Nov. 3, 2010
Courtesy of the University of Arizona and World Science staff

Remember the Star Wars scene in which R2D2 projects a three-dimensional image of a troubled Princess Leia delivering a call for help to Luke Skywalker and his allies?

Scientists now claim that the science-fiction concept of 3D moving pictures is approaching reality, thanks to a break through in 3D holographic imaging technology.

A research team led by University of Arizona optical scientist Nasser Peyghambarian has developed a device that allows the projection of a 3D, moving image without the need for special glasses or other auxiliary devices. The technology is likely to take applications ranging from telemedicine, advertising, updatable 3D maps and entertainment to a new level, the developers predict.

The journal Nature chose the technology to feature on the cover of its Nov. 4 issue.

“At the heart of the system is a screen made from a novel photorefractive ma­terial, capable of refreshing holograms every two seconds, making it the first to achieve a speed that can be described as quasi-real-time,” said Pierre-Alexandre Blanche of the university, lead author of the Nature report. A pho­torefractive material is one that can have varying light-bending properties depending on the light hitting it.

The prototype device uses a 10-inch screen, but Peyghambarian’s group is testing a version with a 17-inch screen.

The image is recorded us ing an array of regular cameras, each of which views the ob ject from a different perspective. That information is then encod­ed on to a fast-pulsed laser beam, which interferes with another beam that serves as a reference. The resulting interference pattern is written in to the photorefractive polymer, or plastic-like material, that creates and stores the image.

Each laser pulse records an individual “hogel” in the polymer. A hogel, short for holographic pixel, is the three-dimension version of a pixel, the basic units that make up the picture.

The hologram fades naturally after a couple of minutes or seconds. It can also be erased by recording a new 3D image, creating a new diffraction structure and deleting the old pattern.

“Let’s say I want to give a presentation in New York,” Peyghambarian explained. “All I need is an array of cam­eras here in my Tucson office and a fast Internet connection. At the other end, in New York, there would be the 3D display using our laser system. Everything is fully automated and controlled by computer. As the image sig­nals are transmitted, the lasers inscribe them in to the screen and render them in to a three-dimensional projec­tion of me speaking.”

More over, he added, “as you move your head left and right or up and down, you see different perspectives. This makes for a very life-like image.”

The work is a result of a collaboration between the university and Nitto Denko Technical, a company in Ocean­side, Calif. The system is a major advance over computer-generated holograms, researchers said, which place high demands on computing power and take too long to be generated to be practical.

Currently, the system can present in one color only, but Peyghambarian and his team say they have experimen­tally demonstrated multi-col or 3D display devices capable of writing images at a faster refresh rate, approach­ing the smooth transitions of images on a TV screen.



Article taken from http://www.world-science.net/othernews/101103_3d