Facing down friendly fire

In the spring of 2002, a U.S. fighter jet flying over Afghanistan mistakenly dropped a laser-guided 500-pound bomb on a group of Canadian soldiers, killing four. A couple of years later, also in Afghanistan, Pat Tillman, the professional football player turned soldier, was shot and killed by fellow U.S. troops in a firefight. 

These sorts of tragic errors are an all-too-regular occurrence in war. But Boston Micromachines Corporation (BMC), a start-up company incubated at BU’s Photonics Center, is developing a technology that could help reduce the number of such “friendly-fire” incidents and create a new, highly secure way to communicate on the battlefield. The U.S. military recently awarded BMC a $100,000 Small Business Technology Transfer Research grant to fund the project.

Based in Watertown, Mass., BMC was founded in 1999 by Thomas Bifano, a College of Engineering professor of manufacturing engineering and aerospace and mechanical engineering and director of the Photonics Center. The company manufactures tiny microelectromechanical (MEMS) mirrors that bend with the force of a small voltage and are used to improve the resolution of optical instruments such as microscopes, retinal imaging, telescopes, and light-based communication systems.

BMC’s idea for combating friendly fire is known as a Secure Communicating Optical Ultra-small Transponder (SCOUT). It starts with what’s known as a retroreflector, or “corner cube,” a three-sided mirror that reflects a beam of light shining from any direction or angle directly back to its source. Common uses of corner cubes range from highway signs to reflectors on running shoes.

In the SCOUT system, a corner cube about the size of a matchbox would be mounted on a soldier’s helmet or on a vehicle such as a tank, with a tiny MEMS mirror on one of the cube’s sides. A current would bend the MEMS mirror rapidly back and forth, so that when the soldier or vehicle was “painted” by a targeting laser, the reflected beam would be interrupted and blink in the view of the soldier, plane, or tank doing the targeting. 

While the simplest form of communication via blinking light is Morse code, Paul Bierden (ENG’92,’94), BMC’s president and CEO, says that because these mirrors move at a speed of 10,000 times a second, “you can send computer data, ones and zeros, via the reflected beam.” Coupled with a sensor on the gun or vehicle of the targeting soldier, the SCOUT system could thereby not only pass on the soldier’s identity, but also plenty of other critical battlefield information.

“It would be a very secure transmission,” explains Bierden, “because the data only goes along the path of the laser.” He expects to have a prototype ready for field-testing by early 2007. He also points out some potential nonmilitary uses for SCOUT, such as tracking the spread of a forest fire. Imagine dropping hundreds of SCOUT transponders equipped with sensors to detect heat, smoke, and wind speed over a large area of forest near a spreading fire. A plane could then shine a laser over the area and the devices would send back their data, giving firefighters real-time information on the strength and movement of the fire.

“It could be used anywhere you’d want to have remote sensing,” Bierden says.