Measurement of shape by using projected random patterns and temporal digital speckle photography

Projected random patterns have been used to measure the shape of discontinu ous objects. A sequence of independent random patterns are projected onto t he object. These images are analyzed by use of the technique called tempora l digital speckle photography (DSP) that is introduced here. With temporal DSP the spatial resolution of the shape measurement is improved considerabl y compared with previously reported results with projected random patterns. A calibration procedure is described that uses a sequence of independent r andom patterns to calibrate measurement volume. As a result, independent sp ace coordinates for each subimage are obtained. The accuracy is of the orde r of 1/1000 of the field of view where a subimage size of 8 pixels seems to be a good compromise between reliability and spatial resolution. The techn ique is illustrated with a measurement of an electrical plug and a 9-V batt ery. (C) 1999 Optical Society of America.