Fringe projection technique for the 3-D shape measurement of a hydroformed shell

Abstract

This paper describes the 3-D shape measurement of a hydroformed shell by a non-contact optical method based on the fringe projection technique. Sinusoidal fringes are produced by the interference of two spherical wavefronts from the output fibre. The fringe patterns are captured by a camera and gratings are made from camera negatives. A slide projector is used to project the fringe patterns onto a hydroformed shell. The deformed fringe pattern image is captured by a CCD camera and a Fourier transform is performed on the image using a microcomputer. In contrast to the conventional Moire method, this method is relatively simple and accurate, and is capable of conducting fully automatic measurement. An experiment illustrates the capabilities of the technique in the 3-D shape measurement of a hydroformed shell.