Acoustic apparatus and method for detecting and identifying near-surface buried objects using a non-contact array of ultrasonic vibrometers (200) each vibrometer having a focused beam in air (400) pointing vertically at the ground. Also there is a low-frequency loudspeaker (60). Both are connected to a digital signal processor (40). The loudspeaker emits continuous sound that penetrates the ground and generates echoes from a buried object, creating seismic vibrations (350) at the surface (150). The vibrometers emit pulses of focused ultrasound with a known depth of field (650) and receive echo pulses (770) from the seismic vibrations. The pulses occur at a much faster rate than the frequency of the seismic vibrations, typically a few thousand times faster, thus permitting the processor to compute the motion and frequency content of the seismic vibrations. This data from the array determines the shape and frequency response of near-surface buried objects which are shown on a display device. The apparatus is practical and inexpensive. A movable means of scanning with the apparatus can cover the ground one section of area at a time.


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