Three-dimensional images seen in movies like Star Wars, Iron Man, or Avatar, although considered by many people to be holograms, are actually volumetric displays.
While holographic displays scatter light on a 2D surface, creating the illusion of a 3D image when looked at a certain angle, volumetric images actually take up three-dimensional space.
A group of researchers from the Brigham Young University, led by Electrical and Computer Engineering Professor Daniel Smalley, have developed a ”free-space volumetric display based on photophoretic optical trapping that produces full-colour graphics in free space with ten-micrometre image points using persistence of vision”.
The project, inspired by popular fiction, started three years ago and has now culminated in a paper published on 24 January in the leading science journal Nature.
“We refer to this colloquially as the Princess Leia project,” said Smalley. “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.”
The process can be likened to 3D-printing, whereby materials are dragged around in space, one drop at a time, to create a three-dimensional object.
With volumetric images, a cellulose particle is trapped with the help of non-visible laser radiation, and then moved around in space, while being illuminated with red, green or blue light, to create the desired image.
Using the new platform, called Optical Trap Display (OTD), the researchers have successfully conjured up butterflies, prisms, a logo of the BYU, and a human-like figure wearing a lab coat, which looks similar to the famous image of Princess Leia uploading a recorded message into the memory banks of R2D2.
In experiments, the OTD was even shown to be capable of rendering images that wrap around, say, a hand, much a bracelet would.
Furthermore, the study could lead to new advances in spatial imaging (important to areas such as neurosurgery) and dynamic imaging (relevant to the fields of fluid dynamics, robotics and sports training).
The research builds on previous attempts to develop volumetric images, and is the first successful attempt at using optical trapping to that end.
“We’re providing a method to make a volumetric image that can create the images we imagine we’ll have in the future,” said Smalley.