Blade Runner 2049 hologram

Holograms: imaging in a new dimension

Image credit: Rex Features

Holographic and 3D visualisation companies are finding new ways to take the quality of holograms to the next level.

The idealised AI-designed woman who appears in an advertisement in ‘Blade Runner 2049’ (pictured above) shows how far the possibilities of holography continue to capture the imagination of science-fiction writers.

For an earlier generation of film-goers, this manifests itself in the form of a wise old man patting the head of an unidentified droid, when suddently a ray of blue light springs out from it, forming itself into a slender robed figure that floats in mid-air. The image of the young woman presents a desperate message before signing off: “Help me, Obi Wan Kenobi. You’re my only hope.”

Ever since Princess Leia made that first dramatic appearance in the original ‘Star Wars’ movie of 1977, it has remained the popular defining image of a hologram, and something of a holy grail for holographic researchers.

However, achieving something with similar capabilities in the real world has so far proved elusive.

Several effects that look a lot like the Princess Leia hologram have appeared in popular culture in recent years. Rapper Tupac Shakur and pop star Michael Jackson were both resurrected to play ghostly live sets. And most recently, Democratic presidential candidate Andrew Yang announced that he will be using holograms of himself as part of his campaign in locations around the US. But these spectral images are not really holograms. They are optical illusions involving reflection, known as Pepper’s Ghost, that have been used in theatres and fairgrounds for over a hundred years.

“The correct physical definition of holography is using the diffraction of light to create images,” says Khan. Such ‘real’ holograms, it turns out, have a lot less wow factor. They require screens or arrays of screens for display, they can’t be viewed from every angle – usually requiring a ‘sweet spot’ where the viewer needs to be positioned – and need huge amounts of processing power to produce simple moving images.

But that might all be about to change with the development of new techniques. “Light field displays are the emerging technology of the moment,” says Khan. “They take a volume of space and slice it up like a cake in a circular fashion. This means you can have occlusion – so when you move your head you can see behind and around things.”

Khan’s Scottish-based Holoxica uses light field displays provided by a company called Looking Glass Factory – they look a bit like a fish tank with the 3D image displayed inside – to visualise data in the form of holograms. These 3D visualisations have a wide variety of applications, ranging from models of the universe based on data from the Hubble Space Telescope, to subatomic particle tracks from the Cern particle accelerator. “We’ve seen the whole of creation in terms of data,” says Khan.

Holoxica’s clients require their data to be viewable in 3D without the use of clunky headsets. The bio-medical sector is one key area where 3D models can provide invaluable teaching and training resources. “2D doesn’t cut it,” says Khan. “Students need to know that this vein is behind this bone and in front of that artery, and no matter what you do in terms of books it’s just not happening.”

Holoxica has created detailed holograms of all the organs of the human body and is working on surgical applications like hip implants, knee replacements and cataract removals. “Surgeons are now obliged to explain what’s going to happen to their patients,” says Khan. “And if they can do that in 3D, it’s just a lot faster.”

Optical illusion

Pepper’s Ghost

Pepper’s Ghost is the name of an optical illusion that was first described in the mid-16th century. Its use was popularised in Victorian London by engineer Henry Dirks and scientist John Henry Pepper, where it was used to create illusions on stage such as the appearance of ghosts. It is still employed today, being the technique behind the posthumous live performances of Tupac Shakur and Michael Jackson.

The trick works by placing an unseen piece of glass between the audience and the stage at a 45-degree angle. A second, darkened room is concealed off stage in which the objects that will form the illusion are placed. By raising the lights in the concealed room the objects are reflected off the surface of the glass, appearing to the audience as if they are behind the glass, on the stage.

Another company using light field displays is Leia, a Silicon Valley start-up whose inspirations are clear from the name. Leia’s technology is a nano-engineered layer that can be fitted to existing screens. “We add a very thin backlight to an LCD display,” says Leia founder and CEO David Fattal. “This diffractive layer is located between the 2D backlight and the LCD panel. It’s completely transparent and is able to send light in different directions in space. It’s all afforded by a diffractive nano-pattern, which is about 100 nanometres in size.”

Because this nano-patterned layer is compatible with any LCD display, Leia’s technology can operate on mobile devices. The company’s collaboration with Red Digital Cinema produced the Hydrogen One, a handset that could display holograms. The great trick here was not the 3D image itself, but the processing power needed to produce it, which is usually far beyond the reach of a mere mobile phone.

Leia achieved this by limiting the number of views. “Instead of trying to render 16 views at full resolution, we get by with just rendering four,” says Fattal. “So the amount of processing is actually less than processing a full-resolution 2D image.”

