The technology – which is reminiscent of the system used by R2D2 in the original Star Wars film to project an image of Princess Leia in distress – is a so-called volumetric display.
Unlike a holographic display, which scatters light only at a 2D surface, a volumetric display has little scattering surfaces scattered throughout a 3D space - the same space occupied by the 3D image. This means that if you are looking at the image you're are also looking at the scatters, and for this reason, a volumetric image can be seen from any angle.
In a paper published in Nature, Professor David Smalley, who headed up the project explained that he and his team have devised a free-space volumetric display platform, based on photophoretic optical trapping, that produces full-colour, aerial volumetric images with 10-micron image points by persistence of vision.
"We're using a laser beam to trap a particle, and then we can steer the laser beam around to move the particle and create the image," said undergrad co-author Erich Nygaard.
Smalley said the easiest way to understand the process is to think about the images it creates as 3D-printed objects. "This display is like a 3D printer for light," he said. "You're actually printing an object in space with these little particles."
So far Smalley and his student researchers have 3D light printed a butterfly, a prism, the stretch-Y BYU logo, rings that wrap around an arm and an individual in a lab coat crouched in a position similar to Princess Leia as she begins her projected message.
While previous researchers outside of BYU have done related work to create volumetric imagery, Smalley's team is the first to use optical trapping and colour effectively.
Commenting on the debt the technology owes to the imagination of the Star Wars creators Smalley said: "We refer to this colloquially as the Princess Leia project. Our group has a mission to take the 3D displays of science fiction and make them real. We have created a display that can do that."
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