This Mobile High-Energy Laser-equipped Stryker was evaluated April 12 during the 2017 Maneuver Fires Integrated Experiment at Fort Sill, Okla. The MEHEL can shoot a drone out of the sky using a 5kW laser. (U.S. Army photo by C. Todd Lopez)

A lot of people think that high-energy lasers, or HELs, can't penetrate fog, rain and dust, said Thomas Webber, director of the Directed Energy Division's Technical Center, U.S. Army Space and Missile Defense Command. That's just plain wrong.

The key to making HELs work in poor atmospheric conditions is something called "adaptive optics," he said, adding that the Army is continuing to make more and more improvements on its adaptive optics system to give a greater range of compensation for degraded conditions. Besides the optics, an effective beam control system is used, which forms one beam from multiple lasers to pinpoint exactly where the peak energy should be focused, he said, adding that it operates in conjunction with the optics system.

Webber outlined some advantages HELs have over conventional weapons. HELs are low-cost, the main expense being the diesel used to power the generators, he said. They're also faster than conventional weapons. The HELs have rapid engagement, which means that once the target is acquired and engaged "it's not getting away from you because the instant fired, it will make contact with it at the speed of light. It doesn't get any faster than that."

Precision of the energy is another key component, meaning HEL can be focused at the most vulnerable point of the target where it will do the most damage thanks to the advanced optics and speed at which a laser travels. In fact, the optics on the HEL are so advanced that a battlefield commander can use them for multiple applications with regards to intelligence, surveillance and reconnaissance. "It's the best ISR capability they'll ever have access to," Webber said.

HEL has "a deep magazine," he said, implying that it doesn't run out of bullets or jam like conventional weapons sometimes do. Another advantage is that HELs don't broadcast a visible signature because the laser beam is invisible to the human eye, despite artist renderings of lasers firing brightly colored beams, he said.

Finally, he said HELs give commanders graduated degrees of engagement. What that means is the HELs can be dialed up to destroy rockets, mortar and artillery fire, as well as unmanned systems, or the power can be dialed down low enough to disable targets as "soft" as an AK-47 rifle.

Getting to this point in time required about 10 years of development, testing and lots of trial and error, Webber said. The reason development has seemed like a long time coming, is that although "we want to get this capability to the field as quickly as we can, we also want to work this in an engineering mindset. We want to get it right and demonstrate the capability and be informed as we move forward," he said.

When the Army was looking for a laser, instead of inventing one, it turned to the private sector, which had been using them for some time in the welding industry. The next step was to develop a thermal management system to address all of the radiant heat that HELs give off, then develop a beam control system that could point at and track moving objects. Also, a power management system was developed that provided HEL with a refresh rate that allowed power to recycle fast enough to fire multiple bursts. All of that, along with generators, batteries and laser components was pretty massive, so the Army decided to place it all on one of its bigger trucks, the Heavy Expanded Mobility Tactical Truck, or HEMTT, which allowed the team to demonstrate capabilities with a 10-kW HEL three years ago.

This fiscal year, a 60-kW HEL-on-a-HEMTT will inform milestone decisions and in FY19, another demonstration will lead to proof of concept. The next step, Webber said, is to put a 100-kW HEL on a Family of Medium Tactical Vehicles, with the goal of making it a program of record.