Standoff Detection of Landmines Using Acoustic Vibrometry

The real-time detection of buried landmines from a moving and vibrating platform is a challenging problem mainly due to the limited sensitivity of present-day receivers. The technical approach we propose is to develop a highly sensitive, acoustic-laser vibrometer system combined with imaging and ranging capabilities. Vibrometers are optical instruments that can accurately measure velocity, displacement, and phase shift patterns of vibrating structures without contact. When image and range information are also obtained, the instrument provides five signatures to discriminate between landmines and other buried objects. The core element of the system will be a new, high gain, avalanche photodiode (APD) array with low-noise and large bandwidth. HgCdTe is the most promising material candidate for the development of these APDs because it can be bandgap engineered to achieve strong absorption at the wavelength of interest and a large asymmetry between the hole and electron impact ionization coefficients. This leads to high gain-bandwidth with minimal excess noise. We propose to use our extensive experience in HgCdTe growth by molecular beam epitaxy and device processing to fabricate the APDs and integrate them into landmine detection systems.