Laser multibeam differential interferometric sensor for acoustic detection of buried objects

Abstract

A laser multibeam differential interferometric sensor (LAMBDIS) was developed that provides measurement of vibration fields of objects with high sensitivity, while having low sensitivity to the whole-body motion of the object, or the sensor itself. The principle of operation of the LAMBDIS is based on the interference of light reflected from different points on the object surface illuminated with a linear array of laser beams. The Doppler shift induced by the sensor motion is approximately the same for all beams and is automatically subtracted from the measurements. The performance of the sensor for laser-acoustic detection of a buried object was experimentally investigated. The ability of LAMBDIS to detect buried objects from a moving vehicle has been demonstrated in field experiments.