Would laser weapons make the world safer?

In this age of science fiction movies and electronic arcade games, we are deluged and bombarded by laser cannons and other similar exotic weapons. Is all this mere fancy, or is there a laser torpedo in our future?

The answer is that there well may be. Both the United States and the Soviet Union are actively pursuing the weapons potential of high-energy lasers and charged-particle beams, collectively known as directed energy transfer or ''exotic'' weapons systems. Success in these programs, which appear promising but are by no means certain, could radically alter the strategic balance for the 1990s and beyond.

What are these technologies, and how are they similar and different? Both directed energy transfer technologies operate on the principle of aiming an intense beam of energy at a target with the purpose of destroying the target, disabling it, or knocking it off course. Laser weapons operate by transferring an intense light beam at the target. Particle-beam weapons, on the other hand, utilize a beam of concentrated radiation subatomic particles, principally neutrons and gamma rays. These dissimilarities affect how and where directed energy weapons appear to work best.

Lasers are subject to the degrading atmospheric influences on any light source, such as diffusion and refraction. As a result, their most promising weapons applications appear to be in the vacuum of space, where atmospheric problems are minimized. Conversely, particle beams tend to degrade across space unless they can interact physically with the surrounding atmosphere to allow particle replenishment within the beam. In the vacuum of space, the beams tend to spread and become unfocused, thus rendering them less effective. Thus, the most promising uses for particle beams are within the atmosphere.

One can reasonably ask why the American and Soviet governments are pursuing these technologies, which is another way of questioning what their weapons utility is expected to be. The answer, in virtually all discussions on the subject, centers on a role in ballistic missile defense, providing a shield against a nuclear missile attack. Laser scenarios focus on orbiting laser battle stations in space which would attack rising missiles during their boost phase, when they are most vulnerable. Particle-beam prospects emphasize stationing the weapons near target areas as terminal defenses against incoming reentry vehicles. Some analysts even project a ''layered'' system where lasers destroy rising missiles and particle-beam defenders wait to pick off warheads that get through the laser screen.

Is all this too good (or too bad, depending on your perspective) to be true? Although these programs are promising, there remain several impediments to realizing laser and particle-beam weapons.

The first problem is the need for a tremendously powerful beam to produce sufficient power to carry out the defensive role. The propagation device and fuel requirements currently add up to a weapon system that weighs literally tons. Inserting the platform in space and servicing it are major obstacles, although the Space Shuttle has been suggested as a prominent candidate for the job.

Second, the requirements for ballistic missile defense are extremely exacting , necessitating highly sophisticated ground and satellite target acquisition and tracking systems. These ''eyes'' are inherently the most vulnerable elements in the system, the most difficult to defend, and hence the most likely to be attacked.

Third, the need to defend the defenders could prove stimulating to the arms race. It is not far-fetched to envision space cluttered with laser-armed satellites, dummy satellites, satellite killers, and satellites designed to destroy the killers.

Fourth is the matter of cost. No one is yet speculating on the price tag for a comprehensive directed energy defense system, but it is almost assuredly going to be very high.

Finally, one must ask what effects these weapons would have on the strategic arms race and efforts to control it. Arms race stimulation prospects are manifest, particularly in the heretofore proscribed militarization of space. At the same time, introduction of these weapons is at odds with several existing arms control agreements.

The most obvious victim is the Antiballistic Missile (ABM) Treaty of 1972. That document expressly forbids basing missile defense in space, and the treaty's language is quite inadequate to deal with this category of weapons. What, for instance, would constitute a laser launcher or interceptor (terms pivotal to the treaty)? Such weapons could be in violation of the limited Test Ban Teaty of 1963 and the Outer Space Treaty of 1967, both of which ban the basing of nuclear and other weapons of mass destruction in space. Finally, deployment could be viewed as abrogation of superpower arms control and disarmament obligations under the Nuclear Non-Proliferation Treaty.

Whether laser or particle-beam weapons will become part of future arsenals no one can answer with certainty. The prospects, however, are clearly there. The real concern is whether introducing these weapons would make the world a more or less dangerous place. It is a question well worth pondering before they become reality.