Leia’s technology can also be fitted to tablets and computer monitors, but perhaps the most exciting development is its recent partnership with German automotive manufacturer Continental to produce holographic in-car information and entertainment systems. Think of the Tesla tablet but with 3D images popping out.

“We’re planning to start equipping cars in 2022,” says Fattal. “And we’re going to distribute content services on top of that – games and linear content and movies and apps.” If that all sounds a bit dangerous, it’s because Leia has one eye on the future when cars are fully autonomous. “You’re going to spend hours in your car where you’re doing absolutely nothing,” says Fattal, “so that need for entertainment is what we’re addressing here.”

Continental_PP_3D_Natural_Display

Image credit: Continental

Perhaps the most promising of all the new techniques is one that isn’t strictly holography at all. A new method of 3D visualisation from researchers at Brigham Young University in the US has managed to achieve the closest thing we have to the hologram in ‘Star Wars’ – a free-floating image formed, seemingly, of light.

The optical trap display uses high-​intensity lasers to trap a tiny particle of cellulose. Once the particle is trapped it can be moved around at high enough speeds that the resulting pattern forms a stable image to the human eye, in much the same way that a sparkler waved at a firework party seems to form a persistent image in space.

This means images can float in mid-air, free from the restrictions of screens and monitors. It also means viewing angles are effectively 360 degrees, and there is no loss of picture quality in different parts of the image.

“With 3D displays based on a screen you will notice that images that are farther away from the screen get fuzzy,” explains Daniel Smalley, lead researcher on the project. “But with this display the particle size doesn’t change so the image is sharp wherever it’s drawn.”

‘The correct physical definition of holography is using the diffraction of light to create images’

Javid Khan, Holoxica

The only problem so far is that the technique can only manipulate a single particle, limiting the size of images to not much larger than a thumbnail. Smalley hopes this problem will be overcome by trapping multiple particles in a two-dimensional plane, which can be swept up and down. “I think we’re about 6-10,000 man or woman hours away from a scaled display,” says Smalley, “by which I mean eight-inch-tall [20cm] images instead of one-centimetre-tall images.”

Once the technique can be scaled up, the applications could be very exciting. One could be air traffic control, which consistently ranks as one of the most stressful jobs in the world. “A lot of the cognitive load comes from the fact that you’re looking at a two-dimensional picture and interpreting it in three dimensions,” explains Smalley. “Instead, you could look at this 3D image and track where a plane or satellite is with ultra-high spatial accuracy and viscerally understand whether these two satellites are going to smash into each other.”

Another application could be catheterisation for heart surgery. Currently this is done by surgeons taking multiple X-rays and working from a 2D screen as they thread the catheter through the arteries towards the heart. Any scraping of the catheter against the artery wall can cause an abrasion, which could lead to an embolism, so the procedure is incredibly delicate and risky. “If you can have an accurate 3D model, you can reduce the amount of X-ray radiation that patients are exposed to,” says Smalley, “and you might be able to improve outcomes.”

In the further future, Smalley envisages a holographic version of a digital assistant like Apple’s Siri or Amazon’s Alexa – imagine your own Princess Leia hologram showing you how to change the fuse in a plug. And even further out he imagines a version of the device that could be fitted to a soldier’s rifle. “They could spray these particles out in front of them and have a projection of a decoy soldier running down an alleyway taking bullets.”

All interesting speculations, but how likely is a world where we send and receive holograms of ourselves Princess Leia style, or have 3D images of Alexa pop into our lounges, genie-like, to answer our questions? That depends how the technique scales up. Smalley is hedging his bets, giving it a fifty-fifty chance of being a life-changing technology. If it does succeed, he envisages a world that increasingly does without screens or headsets, where we are able to be present remotely and experience data in a more visceral manner.

“It will be us living with our data,” says, Smalley, “without having to reach through a screen to get it, where data is part of the physical world around us like chairs and rocks and things.”

Timeline

Holography

1947: Hungarian scientist Dennis Gabor discovers the concepts of holography while working on a project to improve the quality of electron microscope imagery. He is later awarded the Nobel Prize for his work.

1960: The invention of the laser provides a suitable light source to further develop holography.

1962: The first practical optical holograms that record 3D objects are made by Yuri Denisyuk in the Soviet Union and Emmett Leith and Juris Upatnieks at the University of Michigan, USA.

1967: The first holographic image of a person is made.

1968: White light transmission holography is invented by Stephen A Benton, enabling holograms to be viewed using everyday white light.

1974: Michael Foster invents a technique to mass-produce holographic images. Embossed holograms can be printed onto plastic or paper, creating the holographic images we are familiar with today on bank cards and notes.

 

 

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