Digital measurement of three-dimensional shapes using light-in-flight speckle interferometry

Theoretical and experimental results for evaluation of 3-D shapes using lig ht-in-flight speckle interferometry are described. Light-in-flight is a tec hnique that uses laser light sources that emit ultrashort pulses or have a narrow coherence length. The interferogram of the object under study is onl y registered for the object parts for which the difference in path length b etween the reference and the object beam is less than the coherence length. Here, electronic speckle pattern interferometry for out-of-plane displacem ents is used to record the interferogram. An automatic evaluation system th at consists of a computer-controlled image-processing system combined with a positioning system has been built to read the different contour lines and transform them into spatial coordinates, thereby detecting the three-dimen sional shapes. (C) 1999 Society of Photo-Optical Instrumentation Engineers.