The next time you see Tupac playing a show, his hologram might be created with sound.
Scientists at the Max Planck Institute in Germany have created an incredible new way of generating 3D holograms using the power of sound, instead of manipulated light.
It works like this: a single speaker is placed in water and emits ultrasonic frequencies that can do anything: from making a cute little dove appear in the water; or move a small paper boat around.
To achieve different shapes or patterns a "hologram plate"; is placed over the speaker. A video about the process explains that “when this [hologram plate] is placed in front of an ultrasonic speaker the acoustic waves push small particles floating in the water into place” creating the hologram. This plate is specially designed to distort the waves created by the speaker and align them in a way that will create the desired effect.
To create 3D holograms, tiny silicone beads are placed on the surface of the water and, when hit by the ultrasound, they align themselves into three-dimensional forms. This process is called acoustic levitation and has been experimented with in the past when acoustic levitation was achieved by using a large amount of small speakers that emit varying frequencies. With the invention of the hologram plate what would have needed over 27,000 individual speakers can be done with just one.
This innovation has applications beyond just making silicone balls dance in the air or make a little boat sail around. Ultrasound is already used regularly in the field of medicine for treating things like kidney stones, and with the introduction of these hologram plates doctors will be able to use ultrasound to treat patients much more efficiently.