Simulated and experimental demonstrations of the first acoustic hologram enhanced phased arrays for manipulation

When attempting to form a desired static sound field for manipulation, acoustic holograms are generally superior to phased arrays due to their immensely higher resolution. However, they lack the dynamic capabilities of phased arrays. We therefore demonstrate a combination of the two. We produce several holograms for use with a continuously excited 64-element linear phased array. Simulations were used to predict the expected range of performance. We then experimentally demonstrate moving the position of the projected hologram plane via phase delays which tilt the output of the phased array. This creates a much more tightly focused point than the phased array alone, whilst retaining dynamical control. A second hologram allows the complex movement of a “phase surfer” along a phase track. These examples demonstrate that the strengths of both phased arrays and holograms can be combined. These developments open the door for more complex manipulation in the future whilst maintaining a relatively simple electronic set-up, thus reducing the cost whilst increasing the capability.