SIMULTANEOUS MEASUREMENT OF 3 ORTHOGONAL COMPONENTS OF DISPLACEMENT BY ELECTRONIC SPECKLE-PATTERN INTERFEROMETRY AND THE FOURIER-TRANSFORM METHOD

The measurement of three-dimensional displacement by electronic speckl e-pattern interferometry with three object beams and one reference bea m is presented. Multiple interference fringes corresponding to differe nt sensitivity vectors are recorded in a single interferogram and sepa rated by means of the Fourier transform method to give three component s of displacement. The relationship between the ratio of the speckle s ize to the pixel size of a TV camera and the measurement error is inve stigated experimentally and compared with the research of others. The optimum condition leading to a minimum measurement error occurs when t he speckle size is approximately equal to the pixel size. With this co ndition satisfied, the measurement error varies from 1.5% to 6.0%. (C) 1997 Optical Society of America.