Directed-energy weapons systems could provide efficient, cost-effective countermeasures in an age of drones and other airborne threats. Recent scientific and engineering breakthroughs are bringing these systems closer to deployment.
Long before George Lucas conceived of the Death Star with its super laser focused on Alderaan, even before H.G. Wells wrote War of the Worlds with its hostile aliens and their heat-ray weapon, the Greek inventor Archimedes concocted his own heat ray composed of mirrors to concentrate sunlight and ignite the sails of invading Roman ships. The invention of the first working laser in 1960 further inspired militaries around the world to research and develop high-energy lasers (HELs) for the protection of their troops. While the quest has taken decades, the year 2014 alone has seen numerous milestones come to pass.
In the United States, lasers receive more R&D funding than other directed-energy weapons because they are the most promising for lightweight, effective, low-cost operation. Specifically, energy from HELs can be delivered at the speed of light, unlike the supersonic or subsonic speeds of conventional missiles. Another factor driving the development of HEL weapons is their low shot-to-shot operational cost. Whereas it may cost millions to develop laser weapons, their cost per firing is orders of magnitude lower than that of conventional ballistics and projectiles.
The concept of pointing a powerful laser at a target to vaporize it is a simplistic take on what is actually required to create an operational HEL weapon. The biggest challenge for researchers is creating a laser that can reach high enough powers to partially destroy or defeat a target while tracking numerous objects simultaneously. In turbulent atmospheric conditions, like dust and humidity, the laser must propagate efficiently and stay accurately focused on the target. The system must compensate for the movement of the target, the motion of the platform and the distortion of the beam from weather or environmental conditions. The platform must be compact enough to fit on a vehicle or even a soldier’s shoulder, while the optics must be ruggedized to withstand shock and high irradiance. In addition to these requirements for size, weight and power (SWaP), they must be safer to use than chemical-based high-energy lasers.