One of the most memorable scenes in all of science fiction films is the scene in the original Star Wars movie where Luke first sees the holographic projection of Princess Leia while trying to clean R2-D2. Many fans of that film have been waiting for decades for a similar projection system to launch. Physicists have now created a very close approximation to that Star Wars projection using a laser and particle system. The technique is known as a volumetric display and can make 3D moving images that a viewer can see from any angle.
"This is doing something that a hologram can never do — giving you an
The new projection technique is described in the journal Nature in the January 24 issue. It uses a set of nearly invisible laser beams to trap a single particle of cellulose, which is a plant fiber, and then that cellulose is heated unevenly. The result of that uneven heating is that scientists can push the cellulose around.
That colored light is beamed onto the particle and illuminates it as it moves through space. Humans are unable to discern images moving at rates faster than 10 per second so the movement of the particles appears to our eyes as a solid line. The scientists liken it to a sparkler moved in a circle in the dark, if it moves fast enough, we see a solid circle.
The display can be overlaid on real objects and the result is a floating 3D projection that a user can walk all around in real space. One major caveat, for now, is that the images created are tiny, only millimeters across. Only simple line drawings can be created currently including a moving spiral line and a static butterfly outline.
The big improvement with his new tech over modern holograms is that viewing angles for holograms are limited and are also typically static. While images are small, the new technique allows for moving objects viewable from any angle. One thing that might never go away, even as the new technique is perfected, is the see-through quality of objects.
Nasser Peyghambarian, an optical physicist at the University of Arizona in Tucson, says that the see-through quality is because the human eye doesn’t receive light from a particle at the back of an image as much as the front. Another challenge is that control of the floating particles in the air that are key to the projections is difficult and easily destabilized. The researchers say you won't use it in a hurricane, but eventually, it will be usable outside.