Holograms Are No Longer Science Fiction. But Then What?

Movies and science fiction have shaped human expectations - often unrealistically -about many forms of technology. But those expectations are also driving the next generation of applications. JL


Dave Hall reports in The Guardian:

Like the 3D TV, we’re far, far away from the sort of color, resolution and contrast required to push these images beyond mere novelty. But holograms have a future in the fields of remote surgery and telecom. We are already using 3D technology, from autocad and ultra-realistic remote conferencing, to medical technology that allows surgeons to operate remotely or students to learn anatomy.
The fragile apparition endured only long enough to say: “Help me Obi Wan Kenobi, you’re my only hope” before flickering out. But R2D2’s 3D projection gave millions of young eyes, including mine, their first taste of holograms, and planted unrealistic expectations of a future playing dejarik, the gruesome game of holographic chess played on board the Millennium Falcon.
The concept of the hologram was already familiar, invented in the 1940s by physicist Dennis Gabor, but since the force reawakened the idea almost 40 years later, things haven’t really moved on. Why aren’t real, moving, Leia-style holograms now part of our day-to-day lives?
That depends on your definition of a hologram. We have made astounding strides in 3D TV and virtual reality, and in the eye-twistingly complex world of computer-generated holography (CGH) – simply put, a way of recording and reproducing 3D images on a medium like standard images on film. Getting those images to move is a huge challenge.
What the the rest of us probably want to see is an independent 3D image you can see from any angle, one that behaves like a solid object – what some scientists call the volumetric image. And special headgear or glasses somehow seems like cheating. Obi Wan didn’t need them, after all.
Of course, we are already using 3D technology, from autocad and ultra-realistic remote conferencing, to medical technology that allows surgeons to operate remotely or students to learn anatomy.
Indeed, 3D TV caused objects to leap off the screen, but it only worked at certain angles and the specs were a bore. The market sniffed a gimmick and it was gone as quickly as it arrived. Now TV is all about ultra high-definition 4K, leaving Samsung as the last company trying new approaches to 3D TV with lasers and eye-tracking. Whether people will want to watch it is another question.But wait. Didn’t I see rapper Tupac eerily brought back to life at a festival somewhere? Yes, but you didn’t see a hologram. The image you saw wasn’t even 3D – and the idea is far from new. The trick has been around since the early 19th century, used to magic up fairground hauntings, using what’s called the Pepper’s ghost effect. Images are simply projected on to a semi-transparent screen against a dark background, now updated with an interactive twist.
The work being done by the University of Southern California Institute for Creative Technologies comes closest to the Leia effect, with its eerie interactive 360-degree light-field display. It works by projecting light on to a rapidly spinning mirror, reflecting a blue image of a head that can be turned about and viewed from any direction. Sony used the technology for its prototype Ray Modeler 360-degree colour display, a tube-shaped appliance that wouldn’t look out of place in the living room.But Princess Leia didn’t need a tube. And 3D telepresence isn’t quite what our childhood imaginations longed for, even if it means those Shield meetings in Avengers might become reality.

CGH is the holy grail of holography, but it demands colossal computing power to generate the required interference-based images at a speed suitable for real-time video. At the required “nearly one quintillion operations per second ... this is 300 times faster than the current world’s fastest computer. According to Moore’s law, [the technology] will not hit desktops until the year 2046,” says Prof Pierre-Alexandre Blanche from the University of Arizona’s college of optical sciences. I can’t wait that long for my game of holochess.
Instead, Blanche and team have developed what he calls “a stepping stone for holographic television” by writing a holographic stereogram
on to a photorefractive polymer, which is then continuously refreshed, giving the illusion of movement.
While it may never be possible to fabricate an image like Leia’s out of thin air, as photons simply don’t like behaving that way, Brigham Young University researchers and their incredible volumetric image come pretty close. The university’s assistant professor of electrical and computer engineering, Daniel Smalley, and his team created a floating 3D display using lasers to move particles around in the air, resulting in the illusion of solid lines. It can generate tiny images at up to 1,600 dpi. To create larger images they are working on ways to manipulate multiple examples at once, but the technology may still be years away from daily use.
All these ideas share one drawback: they’re all sensitive to vibration and air turbulence, and at present, they’re all pretty simple images. Like the 3D TV, we’re far, far away from the sort of colour, resolution and contrast required to push these images beyond mere novelty. But holograms already have a future in the fields of remote surgery and telecoms. And soon – who knows – lifelike games of chess.