Passive underwater imaging through optimized planar arrays of hydrophones

Planar arrays of acoustic sensors represent a critical component for a 3-D wideband passive imaging system. Recently, a method has been proposed for the design of planar microphone arrays that are superdirective (to provide good performance at low frequencies) and aperiodic (to avoid grating lobes at high frequencies). Robustness against dispersion in the sensor characteristics is achieved by exploiting the probability density functions of such errors. Here, such a method is used to demonstrate that 36 low-cost poorly-matched hydrophones are sufficient to populate a square aperture with a side length of 60 cm used as sensor array for an underwater passive system working from 1.5 kHz to 12 kHz.