Basic Physical Principles and Mine Features Exploited by the Technology

Acoustic-to-seismic (A/S) coupling–based mine detection is based on the ability of sound to penetrate the ground and excite resonances in buried compliant objects [1]. Sound produced in the air efficiently couples into the first 0.5 m of the soil because of the porous nature of weathered ground resulting in acoustic vibrations that are sensitive to the presence of buried mines. This phenomenon has been termed “acoustic-to-seismic coupling” in the research literature. Off-the-shelf loudspeakers are used as the sound source and readily available laser Doppler vibrometers (LDVs) are used to measure the increased ground vibrations due to the presence of the buried mine [2]. The use of airborne acoustics for mine detection exploits three new phenomena that previously have not been explored for the purpose of buried mine detection. First, a landmine is a man-made, acoustically compliant object that is much more compliant than soils. This results in a high-vibration contrast between soils and buried mines that does not occur because of the presence of rocks, roots, and other man-made solid objects, such as concrete and metal. Second, the mine is a nonporous object that offers additional contrast to the porous soil in the presence of coupled sound. Third, the interface between a mine and the soil has been shown to be nonlinear; the interface between the soil and the