Laser Lab Focuses on Protective Eyewear.

When the nuclear arms race was in full swing, the Laser Eye Protection Program at the U.S. Army Soldier Systems Center in Natick, Mass., measured thermal transfer through laboratory materials and clothing systems using a special laser and instrumental manikin.

Data was fed into a computer code that calculated skin-burn severity similar to what would happen during an atomic bomb explosion. Two manikins dressed in burned-out desert and woodland camouflage uniforms, on display at the center, are reminders of that era.

"We stopped that testing ... as the nuclear threat diminished," said Barry DeCristofano, a chemical engineer at the laser lab. "Now, we are working solely on eye protection.

Four kinds of lasers in the lab can produce all wavelengths necessary to test laser eye protection. A picosecond-pulse laser is used for probing optical properties of developmental materials, and a nanosecond-pulse laser is used for optical limiting measurements.

Besides lasers, the lab uses equipment to test other requirements. Ballistic evaluation of eye armor is obtained through an air gun that shoots fragments at speeds meeting military and civilian specifications. Eyewear is placed on a manikin head inside a steel container to catch fragments striking the glasses.

The lab's spectrophotometer measures how much light travels through material at each wavelength. "It's used to match dyes and to see if fielded eyewear still passes the specs," DeCristofano said.

Accelerated measurements are conducted on solar exposure and temperature extremes with a weatherometer and computer-controlled environmental chamber. Industry benefits from the facilities as well. Eyewear manufacturers have used the facilities in testing agreements to provide accelerated exposure and see if the products still meet all specifications.