Laser-acoustic detection of objects buried underwater

Abstract

An object buried underwater such as landmines can potentially be excited to vibrate by a sound source in air. The vibration then radiates a secondary wave in the water to excite the water surface vibration which can be detected by a laser sensor. This idea of laser-acoustic detection of buried objects is effective in detecting objects buried under ground where the object is mechanically excited and the ground surface vibration is scanned by the laser sensor. When applying this approach to detect objects buried underwater, the addition of the water layer has an impact on the flexibility of the detection. Numerical simulations and laboratory experiments are conducted to assess this flexibility. Vibrations of the object and the water surface are experimentally measured and numerically simulated for water layers of different depths. The results reveal the impact of the water layer and the effectiveness of the detection. [Work supported by the Office of Naval Research under Award No. N00014-21-1-2247.]