Daniel Smalley is an Electrical and Engineering Professor with a dream to create the iconic floating 3D image messaging system made famous by Star Wars, in real life.
Incredibly, Smalley has done it. He is quick to point out, however, Princess Leia's message was never a "hologram" - but a 3D light-printed image.
Smalley and his team call it "The Princess Leia Project", creating what is actually a volumetric image, not a hologram. The research paper, published in Nature, explains:
Free-space volumetric displays, or displays that create luminous image points in space, are the technology that most closely resembles the three-dimensional displays of popular fiction.
Such displays are capable of producing images in ‘thin air’ that are visible from almost any direction and are not subject to clipping. Clipping restricts the utility of all three-dimensional displays that modulate light at a two-dimensional surface with an edge boundary; these include holographic displays, nanophotonic arrays, plasmonic displays, lenticular or lenslet displays and all technologies in which the light scattering surface and the image point are physically separate.
A holographic display scatters light only at a 2D surface. If you aren't looking at that surface, you won't see the 3D image because you must be looking at the scattering surface to see the image.
A volumetric display has little scattering surfaces scattered throughout a 3D space — the same space occupied by the 3D image — so if you are looking at the image you're are also looking at the scatters. For this reason, a volumetric image can be seen from any angle.
How exactly the team have created a volumetric image, in simple terms is by using a laser beam to trap a particle - then by steering the laser beam around to move the particle and create the image.
"This display is like a 3D printer for light," Smalley said. "You're actually printing an object in space with these little particles."
The team have begun printing a whole range of objects - a butterfly, a prism - and someone in a lab coat recreating Princess Leia as she calls on Obi Wan Kenobi for help.
This isn't the first time researchers have created volumetric imagery, but it is the first time optical trapping and color have been used effectively, trapping particles and illuminating them with colorful lasers.
"We're providing a method to make a volumetric image that can create the images we imagine we'll have in the future," Smalley says.