An apparatus for investigating a subsurface volume may include an acoustic transducer disposed in an enclosure and generating acoustical signals, an electronics assembly disposed in the enclosure and controlling the acoustic transducer, and a lens assembly. The lens assembly may be disposed in the enclosure and next to the acoustic transducer. The lens assembly may be formed of a plurality of cells. Each cell may be formed as a column oriented transverse to a direction of travel of the acoustical signals. Each cell may have a hub, a plurality of spokes radiating from the hub, and a plurality of fingers circumferentially distributed around the hub. The hub, spokes, and fingers may be oriented to cause the acoustic waves to travel at a different speed in each of three orthogonal directions. A related method uses the apparatus in a wellbore.