A brief history of laser weapons (pictures)

To those who grew up in the 20th century, few things would have seemed as 21st-century as laser weapons. Surely we'd have ray guns in that not-quite-so-distant future! Yet here we are in the second decade of the 21st century already, and laser weapons remain ever so futuristic.

Yet tomorrow is creeping closer, if ever so slowly, toward that vision of laser weapons for land, sea, and air. In this slideshow, we'll take a look at what's been accomplished so far by the U.S. military-industrial complex, what's coming next, and what never really got off the drawing board.

Of the several military branches, the U.S. Navy may be the best positioned at the moment to field an actual laser weapon. What you see here is the proof-of-concept Maritime Laser Demonstrator, designed and built by Northrop Grumman at the behest of the Office of Naval Research. This solid-state laser system successfully scorched a small boat in tests in early 2011, and now the Navy is seeking proposals to build new prototypes; those proposals are due in mid-October.

“We are in the process of developing a laser weapon prototype for the naval surface fleet to counter small unmanned aerial vehicles and small-boat threats,” Chief of Naval Research Rear Adm. Matthew Klunder said in a statement in August.

This is one of the remotely piloted, unmanned small boats that served as a moving target for the firing of the Maritime Laser Demonstrator in early 2011, toward the end of open ocean testing that ran from October 2010 to April 2011. Here, the laser has started a fire in one of the boat's engines. (Click here for video of the test.)

Over three days at sea during that particular demonstration, the laser was operated at high power more than 35 times and "withstood the stresses" of waves in excess of seven feet high, according to Northrop Grumman. The Maritime Laser Demonstrator, installed on a decommissioned Spruance-class destroyer, the USS Paul Foster, also was the first laser system to be integrated with a ship's radar and navigation systems.

"The results show that all critical technologies for an operational laser weapon system are mature enough to begin a formal weapon system development program," Steve Hixson, vice president, space and directed energy systems at Northrop Grumman's Aerospace Systems sector, said in a statement. "Solid-state laser weapons are ready to transition to the fleet."

Another laser project under way at Northrop Grumman is the Firestrike. Earlier this year in its Redondo Beach, Calif., laboratory, the defense contractor lit up a Firestrike demonstrator laser called Gamma to show what a laser weapon could do to the skin and critical components of a cruise missile that might threaten U.S. Navy ships. (Or in this test case, to the skin and components of a surplus drone standing in for a cruise missile.) The pair of photos above show the damage done.

The 13.3-kilowatt Gamma laser was tested at a beam quality of 1.4, exceeding the design goal of 1.5. (Perfection in laser beams merits a 1.)

One of the goals of the Firestrike program is to put a solid-state laser in a smaller package. The Gamma demonstrator, seen here, weighs 500 pounds and measures 23 inches by 40 inches by 12 inches -- "about the size of two countertop microwave ovens," as Northrop Grumman described it -- which means it met the design goals for size and weight reduction. Gamma's "gain medium" (the source of atoms that emit light) is a tiny slab about the size of a microscope slide, so it falls into the category of "slab laser."

In the grand vision of directed-energy weapons, high-powered laser systems would create a virtual shield against all manner of projectiles -- missiles (cruise and shoulder-fired), rockets, artillery shells, mortars -- as well as unmanned aircraft. This artist's rendering dated circa 2006 from (once again) Northrop Grumman shows how the defense contractor envisioned a system called Skyguard defending a seaside airport. The company said at the time that Skyguard's shield would have a five-kilometer radius (20 kilometers against shoulder-fired missiles); bear in mind, though, that news reports pegged the cost at tens of millions of dollars. Ambitions for laser weapons have been scaled back considerably since then.

The ground-based Skyguard was derived from the Tactical High Energy Laser (THEL) system that Northrop Grumman developed for the U.S. Space and Missile Defense Command and for Israel's defense ministry. The THEL Testbed, developed in the late 1990s, was in residency at the Army's White Sands Missile Range in New Mexico.

At the core of the THEL system -- its beam generator -- was a deuterium fluoride chemical laser, which was yoked to a fire control radar and a target acquisition/tracking system; seen here is the beam director assembly. Northrop Grumman says that in field tests between 2000 and 2005, THEL destroyed a total of 46 rockets, artillery shells, and mortar rounds in flight; the tally breaks down this way -- 28 Katyusha rockets (including salvos and a surprise attack), 5 artillery projectiles, 3 large-caliber rockets, 10 mortars (including a salvo of three), and 10 light, medium, and heavy rockets.

Here's the vision, from about a decade ago, for how a THEL system would detect and engage its targets....

...and here's the reality of a rocket being destroyed in the air in a THEL test.

