Imaging with a 2 MHz sparse broadband planar array

A portable high-resolution sonar has been under development to provide Navy divers with acoustic imaging systems for mine reconnaissance. The first phase of development was completed in 2000 with the demonstration of a broadband, 6% sparse line array, imaging a simple target in the NUWC Acoustic Test Facility (ATF). Element locations for this array were computed based on a grid point optimization technique which minimized close-in sidelobes. The center frequency was 2 MHz with a 667 kHz bandwidth. A new sparse planar array, consisting of 121 1 mm/spl times/1 mm 2 MHz elements, has been fabricated, to provide 3-D acoustic images of underwater targets. This array was also designed using the grid point optimization technique.