Laser guns have long been a staple of science fiction. Now Chinese researchers claim to have developed a portable laser rifle. It sounds truly horrific; it does not kill, but can set fire to clothes and skin from considerable distance and weighs about the same as most assault rifles.
According to international studies scholar Jason Ellis, writing for the Center for a New American Security, the U.S. and most other large militaries have been trying to develop laser weapons for decades. The U.S. military has invested vast sums of money in researching development of High Energy Lasers (HEL) and various other Directed Energy (DE) weapons. Lasers are already used for guidance and communication. But a laser capable of actually destroying a distant target would require a power output in the multi-megawatt range, and nothing has been developed so far that could do that, let alone do so repeatedly.
“Laser” stands for “Light amplification by stimulated emission of radiation;” a laser beam is an extremely focused beam of energy. But light tends to spread out, or diffract, as the distance from its source increases. The rate of diffraction is determined by how narrow the beam is as well as its wavelength, but maintaining the tight focus over a long distance requires a lot of power. And a lot of power requires a large infrastructure to generate it.
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Certain lower energy lasers, however, have defensive potential. To destroy a drone, small boat, or incoming artillery shells only requires output in the 10 to low-100s of kilowatts (by contrast, a surgical laser produces 10s of watts and operates at very short distances), a much more manageable target. Indeed, the Navy successfully tested such a device for defense against a “swarm” of small boats or drones, a low-tech tactic an adversary might use to destroy a warship. The laser should be cheaper than conventional weapons (guided missiles are costly) and capable of defending against large numbers of targets since in theory it does not require ammunition. As of 2015, no such weapons has actually been deployed, but the proof of concept is there.
That iteration of a laser weapon requires a huge device mounted on a ship. The military has also developed other forms of antipersonnel DE weapons for crowd control, or to keep enemy soldiers out of particular areas. Additionally, there have been experiments with microwaves and directed Electromagnetic Pulse weapons designed to disrupt or destroy electronics. The smallest of these is mounted on an enormous truck.
Something weighing as little as seven pounds, as China has claimed to have created, still seems far-fetched to many experts in the field.