But despite the test site achievements of the THEL system, chemical lasers have lost their luster because of their cost and complexity. Now THEL's beam control system and command and control system are being combined with the Pentagon's Joint High Power Solid State Laser (JHPSSL) in a new Solid State Laser Testbed Experiment for the U.S. Army.

In March 2009, under the JHPSSL program, Northrop Grumman said it had coaxed a solid-state laser past the 100KW mark -- a record for an electric laser. It got there by combining seven laser chains, each producing about 15KW of power, to produce a single beam of 105.5KW. Note that the 100KW level is generally considered the threshold for "weapons-grade" lasers.

At that time, the seven-chain JHPSSL laser demonstrator ran for more than five minutes, with beam quality of better than 3.0. As of December 2010, the system had logged more than six hours of operating time at power levels greater than 100KW.

Hopes for a chemical-based laser weapon arguably hit their high point with this tricked-out 747, the U.S. Air Force's YAL-1A Airborne Laser Test Bed aircraft. Here you see it on its final flight in February 2012, which is another way of saying that this project is now defunct.

The plan with the Airborne Laser was to catch ballistic missiles in their launch phase, when they're most vulnerable. The ABL, equipped with a "megawatt-class" laser, would fire from that bulbous nose to heat up the side of the missile, weakening it enough to knock it out of commission long before it could reach targets in the U.S. At one point, the Pentagon thought it would build as many as seven ABL aircraft, but in 2009, Defense Secretary Robert Gates put the kibosh on plans to build a second plane and consigned YAL-1A to a humbler fate as nothing more than an R&D effort.

The Airborne Laser did find some success on various test ranges on several occasions in 2010 and 2011. For instance, in February 2010, the aircraft took aim at a short-range "threat representative" liquid-fueled ballistic missile fired at sea, and within two minutes of the launch, while the missile's rocket motors were still firing, the ABL's chemical-fueled laser weapon had heated a pressurized segment of the missile to "critical structural failure," according to the U.S. Missile Defense Agency.

The image sequence here shows the infrared trail of the target missile breaking up in flight as it was zapped.

"With this successful experiment, the Airborne Laser Testbed has blazed a path for a new generation of high-energy, ultra-precision weaponry," Michael Rinn, vice president and ALTB program director at Boeing, said in a statement. "ALTB technology and future directed-energy platforms will transform how the United States defends itself and its friends and allies. Having the capability to precisely project force, in a measured way, at the speed of light, will save lives."

A Missile Defense Agency press release from June 2004 described this as the "wall of fire" of the ABL's "missile-killing" high energy laser. It's part of the 3-ton Beam Transfer Assembly, an array of optics and sensors seen here during testing, that was installed in the aircraft that month.

Where the 747-centric Airborne Laser was built to go after ballistic missiles in the air, Boeing's more modestly proportioned Advanced Tactical Laser aircraft -- a modified C-130 -- was designed to home in on ground targets. The ATL also was equipped with a chemical laser, but the business end of the weapon was that ball turret on the underside of the fuselage.

In September 2009, the Advanced Tactical Laser hit a moving vehicle on the ground, burning a hole in the fender. Boeing didn't offer specifics on the type of vehicle, other than to say it was remote-controlled, or how fast it was moving, nor did it give the airspeed or altitude for the aircraft.

A few weeks earlier, the ATL had made a laser strike on a stationary ground target. As Boeing described the results, "the laser beam's energy defeated the vehicle." By "defeated," Boeing meant that the target was made temporarily or permanently unavailable for its intended use.

Ultimately, the Pentagon would like to cook up a much smaller laser weapons array -- just one-tenth the size and weight of existing lasers packing comparable power -- for tactical aircraft that would target threats on the ground. Enter DARPA's High Energy Liquid Laser Defense System (HELLADS) program, the goal of which is to develop a 150KW laser weapon that has a volume of 3 cubic meters for the system and a weight of no more than 5 kilograms per kilowatt (which, at 150KW, means a weight below 1,650 pounds). In June 2011, DARPA said it was looking to have the 150KW system, featuring twinned laser modules, completed by the end of 2012 and transported to the White Sands Missile Range in New Mexico in early 2013 for ground-testing against rockets, mortars, and surface-to-air missiles, and for simulations of air-to-ground targeting.

In July 2011, Predator drone maker General Atomics won the contract from DARPA to build the Demonstrator Laser Weapon System (DLWS) for HELLADS. General Atomics says it is pursuing a "new approach to electric lasers" that joins "the high storage density of solid-state with the efficient heat removal of flowing liquids."

Following the ground testing of the DLWS in 2013, the laser demonstrator looks likely to be integrated onto a B-1B Lancer aircraft. (See DARPA's illustration of that above.)

