Helicopter-mounted lasers that can dazzle and defend against heat-seeking missiles are now under development, researchers reveal.
The military often relies heavily on helicopters in areas such as Afghanistan, where rough terrain can make it hard for airplanes to land and for troops and vehicles to travel on the ground. However, as the Soviet Union discovered in the 1980s during their war there, copters are easy targets for enemies with shoulder-launched missiles, "and now, unfortunately, the U.S. is on the other side with Afghanistan," says Mohammed Islam, a laser and fiber-optics scientist at the University of Michigan at Ann Arbor. "To consider the magnitude of the problem, there are about 3,000 helicopters in the U.S. armed forces."
Islam and his colleagues are now devising a way to protect helicopters from such attacks using off-the-shelf lasers. The missiles normally home in on aircraft by targeting the infrared radiation given off by the latters' engines; the lasers jam the sensors on these heat-seekers from up to three kilometers away by shining infrared beams at them, buying the helicopters enough time to maneuver away.
Most lasers emit just one wavelength, or color. To deflect missiles, the researchers are employing what are known as mid-infrared supercontinuum lasers, or MISCLs, that give off a much broader range of wavelengths—from the visible (800 nanometers) to the mid-infrared (4.5-microns). (A nanometer is one billionth of a meter; A micron is one millionth of a meter.) Because these lasers emit such a broad spectrum, they inundate the opposing sensors with all the infrared wavelengths the missile might look for; any attempts by opponents to block these dazzling rays by painting reflective or absorptive coatings on the missile beforehand would also blind its sensors to the same wavelengths from the copter engine.
Less than 10 percent of the light from the laser is a visible dim red; the rest falls within the infrared range. Altogether, the latest version of the device packs about 10 watts of power concentrated into a searing beam. "People who put their hands in its beam quickly move the hand away," Islam says.
The new laser uses technology from the telecommunications industry, which relies on multiple wavelength lasers to create many highway lanes for data signals to travel within fiber optics. "It's a clever way of using lasers that you can essentially buy off the shelf," said laser scientist Anthony Johnson at the University of Maryland, Baltimore County, who did not take part in this research.
Laser-based defenses have already found their way onto some aircraft, but the laser optics in these systems can currently have up to 84 moving pieces—precision components that can easily get knocked out of alignment by the rumbling on a copter. "Our lasers have no moving parts, which means they can withstand a helicopter's shake, rattle and roll," Islam explains. The hope is to replace the lasers in existing aircraft antimissile defense systems that detect and train beams on their targets. The system is being commercialized through Islam's company, Omni Sciences.
In terms of weight current laser-based aircraft antimissile defense systems weigh on the order of 16 kilograms, whereas this new laser is more in the 4.5-kilogram range. When it comes to cost, "for our next prototypes, we'll probably have the parts cost $25,000 to $30,000, and with the packaging and testing we could probably sell it profitably for $100,000," Islam says. In comparison, laser-based aircraft defense systems today cost roughly $1 million, he explains.
The researchers developed a first-generation, DVD player–size prototype for the U.S. Army in 2008, and are working on a second-generation, laptop-size device for 2011 that is four times more powerful. Although Islam says that helicopters probably face the greatest need for such laser-based protection against missiles, "it's potentially applicable to all aircraft," he suggests.
Islam says the laser could also aid in border surveillance—the chemicals involved in explosives often emit specific light wavelengths when hit by infrared rays, which means these lasers might be able to detect guns and bombs from afar. "You could put them maybe a kilometer or two apart at borders to monitor someone passing, instead of having a border patrol agent every 60 feet," he says.