An acoustic probe (100, 300) includes an acoustic transducer (15, 444), and a plurality of variably-refracting acoustic lens elements (10, 210a, 210b, 442) coupled to the acoustic transducer. Each variably-refracting acoustic lens element has at least a pair of electrodes (150, 160) adapted to adjust at least one characteristic of the variably-refracting acoustic lens element in response to a selected voltage applied across the electrodes. In one embodiment, each variably-refracting acoustic lens element includes a cavity, first and second fluid media (141, 142) disposed within the cavity, and the pair of electrodes. The speed of sound of an acoustic wave in the first fluid medium is different than the speed of sound of the acoustic wave in the second fluid medium. The first and second fluid media are immiscible with respect to each other, and the first fluid medium has a substantially different electrical conductivity than the second fluid medium.