The year 2009 was a busy time for pronouncements of progress with laser weapons. Here, in May of that year, a small UAV gets zapped by a high-energy laser beam in Boeing's Matrix (Mobile Active Targeting Resource for Integrated eXperiments) project; all told, five UAVs were tracked and shot down at various ranges, Boeing said. Matrix was a trailer-mounted "test bed" that Boeing developed for the U.S. Air Force Research Laboratory.

At the same time as that series of Matrix tests in 2009, the separate, Boeing-funded Laser Avenger also shot down a UAV. The Humvee-mounted Laser Avenger was derived from the existing Avenger platform, which typically carries more traditional "kinetic" weapons, including Stinger antiaircraft missiles and a .50-caliber machine gun. On this test occasion in 2009, Boeing also test-fired a 25mm machine gun from the Laser Avenger platform -- the notion being, apparently, that if you can't hit the target one way, there's always backup.

In 2007, an earlier version of Laser Avenger showed off its prowess -- in tests -- at neutralizing IEDs and unexploded ordnance on the ground.

Here's yet another laser weapons project that Boeing has put its hand to -- the U.S. Army's High Energy Laser Technology Demonstrator (HEL TD). This one features a bigger ground vehicle, the 8-wheeled, 500-horsepower Heavy Expanded Mobility Tactical Truck (HEMTT), topped off by a beam control system. Boeing said in June 2011 that system integration had been completed, and at the time it was looking forward to low-power tests in the fourth quarter of that year.

The Boeing HEL TD is more than just a sketch on paper. But will it keep on trucking? Apparently so. After a long silence on the project, Boeing announced on October 3, 2012, that it will continue the development effort for the U.S. Army Space and Missile Defense Command. The next step under the follow-on contract, which will cover development and testing for the next three years, will be to incorporate a 10KW solid-state laser with the HEL TD system. Field tests will take place during the coming year to "demonstrate the system's ability to acquire, track, damage, and defeat threat-representative targets."

Now we turn our attention to yet another defense contractor, Raytheon, which has its own directed-energy ambitions. In July 2010, the U.S. Navy used Raytheon's Laser Area Weapon System -- which features a solid-state laser -- to shoot down four UAVs in a test that joined it with a Phalanx Close-in Weapon System.

A related system developed by Raytheon is the Laser Centurion Demonstrator, which hypothetically could replace the 20mm cannon of the Phalanx weapons system, an air defense platform that's commonplace on Navy vessels -- and that's known as Centurion when it's adapted for ground use by the Army. Here, the LCD is being shown off at the White Sands Missile Range in early 2009.

This is a different kind of laser weapon -- a nonlethal one. The Green Laser Escalation of Force (GLEF) system is meant to dazzle rather than inflict injury, making it hard for a combatant to aim a weapon or for a civilian to inadvertently wander too close to a checkpoint where deadly force might be employed. The U.S. Army sent GLEF kits to Afghanistan for evaluation in 2010. Similar systems had earlier been used in the war in Iraq.

This, too, was a laser weapon for dazzling, but it seems to have quickly turned into a dead end. It's the Personnel Halting and Stimulation Response (PHaSR) system -- yes, besides having the look of a prop for a TV sci-fi show, it even belabored a "Star Trek" reference. According to an Air Force Research Laboratory fact sheet from 2006, it used two low-power diode-pumped lasers, one with a visible wavelength and one with a mid-infrared wavelength. The prototype hasn't been heard from since.

Now we come to the trippiest laser weapons technologies that the U.S. Army has been scoping out -- the laser-induced plasma channel. In this mind-boggling scenario, the laser beam itself isn't the knock-out punch, if we understand this esoteric tech correctly. Rather, it's the conduit for, essentially, lightning bolts. R&D types at the Army's Picatinny Arsenal in New Jersey were putting the technology to the test earlier this year.

"If a laser beam is intense enough, its electro-magnetic field is strong enough to rip electrons off of air molecules, creating plasma," George Fischer, lead scientist for the project, said in a story by Picatinny's public affairs staff. "This plasma is located along the path of the laser beam, so we can direct it wherever we want by moving a mirror."

Where you might want to direct it is at, say, an enemy vehicle or an unexploded artillery shell.

What the U.S. Navy really wants is a free electron laser -- so much so that its contract with Boeing for a 100-kilowatt FEL lab demonstrator could be worth up to $163 million eventually.

In a FEL system (video), laser light is generated by sending high-energy electrons through a series of magnetic fields, and the resulting beam could be immensely powerful. And an important distinguishing characteristic is the ability to tune the beam to different wavelengths, which could help it better deal with the vagaries of the atmosphere at sea.

But right now, FEL systems are huge and inefficient, and practical systems are a long, long ways off. A report issued last spring by the Center for Strategic and Budgetary Assessments, a Washington, D.C., think tank, said that it might not be until "the late 2020s" that we see ship-based FELs "with power outputs sufficient to interdict more hardened targets, including ballistic-missile reentry vehicles."