Synthetic aperture sonars for imaging of marine geology and buried objects.

Large acoustic apertures are necessary for generating high quality imagery of marine sediments and objects buried beneath the seafloor. These aperture sizes are usually much larger than the widths and lengths of small underwater vehicles. A large aperture is formed along the track of the vehicle by utilization of synthetic aperture processing. Vehicle wings, containing hydrophone arrays that are extended after vehicle submergence, are used to form a large across vehicle track aperture. Imagery of sediment layering is formed by time domain focusing on planar surfaces. However, buried object images are formed by time domain focusing at subsurface focal points. Images of sediments and buried objects are used to measure the performance of these techniques.