A refractable holographic image of an F-4 Phantom Jet created with the new 3-D telepresence system.
Credit: AFP / Nature / Norma Joean Gargasz / University of Arizona
PARIS: An important step nearer towards three-dimensional (3-D) holographic video, a technology with innumerable outlets in entertainment, conferencing, telemedicine and advertising, has been taken, optical scientists reported this week.
Holographic images that 30 years ago were static can now be updated in "quasi real time," according to the research carried out at the University of Arizona in Tucson. Holograms are created by shining a laser on an object, whose image falls on a photosensitive screen.
Bathed in a red or green laser light, the image has a ‘parallax,’ or a 3-D effect, that is deep, up-and-down and side-to-side. In that regard, a hologram far outperforms stereoscopic pictures which have to be viewed with special glasses.
Around the world in real time
Two years ago, the Tucson team scaled up holography from static to mobile with technology which enabled the image to be updated on a small screen every three to four minutes.
Refinements have now enabled a screen refresh that is nearly 100 times faster, with an update every two seconds. In addition, images can be recorded and transmitted.
"We can record a three-dimensional image in one location and show it in another location, in real time, anywhere in the world," said lead researcher Nasser Peyghambarian.
Compressed by fast-pulsing laser beam
The image is recorded using an array of ordinary cameras, which are positioned to view the object from different perspectives - the more cameras that are used, the more complete the final holographic presentation.
The data is then encoded onto a fast-pulsing laser beam which crosses with another beam to create a so-called interference pattern, or a compression of the image in 3-D form.
The pattern falls upon a special film called a photorefractive polymer, which contains molecules of dye that respond to light and rotate and line up in response to an applied electrical field. The hologram that results fades away within a few minutes or alternatively can be erased and overwritten by a new image.
Transmitting holograms to your computer
"Let's say I want to give a presentation in New York," Peyghambarian explained. "All I need is an array of cameras in my Tucson office and a fast Internet connection. At the other end, in New York, there would be the 3-D display using our laser system. Everything is fully automated and controlled by computer.
"As the image signals are transmitted, the lasers inscribe them into the screen and render them into a three-dimensional projection of me speaking."
In its prototype form, the device uses a 25-centimetre screen, but a larger, 42.5-centimetre version is in the works. Right now, the system can only transmit images in green, but the team have already demonstrated multi-colour 3-D displays and are confident it can be incorporated in the set-up in the near future.
