Deformation and profile measurement using the digital projection grating method

This paper presents a digital projection grating method for full field meas urement of out-of-plane deformation and shape of an object. Two grating pat terns on an object before and after deformation are captured by a CCD camer a and stored in a computer. With the aid of Fast Fourier Transform (FFT) an d signal demodulating techniques, a wrapped phase map is generated. The pha ses are expanded in the range of 0-2 pi and compared with the resulting moi re pattern. An unwrapping procedure is used to obtain a continuous phase. I n addition, a digital method for fractional fringe multiplication is also d eveloped. Results on deformation and object profile measurements are presen ted. (C) 1998 Elsevier Science Ltd. AII rights reserved.