Rabbit hologram acoustically levitated by 256 loudspeakers

A levitating 3D rabbit hologram that can be deployed near other objects and above bumpy spaces has been created using ultrasound waves from 256 little loudspeakers.

The hologram, which also requires a projector and a canvas to be raised above the ground, was developed by scientists at University College London.

Researchers could previously only manage acoustic holography in empty spaces and its use in crowded spaces is made possible by a new algorithm, which quickly readjusts sound waves to keep an object in the air.

The breakthrough is said to make acoustic holography feasible in Pro AV markets such as museums and advertising displays.

According to a report in the New Scientist, researchers demonstrated their acoustic holography technique by 3D printing a small plastic rabbit and levitating objects near it, arranging the 256 small loudspeakers producing the ultrasonic waves in a grid.

In one experiment, the scientists made illuminated beads fly around the rabbit in the shape of a butterfly whose wings could be controlled by the motion of fingers. In another, they levitated a piece of nearly transparent fabric above the rabbit, and made it spin while a projector cast images of the rabbit onto it, to create a 3D rabbit hologram hovering above the plastic rabbit. The researchers also levitated a drop of paint above a glass of water.

The scientists have so far only considered acoustic levitation in spaces full of sound-scattering objects that don't move at all or move only in predictable ways such as a hand trying to touch a levitating hologram.

Their next goal is to perfect mid-air object manipulation using sound when objects in the room are moving in unexpected and unanticipated ways.