Laser weapons that won't blind permanently

Used to stop vehicles. [Link]

Laser dazzlers — or “optical distraction devices,” as the military prefers to call them — have proven invaluable in Iraq as a way of warning drivers to stop at checkpoints. (A flash of bright light does tend to give people pause.) But as Danger Room reported, several U.S. troops have suffered serious eye injuries from laser “friendly fire” incidents. So the U.S. military’s Joint Nonlethal Weapons Directorate is developing a new type of laser which aims to be both safer and more effective than existing dazzlers, I report in New Scientist. Whether it will work is still an open question.

Rather than a continuous beam, the Laser Windshield Obscuration project works by firing a short laser pulse, which is absorbed by the vehicle windscreen. That produces a brilliant white ‘re-radiation’ flash (see photo, right), leading to cracking or hazing of the glass (photo, left).

Originally, the objective was to cause the maximum amount of the damage to the windscreen, making it impossible to see through. As the photograph shows, the laser is certainly capable of it. The concept is similar to the lens-destroying “laser crazer” project, proposed for knocking out cameras and other sensors. However, researchers found that the bright flash was enough to cause “optical incapacitation” or dazzling of the driver. Work is now concentrating on changing the output to produce a brilliant flash with minimum damage; ideally, the windscreen would not need to be repaired or replaced.

The laser flash should give a clear and unambiguous signal to stop. If the driver does not stop in spite of the warning, they may be assumed to be a suicide bomber and more lethal means will be used. (And a dazzled suicide bomber should be slightly less dangerous).

Existing laser dazzlers have the double problem of limited effectiveness in daylight and the potential to cause eye damage at short range. The JNLWD say that the Windshield Obscuration Laser will be equally effective in all lighting conditions. And, since the brilliant flash is generated at the windscreen, it should have the same effect at five meters or five hundred.