Directed Energy Weapons

Will the United States develop laser and beam weaponry for a strong nuclear defense to replace the policy of mutually assured destruction. Has the Soviet Union violated treaties by using “yellow rain” in Afghanistan and Indochina? What future lies in store for the clean neutron bomb? What kinds of super missiles are being tested for the future? What new biological and chemical weapons has the United States been cooking up?

The development of lasers has been an exciting chapter in the history of science and engineering. It has produced a new device with potential for applications in an extraordinary variety of fields. Einstein developed the concept of stimulated emission on theoretical grounds. Stimulated emission is the phenomenon that is utilized in lasers. Stimulated emission produces amplification of light so that buildup of high-intensity light in the laser can occur. Einstein described the fundamental nature of the stimulated emission process theoretically.

It seems inevitable that the battlefield laser threat will markedly increase in the coming years. This will be because of not only the development and implementation of laser weapons but also the increasing number of other helpful laser-powered devices such as range finders and target designators. Therefore, it will be necessary for armies to protect their sensors and personnel by introducing passive as well as active countermeasures for laser technology. The primary laser threat will come from laser weapons, although conventional weapons guided to their targets by lasers will also constitute an indirect laser threat, as will be demonstrated later in this chapter.

Laser technology is only 30 years old, but it is much diversified. There are already varieties of military applications, although there are many limitations restricting the use of lasers. Today, the armed forces in most countries routinely use a wide range of laser devices such as laser range finders and designators. In some countries, work is proceeding on more imaginative laser weapon concepts that will eventually fulfill realistic, yet very precise, military requirements. The design of a specific laser weapon is heavily influenced by the characteristics of the intended target. If the desired effect of the weapon is to neutralize aircraft, helicopters, or missiles by burning holes through them or tanks by putting many miniature cracks (crazing) in the glass vision blocks to make them appear to be frosted, a very high-energy laser has to be used with a power output on the order of several megawatts (MW). Such a laser would be a true anti-material weapon. However, if the target is a sensitive electro-optical system or some other type of sensor system, which has to be jammed or destroyed by a laser operating in a countermeasure mode, the choice will be a low-energy laser operating within the frequency bandwidth of the target sensor. This use of a laser can also be considered anti-material. If the target is a soldier, there is one part of his body that is extremely sensitive to laser radiation—his eyes. It is sufficient to use a low-energy laser operating in the visible or near-infrared (near-IR) part of the spectrum to damage the soldier’s eyes and, in effect, cause blindness. If the laser is to cause burn injuries to the soldier’s skin or to set fire to his uniform, a high-energy laser is required. In either case, if the purpose of the laser is to blind or burn the soldier, it will obviously be antipersonnel.

This chapter will discuss directed energy concepts for strategic defense. We will talk about defensive weapons as a countermeasure against any measure that is applied in terms of a lethal weapon against friendly targets. Directed energy concepts can play unique roles in strategic defense because of their reaction time, speed of light engagement, and large geographic converge. This chapter discusses the main directed energy concepts, engagements in which they could have significant advantage, and their expected performance in them. It covers both boost-phase engagements and midcourse applications and contrasts these results with those of earlier analyses (Fig. 5.1).

In this section, we talk about beam weapons and their applications as directed energy weapons. The origin of laser technology dated back to a prediction made in 1916 by Albert Einstein where he suggested that an atom or molecule could be stimulated to emit light of a particular wavelength when light of that wavelength reached it, a phenomenon called stimulated emission. It had already been recognized that atoms and molecules emit and absorb light spontaneously, without outside intervention. In 1928, R. Ladenburg showed that Einstein’s prediction was right. At that time, stimulated emission seemed to be a very rare occurrence that was inevitably overwhelmed by spontaneous emission. It would be many years before physicist learned how to create the right conditions to make practical use of stimulated emission in lasers, the physics of which we know today. The 1970s saw a series of breakthroughs that rekindled military interest in high-energy laser weaponry. These developments were centered in two areas, carbon dioxide and chemical lasers, the technology of which are known today. The CO₂ laser’s potential for high-power output was recognized soon after it was first demonstrated by Patel although technology of gas dynamic laser was invented in 1967. Similar work was reported at about the same time by a Russian group which may have stimulated from American research works [1].

The word laser is an acronym for light amplification by stimulated emission of radiation, although common usage today is to use the word as a noun—laser—rather than as an acronym—LASER.

Starting from the invention of LASER in the early 1960s, laser radiation propagation in the atmosphere has been the subject of intensive research. The high spatial and time coherence of laser sources makes their application attractive for communication, location, geodesy, and high-energy transmission over long distances. Laser sources are widely used for exploring the atmosphere, in particular, its gas composition and pollution, velocities of air and sea flows, and features of the land and sea surface.