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

Theoretical and experimental results for evaluation of 3-D shapes using light-in-flight speckle interferometry are described. Light-in-flight is a technique that uses laser light sources that emit ultrashort pulses or have a narrow coherence length. The interferogram of the object under study is only registered for the object parts for which the difference in path length between the reference and the object beam is less than the coherence length. Here, electronic speckle pattern interferometry for out-of-plane displacements is used to record the interferogram. An automatic evaluation system that 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-dimensional shapes. (C) 1999 Society of Photo-Optical Instrumentation Engineers.