Army lab explores new dimension in data storage

Army researchers in July expect a major breakthrough in 3-D holographic

technology that eventually could be used for storing vast amounts of visual

data, potentially revolutionizing applications for command and control,

simulation, security and Hollywood movie-making.

Researchers at the Army Research Laboratory in Adelphi, Md., will conduct

a laboratory test next month to see if they can use laser beams to "fix"

multiple 3-D holographic images of an object to a tiny crystal.

The technology differs from commercially available 2-D holographic technology

in that it uses images of "real world" objects rather than relying on time-

consuming and costly computer-generated "fantasy" images, said Gary Wood,

optics branch chief at the service research lab. Ironically, however, this

technology might one day be applied for the ultimate in fantasy generation:

movie production.

"If we succeed, it will be a major breakthrough for us. We will be over

the hump and will breathe a huge sigh of relief," Wood said. "If we fail,

I think there will be very limited applications for this technology."

The almost certain applications include storage of large amounts of

data and creating 3-D holographic maps or charts for electronic manuals.

The technology might also be used for biometrics, in which a facial

scan of someone trying to enter a secured building or network would be compared

with a stored holographic image of his or her face to ensure proper identity.

And holographic images may someday be used to orient soldiers to the location

of friendly or enemy forces on the battlefield.

First, however, the service must prove the feasibility of fixing multiplexed

images on a crystal.

An image is considered "fixed" when it does not disappear. Currently,

images disappear within minutes or hours after they are "read," and even

if not read, they disappear within a period of days or months.

The researchers will begin by creating one image, probably one die from

a set of gaming dice, then they will rotate the crystal and fix another

image of the same object on a different part of the same crystal, a process

known as multiplexing.

The July test might include as many as six images of the same object. The

closer the images can be fixed on the crystal, the greater the potential

for storing vast numbers of images.

"It's like drawing lines on a piece of paper. If you can get the lines

very close together, it only takes a great deal of effort to fill up the

entire sheet," said Richard Anderson, a senior science adviser with the

National Science Foundation who participates in the effort.

The crystal being used in the test — a tiny slab of crystal of strontium

barium niobate with a dash of cerium — measures about 8 mm wide, 8 mm high

and 2 mm thick, which is about the size of a flat thumbtack.

No one knows yet how many images can be stored on one crystal, but researchers

hope the answer some day proves to be hundreds of thousands or millions.

Once fixed on the crystal, an image is viewed or "read out" by using

another laser coming from the opposite direction of the first two. In time,

Wood said, the military should be able to use inexpensive commercial lasers,

such as the widely available laser pointers used by lecturers, to read a

holographic image.

Commercially, the technology could be used for displaying images of real

objects — a business owner showing his wares on the sidewalk while the merchandise

remains safely inside, for example.

Applications within the realm of possibility but offering much tougher technological

challenges include realistic 3-D simulation, military deception such as

projecting an image of a tank where no tank exists, or making movies, for

military propaganda purposes or for entertainment.

The Army program has been in place for about five years and is funded at

about $300,000 annually. Funds come from the Army Research Laboratory and

from the Army's Night Vision and Electronic Sensors Directorate, Fort Belvoir,

Va.

Besides fixing a multiplexed image, the laboratory's short-term goals include

finding ways to store the image for long periods of time. Long-term challenges

include improving the quality of images by gaining greater definition, improving

color and making the images scalable in size, an advance that will be necessary

for simulation or movie-making.