UF Develops Better Vision for Smart Weapons

Paul Holloway, a distinguished professor of materials science and engineering, and several colleagues at the University of Florida have received more than $400,000 from the Defense Advanced Research Projects Agency (DARPA) for the first phase of “bio-optics synthetic systems research” to adapt photon sieves, a manmade version of the insect eye. “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.

Instead of the refractive optics currently used, the engineers and physicists rely on diffractive optics, which use interference effects to redirect light in different directions rather than bending it.

Their vision for the technology merges the developments of 19th-century French physicist Augustin Fresnel with a modern appreciation of how insect eyes work. He 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 researchers have modified the zone plate, replacing the transparent rings with a series of precisely spaced holes that sharpen the focus quality of the beam. Similar devices developed before are typically used for X-rays or other electromagnetic radiation outside the visible light spectrum.

“Although the holes help sharpen the focus of the light, they also significantly reduce the amount of light that gets through the metal plate,” says Art Hebard, a UF physicist and member of the project team.

When light strikes a metal surface, such as silver, it generates electrical charge oscillations, called surface plasmons. Hebard said that the UF team has made progress in reconverting these plasmons into light by altering the surface characteristics of the metal.

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.

Potential applications include smart weapons and robots designed to operate autonomously, and may replace refractive lenses in cameras.