3-DIMENSIONAL DISPLACEMENT MEASUREMENT USING CHIRP MODULATION IN A PHOTOREFRACTIVE CORRELATOR

A speckle correlation technique based on chirp modulation of the speck le interference pattern is proposed and demonstrated for the measureme nt of 3-D rigid body motion. The chirp modulation is a consequence of the out-of-plane displacement component associated with object motion. The Fresnel zone plate action introduced by chirp modulation causes t he correlation peaks to focus at different planes along the longitudin al direction. The separation between the correlation peaks along the t ransverse direction gives a measure of in-plane displacement of object motion. Both simulation and experimental studies are performed to est ablish the proposed technique. (C) 1998 Society of Photo-Optical Instr umentation Engineers. [S0091-3286(98)01011-3].