To The Editor:
The article "Optical Warfare: Technology emerges to see the enemy, and to blind him," in the March 1997 issue of Military & Aerospace Electronics was a creditable treatment of a very complex subject. However, I would like to correct some statements which were not totally accurate.
There is no international law which explicitly bans the military use of anti-personnel lasers. In fact, a 1988 opinion by the Judge Advocate General of the Army, with the concurrence of the offices of the Judge Advocate Generals of the Navy and the Air Force, concluded that the use of a laser as an antipersonnel weapon would not violate the law of war prohibition on superfluous injury or unnecessary suffering. This became and remains the position of the United States. A new international "law" on laser weapons, referred to as protocol IV under an existing treaty, has been proposed by a United Nations Review Conference. The United States supports Protocol IV and DOD has issued policy prohibiting the use of laser weapons as defined by this Protocol. The essence of Protocol IV is contained in the following four Articles:
Article I: It is prohibited to employ laser weapons specifically designed, as their sole combat function or as one of their combat functions, to cause permanent blindness to unenhanced vision, that is to the naked eye or to the eye with corrective eyesight devices. The High Contracting parties shall not transfer such weapons to any State or non- State entity.
Article II: In the employment of laser systems, the High Contracting Parties shall take all feasible precautions to avoid the incidence of permanent blindness to unenhanced vision. Such precautions shall include training of their armed forces and other practical measures.
Article III: Blinding as an incidental or collateral effect of the legitimate military employment of laser systems, including laser systems used against optical equipment, is not covered by this Protocol.
Article IV: For the purpose of this Protocol, "permanent blindness" means irreversible and uncorrectable loss of vision which is seriously disabling with no prospect of recovery. Serious disability is equivalent to visual acuity of less than 20/200 Snellen measured in both eyes.
It is a misperception that tactical laser systems must pose a significant danger to eyes. Short-pulse, visible-laser irradiation is the worst hazard for the eye, yet more than ten millijoules total interocular energy would be required to cause permanent blindness as defined by Protocol IV. The hazard to the eye decreases if the laser operates outside of the visible spectrum. Even at arms length from the eye, a typical laser designator operating at 1.06 microns has insufficient output energy to permanently blind. To my knowledge, there has not been a single military laser accident resulting in permanent blindness to both eyes. In fact, it would be a significant technical challenge to design a man-portable laser that had the capability to cause permanent blindness in a realistic battlefield scenario. On the other hand, to design a counter-sensor laser with acceptable ocular hazard is relatively straightforward. The laser designer has several parameters to work with in minimizing ocular hazard:
- knowing range to target, control output energy to achieve desired effect at a level below threshold of serious eye damage;
- selecting a wavelength to optimize effects on target but minimize hazard to eye;
- using continuous-wave or longest pulse possible; and
- maintaining tight beam on optical target to minimize overspill on nearby personnel.
It is a gross exaggeration to associate laser countermeasures with "mass blinding." The laser is a tool literally of surgical precision. It is capable of placing a beam smaller than 16 inches in diameter onto a target at a distance of one mile. It is certainly not a practical weapon of mass destruction. Just to scan a 5-by-40-degree sector of the battlefield with this "pencil-beam" of light would take over three hours at 100 pulses per second. The laser is a very discriminating optical countermeasure - ineffectual unless the threat optic is looking (aiming) directly at the soldier/laser system.
Using a laser to temporarily and safely disable a combatant is practical under certain circumstances. It is an oversimplification to claim the energy necessary for flashblinding is close to the energy threshold for serious eye damage. There are many variables that determine a laser`s effect on the eye. For example, to attempt flashblinding during the day with a short pulse, high rep rate, green laser , could cause permanent eye injury (though not necessarily "permanent blindness"). However, flashblinding at night can be accomplished using a continuous-wave green laser at power levels below even conservative laboratory standards for eye safety.
Laser countermeasures to threat optics and electro-optics represent a revolution in warfighting capability, and constitute an appropriate element of "information warfare." Several countries are developing such laser countermeasure systems. The United States can be an owner or a victim of this capability. Responsible development of lasers and of eye/sensor protectors will ensure that our soldiers have every possible advantage on tomorrow`s battlefield.
U.S. Army Communications-Electronics Command
Night Vision and Electronic Sensors Directorate
Fort Belvoir, Va.