Boffins switch on holographic TV

US academics have developed imaging technology that allows them to display what they claim to be the first truly three-dimensional holographic movies.

The creator of the so-called "holographic television", Dr Harold 'Skip' Garner, professor of biochemistry and internal medicine at the University of Texas Southwestern Medical Center in Dallas, conceded that the technology will "not be coming soon to a theatre near you".

Dr Garner said that entertainment applications could include 3D multiplayer games, theme park or advertising displays and holographic TV.

Dr Michael Huebschman, a postdoctoral researcher in Garner's lab and one of the developers of the technology, said: "I predict that, by the year 2020, that being the year of 'perfect vision', we will have holographic TV in our homes."

The video system is based on complex optics principles, sophisticated computer programs, and a small chip covered with about a million tiny mirrors.

The heart of the system is the digital light processing micro-mirror chip, made by Texas Instruments and currently used in television, video and movie projectors.

These devices incorporate a computer that processes an incoming digital signal several thousand times a second, changing the angle of each micro-mirror to reflect light from a regular light bulb. The resulting image is a two-dimensional video projected onto a screen.

One of Garner's innovations was to replace regular light with laser light. Such light is coherent, meaning that it comprise light of a single wavelength, with all light waves travelling 'in phase' with one another. Light from a white light bulb comprises many different wavelengths that are out of phase.

The system also requires a different kind of digital signal than those feeding into today's projection TV sets.

The signal is a sequence of two-dimensional interference patterns, called interferograms, which can be generated either from scratch or from data gathered from 3-D imaging applications, such as sonograms, CAT scans, magnetic resonance imaging, radar, sonar or computer-aided drafting.

"This technology is potentially powerful for medical applications," said Garner. "We could easily take data from existing 3-D imaging technologies and feed that into our computer algorithms to generate two-dimensional interferograms."

On a computer screen, interferograms look like tiny random black dots similar to an off-the-air TV channel's 'snow'. But the patterns, when fed into the digital light processing micro-mirror chip, cause the tiny mirrors to change in a way that, when laser light is reflected off them, a 3-D moving image appears suspended in air, in a special material called agarose gel, or on a stack of liquid crystal plates similar to computer screens.

Holographic visualisation of human organs, for example, would improve diagnosis of ailments such as a swollen, damaged or malformed heart, Garner explained.

Other possible medical applications include visualisation aids for training surgeons, measuring teeth and bone development, and viewing the possible results of plastic surgery before it is actually done.

Garner and his colleagues have worked with students at Southern Methodist University's Cox School of Business to develop a tentative business plan that explores the possible commercialisation of the technology, focusing on medical applications.

"An important next step is to take our proof of principle technology that we have now and move it into a commercial entity," said Garner.