MULTIREFERENCE FRINGE-PATTERN PROJECTION METHOD FOR MEASURING THE SHAPE OF AN OBJECT WITH SPATIALLY ISOLATED SURFACES

A multireference fringe-pattern projection (MRFP) method is developed for rapid measurement of the shape of an object that has spatially iso lated surfaces. The method combines the commonly used fringe-pattern p rojection method and an acousto-optic deflector (AOD) scanner in one o ptical system. The AOD scanner generates reference fringes, whose posi tions can be conveniently adjusted to suit the respective object by ch anging the control signal to the AOD, We determined the accuracy of th is MRFP method by measuring the displacement of a plastic plate and co mparing the results with those obtained using a linear gauge. We find the relative accuracy to be 0.3%. To demonstrate the capability of thi s method to measure objects that have isolated surfaces, we use it to measure a vertical translation stage, Finally, we use it to measure th e variations in position and shape of a fish while it is swimming. Suc h variation measurements are useful for studying the fluid dynamics of a swimming fish. (C) 1997 Society of Photo-Optical Instrumentation En gineers.