and instead used their lasers as dazzlers against the enemy helicopter pilots. This ultimately proved ineffective in crashing any attack helicopters. On 18 May 2006, the U.S. military announced it was using laser dazzlers mounted on M4 rifles in troops in Iraq as a non-lethal way to stop drivers who fail to stop at checkpoints manned by American soldiers. Other militaries have taken up use of them as well. Countermeasures One defense against laser dazzlers are narrowband optical filters tuned to the frequency of the laser. To counter such defense, dazzlers can employ emitters using more than one wavelength, or tunable lasers with wider range of output. Another defense is photochromic materials able to become opaque under high light energy densities. Nonlinear optics techniques are being investigated: e.g. vanadium-doped zinc telluride (V:ZnTe) can be used to form electro-optic power limiters able to selectively block the intense dazzler beam without affecting weaker light from an observed scene. Legislation Weapons designed to cause permanent blindness are banned by the 1995 United Nations Protocol on Blinding Laser Weapons. Dazzlers intended to cause temporary blindness or disorientation fall outside this protocol. Manufacturers and models LE Systems, under the sponsorship of DARPA, developed a dazzler based on a DPSS laser, with green light output at 532 nm, essentially a higher-intensity version of a green laser pointer. 532 nm light interacts with human eyes well in both daylight and reduced light conditions. B.E. Meyers & Co. produces several dazzlers including the GLARE LA-9/P, GLARE MOUT, GLARE RECOIL LA-22/U, and GLARE HELIOS. The GLARE RECOIL and GLARE HELIOS dazzlers utilize built-in safety mechanisms to prevent eye damage by pairing the dazzler with a rangefinder; the dazzler will self-modulate power output with respect to range to target so the closer the target, the lower the output and the farther the target, the greater the output. As a result the maximum safe laser intensity output is utilized without risking ocular damage. The older GLARE LA-9/P variant includes a rangefinder and an automatic cutoff failsafe but does not have automated modulation capability. Effective range for the various GLARE dazzlers ranges from 400m to 20+km. Despite having the greatest effective range of 5-25+km, the GLARE HELIOS is classified as an FDA Laser safety#Class 1M eye-safe laser. The Dazer Laser Guardian, Dazer Laser Stealth, and "Dazer Laser Defender" by Laser Energetics, Inc. are different types of optical distraction laser systems which can