method for determination of surface shape and deformation

Current demanding engineering analysis and design applications require effective experimental methodologies for characterization of surface shape and deformation. Such characterization is of primary importance in many applications, because these quantities are related to the functionality, performance, and integrity of the objects of interest, especially in view of advances relating to concurrent engineering. In this paper, a new approach to characterization of surface shape and deformation using a simple optical setup is described. The approach consists of a fiber optic based electro-optic holography (EOH) system based on an infrared, temperature tuned laser diode, a single mode fiber optic directional coupler assembly, and a video processing computer. The EOH can be arranged in multiple configurations which include, the three-camera, three-illumination, and speckle correlation modes. In particular, the three-camera mode is described, as well as a brief description of the procedures for obtaining quantitative 3D shape and deformation information. A representative application of the three-camera EOH system demonstrates the viability of the approach as an effective engineering tool. A particular feature of this system and the procedure described in this paper is that the 3D quantitative data are written to data files which can be readily interfaced to commercial CAD/CAM environments.