Inspired by Star Wars, BYU’s Futuristic 3D Display Tech Works Like This …

daniel smalley optical trap 3d printer of light byu brigham young university volumetric display

It started with Star Wars, says Brigham Young University engineering professor and holography expert Daniel Smalley.

But it was Iron Man hero Tony Stark who sealed the deal.

And, as deals go, this one’s huge. In a paper published in Nature recently, Smalley’s team announced it had achieved a world first: It had built a true, 3D volumetric display that, like Princess Leia’s hologram message to Obi-Wan Kenobi in Star Wars (1977), could project free-floating, 3D moving image in the middle of thin air.
optical trap princess leia smalley
Our group has a mission to take the 3D displays of science fiction and make them real,” Smalley said. “And we’ve done that.”

Smalley’s team wasn’t the first to try to replicate the Leia projection. Over the years, several research groups around the world have tried, but failed, to duplicate the holographic feat.

The problem was that everyone has been trying to use holography to mimic that holographic projection in the movie.

But one day, while watching a scene from Iron Man, Smalley noticed that holography could never be used to create the VR suit in that film.

“It was an epiphanic experience,” he said. “When Stark sticks his hand in over the lit-up table, he’s blocking the light.”

You know, until that moment, “Until that point, you know, I’d honestly thought holography could do anything.” But afterward, he knew one thing it couldn’t do. “There’s no way you can use holography to create those images,” Smalley says.

“You can’t block the light in a hologram.”

“And it suddenly occurred to me that you’d have to build this, not with one light source, but with a bunch of flying, floating nanobots, and all of them shooting lasers!”

Laser-firing nanobots? What?

Don’t laugh. The so-called optical trap display (OTD), also known as a phophoretic display, isn’t so much different from floating, laser-firing nanobots. Not in principle, anyway.

The display works by focusing an array of tiny, near-invisible lasers at a single particle — moving it rapidly through the air to create a rapid-fire illusion of an image.

Think of it as a kind of twist on an Etch-a-Sketch toy. The lasers rapidly move that light-catching particle in the desired 3D shape — and it happens so fast, the human eye takes it in like a whole image.

The result is full-color, aerial volumetric images with 10-micron image points, which appear as persistent images to anyone looking at it.

Smalley’s team’s so-called optical trap display (OTD), also known as a phophoretic display, draws images in the air in much the same way that an Etch-a-Sketch toy does, he added.

It utilizes an array of near-invisible lasers to manipulate a single tiny particle in place.

Essentially, the display is utilizing a laser beam to trap a particle. Once trapped, the laser beam moves the particle about in the air, which creates an image sort of like the one you see when kids draw shapes in the air with sparklers.

The easiest way to understand the innovation is to think of it as a 3D printer of light.

It’s not such a stretch. “You’re actually printing an object in space with these little particles,” he said. “You might think of it as a 3D printer — of light.”

“The images are rudimentary, as you can see from the videos and images in this article. But they’re likely to get a whole lot bigger and more detailed, Smalley said, pointing out that just using multiple cellulose particles (instead of one) to “draw the light” make all the difference. That parallelism in particles, he added, likely will require all sorts of light modulation and other optical tech, he says, but eventually running multiple particles in parallel should allow these displays to project larger and larger images.”

And once we get to 100 times or 1000 times what we’ve got now, I think the sky is the limit for applications.”

Smalley’s BYU-based electro-holography research group isn’t just developing various methods and techniques for creating the first ever low cost ‘holographic display,’ using the term loosely.

The team also is researching other uses for photophoretic traps like the Smalley’s OCD.

One potential use for the tech, Smalley suggests, is satellite tracking. “Human operators on Earth have to track satellites that are traveling thousands of miles per hour and along non-linear paths. They have to keep them from colliding, basically, which is stressful,” Smalley continued. “And they have to abstract all that from a regular, 2D display.

But if we could create a volumetric display with a trapped particle (matched) to each tracked object, then the satellite tracker could see — intuitively and viscerally — if two satellites are going to crash,” he added. “That would reduce collisions — as well as the cognitive load on the trackers,” he said.

Another intriguing use for the volumetric display, he added, is to build ultra large displays as projected from small devices.

“Think about mobile phone size and portability, too,” he added. “There’s always a push/pull effect for size and portability. But what if you could decouple the size of your screen with the size of your phone?” Smalley said.

“Once you decouple them, you could, say, start using your smartwatch as a peripheral to your smartphone. If you could get it the (volumetric display) to project out a sufficient large image you even could replace your phone with that watch. I’m not claiming we’ll be able to miniaturize our (OTD) design to this degree, of course. But technologies like this one, which can theoretically be used to project images far, far larger than the projecting device itself, have great promise, he said.

These are just a few examples of the sorts of pragmatic solutions that are possible with this innovation, he said. “But it isn’t quite as fun,” he admits, as chasing future tech as imagined by sci-fi.

“My quest has always been to create the Princess Leia projector .. and also I’ve long wanted to build something like the Holodeck from Star Trek, he adds. “There is great value in work that captures the imagination. Think,” he said, “about Elon Musk’s Falcon Heavy launch.”

Launching Musk’s roadster just seemed whimsical, to say the least. But when the camera started streaming the song, Starman, I found it just totally awe-inspiring.

“I suspect that single moment did more to encourage my kids to become engineers than anything I, as an encouraging parent, had managed up to that point.”

It probably goes without saying, though, that no one had to lure Smalley into the field.

“Put it this way,” he said. “I was a speaker during my high school graduation. And halfway through the talk, I ripped off my cap and gown to reveal a homemade Star Trek uniform underneath.”

“I then went on to explain that, actually, I was a Starfleet historian who’d been slung back to that moment in time, to witness that graduation,” he said.


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Gina Smith is an award-winning journalist and the New York Times bestselling author of Apple founder Steve Wozniak's biography, iWOZ: How I Invented the Personal Computer and Had Fun Doing It (2006/2014, WW Norton) and The Genomics Age (2005/2015, Amacom), a Barron's book of the year. She holds a brand new PhD in cognitive psychology.


  1. Yes, for some people their own Imagination can feel as real as Smalleys in mid air materializing 3D-images and these people perhaps may create stuff like in mid air materializing images.
    Huge Volumetric Displays would be ideal for movie theatres, because they already try to attract people with innovative technology like 3D movies, but they have a hard time to do so, because TV sets and home cinemas compete with movie theatres. Movie projection in a movie theater happens in a controlled environment and I guess that the Optical Trap Display works also best in a controlled environment and that wind and weather would interfer with the movement of the optical trapped particles which draw the image. A smarthone is perhaps not the best ODR projector because of the lack of a controlled environment but the projector in a movie theater may be very well suited for giant volumetric displays.

  2. I wonder what it would be like to implement a brain computer interface device to print interactive volumetric holograms directly from thought or to control self-reconfiguring robots made up of a large ensemble of nanobots, just to start with.

  3. Gina,
    I think that something like the claytronic nanobots will work as N actuators and can electrostatically latch on to each other and detach, but slowly detach, unless we decide to replace the van der waals intermolecular force with something that works alot faster.

    I hope you don’t mind if I use wikipedia as a reference.

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