Instant Holographic Images Make 3-D Movies a Possibility
Instantaneous holograms that could pave the way to three-dimensional motion pictures have moved a step closer to reality, scientists say.
Researchers at Riso National Laboratory in Denmark say they can create a hologram in only five billionths of a second (instead of several minutes) through a technique that requires no chemical processing and thus is immediately ready for viewing.
Instead of photographic film used in other holographic processes, the researchers use a thin polymer film that responds instantaneously to a pulsed laser beam. For reasons that are not yet understood, the laser removes some of the mass on the film and leaves a “grating” that can be used to project a three-dimensional image of the target.
And because the laser pulses 20 times a second, “we can make 3-D movies with it at a video rate,” said P.S. Ramanujam, lead scientist on the project and an internationally recognized pioneer in the field.
In a telephone interview, Ramanujam said he believes the technology will lead to realistic movies for such scientific purposes as the study of cell growth and changes in biological organisms. But he said it will be awhile--maybe 15 to 20 years--before the holographic version of “Gone With the Wind” comes to your neighborhood theater.
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Holograms have been around for several decades, but they have been slow to reach their potential because the tools and the techniques needed to further the science have been hard to come by. But that is changing, partly because of the availability of relatively low-cost and compact lasers.
Glenn Sincerbox of IBM, one of the leaders of a major effort to develop holographic technology for data storage systems, has noted that the emerging field has had to borrow technology from other areas, most notably entertainment and consumer electronics. Thus it had to wait for those fields to develop further in order to have the tools to reach its potential of revolutionizing everything from graphic images to hard disks.
In the area of visual images--those astonishing three-dimensional images most of us have seen in museums--it normally takes more than a minute to produce a single image on photographic film. “And then you have to take the film out and develop it, and then wait for it to dry before you can project the image,” Ramanujam said. “These polymers we are working on don’t need any of this. The image is instantaneous, and you can take one after the other.”
Ramanujam expressed some surprise over his own success in a report on the research in the May 24 issue of the Proceedings of the National Academy of Sciences.
“It is remarkable that such a strong surface relief [the grating that contains the image] is formed already after a five nanosecond exposure,” he wrote. “The cause for the surface relief is still not understood.”
He said, however, that the short exposure time using polymer films--which can be erased by heating and instantly reused--is “paving the way for a cheap, mass replication” of holograms.
The holograms can be viewed by shining another laser through them and projecting the image onto a sheet of glass. “It’s like looking through a window into 3-D space,” he said.
And because his system works so quickly, it could eventually lend itself to real-time three-dimensional monitoring of such things as surgical procedures, he said.
Holography dates to 1948, when British scientist Dennis Gabor figured out the principles, for which he won the Nobel Prize. But scientists had to wait until the 1960s and the availability of lasers to begin serious research.
Holograms are created when a laser beam reflects from an object onto a photographic film in much the same way as optical photography. Then a second laser beam, called the reference beam, reads the image off the film and projects it onto a glass screen.
The stunning visual effects were immediately obvious, but some scientists recognized that what they had here was a system capable of storing huge amounts of data in a very small area.
That led to an ongoing study, funded partly by a $32-million grant from the Defense Advanced Research Project Agency, involving 12 institutions with IBM and Stanford University providing the principal investigators. The five-year project began in November 1995.
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The Holographic Data Storage System, as the program is called, is aimed at developing systems that will contain more than 12 times the information of today’s largest magnetic hard-disk drives and work at speeds 10 times faster than is possible today.
Holographic systems will store data as pages, each containing more than a million data bits. And because the lasers will be able to read information from the entire disk, not just on the surface, it should be possible to store thousands of pages on a disk about the size of a small coin.
Data storage, not the creation of pretty pictures, is the goal of the project, but such a system could also store movies. A disk of 1 cubic centimeter could store 12 gigabytes, so “a movie on a sugar cube is certainly within the realm of possibility,” according to IBM’s Sincerbox.
What the viewer would see would be a digitized version of a regular movie, not a three-dimensional holographic movie. There are other problems that must be overcome before holographic systems can replace traditional movie cameras, not the least of which is safety.
“The big thing about holography as opposed to regular photography is you need a laser to bounce off the object,” said Greg Steckman, a Caltech graduate student who is involved in holographic research. An actor looking directly into the “camera” could suffer eye damage from the laser, Steckman said.
Ramanujam thinks that’s a problem that will be overcome in the next decade or so. Less powerful lasers, for example, and better optics for projection of the image, could reduce that.
And if all else fails, he said, the actors could wear protective glasses. How does that sound, Scarlett?
Lee Dye can be reached at leedye@compuserve.com.
