Laser sensing techniques for acoustic detection of buried mines.

Abstract

Acoustic detection of buried mines is based on excitation of vibrations in the ground with airborne sound and measuring vibration of the ground surface by using a laser interferometric sensor. The principle of detection uses the fact that buried mines have mechanical impedances that are smaller than that of soils. That makes the soil above a mine vibrating with magnitude higher than the surrounding soil. A laser sensor creates a vibration image of the ground by measuring vibration in many points on the surface. The presence of a buried mine can be detected by an abnormality in the vibration image. The method has shown excellent performance in field tests. One limiting factor of the method is a long measurement time due to low frequency of vibrations. Different laser interferometric techniques have been investigated to reduce the time of detection. The paper discusses application of single‐beam scanning laser Doppler vibrometry (LDV), multiple‐beam LDV, and speckle‐interferometry based methods for acoustic detection of mines.