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The 3-D displays seen in such sci-fi movies as Star Wars may not be so far, far away.

A new laser system renders full-color 3-D images in thin air, researchers report in the Jan. 25 Nature. This technology could someday make futuristic, free-floating visuals for everything from air traffic control to surgical planning.

With this new technology, “you really can, in principle, achieve what everyone hopes to achieve, which is the image of Princess Leia in that scene in Star Wars,” says Curtis Broadbent, a physicist at the University of Rochester in New York who was not involved in the work.

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Whereas holograms are images on flat surfaces that only appear three-dimensional because of how the light bounces off the material, the newly created images actually take up 3-D space (SN: 12/4/10, p. 8). Two-dimensional images of virtual performers can also be made to appear 3-D through stage tricks that involve carefully placed projectors and reflective surfaces. But like holograms, these seemingly 3-D images can only be viewed from certain angles. The new technique creates 3-D images that can be seen from almost any direction.

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Using a nearly invisible laser, researchers can steer a tiny glowing particle through a path in 3-D space to create images that can be seen from almost any angle. Here, the team draws a butterfly (left), a portrait of Princess Leia (middle) and a squiggle (right).

This system works by trapping a cellulose particle that’s mere micrometers across in a beam of nearly invisible laser light. That laser repeatedly moves the particle along a specific path through the air, for example, in the shape of a corkscrew or the outline of a butterfly. At each point on the particle’s path, other lasers illuminate it with red, green or blue light, which the particle scatters in all directions. This creates a single image pixel that can be viewed from all sides.

Because the particle whizzes through the air so quickly and loops through the same path over and over again, all these pixels blur together — like the tip of a sparkler waved so fast that it seemingly smears into a solid line. This creates what appears to be a still image floating in the air.

Daniel Smalley, an electrical engineer at Brigham Young University in Provo, Utah, and his colleagues used this method to produce graphics about the size of a postage stamp. Because the technology draws a picture with a single particle, the researchers could create only small images, including a high-resolution picture of Earth about one centimeter in diameter.

“Scaling that up to even something about the size of a computer monitor would be pretty challenging,” Broadbent says. Researchers would have to refine their prototype to make pictures using many particles.

Smalley says he is already imagining a system that manipulates 100 or even 1,000 particles at once. With those improvements, “the sky becomes the limit,” he says.

PARTICLE PAINTING Researchers created a 1-centimeter-wide image of Earth (photographed hovering above a fingertip) by using a nearly invisible laser to drag a glowing 10-micrometer particle back and forth. D.E. Smalley et al/Nature 2018

Free-floating images could help doctors practice surgery before the patient goes under the knife, says physicist Barry Blundell of the University of Derby in England, whose commentary appears in the same issue of Nature. This technology could also be used for physical therapy or improving athletic performance. People could record themselves performing various activities, like swinging a golf club, and then view the footage on 3-D displays to carefully study their bodily motion, explains Blundell. And if the images can be continually updated with real-time data, such 3-D visuals could provide air traffic controllers with dynamic maps of planes in the air, or help researchers track satellites to ensure they don’t collide.

The possibilities for advertising, education and entertainment systems are endless, Broadbent says. The world may someday be full of pop-up images like those imagined in the film Jurassic World, where museum patrons walk through a hall where a projected dinosaur image stands on display, or like the free-standing visuals used by the character Tony Stark in designing his metal suits in the Iron Man films. And unlike virtual reality systems, these new laser-drawn pictures can be seen with the naked eye: No headgear required. (SN: 3/18/17, p. 24).