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Plasmons harnessed for holograms

Science / AAAS

Reconstruction of a red apple with a green leaf in three dimensions using surface plasmon holograms

A new technique to produce full-color holograms that stay the same when viewed from any angle could usher in a day when we plop down on the couch and watch 3-D TV without optical illusions.

Current methods for creating 3-D images are based on producing a separate image for the left and right eyes. "Inside the brain we reconstruct the 3-D, so it is sort of an illusion," optical physicist Satoshi Kawata of Osaka University of Japan explains in a video made available to reporters.

He and colleagues instead made 3-D color holograms that can be viewed with the naked eye and don't change color no matter what angle they are viewed from. They did this by harnessing so-called surface plasmons, which Kawata describes as "the collective electron oscillations traveling on a very thin metal film."

The researchers coat the metal film onto a light sensitive material called photoresist that contains a hologram made with red, green, and blue lasers. The photoresist hologram rests on a thin glass plate. A corrugated layer of silver is laid on top of the photoresist to help guide the holograph's light waves.

The surface plasmons in the metal film are excited using white light. The angle of the incoming light determines which plasmons are excited and diffracted by the hologram, reconstructing the light waves reaching the viewers eyes so that the 3-D image appears.

"No one has thought to use plasmons for display applications, so it was fun for me," Kawata told Wired Science. "I just wanted to demonstrate that this could be done. But I hope people would be interested in thinking seriously to use this technology for larger-scale 3-D display."

Before it goes big time, however, the technology needs to be scaled up — the current images are a few centimeters across. In addition, the images are static, not moving picture such as film or TV.

A paper describing the research appears in the April 8 issue of Science.

Update for 6:20 p.m. ET: Check out videos of a hologram demonstration and an interview with Kawata, available via EurekAlert.

Tip o' the Log to Lisa Grossman at Wired Science
