Scientists have managed to make some lovely 3D-printed holograms via sound waves that aids technology and could be useful for medical ultrasound applications.
Holograms are three dimensional images that have been projected via the manipulation of light. Yet the question remains whether a hologram can be made through sound?
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In fact, the answer to this is a resounding yes. Scientists in Germany have used small silicone beads which are grouped on the surface of water to form patterns. The shape formed remains as long as the sound waves keep coming. Such is the wonderful world of acoustic holograms.
Researchers from the Max Planck Institute for Intelligent Systems and the University of Stuttgart reports about the first acoustic hologram in this week's issue of the journal Nature.
The concept is one that almost reminds us of holograms formed aboard Star Trek as shown on television. The only difference is that instead of light, sound is employed.
The scientists made beautiful water rings in the form of a dove, caused a drop of water to literally levitate and caused small paper boats to float on the surface of the water. It was all in all quite a show that went on solely due to sound waves.
Acoustic levitation was the name of the game. This was a technique that studied bubbles and foams. They were kept in mid-air to keep gravity from causing them to drop back into the water.
All that was required was a transducer which is a vibrating surface. This produced the sound waves. Furthermore, a reflector and sound waves with the right frequency were the necessary requirements.
The right sort of interactions led to troughs and crests canceling each other out completely. Thus small objects such as insects and fish could be levitated at the drop of a hat.
Sound waves of different amplitudes and frequencies were reflected off objects from various angles. A speaker was placed beneath the water which acted as the transducer and it projected sound waves up towards the surface.
Previous experiments had required a number of transducers. This time though a single source was required. The crux of the matter was a special 3D printed hologram plate.
Some parts of the plate were more heavier than others. So the sound waves faced quite some difficulty passing through it. A distortion pattern was formed as a result.
This went all the way up to the surface of the water. Thus any object on the surface whether it be a bead or a boat will respond accordingly.