Profilometry by fringe projection

We present a method to obtain profilometry of a suitable object by fringe projection. The method is appropriate to the case of large objects as compared to the distance from the illuminating source, that is, a nonconstant equivalent wavelength. We develop an experiment to laterally displace a set of fringes on a sphere and obtain quantitative results. There are several orientation parameters involved in the method, and a minimization algorithm is developed to adjust the values of some of them. A series of numerical experiments are performed on this method to test its accuracy under various circumstances. We show that the method can currently attain precisions of approximate tolambda(eq)/80 (lambda(eq) stands for equivalent wavelength) and identify possible sources of error. (C) 2003 Society of Photo-Optical Instrumentation Engineers.