Laser Weapons

Laser attack

US naval intelligence officer Lt. Jack Daley and his Canadian pilot made a third pass over the Russian ship. April 4, 1997 was a bright, cloudless day over the Strait of Juan de Fuca, north of Seattle, Washington. Daley and the pilot were flying a helicopter and photographing a Russian cargo ship, the Kapitan Man, which was suspected of spying on US submarines. As Daley photographed the ship’s antenna array he saw a blinding flash. He turned his head and rubbed his eyes.

After returning from the mission, Lt. Daley and the pilot began to have headaches and visual problems. One of the photographs of the ship showed a laser light shining from the bridge of the Kapitan Man. Both men suffered permanent eye damage, and medical examination of the men was consistent with laser-induced retinal damage.

Lasers are widely used for modern warfighting

The energy of the laser light is confined to a very narrow beam. There are many types of lasers which differ in wavelength, energy, and other characteristics. Lasers have many uses on the modern battlefield. High energy lasers (HEL) can potentially damage or destroy structural targets such as ships, aircraft, and missiles. However, HELs are not thought to be widely available or practical at present, are not primarily intended for use against personnel, and will not be discussed further in this article. Of course, much of the information on military lasers is classified, so our understanding of laser weapons must be considered incomplete.

Low energy lasers (LEL) are widely used in the armed forces of all countries to guide and control conventional weapons. They can be small, portable, hand-held, and battery operated. LELs can also be directly used as weapons. LELs can destroy or blind many of the battlefield sensors used in fire control systems.

However, the most important use of LELs is against the human eye, the organ most sensitive to laser light. Nonweapon LELs in range finders and targeting system are dangerous to the eye at a range of several miles. The hazardous range may be tens of miles if magnifying optics such as binoculars are in use. Magnifying optics placed in front of the eye increase the susceptibility of the eye to laser-induced damage.

Retinal photograph: retinal hole and preretinal hemorrhage after exposure to a Nd:YAG laser. Photo: US Army.	Retinal photograph made after multiple acute retinal burns from a Nd:YAG laser rangefinder. Photo: US Army.

When used against the eye, LELs can cause temporary visual impairment such as flash blindness, discomfort, or disabling glare. Such lasers can cause permanent visual impairment by destroying part of the retina, the inner coating of the back of the eyes, or by causing bleeding in the eye.

Protection – optical filters

One method of protecting the eyes from a laser is the use of glass or plastic optical filters which block the laser beam. Optical filters can be defeated by using a more powerful laser or a laser with a light frequency not blocked by the filter.

Some lasers can be tuned to change the frequency of the emitted laser light (frequency-agile laser). A filter which would protect against all of the light frequencies which can be emitted by frequency-agile lasers would make it impossible for the soldier to see well enough to fight.

Examples of US Army laser eye protection. Photo: US Army.

Protection - indirect viewing

Another means of protection is indirect viewing: avoiding the use of one’s own eyes to look directly at the battlefield. Instead, one looks through a sensor, such as a low light television camera which will not transmit laser light to the eye. Of course, the sensor will be destroyed or inactivated after it is hit by a laser, but the sensor can then be replaced or repaired, and vision will be preserved.

Protection - the black eye patch

Another seemingly odd method of protection is to wear a black eye patch on one eye. After a laser attack at least one eye is preserved. However, after removal of the eye patch, the remaining eye will be vulnerable, but protective or evasive measures can then be taken.

The future

Laser weapons have not been widely used so far. In addition to the Kapitan Man incident described above, the British downed several Argentine planes during the Falklands War by using anti-eye lasers. Recently, pilots of a number of commercial airliners have been targeted with lasers during landing and takeoff. Despite the existence of international agreements which attempt to restrict the use of laser weapons, more widespread military use of these devices seems inevitable.