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Blinding laser weapons a growing concern WHILE lasers have become an essential tool for ophthalmologists, in an ironic twist, the same technology has been used to develop weapons that can cause devastating blindness on the battlefront, according to John Marshall MD who spoke at the annual meeting of the Canadian Ophthalmological Society. The desire to use lasers, or other sorts of "beam" weapons for military purposes was first noted in science fiction. Back in the 1930s, the Buck Rogers character had a ray gun, and in HG Wells' 1898 classic "War of the Worlds", Martians were planning to annihilate Earth with an impressive beam weapon, he noted. It wasn't until 1960 that beam weapons became a real possibility, and research started in that direction. Laser weapons are desirable from the military's point of view because of their impressive combination of power and range. There are currently five classes of battlefield laser systems with various anti-material and anti-personnel applications. These now include rangefinders and target designators, antimaterial systems, antisensor systems, antipersonnel systems, and non-laser optical systems. Laser systems come in various sizes and are found mounted on ships, in aircraft, on satellites and on the ground.Laser rangefinders and target designators are commonly used in tanks to measure distances and mark targets. Anti-material systems are high energy systems used for destroying aircraft and satellites. Anti-sensor systems destroy the enemy's optical sensors. The beams emitted by all of these instruments are potentially blinding. Perhaps most worrying are the antipersonnel systems developed to be carried by infantry that are designed to blind enemy troops. There are also non-laser optical systems that have been deployed, such as the "Dragon", used by the British police. This is a high intensity light source that uses bright flashes and may be used for crowd control. High intensity lights are also used on police guns to disorient suspects."During the Falklands conflict the UK was the first to deploy a dazzle laser system. The Navy claims it just dazzles them. If it dazzles you at five miles, it certainly has the potential to blind you as you get closer," Dr. Marshall said. Dazzle is the sort of vision distortion experienced after seeing oncoming car headlights at night. Dazzle and after-images distort vision for several seconds to a minute or so, enough to slow an enemy down, or affect their aim. Flash blindness occurs when there is a bright flash at night, and causes temporary vision loss, while stronger light can reach the retina and cause permanent damage. "If you are unfortunate enough to look at one of these systems with binoculars, you could get a retinal hazard at up to 80 miles from the system. You could imagine the devastation to an individual suddenly confronted with blindness for no reason," he said. The eye represents a tiny fraction of the surface area of the body, but is vulnerable to numerous injuries because of the sensitivities of the visual system, and the fact that you keep the eye open and directed at areas of interest. The eye is vulnerable to injury because it allows optical radiation to penetrate deep within it. Once the fovea is damaged or destroyed, blindness or severe vision loss will follow, he stressed. From an historical perspective, there have always been eye injuries in battle, but usually from dust and debris that get blown from an explosive source, or blunt trauma. During the Crimean and the Napoleonic campaigns, and the Prussian war, approximately one percent of military injuries were eye injuries. During World War I and World War II, eye injuries climbed to about two percent of total numbers of military injuries. In recent years, however, eye injuries have increased significantly. "Desert Storm was the first time optical systems were deployed in large numbers and the rate of eye injuries went up to 13%. If you look at predictions from the Swedish high command, with a mass deployment of anti-personnel systems, 30% of injuries will be blindness due to laser weapons," Dr. Marshall said. The degree of damage to the eye mostly depends on the distance from the weapon. For example, if a person is eight miles away and a laser system is deployed, transient dazzle will result. If the viewer is a bit closer he will get an afterimage. Flash blindness and disorientation occur in close proximity to the weapon, particularly at night. A person who is within two miles of certain systems may get a burn, but with a high-energy system a retinal haemorrhage is possible. As a direct result of the rise of laser weapons, eye protection has become part of the armamentarium of field soldiers. However, their effectiveness varies and is generally fairly crude."It depends on how much you cost to train. Pilots cost millions, so they have pretty good protection, infantry are relatively inexpensive so their protection is nowhere near as good," Dr Marshall said. One of the recommendations by the British air force is to wear an eye patch, to save one eye if the other is damaged. Ducking is advised by the US air force. Goggles help only to a point because they can't protect against changing wavelengths and pulse duration. On a sarcastic note, Dr. Marshall added, "You have to wear the boxes the goggles come in and cross your eyes." Attempts have been made to stop the use of these weapons, and Dr. Marshall has been quite active in this direction. Starting in 1989, he participated in series of expert meetings with the International Red Cross and United Nations to draw attention to the issue of blinding weapons. The result is that there is now a Geneva Convention banning the use and distribution of anti-personnel laser weapons. But there are gaps in the ban. "It only governed the mass blinding initiatives- blinding of individual soldiers was OK. Systems can still be developed; they just aren't supposed to be used in the field. A bigger gap in the ban is that it doesn't cover non-war operations. In peacekeeping operations, you could use lasers to blind people," he said.However, it turns out lasers and laser weapons are popping up in places other than the battlefield as a vision risk. According to the US based Human Rights Watch (HRW), lasers originally developed for dazzling and blinding missions by militaries are now being offered to law enforcement agencies. An example on the North American market is from the US based LE Technologies, which offers a flashlight-sized device called the Laser Dazzler that disrupts vision. It is being sold to police forces and may be available to other security agencies. Regular laser pointers, already associated with vision problems, have now been identified as a problem for people at a distance. In a newsletter published in April of this year by the US Federal Bureau of Investigation (FBI), laser pointers used by people on the ground are being blamed for vision disruptions of airplane and helicopter pilots. According to the newsletter, handheld lasers, laser pointers and other bright lights are sometimes shone at low-flying aircraft at night time. Beams can reach 1,500 feet, yet helicopters often fly between 500 and 1,000 feet. Over 200 incidents of pilots complaining of laser lights being shone at them have been reported in the US since 1997. "The majority of laser pointer illuminations cause reactions of startling, after imaging, or flash blinding. However, if a laser is powerful enough or sustained on the eye long enough, eye damage can occur," the newsletter states. John Marshall |
