Although 3DTV didn’t experience the take-up many expected, the quest for fully immersive viewing is still alive, with holography being one of the top options. But how far away is the technology from being available in the living room?

For many of us, the concept of a hologram still conjures images of old science fiction films – R2D2 projecting an image of Princess Leia in Star Wars Episode IV, the ‘holodeck’ which made an appearance on many Star Trek episodes…the list goes on. Seeing these scenes often made the technology seem light-years away. However, in recent times, holograms have broken into popular culture, especially in live music; we’ve seen the animated band Gorillaz come to life onstage alongside Madonna, and a startlingly-realistic hologram of the late Tupac Shakur making an appearance at Coachella music festival last year.

The team behind many of these great stunts is London-based Musion.

“Technology is getting better and the creativity we’re seeing is remarkable,” says Musion director James Rock.

“It isn’t just the projection of people. Over the years we’ve shown just what the medium is capable of, from simple floating graphics to more complicated motion-capture techniques, 3D animation and morphing, complete digital creation/resurrection, and large-scale pre-recorded and live broadcasts,” James says.

Although the technology is inevitably cutting edge, it isn’t a hologram in the way you might expect – the 3D image isn’t simply projected into thin air. In fact, it’s a modern day twist on a Victorian stage technique called Pepper’s Ghost. Using an ‘invisible’ foil that is rigged across a display environment at 45º, video content is projected onto a bounce screen which then reflects onto the foil. Due to the angle of this foil, it gives the impression that a real, 3D volumetric image is in view.

“It’s essentially simple geometry and the manipulation of reflections with ultra-bright video projection,” James says.

“Some clever lighting, stage dressing and post production generally finishes off the illusion.

“There’s always going to be a space limitation, even with our small-form, compact technology: Musion EyeCandy. For our full-scale product, Musion Eyeliner, you need an even greater area and the correct lighting conditions.”

The EyeCandy and Eyeliner are both suited to pre-recorded content, but Musion’s TelePresence system adapts the technology to project life-size HD 3D holograms live. Musion recently won a Guinness World Record for its work in India where over 50 simultaneous holographic projections of Indian politician Narendra Modi were shown across the northern state of Gujarat.

Currently, Musion’s brand of holography is only suitable to big-budget commercial enterprises; however, it brings the technology out of the movies and into the public’s conscience, which can only be a good thing in the quest to introduce it into the home.

Researchers at Massachusetts Institute of Technology (MIT) have made this their mission for a number of years now. The team first got involved with holography in 1989 under the guidance of the late Professor Stephen A. Benton who invented the rainbow hologram in 1968 – a hologram designed to be viewed under white light illumination.

Michael Bove, head of the lab’s Object-Based Media Group, co-wrote Holographic Imaging with Stephen and has written or co-written over 60 journal and conference papers on digital television systems, video processing hardware/software design, multimedia, scene modelling, visual display technologies and optics.

Michael anticipates that holographic TV will be available in the next 10 years.

“Holographic TV would be the ultimate no-glasses 3D reconstruction of scenes, with applications in entertainment, data visualisation, communication and anywhere else a 2D screen is currently used,” he says.

“There are probably only about 15-20 research groups worldwide doing serious work on this at the moment. The problem is, the images that have been created are usually small, and if they are large, they usually only have look-around angles of a few degrees, or frame rates that are too slow for moving scenes.”

Further, the equipment needed to produce the imagery tends to be expensive and impractical. This is a problem the team at MIT has been working hard to resolve. They recently revealed a new approach to generating holograms that could lead to full-colour holographic video displays that are much cheaper to manufacture than the experimental, monochromatic displays currently available.

“I’m hoping that we and others can make inexpensive screens big enough for desktop use. The living room will take a bit longer,” Michael says.

Daniel Smalley, a graduate student in the MIT’s Media Lab, is building a prototype colour holographic-video display with a resolution that is roughly that of a standard-definition TV, which can update video images 30 times a second – fast enough to produce the illusion of motion. At the heart of the display is an optical chip, which resembles a microscope slide that Daniel built using only MIT facilities, for about $US10.

Every holographic video display is built on a spatial light modulator, which directs light by diffraction to form points in three-dimensional space. The problem is, they are challenging to use because they have relatively low bandwidth, high cost, low diffraction angle, poor scalability and the presence of quantisation noise, unwanted diffractive orders and zero-order light.

MIT recently presented modulators based on anisotropic leaky-mode couplers, which have the potential to address all of these challenges. These modulators can be fabricated simply, in large quantities and at low cost. They also demonstrate polarisation rotation, enlarged angular diffraction and frequency domain colour filtering, which makes them a viable platform for low-cost, high-performance holographic video displays.

The University of Arizona is also carrying out extensive research in holography and the university’s assistant research professor of optical sciences, Pierre-Alexandre Blanche, says he is impressed at the work MIT is currently carrying out.

“The technology MIT has introduced establishes a completely new way of generating a hologram. It is cheap and efficient so it has many advantages,” he says.

“It is important to see if these new tools will help solve some of the major problems that holography is facing, such as the ‘speckle’ that prevents the sense of texture.”

Previously, this speckle could only be reduced by a trade-off of the holographic resolution.

“Also, it will be interesting to see if we can scale up the device to a large screen without the optics interfering. This can be achieved with a diffuser, but this is very annoying to look at.”

The University of Arizona is focusing its efforts on stereographic holography – a different approach to MIT. This method is less reliant on computer performance, so it is more likely that a solution will be found in the short term.

“Electro-holography requires the calculation of the interferometric pattern which is computationally intensive. This means that there is a bottle-neck real-time display. Spatial bandwidth has also been an issue, but the MIT team seems to have minimised this.

“On the other hand, although stereographic holography doesn’t require a lot of computation, the phase is lost and the depth of field is limited. The jury is still out to find which technology is the best.”

Pierre-Alexandre says that as well as high cost issues, the quality of holography is still not up to speed, and this is severely impairing the proliferation of the technology.

“The amount of information in a hologram is huge. Instead of 2D, the information is 3D, which means you need to have all the optical information from many different perspectives as well as the phase. It is extremely hard to compute all the finest details, such as object texture. So far, I have never seen a computer-generated hologram that reproduces texture – they are all grainy.

“Stereographic holograms with excellent texture and colour reproduction do exist, and those images are the finest examples of 3D. However they are not yet available via video.”