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Nature
Offers Better Visions System
for Smart Weapons
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pdf
The
next generation of smart weapons may “see” targets
with a manmade version of that wonder of the natural world,
the insect eye.
Inspired
by the panoramic and precise vision of flies and other insects,
researchers at several universities and institutions are working
on biologically inspired “eyes” for smart weapons
and other self-guided machines. At the University of Florida,
the focus of the “bio-optics synthetic systems research,”
sponsored by the federal Defense Advanced Research Projects
Agency, or DARPA, is on adapting mechanisms called “photon
sieves” for visual purposes.
“We think we can use this concept to make smart weapons
smarter,” said Paul Holloway, a distinguished professor
of materials science and engineering and the project’s
lead researcher.
Holloway and several colleagues at UF have received more than
$400,000 for the first phase of the research from DARPA. The
project is only about a year old, but the researchers have
applied for several patents for their findings and plan scientific
publication of their work.
Holloway said today’s smart weapons rely on systems
that use refractive optics, or lenses that bend light, to
produce a focused view of the target. The resulting image
is like what is seen through a telescope — the view
of the target is good but the surroundings are completely
lost. This limits a weapon’s accuracy on moving targets,
as well as its ability to overcome flares or other counter
measures designed to confuse the weapon.
Refractive systems also are relatively heavy because they
use mechanical systems to move the lens and keep the target
in view. The added weight requires more propellant and increased
size, which boosts the cost, Holloway said.
The alternative approach of Holloway’s team of engineers
and physicists relies on diffractive optics, which uses interference
effects to redirect light in different directions rather than
bending it. Their vision for the technology merges the developments
of a 19th-century French physicist named Augustin Fresnel
with a modern appreciation of how insect eyes work.
Fresnel invented the Fresnel zone plate, also known as the
Fresnel lens, which uses concentric circles of transparent
and opaque material to diffract light into a single, marginally
focused beam. The Fresnel lens became the standard on lighthouses
for many years. Holloway and his colleagues have modified
the zone plate, replacing the transparent rings with a series
of precisely spaced holes that sharpen the focus quality of
the beam. Although similar devices, called photon sieves,
had been developed before, they are typically used for X-rays
or other electromagnetic radiation outside the visible light
spectrum.
The UF team is the first to develop photon sieves for visible
and longer-wavelength light, including infrared light, Holloway
said. The latter can have important implications for weaponized
vision systems, which sometimes use infrared light.
The team has made and tested small prototypes of the lenses.
Once perfected, the next step could be to put many such lenses
together — some designed for high resolution, others
for lower resolution — onto a surface to produce a multiple-eye
effect, Holloway said. The result would be a lightweight panoramic
vision device with no moving parts, he said.
Leonard J. Buckley, a program manager in materials chemistry
at DARPA’s Defense Science Office, said the technology
is promising.
“This technology has the potential to change the way
we think about optics and specifically about optical lenses,”
he said. “Inspiration from nature has enabled the pursuit
of new materials approaches to optical components, which will
allow more life-like qualities in the system.”
Smart weapons aren’t the only potential application.
Robots designed to operate autonomously, such as those used
to transport nuclear materials, fight oil well fires or do
other tasks too dangerous for people, also could benefit from
improved vision systems, he said. Eventually, such lenses
may even replace refractive lenses in consumer products, such
as cameras, making them lighter and potentially reducing their
costs.
Other researchers working on the UF project include David
Tanner, a UF distinguished professor of physics; Mark Davidson,
a UF research scientist; and Gary McGuire, Olga Shenderova
and Alex Shenderov, researchers at the International Technology
Center in North Carolina’s Research Triangle Park.
Paul
Holloway, pholl@mse.ufl.edu
by Aaron Hoover
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