WASHINGTON - September 30, 2009 - The Pentagon's efforts to develop a beam weapon that can deter an adversary by causing a burning sensation on his or her skin has taken a step forward with the development of a small, potentially hand-held version. The weapon, which is claimed to cause no permanent harm, could also end up being used by police to control civilians.

The idea of the weapon is to "create a heating sensation that repels individual adversaries", according to the Joint Non-Lethal Weapons Directorate (JNLWD) in Quantico, Virginia, which develops less-lethal weapons for the U.S. military and coastguard.

Tests with a rifle-mounted infrared laser, carried out at a U.S. Air Force lab near Dayton, Ohio, have determined a combination of laser pulse power and wavelength that causes an alarming, hot sensation on the skin, but which stops short of causing a burn, says JNLWD project engineer Wesley Burgei.

"We have established the minimum irradiance to cause a sensation and have characterized where thermal injury begins," he says. "But the exact operating irradiance which balances a useful military effect with a conservative margin of safety has not been nailed down yet."