Experimental study on acoustic-to-seismic landmine detection based on laser self-mixing interferometer

Abstract

Laser self-mixing interferometer is a novel remote sensor which permits measuring micro vibration displacement of scattering targets, making it apply to noncontact detection of landmine buried in the ground. An experimental model is developed for acoustic/seismic landmine detection using a laser self-mixing interferometer to obtain the velocity variations image of the ground excited by acoustic wave. Interferometer has a noise floor due to speckle noise, thus sound pressure level should strong enough to stimulate landmine to vibrate in a mode higher than interferometer noise floor. Vibration response in frequency domain and 2D image are obtained with laser self-mixing interferometer in the field test, and results demonstrate it is feasible to detect landmine and distinguish landmine types from the shape and size of the image.